JPH11337704A - Anti-reflective substrate and article using the same - Google Patents

Abstract

(57) [Problem] To provide an antireflection base material in which the contrast and color of an image on a display body are not impaired by dust or the like adhering to the surface. An anti-reflective substrate comprising a transparent substrate, and an antistatic layer and a low refractive index layer composed of an amorphous fluoropolymer in order from the transparent substrate surface side. An antireflective substrate having a refractive index equal to or less than the refractive index of the transparent substrate and the refractive index of the low refractive index layer being lower than the refractive index of the transparent substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antireflective substrate having an antistatic layer and a low refractive index layer on a substrate such as a polyester film and an article using the same.

[0002]

2. Description of the Related Art In recent years, with the rapid development of the information society, portable electric products such as personal computers, televisions, video players, video recorders, and large-sized displays such as liquid crystal, CRT, and plasma have become widespread. The scenes where these are used outdoors and in brightly lit spaces are increasing.

On the other hand, an optical article using a material such as glass or resin located on the frontmost surface of the display is desirably antireflective in order to reduce unnecessary reflectance of light rays and improve transmittance. .

Also, the surface of the optical article is easily charged because it is an insulating material, dust and dirt adhere to the air, and if left as it is, it accumulates. There is a problem of impairing colors. Therefore, it is desirable that the surface of the optical article is subjected to antistatic processing.

In order to solve the above-mentioned problem, a technique of coating a thin film of a conductive metal oxide on the surface of a transparent substrate has conventionally been used. Further, it is known that a technique of forming an antireflection film by coating a thin film having a lower refractive index than the metal oxide on the surface of the thin film of the metal oxide is also known.

Magnesium fluoride (refractive index: 1.3) is used as a material for a thin film having a lower refractive index than a metal oxide.
8), silica (refractive index: 1.44) and the like, which are expected even when coated on the above-mentioned metal oxide thin film, because the refractive index difference between the metal oxide film and the low refractive index film is not sufficient. Anti-reflection performance cannot be obtained. In order to obtain a predetermined antireflection performance, it is necessary to form a multilayer film structure of about five layers, the control of the film thickness becomes complicated, the number of steps is increased, and the yield is low, and the cost is high. Not suitable for mass production.

On the other hand, in the case of a large display or the like, unevenness in the film thickness of the antistatic layer is unavoidable, but this causes a problem that color unevenness of the reflected color occurs.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a transparent substrate, an antistatic layer and an amorphous fluorine-containing polymer in order from the transparent substrate surface side. An antireflective substrate having a low-refractive-index layer made of a coalesced material, wherein the refractive index of the antistatic layer is equal to or less than the refractive index of the transparent substrate, and the refractive index of the low-refractive-index layer is greater than the refractive index of the transparent substrate. It is an antireflective substrate characterized by being low.

The transparent substrate in the present invention is not particularly limited as long as its refractive index is higher than the refractive index of the antistatic layer, and is employed from a wide range. For example, polyester resin, polycarbonate resin, polyarylate resin,
Plates, sheets, films and the like made of polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyetherimide resin, and the like can be given.

Particularly, a polyester resin film is a preferable base material having a refractive index of about 1.6, excellent chemical resistance, low water absorption, and low cost. As the polyester resin film, those commercially available as Cosmoshine (trade name, manufactured by Toyobo) series, Diafoil (trade name, manufactured by Mitsubishi Plastics) series, Lumirror (trade name, manufactured by Toray) series and the like can be used.

Further, a transparent base material which has been subjected to anti-glare processing and prism processing, and a substrate provided with various functions such as a polarizing function, a light diffusing function and a phase difference function can be used.

In the present invention, the refractive index of the antistatic layer is lower than that of the transparent substrate. N ₁ the refractive index of the transparent substrate, if indicated a refractive index of the antistatic layer and the n _2, the relationship of n ₁ and n ₂ are able to satisfy the following equation (1) to (3) simultaneously, a transparent base This is preferable because light interference hardly occurs at the interface between the material and the antistatic layer, and the occurrence of color unevenness in the reflected color can be further suppressed. (1) 1.55 ≦ n ₁ ≦ 1.70 (2) 1.50 ≦ n ₂ ≦ 1.65 (3) n ₁ −n ₂ ≦ 0.05

The relationship between n ₁ and n ₂ is given by the following equations (4) to (4).
It is more preferable that (6) be satisfied at the same time. (4) 1.60 ≦ n ₁ ≦ 1.65 (5) 1.57 ≦ n ₂ ≦ 1.62 (6) n ₁ −n ₂ ≦ 0.03

The thickness of the antistatic layer is such that sufficient antistatic performance can be obtained and the transmittance does not decrease due to coloring.
It is preferably from 30 to 500 nm, more preferably from 50 to 300 nm.

The antistatic layer is formed from a material whose refractive index is lower than that of the transparent substrate. As the antistatic layer, a layer made of a conductive metal oxide or a layer of a resin having a conductive metal oxide is preferable.

The metal oxide has a specific resistance of 1 × 10 ^-7 to 1
It is preferably × 10 ³ Ω · m. As the metal oxide, Sb ₂ O ₅ , SnO ₂ , In ₂ O ₃ , TiO ₂ ,
RuO ₂ , Ta ₂ O ₅ , Yb ₂ O ₃ , Ag ₂ O, Cu
Ob, Ob, and the like are preferable, and Sb ₂ O ₅ , SnO ₂ , In ₂ O _{3, and the} like are preferable because they have good transparency and film-forming properties. Further, an antistatic layer made of an oxide of an alloy of a metal of the above metal oxide and a metal such as Sb or Al may be used, which is preferable because conductivity is further increased.

The resin used for the antistatic layer is preferably selected from resins having film forming properties and useful for improving the adhesion between the transparent substrate and the low refractive index layer. The amount of the metal oxide to be added to the resin is adjusted so that the conductivity of the metal oxide is not impaired and the refractive index of the antistatic layer is equal to or less than the refractive index of the transparent substrate.

The resin used for the antistatic layer is the same as the resin used for the transparent substrate described above, or a phenol resin, an acrylic resin, a melamine resin, a cellulose resin, an epoxy resin, a vinyl resin, Vinyl acetate copolymer resin, ethylene / vinyl alcohol copolymer resin, polyamide resin, polyallyl ether resin, polyethylene resin, polyurethane resin, vinyl chloride resin,
Silicone resin, polystyrene resin, poly (o-chlorostyrene) resin, poly (2,6-dichlorostyrene) resin, poly (bromostyrene) resin, poly (2,6-dibromostyrene) resin, aromatic polyester resin, poly Examples include an aryl sulfone resin, a poly (pentabromophenyl methacrylate) resin, a phenoxy resin and a bromide thereof, and an epoxy resin and a bromide thereof.

In particular, phenoxy resins and epoxy resins are preferred because they have an adhesive group consisting of an epoxy group and can easily adhere the substrate to the low refractive index layer.

Further, a silane coupling agent or a silicone primer may be used to enhance the adhesion between the transparent substrate and the low refractive index layer to such an extent that the conductivity of the antistatic layer is not impaired.

As a method of forming the antistatic layer, the metal oxide is dispersed in an organic solvent solution of the resin used for the antistatic layer because the film formation cost is low, the coating property is excellent, and the production can be stably performed. The method of coating with a die coat using the prepared dispersion is preferable. When coating with a die coat, the organic solvent has a boiling point of 70 ° C or higher,
It is preferable that the surface tension is 50 dyn / cm or less.

Specific examples include cyclohexanone, toluene, xylene, isobutyl alcohol, isobutyl acetate, styrene, dodecane, nonane, dichloropentafluoropropane and the like. These organic solvents are 1
They can be used alone or as a mixture of two or more. In the case of organic solvents that have high surface tension and are difficult to coat,
A surfactant can be blended to lower the surface tension for coating.

The shape of the metal oxide is not particularly limited. The shape may be spherical, plate-like, polygonal, needle-like, elliptical, or the like, or two or more kinds may be used in combination.

The average particle size of the primary particles of the metal oxide in the dispersion is preferably from 10 to 100 nm, preferably from 20 to 70 n.
m is more preferred. If the average particle size is too small, aggregation and precipitation are likely to occur in a dispersion state, which is unstable, and the number of non-contact points between metal oxide particles increases when an antistatic layer is formed, and conductivity may be impaired. Not preferred. If the average particle size is too large, Rayleigh scattering occurs, haze increases, the amount of transmitted light decreases, and film thickness control is not easy.

In the case of a wet film-forming method in which only the metal oxide particles are dispersed, the particles charged on the positive electrode and the negative electrode may aggregate or precipitate. In that case, dispersibility and uniformity can be maintained over a long period of time by treating the surface of the metal oxide with a silane coupling agent. Further, when a silane coupling having a functional group such as an epoxy group or an amino group is used, the adhesion to a transparent substrate or a low refractive index layer can be enhanced.

The non-crystalline fluorine-containing polymer forming the low refractive index layer is not particularly limited as long as the polymer is excellent in transparency because the light is not substantially scattered by crystals. For example, tetrafluoroethylene / vinylidene fluoride / hexafluoropropylene = 37-48
Non-crystalline fluoroolefin-based copolymers such as terpolymers of 15% by weight / 15-35% by weight / 26-44% by weight, and polymers having a fluorinated aliphatic ring structure.
In particular, a polymer having a fluorinated aliphatic ring structure is preferably employed because of its excellent mechanical properties such as creep resistance.

Examples of the polymer having a fluorinated aliphatic ring structure include those obtained by polymerizing a monomer having a fluorinated ring structure and those obtained by cyclopolymerizing a fluorinated monomer having at least two polymerizable double bonds. The polymer having a fluorinated aliphatic ring structure in the main chain obtained by the above method is preferred.

Having a fluorinated aliphatic ring structure in the main chain means that at least one carbon atom constituting the aliphatic ring is a carbon atom in the carbon chain constituting the main chain, and It has a structure in which a fluorine atom or a fluorine-containing group is bonded to at least a part of the constituent carbon atoms.

A polymer having a fluorinated aliphatic ring structure in the main chain obtained by polymerizing a monomer having a fluorinated ring structure is known from JP-B-63-18964.
That is, perfluoro (2,2-dimethyl-1,3-
Homopolymers of a monomer having a fluorinated ring structure such as dioxol), and copolymers of this monomer and a radical polymerizable monomer such as tetrafluoroethylene.

A polymer having a fluorinated aliphatic ring structure in the main chain obtained by cyclopolymerization of a fluorinated monomer having at least two polymerizable double bonds is disclosed in
238111 and JP-A-63-238115. That is, a cyclized polymer of a fluorinated monomer having at least two polymerizable double bonds such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether), or a fluorinated polymer having at least two polymerizable double bonds Copolymers of a monomer and a radical polymerizable monomer such as tetrafluoroethylene are exemplified.

Further, perfluoro (2,2-dimethyl-
A monomer having a fluorinated ring structure such as 1,3-dioxole) is copolymerized with a fluorinated monomer having at least two polymerizable double bonds such as perfluoro (allyl vinyl ether) and perfluoro (butenyl vinyl ether). The obtained polymer may be used.

The polymer having a fluorinated aliphatic ring structure is
Polymers having a ring structure in the main chain are preferred, but those containing 20 mol% or more of polymerized units having a ring structure are preferred in terms of transparency, mechanical properties, and the like.

In the present invention, the method of forming the low refractive index layer is not particularly limited, and an arbitrary processing method can be selected. For example, polymers having a fluorinated aliphatic ring structure include perfluorooctane, CF ₃ (CF ₂ ) _n CH ＝ CH ₂ (n is an integer of 5 to 11), and CF ₃ (CF ₂ ) _m CH ₂ CH ₃
(M is an integer of 5 to 11), and is soluble in a fluorine-based solvent such as hydroxyfluoroether, and a predetermined thickness can be easily applied by applying a solution of this polymer and drying the solvent. The thickness of the low refractive index layer is 50 to 200 nm.
Is preferable, and 80 to 150 nm is more preferable.

In order to enhance the adhesion between the surface of the transparent substrate and the antistatic layer or the adhesion between the antistatic layer and the low refractive index layer, aminosilane coupling agents, epoxysilane coupling agents, amino groups, epoxy groups, etc. Silicone primer having a functional group (for example, PC-7 manufactured by Shin-Etsu Chemical Co., Ltd.)
In A) or the like, the surface of the transparent substrate or the surface of the antistatic layer may be treated with a thin film having a small optical influence of 10 nm or less.

Before the treatment for enhancing the adhesion or before forming the antistatic layer, the surface of the transparent substrate may be subjected to an active energy ray treatment such as a corona discharge treatment or an ultraviolet treatment. When forming a low refractive index layer on the surface of the antistatic layer, the surface of the antistatic layer is subjected to corona discharge treatment in order to enhance adhesion.
Active energy ray treatment such as ultraviolet treatment may be performed.

After coating the low refractive index layer,
In order to completely evaporate the coating solvent and increase the adhesion of the formed coating layer, bake it at a temperature that the transparent substrate film and the coating layer can withstand, or radiate thermal energy such as far-infrared irradiation, electron beam, etc. Good to give.

In order to impart abrasion resistance to the surface of the low-refractive-index layer, a lubricant is applied to the surface of the low-refractive-index layer to such an extent that the antireflection performance is not impaired. You may mix. As such lubricants, such as DuPont product name Krytox, Daikin product name Demnum, Daikin product name Daifoil, Ausimont product name Fomblin, Asahi Glass product name Freonlube, etc. Perfluoropolyethers.

The coating method for producing the antireflective substrate of the present invention is preferably a dip coating method, a roll coating method, a spray coating method, a gravure coating method, a comma coating method, or the like. These coating methods are capable of continuous processing, and are superior in productivity as compared with a batch type evaporation method. Although the productivity is slightly inferior, a spin coating method or the like can also be employed.

In particular, the use of a die coat known in Japanese Patent Application Laid-Open No. 07-151904 is excellent in continuous productivity, can form a large-sized film, has a small thickness deviation, and can easily cope with small to large models.

The article using the anti-reflective substrate in the present invention is not particularly limited as long as it has a transparent substrate requiring antistatic properties and low anti-reflective properties. For example, electrical products such as a personal computer, a television, a video player, a video recorder, and a display can be used. Examples of the display include a CRT, a liquid crystal display, a plasma display, a light emitting diode display, and an electrochromic display.

The antireflective substrate of the present invention comprises a polarizing film,
Alternatively, it can be attached to a display so as to display text or image information, or can be attached to another film or sheet. By sticking this antireflective base material, it is possible to contribute to improvement of the strength of the display body or prevention of scattering.

The method for attaching the antireflective substrate is not particularly limited, and a method such as adhesion, adhesion, and heat fusion can be selected. When the antireflective substrate of the present invention is attached to another film or sheet, it is visible as described above when it is disposed on the front of a display such as a front panel of a projection screen, a CRT filter, a liquid crystal display protection panel, or the like. It can contribute to improvement of the performance and is also useful as a touch panel.

[0043]

EXAMPLES Example 1 (Synthesis Example) 35 g of perfluoro (butenivinyl ether), 150 g of ion-exchanged water, and ((CH ₃ ) ₂ as a polymerization initiator)
90 mg of (CHOCOO) ₂ was placed in a pressure-resistant glass autoclave having an internal volume of 200 ml. After replacing this with nitrogen three times, suspension polymerization was carried out at 40 ° C. for 22 hours. As a result, 28 g of a polymer (hereinafter, referred to as polymer A) was obtained.

The intrinsic viscosity [η] of the polymer A is 0.5 at 30 ° C. in perfluoro (2-butyltetrahydrofuran).
dl / g. Glass transition point of polymer A is 108 ° C.
And at room temperature was a tough and transparent glassy polymer. The 10% thermal decomposition temperature was 460 ° C., the refractive index was as low as 1.34, and the light transmittance was as high as 95% or more. A 2.0% by weight solution of polymer A in perfluoro (2-butyltetrahydrofuran) (hereinafter referred to as solution A) was prepared.

Example 2 (Synthesis Example) Cyclohexanone dispersion of Sn-Sb alloy oxide (ELCOM-P3580, manufactured by Kasei Kagaku Kogyo Co., Ltd., solid content concentration: 5)
70% by weight of brominated epoxy resin diluted with cyclohexanone (phenotote, manufactured by Toto Kasei Co.,
(% By weight) was added to obtain a coating solution (hereinafter referred to as solution B). The solution B was spin-coated on a glass surface and heated at 120 ° C. for 10 minutes to form an antistatic layer. The refractive index of the antistatic layer was 1.63.

Example 3 (Example) A solution B was applied to a polyethylene terephthalate film having a refractive index of 1.63 [A4100 manufactured by Toyobo Co., film thickness 100 μm] (hereinafter abbreviated as PET film C) to a film thickness of 100 nm by a die coating method. And then coated with solution A to a thickness of 104 nm, and passed through an oven at 120 ° C. to obtain a “PET film having an antistatic layer and a low refractive index layer” (hereinafter referred to as PET film D). Abbreviated).

The visible light of the PET film D (wavelength 400
To 700 nm) (hereinafter, 400 to 70).
The average reflectance at 0 nm was abbreviated to 0.3%. PE
When the back surface of the T film D was attached to a liquid crystal display (LCD), reflection of external light was reduced and visibility was improved.

Example 4 (Comparative Example) The average reflectance on one side of PET film C was 6.0%. Further, when the back surface of the PET film C was attached to the LCD surface, reflection of outside light was intense, and it was confirmed that visibility was impaired.

Example 5 (Comparative Example) Solution A was applied to PET film C by die coating method to a film thickness of 104.
nm, and passed through an oven at 120 ° C. to obtain “PET film having only low refractive index layer” (hereinafter abbreviated as PET film E). PET
The single-sided average reflectance of the film E for visible light (wavelength 400 to 700 nm) was 0.3%. When the rear surface of the PET film E was attached to the LCD, reflection of external light was reduced, and visibility was improved.

Example 6 (Comparative Example) In place of the PET film C in Example 3, "refractive index 1.
"Acrylic film having antistatic layer and low refractive index layer" (hereinafter acrylic film) in the same manner as in Example 3, except that a polymethyl methacrylate film [film thickness of 100 µm] (hereinafter abbreviated as acrylic film F) is used. G).

The visible light (wavelength 40) of the acrylic film G
0 to 700 nm) (hereinafter, 400 to 7)
(Abbreviated as average reflectance at 00 nm) was 0.3%. When the back surface of the acrylic film G was attached to the LCD, reflection of external light was reduced and visibility was improved, but color unevenness of the reflected color was observed.

The PET films C to E and the acrylic film G in Examples 3 to 6 were subjected to surface resistivity measurement, ash adhesion degree test, abrasion test and cross cut tape test. Table 1 shows the results.

The surface resistivity was measured using an Ultra High Resistance Meter manufactured by Advantest. In the ash adhesion degree test, immediately after the three types of film surfaces of Examples 3 to 5 were abraded 20 times with a dry cloth in a room, the film was brought close to dry tobacco ash and the degree of ash adhesion was observed. The abrasion test was performed by using Oda Shoji Co., Ltd.'s Dasper K under a load of 500 g and reciprocating abrasion 40 times, and the film appearance after the test was observed. The crosscut tape test was performed based on the JIS K5400 crosscut tape method.

[0054]

[Table 1]

[0055]

According to the present invention, since the refractive index of the antistatic layer in the present invention is lower than the refractive index of the transparent substrate, optically, it does not depend on the thickness of the antistatic layer, but the high antireflection effect of the low refractive index layer. Is obtained. Further, the thickness deviation of the antistatic layer hardly causes optical unevenness, and a large-sized antireflection base material can be easily manufactured.

The anti-reflective substrate of the present invention has excellent anti-reflective properties and anti-static properties, and the anti-static layer enhances the adhesion between the substrate and the low refractive index layer and prevents scratching and peeling. be able to. Therefore, for example, in an image display product using this antireflective base material as a protective plate on the surface, reflection of external light impairs the appearance, or dust adheres to the surface due to static electricity and the image of the display body Is not blurred.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09F 9/00 318 G02B 1/10 Z

Claims (5)

[Claims] 1. An anti-reflective substrate comprising a transparent substrate, and an antistatic layer and a low refractive index layer comprising a non-crystalline fluoropolymer in order from the transparent substrate surface side. An antireflective substrate, wherein the refractive index is lower than the refractive index of the transparent substrate and the refractive index of the low refractive index layer is lower than the refractive index of the transparent substrate. Wherein the refractive index n ₂ of the following formula refractive index n ₁ and an antistatic layer of a transparent substrate (1) to (3) simultaneously satisfying claim 1 antireflective substrate described. (1) 1.55 ≦ n ₁ ≦ 1.70 (2) 1.50 ≦ n ₂ ≦ 1.65 (3) n ₁ −n ₂ ≦ 0.05 3. The antireflective substrate according to claim 1, wherein the low refractive index layer has a refractive index of 1.36 or less. 4. The antireflective substrate according to claim 1, wherein the non-crystalline fluorine-containing polymer is a polymer having a fluorine-containing aliphatic ring structure. 5. An article using the antireflective substrate according to claim 1, 2, 3, or 4.