KR102072883B1 - Optical films, polarizing plate and liquid crystal display apparatus and method for manufacturing same - Google Patents

Abstract

Herein is a step of forming a hard coating layer on the substrate; And a method of manufacturing an optical film comprising forming a polymer coating layer on the hard coating layer, a method of manufacturing a polarizing plate using the same, an optical film, a polarizing plate, and a liquid crystal display device manufactured by the method.

Description

Optical film, polarizing plate and liquid crystal display device and manufacturing method thereof {OPTICAL FILMS, POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY APPARATUS AND METHOD FOR MANUFACTURING SAME}

The present application relates to an optical film, a polarizing plate and a display device, and a manufacturing method thereof.

BACKGROUND ART Liquid crystal displays have a widespread use as optical display elements because they have lower power consumption, smaller volume, lighter weight, and easier portability than cathode ray tube displays. In general, a liquid crystal display has a basic configuration in which polarizers are provided on both sides of a liquid crystal cell.

The polarizing plate is generally composed of a polarizer and a protective film respectively provided on both sides of the polarizer. The polarizing plate is manufactured by a process of separately manufacturing two protective films and a polarizer, and laminating with an adhesive. Therefore, the manufacturing process and the lamination process have to be separately, so process efficiency and cost increase are problematic. In addition, when using the above process, when the protective film is too thin, the protective film is likely to be torn and difficult to handle. Therefore, a protective film of 25 micrometers or more is currently used. However, in this case, since there is a limit to thinning the thickness of the entire polarizing plate, it is inconsistent with the trend of the liquid crystal display device which is required to be thinner.

Korean Patent Application Publication No. 2004-0071485

The present application not only simplifies the process, but also provides an optical film and a polarizing plate manufacturing method capable of improving the thinning and anti-cracking function of the polarizing plate, and an optical film, polarizing plate, and display device manufactured using such a process. .

One embodiment of the present application

Forming a hard coat layer on the substrate; And

Forming a polymer coating layer on the hard coating layer

It provides a method for producing an optical film comprising a.

Another embodiment of the present application

Manufacturing an optical film by the method;

Laminating the polymer coating layer of the optical film to a polarizer; And

It provides a method of manufacturing a polarizing plate comprising the step of peeling the substrate in the optical film.

Another embodiment of the present application is described; A hard coating layer provided on the substrate; And it provides an optical film comprising a polymer coating layer provided on the hard coating layer.

Another embodiment of the present application is a polarizer; And the optical film provided on at least one surface of the polarizer, wherein the polymer coating layer includes an optical film disposed adjacent to the polarizer.

Another embodiment of the present application is a polarizer; A polymer coating layer provided on at least one surface of the polarizer; And it provides a polarizing plate comprising a hard coating layer provided on the opposite side of the surface of the polymer coating layer facing the polarizer.

Another embodiment of the present application provides a liquid crystal display device including the polarizing plate described above.

According to the embodiments described herein, by introducing both the polymer coating layer and the hard coating layer that can act as a polarizing plate protective film by the coating method, the lamination process of the polarizer and the protective film or the hard coating layer introduction process on the protective film In addition to simplifying the cost, the manufacturing cost can be greatly reduced. In addition, by introducing the polymer coating layer and the hard coating layer by the coating method, the thickness can be adjusted as necessary, thereby realizing a layer thinner than the existing thickness, as well as additional adhesion or adhesion for lamination with the polarizer Since no layer is required, the thickness of the polarizing plate can be expected. In addition, compared with the conventional extrusion film protection process, not only can the thickness variation be reduced, but also the coating process has a lower process temperature than the extrusion process or the melt casting process, so that the material of the polymer coating layer can be There is no need to limit it to an excellent polymer or additive, so it is also advantageous from a material selection point of view, and an inexpensive material can be selected.

1 is a schematic view illustrating a manufacturing process of an optical film according to an exemplary embodiment of the present application.
2 illustrates a laminated structure of an optical film according to an exemplary embodiment of the present application.
3 and 4 are schematic views illustrating the manufacturing process of the polarizing plate according to the exemplary embodiment of the present application, respectively.
5 and 6 illustrate a laminated structure of a polarizing plate according to an exemplary embodiment of the present application, respectively.
7 and 8 illustrate a laminated structure of a liquid crystal display device according to an exemplary embodiment of the present application, respectively.
9 shows the results of thermal shock evaluation, heat resistance evaluation and water resistance evaluation of the polarizing plates prepared in Examples and Comparative Examples.

Hereinafter, the exemplary embodiments of the present application will be described in detail.

Method for producing an optical film according to an embodiment of the present application comprises the steps of forming a hard coating layer on the substrate; And forming a polymer coating layer on the hard coating layer.

The procedure of the manufacturing method of the said optical film was illustrated in FIG. First, after forming a hard coating layer on the substrate, a polymer coating layer is formed on the hard coating layer. By doing so, the protective film is conventionally manufactured through an extrusion process or the like, and then, compared with the conventional art of laminating with a polarizer and introducing a hard coating layer as necessary, a laminating process of a polarizer and a protective film or a hard coating layer on a protective film. Not only can the introduction process be simplified, but manufacturing costs can be greatly reduced.

Since the substrate is to be peeled off after laminating the optical film on one surface of the polarizer, it is not particularly limited as long as it can serve as a support during the manufacturing process of the optical film. The substrate need not be transparent as long as it has mechanical properties and flexibility necessary for the film process to serve as a support. For example, a polyethylene terephthalate (PET) film, a cyclo olefin polymer (COP) film, a PC (polycarbonate) film, a triethylene terephthalate (TAC) film, a polyethersulphone (PES) film, and the like may be used as the substrate. It is not limited only. In addition, a single layer film may be used as the base material, but a release layer may be provided on one surface of the substrate, or one surface may be charged. For example, a release film coated with a release layer on the surface may be used, in which case the film is easily peeled off after lamination. In the case of using the antistatic film, it is possible to minimize the effect on the panel by blocking the static electricity generated during the peeling process after lamination.

The hard coat layer may be used without particular limitation, as long as it can express weather resistance and durability on the surface of the polymer coating layer after peeling the substrate later.

According to one embodiment, the hard coating layer is 1 to 6 functional acrylate-based monomers; It may be formed by a hard coating composition comprising a photocurable elastomer and a photo initiator. Here, formed by the composition means that formed by curing the composition, which can be understood as an expression that includes a cured product of the composition.

According to one embodiment, the hard coating composition is a composition in the form of a solvent (free).

In the present specification, the acrylate-based means not only acrylate but also methacrylate or a derivative in which a substituent is introduced into acrylate or methacrylate.

The 1 to 6 functional acrylate monomers are, for example, hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA). ), Ethylene glycol diacrylate (EGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropaneethoxy triacrylate (TMPEOTA), glycerin propoxylated triacrylate (GPTA), pentaerythritol tetraacrylate (PETA) or dipentaerythritol hexaacrylate (DPHA). The 1 to 6 functional acrylate monomers may be used alone or in combination with each other.

According to one embodiment of the present specification, the 1 to 6 functional acrylate monomers are based on 100 parts by weight of solids including the 1 to 6 functional acrylate monomers, the photocurable elastomer, and the photoinitiator. About 20 to about 79.5 parts by weight, or about 20 to about 49.5 parts by weight. When the 1 to 6 functional acrylate monomer is in the above range, it is possible to form a hard coat layer having good physical properties such as high hardness and scratch resistance.

According to one embodiment, the aforementioned hard coating composition comprises a photocurable elastomeric polymer. Throughout this specification, the photocurable elastomer means a polymer material that exhibits elasticity and includes a functional group capable of crosslinking polymerization by ultraviolet irradiation. According to one embodiment of the present disclosure, the photocurable elastomer is at least about 15%, for example from about 15 to about 200%, or from about 20 to about 200%, or from about 20 to about as measured by ASTM D638. It can have an elongation of 150%.

The photocurable elastomer may be crosslinked with the 1 to 6 functional acrylate-based monomer to impart flexibility and impact resistance to the hard coat layer formed by forming a hard coat layer after curing.

According to one embodiment of the present specification, the weight ratio of the photocurable elastomer and the 1 to 6 functional acrylate monomer may be about 20:80 to about 80:20 or about 20:80 to about 50:50. . When the 1 to 6 functional acrylate-based monomers and the photocurable elastomer are crosslinked and polymerized in the above content ratio, they may form a hard coat layer having good physical properties without deteriorating optical properties while exhibiting sufficient impact resistance.

According to one embodiment of the present disclosure, the photocurable elastomer may be a polymer or oligomer having a weight average molecular weight in the range of about 1,000 to about 600,000 g / mol, or about 10,000 to about 600,000 g / mol.

The photocurable elastomer may be, for example, one or more selected from the group consisting of polycaprolactone, urethane acrylate-based polymers, and polyrotasein.

Among the materials that can be used as the photocurable elastomer, polycaprolactone is formed by ring-opening polymerization of caprolactone and has excellent physical properties such as flexibility, impact resistance, and durability.

The urethane acrylate polymer has excellent elasticity and durability, including urethane bonds.

The polyrotaxane refers to a compound in which a dumbbell shaped molecule and a cyclic compound are structurally sandwiched. The dumbbell shaped molecule includes a constant linear molecule and a blocking group disposed at both ends of the linear molecule, the linear molecule penetrates the interior of the cyclic compound, and the cyclic compound can move along the linear molecule. And the separation is prevented by the blocker.

According to one embodiment of the present specification, a cyclic compound in which a lactone compound having a (meth) acrylate compound introduced therein is bonded; Linear molecules penetrating the cyclic compound; And a rotasein compound disposed at both ends of the linear molecule and including a blocking group to prevent the cyclic compound from being separated.

In this case, the cyclic compound may be used without limitation as long as it has a size enough to penetrate or surround the linear molecule, and may be a hydroxyl group, an amino group, a carboxyl group, a thiol group, or an aldehyde group that may react with another polymer or compound. It may also contain a functional group. Specific examples of such cyclic compounds include α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, or mixtures thereof.

In addition, as the linear molecule, a compound having a straight chain form having a molecular weight of a predetermined or more may be used without great limitation, but a polyalkylene compound or a polylactone compound may be used. Specifically, a polyoxyalkylene compound containing an oxyalkylene repeating unit having 1 to 8 carbon atoms or a polylactone compound having a lactone repeating unit having 3 to 10 carbon atoms may be used.

On the other hand, the blockade group may be appropriately adjusted according to the properties of the rotacein compound to be produced, for example, one selected from the group consisting of dinitrophenyl group, cyclodextrin group, ammantane group, triyl group, fluorescein group and pyrene group or Two or more kinds can be used.

Such polyrotaxane compounds may have excellent scratch resistance and may exhibit self-healing ability when scratches or external damages occur.

In the case of using the above-described hard coating composition, it is possible to impart high hardness and flexibility to the hard coating layer by photocuring including the photocurable elastomer, in particular to prevent damage by external impact to ensure excellent impact resistance.

According to one embodiment of the present specification, the photocurable elastomer has about 20 to about 79.5 parts by weight of 100 parts by weight of the solid containing the 1 to 6 functional acrylate-based monomer, the photocurable elastomer, and the photoinitiator. Parts by weight, or from about 20 to about 49.5 parts by weight. If the content of the photocurable elastomer is too high out of the weight ratio, the physical properties of the hard coat layer may be degraded, such as the occurrence of curl after curing or the scratch resistance decreases. In addition, when the content of the photocurable elastomer is too small, the impact resistance may not be sufficiently achieved.

The hard coating composition of the present specification includes a photoinitiator.

According to an embodiment of the present disclosure, the photoinitiator is 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone, methylbenzoylformate, α-dimethoxy-α-phenylacetophenone, 2-benzoyl-2- (dimethylamino)- 1- [4- (4-morpholinyl) phenyl] -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propane On diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide, or bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and the like. Commercially available products include Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur MBF, Irgacure 819, Darocur TPO, Irgacure 907, and Esacure KIP 100F. These photoinitiators can be used individually or in mixture of 2 or more types different from each other.

According to one embodiment of the present specification, the photoinitiator is about 0.5 to about 10 parts by weight based on 100 parts by weight of the solid content including the 1 to 6 functional acrylate monomer, the photocurable elastomer, and the photoinitiator. Parts, or about 1 to about 5 parts by weight. When the photoinitiator is in the above range, sufficient crosslinking photopolymerization can be achieved without lowering the physical properties of the hard coat layer.

The hard coating composition of the present specification includes an organic solvent.

According to one embodiment of the present specification, the organic solvent may be an alcohol solvent such as methanol, ethanol, isopropyl alcohol, butanol, 2-methoxyethanol, 2-ethoxyethanol, or 1-methoxy-2-propanol. Alkoxy alcohol solvents, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, ketone solvents such as cyclohexanone, propylene glycol monopropyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl Ether solvents such as ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, diethyl glycol monobutyl ether, diethylene glycol-2-ethylhexyl ether , Aromatic solvents such as benzene, toluene, xylene and the like can be used alone or in combination.

According to one embodiment of the present specification, the content of the organic solvent may be variously adjusted within a range that does not lower the physical properties of the hard coating composition of the present disclosure, but is not particularly limited, but the 1 to 6 functional acrylate monomers And a weight ratio of the solid content: organic solvent to 100 parts by weight of the photocurable elastomer and the solid content including the photoinitiator may be in a range of about 70:30 to about 99: 1. By including it in a high content, a high viscosity composition can be obtained, thereby enabling thick coating to form a hard coating layer of high thickness, for example 50 μm or more.

On the other hand, the hard coating composition of the present specification, in addition to the aforementioned 1 to 6 functional acrylate monomers, photocurable elastomers, photoinitiators and organic solvents, surfactants, yellowing agents, leveling agents, antifouling agents, etc. It may further include an additive commonly used in the field. In addition, since the content can be variously adjusted within a range that does not lower the physical properties of the hard coating composition of the present disclosure, it is not particularly limited, for example, about 0.1 to about 10 parts by weight based on 100 parts by weight of the hard coating composition May be included.

According to one embodiment of the present specification, for example, the hard coating composition may include a surfactant as an additive, and the surfactant may be a 1 to 2 functional fluorine acrylate, a fluorine surfactant or a silicone surfactant. . In this case, the surfactant may be included in the form of being dispersed or crosslinked in the crosslinked copolymer.

In addition, a yellowing inhibitor may be included as the additive, and the yellowing inhibitor may include a benzophenone compound or a benzotriazole compound.

According to one embodiment of the present specification, the viscosity of the hard coating composition is not particularly limited as long as it has a proper flowability and applicability, but may exhibit relatively high viscosity. For example, the hard coating compositions herein may have a viscosity of about 100 to about 1,200 cps, or about 100 to about 1,200 cps, or about 150 to about 1,200 cps, or about 300 to about 1,200 cps at a temperature of 25 ° C. Can have.

According to another aspect of the present disclosure, there is provided a hard-coating composition in a solvent-free form including 1 to 6 functional acrylate-based monomers, a photocurable elastomer, and a photoinitiator.

In the non-solvent hard coating composition, specific descriptions of the 1 to 6 functional acrylate-based monomers, photocurable elastomers, photoinitiators, and other additives, exemplary compounds, and contents may be included in the hard coating composition including a solvent. As described above. However, the solvent-free hard coating composition does not include an organic solvent may exhibit a higher viscosity. For example, the hard coating compositions herein may have a viscosity of about 300 to about 1,200 cps, or about 300 to about 1,200 cps, or about 500 to about 1,200 cps, or about 800 to about 1,200 cps at a temperature of 25 ° C. Can have.

The hard coating composition of the present disclosure comprising the above-described components may form a hard coating layer by photocuring after coating on a substrate.

According to one embodiment of the present disclosure, using the hard coating composition of the present disclosure, the thickness is about 50 μm or more, for example, about 50 to about 300 μm, or about 50 to about 200 μm, or about 50 to about 150 μm. Or a hard coat layer having a thickness of about 70 to about 150 μm.

When the hard coat layer is formed using the hard coat composition described above, the hard coat layer may be formed by a conventional method used in the art.

For example, the above-mentioned hard coating composition is first applied onto a substrate. At this time, the method of applying the composition is not particularly limited as long as it can be used in the technical field to which the present technology belongs, for example, bar coating method, knife coating method, roll coating method, blade coating method, die coating method, micro gravure coating A method, a comma coating method, a slot die coating method, a lip coating method, or a solution casting method may be used. Next, the hard coat layer may be formed by irradiating ultraviolet rays to the applied hard coat composition to photocuring the hard coat composition. By using the above-described hard coating composition in the same manner it can form a hard coating layer excellent in impact resistance.

The film including the hard coating layer formed using the hard coating composition of the present specification may exhibit excellent high hardness, impact resistance, scratch resistance, high transparency, durability, light resistance, high transmittance, and the like.

The film including the hard coating layer formed by using the hard coating composition described above may have an impact resistance that is excellent enough to replace the glass. For example, the film including the hard coating layer formed by using the hard coating composition described above may not generate cracks when the 22g iron ball is repeatedly dropped freely 10 times at a height of 50 cm.

In addition, the hard coating layer formed by using the above-described hard coating composition, when the steel wool (0000) in a steel tester (steel wool) # 0000 after the reciprocating 400 times with a load of 500g may occur less than two scratches. .

In addition, the hard coating layer formed using the above-described hard coating composition, the light transmittance may be 91.0% or more, or 92.0% or more, the haze may be 1.0% or less, or 0.5% or less, or 0.4% or less.

In addition, the hard coat layer formed using the above-described hard coating composition, the initial color b value may be 1.0 or less. In addition, the difference between the initial color b value and the color b value after 72 hours or more exposure to an ultraviolet lamp in the UVB wavelength region may be 0.5 or less, or 0.4 or less.

In addition, the hard coating layer formed using the above-described hard coating composition, when exposed to a plane after 70 hours or more at a temperature of 50 ℃ or more and more than 80% humidity, spaced apart from each corner or one side plane of the hard coating layer. The maximum value of the distance can be up to about 1.0 mm, or up to about 0.6 mm, or up to about 0.3 mm. More specifically, when placed in a plane after exposure to a temperature of 50 to 90 ℃ and a humidity of 80 to 90% for 70 to 100 hours, the maximum value of the distance from each corner or one side plane of the hard coating layer is About 1.0 mm or less, or about 0.6 mm or less, or about 0.3 mm or less.

The polymer coating layer may serve as a protective film of the polarizer, and may be used without limitation as long as it is optically transparent and can form a layer by a coating process. Here, optically transparent means that visible light transmittance is 70% or more, preferably 85% or more.

The polymer coating layer may be formed of a thermoplastic resin, and may include, for example, a (meth) acrylic resin or a styrene resin. According to one example, the polymer coating layer may include an ultra high molecular weight styrene acrylonitrile (SAN) resin or an acrylic impact modifier or a block copolymer resin of acrylic and butyl acrylate.

As the ultra high molecular weight styrene acrylonitrile (SAN) resin, a weight average molecular weight (Mw) of 5 million or more, preferably 6 million or more resins may be used, and those known in the art may be used. For example, Blendex 869 resin manufactured by Galata Chemical Co. may be used. As the acrylic impact modifier, a core-shell rubber such as core-shell rubber for PMMA may be used. For example, the acrylic impact modifier includes a methyl methacrylate as a main component in the core, a butyl acrylate and a styrene monomer in the second layer, and a methyl methacrylate as the main component in the outermost layer. Can be. The particle diameter of the acrylic impact modifier may be 100-400 nm.

For example, the polymer coating layer may include an acrylic resin or a methacrylic resin. For example, acrylic resin or methacryl-type resin is not specifically limited, Homo or copolymer of a (meth) acrylic-type monomer; Copolymers of (meth) acrylic monomers and aromatic vinyl monomers; Copolymers of (meth) acrylic monomers, aromatic vinyl monomers and acrylonitrile monomers; Copolymers of (meth) acrylic monomers, aromatic vinyl monomers and acid anhydrides; Or copolymers of acrylic monomers, aromatic vinyl monomers, acrylonitrile monomers and acid anhydrides; Copolymers of alkyl methacrylate monomers, styrene monomers, phenylmaleimide monomers and alkyl acrylate monomers may be used.

In the present specification, the copolymer means that the elements referred to as monomers in the present specification are polymerized to be included as repeating units in the copolymer resin. In the present specification, the copolymer may be a block copolymer or a random copolymer. However, the present invention is not limited thereto. In addition, even when referring to the monomers included in the copolymer herein, it is not limited to including only the monomers mentioned, and comonomers other monomers in addition to the above-mentioned monomers within the scope not departing from the object of the present invention. It may further include.

According to an exemplary embodiment, the (meth) acrylic resin includes a copolymer of an alkyl methacrylate monomer, a styrene monomer, a phenylmaleimide monomer, and an alkyl acrylate monomer. In the case of forming the coating layer using such a copolymer, it is possible to provide a film having excellent heat resistance and optical properties as well as improving the production efficiency by reducing the odor generated during the formation of the coating layer and excellent thermal stability.

 The copolymer may include 70 to 98 parts by weight of alkyl methacrylate monomers, 0.1 to 10 parts by weight of styrene monomers, and 1 to 15 parts by weight of phenylmaleimide monomers, based on 100 parts by weight of the copolymer; And 0.1 to 5 parts by weight of alkyl acrylate monomers.

The alkyl methacrylate monomer may provide high transparency optical properties to the resin composition or the coating layer.

The alkyl moiety of the alkyl methacrylate monomer may be a substituted or unsubstituted alkyl group or a cycloalkyl group, wherein the alkyl moiety preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. It is most preferable that they are a methyl group or an ethyl group. Specifically methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, hydroxyethyl methacrylate, isobornyl methacrylate and cyclohexyl methacrylate At least one selected from the group consisting of, but is not limited thereto.

The content of the alkyl methacrylate monomer is about 70 to 98 parts by weight based on 100 parts by weight of the copolymer, more preferably about 82 to 97 parts by weight. When the content satisfies the above range, a film having excellent optical properties may be obtained, and the birefringence generated during stretching may be minimized.

The styrene-based monomer can be expected to improve the polymerization efficiency between each monomer, the effect of reducing the residual monomer contained in the copolymer produced. In addition, the film produced by the resin composition comprising a copolymer containing a styrene-based monomer can more easily control the stretching retardation can provide a zero retardation film having excellent birefringence.

The styrene monomer may be an unsubstituted styrene monomer or a substituted styrene monomer. The substituted styrene monomer may be styrene substituted with a substituent containing an aliphatic hydrocarbon or hetero atom in a benzene ring or vinyl group. For example, styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 2-methyl-4-chlorostyrene, 2,4,6- Trimethylstyrene, cis-β-methylstyrene, trans-β-methylstyrene, 4-methyl-α-methylstyrene, 4-fluoro-α-methylstyrene, 4-chloro-α-methylstyrene, 4-bromo-α -Methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3,4,5,6-pentafluorostyrene , 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, octachlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromo It may be one or more selected from the group consisting of styrene, 2,4-dibromostyrene, α-bromostyrene and β-bromostyrene, but is not limited thereto. More preferably, styrene substituted with C _1-4 alkyl or halogen can be used. More specifically, the styrene monomer may be used at least one member selected from the group consisting of styrene, α-methyl styrene, p-bromo styrene, p-methyl styrene and p-chloro styrene, most preferably styrene, α-methylstyrene and p-methyl styrene.

The content of the styrene monomer is preferably about 0.1 to 10 parts by weight, and more preferably about 0.5 to 5 parts by weight based on 100 parts by weight of the copolymer. When the content of the styrene-based monomer satisfies the above range, the effect of reducing the residual monomer and the glass transition temperature of the copolymer can be obtained, and the stretching retardation of the film is easily controlled, which is more preferable in terms of optical properties of the film. This is because the effect can be obtained.

The said phenyl maleimide-type monomer can improve the thermal stability and heat resistance of a resin composition and a film, and can improve compounding compatibility with a polycarbonate resin. In addition, unlike the conventional cyclohexyl maleimide, generation of an irritating odor can be suppressed.

In general, maleimide-based residual monomers produce an irritating odor during processing, and may be easily solidified to cause appearance defects in manufacturing an optical film. However, unlike the cyclohexyl maleimide monomer, the phenyl maleide monomer has a constant chemical structure due to the substitution of a phenyl group, and thus it is easy to form a copolymer with an alkyl methacrylate monomer and a styrene monomer, and is heat resistant. It can be improved, and the polymerization time is relatively short advantage. For this reason, the amount of phenylmaleimide-based monomer remaining in the resin after copolymer formation is much lower than that of the cyclohexylmaleimide-based resin, and it is possible to reduce the occurrence of odor during processing caused by the residual monomer.

Specific examples of the phenyl maleimide monomer are selected from the group consisting of phenyl maleimide, nitrophenyl maleimide, monochlorophenyl maleimide, dichlorophenyl maleimide, monomethylphenyl maleimide, dimethylphenyl maleimide, and ethylmethylphenyl maleimide It is preferable that it is at least one.

The content of the phenylmaleimide monomer is preferably about 1 to 15 parts by weight, more preferably about 2 to 10 parts by weight based on 100 parts by weight of the copolymer. When the content of the phenylmaleimide monomer satisfies the above range, the heat resistance of the resin composition or the film is strengthened, mixed well with the polycarbonate resin, and the film can be formed without precipitation.

The said alkyl acrylate type monomer can provide polymerization stability, thermal stability, and toughness to the stretched film to a resin composition. By introducing this structural unit into the copolymer, molding processability such as mold release property is improved, and a composition excellent in heat resistance is obtained, such as preventing weight loss due to heat during the process.

The alkyl moiety of the alkyl acrylate monomer may be a substituted or unsubstituted alkyl group or a cycloalkyl group, wherein the alkyl moiety preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, Most preferably, it is a methyl group or an ethyl group. Specifically, it may be methyl acrylate, ethyl acrylate, isopropyl acrylate n-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, isobornyl acrylate, hydroxymethyl acrylate or hydroxyethyl acrylate. It is not limited to this.

The content of the alkyl acrylate monomer is about 0.1 to 5 parts by weight, and more preferably about 0.5 to 3 parts by weight based on 100 parts by weight of the copolymer. When the content satisfies the above range, it is easy to polymerize between the alkyl methacrylate monomer and the phenylmaleimide monomer at the time of copolymer formation, thereby reducing the residue of phenylmaleimide in the resin composition and occurring during the resin melting process. It is possible to overcome the thermal decomposition phenomenon by the phenyl maleimide, there is an effect that the stretching process is easily carried out by giving toughness when stretching the film.

 According to an exemplary embodiment, the weight ratio of the phenylmaleimide monomer and the alkyl acrylate monomer is preferably about 2: 1 to 10: 1, and more preferably about 2: 1 to 7: 1. When the weight ratio of the two monomers satisfies the above range, the residual monomer content in the copolymer may be reduced.

According to an exemplary embodiment, the polymer coating layer including the (meth) acrylic resin may include a copolymer of an alkyl methacrylate monomer, a styrene monomer, a phenylmaleimide monomer, and an alkyl acrylate monomer, and unreacted phenyl. The content of the maleimide monomer can be prepared using a composition having 30 ppm or less, more preferably 20 ppm or less. In manufacturing, a coating method exemplified as the method of manufacturing the hard coat layer described above may be used. Conventionally, the cyclohexyl maleimide monomer mainly used as a monomer of the copolymer which comprises a heat resistant resin discovered that the cyclohexyl group has a high rotational property and is relatively inferior in polymerization degree. Therefore, not only the amount of monomer remaining in the resin after the copolymer polymerization is high, but also the cyclohexylmaleimide monomer generates an irritating and harmful odor, thereby causing a process problem. However, the phenylmaleimide monomer has an excellent degree of polymerization compared to the cyclohexyl maleimide monomer due to the stable aromatic ring, and the amount of monomer remaining in the copolymer is extremely small, thereby improving the stability of the process.

According to an exemplary embodiment, the polymer coating layer including the (meth) acrylic resin includes a polycarbonate together with a copolymer of an alkyl methacrylate monomer, a styrene monomer, a phenylmaleimide monomer, and an alkyl acrylate monomer. . The polycarbonate is added to adjust the phase difference may be included in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the total resin composition, it is preferably included in about 1 to 5 parts by weight. When the polycarbonate is contained in an amount of 0.1 parts by weight or more, it is possible to prevent a problem in which the thickness direction retardation of the stretched film is increased in a positive direction. The problem of increasing can be prevented, and compatibility with the acrylic resin composition can be good, thereby preventing the whitening phenomenon. Therefore, according to the composition of the above range, the absolute value of the surface direction phase difference R _in defined by the following [Equation 1] and the absolute value of the thickness direction phase difference R _th defined by the following [Equation 2] are respectively 5 nm or less, The content may be adjusted to be preferably 3 nm or less, more preferably 0.

(1) R _in = (n _x -n _y ) xd,

R _th = (n _z -n _y ) xd

In [Formula 1] and [Formula 2],

n _x is the largest refractive index of the in-plane refractive index of the optical film,

n _y is a refractive index in a direction perpendicular to n _x of the in-plane refractive indexes of the optical film,

n _z is the refractive index in the thickness direction,

d is the thickness of the film.

The resin composition comprising the copolymer resin and the polycarbonate resin can be prepared using methods well known in the art, such as, for example, compounding.

According to one embodiment, the glass transition temperature of the copolymer for preparing the polymer coating layer containing the (meth) acrylic resin or the resin composition comprising the same is preferably about 100 ℃ to 150 ℃, 105 ℃ to 140 It is more preferable that it is ° C, and most preferably 110 ° C to 130 ° C. When the glass transition temperature is 100 ℃ or more, it is excellent in heat resistance and can prevent the deformation of the film under high temperature and high humidity conditions, thereby preventing the deformation of the polarizing plate can prevent the non-uniformity of the liquid crystal panel. When the glass transition temperature is 150 ° C. or less, the resin processing characteristics are good, and a coating layer is easily formed due to an appropriate viscosity, thereby improving productivity.

The copolymer of the aforementioned alkyl methacrylate monomer, styrene monomer, phenylmaleimide monomer and alkyl acrylate monomer, or a resin composition comprising the same has excellent thermal stability. Generally, a resin containing an alkyl methacrylate undergoes a zipper decomposition peculiar to a resin containing an alkyl methacrylate at around 260 ° C. It is known that the terminal double bond proceeds as a starting point. On the other hand, the above-mentioned copolymer can reduce molding defect by suppressing thermal decomposition in the vicinity of this 260 degreeC, and can realize manufacture of a stable optical article, without degrading a hue. In this specification, thermal stability can be evaluated using a thermogravimetric analyzer (TGA). For example, in a nitrogen environment, the thermal stability may be evaluated by measuring the temperature at which 2% weight of the resin is reduced in the process of raising the temperature from 30 ° C to 500 ° C at a rate of 10 ° C / min and comparing the temperatures. The 2% weight loss temperature is preferably at least 280 ° C, more preferably at least 300 ° C, most preferably at least 320 ° C.

According to one embodiment, as the (meth) acrylic resin or block copolymer resin, a weight average molecular weight of 1,000 to 2 million, specifically 10,000 to 500,000, as an example can be used a resin of 100,000 to 150,000. The glass transition temperature of the (meth) acrylic resin according to one embodiment is 100 ~ 150 ℃, MI (220 ℃, 10kg) 10 or less, preferably 4 ~ 10, has a characteristic of 0.1 ~ 0.3% of the internal haze. The MI represents the flow rate per minute when pressed at a load of 3.8 kg at 230 ° C. as a measure of the flow of resin.

According to another exemplary embodiment of the present application, the polymer coating layer may further include a ultraviolet absorber as necessary.

In the above embodiment, the ultraviolet absorber may be used one or a mixture of two or more known in the art, for example, benzophenone-based ultraviolet absorber, (benzo) triazole-based ultraviolet absorber, triazine-based ultraviolet absorber and the like Can be. Specific examples include hindered amine light stabilizers such as bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and the like. Can be used. Preferably Tinuvin 328, Tinuvin 321, Tinuvin 326 and Tinuvin 360 can be used. As a heat stabilizer, Igafos 168, Iganox 1076, Iganox 245, etc. may be added. The content of the ultraviolet absorbent may be included in 0.5-10% by weight based on the weight of the polymer coating layer including the same.

In addition, the polymer coating layer may further include various known additives such as an anti-blocking agent, a plasticizer, a lubricant, an impact modifier, an antistatic agent, a stabilizer, an antioxidant, a UV stabilizer, a heat stabilizer, and the like, as necessary. . In this case, the additives may be included in an appropriate content within a range that does not impair the physical properties of the optical film including the polymer coating layer, for example, may be included in about 0.1 to 5 parts by weight based on 100 parts by weight of the entire polymer coating layer.

The polymer coating layer composition may further include a solvent. The solvent is preferably MEK (methyl ethyl ketone), toluene, DAA (Diacetone alcohol), MIBK (methyl isobutyl ketone), ACAC (acetyl acetone), etc. in consideration of factors such as process convenience, odor and price. Do. Solid content concentration in the composition for a polymer coating layer containing a solvent may be 10-30% by weight, preferably 15-25% by weight, such as about 20% by weight.

According to one embodiment, the solvent may include two or more solvents having different boiling points and volatile degrees. For example, a first solvent having a low boiling point and high volatility and a second solvent having a high boiling point and low volatility may be used together. According to one example, the solvent may include MEK (methyl ethyl ketone) as the first solvent and DAA (Diacetone alcohol), MIBK (methyl isobutyl ketone), ACAC (acetyl acetone) as the second solvent. When two kinds of solvents are mixed and used alone, when MEK alone is used, for example, the solvent volatilizes too quickly at the stage before entering the drying oven at about 120 ° C., thereby preventing the problem of solidifying from the T-die inlet. have. The mixing ratio of the first solvent and the second solvent is 8: 2 to 6: 4, preferably about 7: 3. According to an exemplary embodiment of the present application, the thickness variation of the polymer coating layer is 1.5 μm or less, preferably 1 μm or less. For example, the thickness variation of the polymer coating layer may be 0-1.5 μm, for example 0.5-1.5 μm. As described above, by introducing the polymer coating layer by the coating method, the thickness variation is small compared with the conventional extrusion process or melt casting method.

According to an exemplary embodiment of the present application, the thickness of the polymer coating layer is 2 to 40 micrometers. In the past, the protective film having a thickness of more than 40 micrometers was mainly used, but according to the exemplary embodiments of the present application, the polymer coating layer may be introduced thinly, thereby realizing a thinner polarizing plate.

 Another embodiment of the present application is a step of laminating a polymer coating layer of the optical film to the polarizer; And it provides a method for producing a polarizing plate comprising the step of peeling the transparent substrate of the optical film. The schematic diagram of the manufacturing method of a polarizing plate is shown in FIGS. According to FIG. 2, the step of laminating the polymer coating layer 3 of the optical film described above on one surface of the polarizer 4 is illustrated. According to FIG. 3, an additional optical film 5 is provided on the other side of the polarizer 4. The further optical film 5 of FIG. 3 can be laminated to the polarizer before or after or at the same time laminating the optical film comprising the substrate 1, the hard coating layer 2 and the polymer coating layer 3 to the polarizer.

As the polarizer, those known in the art may be used. For example, a polarizer in which an iodine or dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based (hereinafter referred to as PVA) polymer film may be used.

The polarizer and the polymer coating layer of the optical film may be laminated using an adhesive or an adhesive. As the adhesive or pressure-sensitive adhesive may be used those known in the art.

As the additional optical film 5 provided on the other side of the polarizer, one known in the art may be used, for example, triacetate cellulose (TAC) film, acrylic film ring opening metathesis polymerization (ROMP) Polynorbornene-based film, ring opening metathesis polymerization followed by hydrogenation (HROMP) polymer film, polyester film, or polypolymer produced by addition polymerization Norbornene-based films and the like can be used. In addition, a film made of a transparent polymer material may be used as a protective film, but is not limited thereto.

An exemplary embodiment of the present application provides an optical film manufactured by the method described above. 4 illustrates a laminated structure of an optical film according to an example. The optical film according to FIG. 4 includes a substrate 1, a hard coating layer 2 and a polymer coating layer 3.

An exemplary embodiment of the present application provides a polarizing plate manufactured by the method described above. 5 illustrates a laminated structure of a polarizing plate according to an example. The polarizing plate according to FIG. 5 comprises an optical film comprising a substrate 1, a hard coating layer 2 and a polymer coating layer 3, a polarizer 4 and additional optics provided on the polymer coating layer 3 of the optical film. Film 5. 6 further shows an adhesive or adhesive layer 7 provided between the polymer coating layer 3 and the polarizer 4, and an adhesive or adhesive layer 6 provided between the additional optical film 5 and the polarizer 4. Is shown.

Another embodiment of the present application is a polarizer; A polymer coating layer provided on at least one surface of the polarizer; And it provides a polarizing plate comprising a hard coating layer provided on the opposite side of the surface of the polymer coating layer facing the polarizer. Such a polarizing plate can be obtained by peeling the substrate 1 from the polarizing plate produced by the above-described method. At this time, the polymer coating layer provided on one surface of the polarizing plate may have a thickness variation or a thickness range as described above.

An exemplary embodiment of the present application provides a liquid crystal display device including the polarizing plate described above. 7 illustrates a lamination order of the liquid crystal display device. In the liquid crystal display device, the polarizer 4 or the additional optical film 5 of the polarizing plate described above may be disposed close to the liquid crystal panel. The substrate 1 of FIG. 7 may be peeled off after the aforementioned polarizing plate is attached to the liquid crystal panel, or before being attached. When the substrate 1 is peeled off may have a structure as shown in FIG. The polarizing plate may be attached to the liquid crystal panel 8 through a pressure sensitive adhesive (PSA), and those known in the art may be used as the pressure sensitive adhesive.

The liquid crystal display device may include a backlight unit provided on the hard coating layer 2 side. The backlight unit may include an optical film such as a light source, a light guide plate, a light collecting film, or a brightness enhancement film, and may have a configuration known in the art. In other words, in the liquid crystal display device, the optical film including the optical film according to the embodiment of the present application may be provided between the liquid crystal panel and the backlight unit, wherein the hard coating layer is disposed to be close to the backlight unit side. Can be. As such, the hard coating layer of the polarizing plate is provided on the backlight unit side, thereby improving the problem that the polarizing plate is scratched by the components of the backlight unit.

Hereinafter, exemplary embodiments of the present application will be exemplified through examples. The following examples are intended to illustrate the invention of the present application, and the present invention is not intended to be limited by the examples.

< Example  1>

Bar coating the hard coating solution on the PET substrate film and then dried for 2 minutes at 90 ℃ in a Matis oven (Mathis Labdryer Co., Ltd.) and then cured to a strength of 193 mJ in Fusion UV curing machine to obtain a hard coating layer of 3μm thickness.

After adding 2.5 parts by weight of a cationic initiator to 100 parts by weight of glycidyl methacrylate and methyl methacrylate copolymer resin, the bar was coated on the hard coat layer. It was dried at 110 ° C. for 5 minutes and cured at a strength of 193 mJ in a Fusion UV curing machine to obtain a polymer coating layer having a thickness of 20 μm. One surface of the PVA polarizer was laminated with the PET film coated with two layers, and the other surface of the PVA polarizer was laminated with acrylic film, and the polymer coating layer of the two-layer coated PET film was laminated so as to meet the surface of the PVA polarizer. Subsequently, durability evaluation was performed after peeling off a PET film.

< Example  2>

A polarizing plate was manufactured in the same manner as in Example 1, except that MMA-OH double-bonded resin was used instead of the copolymer resin.

< Comparative example >

A polarizing plate was manufactured in the same manner as in Example 1, except that an acrylic resin film (HP202, LGMMA Co., Ltd.) was used instead of the PET film having the coating layer formed thereon.

The results of thermal shock, heat resistance, water resistance, and moisture resistance evaluation of the polarizing plate samples prepared in Examples and Comparative Examples are summarized in Table 1 below.

Thermal shock rating
(-40 ℃ ↔80 ℃,
100 Cycle) 80 ℃ heat resistant
100 hours 60 ℃ / 90%
Heat resistance
100 hours 60 ℃ domestic water
24 hours Example 1 No cracks No cracks Initial Ts 42.5%
After endurance
1.1% increase as 43.6% No blister Example 2 No cracks No cracks Initial Ts 42.4%
After endurance
1.7% increase as 44.1% No blister Comparative example PVA and Acrylic
Crack in film layer
Occurs. PVA and Acrylic
Crack in film layer
Occurs. Initial Ts 43.2%
After endurance
45.2%, an increase of 2.0% Large number of blisters

The thermal shock evaluation, heat resistance evaluation, and water resistance evaluation results of Table 1 are shown in FIG. 9. The heat and moisture resistance evaluation results were not significantly changed in the appearance of the polarizing plate sample, and the optical properties after initial and durability evaluation were evaluated and compared. In the Example, the Ts (group permeability) change rate was less than 2% after passing for 1000 hours at 60 ° C./90% moisture and heat conditions, but the comparative example reached 2% in only 100 hours. Judging.

1: description
2: hard coating layer
3: polymer coating layer
4: polarizer
5: additional optical film
6, 7, 9: adhesive or adhesive layer
8: liquid crystal panel

Claims (13)

Forming a hard coat layer on the substrate; And
Forming a polymer coating layer on the hard coating layer;
The polymer coating layer includes a (meth) acrylic resin,
The (meth) acrylic resin is a method for producing an optical film comprising a copolymer of glycidyl methacrylate and alkyl methacrylate monomers. The method of claim 1, wherein the thickness variation of the polymer coating layer is 1.5 μm or less. The method of claim 1, wherein the polymer coating layer has a thickness of 2 to 40 micrometers. Preparing an optical film by the method of any one of claims 1 to 3;
Laminating the polymer coating layer of the optical film to a polarizer; And
Method of manufacturing a polarizing plate comprising the step of peeling the substrate in the optical film. materials; A hard coating layer provided on the substrate; And a polymer coating layer provided on the hard coating layer,
The polymer coating layer includes a (meth) acrylic resin,
The (meth) acrylic resin is an optical film comprising a copolymer of glycidyl methacrylate and alkyl methacrylate monomers. The optical film of claim 5, wherein the thickness variation of the polymer coating layer is 1.5 μm or less. The optical film of claim 5, wherein the polymer coating layer has a thickness of 2 to 40 micrometers. Polarizer; And an optical film according to any one of claims 5 to 7 provided on at least one surface of the polarizer, wherein the polymer coating layer comprises an optical film disposed adjacent to the polarizer. Polarizer; A polymer coating layer provided on at least one surface of the polarizer; And a hard coating layer provided on an opposite surface of the polymer coating layer to face the polarizer.
The polymer coating layer includes a (meth) acrylic resin,
The (meth) acrylic resin is a polarizing plate comprising a copolymer of glycidyl methacrylate and alkyl methacrylate monomers. The polarizing plate of claim 9, wherein a thickness variation of the polymer coating layer is 1.5 μm or less. The polarizing plate of claim 9, wherein the polymer coating layer has a thickness of 2 to 40 micrometers. Liquid crystal display device comprising the polarizing plate according to claim 8. A liquid crystal display device comprising the polarizing plate according to claim 9.

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