KR20160007381A

KR20160007381A - Polarizing plate, high brightness polarizing plate, and ips mode liquid crystal display device

Info

Publication number: KR20160007381A
Application number: KR1020150095772A
Authority: KR
Inventors: 도시카즈 마츠모토
Original assignee: 스미또모 가가꾸 가부시키가이샤
Priority date: 2014-07-11
Filing date: 2015-07-06
Publication date: 2016-01-20
Also published as: KR101875256B1; TW201609414A; CN105278022B; TWI660852B; CN105278022A; JP6462254B2; JP2016018184A

Abstract

In the conventional polarizing plate, suppression of the dimensional change in the absorption axis direction of the polarizing plate is not sufficient.
In the present invention, a polarizing plate for an IPS mode liquid crystal display device in which a first transparent protective film, a polarizing film and a second transparent protective film are laminated in this order, wherein the thickness of the polarizing film is 15 占 퐉 or less, , The in-plane retardation Re (590) at a wavelength of 590 nm is 10 nm or less, the absolute value of the retardation Rth (590) in the thickness direction at a wavelength of 590 nm is 10 nm or less and the thickness at a wavelength of 480 to 750 nm Direction retardation Rth (480-750) is 15 nm or less, and the first transparent protective film has a thickness larger than that of the polarizing film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polarizing plate, a high-brightness polarizing plate, and an IPS mode liquid crystal display,

The present invention relates to a polarizing plate, a high-brightness polarizing plate using the polarizing plate, and an IPS mode liquid crystal display using the same.

BACKGROUND ART A liquid crystal display device is used in various display devices because of its low power consumption, its operation at a low voltage, its light weight and thinness. This liquid crystal display device is composed of many optical members such as a liquid crystal cell, a polarizing plate, a phase difference film, a light condensing sheet, a diffusion film, a light guide plate, and a light reflection sheet. One example of a liquid crystal display device is an in-plane switching (IPS) mode liquid crystal display. For example, in Patent Document 1, a cycloolefin resin film having a specific retardation value is applied to a polarizer having a thickness of 25 [ And an example of an IPS mode liquid crystal display device including the polarizing plate.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2010-107953

However, in the conventional polarizing plate, suppression of the dimensional change in the direction of the absorption axis of the polarizing plate is not sufficient.

That is, the present invention provides the following polarizing plate, high brightness polarizing plate, and liquid crystal display device.

[1] A polarizing plate for an IPS mode liquid crystal display device comprising a first transparent protective film, a polarizing film and a second transparent protective film laminated in this order,

The thickness of the polarizing film is 15 占 퐉 or less,

The first transparent protective film comprises

The in-plane retardation Re (590) at a wavelength of 590 nm is 10 nm or less,

The absolute value of the retardation Rth (590) in the thickness direction at a wavelength of 590 nm is 10 nm or less,

And the absolute value of the retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less,

Wherein the thickness of the first transparent protective film is larger than the thickness of the polarizing film.

[2] The polarizer according to [1], wherein the first transparent protective film and the polarizing film are adhered by a water-soluble adhesive containing a polyvinyl alcohol-based resin and an epoxy compound.

[3] The polarizing plate according to [1], wherein the first transparent protective film and the polarizing film are adhered by an adhesive comprising a resin composition containing an epoxy resin curable by irradiation of active energy rays or heating.

[4] The polarizer according to [3], wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

[5] The polarizer according to any one of [1] to [4], wherein the second transparent protective film comprises a methyl methacrylate resin film, a polyethylene terephthalate resin film or a cellulose resin film.

[6] The polarizer according to any one of [1] to [5], wherein the polarizer is for a mobile phone or a portable information terminal.

[7] A high-brightness polarizing plate in which a brightness enhancement film is laminated on the second transparent protective film side of the polarizing plate described in any one of [1] to [6] through an adhesive.

[8] The high-brightness polarizer described in [7], wherein the high-brightness polarizer is for a mobile phone or a portable information terminal.

[9] An IPS mode liquid crystal display device comprising a polarizing plate described in any of [1] to [6] or a high-brightness polarizing plate described in [7] or [8] arranged on at least one surface of an IPS mode liquid- .

[10] An IPS mode liquid crystal display device as set forth in [9], wherein the IPS mode liquid crystal display device is small / medium-sized.

The polarizing plate of the present invention is suitable for small and medium-sized liquid crystal display devices in which a change in dimension caused in the absorption axis direction is suppressed and a screen of a cellular phone, a portable information terminal, or the like is small.

(Polarizing film)

The polarizing film to be used in the present invention can be produced by a process comprising uniaxially stretching a polyvinyl alcohol based resin film by a known method, a step of adsorbing a dichroic dye by staining the polyvinyl alcohol based resin film with a dichroic dye, A step of treating a polyvinyl alcohol based resin film adsorbed with a coloring pigment with an aqueous solution of boric acid, and a step of washing with water after treatment with an aqueous solution of boric acid.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include a copolymer of vinyl acetate and vinyl acetate, as well as other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is generally about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

A film formed of a polyvinyl alcohol-based resin is used as a original film of a polarizing film. The polyvinyl alcohol resin can be formed by a known method. The film thickness of the polyvinyl alcohol type original film is preferably about 5 to 35 탆, more preferably 5 to 20 탆, from the viewpoint of making the thickness of the obtained polarizing film 15 탆 or less. When the thickness of the original film is 35 m or more, it is necessary to increase the stretching magnification in the production of the polarizing film, and the dimensional shrinkage of the resulting polarizing film tends to increase. On the other hand, if the thickness of the original film is 5 mu m or less, the handling property at the time of stretching is lowered, and problems such as cutting during production tends to occur easily.

The uniaxial stretching of the polyvinyl alcohol based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed in these plural steps.

In the uniaxial stretching, the main yarn may be uniaxially stretched between different rolls, or may be uniaxially stretched using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which a polyvinyl alcohol based resin film is stretched by using a solvent. The draw ratio is usually about 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye is employed. Specific examples of the dichroic dye include iodine and dichroic dyes. It is preferable that the polyvinyl alcohol-based resin film is subjected to immersion treatment in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 占 폚.

The immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing a water-soluble dichroic dye and dyed is employed. The content of the dichroic dye in the aqueous solution is generally about 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water and preferably about 1 × 10 ^-3 to 1 part by weight. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dichroic dye aqueous solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with the dichroic dye is usually carried out by immersing the dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid.

The amount of boric acid in the boric acid-containing aqueous solution 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 containing boric acid contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. The immersing time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 60 to 80 占 폚.

The polyvinyl alcohol-based resin film after treatment with boric acid is usually washed with water. The water washing treatment can be carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 占 폚. The immersion time is usually about 1 to 120 seconds.

After washing with water, drying treatment is carried out to obtain a polarizing film. The drying treatment can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is usually about 30 to 100 占 폚, preferably 50 to 80 占 폚. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

By the drying treatment, the water content of the polarizing film is reduced to a practically acceptable level. The water content thereof is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. If the moisture content exceeds 20% by weight, the thermal stability of the polarizing film may be poor.

The stretching, dyeing, boric acid treatment, washing and drying steps of the polyvinyl alcohol-based resin film in the production process of the polarizer may be carried out in accordance with, for example, the method described in Japanese Patent Application Laid-Open No. 159778/1989. In the method described in this document, a polyvinyl alcohol-based resin layer serving as a polarizer is formed by coating a polyvinyl alcohol-based resin on a base film.

The thickness of the polarizing film is 15 占 퐉 or less, preferably 3 to 10 占 퐉.

(First transparent protective film)

The first transparent protective film is preferably an olefin resin film, and examples thereof include cyclic olefin resins obtained by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives with a polymerization catalyst, May be a film made of a chain olefin resin obtained by polymerization using a polymerization catalyst. Among them, a film made of a cyclic olefin resin is preferable in that a film satisfying the retardation defined by the present invention is obtained.

As the cyclic olefin resin, there may be mentioned, for example, ring-opening metathesis polymerization using cyclopentadiene and olefins with norbornene or a derivative thereof obtained by the Diels-Alder reaction as a monomer, and a resin obtained by subsequent hydrogenation, Ring-opening metathesis polymerization is carried out using tetracyclododecene or a derivative thereof obtained by a Diels-Alder reaction from pentadiene, olefins or methacrylic acid esters as a monomer, and a resin obtained by subsequent hydrogenation, norbornene, Tetracyclododecene, derivatives thereof, or other cyclic olefin monomers are used in the same manner to carry out ring-opening metathesis copolymerization, followed by the addition of a resin obtained by hydrogenation, norbornene, tetracyclo Dodecene, or derivatives thereof , There may be mentioned resins such as obtained by addition copolymerization of an aromatic compound having a vinyl group.

As the cyclic olefin resin, commercially available products can be easily obtained. Examples of the cyclic olefin resin include Topas (manufactured by Topas Advanced Polymers GmbH), Aton (manufactured by JSR Corporation), Zeonor, Zeonex (Manufactured by Mitsui Chemicals, Inc.), and Apel (manufactured by Mitsui Chemicals, Inc.).

As the chain olefin resin, polyethylene or polypropylene resin can be mentioned. Among them, a homopolymer of propylene, and a copolymer mainly composed of propylene and copolymerized with a comonomer copolymerizable therewith at a ratio of usually 1 to 20% by weight, preferably 3 to 10% by weight, Can be used.

The polypropylene resin can be obtained commercially, for example, under the trade names of Prime Polypro (Prime Polymer Co., Ltd.), Nova Tech, WinTech (manufactured by Nippon Polypropylene Co., Ltd.) (Manufactured by Sumitomo Chemical Co., Ltd.) and sun aroma (manufactured by Sun Aroma Co., Ltd.).

The method for producing the first transparent protective film with the cyclic olefin resin or the chain olefin resin may appropriately select the method depending on the resin. For example, a solvent casting method in which a resin dissolved in a solvent is softened with a metal band or a drum to remove the solvent by drying to obtain a film, and a method in which the resin is heated and kneaded at a temperature not lower than its melting temperature and extruded from the die, Thereby obtaining a film. Among them, a melt extrusion method is preferably employed from the viewpoint of productivity.

The retardation Rth in the thickness direction of the first transparent protective film is a value obtained by multiplying the refractive index difference between the in-plane direction and the thickness direction by the thickness of the film, and is represented by the following formula (1). The in-plane retardation Re is a value obtained by multiplying the refractive index difference in the plane by the thickness of the film, and is represented by the following formula (2). Rth and Re can be measured by using various commercially available phase difference systems.

In the thickness direction retardation value _{(Rth) = {(n x} + n y) / 2-n z} × d (1)

Plane retardation value Re = (n _x -n _y ) x d (2)

In the above formula (1) and (2), n _x is a refractive index within the film plane in the x direction (in-plane slow axis direction), n _y is a refractive index in the y direction (in-plane fast axis direction) in the film plane, n _z Is the refractive index in the direction perpendicular to the film plane (thickness direction), and d is the thickness of the film.

The first transparent protective film is formed of a film having both retardation in the plane and in the thickness direction. Although the absolute value of the retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less, the wavelength dependence of the retardation in both the in-plane direction and the thickness direction It can be considered that the above conditions are satisfied in the entire range of wavelengths of 480 to 750 nm if both the retardation in the thickness direction near the wavelength of about 480 nm and the retardation in the thickness direction around the wavelength satisfy the above conditions.

Next, a method of controlling the retardation (Re (590), Rth (590), Rth (480-750)) of the first transparent protective film to satisfy the above conditions will be described. In order to reduce the Re 590 to 10 nm or less, it is necessary to minimize the distortion at the time of stretching remaining in the in-plane direction. In order to make Rth (590) and Rth (480-750) , It is necessary to minimize the distortion remaining in the thickness direction.

For example, in the above-mentioned solvent casting method, a method of relaxing the residual stretching strain in the in-plane direction and the residual shrinkage distortion in the thickness direction, which occurs when the flexible resin solution is dried, is employed. In the melt extrusion method, the distance from the die to the cooling drum is reduced as much as possible in order to prevent the resin film from being stretched between extrusion and cooling of the die, and the extrusion amount and the rotation speed of the cooling drum And a method of controlling the film so as not to be stretched. Also, a method of relaxing the residual strain in the obtained film by heat treatment in the same manner as in the melt extrusion method is also employed.

The thickness of the first transparent protective film is preferably 60 占 퐉 or less. This thickness is preferably 30 m or less, more preferably 25 m or less, from the viewpoint of lowering the retardation value in the thickness direction. The thickness of the first transparent protective film is preferably 5 占 퐉 or more.

The modulus of elasticity of the first transparent protective film is preferably 1500 MPa to 3000 MPa, more preferably 2000 MPa, in view of workability and no problems such as tearing when the polarizer is rewound from the panel. ~ 2500 MPa. Further, in order to improve the durability, etc. high temperature and high humidity under the conditions, temperature 40 ℃ and the water vapor permeability at a relative humidity of 90%, preferably from 150 g / m ² · less than 24 hr, more preferably, 120 g / m ² · 24 hr or less, and more preferably 50 g / m ² · 24 hr or less.

By making the thickness of the first transparent protective film larger than the thickness of the polarizing film, the dimensional change at the time of heating is suppressed, and as a result, the dimensional change during heating of the polarizing plate can be suppressed.

The thickness of the first protective film with respect to the thickness of the polarizing film is preferably 1.5 to 4 times, more preferably 1.7 to 3 times, the thickness of the polarizing film.

(Second transparent protective film)

The second transparent protective film is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and stability of retardation value. The material for the second transparent protective film is not particularly limited, and examples thereof include a methacrylate-based resin, a polyolefin-based resin, a cyclic olefin-based resin, a polyvinyl chloride-based resin, a cellulosic resin, A resin such as a butadiene styrene resin, an acrylonitrile styrene resin, a polyvinyl acetate resin, a polyvinylidene chloride resin, a polyamide resin, a polyacetal resin, a polycarbonate resin, a modified polyphenylene ether resin , Polybutylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin, polyether sulfone resin, polyarylate resin, polyamideimide resin, and polyimide resin . The second transparent protective film is disposed on the opposite side of the liquid crystal cell in the liquid crystal display device of the present invention.

These resins may be used singly or in combination of two or more kinds. These resins can be used after carrying out any suitable polymer denaturation. Examples of such polymer denaturation include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reactions involving dissimilar polymers And the like.

Among them, as the material of the second transparent protective film, it is preferable to use a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, or a cellulose resin.

The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units. The content of the methyl methacrylate unit is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

This methyl methacrylate resin is usually obtained by polymerizing a monofunctional monomer containing methyl methacrylate as a main component in the presence of a radical polymerization initiator. In the polymerization, a polyfunctional monomer or a chain transfer agent may be coexistent, if necessary.

The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylate Methacrylic acid esters other than methyl methacrylate such as 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; Hydroxyalkyl acrylates such as methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate and butyl 2- (hydroxymethyl) acrylate; Unsaturated acids such as methacrylic acid and acrylic acid; Halogenated styrenes such as chlorostyrene and bromostyrene; Substituted styrenes such as vinyltoluene and? -Methylstyrene; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; Unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; And unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. These monomers may be used singly or in combination of two or more kinds.

The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , Ethylene glycol or its oligomers such as tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate, or an oligomer thereof, with acrylic acid or methacrylic acid Esterified; Propylene glycol or its oligomer with both terminal hydroxyl groups being esterified with acrylic acid or methacrylic acid; (Meth) acrylate, neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate and butanediol di (meth) acrylate esterified with acrylic acid or methacrylic acid; Bisphenol A, an alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of the halogen substituents thereof esterified with acrylic acid or methacrylic acid; Trimethylol propane and pentaerythritol esterified with acrylic acid or methacrylic acid, and epoxy groups of glycidyl acrylate or glycidyl methacrylate added to the terminal hydroxyl groups of these polyhydric alcohols; A dibasic acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and halogen substituents thereof, and an alkylene oxide adduct thereof, and the like, in which an epoxy group of glycidyl acrylate or glycidyl methacrylate is ring- Allyl (meth) acrylate; And aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The methacrylic acid-based resin may also be one obtained by modifying a reaction between functional groups copolymerized with a resin. Examples of the reaction include a condensation reaction in a polymer chain of a methyl ester group of methyl acrylate and a hydroxyl group of 2- (hydroxymethyl) acrylate, or a condensation reaction of a carboxyl group of acrylic acid with a hydroxyl group of 2- (hydroxymethyl) Chain hydrolysis condensation reaction, and the like.

Commercially available methyl methacrylate resins are commercially available. Examples of such resins include Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acryphet (manufactured by Mitsubishi Rayon Co., Ltd.), Delpet (Manufactured by Asahi Chemical Industry Co., Ltd.), Ferapelt (manufactured by Kuraray Co., Ltd.), and Arc Referee (manufactured by Nippon Shokubai Co., Ltd.).

The polyethylene terephthalate resin means a resin in which 80 mol% or more of the repeating units are composed of ethylene terephthalate, and may contain other dicarboxylic acid component and diol component. Other dicarboxylic acid components are not particularly limited, and examples thereof include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) Acid, sebacic acid, and 1,4-dicarboxycyclohexane.

Other diol components include, but are not limited to, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol .

These dicarboxylic acid components and diol components may be used in combination of two or more kinds, if necessary. In addition, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-beta-hydroxyethoxybenzoic acid may be used in combination. As another copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of an amide bond, a urethane bond, an ether bond, or a carbonate bond may be used.

Examples of the method for producing the polyethylene terephthalate resin include a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), a method of directly polycondensing a dialkyl ester of terephthalic acid and ethylene glycol (And optionally other diol esters) of terephthalic acid (and optionally other dicarboxylic acids) are reacted with a catalyst (for example, a dialkyl ester of a carboxylic acid or other diol) And a method of polycondensation in the presence of a catalyst. Further, if necessary, solid phase polymerization may be carried out to improve the molecular weight or lower the low molecular weight component.

The polypropylene-based resin means a polymer obtained by polymerization of a chain olefin monomer in which at least 80% of the repeating units are propylene monomers, by using a polymerization catalyst, among the above-mentioned chain olefin-based resins.

Of these, propylene homopolymers are preferred. Further, a copolymer mainly composed of propylene and copolymerized with a copolymerizable comonomer in a proportion of 1 to 20% by weight, preferably 3 to 10% by weight, is also preferable.

When a propylene copolymer is used, ethylene, 1-butene, and 1-hexene are preferable as comonomers copolymerizable with propylene. Among them, ethylene is preferably copolymerized in a proportion of 3 to 10% by weight because transparency is relatively excellent. When the copolymerization ratio of ethylene is 1% by weight or more, transparency is enhanced. On the other hand, if the ratio exceeds 20% by weight, the melting point of the resin may be lowered to impair the heat resistance required for the second transparent protective film.

In the homopolymer of propylene, the content of the component (CXS (cold xylene soluble) component soluble in xylene at 20 캜) is more preferably 1% by weight or less, and more preferably 0.5% or less.

Such a polypropylene-based resin can easily obtain a commercially available product as described above.

The cellulose-based resin is a resin in which part or all of the hydrogen atoms in the hydroxyl group of the cellulose obtained from the raw cellulose such as cotton linters and wood pulp (hardwood pulp, softwood pulp) and the like are substituted with an acetyl group, a propionyl group and / Cellulosic organic acid ester or cellulose mixed organic acid ester. Examples thereof include acetate esters of cellulose, propionic acid esters, butyric acid esters, and mixed esters thereof. Among them, triacetylcellulose film, diacetylcellulose film, cellulose acetate propionate film, and cellulose acetate butyrate film are preferable.

The method of forming the second transparent protective film for adhering the methyl methacrylate resin, the polyethylene terephthalate resin, the polypropylene resin, and the cellulose resin to the polarizing film may be suitably selected And is not particularly limited. For example, a solvent casting method in which a resin dissolved in a solvent is softened with a metal band or a drum to remove the solvent by drying to obtain a film, and a method in which a resin is heated and kneaded at a temperature not lower than its melting temperature, A melt extrusion method is employed. In this melt extrusion method, the single layer film may be extruded, or the multilayer film may be extruded simultaneously.

As the second transparent protective film, commercially available products can be easily obtained. If the methyl methacrylate resin film is a trade name, SUMIFEX (manufactured by Sumitomo Chemical Co., Ltd.), acryrite, (Manufactured by Asahi Chemical Industry Co., Ltd.), Acryprene (manufactured by Mitsubishi Rayon Co., Ltd.), DERAGLASS (manufactured by Asahi Kasei Corporation), Paraglass, Comograss (manufactured by Kuraray Co., Manufactured by Shokubai Co., Ltd.). (Manufactured by Mitsubishi Kagaku Co., Ltd.) and Daizin A-PET sheet (manufactured by Dainippon Ink & Chemicals, Inc.) can be used as the polyethylene terephthalate resin film. (Manufactured by FILMAX Corporation), Suntox (manufactured by Suntox), and Toserol (manufactured by Toserol Corporation), and Toyo Boprene Film (Manufactured by Nippon Polyacetics Co., Ltd.), and Taikou FC (manufactured by Futamura Kagaku Co., Ltd.), and the like . In the case of the cellulose-based resin film, Fuji Tack TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.) can be used.

The first transparent protective film and the second transparent protective film used in the present invention may be imparted with haze. The method of imparting antifogging properties is not particularly limited. For example, a method of mixing inorganic fine particles or organic fine particles into the raw material resin to form a film, and a method of using the multilayer extrusion described above, A method of forming a double-layered film with a resin in which fine particles are not mixed on the other side, or a method of making a three-layered film outward with a resin mixed with particles and a method of mixing inorganic fine particles or organic fine particles in one side of the film with a curable binder resin A method in which a coating solution is coated, and a binder resin is cured to form an antiglare layer, and the like.

The second transparent protective film disposed on the opposite side of the liquid crystal cell (opposite to the surface on which the first transparent protective film having a predetermined retardation property is disposed) may be stretched or may not be stretched. From the viewpoint of thinning the protective film or increasing the strength of the protective film, for example, a cellulose resin film or a stretched methyl methacrylate resin film is preferable. From the viewpoint of suppressing the coloring of the display screen without imparting a retardation to the film, An acid methyl based resin film or a cellulose based resin film is preferable.

The second transparent protective film disposed on the opposite side of the liquid crystal cell may contain a known additive as required. However, since transparency is required in optical applications, it is preferable to limit the amount of the additive to be minimized. Examples of known additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light stabilizers, and impact resistance improvers.

The thickness of the second transparent protective film is usually from 1 to 500 μm, preferably from 10 to 200 μm, more preferably from 10 to 100 μm, from the viewpoints of strength and handling properties.

It is preferable that the first transparent protective film and the second transparent protective film are subjected to a saponification treatment, a corona treatment, a plasma treatment, and the like prior to bonding with the polarizing film.

Functional layers such as a conductive layer, a hard coat layer, and a low reflection layer may be provided on the first transparent protective film and the second transparent protective film. Further, a resin composition having these functions may be selected for the binder resin constituting the antiglare layer.

(Polarizer)

The method of laminating the first transparent protective film and the polarizing film and the second transparent protective film and the polarizing film is preferably a method of integrating them using an adhesive, for example. The thickness of the adhesive layer formed of an adhesive is preferably 0.01 to 35 mu m, more preferably 0.01 to 10 mu m, and still more preferably 0.01 to 5 mu m. Within this range, no floating or peeling occurs between the first transparent protective film and the second transparent protective film and the polarizing film, and an adhesive force with no problem in practical use can be obtained.

As the adhesive, there are, for example, a solvent type adhesive, an emulsion type adhesive, a pressure-sensitive adhesive, a re-wetting adhesive, a polycondensation adhesive, a solventless adhesive, a film type adhesive and a hot melt type adhesive. If necessary, an adhesive layer may be provided through the anchor coat layer.

As the adhesive, a water-soluble adhesive is preferable. The water-soluble adhesive includes, for example, a polyvinyl alcohol-based resin as a main component. The water-soluble adhesive may be a commercially available adhesive, or a commercially available adhesive mixed with a solvent or an additive may be used. Examples of a commercially available polyvinyl alcohol-based resin that can be a water-soluble adhesive include KL-318 manufactured by Kuraray Co., Ltd.

The water-soluble adhesive may contain a crosslinking agent. As the kind of the crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt and the like are preferable, and an epoxy compound is particularly preferable. Commercially available products of the crosslinking agent include, for example, glyoxal and Sumirez resin 650 (30) manufactured by Sumitomo Chemical &

As another preferred adhesive, there can be mentioned an adhesive comprising a resin composition containing an epoxy resin which is cured by irradiation with an active energy ray or heating.

When an adhesive composed of a resin composition containing such an epoxy resin is used, the polarizing film and the transparent protective film are adhered to each other by applying an active energy ray to the adhesive layer interposed between the films to be adhered or by heating , And curing the curable epoxy resin contained in the adhesive. The irradiation of the active energy ray or the curing of the epoxy resin by heat is preferably performed by cationic polymerization of the epoxy resin. In the present invention, the epoxy resin means a compound having two or more epoxy groups in the molecule.

In the present invention, it is preferable that the epoxy resin contained in the curable epoxy resin composition as an adhesive does not contain an aromatic ring in the molecule, from the viewpoints of weatherability, refractive index, cationic polymerizability and the like. As such epoxy resins, hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like can be exemplified.

Hydrogenated epoxy resins are hydrogenated aromatic rings of aromatic epoxy resins. Examples of the aromatic epoxy resin include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bispale F, and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; Glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and epoxy polyvinylphenols. The epoxy resin may be used alone or in combination of two or more. The hydrogenated epoxy resin is obtained by reacting an aromatic polyhydroxy compound such as bisphenol A, which is a raw material of these aromatic epoxy resins, with a nucleophilic polyhydroxy compound obtained by selectively subjecting the aromatic polyhydroxy compound to a nuclear hydrogenation reaction under pressure in the presence of a catalyst, In the presence of a base. Among them, it is preferable to use hydrogenated bisphenol A glycidyl ether as the hydrogenated epoxy resin.

The alicyclic epoxy resin means an epoxy resin having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means an oxygen atom -O- forming a bridge structure with two carbon atoms constituting the alicyclic ring in the structure represented by the following formula. In the formula, m is an integer of 2 to 5.

The compound in which one or more hydrogen atoms of the (CH ₂ ) _m in the above formula are removed from other groups in the chemical structure may be an alicyclic epoxy resin. (CH ₂ ) _m may be appropriately substituted with a straight chain alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy resins, epoxy resins having an oxabicyclohexane ring (wherein m = 3 in the above formula) or an oxabicycloheptane ring (in which m = 4 in the above formula) have excellent adhesiveness are preferably used . Suitable alicyclic epoxy resins are specifically exemplified below, but are not limited to these compounds.

(a) epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(Wherein R ¹ and R ² represent, independently of one another, a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms).

(b) epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(Wherein R ³ and R ⁴ represent, independently of each other, a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

(c) epoxycyclohexylmethyl esters of dicarboxylic acids represented by the following formula (III):

(Wherein R ⁵ and R ⁶ are each independently a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms, and p is an integer of 2 to 20).

(d) epoxycyclohexyl methyl ether methyl ether of polyethylene glycol represented by the following formula (IV):

(Wherein R ⁷ and R ⁸ are each independently a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

(e) epoxycyclohexyl methyl ethers of alkane diols represented by the following formula (V):

(Wherein R ⁹ and R ¹⁰ are each independently a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

(f) a diepoxytrispiro compound represented by the following formula (VI):

(Wherein R ¹¹ and R ¹² independently represent a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(g) a diepoxy monospiro compound represented by the following formula (VII):

(Wherein R ¹³ and R ¹⁴ independently represent a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(h) vinylcyclohexene epoxides represented by the following formula (VIII):

(Wherein R ¹⁵ represents a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(i) epoxycyclopentyl ethers represented by the following formula (IX):

(Wherein R ¹⁶ and R ¹⁷ independently represent a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

(j) diepoxytricyclodecane compounds represented by the following formula (X):

(Wherein R ¹⁸ represents a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms).

Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are more preferably used because they are commercially available or the like and are relatively easy to obtain.

(A) an esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid with (7-oxa-bicyclo [4.1.0] hept- Compound of R < ¹ > = R < ² > = H]

(B) An ester with 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept- Cargo [compound of formula (I) wherein R ¹ = 4-CH ₃ , R ² = 4-CH ₃ ]

(C) an esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [compound of formula (II) wherein R ³ = R ⁴ = H, ],

(Compound of formula (III), R ⁵ = R ⁶ = H, p = 4), (D) (7-oxabicyclo [4.1.0] hept-3-yl) methanol and adipic acid

(E) (4- methyl-7-oxabicyclo [4.1.0] hept-3-yl) methanol and adipic acid and O in the esterified product [formula ^{(III), R 5 = 4} -CH 3, R 6 = 4-CH ₃ , p = 4]

(F) In (7-oxabicyclo [4.1.0] hept-3-yl) ether and the product of methanol and 1,2-ethanediol [formula ^{(V), R 9 = R} 10 = H, r = 2 Lt; / RTI >

Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerin; Triglycidyl ether of trimethylolpropane; Diglycidyl ether of polyethylene glycol; Diglycidyl ether of propylene glycol; And polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin.

The epoxy resin may be used alone, or two or more epoxy resins may be used in combination. The epoxy equivalent of the epoxy resin used in the present invention is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizer after curing may deteriorate or the adhesive strength may decrease. On the other hand, if it exceeds 3,000 g / equivalent, compatibility with other components contained in the adhesive may be lowered.

In the present invention, from the viewpoint of reactivity, cationic polymerization is preferably used as the curing reaction of the epoxy resin. For this purpose, it is preferable to incorporate a cationic polymerization initiator into the curable epoxy resin composition as an adhesive. The cationic polymerization initiator generates cationic species or Lewis acid by irradiation or heating of active energy rays such as visible light, ultraviolet light, X-ray, electron beam and the like, and initiates the polymerization reaction of the epoxy group. Any type of cationic polymerization initiator is preferable in view of workability. Hereinafter, a cationic polymerization initiator for generating a cationic species or a Lewis acid by irradiation of an active energy ray and initiating a polymerization reaction of an epoxy group is referred to as a " photocationic polymerization initiator ", and a cationic species or a Lewis acid is generated by heat, The cationic polymerization initiator for initiating the polymerization reaction is referred to as " thermal cationic polymerization initiator ".

The method of curing the adhesive by irradiation of an active energy ray using a photo cationic polymerization initiator enables curing at room temperature and reduces the need to consider the heat resistance or distortion caused by the expansion of the polarizing film, It is advantageous in that the polarizing film can be favorably adhered. In addition, since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.

Examples of the cationic ion polymerization initiator include, but are not limited to, aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-allene complexes and the like.

Examples of the aromatic diazonium salt include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, and benzene diazonium hexafluoroborate. Examples of the aromatic iodonium salt include diphenyl iodonium tetrakis (pentafluorophenyl) borate, diphenyl iodonium hexafluorophosphate, diphenyl iodonium hexafluoroantimonate, and di (4-nonylphenyl) ) Iodonium hexafluorophosphate, and the like.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis (diphenyl Diphenylsulfide bis (hexafluorophosphate), 4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenylsulfide bis (hexafluoroantimonate) Di (p-toluyl) sulfonyl] -2 (4-hydroxyphenyl) (Isopropylthioxanthone) tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl (meth) acrylate, Diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfone-diphenylsulfide hexafluorophosphate, 4- (Pentafluorophenyl) borate, and 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis .

Examples of the iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II) -Tris (trifluoromethylsulfonyl) methanide, and the like.

Commercially available products of these cationic polymerization initiators are commercially available. Examples thereof include Kayarad PCI-220, Kayarad PCI-620 (manufactured by Nippon Kayaku Co., Ltd.) , "ADEKA OPTOMER SP-150", "ADEKA OPTOMER SP-170" (manufactured by ADEKA Corporation), "CI-5102", "CIT DPI-101 "," DPI-102 "and" CIP-2070S "(all manufactured by Nihon Soda Co., Ltd.) DPI-103, DPI-105, MPI-103, MPI-105, BBI-101, BBI-102, BBI-103, BBI- TPS-103, TPS-105, MDS-103, MDS-105, DTS-102 and DTS-103 PI-2074 " (manufactured by Rhodia), and the like.

These photo cationic polymerization initiators may be used singly or in combination of two or more kinds. Of these, aromatic sulfonium salts are preferably used because they have ultraviolet ray absorption properties even in the wavelength range of 300 nm or more, and thus are excellent in curability and can give a cured product having good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and more preferably 15 parts by weight or less, based on 100 parts by weight of the epoxy resin.

If the blending amount of the photocationic polymerization initiator is less than 0.5 part by weight based on 100 parts by weight of the epoxy resin, the curing becomes insufficient and the mechanical strength and the adhesive strength tend to be lowered. When the blending amount of the photocationic polymerization initiator exceeds 20 parts by weight based on 100 parts by weight of the epoxy resin, the amount of the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases, and the durability may be deteriorated.

When a photo cationic polymerization initiator is used, the curable epoxy resin composition as an adhesive may further contain a photosensitizer, if necessary. By using a photosensitizer, the reactivity of the cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, halogen compounds, and photoreducing pigments.

More specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and?,? -Dimethoxy-? -Phenylacetophenone; Benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; Thioxanthone derivatives such as 2-chlorothioxanthone, and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloro anthraquinone and 2-methyl anthraquinone; Acridone derivatives such as N-methyl acridone and N-butyl acridone; Other examples include, but are not limited to,?,? - diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, and halogen compounds. These photosensitizers may be used alone or in combination of two or more. It is preferably contained in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the photosensitizer and the curable epoxy resin composition.

On the other hand, examples of the thermal cationic polymerization initiator include benzylsulfonium salts, thiophenium salts, thioronium salts, benzylammonium, pyridinium salts, hydradinium salts, carboxylic acid esters, sulfonic acid esters, and amineimides. These thermal cationic polymerization initiators can be easily obtained as commercial products, and examples thereof include "ADEKA OPTON CP77", "ADEKA OPTON CP66" (manufactured by ADEKA Corporation), "CI -2639 "," CI-2624 "(manufactured by Nippon Soda Co., Ltd.)," Sun Aid SI-60L "," Sun Aid SI-80L "and" Sun Aid SI- Ltd.) and the like.

The epoxy resin contained in the adhesive may be cured by either cationic ion polymerization or thermal cationic polymerization, or may be cured by both cationic ion polymerization and thermal cationic polymerization. In the latter case, it is preferable to use a combination of a photo cationic polymerization initiator and a thermal cationic polymerization initiator.

The curable epoxy resin composition may further contain a compound that promotes cationic polymerization such as oxetanes and polyols.

Oxetanes are compounds having a 4-membered ring ether in the molecule, and examples thereof 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, , And phenol novolac oxetane.

These oxetanes are commercially available as commercially available products, and examples thereof include "Aronoxetan OXT-101", "Aronoxetan OXT-121", "Aronoxetan OXT-211" , "Aronoxetan OXT-221", and "Aronoxetan OXT-212" (all manufactured by Toagosei Co., Ltd.). These oxetanes are contained in the curable epoxy resin composition in an amount of usually 5 to 95% by weight, preferably 30 to 70% by weight.

As the polyol, it is preferable that an acid group other than the phenolic hydroxyl group is not present. For example, a polyol compound having no functional group other than the hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxyl group, Polycarbonate polyol and the like. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and further preferably 1,000 or less. These polyols are usually contained in a proportion of not more than 50% by weight, preferably not more than 30% by weight, in the curable epoxy resin composition.

The curable epoxy resin composition 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, a plasticizer, Antifoaming 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 antioxidant and the like.

After the adhesive (epoxy-based curable adhesive) comprising the curable epoxy resin composition containing the epoxy resin as described above is applied to the adhesive surface of the polarizing film or the transparent protective film or both of the adhesive surfaces, Curing adhesive layer by irradiating or heating an active energy ray and bonding the polarizing film and the transparent protective film to each other through an adhesive layer comprising a cured layer of a curable epoxy resin composition. The coating method of the adhesive is not particularly limited, but various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater are employed.

Here, the adhesive containing this epoxy resin used for bonding the polarizing film and the transparent protective film can basically be used as a solvent-free adhesive agent substantially not containing a solvent component, but each coating method has an optimum viscosity range A solvent may be added to adjust the viscosity. As the solvent, it is preferable to use those which dissolve the epoxy resin composition well without deteriorating the optical performance of the polarizing film. The solvent is not particularly limited, and examples thereof include hydrocarbons typified by toluene, esters typified by ethyl acetate Of organic solvents.

When the adhesive is cured by irradiation of an active energy ray, the light source used is not particularly limited. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a high pressure mercury lamp, a chemical lamp, A light lamp, a microwave-excited mercury lamp, and a metal halide lamp. The light irradiation intensity to the curable epoxy resin composition may vary depending on the composition, but it is preferable that the irradiation intensity in the wavelength range effective for activation of the photocationic polymerization initiator is 0.1 to 100 mW / cm ² . When the light irradiation intensity to the curable epoxy resin composition is less than 0.1 mW / cm ² , the reaction time becomes long. When the irradiation intensity exceeds 100 mW / cm ² , heat radiated from the lamp and heat generated during polymerization of the curable epoxy resin composition, The yellowing of the curable epoxy resin composition or deterioration of the polarizing film may occur. The light irradiation time to the curable epoxy resin composition is controlled for each composition and is not particularly limited, but is 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 in the curable epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the photocationic polymerization initiator is not sufficient and the curing of the adhesive may be insufficient. If the accumulated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes extremely long, which may adversely affect the productivity.

When the adhesive is cured by heat, it can be heated by a generally known method, and the conditions and the like are not particularly limited, but usually the temperature at which the thermal cationic polymerization initiator compounded in the curable epoxy resin composition generates cationic species or Lewis acid The specific heating temperature is, for example, about 50 to 200 占 폚.

Even when curing is carried out under either irradiation or heating of an active energy ray, curing is carried out in such a range that the polarization degree, transmittance and hue of the polarizing film, transparency and retardation characteristics of the transparent protective film, and various functions of the polarizing plate are not deteriorated .

(Characteristics of Polarizer)

The degree of polarization of the polarizing plate of the present invention is preferably 99% or more. More preferably, it is 99.9% or more. The mono-transmittance is preferably 38 to 45%. More preferably, it is 40 to 44%. When the polarizing plate of the present invention is used on the viewing side of the liquid crystal display, it is preferable to use a polarizing plate having a monodisperse transmittance of 38 to 43.5%. When the polarizing plate is used on the backlight side of a liquid crystal display device, Do. Particularly, when a single transmittance of the polarizing plate on the viewer side is lower than a single transmittance of the polarizing plate on the backlight side, a liquid crystal display having a high frontal contrast can be obtained.

The polarization degree and the mono-transmittance are numerical values defined by the following formulas.

(?) = 0.5 × [Tp (?) + Tc (?)]

(?) = 100 x [Tp (?) - Tc (?)] / [Tp (?) + Tc

Here, Tp (?) Is the transmittance (%) of the polarizing film measured by the relationship between the linearly polarized light of incident wavelength? Nm and the parallel Nicol, Tc (?) Is the transmittance of the polarizing film measured by the linearly polarized light of incident? (%) Of the polarizing film measured in relation to the polarizing film. All of these values are measurement values obtained by polarized ultraviolet visible absorption spectroscopy by a spectrophotometer. The spectral transmittance (lambda) and the degree of polarization (lambda) obtained for each wavelength are multiplied by a sensitivity correction called visibility correction, which is referred to as a visibility-corrected uniforme transmittance Ty and a visual sensitivity correction polarization degree Py. The visibility correction will be described later in detail. Ty and Py can be conveniently measured with, for example, a spectrophotometer (model number: V7100) manufactured by Nippon Bunko Co., Ltd.

(High brightness polarizer)

The polarizing plate of the present invention can be a high-brightness polarizing plate by laminating a brightness enhancement film on the second transparent protective film side of the polarizing plate (opposite to the side where the first transparent protective film is disposed) through the adhesive.

As the brightness enhancement film, a polarization conversion element having a function of separating outgoing light from a light source (backlight) into transmitted polarized light and reflected polarized light or scattered polarized light is used. Such a brightness enhancement film can improve the emission efficiency of linearly polarized light by using recycled light from a backlight of reflected polarized light or scattered polarized light.

Examples of the brightness enhancement film include anisotropic reflective polarizers. As the anisotropic reflective polarizer, an anisotropic multilayer film that transmits linearly polarized light in one vibrating direction and reflects linearly polarized light in the other vibrating direction is exemplified. Examples of the anisotropic multi-layer film include the trade name "DBEF" manufactured by 3M (see, for example, Japanese Patent Application Laid-Open No. 4-268505, etc.). The anisotropic reflective polarizer may be a composite of a cholesteric liquid crystal layer and a? / 4 plate. As such a composite, a trade name "PCF ", manufactured by NITTO DENKO CO., LTD. May be mentioned (see Japanese Patent Application Laid-Open No. 11-231130, etc.). As the anisotropic reflective polarizer, a reflective grid polarizer can be mentioned. As the reflective grid polarizer, a metal lattice reflective polarizer (see, for example, US Pat. No. 6,288,840, etc.) that microfabricates a metal to generate a reflective polarized light in a visible light region, and a device in which metal fine particles are stretched in a polymer matrix See Japanese Patent Application Laid-Open No. 8-184701, etc.).

A functional layer may be formed on the surface opposite to the bonding surface of the brightness enhancement film with the polarizing plate.

Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusion layer, a retardation layer having a retardation value of 1/4 wavelength, and the like, thereby improving the adhesion with the backlight tape and improving the uniformity of the display image .

Examples of the pressure sensitive adhesive for bonding the polarizing plate and the brightness enhancement film include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, , Rubber such as synthetic rubber and the like may be suitably selected and used as the base polymer. The pressure-sensitive adhesive is preferably excellent in optical transparency, exhibiting appropriate wettability, cohesiveness and adhesive property, and excellent weather resistance and heat resistance.

(Pressure-sensitive adhesive layer)

The pressure-sensitive adhesive layer should have good optical transparency and exhibit adhesive properties such as adequate wettability, cohesiveness, and adhesiveness, but it is preferably used with excellent durability and the like. Specific examples of the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer include a pressure-sensitive adhesive (also referred to as an acrylic pressure-sensitive adhesive) made of an acrylic resin.

The pressure-sensitive adhesive layer formed of the acrylic pressure-sensitive adhesive is not particularly limited, and examples thereof include (meth) acrylate such as butyl acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, An ester-based resin, or a copolymer resin using two or more of these (meth) acrylic acid esters. These resins are also copolymerized with polar monomers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 2-N, And monomers having a polar functional group such as a carboxyl group, a hydroxyl group, an amide group, an amino group, and an epoxy group such as glycidyl (meth) acrylate. The pressure-sensitive adhesive is usually blended with a cross-linking agent together with an acrylic resin.

The pressure-sensitive adhesive may further contain various additives. Suitable additives include silane coupling agents and antistatic agents. The silane coupling agent is effective in enhancing adhesion to glass. The antistatic agent is effective in reducing or preventing the generation of static electricity. That is, when the polarizing plate is attached to the liquid crystal cell through the pressure-sensitive adhesive layer, the surface protective film (separator) which has been temporarily adhered and covered with the pressure-sensitive adhesive layer until then is peeled off and then bonded to the liquid crystal cell. However, The alignment failure may occur in the liquid crystal in the cell due to the static electricity, which may cause display failure of the IPS mode liquid crystal display device.

In order to reduce or prevent the generation of such static electricity, mixing of an antistatic agent is effective.

The thickness of the pressure-sensitive adhesive is preferably 3 to 50 占 퐉. More preferably, it is 3 to 30 mu m.

The storage elastic modulus of the pressure-sensitive adhesive is not particularly limited. For example, when it is desired to suppress warpage of the liquid crystal panel in the high temperature test or the high temperature and high humidity test, the storage elastic modulus at 23 deg. do. More preferably 0.8 MPa or less, and further preferably 0.5 MPa or less.

The pressure-sensitive adhesive may or may not contain an acid. Even in the case of including an acid, it is preferable that the amount of acidity is small. Specifically, it is preferable that the amount of the acid component in the total monomer component is less than 1.0% by weight based on the amount of the whole monomer component.

When the pressure-sensitive adhesive layer is made conductive, its resistance value may be suitably selected. For example, the pressure-sensitive adhesive layer may be in the range of 1 × 10 ⁹ to 1 × 10 ¹¹ Ω / □ so as not to interfere with the operation of a touch panel such as a smart phone desirable.

(Polarizer having a pressure-sensitive adhesive)

The polarizing plate of the present invention may be a polarizing plate having a pressure-sensitive adhesive by providing a pressure-sensitive adhesive layer on at least one surface of the polarizing plate. As the pressure-sensitive adhesive layer, the same pressure-sensitive adhesive as that described above can be used.

(High Brightness Polarizer with Adhesive)

The high-brightness polarizing plate of the present invention can be a high-brightness polarizing plate having a pressure-sensitive adhesive attached thereto by providing a pressure-sensitive adhesive layer on at least one surface thereof. The pressure-sensitive adhesive may be provided on the transparent protective film disposed on the liquid crystal cell side. As the pressure-sensitive adhesive layer, the same pressure-sensitive adhesive as that described above can be used.

(Usage)

The polarizing plate and the high-brightness polarizing plate of the present invention are suitable as components of a liquid crystal panel or a liquid crystal display device, but are particularly suitable for use in medium-sized and small-sized liquid crystal display devices such as cellular phones and portable information terminals using thin glass of 0.7 mm or less. The size of the polarizing plate and the high-brightness polarizing plate of the present invention is preferably 55 mm x 41 mm or larger, more preferably 154 mm x 87 mm or larger, and more preferably 233 mm x 310 mm or smaller, 229 mm x 305 mm or less, and more preferably 174 mm x 231 mm.

(Liquid crystal display device)

The polarizing plate and the high-brightness polarizing plate are bonded to the IPS mode liquid crystal cell through the pressure-sensitive adhesive layer to constitute a liquid crystal panel, and are used in a liquid crystal display device. On the back side of the liquid crystal panel to which the polarizing plate of the present invention is bonded, a polarizing plate of the same kind or a known polarizing plate can be bonded. In particular, it is preferable that the polarizing plate provided with the transparent protective film imparted with the above-mentioned antiglare property is bonded to the viewer side of the liquid crystal panel.

It is preferable that a polarizing plate provided with a cellulose resin film, a polyethylene terephthalate resin film, or a methyl methacrylate resin film provided with a light-diffusing property and a light resistance is bonded to the viewer side of the liquid crystal panel. It is preferable that a polarizing plate provided with a cellulose-based resin film, a polyethylene terephthalate-based resin film, a methyl methacrylate-based resin film, or a polypropylene-based resin film is bonded to the back side of the liquid crystal panel. When a polyethylene terephthalate resin film, a methyl methacrylate resin film and a polypropylene resin film are used, the water vapor transmission rate and the water absorption rate are smaller than those of a triacetyl cellulose film commonly used for a protective film of a polarizing plate, The durability of the polarizing plate is improved and the deterioration of the display quality due to the environmental change of the display device using the polarizing plate is suppressed. Further, by containing the ultraviolet absorber, the durability of the polarizing plate using the ultraviolet absorber is further improved as compared with the case where the triacetylcellulose film is used.

There is no limitation on the combination of the polarizing plates bonded to the viewer side and the back side of the liquid crystal panel, and any combination can be selected. As an example, a polarizing plate provided with a polyethylene terephthalate-based resin film provided with visibility and light resistance on the viewing side of a liquid crystal panel, and a polarizing plate provided with a polypropylene-based resin film on its backside can be cited.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples. In the examples,% and parts representing the content or amount are based on weight unless otherwise specified. The evaluation method used in the examples is as follows.

(1) Thickness:

Using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) in-plane retardation Re and thickness direction retardation Rth:

(KOBRA-ADH, manufactured by Oji Paper Co., Ltd.) with a wavelength of 590 nm, 483 nm or 755 nm at 23 ° C.

(3) Dimensional change rate of polarizer

The polarizing plate was cut into 100 mm square of 100 mm in the direction of the absorption axis 100 mm in the direction of the transmission axis, and left for 100 hours in an environment of 85 캜. The dimensions of the polarizing plate were measured using a 2-dimensional measuring machine "NEXIV VMR-12072 " manufactured by Nikon Corporation. The dimensional change ratio of the polarizing plate is calculated by the following equation, assuming that the dimensional change amount obtained by subtracting the dimension (L ₁ ) after the test from the dimension (L ₀ ) before the test in the absorption axis direction is ΔL.

Dimensional change rate of polarizer =? L / L ₀

(4) Storage elastic modulus:

The storage elastic modulus (G ') of the pressure-sensitive adhesive layer was measured according to the following (I) to (III).

Two samples of (25 ± 1 mg) samples are taken out from the pressure-sensitive adhesive layer (I) and molded into a substantially bead shape.

(II) The obtained substantially bead-shaped sample is adhered to the upper and lower surfaces of the I-shaped jig, and the upper and lower surfaces are sandwiched between the L-shaped jig. The measurement sample is composed of an L-shaped jig, an adhesive, an I-shaped jig, an adhesive, and an L-shaped jig.

(III) The storage elastic modulus (G ') of the thus fabricated sample was measured at a temperature of 23 占 폚, a frequency of 1 Hz, and an initial distortion (?) Using a dynamic viscoelasticity measuring device (DVA-220, manufactured by Haitai Heavy Industries, Ltd.) 1 < N >.

(5) Adhesion to glass:

The polarizing plate provided with the pressure-sensitive adhesive layer was cut to a width of 25 mm, bonded to a glass plate at the pressure-sensitive adhesive layer side, pressed at a temperature of 50 캜 under a pressure of 5 atm for 20 minutes, Then, AZ1 manufactured by Shimazu Seisakusho Co., Ltd. was used to measure the stress when peeled off in the direction of 180 占 with respect to the longitudinal direction of the cut polarizing plate according to JIS Z 0237.

(6) Modulus of elasticity (measured in accordance with JIS K 7161)

The test piece was cut to a width of 15 mm, and the test piece was pulled at a rate of 50 mm / min using AZ1 manufactured by Shimadzu Corporation, and the modulus of elasticity was determined from the strain curve.

(7) Water vapor permeability (measured in accordance with JIS Z 0208)

Sectional area of 27 cm < ² > according to JIS Z 0208. This specification stipulates measurement of the moisture permeability at either the temperature of 25 占 폚 or 40 占 폚, but in this specification, a temperature of 40 占 폚 is employed.

(Production Example 1)

Preparation of polarizing film (Production of polarizing film A having a thickness of 7 탆)

A polyvinyl alcohol film (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) having a thickness of 20 占 퐉 was uniaxially stretched by about 5 times by dry stretching and immersed in pure water at 60 占 폚 for one minute And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 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 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain a polarizer having a thickness of 7 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Production of polarizing film B having a thickness of 12 占 퐉)

A polyvinyl alcohol film (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) having a thickness of 30 占 퐉 was uniaxially stretched by about 5 times by dry stretching and immersed in pure water at 60 占 폚 for one minute And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 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 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 占 폚 for 20 seconds, and then dried at 65 占 폚 to obtain a polarizer having a thickness of 12 占 퐉 in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Production of polarizing film C having a thickness of 23 占 퐉)

A polyvinyl alcohol film (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) having a thickness of 60 탆 was uniaxially stretched by about 5 times by dry stretching and immersed in pure water at 60 캜 for one minute And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed in an aqueous solution of 8.5 / 8.5 / 100 weight ratio of potassium iodide / boric acid / water at 72 캜 for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain a polarizer having a thickness of 23 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Luminance enhancement film A)

In the following examples, a 26 탆 thick brightness enhancement film ("Advanced Polarized Film, Version 3" manufactured by 3M) was used as the brightness enhancement film A.

(Preparation Example 2) Preparation of water-soluble adhesive

Three parts of a carboxyl group-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts of water, and a polyamide epoxy additive (a water-soluble epoxy compound manufactured by Sumitomo Chemical Co., (Sumirez Resin 650 (30), an aqueous solution having a solid concentration of 30%) was added to obtain a water-soluble adhesive.

(Production Example 3) Preparation of pressure-sensitive adhesive

A pressure-sensitive adhesive layer having a thickness of 20 占 퐉 was formed from a commercially available acrylic pressure-sensitive adhesive. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.42 MPa at 23 占 폚. Further, when the pressure-sensitive adhesive layer was bonded to a polarizing plate described later and adhered to glass, the adhesive force to glass was 5 N / 25 mm.

[Example 1]

A second transparent protective film made of triacetyl cellulose (KC2UA, manufactured by Konica Minolta Co., Ltd., thickness 25 占 퐉) was laminated on one surface of a polarizing film A (thickness 7 占 퐉) in which iodine was adsorbed and oriented on a polyvinyl alcohol film (Trade name: "ZF14" manufactured by Nippon Zeon Co., Ltd.), 3.3 times the thickness of the polarizing film, and 23 times the thickness of the polarizing film were laminated on the other surface (Re (590)) = 2.1 nm at the wavelength of 590 nm, a thickness direction retardation (Rth (590)) of 2.8 nm at the wavelength of 590 nm, and a retardation in the thickness direction (483)) = 2.5 nm and a thickness direction retardation (Rth (755)) of-4.2 nm at a wavelength of 755 nm, an elastic modulus of 2315 MPa and a moisture permeability of 17 g / m ² .24 hr. did. Adhesion between the films was carried out by first coating each of the water-soluble adhesives prepared on the first transparent protective film or the second transparent protective film, laminating them on the polarizing film with an adhesive, and then drying at 80 ° C for 5 minutes. The obtained polarizing plate was cured at 40 DEG C for 168 hours, and the dimensional change rate was measured and found to be 0.92%.

A pressure sensitive adhesive layer was formed by applying an acrylic pressure sensitive adhesive on a separator and laminated on the first transparent protective film side to produce a member in which a separator was laminated on a pressure sensitive adhesive layer of a polarizing plate having a pressure sensitive adhesive.

The liquid crystal display of the IPS mode (mobile phone (model number: W62S) manufactured by Sony Ericsson Mobil Communications) was disassembled to peel and remove the polarizing plates on both sides of the liquid crystal cell. Instead, the polarizing plate Two sheets were bonded to each other on the side of the pressure-sensitive adhesive layer from which the respective separators were peeled so as to be in the orthogonal Nicols state on the side (visibility side) and the back side (light incidence side) of the liquid crystal cell. At this time, the absorption axis of the polarizing plate on the front side (viewer side) was arranged so as to be in parallel with the alignment direction when the voltage of the liquid crystal molecules in the liquid crystal cell was zero (black display). The IPS mode liquid crystal display device was reassembled and turned on and the color shift in the black display state in which no voltage was applied to the liquid crystal cell was measured by the liquid crystal viewing angle and chromaticity characteristic measuring device EZ contrast manufactured by ELDIM, ? U'v 'was 0.15.

[Example 2]

A transparent protective film made of triacetyl cellulose (KC2UA, manufactured by Konica Minolta Co., Ltd., thickness: 25 占 퐉) was bonded to one surface of a polarizing film A (thickness 7 占 퐉) having iodine adsorbed and aligned on a polyvinyl alcohol film (Trade name: "ZF14-013" available from Nippon Zeon Co., Ltd.) having a thickness of 13 mu m and a thickness of 1.9 times the thickness of the polarizing film were laminated on the other surface (surface on the liquid crystal cell side) , Retardation in the thickness direction (Rth (590)) = 3.4 nm at a wavelength of 590 nm, in-plane retardation (Re (590)) at a wavelength of 590 nm = 483) = 3.5 nm and the retardation in the thickness direction at a wavelength of 755 nm (Rth (755)) = 2.8 nm, the elastic modulus = 2225 MPa and the moisture permeability = 35 g / m ² .24 hr. Adhesion between the films was carried out by first coating each of the water-soluble adhesives prepared on the first transparent protective film or the second transparent protective film, laminating them on the polarizing film with an adhesive, and then drying at 80 ° C for 5 minutes. The resulting polarizing plate was cured at 40 DEG C for 168 hours, and then the rate of dimensional change was measured and found to be 1.21%.

A pressure sensitive adhesive layer was formed by applying an acrylic pressure sensitive adhesive on a separator and laminated on the first transparent protective film side to produce a member in which a separator was laminated on a pressure sensitive adhesive layer of a polarizing plate having a pressure sensitive adhesive. The polarizing plate having the pressure-sensitive adhesive was bonded to the liquid crystal cell of the IPS mode liquid crystal display device in the same manner as in Example 1, and the color shift was measured. As a result, the color shift? U'v 'was 0.15.

[Example 3]

A polarizing plate was produced in the same manner as in Example 1 except that the polarizing film A having a thickness of 7 占 퐉 was changed to the polarizing film B having a thickness of 12 占 퐉. The dimensional change rate of the polarizing plate was measured and found to be 1.00%.

[Example 4]

A brightness enhancement film A was adhered to the second transparent protective film side of the polarizing plate in Example 1 through a pressure-sensitive adhesive and bonded to produce a high-brightness polarizing plate. The dimensional change rate of this high-brightness polarizing plate was measured and found to be 0.78%.

A pressure sensitive adhesive layer was formed by applying an acrylic pressure sensitive adhesive on a separator and laminated on the first transparent protective film side to produce a member having a pressure sensitive adhesive layer of a high brightness polarizing plate having a pressure sensitive adhesive laminated with a separator.

The polarizing plate of Example 1 was used as a liquid crystal cell of IPS mode (liquid crystal display of IPS mode) [mobile phone (model number: W62S) manufactured by Sony Ericsson Mobil Communications] was disassembled to peel and remove the polarizing plates on both sides of the liquid crystal cell, The bright polarizing plate produced in Example 4 was bonded to the back side (light incidence side) at the side of the pressure-sensitive adhesive layer on which the respective separators were peeled so as to be in the orthogonal Nicols state. At this time, the absorption axis of the polarizing plate on the front side (viewer side) was arranged so as to be parallel to the alignment direction at the time of voltage unapplied (black display) of the liquid crystal molecules in the liquid crystal cell. The IPS mode liquid crystal display device was reassembled and turned on and the color shift in the black display state in which no voltage was applied to the liquid crystal cell was measured by the liquid crystal viewing angle and chromaticity characteristic measuring device EZ contrast manufactured by ELDIM, ? U'v 'was 0.14.

[Example 5]

A brightness enhancement film A was bonded to the second transparent protective film side of the polarizing plate in Example 2 through a pressure-sensitive adhesive to produce a high-brightness polarizing plate. The dimensional change ratio of this high-brightness polarizing plate was measured and found to be 1.04%.

The polarizing plate of Example 1 was bonded to the front side (viewing side) of the liquid crystal cell and the high-brightness polarizing plate produced in Example 5 was placed on the back side (light incidence side) so as to be in an orthogonal Nicols state in the same manner as in Example 4, The shift was measured, and the color shift? U'v 'was 0.14.

[Example 6]

A brightness enhancement film A was bonded to the second transparent protective film side of the polarizing plate in Example 3 through a pressure-sensitive adhesive to produce a high-brightness polarizing plate. The dimensional change ratio of the high-brightness polarizing plate was measured and found to be 0.88%.

The polarizing plate of Example 1 was bonded to the front surface side (visible side) of the liquid crystal cell and the high-brightness polarizing plate produced in Example 6 was attached to the back surface side (light incidence side) so as to be in the orthogonal Nicols state in the same manner as in Example 4, The shift was measured, and the color shift? U'v 'was 0.14.

[Comparative Example 1]

A polarizing plate was produced in the same manner as in Example 1 except that the polarizing film A having a thickness of 7 占 퐉 was changed to a polarizing film C having a thickness of 23 占 퐉. The dimensional change rate of the polarizing plate was measured and found to be 1.55%.

On the side of the first transparent protective film of the polarizing plate, the acrylic pressure sensitive adhesive prepared on the former separator was bonded to produce a polarizing plate having a pressure sensitive adhesive. The polarizing plate having the pressure-sensitive adhesive was bonded to the liquid crystal cell of the IPS mode liquid crystal display device in the same manner as in Example 1, and the color shift was measured. The color shift? U'v 'was 0.15.

It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and is intended to include all modifications within the meaning and range equivalent to the claims.

Claims

A polarizing plate for an IPS mode liquid crystal display device comprising a first transparent protective film, a polarizing film and a second transparent protective film laminated in this order,
The thickness of the polarizing film is 15 占 퐉 or less,
The first transparent protective film comprises
The in-plane retardation Re (590) at a wavelength of 590 nm is 10 nm or less,
The absolute value of the retardation Rth (590) in the thickness direction at a wavelength of 590 nm is 10 nm or less,
And the absolute value of the retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less,
Wherein the thickness of the first transparent protective film is larger than the thickness of the polarizing film.

The polarizing plate according to claim 1, wherein the first transparent protective film and the polarizing film are bonded by a water-soluble adhesive containing a polyvinyl alcohol-based resin and an epoxy compound.

The polarizing plate according to claim 1, wherein the first transparent protective film and the polarizing film are bonded by an adhesive comprising a resin composition containing an epoxy resin which is cured by irradiation of active energy rays or heating.

The polarizing plate according to claim 3, wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

The polarizing plate according to any one of claims 1 to 4, wherein the second transparent protective film comprises a methyl methacrylate resin film, a polyethylene terephthalate resin film or a cellulose resin film.

The polarizing plate according to any one of claims 1 to 4, wherein the polarizing plate is for a mobile phone or a portable information terminal.

A high-brightness polarizing plate in which a brightness enhancement film is laminated on the second transparent protective film side of the polarizing plate described in any one of claims 1 to 4 through an adhesive.

The high-brightness polarizer according to claim 7, wherein the high-brightness polarizer is for a mobile phone or a portable information terminal.

A polarizing plate according to any one of claims 1 to 4, or a polarizing plate according to any one of claims 1 to 4, on at least one surface of an IPS mode liquid crystal cell, And a high-brightness polarizing plate in which a brightness enhancement film is laminated through a pressure-sensitive adhesive.

The IPS mode liquid crystal display device according to claim 9, wherein the IPS mode liquid crystal display device is small / medium type.