JP2016085369A - Polarizing plate and image display device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate which has excellent adhesiveness to a polarizer and includes a protective layer having high durability; and an image display device including the polarizing plate.SOLUTION: A polarizing plate includes: a polarizer; and a protective layer which is arranged on at least one surface of the polarizer and is formed of a cured product of a resin composition containing an aromatic epoxy compound. The protective layer contains a rigid aromatic epoxy resin obtained by curing the resin composition containing the aromatic epoxy compound, and thereby can achieve high elastic modulus and high durability and can improve adhesiveness to the polarizer.SELECTED DRAWING: Figure 1

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 mainly composed of an aromatic epoxy resin 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, an acrylic resin film is attached to both sides of a polarizer using an adhesive, or The protective film is attached to one side of the polarizer via an adhesive layer, and the other side is bonded to a retardation film made using COP (cycloolefin resin) film, TAC film, PC (polycarbonate) film, etc. A structure pasted through an agent layer is conventionally 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, a protective film containing a cured product of an epoxy resin proposed in Patent Document 1 and a protective film containing a cured product including an epoxy resin and an acrylic resin proposed in Patent Document 3 are elastic. The rate was low, and there was a problem that the polarizing film was easily cracked by heat shrinkage. 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

  Accordingly, the present invention solves the above-described problems, and provides a polarizing plate provided with a protective layer having good adhesion to a polarizer and having high durability, and an image display device including the polarizing plate. With the goal.

  According to one embodiment of the present invention, a polarizer and a protective layer disposed on at least one surface of the polarizer and formed of a cured product of a resin composition containing an aromatic epoxy compound are included. A polarizing plate is provided.

  The polarizing plate according to one embodiment of the present invention includes a protective layer containing a rigid aromatic epoxy resin obtained by curing a resin composition containing an aromatic epoxy compound on at least one surface of a polarizer. Elastic modulus and high durability can be realized, and thermal contraction of the polarizer can be suppressed. 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 aromatic epoxy compound may be a compound represented by the following general formula (1).

  When the said aromatic epoxy compound contains the compound represented by General formula (1), high elastic modulus of a protective layer is realizable.

  The resin composition may include an aromatic epoxy compound as a main component, and the aromatic epoxy compound may be contained in an amount of 40% by mass to 90% by mass with respect to the entire resin composition.

  When the resin composition contains an aromatic epoxy compound as a main component, the protective layer obtained by curing the resin composition contains an aromatic epoxy resin as a main component, thereby realizing further high elastic modulus. Therefore, the thermal contraction of the polarizer can be further suppressed, and the durability of the polarizing plate can be further improved.

  The resin composition may further include an epoxy compound having no aromatic ring.

  When the resin composition further contains an epoxy compound having no aromatic ring, 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 contain a photocationic polymerization initiator.

  A polarizing plate having a high elastic modulus and high durability and capable of suppressing thermal contraction of the polarizer can be realized.

  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, whereby durability is improved and a long life can be realized.

  The polarizing plate which concerns on this invention is equipped with the protective layer containing an aromatic epoxy resin on at least one surface of a polarizer, and the thermal contraction of a polarizer is suppressed. 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 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 intensive studies to solve the above-mentioned problems, the present inventor has realized a reduction in thickness, weight, and durability by using an aromatic epoxy resin having a rigid skeleton as the 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. In particular, a polarizer produced by dyeing a polyvinyl alcohol film having an average polymerization degree of 2000 or more and 2800 or less and a saponification degree of 90 mol% or more and 100 mol% or less with iodine and stretching it uniaxially 5 to 6 times is preferable. More specifically, such a polarizer can be obtained by, for example, immersing and stretching a polyvinyl alcohol film by immersing it in an aqueous iodine solution. As the iodine aqueous solution, for example, an aqueous solution of 0.1% by mass to 1.0% by mass of iodine / potassium iodide is preferable. If necessary, it may be immersed in an aqueous solution such as boric acid or potassium iodide at 50 to 70 ° C., or may be immersed in water at 25 to 35 ° C. in order to prevent washing or uneven dyeing. Stretching may be performed after dyeing with iodine, may be stretched while dyeing, or may be dyed with iodine after stretching. After dyeing and stretching, it may be washed with water and dried at 35 to 55 ° C. for about 1 to 10 minutes.

Resin Composition The protective layers 103 and 105 according to the present invention include an aromatic epoxy resin. That is, the protective layer according to the present invention is a cured product of a resin composition containing an aromatic epoxy compound. In the resin composition according to the present invention, the aromatic epoxy compound is preferably contained as a main component of the resin composition in order to achieve high durability. The content of the aromatic epoxy compound is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 85% by mass or less, and more preferably 60% by mass with respect to the entire resin composition from the viewpoint of the cured film elastic modulus and the like. % To 80% by mass is particularly preferable. The aromatic epoxy compound is preferably an epoxy compound having two or more aromatic rings in the molecule and having two or more functions. In particular, the aromatic epoxy compound is preferably diglycidyl ether having a naphthalene skeleton.

That is, the aromatic epoxy compound may be, for example, a compound represented by the following chemical formula (1).

  The protective layer according to the present invention is produced by polymerizing a resin composition containing a resin monomer that is an aromatic epoxy compound such as diglycidyl ether having a naphthalene skeleton represented by chemical formula (1).

  The resin composition further contains an epoxy compound having no aromatic ring from the viewpoint of improving photoreactivity and diluting the viscosity of the resin composition. The content of the epoxy compound having no aromatic ring is preferably 10% by mass to 60% by mass, more preferably 20% by mass to 50% by mass, and more preferably 20% by mass to 40% by mass with respect to the entire resin composition. % Or less is particularly preferable. It may be. The epoxy compound which does not have an aromatic ring is not specifically limited, For example, an aliphatic epoxy resin monomer and an alicyclic epoxy resin monomer are mentioned.

  Examples of the aliphatic epoxy resin monomer 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 Examples include ether.

  Alicyclic epoxy resin monomers include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1,2: 8,9 diepoxy limonene, 1,2-epoxy-4-vinylcyclohexane, etc. Is mentioned.

  In addition to the aromatic epoxy compound and the epoxy compound having no aromatic ring, the resin composition of the protective layer according to the present invention includes other resin monomers, a photoacid generator (photocation polymerization initiator), and light. A sensitizer and the like may be included.

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. These may be used alone or in combination of two or more.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  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 (Pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium phosphate, and the like.

  Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) -tris. And (trifluoromethylsulfonyl) methanide.

  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.

  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. 0.1 mass% or more and 15 mass% or less are preferable, 0.5 mass% or more and 10 mass% or less are more preferable, and 1 mass% or more and 8 mass% or less are especially preferable.

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; Don, acridone derivatives, such as N- butyl acridone; and, alpha, alpha-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, halogen compounds and the like.

  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 35% 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 monomer having a photopolymerizable functional group other than the epoxy group. By containing such a resin monomer, the 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 a resin having a hydrolyzed condensate of propyltriethoxysilane, a condensate of 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. Etc. in the skeleton. 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, phenoxy Diethylene 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) Addition of mono-ε-caprolactone to acrylate, trimethylolmethane tri (meth) acrylate, isobornyl (meth) acrylate, N-vinylpyrrolidone, acryloylmorpholine, urethane (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrahydrofurfuryl alcohol (Meth) acrylate, tetrahydrofurfuryl alcohol di-ε-caprolactone adduct (meth) acrylate, tetrahydrofurfuryl alcohol mono β-methyl-δ-valerolacto (Meth) acrylate compounds such as (meth) acrylate of adducts, (meth) acrylates of diβ-methyl-δ-valerolactone adducts of tetrahydrofurfuryl alcohol, ω-carboxy-polycaprolactone monoacrylate, etc .; Nitrile group-containing vinyl compounds such as acrylonitrile and methacrylonitrile; 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 -Resins having amide group-containing vinyl compounds such as isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, diacetone (meth) acrylamide, N, N-methylenebis (meth) acrylamide in the skeleton.

  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. 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 monomer having a photopolymerizable functional group other than an epoxy group is 0% by mass or more based on the entire resin composition forming the protective layer. 50 mass% or less is preferable and 0 mass% or more and 35 mass% or less are especially 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. Usually, the above-described aromatic epoxy compound, epoxy compound having no aromatic skeleton, A resin composition is obtained by mixing 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. The mixing method is not particularly limited, and may be sufficiently stirred and mixed at room temperature (25 ° C.) until the mixture becomes uniform.

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 (356 nm standard, metal halide) is applied to the polarizing plate before ultraviolet irradiation thus bonded. 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.

  Further, 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 includes an aromatic epoxy resin obtained by curing an aromatic epoxy compound with a resin composition. The aromatic epoxy compound has a rigid skeleton, and the aromatic epoxy resin obtained by curing the aromatic epoxy compound is also a rigid polymer. Therefore, the protective layer containing an aromatic epoxy resin can achieve a high elastic modulus and can suppress thermal contraction of the polarizer. In addition, the protective layer according to the present invention has good adhesion to the polarizer, and the protective layer can be formed directly on the substrate. Therefore, the protective layer according to the present invention can be applied as a protective film for protecting the polarizer of the polarizing plate used in the image display device. Moreover, when an aromatic epoxy compound is included as a main ingredient, a protective layer containing an aromatic epoxy resin as a main component obtained by curing a resin composition is preferable because durability is improved.

  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 plates according to the present invention will be described based on Examples 1 to 6 and Comparative Examples 1 to 3.

<Example 1>
Preparation of resin composition 80 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 20 parts by mass of Cel3000 (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, photoacid generator 4 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a (photocation polymerization initiator) and 0.5 parts by mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer are mixed to obtain a resin composition Was prepared.

Production of Polarizer A polarizer was produced by the following method. A polyvinyl alcohol film with an average polymerization degree of 2400, a saponification degree of 99.9% and a thickness of 75 μm is immersed in warm water at 28 ° C. for 90 seconds to swell, then iodine / potassium iodide (weight ratio 2/3) concentration 0.6% by weight The polyvinyl alcohol film was dyed while being dipped in an aqueous solution and stretched 2.1 times. Thereafter, the film was stretched in a boric acid ester aqueous solution at 60 ° C. so that the total stretching ratio was 5.8 times, washed with water, and then dried at 45 ° C. for 3 minutes to prepare a polarizer (thickness 25 μm).

Production of Polarizing Plate Next, using the polarizer produced as described above and the prepared resin composition in a constant temperature room at room temperature (25 ° C.) and a humidity of 50% RH, and by the method for producing a polarizing plate described above. A polarizing plate was prepared. In addition, 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 temperature-controlled 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>
70 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 30 parts by mass of EX214L (manufactured by Nagase ChemteX Corporation) as an epoxy compound not containing an aromatic ring, and CPI100- as a photoacid generator 4 parts by mass of P (manufactured by San Apro Co., Ltd.) and 0.5 parts 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>
70 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 15 parts by mass of Cel3000 (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, and OXT-221 (as another resin monomer) 15 parts by mass of Toagosei Co., Ltd., 4 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator, and 0.5 mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer Partial mixing was performed to prepare a resin composition. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Example 4>
70 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 10 parts by mass of Cel3000 (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, and OXT-121 (as an other resin monomer) 20 parts by mass of Toagosei Co., Ltd., 4 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator, and 0.5 mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer Partial mixing was performed to prepare a resin composition. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Example 5>
60 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 20 parts by mass of Cel3000 (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, and OXT-121 (as another resin monomer) 20 parts by mass of Toagosei Co., Ltd., 4 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator, and 0.5 mass of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer Partial mixing was performed to prepare a resin composition. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Example 6>
50 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 25 parts by mass of EX214L (manufactured by Nagase ChemteX Corporation) as an epoxy compound not containing an aromatic ring, and OXT- as another resin monomer 25 parts by mass of 121 (manufactured by Toagosei Co., Ltd.), 4 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) as a photoacid generator, and DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer A resin composition was prepared by mixing 0.5 parts by mass. Then, the polarizing plate was produced similarly to the above-mentioned Example 1 using the produced resin composition.

<Comparative Example 1>
20 parts by mass of EPICLON HP-4032D (manufactured by DIC Corporation) as an aromatic epoxy compound, 30 parts by mass of Cel3000 (manufactured by Daicel Corporation) and 25 parts of Cel2021P (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring 20 parts by mass of OXT-221 (manufactured by Toagosei Co., Ltd.), 4 parts by mass of CPI100-P (manufactured by SANAPRO) as a photoacid generator, and DETX- as a photosensitizer 0.5 parts by mass of S (manufactured by Nippon Kayaku Co., Ltd.) was 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 Example 2>
35 parts by mass of Cel2021P (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, 15 parts by mass of OXT-221 (manufactured by Toagosei Co., Ltd.) and OXT-121 (manufactured by Toagosei Co., Ltd.) as other resin monomers 50 parts by mass, 2.5 parts by mass of CPI100-P (manufactured by San Apro Co., Ltd.) and 2.5 parts 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 Example 3>
75 parts by mass of Cel2021P (manufactured by Daicel Corporation) as an epoxy compound not containing an aromatic ring, 25 parts by mass of OXT-221 (manufactured by Toagosei Co., Ltd.) as the other resin monomer, and CPI100-P (as a photopolymerization initiator) 4 parts by mass of San Apro Co., Ltd. and 1 part by mass of Irg184 (manufactured by BASF) 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.

Table 1 below summarizes the blending ratio (weight ratio) of each material of the resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3.

(Adhesion test)
Glass was bonded to one protective layer side of the polarizing plate prepared in Examples 1 to 6 and Comparative Examples 1 to 3 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 1mm square grids and applying cellophane tape to them, and then peeling them off, and the adhesion was evaluated by the number of grids where the protective layer remained without peeling off 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 prepared in Examples 1 to 6 and Comparative Examples 1 to 3 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 prepared in Examples 1 to 6 and Comparative Examples 1 to 3 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 prepared in Examples 1 to 6 and Comparative Examples 1 to 3 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.

Table 2 below shows 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 6, 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 5 in which the content of the aromatic epoxy compound in the resin composition was 60 parts 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 3, the polarizer shrinkage exceeded 0.5 mm, whereas in the polarizing plates of Examples 1 to 6, the polarizer shrinkage was all It became 0.5mm 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 3 were confirmed to have cracks in the polarizer, whereas the polarizers of Examples 1 to 6 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 3, cracking of the polarizer was confirmed, whereas in the polarizing plates of Examples 1 to 6, 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 evaluation and results of the tests of the polarizing plates of Examples 1 to 6 and Comparative Examples 1 to 3, 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 (7)

A polarizer,
A protective layer disposed on at least one surface of the polarizer and formed by a cured product of a resin composition containing an aromatic epoxy compound;
A polarizing plate comprising The polarizing plate according to claim 1, wherein the aromatic epoxy compound is a compound represented by the following general formula (1).
The resin composition contains the aromatic epoxy compound as a main component,
The polarizing plate according to claim 1 or 2, wherein the aromatic epoxy compound is contained in an amount of 40% by mass to 90% by mass with respect to the entire resin composition.
  The polarizing plate according to any one of claims 1 to 3, wherein the resin composition further includes an epoxy compound having no aromatic ring.   The polarizing plate according to claim 1, wherein the resin composition further contains a photocationic polymerization initiator.   The polarizing plate according to claim 1, wherein the protective layer has a thickness of 25 μm or less. An image display apparatus provided with the polarizing plate as described in any one of Claims 1 thru | or 6.