WO2024257762A1 - Feuille optique, article en feuille, plaque de polarisation, élément de panneau tactile, dispositif d'affichage, procédé de sélection de feuille optique et procédé de fabrication de feuille optique - Google Patents

Feuille optique, article en feuille, plaque de polarisation, élément de panneau tactile, dispositif d'affichage, procédé de sélection de feuille optique et procédé de fabrication de feuille optique Download PDF

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Publication number
WO2024257762A1
WO2024257762A1 PCT/JP2024/021192 JP2024021192W WO2024257762A1 WO 2024257762 A1 WO2024257762 A1 WO 2024257762A1 JP 2024021192 W JP2024021192 W JP 2024021192W WO 2024257762 A1 WO2024257762 A1 WO 2024257762A1
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WIPO (PCT)
Prior art keywords
layer
optical sheet
less
wavelength
spectral transmittance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2024/021192
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English (en)
Japanese (ja)
Inventor
健 吉中
史哲 岡崎
祐太 新庄
裕介 橋本
賢一 塚田
治 渡邉
恵実子 加藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dai Nippon Printing Co Ltd
Original Assignee
Dai Nippon Printing Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Dai Nippon Printing Co Ltd filed Critical Dai Nippon Printing Co Ltd
Priority to JP2025527939A priority Critical patent/JPWO2024257762A1/ja
Priority to CN202480037265.0A priority patent/CN121241283A/zh
Priority to KR1020257041433A priority patent/KR20260022316A/ko
Publication of WO2024257762A1 publication Critical patent/WO2024257762A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
    • B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B23/08—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/042—Coating with two or more layers, where at least one layer of a composition contains a polymer binder
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/046—Forming abrasion-resistant coatings; Forming surface-hardening coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/80—Constructional details
    • H10K50/86—Arrangements for improving contrast, e.g. preventing reflection of ambient light
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/10—OLED displays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays

Definitions

  • This disclosure relates to optical sheets, sheet articles, polarizing plates, touch panel members, display devices, methods for selecting optical sheets, and methods for manufacturing optical sheets.
  • Patent Document 1 and Patent Document 2 disclose an optical sheet including a functional layer.
  • the functional layer includes a cured product of an ultraviolet-curable resin composition.
  • the functional layer functions as a so-called hard coat layer.
  • the functional layer imparts high hardness to the surface of the optical sheet.
  • the optical sheet including the functional layer can be incorporated into various display devices. By using an optical sheet including a functional layer, the occurrence of scratches due to rubbing can be suppressed.
  • the functional layer is further provided with a blue light blocking function.
  • Blue light can increase the burden and fatigue of the viewer, such as eye strain. Blue light can deteriorate the polarizers in liquid crystal display panels and the EL elements in organic EL display panels.
  • the functional layer described in Patent Document 1 contains a yellow pigment.
  • the yellow pigment can absorb some blue light.
  • the yellow pigment cannot provide the optical sheet with sufficient blue-cutting functionality.
  • an optical sheet containing a yellow pigment changes the color of an image observed through the light.
  • the functional layer described in Patent Document 2 contains an ultraviolet absorbing agent.
  • the ultraviolet absorbing agent can absorb blue light.
  • the functional layer described in Patent Document 2 blocks light of about 410 nm as blue light. Therefore, problems caused by blue light can be suppressed.
  • an ultraviolet absorbing agent that exhibits blue light blocking function is contained in an ultraviolet curable resin composition.
  • the ultraviolet absorbing agent can absorb ultraviolet light when a coating film of the curable resin composition is exposed to ultraviolet light. Therefore, ultraviolet irradiation of the coating film is inhibited, and the functional layer does not cure sufficiently.
  • Patent Document 1 JP6641105B
  • Patent Document 2 JP6696562B
  • the present disclosure aims to improve the hardness of an optical sheet that includes a layer containing a cured product of a curable resin composition and an ultraviolet absorber.
  • the optical sheet according to the first embodiment of the present disclosure is An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface,
  • the functional layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the spectral transmittance at a wavelength of 380 nm is 1% or less
  • the spectral transmittance at a wavelength of 440 nm is 70% or more
  • An indentation hardness HA1 at a first position on the cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer satisfy the following relationship: HA3 ⁇ HA2 ⁇ HA1 HA1/HA2 ⁇ HA2/HA3 the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface
  • the sheet article according to the first embodiment of the present disclosure includes a plurality of optical sheets according to the first embodiment of the present disclosure.
  • the polarizing plate according to the first embodiment of the present disclosure is An optical sheet according to a first embodiment of the present disclosure; and a polarizer superimposed on the optical sheet.
  • the touch panel member according to the first embodiment of the present disclosure includes: An optical sheet according to a first embodiment of the present disclosure; and an electrode layer overlaid on the optical sheet.
  • the display device includes: An optical sheet according to a first embodiment of the present disclosure; and a display element superimposed on the optical sheet.
  • the method for selecting an optical sheet according to the first embodiment of the present disclosure includes: An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface,
  • the functional layer includes a cured product of a curable resin composition and an ultraviolet absorber, Measuring a spectral transmittance at a wavelength of 380 nm and a spectral transmittance at a wavelength of 440 nm; Measuring an indentation hardness HA1 at a first position on a cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer; selecting an optical sheet based on the measured spectral transmittance and the measured indentation hardness; the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface portion close
  • a method for producing a first optical sheet according to a first embodiment of the present disclosure includes: An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface, A step of preparing an optical sheet, the functional layer including a cured product of a curable resin composition and an ultraviolet absorber; selecting an optical sheet based on a spectral transmittance at a wavelength of 380 nm, a spectral transmittance at a wavelength of 440 nm, an indentation hardness HA1 at a first position on a cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer; the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface portion close to the second surface in the cross section, A method for manufacturing an optical
  • the method for producing the second optical sheet according to the first embodiment of the present disclosure includes: A step of applying a first curable resin composition containing an ultraviolet absorber onto a substrate film; A step of curing a coating film of a first curable resin composition to produce a first portion on the base film; applying a second curable resin composition onto the first portion; and curing the coating of the second curable resin composition to produce a second part bonded to the first part.
  • the optical sheet according to the second embodiment of the present disclosure is A first layer and a second layer adjacent to the first layer,
  • the first layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the thickness ratio is 1.5 or more and 7.5 or less, the thickness ratio is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer;
  • the spectral transmittance at a wavelength of 410 nm is 15% or less,
  • the spectral transmittance at a wavelength of 440 nm is 70% or more.
  • the sheet article according to the second embodiment of the present disclosure includes a plurality of optical sheets according to the second embodiment of the present disclosure.
  • the polarizing plate according to the second embodiment of the present disclosure is An optical sheet according to a second embodiment of the present disclosure; and a polarizer superimposed on the optical sheet.
  • the touch panel member according to the second embodiment of the present disclosure includes: An optical sheet according to a second embodiment of the present disclosure; and an electrode layer overlaid on the optical sheet.
  • the display device includes: An optical sheet according to a second embodiment of the present disclosure; and a display element superimposed on the optical sheet.
  • a method for selecting an optical sheet according to a second embodiment of the present disclosure includes: A first layer and a second layer adjacent to the first layer,
  • the first layer includes a cured product of a curable resin composition and an ultraviolet absorber, measuring a thickness ratio, which is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer; Measuring the spectral transmittance at a wavelength of 410 nm; Measuring the spectral transmittance at a wavelength of 440 nm; selecting an optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 410 nm, and the spectral transmittance at a wavelength of 440 nm.
  • a method for producing a first optical sheet according to a second embodiment of the present disclosure includes: A first layer and a second layer adjacent to the first layer, preparing an optical sheet, the first layer including a cured product of a curable resin composition and an ultraviolet absorber; selecting an optical sheet based on a thickness ratio, which is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer, a spectral transmittance at a wavelength of 410 nm, and a spectral transmittance at a wavelength of 440 nm.
  • a method for producing a second optical sheet according to a second embodiment of the present disclosure includes: A step of applying a first curable resin composition containing an ultraviolet absorber onto a substrate film; A step of forming a first portion on the substrate film by curing a coating film of a first curable resin composition; applying a second curable resin composition onto the first portion; and curing the coating of the second curable resin composition to produce a second part bonded to the first part.
  • the optical sheet according to the third embodiment of the present disclosure is A first layer and a second layer adjacent to the first layer,
  • the first layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the thickness ratio is 1.2 or more and 7.5 or less, the thickness ratio is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer;
  • the spectral transmittance at a wavelength of 380 nm is less than 1%,
  • the spectral transmittance at a wavelength of 440 nm is 70% or more,
  • the slope of the spectral transmittance at each wavelength at intervals of 0.5 nm within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less,
  • the slope (%/nm) of the spectral transmittance at wavelength X is the value obtained by subtracting the spectral transmittance (%) at wavelength
  • the sheet article according to the third embodiment of the present disclosure includes a plurality of optical sheets according to the third embodiment of the present disclosure.
  • the polarizing plate according to the third embodiment of the present disclosure is An optical sheet according to a third embodiment of the present disclosure; and a polarizer superimposed on the optical sheet.
  • the touch panel member according to the third embodiment of the present disclosure includes: An optical sheet according to a third embodiment of the present disclosure; and an electrode layer overlaid on the optical sheet.
  • a display device includes: An optical sheet according to a third embodiment of the present disclosure; and a display element superimposed on the optical sheet.
  • a method for selecting an optical sheet according to a third embodiment of the present disclosure includes: A first layer and a second layer adjacent to the first layer, The first layer includes a cured product of a curable resin composition and an ultraviolet absorber, measuring a thickness ratio, which is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer; measuring the spectral transmittance at each wavelength in 0.5 nm intervals within a wavelength range of 379.5 nm or more and 440.5 nm or less; selecting an optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 380 nm, the spectral transmittance at a wavelength of 440 nm, and a slope of the spectral transmittance at wavelengths every 0.5 nm within a wavelength range of 380 nm or more and 440 nm or less;
  • the slope (%/nm) of the spectral transmittance at wavelength X is the value obtained by subtracting the spectral transmitt
  • a method for producing a first optical sheet according to a third embodiment of the present disclosure includes: A first layer and a second layer adjacent to the first layer, preparing an optical sheet, the first layer including a cured product of a curable resin composition and an ultraviolet absorber; selecting an optical sheet based on a thickness ratio, which is a ratio of a thickness ( ⁇ m) of the first layer to a thickness ( ⁇ m) of the second layer, a spectral transmittance at a wavelength of 380 nm, a spectral transmittance at a wavelength of 440 nm, and a slope of the spectral transmittance at each wavelength at intervals of 0.5 nm within a wavelength range of 380 nm to 440 nm,
  • the slope (%/nm) of the spectral transmittance at wavelength X is the value obtained by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral transmittance (%) at wavelength X+0.5 (nm).
  • a method for producing a second optical sheet according to a third embodiment of the present disclosure includes: A step of applying a first curable resin composition containing an ultraviolet absorber onto a substrate film; A step of forming a first portion on the substrate film by curing a coating film of a first curable resin composition; applying a second curable resin composition onto the first portion; and curing the coating of the second curable resin composition to produce a second part bonded to the first part.
  • the hardness can be improved in an optical sheet including a layer containing a cured product of a curable resin composition and an ultraviolet absorber.
  • FIG. 1 is a diagram for explaining the first embodiment, and is a cross-sectional view showing an example of an optical sheet.
  • FIG. 2A is an enlarged view of FIG. 1, illustrating the measurement positions of the indentation hardness.
  • FIG. 2B is a graph showing an example of a load-displacement curve obtained by the nanoindentation method.
  • FIG. 3 is a perspective view showing an example of a sheet article including an optical sheet.
  • FIG. 4 is a cross-sectional view showing an example of a polarizing plate including the optical sheet shown in FIG.
  • FIG. 5 is a cross-sectional view showing an example of a touch panel member including the optical sheet shown in FIG.
  • FIG. 6 is a cross-sectional view showing an example of a display device including the optical sheet shown in FIG.
  • FIG. 1 is a diagram for explaining the first embodiment, and is a cross-sectional view showing an example of an optical sheet.
  • FIG. 2A is an enlarged view of FIG. 1, illustrating the measurement positions
  • FIG. 7 is a graph showing an example of the spectral transmittance and the slope of the spectral transmittance of an optical sheet.
  • FIG. 8 is a diagram for explaining the second embodiment, and is a cross-sectional view showing an example of an optical sheet.
  • FIG. 9 is a diagram for explaining the third embodiment, and is a cross-sectional view showing an example of an optical sheet.
  • FIG. 10 is a graph showing another example of the spectral transmittance and the slope of the spectral transmittance of the optical sheet.
  • the first to third embodiments of this disclosure relate to the following [1] to [75].
  • An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface,
  • the functional layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the spectral transmittance at a wavelength of 380 nm is 1% or less
  • the spectral transmittance at a wavelength of 440 nm is 70% or more
  • An indentation hardness HA1 at a first position on the cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer satisfy the following relationship: HA3 ⁇ HA2 ⁇ HA1 HA1/HA2 ⁇ HA2/HA3 the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface portion close to the second surface in the cross section, The second
  • An intermediate layer is provided between the functional layer and the base material layer, an indentation hardness HB of the intermediate layer at a cross section is smaller than an indentation hardness HC of the base layer at a cross section;
  • the optical sheet according to any one of [1] to [10], wherein the intermediate layer has a thickness of 4.2 ⁇ m or less.
  • An intermediate layer is provided between the functional layer and the base material layer,
  • the optical sheet according to any one of [1] to [11], wherein the indentation hardness HB of the cross section of the intermediate layer is 120 MPa or more.
  • the slope of the spectral transmittance at each wavelength at intervals of 0.5 nm within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less
  • the slope (%/nm) of the spectral transmittance at wavelength X is a value obtained by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral transmittance (%) at wavelength X+0.5 (nm).
  • the a * value of the L * a * b * color system measured by transmitted light is -3.0 or more and -1.6 or less;
  • the optical sheet according to any one of [1] to [18], wherein the b * value of the L * a * b * color system measured by transmitted light is 3.5 or more and 6.0 or less.
  • a first layer and a second layer adjacent to the first layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the thickness ratio is 1.5 or more and 7.5 or less, the thickness ratio is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer;
  • the spectral transmittance at a wavelength of 410 nm is 15% or less,
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [28] to [31], wherein the ratio of silicon element to carbon element measured on the first surface by X-ray photoelectron spectroscopy is 0.02 or more.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [28] to [32], wherein the ratio of elemental fluorine on the first surface measured by X-ray photoelectron spectroscopy is 0.1% or less.
  • the a * value of the L * a * b * color system measured by transmitted light is -3.0 or more and -1.6 or less;
  • the optical sheet according to any one of [28] to [33], wherein the b * value of the L * a * b * color system measured by transmitted light is 3.5 or more and 6.0 or less.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface; [28] to [42], wherein the pencil hardness of the first surface is 2H or more as measured in accordance with JIS K 5600-5-4:1999 at a load of 500 g and a speed of 1.4 mm/sec.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [28] to [43], wherein the load capacity of the first surface in a steel wool scratch resistance test under the following conditions is 200 g or more.
  • a first layer and a second layer adjacent to the first layer includes a cured product of a curable resin composition and an ultraviolet absorber,
  • the thickness ratio is 1.2 or more and 7.5 or less, the thickness ratio is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer;
  • the spectral transmittance at a wavelength of 380 nm is less than 1%,
  • the spectral transmittance at a wavelength of 440 nm is 70% or more,
  • the slope of the spectral transmittance at each wavelength at intervals of 0.5 nm within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less,
  • An optical sheet in which the slope (%/nm) of the spectral transmittance at wavelength X is a value obtained by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [45] to [50], wherein the ratio of silicon element to carbon element measured on the first surface by X-ray photoelectron spectroscopy is 0.02 or more.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [45] to [51], wherein the ratio of elemental fluorine on the first surface measured by X-ray photoelectron spectroscopy is 0.1% or less.
  • the a * value of the L * a * b * color system measured by transmitted light is -3.0 or more and -1.6 or less;
  • the optical sheet according to any one of [45] to [52], wherein the b * value of the L * a * b * color system measured by transmitted light is 3.5 or more and 6.0 or less.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of [45] to [60], wherein the indentation hardness of the first surface at an indentation depth of 100 nm is 330 MPa or more.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface; [45] to [61], wherein the pencil hardness of the first surface is 2H or more as measured in accordance with JIS K 5600-5-4:1999 at a load of 500 g and a speed of 1.4 mm/sec.
  • a first surface and a second surface opposed to the first surface, the first layer and the second layer are disposed in this order from the first surface to the second surface;
  • the optical sheet according to any one of items [45] to [62], wherein the load capacity of the first surface in a steel wool scratch resistance test under the following conditions is 150 g or more.
  • Steel wool scratch resistance test Steel wool #0000 is used and moved back and forth 10 times at a moving speed of 100 mm/sec and a one-way moving distance of 120 mm.
  • a sheet article comprising a plurality of the optical sheets according to any one of [1] to [63].
  • a polarizing plate comprising the optical sheet and a polarizer superimposed thereon.
  • a touch panel member comprising the optical sheet and an electrode layer overlapped therewith.
  • a display device comprising the optical sheet and a display element overlapped therewith.
  • An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface,
  • the functional layer includes a cured product of a curable resin composition and an ultraviolet absorber, Measuring a spectral transmittance at a wavelength of 380 nm and a spectral transmittance at a wavelength of 440 nm; Measuring an indentation hardness HA1 at a first position on a cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer; selecting an optical sheet based on the measured spectral transmittance and the measured indentation hardness; the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface portion close to the second surface in the cross section, The second position is located at a center
  • An optical sheet including a first surface and a second surface opposite to the first surface, a base layer and a functional layer in this order from the second surface to the first surface, A step of preparing an optical sheet, the functional layer including a cured product of a curable resin composition and an ultraviolet absorber; selecting an optical sheet based on a spectral transmittance at a wavelength of 380 nm, a spectral transmittance at a wavelength of 440 nm, an indentation hardness HA1 at a first position on a cross section of the functional layer, an indentation hardness HA2 at a second position on the cross section of the functional layer, and an indentation hardness HA3 at a third position on the cross section of the functional layer; the first position is located in a surface portion close to the first surface in the cross section, the third position is located in a surface portion close to the second surface in the cross section, A method for manufacturing an optical sheet, wherein the second position is located at a center between the first position and the
  • a step of applying a first curable resin composition containing an ultraviolet absorber onto a substrate film A step of forming a first portion on the substrate film by curing a coating film of a first curable resin composition; applying a second curable resin composition onto the first portion; and curing a coating of a second curable resin composition to produce a second portion bonded to the first portion.
  • a first layer and a second layer adjacent to the first layer includes a cured product of a curable resin composition and an ultraviolet absorber, measuring a thickness ratio, which is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer; Measuring the spectral transmittance at a wavelength of 410 nm; Measuring the spectral transmittance at a wavelength of 440 nm; selecting an optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 410 nm, and the spectral transmittance at a wavelength of 440 nm.
  • a first layer and a second layer adjacent to the first layer preparing an optical sheet, the first layer including a cured product of a curable resin composition and an ultraviolet absorber; selecting an optical sheet based on a thickness ratio, which is a ratio of a thickness ( ⁇ m) of the first layer to a thickness ( ⁇ m) of the second layer, a spectral transmittance at a wavelength of 410 nm, and a spectral transmittance at a wavelength of 440 nm.
  • the first layer includes a cured product of a curable resin composition and an ultraviolet absorber, measuring a thickness ratio, which is the ratio of the thickness ( ⁇ m) of the first layer to the thickness ( ⁇ m) of the second layer; measuring the spectral transmittance at each wavelength in 0.5 nm intervals within a wavelength range of 379.5 nm or more and 440.5 nm or less; selecting an optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 380 nm, the spectral transmittance at a wavelength of 440 nm, and a slope of the spectral transmittance at wavelengths every 0.5 nm within a wavelength range of 380 nm or more and 440 nm or less; A method for selecting an optical sheet, wherein the slope (%/nm) of the spectral transmittance at wavelength X is a value obtained by subtracting the spectral transmittance (%) at wavelength X-
  • the numerical range may be formed by combining any one upper limit candidate with any one lower limit candidate.
  • Parameter B may be A1 or more, A2 or more, or A3 or more.
  • Parameter B may be A4 or less, A5 or less, or A6 or less.”
  • the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.
  • FIG. 1 In order to clarify the directional relationships between the drawings, several drawings show a first direction D1, a second direction D2, and a third direction D3 with arrows that have the same symbol.
  • the tip of the arrow is the first side of each direction.
  • the side opposite the tip of the arrow is the second side of each direction.
  • Arrows that point perpendicular to the paper surface and toward the back of the paper surface are shown by a symbol of an x in a circle, as shown in Figure 1, for example.
  • the optical sheet 10 includes a first surface 11 and a second surface 12.
  • the optical sheet 10 includes, in the order from the second surface 12 toward the first surface 11, a base layer 40 and a functional layer 20.
  • the functional layer 20 includes a cured product of a curable resin composition and an ultraviolet absorber.
  • the functional layer 20 including the ultraviolet absorber can provide at least one of an ultraviolet cut function and a blue light cut function to the optical sheet 10.
  • the optical sheet 10 has the following characteristics (X) and (Y) with respect to the spectral transmittance.
  • (X) The spectral transmittance of the optical sheet 10 at a wavelength of 380 nm is 1% or less.
  • (Y) The spectral transmittance of the optical sheet 10 at a wavelength of 440 nm is 70% or more.
  • the optical sheet 10 can adequately block light with a wavelength of around 380 nm. This can reduce problems caused by ultraviolet rays and blue light.
  • the image light emitted from the display device 60 can be transmitted through the optical sheet 10.
  • the optical sheet 10 can block light with a wavelength of about 380 nm from the image light. By sufficiently blocking light with a wavelength of about 380 nm from the image light, it is possible to reduce the burden on the observer of the image, such as eye strain.
  • External light such as sunlight can enter the optical sheet 10.
  • deterioration of the display element 61 can be suppressed.
  • deterioration of the EL element (organic electroluminescence element) of an organic EL panel (organic electroluminescence panel) can be suppressed.
  • deterioration of the polarizer 52 of the polarizing plate 50 can be suppressed.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm may be 1% or less, or may be less than 1%. There is no particular lower limit set for the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm may be 0% or more, or may be greater than 0%.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm may be 0% or more and 1% or less, or 0% or more and less than 1%.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm may be greater than 0% or more and 1% or less, or 0% or more and less than 1%.
  • light with a wavelength of 440 nm or more can pass through the optical sheet 10 with high transmittance.
  • the optical sheet 10 may transmit light with a wavelength of 440 nm or more with high transmittance. This makes it possible to suppress changes and deterioration in the color of an image observed through the optical sheet 10.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 440 nm may be 70% or more, 75% or more, 80% or more, or 85% or more.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 440 nm may be 100% or less, or may be less than 100%.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 440 nm may be 70% or more and 100% or less, 75% or more and 100% or less, 80% or more and 100% or less, or 85% or more and 100% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 440 nm may be 70% or more and less than 100%, 75% or more and less than 100%, 80% or more and less than 100%, or 85% or more and less than 100%.
  • the optical sheet 10 may have the following feature (Z) in addition to the above-mentioned features (X) and (Y).
  • (Z) The slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less.
  • the spectral transmittance of the optical sheet 10 is measured for each wavelength in 0.5 nm intervals within the wavelength range of 379.5 nm to 440.5 nm. The results of the spectral transmittance measurements are used to determine whether or not characteristic (Z) is satisfied. Note that the above-mentioned characteristic (X) is evaluated based on the measured value of the spectral transmittance at a wavelength of 380.0 nm. The above-mentioned characteristic (Y) is evaluated based on the measured value of the spectral transmittance at a wavelength of 440.0 nm.
  • the slope of the spectral transmittance indicates the increase in transmittance (%) per 1 nm of wavelength.
  • the slope of the spectral transmittance at wavelength X is the value obtained by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral transmittance (%) at wavelength X+0.5 (nm).
  • the optical sheet 10 is determined to have characteristic (Z). If the wavelength at which the slope of the spectral transmittance is maximum is 395.5 nm or less, the optical sheet 10 is determined to not have characteristic (Z). If the wavelength at which the slope of the spectral transmittance is maximum is 420.5 or more, the optical sheet 10 is determined to not have characteristic (Z).
  • Characteristic (Z) specifies the manner in which the spectral transmittance increases with increasing wavelength.
  • the slope of the spectral transmittance has the same meaning as the value of the differential equation of the function that represents the spectral transmittance. Therefore, at the wavelength at which the slope of the spectral transmittance is at its maximum value and at wavelengths around that wavelength, the spectral transmittance increases rapidly with increasing wavelength.
  • the wavelength at which the maximum value of the slope of the spectral transmittance defined by characteristic (Z) is obtained may be 405 nm or more, 408 nm or more, 410 nm or more, 412 nm or more, or 415 nm or more.
  • the wavelength at which the maximum value of the slope of the spectral transmittance defined by characteristic (Z) is obtained may be 419 nm or less.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained may be 400 nm or more and 420 nm or less, 405 nm or more and 420 nm or less, 408 nm or more and 420 nm or less, 410 nm or more and 420 nm or less, 412 nm or more and 420 nm or less, or 415 nm or more and 420 nm or less.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained may be 400 nm or more and 419 nm or less, 405 nm or more and 419 nm or less, 408 nm or more and 419 nm or less, 410 nm or more and 419 nm or less, 412 nm or more and 419 nm or less, or 415 nm or more and 419 nm or less.
  • a lower limit may be set for the maximum value of the slope of the spectral transmittance specified in characteristic (Z), i.e., the maximum value of the slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm to 440 nm.
  • the maximum value of the slope of the spectral transmittance specified in characteristic (Z) may be 2.0 (%/nm) or more, 2.5 (%/nm) or more, 3.0 (%/nm) or more, 3.5 (%/nm) or more, or 4.0 (%/nm) or more.
  • An upper limit may be set for the maximum value of the slope of the spectral transmittance defined by characteristic (Z). By setting an upper limit for the maximum value of the spectral transmittance, color changes and deterioration can be suppressed more naturally.
  • the maximum value of the slope of the spectral transmittance defined by characteristic (Z) may be 8.0 (%/nm) or less, 7.0 (%/nm) or less, 6.0 (%/nm) or less, 5.5 (%/nm) or less, or 5.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 8.0 (%/nm) or less, 2.5 (%/nm) or more and 8.0 (%/nm) or less, 3.0 (%/nm) or more and 8.0 (%/nm) or less, 3.5 (%/nm) or more and 8.0 (%/nm) or less, or 4.0 (%/nm) or more and 8.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 7.0 (%/nm) or less, 2.5 (%/nm) or more and 7.0 (%/nm) or less, 3.0 (%/nm) or more and 7.0 (%/nm) or less, 3.5 (%/nm) or more and 7.0 (%/nm) or less, or 4.0 (%/nm) or more and 7.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 6.0 (%/nm) or less, 2.5 (%/nm) or more and 6.0 (%/nm) or less, 3.0 (%/nm) or more and 6.0 (%/nm) or less, 3.5 (%/nm) or more and 6.0 (%/nm) or less, or 4.0 (%/nm) or more and 6.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 5.5 (%/nm) or less, 2.5 (%/nm) or more and 5.5 (%/nm) or less, 3.0 (%/nm) or more and 5.5 (%/nm) or less, 3.5 (%/nm) or more and 5.5 (%/nm) or less, or 4.0 (%/nm) or more and 5.5 (%/nm).
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 5.0 (%/nm) or less, 2.5 (%/nm) or more and 5.0 (%/nm) or less, 3.0 (%/nm) or more and 5.0 (%/nm) or less, 3.5 (%/nm) or more and 5.0 (%/nm) or less, or 4.0 (%/nm) or more and 5.0 (%/nm) or less.
  • FIG. 7 is a graph showing the spectral transmittance and the slope of the spectral transmittance of the optical sheets for sample A1 and sample A2.
  • Sample A1 has feature (Z) in addition to feature (X) and feature (Y).
  • the spectral transmittance (%) may increase monotonically with increasing wavelength.
  • the slope of the spectral transmittance at each wavelength in 0.5 nm intervals within the wavelength range of 380 nm to 440 nm may be greater than 0. According to these examples, color changes and deterioration of the image observed through the optical sheet 10 can be more naturally suppressed.
  • the optical sheet 10 may have the following feature (W) in addition to the feature (X) and the feature (Y).
  • W The spectral transmittance at a wavelength of 410 nm is 15% or less.
  • condition (W) By satisfying condition (W), light with a wavelength of 410 nm or less can be sufficiently blocked. This allows ultraviolet rays and blue light to be blocked more effectively.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be 15% or less, 14% or less, 13% or less, 12% or less, or 10% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be 0% or more, greater than 0%, 2% or more, or 5% or more.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be 0% or more and 15% or less, 0% or more and 14% or less, 0% or more and 13% or less, 0% or more and 12% or less, or 0% or more and 10% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be greater than 0% and 15% or less, greater than 0% and 14% or less, greater than 0% and 13% or less, greater than 0% and 12% or less, or greater than 0% and 10% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be 2% or more and 15% or less, greater than 2% and 14% or less, greater than 2% and 13% or less, greater than 2% and 12% or less, or greater than 2% and 10% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 410 nm may be 5% or more and 15% or less, 5% or more and 14% or less, 5% or more and 13% or less, 5% or more and 12% or less, or 5% or more and 10% or less.
  • Spectral transmittance is the arithmetic mean of five measured values measured in accordance with JIS Z8722:2009.
  • the geometric condition e specified in JIS Z8722:2009 is adopted in measuring spectral transmittance.
  • the five measured values are measured at five measurement positions on the sample of the optical sheet to be evaluated. The five measurement positions are located at least 10 mm apart from each other.
  • the test environment when measuring spectral transmittance is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%.
  • the sample is placed in the test environment for 16 hours before starting the test. Before measuring the spectral transmittance, the light source of the measuring device is turned on for 15 minutes to stabilize the output of the light source.
  • the functional layer 20 further includes a cured product of the curable resin composition.
  • the cured product of the curable resin composition is also referred to as a resin cured product.
  • the resin cured product can impart high hardness to the functional layer 20 and the optical sheet 10.
  • the functional layer 20 functions as a so-called hard coat layer.
  • the optical sheet 10 with improved hardness has excellent scratch resistance. When the optical sheet 10 is in use, scratches on the optical sheet 10 can be suppressed.
  • the optical sheet 10 is also suitable for a touch panel member 55 (see Figure 5) that is expected to come into contact with a finger or a pen during use.
  • the functional layer containing the cured resin is obtained by curing a coating film of a curable resin composition.
  • the coating film can be cured by exposure to light, which promotes a crosslinking reaction. High-energy short-wavelength light is usually used for exposure.
  • the UV absorber added to the curable resin composition can absorb the light used in the curing process of the coating film. In other words, the UV absorber can inhibit the curing process of the curable resin composition.
  • the hardness of the functional layer containing the cured resin is low, scratch resistance may be significantly reduced. If the hardness of the functional layer containing the cured resin is low, the UV absorber may bleed out from the functional layer when the optical sheet is used. If the UV absorber bleeds out, the UV blocking function and blue light blocking function of the optical sheet 10 may also become insufficient.
  • the indentation hardness HA1, the indentation hardness HA2, and the indentation hardness HA3 satisfy the following condition (A) and condition (B).
  • the indentation hardnesses HA1 to HA3 are the indentation hardnesses of the functional layer 20 in the cross section of the optical sheet 10.
  • the cross section of the optical sheet 10 where the indentation hardness is measured is a cross section along the thickness direction of the optical sheet 10.
  • the cross section of the optical sheet 10 where the indentation hardness is measured is a cross section along the first direction D1, which is the stacking direction of the functional layer 20 and the base layer 40.
  • the indentation hardness HA1 is the indentation hardness at a first position 26 in the cross section of the functional layer 20.
  • the first position 26 is located in the surface layer of the functional layer 20 close to the first surface 11 in the cross section of the functional layer 20.
  • the first position 26 is a position shifted 1.2 ⁇ m from the first side surface 21 to the second side surface 22 along the thickness direction of the optical sheet 10, i.e., the normal direction of the optical sheet 10.
  • the indentation hardness at the first position 26 is an indicator of the hardness of the functional layer 20 in the vicinity of the first side surface 21.
  • the first side 21 and the second side 22 are a pair of main surfaces of the functional layer 20.
  • the first side 21 is located on the first side in the first direction D1, which is the normal direction of the functional layer 20.
  • the first side 21 is a surface closer to the first surface 11 in the first direction D1.
  • the first side 21 of the functional layer 20 constitutes the first surface 11 of the optical sheet 10.
  • the second side 22 is located on the second side in the first direction D1.
  • the second side 22 is a surface closer to the second surface 12 in the first direction D1.
  • the indentation hardness HA3 is the indentation hardness at a third position 28 in the cross section of the functional layer 20.
  • the third position 28 is located in the surface layer of the functional layer 20 close to the second surface 12 in the cross section of the functional layer 20.
  • the third position 28 is a position shifted 1.2 ⁇ m from the second side surface 22 to the first side surface 21 along the thickness direction of the optical sheet 10, i.e., the normal direction of the optical sheet 10.
  • the indentation hardness at the third position 28 is an indicator of the hardness of the functional layer 20 in the vicinity of the second side surface 22.
  • the indentation hardness HA2 is the indentation hardness at the second position 27 in the cross section of the functional layer 20.
  • the indentation hardness at the second position 27 is an indicator of the hardness at the center of the thickness direction of the functional layer 20. As shown in FIG. 2A, the second position 27 is located in the center of the first position 26 and the third position 28 along the thickness direction of the optical sheet 10, i.e., the normal direction of the optical sheet 10.
  • Indentation hardness is the hardness measured by the nanoindentation method using a nanoindenter.
  • the nanoindentation method is a method for measuring hardness based on a load-displacement curve.
  • the load-displacement curve is obtained by loading and unloading the evaluation object using an indenter.
  • the load-displacement curve shows the relationship between the indentation load and the indentation depth.
  • the nanoindentation method makes it possible to evaluate the hardness of a microscopic area.
  • a test piece made from the optical sheet to be evaluated is used.
  • a sample is cut out from the optical sheet 10 to be evaluated.
  • This sample is embedded in an embedding resin.
  • the embedding resin is a cold-curing type two-component epoxy hardening resin.
  • the embedding resin is left at room temperature for 24 hours or more to harden, and an embedded sample is produced.
  • the embedded sample is cut with a microtome to expose the cross section of the optical sheet 10 along the first direction D1, which corresponds to the normal direction of the optical sheet.
  • An indenter is pressed into the exposed cross section of the functional layer 20 to measure the indentation hardness at the cross section of the functional layer 20.
  • the indenter used to measure the indentation hardness at the cross section of the optical sheet 10 is a Berkovich indenter having a triangular pyramid shape.
  • the indenter is pressed into the cross section of the sample that is to be evaluated from a direction perpendicular to the surface to be evaluated.
  • the indenter is pressed at a pressing speed of 10 nm/sec.
  • the indenter is pressed into the sample until the indentation depth reaches 100 nm.
  • the indenter is held in a state in which it is pressed 100 nm into the optical sheet 10 from the surface to be evaluated for 5 seconds.
  • the indenter is then retracted from the surface to be evaluated, and the load is removed from the optical sheet 10.
  • the indenter is moved along a direction perpendicular to the surface to be evaluated.
  • the indenter is retracted at a pressing speed of 10 nm/sec.
  • the above-described movement of the indenter results in a load-displacement curve C.
  • the load-displacement curve C is a graph showing the magnitude of the load applied to the surface to be evaluated via the indenter and the pressing depth of the indenter.
  • Figure 2B shows an example of the load-displacement curve C.
  • the indentation hardness H IT is determined by the following formula (1) using the maximum load Fmax and the contact projection area Ap.
  • HIT Fmax/Ap...(1)
  • the maximum load Fmax and the contact projection area Ap are obtained by analyzing the load-displacement curve.
  • the maximum load Fmax is the maximum indentation load.
  • the contact projection area Ap is the projected area on a plane perpendicular to the indentation direction of the region where the indenter and the sample are in contact at the maximum indentation load.
  • the contact projection area Ap is determined by a correction formula created by the standard method for the device using a standard sample of fused quartz.
  • the indentation hardness is the arithmetic average of 10 measurements taken at 10 measurement positions on the optical sheet being evaluated.
  • Condition (A) requires that the indentation hardness at the cross section of the functional layer 20 increases from the second side to the first side in the first direction D1. In other words, condition (A) requires that the indentation hardness at the cross section of the functional layer 20 increases from the second surface 12 to the first surface 11.
  • Condition (B) requires that the gradient of change in indentation hardness in the cross section of the functional layer 20 is smaller on the first side in the first direction D1 than on the second side. In other words, condition (B) requires that the indentation hardness in the cross section of the functional layer 20 changes significantly in the vicinity of the second side 22 (second surface 12).
  • condition (A) and condition (B) By combining condition (A) and condition (B), in the region away from the first surface 11 of the functional layer 20, the hardness increases rapidly from the first surface 11 to the second surface 12. Sufficient hardness is ensured in the region close to the first surface 11 of the functional layer 20. Furthermore, even in the region close to the first surface 11 of the functional layer 20, the hardness can increase from the second surface 12 to the first surface 11. Therefore, by combining condition (A) and condition (B), the hardness of the first surface 11 of the optical sheet 10 can be improved, and the scratch resistance of the first surface 11 of the optical sheet 10 can be improved. In addition, the ultraviolet absorbing agent contained in the functional layer 20 can be suppressed from bleeding out from the first surface 11. This allows the optical sheet 10 to stably exhibit its ultraviolet ray blocking function and blue light blocking function.
  • condition (C) including the indentation hardness HA1 and the indentation hardness HA2 may further be satisfied.
  • condition (C) which sets the upper limit of "HA1/HA2"
  • the indentation hardness HA2 at the second position 27 can be made sufficiently larger than the indentation hardness HA1 at the first position 26.
  • the indentation hardness at the cross section of the functional layer 20 increases from the second side surface 22 toward the first side surface 21.
  • condition (C) is satisfied, the indentation hardness at the cross section of the functional layer 20 increases sufficiently at the center of the second side surface 22 and the first side surface 21.
  • the functional layer 20 has a sufficiently large indentation hardness in the region from the center in the thickness direction to the first side surface 21. This effectively improves the hardness at the first surface 11 of the optical sheet 10, and effectively improves the scratch resistance at the first surface 11.
  • the "HA1/HA2" ratio specified in condition (C) may be 1.7 or less, 1.5 or less, 1.2 or less, or 1.1 or less. There is no particular lower limit for "HA1/HA2". "HA1/HA2" may be 1.0 or more, or may be greater than 1.0.
  • condition (D) including the indentation hardness HA2 and the indentation hardness HA3 may further be satisfied.
  • condition (D) which sets the lower limit of "HA2/HA3"
  • the indentation hardness HA2 at the second position 27 can be made sufficiently larger than the indentation hardness HA3 at the third position 28.
  • the indentation hardness at the cross section of the functional layer 20 increases from the second side surface 22 toward the first side surface 21.
  • condition (D) is satisfied, the indentation hardness at the cross section of the functional layer 20 increases sufficiently at the center of the second side surface 22 and the first side surface 21.
  • the functional layer 20 has a sufficiently large indentation hardness in the region from the center in the thickness direction to the first side surface 21. This effectively improves the hardness at the first surface 11 of the optical sheet 10, and effectively improves the scratch resistance at the first surface 11.
  • the "HA2/HA3" defined in condition (D) may be 1.2 or more, 1.7 or more, 2.0 or more, 2.4 or more, or 2.7 or more. No upper limit is set for "HA2/HA3". "HA2/HA3" may be 5.0 or less. "HA2/HA3” may be 1.2 or more and 5.0 or less, 1.7 or more and 5.0 or less, 2.0 or more and 5.0 or less, 2.4 or more and 5.0 or less, or 2.7 or more and 5.0 or less.
  • condition (E) including the indentation hardness HA1 and the indentation hardness HA3 may be further satisfied.
  • condition (D) which sets the lower limit of "HA1/HA3"
  • the indentation hardness HA1 at the first position 26 can be made sufficiently larger than the indentation hardness HA3 at the third position 28.
  • the indentation hardness at the cross section of the functional layer 20 becomes sufficiently larger from the second side surface 22 to the first side surface 21. This effectively improves the hardness at the first surface 11 of the optical sheet 10, and effectively improves the scratch resistance at the first surface 11.
  • the "HA1/HA3" defined in condition (E) may be 1.4 or more, 2.0 or more, 2.5 or more, 3.0 or more, or 3.2 or more. No upper limit is set for "HA1/HA3". "HA1/HA3" may be 5.5 or less. "HA1/HA3” may be 1.4 or more and 5.5 or less, 2.0 or more and 5.5 or less, 2.5 or more and 5.5 or less, 3.0 or more and 5.5 or less, or 3.2 or more and 5.5 or less.
  • condition (F) including the indentation hardness HA2 and the indentation hardness HC may further be satisfied.
  • the indentation hardness HC is the indentation hardness of the base layer 40 at a cross section of the optical sheet 10. As shown in FIG. 2A, the cross section of the optical sheet 10 where the indentation hardness HC is measured is a cross section along the thickness direction of the optical sheet 10. In the illustrated example, the cross section of the optical sheet 10 where the indentation hardness HC is measured is a cross section along the first direction D1, which is the stacking direction of the functional layer 20 and the base layer 40.
  • the indentation hardness HC is the indentation hardness at the central position 41 of the base material layer 40 in the cross section of the base material layer 40. As shown in FIG. 2A, the central position 41 is located in the center in the thickness direction in the cross section of the base material layer 40.
  • condition (F) which sets the upper limit of "HA2/HC"
  • deformation such as curling or warping of the optical sheet 10 can be suppressed.
  • the "HA2/HC” defined in condition (F) may be 1.3 or less, 1.2 or less, or 1.1 or less. No lower limit is set for “HA2/HC”. "HA2/HC” may be 0.73 or more, 0.90 or more, or 0.95 or more.
  • HA2/HC may be 0.73 or more and 1.3 or less, 0.73 or more and 1.2 or less, or 0.73 or more and 1.1 or less.
  • HA2/HC may be 0.90 or more and 1.3 or less, 0.90 or more and 1.2 or less, or 0.90 or more and 1.1 or less.
  • HA2/HC may be 0.95 or more and 1.3 or less, 0.95 or more and 1.2 or less, or 0.95 or more and 1.1 or less.
  • condition (G) including the indentation hardness HA1 and the indentation hardness HC may be further satisfied.
  • condition (G) that sets the upper limit of "HA1/HC” deformation of the optical sheet 10 such as curling and warping can be suppressed.
  • the "HA1/HC” specified in condition (G) may be 1.5 or less, 1.3 or less, or 1.2 or less. There is no particular lower limit for “HA1/HC”. "HA1/HC” may be 1.0 or more, 1.1 or more, or 1.2 or more.
  • HA1/HC may be 1.0 or more and 1.5 or less, or 1.0 or more and 1.3 or less, or 1.0 or more and 1.2 or less.
  • HA1/HC may be 1.1 or more and 1.5 or less, or 1.1 or more and 1.3 or less, or 1.1 or more and 1.2 or less.
  • HA1/HC may be 1.2 or more and 1.5 or less, or 1.2 or more and 1.3 or less.
  • condition (H) including the indentation hardness HA and the indentation hardness HC may be further satisfied.
  • H the condition that sets the upper limit of "HA/HC”
  • HA/HC defined in condition (H) may be 1.2 or less, 1.1 or less, or 0.90 or less. No lower limit is set for “HA/HC”. "HA/HC” may be 0.78 or more, 0.84 or more, or 0.86 or more.
  • HA/HC may be 0.78 or more and 1.2 or less, 0.78 or more and 1.1 or less, or 0.78 or more and 0.90 or less.
  • HA/HC may be 0.84 or more and 1.2 or less, 0.84 or more and 1.1 or less, or 0.84 or more and 0.90 or less.
  • HA/HC may be 0.86 or more and 1.2 or less, 0.86 or more and 1.1 or less, or 0.86 or more and 0.90 or less.
  • a lower limit for the indentation hardness HA1 at the first position 26 may be set. By setting a lower limit for the indentation hardness HA1, the hardness at the first surface 11 of the optical sheet 10 can be effectively improved, and the scratch resistance at the first surface 11 can be effectively improved.
  • the indentation hardness HA1 at the first position 26 may be 340 MPa or more, 342 MPa or more, 387 MPa or more, 409 MPa or more, 414 MPa or more, 417 MPa or more, 483 MPa or more, 500 MPa or more, or 522 MPa or more.
  • the indentation hardness HA1 may be 600 MPa or less.
  • the indentation hardness HA1 may be 340 MPa or more and 600 MPa or less, 342 MPa or more and 600 MPa or less, 387 MPa or more and 600 MPa or less, 409 MPa or more and 600 MPa or less, 414 MPa or more and 600 MPa or less, 417 MPa or more and 600 MPa or less, 483 MPa or more and 600 MPa or less, 500 MPa or more and 600 MPa or less, or 522 MPa or more and 600 MPa or less.
  • a lower limit for the indentation hardness HA2 at the second position 27 may be set.
  • the indentation hardness HA2 at the second position 27 may be 240 MPa or more, 243 MPa or more, 298 MPa or more, 313 MPa or more, 348 MPa or more, 360 MPa or more, 424 MPa or more, or 453 MPa or more.
  • the indentation hardness HA2 may be 550 MPa or less.
  • the indentation hardness HA2 may be 240 MPa or more and 550 MPa or 243 MPa or more and 550 MPa or 298 MPa or more and 550 MPa or 313 MPa or more and 550 MPa or 348 MPa or more and 550 MPa or 360 MPa or more and 550 MPa or 424 MPa or more and 550 MPa or 453 MPa or more and 550 MPa.
  • a lower limit for the indentation hardness HA3 at the third position 28 may be set.
  • the indentation hardness HA3 at the third position 28 may be 120 MPa or more, 122 MPa or more, 126 MPa or more, 129 MPa or more, 132 MPa or more, 147 MPa or more, 241 MPa or more, or 264 MPa or more.
  • the indentation hardness HA3 may be 350 MPa or less.
  • the indentation hardness HA3 may be 120 MPa or more and 350 MPa or less, 122 MPa or more and 350 MPa or less, 126 MPa or more and 350 MPa or less, 129 MPa or more and 350 MPa or less, 132 MPa or more and 350 MPa or less, 147 MPa or more and 350 MPa or less, 241 MPa or more and 350 MPa or less, or 264 MPa or more and 350 MPa or less.
  • the hardness of the first surface 11 of the optical sheet 10 can be improved, and the scratch resistance of the first surface 11 of the optical sheet 10 can also be improved.
  • the pencil hardness of the first surface 11 can be made 2H or more.
  • the load capacity of the first surface 11 in a steel wool scratch resistance test can be made 100 g or more.
  • Pencil hardness is an index showing resistance to defects such as scratches that occur when a pencil lead is pressed against a sample to be evaluated and moved. Pencil hardness is measured using a pencil hardness tester.
  • the optical sheet sample to be evaluated is rectangular in shape. The short side of the rectangular shape is 50 mm, and the long side is 100 mm.
  • the test environment is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%.
  • the sample is placed in the test environment for 16 hours before the start of the test.
  • the rectangular sample is spread out on the pencil hardness tester so as not to cause wrinkles or warping.
  • the two short sides of the spread sample are fixed to the pencil hardness tester using mending tape over the entire length of the short sides.
  • the mending tape may be 3M's product name "810-3-18".
  • the load applied to the pencil during the test is 500 g.
  • the pencil movement speed is 1.4 mm/sec.
  • the pencil movement length is 10 mm.
  • the pencil movement direction is parallel to the long side of the sample.
  • the pencil is a UNI made by MITSU-BISHI. Five tests are performed on the same sample using pencils of the same hardness. The five tests are performed at locations on the same sample that are at least 10 mm apart. A re-sharpened pencil is used for each of the five tests.
  • test count is four or more times without defects on the first surface 11, the sample is deemed to have passed the evaluation.
  • a defect is a scratch of 3 mm or more.
  • the presence or absence of defects is confirmed by visually inspecting the surface of the sample removed from the pencil hardness tester. The sample surface is observed under indoor lighting. The observation distance is 30 cm. The illuminance on the sample surface to be observed is 800 Lx or more and 1200 Lx or less.
  • the pencil hardness of the sample to be evaluated shall be the highest of the pencil hardnesses used in the tests that were judged to have passed.
  • Other conditions for the pencil hardness test shall conform to JIS K 5600-5-4:1999.
  • the steel wool scratch resistance test is an index showing resistance to defects such as scratches that occur when steel wool is pressed against a sample to be evaluated and moved relative to it.
  • the optical sheet sample to be evaluated is rectangular in shape.
  • the short side of the rectangle is 30 mm, and the long side is 250 mm.
  • the rectangular sample is spread out on the test machine so that no wrinkles or warping occurs.
  • the two short sides of the spread sample are fixed to the test machine using mending tape over the entire length of the short sides.
  • the mending tape is not particularly limited. As an example, the mending tape may be "810-3-18" manufactured by 3M.
  • the steel wool as a sliding piece is brought into contact with the surface of the sample that is constituted by the first side of the optical sheet.
  • the steel wool is "Bonstar B-204" with a count of #0000 manufactured by Japan Steel Wool Co., Ltd.
  • the Bonstar B-204 is a commercial size with a width of approximately 390 mm, length of approximately 75 mm, and thickness of approximately 110 mm.
  • the contact area between the test sample and the sliding piece is 20 mm x 20 mm.
  • a load is applied to the sliding piece from the vertical direction, and the sample that is spread out along the horizontal surface is pressed against the sliding piece. With the sliding piece pressed against the sample, the sliding piece and the sample are moved relative to each other in the horizontal direction.
  • the sliding piece and the test sample are moved relative to each other in a direction perpendicular to the direction in which the steel wool fibers mainly extend.
  • the load pressing the sliding piece against the sample is a minimum of 50 g.
  • the relative movement is a reciprocating movement along a linear path.
  • the reciprocating movement cycle is 10 times.
  • the test environment is 23°C ⁇ 2°C in temperature and 50% ⁇ 5% in relative humidity.
  • the sample is placed in the test environment for 16 hours before the start of the test.
  • the reciprocating speed is 100 mm/sec.
  • the stroke of the reciprocating motion is 120 mm for both the forward and return paths.
  • the reciprocating motion is parallel to the long side of the sample.
  • the preparation sample is a polyethylene terephthalate film.
  • the preparation sample is rectangular with short sides of 30 mm and long sides of 250 mm.
  • the steel wool is rubbed against the untreated surface of the polyethylene terephthalate film.
  • the preparation sample is spread along a horizontal plane, and the two short sides of the preparation sample are fixed to the testing machine with mending tape.
  • the steel wool is pressed against the preparation sample from above in the vertical direction.
  • the contact area between the preparation sample and the steel wool is 20 mm x 20 mm.
  • the load used to press the steel wool against the preparation sample is 500 g.
  • the steel wool and the preparation sample are moved relative to each other in the horizontal direction.
  • the steel wool and the preparation sample are moved relative to each other in a direction perpendicular to the direction in which the steel wool fibers mainly extend.
  • the relative movement is a reciprocating movement.
  • the reciprocating movement is performed 200 times.
  • the reciprocating movement speed is 100 mm/sec.
  • the stroke of the reciprocating movement is 120 mm for both the forward and return paths.
  • the steel wool pressed against the preparation sample in this manner is used in the test to be evaluated.
  • the sample is removed from the testing machine and the surface of the sample, which is made up of the first side of the optical sheet, is observed with the naked eye.
  • the sample surface is observed under indoor lighting. The observation distance is 30 cm.
  • the illuminance on the surface of the sample being evaluated is 800 Lx or more and 1200 Lx or less.
  • the steel wool scratch resistance test is performed five times on the optical sheet to be evaluated. A test that does not observe scratches on the first surface 11 four or more times is considered to have passed the test. The five tests are performed on different samples cut out from the same optical sheet. The steel wool is replaced after each of the five tests. The above-mentioned break-in of the steel wool is performed after each of the five tests.
  • the load with which the sliding piece is pressed against the sample is increased by 50g up to 300g.
  • the load with which the sliding piece is pressed against the sample is increased by 50g each time: 100g, 150g, 200g, 250g, 300g.
  • the maximum load in the test that is judged as a pass is regarded as the load capacity of the steel wool scratch resistance test for that sample. For example, an evaluation object that is evaluated as having a load capacity of 200g is judged to pass in all tests with a pressing load of 50g, 100g, 150g, and 200g.
  • condition (A) and condition (B) by satisfying other conditions in addition to condition (A) and condition (B), the hardness and scratch resistance of the first surface 11 of the optical sheet 10 can be improved.
  • the pencil hardness of the first surface 11 may be 2H or more, 3H or more, or 4H or more.
  • the load capacity of the first surface 11 in a steel wool scratch resistance test may be 100g or more, 150g or more, 200g or more, 250g or more, or 300g or more.
  • the pencil hardness of the first surface 11 may be 2H or more and 8H or less, 3H or more and 8H or less, or 4H or more and 8H or less.
  • the load capacity in the steel wool scratch resistance test on the first surface 11 may be 100 g or more and 300 g or less, 150 g or more and 300 g or less, 200 g or more and 300 g or less, or 300 g.
  • the functional layer 20 may be in contact with the substrate layer 40.
  • the functional layer 20 may be formed by applying a curable resin composition onto the substrate layer 40.
  • the substrate layer 40 may be a substrate film.
  • the optical sheet 10 may further include an intermediate layer 30.
  • the intermediate layer 30 is located between the functional layer 20 and the base layer 40 in the first direction D1, which is the thickness direction.
  • the intermediate layer 30 is in contact with the functional layer 20.
  • the intermediate layer 30 is in contact with the base layer 40.
  • the base layer 40 and intermediate layer 30 may both be constituted by a base film 45 to which a curable resin composition for producing the functional layer 20 is applied.
  • the intermediate layer 30 may be constituted by a portion of the base film 45 that is permeated with the curable resin composition.
  • the base layer 40 may be constituted by a portion of the base film 45 that is not permeated with the curable resin composition.
  • the intermediate layer 30 as a permeation layer may contain at least a portion of the same resin component as that contained in the base layer 40. According to this example, the adhesion between the intermediate layer 30 and the base layer 40 can be improved. The adhesion between the intermediate layer 30 and the base layer 40 can also contribute to improving the hardness at the first surface 11.
  • the intermediate layer 30 as a permeation layer may contain at least a portion of the same resin component as that contained in the functional layer 20. According to this example, the adhesion between the intermediate layer 30 and the functional layer 20 can be improved. The adhesion between the intermediate layer 30 and the functional layer 20 can also contribute to improving the hardness at the first surface 11.
  • the intermediate layer 30 may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the functional layer 20. By including an ultraviolet absorbing agent in the intermediate layer 30, the blue light blocking function can be enhanced.
  • the intermediate layer 30 As a permeation layer, the adhesion between the base film 45 and the functional layer 20 is improved. This improves the hardness of the first surface 11 of the optical sheet 10, and improves the scratch resistance of the first surface 11 of the optical sheet 10.
  • Fourier transform infrared spectroscopy allows for quantitative analysis of the chemical bonds contained in each layer 20, 30, 40. By using Fourier transform infrared spectroscopy, it is possible to determine whether or not the intermediate layer 30 contains the resin component contained in the functional layer 20. By using Fourier transform infrared spectroscopy, it is possible to determine whether or not the intermediate layer 30 contains the resin component contained in the base layer 40.
  • the presence of the permeation layer can be confirmed by observing the cross section of the optical sheet along the first direction with a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • An observation image of the cross section of the optical sheet 10 to be evaluated is obtained by observing a thickness measurement sample, described below, with a scanning transmission electron microscope.
  • the thickness measurement sample is stained before observation with the scanning transmission electron microscope. Osmium tetroxide, ruthenium tetroxide, phosphotungstic acid, etc. may be used for staining.
  • the substrate film 45 may contain one or more of an acrylic resin and a cellulose resin.
  • the acrylic resin and the cellulose resin are easily permeated with the curable resin composition. Therefore, the intermediate layer 30, which is a mixed layer of the resin components of the functional layer 20 and the resin components of the substrate layer 40, can be easily produced. From this point of view, the substrate layer 40 may contain one or more of an acrylic resin and a cellulose resin.
  • the intermediate layer 30 may contain one or more of an acrylic resin and a cellulose resin.
  • the indentation hardness HB of the intermediate layer 30 at the cross section may be smaller than the indentation hardness HC of the base layer 40 at the cross section.
  • the intermediate layer 30 with a small indentation hardness can flexibly deform in accordance with the deformation of the functional layer 20 when the functional layer 20 cures and shrinks. By positioning this intermediate layer 30 between the base layer 40 and the functional layer 20, deformation such as curling and warping of the optical sheet 10 can be suppressed.
  • the indentation hardness HB at the cross section of the intermediate layer 30 is the indentation hardness of the intermediate layer 30 at the cross section of the optical sheet 10.
  • the cross section of the optical sheet 10 where the indentation hardness is measured is a cross section along the thickness direction of the optical sheet 10.
  • the cross section of the optical sheet 10 where the indentation hardness is measured is a cross section along the first direction D1, which is the stacking direction of the functional layer 20 and the base layer 40.
  • the indentation hardness HB is the indentation hardness at the central position 31 of the intermediate layer 30 at the cross section of the intermediate layer 30. As shown in FIG. 2A, the central position 31 is located at the center in the thickness direction at the cross section of the intermediate layer 30.
  • the intermediate layer 30 may contain a monomer.
  • the intermediate layer 30 may contain at least a portion of the monomer contained in the curable resin composition for producing the functional layer 20. According to these examples, an intermediate layer 30 with low hardness can be stably formed.
  • the intermediate layer 30 functions as a deformation absorbing layer and can suppress deformation such as curling and warping of the optical sheet 10.
  • Whether the intermediate layer 30 contains a monomer is determined by staining with osmium tetroxide.
  • a cross-sectional sample is cut out from the optical sheet 10 by cutting. The thickness of the sample is about 80 nm. The cut out sample is collected on a Cu mesh. This sample is stained with osmium tetroxide for 30 minutes by a vapor-phase staining method. The portion of the stained sample corresponding to the intermediate layer 30 is observed using a scanning transmission electron microscope (STEM). Unsaturated double bonds that may be contained in the intermediate layer 30 are colored by the staining process. Therefore, if the observed sample is colored by staining, it is determined that the intermediate layer 30 contains a monomer. Whether the monomer contained in the intermediate layer 30 is the same as the monomer contained in the curable resin composition for producing the intermediate layer 30 is determined by quantitatively analyzing the chemical bonds using Fourier transform infrared spectroscopy (FT-IR).
  • FT-IR Fourier transform infrared spect
  • a lower limit for the indentation hardness HB at the cross section of the intermediate layer 30 may be set. By setting a lower limit for the indentation hardness HB, the hardness at the first surface 11 of the optical sheet 10 can be effectively improved.
  • the indentation hardness HB at the cross section of the intermediate layer 30 may be 120 MPa or more, 124 MPa or more, 138 MPa or more, 142 MPa or more, 151 MPa or more, or 156 MPa or more.
  • An upper limit may be set for the indentation hardness HB at the cross section of the intermediate layer 30.
  • the indentation hardness HB at the cross section of the intermediate layer 30 may be 240 MPa or less, 237 MPa or less, 200 MPa or less, or 180 MPa or less.
  • the indentation hardness HB may be 120 MPa or more and 240 MPa or less, 124 MPa or more and 240 MPa or less, 138 MPa or more and 240 MPa or less, 142 MPa or more and 240 MPa or less, 151 MPa or more and 240 MPa or less, or 156 MPa or more and 240 MPa or less.
  • the indentation hardness HB may be 120 MPa or more and 237 MPa or less, 124 MPa or more and 237 MPa or less, 138 MPa or more and 237 MPa or less, 142 MPa or more and 237 MPa or less, 151 MPa or more and 237 MPa or less, or 156 MPa or more and 237 MPa or less.
  • the indentation hardness HB may be 120 MPa or more and 200 MPa or less, 124 MPa or more and 200 MPa or less, 138 MPa or more and 200 MPa or less, 142 MPa or more and 200 MPa or less, 151 MPa or more and 200 MPa or less, or 156 MPa or more and 200 MPa or less.
  • the indentation hardness HB may be 120 MPa or more and 180 MPa or less, 124 MPa or more and 180 MPa or less, 138 MPa or more and 180 MPa or less, 142 MPa or more and 180 MPa or less, 151 MPa or more and 180 MPa or less, or 156 MPa or more and 180 MPa or less.
  • a lower limit may be set for the thickness T20 of the functional layer 20.
  • the thickness T20 of the functional layer 20 may be 4.0 ⁇ m or more, 4.2 ⁇ m or more, 5.2 ⁇ m or more, or 5.5 ⁇ m or more.
  • An upper limit may be set for the thickness T20 of the functional layer 20.
  • the thickness T20 of the functional layer 20 may be 10 ⁇ m or less, 9.5 ⁇ m or less, 8.7 ⁇ m or less, or 7.4 ⁇ m or less.
  • the thickness T20 of the functional layer 20 may be 4.0 ⁇ m or more and 10 ⁇ m or less, 4.2 ⁇ m or more and 10 ⁇ m or less, 5.2 ⁇ m or more and 10 ⁇ m or less, or 5.5 ⁇ m or more and 10 ⁇ m or less.
  • the thickness T20 of the functional layer 20 may be 4.0 ⁇ m or more and 9.5 ⁇ m or less, 4.2 ⁇ m or more and 9.5 ⁇ m or less, 5.2 ⁇ m or more and 9.5 ⁇ m or less, or 5.5 ⁇ m or more and 9.5 ⁇ m or less.
  • the thickness T20 of the functional layer 20 may be 4.0 ⁇ m or more and 8.7 ⁇ m or less, 4.2 ⁇ m or more and 8.7 ⁇ m or less, 5.2 ⁇ m or more and 8.7 ⁇ m or less, or 5.5 ⁇ m or more and 8.7 ⁇ m or less.
  • the thickness T20 of the functional layer 20 may be 4.0 ⁇ m or more and 7.4 ⁇ m or less, 4.2 ⁇ m or more and 7.4 ⁇ m or less, 5.2 ⁇ m or more and 7.4 ⁇ m or less, or 5.5 ⁇ m or more and 7.4 ⁇ m or less.
  • An upper limit may be set for the thickness T30 of the intermediate layer 30.
  • an upper limit may be set for the thickness T30 of the intermediate layer 30.
  • the thickness T30 of the intermediate layer 30 may be 4.2 ⁇ m or less, 3.1 ⁇ m or less, 2.7 ⁇ m or less, 2.4 ⁇ m or less, 2.3 ⁇ m or less, or 2.0 ⁇ m or less.
  • the intermediate layer 30 is not essential and can be omitted from the optical sheet 10.
  • the thickness T30 of the intermediate layer 30 may be greater than 0, may be 0.5 ⁇ m or more, may be 1.0 ⁇ m or more, or may be 1.4 ⁇ m or more.
  • the thickness T30 of the intermediate layer 30 may be 0.5 ⁇ m or more and 4.2 ⁇ m or less, 0.5 ⁇ m or more and 3.1 ⁇ m or less, 0.5 ⁇ m or more and 2.7 ⁇ m or less, 0.5 ⁇ m or more and 2.4 ⁇ m or less, 0.5 ⁇ m or more and 2.3 ⁇ m or less, or 0.5 ⁇ m or more and 2.0 ⁇ m or less.
  • the thickness T30 of the intermediate layer 30 may be 1.0 ⁇ m or more and 4.2 ⁇ m or less, 1.0 ⁇ m or more and 3.1 ⁇ m or less, 1.0 ⁇ m or more and 2.7 ⁇ m or less, 1.0 ⁇ m or more and 2.4 ⁇ m or less, 1.0 ⁇ m or more and 2.3 ⁇ m or less, or 1.0 ⁇ m or more and 2.0 ⁇ m or less.
  • the thickness T30 of the intermediate layer 30 may be 1.4 ⁇ m or more and 4.2 ⁇ m or less, 1.4 ⁇ m or more and 3.1 ⁇ m or less, 1.4 ⁇ m or more and 2.7 ⁇ m or less, 1.4 ⁇ m or more and 2.4 ⁇ m or less, 1.4 ⁇ m or more and 2.3 ⁇ m or less, or 1.4 ⁇ m or more and 2.0 ⁇ m or less.
  • the thickness T40 of the base layer 40 may be thicker than the thickness T20 of the functional layer 20.
  • the thickness T40 of the base layer 40 may be thicker than the thickness T30 of the intermediate layer 30.
  • the thickness T40 of the base layer 40 may be thicker than the total thickness of the thickness T20 of the functional layer 20 and the thickness T30 of the intermediate layer 30.
  • a base layer 40 having such a thickness T40 can stably support the functional layer 20 and the intermediate layer 30.
  • the intermediate layer 30 as a permeation layer is not essential for the optical sheet 10 of the first embodiment.
  • the intermediate layer 30 itself is not essential for the optical sheet 10 of the first embodiment. Regardless of the presence or absence of the intermediate layer 30, the hardness and scratch resistance of the first surface 11 can be improved by satisfying the above-mentioned conditions (A) and (B) regarding the indentation hardness in the cross section of the functional layer 20.
  • the thicknesses T20, T30, and T40 of each layer 20, 30, and 40 included in the optical sheet 10 are determined using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 10 to be evaluated is observed with a scanning transmission electron microscope, and the thickness is measured from the image observed with the scanning transmission electron microscope.
  • the thicknesses T20, T30, and T40 are determined as the arithmetic mean of the ten thickness measurements taken at ten measurement positions.
  • the observation image of the cross section of the optical sheet 10 to be evaluated is obtained by observing the thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained by the following first and second steps.
  • a cut sample is cut out from the optical sheet to be evaluated.
  • the cut sample is visually checked for any abnormalities such as dirt or scratches.
  • the cut sample is embedded in resin to prepare an embedded sample.
  • the embedded sample is prepared as follows. First, the cut sample is placed in a silicon embedding plate. Embedding resin is poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin is hardened inside the silicon embedding plate. Next, the cut sample and the embedding resin that encases it are removed from the silicon embedding plate to obtain the embedded sample. The embedded sample is shaped like a block.
  • the embedding resin is epoxy resin.
  • the block-shaped embedded sample is cut to prepare a slice sample.
  • the slice sample includes a surface along a first direction (thickness direction, lamination direction) of the target optical sheet.
  • a slice sample that is free of defects such as holes and has a uniform thickness of about 60 nm to 100 nm is used as a thickness measurement sample.
  • the imaging conditions of the scanning transmission electron microscope are as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • the a * value of the L * a * b * color system of the optical sheet 10 measured by transmitted light may be -3.0 or more and -1.6 or less.
  • the b * value of the L * a * b * color system of the optical sheet 10 measured by transmitted light may be 3.5 or more and 6.0 or less.
  • the L * a * b * color system is a color coordinate defined as the CIE 1976 L * a * b * color space, and is also defined in JIS Z8781-4:2013.
  • the a * value and b * value in the L * a * b * color system are obtained based on the transmittance measured at 0.5 nm intervals in the range of 300 nm to 780 nm.
  • the light source of the measuring device is turned on for 15 minutes to stabilize the output of the light source.
  • the incident surface when measuring the a* value and the b * value is the second surface 12 of the optical sheet 10.
  • the test environment when measuring the a* value and the b * value is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%.
  • the sample is placed in the test environment for 16 hours before the start of the test.
  • the a * value is the arithmetic average of five measured values.
  • the five measured values are measured at five measurement positions on the optical sheet to be evaluated. The five measurement positions are located 10 mm or more apart from each other.
  • the b * value is the arithmetic average of the five measured values.
  • the five measured values for the b * value are the values measured at the five measurement positions where the five measured values for the a * value were measured.
  • the yellowness index (YI value) of the optical sheet 10 may be 12 or less, 11 or less, 10 or less, or 9.0 or less.
  • the yellowness index is an index showing the degree of yellow coloring of the optical sheet 10.
  • the yellowness (YI value) of the optical sheet 10 may be equal to or greater than 0.
  • the yellowness index (YI value) of the optical sheet 10 may be 0 or more and 12 or less, 0 or more and 11 or less, 0 or more and 10 or less, or 0 or more and 9.0 or less.
  • the yellowness index (YI value) of the optical sheet 10 may be 0 or more and 12 or less, 0 or more and 11 or less, 0 or more and 10 or less, or 0 or more and 9.0 or less.
  • Yellowness is measured by transmitted light.
  • auxiliary illuminant C and a 2-degree visual field are used to measure transmittance at 0.5 nm intervals in the range of 300 nm to 780 nm, and tristimulus values X, Y, and Z in the XYZ color system are calculated based on the measured transmittance.
  • the geometrical optical condition e of JIS Z 8722:2009 is adopted as the geometrical optical condition when measuring the yellowness.
  • the diameter of the incident light beam on the test piece is made smaller than the diameter of the opening.
  • the light source of the measuring device is turned on for 15 minutes to stabilize the output of the D65 light source.
  • the incident surface when measuring the yellowness is the second surface 12 of the optical sheet 10.
  • the test environment when measuring the yellowness is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%. The sample is placed in the test environment for 16 hours before the start of the test.
  • the yellowness index (YI value) is the arithmetic average of five measured values.
  • the five measured values are measured at five measurement positions on the optical sheet to be evaluated.
  • the five measurement positions are located at least 10 mm apart from each other.
  • Other measurement conditions when measuring the yellowness index (YI value) are in accordance with JIS K7373-1:2006.
  • the total light transmittance of the optical sheet 10 may be 50% or more, 70% or more, 80% or more, or 90% or more.
  • the total light transmittance of the optical sheet 10 does not have a particular upper limit.
  • the total light transmittance of the optical sheet 10 may be 100% or less, or may be less than 100%.
  • the total light transmittance of the optical sheet 10 may be 50% or more and 100% or less, 70% or more and 100% or less, 80% or more and 100% or less, or 90% or more and 100% or less.
  • the total light transmittance of the optical sheet may be 50% or more and less than 100%, 70% or more and less than 100%, 80% or more and less than 100%, or 90% or more and less than 100%.
  • a D65 light source is used to measure the total light transmittance. Before measuring the total light transmittance, the D65 light source is turned on for 15 minutes to stabilize the output of the D65 light source. The angle of incidence on the sample when measuring the total light transmittance is 0°. The incident surface when measuring the total light transmittance of the optical sheet 10 is the second surface of the optical sheet.
  • the test environment when measuring the total light transmittance is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%. The sample is placed in the test environment for 16 hours before starting the test. Other measurement conditions when measuring the total light transmittance are in accordance with JIS K7361-1:1997.
  • the total light transmittance is the arithmetic average of five measured values.
  • the five measured values are measured at five measurement positions on the optical sheet to be evaluated.
  • the five measurement positions are located at least 10 mm apart from each other.
  • the transmission haze of the optical sheet 10 may be 1.1% or less, 0.5% or less, or 0.2% or less.
  • the transmission haze of the optical sheet 10 has no particular lower limit.
  • the transmission haze of the optical sheet 10 may be 0% or more, or may be greater than 0%.
  • the transmission haze of the optical sheet 10 may be 0% or more and 1.1% or less, 0% or more and 0.5% or less, or 0% or more and 0.2% or less.
  • the transmission haze of the optical sheet 10 may be greater than 0% and 1.1% or less, greater than 0% and 0.5% or less, or greater than 0% and 0.2% or less.
  • a D65 light source is used to measure the transmission haze. Before measuring the transmission haze, the D65 light source is turned on for 15 minutes to stabilize the output of the D65 light source. The angle of incidence on the sample when measuring the transmission haze is 0°. The incident surface when measuring the transmission haze of the optical sheet 10 is the second surface 12 of the optical sheet 10. The test environment when measuring the transmission haze is a temperature of 23°C ⁇ 2°C and a relative humidity of 50% ⁇ 5%. The sample is placed in the test environment for 16 hours before the start of the test. Other measurement conditions when measuring the transmission haze are in accordance with JIS K7136:2000.
  • the transmission haze is the arithmetic average of five measured values.
  • the five measured values are measured at five measurement positions on the optical sheet to be evaluated.
  • the five measurement positions are located at least 10 mm apart from each other.
  • the ratio of silicon element to carbon element measured on the first surface 11 by X-ray photoelectron spectroscopy may be 0.02 or more.
  • the amount of silicon element may be 0.02 or more when the amount of carbon element is 1.
  • the silicon element is the sum of an inorganic component (silica) and an organic component (silicone).
  • the functional layer 20 may contain inorganic particles as a lubricant.
  • the curable resin composition for producing the functional layer 20 may contain a leveling agent.
  • a Si-based leveling agent as the leveling agent added to the curable resin composition, the ratio of silicon elements to carbon elements can be set to 0.02 or more.
  • the ratio of elemental fluorine measured on the first surface 11 by X-ray photoelectron spectroscopy may be 0.1% or less. In other words, the ratio of the amount of elemental fluorine to the total amount of elements detected by X-ray photoelectron spectroscopy may be 0.001 or less. In this example, substantially no fluorine is detected in the surface layer of the optical sheet 10. By not using an F-based leveling agent as the leveling agent added to the curable resin composition, the ratio of elemental fluorine can be 0.1% or less.
  • X-ray photoelectron spectroscopy allows for quantitative analysis of the elements present on the surface layer of the optical sheet 10.
  • X-ray photoelectron spectroscopy uses an X-ray photoelectron spectroscopy device (XPS).
  • the X-ray photoelectron spectrum of the C1s orbital, O1s orbital, Si2p orbital, and F1s orbital of the low refractive index layer surface of each measurement sample is measured under the conditions described below. Peak separation is performed for each X-ray photoelectron spectrum to determine the ratio of F element to all elements.
  • Measurement conditions Measurement method: Wide/Narrow X-ray source: Monochrome A1K ⁇ X-ray output: 150W Emission current: 10mA Acceleration voltage: 15 kV Charge neutralization mechanism: ON Measurement area: 300 ⁇ m x 700 ⁇ m Pass Energy: Survey: 160eV, Narrow: 40eV Photoelectron capture angle: 90° Auto Z: ON Peak shift correction: Correction was made so that the C-C peak in the C1s peak was 285.0 eV. Waveform separation of narrow peaks: Executed using the GL function in the analysis software attached to the device. Etching ions: Ar monoatomic ions
  • the base layer 40, the intermediate layer 30, and the functional layer 20 are stacked in the first direction D1.
  • the first direction D1 is the stacking direction.
  • the base layer 40, the intermediate layer 30, and the functional layer 20 extend in the second direction D2 and the third direction D3 perpendicular to the first direction D1.
  • the second direction D2 and the third direction D3 are perpendicular to each other.
  • the first direction D1 is the thickness direction and normal direction of the optical sheet 10.
  • the first direction D1 is also the thickness direction and normal direction of each layer 40, 30, and 20 included in the optical sheet 10.
  • the first surface 11 is composed of the functional layer 20.
  • the second surface 12 is composed of the base layer 40.
  • the functional layer 20 and the intermediate layer 30 are adjacent to each other in the first direction D1.
  • the intermediate layer 30 and the base layer 40 are adjacent in the first direction D1.
  • the optical sheet 10 may include layers other than the functional layer 20, the intermediate layer 30, and the substrate layer 40.
  • the optical sheet 10 may include one or more of a low-reflection layer, an antistatic layer, an antifouling layer, etc.
  • a layer other than the functional layer 20 may constitute the first surface 11.
  • the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer are thin layers. Therefore, even in an example in which the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer, constitute the first surface 11, the combination of the functional layer 20 and the intermediate layer 30 can improve the hardness of the first surface 11 of the optical sheet 10 and improve the scratch resistance of the first surface 11 of the optical sheet 10.
  • the base layer 40 supports the functional layer 20 together with the intermediate layer 30.
  • the base layer 40 may be transparent. Transparent means that the total light transmittance in accordance with JIS K7361-1:1997 is 50% or more, and may be 70% or more, 80% or more, or 90% or more.
  • the material of the base layer 40 is not particularly limited.
  • the material of the base layer 40 may be resin or glass. Resin is preferable because it is lightweight and easy to manufacture.
  • the resin used in the base layer 40 may be a polyolefin resin such as polyethylene or polypropylene.
  • the resin used in the base layer 40 may be a vinyl resin such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, or ethylene-vinyl alcohol copolymer.
  • the resin used in the base layer 40 may be a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate.
  • the resin used in the base layer 40 may be an acrylic resin such as polymethyl (meth)acrylate or polyethyl (meth)acrylate.
  • the resin used in the base layer 40 may be a styrene resin such as polystyrene, a polyamide resin such as nylon 6 or nylon 66, or a cellulose resin such as triacetyl cellulose. Further examples of the resin used in the base layer 40 include resins such as polycarbonate, polyimide resins, and cycloolefin resins obtained from cycloolefins such as norbornene and dicyclopentadiene.
  • the substrate layer 40 may contain only one of the above-mentioned resins, or may contain two or more of the above-mentioned resins.
  • the thickness of the resin substrate layer 40 is not particularly limited. From the viewpoint of ease of handling, the thickness of the resin substrate layer 40 may be 10 ⁇ m or more, 20 ⁇ m or more, or 50 ⁇ m or more. The thickness of the resin substrate layer 40 may be 500 ⁇ m or less, 400 ⁇ m or less, or 300 ⁇ m or less. The thickness of the glass substrate layer 40 may be 500 ⁇ m or more.
  • the substrate layer 40 may be flexible.
  • the thickness of the resin substrate layer 40 may be 10 ⁇ m or more and 40 ⁇ m or less.
  • the thickness of the resin substrate layer 40 may be 40 ⁇ m or more and 100 ⁇ m or less from the viewpoint of preventing the glass from shattering.
  • the substrate layer 40 may be prepared as a substrate film 45.
  • This substrate film 45 may include only a single layer or may include multiple layers.
  • the substrate layer 40 may include a primer layer such as an easy-adhesion layer.
  • the surface of the substrate film 45 may be subjected to one or more of sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, etching treatment such as oxidation, and undercoat treatment. These treatments can improve the adhesion between the substrate film 45 and the layer adjacent to the substrate film 45.
  • the surface of the substrate film 45 may be subjected to a cleaning treatment such as solvent cleaning or ultrasonic cleaning.
  • the functional layer 20 includes a binder resin 23 and an ultraviolet absorbing agent.
  • the functional layer 20 exhibits a blue light blocking function by including the ultraviolet absorbing agent.
  • the binder resin 23 includes a cured product of a curable resin composition.
  • the functional layer 20 includes a cured product of a curable resin composition, which contributes to improving the hardness of the first surface 11 and the functional layer 20.
  • the curable resin composition may be an ionizing radiation curable resin composition.
  • the ionizing radiation curable resin composition may include one or more of an ultraviolet ray curable resin composition and an electron beam curable resin composition.
  • the ionizing radiation curable resin composition may include an ionizing radiation curable compound and a photopolymerization initiator.
  • the ionizing radiation curable compound may include one or more of an ultraviolet ray curable compound and an electron beam curable compound.
  • the ultraviolet ray curable compound is a resin that is cured by irradiation with ultraviolet rays.
  • the electron beam curable compound is a resin that is cured by irradiation with an electron beam.
  • the cured product of the curable resin composition may be a cured curable compound.
  • the ionizing radiation curable compound contains an ionizing radiation curable functional group.
  • the ionizing radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups.
  • the ionizing radiation curable compound may contain two or more ionizing radiation curable functional groups.
  • the ionizing radiation curable compound may be a compound having an ethylenically unsaturated bond group.
  • the ionizing radiation curable compound may be a (meth)acrylate-based compound having a (meth)acryloyl group.
  • the ionizing radiation curable compound may be a siloxane compound containing a siloxane bond.
  • (meth)acrylate compounds containing four or more ethylenically unsaturated bond groups are referred to as "polyfunctional (meth)acrylate compounds.”
  • (Meth)acrylate compounds containing two to three ethylenically unsaturated bond groups are referred to as “low-functional (meth)acrylate compounds.”
  • the (meth)acrylate compound may be a monomer or an oligomer.
  • An ionizing radiation curable compound containing a low-functionality (meth)acrylate compound can suppress uneven shrinkage during curing and smooth the surface of the functional layer 20.
  • the proportion of the low-functional (meth)acrylate compound in the ionizing radiation curable compound may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass.
  • the low-functional (meth)acrylate compound may be a (meth)acrylate compound containing two ethylenically unsaturated bond groups.
  • examples of bifunctional (meth)acrylate compounds include isocyanuric acid di(meth)acrylate, polyalkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, and polybutylene glycol di(meth)acrylate, bisphenol A tetraethoxy diacrylate, bisphenol A tetrapropoxy diacrylate, and 1,6-hexanediol diacrylate.
  • examples of trifunctional (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate.
  • polyfunctional (meth)acrylate compounds having 4 or more functional groups include pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and dipentaerythritol tetra(meth)acrylate.
  • the (meth)acrylate compound may be modified as described below.
  • Examples of (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate.
  • Urethane (meth)acrylate can be obtained, for example, by reacting polyhydric alcohol and organic diisocyanate with hydroxy (meth)acrylate.
  • Epoxy (meth)acrylate may be a (meth)acrylate obtained by reacting trifunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with (meth)acrylic acid.
  • Epoxy (meth)acrylate may be a (meth)acrylate obtained by reacting difunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with polybasic acid and (meth)acrylic acid.
  • Epoxy (meth)acrylate may be a (meth)acrylate obtained by reacting difunctional or higher aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, etc. with phenols and (meth)acrylic acid.
  • the (meth)acrylate compound may have a part of its molecular skeleton modified in order to suppress uneven shrinkage caused by crosslinking.
  • the (meth)acrylate compound may be modified with, for example, ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, etc.
  • the (meth)acrylate compound may be modified with an alkylene oxide such as ethylene oxide or propylene oxide.
  • the proportion of the alkylene oxide-modified (meth)acrylate compound in the ionizing radiation curable compound may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass.
  • the alkylene oxide-modified (meth)acrylate compound may be a low-functional (meth)acrylate compound or a (meth)acrylate compound having two ethylenically unsaturated bond groups.
  • Examples of (meth)acrylate compounds having two alkylene oxide-modified ethylenically unsaturated bond groups include bisphenol F alkylene oxide-modified di(meth)acrylate, bisphenol A alkylene oxide-modified di(meth)acrylate, isocyanuric acid alkylene oxide-modified di(meth)acrylate, and polyalkylene glycol di(meth)acrylate.
  • the average repeating units of the alkylene glycol contained in the polyalkylene glycol di(meth)acrylate may be 3 to 5.
  • the alkylene glycol contained in the polyalkylene glycol di(meth)acrylate may be ethylene glycol and/or polyethylene glycol.
  • Examples of (meth)acrylate compounds having three ethylenically unsaturated bond groups modified with alkylene oxide include trimethylolpropane alkylene oxide-modified tri(meth)acrylate and isocyanuric acid alkylene oxide-modified tri(meth)acrylate.
  • One type of ionizing radiation curable compound may be used alone, or two or more types of ionizing radiation curable compounds may be used in combination. That is, the curable resin composition may contain one type of ionizing radiation curable compound, or two or more types of ionizing radiation curable compounds.
  • the curable resin composition may contain a solvent-drying type resin.
  • a solvent-drying type resin is a resin that becomes a coating simply by drying the solvent added to adjust the solid content during coating.
  • An example of a solvent-drying type resin is a thermoplastic resin.
  • the solvent-drying type resin is not particularly limited. Examples of the solvent-drying type resin include styrene-based resins, (meth)acrylic-based resins, alicyclic olefin-based resins, polyester-based resins, and cellulose derivatives such as cellulose esters.
  • the curable resin composition may contain one or more of these solvent-drying type resins.
  • the curable resin composition may contain a thermosetting compound.
  • a thermosetting compound is a resin that hardens when heated. There are no particular limitations on the thermosetting compound. Examples of thermosetting compounds include phenolic resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, unsaturated polyester resins, polyurethane resins, epoxy resins, aminoalkyd resins, melamine-urea co-condensation resins, and silicon resins.
  • the curable resin composition may contain one or more of these thermosetting compounds.
  • the photopolymerization initiator is not particularly limited.
  • Examples of the photopolymerization initiator include acetophenones, benzophenones, Michler's benzoyl benzoate, ⁇ -amyloxime ester, thioxanthones, propiophenones, benzils, benzoins, acylphosphine oxides, etc.
  • the curable resin composition may contain one or more of these photopolymerization initiators.
  • the photopolymerization initiator may be acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, etc.
  • the curable resin composition may contain one or more of these photopolymerization initiators together with an ionizing radiation curable compound having a radically polymerizable unsaturated group.
  • the photopolymerization initiator may be an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metallocene compound, a benzoin sulfonate ester, or the like.
  • the curable resin composition may contain one or more of these photopolymerization initiators together with an ionizing radiation curable compound having a cationically polymerizable functional group.
  • the curable resin composition may contain a photosensitizer.
  • photosensitizers include n-butylamine, triethylamine, poly-n-butylphosphine, etc.
  • the curable resin composition may contain one or more of these photosensitizers.
  • the content of the photopolymerization initiator may be 1 part by mass or more, or 2 parts by mass or more, per 100 parts by mass of the ionizing radiation curable compound.
  • the content of the photopolymerization initiator may be 10 parts by mass or less, or 8 parts by mass or less, per 100 parts by mass of the ionizing radiation curable compound. This content can improve the hardness of the functional layer 20.
  • the ultraviolet absorber may be dispersed in the first direction D1, the second direction D2, and the third direction D3 in the functional layer 20.
  • the ultraviolet absorber may be included in a liquid curable resin composition.
  • the ultraviolet absorber included in the curable resin composition may be dispersed in the functional layer 20 after a coating film of the curable resin composition is subjected to a drying process and a curing process.
  • the ultraviolet absorber imparts a blue light cut function to the functional layer 20 and the optical sheet 10.
  • the characteristics of the blue light cut function can be adjusted by the type and content of the ultraviolet absorber. Therefore, the blue light cut function caused by the ultraviolet absorber can make the spectral transmittance at a wavelength of 440 nm 70% or more, while making the spectral transmittance at a wavelength of 410 nm 15% or less.
  • the a * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the b * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the yellowness YI value measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the type and content of the ultraviolet absorber are not particularly limited.
  • the type and content of the ultraviolet absorber can be selected so as to obtain the desired blue light cut function and the desired a * value and b * value.
  • Examples of ultraviolet absorbers include triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.
  • Examples of triazine-based ultraviolet absorbers include “TINUVIN 460" and “TINUVIN 477” available from BASF.
  • Examples of triazine-based ultraviolet absorbers include “LA-46” available from ADEKA Corporation.
  • Examples of benzophenone-based ultraviolet absorbers include “CHMASSORB 81/FL” available from BASF.
  • Examples of benzotriazole-based ultraviolet absorbers include "KEMISORB 71D" and “KEMISORB 79" available from Chemipro Chemical Co., Ltd.
  • benzotriazole-based ultraviolet absorbers examples include “JF-80” and “JAST-500” available from Johoku Chemical Industry Co., Ltd.
  • benzotriazole-based ultraviolet absorbers examples include “ULS-1933D” available from Lion Specialty Chemicals Co., Ltd. and “RUVA-93” available from Otsuka Chemical Co., Ltd.
  • the ultraviolet absorber contained in the curable resin composition may be polymerized or oligomerized.
  • the curable resin composition may contain a polymer or oligomer having a benzotriazole, triazine, or benzophenone skeleton as an ultraviolet absorber.
  • the curable resin composition may contain an ultraviolet absorber obtained by thermally copolymerizing a (meth)acrylate having a benzotriazole or benzophenone skeleton with methyl methacrylate (MMA) in any ratio.
  • MMA methyl methacrylate
  • the content of the ultraviolet absorber is not particularly limited.
  • the content of the ultraviolet absorber may be 1 part by mass or more, or 2 parts by mass or more, per 100 parts by mass of the solid content of the curable resin composition.
  • the content of the ultraviolet absorber may be 35 parts by mass or less, or 12 parts by mass or less, per 100 parts by mass of the solid content of the curable resin composition.
  • the curable resin composition may contain a sesamol-type benzotriazole monomer represented by the following general formula (1):
  • R 1 in formula (1) represents a hydrogen atom or a methyl group
  • R 2 in formula (1) represents a linear or branched alkylene group having 1 to 6 carbon atoms, or a linear or branched oxyalkylene group having 1 to 6 carbon atoms.
  • sesamol-type benzotriazole monomer is not particularly limited.
  • Specific examples of the sesamol-type benzotriazole monomer include the following: 2-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]ethyl methacrylate, 2-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]ethyl acrylate, 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]propyl methacrylate, 3-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5-yl]propyl acrylate, 4-[2-(6-hydroxybenzo[1,3]dioxol-5-yl)-2H-benzotriazol-5
  • the sesamol-type benzotriazole monomer may be contained in the functional layer 20 at a content of 5% by mass or more and 20% by mass or less. With such a content, it is easy to adjust the spectral transmittance to a preferred range.
  • the sesamol-type benzotriazole monomer may react with the resin component constituting the functional layer 20 and be included as part of the resin component.
  • the sesamol-type benzotriazole monomer may be included alone without reacting with the resin component constituting the functional layer 20.
  • the curable resin composition may contain particles as a lubricant.
  • the particles as a lubricant may be inorganic particles or metal oxide particles.
  • the particles as a lubricant may be silica.
  • the particles as a lubricant may be silica without a reactive group.
  • the average primary particle diameter of the silica without a reactive group may be 100 nm or more and 600 nm or less, or 100 nm or more and 350 nm or less. By setting the average primary particle diameter of the particles as a lubricant to 100 nm or more, an excellent blocking prevention function can be exhibited. By setting the average primary particle diameter of the particles as a lubricant to 600 nm or more, the transmission haze can be reduced.
  • the particle diameter of the particles contained in the functional layer 20 is a value specified by the following (1) to (3).
  • a cross section of an optical sheet containing particles is observed with a scanning transmission electron microscope (STEM) to obtain an observation image.
  • the observation image is obtained by preparing a sample similar to the above-mentioned thickness measurement sample and observing this sample with a scanning transmission electron microscope.
  • (2) 30 particles are randomly selected from the observed image, and the particle diameter of each particle is measured.
  • the measurement values of the largest 10 particles and the smallest 10 particles are excluded from the measurement values of the 30 particles, to select the particle diameter measurement values of 10 particles.
  • the particle diameter (nm) is the distance between two parallel lines that is the maximum distance between the two lines when the particle is sandwiched between the two lines.
  • the particle diameter is the maximum length of the particle in the observed image.
  • the above steps (1) and (2) are repeated five times for the same optical sheet to be measured.
  • the arithmetic mean value of the particle diameter measurements for a total of 50 particles is regarded as the average particle diameter (nm) of the particles.
  • the curable resin composition may contain a Si-based leveling agent as an additive.
  • the functional layer coating liquid contains a Si-based leveling agent
  • the surface of the functional layer 20 can be made smoother.
  • the Si-based leveling agent can impart excellent slip properties and excellent anti-fouling properties to the surface of the functional layer 20.
  • the curable resin composition may contain other additives.
  • additives include antistatic agents, antioxidants, surfactants, dispersants, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments, dyes), defoamers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, and surface modifiers.
  • the curable resin composition may contain one or more of these additives.
  • the curable resin composition may contain a solvent.
  • the solvent can be selected and used according to the type and solubility of the resin component used.
  • Examples of the type of solvent include ketones, ethers, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated carbons, esters, water, alcohols, cellosolves, cellosolve acetates, sulfoxides, and amides.
  • ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and diacetone alcohol.
  • ether solvents include dioxane, tetrahydrofuran, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.
  • aliphatic hydrocarbon solvents include hexane.
  • alicyclic hydrocarbon solvents include cyclohexane.
  • aromatic hydrocarbon solvents include toluene and xylene.
  • halogenated carbon solvents include dichloromethane and dichloroethane.
  • ester solvents include methyl acetate, ethyl acetate, and butyl acetate.
  • alcohol solvents include ethanol, isopropanol, butanol, and cyclohexanol.
  • the curable resin composition may contain one or more of the solvents listed above.
  • the content ratio of the raw materials in the curable resin composition i.e., the solid content ratio, is not particularly limited.
  • the content ratio of the raw materials in the curable resin composition may be 5% by mass or more, or 25% by mass or more.
  • the content ratio of the raw materials in the curable resin composition may be 70% by mass or less, or 60% by mass or less.
  • the functional layer 20 is produced using a liquid curable resin composition containing an ultraviolet absorber.
  • the prepared curable resin composition is applied to the surface on which the functional layer 20 is to be produced to form a coating film of the curable resin composition.
  • the coating film of the curable resin composition is dried and the dried coating film is cured to obtain the functional layer 20.
  • the method for preparing the curable resin composition is not particularly limited.
  • the curable resin composition may be prepared using known devices such as a paint shaker, a bead mill, a kneader, or a mixer.
  • the method for applying the curable resin composition is not particularly limited.
  • the curable resin composition may be applied by a known method such as spin coating, dipping, spraying, die coating, bar coating, roll coating, meniscus coating, flexographic printing, screen printing, or pad coating.
  • the curing treatment of the curable resin composition may be performed by irradiation with ionizing radiation.
  • the ionizing radiation may be ultraviolet light or an electron beam.
  • ultraviolet light sources include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, metal halide lamps, etc.
  • the wavelength of the ultraviolet light may be in the wavelength range of 190 nm to 420 nm. It is preferable that the wavelength of the ultraviolet light used in the curing treatment is the central absorption wavelength of the photopolymerization initiator contained in the curable resin composition, or is close to the central absorption wavelength.
  • the wavelength of the ultraviolet light used in the curing treatment is away from the central absorption wavelength of the ultraviolet absorber contained in the curable resin composition.
  • the functional layer 20 can be sufficiently cured by the curing treatment by ultraviolet light irradiation.
  • the intermediate layer 30 is a layer adjacent to the functional layer 20 and the substrate layer 40.
  • the intermediate layer 30 may be a resin layer.
  • the intermediate layer 30 may be a layer having high adhesion to the substrate layer 40.
  • the intermediate layer 30 may be a layer having high adhesion to the functional layer 20.
  • the indentation hardness HB measured on the cross section of the intermediate layer 30 may be smaller than the indentation hardness HC measured on the cross section of the substrate layer 40.
  • the indentation hardness HB measured on the cross section of the intermediate layer 30 may be smaller than the indentation hardness HA1 measured on the cross section of the functional layer 20 at the first position 26.
  • the indentation hardness HB measured on the cross section of the intermediate layer 30 may be smaller than the indentation hardness HA2 measured on the cross section of the functional layer 20 at the second position 27.
  • the indentation hardness HB measured on the cross section of the intermediate layer 30 may be smaller than the indentation hardness HA measured on the cross section of the functional layer 20.
  • the indentation hardness HA is the arithmetic average of the indentation hardness HA1 at the first position 26, the indentation hardness HA2 at the second position 27, and the indentation hardness HA3 at the third position 28.
  • the presence of such intermediate layers 30 can improve the hardness of the first surface 11 of the optical sheet 10, and can improve the scratch resistance of the first surface 11 of the optical sheet 10.
  • the material of the intermediate layer 30 may be selected as follows.
  • the intermediate layer 30 may contain a thermoplastic resin.
  • the intermediate layer 30 may contain the same resin component as at least a portion of the resin component contained in the functional layer 20.
  • the intermediate layer 30 may contain one or more of an acrylic resin and a cellulose resin.
  • the intermediate layer 30 may contain a monomer.
  • the intermediate layer 30 may contain at least a portion of the monomer contained in the curable resin composition for producing the functional layer 20.
  • the intermediate layer 30 may be a mixed layer of the resin component of the functional layer 20 and the resin component of the base layer 40.
  • the intermediate layer 30 By forming the intermediate layer 30 as a mixed layer of the resin component of the functional layer 20 and the resin component of the base layer 40, the hardness of the first surface 11 of the optical sheet 10 can be improved, and the scratch resistance of the first surface 11 of the optical sheet 10 can be improved.
  • the intermediate layer 30 as a mixed layer may be a permeation layer in which the curable resin composition for producing the functional layer 20 is permeated into the base film 45.
  • the base film 40 and the intermediate layer 30 may both be composed of the base film 45 to which the curable resin composition for producing the functional layer 20 is applied.
  • the intermediate layer 30 may be composed of a portion of the base film 45 into which the curable resin composition has permeated (permeation layer).
  • the base layer 40 may be composed of a portion of the base film 45 into which the curable resin composition has not permeated.
  • the solvent contained in the curable resin composition easily penetrates the base film 45, so that the intermediate layer 30 can be stably formed as a penetration layer.
  • the solvent easily penetrates the base film 45.
  • the solvent easily penetrates cellulose-based resins, particularly triacetylcellulose (TAC).
  • TAC triacetylcellulose
  • the solvent also easily penetrates acrylic resins. Therefore, the base layer 40 and the base film 45 may contain one or more acrylic resins and cellulose resins.
  • the intermediate layer 30, which is a mixed layer of the resin components of the functional layer 20 and the resin components of the base layer 40 can be stably produced.
  • the produced intermediate layer 30 contains one or more acrylic resins and cellulose resins.
  • the ease of forming the penetration layer varies depending on the relationship between the curable resin compound and solvent contained in the curable resin composition and the substrate film 45.
  • the ease of forming the penetration layer also varies depending on the viscosity of the curable resin composition, the drying conditions of the coating of the curable resin composition, and the curing conditions of the coating of the curable resin composition. Therefore, the thickness T30 of the intermediate layer 30 as the penetration layer can be adjusted depending on the material contained in the curable resin composition, the material of the substrate film 45, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, etc.
  • the intermediate layer may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the functional layer.
  • the method for manufacturing the optical sheet 10 may include the following four steps.
  • the manufacturing method may further include a step of drying the coating film of the first curable resin composition before the step of curing the coating film of the first curable resin composition.
  • the manufacturing method may further include a step of drying the coating film of the second curable resin composition before the step of curing the coating film of the second curable resin composition.
  • the functional layer 20 can be formed by the first portion 20A and the second portion 20B.
  • the curable resin composition permeates the base film 45, thereby forming the intermediate layer 30 as a part of the base film 45.
  • the base layer 40 can be formed by the portion of the base film 45 that is not permeated by the curable resin composition.
  • the second portion 20B constitutes the surface portion of the functional layer 20.
  • the surface portion of the functional layer 20 is located near the first surface 11 or constitutes the first surface 11.
  • the first portion 20A constitutes the portion of the functional layer 20 that is bonded to the base film 45.
  • the first portion 20A is separated from the first surface 11.
  • the first curable resin composition and the second curable resin composition may be the same as the curable resin composition described above. However, the second curable resin composition may not contain an ultraviolet absorber.
  • the second curable resin composition may contain an ultraviolet absorber in a content smaller than the content of the first curable resin composition.
  • the second curable resin composition may contain an ultraviolet absorber in a content smaller than the content of the first curable resin composition.
  • the first curable resin composition contains more UV absorber. Therefore, the hardness of the first portion 20A is reduced.
  • the second curable resin composition does not contain UV absorber or contains only a small amount of UV absorber.
  • the coating film of the second curable resin composition can be irradiated with a sufficient amount of ionizing radiation, such as UV radiation, with sufficient strength. Therefore, the crosslinking reaction in the second portion 20B is promoted, and the hardness of the second portion 20B becomes hard. This allows the hardness of the first side 21 of the functional layer 20 to be improved while providing the functional layer 20 with UV cut function and blue light cut function due to the UV absorber.
  • the first portion 20A to which the first curable resin composition is applied may have a low hardness due to the inclusion of an ultraviolet absorber, which halts the crosslinking reaction. Therefore, the second curable resin composition may penetrate into the first portion 20A.
  • the first curable resin composition and the second curable resin composition are mixed, and the interface between the first portion 20A and the second portion 20B becomes inconspicuous. This significantly improves the adhesion between the first portion 20A and the second portion 20B.
  • the indentation hardness distribution defined by the above-mentioned condition (A) can then be imparted to the functional layer 20.
  • the indentation hardness gradient characteristic defined by condition (B) can be imparted to the functional layer 20.
  • the amount of the second curable resin composition applied may be greater than the amount of the first curable resin composition applied.
  • the UV absorbent is mainly dispersed in the first portion 20A.
  • the first portion 20A is covered by the high-hardness second portion 20B. Therefore, the UV absorbent can be effectively prevented from passing through the second portion 20B and bleeding out.
  • the second curable resin composition can penetrate not only into the first portion 20A but also into the base layer 40.
  • the amount of penetration of the first and second curable resin compositions into the base film 45 can be adjusted by the materials contained in the first and second curable resin compositions, the material of the base film 45, the preparation conditions of the first and second curable resin compositions, the drying conditions of the first and second curable resin compositions, the curing conditions of the first and second curable resin compositions, etc. Therefore, the thickness T30 of the intermediate layer 30 as a penetration layer can be adjusted with a high degree of freedom.
  • the above manufacturing method allows the spectral transmittance characteristics to be adjusted with a high degree of freedom.
  • the spectral transmittance characteristics can be adjusted by factors other than the type and total content of the ultraviolet absorbents contained in the first and second curable resin compositions.
  • the wavelength of the ultraviolet light used in the curing process is preferably away from the central absorption wavelength of the ultraviolet absorber contained in the curable resin composition. For this reason, in many conventional curable resin compositions, particularly ultraviolet curable resin compositions, contain only one type of ultraviolet absorber.
  • the spectral transmission characteristics can be adjusted by factors other than the type of UV absorbent and the total content of the UV absorbent.
  • the spectral transmission characteristics can be adjusted by the ratio of the content of the UV absorbent in the first curable resin composition to the content of the UV absorbent in the second curable resin composition.
  • the spectral transmission characteristics can be adjusted by the ratio of the content of the UV absorbent in the first curable resin composition to the content of the curable resin composition in the second curable resin composition.
  • the spectral transmission characteristics can be adjusted by one or more of the thickness of the first portion 20A, the thickness of the second portion 20B, and the ratio of the thickness of the first portion 20A to the thickness of the second portion 20B.
  • the coating of the second curable resin composition can be cured while avoiding the influence of the ultraviolet absorber contained in the first portion 20A.
  • the type, content, and content ratio of the ultraviolet absorber contained in the first curable resin composition and the first portion 20A of the functional layer 20 can be selected with a high degree of freedom. This allows the functional layer 20 and the optical sheet 10 to be given the desired spectral transmittance characteristics.
  • the ultraviolet absorber can be unevenly distributed in a portion of the functional layer 20 in the thickness direction, for example, the first portion 20A. Therefore, the ultraviolet absorber can be effectively utilized to efficiently capture ultraviolet light and blue light. From this point of view, the desired spectral transmission characteristics can be imparted to the functional layer 20 and the optical sheet 10. Furthermore, while imparting the desired spectral transmission characteristics to the optical sheet 10, the hardness and scratch resistance of the first surface 11 can be improved.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 380 nm is 1% or less.
  • the spectral transmittance of the optical sheet 10 at a wavelength of 440 nm is 70% or more.
  • a long sheet product 5 including a large number of optical sheets 10 can be manufactured as shown in Fig. 3.
  • the long sheet product 5 is cut to a predetermined size to obtain the optical sheets 10.
  • optical sheets 10 having various dimensions can be obtained from the long sheet product 5 in accordance with needs. Therefore, optical sheets 10 having various dimensions can be provided in a timely manner.
  • Fig. 3 by handling the sheet product 5 as a roll 7 wound around a winding core 6 centered on a winding axis RA, the handling of the sheet product 5 can be improved.
  • the method for manufacturing the optical sheet may further include a step of selecting the manufactured optical sheet 10.
  • the step of selecting the optical sheet 10 may include a step of measuring the spectral transmittance, a step of measuring the indentation hardness, and a step of selecting the optical sheet based on the measurement results.
  • the spectral transmittance at a wavelength of 380 nm and the spectral transmittance at a wavelength of 440 nm may be measured.
  • the indentation hardness in the cross section of the functional layer 20 may be measured. More specifically, the indentation hardness HA1 at the first position 26, the indentation hardness HA2 at the second position 27 at the cross section of the functional layer 20, and the indentation hardness HA3 at the third position 28 at the cross section of the functional layer 20 may be measured.
  • the first position 26 is located at the surface layer close to the first surface in the cross section.
  • the third position 28 is located at the surface layer close to the second surface in the cross section.
  • the second position 27 is located in the middle between the first position 26 and the third position 28.
  • the optical sheet may be selected based on the measured spectral transmittance and the measured indentation hardness.
  • a spectral transmittance of 1% or less at a wavelength of 380 nm may be acceptable.
  • a spectral transmittance of 70% or more at a wavelength of 440 nm may be acceptable.
  • the condition for acceptance may be that the functional layer 20 has the following characteristics (X) and (Y) regarding the indentation hardness HA1 at the first position 26 on the cross section of the functional layer 20, the indentation hardness HA2 at the second position 27 on the cross section of the functional layer 20, and the indentation hardness HA3 at the third position 28 on the cross section of the functional layer 20.
  • the optical sheet 10 selected as a good product has excellent ultraviolet blocking function and excellent blue light blocking function, and has high hardness on the first surface 11. This selection step makes it possible to select an optical sheet with excellent scratch resistance with high precision without performing scratch tests using felt or steel wool.
  • the optical sheet 10 according to the first embodiment may be applied to a polarizing plate 50.
  • An optical sheet 110 according to a second embodiment and an optical sheet 210 according to a third embodiment, which will be described later, may also be applied to the polarizing plate 50.
  • the polarizing plate 50 includes a first protective sheet 51, a polarizer 52, and a second protective sheet 53.
  • the first protective sheet 51 and the second protective sheet 53 sandwich the polarizer 52 between them and cover both sides.
  • At least one of the first protective sheet 51 and the second protective sheet 53 may include an optical sheet 10, 110, or 210.
  • the first protective sheet 51 includes the optical sheet 10, 110, or 210.
  • the optical sheet 10, 110, or 210 may block light with a wavelength of 380 nm or less contained in the light incident on the polarizing plate 50 with high efficiency. This can suppress deterioration of the polarizer 52 caused by blue light.
  • the polarizer 52 transmits one linearly polarized component and blocks the other linearly polarized component.
  • the polarizer 52 may be an absorptive polarizer that absorbs the other linearly polarized component.
  • the polarizer 52 may be a reflective polarizer that reflects the other linearly polarized component.
  • the polarizer 52 may be a sheet-type polarizer such as a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, or an ethylene-vinyl acetate copolymer saponified film that has been dyed with iodine or the like and stretched.
  • the polarizer 52 may be a wire-grid type polarizer made of a large number of metal wires arranged in parallel.
  • the polarizer 52 may be a coating type polarizer coated with lyotropic liquid crystal or a dichroic guest-host material.
  • the polarizer 52 may be a multilayer thin-film type polar
  • the polarizing plate 50 is not limited to the configuration shown in FIG. 4.
  • the polarizing plate 50 may include a quarter-phase plate in addition to the optical sheets 10, 110, and 210 and the polarizer 52.
  • This polarizing plate 50 functions as a circular polarizing plate.
  • the polarizing plate 50 as a circular polarizing plate has the function of suppressing reflection.
  • the optical sheet 10 according to the first embodiment may be applied to a touch panel member 55.
  • An optical sheet 110 according to a second embodiment and an optical sheet 210 according to a third embodiment, which will be described later, may also be applied to the touch panel member 55.
  • the touch panel member 55 has optical sheets 10, 110, 210 and an electrode layer 56.
  • the touch panel member 55 is a member that constitutes a touch panel.
  • the touch panel member 55 outputs the approach or contact of a detection object such as a finger or pen as an electrical state change.
  • a controller electrically connected to the touch panel member 55 can identify the position of the detection object based on the output from the touch panel member 55.
  • the first surface of the optical sheets 10, 110, 210 has high hardness and excellent scratch resistance. Therefore, when the detection object is rubbed against the first surface, scratches on the first surface can be suppressed.
  • the electrode layer 56 includes a conductor for detecting the contact position.
  • the configuration of the conductor is appropriately selected depending on the method by which the touch panel detects contact.
  • the electrode layer 56 may include a conductor that spreads in a planar shape without being divided into regions.
  • the electrode layer 56 may include multiple conductors. The multiple conductors may be arranged in one direction, and each conductor may extend in a direction perpendicular to the one direction.
  • the conductor included in the electrode layer 56 may be a film formed from a transparent conductive material.
  • transparent conductive materials include metal oxides such as indium tin oxide (ITO).
  • ITO indium tin oxide
  • the conductor included in the electrode layer 56 may include metal wires arranged in a mesh pattern.
  • the optical sheet 10 according to the first embodiment may be applied to the display device 60.
  • An optical sheet 110 according to a second embodiment and an optical sheet 210 according to a third embodiment, which will be described later, may also be applied to the display device 60. .
  • the display device 60 includes a display element 61 and optical sheets 10, 110, 210.
  • the display element 61 has a display surface 61a that displays an image.
  • the optical sheets 10, 110, 210 are overlaid on the display element 61 with their second surfaces facing the display surface 61a.
  • the optical sheets 10, 110, 210 may be bonded to the display element 61 via a bonding layer including an adhesive, a sticky material, or the like.
  • the optical sheets 10, 110, 210 may be incorporated into the display device 60 as part of the polarizing plate 50 or the touch panel member 55.
  • the image light emitted from the display element 61 passes through the optical sheets 10, 110, and 210.
  • the optical sheets 10, 110, and 210 may block light with wavelengths of 380 nm or less contained in the image light with high efficiency. This can reduce the burden on the observer, such as eye strain.
  • the optical sheets 10, 110, and 210 block light with wavelengths of 410 nm or less from the external light entering the display device 60. This can prevent the polarizer 52 of the polarizing plate 50 and the EL elements of the organic EL panel from being deteriorated by blue light contained in the external light.
  • the first surface of the optical sheets 10, 110, and 210 has a sufficiently high hardness. Therefore, the optical sheets 10, 110, and 210 can protect the display surface 61a of the display device 60. In addition, since scratches on the first surface can be suppressed, the display device 60 can display high-quality images.
  • the display element 61 is not particularly limited. Examples of the display element 61 include a liquid crystal display element, an EL display element, a plasma display element, an electronic paper element, etc.
  • the first curable resin composition 1A was applied onto a substrate film made of triacetyl cellulose having a thickness of 80 ⁇ m, and a first coating film was formed on the substrate film.
  • the method for producing the first curable resin composition 1A will be described later.
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.4 m/s).
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.5 m/s). The above caused the solvent to volatilize.
  • the first coating film was irradiated with ultraviolet light at an integrated light amount of 66 mJ/cm 2.
  • the first coating film was cured by irradiation with ultraviolet light, and the first portion of the functional layer was formed on the substrate film.
  • the amount of application of the first curable resin composition 1A was set to an amount that would produce a first portion with a dry thickness of 3.4 ⁇ m, assuming that there was no penetration into the substrate film.
  • the second curable resin composition 1A having the following formulation was applied onto the first portion to form a second coating film on the substrate film.
  • the solid content of the second curable resin composition 1A was 45%.
  • the second curable resin composition 1A did not contain an ultraviolet absorber.
  • the second coating film was dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s).
  • the second coating film was dried under the conditions of 70°C x 20 seconds (drying air speed 0.3 m/s). The above caused the solvent to volatilize.
  • the second coating film was irradiated with ultraviolet light at an integrated light amount of 288 mJ/ cm2 .
  • the second coating film was cured by irradiation with ultraviolet light, and the second portion of the functional layer was prepared on the substrate film and the first portion.
  • the amount of application of the second curable resin composition 1A was set to an amount that would produce a second portion with a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate layer or the first portion.
  • Example 11 As a result of the above, an optical sheet according to Example 11 was obtained.
  • the first portion and the second portion constituted a functional layer.
  • the cross section of the optical sheet of Example 11 was observed during the thickness measurement described below.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used to observe the cross section.
  • the cross section was observed at an acceleration voltage of 10 kV to 30 kV and a magnification of 5000 times, it was found that the curable resin composition had penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer. Furthermore, the interface between the first and second parts in the functional layer could not be observed.
  • the contents in the four-neck flask were refluxed and dehydrated at 110-115°C for 4 hours.
  • 30 mL of water and 0.6 g (0.006 mol) of sodium carbonate were added to the four-neck flask.
  • the four-neck flask was then left to stand, and the lower aqueous layer was separated and removed.
  • 0.2 g of activated carbon was added to the four-neck flask, and the contents were refluxed and stirred to decolorize.
  • the contents removed from the four-neck flask were then filtered. 40 mL of toluene was collected from the obtained filtrate under reduced pressure.
  • An intermediate composition was prepared by mixing the following: - Multifunctional monomer (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded (a polymer in which a sesamol-type benzotriazole monomer is reactively bonded to MMA and an ultraviolet absorber at a mass ratio X of 40 parts by mass) Solvent (a mixture of MEK and toluene in a mass ratio of 30:70) The polyfunctional monomer and the acrylic polymer (1) were mixed in a solid content mass ratio of 30:70.
  • - Multifunctional monomer PT-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.
  • Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded a polymer in which a sesamol-type benzotriazole monomer is reactively
  • the obtained intermediate composition was mixed with a photopolymerization initiator (4 parts by mass of Irgacure 819, manufactured by BASF) and a leveling agent (0.2 parts by mass of LE-304, manufactured by Kyoeisha) and thoroughly stirred to prepare a first curable resin composition 1A.
  • the obtained first curable resin composition 1A contained 25% solids.
  • UV-curable acrylate-containing composition 50 parts by mass (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass of ultraviolet-curable urethane acrylate-containing composition (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577")
  • Leveling agent 0.4 parts by mass (Kyoeisha, product name "LE-304”)
  • Photopolymerization initiator 4 parts by mass IGM Resins, trade name "Omnirad184”
  • Lubricant 20 parts by mass (CIK Nanotech, SIRMIBK15WT%-E65)
  • Solvent a mixture of methyl isobutyl ketone and methyl ethyl ketone in a mass ratio of 55:48)
  • Example 12 differs from the above-mentioned Example 11 in that the coating amount of the first curable resin composition 1A was increased, but otherwise the optical sheet of Example 12 was obtained using the same materials and the same method as in Example 11.
  • the coating amount of the first curable resin composition 1A was set to an amount that would produce a first portion with a dry thickness of 4.0 ⁇ m, assuming that there was no penetration into the base film.
  • Example 12 When measuring the thickness as described below, the cross section of the optical sheet of Example 12 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 13 differs from Example 11 in that the solid content ratio of the first curable resin composition was changed, the solid content ratio of the second curable resin composition was changed, and the amount of the second curable resin composition applied was increased.
  • the optical sheet of Example 13 was obtained using the same materials and the same method as Example 11.
  • a first curable resin composition having a solid content of 35% was used.
  • the first curable resin composition used in Example 13 was obtained by adjusting the amount of solvent contained in the first curable resin composition 1A.
  • a second curable resin composition having a solid content of 50% was used.
  • the second curable resin composition used in Example 13 was obtained by adjusting the amount of solvent contained in the second curable resin composition 1A.
  • the amount of the second curable resin composition applied was set to an amount that would produce a second portion with a dry thickness of 6.0 ⁇ m, assuming that there was no penetration into the base film and the first portion.
  • Example 13 When measuring the thickness as described below, the cross section of the optical sheet of Example 13 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 14 differs from Example 11 above in that the solid content ratio of the first curable resin composition and the solid content ratio of the second curable resin composition were changed, and the optical sheet of Example 14 was obtained by the same materials and the same method as Example 11 in other respects.
  • a first curable resin composition having a solid content of 20% was used.
  • the first curable resin composition used in Example 14 was obtained by adjusting the amount of solvent contained in the first curable resin composition 1A.
  • a second curable resin composition having a solid content of 40% was used.
  • the second curable resin composition used in Example 14 was obtained by adjusting the amount of solvent contained in the second curable resin composition 1A.
  • Example 14 When measuring the thickness as described below, the cross section of the optical sheet of Example 14 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 15 differs from Example 11 above in that the amount of the first curable resin composition 1A applied was reduced and the amount of the second curable resin composition 1A applied was reduced.
  • the optical sheet of Example 15 was obtained by using the same materials and the same method as Example 11.
  • the amount of the first curable resin composition 1A applied was set to an amount that would produce a first portion with a dry thickness of 1.7 ⁇ m, assuming that there was no penetration into the base film.
  • the amount of the second curable resin composition applied was set to an amount that would produce a second portion with a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the base film and the first portion.
  • Example 15 When measuring the thickness as described below, the cross section of the optical sheet of Example 15 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 16 differs from Example 11 in that the composition of the first curable resin composition was changed, the amount of the first curable resin composition applied was increased, and the amount of the second curable resin composition 1A applied was increased.
  • the optical sheet of Example 16 was obtained using the same materials and methods as Example 11.
  • the first curable resin composition 1A used in Example 11 contained a polyfunctional monomer and an acrylic polymer (1) mixed in a solid content mass ratio of 30:70.
  • the first curable resin composition used in Example 16 was obtained by mixing a polyfunctional monomer and an indole-based ultraviolet absorber mixed in a mass ratio of 95:5 instead of the polyfunctional monomer and acrylic polymer (1) of the first curable resin composition 1A.
  • the polyfunctional monomer contained in the first curable resin composition used in Example 16 was the same as the polyfunctional monomer contained in the first curable resin composition 1A.
  • the indole-based ultraviolet absorber contained in the first curable resin composition used in Example 16 was a product name "BONASORB UA-3912" manufactured by Orient Chemical Industry Co., Ltd.
  • the solid content of the first curable resin composition used in Example 16 was 25%, which was the same as the solid content of the first curable resin composition 1A.
  • the amount of the first curable resin composition applied was set to an amount that would create a first portion with a dry thickness of 4.0 ⁇ m, assuming no penetration into the base film.
  • the amount of the second curable resin composition 1A applied was set to an amount that would create a second portion with a dry thickness of 7.0 ⁇ m, assuming no penetration into the base film or the first portion.
  • Example 16 When measuring the thickness as described below, the cross section of the optical sheet of Example 16 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 17 differs from Example 11 above in that the amount of the first curable resin composition 1A applied was increased and the amount of the second curable resin composition 1A applied was decreased, and the optical sheet of Example 15 was obtained by the same materials and the same method as Example 11 in other respects.
  • the amount of the first curable resin composition 1A applied was an amount that would produce a first portion with a dry thickness of 5.1 ⁇ m, assuming that there was no penetration into the base film.
  • the amount of the second curable resin composition applied was an amount that would produce a second portion with a dry thickness of 3.0 ⁇ m, assuming that there was no penetration into the base film and the first portion.
  • Example 17 When measuring the thickness as described below, the cross section of the optical sheet of Example 17 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Example 18 differs from Example 11 in that the leveling agent of the first curable resin composition 1A was omitted and that the leveling agent of the second curable resin composition 1A was changed, and the optical sheet of Example 18 was obtained using the same materials and the same method as Example 11 in other respects.
  • the first curable resin composition used to form the first coating film differs from the first curable resin composition 1A described above in that the leveling agent "Kyoeisha, LE-304, 0.2 parts by mass" was omitted, and the other respects were the same as the first curable resin composition 1A described above.
  • Example 18 the second curable resin composition used to form the second coating film differed from the second curable resin composition 1A described above in that the leveling agent "DIC, F-477, 0.3 parts by mass” was used instead of the leveling agent "Kyoeisha, LE-304, 0.4 parts by mass”.
  • the second curable resin composition used to form the second coating film was the same as the above-mentioned second curable resin composition 1A except for the leveling agent.
  • Example 18 When measuring the thickness as described below, the cross section of the optical sheet of Example 18 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • the amount of the first curable resin composition 1A applied was set to an amount that would produce a first portion having a dry thickness of 5.7 ⁇ m, assuming that there was no penetration into the substrate film.
  • an optical sheet according to Comparative Example 11 was obtained. That is, in the optical sheet according to Comparative Example 11, the functional layer was composed only of the first portion prepared using the first curable resin composition 1A.
  • the thickness of the layer produced using the first curable resin composition 1A in Comparative Example 11 was different from the thickness of the layer produced using the first curable resin composition 1A in Example 11.
  • the method and conditions for producing the functional layer using the first curable resin composition 1A in Comparative Example 11 were the same as the method and conditions for producing the first part using the first curable resin composition 1A in Example 11.
  • Example 11 When measuring the thickness as described below, the cross section of the optical sheet according to Comparative Example 11 was observed in the same manner as in Example 11.
  • the first curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • a first curable resin composition 1B having the following formulation was applied onto a substrate film made of triacetyl cellulose having a thickness of 80 ⁇ m, and a first coating film was formed on the substrate film.
  • the solid content of the first curable resin composition 1B was 45%.
  • the first curable resin composition 1B did not contain an ultraviolet absorber.
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.4 m/s).
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.5 m/s). The above caused the solvent to volatilize.
  • the first coating film was irradiated with ultraviolet light at an integrated light amount of 66 mJ/cm 2.
  • the first coating film was cured by irradiation with ultraviolet light, and the first portion of the functional layer was formed on the substrate film.
  • the amount of application of the first curable resin composition 1B was set to an amount that would produce a first portion with a dry thickness of 4.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • UV-curable acrylate-containing composition 50 parts by mass (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass of ultraviolet-curable urethane acrylate-containing composition (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577")
  • Leveling agent 0.4 parts by mass (Kyoeisha, product name "LE-304”)
  • Photopolymerization initiator 4 parts by mass IGM Resins, trade name "Omnirad184”
  • Solvent a mixture of methyl isobutyl ketone and methyl ethyl ketone in a mass ratio of 55:48)
  • the second curable resin composition was applied onto the first portion to form a second coating film on the substrate film.
  • the first curable resin composition 1A used in Example 11 was used as the second curable resin composition.
  • the solid content of the second curable resin composition used in Comparative Example 12 was 25%.
  • the second curable resin composition used in Comparative Example 12 contained an ultraviolet absorber.
  • the second coating film was dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s). Thereafter, the second coating film was dried under the conditions of 70°C x 20 seconds (drying air speed 0.3 m/s). As a result, the solvent was volatilized.
  • the second coating film was irradiated with ultraviolet light at an integrated light amount of 288 mJ/ cm2 .
  • the second coating film was cured by irradiation with ultraviolet light to prepare the second portion of the functional layer on the substrate film and the first portion.
  • the amount of the second curable resin composition 1A applied was set to an amount sufficient to produce a second portion having a dry thickness of 3.5 ⁇ m, on the assumption that the composition would not penetrate into the base layer or the first portion.
  • an optical sheet according to Comparative Example 12 was obtained.
  • the functional layer was formed by the first portion and the second portion.
  • the cross section of the optical sheet according to Comparative Example 12 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Comparative Example 13 differs from Comparative Example 11 in that the composition of the first curable resin composition was changed, the amount of the first curable resin composition applied was increased, and the cumulative amount of ultraviolet light irradiated during curing of the first coating film was increased.
  • the optical sheet of Comparative Example 13 was obtained using the same materials and methods as Comparative Example 11.
  • the first curable resin composition 1A used in Comparative Example 11 and Example 11 contained a polyfunctional monomer and an acrylic polymer (1) mixed in a solid content mass ratio of 30:70.
  • the first curable resin composition used in Comparative Example 13 contained a polyfunctional monomer and an acrylic polymer (1) mixed in a solid content mass ratio of 60:40.
  • the polyfunctional monomer contained in the first curable resin composition used in Comparative Example 13 was the same as the polyfunctional monomer contained in the first curable resin composition 1A.
  • the acrylic polymer (1) contained in the first curable resin composition used in Comparative Example 12 was the same as the acrylic polymer (1) contained in the first curable resin composition 1A.
  • the solid content of the first curable resin composition used in Comparative Example 13 was 25%, which was the same as the solid content of the first curable resin composition 1A.
  • the amount of the first curable resin composition applied was set to an amount sufficient to produce a functional layer having a dry thickness of 7.5 ⁇ m and consisting of only the first portion, assuming that the composition did not penetrate into the substrate film.
  • the cumulative amount of ultraviolet light irradiated during curing of the first coating film was 132 mJ/ cm2 .
  • Example 11 During thickness measurement described below, the cross section of the optical sheet according to Comparative Example 13 was observed in the same manner as in Example 11.
  • the first curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • a first curable resin composition 1C having the following formulation was applied onto a substrate film made of triacetyl cellulose having a thickness of 80 ⁇ m, and a first coating film was formed on the substrate film.
  • the solid content of the first curable resin composition 1C was 45%.
  • the first curable resin composition 1C did not contain an ultraviolet absorber.
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.4 m/s).
  • the first coating film was dried under the condition of 50° C. ⁇ 20 seconds (drying air speed 0.5 m/s). The above caused the solvent to volatilize.
  • the first coating film was irradiated with ultraviolet light at an integrated light amount of 132 mJ/cm 2.
  • the first coating film was cured by irradiation with ultraviolet light, and the first portion of the functional layer was formed on the substrate film.
  • the amount of application of the first curable resin composition 1C was set to an amount that would produce a first portion with a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • UV-curable acrylate-containing composition 50 parts by mass (DPHA (dipentaerythritol hexaacrylate), manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass of ultraviolet-curable urethane acrylate-containing composition (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577”) Leveling agent: 0.4 parts by mass (Kyoeisha, product name "LE-304”) ⁇ Photopolymerization initiator 4 parts by mass (IGM Resins, trade name "Omnirad184”) Solvent (a mixture of methyl isobutyl ketone and methyl ethyl ketone in a mass ratio of 55:48)
  • DPHA dipentaerythritol hexaacrylate
  • UV-curable urethane acrylate-containing composition manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577
  • Leveling agent 0.4 parts by mass (Kyoeisha
  • the second curable resin composition was applied onto the first portion to form a second coating film on the substrate film.
  • the first curable resin composition 1A used in Example 11 was used as the second curable resin composition.
  • the solid content of the second curable resin composition used in Comparative Example 14 was 25%.
  • the second curable resin composition used in Comparative Example 14 contained an ultraviolet absorber.
  • the second coating film was dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s). Thereafter, the second coating film was dried under the conditions of 70°C x 20 seconds (drying air speed 0.3 m/s). As a result, the solvent was volatilized.
  • the second coating film was irradiated with ultraviolet light at an integrated light amount of 288 mJ/ cm2 .
  • the second coating film was cured by irradiation with ultraviolet light to prepare the second portion of the functional layer on the substrate film and the first portion.
  • the amount of the second curable resin composition 1A applied was set to an amount sufficient to produce a second portion having a dry thickness of 3.5 ⁇ m, on the assumption that the composition would not penetrate into the base layer or the first portion.
  • an optical sheet according to Comparative Example 14 was obtained.
  • the functional layer was formed by the first portion and the second portion.
  • the cross section of the optical sheet according to Comparative Example 14 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the intermediate layer.
  • the interface between the first and second parts in the functional layer could not be observed.
  • Comparative Example 15 differs from the above-mentioned Comparative Example 13 in that the leveling agent of the first curable resin composition and the leveling agent of the second curable resin composition were changed, but otherwise the optical sheet of Comparative Example 15 was obtained using the same materials and method as Comparative Example 13.
  • the first curable resin composition used to form the first coating film differed from the first curable resin composition used in Comparative Example 13 in that the leveling agent "0.2 parts by mass of F-568 manufactured by DIC” was used instead of the leveling agent "0.2 parts by mass of LE-304 manufactured by Kyoeisha.”
  • the first curable resin composition used to form the first coating film was the same as the first curable resin composition used in Comparative Example 13, except for the leveling agent.
  • the second curable resin composition used to form the second coating film differed from the second curable resin composition 1A used in Comparative Example 13 in that the leveling agent "0.4 parts by mass of F-477 manufactured by DIC” was used instead of the leveling agent "0.4 parts by mass of LE-304 manufactured by Kyoeisha.”
  • the second curable resin composition used to form the second coating film was the same as the second curable resin composition 1A used in Comparative Example 13, except for the leveling agent.
  • the cross section of the optical sheet according to Comparative Example 15 was observed in the same manner as in Example 11.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Thickness>> A sample for thickness measurement was prepared by the following first and second steps.
  • the embedded sample was prepared using the following procedure. First, the cut sample was placed in a silicon embedding plate. Embedding resin was poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin was allowed to harden within the silicon embedding plate. Next, the cut sample and the embedding resin surrounding it were removed from the silicon embedding plate to obtain an embedded sample. The embedded sample was shaped like a block.
  • the silicon embedding plate used was manufactured by Dosaka EM.
  • the embedding resin was epoxy resin.
  • the embedding resin was obtained by mixing Struers' product name "Epofix” and the same company's product name "Epofix Hardener” in a ratio of 10:1.2.
  • the embedding resin was allowed to harden by leaving it at room temperature for 12 hours.
  • the block-shaped embedded sample was cut with a diamond knife to prepare a slice sample.
  • the slice sample was aligned along the first direction (thickness direction, lamination direction) of the target optical sheet.
  • slice samples without defects such as holes and with a uniform thickness of about 60 nm to 100 nm were used as thickness measurement samples.
  • microtome was used to cut the embedded samples.
  • the microtome was an Ultramicrotome EM UC7 manufactured by Leica Microsystems. When cutting the block-shaped embedded sample, it was first roughly cut as coarse trimming, and finally, precisely trimmed with a diamond knife to obtain a section sample.
  • the thickness of each layer was measured using the observation image of the thickness measurement sample by a scanning transmission electron microscope.
  • the thickness measurement sample was stained. Osmium tetroxide was used for staining.
  • the stained thickness measurement sample was imaged using a scanning transmission electron microscope to obtain an observation image of the thickness measurement sample.
  • the scanning transmission electron microscope used was an S4800 manufactured by Hitachi High-Tech Corporation.
  • the imaging conditions were as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • Ten observation images were taken from one thickness measurement sample for each example.
  • the ten observation images were taken at ten observation positions (measurement positions) spaced at a pitch of 10 ⁇ m apart in a direction perpendicular to the first direction of the optical sheet in question.
  • the functional layer thickness T20 ( ⁇ m) and intermediate layer thickness T30 ( ⁇ m) for the optical sheet in each example were measured.
  • the arithmetic mean value of the ten thickness measurements from the ten observation images was taken as the thickness of the target layer.
  • the measurement results for the functional layer thickness T20 ( ⁇ m) and the intermediate layer thickness T30 ( ⁇ m) are shown in Table 1.
  • Spectral transmittance >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The spectral transmittance (%) was measured. The spectral transmittance (%) was measured for each wavelength at intervals of 0.5 nm within the wavelength range of 379.5 nm to 440.5 nm. The measurement was performed using an ultraviolet-visible spectrophotometer "UV-2600" manufactured by Nippon Bunko Co., Ltd. Using the measured value of the spectral transmittance, each wavelength in the range of 380 nm to 440 nm at intervals of 0.5 nm was measured.
  • UV-2600 ultraviolet-visible spectrophotometer
  • the slope of the spectral transmittance at wavelength was calculated.
  • the slope of the spectral transmittance at wavelength X was calculated by subtracting the spectral transmittance (%) at wavelength X+0.5 (nm) from the spectral transmittance (%) at wavelength X-0.5 (nm).
  • the measurement results of the spectral transmittance at 380.0 nm and the spectral transmittance at 440.0 nm are shown in Tables 1 and 2.
  • the wavelengths at which the slope of the spectral transmittance is maximum are shown in Tables 1 and 2.
  • optical sheets according to Examples 11 to 18 and Comparative Examples 11 to 15 were placed on the display surface of a commercially available organic EL display device, and the image displayed by the organic EL display device was observed through the optical sheet.
  • Examples 11 to 18 and Comparative Examples 11 to 15 there was no noticeable change in color between the image when the optical sheet was installed and the image when the optical sheet was not installed, and it was within the range that could be considered an acceptable product.
  • Examples 11 to 16, Example 18, and Comparative Examples 11 to 15 there was no noticeable change in color between the image when the optical sheet was installed and the image when the optical sheet was not installed.
  • Pencil hardness >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The pencil hardness was measured using a pencil hardness tester manufactured by Toyo Seiki Seisakusho Co., Ltd. The pencil hardness evaluated according to the above-mentioned evaluation criteria is shown in Table 1.
  • the sample was placed on the base plate with the second surface of the optical sheet in contact with the base plate.
  • the height of the four corners of the sample from the base plate was measured as the float (mm).
  • the maximum of the four float measurements taken for one sample was taken as the float for that sample.
  • the float was measured for each of the three samples.
  • the arithmetic mean value of the three float measurements was taken as the deformation amount for that example.
  • the deformation amount measurement results are shown in Table 1.
  • Measurement conditions Measurement method: Wide/Narrow X-ray source: Monochrome A1K ⁇ X-ray output: 150W Emission current: 10mA Acceleration voltage: 15 kV Charge neutralization mechanism: ON Measurement area: 300 ⁇ m x 700 ⁇ m Pass Energy: Survey: 160eV, Narrow: 40eV Photoelectron capture angle: 90° Auto Z: ON Peak shift correction: Correction was made so that the C-C peak in the C1s peak was 285.0 eV. Waveform separation of narrow peaks: Executed using the GL function in the analysis software attached to the device. Etching ions: Ar monoatomic ions
  • Table 2 shows the percentage (%) of the amount of each element detected, with the total amount of elements detected being 100.
  • Example 11 the ratio of silicon element to carbon element was 0.02 (2%) or more.
  • the cross section of the functional layer in Example 11 was observed.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used for the cross section observation. When the cross section was observed at an acceleration voltage of 10 kV to 30 kV and a magnification of 5000 times, the silica added as a lubricant was dispersed without being unevenly distributed in aggregate.
  • the epoxy resin used for embedding was obtained by mixing Struers' product name "Epofix” with the same company's product name “Epofix Hardener” in a ratio of 10:1.2.
  • a microtome was used to cut the embedded samples.
  • the microtome used was Leica Microsystems' product name "Ultramicrotome EM UC7.”
  • the indentation hardness (MPa) of the cross section of the slice samples of the optical sheet according to each example was measured using the method described above.
  • the indentation hardness (MPa) was measured using a measuring device "TI-950 TriboIndenter” manufactured by BRUKER.
  • the indenter used to measure the indentation hardness (MPa) was "TI-0039" manufactured by BRUKER.
  • the following measurement results for indentation hardness (MPa) are shown in Table 1.
  • the indentation hardness in the cross section of each layer was the arithmetic average value of the indentation hardness measured at 10 measurement positions.
  • the 10 measurement positions were 10 positions on one slice sample, spaced apart at 5 ⁇ m intervals in a direction perpendicular to the first direction of the optical sheet.
  • Total light transmittance >> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The total light transmittance was measured. A haze meter "HM-150" manufactured by Murakami Color Research Laboratory was used to measure the total light transmittance. The measurement results of the total light transmittance are shown in Table 2.
  • Yellowness index YI value>> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and comparative examples. The samples were visually confirmed to be free of any abnormalities such as dust or scratches. The yellowness index YI value of the optical sheets according to each example was measured by the method described above. The yellowness index YI value was measured using an ultraviolet-visible spectrophotometer "UV-2600" manufactured by Shimadzu Corporation. The measurement results of the yellowness index YI value are shown in Table 2.
  • the optical sheet 110 includes a first layer 120.
  • the first layer 120 includes a cured product of a curable resin composition and an ultraviolet absorber.
  • the first layer 120 including the ultraviolet absorber provides the optical sheet 110 with a blue light blocking function.
  • the optical sheet 110 has a spectral transmittance of 15% or less at a wavelength of 410 nm.
  • the optical sheet 110 has a spectral transmittance of 70% or more at a wavelength of 440 nm.
  • the optical sheet 110 may block light having a wavelength of 410 nm or less with high efficiency.
  • the optical sheet 110 may transmit light having a wavelength of 440 nm or more with high transmittance.
  • the optical sheet 110 blocks light with a wavelength of 410 nm or less, thereby suppressing problems caused by blue light.
  • image light emitted from the display device 60 can pass through the optical sheet 110.
  • the optical sheet 110 can block light with a wavelength of 410 nm or less from the image light.
  • eye strain of the observer of the image can be alleviated.
  • external light such as sunlight can be incident on the optical sheet 110.
  • deterioration of the EL element (organic electroluminescence element) of an organic EL panel (organic electroluminescence panel) can be suppressed.
  • deterioration of the polarizer 52 of the polarizing plate 50 can be suppressed.
  • Light with a wavelength of 440 nm or more can pass through the optical sheet 110 with high transmittance. This makes it possible to suppress changes and deterioration in the color of the image observed through the optical sheet 110.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be 15% or less, 14% or less, 13% or less, 12% or less, or 10% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be 0% or more, greater than 0%, 2% or more, or 5% or more.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be 0% or more and 15% or less, 0% or more and 14% or less, 0% or more and 13% or less, 0% or more and 12% or less, or 0% or more and 10% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be greater than 0% and 15% or less, greater than 0% and 14% or less, greater than 0% and 13% or less, greater than 0% and 12% or less, or greater than 0% and 10% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be 2% or more and 15% or less, greater than 2% and 14% or less, greater than 2% and 13% or less, greater than 2% and 12% or less, or greater than 2% and 10% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 410 nm may be 5% or more and 15% or less, 5% or more and 14% or less, 5% or more and 13% or less, 5% or more and 12% or less, or 5% or more and 10% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 440 nm may be 70% or more, 75% or more, 80% or more, or 85% or more.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 440 nm may be 100% or less, or may be less than 100%.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 440 nm may be 70% or more and 100% or less, 75% or more and 100% or less, 80% or more and 100% or less, or 85% or more and 100% or less.
  • the spectral transmittance of the optical sheet 110 at a wavelength of 440 nm may be 70% or more and less than 100%, 75% or more and less than 100%, 80% or more and less than 100%, or 85% or more and less than 100%.
  • the method for measuring the spectral transmittance is the same as that described in the first embodiment.
  • the first layer 120 further includes a cured product of the curable resin composition.
  • the cured product of the curable resin composition is also referred to as a resin cured product.
  • the resin cured product can impart high hardness to the first layer 120 and the optical sheet 110.
  • the first layer 120 functions as a so-called hard coat layer.
  • the optical sheet 110 with improved hardness has excellent scratch resistance. When the optical sheet 110 is in use, scratches on the optical sheet 110 can be suppressed.
  • the optical sheet 110 is also suitable for a touch panel member 55 (see FIG. 5) that is expected to come into contact with a finger or a pen during use.
  • a resin layer containing a cured resin product is obtained by curing a coating film of a curable resin composition.
  • the coating film can be cured by exposing the coating film to light, which promotes a crosslinking reaction. High-energy short-wavelength light is usually used for exposure.
  • the ultraviolet absorber added to the curable resin composition can absorb the light used in the curing process of the coating film. In other words, the ultraviolet absorber can inhibit the curing process of the curable resin composition.
  • the scratch resistance may be significantly reduced. If the hardness of the resin layer containing the cured resin is low, the UV absorber may bleed out of the resin layer when the optical sheet is used. If the UV absorber bleeds out, the blue light blocking function of the optical sheet 110 will also be insufficient.
  • a measure is taken to improve the hardness of the first layer 120 and the optical sheet 110.
  • the optical sheet 110 according to the second embodiment includes a second layer 130 adjacent to the first layer 120.
  • the thickness ratio is 1.5 or more and 7.5 or less.
  • the thickness ratio is determined using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 110 to be evaluated is observed with a scanning transmission electron microscope, and the thicknesses T120 and T130 are measured from the image observed with the scanning transmission electron microscope.
  • the thickness ratio at the measurement position is calculated from the thickness T120 of the first layer 120 and the thickness T130 of the second layer 130 measured at the same position in a direction perpendicular to the thickness direction observed with the scanning transmission electron microscope.
  • the thicknesses T120 and T130 are measured at 10 measurement positions, and the 10 thickness ratios are calculated.
  • the thickness ratio of the optical sheet 110 is determined as the arithmetic mean value of the 10 thickness ratios.
  • the observation image of the cross section of the optical sheet 110 to be evaluated is obtained by observing the thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained by the following first and second steps.
  • a cut sample is cut out from the optical sheet to be evaluated.
  • the cut sample is visually checked for any abnormalities such as dirt or scratches.
  • the cut sample is embedded in resin to prepare an embedded sample.
  • the embedded sample is prepared as follows. First, the cut sample is placed in a silicon embedding plate. Embedding resin is poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin is hardened inside the silicon embedding plate. Next, the cut sample and the embedding resin that encases it are removed from the silicon embedding plate to obtain the embedded sample. The embedded sample is shaped like a block.
  • the embedding resin is epoxy resin.
  • the block-shaped embedded sample is cut to prepare a slice sample.
  • the slice sample includes a surface along a first direction (thickness direction, lamination direction) of the target optical sheet.
  • a slice sample that is free of defects such as holes and has a uniform thickness of about 60 nm to 100 nm is used as a thickness measurement sample.
  • the imaging conditions of the scanning transmission electron microscope are as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • the optical sheet 110 may include a first surface 111 and a second surface 112 that face each other in a first direction D1.
  • the first surface 111 and the second surface 112 constitute a pair of main surfaces of the optical sheet 110.
  • the first direction D1 is the stacking direction of the multiple layers included in the optical sheet 110. From the first surface 111 to the second surface 112 in the first direction D1, the first layer 120 and the second layer 130 are positioned in this order.
  • the hardness of the first layer 120 is improved. This improves the hardness of the first surface 111, and also improves the scratch resistance of the first surface 111.
  • the pencil hardness of the first surface 111 can be made 2H or more.
  • the load capacity of the first surface 111 in a steel wool scratch resistance test can be made 200 g or more.
  • the indentation hardness of the cross section of the first layer 120 with an indentation depth of 100 nm can be made 350 MPa or more.
  • Pencil hardness is an index that indicates resistance to defects such as scratches that occur when a pencil lead is pressed against a sample to be evaluated and moved.
  • the method for measuring pencil hardness is the same as the measurement method described in the first embodiment.
  • the steel wool scratch resistance test is an index showing resistance to defects such as scratches that occur when steel wool is pressed against the sample to be evaluated and moved relative to it.
  • the method for measuring the load capacity in the steel wool scratch resistance test is the same as the measurement method described in the first embodiment.
  • the indentation hardness H IT is a hardness measured by a nanoindentation method using a nanoindenter.
  • the measurement position of the indentation hardness H IT in the cross section of the first layer 120 is a position shifted by 1.2 ⁇ m from the first side surface 121 to the second side surface 122 of the first layer 120 along the normal direction of the optical sheet 110. That is, assuming that the first layer 120 corresponds to the functional layer 20, the indentation hardness H IT in the cross section of the first layer 120 is measured at the first position 26 described with reference to FIG. 2A in the first embodiment.
  • the measurement method of the indentation hardness is the same as the measurement method described in the first embodiment.
  • the first side surface 121 and the second side surface 122 are a pair of main surfaces of the first layer 120.
  • the first side surface 121 is located on a first side in a first direction D1, which is a normal direction of the first layer 120.
  • the first side surface 121 is a surface closer to the first surface 111 in the first direction D1.
  • the first side surface 121 of the first layer 120 constitutes the first surface 111 of the optical sheet 110.
  • the second side surface 122 is located on a second side in the first direction D1.
  • the second side surface 122 is a surface closer to the second surface 112 in the first direction D1.
  • the thickness ratio (T120/T130) of the thickness T120 of the first layer 120 to the thickness T130 of the second layer 130 on the hardness of the first layer 120 and the hardness at the first surface 111 of the optical sheet 110 are unknown.
  • the hardness of the first layer 120 and the hardness at the first surface 111 were improved by providing the second layer 130 adjacent to the first layer 120 containing a cured resin and an ultraviolet absorber as a thin layer so as to satisfy the thickness ratio.
  • the second layer 130 tends to have a lower hardness than the first layer 120, which contains a cured resin.
  • the second layer 130 has an appropriate thickness that is thinner than the first layer 120, the adhesion of the first layer 120 to the optical sheet 110 is more easily ensured, and in addition, the hardness of the second layer 130 is more easily prevented from being reflected in the hardness of the first surface 111.
  • the present disclosure is not bound by this inference.
  • the thickness ratio of the first layer 120 to the second layer 130 has the following relationship with the hardness of the first surface 111 of the optical sheet 110 and the first layer 120:
  • the hardness of the first layer 120 and the hardness at the first surface 111 are improved.
  • the thickness ratio may be 1.5 or more, and may further be 1.7 or more, 2.6 or more, 2.9 or more, or 3.4 or more.
  • the pencil hardness of the first surface 111 may be 2H or more, 3H or more, or 4H or more.
  • the load capacity of the first surface 111 in a steel wool scratch resistance test may be 200g or more, 250g or more, or 300g or more.
  • the indentation hardness of the cross section of the first layer 120 at an indentation depth of 100 nm may be 350 MPa or more, 380 MPa or more, 387 MPa or more, 410 MPa or more, 414 MPa or more, 420 MPa or more, 440 MPa or more, 442 MPa or more, or 480 MPa or more.
  • the pencil hardness of the first surface 111 may be 2H or more and 8H or less, 3H or more and 8H or less, or 4H or more and 8H or less.
  • the load capacity in the steel wool scratch resistance test on the first surface 111 may be 200 g or more and 300 g or less, 250 g or more and 300 g or less, or may be 300 g.
  • the indentation hardness in the cross section of the first layer 120 when the indentation depth is 100 nm may be 350 MPa or more and 600 MPa or less, 380 MPa or more and 600 MPa or less, 387 MPa or more and 600 MPa or less, 410 MPa or more and 600 MPa or less, 414 MPa or more and 600 MPa or less, 420 MPa or more and 600 MPa or less, 440 MPa or more and 600 MPa or less, 442 MPa or more and 600 MPa or less, or 480 MPa or more and 600 MPa or less.
  • the thickness ratio becomes too large, the hardness of the first layer 120 and the hardness at the first surface 111 may decrease.
  • the thickness ratio may be 7.5 or less.
  • the thickness ratio becomes too large, other problems may occur.
  • a lower limit to the thickness ratio the hardness of the first layer 120 and the hardness at the first surface 111 increase.
  • the thickness ratio becomes too large, curling or warping may occur in the optical sheet 110.
  • an upper limit to the thickness ratio deformation such as curling or warping can be suppressed.
  • the thickness ratio may be 7.5 or less, or may be 7.3 or less, 5.0 or less, 4.8 or less, or 3.9 or less.
  • the upper limit of the thickness ratio in this way, deformation such as curling or warping of the optical sheet 110 can be suppressed.
  • the hardness of the first layer 120 and the hardness at the first surface 111 can be improved.
  • the details of why deformation such as curling and warping can be suppressed by setting an upper limit on the thickness ratio are unclear.
  • the following can be inferred as one of the reasons for deformation suppression. Since the first layer 120 contains a resin cured product, it may shrink during the curing process. This curing shrinkage may cause deformation such as curling and warping in the optical sheet 110.
  • the second layer 130 adjacent to the first layer 120 has a thickness that is at least a certain percentage of the thickness of the first layer 120. Therefore, it is inferred that the second layer 130 at least partially absorbs the deformation of the first layer 120, and deformation of the optical sheet 110 is suppressed.
  • the present disclosure is not bound by this inference.
  • the thickness ratio may be 1.5 or more and 7.5 or less, or may be 1.7 or more and 7.5 or less, or may be 2.6 or more and 7.5 or less, or may be 2.9 or more and 7.5 or less, or may be 3.4 or more and 7.5 or less.
  • the thickness ratio may be 1.5 or more and 7.3 or less, or may be 1.7 or more and 7.3 or less, or may be 2.6 or more and 7.3 or less, or may be 2.9 or more and 7.3 or less, or may be 3.4 or more and 7.3 or less.
  • the thickness ratio may be 1.5 or more and 5.0 or less, or may be 1.7 or more and 5.0 or less, or may be 2.6 or more and 5.0 or less, or may be 2.9 or more and 5.0 or less, or may be 3.4 or more and 5.0 or less.
  • the thickness ratio may be 1.5 or more and 4.8 or less, or may be 1.7 or more and 4.8 or less, or 2.6 or more and 4.8 or less, or 2.9 or more and 4.8 or less, or 3.4 or more and 4.8 or less.
  • the thickness ratio may be 1.5 or more and 3.9 or less, or may be 1.7 or more and 3.9 or less, or 2.6 or more and 3.9 or less, or 2.9 or more and 3.9 or less, or 3.4 or more and 3.9 or less.
  • a lower limit may be set for the thickness T120 of the first layer 120.
  • the thickness T120 of the first layer 120 may be 5.0 ⁇ m or more, 5.2 ⁇ m or more, 6.2 ⁇ m or more, 6.6 ⁇ m or more, or 6.7 ⁇ m or more.
  • An upper limit may be set for the thickness T120 of the first layer 120.
  • the thickness T120 of the first layer 120 may be 9.0 ⁇ m or less, 8.7 ⁇ m or less, 7.6 ⁇ m or less, 7.5 ⁇ m or less, or 7.3 ⁇ m or less.
  • the thickness T120 may be 5.0 ⁇ m or more and 9.0 ⁇ m or less, 5.2 ⁇ m or more and 9.0 ⁇ m or less, 6.2 ⁇ m or more and 9.0 ⁇ m or less, 6.6 ⁇ m or more and 9.0 ⁇ m or less, or 6.7 ⁇ m or more and 9.0 ⁇ m or less.
  • the thickness T120 may be 5.0 ⁇ m or more and 8.7 ⁇ m or less, 5.2 ⁇ m or more and 8.7 ⁇ m or less, 6.2 ⁇ m or more and 8.7 ⁇ m or less, 6.6 ⁇ m or more and 8.7 ⁇ m or less, or 6.7 ⁇ m or more and 8.7 ⁇ m or less.
  • the thickness T120 may be 5.0 ⁇ m or more and 7.6 ⁇ m or less, 5.2 ⁇ m or more and 7.6 ⁇ m or less, 6.2 ⁇ m or more and 7.6 ⁇ m or less, 6.6 ⁇ m or more and 7.6 ⁇ m or less, or 6.7 ⁇ m or more and 7.6 ⁇ m or less.
  • the thickness T120 may be 5.0 ⁇ m or more and 7.5 ⁇ m or less, 5.2 ⁇ m or more and 7.5 ⁇ m or less, 6.2 ⁇ m or more and 7.5 ⁇ m or less, 6.6 ⁇ m or more and 7.5 ⁇ m or less, or 6.7 ⁇ m or more and 7.5 ⁇ m or less.
  • the thickness T120 may be 5.0 ⁇ m or more and 7.3 ⁇ m or less, 5.2 ⁇ m or more and 7.3 ⁇ m or less, 6.2 ⁇ m or more and 7.3 ⁇ m or less, 6.6 ⁇ m or more and 7.3 ⁇ m or less, or 6.7 ⁇ m or more and 7.3 ⁇ m or less.
  • a lower limit may be set for the thickness T130 of the second layer 130.
  • the thickness T130 of the second layer 130 may be 1.2 ⁇ m or more, 1.5 ⁇ m or more, 1.6 ⁇ m or more, or 1.7 ⁇ m or more.
  • An upper limit may be set for the thickness T130 of the second layer 130.
  • the thickness T130 of the second layer 130 may be 3.2 ⁇ m or less, 3.0 ⁇ m or less, 2.5 ⁇ m or less, 2.4 ⁇ m or less, 2.3 ⁇ m or less, or 2.1 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 3.2 ⁇ m or less, 1.5 ⁇ m or more and 3.2 ⁇ m or less, 1.6 ⁇ m or more and 3.2 ⁇ m or less, or 1.7 ⁇ m or more and 3.2 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 3.0 ⁇ m or less, 1.5 ⁇ m or more and 3.0 ⁇ m or less, 1.6 ⁇ m or more and 3.0 ⁇ m or less, or 1.7 ⁇ m or more and 3.0 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 2.5 ⁇ m or less, 1.5 ⁇ m or more and 2.5 ⁇ m or less, 1.6 ⁇ m or more and 2.5 ⁇ m or less, or 1.7 ⁇ m or more and 2.5 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 2.4 ⁇ m or less, 1.5 ⁇ m or more and 2.4 ⁇ m or less, 1.6 ⁇ m or more and 2.4 ⁇ m or less, or 1.7 ⁇ m or more and 2.4 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 2.3 ⁇ m or less, 1.5 ⁇ m or more and 2.3 ⁇ m or less, 1.6 ⁇ m or more and 2.3 ⁇ m or less, or 1.7 ⁇ m or more and 2.3 ⁇ m or less.
  • the thickness T130 may be 1.2 ⁇ m or more and 2.1 ⁇ m or less, 1.5 ⁇ m or more and 2.1 ⁇ m or less, 1.6 ⁇ m or more and 2.1 ⁇ m or less, or 1.7 ⁇ m or more and 2.1 ⁇ m or less.
  • the thickness T120 of the first layer 120 and the thickness T130 of the second layer 130 are each measured using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 110 to be evaluated is observed with a scanning transmission electron microscope, and the thicknesses T120 and T130 are measured from the observation image of the scanning transmission electron microscope.
  • the observation image of the cross section of the optical sheet 110 to be evaluated is obtained by observing a thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained through the first and second steps described above.
  • the thickness T120 is determined as the arithmetic mean value of ten thickness measurement values measured at ten measurement positions.
  • the thickness T130 is determined as the arithmetic mean value of ten thickness measurement values measured at ten measurement positions.
  • the hardness of the first layer 120 may be greater than the hardness of the second layer 130.
  • the indentation hardness H IT measured on a cross section of the first layer 120 may be greater than the indentation hardness H IT measured on a cross section of the second layer 130.
  • the measurement position of the indentation hardness H IT of the cross section of the second layer 130 is the center position in the thickness direction of the second layer 130. That is, assuming that the second layer 130 corresponds to the intermediate layer 30, the indentation hardness H IT of the cross section of the second layer 130 is measured at the center position 31 described with reference to FIG. 2A in the first embodiment.
  • the indentation hardness H IT of the cross section of the second layer 130 is measured by pressing an indenter into this measurement position.
  • the indentation hardness H IT of the cross section of the second layer 130 is otherwise measured by the same measurement method as the measurement method of the indentation hardness H IT of the cross section of the first layer 120 described above.
  • the second layer 130 may include one or more of an acrylic resin and a cellulose resin. According to this example, a relationship in which the hardness of the first layer 120 is greater than that of the second layer 130 is stably generated. For example, the indentation hardness H IT measured at the cross section of the first layer 120 can be stably greater than the indentation hardness H IT measured at the cross section of the second layer 130. By combining this hardness relationship with the above-mentioned condition regarding the thickness ratio, the hardness of the first surface 111 of the optical sheet 110 is stably high.
  • the hardness of the first layer 120, the pencil hardness of the first surface 111, the load capacity in the steel wool scratch resistance test on the first surface 111, and the indentation hardness H IT at the cross section of the first layer 120 can be increased.
  • deformation such as curling and warping of the optical sheet 110 can be stably suppressed.
  • the second layer 130 may contain the same resin component as at least a part of the resin component contained in the first layer 120.
  • the adhesion between the second layer 130 and the first layer 120 can be improved.
  • the hardness of the first layer 120 and the hardness at the first surface 111 can be stably improved.
  • the pencil hardness at the first surface 111, the load capacity in a steel wool scratch resistance test at the first surface 111, and the indentation hardness HIT at a cross section of the first layer 120 can be increased.
  • FT-IR Fourier transform infrared spectroscopy
  • the second layer 130 may include a monomer. According to this example, a relationship in which the hardness of the first layer 120 is greater than that of the second layer 130 is stably generated. For example, the indentation hardness H IT measured at the cross section of the first layer 120 can be stably greater than the indentation hardness H IT measured at the cross section of the second layer 130. By combining this hardness relationship with the above-mentioned condition regarding the thickness ratio, the hardness of the first layer 120 and the hardness at the first surface 111 of the optical sheet 110 can be stably improved.
  • the pencil hardness at the first surface 111, the load capacity in the steel wool scratch resistance test at the first surface 111, and the indentation hardness H IT at the cross section of the first layer 120 can be increased.
  • deformation such as curling and warping of the optical sheet 110 can be stably suppressed.
  • the second layer 130 may contain at least a part of the monomer contained in the curable resin composition for producing the first layer 120. According to this example, a relationship in which the hardness of the first layer 120 is greater than that of the second layer 130 is stably generated. For example, the indentation hardness H IT measured on the cross section of the first layer 120 can be stably made greater than the indentation hardness H IT measured on the cross section of the second layer 130. In addition, the adhesion between the second layer 130 and the first layer 120 can be improved. As a result, the hardness of the first layer 120 and the hardness of the first surface 111 of the optical sheet 110 can be stably improved.
  • Whether the second layer 130 contains a monomer is determined by staining with osmium tetroxide.
  • a cross-sectional sample is cut out from the optical sheet 110 by cutting. The thickness of the sample is about 80 nm. The cut out sample is collected on a Cu mesh. This sample is stained with osmium tetroxide for 30 minutes by a vapor-phase staining method. The portion of the stained sample corresponding to the second layer 130 is observed using a scanning transmission electron microscope (STEM). The unsaturated double bonds that may be contained in the second layer 130 are colored by the staining process. Therefore, if the observed sample is colored by staining, it is determined that the second layer 130 contains a monomer. Whether the monomer contained in the second layer 130 is the same as the monomer contained in the curable resin composition for producing the first layer 120 is determined by quantitatively analyzing the chemical bonds using Fourier transform infrared spectroscopy (FT-IR).
  • FT-IR Fourier transform infrared spect
  • the optical sheet 110 may include a base layer 140.
  • the first layer 120, the second layer 130, and the base layer 140 may be arranged in this order from the first surface 111 to the second surface 112 in the first direction D1.
  • the first layer 120 includes a first side surface 121 and a second side surface 122.
  • the first side surface 121 and the second side surface 122 constitute a pair of main surfaces of the first layer 120.
  • the first side surface 121 constitutes the first surface 111.
  • the second side surface 122 is in contact with the second layer 130.
  • the thickness T140 of the base layer 140 may be thicker than the thickness T120 of the first layer 120.
  • the thickness T140 of the base layer 140 may be thicker than the thickness T130 of the second layer 130.
  • the thickness T140 of the base layer 140 may be thicker than the total thickness of the thickness T120 of the first layer 120 and the thickness T130 of the second layer 130.
  • a base layer 140 having such a thickness T140 can stably support the first layer 120 and the second layer 130.
  • the thickness T140 of the base layer 140 is measured using a scanning transmission electron microscope (STEM) in the same manner as the thickness T120 of the first layer 120 and the thickness T130 of the second layer 130.
  • a cross section of the optical sheet 110 to be evaluated is observed with the scanning transmission electron microscope, and the thickness T140 is measured from the image observed with the scanning transmission electron microscope.
  • the cross-sectional image of the optical sheet 110 to be evaluated is obtained by observing a thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained through the above-mentioned first and second steps.
  • the thickness T140 of the base layer 140 is determined as the arithmetic mean value of ten thickness measurements taken at ten measurement positions.
  • the second layer 130 may contain at least a part of the same resin component as the resin component contained in the base layer 140.
  • the adhesion between the second layer 130 and the base layer 140 can be improved.
  • the adhesion between the second layer 130 and the base layer 140 can also contribute to improving the hardness of the first layer 120 and the hardness at the first surface 111.
  • the adhesion between the second layer 130 and the base layer 140 is improved, the hardness of the first layer 120 and the hardness at the first surface 111 can be improved.
  • the pencil hardness at the first surface 111, the load capacity in a steel wool scratch resistance test at the first surface 111, and the indentation hardness HIT at the cross section of the first layer 120 can be increased.
  • the second layer 130 may include at least a part of the resin component included in the first layer 120 and at least a part of the resin component included in the base layer 140. According to this example, a relationship in which the hardness of the first layer 120 is greater than the hardness of the second layer 130 is stably generated.
  • the indentation hardness H IT measured on the cross section of the first layer 120 can be stably made greater than the indentation hardness H IT measured on the cross section of the second layer 130.
  • the adhesion between the first layer 120 and the second layer 130 can be improved, and the adhesion between the second layer 130 and the base layer 140 can be improved.
  • the adhesion By improving the adhesion, the hardness of the first layer 120 and the hardness at the first surface 111 can be stably improved.
  • the second layer 130 may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the first layer 120. By including an ultraviolet absorbing agent in the second layer 130, the blue light blocking function can be enhanced.
  • the second layer 130 may be a mixed layer of the resin component of the first layer 120 and the resin component of the base layer 140.
  • the second layer 130 as a mixed layer of the resin component of the first layer 120 and the resin component of the base layer 140 can more effectively improve the hardness of the first layer 120 and the hardness at the first surface 111.
  • the second layer 130 as a mixed layer may be a permeation layer in which the curable resin composition for producing the first layer 120 is permeated into the base film 145.
  • the base layer 140 and the second layer 130 may both be composed of the base film 145 to which the curable resin composition for producing the first layer 120 is applied.
  • the portion of the base film 145 that is permeated with the curable resin composition may constitute the second layer 130.
  • the portion of the base film 145 that is not permeated with the curable resin composition may constitute the base layer 140.
  • the presence of the permeation layer can be confirmed by observing the cross section of the optical sheet along the first direction with a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • An observation image of the cross section of the optical sheet 110 to be evaluated is obtained by observing the above-mentioned thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is stained before observation with the scanning transmission electron microscope. Osmium tetroxide, ruthenium tetroxide, phosphotungstic acid, etc. may be used for staining.
  • the substrate layer 140 and the substrate film 145 may contain one or more of an acrylic resin and a cellulose resin.
  • the acrylic resin and the cellulose resin are easily permeated with the curable resin composition. Therefore, the second layer 130, which is a mixed layer of the resin components of the first layer 120 and the resin components of the substrate layer 140, can be easily produced. According to this example, the hardness of the first layer 120 and the hardness at the first surface 111 can be stably improved.
  • the hardness of the base layer 140 may be greater than the hardness of the second layer 130.
  • the indentation hardness H IT measured on a cross section of the base layer 140 may be greater than the indentation hardness H IT measured on a cross section of the second layer 130.
  • the measurement position of the indentation hardness H IT of the cross section of the base material layer 140 is the center in the thickness direction of the base material layer 140. That is, assuming that the base material layer 140 corresponds to the base material layer 40, the indentation hardness H IT of the cross section of the base material layer 140 is measured at the center position 41 described with reference to FIG. 2A in the first embodiment.
  • the indentation hardness H IT of the cross section of the base material layer 140 is measured by pressing an indenter into this measurement position.
  • the indentation hardness H IT of the cross section of the base material layer 140 is otherwise measured by the same measurement method as the measurement method of the indentation hardness H IT of the cross section of the first layer 120 described above.
  • the a * value of the L * a * b * color system of the optical sheet 110 measured by transmitted light may be -3.0 or more and -1.6 or less.
  • the b * value of the L * a * b * color system of the optical sheet 110 measured by transmitted light may be 3.5 or more and 6.0 or less.
  • the yellowness index (YI value) of the optical sheet 110 may be 12 or less, 11 or less, 10 or less, or 9.0 or less.
  • the yellowness index is an index showing the degree of yellow coloring of the optical sheet 110.
  • the yellowness (YI value) of the optical sheet 110 may be equal to or greater than 0.
  • the yellowness index (YI value) of the optical sheet 110 may be greater than 0 and less than 12, greater than 0 and less than 11, greater than 0 and less than 10, or greater than 0 and less than 9.0.
  • the yellowness index (YI value) of the optical sheet 110 may be greater than 0 and less than 12, greater than 0 and less than 11, greater than 0 and less than 10, or greater than 0 and less than 9.0.
  • the method for measuring the yellowness is the same as that described in the first embodiment.
  • the total light transmittance of the optical sheet 110 may be 50% or more, 70% or more, 80% or more, or 90% or more.
  • the total light transmittance of the optical sheet 110 does not have a particular upper limit.
  • the total light transmittance of the optical sheet 110 may be 100% or less, or may be less than 100%.
  • the total light transmittance of the optical sheet 110 may be 50% or more and 100% or less, 70% or more and 100% or less, 80% or more and 100% or less, or 90% or more and 100% or less.
  • the total light transmittance of the optical sheet 110 may be 50% or more and less than 100%, 70% or more and less than 100%, 80% or more and less than 100%, or 90% or more and less than 100%.
  • the method for measuring the total light transmittance is the same as that described in the first embodiment.
  • the transmission haze of the optical sheet 110 may be 1.1% or less, 0.5% or less, or 0.2% or less.
  • the transmission haze of the optical sheet 110 does not have a particular lower limit.
  • the transmission haze of the optical sheet 110 may be 0% or greater than 0%.
  • the transmission haze of the optical sheet 110 may be 0% or more and 1.1% or less, 0% or more and 0.5% or less, or 0% or more and 0.2% or less.
  • the transmission haze of the optical sheet 110 may be greater than 0% and 1.1% or less, greater than 0% and 0.5% or less, or greater than 0% and 0.2% or less.
  • the method for measuring the transmission haze is the same as that described in the first embodiment.
  • the ratio of silicon element to carbon element measured on the first surface 111 by X-ray photoelectron spectroscopy may be 0.02 or more. In other words, in the quantitative analysis result of elements by X-ray photoelectron spectroscopy, the amount of silicon element may be 0.02 or more when the amount of carbon element is 1.
  • the silicon element is the sum of an inorganic component (silica) and an organic component (silicone).
  • the first layer 120 may contain inorganic particles as a lubricant.
  • By setting the ratio of silicon element to carbon element to 0.02 or more it is possible to suppress the aggregation of inorganic particles added as a lubricant, for example, the aggregation of silica. In other words, by setting the ratio of silicon element to carbon element to 0.02 or more, the lubricant functions effectively.
  • the lubricant can suppress the adjacent optical sheets 110 from sticking to each other when the optical sheets 110 are stacked or rolled up.
  • the curable resin composition for producing the first layer 120 may contain a leveling agent.
  • a Si-based leveling agent as the leveling agent added to the curable resin composition, the ratio of silicon elements to carbon elements can be set to 0.02 or more.
  • the ratio of elemental fluorine measured on the first surface 111 by X-ray photoelectron spectroscopy may be 0.1% or less. In other words, the ratio of the amount of elemental fluorine to the total amount of elements detected by X-ray photoelectron spectroscopy may be 0.001 or less. In this example, substantially no fluorine is detected in the surface layer of the optical sheet 110. By not using an F-based leveling agent as the leveling agent added to the curable resin composition, the ratio of elemental fluorine can be 0.1% or less.
  • X-ray photoelectron spectroscopy allows for quantitative analysis of elements present on the surface layer of the optical sheet 110.
  • an X-ray photoelectron spectroscopy device XPS
  • the measurement method by X-ray photoelectron spectroscopy using an X-ray photoelectron spectroscopy device is the same as the measurement method described in the first embodiment.
  • the base layer 140, the second layer 130, and the first layer 120 are stacked in the first direction D1.
  • the first direction D1 is the stacking direction.
  • the base layer 140, the second layer 130, and the first layer 120 extend in the second direction D2 and the third direction D3 perpendicular to the first direction D1.
  • the second direction D2 and the third direction D3 are perpendicular to each other.
  • the first direction D1 is the thickness direction and normal direction of the optical sheet 110.
  • the first direction D1 is also the thickness direction and normal direction of each layer 140, 130, and 120 included in the optical sheet 110.
  • the first surface 111 is composed of the first layer 120.
  • the second surface 112 is composed of the base layer 140.
  • the first layer 120 and the second layer 130 are adjacent in the first direction D1.
  • the second layer 130 and the base layer 140 are adjacent in the first direction D1.
  • the optical sheet 110 may include layers other than the first layer 120, the second layer 130, and the base layer 140.
  • the optical sheet 110 may include one or more of a low-reflection layer, an antistatic layer, an antifouling layer, etc.
  • a layer other than the first layer 120 may constitute the first surface 111.
  • the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer are thin layers. Therefore, even in the example in which the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer, constitute the first surface 111, the hardness of the first surface 111 can be improved by the combination of the first layer 120 and the second layer 130.
  • the base layer 140 supports the first layer 120 and the second layer 130.
  • the base layer 140 may be transparent.
  • transparent means that the total light transmittance in accordance with JIS K7361-1:1997 is 50% or more. This means that the ratio is 70% or more, 80% or more, or 90% or more.
  • the substrate layer 140 may be the same as the substrate layer 40 described in the first embodiment.
  • the substrate layer 140 may have the same configuration as the substrate layer 40 described in the first embodiment.
  • the material of the substrate layer 140 may be the same as the material of the substrate layer 40 described in the first embodiment.
  • the thickness T140 of the substrate layer 140 may be the same as the thickness T40 of the substrate layer 40 described in the first embodiment.
  • the layer structure of the substrate layer 140 may be the same as the layer structure of the substrate layer 40 described in the first embodiment.
  • the substrate layer 140 may be prepared as a substrate film 145.
  • This substrate film 145 may include only a single layer or may include multiple layers.
  • the substrate layer 140 may include a primer layer such as an easy-adhesion layer.
  • the surface of the substrate film 145 may be subjected to one or more of sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, etching treatment such as oxidation, and undercoat treatment. These treatments can improve the adhesion between the substrate film 145 and the layer adjacent to the substrate film 145.
  • the surface of the substrate film 145 may be subjected to a cleaning treatment such as solvent cleaning or ultrasonic cleaning.
  • the first layer 120 includes a binder resin 123 and an ultraviolet absorbing agent.
  • the first layer 120 exhibits a blue light blocking function by including the ultraviolet absorbing agent.
  • the binder resin 123 is a curable resin composition.
  • the first layer 120 contains a cured product of the curable resin composition, which contributes to improving the hardness of the first surface 111 and the first layer 120.
  • the first layer 120 may have the same configuration as the functional layer 20 described in the first embodiment.
  • the material of the first layer 120 may be the same as the material of the functional layer 20 described in the first embodiment.
  • the layer structure of the first layer 120 may be the same as the layer structure of the functional layer 20 described in the first embodiment.
  • the curable resin composition may be an ionizing radiation curable resin composition.
  • the ionizing radiation curable resin composition may include one or more of an ultraviolet ray curable resin composition and an electron beam curable resin composition.
  • the ionizing radiation curable resin composition may include an ionizing radiation curable compound and a photopolymerization initiator.
  • the ionizing radiation curable compound may include one or more of an ultraviolet ray curable compound and an electron beam curable compound.
  • the ultraviolet ray curable compound is a resin that is cured by irradiation with ultraviolet rays.
  • the electron beam curable compound is a resin that is cured by irradiation with an electron beam.
  • the cured product of the curable resin composition may be a cured curable compound.
  • the ionizing radiation curable compound may be the same as the ionizing radiation curable compound used in the functional layer 20 described in the first embodiment.
  • the photopolymerization initiator is not particularly limited, and may be the same as the photopolymerization initiator used in the functional layer 20 described in the first embodiment.
  • the content of the photopolymerization initiator may be the same as the content of the photopolymerization initiator described in the first embodiment.
  • the ultraviolet absorbent may be dispersed in a first direction D1, a second direction D2, and a third direction D3 in the first layer 120.
  • the ultraviolet absorbent may be included in a liquid curable resin composition.
  • the ultraviolet absorbent included in the curable resin composition may be dispersed in the first layer 120 after a coating film of the curable resin composition is subjected to a drying process and a curing process.
  • the ultraviolet absorber imparts a blue light cut function to the first layer 120 and the optical sheet 110.
  • the characteristics of the blue light cut function can be adjusted by the type and content of the ultraviolet absorber. Therefore, the blue light cut function caused by the ultraviolet absorber can make the spectral transmittance at a wavelength of 440 nm 70% or more, while making the spectral transmittance at a wavelength of 410 nm 15% or less.
  • the a * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the b * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the yellowness YI value measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the type and content of the ultraviolet absorber are not particularly limited.
  • the type and content of the ultraviolet absorber can be selected so as to obtain the desired blue light cut function and the desired a * value and b * value.
  • the type and content of the UV absorbent may be the same as those described in the first embodiment.
  • the curable resin composition may contain particles as a lubricant.
  • the curable resin composition may contain the same particles as the particles as the lubricant contained in the curable resin composition for the functional layer described in the first embodiment.
  • the particle diameter of the particles contained in the first layer 120 is a value specified in the same manner as the particle diameter of the particles contained in the functional layer 20 described in the first embodiment.
  • the curable resin composition may contain a Si-based leveling agent as an additive.
  • the surface of the first layer 120 can be made smoother.
  • the Si-based leveling agent can impart excellent slip properties and excellent anti-fouling properties to the surface of the first layer 120.
  • the curable resin composition may contain other additives.
  • additives include antistatic agents, antioxidants, surfactants, dispersants, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments, dyes), defoamers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, and surface modifiers.
  • the curable resin composition may contain one or more of these additives.
  • the curable resin composition may contain a solvent.
  • the curable resin composition may contain the same solvent as the solvent contained in the curable resin composition for the functional layer described in the first embodiment.
  • the content ratio of the raw materials in the curable resin composition i.e., the solid content ratio, is not particularly limited.
  • the content ratio of the raw materials in the curable resin composition may be 5% by mass or more, or 25% by mass or more.
  • the content ratio of the raw materials in the curable resin composition may be 70% by mass or less, or 60% by mass or less.
  • the first layer 120 is made using a liquid curable resin composition containing an ultraviolet absorber.
  • the prepared curable resin composition is applied to a surface on which the first layer 120 is to be made to form a coating film of the curable resin composition.
  • the coating film of the curable resin composition is dried, and the dried coating film is cured to obtain the first layer 120.
  • the method for preparing the curable resin composition is not particularly limited.
  • the curable resin composition may be prepared using known devices such as a paint shaker, a bead mill, a kneader, or a mixer.
  • the method for applying the curable resin composition is not particularly limited.
  • the curable resin composition may be applied by a known method such as spin coating, dipping, spraying, die coating, bar coating, roll coating, meniscus coating, flexographic printing, screen printing, or pad coating.
  • the curing treatment of the curable resin composition may be performed by irradiation with ionizing radiation.
  • the ionizing radiation may be ultraviolet light or an electron beam.
  • ultraviolet light sources include ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, metal halide lamps, etc.
  • the wavelength of the ultraviolet light may be in the wavelength range of 190 nm to 420 nm. It is preferable that the wavelength of the ultraviolet light used in the curing treatment is the central absorption wavelength of the photopolymerization initiator contained in the curable resin composition, or is close to the central absorption wavelength.
  • the wavelength of the ultraviolet light used in the curing treatment is away from the central absorption wavelength of the ultraviolet absorber contained in the curable resin composition.
  • the first layer 120 can be sufficiently cured by the curing treatment by ultraviolet irradiation.
  • the second layer 130 is a layer adjacent to the first layer 120 and the base layer 140. As described above, the second layer 130 has a thickness T130 adjusted with respect to the thickness T120 of the first layer 120.
  • the thickness ratio which is the ratio of the thickness T120 of the first layer 120 to the thickness T130 of the second layer 130, is equal to or greater than 1.5 and equal to or less than 7.5.
  • the second layer 130 may be a resin layer.
  • the second layer 130 may be a layer that has high adhesion to the base layer 140.
  • the second layer 130 may be a layer that has high adhesion to the first layer 120.
  • the second layer 130 may have a hardness lower than that of the first layer 120.
  • the indentation hardness measured on a cross section of the first layer 120 may be greater than the indentation hardness measured on a cross section of the second layer 130.
  • the presence of such a second layer 130 can improve the hardness of the first layer 120 and the hardness at the first surface 111.
  • the material of the second layer 130 may be selected as follows.
  • the second layer 130 may include a thermoplastic resin.
  • the second layer 130 may include the same resin component as at least a portion of the resin component contained in the first layer 120.
  • the second layer 130 may include one or more of an acrylic resin and a cellulose resin.
  • the second layer 130 may include the same resin component as at least a portion of the resin component contained in the first layer 120.
  • the second layer 130 may include a monomer.
  • the second layer 130 may include at least a portion of the monomer contained in the curable resin composition for producing the first layer 120.
  • the second layer 130 may be a mixed layer of the resin component of the first layer 120 and the resin component of the base layer 140.
  • the second layer 130 may be a mixed layer of the resin component of the first layer 120 and the resin component of the base layer 140.
  • the second layer 130 as a mixed layer may be a permeation layer in which the curable resin composition for producing the first layer 120 is permeated into the base film 145.
  • the base film 140 and the second layer 130 may both be constituted by the base film 145 to which the curable resin composition for producing the first layer 120 is applied.
  • the second layer 130 may be constituted by a portion of the base film 145 into which the curable resin composition has permeated (permeation layer).
  • the base layer 140 may be constituted by a portion of the base film 145 into which the curable resin composition has not permeated.
  • the solvent contained in the curable resin composition easily penetrates the base film 145, so that the second layer 130 can be stably formed as a penetration layer.
  • the solvent easily penetrates the base film 145.
  • the solvent easily penetrates cellulose-based resins, particularly triacetylcellulose (TAC).
  • TAC triacetylcellulose
  • the solvent also easily penetrates acrylic resins. Therefore, the base layer 140 and the base film 145 may contain one or more of an acrylic resin and a cellulose resin.
  • the second layer 130 which is a mixed layer of the resin component of the first layer 120 and the resin component of the base layer 140, can be stably produced.
  • the produced second layer 130 contains one or more of an acrylic resin and a cellulose resin.
  • the ease of forming the penetration layer varies depending on the relationship between the curable resin compound and the solvent contained in the curable resin composition and the base film 145.
  • the ease of forming the penetration layer also varies depending on the viscosity of the curable resin compound, the drying conditions of the coating of the curable resin compound, and the curing conditions of the coating of the curable resin compound. Therefore, the thickness T130 of the second layer 130 as a penetration layer can be adjusted depending on the material contained in the curable resin composition, the material of the base film 145, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, and the like.
  • the amount of penetration varies depending on the material contained in the curable resin composition, the material of the base film 145, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, and the like, so the thickness T120 of the first layer 120 can also be adjusted. That is, when the second layer 130 is produced as a penetration layer, the thickness ratio can be adjusted.
  • the second layer may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the first layer.
  • a method for manufacturing the optical sheet 110 may include a step of preparing an intermediate laminate including a substrate layer 140 and a second layer 130, and a step of preparing a first layer 120 on the second layer 130.
  • the method for producing the intermediate laminate may be appropriately selected depending on the configuration of the second layer 130 to be produced.
  • the intermediate laminate may be produced by laminating the film constituting the second layer 130 and the film constituting the base layer 140.
  • the second layer 130 and the base layer 140 may be directly bonded by heat welding.
  • the second layer 130 and the base layer 140 may be bonded using a bonding layer containing an adhesive, a pressure-sensitive adhesive, or the like.
  • the intermediate laminate may be produced by forming the second layer 130 on the base layer 140 as a base film by a wet method. In the wet method, a liquid composition is prepared.
  • the liquid composition is applied onto the base layer 140.
  • the second layer 130 may be formed on the base layer 140 by drying the coating of the composition.
  • the first layer 120 may be produced by the wet method described above.
  • a liquid curable resin composition is prepared.
  • the liquid curable resin composition may contain solids constituting the binder resin 123 of the first layer 120, additives such as an ultraviolet absorber and a polymerization initiator, and a solvent.
  • the curable resin composition is applied onto the second layer 130 of the intermediate laminate, thereby obtaining a coating of the curable resin composition on the second layer 130. Next, the coating is dried and cured, thereby obtaining the first layer 120 on the second layer 130.
  • a method for manufacturing the optical sheet 110 may include a step of preparing an intermediate laminate including the second layer 130 and the first layer 120, and a step of laminating the intermediate laminate including the second layer 130 and the first layer 120 to the base layer 140.
  • the first layer 120 may be formed on the second layer 130 by a wet method.
  • the base layer 140 and the second layer 130 of the intermediate laminate may be directly bonded by heat welding.
  • the base layer 140 and the second layer 130 of the intermediate laminate may be bonded using a bonding layer containing an adhesive, a pressure sensitive adhesive, or the like.
  • the intermediate laminate may include a release sheet, a first layer 120, and a second layer 130 in this order.
  • the process of producing the intermediate laminate may include a process of forming the first layer 120 on the release surface of the release sheet by a wet method, and a process of forming the second layer 130 on the first layer 120.
  • the second layer 130 may be formed on the first layer 120 by a wet method.
  • the second layer 130 may be composed of a film laminated to the first layer 120.
  • the release sheet may be peeled off from the second layer 130 and the first layer 120 that are transferred onto the substrate layer 140.
  • the manufacturing method of the optical sheet 110 may include a step of producing the first layer 120 on the substrate film 145 by a wet method.
  • This manufacturing method may include a step of applying a curable resin composition onto the substrate film 145 and a step of curing the coating of the curable resin composition.
  • the manufacturing method may further include a step of drying the coating of the curable resin composition before the step of curing the coating.
  • the first layer 120 may be constituted by the coating of the cured curable resin composition.
  • the second layer 130 may be constituted by a portion of the substrate film 145 into which the curable resin composition has permeated (i.e., a permeation layer).
  • the substrate layer 140 may be constituted by a portion of the substrate film into which the curable resin composition has not permeated.
  • the thickness T130 of the second layer 130 as a penetration layer can be adjusted depending on the material contained in the curable resin composition, the material of the base film 145, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, etc.
  • the amount of penetration into the base layer 140 changes depending on the material contained in the curable resin composition, the material of the base film 145, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, etc., so the thickness T120 of the first layer 120 can also be adjusted.
  • the thickness ratio can be adjusted when the second layer 130 is produced as a penetration layer.
  • the thickness T130 of the second layer 130 can be increased by selecting a type of solvent that easily penetrates the base film 145 or by increasing the content of the solvent.
  • the thickness T130 of the second layer 130 can be increased by selecting a base film 145 made of a resin material that is easily penetrated by the solvent of the curable resin composition.
  • a resin material that is easily penetrated by a solvent is a cellulose-based resin such as triacetylcellulose (TAC).
  • TAC triacetylcellulose
  • the thickness of the second layer 130 can be increased.
  • the thickness T130 of the second layer 130 can be increased by reducing the temperature of the heated air blown onto the coating film during the drying process or by reducing the flow rate or volume of the heated air. If the solid content of the curable resin composition is high, the thickness T130 of the second layer 130 can be reduced.
  • the manufacturing method of the optical sheet 110 may include the following four steps.
  • the manufacturing method may further include a step of drying the coating film of the first curable resin composition before the step of curing the coating film of the first curable resin composition. In a fourth example, the manufacturing method may further include a step of drying the coating film of the second curable resin composition before the step of curing the coating film of the second curable resin composition.
  • the first layer 120 may be formed by the first portion 120A and the second portion 120B.
  • the second layer 130 may be formed by the portion of the base film 145 that is permeated with the curable resin composition (i.e., the permeation layer).
  • the base layer 140 may be formed by the portion of the base film 145 that is not permeated with the curable resin composition.
  • the second portion 120B constitutes a surface portion of the first layer 120.
  • the surface portion of the first layer 120 is located near the first surface 111 or constitutes the first surface 111.
  • the first portion 120A constitutes a portion of the first layer 120 that is bonded to the second layer 130.
  • the first portion 120A is away from the first surface 111.
  • the first curable resin composition and the second curable resin composition have different compositions, so that the properties can be changed between the first portion 120A and the second portion 120B in the first layer 120.
  • the first curable resin composition and the second curable resin composition may be the same as the curable resin composition described above.
  • the second curable resin composition may not contain an ultraviolet absorber.
  • the second curable resin composition may contain an ultraviolet absorber in a content smaller than the content of the first curable resin composition.
  • the second curable resin composition may contain an ultraviolet absorber in a content smaller than the content of the first curable resin composition.
  • the first curable resin composition contains more ultraviolet absorbent. Therefore, the hardness of the first portion 120A is reduced.
  • the second curable resin composition does not contain ultraviolet absorbent or contains only a small amount of ultraviolet absorbent.
  • the coating film of the second curable resin composition can be irradiated with a sufficient amount of ionizing radiation, such as ultraviolet light, with sufficient strength. Therefore, the crosslinking reaction in the second portion 120B is promoted, and the hardness of the second portion 120B becomes hard. This makes it possible to harden the surface hardness of the first side 121 of the first layer 120 while imparting the blue light cutting function due to the ultraviolet absorbent to the first layer 120.
  • the UV absorbent is mainly dispersed in the first portion 120A.
  • the first portion 120A is covered by the second portion 120B, which has a higher hardness. Therefore, the UV absorbent can be effectively prevented from passing through the second portion 120B and bleeding out.
  • the first portion 120A to which the second curable resin composition is applied may contain an ultraviolet absorber, which may cause the crosslinking reaction to stagnate, resulting in low hardness. Therefore, the second curable resin composition may penetrate into the first portion 120A.
  • the first curable resin composition and the second curable resin composition are mixed, and the interface between the first portion 120A and the second portion 120B becomes inconspicuous. This significantly improves the adhesion between the first portion 120A and the second portion 120B.
  • the second curable resin composition can penetrate not only the first portion 120A but also the base layer 140.
  • the thickness T130 of the second layer 130 as a penetration layer can be adjusted by the materials contained in the first and second curable resin compositions, the material of the base film 145, the preparation conditions of the first and second curable resin compositions, the drying conditions of the first and second curable resin compositions, the curing conditions of the first and second curable resin compositions, etc.
  • the thickness T130 and thickness ratio of the second layer 130 can be adjusted with a higher degree of freedom compared to the manufacturing method according to the third example described above.
  • the manufacturing method according to the fourth example also allows for a high degree of freedom in adjusting the spectral transmittance.
  • the spectral transmittance can be adjusted by factors other than the type and total content of the ultraviolet absorbent contained in the first and second curable resin compositions.
  • the wavelength of the ultraviolet light used in the curing process is preferably away from the central absorption wavelength of the ultraviolet absorber contained in the curable resin composition. For this reason, in many conventional curable resin compositions, particularly ultraviolet curable resin compositions, contain only one type of ultraviolet absorber.
  • the spectral transmission characteristics can be adjusted by factors other than the type of ultraviolet absorbent and the total content of the ultraviolet absorbent.
  • the spectral transmission characteristics can be adjusted by the ratio of the content of the ultraviolet absorbent in the first curable resin composition to the content of the ultraviolet absorbent in the second curable resin composition.
  • the spectral transmission characteristics can be adjusted by the ratio of the content of the ultraviolet absorbent in the first curable resin composition to the content of the curable resin composition in the second curable resin composition.
  • the spectral transmittance can be adjusted by one or more of the thickness of the first portion 120A, the thickness of the second portion 120B, and the ratio of the thickness of the first portion 120A to the thickness of the second portion 120B.
  • the coating of the second curable resin composition can be cured while avoiding the influence of the ultraviolet absorber contained in the first portion 120A. That is, when the coating of the second curable resin composition is cured, the influence of the ultraviolet absorber contained in the first curable resin composition can be suppressed. Therefore, the type, content, and content ratio of the ultraviolet absorber contained in the first curable resin composition and the first portion 120A of the first layer 120 can be selected with a high degree of freedom. This allows the first layer 120 and the optical sheet 110 to be given the desired spectral transmission characteristics.
  • the ultraviolet absorbing agent can be unevenly distributed in a portion of the first layer 120 in the thickness direction, for example, the first portion 120A. Therefore, the ultraviolet absorbing agent can be effectively utilized to efficiently capture blue light. From this point of view, the desired spectral transmission characteristics can be imparted to the first layer 120 and the optical sheet 110. Furthermore, while imparting the desired spectral transmission characteristics to the optical sheet 110, the hardness and scratch resistance of the first surface 111 can be improved.
  • a long sheet article 5 including a number of optical sheets 110 can be manufactured.
  • the long sheet article 5 is cut to a predetermined size to obtain the optical sheet 110.
  • optical sheets 110 having various dimensions can be obtained from the long sheet article 5 in accordance with needs. Therefore, optical sheets 110 having various dimensions can be provided in a timely manner.
  • the handleability of the sheet article 5 can be improved.
  • the manufacturing method of the optical sheet may further include a step of selecting the manufactured optical sheet 110 in addition to the step of manufacturing the optical sheet described above.
  • the step of selecting the optical sheet 110 may include a step of measuring a thickness ratio, a step of measuring a spectral transmittance at a wavelength of 410 nm, and a step of measuring a spectral transmittance at a wavelength of 440 nm.
  • the thickness ratio is a ratio of the thickness T120 ( ⁇ m) of the first layer 120 to the thickness T130 ( ⁇ m) of the second layer 130.
  • the step of selecting the optical sheet 110 may further include a step of selecting the optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 410 nm, and the spectral transmittance at a wavelength of 440 nm.
  • a thickness ratio of 1.5 or more and 7.5 or less may be considered acceptable.
  • a spectral transmittance of 15% or less at a wavelength of 410 nm may be considered acceptable.
  • a spectral transmittance of 70% or more at a wavelength of 440 nm may be considered acceptable.
  • the optical sheet 110 that passes all of the thickness ratio, the spectral transmittance at a wavelength of 410 nm, and the spectral transmittance at a wavelength of 440 nm may be selected as a good product.
  • the optical sheet 110 selected as a good product has an excellent blue light blocking function and has high hardness on the first surface 111. According to this selection step, an optical sheet having excellent scratch resistance can be selected with high precision without performing an abrasion
  • the optical sheet 110 may be applied to one or more of the polarizing plate 50, the touch panel member 55, and the display device 60.
  • the first curable resin composition 2A was applied onto a substrate film made of triacetyl cellulose having a thickness of 80 ⁇ m, and a first coating film was formed on the substrate film.
  • the method for producing the first curable resin composition 2A will be described later.
  • the first coating film was dried under the condition of 40° C. ⁇ 20 seconds (drying air speed 0.4 m/s).
  • the first coating film was dried under the condition of 40° C. ⁇ 20 seconds (drying air speed 0.5 m/s). The above caused the solvent to volatilize.
  • the first coating film was irradiated with ultraviolet light at an integrated light amount of 66 mJ/cm 2.
  • the first coating film was cured by irradiation with ultraviolet light, and the first portion of the first layer was formed on the substrate film.
  • the amount of application of the first curable resin composition 2A was set to an amount that would produce a first portion with a dry thickness of 3.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • the second curable resin composition 2A having the following formulation was applied onto the first portion to form a second coating film on the substrate film.
  • the solid content of the second curable resin composition 2A was 47%.
  • the second curable resin composition 2A did not contain an ultraviolet absorber.
  • the second coating film was dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s).
  • the second coating film was dried under the conditions of 70°C x 20 seconds (drying air speed 0.3 m/s). The above caused the solvent to volatilize.
  • the second coating film was irradiated with ultraviolet light at an integrated light quantity of 288 mJ/ cm2 .
  • the second coating film was cured by irradiation with ultraviolet light, and the second portion of the first layer was prepared on the substrate film and the first portion.
  • the amount of application of the second curable resin composition 2A was set to an amount that would produce a second portion with a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate layer or the first portion.
  • the optical sheet of Example 21 was obtained.
  • the first layer was composed of the first portion and the second portion.
  • the cross section of the optical sheet of Example 21 was observed during the thickness measurement described below.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used to observe the cross section.
  • the cross section was observed at an acceleration voltage of 10 kV to 30 kV and a magnification of 5000 times, it was found that the curable resin composition had permeated the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer. Furthermore, the interface between the first and second parts in the first layer could not be observed.
  • Second curable resin composition 2A A sesamol-type benzotriazole monomer was synthesized, and then an acrylic polymer to which the sesamol-type benzotriazole monomer was reactively bonded was synthesized, thereby obtaining a first curable resin composition 2A.
  • the contents in the four-neck flask were refluxed and dehydrated at 110-115°C for 4 hours.
  • 30 mL of water and 0.6 g (0.006 mol) of sodium carbonate were added to the four-neck flask.
  • the four-neck flask was then left to stand, and the lower aqueous layer was separated and removed.
  • 0.2 g of activated carbon was added to the four-neck flask, and the contents were refluxed and stirred to decolorize.
  • the contents removed from the four-neck flask were then filtered. 40 mL of toluene was collected from the obtained filtrate under reduced pressure.
  • An intermediate composition was prepared by mixing the following: - Multifunctional monomer (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded (a polymer in which a sesamol-type benzotriazole monomer is reactively bonded to MMA and an ultraviolet absorber at a mass ratio X of 40 parts by mass) Solvent (a mixture of MEK and toluene in a mass ratio of 30:70) The polyfunctional monomer and the acrylic polymer (1) were mixed in a solid content mass ratio of 20:80.
  • - Multifunctional monomer PT-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.)
  • Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded a polymer in which a sesamol-type benzotriazole monomer is reactive
  • the obtained intermediate composition was mixed with a photopolymerization initiator (4 parts by mass of Irgacure 819, manufactured by BASF) and a leveling agent (0.2 parts by mass of LE-304, manufactured by Kyoeisha) and thoroughly stirred to prepare a first curable resin composition 2A.
  • the obtained first curable resin composition 2A contained a solid content of 27.5%.
  • UV-curable acrylate-containing composition 50 parts by mass (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass of ultraviolet-curable urethane acrylate-containing composition (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577")
  • Leveling agent 0.4 parts by mass (Kyoeisha, product name "LE-304”)
  • Photopolymerization initiator 4 parts by mass IGM Resins, trade name "Omnirad184”
  • Lubricant 20 parts by mass (CIK Nanotech, SIRMIBK15WT%-E65)
  • Solvent a mixture of methyl isobutyl ketone and methyl ethyl ketone in a mass ratio of 55:48)
  • Example 22 differs from the above-mentioned Example 21 in that the amount of the first curable resin composition 2A applied was reduced, but otherwise the optical sheet of Example 22 was obtained using the same materials and method as Example 21.
  • the amount of the first curable resin composition 2A applied was set to an amount that would produce a first portion with a dry thickness of 2.6 ⁇ m, assuming that there was no penetration into the base film.
  • Example 22 When measuring the thickness as described below, the cross section of the optical sheet of Example 22 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 23 differs from the above-mentioned Example 21 in that the coating amount of the first curable resin composition 2A was increased, but otherwise the optical sheet of Example 23 was obtained using the same materials and the same method as in Example 21.
  • the coating amount of the first curable resin composition 2A was set to an amount that would produce a first portion with a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the base film.
  • Example 23 When measuring the thickness as described below, the cross section of the optical sheet of Example 23 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 24 differs from the above-mentioned Example 21 in that the drying conditions for the first coating film were changed, but otherwise the optical sheet of Example 24 was obtained using the same materials and in the same manner as in Example 21.
  • the first coating film was first dried under the conditions of 60° C. ⁇ 20 seconds (drying air speed 0.4 m/s), and then dried under the conditions of 60° C. ⁇ 20 seconds (drying air speed 0.5 m/s).
  • Example 24 When measuring the thickness as described below, the cross section of the optical sheet of Example 24 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 25 differs from Example 21 in that the solid content ratio of the first curable resin composition and the solid content ratio of the second curable resin composition were changed, and the amount of the second curable resin composition applied was increased.
  • the optical sheet of Example 25 was obtained by the same materials and the same method as Example 21 in other respects.
  • a first curable resin composition having a solid content of 35% was used.
  • the first curable resin composition used in Example 25 was obtained by adjusting the amount of solvent contained in the first curable resin composition 2A.
  • a second curable resin composition having a solid content of 52% was used.
  • the second curable resin composition used in Example 25 was obtained by adjusting the amount of solvent contained in the second curable resin composition 2A.
  • the amount of the second curable resin composition applied was set to an amount that would produce a first portion with a dry thickness of 6.0 ⁇ m, assuming that there was no penetration into the base film or the first portion.
  • Example 25 When measuring the thickness as described below, the cross section of the optical sheet of Example 25 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 26 differs from Example 21 above in that the solid content ratio of the first curable resin composition and the solid content ratio of the second curable resin composition were changed, and the optical sheet of Example 26 was obtained by the same materials and the same method as Example 21 in other respects.
  • a first curable resin composition having a solid content of 20% was used.
  • the first curable resin composition used in Example 26 was obtained by adjusting the amount of solvent contained in the first curable resin composition 2A.
  • a second curable resin composition having a solid content of 40% was used.
  • the second curable resin composition used in Example 26 was obtained by adjusting the amount of solvent contained in the second curable resin composition 2A.
  • Example 26 When measuring the thickness as described below, the cross section of the optical sheet of Example 26 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 27 differs from Example 21 in that the leveling agent of the first curable resin composition 2A was omitted and that the leveling agent of the second curable resin composition 2A was changed, and the optical sheet of Example 27 was obtained using the same materials and the same method as Example 21 in other respects.
  • the first curable resin composition used to form the first coating film differs from the first curable resin composition 2A described above in that the leveling agent "Kyoeisha, LE-304, 0.2 parts by mass" was omitted, and the other respects were the same as the first curable resin composition 2A described above.
  • Example 27 the second curable resin composition used to form the second coating film differed from the second curable resin composition 2A described above in that the leveling agent "DIC, F-477, 0.3 parts by mass” was used instead of the leveling agent "Kyoeisha, LE-304, 0.4 parts by mass”.
  • the second curable resin composition used to form the second coating film was the same as the above-mentioned second curable resin composition 2A, except for the leveling agent.
  • Example 27 When measuring the thickness as described below, the cross section of the optical sheet of Example 27 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 21 differs from the above-mentioned Example 21 in that the base film was changed, the amount of the first curable resin composition 2A applied was increased and the amount of the second curable resin composition 2A applied was decreased, the integrated amount of ultraviolet light irradiated during curing of the second coating film was reduced, the leveling agent for the first curable resin composition 2A was changed, and the leveling agent for the second curable resin composition 2A was changed. Otherwise, the optical sheet of Comparative Example 21 was obtained using the same materials and the same method as in Example 21.
  • Comparative Example 21 a base film made of triacetyl cellulose having a thickness of 40 ⁇ m was used.
  • the content ratio of the plasticizer in the base film of Comparative Example 21 was higher than that of the base film of Example 21.
  • the amount of the first curable resin composition 2A applied was an amount that would produce a first portion having a dry thickness of 4.0 ⁇ m, assuming that there was no penetration into the base film.
  • the amount of the second curable resin composition 2A applied was an amount that would produce a second portion having a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the base film and the first portion.
  • the cumulative amount of ultraviolet light irradiated during curing of the second coating film was 132 mJ/cm 2 .
  • the first curable resin composition used to form the first coating film differed from the first curable resin composition 2A described above in that the leveling agent "0.2 parts by mass of F-568 manufactured by DIC” was used instead of the leveling agent "0.2 parts by mass of LE-304 manufactured by Kyoeisha.”
  • the first curable resin composition used to form the first coating film was the same as the first curable resin composition 2A described above, except for the leveling agent.
  • the second curable resin composition used to form the second coating film differed from the above-mentioned second curable resin composition 2A in that the leveling agent "DIC, F-477, 0.4 parts by mass” was used instead of the leveling agent "Kyoeisha, LE-304, 0.4 parts by mass.”
  • the second curable resin composition used to form the second coating film was the same as the above-mentioned second curable resin composition 2A except for the leveling agent.
  • Example 21 When measuring the thickness as described below, the cross section of the optical sheet according to Comparative Example 21 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 22 differs from Example 21 above in that the composition of the first curable resin composition was changed, the amount of the first curable resin composition applied was changed, and the amount of the second curable resin composition 2A applied was changed.
  • the optical sheet of Comparative Example 22 was obtained by using the same materials and the same method as in Example 21.
  • the first curable resin composition 2A used in Example 21 contained a polyfunctional monomer and an acrylic polymer (1) mixed in a solid content mass ratio of 20:80.
  • the first curable resin composition used in Comparative Example 22 was obtained by mixing a polyfunctional monomer and an indole-based ultraviolet absorber mixed in a mass ratio of 95:5 instead of the polyfunctional monomer and acrylic polymer (1) of the first curable resin composition 2A.
  • the polyfunctional monomer contained in the first curable resin composition used in Comparative Example 22 was the same as the polyfunctional monomer contained in the first curable resin composition 2A.
  • the solid content of the first curable resin composition used in Comparative Example 22 was 27.5%, which was the same as the solid content of the first curable resin composition 2A.
  • the indole-based ultraviolet absorber contained in the first curable resin composition used in Comparative Example 22 was a product name "BONASORB UA-3912" manufactured by Orient Chemical Industry Co., Ltd.
  • the amount of the first curable resin composition applied was set to an amount that would create a first portion with a dry thickness of 4.0 ⁇ m, assuming no penetration into the base film.
  • the amount of the second curable resin composition 2A applied was set to an amount that would create a second portion with a dry thickness of 8.0 ⁇ m, assuming no penetration into the base film or first portion.
  • the cross section of the optical sheet according to Comparative Example 22 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 23 differs from the above-mentioned Comparative Example 21 in that the coating amount of the first curable resin composition 2A was increased, and otherwise the optical sheet of Comparative Example 23 was obtained using the same materials and the same method as in Comparative Example 21.
  • the coating amount of the first curable resin composition 2A was set to an amount that would produce a first portion with a dry thickness of 5.5 ⁇ m, assuming that there was no penetration into the base film.
  • the cross section of the optical sheet according to Comparative Example 23 was observed in the same manner as in Example 21.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • the amount of the first curable resin composition 2A applied was set to an amount that would produce a first portion having a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • an optical sheet according to Comparative Example 24 was obtained. That is, in the optical sheet according to Comparative Example 24, the first layer was composed only of the first portion prepared using the first curable resin composition 2A.
  • the thickness of the layer produced using the first curable resin composition 2A in Comparative Example 24 was different from the thickness of the layer produced using the first curable resin composition 2A in Example 21.
  • the method and conditions for producing the first layer using the first curable resin composition 2A in Comparative Example 24 were the same as the method and conditions for producing the first part using the first curable resin composition 2A in Example 21.
  • Example 24 When measuring the thickness as described below, the cross section of the optical sheet according to Comparative Example 24 was observed in the same manner as in Example 21.
  • the first curable resin composition 2A penetrated the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • Thickness and thickness ratio>> A sample for thickness measurement was prepared by the following first and second steps.
  • the embedded sample was prepared using the following procedure. First, the cut sample was placed in a silicon embedding plate. Embedding resin was poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin was allowed to harden within the silicon embedding plate. Next, the cut sample and the embedding resin surrounding it were removed from the silicon embedding plate to obtain an embedded sample. The embedded sample was shaped like a block.
  • the silicon embedding plate used was manufactured by Dosaka EM.
  • the embedding resin was epoxy resin.
  • the embedding resin was obtained by mixing Struers' product name "Epofix” and the same company's product name "Epofix Hardener” in a ratio of 10:1.2.
  • the embedding resin was allowed to harden by leaving it at room temperature for 12 hours.
  • the block-shaped embedded sample was cut with a diamond knife to prepare a slice sample.
  • the slice sample was aligned along the first direction (thickness direction, lamination direction) of the target optical sheet.
  • slice samples without defects such as holes and with a uniform thickness of about 60 nm to 100 nm were used as thickness measurement samples.
  • microtome was used to cut the embedded samples.
  • the microtome was an Ultramicrotome EM UC7 manufactured by Leica Microsystems. When cutting the block-shaped embedded sample, it was first roughly cut as coarse trimming, and finally, precisely trimmed with a diamond knife to obtain a section sample.
  • the thickness of each layer was measured using the observation image of the thickness measurement sample by a scanning transmission electron microscope.
  • the thickness measurement sample was stained. Osmium tetroxide was used for staining.
  • the stained thickness measurement sample was imaged using a scanning transmission electron microscope to obtain an observation image of the thickness measurement sample.
  • the scanning transmission electron microscope used was an S4800 manufactured by Hitachi High-Tech Corporation.
  • the imaging conditions were as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • Ten observation images were obtained from one thickness measurement sample for each example.
  • the ten observation images were obtained at ten observation positions (measurement positions) spaced at a pitch of 10 ⁇ m in a direction perpendicular to the first direction of the optical sheet in question.
  • the thickness T120 ( ⁇ m) of the first layer and the thickness T130 ( ⁇ m) of the second layer for the optical sheet in each example were measured.
  • the thickness ratio (T120/T130) was calculated based on the thickness T120 ( ⁇ m) of the first layer and the thickness T130 ( ⁇ m) of the second layer measured from each observation image.
  • the calculated average of 10 measurements of thickness T120 ( ⁇ m) measured from 10 observation images was taken as the thickness T120 ( ⁇ m) of the first layer.
  • the calculated average of 10 measurements of thickness T130 ( ⁇ m) measured from 10 observation images was taken as the thickness T130 ( ⁇ m) of the second layer.
  • the calculated average of 10 values of thickness ratio (T120/T130) measured from 10 observation images was taken as the thickness ratio (T120/T130) of the optical sheet.
  • the measurement results of the thickness ( ⁇ m) of the first layer, the measurement results of the thickness ( ⁇ m) of the second layer, and the measurement results of the thickness ratio (T120/T130) are shown in Table 3. In Table 3, examples with a thickness ratio of 1.5 to 7.5 are marked "OK", and other examples are marked "NG".
  • Spectral transmittance >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The spectral transmittance (%) was measured. The spectral transmittance (%) was measured for wavelengths of 380 nm, 410 nm, 420 nm, and 440 nm. The ultraviolet-visible spectrophotometer "UV-2600" was used. The measurement results of the spectral transmittance at each wavelength are shown in Table 3. In Table 3, the spectral transmittance at 410 nm is 15% or less, and the spectral transmittance at a wavelength of 440 nm is 15% or less. The examples having a spectral transmittance of 70% or more were marked as "OK", and the other examples were marked as "NG".
  • optical sheets according to Examples 21 to 27 and Comparative Examples 21 to 24 were placed on the display surface of a commercially available organic EL display device, and the image displayed by the organic EL display device was observed through the optical sheet.
  • Examples 21 to 27, Comparative Example 21, Comparative Example 23, and Comparative Example 24 no change in color was perceptible between the image when the optical sheet was installed and the image when the optical sheet was not installed.
  • Comparative Example 22 a change in the color of the image was confirmed when the optical sheet was installed.
  • Pencil hardness >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The pencil hardness was measured using a pencil hardness tester manufactured by Toyo Seiki Seisakusho Co., Ltd. The pencil hardness evaluated according to the above-mentioned evaluation criteria is shown in Table 3.
  • the sample was placed on the base plate with the second surface of the optical sheet in contact with the base plate.
  • the height of the four corners of the sample from the base plate was measured as the float (mm).
  • the maximum of the four float measurements taken for one sample was taken as the float for that sample.
  • the float was measured for each of the three samples.
  • the arithmetic mean value of the three float measurements was taken as the amount of deformation for that example.
  • the deformation measurement results are shown in Table 3.
  • Measurement conditions Measurement method: Wide/Narrow X-ray source: Monochrome A1K ⁇ X-ray output: 150W Emission current: 10mA Acceleration voltage: 15 kV Charge neutralization mechanism: ON Measurement area: 300 ⁇ m x 700 ⁇ m Pass Energy: Survey: 160eV, Narrow: 40eV Photoelectron capture angle: 90° Auto Z: ON Peak shift correction: Correction was made so that the C-C peak in the C1s peak was 285.0 eV. Waveform separation of narrow peaks: Executed using the GL function in the analysis software attached to the device. Etching ions: Ar monoatomic ions
  • Table 3 shows the percentage (%) of the amount of each element detected, with the total amount of elements detected being 100.
  • Example 21 the ratio of silicon element to carbon element was 0.02 (2%) or more.
  • the cross section of the first layer of Example 21 was observed.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used for the cross section observation. When the cross section was observed at an accelerating voltage of 10 kV to 30 kV and a magnification of 5000 times, the silica added as a lubricant was dispersed without being unevenly distributed in aggregate.
  • the epoxy resin used for embedding was obtained by mixing Struers' product name "Epofix” with the same company's product name “Epofix Hardener” in a ratio of 10:1.2.
  • a microtome was used to cut the embedded samples.
  • the microtome used was Leica Microsystems' product name "Ultramicrotome EM UC7.”
  • the indentation hardness H IT (MPa) at the cross section of the first layer, the indentation hardness H IT (MPa) at the cross section of the second layer, and the indentation hardness H IT (MPa) at the cross section of the base layer were measured by the above-mentioned method.
  • the indentation hardness H IT at the cross section of each layer was measured using a measuring device "TI-950 TriboIndenter” manufactured by BRUKER.
  • the indenter used to measure the indentation hardness H IT at the cross section of each layer was "TI-0039" manufactured by BRUKER.
  • the measurement results of the indentation hardness H IT (MPa) at the cross section of each layer are shown in Table 3.
  • the indentation hardness at the cross section of each layer was the arithmetic average value of the indentation hardness measured at 10 measurement positions.
  • the ten measurement positions were located at ten positions on one slice sample, spaced apart at 5 ⁇ m intervals in a direction perpendicular to the first direction of the optical sheet.
  • Total light transmittance >> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The total light transmittance was measured. A haze meter "HM-150" manufactured by Murakami Color Research Laboratory was used to measure the total light transmittance. The measurement results of the total light transmittance are shown in Table 3.
  • Yellowness index YI value>> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and comparative examples. The samples were visually confirmed to be free of any abnormalities such as dust or scratches. The yellowness index YI value of the optical sheets according to each example was measured by the method described above. The yellowness index YI value was measured using an ultraviolet-visible spectrophotometer "UV-2600" manufactured by Shimadzu Corporation. The measurement results of the yellowness index YI value are shown in Table 3.
  • the optical sheet 210 includes a first layer 220.
  • the first layer 220 includes a cured product of a curable resin composition and an ultraviolet absorbing agent.
  • the first layer 220 including the ultraviolet absorbing agent provides the optical sheet 210 with a blue light blocking function.
  • the optical sheet 210 satisfies the following conditions (3A) to (3C) regarding the spectral transmittance.
  • (3A) The spectral transmittance of the optical sheet 210 at a wavelength of 380 nm is less than 1%.
  • (3B) The spectral transmittance of the optical sheet 210 at a wavelength of 440 nm is 70% or more.
  • the slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less.
  • the spectral transmittance of the optical sheet 210 is measured for each wavelength in 0.5 nm increments within the wavelength range of 379.5 nm to 440.5 nm. The results of the spectral transmittance measurements are used to determine whether conditions (3A)-(3C) are met.
  • Condition (3A) is determined based on the measured value of the spectral transmittance at a wavelength of 380.0.
  • Condition (3B) is determined based on the measured value of the spectral transmittance at a wavelength of 440.0.
  • the slope of the spectral transmittance indicates the increase in transmittance (%) per 1 nm of wavelength.
  • the slope of the spectral transmittance at wavelength X is the value obtained by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral transmittance (%) at wavelength X+0.5 (nm).
  • condition (3C) is determined to be met. If the wavelength at which the slope of the spectral transmittance is maximum is 395.5 nm or less, condition (3C) is determined to be not met. If the wavelength at which the slope of the spectral transmittance is maximum is 420.5 nm or more, condition (3C) is determined to be not met.
  • the optical sheet 210 may block light having a wavelength of 380 nm or less with high efficiency.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm may be less than 1%, 0.5% or less, or 0.4% or less.
  • the optical sheet 210 may transmit light having a wavelength of 440 nm or more with high transmittance.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 440 nm may be 70% or more, 80% or more, or 85% or more.
  • condition (3C) the manner in which the spectral transmittance increases with increasing wavelength is specified.
  • the slope of the spectral transmittance has the same meaning as the value of the differential equation of the function that represents the spectral transmittance. Therefore, at the wavelength at which the slope of the spectral transmittance is at its maximum value and at wavelengths around that wavelength, the spectral transmittance increases rapidly with increasing wavelength.
  • conditions (3A) and (3C) light in the wavelength range of 380 nm or more and 400 nm or less is blocked by optical sheet 210 with sufficient efficiency.
  • satisfying conditions (3B) and (3C) light in the wavelength range of 420 nm or more and 440 nm or less can pass through optical sheet 210 with sufficient transmittance.
  • the optical sheet 210 can sufficiently block light with a wavelength of 400 nm or less, thereby suppressing problems caused by blue light.
  • the image light emitted from the display device 60 can pass through the optical sheet 210.
  • the optical sheet 210 can sufficiently block light with a wavelength of 400 nm or less from the image light.
  • eye strain of the observer of the image can be alleviated.
  • external light such as sunlight can enter the optical sheet 210.
  • Light with a wavelength of 420 nm or more can pass through the optical sheet 210 with high transmittance. This makes it possible to suppress changes and deterioration in the color of the image observed through the optical sheet 210.
  • the wavelength at which the maximum value of the slope of the spectral transmittance specified by condition (3C) is obtained may be 405 nm or more, 408 nm or more, 410 nm or more, 412 nm or more, or 415 nm or more.
  • the wavelength at which the maximum value of the slope of the spectral transmittance defined by condition (3C) is obtained may be 419.5 nm or less, or 419 nm or less.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained may be 405 nm or more and 420 nm or less, 408 nm or more and 420 nm or less, 410 nm or more and 420 nm or less, 412 nm or more and 420 nm or less, or 415 nm or more and 420 nm or less.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained may be 400 nm or more and 419.5 nm or less, 405 nm or more and 419.5 nm or less, 408 nm or more and 419.5 nm or less, 410 nm or more and 419.5 nm or less, 412 nm or more and 419.5 nm or less, or 415 nm or more and 419.5 nm or less.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained may be 400 nm or more and 419 nm or less, 405 nm or more and 419 nm or less, 408 nm or more and 419 nm or less, 410 nm or more and 419 nm or less, 412 nm or more and 419 nm or less, or 415 nm or more and 419 nm or less.
  • a lower limit may be set for the maximum value of the slope of the spectral transmittance specified in condition (3C), i.e., the maximum value of the slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm to 440 nm.
  • the maximum value of the slope of the spectral transmittance specified in condition (3C) may be 2.0 (%/nm) or more, 2.5 (%/nm) or more, 3.0 (%/nm) or more, 3.5 (%/nm) or more, or 4.0 (%/nm) or more.
  • An upper limit may be set for the maximum value of the slope of the spectral transmittance specified in condition (3C). By setting an upper limit for the maximum value of the spectral transmittance, color changes and deterioration can be suppressed more naturally.
  • the maximum value of the slope of the spectral transmittance specified in condition (3C) may be 8.0 (%/nm) or less, 7.0 (%/nm) or less, 6.0 (%/nm) or less, 5.5 (%/nm) or less, or 5.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 8.0 (%/nm) or less, 2.5 (%/nm) or more and 8.0 (%/nm) or less, 3.0 (%/nm) or more and 8.0 (%/nm) or less, 3.5 (%/nm) or more and 8.0 (%/nm) or less, or 4.0 (%/nm) or more and 8.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 7.0 (%/nm) or less, 2.5 (%/nm) or more and 7.0 (%/nm) or less, 3.0 (%/nm) or more and 7.0 (%/nm) or less, 3.5 (%/nm) or more and 7.0 (%/nm) or less, or 4.0 (%/nm) or more and 7.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 6.0 (%/nm) or less, 2.5 (%/nm) or more and 6.0 (%/nm) or less, 3.0 (%/nm) or more and 6.0 (%/nm) or less, 3.5 (%/nm) or more and 6.0 (%/nm) or less, or 4.0 (%/nm) or more and 6.0 (%/nm) or less.
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 5.5 (%/nm) or less, 2.5 (%/nm) or more and 5.5 (%/nm) or less, 3.0 (%/nm) or more and 5.5 (%/nm) or less, 3.5 (%/nm) or more and 5.5 (%/nm) or less, or 4.0 (%/nm) or more and 5.5 (%/nm).
  • the maximum value of the slope of the spectral transmittance may be 2.0 (%/nm) or more and 5.0 (%/nm) or less, 2.5 (%/nm) or more and 5.0 (%/nm) or less, 3.0 (%/nm) or more and 5.0 (%/nm) or less, 3.5 (%/nm) or more and 5.0 (%/nm) or less, or 4.0 (%/nm) or more and 5.0 (%/nm) or less.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm may be less than 1%, may be 0.5% or less, or may be 0.4% or less. By setting the upper limit of the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm in this manner, blue light can be blocked more effectively. No lower limit is set for the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm may be 0% or more, or may be greater than 0%.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm may be 0% or more and less than 1%, 0% or more and less than 0.5%, or 0% or more and less than 0.4%.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 380 nm may be greater than 0% and less than 1%, greater than 0% and less than 0.5%, or greater than 0% and less than 0.4%.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 440 nm may be 70% or more, 75% or more, 80% or more, or 85% or more.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 440 nm may be 100% or less, or may be less than 100%.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 440 nm may be 70% or more and 100% or less, 75% or more and 100% or less, 80% or more and 100% or less, or 85% or more and 100% or less.
  • the spectral transmittance of the optical sheet 210 at a wavelength of 440 nm may be 70% or more and less than 100%, 75% or more and less than 100%, 80% or more and less than 100%, or 85% or more and less than 100%.
  • the method for measuring the spectral transmittance is the same as that described in the first embodiment.
  • FIG. 10 is a graph showing the spectral transmittance and slope of the spectral transmittance of the optical sheets for samples C1 to C5.
  • Samples C1 to C3 satisfy all of conditions (3A), (3B), and (3C).
  • Sample C1 shows the spectral transmittance for the optical sheet according to Example 31 described below.
  • Sample C2 shows the spectral transmittance for the optical sheet according to Example 32 described below.
  • Sample C3 shows the spectral transmittance for the optical sheet according to Example 36 described below.
  • the spectral transmittance (%) may increase monotonically with increasing wavelength.
  • the slope of the spectral transmittance at each wavelength in 0.5 nm intervals within the wavelength range of 380 nm to 440 nm may be greater than 0. According to these examples, changes and deterioration in color of the image observed through the optical sheet 210 can be more naturally suppressed.
  • the first layer 220 further includes a cured product of the curable resin composition.
  • the cured product of the curable resin composition is also referred to as a resin cured product.
  • the resin cured product can impart high hardness to the first layer 220 and the optical sheet 210.
  • the first layer 220 functions as a so-called hard coat layer.
  • the optical sheet 210 with improved hardness has excellent scratch resistance. When the optical sheet 210 is in use, scratches on the optical sheet 210 can be suppressed.
  • the optical sheet 210 is also suitable for a touch panel member 55 (see FIG. 5) that is expected to come into contact with a finger or a pen during use.
  • a resin layer containing a cured resin product is obtained by curing a coating film of a curable resin composition.
  • the coating film can be cured by exposing the coating film to light, which promotes a crosslinking reaction. High-energy short-wavelength light is usually used for exposure.
  • the ultraviolet absorber added to the curable resin composition can absorb the light used in the curing process of the coating film. In other words, the ultraviolet absorber can inhibit the curing process of the curable resin composition.
  • the scratch resistance may be significantly reduced. If the hardness of the first layer containing the cured resin is low, the UV absorber may bleed out from the first layer when the optical sheet is used. If the UV absorber bleeds out, the blue light blocking function of the optical sheet 210 will also be insufficient.
  • a measure is taken to improve the hardness of the first layer 220 and the optical sheet 210.
  • the optical sheet 210 according to the third embodiment includes a second layer 230 adjacent to the first layer 220.
  • the thickness ratio is 1.2 or more and 7.5 or less.
  • the thickness ratio is determined using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 210 to be evaluated is observed with a scanning transmission electron microscope, and the thicknesses T220 and T230 are measured from the image observed with the scanning transmission electron microscope.
  • the thickness ratio at the measurement position is calculated from the thickness T220 of the first layer 220 and the thickness T230 of the second layer 230 measured at the same position in a direction perpendicular to the thickness direction observed with the scanning transmission electron microscope.
  • the thicknesses T220 and T230 are measured at 10 measurement positions, and the thickness ratios of the 10 measurements are calculated.
  • the thickness ratio of the optical sheet 210 is determined as the arithmetic mean value of the 10 thickness ratios.
  • the observation image of the cross section of the optical sheet 210 to be evaluated is obtained by observing the thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained by the following first and second steps.
  • a cut sample is cut out from the optical sheet to be evaluated.
  • the cut sample is visually checked for any abnormalities such as dirt or scratches.
  • the cut sample is embedded in resin to prepare an embedded sample.
  • the embedded sample is prepared as follows. First, the cut sample is placed in a silicon embedding plate. Embedding resin is poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin is hardened inside the silicon embedding plate. Next, the cut sample and the embedding resin that encases it are removed from the silicon embedding plate to obtain the embedded sample. The embedded sample is shaped like a block.
  • the embedding resin is epoxy resin.
  • the block-shaped embedded sample is cut to prepare a slice sample.
  • the slice sample includes a surface along a first direction (thickness direction, lamination direction) of the target optical sheet.
  • a slice sample that is free of defects such as holes and has a uniform thickness of about 60 nm to 100 nm is used as a thickness measurement sample.
  • the imaging conditions of the scanning transmission electron microscope are as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • the optical sheet 210 may include a first surface 211 and a second surface 212 that face each other in a first direction D1.
  • the first surface 211 and the second surface 212 constitute a pair of main surfaces of the optical sheet 210.
  • the first direction D1 is the stacking direction of the multiple layers included in the optical sheet 210. From the first surface 211 to the second surface 212 in the first direction D1, the first layer 220 and the second layer 230 are positioned in this order.
  • the hardness of the first surface 211 can be improved, and the scratch resistance of the first surface 211 can also be improved.
  • the pencil hardness of the first surface 211 can be made 2H or more.
  • the load capacity of the first surface 211 in a steel wool scratch resistance test can be made 150 g or more.
  • the indentation hardness of the first surface 211 with an indentation depth of 100 nm can be made 330 MPa or more.
  • Pencil hardness is an index that indicates resistance to defects such as scratches that occur when a pencil lead is pressed against a sample to be evaluated and moved.
  • the method for measuring pencil hardness is the same as the measurement method described in the first embodiment.
  • the steel wool scratch resistance test is an index showing resistance to defects such as scratches that occur when steel wool is pressed against the sample to be evaluated and moved relative to it.
  • the method for measuring the load capacity in the steel wool scratch resistance test is the same as the measurement method described in the first embodiment.
  • the indentation hardness H IT is a hardness measured by a nanoindentation method using a nanoindenter.
  • the measurement position of the indentation hardness H IT in the cross section of the first layer 20 is a position shifted by 1.2 ⁇ m from the first side surface 221 to the second side surface 222 of the first layer 220 along the normal direction of the optical sheet 210. That is, assuming that the first layer 220 corresponds to the functional layer 20, the indentation hardness H IT in the cross section of the first layer 220 is measured at the first position 26 described with reference to FIG. 2A in the first embodiment.
  • the method of measuring the indentation hardness is the same as the measurement method described in the first embodiment.
  • the first side surface 221 and the second side surface 222 are a pair of main surfaces of the first layer 220.
  • the first side surface 221 is located on a first side in a first direction D1 that is a normal direction of the first layer 220.
  • the first side surface 221 is a surface that is closer to the first surface 211 in the first direction D1.
  • the first side surface 221 of the first layer 220 constitutes the first surface 211 of the optical sheet 210.
  • the second side surface 222 is located on a second side in the first direction D1.
  • the second side surface 222 is a surface that is closer to the second surface 212 in the first direction D1.
  • the details of the effect of the thickness ratio (T220/T230) of the thickness T220 of the first layer 220 to the thickness T230 of the second layer 230 on the hardness of the first layer 220 and the hardness at the first surface 211 of the optical sheet 210 are unknown.
  • the hardness of the first layer 220 and the hardness at the first surface 211 were improved by providing the second layer 230 adjacent to the first layer 220 containing the cured resin and the UV absorber as a thin layer so as to satisfy the thickness ratio.
  • the second layer 230 tends to have a lower hardness than the first layer 220, which contains a cured resin.
  • the second layer 230 has an appropriate thickness that is thinner than the first layer 220, the adhesion of the first layer 220 to the optical sheet 210 is more easily ensured, and in addition, the hardness of the second layer 230 is more easily prevented from being reflected in the hardness of the first surface 211.
  • the present disclosure is not bound by this inference.
  • the thickness ratio of the first layer 220 to the second layer 230 has the following relationship with the hardness of the first surface 211 of the optical sheet 210 and the first layer 220:
  • the thickness ratio may be 1.2 or more, and may further be 1.5 or more, 1.6 or more, 1.7 or more, 2.6 or more, 2.7 or more, or 3.2 or more.
  • the pencil hardness of the first surface 211 may be 2H or more, 3H or more, or 4H or more.
  • the load capacity of the first surface 211 in a steel wool scratch resistance test may be 150g or more, 200g or more, 250g or more, or 300g or more.
  • the indentation hardness of the cross section of the first layer 220 at an indentation depth of 100 nm may be 330 MPa or more, 333 MPa or more, 342 MPa or more, or 379 MPa or more.
  • the pencil hardness of the first surface 211 may be 2H or more and 8H or less, 3H or more and 8H or less, or 4H or more and 8H or less.
  • the load capacity in the steel wool scratch resistance test on the first surface 211 may be 150 g or more and 300 g or less, 200 g or more and 300 g or less, 250 g or more and 300 g or less, or 300 g.
  • the indentation hardness in the cross section of the first layer 220 when the indentation depth is 100 nm may be 330 MPa or more and 600 MPa or less, 333 MPa or more and 600 MPa or less, 342 MPa or more and 600 MPa or less, or 379 MPa or more and 600 MPa or less.
  • the thickness ratio becomes too large, the hardness of the first layer 220 and the hardness at the first surface 211 may decrease.
  • the thickness ratio may be 7.5 or less.
  • the thickness ratio becomes too large, other problems may occur.
  • a lower limit to the thickness ratio the hardness of the first layer 220 and the hardness at the first surface 211 increase.
  • the thickness ratio becomes too large, curling or warping may occur in the optical sheet 210.
  • an upper limit to the thickness ratio deformation such as curling or warping can be suppressed.
  • the thickness ratio may be 7.5 or less, or may be 7.4 or less, 5.0 or less, 4.8 or less, or 3.9 or less.
  • the upper limit of the thickness ratio in this way, deformation such as curling or warping of the optical sheet 210 can be suppressed.
  • the hardness of the first layer 220 and the hardness of the first surface 211 can be improved.
  • the details of why deformation such as curling and warping can be suppressed by setting an upper limit on the thickness ratio are unclear.
  • the following can be inferred as one of the reasons for deformation suppression.
  • the first layer 220 contains a resin cured product, it may shrink during the curing process. This curing shrinkage may cause deformation such as curling and warping in the optical sheet 210.
  • the second layer 230 adjacent to the first layer 220 has a thickness that is at least a certain percentage of the thickness of the first layer 220. Therefore, it is inferred that the second layer 230 at least partially absorbs the deformation of the first layer 220, and deformation of the optical sheet 210 is suppressed.
  • the present disclosure is not bound by this inference.
  • the thickness ratio may be 1.2 or more and 7.5 or less, 1.2 or more and 7.4 or less, 1.2 or more and 5.0 or less, 1.2 or more and 4.8 or less, or 1.2 or more and 3.9 or less.
  • the thickness ratio may be 1.5 or more and 7.5 or less, 1.5 or more and 7.4 or less, 1.5 or more and 5.0 or less, 1.5 or more and 4.8 or less, or 1.5 or more and 3.9 or less.
  • the thickness ratio may be 1.6 or more and 7.5 or less, 1.6 or more and 7.4 or less, 1.6 or more and 5.0 or less, 1.6 or more and 4.8 or less, or 1.6 or more and 3.9 or less.
  • the thickness ratio may be 1.7 or more and 7.5 or less, 1.7 or more and 7.4 or less, 1.7 or more and 5.0 or less, 1.7 or more and 4.8 or less, or 1.7 or more and 3.9 or less.
  • the thickness ratio may be 2.6 to 7.5, 2.6 to 7.4, 2.6 to 5.0, 2.6 to 4.8, or 2.6 to 3.9.
  • the thickness ratio may be 2.7 to 7.5, 2.7 to 7.4, 2.7 to 5.0, 2.7 to 4.8, or 2.7 to 3.9.
  • the thickness ratio may be 3.2 to 7.5, 3.2 to 7.4, 3.2 to 5.0, 3.2 to 4.8, or 3.2 to 3.9.
  • a lower limit may be set for the thickness T220 of the first layer 220.
  • the thickness T220 of the first layer 220 may be 3.2 ⁇ m or more, 3.5 ⁇ m or more, 3.9 ⁇ m or more, 4.5 ⁇ m or more, 5.5 ⁇ m or more, or 7.0 ⁇ m or more.
  • An upper limit may be set for the thickness T220 of the first layer 220.
  • the thickness T220 of the first layer 220 may be 8.9 ⁇ m or less, 8.0 ⁇ m or less, or 7.6 ⁇ m or less.
  • the thickness T220 may be 3.2 ⁇ m or more and 8.9 ⁇ m or less, 3.5 ⁇ m or more and 8.9 ⁇ m or less, 3.9 ⁇ m or more and 8.9 ⁇ m or less, 4.5 ⁇ m or more and 8.9 ⁇ m or less, 5.5 ⁇ m or more and 8.9 ⁇ m or less, or 7.0 ⁇ m or more and 8.9 ⁇ m or less.
  • the thickness T220 may be 3.2 ⁇ m or more and 8.0 ⁇ m or less, 3.5 ⁇ m or more and 8.0 ⁇ m or less, 3.9 ⁇ m or more and 8.0 ⁇ m or less, 4.5 ⁇ m or more and 8.0 ⁇ m or less, 5.5 ⁇ m or more and 8.0 ⁇ m or less, or 7.0 ⁇ m or more and 8.0 ⁇ m or less.
  • the thickness T220 may be 3.2 ⁇ m or more and 7.6 ⁇ m or less, 3.5 ⁇ m or more and 7.6 ⁇ m or less, 3.9 ⁇ m or more and 7.6 ⁇ m or less, 4.5 ⁇ m or more and 7.6 ⁇ m or less, 5.5 ⁇ m or more and 7.6 ⁇ m or less, or 7.0 ⁇ m or more and 7.6 ⁇ m or less.
  • a lower limit may be set for the thickness T230 of the second layer 230.
  • the thickness T230 of the second layer 230 may be 1.2 ⁇ m or more, 1.5 ⁇ m or more, 1.8 ⁇ m or more, or 1.8 ⁇ m or more.
  • An upper limit may be set for the thickness T230 of the second layer 230.
  • the thickness T230 of the second layer 230 may be 3.5 ⁇ m or less, 3.0 ⁇ m or less, 2.7 ⁇ m or less, 2.6 ⁇ m or less, or 2.4 ⁇ m or less.
  • the thickness T230 may be 1.2 ⁇ m or more and 3.5 ⁇ m or less, 1.5 ⁇ m or more and 3.5 ⁇ m or less, 1.8 ⁇ m or more and 3.5 ⁇ m or less, or 1.8 ⁇ m or more and 3.5 ⁇ m or less.
  • the thickness T230 may be 1.2 ⁇ m or more and 3.0 ⁇ m or less, 1.5 ⁇ m or more and 3.0 ⁇ m or less, 1.8 ⁇ m or more and 3.0 ⁇ m or less, or 1.8 ⁇ m or more and 3.0 ⁇ m or less.
  • the thickness T230 may be 1.2 ⁇ m or more and 2.7 ⁇ m or less, 1.5 ⁇ m or more and 2.7 ⁇ m or less, 1.8 ⁇ m or more and 2.7 ⁇ m or less, or 1.8 ⁇ m or more and 2.7 ⁇ m or less.
  • the thickness T230 may be 1.2 ⁇ m or more and 2.6 ⁇ m or less, 1.5 ⁇ m or more and 2.6 ⁇ m or less, 1.8 ⁇ m or more and 2.6 ⁇ m or less, or 1.8 ⁇ m or more and 2.6 ⁇ m or less.
  • the thickness T230 may be 1.2 ⁇ m or more and 2.4 ⁇ m or less, 1.5 ⁇ m or more and 2.4 ⁇ m or less, 1.8 ⁇ m or more and 2.4 ⁇ m or less, or 1.8 ⁇ m or more and 2.4 ⁇ m or less.
  • the thickness T220 of the first layer 220 and the thickness T230 of the second layer 230 are each measured using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 210 to be evaluated is observed with a scanning transmission electron microscope, and the thicknesses T220 and T230 are measured from the observation image of the scanning transmission electron microscope.
  • the observation image of the cross section of the optical sheet 210 to be evaluated is obtained by observing a thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained through the first and second steps described above.
  • the thickness T220 is determined as the arithmetic mean value of ten thickness measurement values measured at ten measurement positions.
  • the thickness T230 is determined as the arithmetic mean value of ten thickness measurement values measured at ten measurement positions.
  • the hardness of the first layer 220 may be greater than the hardness of the second layer 230.
  • the indentation hardness H IT measured on a cross section of the first layer 220 may be greater than the indentation hardness H IT measured on a cross section of the second layer 230.
  • the measurement position of the indentation hardness H IT of the cross section of the second layer 230 is the center position in the thickness direction of the second layer 230. That is, assuming that the second layer 230 corresponds to the intermediate layer 30, the indentation hardness H IT of the cross section of the second layer 230 is measured at the center position 31 described with reference to FIG. 2A in the first embodiment.
  • the indentation hardness H IT of the cross section of the second layer 230 is measured by pressing an indenter into this measurement position.
  • the indentation hardness H IT of the cross section of the second layer 230 is otherwise measured by the same measurement method as the measurement method of the indentation hardness H IT of the cross section of the first layer 220 described above.
  • the second layer 230 may include one or more of an acrylic resin and a cellulose resin. According to this example, a relationship in which the hardness of the first layer 220 is greater than that of the second layer 230 is stably generated.
  • the indentation hardness H IT measured at the cross section of the first layer 220 can be stably greater than the indentation hardness H IT measured at the cross section of the second layer 230.
  • the hardness of the first layer 220, the pencil hardness of the first surface 211, the load capacity in the steel wool scratch resistance test on the first surface 211, and the indentation hardness H IT at the cross section of the first layer 220 can be increased.
  • deformation such as curling and warping of the optical sheet 210 can be stably suppressed.
  • the second layer 230 may contain the same resin component as at least a part of the resin component contained in the first layer 220. According to this example, it is possible to improve the adhesion between the second layer 230 and the first layer 220. When the adhesion between the second layer 230 and the first layer 220 is improved, it is possible to stably improve the hardness of the first layer 220 and the hardness at the first surface 211. As a result, the pencil hardness at the first surface 211, the load capacity in a steel wool scratch resistance test at the first surface 211, and the indentation hardness HIT at a cross section of the first layer 220 may increase.
  • FT-IR Fourier transform infrared spectroscopy
  • the second layer 230 may include a monomer. According to this example, a relationship in which the hardness of the first layer 220 is greater than that of the second layer 230 is stably generated.
  • the indentation hardness H IT measured at the cross section of the first layer 220 can be stably greater than the indentation hardness H IT measured at the cross section of the second layer 230.
  • the pencil hardness at the first surface 211, the load capacity in the steel wool scratch resistance test at the first surface 211, and the indentation hardness H IT at the cross section of the first layer 220 can be increased.
  • deformation such as curling and warping of the optical sheet 210 can be stably suppressed.
  • the second layer 230 may contain at least a part of the monomer contained in the curable resin composition for producing the first layer 220. According to this example, a relationship in which the hardness of the first layer 220 is greater than that of the second layer 230 is stably generated. For example, the indentation hardness H IT measured on the cross section of the first layer 220 can be stably made greater than the indentation hardness H IT measured on the cross section of the second layer 230. In addition, the adhesion between the second layer 230 and the first layer 220 can be improved. As a result, the hardness of the first layer 220 and the hardness of the first surface 211 of the optical sheet 210 can be stably improved.
  • Whether the second layer 230 contains a monomer is determined by staining with osmium tetroxide.
  • a cross-sectional sample is cut out from the optical sheet 210 by cutting. The thickness of the sample is about 80 nm. The cut out sample is collected on a Cu mesh. This sample is stained with osmium tetroxide for 30 minutes by a vapor-phase staining method. The portion of the stained sample corresponding to the second layer 230 is observed using a scanning transmission electron microscope (STEM). The unsaturated double bonds that may be contained in the second layer 230 are colored by the staining process. Therefore, if the observed sample is colored by staining, it is determined that the second layer 230 contains a monomer. Whether the monomer contained in the second layer 230 is the same as the monomer contained in the curable resin composition for producing the first layer 220 is determined by quantitatively analyzing the chemical bonds using Fourier transform infrared spectroscopy (FT-IR).
  • FT-IR Fourier
  • the optical sheet 210 may include a base layer 240.
  • the first layer 220, the second layer 230, and the base layer 240 may be arranged in this order from the first surface 211 to the second surface 212 in the first direction D1.
  • the first layer 220 includes a first side surface 2221 and a second side surface 222.
  • the first side surface 2221 and the second side surface 222 constitute a pair of main surfaces of the first layer 220.
  • the first side surface 2221 constitutes the first surface 211.
  • the second side surface 222 is in contact with the second layer 230.
  • the thickness T240 of the base layer 240 may be greater than the thickness T220 of the first layer 220.
  • the thickness T240 of the base layer 240 may be greater than the thickness T230 of the second layer 230.
  • the thickness T240 of the base layer 240 may be greater than the total thickness of the thickness T220 of the first layer 220 and the thickness T230 of the second layer 230.
  • a base layer 240 having such a thickness T240 can stably support the first layer 220 and the second layer 230.
  • the thickness T240 of the base layer 240 is measured using a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • the cross section of the optical sheet 210 to be evaluated is observed with a scanning transmission electron microscope, and the thickness T240 is measured from the observation image of the scanning transmission electron microscope.
  • the observation image of the cross section of the optical sheet 210 to be evaluated is obtained by observing a thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is obtained through the first and second steps described above.
  • the thickness T240 of the base layer 240 is determined as the arithmetic mean value of 10 thickness measurement values measured at 10 measurement positions.
  • the second layer 230 may contain at least a part of the same resin component as the resin component contained in the base layer 240.
  • the adhesion between the second layer 230 and the base layer 240 can be improved.
  • the adhesion between the second layer 230 and the base layer 240 can also contribute to improving the hardness of the first layer 220 and the hardness at the first surface 211.
  • the adhesion between the second layer 230 and the base layer 240 is improved, the hardness of the first layer 220 and the hardness at the first surface 211 can be improved. This can increase the pencil hardness at the first surface 211, the load capacity in a steel wool scratch resistance test at the first surface 211, and the indentation hardness HIT at the cross section of the first layer 220.
  • the second layer 230 may include at least a part of the resin component included in the first layer 220 and at least a part of the resin component included in the base layer 240. According to this example, a relationship in which the hardness of the first layer 220 is greater than the hardness of the second layer 230 is stably generated.
  • the indentation hardness H IT measured on the cross section of the first layer 220 can be stably made greater than the indentation hardness H IT measured on the cross section of the second layer 230.
  • the adhesion between the first layer 220 and the second layer 230 can be improved, and the adhesion between the second layer 230 and the base layer 240 can be improved.
  • the adhesion By improving the adhesion, the hardness of the first layer 220 and the hardness at the first surface 211 can be stably improved.
  • the second layer 230 may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the first layer 220. By including an ultraviolet absorbing agent in the second layer 230, the blue light blocking function can be enhanced.
  • the second layer 230 may be a mixed layer of the resin component of the first layer 220 and the resin component of the base layer 240.
  • the second layer 230 as a mixed layer of the resin component of the first layer 220 and the resin component of the base layer 240 can more effectively improve the hardness of the first layer 220 and the hardness at the first surface 211.
  • the second layer 230 as a mixed layer may be a permeation layer in which the curable resin composition for producing the first layer 220 is permeated into the base film 245.
  • the base layer 240 and the second layer 230 may both be composed of the base film 245 to which the curable resin composition for producing the first layer 220 is applied.
  • the part of the base film 245 that is permeated with the curable resin composition may constitute the second layer 230.
  • the part of the base film 245 that is not permeated with the curable resin composition may constitute the base layer 240.
  • the presence of the permeation layer can be confirmed by observing the cross section of the optical sheet along the first direction with a scanning transmission electron microscope (STEM).
  • STEM scanning transmission electron microscope
  • An observation image of the cross section of the optical sheet 210 to be evaluated is obtained by observing the above-mentioned thickness measurement sample with a scanning transmission electron microscope.
  • the thickness measurement sample is stained before observation with the scanning transmission electron microscope. Osmium tetroxide, ruthenium tetroxide, phosphotungstic acid, etc. may be used for staining.
  • the base layer 240 and the base film 245 may contain one or more of an acrylic resin and a cellulose resin.
  • the acrylic resin and the cellulose resin are easily permeated with the curable resin composition. Therefore, the second layer 230, which is a mixed layer of the resin components of the first layer 220 and the resin components of the base layer 240, can be easily produced. According to this example, the hardness of the first layer 220 and the hardness at the first surface 211 can be stably improved.
  • the hardness of the base layer 240 may be greater than the hardness of the second layer 230.
  • the indentation hardness H IT measured on a cross section of the base layer 240 may be greater than the indentation hardness H IT measured on a cross section of the second layer 230.
  • the measurement position of the indentation hardness H IT of the cross section of the base material layer 240 is the center in the thickness direction of the base material layer 240. That is, assuming that the base material layer 240 corresponds to the base material layer 40, the indentation hardness H IT of the cross section of the base material layer 240 is measured at the center position 41 described with reference to FIG. 2A in the first embodiment. The indentation hardness H IT of the cross section of the base material layer 240 is measured by pressing an indenter into this measurement position. The indentation hardness H IT of the cross section of the base material layer 240 is otherwise measured by the same measurement method as the measurement method of the indentation hardness H IT of the cross section of the first layer 220 described above.
  • the a * value of the L * a * b * color system of the optical sheet 210 measured by transmitted light may be -3.0 or more and -1.6 or less.
  • the b * value of the L * a * b * color system of the optical sheet 210 measured by transmitted light may be 3.5 or more and 6.0 or less.
  • the yellowness index (YI value) of the optical sheet 210 may be 12 or less, 11 or less, 10 or less, or 9.0 or less.
  • the yellowness index is an index showing the degree of yellow coloring of the optical sheet 210.
  • the yellowness (YI value) of the optical sheet 210 may be equal to or greater than 0.
  • the yellowness index (YI value) of the optical sheet 210 may be greater than 0 and less than 12, greater than 0 and less than 11, greater than 0 and less than 10, or greater than 0 and less than 9.0.
  • the yellowness index (YI value) of the optical sheet 210 may be greater than 0 and less than 12, greater than 0 and less than 11, greater than 0 and less than 10, or greater than 0 and less than 9.0.
  • the method for measuring the yellowness is the same as that described in the first embodiment.
  • the total light transmittance of the optical sheet 210 may be 50% or more, 70% or more, 80% or more, or 90% or more.
  • the total light transmittance of the optical sheet 210 does not have a particular upper limit.
  • the total light transmittance of the optical sheet 210 may be 100% or less, or may be less than 100%.
  • the total light transmittance of the optical sheet 210 may be 50% or more and 100% or less, 70% or more and 100% or less, 80% or more and 100% or less, or 90% or more and 100% or less.
  • the total light transmittance of the optical sheet 210 may be 50% or more and less than 100%, 70% or more and less than 100%, 80% or more and less than 100%, or 90% or more and less than 100%.
  • the method for measuring the total light transmittance is the same as that described in the first embodiment.
  • the transmission haze of the optical sheet 210 may be 1.1% or less, 0.5% or less, or 0.2% or less.
  • the transmission haze of the optical sheet 210 does not have a particular lower limit.
  • the transmission haze of the optical sheet 210 may be 0% or greater than 0%.
  • the transmission haze of the optical sheet 210 may be 0% or more and 1.1% or less, 0% or more and 0.5% or less, or 0% or more and 0.2% or less.
  • the transmission haze of the optical sheet 210 may be greater than 0% and 1.1% or less, greater than 0% and 0.5% or less, or greater than 0% and 0.2% or less.
  • the method for measuring the transmission haze is the same as that described in the first embodiment.
  • the ratio of silicon element to carbon element measured on the first surface 211 by X-ray photoelectron spectroscopy may be 0.02 or more. In other words, in the quantitative analysis result of elements by X-ray photoelectron spectroscopy, the amount of silicon element may be 0.02 or more when the amount of carbon element is 1.
  • the silicon element is the sum of an inorganic component (silica) and an organic component (silicone).
  • the first layer 220 may contain inorganic particles as a lubricant.
  • By setting the ratio of silicon element to carbon element to 0.02 or more it is possible to suppress the aggregation of inorganic particles added as a lubricant, for example, the aggregation of silica. In other words, by setting the ratio of silicon element to carbon element to 0.02 or more, the lubricant functions effectively.
  • the lubricant can suppress the adjacent optical sheets 210 from sticking to each other when the optical sheets 210 are stacked or rolled up.
  • the curable resin composition for producing the first layer 220 may contain a leveling agent.
  • a Si-based leveling agent as the leveling agent added to the curable resin composition, the ratio of silicon elements to carbon elements can be set to 0.02 or more.
  • the ratio of elemental fluorine measured on the first surface 211 by X-ray photoelectron spectroscopy may be 0.1% or less. In other words, the ratio of the amount of elemental fluorine to the total amount of elements detected by X-ray photoelectron spectroscopy may be 0.001 or less. In this example, substantially no fluorine is detected in the surface layer of the optical sheet 210. By not using an F-based leveling agent as the leveling agent added to the curable resin composition, the ratio of elemental fluorine can be 0.1% or less.
  • X-ray photoelectron spectroscopy allows for quantitative analysis of elements present on the surface layer of the optical sheet 210.
  • an X-ray photoelectron spectroscopy device XPS
  • the measurement method by X-ray photoelectron spectroscopy using an X-ray photoelectron spectroscopy device is the same as the measurement method described in the first embodiment.
  • the base layer 240, the second layer 230, and the first layer 220 are stacked in the first direction D1.
  • the first direction D1 is the stacking direction.
  • the base layer 240, the second layer 230, and the first layer 220 extend in the second direction D2 and the third direction D3 perpendicular to the first direction D1.
  • the second direction D2 and the third direction D3 are perpendicular to each other.
  • the first direction D1 is the thickness direction and normal direction of the optical sheet 210.
  • the first direction D1 is also the thickness direction and normal direction of each layer 240, 230, and 220 included in the optical sheet 210.
  • the first surface 211 is composed of the first layer 220.
  • the second surface 212 is composed of the base layer 240.
  • the first layer 220 and the second layer 230 are adjacent in the first direction D1.
  • the second layer 230 and the base layer 240 are adjacent in the first direction D1.
  • the optical sheet 210 may include layers other than the first layer 220, the second layer 230, and the base layer 240.
  • the optical sheet 210 may include one or more of a low-reflection layer, an antistatic layer, an antifouling layer, etc.
  • a layer other than the first layer 220 may constitute the first surface 211.
  • the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer are thin layers. Therefore, even in the example in which the other layers, such as the low-reflection layer, the antistatic layer, and the antifouling layer, constitute the first surface 211, the hardness of the first surface 211 can be improved by the combination of the first layer 220 and the second layer 230.
  • the base layer 240 supports the first layer 220 and the second layer 230.
  • the base layer 240 may be transparent.
  • transparent means that the total light transmittance in accordance with JIS K7361-1:1997 is 50% or more. This means that the ratio is 70% or more, 80% or more, or 90% or more.
  • the substrate layer 240 may be the same as the substrate layer 40 described in the first embodiment.
  • the substrate layer 240 may be the same as the substrate layer 140 described in the second embodiment.
  • the substrate layer 240 may have the same configuration as the substrate layer 40 described in the first embodiment.
  • the substrate layer 240 may have the same configuration as the substrate layer 140 described in the second embodiment.
  • the material of the substrate layer 240 may be the same as the material of the substrate layer 40 described in the first embodiment.
  • the material of the substrate layer 240 may be the same as the material of the substrate layer 140 described in the second embodiment.
  • the thickness T240 of the substrate layer 240 may be the same as the thickness T40 of the substrate layer 40 described in the first embodiment.
  • the thickness T240 of the substrate layer 240 may be the same as the thickness T140 of the substrate layer 140 described in the second embodiment.
  • the layer configuration of the substrate layer 240 may be the same as the layer configuration of the substrate layer 40 described in the first embodiment.
  • the layer structure of the base material layer 240 may be the same as the layer structure of the base material layer 240 described in the second embodiment.
  • the substrate layer 240 may be prepared as a substrate film 245.
  • This substrate film 245 may include only a single layer or may include multiple layers.
  • the substrate layer 240 may include a primer layer such as an easy-adhesion layer.
  • the surface of the substrate film 245 may be subjected to one or more of sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, etching treatment such as oxidation, and undercoat treatment. These treatments can improve the adhesion between the substrate film 245 and the layer adjacent to the substrate film 245.
  • the surface of the substrate film 245 may be subjected to a cleaning treatment such as solvent cleaning or ultrasonic cleaning.
  • the first layer 220 includes a binder resin 223 and an ultraviolet absorbing agent.
  • the first layer 220 exhibits a blue light blocking function by including the ultraviolet absorbing agent.
  • the binder resin 223 is a curable resin composition.
  • the first layer 220 contains a cured product of the curable resin composition, which contributes to improving the hardness of the first surface 211 and the first layer 220.
  • the first layer 220 may have the same configuration as the functional layer 20 described in the first embodiment.
  • the first layer 220 may have the same configuration as the first layer 120 described in the second embodiment.
  • the material of the first layer 220 may be the same as the material of the functional layer 20 described in the first embodiment.
  • the material of the first layer 220 may be the same as the material of the first layer 120 described in the second embodiment.
  • the layer structure of the first layer 220 may be the same as the layer structure of the functional layer 20 described in the first embodiment.
  • the layer structure of the first layer 220 may be the same as the layer structure of the first layer 120 described in the second embodiment.
  • the curable resin composition may be an ionizing radiation curable resin composition.
  • the ionizing radiation curable resin composition may include one or more of an ultraviolet ray curable resin composition and an electron beam curable resin composition.
  • the ionizing radiation curable resin composition may include an ionizing radiation curable compound and a photopolymerization initiator.
  • the ionizing radiation curable compound may include one or more of an ultraviolet ray curable compound and an electron beam curable compound.
  • the ultraviolet ray curable compound is a resin that is cured by irradiation with ultraviolet rays.
  • the electron beam curable compound is a resin that is cured by irradiation with an electron beam.
  • the cured product of the curable resin composition may be a cured curable compound.
  • the ionizing radiation curable compound may be the same as the ionizing radiation curable compound used in the functional layer 20 described in the first embodiment.
  • the ionizing radiation curable compound may be the same as the ionizing radiation curable compound used in the first layer 120 described in the second embodiment.
  • the photopolymerization initiator is not particularly limited.
  • the photopolymerization initiator may be the same as the photopolymerization initiator used in the functional layer 20 described in the first embodiment.
  • the photopolymerization initiator may be the same as the photopolymerization initiator used in the first layer 120 described in the second embodiment.
  • the ultraviolet absorber may be dispersed in a first direction D1, a second direction D2, and a third direction D3 in the first layer 220.
  • the ultraviolet absorber may be included in a liquid curable resin composition.
  • the ultraviolet absorber included in the curable resin composition may be dispersed in the first layer 220 after a coating film of the curable resin composition is subjected to a drying process and a curing process.
  • the ultraviolet absorber imparts a blue light cut function to the first layer 220 and the optical sheet 210.
  • the characteristics of the blue light cut function can be adjusted by the type and content of the ultraviolet absorber. Therefore, the blue light cut function caused by the ultraviolet absorber can make the spectral transmittance at a wavelength of 440 nm 70% or more, while making the spectral transmittance at a wavelength of 410 nm 15% or less.
  • the a * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the b * value of the L * a * b * color system measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the yellowness YI value measured by transmitted light can be adjusted by the type and content of the ultraviolet absorber.
  • the type and content of the ultraviolet absorber are not particularly limited.
  • the type and content of the ultraviolet absorber can be selected so as to obtain the desired blue light cut function and the desired a * value and b * value.
  • the type and amount of the ultraviolet absorbent may be the same as the type and amount of the ultraviolet absorbent described in the first embodiment.
  • the type and amount of the ultraviolet absorbent may be the same as the type and amount of the ultraviolet absorbent described in the second embodiment.
  • the curable resin composition may contain particles as a lubricant.
  • the curable resin composition may contain the same particles as the particles as the lubricant contained in the curable resin composition for the functional layer described in the first embodiment.
  • the curable resin composition may contain the same particles as the particles as the lubricant contained in the curable resin composition for the first layer described in the second embodiment.
  • the particle diameter of the particles contained in the first layer 220 is determined in the same manner as the particle diameter of the particles contained in the functional layer 20 described in the first embodiment.
  • the curable resin composition may contain a Si-based leveling agent as an additive.
  • the surface of the first layer 220 can be made smoother.
  • the Si-based leveling agent can impart excellent slip properties and excellent anti-fouling properties to the surface of the first layer 220.
  • the curable resin composition may contain other additives.
  • additives include antistatic agents, antioxidants, surfactants, dispersants, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments, dyes), defoamers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, and surface modifiers.
  • the curable resin composition may contain one or more of these additives.
  • the curable resin composition may contain a solvent.
  • the curable resin composition may contain the same solvent as the solvent contained in the curable resin composition for the functional layer described in the first embodiment.
  • the curable resin composition may contain the same solvent as the solvent contained in the curable resin composition for the first layer described in the second embodiment.
  • the content ratio of the raw materials in the curable resin composition i.e., the solid content ratio, is not particularly limited.
  • the content ratio of the raw materials in the curable resin composition may be 5% by mass or more, or 25% by mass or more.
  • the content ratio of the raw materials in the curable resin composition may be 70% by mass or less, or 60% by mass or less.
  • the first layer 220 is made using a liquid curable resin composition containing an ultraviolet absorber.
  • the prepared curable resin composition is applied to a surface on which the first layer 220 is to be made to form a coating film of the curable resin composition.
  • the coating film of the curable resin composition is dried, and the dried coating film is cured to obtain the first layer 220.
  • the preparation method, application method, and curing treatment of the curable resin composition are not particularly limited.
  • the preparation method, application method, and curing treatment of the curable resin composition may be the same as the preparation method, application method, and curing treatment of the curable resin composition for the first layer described in the first embodiment, respectively.
  • the second layer 230 is a layer adjacent to the first layer 220 and the base layer 240. As described above, the second layer 230 is a layer whose thickness T230 is adjusted with respect to the thickness T220 of the first layer 220.
  • the thickness ratio which is the ratio of the thickness T220 of the first layer 220 to the thickness T230 of the second layer 230, is not less than 1.2 and not more than 7.5.
  • the second layer 230 may be a resin layer.
  • the second layer 230 may be a layer that has high adhesion to the base layer 240.
  • the second layer 230 may be a layer that has high adhesion to the first layer 220.
  • the second layer 230 may have a hardness lower than that of the first layer 220.
  • the indentation hardness measured on a cross section of the first layer 220 may be greater than the indentation hardness measured on a cross section of the second layer 230.
  • the presence of such a second layer 230 can improve the hardness of the first layer 220 and the hardness at the first surface 211.
  • the material of the second layer 230 may be selected as follows.
  • the second layer 230 may include a thermoplastic resin.
  • the second layer 230 may include the same resin component as at least a portion of the resin component contained in the first layer 220.
  • the second layer 230 may include one or more of an acrylic resin and a cellulose resin.
  • the second layer 230 may include the same resin component as at least a portion of the resin component contained in the first layer 220.
  • the second layer 230 may include a monomer.
  • the second layer 230 may include at least a portion of the monomer contained in the curable resin composition for producing the first layer 220.
  • the second layer 230 may be a mixed layer of the resin component of the first layer 220 and the resin component of the base layer 240.
  • the second layer 230 By forming the second layer 230 as a mixed layer of the resin component of the first layer 220 and the resin component of the base layer 240, the hardness of the first surface 211 of the optical sheet 210 can be more effectively improved.
  • the second layer 230 as a mixed layer may be a permeation layer in which the curable resin composition for producing the first layer 220 is permeated into the base film 245.
  • the base film 240 and the second layer 230 may both be constituted by the base film 245 to which the curable resin composition for producing the first layer 220 is applied.
  • the second layer 230 may be constituted by a portion of the base film 245 into which the curable resin composition has permeated (permeation layer).
  • the base film 245 may be constituted by a portion of the base film 245 into which the curable resin composition has not permeated.
  • the solvent contained in the curable resin composition easily penetrates the base film 245, so that the second layer 230 can be stably formed as a penetration layer.
  • a base film 245 with high water absorption (liquid absorption) the solvent easily penetrates the base film 245.
  • the solvent easily penetrates cellulose-based resins, particularly triacetylcellulose (TAC).
  • TAC triacetylcellulose
  • the solvent also easily penetrates acrylic resins. Therefore, the base layer 240 and the base film 245 may contain one or more of an acrylic resin and a cellulose resin.
  • the second layer 230 which is a mixed layer of the resin component of the first layer 220 and the resin component of the base layer 240, can be stably produced.
  • the produced second layer 230 contains one or more of an acrylic resin and a cellulose resin.
  • the ease of forming the penetration layer changes depending on the relationship between the curable resin compound and the solvent contained in the curable resin composition and the base film 245.
  • the ease of forming the penetration layer also changes depending on the viscosity of the curable resin compound, the drying conditions of the coating of the curable resin compound, and the curing conditions of the coating of the curable resin compound. Therefore, the thickness T230 of the second layer 230 as a penetration layer can be adjusted depending on the material contained in the curable resin composition, the material of the base film 245, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, and the like.
  • the amount of penetration changes depending on the material contained in the curable resin composition, the material of the base film 245, the preparation conditions of the curable resin composition, the drying conditions of the curable resin composition, the curing conditions of the curable resin composition, and the like, so the thickness T220 of the first layer 220 can also be adjusted. That is, when the second layer 230 is produced as a penetration layer, the thickness ratio can be adjusted.
  • the second layer may contain an ultraviolet absorbing agent that is the same as at least a portion of the ultraviolet absorbing agent contained in the first layer.
  • a method for manufacturing the optical sheet 210 may include a step of producing an intermediate laminate including the base layer 240 and the second layer 230, and a step of producing the first layer 220 on the second layer 230. Details of the first example of the method for manufacturing the optical sheet may be similar to the first example of the method for manufacturing the optical sheet described in the second embodiment.
  • the manufacturing method of the optical sheet 210 may include a step of producing an intermediate laminate including the second layer 230 and the first layer 220, and a step of laminating the intermediate laminate including the second layer 230 and the first layer 220 and the base layer 240. Details of the second example of the manufacturing method of the optical sheet may be similar to the second example of the manufacturing method of the optical sheet described in the second embodiment.
  • the manufacturing method of the optical sheet 210 may include a step of producing the first layer 220 on the base film 245 by a wet method.
  • This manufacturing method may include a step of applying a curable resin composition onto the base film 245 and a step of curing the coating of the curable resin composition.
  • the manufacturing method may further include a step of drying the coating of the curable resin composition before the step of curing the coating.
  • the first layer 220 may be constituted by the coating of the cured curable resin composition.
  • the second layer 230 may be constituted by a portion of the base film 245 into which the curable resin composition has permeated (i.e., a permeation layer).
  • the base layer 240 may be constituted by a portion of the base film into which the curable resin composition has not permeated.
  • the details of the third example of the manufacturing method of the optical sheet may be the same as the third example of the manufacturing method of the optical sheet described in the second embodiment. According to the third example of the manufacturing method of the optical sheet, the same action and effect as the third example of the manufacturing method of the optical sheet described in the second embodiment can be achieved.
  • the manufacturing method of the optical sheet 210 may include the following four steps.
  • Details of the fourth example of the method for manufacturing an optical sheet may be similar to those of the fourth example of the method for manufacturing an optical sheet described in the second embodiment. According to the fourth example of the method for manufacturing an optical sheet, it is possible to achieve the same effects as those of the fourth example of the method for manufacturing an optical sheet described in the second embodiment.
  • the manufacturing method according to the fourth example allows for a higher degree of freedom in adjusting the spectral transmittance characteristics of the optical sheet 210.
  • (3A) The spectral transmittance of the optical sheet 210 at a wavelength of 380 nm is less than 1%.
  • (3B) The spectral transmittance of the optical sheet 210 at a wavelength of 440 nm is 70% or more.
  • the slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less.
  • a long sheet article 5 including a number of optical sheets 210 can be manufactured.
  • the long sheet article 5 is cut to a predetermined size to obtain the optical sheet 210.
  • optical sheets 210 having various dimensions can be obtained from the long sheet article 5 in accordance with needs. Therefore, optical sheets 210 having various dimensions can be provided in a timely manner.
  • the handleability of the sheet article 5 can be improved.
  • the manufacturing method of the optical sheet may further include a step of selecting the manufactured optical sheet 210 in addition to the step of manufacturing the optical sheet described above.
  • the step of selecting the optical sheet 210 may include a step of measuring the thickness ratio and a step of measuring the spectral transmittance at each wavelength at intervals of 0.5 nm within a wavelength range of 379.5 nm to 440.5 nm.
  • the thickness ratio is the ratio of the thickness T220 ( ⁇ m) of the first layer 220 to the thickness T230 ( ⁇ m) of the second layer 230.
  • the step of selecting the optical sheet 210 may further include a step of selecting the optical sheet based on the thickness ratio, the spectral transmittance at a wavelength of 380 nm, the spectral transmittance at a wavelength of 440 nm, and the slope of the spectral transmittance at wavelengths at intervals of 0.5 nm within a wavelength range of 380 nm to 440 nm.
  • a thickness ratio of 1.2 or more and 7.5 or less may be acceptable.
  • a spectral transmittance of less than 1% at a wavelength of 380 nm may be acceptable.
  • a spectral transmittance of 70% or more at a wavelength of 440 nm may be acceptable.
  • the slope (%/nm) of the spectral transmittance at wavelength X is calculated by subtracting the spectral transmittance (%) at wavelength X-0.5 (nm) from the spectral transmittance (%) at wavelength X+0.5 (nm).
  • the slope of the spectral transmittance at each wavelength at intervals of 0.5 nm within the range of 380 nm to 440 nm may be acceptable if the maximum value is within the range of 400 nm to 420 nm.
  • the optical sheet 210 that passes all of the thickness ratio, the spectral transmittance at a wavelength of 380 nm, the spectral transmittance at a wavelength of 440 nm, and the maximum value of the slope of the spectral transmittance may be selected as a good product.
  • the optical sheet 210 selected as a good product has an excellent blue light blocking function and has high hardness on the first surface 211. According to this selection step, an optical sheet having excellent scratch resistance can be selected with high precision without performing a scratch test using felt or steel wool.
  • the optical sheet 210 may be applied to one or more of the polarizing plate 50, the touch panel member 55, and the display device 60.
  • the first curable resin composition 3A was applied onto a substrate film made of triacetyl cellulose having a thickness of 80 ⁇ m, and a first coating film was formed on the substrate film.
  • the method for producing the first curable resin composition 3A will be described later.
  • the first coating film was dried under the condition of 40° C. ⁇ 20 seconds (drying air speed 0.4 m/s). After that, the first coating film was dried under the condition of 40° C. ⁇ 20 seconds (drying air speed 0.5 m/s). The above caused the solvent to volatilize.
  • the first coating film was irradiated with ultraviolet light at an integrated light amount of 66 mJ/cm 2.
  • the first coating film was cured by irradiation with ultraviolet light, and the first portion of the first layer was formed on the substrate film.
  • the amount of application of the first curable resin composition 3A was set to an amount that would produce a first portion with a dry thickness of 4.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • the second curable resin composition 3A having the following formulation was applied onto the first portion to form a second coating film on the substrate film.
  • the solid content of the second curable resin composition 3A was 47%.
  • the second curable resin composition 3A did not contain an ultraviolet absorber.
  • the second coating film was dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s).
  • the second coating film was dried under the conditions of 70°C x 20 seconds (drying air speed 0.3 m/s). The above caused the solvent to volatilize.
  • the second coating film was irradiated with ultraviolet light at an integrated light quantity of 288 mJ/ cm2 .
  • the second coating film was cured by irradiation with ultraviolet light, and the second portion of the first layer was prepared on the substrate film and the first portion.
  • the amount of application of the second curable resin composition 3A was set to an amount that would produce a second portion with a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate layer or the first portion.
  • the optical sheet of Example 31 was obtained.
  • the first layer was composed of the first portion and the second portion.
  • the cross section of the optical sheet of Example 31 was observed during the thickness measurement described below.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used to observe the cross section.
  • the cross section was observed at an acceleration voltage of 10 kV to 30 kV and a magnification of 5000 times, it was found that the curable resin composition had permeated the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer. Furthermore, the interface between the first and second parts in the first layer could not be observed.
  • the contents in the four-neck flask were refluxed and dehydrated at 110-115°C for 4 hours.
  • 30 mL of water and 0.6 g (0.006 mol) of sodium carbonate were added to the four-neck flask.
  • the four-neck flask was then left to stand, and the lower aqueous layer was separated and removed.
  • 0.2 g of activated carbon was added to the four-neck flask, and the contents were refluxed and stirred to decolorize.
  • the contents removed from the four-neck flask were then filtered. 40 mL of toluene was collected from the obtained filtrate under reduced pressure.
  • An intermediate composition was prepared by mixing the following: - Multifunctional monomer (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded (a polymer in which a sesamol-type benzotriazole monomer is reactively bonded to MMA and an ultraviolet absorber at a mass ratio X of 40 parts by mass) Solvent (a mixture of MEK and toluene in a mass ratio of 30:70) The polyfunctional monomer and the acrylic polymer (1) were mixed in a solid content mass ratio of 40:60.
  • - Multifunctional monomer PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.)
  • Acrylic polymer (1) to which a sesamol-type benzotriazole monomer is reactively bonded a polymer in which a sesamol-type benzotriazole monomer is reactive
  • the obtained intermediate composition was mixed with a photopolymerization initiator (4 parts by mass of Irgacure 819, manufactured by BASF) and a leveling agent (0.2 parts by mass of LE-304, manufactured by Kyoeisha) and thoroughly stirred to prepare a first curable resin composition 3A.
  • the obtained first curable resin composition 3A contained a solid content of 27.5%.
  • UV-curable acrylate-containing composition 50 parts by mass (PET-30 (pentaerythritol triacrylate), manufactured by Nippon Kayaku Co., Ltd.) 50 parts by mass of ultraviolet-curable urethane acrylate-containing composition (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 577")
  • Leveling agent 0.4 parts by mass (Kyoeisha, product name "LE-304”)
  • Photopolymerization initiator 4 parts by mass IGM Resins, trade name "Omnirad184”
  • Lubricant 20 parts by mass (CIK Nanotech, SIRMIBK15WT%-E65)
  • Solvent a mixture of methyl isobutyl ketone and methyl ethyl ketone in a mass ratio of 55:48)
  • Example 32 differs from the above-mentioned Example 31 in that the amount of the first curable resin composition 3A applied was reduced, but otherwise the optical sheet of Example 32 was obtained using the same materials and method as Example 31.
  • the amount of the first curable resin composition 3A applied was set to an amount that would produce a first portion with a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the base film.
  • Example 32 When measuring the thickness as described below, the cross section of the optical sheet of Example 32 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 33 differs from the above-mentioned Example 31 in that the coating amount of the first curable resin composition 3A was increased, but otherwise the optical sheet of Example 33 was obtained using the same materials and by the same method as in Example 31.
  • the coating amount of the first curable resin composition 3A was set to an amount that would produce a first portion with a dry thickness of 4.9 ⁇ m, assuming that there was no penetration into the base film.
  • Example 33 When measuring the thickness as described below, the cross section of the optical sheet of Example 33 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 34 differs from Example 31 in that the drying conditions of the first coating film were changed and the amount of the second curable resin composition 3A applied was increased, but the optical sheet of Example 34 was obtained using the same materials and methods as Example 31.
  • the first coating film was first dried under the conditions of 60°C x 20 seconds (drying air speed 0.4 m/s), and then dried under the conditions of 60°C x 20 seconds (drying air speed 0.5 m/s).
  • the amount of the second curable resin composition 3A applied was set to an amount that would produce a second portion with a dry thickness of 5.5 ⁇ m, assuming that there was no penetration into the base film or the first portion.
  • Example 34 When measuring the thickness as described below, the cross section of the optical sheet of Example 34 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 35 differs from Example 31 in that the solid content ratio of the first curable resin composition and the solid content ratio of the second curable resin composition were changed, and the optical sheet of Example 35 was obtained by the same materials and the same method as Example 31.
  • a first curable resin composition having a solid content of 20% was used.
  • the first curable resin composition used in Example 35 was obtained by adjusting the amount of solvent contained in the first curable resin composition 3A.
  • a second curable resin composition having a solid content of 40% was used.
  • the second curable resin composition used in Example 35 was obtained by adjusting the amount of solvent contained in the second curable resin composition 3A.
  • Example 35 When measuring the thickness as described below, the cross section of the optical sheet of Example 35 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 36 differs from Example 31 in that the amount of the first curable resin composition 3A applied was reduced and the amount of the second curable resin composition 3A applied was reduced.
  • the optical sheet of Example 36 was obtained using the same materials and methods as Example 31.
  • the amount of the first curable resin composition 3A applied was set to an amount that would produce a first portion with a dry thickness of 1.5 ⁇ m, assuming that there was no penetration into the base film.
  • the amount of the second curable resin composition 3A applied was set to an amount that would produce a second portion with a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the base film or the first portion.
  • Example 36 When measuring the thickness as described below, the cross section of the optical sheet of Example 36 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 37 differs from the above-mentioned Example 36 in that the amount of the second curable resin composition 3A applied was reduced, but the optical sheet of Example 37 was otherwise obtained using the same materials and method as in Example 36.
  • the amount of the second curable resin composition 3A applied was set to an amount that would produce a second portion with a dry thickness of 3.2 ⁇ m, assuming that there was no penetration into the base film or the first portion.
  • Example 37 When measuring the thickness as described below, the cross section of the optical sheet of Example 37 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Example 38 differs from Example 31 in that the leveling agent of the first curable resin composition 3A was omitted and that the leveling agent of the second curable resin composition 3A was changed, and the optical sheet of Example 38 was obtained by the same materials and the same method as Example 31 in other respects.
  • the first curable resin composition used to form the first coating film differs from the first curable resin composition 3A described above in that the leveling agent "Kyoeisha, LE-304, 0.2 parts by mass" was omitted, and the other respects were the same as the first curable resin composition 3A described above.
  • Example 38 the second curable resin composition used to form the second coating film differed from the second curable resin composition 3A described above in that the leveling agent "DIC, F-477, 0.3 parts by mass” was used instead of the leveling agent "Kyoeisha, LE-304, 0.4 parts by mass”.
  • the second curable resin composition used to form the second coating film was the same as the above-mentioned second curable resin composition 3A, except for the leveling agent.
  • Example 38 When measuring the thickness as described below, the cross section of the optical sheet of Example 38 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 31 differs from Example 31 in that the substrate film was changed, the amount of the first curable resin composition 3A applied was increased and the amount of the second curable resin composition 3A applied was decreased, and the cumulative amount of ultraviolet light irradiated during the curing of the second coating film was decreased.
  • the optical sheet of Comparative Example 31 was obtained by the same materials and the same method as Example 31 in other respects.
  • a substrate film made of triacetyl cellulose having a thickness of 40 ⁇ m was used.
  • the content ratio of the plasticizer in the substrate film of Comparative Example 31 was higher than the content ratio of the plasticizer in the substrate film of Example 31.
  • the coating amount of the first curable resin composition 3A was set to an amount that would produce a first portion with a dry thickness of 5.0 ⁇ m, assuming that there was no penetration into the substrate film.
  • the coating amount of the second curable resin composition 3A was set to an amount that would produce a second portion with a dry thickness of 3.5 ⁇ m, assuming that there was no penetration into the substrate film and the first portion.
  • the cumulative amount of ultraviolet light irradiated during the curing of the second coating film was set to 132 mJ/cm 2 .
  • the cross section of the optical sheet according to Comparative Example 31 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 32 differs from Example 31 above in that the composition of the first curable resin composition was changed, the amount of the first curable resin composition applied was changed, and the amount of the second curable resin composition 3A applied was changed.
  • the optical sheet of Comparative Example 32 was obtained by using the same materials and the same method as in Example 31.
  • the first curable resin composition 3A used in Example 31 contained a polyfunctional monomer and an acrylic polymer (1) mixed in a solid content mass ratio of 20:80.
  • the first curable resin composition used in Comparative Example 32 was obtained by mixing a polyfunctional monomer and a triazine-based ultraviolet absorber mixed in a mass ratio of 95:5 instead of the polyfunctional monomer and acrylic polymer (1) of the first curable resin composition 3A.
  • the polyfunctional monomer contained in the first curable resin composition used in Comparative Example 32 was the same as the polyfunctional monomer contained in the first curable resin composition 3A.
  • the solid content of the first curable resin composition used in Comparative Example 32 was 27.5%, which was the same as the solid content of the first curable resin composition 3A.
  • the triazine-based ultraviolet absorber contained in the first curable resin composition used in Comparative Example 32 was Tinuvin 479, a product name manufactured by BASF.
  • the amount of the first curable resin composition applied was set to an amount that would create a first portion with a dry thickness of 5.0 ⁇ m, assuming that there would be no penetration into the base film.
  • the amount of the second curable resin composition 3A applied was set to an amount that would create a second portion with a dry thickness of 8.0 ⁇ m, assuming that there would be no penetration into the base film or the first portion.
  • the cross section of the optical sheet according to Comparative Example 32 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Comparative Example 33 differs from Example 31 in that the base film was changed, the amount of the first curable resin composition 3A was increased, the amount of the second curable resin composition 3A was reduced, and the cumulative amount of ultraviolet light irradiated during curing of the second coating film was reduced.
  • the optical sheet of Comparative Example 33 was obtained using the same materials and methods as in Example 31.
  • the same base film as the base film used in Comparative Example 31 was used.
  • the amount of the first curable resin composition 3A applied was an amount that would produce a first portion with a dry thickness of 7.0 ⁇ m, assuming that there was no penetration into the base film.
  • the amount of the second curable resin composition 3A applied was an amount that would produce a second portion with a dry thickness of 4.0 ⁇ m, assuming that there was no penetration into the base film and the first portion.
  • the cumulative amount of ultraviolet light irradiated during curing of the second coating film was 132 mJ/cm 2 .
  • the cross section of the optical sheet according to Comparative Example 33 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • the amount of the first curable resin composition 3A applied was set to an amount that would produce a first portion having a dry thickness of 6.5 ⁇ m, assuming that there was no penetration into the substrate film.
  • an optical sheet according to Comparative Example 34 was obtained. That is, in the optical sheet according to Comparative Example 34, the first layer was composed only of the first portion prepared using the first curable resin composition 3A.
  • the thickness of the layer produced using the first curable resin composition 3A in Comparative Example 34 was different from the thickness of the layer produced using the first curable resin composition 3A in Example 31.
  • the method and conditions for producing the first layer using the first curable resin composition 3A in Comparative Example 34 were the same as the method and conditions for producing the first part using the first curable resin composition 3A in Example 31.
  • Example 34 When measuring the thickness as described below, the cross section of the optical sheet according to Comparative Example 34 was observed in the same manner as in Example 31.
  • the first curable resin composition 3A penetrated the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • Comparative Example 35 differs from the above-mentioned Comparative Example 31 in that the leveling agent of the first curable resin composition 3A and the leveling agent of the second curable resin composition 3A were changed, and otherwise the optical sheet of Comparative Example 35 was obtained using the same materials and in the same manner as Comparative Example 31.
  • the first curable resin composition used to form the first coating film differed from the first curable resin composition 3A described above in that the leveling agent "0.2 parts by mass of F-568 manufactured by DIC” was used instead of the leveling agent "0.2 parts by mass of LE-304 manufactured by Kyoeisha.”
  • the first curable resin composition used to form the first coating film was the same as the first curable resin composition 3A described above, except for the leveling agent.
  • the second curable resin composition used to form the second coating film differed from the above-mentioned second curable resin composition 2A in that the leveling agent "DIC, F-477, 0.4 parts by mass” was used instead of the leveling agent "Kyoeisha, LE-304, 0.4 parts by mass.”
  • the second curable resin composition used to form the second coating film was the same as the above-mentioned second curable resin composition 3A, except for the leveling agent.
  • the cross section of the optical sheet according to Comparative Example 35 was observed in the same manner as in Example 31.
  • the curable resin composition penetrated into the substrate film, causing the substrate film to swell, forming a permeation layer that constitutes the second layer.
  • the interface between the first and second parts in the first layer could not be observed.
  • Thickness and thickness ratio>> A sample for thickness measurement was prepared by the following first and second steps.
  • the embedded sample was prepared using the following procedure. First, the cut sample was placed in a silicon embedding plate. Embedding resin was poured into the silicon embedding plate with the cut sample placed in it. Next, the embedding resin was allowed to harden within the silicon embedding plate. Next, the cut sample and the embedding resin surrounding it were removed from the silicon embedding plate to obtain an embedded sample. The embedded sample was shaped like a block.
  • the silicon embedding plate used was manufactured by Dosaka EM.
  • the embedding resin was epoxy resin.
  • the embedding resin was obtained by mixing Struers' product name "Epofix” and the same company's product name "Epofix Hardener” in a ratio of 10:1.2.
  • the embedding resin was allowed to harden by leaving it at room temperature for 12 hours.
  • the block-shaped embedded sample was cut with a diamond knife to prepare a slice sample.
  • the slice sample was aligned along the first direction (thickness direction, lamination direction) of the target optical sheet.
  • slice samples without defects such as holes and with a uniform thickness of about 60 nm to 100 nm were used as thickness measurement samples.
  • microtome was used to cut the embedded samples.
  • the microtome was an Ultramicrotome EM UC7 manufactured by Leica Microsystems. When cutting the block-shaped embedded sample, it was first roughly cut as coarse trimming, and finally, precisely trimmed with a diamond knife to obtain a section sample.
  • the thickness of each layer was measured using the observation image of the thickness measurement sample by a scanning transmission electron microscope.
  • the thickness measurement sample was stained. Osmium tetroxide was used for staining.
  • the stained thickness measurement sample was imaged using a scanning transmission electron microscope to obtain an observation image of the thickness measurement sample.
  • the scanning transmission electron microscope used was an S4800 manufactured by Hitachi High-Tech Corporation.
  • the imaging conditions were as follows. ⁇ Imaging conditions> Mode: Transmission mode TE, bright field Acceleration voltage: 10 kV to 30 kV Emission current: 10 ⁇ A WD (Working Distance): 8.8 ⁇ 0.1mm Magnification: 5000x
  • Ten observation images were obtained from one thickness measurement sample for each example.
  • the ten observation images were obtained at ten observation positions (measurement positions) spaced at 10 ⁇ m intervals in a direction perpendicular to the first direction of the optical sheet in question.
  • the thickness T220 ( ⁇ m) of the first layer and the thickness T230 ( ⁇ m) of the second layer for the optical sheet in each example were measured.
  • the thickness ratio (T220/T230) was calculated based on the thickness T220 ( ⁇ m) of the first layer and the thickness T230 ( ⁇ m) of the second layer measured from each observation image.
  • the calculated average of the 10 measured values for thickness T220 ( ⁇ m) measured from the observation images at 10 points was taken as the thickness T220 ( ⁇ m) of the first layer.
  • the calculated average of the 10 measured values for thickness T230 ( ⁇ m) measured from the observation images at 10 points was taken as the thickness T230 ( ⁇ m) of the second layer.
  • the calculated average of the 10 values for the thickness ratio (T220/T230) measured from the observation images at 10 points was taken as the thickness ratio (T220/T230) of the optical sheet.
  • the measurement results of the thickness ( ⁇ m) of the first layer, the thickness ( ⁇ m) of the second layer, and the thickness ratio (T220/T230) are shown in Table 4.
  • Table 4 examples where the thickness ratio is 1.2 or more and 7.5 or less are marked "OK", and other examples are marked "NG”.
  • Spectral transmittance >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The spectral transmittance (%) was measured. The spectral transmittance (%) was measured for each wavelength in the range of 379.5 nm to 440.5 nm at intervals of 0.5 nm. The measurement was performed using an ultraviolet-visible spectrophotometer "UV-2600" manufactured by Nippon Bunko Co., Ltd. Using the measured value of the spectral transmittance, each wavelength in the range of 380 nm to 440 nm at intervals of 0.5 nm was measured.
  • UV-2600 ultraviolet-visible spectrophotometer
  • the slope of the spectral transmittance at wavelength was calculated.
  • the slope of the spectral transmittance at wavelength X was calculated by subtracting the spectral transmittance (%) at wavelength X+0.5 (nm) from the spectral transmittance (%) at wavelength X-0.5 (nm).
  • the measurement results of the spectral transmittance at 380.0 nm and the spectral transmittance at 440.0 nm are shown in Table 4.
  • the wavelength at which the maximum value of the slope of the spectral transmittance is obtained is shown in Table 4.
  • examples in which all of the following conditions (3A), (3B), and (3C) were satisfied are indicated as "OK", and other examples are indicated as "NG”.
  • (3A) The spectral transmittance of the optical sheet 210 at a wavelength of 380 nm is less than 1%.
  • (3B) The spectral transmittance of the optical sheet 210 at a wavelength of 440 nm is 70% or more.
  • the slope of the spectral transmittance at each wavelength at 0.5 nm intervals within the wavelength range of 380 nm or more and 440 nm or less has a maximum value within the wavelength range of 400 nm or more and 420 nm or less.
  • optical sheets according to Examples 31 to 38 and Comparative Examples 31 to 35 were placed on the display surface of a commercially available organic EL display device, and the image displayed by the organic EL display device was observed through the optical sheet.
  • Examples 31 to 38, Comparative Example 31, Comparative Example 34, and Comparative Example 35 no change in color was perceptible between the image when the optical sheet was installed and the image when the optical sheet was not installed.
  • Comparative Examples 32 and 33 a change in the color of the image was confirmed when the optical sheet was installed.
  • Pencil hardness >> Samples of 50 mm x 100 mm were cut out from the optical sheets according to the examples and comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The pencil hardness was measured using a pencil hardness tester manufactured by Toyo Seiki Seisakusho Co., Ltd. The pencil hardness evaluated according to the above-mentioned evaluation criteria is shown in Table 4.
  • the sample was placed on the base plate so that the second surface of the optical sheet was in contact with the base plate.
  • the height of the four corners of the sample from the base plate was measured as the float (mm).
  • the maximum of the four float measurements taken for one sample was taken as the float for that sample.
  • the float was measured for each of the three samples.
  • the arithmetic mean of the three float measurements was taken as the deformation amount for that example.
  • the deformation amount measurement results are shown in Table 4.
  • Comparative Example 32 the sample placed on the platen curled into a cylindrical shape, and the amount of deformation could not be measured.
  • Measurement conditions Measurement method: Wide/Narrow X-ray source: Monochrome A1K ⁇ X-ray output: 150W Emission current: 10mA Acceleration voltage: 15 kV Charge neutralization mechanism: ON Measurement area: 300 ⁇ m x 700 ⁇ m Pass Energy: Survey: 160eV, Narrow: 40eV Photoelectron capture angle: 90° Auto Z: ON Peak shift correction: Correction was made so that the C-C peak in the C1s peak was 285.0 eV. Waveform separation of narrow peaks: Executed using the GL function in the analysis software attached to the device. Etching ions: Ar monoatomic ions
  • Table 4 shows the percentage (%) of the amount of each element detected, with the total amount of elements detected being 100.
  • Example 31 the ratio of silicon element to carbon element was 0.02 (2%) or more.
  • the cross section of the first layer of Example 31 was observed.
  • a scanning transmission electron microscope S4800 manufactured by Hitachi High-Tech Corporation was used for the cross section observation. When the cross section was observed at an acceleration voltage of 10 kV to 30 kV and a magnification of 5000 times, the silica added as a lubricant was dispersed without being unevenly distributed in aggregate.
  • the epoxy resin used for embedding was obtained by mixing Struers' product name "Epofix” with the same company's product name “Epofix Hardener” in a ratio of 10:1.2.
  • a microtome was used to cut the embedded samples.
  • the microtome was Leica Microsystems' product name "Ultramicrotome EM UC7.”
  • the indentation hardness H IT (MPa) at the cross section of the first layer, the indentation hardness H IT (MPa) at the cross section of the second layer, and the indentation hardness H IT (MPa) at the cross section of the base layer were measured by the above-mentioned method.
  • the indentation hardness H IT at the cross section of each layer was measured using a measuring device "TI-950 TriboIndenter” manufactured by BRUKER.
  • the indenter used to measure the indentation hardness H IT at the cross section of each layer was "TI-0039" manufactured by BRUKER.
  • the measurement results of the indentation hardness H IT (MPa) at the cross section of each layer are shown in Table 4.
  • the indentation hardness at the cross section of each layer was the arithmetic average value of the indentation hardness measured at 10 measurement positions.
  • the ten measurement positions were located at ten positions on one slice sample, spaced apart at a pitch of 5 ⁇ m in a direction perpendicular to the first direction of the optical sheet.
  • Total light transmittance >> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and the comparative examples. The samples were visually inspected to ensure that there were no defects such as dust or scratches. The total light transmittance was measured. A haze meter "HM-150" manufactured by Murakami Color Research Laboratory was used to measure the total light transmittance. The measurement results of the total light transmittance are shown in Table 4.
  • Yellowness index YI value>> Samples of 5 cm x 10 cm were cut out from the optical sheets according to the examples and comparative examples. The samples were visually confirmed to be free of any abnormalities such as dust or scratches. The yellowness index YI value of the optical sheets according to each example was measured by the method described above. The yellowness index YI value was measured using an ultraviolet-visible spectrophotometer "UV-2600" manufactured by Shimadzu Corporation. The measurement results of the yellowness index YI value are shown in Table 4.
  • D1 first direction, D2: second direction, D3: third direction, RA: winding axis, 5: sheet item, 6: winding core, 7: roll, 10: optical sheet, 11: first surface, 12: second surface, 20: functional layer, 20A: first part, 20B: second part, 21: first side, 22: second side, 23: binder resin, 26: first position, 27: second position, 28: third position, 30: intermediate layer, 40: substrate layer, 45: substrate film, 50: polarizing plate, 51: first protective sheet, 52: polarizer, 53: second protective sheet, 55: touch panel member, 56: electrode layer, 60: display device , 61: display element, 61a: display surface, 110: optical sheet, 111: first surface, 112: second surface, 120: first layer, 120A: first part, 120B: second part, 121: first side, 122: second side, 123: binder resin, 130: second layer, 140: base layer, 145: base film, 210: optical sheet, 211: first surface

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Medicinal Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Laminated Bodies (AREA)
  • Polarising Elements (AREA)

Abstract

L'invention concerne une feuille optique comprenant une première surface et une seconde surface faisant face à la première surface. La feuille optique comprend une couche de matériau de base et une couche fonctionnelle dans l'ordre de la seconde surface à la première surface. La couche fonctionnelle comprend un produit durci d'une composition de résine durcissable, et un absorbeur d'ultraviolets. La transmittance spectrale à une longueur d'onde de 380 nm est inférieure ou égale à 1%. La transmittance spectrale à une longueur d'onde de 440 nm est de 70% ou plus. Une dureté d'indentation HA1 à une première position dans une section transversale de la couche fonctionnelle, une dureté d'indentation HA2 à une deuxième position dans la section transversale de la couche fonctionnelle, et une dureté d'indentation HA3 à une troisième position dans la section transversale de la couche fonctionnelle satisfont aux relations suivantes. La première position est située dans une partie de couche de surface proche de la première surface dans la section transversale. La troisième position est située dans une partie de couche de surface proche de la seconde surface dans la section transversale. La deuxième position est située à mi-chemin entre la première position et la deuxième position. HA3 < HA2 < HA1 HA1/HA2 ≤ HA2/HA3
PCT/JP2024/021192 2023-06-12 2024-06-11 Feuille optique, article en feuille, plaque de polarisation, élément de panneau tactile, dispositif d'affichage, procédé de sélection de feuille optique et procédé de fabrication de feuille optique Ceased WO2024257762A1 (fr)

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JP2025527939A JPWO2024257762A1 (fr) 2023-06-12 2024-06-11
CN202480037265.0A CN121241283A (zh) 2023-06-12 2024-06-11 光学片、片物品、偏振片、触控面板构件、显示装置、光学片的选定方法以及光学片的制造方法
KR1020257041433A KR20260022316A (ko) 2023-06-12 2024-06-11 광학 시트, 시트 물품, 편광판, 터치 패널 부재, 표시 장치, 광학 시트의 선정 방법, 및 광학 시트의 제조 방법

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2026058692A1 (fr) * 2024-09-11 2026-03-19 大日本印刷株式会社 Feuille antireflet, article en feuille, plaque de polarisation, dispositif d'affichage, et panneau

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003131007A (ja) * 2001-10-29 2003-05-08 Toppan Printing Co Ltd 光学フィルム及びその製造方法
WO2011040541A1 (fr) * 2009-09-30 2011-04-07 大日本印刷株式会社 Stratifié optique et procédé de production d'un stratifié optique
JP2019073013A (ja) * 2017-10-16 2019-05-16 大日本印刷株式会社 ポリイミドフィルム、ポリイミドフィルムの製造方法、積層体、ディスプレイ用表面材、タッチパネル部材、液晶表示装置、及び有機エレクトロルミネッセンス表示装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003131007A (ja) * 2001-10-29 2003-05-08 Toppan Printing Co Ltd 光学フィルム及びその製造方法
WO2011040541A1 (fr) * 2009-09-30 2011-04-07 大日本印刷株式会社 Stratifié optique et procédé de production d'un stratifié optique
JP2019073013A (ja) * 2017-10-16 2019-05-16 大日本印刷株式会社 ポリイミドフィルム、ポリイミドフィルムの製造方法、積層体、ディスプレイ用表面材、タッチパネル部材、液晶表示装置、及び有機エレクトロルミネッセンス表示装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2026058692A1 (fr) * 2024-09-11 2026-03-19 大日本印刷株式会社 Feuille antireflet, article en feuille, plaque de polarisation, dispositif d'affichage, et panneau

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TW202506421A (zh) 2025-02-16

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