WO2012141422A1 - Procédé pour préparer une résine de copolymère acrylique pour film optique et procédé pour fabriquer un film optique utilisant celle-ci - Google Patents

Procédé pour préparer une résine de copolymère acrylique pour film optique et procédé pour fabriquer un film optique utilisant celle-ci Download PDF

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WO2012141422A1
WO2012141422A1 PCT/KR2012/000869 KR2012000869W WO2012141422A1 WO 2012141422 A1 WO2012141422 A1 WO 2012141422A1 KR 2012000869 W KR2012000869 W KR 2012000869W WO 2012141422 A1 WO2012141422 A1 WO 2012141422A1
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Prior art keywords
weight parts
acrylic
meth
monomer
acrylic copolymer
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Ceased
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PCT/KR2012/000869
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English (en)
Inventor
Eun-Jung Choi
Chang-Hun Han
Jae-Bum Seo
Beom-Seok Kim
Byoung-Il Kang
Nam-Jeong Lee
Su-Kyung Kim
Jun-Geun Um
Da-Eun Sung
Joong-Hoon Lee
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LG Chem Ltd
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LG Chem Ltd
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Priority claimed from KR1020110083999A external-priority patent/KR101270220B1/ko
Application filed by LG Chem Ltd filed Critical LG Chem Ltd
Priority to CN201280014427.6A priority Critical patent/CN103443147B/zh
Priority to JP2013544407A priority patent/JP5796837B2/ja
Priority to US14/006,267 priority patent/US9429682B2/en
Publication of WO2012141422A1 publication Critical patent/WO2012141422A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
    • 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
    • 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
    • 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
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
    • C08J2333/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • G02B1/105—
    • 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
    • G02B1/11—Anti-reflection coatings
    • G02B1/111—Anti-reflection coatings using layers comprising organic materials

Definitions

  • the present invention relates to a method for preparing a resin for an optical film and, more particularly, to a method for fabricating an acrylic copolymer resin having excellent thermal stability.
  • Advanced level requirements are required for a polymer material used for such displays.
  • LCDs as LCDs are becoming thinner, lighter, and larger in terms of screen area, obtaining a wide viewing angle and a high contrast ratio, suppressing of a change in an image color according to a viewing angle, and making a screen display uniform have become particularly significant issues.
  • various polymer films are used for a polarization film, a polarizer protective film, a retardation film, a plastic substrate, a light guide plate, and the like, and various modes of LCD devices using twisted nematic (TN), super-twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS) liquid crystal cells, and the like, as liquid crystal have been developed.
  • These liquid crystal cells have a unique liquid crystal arrangement, respectively having a unique optical anisotropy, and, in order to compensate for the optical anisotropy, films obtained by stretching various types of polymers and providing retardation function thereto have been proposed.
  • a polarization plate generally has a structure in which a triacetyl cellulose film (TAC) film is laminated on a polarizer as a protective film, using a water-based adhesive made of a polyvinylalcohol-based aqueous solution.
  • TAC triacetyl cellulose film
  • the degree of polarization may be degraded, the polarizer and the protective film may be separated, and optical characteristics may be degraded, such that the polarization plate is variably restricted in terms of the purpose thereof.
  • the TAC film has an in-plane retardation value (R in ) and a thickness retardation value (R th ) which are severely changed according to changes in ambient temperature and moisture in the surrounding environment, and, in particular, a retardation value with respect to incident light in a tilt direction is greatly varied.
  • R in in-plane retardation value
  • R th thickness retardation value
  • the TAC film has a great dimensional variation according to changes in ambient temperature and moisture environments and a relatively high photoelastic coefficient value.
  • retardation characteristics may be changed locally to thereby degrade image quality.
  • An acrylic resin has been well known as a material for complementing the various shortcomings of the TAC film.
  • the acrylic resin does not have sufficient heat resistance characteristics, and creates a retardation in in-plane and thickness directions after being stretched, and therefore is not appropriate to be applied as a protective film.
  • An aspect of the present invention provides a method for preparing an acrylic copolymer resin having excellent thermal stability, transparency, and optical physical properties.
  • a method for preparing an acrylic copolymer resin for an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; and thermally treating the copolymer at a temperature ranging from 240°C to 300°C .
  • the suspension-polymerizing may include: a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60°C to 90°C for two to three hours; and a second polymerization operation of increasing the temperature by 5°C to 20°C, based on the temperature of the first polymerization operation, and additionally performing polymerization for one to two hours.
  • the second polymerization operation may be performed at a temperature ranging from 80°C to 100°C.
  • the acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
  • the alkyl group of the alkyl(meth)acrylate monomer may have 1 to 10 carbon atoms.
  • the alkyl(meth)acrylate monomer may be selected from the group consisting of methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, and ethylethacrylate.
  • the (meth)acrylic acid monomer may be selected from the group consisting of acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, and butylmethacrylic acid.
  • the acrylic copolymer resin for an optical film obtained by the preparation method may include glutaric anhydride.
  • the acrylic copolymer resin for an optical film obtained through the preparation method may include 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit, over 100 weight parts of the acrylic copolymer resin.
  • a glass transition temperature of the acrylic copolymer resin may be 120°C or higher.
  • Haze of the acrylic copolymer resin may range from 0.1 to 1%, and transmittance thereof may be 90% or more.
  • the thermal treatment may be performed as an extrusion operation.
  • the extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
  • the extrusion operation may be performed in vacuum at a pressure lower than 40 torr.
  • a method for fabricating an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240°C to 300°C; extruding the acrylic copolymer to fabricate a film; and stretching the film.
  • the operation for preparing the acrylic copolymer may be the same as described above, and thermally treating the acrylic copolymer and extruding the acrylic copolymer to fabricate a film may be performed as a single operation.
  • the extrusion operation may be performed by performing a re-extrusion two to five times by using a twin screw extruder.
  • the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple.
  • MD mechanical direction
  • TD transverse direction
  • the optical film having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from -5 to 5 nm respectively:
  • n x is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction
  • n y is a refractive index in a direction perpendicular to the n x direction in the in-plane direction
  • n z is a refractive index in a thicknesswise direction
  • d is the thickness of the film.
  • the optical film may have a coefficient of thermal expansion (CTE) of 70 ppm/°C or lower.
  • a resin having an effectively lowered CTE and an optical film can be manufactured by inducing the formation of a glutaric anhydride structure by using suspension polymerization that facilitates adjustment of the molecular weight of a resin.
  • An aspect of the present invention provides a method for preparing an acrylic copolymer resin for an optical film, including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare a copolymer ; and thermally treating the copolymer at a temperature ranging from 240°C to 300°C.
  • the copolymer may be a block copolymer or a random copolymer, but the form of the copolymer is not limited thereto.
  • suspension polymerization includes any suspension polymerization methods generally used in the related art.
  • a suspension polymerization method a raw material monomer is dispersed in an immiscible liquid such as water and polymerized by adding an initiator, or the like, thereto. With this method, heat generated as a polymer is polymerized is transferred to the immiscible liquid, facilitating controlling of heating and adjusting of molecular weight in relation to toughness.
  • an immerscible liquid that may be used in an embodiment of the present invention is water.
  • the suspension-polymerization operation may be performed by including a first polymerization operation of performing suspension polymerization at an initial reaction temperature ranging from 60°C to 90°C for two to three hours and a second polymerization operation of increasing the temperature to 80°C to 100°C and additionally performing polymerization for one to two hours.
  • the first polymerization operation of performing suspension polymerization at the initial reaction temperature satisfies a condition of an initiator used in the related art. If the initial reaction temperature is lower than 60°C, it may not be able to effectively secure a polymerization conversion ratio, and if the initial reaction temperature exceeds 90°C, there may be a problem in controlling an initial reaction such as heat controlling.
  • a reaction temperature may be set according to a half-life of the initiator and a reaction duration may be adjusted to be two to three hours.
  • the reaction duration is related to efficiency, which is not particularly limited so long as it is within a range in which an appropriate polymerization level is obtainable; however, since it is more effective as the reaction duration is shorter, the reaction duration may be two to three hours.
  • the conversion ratio may be enhanced by the second polymerization operation in which the temperature is increased and polymerization is additionally performed.
  • the temperature in the second polymerization operation may be increased to be higher by about 5°C to 20°C, preferably, by 10°C, based on the initial polymerization temperature in the aspect of completing the polymerization of an unreacted monomer.
  • the second polymerization operation is preferably performed at a temperature ranging from 80°C to 100°C. If the additional polymerization operation is performed at a temperature lower than 80°C, efficiency in completing the polymerization may be degraded, and if the additional polymerization operation is performed at a temperature higher than 100°C, it may be difficult to control a reaction such as a rise in temperature.
  • the reaction duration is one to two hours.
  • a resin in order to enhance toughness of a stretched film, a resin is prepared by using suspension polymerization facilitating the adjustment of molecular weight of the resin, and since the heat treatment operation is included, a formation of glutaric anhydride may be induced by providing thermal history to the resin.
  • the prepared copolymer is heated to a temperature ranging from 240°C to 300°C, and preferably, to a temperature ranging from 260°C to 290°C. If the temperature for the thermal treatment operation is lower than 240°C, glutaric anhydride may not be effectively generated, and if the temperature for the thermal treatment operation exceeds 300°C, there may be a problem with stability in relation to resin decomposition.
  • the thermal treatment operation may be performed as an extrusion operation. Namely, it is preferable in terms of process that the copolymer obtained in the form of granule according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240°C to 300°C so as to be prepared.
  • the copolymer is re-extruded two to five times by using a twin screw extruder, but the number of re-extrusions may vary, depending on the temperature and the length of the extruder, and an amount of extrusions exceeding five times is not desirable in terms of stability, according to resin degradation.
  • the copolymer is re-extruded two or more times by using the twin screw extruder with the screws having a length of about 1 m, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
  • the extrusion process may be preferably performed in a vacuum state, and more preferably, performed in a state in which the degree of vacuum is less than 40 torr. Since, in an embodiment of the present invention, glutaric anhydride is generated through the foregoing extrusion process, a higher efficiency than a case in which methanol, or the like, generated in the conversion reaction is removed in a vacuum can be obtained.
  • the acrylic copolymer resin including (meth)acrylic acid monomer is thermally treated to induce a generation of glutaric anhydride, thus lowering the coefficient of thermal expansion of the resin.
  • the acrylic copolymer resin for an optical film prepared as described above may be in a pellet state, and include glutaric anhydride.
  • the glutaric anhydride unit is generated as an alkyl(meth)acrylate unit and/or an acrylic unit containing a benzene ring, and a (meth)acrylic acid unit react according to the thermal treatment after the preparation of the copolymer.
  • the content of the glutaric anhydride unit within the finally obtained acrylic copolymer for an optical film can be adjusted by regulating the content of the (meth)acrylic acid monomer applied for polymerization and the degree of thermal treatment.
  • unit is used to designate a corresponding component that does not exist in the form of a monomer in a case in which a monomer is polymerized to form a copolymer.
  • the four-composite copolymer including the glutaric anhydride unit has an effect of reducing the coefficient of thermal expansion, which is not found in the three-composite copolymer including the alkyl(meth) acrylate monomer, the acrylic monomer containing a benzene ring, and the (meth)acrylic acid monomer, while maintaining the same excellent retardation characteristics as those of the three-composite copolymer. This is because macromolecule chain rotation is limited by a bulky functional group of the glutaric anhydride.
  • the content of the monomers added for polymerization is 3 to 15 weight parts of an acrylic monomer containing the benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate monomer, and 5 to 20 weight parts of a (meth)acrylic acid monomer.
  • the acrylic monomer containing the benzene rings When the acrylic monomer containing the benzene rings is out of the given range, there may be a problem in adjusting a retardation of a protective film. Also, if the (meth)acrylic acid monomer is less than 5 weight parts, the content of the generated glutaric anhydride may be insufficient to lower the coefficient of thermal expansion, and if the (meth)acrylic acid monomer exceeds 20 weight parts, thermal stability of the final resin may be increased, resulting in a film becoming brittle when fabricated.
  • the acrylic monomer containing the benzene ring serves to adjust the retardation in in-plane or thickness directions, such that the acrylic copolymer resin according to an embodiment of the present invention can be appropriately applied as a polarizer protective film.
  • the acrylic monomer containing the benzene ring may be substituted with an aryl group having 6 to 40 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, an aryloxy group having 6 to 40 carbon atoms, or an aryloxyalkyl group having 6 to 40 carbon atoms.
  • the acrylic monomer containing the benzene ring may be (meth)acrylate substituted with an arylalkyl group having 6 to 15 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, or an aryloxyalkyl group having 6 to 15 carbon atoms in terms of transparency.
  • Preferred examples of the acrylic monomer containing a benzene ring may be selected from the group consisting of benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 3-phenylpropyl acrylate, and 2-phenoxyethyl acrylate.
  • the acrylic monomer containing the benzene ring may be benzyl methacrylate.
  • 'alkyl(meth)acrylate monomer' may refer to both an 'alkylacrylate monomer' and an 'alkylmethacrylate monomer'.
  • the alkyl group of the alkyl(meth) acrylate monomer has, preferably, 1 to 10 carbon atoms, more preferably, 1 to 4 carbon atoms, and more preferably, is a methyl group or an ethyl group.
  • the alkyl(meth)acrylate monomer may include methylacrylate, ethylacrylate, methylmethacrylate, ethylmethacrylate, methylethacryate, ethylethacrylate, and the like. Among them, methylmethacrylate is the most preferable, but the present invention is not limited thereto.
  • the '(meth)acrylic acid monomer' refers to the inclusion of an 'acrylic acid monomer' and a 'methacrylic acid monomer'.
  • the (meth)acrylic acid monomer allows the acrylic copolymer resin according to an embodiment of the present invention to have sufficient thermal stability, and induces generation of glutaric anhydride to thus lower the coefficient of thermal expansion of the resin.
  • the (meth)acrylic acid monomer may be substituted with an alkyl group having 1 to 5 carbon atoms, or may be unsubstituted.
  • the (meth)acrylic acid monomer may be, for example, acrylic acid, methacrylic acid, methylacryl acid, methylmethacrylic acid, ethylacrylic acid, ethylmethacrylic acid, butylacrylic acid, butylmethacrylic acid, or the like. Among these, the use of methacrylic acid is most economical.
  • the acrylic copolymer resin for an optical film obtained through the foregoing preparation method includes 3 to 15 weight parts of an acrylic unit containing a benzene ring, 65 to 92 weight parts of an alkyl(meth)acrylate unit, 0 to 4 weight parts of a (meth)acrylic acid unit, and 5 to 16 weight parts of a glutaric anhydride unit.
  • the copolymer resin may not be effective to lower the coefficient of thermal expansion, and in order to prepare the copolymer resin in which the content of glutaric anhydride exceeds 16 weight parts over 100 weight parts of the overall copolymer resin, the content of acrylic acid may be required to be increased. In this case, however, thermal stability may be increased to be so high as to make the final film brittle. Thus, preferably, a great deal of acrylic acid is converted into glutaric anhydride, after polymerization, to lower the coefficient of thermal expansion.
  • a weight-average molecular weight of the acrylic copolymer resin preferably ranges from 50000 to 500000 in terms of thermal stability, processibility, and productivity, and more preferably, from 50000 to 200000.
  • a glass transition temperature Tg of the acrylic copolymer resin may preferably be 120°C or higher, and more preferably, 125°C or higher.
  • a method for fabricating an optical film including: suspension-polymerizing an acrylic monomer containing a benzene ring, an alkyl(meth)acrylate monomer, and a (meth)acrylic acid monomer to prepare an acrylic copolymer; thermally treating the acrylic copolymer at a temperature ranging from 240°C to 300°C; extruding the acrylic copolymer to fabricate a film; and stretching the film.
  • the thermally treating and the extruding the acrylic copolymer to fabricate a film are performed as a single operation. Namely, it is preferable, in terms of process, that a copolymer obtained in the form of granules according to the outcome of the suspension polymerization is hot-extruded at a temperature ranging from 240°C to 300°C to fabricate a film.
  • a film may be fabricated with the acrylic copolymer resin by a method well known in the art such as a caster method, or the like, but the extrusion method, which is economical, is desirous.
  • the copolymer is re-extruded two to five times by using a twin screw extruder, but a single extrusion may be performed according to a provided temperature range and device, or a single screw extruder may be used under conditions in which heat transmission and extrusion are effectively performed.
  • uni-axially or bi-axially stretching the film may be additionally performed.
  • stretching in a mechanical direction (MD) (or a vertical direction) and stretching in a transverse direction (TD) (or a horizontal direction) may be separately performed, or both may be performed together.
  • MD mechanical direction
  • TD transverse direction
  • any one of vertical stretching and horizontal stretching may first be performed and then the stretching in the other direction may be performed.
  • vertical and horizontal stretching may be simultaneously performed. Stretching may be performed in a single stage or in multiple stages. In the case of vertical stretching, the stretching may be performed according to difference between the speeds of rollers, and in the case of horizontal stretching, a tenter may be used.
  • a rail initiation angle of the tenter is generally within 10 degrees to restrain a bowing phenomenon occurring in the event of horizontal stretching, and to control the angle of an optical axis regularly.
  • the same bowing restraining effect can also be obtained by performing multistage horizontal stretching.
  • the film may be stretched in a vertical direction (i.e., in a mechanical direction (MD)) so as to be double and then stretched biaxially in a horizontal direction (i.e., in a transverse direction (TD)) so as to be triple.
  • MD mechanical direction
  • TD transverse direction
  • a conditioner may be added according to circumstances, to fabricate a film.
  • the stretching may be performed at a temperature ranging from (Tg - 20°C) ⁇ (Tg + 30°C).
  • the glass transition temperature refers to a temperature range starting from a temperature at which a storage modulus of the copolymer resin starts to be lowered so a loss modulus starts to be increased to be greater than the storage modulus to a temperature at which orientation of polymer chains is lessened to be lost.
  • the glass transition temperature may be measured by a differential scanning calorimetry (DSC).
  • DSC differential scanning calorimetry
  • the temperature at the time of the stretching process may be a glass transition temperature of the film.
  • the optical film fabricated as described above having an in-plane retardation value represented by Equation 1 shown below and a thickness retardation value represented by Equation 2 shown below may range from -5 to 5 nm.
  • n x is a refractive index in a direction in which the refractive index is the greatest in the in-plane direction
  • n y is a refractive index in a direction perpendicular to the n x direction in the in-plane direction
  • n z is a refractive index in a thicknesswise direction
  • d is the thickness of the film.
  • the thickness of the optical film fabricated as described above may range from 20 to 200 ⁇ m, preferably, range from 40 to 120 ⁇ m, and have transparency (haze) ranging from 0.1 to 1% and transmittance of 90% or more.
  • the optical film has a coefficient of thermal expansion (CTE) of 70 ppm/°C or lower.
  • CTE coefficient of thermal expansion
  • the thickness, transparency, and transmittance of the film are within the foregoing ranges, in case of using the optical film according to an embodiment of the present invention as a protective film of a polarizer, image quality is not degraded.
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • the prepared mixture was primarily suspension-polymerized at an initial reaction temperature of 80°C for two hours, and then, the temperature was raised to 95°C to perform secondary polymerization on the resultant material for one hour.
  • the resultant material was then cleansed and dried to fabricate MMA-BzMA-MAA beads.
  • the obtained beads were re-extruded twice through a co-rotating twin screw extruder at 270°C to prepare a resin in a state of pellet, and at this time, the degree of vacuum (Torr) was 20.
  • the composition of the final resin is shown in Table 1 below and the physical properties of the final resin are shown in Table 3 below.
  • an extruded film having a thickness of 180 ⁇ m was fabricated by using an extruder including a T-die.
  • the fabricated film was stretched in a mechanical direction (MD) so as to be double and then stretched biaxially in a transverse direction (TD) so as to be triple, thus fabricating a film having a thickness of 60 ⁇ m, and TAC and PVA were bonded to the film to fabricate a polarization plate.
  • MD mechanical direction
  • TD transverse direction
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • a resin was prepared through the same process as that of Embodiment 1.
  • the composition of the final resin is shown in Table 1, the physical properties of the final resin are shown in Table 3, and the physical properties of the film are shown in Table 5.
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • MMA methyl methacrylate
  • BzMA benzyl methacrylate
  • MAA methacrylic acid
  • a resin was prepared through the same process as that of Embodiment 1.
  • the composition of the final resin is shown in Table 2, the physical properties of the final resin are shown in Table 4, and the physical properties of the film are shown in Table 6.
  • compositions of the final resins and physical evaluation method of the final resin were as follows.
  • Weight-average molecular weight (Mw) The prepared resin was dissolved in tetrahydropurane and measured by using gel permeation chromatography (GPC).
  • Tg Glass transition temperature
  • Haze and light transmittance Measured based on an ASTM 1003 method.
  • a method for evaluating the physical properties of the film according to an embodiment of the present invention is as follows.
  • Retardation value (R in ,R th ): Measured by using an Elli-SE from Ellipso Tech. Co., Ltd.
  • Toughness Measured by bending a 60 ⁇ m film ten times by hand to check whether or not it would break ( ⁇ : unbroken, ⁇ : broken one to three times, ⁇ : broken five or more times)
  • the CTE can be lowered while satisfying the basic conditions with respect to the polarizer protective film such as retardations by polymerizing using particular compositions and contents of monomers and performing a thermal treatment thereupon.

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Abstract

La présente invention concerne un procédé pour préparer une résine de copolymère acrylique pour un film optique qui comprend : la polymérisation en suspension d'un monomère acrylique contenant un cycle benzénique, un monomère de (méth)acrylate d'alkyle, et un monomère d'acide (méth)acrylique pour préparer un copolymère ; et le traitement thermique du copolymère à une température dans la plage de 240 °C à 300 °C. Selon le procédé pour préparer un copolymère acrylique de la présente invention, une résine ayant un CTE efficacement abaissé peut être fabriquée en induisant la formation d'une structure d'anhydride glutarique en utilisant une polymérisation en suspension qui facilite l'ajustement du poids moléculaire d'une résine.
PCT/KR2012/000869 2011-04-13 2012-02-07 Procédé pour préparer une résine de copolymère acrylique pour film optique et procédé pour fabriquer un film optique utilisant celle-ci Ceased WO2012141422A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN201280014427.6A CN103443147B (zh) 2011-04-13 2012-02-07 制备光学膜用丙烯酸系共聚物树脂的方法及使用其制造光学膜的方法
JP2013544407A JP5796837B2 (ja) 2011-04-13 2012-02-07 光学フィルム用アクリル系共重合体樹脂の製造方法及びこれを用いた光学フィルムの製造方法
US14/006,267 US9429682B2 (en) 2011-04-13 2012-02-07 Method for preparing acrylic copolymer resin for optical film and method for fabricating optical film using the same

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2011-0034443 2011-04-13
KR20110034443 2011-04-13
KR1020110083999A KR101270220B1 (ko) 2011-04-13 2011-08-23 광학 필름용 아크릴계 공중합체 수지의 제조방법 및 이를 이용한 광학필름의 제조방법
KR10-2011-0083999 2011-08-23

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US11008452B2 (en) 2015-07-31 2021-05-18 Mitsubishi Chemical Corporation Copolymer, process for producing copolymer, resin composition, shaped article and vehicle

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US4874824A (en) * 1987-11-23 1989-10-17 Rohm And Haas Company Process for manufacturing low-acid, glutaric-anhydride-containing copolymers
EP0264508B1 (fr) * 1985-05-02 1991-09-11 Sumitomo Chemical Company, Limited Procédé de préparation de copolymères thermoplastiques stables à la chaleur
US20090275718A1 (en) * 2008-04-30 2009-11-05 Lg Chem, Ltd. Resin composition and optical films formed by using the same
KR20100104518A (ko) * 2009-03-18 2010-09-29 주식회사 엘지화학 아크릴계 공중합체 수지, 이를 포함하는 광학 필름 및 액정표시 장치

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EP0264508B1 (fr) * 1985-05-02 1991-09-11 Sumitomo Chemical Company, Limited Procédé de préparation de copolymères thermoplastiques stables à la chaleur
US4874824A (en) * 1987-11-23 1989-10-17 Rohm And Haas Company Process for manufacturing low-acid, glutaric-anhydride-containing copolymers
US20090275718A1 (en) * 2008-04-30 2009-11-05 Lg Chem, Ltd. Resin composition and optical films formed by using the same
KR20100104518A (ko) * 2009-03-18 2010-09-29 주식회사 엘지화학 아크릴계 공중합체 수지, 이를 포함하는 광학 필름 및 액정표시 장치

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11008452B2 (en) 2015-07-31 2021-05-18 Mitsubishi Chemical Corporation Copolymer, process for producing copolymer, resin composition, shaped article and vehicle

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