JP2016122181A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin polarizing plate that does not have a protective film between an adhesive layer and a polarizer and has improved durability in a humid and high-temperature environment, where the adhesive layer and a protective layer formed on the surface of the polarizer have a strong adhesion to each other; and a liquid crystal display device including the polarizing plate.SOLUTION: There is provided a polarizing plate having a functional resin layer, a first adhesive layer, a first protective layer that is a cured product of a curable resin composition, and a polarizer laminated in this order, where the curable resin composition contains an active energy-ray curable compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate and a liquid crystal display device having the polarizing plate.

  The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate is usually used by being incorporated in a liquid crystal display device in a state where a transparent resin film is laminated as a protective film on both sides of the polarizer. In recent years, thinning of liquid crystal display devices is progressing, and further thinning is demanded for polarizing plates incorporated in liquid crystal display devices. Then, the polarizing plate which laminated | stacked the protective film only on the one side of a polarizer is proposed (patent document 1).

  Moreover, in order to improve the brightness of the liquid crystal display device, a reflective polarizing film (brightness improving film) is laminated on the polarizing plate disposed on the light source side particularly in the liquid crystal display device through an adhesive layer. As the pressure-sensitive adhesive layer, a diffusion pressure-sensitive adhesive layer is often used in order to suppress interference fringes generated in the display unit of the liquid crystal display device.

  In a polarizing plate in which a protective film is laminated only on one side, when the brightness enhancement film is laminated via an adhesive layer, the surface in contact with the adhesive layer becomes a polarizer (Patent Document 2). In the polarizing plate having such a layer configuration, there is a problem that the adhesion between the polarizer and the pressure-sensitive adhesive layer is small. Furthermore, particularly when a diffusion adhesive is used as the pressure-sensitive adhesive layer, there is a problem that the durability of the pressure-sensitive adhesive layer in a wet heat environment is low, and the polarizing plate is floated or peeled off.

Japanese Patent Laid-Open No. 10-186133 JP 2010-39458 A

  The object of the present invention is a thin polarizing plate that does not have a protective film between the pressure-sensitive adhesive layer and the polarizer, and has a strong adhesion between the protective layer and the pressure-sensitive adhesive layer formed on the surface of the polarizer, An object of the present invention is to provide a polarizing plate having improved durability in a humid heat environment and a liquid crystal display device having the polarizing plate.

[1] A polarizing plate in which a functional resin layer, a first pressure-sensitive adhesive layer, a first protective layer that is a cured product of a curable resin composition, and a polarizer are laminated in this order, and the curable resin The composition contains an active energy ray-curable compound, and a polarizing plate.
[2] The polarizing plate according to [1], wherein the curable resin composition contains a light diffusing agent.
[3] The polarizing plate according to [1] or [2], wherein the first pressure-sensitive adhesive layer is a diffusion pressure-sensitive adhesive layer.
[4] The polarizing plate according to any one of [1] to [3], wherein the functional resin layer is a layer having a brightness enhancement film.
[5] The polarizing plate according to any one of [1] to [4], wherein the active energy ray-curable compound includes a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.
[6] The polarizing plate according to any one of [1] to [5], wherein the active energy ray-curable compound includes a cationic polymerizable compound.
[7] The polarizing plate according to [6], wherein the cationically polymerizable compound includes a compound having at least one oxirane ring in the molecule.
[8] The polarizing plate according to any one of [1] to [7], wherein the thickness of the first pressure-sensitive adhesive layer is 0.1 to 10 μm.
[9] The polarizing plate according to any one of [1] to [8], having a second protective layer on the side opposite to the side where the first protective layer of the polarizer is laminated.
[10] The polarizing plate according to [9], wherein the second protective layer is a thermoplastic resin film.
[11] The polarizing plate according to [9] or [10], having a second pressure-sensitive adhesive layer on the side opposite to the side on which the polarizer of the second protective layer is laminated.
[12] The polarizing plate according to [11], wherein a release film is laminated on the surface of the second pressure-sensitive adhesive layer opposite to the side on which the second protective layer is laminated.
[13] A liquid crystal display device comprising the polarizing plate according to any one of [1] to [11] and a liquid crystal cell.

  According to the present invention, a thin polarizing plate that does not have a protective film between the pressure-sensitive adhesive layer and the polarizer, has strong adhesion between the polarizer and the pressure-sensitive adhesive layer, and has improved durability in a humid heat environment. A polarizing plate and a liquid crystal display device having the polarizing plate can be provided.

It is a figure which shows an example of the layer structure in the polarizing plate of this invention. It is a figure which shows an example of the layer structure in the liquid crystal display device of this invention.

  The polarizing plate of the present invention is a polarizing plate in which a functional resin layer, a first pressure-sensitive adhesive layer, a first protective layer that is a cured product of a curable resin composition, and a polarizer are laminated in this order. Further, the curable resin composition contains an active energy ray-curable compound. Hereinafter, each member will be described.

[Polarizer]
The polarizer is preferably an optical film having a property of absorbing linearly polarized light having a vibration surface parallel to the optical axis and transmitting linearly polarized light having a vibration surface orthogonal to the optical axis, and specifically, a polyvinyl alcohol resin. Examples thereof include a polarizer in which a dichroic dye (iodine or dichroic organic dye) is adsorbed and oriented on a film.
The thickness of the polarizer is usually 30 μm or less, preferably 25 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, and particularly preferably 7 μm or less. In addition, when applying what applied the dichroic pigment | dye to the polyvinyl alcohol-type resin layer as a polarizer, the polarizer may be obtained by extending | stretching a polyvinyl alcohol-type resin single-piece | unit, or a substrate etc. After applying and drying the alcohol resin solution, it may be stretched together with the base material to remove the base material to obtain a polarizer. When stretching together with the substrate, it is easy to produce a polarizer having a thickness of 7 μm or less.

  Examples of the substrate include a polyethylene terephthalate film, a polycarbonate film, a triacetyl cellulose film, a norbornene film, a polyester film, and a polystyrene film.

  As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin layer, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

  The degree of saponification of the polyvinyl alcohol-based resin is usually 80 mol% or more, preferably 90 to 99.5 mol%, more preferably 94 to 99 mol%. When the saponification degree is less than 80 mol%, the water resistance and heat-and-moisture resistance of the resulting polarizing plate are lowered. When the degree of saponification exceeds 99.5 mol%, the dyeing speed becomes slow, productivity may be lowered, and a polarizer having sufficient polarization performance may not be obtained.

  The polyvinyl alcohol-based resin may be a partially modified polyvinyl alcohol, for example, olefin modification with ethylene, propylene, etc .; unsaturated carboxylic acid modification with acrylic acid, methacrylic acid, crotonic acid, etc .; unsaturated Those modified with an alkyl ester of carboxylic acid, acrylamide or the like may be used. The modification ratio of the polyvinyl alcohol-based resin is preferably less than 30 mol%, and more preferably less than 10%. When modification exceeding 30 mol% is performed, the dichroic dye tends to be difficult to adsorb, and a polarizer having sufficient polarization performance may not be obtained.

  The average degree of polymerization of the polyvinyl alcohol resin is preferably about 100 to 10000, more preferably 1500 to 8000, and still more preferably 2000 to 5000. When the average degree of polymerization is less than 100, it tends to be difficult to obtain preferable polarization performance. When the average degree of polymerization exceeds 10,000, the solubility in a solvent is deteriorated, and the formation of a polyvinyl alcohol-based resin layer is difficult. Tend to be difficult.

  An appropriate commercially available product can be used as the polyvinyl alcohol-based resin. Suitable commercial products are trade names, “PVA124” and “PVA117” manufactured by Kuraray Co., Ltd. (both saponification degree: 98-99 mol%), “PVA624” (saponification degree: 95- 96 mol%), "PVA617" (degree of saponification: 94.5-95.5 mol%); "N-300" and "NH-18" (both saponification degrees) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. : 98 to 99 mol%), "AH-22" (degree of saponification: 97.5 to 98.5 mol%), "AH-26" (degree of saponification: 97 to 98.8 mol%), Japan “JC-33” (saponification degree: 99 mol% or more), “JF-17”, “JF-17L” and “JF-20” (all saponification degree: 98- 99 mol%), “JM-26” (degree of saponification: 95.5-97.5 mol%), “JM-33” (ken Degrees: 93.5 to 95.5 mol%), "JP-45" (saponification degree: 86.5 to 89.5 mol%), and the like.

  Examples of the dichroic dye contained (adsorption orientation) in the polarizer include iodine or a dichroic organic dye. Dichroic organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B , Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue , Direct First Orange S, and First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

[First protective layer]
In the polarizing plate of the present invention, the first protective layer is laminated on one side of the polarizer. The first protective layer is a cured layer formed by curing a curable resin composition containing an active energy ray-curable compound. The active energy ray-curable compound means a compound that can be cured by irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.). The active energy ray-curable compound may be a cationic polymerizable compound, a radical polymerizable compound, or may contain both a cationic polymerizable compound and a radical polymerizable compound.

  The glass transition temperature (Tg) of the first protective layer is preferably 23 ° C. or higher, more preferably 40 ° C. or higher, further preferably 50 ° C. or higher, and preferably 60 ° C. or higher. Particularly preferred. Moreover, the glass transition temperature of a 1st protective layer is 200 degrees C or less normally. When the glass transition temperature of the first protective layer is less than 23 ° C., the optical performance of the polarizer tends to deteriorate. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

  The thickness of the first protective layer is preferably 0.1 to 10 μm, and more preferably 1 to 5 μm. If the thickness of the first protective layer is less than 0.1 μm, the suppression of reduction in optical performance may not be sufficient, while if it exceeds 10 μm, the effect of reducing the thickness and weight of the polarizing plate may be reduced. is there.

[Curable resin composition]
The curable resin composition preferably contains a radical polymerizable compound or a cationic polymerizable compound, and more preferably contains a radical polymerizable compound and a cationic polymerizable compound. When a radically polymerizable compound and a cationically polymerizable compound are included, an effect of increasing the hardness of the first protective layer can be expected, and furthermore, adjustment of the viscosity and curing rate of the curable resin composition can be performed more easily. Become.

[Active energy ray curable compound (radical polymerizable compound)]
Examples of the radical polymerizable compound include a compound having at least one (meth) acryloyloxy group in the molecule (hereinafter sometimes referred to as “(meth) acrylic compound”), and at least one ( Examples thereof include compounds having a meth) acrylamide group (hereinafter sometimes referred to as “(meth) acrylamide compounds”). The “(meth) acryloyloxy group” means a methacryloyloxy group or an acryloyloxy group, and the (meth) acrylamide group means a methacryloylamide group or an acryloylamide group.

(Meth) acrylic compounds include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule and (meth) acrylates having at least two (meth) acryloyloxy groups in the molecule. An oligomer etc. are mentioned. These may be used alone or in combination of two or more. When two or more types are used in combination, two or more (meth) acrylate monomers may be used, two or more (meth) acrylate oligomers may be used, and, of course, one or more (meth) acrylate monomers. One or more (meth) acrylate oligomers may be used in combination.

  The above (meth) acrylate monomer includes a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule, and a bifunctional (meth) methacrylate having two (meth) acryloyloxy groups in the molecule. ) Acrylate monomers and polyfunctional (meth) acrylate monomers having 3 or more (meth) acryloyloxy groups in the molecule.

  Monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4- Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, 1,4-cyclohexanedimethanol monoacrylate , Dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (Meth) acrylate, ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, and the like can be given.

  As the monofunctional (meth) acrylate monomer, a carboxyl group-containing (meth) acrylate monomer may be used. Examples of the carboxyl group-containing monofunctional (meth) acrylate monomer include 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, carboxyethyl (meth) acrylate, and 2- (meth). Examples include acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N ′, N′-dicarboxymethyl-p-phenylenediamine, and 4- (meth) acryloyloxyethyl trimellitic acid.

Examples of (meth) acrylamide compounds include N-substituted (meth) acrylamide compounds. An N-substituted (meth) acrylamide compound is a (meth) acrylamide compound having a substituent at the N-position. A typical example of the substituent is an alkyl group. The N-position substituents may be bonded to each other to form a ring, and —CH ₂ — constituting the ring may be substituted with an oxygen atom. Further, a substituent such as an alkyl group or an oxo group (═O) may be bonded to the carbon atom constituting the ring. N-substituted (meth) acrylamides can generally be prepared by reaction of (meth) acrylic acid or its chloride with a primary or secondary amine.

The N-substituted (meth) acrylamide compound is preferably a compound represented by the following formula (III). In the following formula (III), Q ¹ represents a hydrogen atom or a methyl group, Q ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Q ³ represents a carbon number that may have a hydroxyl group or an amino group. 1 to 6 alkyl groups are represented, or Q ² and Q ³ are bonded to each other to form a 5-membered or 6-membered ring in which —CH ₂ — may be substituted with an oxygen atom. The hydrogen atom of the amino group may be substituted with an alkyl group.
An example where Q ³ is an alkyl group having a hydroxyl group is a hydroxyalkyl group. Examples where Q ³ is an alkyl group having an amino group include an aminoalkyl group, an N-alkylaminoalkyl group, and an N, N-dialkylaminoalkyl group. When Q ² and Q ³ are bonded to each other to form a 5-membered ring or 6-membered ring in which —CH ₂ — may be substituted with an oxygen atom, examples of the 5-membered ring or 6-membered ring are N In the form of a group leading to carbonyl (C═O) at the -position, 1-pyrrolidinyl (C ₄ H ₈ N—), 2-oxazolidinone-3-yl [C ₂ H ₄ OC (═O) N—] , piperidino (N- C ₅ H _10), morpholino _{(C 2 H 4 OC 2 H} 4 N-) , and the like.

Examples of N-substituted (meth) acrylamide compounds in which Q ² is a hydrogen atom and Q ³ is an alkyl group include N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, There are N-butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-hexyl (meth) acrylamide and the like. Similarly, examples of N-substituted (meth) acrylamide in which both Q ² and Q ³ are alkyl groups include N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide.

Examples of N-substituted (meth) acrylamide compounds in which Q ² is a hydrogen atom and Q ³ is an alkyl group having a hydroxyl group include N-hydroxymethyl (meth) acrylamide and N- (2-hydroxyethyl) (meth) acrylamide. N- (2-hydroxypropyl) (meth) acrylamide. As an N-substituted (meth) acrylamide compound in which Q ² is a hydrogen atom and Q ³ is an alkyl group having an amino group, N- [2- (N, N-dimethylamino) ethyl] (meth) acrylamide, N- [2- (N, N-diethylamino) ethyl] (meth) acrylamide, N- [3- (N, N-dimethylamino) propyl] (meth) acrylamide, N- [1-methyl-1- (N , N-dimethylamino) ethyl] (meth) acrylamide and the like.

As an N-substituted (meth) acrylamide compound in which Q ² and Q ³ are bonded to each other to form a 5-membered ring or 6-membered ring in which —CH ₂ — may be substituted with an oxygen atom, N-acryloyl Examples include pyrrolidine, 3-acryloyl-2-oxazolidinone, 4-acryloylmorpholine, N-acryloylpiperidine, and N-methacryloylpiperidine.

  Among the N-substituted (meth) acrylamide compounds, N-hydroxyalkyl (meth) acrylamides such as N-hydroxymethylacrylamide and N- (2-hydroxyethyl) acrylamide, and N, N-dimethylacrylamide and N, N, N-dialkyl (meth) acrylamide such as N-diethylacrylamide is preferred, and N- (2-hydroxyethyl) acrylamide or N, N-dimethylacrylamide is particularly preferred.

  In addition, N-alkyl (meth) acrylamide having a long chain alkyl such as N-dodecyl (meth) acrylamide, N- (methoxymethyl) acrylamide, N- (ethoxymethyl) acrylamide, N- (propoxymethyl) acrylamide, and N- (alkoxyalkyl) (meth) acrylamide such as N- (butoxymethyl) acrylamide can also be used as the N-substituted (meth) acrylamide compound constituting the active energy ray-curable compound.

  Bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylate, polyoxyalkylene glycol di (meth) acrylate, halogen-substituted alkylene glycol di (meth) acrylate, aliphatic polyol di (meth) acrylate, hydrogenated Di (meth) acrylate of dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylate of dioxane glycol or dioxane dialkanol, di (meth) acrylate, bisphenol A or bisphenol of alkylene oxide adduct of bisphenol A or bisphenol F A typical example is F epoxy di (meth) acrylate.

  Examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di ( (Meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditrimethylolpropane di (meth) acrylate , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di ( Acrylate), polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicone di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2-bis [4 -(Meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclodecane dimethanol di (Meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], aceto of hydroxypivalaldehyde and trimethylolpropane Di (meth) acrylate, tris (hydroxyethyl) isocyanate of a phenolic compound [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] Examples thereof include nurate di (meth) acrylate.

  The trifunctional or higher polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol. Tri- or higher functional aliphatic polyols such as tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate Of poly (meth) acrylate. In addition, poly (meth) acrylate of tri- or higher functional halogen-substituted polyol, tri (meth) acrylate of glycerin alkylene oxide adduct, tri (meth) acrylate of trimethylolpropane alkylene oxide adduct, 1,1,1- Examples include tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate tri (meth) acrylates, and the like.

  Examples of (meth) acrylate oligomers include urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and epoxy (meth) acrylate oligomers.

  The urethane (meth) acrylate oligomer is a compound having a urethane bond (—NHCOO—) and at least two (meth) acryloyloxy groups in the molecule. Specifically, the product of the urethanation reaction between a hydroxyl group-containing (meth) acrylate monomer having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule and a polyisocyanate, or a polyol and a polyisocyanate. Products of urethane reaction of terminal isocyanate group-containing urethane compound obtained by reacting with a (meth) acrylate monomer each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule Etc.

  Examples of hydroxyl group-containing (meth) acrylate monomers used in the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-phenoxy. Examples include propyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate.

  Examples of the polyisocyanate used for the urethanization reaction with the hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and aromatic of these diisocyanates. Diisocyanates obtained by hydrogenating the above isocyanates (for example, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, Examples thereof include polyisocyanates obtained by increasing the amount of diisocyanate.

In addition, examples of the polyols used for forming a terminal isocyanate group-containing urethane compound by reaction with polyisocyanate include aromatic polyols, aliphatic and alicyclic polyols, polyester polyols, polyether polyols, and the like. . Examples of aromatic polyols include 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, 4,4′-naphthalenediethanol, 3,4′-naphthalenediethanol, and the like. Can be mentioned. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditriol. Examples include methylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.
The polyester polyol is obtained by a dehydration condensation reaction between the above polyols and a polybasic carboxylic acid or an anhydride thereof. Examples of the polybasic carboxylic acid or its anhydride include succinic acid, succinic anhydride, adipic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, anhydrous Examples include pyromellitic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic acid, and hexahydrophthalic anhydride.
Examples of the polyether polyol include polyalkylene glycol, polyoxyalkylene-modified polyol obtained by reaction of the above polyols or dihydroxybenzenes with alkylene oxide, and the like.

  The polyester (meth) acrylate oligomer is a compound having at least two ester bonds and at least two (meth) acryloyloxy groups in the molecule. Specifically, it can be obtained by dehydration condensation reaction of (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Polybasic carboxylic acids or anhydrides used in the dehydration condensation reaction include succinic acid, succinic anhydride, adipic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, trimellitic acid, trimellitic anhydride Examples include acids, pyromellitic acid, pyromellitic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, and the like. The polyol used in the dehydration condensation reaction is 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane. , Ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, hydrogenated bisphenol A and the like.

  The epoxy (meth) acrylate oligomer has at least two (meth) acryloyloxy groups in the molecule, and can be obtained by an addition reaction between polyglycidyl ether and (meth) acrylic acid. Examples of the polyglycidyl ether used for the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

  When the curable resin composition contains a radical polymerizable compound, the content of the radical polymerizable compound is usually 1 to 70 parts by weight, preferably 10 to 60 parts by weight with respect to 100 parts by weight of the curable composition. Part.

[Active energy ray curable compound (cationic polymerizable compound)]
Examples of the cationically polymerizable compound include a compound having at least one oxetane ring (four-membered ether) in the molecule (hereinafter sometimes simply referred to as “oxetane compound”), and at least one oxirane ring in the molecule. Examples thereof include compounds having (3-membered ring ether) (hereinafter sometimes simply referred to as “epoxy compounds”).

  Examples of the oxetane compound include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [( 3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolak oxetane and the like. These oxetane compounds can be easily obtained as commercial products, and as the commercial products, all of them are trade names sold by Toagosei Co., Ltd., “Aron Oxetane (registered trademark) XT-101”. ”,“ Aron Oxetane (registered trademark) OXT-121 ”,“ Aron Oxetane (registered trademark) OXT-221 ”,“ Aron Oxetane (registered trademark) OXT-221 ”,“ Aron Oxetane (registered trademark) OXT-212 ”, etc. Is mentioned.

  Moreover, in addition to said oxetane compound, the curable resin composition may contain an epoxy compound. It is preferable that the curable resin composition contains an epoxy compound in that the adhesion between the first protective layer and the polarizer becomes better.

  Examples of the epoxy compound include an aromatic epoxy compound, a glycidyl ether of a polyol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound.

  Aromatic epoxy compounds include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins and hydroxybenzaldehyde phenol novolacs Examples thereof include novolak-type epoxy resins such as epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  As the glycidyl ether of a polyol having an alicyclic ring, a nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating an aromatic polyol under pressure in the presence of a catalyst under pressure is used as a glycidyl ether. Can be listed. Examples of aromatic polyols include bisphenol type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac type resins such as phenol novolac resin, cresol novolac resin, hydroxybenzaldehyde phenol novolac resin; tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, A polyfunctional compound such as polyvinylphenol is exemplified. Glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of these aromatic polyols with epichlorohydrin. Among these glycidyl ethers of polyols having an alicyclic ring, hydrogenated bisphenol A diglycidyl ether is preferable.

  Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene glycol Diglycidyl ether of neopentyl glycol; by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol or glycerin The polyglycidyl ether of the polyether polyol obtained is mentioned.

Moreover, the monofunctional epoxy compound represented by the following Formula (I) is also mentioned as an aliphatic epoxy compound. R ¹ is an optionally branched alkyl group having 1 to 15 carbon atoms. The alkyl group preferably has 6 or more carbon atoms, more preferably 6 to 10 carbon atoms. Of these, a branched alkyl group is preferred. Examples of the monofunctional epoxy compound represented by the formula (I) include 2-ethylhexyl glycidyl ether.

  An alicyclic epoxy compound refers to a compound having at least one structure in the molecule forming an oxirane ring together with a carbon atom of the alicyclic ring. Here, “the structure forming an oxirane ring together with the carbon atom of the alicyclic ring” means a structure represented by the following formula (II). N in a formula is an integer of 2-5.

A compound in which a group in a form in which one or a plurality of hydrogen atoms in (CH ₂ ) _n in formula (II) are removed is bonded to another chemical structure is an alicyclic epoxy compound. In addition, one or more hydrogen atoms in (CH ₂ ) _n forming the alicyclic ring may be substituted with a linear alkyl group such as a methyl group or an ethyl group.

  As the epoxy compound, an alicyclic epoxy compound is preferable, and an epoxy cyclohexane (with n = 4 in the above formula (II)) or epoxy cycloheptane is preferable in that an excellent protective layer can be easily obtained due to adhesion with a polarizer. An epoxy compound having [in formula (II) where n = 5] is more preferred. Specific examples of the alicyclic epoxy compound are listed below.

  In the curable resin composition, the epoxy compound may be used alone or in combination of two or more.

When curable resin composition contains an oxetane compound, content of an oxetane compound is 1-50 weight part normally with respect to 100 weight part of curable compositions, Preferably it is 10-40 weight part. When curable resin composition contains an epoxy compound, content of an epoxy compound is 1-90 weight part normally with respect to 100 weight part of curable compositions, Preferably it is 20-80 weight part.
Moreover, when curable resin composition contains a cationically polymerizable compound, content of a cationically polymerizable compound is 10-99 weight part normally with respect to 100 weight part of curable compositions, Preferably 40- 99 parts by weight.

[Radical polymerization initiator]
When the curable resin composition contains a radical polymerizable compound as the active energy ray curable compound, the curable resin composition preferably contains a radical polymerization initiator. Any radical polymerization initiator may be used as long as it can initiate polymerization of a radical polymerizable compound such as a (meth) acrylic compound by irradiation with active energy rays, and a known one can be used. Examples of the radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- ( Acetophenone initiators such as methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone and 4,4′-diamino Benzophenone initiators such as benzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; other xanthone, fluorenone, camphorquinone, benz Examples include aldehyde and anthraquinone.

  Commercially available radical polymerization initiators can be easily obtained. For example, “Irgacure (registered trademark) 184”, “Irgacure (registered trademark) 907” and “Darocur (registered trademark)” manufactured by BASF are available. Trademark) 1173 "," Lucirin (registered trademark) TPO ", and the like.

  The content of the radical polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 6 parts by weight with respect to 100 parts by weight of the total amount of radical polymerizable compounds such as (meth) acrylic compounds. . When the blending amount of the radical polymerization initiator is small, the curing becomes insufficient, and the adhesion between the first protective layer and the polarizer layer tends to decrease. Moreover, when there are too many compounding quantities of a radical polymerization initiator, the active energy ray curable compound in a curable resin composition will decrease relatively, and the durability of the optical characteristic of the polarizing plate obtained may fall. is there.

[Cationic polymerization initiator]
When the curable resin composition contains a cationic polymerizable compound such as an oxetane compound or an epoxy compound as an active energy ray curable compound, a cationic polymerization initiator is usually blended in the curable resin composition. If a cationic polymerization initiator is used, the temperature rise required when forming the first protective layer can be reduced. Therefore, a protective layer with better adhesion to the polarizer can be formed without considering the heat resistance of the polarizer and the distortion due to the expansion of the polarizer.

  The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of the cationic polymerizable compound. Examples of the cationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-arene complexes.

Examples of the aromatic diazonium salt include the following compounds.
Benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, benzenediazonium hexafluoroborate, etc.

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

Examples of the aromatic sulfonium salt include the following compounds.
Triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis [diphenylsulfonio] diphenyl sulfide bishexafluorophosphate, 4,4'-bis [Di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate, 7- [di ( p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone Tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoro Antimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Examples of the iron-arene complex include the following compounds.
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

  These cationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad (registered trademark) PCI-220” and “Kayarad” sold by Nippon Kayaku Co., Ltd. under the trade names, respectively. (Registered trademark) PCI-620 "," UVI-6990 "sold by Dow Chemical Company," UVACURE (registered trademark) 1590 "sold by Daicel-Cytec Corporation, and sold by ADEKA Corporation "Adekaoptomer (registered trademark) SP-150" and "Adekaoptomer (registered trademark) SP-170", "CI-5102" and "CIT-1370" sold by Nippon Soda Co., Ltd. , "CIT-1682", "CIP-1866S", "CIP-2048S" and "CIP-2064S", Midori Chemical ( "DPI-101", "DPI-102", "DPI-103", "DPI-105", "MPI-103", "MPI-105", "BBI-101", " “BBI-102”, “BBI-103”, “BBI-105”, “TPS-101”, “TPS-102”, “TPS-103”, “TPS-105”, “MDS-103”, “MDS-” 105 "," DTS-102 "and" DTS-103 "," PI-2074 "sold by Rhodia.

  These cationic polymerization initiators may be used alone or in combination of two or more. Aromatic sulfonium salt in that it has an ultraviolet absorption property even in a wavelength region of 300 nm or more, and thus can provide a cured layer of a curable resin composition having excellent curability and good mechanical strength and adhesion. Is preferred.

  The content of the cationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 6 parts by weight, based on 100 parts by weight of the total of the cationic polymerizable compounds such as epoxy compounds and oxetane compounds. When the content of the cationic polymerization initiator is small, curing is insufficient and mechanical strength and adhesiveness of the first protective layer tend to be lowered. On the other hand, when there is too much content of a cationic polymerization initiator, the optical performance of a polarizer may fall.

[Light diffusing agent]
The curable resin composition preferably contains a light diffusing agent. The light diffusing agent has a function of diffusing light. By including a light diffusing agent in the curable resin composition forming the first protective layer, when the first pressure-sensitive adhesive layer is a diffusion pressure-sensitive adhesive layer containing a light diffusing agent, the content of the light diffusing agent is Therefore, the wet heat durability of the polarizing plate can be further improved. The light diffusing agent is preferably a particle, and more preferably a particle having a refractive index different from that of the base polymer constituting the curable resin composition. Examples of the light diffusing agent include particles made of an inorganic compound and particles made of an organic compound (polymer). Since the base polymer constituting the pressure-sensitive adhesive layer, including the acrylic polymer, often exhibits a refractive index of around 1.4, the light diffusing agent incorporated therein has a refractive index of about 1-2. From the above, it may be selected as appropriate. The difference in refractive index between the base polymer constituting the first pressure-sensitive adhesive layer and the light diffusing agent is usually 0.01 or more, and from the viewpoint of brightness and visibility of the liquid crystal display device, 0.01 to 0.5. Is preferable. The particles used as the light diffusing agent are preferably spherical, more preferably close to monodisperse, and more preferably particles having an average particle size in the range of about 2 to 6 μm.

  Examples of the particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45).

  Particles made of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index 1.50). To 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), silicone resin Examples thereof include beads (refractive index: 1.46).

  The blending amount of the light diffusing agent is the haze value required for the first protective layer in which the light diffusing agent is blended, the brightness of the liquid crystal display device to which the polarizing plate having the first protective layer is applied, etc. Although it is determined as appropriate in consideration, it is generally 3 to 50 parts by weight, preferably 5 to 45 parts by weight, based on 100 parts by weight of the base polymer of the curable resin composition.

The first protective layer containing the light diffusing agent ensures the brightness of the liquid crystal display device in which the polarizing plate is incorporated, and from the viewpoint of preventing bleeding and blurring of the display image from occurring. The haze is preferably 10 to 80%, more preferably 20 to 60%. The haze is a value defined by JIS K 7105 and expressed by (diffuse transmittance / total light transmittance) × 100 (%).
[Other ingredients]
The curable resin composition may further contain a photosensitizer as necessary. By containing a photosensitizer, the reactivity of cationic polymerization and / or radical polymerization is increased, and the mechanical strength of the first protective layer and the adhesion of the first protective layer can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreductive dyes.

  In the curable resin composition, a known polymer additive usually used for polymers can be added. Examples of the polymer additive include primary antioxidants such as phenols and amines, sulfur secondary antioxidants, hindered amine light stabilizers (HALS), benzophenones, benzotriazoles, and benzoates. And ultraviolet absorbers.

  The curable resin composition may contain a solvent. The solvent is appropriately selected in consideration of the solubility of the components constituting the curable resin composition. Solvents include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol, isopropanol and n-butanol; acetone and methyl ethyl ketone Ketones such as methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; halogenated hydrocarbons such as methylene chloride and chloroform There is kind. The content of the solvent is appropriately determined so as to have a viscosity that allows easy application of the curable resin composition.

The curable resin composition may contain a leveling agent. When applying a curable resin composition to a polarizer or a substrate, if the wettability on the polarizer or the substrate is poor or the uniformity of the surface of the cured layer of the curable resin composition is poor, leveling They can be improved by adding agents. As the leveling agent, various compounds such as silicone-based, fluorine-based, polyether-based, acrylic acid copolymer-based and titanate-based compounds can be used. These leveling agents may be used alone or in combination of two or more.
The content of the leveling agent is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.7 part by weight, with respect to 100 parts by weight of the active energy ray-curable compound. More preferably, it is 2 to 0.5 parts by weight. If the content is less than 0.01 parts by weight, the wettability and surface uniformity tend to be insufficiently improved. If the amount exceeds 1 part by weight, the adhesion of the first protective layer is poor. There is a tendency to decrease.

[Second protective layer]
In the polarizing plate of the present invention, it is preferable that the polarizer has a second protective layer on the side opposite to the side where the first protective layer is laminated. The second protective layer is preferably laminated on the polarizer. As a 2nd protective layer, the layer obtained by hardening | curing curable resin composition similarly to the above-mentioned 1st protective layer, or a thermoplastic resin film is mentioned. When the second protective layer is a layer obtained by curing the curable resin composition in the same manner as the first protective layer described above, the curable resin that forms the first protective layer and the second protective layer The same curable resin composition may be sufficient as a composition, and a different curable resin composition may be sufficient as it. When the second protective layer is a layer obtained by curing the curable resin composition, the polarizing plate is a polarizing plate having no protective film on both sides, and the second protective layer is a thermoplastic resin film. In this case, the polarizing plate is a polarizing plate having a protective film on one side. In the polarizing plate of the present invention, the second protective layer is preferably a thermoplastic resin film.
As thermoplastic resin films, cellulose acetate resins, cycloolefin resins, polyolefin resins, acrylic resins, polyimide resins, polycarbonate resins, polyester resins, etc. have been widely used as protective film forming materials in the field. Films formed from the materials used can be used. From the viewpoints of mass productivity and adhesiveness, the thermoplastic resin film is preferably a cellulose acetate-based resin film or a cycloolefin-based resin film. Moreover, the cellulose acetate type-resin film is more preferable from the point that the ease of providing a surface treatment layer and an optical characteristic are favorable.

  The cellulose acetate-based resin film is a film composed of a cellulose portion or a complete acetate ester, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film.

  A commercial item can be used for a cellulose acetate type-resin film. Suitable commercial products include “Fujitac (registered trademark) TD80”, “Fujitack (registered trademark) TD80UF”, “Fujitac (registered trademark) TD80UZ”, and Konica Minolta Opto Co., Ltd. sold by Fuji Film Co., Ltd. "KC8UX2M", "KC8UY" (all of which are trade names), and the like.

  The cycloolefin resin is a thermoplastic resin including a unit derived from a monomer having a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. The cycloolefin-based resin may be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer, ring-opening copolymer using two or more cycloolefins, cycloolefin and chain olefin, vinyl group, etc. It may be an addition polymer with an aromatic compound having Moreover, when the thermoplastic resin film is bonded to the polarizer, it is also effective to introduce a polar group from the viewpoint of improving the adhesion with the polarizer.

  When a copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group constitutes a protective film, examples of the chain olefin include ethylene and propylene, and an aromatic group having a vinyl group. Examples of the compound include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In such a terpolymer, the monomer unit consisting of a chain olefin is usually 5 to 80 mol% of a monomer consisting of an aromatic compound having a vinyl group with respect to the total number of units constituting the polymer of 100 mol%. The unit is usually 5 to 80 mol%.

  Commercially available products can be used for the cycloolefin-based resin, and “TOPAS (registered trademark)” (Topas Advanced Polymers GmbH), “Arton (registered trademark)” (manufactured by JSR Corporation), “Zeonor ( "ZEONOR (registered trademark)", "ZEONEX (registered trademark)" (manufactured by Nippon Zeon Co., Ltd.), "Apel (registered trademark)" (manufactured by Mitsui Chemicals, Inc.) (all products Name) etc. can be used suitably. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. Even if commercially available films such as “ESCINA (registered trademark)”, “SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “ZEONOR FILM (registered trademark)” (manufactured by ZEON CORPORATION) are used. Good.

  The cycloolefin resin film may be uniaxially stretched or biaxially stretched. In this case, the draw ratio is usually 1.1 to 5 times, preferably 1.1 to 3 times.

  The polyolefin-based resin is a polymer having a chain olefin such as ethylene or propylene as a main monomer, and may be a homopolymer or a copolymer. Of these, a homopolymer of propylene and a copolymer in which a small amount of ethylene is copolymerized with propylene are preferable.

  The acrylic resin is a polymer having methyl methacrylate as a main monomer, and may be a homopolymer of methyl methacrylate, methyl methacrylate, and an acrylic ester such as methyl acrylate. The copolymer may be used.

  Polyimide resin is a polymer with an imide bond in the main chain, and is polymerized with tetracarboxylic dianhydride and diamine to form polyamic acid (polyamic acid), which is a polyimide precursor, and then dehydrated and cyclized. (Imidation) What is obtained by reaction is mentioned.

  The polycarbonate-based resin is a polymer having a carbonate bond in the main chain, and examples thereof include those obtained by condensation polymerization of bisphenol A and phosgene.

  The polyester-based resin is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol, and examples thereof include polyethylene terephthalate.

  In addition, the surface of the thermoplastic resin film far from the polarizer may be subjected to surface treatment such as antiglare treatment, hard coat treatment, antistatic treatment, antireflection treatment, liquid crystalline compounds, A coat layer made of a molecular weight compound or the like may be formed.

As a 2nd protective layer, when employ | adopting the layer obtained by hardening | curing curable resin composition, 0.1-10 micrometers is preferable and, as for the thickness of a 2nd protective layer, 1-5 micrometers is more preferable. If the thickness of the second protective layer is less than 0.1 μm, the suppression of reduction in optical performance may not be sufficient, while if it exceeds 10 μm, the effect of reducing the thickness and weight of the polarizing plate may be reduced. is there.
When a thermoplastic resin film is employed as the second protective layer, it is usually 5 to 100 μm, preferably 10 to 80 μm, and more preferably 50 μm or less. If the thickness of the thermoplastic resin film is too thin, the strength tends to decrease and the processability tends to be inferior. If it is too thick, the transparency tends to decrease and the weight of the polarizing plate tends to increase.

[Adhesive layer]
In the polarizing plate of the present invention, the first pressure-sensitive adhesive layer is laminated on the surface of the first protective layer that is far from the polarizer. Furthermore, it is preferable that the polarizing plate of this invention has a 2nd adhesive layer in the side far from the polarizer in a 2nd protective layer. More preferably, the second pressure-sensitive adhesive layer is laminated on the second protective layer. The polarizing plate having the second pressure-sensitive adhesive layer can be directly bonded to the liquid crystal cell via the second pressure-sensitive adhesive layer. In the present specification, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be collectively referred to as a pressure-sensitive adhesive layer.
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer preferably contains a base polymer such as an acrylic polymer, silicone polymer, polyester, polyurethane, or polyether. Above all, like an adhesive based on an acrylic polymer (acrylic adhesive), it has excellent optical transparency and adhesiveness, maintains appropriate wettability and cohesion, and is also weather and heat resistant. It is more preferable to select and use a material that has properties such as, and that does not cause peeling problems such as floating and peeling under heating and humidification conditions. Examples of the acrylic pressure-sensitive adhesive include an alkyl ester in which an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group and a butyl group is bonded to an oxy group of (meth) acrylic acid, and (meth) acrylic acid or (meth) An acrylic copolymer obtained by blending and polymerizing an acrylic monomer such as hydroxyethyl acrylate is useful as the base polymer. The glass transition temperature of the base polymer is preferably 25 ° C. or lower, and more preferably 0 ° C. or lower. Moreover, it is preferable that the weight average molecular weight of a base polymer is 100,000 or more.

  The pressure-sensitive adhesive layer is prepared by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by weight solution, and forming a pressure-sensitive adhesive layer on the release film. The pressure-sensitive adhesive layer can be formed by transferring onto the protective film. In general, the pressure-sensitive adhesive composition contains a crosslinking agent in addition to the base polymer. It is also preferable to mix a silane coupling agent. Although the thickness of an adhesive layer is determined according to the adhesive force etc., it is 1-50 micrometers normally.

The first pressure-sensitive adhesive layer is preferably a diffusion pressure-sensitive adhesive layer containing a light diffusing agent. Examples of the light diffusing agent include the same light diffusing agent that the first protective layer may contain.
When the first pressure-sensitive adhesive layer is a diffusion pressure-sensitive adhesive layer, the content of the light diffusing agent is determined by the haze value required for the first protective layer in which the light diffusing agent is blended or the first protective layer. Although it is determined appropriately in consideration of the brightness of the liquid crystal display device to which the polarizing plate is applied, it is generally 3 to 50 parts by weight with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive composition, preferably Is 5 to 45 parts by weight.

  The haze of the pressure-sensitive adhesive layer is preferably 10 to 80% and more preferably 20 to 60% from the viewpoint of ensuring the brightness of the liquid crystal display device incorporating the polarizing plate and making the display image less likely to bleed or blur. .

  The pressure-sensitive adhesive composition may contain a pigment, a colorant, an antioxidant, an ultraviolet absorber and the like. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

[Adhesion between polarizer and second protective layer]
When a thermoplastic resin film is employed as the second protective layer, and the second protective layer and the polarizer are laminated, the polarizer and the second protective layer are usually adhesive or adhesive. Bonded with an agent. In bonding these films, plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment are performed on the bonding surface of the polarizer and / or the second protective layer in order to improve adhesion. Further, surface treatment such as solvent treatment may be appropriately performed. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  Examples of the pressure-sensitive adhesive used for bonding the polarizer and the second protective layer include the same pressure-sensitive adhesive as that used for the pressure-sensitive adhesive layer.

  As an adhesive used for bonding the polarizer and the second protective layer, a curable resin composition (active energy ray curable adhesive) containing an active energy ray curable compound or an adhesive component is used. An aqueous adhesive (aqueous adhesive) dissolved or dispersed in water can be used.

  As the active energy ray-curable adhesive, the same curable resin composition that forms the protective layer described above can be used. The curable resin composition used for forming the protective layer and the active energy ray-curable adhesive used for bonding the polarizer and the second protective layer may be the same or different. Good.

  Examples of the water-based adhesive include an adhesive composition containing a polyvinyl alcohol resin or a urethane resin as a main component.

  When the water-based adhesive contains a polyvinyl alcohol resin as a main component, the polyvinyl alcohol resin includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and acetic acid. Examples thereof include a copolymer of vinyl and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having ammonium groups. The polyvinyl alcohol resin contained in the water-based adhesive preferably has an appropriate degree of polymerization. For example, the viscosity is preferably 4 to 50 mPa · sec when an aqueous solution having a concentration of 4% by weight is used. 6 to 30 mPa · sec is more preferable.

  Moreover, it is also preferable that the water-based adhesive contains a modified polyvinyl alcohol resin. Examples of the modified polyvinyl alcohol resin include acetoacetyl group-modified polyvinyl alcohol resin, anion-modified polyvinyl alcohol resin, and cation-modified polyvinyl alcohol resin. When the water-based adhesive contains such a modified polyvinyl alcohol resin, the effect of improving the water resistance of the adhesive layer is easily obtained.

The water-based adhesive may contain two or more kinds of the modified polyvinyl alcohol-based resin, and also includes an unmodified polyvinyl alcohol-based resin (specifically, a complete or partially saponified product of polyvinyl acetate) and the above-mentioned It may contain both of the modified polyvinyl alcohol resin.
A commercial item can be used for the polyvinyl alcohol-type resin which comprises a water-system adhesive agent. For example, “PVA-117H”, “KL-318”, “KM-118” and “CM-318” sold by Kuraray Co., Ltd., “GOHSENOL” (registered by Nippon Synthetic Chemical Industry Co., Ltd.) Trademark) NH-20 "," Gosefimer (registered trademark) Z "series," Gosefimer (registered trademark) K-210 "and" Gosenar (registered trademark) T-330 "(all are trade names) Etc.

The water-based adhesive containing a polyvinyl alcohol resin as a main component may contain a crosslinking agent. When compounds capable of forming a crosslinking agent are listed by functional group, an isocyanate compound having at least two isocyanato groups (-NCO) in the molecule; an epoxy compound having at least two epoxy groups in the molecule; mono- or di-aldehyde; organic Titanium compounds; inorganic salts of divalent or trivalent metals such as magnesium, calcium, iron, nickel, zinc and aluminum; metal salts of glyoxylic acid; methylol melamine.
Among these crosslinking agents, epoxy compounds including water-soluble polyamide epoxy resins, aldehydes, methylol melamine, alkali metal or alkaline earth metal salts of glyoxylic acid, and the like can be preferably used.

  The crosslinking agent is preferably dissolved in water together with the polyvinyl alcohol resin to form an adhesive. However, since the amount of the crosslinking agent in the aqueous solution may be small, any crosslinking agent having a solubility of at least about 0.1% by weight in water can be used.

  Although content of a crosslinking agent is suitably designed according to the kind etc. of polyvinyl alcohol-type resin, it is 5-60 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resin, Preferably it is 10-10 weight part. 50 parts by weight. When the crosslinking agent is blended within this range, good adhesiveness can be obtained. If the amount of the cross-linking agent is too large, the reaction of the cross-linking agent proceeds in a short time and the adhesive tends to gel early, resulting in extremely short pot life and industrial use. It becomes difficult.

  The water-based adhesive may contain conventionally known appropriate additives such as a silane coupling agent, a plasticizer, an antistatic agent, and fine particles as long as the effects of the present invention are not impaired.

  The thickness of the adhesive layer obtained after drying or curing is usually 0.01 to 5 μm, but can be 1 μm or less when an aqueous adhesive is used. On the other hand, even when an active energy ray-curable adhesive is used, it is preferably 2 μm or less, and more preferably 1 μm or less. If the adhesive layer is too thin, the adhesion may be insufficient, and if the adhesive layer is too thick, the appearance of the polarizing plate may be poor.

[Functional resin layer]
In the polarizing plate of the present invention, a functional resin layer is laminated on the surface of the first pressure-sensitive adhesive layer opposite to the first protective layer side. The functional resin layer is preferably the outermost layer of the polarizing plate of the present invention. The functional resin layer refers to a layer containing a resin film that imparts various optical functions to the polarizing plate. Examples of such a resin film include a retardation film and a brightness enhancement film. The functional resin layer is preferably a brightness enhancement film.

  The retardation film is used for the purpose of compensation of retardation by a liquid crystal cell. Examples of the retardation film include a birefringent film made of a stretched resin film, a film in which a discotic liquid crystal or a nematic liquid crystal is oriented and fixed, and the liquid crystal layer formed on a film substrate. As the film substrate for supporting the liquid crystal layer, a cellulose-based film such as triacetyl cellulose is preferable.

  Examples of the resin that forms the birefringent film include polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefins such as polypropylene, polyethylene terephthalate, polyarylate, polyamide, and the like. The stretching may be performed by an appropriate method such as uniaxial or biaxial. Moreover, the birefringent film which controlled the refractive index of the thickness direction of a film by applying shrinkage force and / or extending | stretching force under adhesion | attachment with a heat-shrinkable film may be sufficient. Note that two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as broadening the bandwidth.

  The brightness enhancement film is incorporated in a liquid crystal display device for the purpose of improving brightness. As the brightness enhancement film, a reflective polarization separation sheet designed to produce anisotropy in reflectance by laminating a plurality of thin film films having different refractive index anisotropies, an alignment film of a cholesteric liquid crystal polymer, and the like Examples thereof include a circularly polarized light separating sheet in which an oriented liquid crystal layer is supported on a film substrate.

  In the polarizing plate of the present invention, one type of functional resin film may be laminated, or two or more types of functional resin films may be laminated. The order in laminating two or more types of functional resin films is not particularly limited.

[Production method of polarizing plate]
The polarizing plate of the present invention can be produced by a method including the following steps (i) to (iii). Note that the order of the step (i) and the step (ii) is not limited, and the step (ii) may be performed first, or these steps may be performed simultaneously.

Step (i) Step of laminating a first protective layer on one side of the polarizer,
Step (ii) Step of laminating the first pressure-sensitive adhesive layer on one side of the functional resin layer,
Step (iii) A step of bonding the first protective layer and the first pressure-sensitive adhesive layer.
Moreover, the polarizing plate of this invention can also be manufactured by laminating | stacking a 1st protective layer, a 1st adhesive layer, and a functional resin layer in this order on one surface of a polarizer. Below, although the method to manufacture the polarizing plate of this invention by the method of including process (i)-(iii) in this order is mainly demonstrated, a manufacturing method is not restrict | limited at all to this method.

[Step (i)]
In said process (i), a protective layer is laminated | stacked on the single side | surface of a polarizer layer by the process including the coating layer formation process to a base material, a coating layer bonding process, a coating layer hardening process, and a base material removal process.

  In the coating layer forming step on the substrate, first, a curable resin composition containing an active energy ray-curable compound that forms the first protective layer on the substrate is applied. Drying is performed as necessary, and a coating layer of the curable resin composition is provided on the substrate surface. Here, as the base material, in addition to the base material described above, a metal belt, a glass plate, or the like can also be used. Moreover, the surface by which the curable resin composition of a base material is coated may be given the peeling process previously. As a coating method of the curable resin composition containing the active energy ray-curable compound that forms the first protective layer, there is a method of coating with a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, or the like. Can be mentioned. As a method different from the above-described coating method, there is a method in which the curable resin composition is dropped between a polarizer and a substrate, and then pressed with a roll or the like to spread uniformly. In this method, it is possible to use metal or rubber as the material of the roll.

  In the coating layer bonding step, the coating layer formed on the substrate in the coating layer forming step and the polarizer are bonded to each other, and a laminated body in which the polarizer / the coating layer / the substrate is stacked in this order is manufactured. .

In the coating layer curing step, the curable resin composition is applied to the laminate by, for example, irradiating or heating active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams from the substrate side. The layer is cured to form a protective layer. When the curable resin composition for forming the protective layer is cured by irradiation with active energy rays, it is preferable to use a light source having a light emission distribution at a wavelength of 400 nm or less. Examples of such light sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. The light irradiation intensity of the active energy ray may vary depending on the composition to be irradiated, but the irradiation intensity in the wavelength region effective for activation of the photo radical polymerization initiator and / or the photo cationic polymerization initiator is 10 to 2500 mW / cm ^2. It is preferable that When the light irradiation intensity is less than 10 mW / cm ² , the reaction time becomes too long, and when it exceeds 2500 mW / cm ² , the heat radiated from the lamp and the polymerization of the curable resin composition or the adhesive composition are performed. Heat generation may cause yellowing of the curable resin composition or adhesive composition and deterioration of the polarizer.

Although the light irradiation time to the curable resin composition or the adhesive composition may be different for each composition to be irradiated, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 2500 mJ / cm ^2. It is preferable to set as follows. When this integrated light quantity is less than 10 mJ / cm ² , active species derived from the polymerization initiator are not sufficiently generated, and the resulting protective layer and adhesive layer may be insufficiently cured. On the other hand, if the integrated light quantity exceeds 2500 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity. In addition, it is preferable that irradiation of an active energy ray is performed in the range in which various performances, such as a polarization degree and transmittance | permeability of a polarizer, do not fall.

In the subsequent substrate removal step, the substrate on the protective layer is removed.
Moreover, as another method for performing the step (i), the curable resin composition for forming the first protective layer is directly applied to the polarizer, and irradiated with active energy rays or heated, thereby curable resin. A method of curing a coating layer made of the composition to form a first protective layer is also included.

[Step (ii)]
In step (ii), the first pressure-sensitive adhesive layer is laminated on the functional resin layer. First, lamination | stacking of a 1st adhesive layer can be performed by the method of using a peeling film, the method of apply | coating an adhesive composition on a functional resin layer, etc. The method of using the release film is to apply the adhesive composition to the release-treated surface of the release film that has been subjected to the release treatment to form an adhesive layer, and the resulting adhesive layer and functional resin layer Can be carried out by laminating. Moreover, the method of apply | coating an adhesive composition on a protective film can be performed by apply | coating an adhesive composition on a functional resin layer, and forming an adhesive layer. In this method, it is preferable to laminate a release film on the obtained pressure-sensitive adhesive layer to protect the surface of the first pressure-sensitive adhesive layer.

[Step (iii)]
In the step (iii), the first protective layer and the first pressure-sensitive adhesive layer are bonded to obtain a polarizing plate. In addition, it is preferable that the polarizing plate of this invention has a 2nd protective layer and a 2nd adhesive layer in this order further on the opposite side to the 1st protective layer side in a polarizer. When a curable resin composition is employed as the second protective layer, the second protective layer can be formed by the same method as the method for forming the first protective layer. Moreover, when employ | adopting a thermoplastic resin film as a 2nd protective layer, the said adhesive agent is apply | coated to the bonding surface of a thermosetting resin film and / or polarizer, and both are bonded by bonding. Two protective layers can be formed. Examples of the method for laminating the second pressure-sensitive adhesive layer include the same method as the method for laminating the first pressure-sensitive adhesive layer.

  The polarizing plate of the present invention can be applied to a liquid crystal cell or the like to constitute a liquid crystal display device. When a polarizing plate has a 2nd adhesive layer, it is preferable to laminate | stack and protect the said peeling film on the 2nd adhesive layer side until the time of the use. As a release film used here, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate is used as a base material, and a silicone-treated surface is bonded to the adhesive layer of the base film. And the like subjected to such a mold release treatment. When the release film is laminated on the polarizing plate, the release film may be peeled off from the polarizing plate and bonded to the liquid crystal cell.

  With reference to FIG. 1 (a) and FIG.1 (b), an example of the laminated constitution of the polarizing plate of this invention is demonstrated. Fig.1 (a) and FIG.1 (b) are schematic which shows an example of the polarizing plate of this invention. FIG. 1A shows a polarizing plate 10 having a polarizer 1, a first protective layer 21, a first pressure-sensitive adhesive layer 31, and a functional resin layer 4 in this order. FIG.1 (b) has the 2nd adhesive layer 32, the 2nd protective layer 22, the polarizer 1, the 1st protective layer 21, the 1st adhesive layer 31, and the functional resin layer 4 in this order. It is a polarizing plate.

  The haze of the polarizing plate of the present invention is preferably 10 to 80%, and preferably 20 to 60% from the viewpoint of ensuring the brightness of the liquid crystal display device incorporating the polarizing plate and making the display image less likely to bleed or blur. More preferred. The haze of the polarizing plate of the present invention can be adjusted by appropriately selecting the haze of members incorporated in the polarizing plate such as the first pressure-sensitive adhesive layer and the first protective layer.

[Liquid Crystal Display]
The polarizing plate of this invention can be used conveniently as a polarizing plate which comprises a liquid crystal display device. Usually, in a liquid crystal display device, a pair of polarizing plates are bonded to the viewing side and the light source side of the liquid crystal cell. At least one of the polarizing plates included in the liquid crystal display device of the present invention is the polarizing plate of the present invention. Furthermore, it is preferable that the polarizing plate of this invention is a polarizing plate arrange | positioned at the light source side among a pair of polarizing plates. In this case, a known polarizing plate can be used as the other polarizing plate. In the polarizing plate of the present invention, the first protective layer is provided between the polarizer and the first pressure-sensitive adhesive layer, whereby the adhesion can be increased.
Furthermore, the polarizing plate of the present invention having the second pressure-sensitive adhesive layer is useful because it can be directly attached to the glass substrate constituting the liquid crystal cell via the second pressure-sensitive adhesive layer. In order to laminate the polarizing plate having the second pressure-sensitive adhesive layer and the release film on the glass substrate, the release film is peeled off from the polarizing plate, and the exposed second pressure-sensitive adhesive layer surface is bonded to the surface of the glass substrate.
The liquid crystal display device of the present invention will be described in more detail with reference to FIG. FIG. 2 is a schematic view showing an example of the liquid crystal display device of the present invention. In the liquid crystal display device shown in FIG. 2, the backlight 8 and the polarizing plate 10 are bonded via the backlight tape 7. Moreover, the polarizing plate 10 and the liquid crystal cell 5 are bonded through the second pressure-sensitive adhesive layer 32 (not shown) of the polarizing plate 10. Note that the polarizing plate 6 shown in FIG. 2 may be the polarizing plate of the present invention or a known polarizing plate.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In the examples, parts and% indicating the amount used or content are based on weight unless otherwise specified.

  First, the example which prepared the curable resin composition is shown. The following compounds were used for the preparation of the curable resin composition.

<Active energy ray-curable compound>
“Celoxide (registered trademark) 2021P”: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, obtained from Daicel Chemical Industries, Ltd.
“OXT-221”: bis (3-ethyl-3-oxetanylmethyl) ether, obtained from Toagosei Co., Ltd.
“A-DCP”: tricyclodecane dimethanol diacrylate, obtained from Shin-Nakamura Chemical Co., Ltd.
Obtained from.

<Photocationic polymerization initiator>
"Adekaoptomer (registered trademark) SP-150": 4,4'-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator, obtained from ADEKA Corporation in the form of a propylene carbonate solution .

<Photoradical polymerization initiator>
“Irgacure (registered trademark) 907”: 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, obtained from BASF Japan K.K.
“Darocur (registered trademark) 1173”: 2-hydroxy-2-methyl-1-phenyl-propan-1-one, obtained from BASF Japan Ltd.

<Diffusion particles>
“Art Pearl (registered trademark) SE-006T”: acrylic beads, particle size 6 μm, obtained from Negami Industrial Co., Ltd.

<Other ingredients>
“SH710”: Silicone leveling agent, obtained from Toray Dow Corning Co., Ltd.

[Production Example 1] Preparation of curable resin compositions A to F The following components were mixed to prepare curable resin compositions A to F, respectively. Photocationic polymerization initiator "Adekaoptomer" SP-150 "uses a propylene carbonate solution, but in the following, it is indicated by its active ingredient amount.

<Curable resin composition A>
“Celoxide (registered trademark) 2021P” 70 parts “OXT-221” 30 parts “Adekaoptomer (registered trademark) SP-150” 2.25 parts “SH710” 0.2 part

<Curable resin composition B>
"Celoxide (registered trademark) 2021P" 35 parts "OXT-221" 15 parts "A-DCP" 50 parts "Adekaoptomer (registered trademark) SP-150" 1.13 parts "Darocur (registered trademark) 1173" 25 parts “SH710” 0.2 part

<Curable resin composition C>
"Celoxide (registered trademark) 2021P" 35 parts "OXT-221" 15 parts "A-DCP" 50 parts "Adekaoptomer (registered trademark) SP-150" 1.13 parts "Darocur (registered trademark) 1173" 25 parts "Art Pearl (registered trademark) SE-006T" 5 parts "SH710" 0.2 parts

<Curable resin composition D>
"Celoxide (registered trademark) 2021P" 35 parts "OXT-221" 15 parts "A-DCP" 50 parts "Adekaoptomer (registered trademark) SP-150" 1.13 parts "Darocur (registered trademark) 1173" 25 parts "Art Pearl (registered trademark) SE-006T" 10 parts "SH710" 0.2 parts

<Curable resin composition E>
"Celoxide (registered trademark) 2021P" 35 parts "OXT-221" 15 parts "A-DCP" 50 parts "Adekaoptomer (registered trademark) SP-150" 1.13 parts "Darocur (registered trademark) 1173" 25 parts "Art Pearl (registered trademark) SE-006T" 20 parts "SH710" 0.2 parts

[Production Example 2] Production of polarizer A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 20 μm was uniaxially stretched about 4 times in a dry process, and the tension state was maintained. The sample was immersed in pure water at 40 ° C. for 1 minute, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 10/100 at 28 ° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 7.5 / 100 at 68 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 10 ° C. for 20 seconds and then dried at 65 ° C. to prepare a polarizer in which iodine was adsorbed and oriented on a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizer was 7 μm.

  Next, the example which prepared the adhesive agent is shown. The following compounds were used for polyvinyl alcohol and epoxy crosslinking agent.

<Polyvinyl alcohol>
"Kuraray Poval (registered trademark) KL318": carboxyl group-modified polyvinyl alcohol, obtained from Kuraray Co., Ltd.

<Epoxy-based crosslinking agent>
“Smilease Resin (registered trademark) 650”: water-soluble polyamide epoxy resin (aqueous solution with a solid content of 30%), obtained from Sumika Chemtex Co., Ltd.

[Production Example 3] Preparation of water-based adhesive The following components were mixed to prepare a water-based adhesive. The epoxy-based cross-linking agent "Smileze Resin 650" is an aqueous solution. The amount of active ingredients is displayed.

<Water-based adhesive>
"Pure water" 100 parts "Kuraray Poval (registered trademark) KL318" 1.8 parts "Smiles Resin (registered trademark) 650" 0.9 parts

[Production Example 4] Production of Polarizing Plate A A water-based adhesive prepared in Production Example 3 was applied to one side of the polarizer produced in Production Example 2, and a protective layer [Konica Minolta Opto Corp. ), KC2UA, thickness 25 μm, referred to as second protective layer], pure water is applied to the other surface, and a polyethylene film [Toray Film Processing Co., Ltd., Tretec (registered trademark) 7332, thickness 30 μm] was pasted. After drying this at 60 degreeC for 3 minutes, the polyethylene-type film was peeled off and the polarizing plate A which has a 2nd protective layer on one side was produced.

[Example 1]
(1) Production of polarizing plate The curable resin composition A prepared in Production Example 1 was applied to one side of a 50 μm thick cycloolefin film [trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.] using a bar coater. Coating was performed so that the film thickness after curing was about 5 μm. The coated surface was bonded to the polarizer side of the polarizing plate A produced in Production Example 4 to produce a laminate. The laminate is irradiated with ultraviolet rays from the cycloolefin film side with a belt conveyor (using a “D bulb” manufactured by Fusion UV Systems) so that the integrated light quantity becomes 500 mJ / cm ^2, and is cured. The resin composition was cured, and then the cycloolefin film was peeled from the laminate. Thus, a polarizing plate composed of the first protective layer (cured product of the curable resin composition) / polarizer / adhesive layer / second protective layer was produced.

  Next, on the first protective layer side of the polarizing plate produced in (1), a layer of 5 μm thick acrylic adhesive A (adhesive layer A, haze value 0%) is used as the first adhesive layer. After providing, on the side opposite to the first protective layer of the acrylic pressure-sensitive adhesive, a brightness enhancement film having a thickness of 26 μm [trade name “Advanced Polarized Film, Version 3 (APF-V3)” manufactured by 3M Co., Ltd.]] Were laminated. In addition, the corona process was given before bonding except the bonding surface of a 1st protective layer and a 1st adhesive layer.

[Examples 2 to 5]
In Example 1, a polarizing plate was produced in the same manner as in Example 1 except that the curable resin composition shown in Table 1 was changed.

[Example 6]
In Example 2, a polarizing plate was produced in the same manner as in Example 2 except that the diffusion adhesive layer B having a thickness of 15 μm and a haze of 36% was used as the first adhesive layer.

[Example 7]
In Example 3, a polarizing plate was produced in the same manner as in Example 3, except that the diffusion adhesive layer B was used as the first adhesive layer.

[Example 8]
In Example 4, a polarizing plate was produced in the same manner as in Example 4 except that the diffusion adhesive layer B was used as the first adhesive layer.

[Example 9]
In Example 5, a polarizing plate was produced in the same manner as in Example 5 except that the diffusion adhesive layer B was used as the first adhesive layer.

[Example 10]
In Example 2, a polarizing plate was produced in the same manner as in Example 2 except that the diffusion adhesive layer C having a thickness of 15 μm and a haze of 50% was used as the first adhesive layer.

[Example 11]
In Example 3, a polarizing plate was produced in the same manner as in Example 3 except that the diffusion adhesive layer C was used as the first adhesive layer.

[Example 12]
In Example 4, a polarizing plate was produced in the same manner as in Example 4 except that the diffusion adhesive layer C was used as the first adhesive layer.

[Example 13]
In Example 5, a polarizing plate was produced in the same manner as in Example 5 except that the diffusion adhesive layer C was used as the first adhesive layer.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the first protective layer was not laminated, that is, the first pressure-sensitive adhesive layer was laminated directly on the polarizer.

[Comparative Example 2]
A polarizing plate was produced in the same manner as in Example 9, except that the first protective layer was not laminated, that is, the first pressure-sensitive adhesive layer was laminated directly on the polarizer.

[Comparative Example 3]
A polarizing plate was produced in the same manner as in Example 13, except that the first protective layer was not laminated, that is, the first pressure-sensitive adhesive layer was laminated directly on the polarizer.

<Evaluation of optical durability of polarizing plate>
On the side of the polarizing plate produced in (1) opposite to the polarizer of the second protective layer, an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was provided as the second pressure-sensitive adhesive layer. Under the present circumstances, the corona treatment was given to each bonding surface of a 2nd protective layer and a 2nd adhesive layer. Then, it is cut into a size of 60 mm × 110 mm so that the direction parallel to the absorption axis of the polarizer is a long side, and alkali-free glass [trade name “EAGLE XG manufactured by Corning, Inc. "]". The sample was autoclaved for 1 hour at a temperature of 50 ° C. and a pressure of 5 kg / cm ² (490.3 kPa), and then left for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 55%. This sample was left in an environment at a temperature of 65 ° C. and a relative humidity of 90% for 100 hours, and the change in appearance was observed. At that time, the case where there was no change was indicated as ◯, the case where peeling or floating was observed was indicated as ×, and the result was shown in the column of “Damp heat durability” in Table 1.

<Haze evaluation of polarizing plate>
The polarizing plate produced in the above (1) is made to be incident from the second protective layer side by a haze meter (HM-150 type, manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS K 7136. The haze of the polarizing plate was measured.

  From Table 1, in Comparative Examples 1 to 3 without the first protective layer, peeling occurred in a moist heat environment at a temperature of 65 ° C. and a relative humidity of 90%, whereas the examples having the first protective layer are It can be seen that none of them is peeled off. Moreover, it turns out that a haze is adjustable together with a diffusion adhesive layer by putting particles in the first protective layer.

  According to the present invention, it is a thin polarizing plate having no protective film between the pressure-sensitive adhesive layer and the polarizer, and the adhesion between the protective layer and the pressure-sensitive adhesive layer formed on the surface of the polarizer is strong, It is possible to provide a polarizing plate with improved durability in a humid heat environment and a liquid crystal display device having the polarizing plate.

1: Polarizer, 21: First protective layer, 22: Second protective layer, 31: First pressure-sensitive adhesive layer, 32: Second pressure-sensitive adhesive layer, 4: Functional resin film, 10: Polarizing plate 11: Liquid crystal display device, 5: Liquid crystal cell, 6: Polarizing plate, 7: Backlight tape, 8: Backlight unit

Claims (13)

A functional resin layer, a first pressure-sensitive adhesive layer, a first protective layer that is a cured product of a curable resin composition, and a polarizer are laminated in this order,
The curable resin composition contains an active energy ray curable compound.   The polarizing plate according to claim 1, wherein the curable resin composition contains a light diffusing agent.   The polarizing plate according to claim 1, wherein the first pressure-sensitive adhesive layer is a diffusion pressure-sensitive adhesive layer.   The polarizing plate according to claim 1, wherein the functional resin layer is a layer having a brightness enhancement film.   The polarizing plate according to claim 1, wherein the active energy ray-curable compound includes a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.   The polarizing plate according to any one of claims 1 to 5, wherein the active energy ray-curable compound contains a cationic polymerizable compound.   The polarizing plate according to claim 6, wherein the cationically polymerizable compound includes a compound having at least one oxirane ring in the molecule.   The polarizing plate according to claim 1, wherein the first pressure-sensitive adhesive layer has a thickness of 0.1 to 10 μm.   The polarizing plate according to claim 1, further comprising a second protective layer on a side opposite to the side on which the first protective layer of the polarizer is laminated.   The polarizing plate according to claim 9, wherein the second protective layer is a thermoplastic resin film.   The polarizing plate of Claim 9 or 10 which has a 2nd adhesive layer in the opposite side to the side with which the polarizer of the 2nd protective layer was laminated | stacked.   The polarizing plate of Claim 11 by which the peeling film was laminated | stacked on the surface on the opposite side to the side by which the 2nd protective layer of the 2nd adhesive layer was laminated | stacked.   A liquid crystal display device comprising the polarizing plate according to claim 1 and a liquid crystal cell.

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