KR20150136605A - Polarizing plate - Google Patents

Abstract

The polarizing plate of the present invention is a polarizer comprising a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and aligned, and a protective film including a transparent resin is bonded to the polarizer through an adhesive, wherein the adhesive has a cationic polymerizable functional group A photo-curable component containing a compound, a photo-cationic polymerization initiator, and a photo-base generator. The polarizing plate of the present invention has good heat resistance.

Description

POLARIZING PLATE

The present invention relates to a polarizing plate in which a protective film containing a transparent resin is bonded to a polarizer in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin.

The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate is usually inserted into a liquid crystal display device in a state in which a protective film is laminated on both sides of the polarizer. It is also known to provide a protective film on only one side of the polarizer. In most cases, a layer having a different optical function is bonded not only as a simple protective film to the other side but also as a protective film.

As a method for producing a polarizer, there is widely known a method in which a uniaxially stretched polyvinyl alcohol based resin film dyed with a dichroic dye is subjected to boric acid treatment, washed with water and then dried. The polarizer thus obtained is usually subjected to a protection film immediately after washing with water and drying. This is because the polarizer after drying has a weak physical strength, and once it is wound, it tends to be torn in the processing direction. Therefore, the dried polarizer is usually applied with an aqueous adhesive immediately, and then the protective film is simultaneously bonded to both surfaces through the adhesive. As a protective film, an acetylcellulose resin film having a thickness of 10 to 120 mu m is usually used.

On the other hand, since the acetylcellulose-based resin film has high moisture permeability, the polarizing plate to which this film is applied as a protective film has problems such as deterioration under the conditions of, for example, a temperature of 70 DEG C and a relative humidity of 90%. Therefore, a method of solving such a problem by using a resin having a lower moisture permeability than an acetylcellulose-based resin as a protective film has been proposed. For example, a cycloolefin-based resin is known to be a protective film. Specifically, it is described in Patent Document 1 that a thermoplastic saturated norbornene resin film is laminated on at least one surface of a polarizer.

When such a resin film having low moisture permeability is bonded to the above-described polarizer by a conventional apparatus, an aqueous adhesive using water as a main solvent, for example, a polyvinyl alcohol aqueous solution, is used to bond the resin film, Called wet lamination, there is a problem that sufficient adhesive strength can not be obtained or appearance becomes poor. This is because the resin film having a low moisture permeability is generally hydrophobic rather than the acetylcellulose resin film, but the water as a solvent can not be sufficiently dried because of low moisture permeability.

Thus, Patent Document 2 proposes that a polarizer made of a polyvinyl alcohol-based resin and a thermoplastic saturated norbornene-based resin film are bonded by a polyurethane-based adhesive agent. However, the polyurethane-based adhesive has a problem that not only time is required for curing but also adhesion is not necessarily sufficient.

Furthermore, as an adhesive which gives a high adhesive force between a polarizer made of a resin film having a low water vapor permeability and a polyvinyl alcohol-based resin, and a resin film having high moisture permeability such as an acetylcellulose resin and the above polarizer, There is an attempt to use Mars Adhesive. For example, Patent Document 3 discloses an adhesive mainly comprising an epoxy compound that does not contain an aromatic ring. The adhesive is cured by irradiation of active energy rays, specifically, cationic polymerization by irradiation of ultraviolet rays, It has been proposed to bond the film. Patent Document 4 discloses a technique of using a photocurable adhesive in which an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group are combined and a photocationic polymerization initiator is further blended to bond the polarizer and the protective film.

The adhesives disclosed in Patent Documents 3 and 4 are intended to be cured by cationic polymerization, so that a photo cationic polymerization initiator, that is, a photoacid generator that generates an acid upon irradiation with light, is blended.

However, in the adhesives cured by the photocationic polymerization disclosed in the above Patent Documents 3 and 4, since the acid generated from the photocationic polymerization initiator by the irradiation of ultraviolet rays remains after polymerization and curing, There is a problem that the polarizer is deteriorated by heat such as a test and discolored.

[Patent Document 1] Japanese Patent Application Laid-open No. 6-51117 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2000-321432 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-245925 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-257199

Disclosure of the Invention A problem to be solved by the present invention is to provide a polarizing plate which is excellent in heat resistance and does not readily undergo discoloration of a polarizer due to heat.

The present inventors have found that a polarizing plate obtained by bonding a polarizer and a protective film including a transparent resin to a photo-curing composition for forming an adhesive by blending a predetermined amount of a thermal base generator with the polarizing plate is excellent in heat resistance, The discoloration of the dye is inhibited.

That is, the present invention relates to a polarizer comprising a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and aligned, and a protective film including a transparent resin is bonded to the polarizer through an adhesive. The adhesive is a compound having a cationically polymerizable functional group A photo-curable component comprising a photo-curable component, a photo-cationic polymerization initiator, and a photo-base generator.

It is preferable that the above-mentioned adhesive contains 0.01 to 20 parts by weight of the above-mentioned heat base generating agent per 100 parts by weight of the photocurable component.

The protective film bonded to one surface of the polarizer through the adhesive is a cycloolefin resin film and the protective film bonded to the other surface of the polarizer through the adhesive is made of acetylcellulose It is preferable that a pressure-sensitive adhesive layer having antistatic function is formed on the surface of the acetylcellulose-based resin film opposite to the surface bonded to the polarizer.

The polarizing plate of the present invention is a polarizing plate in which an adhesive for bonding a polarizer and a protective film comprising a transparent resin is a photo-curable composition comprising a photo-curable component containing a compound having a cationic polymerizable functional group, a photo cationic polymerization initiator, So that good heat resistance is exhibited.

A polarizing plate according to the present invention is obtained by bonding a protective film containing a transparent resin through an adhesive to a polarizer in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin. Hereinafter, the respective members constituting the polarizing plate will be described in order.

[Polarizer]

A polarizer is a film having a function of converting natural light into linearly polarized light, which is formed by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film. The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. 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 copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol-based resin is usually in the range of 1,000 to 10,000, preferably 1,500 to 10,000. Such a film of a polyvinyl alcohol-based resin is used as a raw film of a polarizer. The polyvinyl alcohol resin can be formed by a known method.

The polarizer of the present invention is obtained by uniaxially stretching a polyvinyl alcohol-based resin film formed as described above, dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye (dyeing treatment) , A polyvinyl alcohol resin film on which a dichroism dye is adsorbed is treated with an aqueous solution of boric acid (boric acid treatment), followed by treatment with aqueous solution of boric acid (water treatment) and finally drying. The thus obtained polarizer in which the dichroic dye is adsorbed and aligned is a polarizing plate obtained by bonding a protective film to be described later.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing with a dichroic dye or simultaneously with dyeing with a dichroic dye or may be performed after dyeing with a dichroic dye. In the case where uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural steps. In order to perform uniaxial stretching, the film may be stretched by passing between rolls having different peripheral velocities, or may be stretched by a method of sandwiching between rolls. In addition, dry stretching may be performed in the atmosphere, or wet stretching may be performed in the state of being swollen by a solvent. The final draw ratio of the polyvinyl alcohol-based resin film is usually about 4 to 8 times.

In order to dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, a polyvinyl alcohol-based resin film may be dipped in an aqueous solution containing a dichroic dye. As the dichroic dye, iodine or a dichroic dye is specifically used.

When iodine is used as the dichroic dye, a method is generally employed in which a polyvinyl alcohol-based resin film is dipped in an aqueous solution containing iodine and potassium iodide for dyeing.

The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution is usually about 20 to 40 占 폚, and the immersion time in the aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of dying and dyeing the polyvinyl alcohol resin film into an aqueous solution containing a water-soluble dichroic dye is generally adopted. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ^{-3 to} 1 × 10 ^-2 parts by weight per 100 parts by weight of water. The aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 占 폚, and the immersion time in the aqueous solution is usually about 30 to 300 seconds.

The boric acid treatment after dyeing with the dichroic dye is carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution of boric acid. The content of boric acid in the aqueous solution of boric acid is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous solution of boric acid contains potassium iodide. The content of potassium iodide in the aqueous solution of boric acid is usually about 2 to 20 parts by weight, preferably 5 to 15 parts by weight, per 100 parts by weight of water. The immersing time of the film in the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably 150 seconds or more, more preferably 200 seconds or more, preferably 600 seconds or less, further preferably 400 seconds or less . The temperature of the boric acid aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚.

The polyvinyl alcohol-based resin film after treatment with boric acid is usually washed with water. The water washing treatment is carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. After washing with water, drying is carried out to obtain a polarizer. The temperature of the water in the water washing treatment is usually about 5 to 40 캜, and the immersing time is usually about 2 to 120 seconds. Drying to be performed thereafter is usually carried out using a hot-air dryer or a far-infrared heater. The drying temperature is usually 40 to 100 ° C, and the drying time is usually 120 to 600 seconds.

Thus, a polarizer made of a polyvinyl alcohol-based resin film in which iodine or a dichroic dye is adsorbed and oriented is produced. The thickness of the polarizer may be about 10 to 40 mu m.

[Protection film]

The polarizing plate of the present invention is obtained by bonding a film made of a transparent resin as a protective film to the above-described polarizer. When the protective film is bonded to both surfaces of the polarizer, the two films bonded to both surfaces may be of the same kind or of different kinds. As the protective film, a cycloolefin resin film, a polyester resin film, an acrylic resin film, a polycarbonate resin film, a polysulfone resin film, an alicyclic polyimide resin film, an acetylcellulose resin film, have.

In the present invention, it is preferable that the protective film bonded to one surface of the polarizer is a cycloolefin-based resin film and the protective film bonded to the other surface is an acetylcellulose-based resin film. The cycloolefin-based resin constituting the cycloolefin-based resin film can be obtained, for example, by copolymerizing a structural unit of a cyclic olefin (cycloolefin) represented by norbornene or tetracyclododecene (also known as dimethano-octahydronaphthalene) Is a thermoplastic resin. The cycloolefin resin may be a hydrogenated product of a ring-opening polymer of the cycloolefin described above or a ring-opening copolymer using two or more cycloolefins. In addition to the hydrogenated product of the ring-opened copolymer using a cycloolefin, a chain olefin, Or an aromatic compound having a bond. A polar group may be introduced into the cycloolefin-based resin.

Suitable commercially available products can be used for the cycloolefin-based resin. For example, "TOPAS" produced by TOPAS ADVANCED POLYMERS GmbH of Germany, "TOPAS" sold by Polyplastics Co., Ltd., "Aton" sold by JSR Corp., and "Zeon" sold by Nippon Zeon Co., ZEONOR ", "ZEONEX ", and" APEL "sold by Mitsui Kagaku Co., Ltd. (all trade names).

The cycloolefin resin is formed into a film. For the film formation, a known film forming method such as a solvent casting method or a melt extrusion method is suitably used. A cycloolefin-based resin film that has been formed, or a cycloolefin-based resin film that is further stretched to impart a phase difference is also commercially available. Specific examples thereof include "Arton film" sold by JSR Corporation, "Zeonoah film" sold by Nippon Zeon Co., Ltd., "Essina" sold by Sekisui Chemical Co., Ltd., and " SCA40 "(all trade names), and the like.

The acetylcellulose-based resin constituting the acetylcellulose-based resin film is a resin in which at least a part of the hydroxyl groups in the cellulose are converted into an acetic acid ester, and a part of the resin is esterified and partly esterified with another acid It may be an ester. Specific examples of the acetylcellulose-based resin include triacetylcellulose, diacetylcellulose, cellulose acetate propionate, and cellulose acetate butyrate.

The bonding film may be subjected to adhesion (easy adhesion) treatment such as saponification treatment, corona treatment, primer treatment, anchor coating treatment and the like before the bonding to the polarizer.

The protective film may have various treatment layers such as a hard coat layer, an antireflection layer, and an antiglare layer on the surface opposite to the bonding surface to the polarizer. The thickness of the protective film is usually in the range of about 5 to 200 mu m, preferably 10 mu m or more, more preferably 120 mu m or less, and furthermore preferably 85 mu m or less.

[glue]

In the present invention, an adhesive is used for bonding the polarizer and the protective film as described above. This adhesive is obtained by irradiating an active energy ray to a photo-curable composition containing a photo-curable component containing a compound having a cationically polymerizable functional group, a photo cationic polymerization initiator, and a photoacid generator. The components of the photocurable composition for forming the adhesive will be described in turn.

(Photocurable component)

The compound having a cationically polymerizable functional group means a compound or oligomer which is composed of an epoxy compound, an oxetane compound or a vinyl ether compound and which undergoes polymerization reaction by irradiation with ultraviolet rays or the like to cure.

Examples of the photocurable epoxy compound include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, aliphatic epoxy compounds, and the like.

First, the alicyclic epoxy compound will be described. This is a compound having at least one epoxy group directly bonded to the alicyclic ring in the molecule. For example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate, ethylenebis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-cyclohexylmethyl) adipate, diethyleneglycol bis 3,4-epoxycyclohexylmethyl ether), ethylene glycol bis (3,4-epoxycyclohexylmethyl) ether, and the like. Of these compounds, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate is preferable from the viewpoints of curability and adhesiveness.

Next, the aromatic epoxy compound will be described. This is a compound having an aromatic ring and an epoxy group in the molecule. Specific examples thereof include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S, or oligomers thereof; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolac epoxy resin and hydroxybenzaldehyde phenol novolac epoxy resin; Polyfunctional epoxy compounds such as glycidyl ether of 2,2 ', 4,4'-tetrahydroxydiphenylmethane and glycidyl ether of 2,2', 4,4'-tetrahydroxybenzophenone ; And polyfunctional epoxy resins such as epoxidized polyvinyl phenol.

Hydrogenated epoxy compounds will be described. The nuclear hydrogen addition of the above aromatic epoxy compound becomes a hydrogenated epoxy compound. These are polyhydric alcohols, typically hydrogenated bisphenols, obtained by selectively hydrogenating an aromatic polyhydroxy compound, typically a bisphenol, as a raw material of the corresponding aromatic epoxy compound in the presence of a catalyst and under pressure. And then reacting it with epichlorohydrin to obtain chlorohydrin ether, which is then subjected to ring closure in the molecule with an alkali.

Next, the aliphatic epoxy compound will be described. The aliphatic epoxy compounds include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specific examples thereof include diglycidyl ether of neopentyl glycol, diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, trimethylol propane , Diglycidyl ether of polyethylene glycol, diglycidyl ether of propylene glycol, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin, one or more alkylene oxides (such as ethylene oxide, Propylene oxide), and polyglycidyl ether of polyether polyol. Among these compounds, from the viewpoint of adhesiveness, it is preferable to use diglycidyl ether of neopentyl glycol, diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol and the like.

Next, the oxetane compound will be described. This is a compound containing at least one oxetanyl group in the molecule. Specific examples thereof include 3-ethyl-3-hydroxymethyloxetane (also referred to as oxetane alcohol), 2-ethylhexyloxetane, 1,4-bis [{(3-ethyloxetan- (3-ethyloxetan-3-yl) methoxy} methyl] oxetane, 3-ethyl-3- (phenoxymethyl) benzene (also referred to as xylylene bisoxetane) Methyl) oxetane, 3- (cyclohexyloxy) methyl-3-ethyl oxetane, and the like. By including these compounds, the curing rate and adhesion can be improved.

The vinyl ether compound will be described. This is a compound containing at least one vinyloxy group in the molecule. Specific examples thereof include n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, 1,4-butanediol divinyl ether, neopentyl Cyclohexanedimethanol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, dipropylene glycol divinyl ether, trimethylolpropane trivinyl ether, 2-hydrohexylethyl Hexane dimethanol monovinyl ether, diethylene glycol monovinyl ether, dipropylene glycol monovinyl ether, acetoxyethyl vinyl ether, acetoxybutyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxybutyl vinyl ether, (Acetoxymethyl) cyclohexanemethanol vinyl ether, diethylene glycol vinyl ether acetate, glycidyloxyethyl vinyl ether, glycidyloxybutyl vinyl ether, 2 - [(4-vinyloxy) Methylcyclohexyl) methoxy methyl] ethoxymethyl oxirane, 2- [{2- (vinyloxy)} 2] and the like oxirane. By including these compounds, it is possible to achieve an improvement in the viscosity and the curing rate in the adhesive.

The compounds having a cationically polymerizable functional group as exemplified above may be used alone or in combination of a plurality of compounds. However, from the viewpoints of weatherability, curing rate and adhesiveness, at least an alicyclic epoxy compound and an aliphatic epoxy compound .

When an alicyclic epoxy compound and an aliphatic epoxy compound are used in combination, these blend ratios are preferably 20 to 95% by weight based on the total amount of photo-curable components including a compound having a cationically polymerizable functional group, It is preferable that the aliphatic epoxy compound is 5% by weight or more. When 20% by weight or more of an alicyclic epoxy compound, especially an alicyclic diepoxy compound, is incorporated in the total photo-curable component, the storage elastic modulus of the cured product at 80 캜 is increased. Therefore, The polarizer is not easily broken in the polarizing plate. Further, when the aliphatic epoxy compound is blended in an amount of 5% by weight or more based on the total amount of the cationic polymerizable compound, adhesion between the polarizer and the protective film is further improved.

On the other hand, if the amount is too large, the storage elastic modulus of the cured product lowers and the polarizer tends to be broken. Therefore, it is preferable that the amount of the photo-curable component is 70 wt% or less. Further, the total of the blending ratios of the alicyclic epoxy compound and the aliphatic epoxy compound does not exceed 100% by weight.

(Gwangyang Ion Polymerization Initiator)

In the present invention, the photocurable component described above is cured by cationic polymerization by irradiation of an active energy ray to form an adhesive layer, so that a photocationic polymerization initiator is incorporated in the photocurable composition. The cationic ionic polymerization initiator generates a cationic species or a Lewis acid by irradiation of an active energy ray such as visible light, ultraviolet ray, X-ray or electron beam to initiate polymerization reaction of the cationic ion-curable component. Since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with a cationic ion-curable component. Examples of the compound capable of generating a cationic species or a Lewis acid by irradiation with an active energy ray include an onium salt such as an aromatic iodonium salt and an aromatic sulfonium salt, an aromatic diazonium salt, and an iron-arene complex.

The aromatic iodonium salt is a compound having a diaryliodonium cation, and the diaryliodonium cation is typically a diphenyliodonium cation. The aromatic sulfonium salt is a compound having a triarylsulfonium cation, and as the triarylsulfonium cation, typically a triphenylsulfonium cation or a 4,4'-bis (diphenylsulfonium) diphenylsulfide cation And the like. The aromatic diazonium salt is a compound having a diazonium cation, and as the diazonium cation, a benzene diazonium cation is typically exemplified. In addition, the iron-arene complex is typically a cyclopentadienyl iron (II) arene cation complex.

The above-mentioned cations are paired with anions to constitute a photocationic polymerization initiator. Examples of the anions constituting the photocationic polymerization initiator include hexafluorophosphate anion PF ₆ ^- , hexafluoroantimonate anion SbF ₆ ^- , pentafluorohydroxyantimonate anion SbF ₅ (OH) ^- , hexa Fluoroarsenate anion AsF ₆ ^- , tetrafluoroborate anion BF ₄ ^- , tetrakis (pentafluorophenyl) borate anion B (C ₆ F ₅ ) ₄ ^- and the like.

Of these photocationic polymerization initiators, aromatic sulfonium salts in particular have an ultraviolet ray absorption property even in the wavelength region around 300 nm, and thus can give a cured product excellent in curability and having good mechanical strength and adhesive strength, .

Various photocatalytic ion polymerization initiators are commercially available. Examples of commercially available products include "CPI" series sold by Sana Pro Co., "CYRACURE UVI" series sold by Dow Chemical Company, "ADEKA Optomer SP" series sold by ADEKA Co., , "IRGACURE" series (which is classified as a cationic photopolymerization initiator) sold by BASF Corporation of Germany, "SANEID SI" series sold by SANSHIN KAGAKU KOGYO Co., , And "UVACURE 1590" (all trade names).

The blending amount of the photocationic polymerization initiator is preferably 0.5 to 10 parts by weight based on 100 parts by weight of a photocurable component containing a compound having a cationically polymerizable functional group. By adding at least 0.5 part by weight of a cationic polymerization initiator per 100 parts by weight of the photocurable component, the cationic polymerizable compound can be sufficiently cured, and a high mechanical strength and adhesive strength can be imparted to the resulting polarizing plate. On the other hand, when the amount is increased, the amount of the acid remaining in the cured product increases, which may lower the heat resistance of the polarizer. Therefore, the blending amount of the photocationic polymerization initiator 10 parts by weight or less per 100 parts by weight of the component. This blending amount is preferably 1 part by weight or more, and more preferably 6 parts by weight or less.

(Thermal nucleating agent)

In the present invention, in order to solve the problem of deterioration of the polarizer by the above-mentioned acid, a thermal base generator is added to the photo-curable composition comprising the photo-curable component and the photo-cation polymerization initiator. A heat nucleating agent means a compound which generates a base by heat. This thermal base generating agent generates a base when heat is externally applied to the polarizing plate by sunlight or a backlight and by a high temperature environment such as a heat resistance test of a polarizing plate. Since this base neutralizes an acid derived from a photo cationic polymerization initiator or the like remaining in a cured product (adhesive) of the photo-curing composition applied to the polarizing plate, discoloration of the polarizer in a high temperature environment can be suppressed.

For example, a 1,8-diazabicyclo (5.4.0) undecene-7 phenol salt used as a thermal base generator in a later-described example generates a tertiary amine by heat, and this amine reacts with an acid.

By blending the thermal base generator with the photo-curable composition forming the adhesive, the polarizing plate in the high temperature environment is suppressed and the heat resistance is excellent, as compared with the case where the thermal base generator is not blended.

Hereinafter, the thermal base generator will be described. Photocatalytic ion polymerization is put to practical use from the point of being not inhibited by oxygen as compared with photo radical polymerization, but the acid generated even after curing remains in the adhesive layer. Particularly, in the polarizing plate, if the acid remains in the adhesive layer, it acts as a catalyst, causing the polarizing plate to be discolored by the polyenol of the polyvinyl alcohol-based resin constituting the polarizer. In the present invention, discoloration of the polarizing plate by an acid can be prevented even after curing by blending a photo-curable composition containing a cationically polymerizable functional group and a photo-curable component containing a photo-cation polymerization initiator.

The thermal base generator used in the present invention may be any compound that generates a base by heating. Examples of the thermal base generator include carbamate derivatives such as 2- (4-biphenyl) -2-propyl carbamate and 1,1-dimethyl-2-cyanoethyl carbamate, N'-trimethyl urea and the like, dihydropyridine derivatives such as 1,4-dihydronichotinamide, dicyandiamide, salts formed with acids and bases such as organic and inorganic salts, and the like.

Among the above-mentioned heat-base generators, salts composed of acids and bases are particularly preferred because of their excellent stability in composition, storage stability in adhesives, and cost. Among them, from the viewpoint of compatibility with the photo-curable component, it is preferably a salt of an acid and an amine compound, more preferably an organic salt of an organic acid and an amine compound.

The acid in the thermal base generator includes an organic acid and an inorganic acid. Examples of the organic acid include monoalkyl carbonic acid such as carboxylic acid, methyl carbonate and ethyl carbonate; Aromatic hydroxy compounds such as phenol, cresol, catechol and naphthol; And sulfonic acids such as octylbenzenesulfonic acid, butylbenzenesulfonic acid, toluenesulfonic acid, benzenesulfonic acid and methanesulfonic acid.

Examples of the carboxylic acid include saturated fatty acids such as formic acid, acetic acid, 2-ethylhexanoic acid and valeric acid; But are not limited to, acrylic acid, crotonic acid, methacrylic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, Unsaturated carboxylic acids such as toluene and the like; Chloroacetic acid, chloroacetic acid, cyanoacetic acid, dichloroacetic acid, trichloroacetic acid, trimethylacetic acid, fluoroacetic acid, bromoacetic acid, methoxyacetic acid, mercaptoacetic acid, iodoacetic acid, vinylacetic acid, oxaloacetic acid, phenylacetic acid and phenoxyacetic acid Substituted acetic acid; Dicarboxylic acids such as acetic acid, malic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid and sebacic acid; Hydroxycarboxylic acids such as glycolic acid, lactic acid, citric acid, d-tartaric acid, meso tartaric acid, ascorbic acid and mandelic acid; Ketocarboxylic acids such as pyruvic acid and levulic acid; And halocarboxylic acids such as 2-chloropropionic acid and 3-chloropropionic acid.

Examples of the inorganic acid include halogen acids such as hydrochloric acid, hydrofluoric acid and bromic acid, carbonic acid forming a carbonate or hydrogen carbonate, perhalogenous acids such as perchloric acid and perbromic acid, sulfuric acid and phosphoric acid.

Among them, organic acids are preferable, and carboxylic acids, aromatic hydroxy compounds, and sulfonic acids are more preferable, saturated fatty acids and aromatic hydroxy compounds are more preferable, and formic acid, acetic acid, 2-ethylhexanoic acid, and phenol are particularly preferable Do.

Examples of amine compounds constituting the thermal base generator include primary amines, secondary amines, tertiary amines, aliphatic unsaturated amines and aromatic amines. In addition, the amine compound in the thermal base generator forms a salt with an acid, so that it does not become a quaternary ammonium salt.

The above primary amines may be aliphatic amines including alicyclic amines, aromatic amines, and amines having other reactive functional groups. These may be monoamines having one nitrogen atom derived from an amino group in one molecule, or two or more nitrogen atoms such as diamine and triamine.

Examples of the aliphatic amines include saturated aliphatic amines such as monomethylamine, monoethylamine, monopropylamine, monoisopropylamine, monobutylamine, mono-tert-butylamine, monopentylamine, monohexylamine and monoheptylamine; Unsaturated aliphatic amines such as vinylamine, allylamine, butenylamine, pentenylamine, hexenylamine, pentadienylamine, and hexadienylamine; And alicyclic amines such as cyclopentylamine, cyclohexylamine, cyclooctylamine, menthylamine, cyclopentenylamine, cyclohexenylamine and cyclohexadienylamine.

Examples of the aromatic primary amine include aniline, benzylamine, naphthylamine, naphthylmethylamine, toluidine, tolylenediamine, and the like.

Examples of the primary amine having another reactive functional group include ethylenediamine, ethylenetriamine, monoethanolamine, aminothiophene, glycine, alanine, phenylalanine, aminoacetone and the like.

The secondary amines can be aliphatic amines including alicyclic amines, aromatic amines and other reactive functional groups. These may be monoamines having one nitrogen atom or one nitrogen atom derived from an amino group or imino group in one molecule, or two or more nitrogen atoms such as diamine and triamine. Also, a heterocyclic compound in which a nitrogen atom derived from an amino group or an imino group is a member of an alicyclic ring or an aromatic ring may be used.

The aliphatic amine may be a saturated aliphatic amine, an unsaturated aliphatic amine, an alicyclic amine, or the like. Specific examples of the saturated aliphatic amine include dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, methylethylamine, methylpropylamine, methylbutylamine, methylpentylamine, methylhexylamine , N-methylethylenediamine, N, N'-dimethylethylenediamine, N, N'-dimethylethylenediamine, N, N'-dimethylethylenediamine, N- Ethyl ethylenediamine, N, N'-diethylethylenediamine, and the like.

Specific examples of the unsaturated aliphatic amine include aliphatic amines such as methyl vinyl amine, methyl ally amine, methyl butenyl amine, methyl pentenyl amine, methyl hexenyl amine, ethyl vinyl amine, ethyl allylamine, ethyl butenyl amine, Butenylamine, butylhexylamine, butylhexylamine, butylhexylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, diethylamine, But are not limited to, vinylamine, diallylamine, dibutenylamine, dipentenylamine, dioxenylamine, vinylallylamine, vinylbutenylamine, vinylpentenylamine, vinylhexenylamine, allylbutenylamine, allylpentenylamine, Decylamine, decylamine, decylamine, decylamine, decylamine, decylamine, decylamine, decylamine,

Specific examples of the alicyclic amine include dicyclopentylamine, dicyclohexylamine, methylcyclopentylamine, methylcyclohexylamine, methylcyclooctylamine, ethylcyclopentylamine, ethylcyclohexylamine, ethylcyclooctylamine, propylcyclo But are not limited to, pentylamine, propylcyclohexylamine, butylcyclopentylamine, butylcyclohexylamine, hexylcyclopentylamine, hexylclohexylamine, hexylcloctylamine, vinylcyclopentylamine, vinylcyclohexylamine, , Saturated alicyclic amines such as allyl cyclopentylamine, allylcyclohexylamine, allylcyclooctylamine, butenylcyclopentylamine, butenylcyclohexylamine and butenylcyclooctylamine; In addition, it is also possible to use at least one compound selected from the group consisting of methylcyclopentenylamine, methylcyclohexenylamine, methylcyclooctenylamine, ethylcyclopentenylamine, ethylcyclohexenylamine, ethylcyclooctenylamine, propylcyclopentenylamine, Butylcyclopentenylamine, butylcyclopentenylamine, butylcyclohexenylamine, vinylcyclopentenylamine, vinylcyclohexenylamine, vinylcyclooctenylamine, allylcyclopentenylamine, allylcyclohexenylamine, butenylcyclopentenylamine, Decylcyclohexylamine, decylcyclohexenylamine, dicyclopentenylamine, dicyclohexylamine, dicyclooctenylamine, methylcyclopentadienylamine, ethylcyclopentadienylamine, propylcyclopentadienylamine, methylcyclohexadienyl Amine, ethylcyclohexadienylamine, propylcyclohexadienylamine, vinylcyclopentadienylamine, vinylcyclohexadienylamine, allylcyclopentadienylamine , Allylcyclohexadienylamine, dicyclopentadienylamine, dicyclohexadienylamine, dicyclooctadienylamine, dicyclooctatrienylamine, methylcyclooctatrienylamine, and ethylcyclooctatriene And unsaturated alicyclic amines such as n-amyl amine.

Examples of the aromatic secondary amine include diphenylamine, ditolylamine, dibenzylamine, dinaphthylamine, N-methylaniline, N-ethyl aniline, N-propylaniline, N-butyl aniline, , N-ethyltoluidine, N-propyltoluidine, N-butyltoluidine, N-methylbenzylamine, N-ethylbenzylamine, N-propylbenzylamine, N-butylbenzylamine, N-propylnaphthylamine, N, N'-dimethyltolylenediamine, N, N'-diethyltolylenediamine, N-vinyl aniline, N-allylaniline, N- N-cyclohexyl aniline, N-cyclohexenyl aniline, N-cyclohexenyl aniline, N-cyclohexyl aniline, N-cyclohexyl aniline, N-cyclohexyl aniline, N- And cyclopentadienyl aniline.

The secondary amine may be a heterocyclic compound (sometimes referred to as a cyclic amine) in which the nitrogen atom of the amino group is a member of an alicyclic ring or an aromatic ring, as described above. Specific examples thereof include pyrrole, pyrrolidine, imidazole, piperidine, piperazine, methylpyrrole, methylpyrrolidine, methylimidazole, methylpiperidine, methylpiperazine, ethylpyrrole, ethylpyrrolidine , Ethylimidazole, ethylpiperidine, ethylpiperazine, phthalimide, maleimide, caprolactam, pyrrolidone, morpholine and the like.

Examples of the secondary amine having other reactive functional groups include N-methylglycine, N-ethylglycine, N-methylalanine, N-ethylalanine, N- methylaminothiophene, N-methylethanolamine, N-ethylethanolamine, and the like.

The tertiary amine may be an aliphatic amine, an aromatic amine, or an amine having other reactive functional groups, including an alicyclic amine, as well as a secondary amine, and may be a monoalcohol having one nitrogen atom derived from an amino group, Amine, and may have two or more nitrogen atoms such as diamine and triamine. Further, as with the secondary amine, the nitrogen atom derived from an amino group or the like may be a heterocyclic compound which is a member of an alicyclic ring or an aromatic ring.

Examples of the aliphatic tertiary amine include saturated aliphatic amines, unsaturated aliphatic amines and alicyclic amines. Specific examples of the saturated aliphatic amine include trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, dimethylethylamine, dimethylpropylamine, dimethylbutylamine, dimethylpentylamine, dimethylhexylamine , Diethylpropylamine, diethylbutylamine, diethylpentylamine, diethylhexylamine, dipropylbutylamine, dipropylpentylamine, dipropylhexylamine, dibutylpentylamine, dibutylhexylamine, dipentylhexylamine , Methyldiethylamine, methyldipropylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, ethyldipropylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, propyldibutylamine , Propyldiphenylamine, propyldiphenylamine, butyldiphenylamine, butyldiphenylamine, butyldiphenylamine, butyldiphenylamine, butyldiphenylamine, butyldiphexylamine, pentyldihexylamine, methylethylpropylamine, methylethylbutylamine, methylethylhexylamine, methylpropylbutylamine, N, N ', N'-tetramethylethylenediamine, N, N'-tetramethylethylenediamine, N, N'-tetramethylethylenediamine, propylbutylpentylamine, butyldimethylamine, butyldimethylamine, N, N, N ', N'-tetraethylethylenediamine, and the like.

Specific examples of the unsaturated aliphatic amine include trivinylamine, triallylamine, tributenylamine, tripentenylamine, trihexenylamine, dimethylvinylamine, dimethylallylamine, dimethylbutenylamine, dimethylpentenylamine, di And examples thereof include ethyl vinyl amine, diethyl ally amine, diethyl butenyl amine, diethyl pentenyl amine, diethyl hexenyl amine, dipropyl vinyl amine, dipropyl ally amine, dipropyl butenyl amine, methyl divinyl amine, Allyl amine, methyl dibutyl amine, ethyl divinyl amine, ethyl diallylamine and the like.

Specific examples of the alicyclic amine include tricyclopentylamine, tricyclohexylamine, tricyclooctylamine, dimethylcyclopentylamine, dimethylcyclohexylamine, diethylcyclopentylamine, diethylcyclohexylamine, dipropylcyclopentylamine Such as dipropylcyclohexylamine, dibutylcyclopentylamine, methyldicyclopentylamine, methyldicyclohexylamine, ethyldicyclopentylamine, ethyldicyclohexylamine, propyldicyclopentylamine and propyldicyclohexylamine, and the like. Saturated alicyclic amines; It is also possible to use at least one compound selected from the group consisting of tricyclopentenylamine, tricyclohexylamine, tricyclopentadienylamine, tricyclohexadienylamine, dimethylcyclopentenylamine, dimethylcyclohexenylamine, diethylcyclopentenylamine, diethylcyclo And unsaturated alicyclic amines such as hexenylamine, dipropylcyclopentenylamine, dipropylcyclohexylamine, methyldicyclopentenylamine, ethyldicyclopentenylamine, and propyldicyclopentenylamine.

Examples of the aromatic tertiary amine include N, N-dimethylaniline, N, N-dimethylbenzylamine, N, N-dimethyltoluidine, N, N-dimethylnaphthylamine, N, N-dipropyl aniline, N, N-dipropyl benzyl amine, N, N-dipropyl toluidine, N, N-dipropyl aniline, N, N-diallylamine, N, N-diallylamine, N-methyldiphenylamine, N, N-dimethylaniline, N, -Diethylenetetramine, dibutylethylenediamine, dibutylethylamine, dibutylethylamine, dibutylethylamine, dibutylethylamine, dibutylamine, dibutylamine, dibutylamine, N, N, N ', N'-tetramethyltolylenediamine, N, N, N (trimethylsilyl) aminonitrile, ', N'-tetraethyltolylenediamine, and the like.

The tertiary amine may also be a heterocyclic compound (sometimes referred to as a cyclic amine) in which the nitrogen atom of the amino group is a member of an alicyclic ring or an aromatic ring as in the case of a secondary amine. Specific examples thereof include N-methylpyrrolidone, N-methylpyrrolidine, N-methylpyrrolidine, N-methylimidazole, N-methylpiperidine, N- N, N'-dimethylpiperazine, N, N'-diethylpiperazine, hexamethylenetetramine, cycloamidine compounds, pyridine, pyridazine, pyrazine, quinoline, quinazoline, quinuclidine Pyridine, N-methylpyrrolidone, N-ethylpyrrolidone, N-methylmorpholine, N-ethylmorpholine and the like.

Examples of other tertiary amines having a reactive functional group include N, N-dimethylglycine, N, N-diethylglycine, N, N-dimethylalanine, N, N-diethylalanine, N, N-dimethylaminothiophene, 1,1,3,3-tetramethylguanidine, and the like.

Of the amine compounds capable of forming the above-mentioned thermal base generators, the cycloamidine compounds are preferable from the viewpoints of the basic strength of the base generated upon heating, the stability of the composition, and the availability of the base. The cycloamidine compound in the present invention can be represented by the following formula (I).

In the formula (I), m is an integer of 2 to 6, preferably an integer of 3 to 5. In the formula (I), one or a plurality of hydrogen atoms in (CH ₂ ) _m forming the alicyclic ring may be substituted or substituted, and examples of preferable substituents include those having 1 to 6 carbon atoms which may be substituted with an alkoxy group An alkyl group, and a dialkylamino group having 2 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a tert-butyl group and an n-hexyl group, and an alkyl group having 1 to 6 carbon atoms substituted with an alkoxy group Examples of the hydroxyalkyl group include a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-hydroxyisopropyl group, a 3-hydroxy-tert-butyl group, . Examples of the dialkylamino group having 2 to 12 carbon atoms include a dimethylamino group, a methylethylamino group, a diethylamino group, a diisopropylamino group, a tert-butylmethylamino group, and a di-n-hexylamino group.

Of the compounds represented by the above formula (I), 1,5-diazabicyclo [4.3.0] -5-nonene [a compound of m = 3 in the formula (I), sometimes referred to as DBN) Diazabicyclo [4.4.0] deca-5-ene [compound of m = 4 in the formula (I)], 1,8-diazabicyclo [5.4.0] undeca-7- Ene [in the formula (I), a compound of m = 5, sometimes referred to as DBU), 5-hydroxypropyl-1,8-diazabicyclo [5.4.0] undeca-7- A compound in which one hydrogen atom in m = 5 and (CH ₂ ) _m is substituted by a hydroxypropyl group in the formula (I)] and 5-dibutylamino-1,8-diazabicyclo [5.4.0] 7-ene (a compound wherein one hydrogen atom in m = 5 and (CH ₂ ) _m is substituted with a dibutylamino group in the above formula (I)] is preferable. Of these, 1,5-diazabicyclo [4.3.0] -5-nonene are more preferable.

The blending amount of the thermal base generator is usually 0.01 parts by weight or more, preferably 0.1 parts by weight or more, and 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 10 parts by weight or less, 2 parts by weight or less. If the blending amount is too small, the effect of the generated base becomes insufficient, and deterioration of the polarizer can not be improved. On the other hand, if the amount is too large, the cationic polymerization in the photocurable composition may be inhibited. Therefore, the curing of the adhesive becomes insufficient, and there is a possibility that the problem of discoloration in the durability of wet heat and the like may occur.

The adhesive in the present invention may contain other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, Defoaming agents, leveling agents, and the like. Examples of the ion trap agent include inorganic compounds such as powdery bismuth, antimony, magnesium, aluminum, calcium, titanium and mixtures thereof. Examples of the antioxidant include hindered phenol-based oxides And the like.

[Polarizing plate and manufacturing method thereof]

The polarizing plate of the present invention can be obtained by bonding a polarizer and a protective film made of a transparent resin through the above-described photo-curable composition and irradiating an active energy ray thereon to cure the uncured photo-curable composition to fix the protective film on the polarizer By weight. The uncured photocurable composition may be applied to at least one of the bonding surfaces of the polarizer and the protective film. When the protective film is bonded to both surfaces of the polarizer, the two protective films may be bonded step by step, or both surfaces may be bonded in one step.

There is no particular limitation on the coating method of the photocurable composition for forming the adhesive, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Further, since each coating method has an optimum viscosity range, it is also a useful technique to adjust the viscosity of the photocurable composition using a solvent. As the solvent, it is possible to use a solvent which dissolves a photo-curable component having a cationically polymerizable functional group well without deteriorating the optical performance of the polarizer. Examples thereof include hydrocarbons typified by toluene and esters typified by ethyl acetate Organic solvents can be used. The thickness of the adhesive layer after curing is usually 50 占 퐉 or less, preferably 20 占 퐉 or less, more preferably 10 占 퐉 or less.

The light source used for light irradiation is not particularly limited, but a light source having a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, Etc. are suitably used. The light irradiation intensity to the photo-curing composition is determined for each composition of interest and is not particularly limited, but it is preferable that the irradiation intensity in the wavelength range effective for activation of the photocationic polymerization initiator is 0.1 to 1,000 mW / cm 2 . If the light irradiation intensity to the photo-curable composition is too small, the reaction time becomes excessively long, and if the intensity is increased, heat radiated from the lamp and heat generated during polymerization of the photo- There is a possibility of causing deterioration of the apparatus. The light irradiation time to the adhesive is controlled for each composition to be cured and is not particularly limited, but is preferably set so that the integrated light amount expressed by the product of irradiation intensity and irradiation time is 10 to 5,000 mJ / cm 2. If the amount of accumulated light is too small, generation of an acid derived from a photocationic polymerization initiator is not sufficient and there is a possibility that the curing of the obtained adhesive layer becomes insufficient. On the other hand, if the integrated amount of light is increased, irradiation time becomes very long, . ≪ / RTI >

In curing the adhesive by light irradiation, it is preferable to set various conditions as described above within a range in which the polarizing plate, the transmittance and hue of the polarizer, and the transparency of the protective film, and other functions of the polarizing plate are not deteriorated.

[Optical properties of polarizer]

The polarizing plate of the present invention employs a photo-curable composition comprising 0.01 to 20 parts by weight of a thermal base generator in 100 parts by weight of a photo-curable component containing a compound having a cationic polymerizable functional group in an adhesive layer constituting a polarizing plate So that it does not easily deteriorate even when exposed to high temperature conditions and is excellent in heat resistance. For example, when a heating test is conducted in which the temperature is kept at 90 占 폚 for 48 hours, the amount of change of the ab value represented by the a-value of the transmission color and the square value of the b value Can be suppressed.

Here, the above-mentioned transmission hue means the color of light transmitted through the other surface when natural light is irradiated from one surface to one polarizing plate. This color can be expressed by a value and b value in the hunter's Lab colorimetric system and is measured using standard light. Further, in the present invention, the transmission color of the polarizing plate is actually measured by forming a pressure-sensitive adhesive layer on an acetylcellulose-based film of a polarizing plate having a protective film (a cycloolefin-based film and an acetylcellulose-based film in the following examples) And adhered to the glass plate at the pressure-sensitive adhesive layer side. The Lab colorimetric system is represented by Hunter's brightness index L and color coordinates a and b as described in JIS K 5981: 2006 " Synthetic Resin Powder Coating Film " There is an L * a * b * color system defined in JIS Z 8729: 2004 "Color display method-L * a * b * color system and L * u * v * color system" It adopts Lab colorimetric system. The values of the lightness index L and the colors a and b are calculated from the tristimulus values X, Y, and Z defined in JIS Z 8722: 2009 "Color measurement method - reflection and transmission object color"

L = 10Y ^1/2

a = 17.5 (10.2 X Y) / Y ^1/2

b = 7.0 (Y-0.847Z) / Y ^1/2

In the Lab colorimetric system, the colors a and b can represent positions corresponding to saturation, and when the color a value increases, the hue changes to a red color system, while when the color b value increases, the hue changes to a yellow color system.

The ab value representing the color is calculated by the following formula (II).

ab = (a ² + b ² ) ^1/2 (II)

Since the polarizing plate of the present invention can reduce the amount of change of the ab value expressed by the averaged value of the transmission hue and the square value of the b value after performing the heating test in which the polarizing plate is left to stand for 48 hours under the environment of 90 DEG C, The polarizing plate is not yellowing and excellent in durability even under the environment.

[Other optical layers that can be laminated on the polarizing plate]

The polarizing plate of the present invention may be a laminated optical member combined with an optical layer having an optical function other than the polarization function. For example, a reflective layer, a semi-transmissive reflective layer, a light diffusion layer, a retardation plate, a light-collecting plate, a brightness enhancement film, and the like used for forming a liquid crystal display device and the like are used for the optical layer laminated on the polarizing plate for the purpose of forming an optical member. The reflective layer, the semi-transmissive reflective layer, and the light-diffusing layer described above are used to form a reflective polarizing plate (optical member), a transflective polarizing plate (optical member) and a diffusing polarizing plate (optical member) Is used.

The polarizing plate of the reflection type is used in a liquid crystal display device of the type in which incident light from the viewer side is reflected and displayed, and since a light source such as a backlight can be omitted, the liquid crystal display device can be easily thinned. Further, the transflective type polarizing plate is used in a liquid crystal display device of a type in which light is reflected through a light source such as a backlight in a dark place while being reflective in a bright place. The optical member as the reflection type polarizing plate may be a structure in which a reflection layer is formed by laying a foil or a vapor deposition film made of a metal such as aluminum on a protective film on a polarizer. The optical member as the transflective type polarizing plate may be one having a structure in which the above-mentioned reflective layer is formed as a half mirror, or a reflective plate exhibiting light transmittance is attached to a polarizing plate by containing a pearl pigment or the like. On the other hand, the optical member as a diffusion type polarizing plate can be obtained by various methods such as a method of performing a mat treatment on a protective film on a polarizing plate, a method of applying a resin containing a fine particle, May have a micro concavo-convex structure.

The formation of the optical member as the polarizing plate for both of the reflection diffusion and the reflection can be performed by, for example, forming a reflective layer reflecting the concavo-convex structure on the fine uneven structure surface of the polarizing plate. The reflective layer of the fine concavo-convex structure has the advantage of preventing directivity and glare by diffusing incident light by diffuse reflection, and suppressing unevenness of light and shade. Further, the resin layer or film containing fine particles has an advantage that the incident light and the reflected light thereof are diffused when they penetrate the fine particle-containing layer, whereby the non-uniformity of light and shade can be further suppressed. The reflective layer reflecting the surface micro concavo-convex structure can be formed by laying a metal directly on the surface of the fine concavo-convex structure by vapor deposition such as vacuum deposition, ion plating, sputtering, plating or the like. Examples of the fine particles to be blended to form the surface micro concavo-convex structure include inorganic fine particles made of silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle diameter of 0.1 to 30 탆, Crosslinked or uncrosslinked polymer and the like can be used.

On the other hand, the above-mentioned retardation plate as the optical layer is used for the purpose of compensating the retardation by the liquid crystal cell or the like. Examples thereof include a birefringent film made of stretched films of various plastics, a film in which discotic liquid crystals or nematic liquid crystals are aligned and fixed, and those in which the liquid crystal layer is formed on a film substrate. In this case, an acetylcellulose-based resin film such as triacetylcellulose is preferably used as the film substrate for supporting the aligned liquid crystal layer.

Examples of the plastic forming the birefringent film include polyolefins such as polycarbonate, polyvinyl alcohol, polystyrene, polymethylmethacrylate and polypropylene, polyarylate and polyamide. The stretched film may be processed by an appropriate method such as uniaxial stretching or biaxial stretching. Further, a birefringent film in which the refractive index in the thickness direction of the film is controlled by applying a shrinking force and / or a stretching force under adhesion with the heat shrinkable film may be used. Further, two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as broadening.

The light-collecting plate is used for the purpose of optical path control or the like, and can be formed as a prism array sheet, a lens array sheet, a dot-laid sheet, or the like.

The brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display device and the like. Examples of such a brightness enhancement film include a reflection type polarized light separating sheet designed to laminate a plurality of thin films having different refractive index anisotropy, An orientation film of a cholesteric liquid crystal polymer, and a circularly polarized light separation sheet in which the alignment liquid crystal layer is supported on a film base.

The optical member includes a polarizing plate and a single layer or two or more layers selected from optical layers such as the above-mentioned reflective layer, transflective reflective layer, light diffusing layer, retardation plate, condensing plate, Or a laminate of three or more layers. Two or more kinds of optical layers may be combined as desired. The arrangement of each optical layer is not particularly limited.

The various optical layers forming the optical member are integrated using an adhesive. Therefore, the adhesive to be used is not particularly limited as long as the adhesive layer is formed satisfactorily. It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoint of simplicity of the bonding operation and prevention of optical distortion. When a transparent resin film is bonded as a protective film to one surface of a polarizer and an optical layer such as a retarder is directly bonded to the other surface of the polarizer, a polarizer, a transparent resin film as a protective film and an optical layer ) Can also be bonded by using a photo-curable composition containing a photo-curable component and a photo-base generator specified in the present invention.

As the above-mentioned pressure-sensitive adhesive, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyether, or the like may be used as the base polymer. Among them, as in the case of an acrylic pressure sensitive adhesive, it has excellent optical transparency, maintains appropriate wettability and cohesive force, has excellent adhesiveness to a substrate, has weather resistance and heat resistance, and peels off or peels off under heating or humidification conditions It is preferable to select and use those that do not cause a problem. In the acrylic pressure-sensitive adhesive, an acrylic ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group and a butyl group and an acrylic monomer containing a functional group such as (meth) acrylic acid or (meth) An acrylic copolymer having a weight-average molecular weight of 100,000 or more and having a transition temperature of preferably 0 占 폚 or less is useful as a base polymer. Here, the term "(meth) acrylic acid" means that acrylic acid or methacrylic acid may be used, and "(meth) acrylate" means any of hydroxyethyl acrylate and hydroxyethyl methacrylate It means good.

The pressure-sensitive adhesive layer on the polarizing plate can be formed, for example, by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a solution of 10 to 40% by weight and directly coating the solution on the polarizing plate to form a pressure- Or a method in which a pressure-sensitive adhesive layer is formed by previously forming a pressure-sensitive adhesive layer on a protective film in a sheet form and then transferring the pressure-sensitive adhesive layer onto a polarizing plate. The thickness of the pressure-sensitive adhesive layer is determined depending on the adhesive strength and the like, but is preferably in the range of about 1 to 50 mu m.

The pressure-sensitive adhesive layer may contain a filler, pigment, colorant, antioxidant, ultraviolet absorber, antistatic agent, etc., made of glass fiber, glass bead, resin bead, metal powder or other inorganic powder, if necessary. Examples of the ultraviolet absorber include a salicylate ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

Examples of the antistatic agent include ionic compounds, conductive fine particles, and conductive polymers. Of these, suitable antistatic agents may be used alone or in combination of two or more. Of course, two or more types of antistatic agents classified as ionic compounds may be used in combination, two or more types of antistatic agents classified as conductive fine particles may be used in combination, and combinations of two or more types of antistatic agents classified as conductive polymers .

Among the above-described antistatic agents, ionic compounds are preferably used since they are excellent in compatibility with solvents.

The ionic compound can be classified into an ionic compound having an organic cation, an ionic compound having an inorganic cation, an ionic compound having an organic anion, and an ionic compound having an inorganic anion. An example of an ionic compound having an organic cation is classified according to the structure of the organic cation and displayed as follows.

Pyridinium salts:

1-butylpyridinium tetrafluoroborate,

1-butylpyridinium hexafluorophosphate,

1-butyl-3-methylpyridinium tetrafluoroborate,

1-butyl-3-methylpyridinium trifluoromethanesulfonate,

1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide,

1-butyl-3-methylpyridinium bis (pentafluoroethanesulfonyl) imide,

1-butyl-4-methylpyridinium hexafluorophosphate,

1-hexylpyridinium tetrafluoroborate,

1-hexylpyridinium hexafluorophosphate,

1-hexyl-4-methyl-pyridinium bis (fluorosulfonyl) imide,

1-octylpyridinium hexafluorophosphate,

1-butylpyridinium N- (trifluoromethanesulfonyl) trifluoroacetamide,

1-butyl-3-methylpyridinium N- (trifluoromethanesulfonyl) trifluoroacetamide and the like.

Imidazolium salt:

Ethyl-3-methylimidazolium tetrafluoroborate,

1-ethyl-3-methylimidazolium hexafluorophosphate,

Ethyl-3-methylimidazolium acetate,

Ethyl-3-methylimidazolium trifluoroacetate,

1-ethyl-3-methylimidazolium heptafluorobutyrate,

1-ethyl-3-methylimidazolium trifluoromethanesulfonate,

1-ethyl-3-methylimidazolium perfluorobutanesulfonate,

1-ethyl-3-methylimidazolium p-toluenesulfonate,

1-ethyl-3-methylimidazolium dicyanamide,

1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide,

1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imide,

1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methanide,

1-ethyl-3-methylimidazolium N- (trifluoromethanesulfonyl) trifluoroacetamide,

1-butyl-3-methylimidazolium methanesulfonate,

1-butyl-3-methylimidazolium tetrafluoroborate,

1-butyl-3-methylimidazolium hexafluorophosphate,

1-butyl-3-methylimidazolium trifluoroacetate,

1-butyl-3-methylimidazolium heptafluorobutyrate,

1-butyl-3-methylimidazolium trifluoromethanesulfonate,

1-butyl-3-methylimidazolium perfluorobutanesulfonate,

1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide,

1-hexyl-3-methylimidazolium bromide,

1-hexyl-3-methylimidazolium chloride,

1-hexyl-3-methylimidazolium tetrafluoroborate,

1-hexyl-3-methylimidazolium hexafluorophosphate,

1-hexyl-3-methylimidazolium trifluoromethanesulfonate,

1-octyl-3-methylimidazolium tetrafluoroborate,

1-octyl-3-methylimidazolium hexafluorophosphate,

1-hexyl-2,3-dimethylimidazolium tetrafluoroborate,

1,2-dimethyl-3-propylimidazolium bis (trifluoromethanesulfonyl) imide and the like.

Pyrrolidinium salt:

1-butyl-1-methylpyrrolidinium hexafluorophosphate and the like.

Quaternary ammonium salts:

Tetrabutylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate,

Tetrabutylammonium p-toluenesulfonate,

Tetrahexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate,

N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl)

Diallyldimethylammonium tetrafluoroborate,

Diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium trifluoromethanesulfonate,

Diallyldimethylammonium bis (trifluoromethanesulfonyl) imide,

Diallyldimethylammonium bis (pentafluoroethanesulfonyl) imide,

Diallyldimethylammonium N- (trifluoromethanesulfonyl) trifluoroacetamide,

Glycidyl trimethyl ammonium trifluoromethanesulfonate,

Glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide,

Glycidyl trimethyl ammonium bis (pentafluoroethanesulfonyl) imide,

Glycidyltrimethylammonium N- (trifluoromethanesulfonyl) trifluoroacetamide,

N, N-dimethyl-N-ethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl)

N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-ethyl-N-heptylammonium bis (trifluoromethanesulfonyl)

N, N-dimethyl-N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl)

N, N-dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoromethanesulfonyl)

N, N-dimethyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl)

N, N-dimethyl-N-pentyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide,

Trimethylheptylammonium bis (trifluoromethanesulfonyl) imide,

N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide,

N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide,

N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide,

N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide,

Triethylpropylammonium bis (trifluoromethanesulfonyl) imide,

Triethylpentylammonium bis (trifluoromethanesulfonyl) imide,

Triethylheptylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dipropyl-N-methyl-N-ethylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dipropyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dipropyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide,

N, N-dibutyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl)

N, N-dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide,

Trioctylmethylammonium bis (trifluoromethanesulfonyl) imide,

Trioctylmethylammonium hexafluorophosphate,

N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl)

(2-hydroxyethyl) trimethylammonium bis (trifluoromethanesulfonyl) imide,

(2-hydroxyethyl) trimethylammonium dimethylphosphinate and the like.

Examples of ionic compounds having inorganic cations include the following.

Lithium bromide,

Lithium iodide,

Lithium tetrafluoroborate,

Lithium hexafluorophosphate,

Lithium thiocyanate,

Lithium perchlorate,

Lithium trifluoromethanesulfonate,

Lithium bis (trifluoromethanesulfonyl) imide,

Lithium bis (pentafluoroethanesulfonyl) imide,

Lithium tris (trifluoromethanesulfonyl) methanide,

Potassium bis (fluorosulfonyl) imide and the like.

The ionic compound having an organic cation and the ionic compound having an inorganic cation exemplified above have a counter ion (anion), respectively. Thus, examples of the above-described ionic compound having an organic anion and an ionic compound having an inorganic anion can be found in the above-mentioned compounds.

In the case where the anion component constituting the ionic compound is hexafluorophosphate, the color change of the polarizer due to heat of the polarizer made of the cycloolefin resin film, the polarizer and the acetylcellulose resin film becomes remarkable, and in this case Particularly, the effect of the present invention can be confirmed.

The above optical member can be disposed on one or both surfaces of the liquid crystal cell. The above-described pressure-sensitive adhesive layer can also be used for bonding the optical member to the liquid crystal cell. The liquid crystal cell may be any liquid crystal cell. For example, liquid crystal cells of various types such as an active matrix drive type liquid crystal cell typified by a thin film transistor type and a simple matrix drive liquid crystal cell typified by a super twisted nematic type, A display device can be formed. The optical members provided on both surfaces of the liquid crystal cell may be the same or different.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the following compounds were used as a compound having a cationic polymerizable functional group, a photocationic polymerizable initiator, and a heat base generator. The name given with "" at the beginning of each is the product name.

<Compound Having Cationic Polymerizable Functional Group>

"Ceroxide 2021P": 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate obtained from Daihekagaku Kogyo Co., Ltd. Because it contains some impurities, the epoxy equivalent is about 134 g / equivalent. Further, if it is a pure product of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, the epoxy equivalent is about 126 g / equivalent.

<Gwangyang Ion Polymerization Initiator>

"CPI-100 P ": 50 wt% propylene carbonate solution of 4- (phenylthio) phenyldiphenylsulfonium hexafluorophosphate obtained from San A Pro Co., Ltd.

<Thermal Base Generator>

"U-CAT SA 1 ": DBU-phenol salt obtained from San A Pro Co., Ltd. (the composition described in the manufacturer catalog). For DBU, the manufacturer catalog is shown as 1,8-diazabicyclo (5.4.0) undecene 7. [

"U-CAT SA 102 ": DBU-octylate obtained from San A Pro Co., Ltd. (composition described in the manufacturer's catalog).

"U-CAT 5002 ": DBU-based tetraphenyl borate salt obtained from San A Pro Co., Ltd. (composition described in the manufacturer catalog). Although it has been disclosed that it is a latent curing accelerator used in liquid-semiconductor sealing, a specific structure for the DBU system is not disclosed.

[Examples 1 to 9, Comparative Example 1]

(1) Preparation of photocurable composition

"CeLoxide 2021P" as a compound having a cationically polymerizable functional group, "CPI-100P" as a photocationic polymerization initiator, and a heat base generator were put into a screw tube having a capacity of 20 ml as shown in Table 1, Each of the liquid photo-curable compositions 1 to 10 was prepared by defoaming.

(2) Production of Polarizer

The photoconductive compositions 1 to 10 prepared in the above (1) were applied to a corona discharge treated surface of a cycloolefin film (trade name "ZEONOR", manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 탆 and subjected to corona discharge treatment on its surface, To a thickness of about 3.5 mu m after curing.

A polyvinyl alcohol-iodine polarizer having a thickness of 28 탆 was bonded to the coated surface. Subsequently, a corona discharge treatment was carried out on the joint surface of an acetylcellulose-based film (trade name: N-TAC KC4FR-1, manufactured by Konica Minolta Advanced Layer Co., Ltd.) having a thickness of 40 탆 and a cycloolefin- The same photocurable composition as used in the film was coated with a bar coater so that the film thickness after curing was about 3.5 占 퐉. On the coated surface, a polarizer having the above-prepared cycloolefin-based film bonded to one side thereof was bonded on the polarizer side to prepare a laminate. Ultraviolet rays were irradiated from the side of the acetylcellulose film of the laminate using an ultraviolet irradiator equipped with a belt conveyor (lamp: "D bulb" manufactured by Fusion UV Systems Co., Ltd.) to obtain an integrated light quantity of 500 mJ / The photocurable composition was cured. Thus, a polarizing plate having a protective film bonded to both surfaces of the polarizer was produced.

(3) Formation of a pressure-sensitive adhesive layer

To the copolymer of butyl acrylate, methyl acrylate, acrylic acid and hydroxyethyl acrylate, an isocyanate crosslinking agent ("Colonate L ": ethyl acetate solution of 75% of trimethylolpropane adduct of tolylene diisocyanate) (Available from Nippon Polyurethane Co., Ltd.), a silane coupling agent ("KBM-403": 3-glycidoxypropyltrimethoxysilane, liquid, available from Shinetsu Kagaku Kogyo Co., Ltd.), and an antistatic agent 1 -Hexylpyridinium hexafluorophosphate and the compound represented by the following formula (III)] was added to a polyethylene terephthalate film (trade name: "SP-PLR382050 " (Obtained from LINTEC CO., LTD., Called release film) was coated with a die coater so as to have a thickness of 20 탆 after drying, and a sheet-like Thereby producing an adhesive. Subsequently, a surface (adhesive surface) opposite to the release film of the sheet-like pressure-sensitive adhesive obtained above was bonded to the acetylcellulose-based film surface of the polarizing plate prepared in (2) above by means of a laminator, C for 7 days to obtain a polarizing film having a pressure-sensitive adhesive layer formed thereon.

(4) Evaluation of Durability of Polarizer

The polarizing plate on which the pressure-sensitive adhesive layer prepared in (3) was formed was cut into a size of 30 mm x 30 mm, and bonded to a non-alkali glass (trade name "EAGLE XG" manufactured by Corning) on the pressure-sensitive adhesive layer side. The a and b values of the respective transmission hues were measured in the state of the polarizing plate / glass laminate having the pressure-sensitive adhesive layer formed thereon. Thereafter, a durability test was conducted in which the polarizing plate / glass laminate having the pressure-sensitive adhesive layer formed thereon was kept at a high temperature of 90 DEG C for 48 hours.

The measurement of the a and b values of the transmission hue was performed on the polarizing plate / glass laminate having the pressure-sensitive adhesive layer formed before and after the durability test. For the measurement, an ultraviolet visible spectrophotometer "UV-2450 " manufactured by Shimadzu Seisakusho Co., Ltd., and an optional accessory" Polarizer film holder " First, a parallel transmission spectrum (transmission spectrum when linearly polarized light having a vibration plane parallel to the transmission axis of the polarizing plate is incident) and an orthogonal transmission spectrum (transmission axis of the polarizing plate in the wavelength range of 380 to 780 nm (Transmission spectrum when the linearly polarized light having an orthogonal vibration plane is incident) is obtained by using the software "UV-Probe" attached to the spectrophotometer, and the single transmission spectrum of the laminate (equivalent to the transmission spectrum when natural light is incident ), And the a value and the b value of the transmission color were calculated. Based on this measured value, the ab value of the transmission color was obtained according to the following formula.

^{ab = (a 2 + b 2} ) 1/2

The change Δab of the transmission color before and after the durability test was determined. The results are shown in Table 1. The change Δab of the transmittance hue before and after the durability test was a value obtained by subtracting the ab value of the transmittance hue before the durability test from the ab value of the transmittance hue after the durability test and as an index of the hue change by the durability test. When? Ab is 0, it means that there is no color change, and when it is larger, it means that color change is larger.

? Ab = ab value after endurance test - ab value before endurance test

With respect to Examples 1 to 9 and Comparative Example 1, the results of color change at the time of heat resistance test are shown in the column of &quot; optical durability &quot;

[Table 1]

As shown in Table 1, in the photocurable compositions of Examples 1 to 9 in which a thermal base generator was blended, Δab was smaller than that of Comparative Example 1 in which no thermal base generator was added, and discoloration of the polarizing plate was suppressed .

Since the polarizing plate of the present invention has good heat resistance, the present invention is industrially very useful.

Claims (3)

A protective film including a transparent resin is bonded to a polarizer including a polyvinyl alcohol resin in which a dichroic dye is adsorbed and oriented via an adhesive,
Wherein the adhesive is formed of a photocurable composition containing a photocurable component containing a compound having a cationic polymerizable functional group, a photocationic polymerization initiator, and a heat base generator. The polarizing plate according to claim 1, wherein the adhesive contains 0.01 to 20 parts by weight of the thermal base generator per 100 parts by weight of the photocurable component. The polarizing plate according to claim 1 or 2, wherein the protective film to be bonded to one surface of the polarizer through the adhesive is a cycloolefin-based resin film, and the protective film bonded to the other surface of the polarizer through the adhesive Wherein the protective film is an acetylcellulose based resin film and a pressure-sensitive adhesive layer having antistatic function is formed on a surface of the acetylcellulose based resin film opposite to the surface bonded to the polarizer.