JP6608150B2 - Polarizing plate and image display device including the same - Google Patents

Description

  The present invention relates to a polarizing plate and an image display device including the same. In particular, the present invention relates to a polarizing plate provided with a protective layer and an image display device including the same.

  The liquid crystal display device includes a polarizing plate for blocking transmission of light in a predetermined direction together with the liquid crystal. As a polarizing plate, a structure in which a thermoplastic protective film such as a TAC (triacetyl cellulose) film, a PET (polyethylene terephthalate) film, or an acrylic resin film is attached to both sides of a polarizer using an adhesive, or Retardation film produced using a protective film on one side of the polarizer, an adhesive layer, and a COP (cycloolefin resin) film, TAC film, or PC (polycarbonate) film on the other side Conventionally, a structure in which is attached via an adhesive layer is known.

  In addition, in order to reduce the thickness, weight, and durability of the polarizing plate, a structure in which an adhesive layer is omitted and a protective film is directly formed on a polarizer has been studied. For example, Patent Document 1 proposes a protective layer made of a cured product of a curable resin composition containing an active energy ray-curable compound containing an epoxy compound laminated on one surface of a polarizing film, Patent Document 2 proposes a protective film containing a cured product obtained by polymerizing a photopolymerizable compound including an acrylic compound directly applied to the surface of a polarizer. Patent Document 3 discloses a protective film mainly composed of a cured product of an active energy ray-curable resin composition containing an alicyclic epoxy compound and an acrylic compound provided on at least one side of a polarizing film. Proposed.

  However, the protective film containing a cured product of an epoxy resin proposed in Patent Document 1 and the protective film containing a cured product containing an epoxy resin and an acrylic resin proposed in Patent Document 3 are elastic. There was a problem that the rate was low and cracks of the polarizing film due to heat shrinkage were likely to occur. Moreover, since the protective film containing the hardened | cured material of acrylic resin proposed by patent document 2 has the large shrinkage | contraction at the time of hardening of resin, it says that the adhesiveness with respect to a polarizing film is weak, and the crack of a polarizing film is easy to generate | occur | produce. There was a problem.

Japanese Patent No. 5267920 Japanese Patent No. 4326268 JP 2009-211057 A

  An object of the present invention is to solve the above-described problems, and to provide a polarizing plate provided with a protective layer having good adhesion to a polarizer and high durability, and an image display device including the polarizing plate. And

  According to one embodiment of the present invention, a polarizer and a cured product of a resin composition that is disposed on at least one surface of the polarizer and includes an epoxy resin having an unsaturated bond in a molecule are formed. A polarizing plate containing 30% by mass or more and 85% by mass or less of an epoxy resin having an unsaturated bond in the molecule with respect to the entire resin composition.

  A polarizing plate according to an embodiment of the present invention is a composition in which durability and adhesion of a polarizer are obtained by curing a resin composition containing, as a main component, an epoxy resin having an unsaturated bond in the molecule on at least one surface of the polarizer. It becomes possible to improve the property. Moreover, since the adhesiveness of the protective layer to the polarizer is good, the protective layer can be formed directly on the surface of the polarizer, and it is not necessary to use an adhesive or the like. Therefore, the polarizing plate can be reduced in thickness and weight.

  The resin composition may further include an epoxy compound having no unsaturated bond in the molecule.

  When the resin composition further contains an epoxy compound having no unsaturated bond in the molecule, the viscosity of the resin composition can be diluted, and the protective layer can be easily formed on the polarizer.

  The resin composition may further include a photoacid generator.

  The resin composition can be cured by irradiation with energy rays by including a photoacid generator.

  The protective layer may have a thickness of 25 μm or less.

  When the thickness of the protective layer is 25 μm or less, the reliability and flexibility of the protective layer can be improved.

  According to an embodiment of the present invention, an image display device including any one of the polarizing plates is provided.

  The image display apparatus according to an embodiment of the present invention includes any one of the polarizing plates, thereby improving durability and realizing a long life.

  The polarizing plate according to the present invention includes a protective layer containing an epoxy resin having an unsaturated bond in the molecule on at least one surface of the polarizer, thereby suppressing cracking of the polarizer due to thermal shock and durability. Can be realized. In addition, since the protective layer has good adhesion to the polarizer, it is possible to form the protective layer directly on the surface of the polarizer, and it is not necessary to use an adhesive or the like. Therefore, the polarizing plate according to the present invention can be reduced in thickness and weight.

It is sectional drawing which shows the polarizing plate which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the polarizing plate which concerns on one Embodiment of this invention.

  As a result of diligent investigations to solve the above-mentioned problems, the present inventor has achieved a reduction in thickness, weight, and durability by using an epoxy resin having an unsaturated bond in the molecule as a main component of the resin composition. As a result, the present invention has been completed.

  Hereinafter, a polarizing plate provided with a protective layer according to the present invention and an image display device including the polarizing plate will be described in detail with reference to the drawings. However, the polarizing plate provided with the protective layer of the present invention and the image display device provided with the polarizing plate can be implemented in different modes, and are limited to the description of the embodiments described below. It is not a thing. Note that in the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

  FIG. 1 is a cross-sectional view showing an example of a polarizing plate 100 according to an embodiment of the present invention. As shown in FIG. 1, a polarizing plate 100 is a polarizer 101 and a protective layer for a polarizing plate (hereinafter simply referred to as a “protective layer”) that is attached to the surface of the polarizer 101 and functions as a polarizer protective member. 103 and 105.

There is no restriction | limiting in particular as polarizer polarizer 101, A conventionally well-known thing can be used. For example, dichroic materials such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product.

Resin Composition The protective layers 103 and 105 according to the present invention include an epoxy resin having an unsaturated bond in the molecule. That is, the protective layer according to the present invention is a cured product of a resin composition containing an epoxy resin having an unsaturated bond in the molecule. In the resin composition according to the present invention, in order to achieve high durability, an epoxy resin having an unsaturated bond in the molecule is preferably contained as a main component of the resin composition. The content of the epoxy resin having an unsaturated bond in the molecule is preferably 30% by mass or more and 85% by mass or less, and preferably 35% by mass or more and 80% by mass or less with respect to the entire resin composition from the viewpoint of the cured film elastic modulus and the like. Is more preferable, and 40 mass% or more and 80 mass% or less are especially preferable.

  The epoxy resin having an unsaturated bond in the molecule to be contained in the resin composition according to the present invention includes a double bond in the chain of a diene homopolymer such as butadiene or isoprene, or a copolymer of an alkene such as diene or ethylene. Examples include epoxidized resins. As an epoxy resin which has an unsaturated bond in the molecule | numerator contained in the resin composition which concerns on this invention, a butadiene-type epoxy resin is preferable. Examples of butadiene-based epoxy resins include liquid epoxidized polybutadiene (terminal OH group) (Epolide (registered trademark) PB3600 [EPL PB3600], Daicel), 1,2-polybutadiene (JP-100, 200, Nippon Soda), epoxy Examples include, but are not limited to, modified polybutadiene (Ricon (registered trademark) 657, CRAY VALLEY), BF-1000 (ADEKA), R-45EPT (Nagase ChemteX).

More preferable butadiene-based epoxy resins include, for example, compounds represented by the following chemical formula (1), but are not limited thereto.

Here, in Formula (1), m is 3 or more and 15 or less, and n is 5 or more and 40 or less.

  The protective layer according to the present invention is formed by polymerizing a resin composition containing an epoxy resin having an unsaturated bond in the molecule represented by the formula (1).

  The resin composition further contains a resin having no unsaturated bond in the molecule from the viewpoint of improving the photoreactivity and diluting the viscosity of the resin composition. The content of the resin having no unsaturated bond in the molecule is preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, and more preferably 20% by mass or more with respect to the entire resin composition. 40 mass% or less is especially preferable. It may be. The resin having no unsaturated bond in the molecule is not particularly limited, and examples thereof include aliphatic epoxy resins and alicyclic epoxy resins.

  Examples of the aliphatic aliphatic epoxy resins include aliphatic polyhydric alcohols and polyglycidyl ether compounds of alkylene oxide adducts thereof, such as 1,4-butanediol diglycidyl ether and 1,6-hexanediol diglycidyl ether. , Diethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane diglycidyl ether, polyethylene glycol diglycidyl ether Although ether etc. are mentioned, it is not limited to these.

  Examples of alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1,2: 8,9 diepoxy limonene, 1,2-epoxy-4-vinylcyclohexane, and the like. Although it is mentioned, it is not limited to these.

  In addition to the epoxy resin having an unsaturated bond in the molecule and the epoxy resin having no unsaturated bond in the molecule, the resin composition of the protective layer according to the present invention includes other resins, photoacid generators (light A cationic polymerization initiator), a photosensitizer, and the like.

As the photoacid generator , a conventionally known photoacid generator can be used without particular limitation. Specific examples include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes, but are not limited thereto. These may be used alone or in combination of two or more.

  Examples of the aromatic diazonium salt include, but are not limited to, benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, and the like.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di (4-nonylphenyl) iodonium hexafluorophosphate. It is not limited to.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate, 4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4'-bis [Di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxa N-ton hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (P-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis Examples thereof include, but are not limited to, (pentafluorophenyl) borate and diphenyl [4- (phenylthio) phenyl] sulfonium phosphate.

  Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) -tris. Examples thereof include (trifluoromethylsulfonyl) methanide, but are not limited thereto.

  Commercially available photoacid generators may be used. For example, CPI-100P, 101A, 200K, 210S (manufactured by Sun Apro Co., Ltd.), Kayrad (registered trademark) PCI-220, PCI-620 (manufactured by Nippon Kayaku Co., Ltd.) ), UVI-6990 (Union Carbide), Adekaoptomer SP-150, SP-170 (ADEKA), CI-5102, CIT-1370, 1682, CIP-1866S, 2048S, 2064S, (Nippon Soda) Co., Ltd.), DPI-101, 102, 103, 105, MPI-103, 105, BBI-101, 102, 103, 105, TPS-101, 102, 103, 105, MDS-103, 105, DTS-102 , 103 (manufactured by Midori Chemical Co., Ltd.), PI-2074 (manufactured by Rhodia Japan Co., Ltd.), and the like, but are not limited thereto.

  In addition, from the viewpoint of preventing a decrease in the resin composition curability after irradiation with active energy rays, and a decrease in durability, the content of the photoacid generator is based on the entire resin composition forming the protective layer. It is preferably 0.11% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, and particularly preferably 1% by mass or more and 8% by mass or less.

Photosensitizer The resin composition forming the protective layer of the present invention contains a photosensitizer, whereby the reactivity of cationic polymerization is improved, and the mechanical strength and adhesiveness of the resin composition of this embodiment are improved. Can be improved.

  Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes, and more specifically, benzoin methyl ether. Benzoin derivatives such as benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4′-bis (dimethylamino) benzophenone, 4, Benzophenone derivatives such as 4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone; N-methylacrylic Examples thereof include, but are not limited to, acridone derivatives such as dong and N-butylacridone; and α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, halogen compounds and the like.

  In addition, from the viewpoint of improving curability and weather resistance, the content of the photosensitizer is preferably 0% by mass or more and 5% by mass or less, and 0% by mass with respect to the entire resin composition forming the protective layer. % To 3% by mass is particularly preferable.

Resin having a photopolymerizable functional group other than an epoxy group The protective layer according to the present invention may contain a resin having a photopolymerizable functional group other than an epoxy group. That is, the resin composition forming the protective layer according to the present invention may further contain a resin having a photopolymerizable functional group other than the epoxy group. By containing such a resin, photoreactivity can be further improved, and the viscosity of the resin composition can be easily diluted.

  Examples of the resin having a photopolymerizable functional group other than an epoxy group include oxetane resins and vinyl ether resins that are cationically polymerizable compounds, acrylic resins that are radically polymerizable compounds, and the like.

The oxetane resin is not particularly limited as long as it has at least one oxetanyl group in the molecule. For example, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- Phenoxymethyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-[(3-ethyloxetane-3-yl) methoxymethyl] oxetane, 1,4-bis [(3-ethyloxetane-3- Yl) methoxymethyl] benzene, 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,2 -Bis [(3-ethyloxetane-3-yl) methoxy] benzene, 4,4′-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,2′-bis [(3-ethyloxeta -3-yl) methoxy] biphenyl, 3,3 ′, 5,5′-tetramethyl-4,4′-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,7-bis [( 3-ethyloxetane-3-yl) methoxy] naphthalene, bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] methane, bis [2-{(3-ethyloxetane-3-yl) methoxy } Phenyl] methane, 2,2-bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] propane, and etherification modification of novolac phenol-formaldehyde resin with 3-chloromethyl-3-ethyloxetane 3 (4), 8 (9) -bis [(3-ethyloxetane-3-yl) methoxymethyl] -tricyclo [5.2.1.0 ^2,6 ] decane, 2,3-bis [(3-ethyloxetane -3-yl) methoxymethyl] norvo Lunan, 1,1,1-tris [(3-ethyloxetane-3-yl) methoxymethyl] propane, 1-butoxy-2,2-bis [(3-ethyloxetane-3-yl) methoxymethyl] butane, 1,2-bis [{2- (3-ethyloxetane-3-yl) methoxy} ethylthio] ethane, bis [{4- (3-ethyloxetane-3-yl) methylthio} phenyl] sulfide, 1,6- Bis [(3-ethyloxetane-3-yl) methoxy] -2,2,3,3,4,4,5,5-octafluorohexane, 3-[(3-ethyloxetane-3-yl) methoxy] Examples thereof include, but are not limited to, resins having hydrolytic condensates of propyltriethoxysilane, tetrakis [(3-ethyloxetane-3-yl) methyl] silicate, and the like in the skeleton.

  As the acrylic resin, conventionally known acrylic resins can be used without particular limitation as long as they exhibit radical polymerizability. Typical examples include resins having (meth) acryloyl group, (meth) acrylamide group, etc. in the skeleton, (meth) acrylic acid and derivatives thereof, (meth) acrylonitrile, (meth) acrylamide and derivatives thereof. However, it is not limited to these. These resins may be used alone or in combination of two or more.

  More specifically, examples of the acrylic resin include (meth) acrylic acid and salts thereof. That is, methyl (meth) acrylate, ethyl (meth) acrylate, methylphenoxyethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) Acrylate, pentyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylate, 2-methoxyethyl (meth) acrylate, (meth) acrylate, 2-hydroxy Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, 3-chloro -2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, ethylene glycol di (meth) acrylate, phenoxyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, phenoxydiethylene glycol ( (Meth) acrylate, triethylene glycol di (meth) acrylate, phenoxytriethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, dipropylene Glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylol Methane tri (meth) acrylate, isobornyl (meth) acrylate, N-vinylpyrrolidone, acryloylmorpholine, urethane (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrahydrofurfuryl alcohol mono-ε-caprolactone adduct (meta ) Addition of mono-β-methyl-δ-valerolactone to (meth) acrylate and tetrahydrofurfuryl alcohol of di-ε-caprolactone adduct of acrylate and tetrahydrofurfuryl alcohol (Meth) acrylates, (meth) acrylate compounds such as (meth) acrylates and ω-carboxy-polycaprolactone monoacrylates of diβ-methyl-δ-valerolactone adducts of tetrahydrofurfuryl alcohol; acrylonitrile, methacrylate Nitrile group-containing vinyl compounds such as rhonitrile; and (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N- Butyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N- (hydroxyethyl) acrylamide, N-isopropyl ( Meta) Examples include resins having amide group-containing vinyl compounds such as rilamide, N-methylol (meth) acrylamide, diacetone (meth) acrylamide, and N, N-methylenebis (meth) acrylamide in the skeleton, but are not limited thereto. It is not a thing.

  Among these, from the viewpoint of excellent initial curability as a resin composition for forming a protective layer and improving adhesiveness with a polarizer, at least one of a hydroxy group-containing acrylic monomer and a phenoxy group-containing acrylic monomer is More preferably, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, methylphenoxyethyl (meth) acrylate and phenoxydiethylene glycol (meth) acrylate, and 2-hydroxy-3-phenoxypropyl acrylate are more preferable. .

  Examples of the vinyl ether resin include resins having diethylene glycol divinyl ether, triethylene glycol divinyl ether, cyclohexyl vinyl ether, polyethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether in the skeleton, but are not limited thereto. is not. Of these, triethylene glycol divinyl ether and cyclohexyl vinyl ether are particularly preferable from the viewpoint of availability and handling.

  In addition, from the viewpoint of improving curability and weather resistance, the content of the resin having a photopolymerizable functional group other than an epoxy group is 0% by mass or more and 60% by mass with respect to the entire resin composition forming the protective layer. % By mass or less is preferable, and 0% by mass or more and 35% by mass or less is particularly preferable.

Method for Producing Resin Composition for Protective Layer The method for producing the resin composition for the protective layer according to the present invention is not particularly limited, and is usually an epoxy resin having an unsaturated bond in the molecule, and in the molecule. A resin composition can be obtained by mixing an epoxy compound having no unsaturated bond, a resin monomer having a photopolymerizable functional group other than an epoxy group, a photoacid generator, and a photosensitizer. In addition, you may use an organic solvent suitably for viscosity adjustment. Moreover, there is no restriction | limiting in particular also in the mixing method, What is necessary is just to stir and mix sufficiently until it becomes uniform at room temperature (25 degreeC).

2. Manufacturing method of polarizing plate With reference to FIG. 2, the manufacturing method of the polarizing plate provided with the protective layer which concerns on this invention is demonstrated. As shown in FIG. 2, first, the polarizer 201 is sandwiched between the PET film 203 and the PET film 205, and the obtained resin composition 207 for the protective layer is placed between the PET film 203 and the polarizer 201. In addition, an appropriate amount is dropped with a dropper between the PET film 205 and the polarizer 201, and bonded by roll presses 209 and 201. In addition, as PET film 203,205, a commercial item (for example, Toray Industries, Inc. thickness: 50 micrometers) can be used.

Next, 300 to 3000 mJ / cm ² , preferably 500 to 2000 mJ / cm ² , more preferably 800 to 1500 mJ / cm ² (based on 356 nm, metal halide) 1 is used, and the PET films 203 and 205 are peeled off to produce the polarizing plate 100 with the protective layers 103 and 105 shown in FIG.

  In FIG. 1, the protective layers 103 and 105 are provided on both sides of the polarizer 100 and the polarizer 101 is sandwiched between the protective layers 103 and 105. However, the protective layer 103 or 105 is provided only on one side of the polarizer 101. It is good also as a structure which provides.

  In addition, from the viewpoint of improving reliability and flexibility, the resin composition is preferably applied so that the thickness of the protective layer 103 after curing is 25 μm or less, and is applied so as to be 15 μm or less. More preferably.

  The protective layer according to the present invention contains an epoxy resin having an unsaturated bond in the molecule obtained by curing a resin composition containing an epoxy resin having an unsaturated bond in the molecule. The polarizing plate which concerns on this invention can suppress the thermal contraction of a polarizer by providing the protective layer which concerns on this invention on at least one surface of a polarizer. As a result, the polarizer can be prevented from cracking due to thermal shock, and a polarizing plate having excellent durability can be realized. In addition, since the protective layer according to the present invention has good adhesion to the polarizer, the protective layer can be formed directly on the surface of the polarizer. Therefore, it is not necessary to use an adhesive. Therefore, the polarizing plate of the present invention can be reduced in thickness and weight.

  The polarizing plate according to the present invention can be used in an image display device such as a liquid crystal display device. For example, a polarizing plate provided with the protective layer according to the present invention on both surfaces of a polarizer may be applied to an IPS liquid crystal display device. Further, a polarizing plate provided with the protective layer according to the present invention may be applied to at least one surface of a polarizer in a VA liquid crystal display device. Since the image display device according to the present invention includes a polarizing plate with improved durability, it is possible to achieve a long life.

  Hereinafter, the polarizing plate according to the present invention will be described based on Examples 1 to 4 and Comparative Examples 1 to 3.

<Example 1>
Preparation of Resin Composition JP-100 (Nippon Soda Co., Ltd.) is 80% by mass as an epoxy resin having an unsaturated bond in the molecule, and Cel3000 (Daicel Co., Ltd.) is 20% by mass as an epoxy resin having no unsaturated bond. %, 4% by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator (photo cationic polymerization initiator), and 0.5% by mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer % To prepare a resin composition.

Production of Polarizer A polarizer was produced by the following method. A polyvinyl alcohol film having an average polymerization degree of 2400, a saponification degree of 99.9%, and a thickness of 75 μm was immersed in warm water at 28 ° C. for 90 seconds to swell, and then a concentration of iodine / potassium iodide (weight ratio 2/3) was 0. A polyvinyl alcohol film was dyed while being immersed in a 6% by weight aqueous solution and stretched 2.1 times. Thereafter, the film was stretched in a 60 ° C. boric acid ester aqueous solution so that the total stretching ratio was 5.8 times, washed with water, and then dried at 45 ° C. for 3 minutes to produce a polarizer (thickness 25 μm). .

Production of Polarizing Plate Next, using the polarizer produced as described above and the prepared resin composition in a temperature-controlled room at room temperature (25 ° C.) and humidity 50% RH, and by the method for producing a polarizing plate described above. A polarizing plate was prepared. The ultraviolet irradiation conditions are 1000 mJ / cm ² (365 nm standard, using a metal halide lamp) from both sides, and after ultraviolet irradiation, the polarizing plate is stored in the above-mentioned constant temperature room for 24 hours, and the resin composition is aged and cured, A polarizing plate was completed. The thickness of one surface of the protective layer was 10 to 15 μm. The protective layer was formed on both sides of the polarizer.

<Example 2>
JP-100 (manufactured by Nippon Soda Co., Ltd.) is used as an epoxy resin having an unsaturated bond in the molecule.
35% by mass of EX214L (manufactured by Nagase ChemteX Corporation) and 5% by mass of EX141 (manufactured by Sechemtex Co., Ltd.) as an epoxy resin having no unsaturated bond, and CPI100-P (San Apro Co., Ltd.) as a photoacid generator 4% by mass) and 0.5% by mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer were mixed to prepare a resin composition. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Example 3>
40% by mass of JP-100 (manufactured by Nippon Soda Co., Ltd.) as an epoxy resin having an unsaturated bond in the molecule, 20% by mass of EX214L (manufactured by Nagase ChemteX Corporation) as an epoxy resin having no unsaturated bond, and Cel2021P 20% by mass (manufactured by Daicel Corporation), 20% by mass of OXT-221 (manufactured by Toagosei Co., Ltd.) as the other resin monomer, 4% by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as the photoacid generator, And DETX-S (made by Nippon Kayaku Co., Ltd.) 0.5 mass% was mixed as a photosensitizer, and the resin composition was prepared. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Example 4>
JP-100 (manufactured by Nippon Soda Co., Ltd.) is 60% by mass as an epoxy resin having an unsaturated bond in the molecule, EX214L (manufactured by Nagase ChemteX Corporation) is 20% by mass as an epoxy resin having no unsaturated bond, and others. 20% by mass of OXT-121 (manufactured by Toagosei Co., Ltd.), 4% by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator, and DETX-S (Nippon Kayaku Co., Ltd.) as a photosensitizer A resin composition was prepared by mixing 0.5% by mass. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Examples 5 to 8>
Polarizers were changed, and polarizing plates of Examples 5 to 8 were produced using the resin compositions of Examples 1 to 4.

Production of Polarizer A polarizer was produced by the following method. A film containing an acid catalyst having a dehydrating action on polyvinyl alcohol having an average polymerization degree of 1500 or more and 2800 or less, a saponification degree of 99.9%, and a thickness of 18 μm is uniaxially stretched in an oven at 130 ° C. or higher 5 times or more and then dehydrated. Made progress. Stretching was performed in an aqueous boric acid solution at 85 ° C. or higher so that the total draw ratio was 6 times or more, washed with water, and then dried at 60 ° C. or higher for 5 minutes to prepare a polyene polarizer (thickness 10 μm). .

Production of Polarizing Plate Using the obtained polyene polarizer, the polarizing plate of Examples 5 to 8 is completed by aging and curing the resin compositions of Examples 1 to 4 in the same manner as in Example 1. I let you. The thickness of one surface of the protective layer was 10 to 15 μm. The protective layer was formed on both sides of the polarizer.

<Comparative Example 1>
JP-100 (manufactured by Nippon Soda Co., Ltd.) is 25% by mass as an epoxy resin having an unsaturated bond in the molecule, Cel3000 (manufactured by Daicel Corporation) is 30% by mass as an epoxy resin having no unsaturated bond, and Cel2021P (stock) 25% by weight (made by Daicel Co., Ltd.), 20% by weight OXT-221 (made by Toagosei Co., Ltd.) as the other resin monomer, 4% by weight CPI100-P (made by San Apro Co., Ltd.) as the photoacid generator, and light A resin composition was prepared by mixing 0.5% by mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a sensitizer. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Comparative Example 2>
No epoxy resin having an unsaturated bond in the molecule is added, Cel2021P (manufactured by Daicel Corporation) is 35% by mass as an epoxy resin having no unsaturated bond, and OXT-221 (manufactured by Toagosei Co., Ltd.) as another resin monomer. ) 15% by mass and A-DOG (manufactured by Shin-Nakamura Chemical Co., Ltd.) 50% by mass, CPI100-P (manufactured by San Apro Co.) as a photopolymerization initiator 2.5% by mass and Irg184 (manufactured by BASF) A resin composition was prepared by mixing 2.5% by mass. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Comparative Example 3>
75% by mass of Cel2021P (manufactured by Daicel Corporation) is used as an epoxy resin having no unsaturated bond without adding an epoxy resin having an unsaturated bond in the molecule, and OXT-221 (manufactured by Toagosei Co., Ltd.) as another resin monomer. ), 25% by mass, 4% by mass of CPI100-P (manufactured by San Apro Co., Ltd.) and 1% by mass of Irg184 (manufactured by BASF) as a photopolymerization initiator were mixed to prepare a resin composition. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Comparative Examples 4-6>
The polarizers of Comparative Examples 4 to 6 were completed by aging and curing the resin compositions of Comparative Examples 1 to 3 in the same manner as in Example 1 using the same polarizers as in Examples 5 to 8. It was. The thickness of one surface of the protective layer was 10 to 15 μm. The protective layer was formed on both sides of the polarizer.

(Adhesion test)
Glass was bonded to one protective layer side of the polarizing plate prepared in Examples 1 to 8 and Comparative Examples 1 to 6 via a pressure-sensitive adhesive, and a cutter knife was applied to the protective layer surface of the polarizing plate on the side opposite to the glass surface. The test was performed by cutting 100 square grids of 1 mm square and applying cellophane tape to them, and then peeling off, and the adhesion was evaluated by the number of grids remaining without the protective layer being peeled off from the polarizer. . The case where the number of remaining grids was 100/100 was evaluated as ◯, the case of 80 to 99/100 was evaluated as Δ, and the case of less than 80/100 was evaluated as ×.

(Hot water immersion test)
The polarizing plates produced in Examples 1 to 8 and Comparative Examples 1 to 6 were cut into a size of 50 mm × 50 mm with a Thomson blade, immersed in a water bath at 60 ° C., and held for 2 hours. Then, each sample was taken out from the water tank and the magnitude | size of the shrinkage | contraction of a polarizer was measured. As an evaluation standard, a size of shrinkage of less than 1.0 mm was accepted. The evaluation results are shown in Table 2 below. A preferable result is 0.5 mm or less, more preferably 0.3 mm or less, and particularly preferably 0 mm.

(Heat resistance test)
The polarizing plates produced in Examples 1 to 8 and Comparative Examples 1 to 6 were cut into a size of 50 mm × 50 mm with a Thomson blade and bonded to glass via a pressure sensitive adhesive. The produced polarizing plate with glass was left in an environment of 85 ° C. for 500 hours, and then cracking of the polarizer was confirmed. When there was no crack of the polarizer, it was evaluated as ◯, and when there was a crack, it was evaluated as x.

(Thermal shock test)
The polarizing plates produced in Examples 1 to 8 and Comparative Examples 1 to 6 were cut into a size of 50 mm × 50 mm with a Thomson blade and bonded to glass via a pressure sensitive adhesive. The produced polarizing plate with glass was left in an environment of −40 ° C. to 85 ° C. for 200 cycles, and then cracking of the polarizer was confirmed. When there was no crack of the polarizer, it was evaluated as ◯, and when there was a crack, it was evaluated as x.

Tables 1 and 2 below show the evaluation and results of the adhesion test, hot water immersion test, heat resistance test, and thermal shock test.

  With reference to the evaluation of the adhesion test, in any polarizing plate of Examples 1 to 8, the adhesion between the protective layer and the polarizer according to the present invention was good. In particular, the adhesiveness between the protective layer and the polarizer of Examples 1 to 8 in which the content of the epoxy resin having an unsaturated bond in the molecule in the resin composition was 30% by mass or more was good.

  Referring to the results of the hot water immersion test, in the polarizing plates of Comparative Examples 1 to 6, the shrinkage of the polarizer exceeded 0.5 mm, whereas in the polarizing plates of Examples 1 to 8, the shrinkage of the polarizer was any. Was also 0.5 mm or less. Therefore, in the polarizing plate which concerns on this invention, it turns out that shrinkage | contraction of a polarizer was suppressed compared with the comparative example, and durability was improved.

  Referring to the results of the heat resistance test, the polarizers of Comparative Examples 1 to 6 were confirmed to have cracks in the polarizer, whereas the polarizers of Examples 1 to 8 were not confirmed to have cracks in the polarizer. Therefore, it can be seen that in the polarizing plate according to the present invention, the shrinkage of the polarizer due to heat can be suppressed, and the durability is improved.

  Referring to the results of the thermal shock test, in the polarizing plates of Comparative Examples 1 to 6, cracking of the polarizer was confirmed, whereas in the polarizing plates of Examples 1 to 8, cracking of the polarizer was not confirmed. . Therefore, it can be seen that the polarizing plate according to the present invention can suppress the shrinkage of the polarizer at low temperature and high temperature, and the durability is improved.

  As can be seen from the evaluations and results of the tests of the polarizing plates of Examples 1 to 8 and Comparative Examples 1 to 6 described above, the polarizing plate provided with the protective layer according to the present invention is excellent in adhesiveness and durability. ing. Therefore, the polarizing plate according to the present invention can be suitably used for an image display device such as a liquid crystal display device.

100: Polarizing plate 101: Polarizer 103: Protective layer 105: Protective layer 201: Polarizer 203: PET film 205: PET film 207: Resin composition 209: Roll press 2011: Roll press

Claims (6)

A polarizer,
A protective layer formed on a cured product of a resin composition, which is disposed on at least one surface of the polarizer and contains an epoxy resin having an unsaturated bond in the molecule;
Including
Containing 30% by mass or more and 85% by mass or less of an epoxy resin having an unsaturated bond in the molecule with respect to the entire resin composition ;
The polarizing plate characterized in that the epoxy resin having an unsaturated bond in the molecule is selected from a resin obtained by epoxidizing a double bond in a chain of a diene homopolymer or an alkene copolymer . The polarizing plate according to claim 1, wherein the epoxy resin having an unsaturated bond in the molecule is a compound represented by the following chemical formula.

(In the chemical formula, m is 3 or more and 15 or less, and n is 5 or more and 40 or less.) The resin composition, polarizer according to claim 1 or 2, further comprising a no epoxy compound an unsaturated bond in the molecule. The resin composition polarizing plate according to any one of claims 1 to 3, further comprising a photoacid generator. The polarizing plate according to any one of claims 1 to 4, wherein the thickness of the protective layer is 25μm or less. An image display device characterized by comprising a polarizing plate according to any one of claims 1 to 5.