TW201609414A - Polarizing plate, high brightness polarizing and IPS mode liquid crystal display device - Google Patents

Abstract

This invention provides a polarizing plate which sufficiently suppresses dimensional variation in the direction of an absorbing axis of the polarizing plate. The polarizing plate of this invention is for use in an IPS mode liquid crystal display device which is a transparent resin film constituted by laminating, sequentially, a first transparent protective film, a polarizing film and a second transparent protective film, wherein: the polarizing film has a thickness of 15 [mu]m or less, the first transparent protective film has an in-plane Retardation Re (590), at a wave length of 590 nm, of 10 nm or less, an absolute value of Retardation Rth (590) in the direction of thickness, at the wave length of 590 nm, of 10 nm or less, and an absolute value of Retardation Rth (480-750) in the direction of thickness, at the wave length of 480~750 nm, of 15 nm or less; the first transparent protective film has a thickness of larger than the thickness of the polarizing film.

Description

Polarizing plate, high brightness polarizing plate and IPS mode liquid crystal display device

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

The liquid crystal display device is used in various display devices because of its low power consumption, low voltage operation, light weight, and thinness. This liquid crystal display device is composed of a plurality of optical members such as a liquid crystal cell, a polarizing plate, a retardation film, a condensing sheet, a diffusion film, a light guide plate, and a light reflection sheet. One of the liquid crystal display devices is, for example, a liquid crystal display device of an in-plane switching (IPS) mode. For example, Patent Document 1 discloses that a polarizing element layer having a thickness of 25 μm has a specific phase difference. A polarizing plate having a cycloolefin resin film as a protective film and an IPS mode liquid crystal display device including the polarizing plate.

[Previous Technical Literature]

[Patent Literature]

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

However, the conventional polarizing plate does not sufficiently suppress the dimensional change of the absorption axis direction of the polarizing plate.

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

[1] A polarizing plate which is 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 polarizing film has a thickness of 15 μ. m or less; the first transparent protective film has a retardation Re(590) of 10 nm or less in a plane at a wavelength of 590 nm, a retardation Rth (590) in a thickness direction of a wavelength of 590 nm, an absolute value of 10 nm or less, and a thickness of 480 to 750 nm. The retardation of the direction Rth (480-750) is a transparent resin film having an absolute value of 15 nm or less; the thickness of the first transparent protective film is larger than the thickness of the polarizing film.

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

[4] The polarizing plate according to the above [3], wherein the epoxy resin contains a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule.

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

[6] The polarizing plate according to any one of [1] to [5] wherein the polarizing plate is used for a mobile phone or a portable terminal.

[7] A high-intensity polarizing plate which is obtained by laminating a brightness enhancing film on the second transparent protective film side of the polarizing plate according to any one of [1] to [6].

[8] The high-brightness polarizing plate according to [7], wherein the high-brightness polarizing plate is used for a mobile phone or a portable terminal.

[9] An IPS mode liquid crystal display device, wherein the polarizing plate according to any one of [1] to [6], or [7] or [8], is provided in at least one surface of the IPS mode liquid crystal cell. Made of high-brightness polarizer.

[10] The IPS mode liquid crystal display device according to [9], wherein the IPS mode liquid crystal display device is used for a small-to-medium-sized liquid crystal display device.

The polarizing plate of the present invention can be prevented from changing in size in the direction of the absorption axis, and is suitable for use in a small-sized and medium-sized liquid crystal display device such as a mobile phone or a portable terminal.

(polarized film)

The polarizing film used in the present invention is usually produced by the following steps: uniaxially stretching a polyvinyl alcohol-based resin film by a conventional method Step of stretching; a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb a dichroic dye; a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed thereon with a boric acid aqueous solution; and using boric acid The step of washing with water after the aqueous solution is carried out.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. The polyvinyl acetate-based resin is a copolymer of a monomer which can be copolymerized with vinyl acetate, in addition to a polyvinyl acetate of a homopolymer of vinyl acetate. Other monomers which can be copolymerized with vinyl acetate include, for example, 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 usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, aldehyde-modified polyethylene formaldehyde, polyvinyl acetal or the like may be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000.

A film made of a polyvinyl alcohol-based resin can be used as a polarizing film. A method of forming a film of a polyvinyl alcohol-based resin can be carried out by a conventional method. When the thickness of the obtained polarizing film is set to 15 μm or less, the film thickness of the polyvinyl alcohol-based film is preferably about 5 to 35 μm , more preferably 5 to 20 μm . When the film thickness of the germ film is 35 μm or more, the stretching ratio at the time of manufacturing the polarizing film must be increased, and the dimensional shrinkage of the obtained polarizing film tends to become large. On the other hand, when the film thickness of the germ film is 5 μm or less, the workability at the time of stretching is lowered, and it tends to cause defects such as breakage during production.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When the uniaxial stretching is carried out after dyeing, the uniaxial stretching can also be carried out before boric acid treatment or boric acid treatment. Moreover, uniaxial stretching can also be performed in a plurality of stages.

When extending uniaxially, it is possible to extend toward a shaft between rolls having different circumferential speeds, or to extend to one axis using a heat roller. Further, the uniaxial stretching may be a dry stretching in which stretching is carried out in the air, or may be a wet stretching in which a solvent is stretched in a state in which a polyvinyl alcohol-based resin film is swollen. The stretching ratio is usually about 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film as a dichroic dye, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically, iodine or a dichroic dye can be used. Further, the polyvinyl alcohol-based resin film is preferably treated by immersing in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is usually used. In the aqueous solution, the content of iodine is usually about 0.01 to 1 part by weight per 100 parts by weight of water. Further, the content of potassium iodide is usually from 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 °C.

Further, the time (dyeing time) of immersing in the 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-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye and dyed is usually used. The content of the dichroic dye in the aqueous solution is usually from about 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably from about 1 × 10 ^-3 to about 1 part by weight. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution of the dichroic dye used for dyeing is usually about 20 to 80 °C. Further, the time (dyeing time) of immersing in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with the dichroic dye can be 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 aqueous solution containing boric acid is usually from about 2 to 15 parts by weight per 100 parts by weight of water, preferably from 5 to 12 parts by weight. When iodine is used as the dichroic dye, it is preferred 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 per 100 parts by weight of water, and preferably about 5 to 12 parts by weight. The time of immersion in the aqueous solution containing boric acid 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 aqueous solution containing boric acid is usually 50 ° C or more, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

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

After washing, the mixture was subjected to a drying treatment to obtain a polarizing film. The drying treatment can be carried out using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

The moisture content of the polarizing film is reduced to a practical level by a drying treatment. The moisture content is usually from 5 to 20% by weight, preferably from 8 to 15% by weight. When the water content is less than 5% by weight, the polarizing film may lose flexibility, or the polarizing film may be damaged or broken after drying. Further, when the water content is more than 20% by weight, the thermal stability of the polarizing film may be inferior.

Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the production step of the polarizing element can be carried out, for example, according to the method described in JP-A-2012-159778. In the method described in this document, a polyvinyl alcohol-based resin is applied to a base film to form a polyvinyl alcohol-based resin layer as a polarizing element.

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

(first transparent protective film)

The first transparent protective film is preferably an olefin-based resin film, and may be, for example, a cyclic olefin system obtained by polymerizing a cyclic olefin monomer such as norbornene or another cyclopentadiene derivative using a polymerization catalyst. A resin or a film of a chain olefin-based resin obtained by polymerizing a chain olefin monomer such as ethylene or propylene using a catalyst for polymerization. Among them, a film containing a cyclic olefin resin is preferable in that a film which satisfies the retardation prescribed by the present invention can be obtained.

The cyclic olefin-based resin may, for example, be subjected to ring-opening metathesis polymerization by using a cyclodecene obtained from a cyclopentadiene and an olefin by a Diels-Alder reaction or a derivative thereof as a monomer, and then borrowing a resin obtained by hydrogenation; a ring-opening metathesis polymerization of tetracyclododecene or a derivative thereof derived from dicyclopentadiene with an olefin or a methacrylate by a Di-A reaction, and then borrowed a resin obtained by hydrogenation; using two or more kinds of norbornene, tetracyclododecene, derivatives thereof, or other cyclic olefin monomers, similarly performing ring-opening metathesis copolymerization, followed by hydrogenation The obtained resin; a resin obtained by copolymerizing a vinylene-containing aromatic compound or the like with the above-described norbornene, tetracyclododecene or the like.

A commercially available product can be easily obtained from the cyclic olefin resin. For example, Topas (manufactured by Topas Advanced Polymers GmbH), ARTON (manufactured by JSR Co., Ltd.), ZEONOR, and ZEONEX (the above is Japan Rui)翁), and APELT (manufactured by Mitsui Chemicals, Inc.).

The chain olefin-based resin may, for example, be polyethylene or a polypropylene resin. Among them, a copolymer which is a homopolymer of propylene and a copolymer which is mainly composed of propylene and copolymerizable with propylene may be used, and the copolymerization is usually carried out at a ratio of from 1 to 20% by weight, preferably. It is carried out at a ratio of 3 to 10% by weight.

Commercially available products can be easily obtained from the polypropylene resin, and various product names include Primepolypro (manufactured by PRIME PORYMER Co., Ltd.), NOVATEC, and WINTEC (the above are Japanese polypropylene shares). Ltd.), Sumitomo Nobrene (manufactured by Sumitomo Chemical Co., Ltd.), and SunAllomer (manufactured by SunAllomer Co., Ltd.).

A method of producing the first transparent protective film from a cyclic olefin resin or a chain olefin resin may be a method of appropriately selecting a resin. For example, a solvent casting method in which a resin dissolved in a solvent is suspended in a metal belt or a drum, a solvent is removed to remove a solvent, and a resin is heated to a temperature higher than a melting temperature thereof, and then a die is used. Extrusion, cooling by cooling the drum body, thereby obtaining a melt extrusion method of the film. Among them, from the viewpoint of productivity, it is preferred to employ a melt extrusion method.

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 and the thickness direction by the thickness of the film, and is represented by the following formula (1). Further, 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 using various commercially available phase difference meters.

The retardation value in the thickness direction (Rth)={(n _x +n _y )/2-n _z }×d (1)

In-plane delay value (Re)=(n _x -n _y )×d (2)

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

The first transparent protective film is composed of a film having a small retardation in the in-plane and thickness directions. Further, the absolute value of the retardation Rth (480-750) in the thickness direction of the wavelength of 480 to 750 nm is 15 nm or less. However, in the general resin, the retardation in the in-plane and thickness directions has wavelength dependence, and the wavelength is changed. Since almost all of them are linear, the retardation in the thickness direction around the wavelength of 480 nm and around 750 nm satisfies the above conditions, and it can be considered that the above conditions are satisfied in all ranges of the wavelength of 480 to 750 nm.

Next, the description will be made in such a manner that the retardation (Re(590), Rth(590), Rth(480-750)) of the first transparent protective film satisfies the above conditions. In order to make Re(590) 10 nm or less, it is necessary to reduce the deformation remaining in the in-plane direction as much as possible, and in order to make Rth (590) and Rth (480-750) below the predetermined value of the present invention, it is necessary to do It is possible to reduce the deformation remaining in the thickness direction.

For example, in the solvent casting method, a method of stretching and deforming in the in-plane direction which occurs when the casting resin solution is dried by heat treatment, and a method of relaxing the residual shrinkage deformation in the thickness direction can be employed. Further, in the melt extrusion method, in order to prevent the elongation from the extrusion of the resin film from the die to the cooling, it is possible to minimize the distance from the die to the cooling drum while controlling the amount of extrusion and the cooling drum. The method of rotating the speed to avoid film stretching, and the like. Further, a method of relaxing the deformation of the film obtained by the same method as the melt extrusion method by heat treatment may be employed.

The thickness of the first transparent protective film is preferably 60 μm or less. From the viewpoint of lowering the phase difference in the thickness direction, the thickness of the first transparent protective film is preferably 30 μm or less, more preferably 25 μm or less. Further, the thickness of the first transparent protective film is preferably 5 μm or more.

The modulus of elasticity of the first transparent protective film is preferably from 1,500 MPa to 3,000 MPa, and more preferably from 2,000 MPa to 2,500 MPa, in terms of workability or the problem that cracking does not occur when the polarizing plate is reworked from the panel. Further, in order to improve durability such as conditions under high temperature and high humidity, the moisture permeability at a temperature of 40 ° C and a relative humidity of 90% is preferably 150 g / m ² / ‧ 24 hours or less, more preferably 120 g / m ² ‧ 24 Below the hour, it is more preferably 50 g/m ² ‧ 24 hours or less.

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

The thickness of the first protective film 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 a material excellent in transparency, mechanical strength, thermal stability, water resistance, and stability of phase difference. The material for the second transparent protective film is not particularly limited, and examples thereof include a methyl methacrylate resin, a polyolefin resin, a cyclic olefin resin, a polyvinyl chloride resin, a cellulose resin, and a styrene resin. Resin, acrylonitrile/butadiene/styrene resin, acrylonitrile/styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamine resin, polyacetal resin, poly Carbonate-based resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyfluorene resin, polyether oxime resin, polyaryl A film of an ester resin, a polyamidimide resin, and a polyimide resin. In the liquid crystal display device of the present invention, the second transparent protective film is disposed on the opposite side of the liquid crystal cell.

These resins may be used singly or in combination of two or more kinds. Further, the resins may be used after any suitable polymer modification, and the polymer modification may include, for example, copolymerization, crosslinking, molecular terminal modification, stereoregular control, and concomitant polymerization. The mixture is modified by mixing or the like when reacting with each other.

Among these, the material of the second transparent protective film is preferably 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 a methyl methacrylate unit. The content of the methyl methacrylate unit is preferably 70% by weight or more, and may also be 100% by weight. The methyl methacrylate unit is a 100% by weight polymer, which is a methyl methacrylate homopolymer obtained by separately polymerizing methyl methacrylate.

The methyl methacrylate-based resin is usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component in the presence of a radical polymerization initiator. At the time of polymerization, a polyfunctional monomer or a chain transfer agent may be simultaneously present as needed.

The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methyl group. a methacrylate other than methyl methacrylate such as benzyl acrylate, 2-ethylhexyl methacrylate or 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, Cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxy acrylate Acrylates such as ethyl ester; methyl 2-(hydroxymethyl)acrylate, methyl 3-(hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, and butyl 2-(hydroxymethyl)acrylate Hydroxyalkyl acrylates such as esters; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyl toluene and α-methylstyrene; acrylonitrile and Unsaturated nitriles such as methacryl oxime; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated quinones such as phenylmaleimide and cyclohexylmaleimide . These monomers may be used alone or in combination of two or more.

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, and triethylene glycol. Ethylene glycol such as di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol di(meth)acrylate The hydroxyl group at both ends of the oligomer is esterified with acrylic acid or methacrylic acid; the hydroxyl group at both terminals of propylene glycol or its oligomer is esterified with acrylic acid or methacrylic acid; neopentyl glycol di(meth)acrylic acid The hydroxyl group of a glycol such as an ester, hexanediol di(meth)acrylate, or butanediol di(meth)acrylate is esterified with acrylic acid or methacrylic acid; a ring of bisphenol A and bisphenol A The oxane adduct, or the terminal hydroxyl groups of the halogen substituents are esterified with acrylic acid or methacrylic acid; the polyols such as trimethylolpropane and neopentyl alcohol are esterified with acrylic acid or methacrylic acid. And ring-opening addition of glycerol acrylate or glycerol methacrylate to the terminal hydroxyl groups of the polyols The epoxy groups are; succinic acid, adipic acid, substituted terephthalic acid, phthalic acid, and the like such halogen a dibasic acid, and an epoxy group of a glycerol acrylate or a methacrylic acid glyceride, such as an alkylene oxide adduct; or an allyl (meth) acrylate; Group of divinyl compounds and the like. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate-based resin may be further modified and reacted by a reaction between the functional groups of the resin. The reaction may, for example, be a polymer chain in-methanol condensation reaction of a methyl ester group of methyl acrylate with a hydroxyl group of methyl 2-(hydroxymethyl) acrylate, or a carboxyl group of acrylic acid and 2-(hydroxymethyl) acrylate. A polymer chain internal dehydration condensation reaction of a hydroxyl group of an ester.

Commercially available products can be easily obtained, for example, SUMIPEX (manufactured by Sumitomo Chemical Co., Ltd.), ACRYPET (manufactured by Mitsubishi Rayon Co., Ltd.), and DELPET (manufactured by Asahi Kasei Co., Ltd.). , PARAPET (manufactured by Kuraray Co., Ltd.) and Acryviewa (manufactured by Nippon Shokubai Co., Ltd.).

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

The other diol component is not particularly limited, and examples thereof include propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, and bisphenol. Ethylene oxide adduct of A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

These dicarboxylic acid components or diol components may be used in combination of two or more kinds as needed. Further, a hydroxycarboxylic acid such as p-hydroxybenzoic acid or p-β-hydroxyethoxybenzoic acid may be used in combination. Further, a dicarboxylic acid component or a diol component containing a small amount of a guanamine bond, an amine ester bond, an ether bond, or a carbonate bond may be used as another copolymerization component.

The method for producing a polyethylene terephthalate resin may be a method in which a terephthalic acid and an ethylene glycol (and other dicarboxylic acids or other diols as needed) are directly condensed. a method of polycondensation of a dialkyl phthalate and ethylene glycol (and optionally a dialkyl ester of a dicarboxylic acid or other diol), followed by transesterification, and terephthalic acid (and A method of polycondensation of a glycol ester of another dicarboxylic acid as needed (and other glycol esters as needed) in the presence of a catalyst. Further, solid phase polymerization may be carried out as needed to increase the molecular weight or lower the low molecular weight component.

The polypropylene-based resin is a polymer obtained by polymerizing a chain olefin monomer in which 80% or more of the repeating units in the linear olefin-based resin is a propylene monomer using a catalyst for polymerization.

Among them, those which are homopolymers of propylene are preferred. Further, it is also preferred to copolymerize a comonomer which is mainly composed of propylene and which is copolymerizable with propylene in a ratio of from 1 to 20% by weight, preferably from 3 to 10% by weight.

When a propylene copolymer is used, a co-monolithic system copolymerizable with propylene is preferably ethylene, 1-butene, and 1-hexene. Among them, since transparency is relatively excellent, it is preferred to copolymerize ethylene in a ratio of 3 to 10% by weight. When the copolymerization ratio of ethylene is 1% by weight or more, the effect of improving transparency can be exhibited. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin may fall and the heat resistance required for the second transparent protective film may be impaired.

In the homopolymer of propylene, it is preferable that the component (CXS (cold xylene soluble) component) which is soluble in 20 ° C is 1% by weight or less, and the CXS component is 0.5% or less. good.

As described above, such a polypropylene-based resin can be easily obtained as a commercially available product.

The term "cellulosic resin" refers to a cellulose organic acid ester or a cellulose mixed organic acid ester, and is made of cotton linters. A part or all of the hydrogen atom of the hydroxyl group of the cellulose obtained from the raw material cellulose such as wood pulp (broadwood pulp, conifer pulp) is substituted with an ethyl sulfonium group, a propyl group and/or a butyl group. For example, it is composed of cellulose acetate, propionate, butyrate, and a mixed ester thereof. Among them, a cellulose triacetate film, a cellulose diacetate film, a cellulose acetate propionate film, and a cellulose acetate butyrate film are preferable.

A method for adhering a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, and a cellulose resin to a second transparent protective film of a polarizing film, as long as it is appropriately selected The method of each resin is not particularly limited. For example, it can be: a solvent-casting method in which a resin dissolved in a solvent hangs down on a metal belt or a drum body, and a solvent is removed by drying to obtain a film; and the resin is heated to a temperature higher than a melting temperature thereof and kneaded, and then extruded from a die to carry out The film was cooled to thereby obtain a melt extrusion method of the film. In the melt extrusion method, a single layer film can be extruded, or a multilayer film can be simultaneously extruded.

A film which is a second transparent protective film can be used, and a commercially available product can be easily obtained. If it is a methyl methacrylate-based resin film, the trade name can be exemplified by SUMIPEX (manufactured by Sumitomo Chemical Co., Ltd.), ACRYLITE, ACRYPLEN ( The above are made by Mitsubishi Rayon Co., Ltd., DELAGLAS (made by Asahi Kasei Co., Ltd.), PARAGLAS, COMOGLAS (above, manufactured by Kuraray Co., Ltd.), and Acryviewa (manufactured by Nippon Shokubai Co., Ltd.). In the case of a polyethylene terephthalate resin film, the trade name may be, for example, Novaclear (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemicals Co., Ltd.). For the polypropylene resin film, FILMAX CPP film (manufactured by FILMAX Co., Ltd.), Suntox (manufactured by Sun Tox Co., Ltd.), TOHCELLO (manufactured by Tohcello Co., Ltd.), and Toyobo PYLEN film (Toyobo Co., Ltd.) Co., Ltd.), Torayfan (manufactured by TORAY Membrane Processing Co., Ltd.), Japan Polyace (manufactured by Japan Polyace Co., Ltd.), and Taihe FC (manufactured by FUTAMURA CHEMICAL CO., LTD.). In addition, as a cellulose-based resin film, the product name may be, for example, Fujitac TD (made by Fujifilm Co., Ltd.), KC2UA, and KONICA MINOLTA TAC film KC (made by KONICA MINOLTA Co., Ltd.).

The first transparent protective film and the second transparent protective film used in the present invention can impart anti-glare properties (haze). The method of imparting anti-glare property is not particularly limited, and for example, a method of mixing inorganic fine particles or organic fine particles in the raw material resin to form a film may be employed; and using the above-described multilayer extrusion, one is a resin mixed with fine particles and The other is a method of performing two-layer film formation by using a resin in which fine particles are not mixed; or a method of performing three-layer film formation by using a resin in which particles are mixed as an outer side; and coating a single side of the film on a hardening adhesive resin. A method in which an inorganic fine particle or an organic fine particle is used as a coating liquid to cure a binder resin to provide an antiglare layer.

The second transparent protective film disposed on the opposite side of the liquid crystal cell side (the side opposite to the side on which the first transparent protective film having a predetermined retardation property is disposed) may be extended or not extended. From the viewpoint of thinning or increasing the strength of the protective film, for example, a cellulose resin film or an extended methyl methacrylate resin film is preferable, and a phase difference is not imparted to the film to suppress coloration of the display image. From the viewpoint of the above, an unstretched methyl methacrylate resin film or a cellulose resin film is preferred.

Further, the second transparent protective film disposed on the opposite side of the liquid crystal cell side may contain a conventional additive as needed. However, since it is necessary to have transparency for optical use, it is preferred that the amount of the additive is suppressed to a minimum. The conventional additives may, for example, be a lubricant, a pressure-resistant adhesive, a heat stabilizer, an antioxidant, an antistatic agent, a light stabilizer, a flushing resistance improving agent, or the like.

The thickness of the second transparent protective film is usually about 1 to 500 μm , preferably 10 to 200 μm , and preferably 10 to 100 μm from the viewpoint of strength, handleability, and the like.

The first transparent protective film and the second transparent protective film are preferably subjected to saponification treatment, corona treatment, plasma treatment, or the like before being bonded to the polarizing film.

A functional layer such as a conductive layer, a hard coat layer, and a low reflection layer may be further provided on the first transparent protective film and the second transparent protective film. Further, a resin composition having such a function may be selected as 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 using an adhesive, for example. The thickness of the adhesive layer formed of the adhesive is preferably 0.01 to 35 μm, more preferably 0.01 to 10 μm , still more preferably 0.01 to 5 μm . When it is in this range, floating and peeling do not occur between the first transparent protective film and the second transparent protective film and the polarizing film, and an adhesive force which is practically problem-free can be obtained.

Examples of the subsequent agent include a solvent-based adhesive, an emulsified adhesive, a pressure-sensitive adhesive, a rewet adhesive, a polycondensation adhesive, a solventless adhesive, a film adhesive, and a hot melt adhesive. . Further, an adhesive layer may be provided through the anchor coating as needed.

The solvent is preferably a water-soluble adhesive. The water-soluble adhesive is, for example, a polyvinyl alcohol-based resin as a main component. The water-soluble adhesive can be used commercially or in a commercially available adhesive. Agents, additives. A commercially available polyvinyl alcohol-based resin which can be a water-soluble adhesive, for example, KL-318 manufactured by KURARAY Co., Ltd., or the like.

The water soluble adhesive may contain a crosslinking agent. The type of the crosslinking agent is preferably an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt or the like, and is particularly preferably an epoxy compound. Commercial products of the crosslinking agent include, for example, glyoxal, Sumirez Resin 650 (30) manufactured by Sumika Chemtex Co., Ltd., and the like.

Further, another preferable adhesive agent is 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 followed by irradiation activity with respect to the coating layer of the adhesive interposed between the subsequent films. The energy ray or heating is performed by hardening the curable epoxy resin contained in the adhesive. The curing of the epoxy resin obtained by irradiation with active energy or heat is preferably obtained by cationic polymerization of an epoxy resin. Further, the epoxy resin in the present invention means a compound having two or more epoxy groups in the molecule.

In the present invention, from the viewpoints of weather resistance, refractive index, cationic polymerizability, and the like, the epoxy resin contained in the curable epoxy resin composition of the adhesive is preferably one which does not contain an aromatic ring in the molecule. Examples of such an epoxy resin include a hydrogenated epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin.

Aromatic ring of hydrogenated epoxy resin aromatic epoxy resin Hydrogenated. Examples of the aromatic epoxy resin include a bisphenol type epoxy resin such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; and a phenol novolak epoxy resin; , cresol novolac epoxy resin and novolak type epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone and epoxidized poly A polyfunctional epoxy resin such as vinyl phenol. The hydrogenated epoxy resin can be obtained by selectively performing a nuclear hydrogenation reaction of an aromatic polyhydroxy compound such as bisphenol A which is a raw material of the aromatic epoxy resin in the presence of a catalyst under pressure. The nuclear hydrogenated polyhydroxy compound is produced by reacting with epichlorohydrin. Among them, as the hydrogenated epoxy resin, it is preferred to use a hydrogenated bisphenol A glycidyl ether.

The alicyclic epoxy resin means an epoxy resin having one or more epoxy groups bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means an oxygen atom -O- which forms a crosslinked structure between two carbon atoms constituting the alicyclic ring in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.

The group in which one or a plurality of hydrogen atoms in the above formula (CH ₂ ) _m is removed is bonded to a compound having another chemical structure, and can be an alicyclic epoxy resin. One or a plurality of hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (m=3 in the above formula) or an oxabicycloheptane ring (m=4 in the above formula) It exhibits excellent adhesion and is suitable for use. Hereinafter, a suitable alicyclic epoxy resin is specifically exemplified, and is not limited to these compounds.

(a) Epoxycyclohexylmethylepoxycyclohexanecarboxylic acid esters of the following formula (I): (wherein R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(b) an epoxycyclohexanecarboxylic acid ester of an alkanediol represented by the following formula (II): (wherein R ³ and R ⁴ each independently represent a hydrogen atom or a linear alkyl group having 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 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).

(d) Epoxycyclohexyl methyl ether of polyethylene glycol represented by the following formula (IV): (wherein R ⁷ and R ⁸ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

(e) an epoxycyclohexyl methyl ether of an alkanediol represented by the following formula (V): (wherein R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

(f) a diepoxytrisole compound represented by the following formula (VI): (wherein R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(g) a diepoxy single spiro compound represented by the following formula (VII): (wherein R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(h) Vinylcyclohexene diepoxides of the following formula (VIII): (wherein R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(i) Epoxycyclopentyl ethers of the following formula (IX): (Wherein, R ¹⁶ and R ¹⁷ each independently represent a system hydrogen atom or a linear alkyl group having a carbon number of 1 to 5).

(j) Dicyclooxy tricyclodecanes of the following formula (X): (wherein R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

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

(A) an ester of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid with (7-oxa-bicyclo[4.1.0]heptan-3-yl)methanol [in the formula (I), a compound of R ¹ =R ² =H], (B) 4-methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo[ 4.1.0]Hept-3-yl)methanol ester [In the formula (I), R ¹ =4-CH ₃ , R ² =4-CH ₃ compound], (C) 7-oxabicyclo[4.1 .0] an ester of heptane-3-carboxylic acid with 1,2-ethanediol [in the formula (II), a compound of R ³ = R ⁴ = H, n = 2], (D) (7- An ester of oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [in the formula (III), a compound of R ⁵ =R ⁶ =H, p=4], (E)(4- An ester of methyl-7-oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [in the formula (III), R ⁵ =4-CH ₃ , R ⁶ =4-CH ₃ , Compound of p=4], (F) (7-oxabicyclo[4.1.0]heptan-3-yl)methanol and ethereal compound of 1,2-ethanediol [in formula (V), R ⁹ = R ¹⁰ = H, compound of r = 2].

Further, examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyols or alkylene oxide adducts thereof. More specifically, diglycidyl ether of 1,4-butanediol; diglycidyl ether of 1,6-hexanediol; triglycidyl ether of glycerol; triglycidyl of trimethylolpropane; Ether; diglycidyl ether of polyethylene glycol; diglycidyl ether of propylene glycol; addition of one or more alkylene oxides (ethylene oxide) by aliphatic polyols such as ethylene glycol, propylene glycol and glycerin And polyglycidyl ether of a polyether polyol obtained by propylene oxide.

Epoxy resins may be used alone or in combination of two or more. The epoxy equivalent of the epoxy resin used in the present invention is usually from 30 to 3,000 g/equivalent, preferably from 50 to 1,500 g/equivalent. When the epoxy equivalent is less than 30 g/eq, the flexibility of the composite polarizing plate after curing may be lowered or the strength may be lowered. On the other hand, when it exceeds 3,000 g/eq, the compatibility with other components contained in the adhesive may be lowered.

In the present invention, from the viewpoint of reactivity, it is preferably Cationic polymerization is used as a hardening reaction of the epoxy resin. Therefore, it is preferred to formulate a cationic polymerization initiator in the curable epoxy resin composition of the adhesive. The cationic polymerization initiator starts a polymerization reaction of an epoxy group by irradiation or heating of an active energy ray such as visible light, ultraviolet light, X-ray, or electron beam to generate a cationic species or a Lewis acid. From the standpoint of workability, any type of cationic polymerization initiator can impart potential, and is preferred. Hereinafter, a cationic polymerization initiator which starts a polymerization reaction of an epoxy group by a cationic species or a Lewis acid by irradiation with an active energy ray is referred to as a "photocationic polymerization initiator"; a cationic species is generated by heat or The cationic polymerization initiator which starts the Lewis acid and initiates the polymerization of the epoxy group is called a "thermal cationic polymerization initiator".

By using a photocationic polymerization initiator, the method of hardening the adhesive by irradiation of an active energy ray can be used for curing at room temperature, reducing the need for deformation due to heat resistance or expansion of the polarizing film, and providing a transparent protective film. It is advantageous in terms of a good adhesion to the polarizing film. Further, since the photocationic polymerization initiator acts as a photocatalyst by light, it is excellent in storage stability and workability even when it is mixed with an epoxy resin.

The photocationic polymerization initiator is not particularly limited, and examples thereof include an aromatic diazonium salt; an aromatic iodonium salt; an onium salt such as an aromatic onium salt; and an iron-propadiene complex.

Examples of the aromatic diazonium salt include a benzenediazonium salt hexafluoroantimonate, a benzenediazonium salt hexafluorophosphate, and a benzenediazonium salt hexafluoroborate. Further, examples of the aromatic iodonium salt include diphenyl iodonium quinone (pentafluorophenyl) borate, diphenyl iodonium hexafluorophosphate, and diphenyl. Base iodonium hexafluoroantimonate and bis(4-mercaptophenyl)iodonium hexafluorophosphate.

Examples of the aromatic onium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium (pentafluorophenyl) borate, and 4,4'-bis(diphenyl). Diphenyl sulfide bis(hexafluorophosphate), 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluoroantimonate) , 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluorophosphate), 7-[bis(p-tolylmethyl) fluorenyl ]-2-isopropyloxazepinone hexafluoroantimonate, 7-[bis(p-tolylmethyl)indolyl]-2-isopropyloxythiazolone oxime (pentafluorophenyl) Borate, 4-phenylcarbonyl-4'-diphenylindenyl-diphenyl sulfide hexafluorophosphate, 4-(p-t-butylphenylcarbonyl)-4'-diphenylanthracene Base-diphenyl sulfide hexafluoroantimonate and 4-(p-t-butylphenylcarbonyl)-4'-bis(p-tolylmethyl) fluorenyl-diphenyl sulfide oxime Fluorophenyl) borate and the like.

Further, examples of the iron-propylene diene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and Xylene-cyclopentadienyl iron (II)- cis (trifluoromethylsulfonyl) methanide and the like.

Commercially available products of such photo-cationic polymerization initiators can be easily obtained. For example, "KAYARAD PCI-220" and "KAYARAD PCI-620" (the above are manufactured by Nippon Kayaku Co., Ltd.) can be easily listed. "UVI-6990" (manufactured by Union Carbide), "Adeka Optomer SP-150", "Adeka Optomer SP-170" (above, ADEKA Co., Ltd.), "CI-5102", "CIT-1370", " CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (above is made by Japan Soda Co., Ltd.), "DPI-101", "DPI-102", "DPI-103", "DPI-105" "MPI-103", "MPI-105", "BBI-101", "BBI-102", "BBI-103", "BBI-105", "TPS-101", "TPS-102", "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102", "DTS-103" (above is made by Midori Chemical Co., Ltd.), "PI-2074" (made by Rhodia Corporation).

These photocationic polymerization initiators may be used alone or in combination of two or more. Among these, the aromatic sulfonium salt particularly has ultraviolet absorbing properties in a wavelength region of 300 nm or more. Therefore, it is excellent in curability, and a cured product having good mechanical strength and adhesion strength can be obtained, and therefore it is suitably used.

The compounding 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.

When the 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 tends to be insufficient, and the mechanical strength and the subsequent strength tend to be lowered. In addition, when the amount of the photocationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, and the hygroscopic property of the cured product may be high and durability may be improved. reduce.

When a photocationic polymerization initiator is used, the curable epoxy resin composition of the adhesive may further contain a photosensitizer as needed. By using a light sensitizer, the reactivity of cationic polymerization can be improved and hardening can be improved Mechanical strength and strength of the material. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo and a diazo compound, a halide, and a photoreductive dye.

To give a more specific example of the photosensitizer, for example, benzoin methyl ether, benzoin isopropyl ether, and α,α-dimethoxy-α-phenylacetophenone can be cited. Benzoin derivatives; benzophenone, 2,4-dichlorobenzophenone, methyl phthalate, benzoic acid, 4,4'-bis(dimethylamino)benzophenone And benzophenone derivatives such as 4,4'-bis(diethylamino)benzophenone; thioxanthone derivatives such as 2-chlorothiazinone and 2-isopropylthioxanthone ; anthracene derivatives such as 2-chloroindole and 2-methylindole; acridine derivatives such as N-methylacridone and N-butylacridone; other α,α-diethoxy But the acetophenone, benzyl, anthrone, xanthone, urea guanidine compound, and halide are not limited thereto. Further, these photo sensitizers may be used alone or in combination of two or more. In 100 parts by weight of the curable epoxy resin composition, the photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight.

On the other hand, examples of the thermal cationic polymerization initiator include a benzyl sulfonium salt, a thiophene sulfonium salt, a thioindole salt, a benzylammonium salt, a pyridinium salt, a hydrazine salt, a carboxylic acid ester, a sulfonate, and an amine hydrazine. Imine and the like. Commercially available products can be easily obtained by using such a thermal cationic polymerization initiator. For example, "Adekaopton CP77" and "Adekaopton CP66" (above, ADEKA Co., Ltd.), "CI-2639", "CI" -2624" (The above is made by Japan Soda Co., Ltd.), "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L" (above is Sanxin Chemical Industry Co., Ltd.) system) Wait.

The epoxy resin contained in the subsequent agent can be cured by either photocationic polymerization or thermal cationic polymerization, or can be cured by both photocationic polymerization and thermal cationic polymerization. In the latter case, a photocationic polymerization initiator and a thermal cationic polymerization initiator are preferably used in combination.

Further, the curable epoxy resin composition may further contain a compound which promotes cationic polymerization such as oxetane or polyol.

The oxetane is a compound having a 4-membered cyclic ether in the molecule, and examples thereof include 3-ethyl-3-hydroxymethyloxetane and 1,4-bis[(3-ethyl-) 3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis[(3-ethyl-3-oxocyclo) Butyryl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenol novolac oxetane.

Commercially available products can be easily obtained from these oxetane. For example, "ARON OXETANE OXT-101", "ARON OXETANE OXT-121", "ARON OXETANE OXT-211", "ARON" can be cited. OXETANE OXT-221", "ARON OXETANE OXT-212" (above, manufactured by Toagosei Co., Ltd.). The curable epoxy resin composition usually contains the oxetanes in a ratio of 5 to 95% by weight, preferably 30 to 70% by weight.

The polyols are preferably those in which an acidic group other than a phenolic hydroxyl group is not present, and examples thereof include a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, and a polycaprolactone polyol compound. A polyol compound having a phenolic hydroxyl group, a polycarbonate polyol, or the like. The molecular weight of the polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, still more preferably 1,000 or less. The curable epoxy resin composition usually contains the polyols in an amount of 50% by weight or less, preferably 30% by weight or less.

Further, the curable epoxy resin composition may contain an ion replenishing agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, or a thermoplastic resin as long as it does not impair the effect as an adhesive. , fillers, flow regulators, plasticizers, defoamers, etc. Examples of the ion-accepting agent include inorganic compounds such as a powdery lanthanum, an anthraquinone, a magnesium-based, an aluminum-based, a calcium-based, a titanium-based, and a mixed system thereof. Examples of the antioxidant include a hindered phenol-based antioxidant. .

An adhesive (epoxy-based adhesive agent) composed of a curable epoxy resin composition containing an epoxy resin as described above is applied to the adhesion surface of the polarizing film or the transparent protective film, or is coated thereon. After the two surfaces are bonded to each other, the surface is coated with an adhesive, and the uncured adhesive layer is cured by irradiation with an active energy ray or heating, and is permeable to the composition of the curable epoxy resin. An adhesive layer composed of a cured layer is attached to the polarizing film and the transparent protective film. The coating method of the subsequent agent is not particularly limited, and various coating methods such as a doctor blade, a wire bar, a die coater, a notch wheel coater, and a gravure coater can be employed.

Among them, the adhesive containing the epoxy resin used in the polarizing film and the transparent protective film can basically be used as a solventless adhesive which does not substantially contain a solvent component, but each coating method is The optimum viscosity range for each is to adjust the viscosity and also contain solvents. The solvent is preferably used in order to dissolve the epoxy resin composition without lowering the optical properties of the polarizing film, and is not particularly limited, and examples thereof include hydrocarbons represented by toluene and ethyl acetate. An organic solvent such as an ester.

When the adhesive is cured by irradiation with an active energy ray, the light source to be used is not particularly limited, and examples thereof include a low-pressure mercury lamp having a light-emitting distribution at a wavelength of 400 nm or less, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, and a firefly. Light, black light, microwave excited mercury lamp and metal halide lamp. The light irradiation intensity of the curable epoxy resin composition may vary depending on the composition thereof, but the irradiation intensity in the wavelength region effective for activation of the photocationic polymerization initiator is 0.1 to 100 mW/cm ^{2 .} It is better. When the light irradiation intensity of the curable epoxy resin composition is less than 0.1 mW/cm ² , the reaction time becomes too long, and if it exceeds 100 mW/cm ² , the heat and hardenability due to the lamp may be radiated. The heat generation during the polymerization of the epoxy resin composition causes yellowing of the curable epoxy resin composition and deterioration of the polarizing film. The light irradiation time of the curable epoxy resin composition is not particularly limited as long as it is controlled by the entire composition, but the integrated light amount shown by the product of the irradiation intensity and the irradiation time becomes 10 to 5,000 mJ/cm. The mode of ² is set to be preferred. When the cumulative light amount of the curable epoxy resin composition is less than 10 mJ/cm ² , the generation of the active species derived from the photocationic polymerization initiator may be insufficient, and the curing of the adhesive may be insufficient. Further, if the cumulative amount of light exceeds 5,000 mJ/cm ² , the irradiation time becomes extremely long, which may be disadvantageous for improving productivity.

When the adhesive is hardened by heat, it can be used in general. The heating method is not particularly limited, and the heating is usually carried out by using a thermal cationic polymerization initiator prepared in a curable epoxy resin composition to generate a cationic species or a Lewis acid. The specific heating temperature is, for example, It is about 50 to 200 °C.

When curing is performed under any conditions of irradiation with an active energy ray or heating, the polarization degree, transmittance, and hue of the polarizing film, transparency and phase difference characteristics of the transparent protective film, and functions of the polarizing plate are not caused. It is preferred to harden the range of reduction.

(Characteristics of polarizing plate)

The polarizing plate of the present invention preferably has a degree of polarization of 99% or more. More preferably, it is 99.9% or more. Moreover, the monomer permeability is preferably from 38 to 45%. More preferably, it is 40 to 44%. When the polarizing plate of the present invention is used for the viewing side of the liquid crystal display device, it is preferable to use a monomer transmittance of 38 to 43.5%, and when used for the backlight side of the liquid crystal display device, the use of 41 It is better to 44.5%. In particular, when the single-passivity of the polarizing plate on the viewing side is lower than the single-passivity of the polarizing plate on the backlight side, a liquid crystal display device having a high front contrast can be used.

The degree of polarization and monomer permeability are values defined by the following formula.

Monomer penetration rate (λ) = 0.5 × [Tp (λ) + Tc (λ)]

Polarization (λ)=100×[Tp(λ)-Tc(λ)]/[Tp(λ)+Tc(λ)]

Where Tp(λ) is the polarizing film transmittance (%) measured by the relationship between the linear polarization of the incident wavelength λ nm and the parallel Nicols, Tc(λ) is the transmittance (%) of the polarizing film measured by the relationship between the linear polarized light at the incident wavelength λ nm and the crossed Nicols, which is obtained by spectrophotometric measurement of polarized ultraviolet visible light absorption spectrum. measured value. Further, the sensitivity of the single-passivity (λ) and the degree of polarization (λ) obtained for each wavelength are corrected by the sensitivity of the so-called visual sensitivity correction, which is called the visual sensitivity correction monomer transmittance (Ty) and the visual acuity. Sensitivity corrects the degree of polarization (Py). The visual sensitivity correction will be described later. For example, Ty and Py can be easily measured by a spectrophotometer (model: V7100) manufactured by JASCO Corporation.

(High brightness polarizer)

The polarizing plate of the present invention can be used as a high-brightness polarizing plate by laminating a brightness enhancing film on the second transparent protective film side of the polarizing plate (the side opposite to the surface on which the first transparent protective film is disposed) via an adhesive.

As the brightness enhancement film, a polarization conversion element having a function of separating the emitted light from the light source (backlight) into a penetrating polarized light and a reflected polarized light or a scattered polarized light can be used. Such a brightness enhancement film can improve the efficiency of linear polarized light emission by utilizing recursive light from a backlight that reflects polarized or scattered polarized light.

Examples of the brightness enhancement film include an anisotropic reflective polarizing element. The anisotropic reflective polarizing element may be an anisotropic multiple film that transmits linearly polarized light in one direction of vibration and linearly polarized light that reflects the direction of vibration of the other. For example, the product name "DBEF" manufactured by 3M is used (for example, see JP-A-4-268505, etc.). Moreover, the anisotropic reflective polarizing element can be exemplified by a cholesteric liquid crystal layer and λ/4. A composite of plates. The product name "PCF" manufactured by Nitto Denko Co., Ltd. (refer to Japanese Laid-Open Patent Publication No. Hei 11-231130, etc.). Further, examples of the anisotropic reflective polarizing element include a reflective grating type polarizing element. The reflective grating type polarizing element is a metal grating reflective polarizing element that emits a polarized light in a visible light region (refer to the specification of US Pat. No. 6288840, etc.), and puts the fine particles of the metal into a high In the molecular matrix, it is extended (refer to Japanese Laid-Open Patent Publication No. Hei 8-184701, etc.).

A functional layer may be formed on the opposite side of the bonding surface of the polarizing plate of the brightness enhancing film.

Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusion layer, and a retardation layer having a phase difference of 1/4 wavelength, whereby the adhesion to the tape for the backlight module can be improved. Improve the uniformity of the displayed image.

The adhesive for bonding the polarizing plate and the brightness enhancing film can be suitably selected, for example, an acrylic polymer, a polyoxymethylene polymer, a polyester, a polyurethane, a polyamide, a polyvinyl ether, a vinyl acetate/chlorine A polymer such as an ethylene copolymer, a modified polyolefin, an epoxy-based, a fluorine-based, a natural rubber, or a synthetic rubber is used as a substrate polymer. The adhesive is particularly excellent in optical transparency, and exhibits excellent wettability, cohesiveness, and adhesion properties, and is excellent in weather resistance and heat resistance.

(adhesive layer)

The adhesive layer is excellent in optical transparency and exhibits appropriate wetting. Adhesive properties such as properties, aggregability, and adhesion may be sufficient, but those having excellent durability and the like are preferred. Specifically, examples of the adhesive for forming the pressure-sensitive adhesive layer include a pressure-sensitive adhesive (also referred to as an acrylic pressure-sensitive adhesive) composed of an acrylic resin.

The adhesive layer formed of the acrylic adhesive is not particularly limited, but it is preferably used such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and (methyl). a (meth) acrylate resin of 2-ethylhexyl acrylate or a copolymerized resin of two or more of these (meth) acrylates. Further, among the resins, the polar monomers are copolymerized. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylamide, and (meth)acrylic acid. A monomer having a polar functional group such as a carboxyl group, a hydroxyl group, a decylamino group, an amine group or an epoxy group of 2-N,N-dimethylaminoethyl ester and glycidyl (meth) acrylate. Further, in the adhesive, an acrylic resin and a crosslinking agent are usually formulated at the same time.

In addition, various additives can be formulated in the adhesive. Suitable additives are decane coupling agents or antistatic agents. The decane coupling agent is effective in improving the adhesion to the glass. Antistatic agents are effective in reducing or preventing the generation of static electricity. In other words, when the polarizing plate is attached to the liquid crystal cell via the adhesive layer, the surface protective film (separator) which has been temporarily protected by the adhesive layer and then temporarily protected is attached to the liquid crystal cell, but when the surface protective film is peeled off The generated static electricity sometimes causes poor alignment of the liquid crystal in the cell, which results in poor display of the IPS mode liquid crystal display device.

Matching resistance in reducing or preventing such static electricity generation The electrostatic agent is effective.

The thickness of the adhesive is preferably from 3 to 50 μm . More preferably, it is 3 to 30 μm .

The storage elastic modulus of the above-mentioned adhesive is not particularly limited. For example, in order to suppress the warpage of the liquid crystal panel in the high temperature test and the high temperature and high humidity test, the adhesion modulus of the adhesive at 23 ° C is 1.0 MPa. The following are preferred. More preferably, it is 0.8 MPa or less, and still more preferably 0.5 MPa or less.

Further, the adhesive may or may not contain an acid. When an acid is contained, it is preferred that the acid is used in a small amount. Specifically, the amount of the acid component in all the monomer components is preferably less than 1.0% by weight based on the total amount of the monomer components.

When the adhesive layer is electrically conductive, the resistance value may be appropriately selected, for example, in a range of 1 × 10 ⁹ to 1 × 10 ¹¹ Ω / □ in a manner that does not hinder the operation of the touch panel of a smart phone or the like. It is better.

(Polarizer with adhesive)

The polarizing plate of the present invention is a polarizing plate to which an adhesive layer is provided on at least one surface and is provided with an adhesive. The adhesive layer can be the same as the adhesive described above.

(High-brightness polarizer with adhesive)

The high-brightness polarizing plate of the present invention is a high-brightness polarizing plate to which an adhesive layer is provided on at least one surface and is provided with an adhesive. The adhesive can be set It is on the transparent protective film disposed on the liquid crystal cell side. The adhesive layer can be the same as the adhesive described above.

(use)

The polarizing plate and the high-brightness polarizing plate of the present invention are suitable as constituent members of a liquid crystal panel and a liquid crystal display device, and are particularly suitable for use in small and medium-sized liquid crystal display devices such as mobile phones and portable terminal devices 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, for example, preferably 55 mm × 41 mm or more, more preferably 154 mm × 87 mm or more, and is preferably 233 mm × 310 mm or less, more preferably 229 mm × 305 mm or less, and further The best is 174mm × 231mm.

(liquid crystal display device)

The polarizing plate and the high-brightness polarizing plate are used for a liquid crystal display device in which a liquid crystal panel is bonded to an IPS mode liquid crystal cell via an adhesive layer. A polarizing plate of a contract type or a conventional polarizing plate can be attached to the back side of the liquid crystal panel to which the polarizing plate of the present invention is bonded. In particular, it is preferable that a polarizing plate provided with a transparent protective film to which an anti-glare property is provided is bonded to the viewing side of the liquid crystal panel.

When a liquid crystal display device is formed, a cellulose resin film, a polyethylene terephthalate resin film, or a methyl methacrylate which is provided with anti-glare property and light resistance is attached to the viewing side of the liquid crystal panel. A polarizing plate of a resin film is preferred. Further, a cellulose resin film, a polyethylene terephthalate resin film, and a methyl group are bonded to the back side of the liquid crystal panel. A polarizing plate of a methyl olefin resin film or a polypropylene resin film is preferable. When a polyethylene terephthalate resin film, a methyl methacrylate resin film, or a polypropylene resin film is used, water vapor is worn compared to a cellulose triacetate film which is generally used for a protective film of a polarizing plate. Since the transmittance and the water absorption rate are small, and the dimensional change is small, the durability of the polarizing plate is improved, and the display quality deterioration of the display device using the polarizing plate with environmental changes is suppressed. Further, by further containing an ultraviolet absorber, the durability of the polarizing plate using the same is higher than that of the cellulose triacetate film.

The combination of the polarizing plate on the viewing side and the back side of the liquid crystal panel is not limited, and any combination can be selected. As an example, a polarizing plate provided with a polyethylene terephthalate resin film to which anti-glare property and light resistance are provided is bonded to the viewing side of the liquid crystal panel, and is laminated on the back side. A polarizing plate having a polypropylene resin film.

Example

Hereinafter, the present invention will be described in further detail by way of examples, but the invention is not limited by the examples. In the examples, the content and the % and the amount of the use amount are used as the weight basis unless otherwise noted. Further, the evaluation methods used in the examples are as follows.

(1) Thickness: Measured using a digital micrometer MH-15M manufactured by Nikon Co., Ltd.

(2) In-plane retardation Re and thickness direction retardation Rth: a phase difference meter using a parallel Nicols rotation method, KOBRA-ADH manufactured by Oji Scientific Instruments Co., Ltd., at a wavelength of 590 nm, 483 nm at 23 ° C or Light was measured at 755 nm.

(3) Dimensional change rate of polarizing plate

The polarizing plate was cut into a square of 100 mm square in the direction of the absorption axis of 100 mm × 100 mm in the direction of the penetration axis, and allowed to stand in an environment of 85 ° C for 100 hours. The size of the polarizing plate was measured using a two-dimensional measuring device "NEXIV VMR-12072" manufactured by Nikon Co., Ltd. The dimensional change rate of the polarizing plate is ΔL as determined by subtracting the dimension (L ₁ ) in the absorption axis direction after the test from the dimension (L ₀ ) in the absorption axis direction before the test, as follows. Calculated by the formula.

Dimensional change rate of polarizing plate = △ L / L ₀

(4) Storage elastic modulus: The storage elastic modulus (G') of the adhesive layer was measured by the following (I) to (III).

(I) Two 25 ± 1 mg samples were taken out from the adhesive layer and formed into a slightly spherical shape.

(II) The obtained slightly spherical sample was attached to the upper and lower surfaces of the I-shaped mold, and the uppermost and lower surfaces were covered with an L-shaped jig. The composition of the measurement sample was changed into an L-shaped jig/adhesive/I-type jig/adhesive/L-type jig.

(III) The elastic modulus (G') of the sample stored in this manner is The dynamic viscoelasticity measuring apparatus [DVA-220, manufactured by IT Measurement Control Co., Ltd.] was measured under the conditions of a temperature of 23 ° C, a number of cycles of 1 Hz, and an initial deformation of 1 N.

(5) Adhesion to glass: The polarizing plate provided with the adhesive layer was cut into a width of 25 mm, and the glass plate was attached to the side of the adhesive layer, and applied at a temperature of 50 ° C and a pressure of 5 atm for 20 minutes. After pressurization, and then standing at 23 ° C for one day, AZ1 manufactured by Shimadzu Corporation was used, and the peeling was measured in the direction of 180° with respect to the longitudinal direction of the cut polarizing plate in accordance with JIS Z 0237. Time stress.

(6) Elastic modulus (measured in accordance with JIS K 7161)

The test piece was cut into a width of 15 mm, and the test piece was stretched at a speed of 50 mm/min using AZ1 manufactured by Shimadzu Corporation, and the elastic modulus was obtained from the deformation stress curve.

(7) Moisture permeability (measured according to JI Z 0208)

The cross-sectional area of 27 cm ² was determined in accordance with JIS Z 0208. In the specification of JIS Z 0208, it is intended to measure the moisture permeability at any temperature of 25 ° C or 40 ° C, and the present specification employs a temperature of 40 ° C.

(Manufacturing Example 1) Production of polarizing film

(Production of polarizing film A with a thickness of 7 μm )

A polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times by dry stretching, thereby directly maintaining a tight state, pure at 60 ° C After immersing in water for 1 minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed at 72 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 8.5 / 8.5 / 100. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizing element having a thickness of 7 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Production of polarizing film B with a thickness of 12 μm )

A polyvinyl alcohol film having a thickness of 30 μm (average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times by dry stretching, thereby directly maintaining a tight state, pure at 60 ° C After immersing in water for 1 minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed at 72 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 8.5 / 8.5 / 100. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizing element having a thickness of 12 μm in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Production of polarizing film C with a thickness of 23 μm )

A polyvinyl alcohol film having a thickness of 60 μm (average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times by dry stretching, thereby directly maintaining a tight state, pure at 60 ° C. After immersing in water for 1 minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed at 72 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 8.5 / 8.5 / 100. Then, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizing element having a thickness of 23 μm in which a directional iodine was adsorbed on a polyvinyl alcohol film.

(Brightness film A)

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

(Production Example 2) Preparation of water-soluble adhesive

3 parts of carboxyl-modified polyvinyl alcohol [KL-318, manufactured by KURARAY Co., Ltd.] was dissolved in 100 parts of water, and a polyamine-based epoxy-based additive of a water-soluble epoxy compound was added to the aqueous solution [Sumika Chemtex Co., Ltd. The company's Sumirez Resin 650 (30), an aqueous solution with a solid concentration of 30%], 1.5 parts, as a water-soluble adhesive.

(Manufacturing Example 3) Modulation of an adhesive

An adhesive layer having a thickness of 20 μm was formed from a commercially available acrylic adhesive. The storage modulus of the adhesive layer was 0.42 MPa at 23 °C. Further, the adhesive layer was bonded to a polarizing plate to be described later, and the glass adhesion force when bonded to the glass was 5 N/25 mm.

[Example 1]

The second transparent protective film composed of cellulose triacetate was bonded to one side of the polarizing film A (thickness 7 μm ) in which the iodine was adsorbed and oriented on the polyvinyl alcohol film [KCICAUA, manufactured by KONICA MINOLTA Co., Ltd., thickness 25 μm ] On the other side (the surface on the side of the liquid crystal cell), a first transparent protective film made of a cycloolefin polymer [trade name "ZF14" manufactured by Japan ZEON Co., Ltd.) and a thickness of the polarizing film of 3.3 times and thickness are bonded. 23 μm , in-plane retardation at a wavelength of 590 nm (Re(590))=2.1 nm, retardation in the thickness direction at a wavelength of 590 nm (Rth(590))=2.8 nm, retardation in the thickness direction at a wavelength of 483 nm (Rth(483) ) = 2.5 nm, retardation in the thickness direction at a wavelength of 755 nm (Rth (755)) = -4.2 nm, elastic modulus = 2315 MPa, and moisture permeability = 17 g / m ² ‧ 24 hours], and a polarizing plate was produced. The film is applied to the first transparent protective film or the second transparent protective film by separately preparing a water-soluble adhesive prepared in advance, and is laminated on the polarizing film via an adhesive, and then dried at 80 ° C. In minutes. The obtained polarizing plate was aged at 40 ° C for 168 hours, and then the dimensional change rate was measured and found to be 0.92%.

An acrylic adhesive is applied to the separator to form an adhesive layer, and is laminated on the side of the first transparent protective film, and the adhesive is formed on the polarizing plate with the adhesive attached to the adhesive layer.

Dissolving the IPS mode liquid crystal display device [Mobile phone (Model: W62S) manufactured by Sony Ericsson Mobile Co., Ltd.], and peeling and removing the polarizing plates on both sides of the liquid crystal cell, on the side of the adhesive layer on which the respective separators are peeled off, In place of the liquid crystal cell, two polarizing plates with an adhesive attached to Example 1 were bonded to the front side (viewing side) and the back side (light incident side) of the liquid crystal cell in such a manner as to be in a crossed Nicols state. Polarization on both sides board. At this time, the absorption axis of the polarizing plate on the front side (viewing side) is arranged in parallel with the orientation direction when liquid crystal molecules in the liquid crystal cell are applied without voltage (black screen). The liquid crystal display device of the IPS mode is assembled and lighted again, and the color shift of the black screen state in which the voltage is not applied to the liquid crystal cell is measured by the liquid crystal viewing angle/chromaticity characteristic measuring device EZ contrast manufactured by ELDIM Co., Ltd., and the result is color-shift. The color shift Δu'v' is 0.15.

[Embodiment 2]

One side of the polarizing film A (thickness: 7 μm ) in which the iodine is adsorbed and oriented on the polyvinyl alcohol film is bonded to a transparent protective film composed of cellulose triacetate [KCICAUA, manufactured by KONICA MINOLTA Co., Ltd., thickness 25 μm ], The other side (the surface on the liquid crystal cell side) is bonded to a transparent protective film composed of a cycloolefin polymer [trade name "ZF14-013" obtained by Japan ZEON Co., Ltd., thickness: 13 μm , thickness of the polarizing film 1.9 times, in-plane retardation at a wavelength of 590 nm (Re(590))=0.8 nm, retardation in the thickness direction at a wavelength of 590 nm (Rth(590))=3.4 nm, retardation in the thickness direction at a wavelength of 483 nm (Rth(483)) = 3.5 um, retardation in the thickness direction of wavelength 755 nm (Rth (755)) = 2.8 nm, elastic modulus = 2225 MPa, moisture permeability = 35 g / m ² ‧ 24 hours], and a polarizing plate was produced. The water-soluble adhesives prepared in advance are applied to the first transparent protective film or the second transparent protective film, and the polarizing film is laminated via an adhesive, and then dried at 80 ° C for 5 minutes. . The obtained polarizing plate was aged at 40 ° C for 168 hours, and the dimensional change ratio was measured and found to be 1.21%.

Applying an acrylic adhesive to the separator to form a sticky The agent layer is laminated on the side of the first transparent protective film, and the adhesive layer formed on the polarizing plate with the adhesive is laminated with a member of the separator. The polarizing plate with an 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 Δu'v' was 0.15.

[Example 3]

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

An acrylic adhesive is applied to the separator to form an adhesive layer, and is laminated on the side of the first transparent protective film, and the adhesive is formed on the polarizing plate with the adhesive attached to the adhesive layer. The polarizing plate with an 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 Δu'v' was 0.15.

[Example 4]

On the second transparent protective film side of the polarizing plate of Example 1, the brightness enhancing film A was bonded via an adhesive to produce a high-brightness polarizing plate. The dimensional change rate of the high-brightness polarizing plate was measured and found to be 0.78%.

An adhesive layer is formed on the separator to form an adhesive layer, and is laminated on the side of the first transparent protective film, and the adhesive is laminated on the high-brightness polarizing plate with the adhesive.

Decomposition of IPS mode liquid crystal display device [Mobile phone made by Sony Ericsson Mobile (Model: W62S)], LCD The polarizing plates on both sides of the unit are peeled off and removed, and the polarizing plate of the first embodiment is attached to the liquid crystal cell in such a manner that the adhesive layer layer of each of the separators is stripped to be in a crossed Nicols state. On the front side (viewing side), the high-intensity polarizing plate produced in Example 4 was bonded to the back side (light incident side) instead of the polarizing plates on both sides of the liquid crystal cell. At this time, the absorption axis of the polarizing plate on the front side (viewing side) is arranged in parallel with the orientation direction when liquid crystal molecules in the liquid crystal cell are applied without voltage (black screen). The liquid crystal display device of the IPS mode is assembled and lighted again, and the color shift of the black screen state in which the voltage is not applied to the liquid crystal cell is measured by the liquid crystal viewing angle/chromaticity characteristic measuring device EZ contrast manufactured by ELDIM Co., Ltd., and the result is color-shift. The color shift Δu'v' is 0.14.

[Example 5]

On the second transparent protective film side of the polarizing plate of Example 2, the brightness enhancing film A was bonded via an adhesive to prepare a high-brightness polarizing plate. The dimensional change rate of the high-brightness polarizing plate was measured and found to be 1.04%.

An adhesive layer is formed on the separator to form an adhesive layer, and is laminated on the side of the first transparent protective film, and the adhesive is laminated on the high-brightness polarizing plate with the adhesive.

In the same manner as in the fourth embodiment, the polarizing plate of the first embodiment was bonded to the front side (the viewing side) of the liquid crystal cell in the form of a crossed Nicols, and the high-intensity polarized light produced in Example 5 was used. The plate was attached to the back side (light incident side), and the color shift was measured. As a result, the color shift Δu'v' was 0.14.

[Embodiment 6]

The brightness enhancement film A was bonded to the second transparent protective film side of the polarizing plate of Example 3 via an adhesive to prepare a high-brightness polarizing plate. The dimensional change rate of the high-brightness polarizing plate was measured and found to be 0.88%.

An adhesive layer is formed on the separator to form an adhesive layer, and is laminated on the side of the first transparent protective film, and the adhesive is laminated on the high-brightness polarizing plate with the adhesive.

In the same manner as in the fourth embodiment, the polarizing plate of the first embodiment was bonded to the front side (viewing side) of the liquid crystal cell in the form of a crossed Nicols, and the high-intensity polarized light produced in Example 6 was used. The plate was attached to the back side (light incident side), and the color shift was measured. As a result, the color shift Δu'v' was 0.14.

[Comparative Example 1]

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

An acrylic adhesive prepared on the previous separator was attached to the first transparent protective film side of the polarizing plate to prepare a polarizing plate with an adhesive. The polarizing plate with the adhesive was attached 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 Δu'v' was 0.15.

The embodiments and examples disclosed in the present disclosure are all The points are illustrative and not intended to limit the inventors of the present invention. The scope of the present invention is defined by the scope of the claims and the scope of the appended claims.

(industrial availability)

The polarizing plate of the present invention suppresses the dimensional change caused by the absorption axis direction, and is suitable for a small-sized and medium-sized liquid crystal display device such as a mobile phone or a portable terminal.

Claims (10)

A polarizing plate which is 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, and the polarizing film has a thickness of 15 μm or less; The transparent protective film has a retardation Re(590) of 10 nm or less in a plane at a wavelength of 590 nm, an absolute value of a retardation Rth (590) in a thickness direction of a wavelength of 590 nm of 10 nm or less, and a retardation Rth of a thickness direction of a wavelength of 480 to 750 nm (480). A transparent resin film having an absolute value of -750) of 15 nm or less; the thickness of the first transparent protective film being greater 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 followed 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 followed by an adhesive containing a resin composition containing irradiation with active energy rays or heating. Hardened epoxy resin. The polarizing plate according to claim 3, wherein the epoxy resin contains a compound having one or more epoxy groups bonded to the 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 or a polyethylene terephthalate resin. Membrane or cellulose A resin film. The polarizing plate according to any one of claims 1 to 5, wherein the polarizing plate is for a mobile phone or a portable terminal. A high-brightness polarizing plate which is formed by a layer of a brightness enhancing film on the second transparent protective film side of the polarizing plate according to any one of the first to sixth aspects of the invention. The high-brightness polarizing plate of the seventh aspect of the invention, wherein the high-brightness polarizing plate is used for a mobile phone or a portable terminal. An IPS mode liquid crystal display device, which is disposed on at least one side of an IPS mode liquid crystal cell, and is configured with a polarizing plate according to any one of claims 1 to 6, or a patent application scope 7 or The high-intensity polarizing plate described in 8 items is formed. The IPS mode liquid crystal display device according to claim 9, wherein the IPS mode liquid crystal display device is used for a small-to-medium-sized liquid crystal display device.