JP6462254B2 - Polarizing plate, high-intensity polarizing plate, and IPS mode liquid crystal display device - Google Patents

Description

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

  Liquid crystal display devices are used in various display devices by taking advantage of low power consumption, operation at low voltage, light weight and thinness. This liquid crystal display device is composed of many optical members such as a liquid crystal cell, a polarizing plate, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. An example of the liquid crystal display device is an in-plane switching (IPS) mode liquid crystal display device. For example, Patent Document 1 discloses a cycloolefin having a specific retardation value in a polarizer having a thickness of 25 μm. The example of the polarizing plate which laminated | stacked the system resin film as a protective film, and the IPS mode liquid crystal display device containing this is shown.

JP 2010-107953 A

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

That is, the present invention provides the following polarizing plate, high-intensity polarizing plate, and liquid crystal display device.
[1] 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,
The thickness of the polarizing film is 15 μm or less,
The first transparent protective film is
In-plane retardation Re (590) at a wavelength of 590 nm is 10 nm or less,
The absolute value of retardation Rth (590) in the thickness direction at a wavelength of 590 nm is 10 nm or less,
The absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less,
A polarizing plate, wherein the thickness is a transparent resin film 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 adhered by a water-soluble adhesive containing a polyvinyl alcohol resin and an epoxy compound.
[3] The polarizing plate according to [1], wherein the first transparent protective film and the polarizing film are bonded by an adhesive made of a resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating.
[4] The polarizing plate according to [3], wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.
[5] The polarizing plate according to any one of [1] to [4], wherein the second transparent protective film comprises a methyl methacrylate resin film, a polyethylene terephthalate resin film, or a cellulose resin film.
[6] The polarizing plate according to any one of [1] to [5], wherein the polarizing plate is for a mobile phone or a portable information terminal.
[7] High-intensity polarized light in which a brightness enhancement film is laminated via an adhesive on the side opposite to the surface on which the first transparent protective film of the polarizing plate according to any one of [1] to [6] is disposed Board.
[8] The high-intensity polarizing plate according to [7], wherein the high-intensity polarizing plate is for a mobile phone or a portable information terminal.
[9] The polarizing plate according to any one of [1] to [6] or the high-intensity polarizing plate according to [7] or [8] is disposed on at least one surface of the IPS mode liquid crystal cell. IPS mode liquid crystal display device.
[10] The IPS mode liquid crystal display device according to [9], wherein the IPS mode liquid crystal display device is for a small and medium size.

  The polarizing plate of the present invention is suitable for a small and medium-sized liquid crystal display device having a small screen such as a mobile phone or a personal digital assistant, in which a dimensional change occurring in the absorption axis direction is suppressed.

(Polarizing film)
The polarizing film used in the present invention is usually a step of uniaxially stretching a polyvinyl alcohol resin film by a known method, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, The polyvinyl alcohol resin film on which the dichroic dye is adsorbed is manufactured through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

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

  What formed the polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, considering that the thickness of the obtained polarizing film is 15 μm or less. When the film thickness of the raw film is 35 μm or more, it is necessary to increase the draw ratio when producing the polarizing film, and the dimensional shrinkage of the resulting polarizing film tends to increase. On the other hand, when the film thickness of the raw film is 5 μm or less, the handling property at the time of stretching is lowered, and there is a tendency that problems such as cutting are likely to occur during production.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

  As a method of dyeing the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1800 seconds.

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

  The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

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

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

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

  Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol resin film in the production process of the polarizer may be performed in accordance with, for example, the method described in JP2012-159778A. . In the method described in this document, a polyvinyl alcohol resin layer to be a polarizer is formed by coating a polyvinyl alcohol resin on a base film.

  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 resin film. For example, a cyclic olefin resin obtained by polymerizing a cyclic olefin monomer such as norbornene and other cyclopentadiene derivatives using a polymerization catalyst, or ethylene And a film made of a chain olefin resin obtained by polymerizing a chain olefin monomer such as propylene using a polymerization catalyst. Especially, the film which consists of cyclic olefin resin is preferable at the point which obtains the film which satisfy | fills the retardation which this invention defines.

  Examples of the cyclic olefin-based resin include a resin obtained by ring-opening metathesis polymerization using cyclopentadiene and olefins by a Diels-Alder reaction or a derivative thereof as a monomer, followed by hydrogenation, and dicyclopentadiene and olefin. Resin, norbornene, tetracyclododecene, and derivatives thereof obtained by performing ring-opening metathesis polymerization using tetracyclododecene or its derivative obtained from dihydric acid or methacrylates by Diels-Alder reaction as a monomer, followed by hydrogenation A ring-opening metathesis copolymerization using two or more cyclic olefin monomers in the same manner, followed by hydrogenation, a resin obtained by hydrogenation, norbornene, tetracyclododecene, or The derivatives, resins obtained by addition copolymerization of aromatic compounds and the like having a vinyl group.

  Cyclic olefin-based resins can be easily obtained as commercial products. For example, under the trade names, Topas (Topas Advanced Polymers GmbH), Arton (manufactured by JSR Corporation), Zeonoa, Zeonex (and above, Japan) Zeon Co., Ltd.), and Apel (Mitsui Chemicals Co., Ltd.).

  Examples of the chain olefin resin include polyethylene or polypropylene resin. Among them, a propylene homopolymer and a comonomer mainly composed of propylene and copolymerizable therewith are usually copolymerized at a rate of 1 to 20% by weight, preferably at a rate of 3 to 10% by weight. Copolymers can be used.

  Polypropylene resins can be easily obtained as commercial products. For example, Prime Polypro (manufactured by Prime Polymer Co., Ltd.), Novatec, Wintech (manufactured by Nippon Polypro Co., Ltd.), Sumitomo Nobrene (manufactured by Sumitomo Chemical Co., Ltd.), sun allomer (manufactured by Sun Allomer Co., Ltd.)

  As a method for producing the first transparent protective film from the cyclic olefin resin or the chain olefin resin, a method corresponding to the resin may be appropriately selected. For example, a resin dissolved in a solvent is cast onto a metal band or drum, and a solvent casting method for obtaining a film by drying and removing the solvent, and the resin is heated and kneaded to a temperature higher than its melting temperature and extruded from a die, A melt extrusion method for obtaining a film by cooling with a cooling drum is employed. Of these, the melt extrusion method is preferably employed from the viewpoint of productivity.

The retardation Rth in the thickness direction of the first transparent protective film is a value obtained by multiplying the refractive index difference between the in-plane and thickness directions by the thickness of the film, and is represented by the following formula (1). The in-plane retardation Re is a value obtained by multiplying the in-plane refractive index difference 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 thickness direction retardation value _{(Rth) = {(n x} + n y) / 2-n z} × d (1)
Plane retardation value _{(Re) = (n x -n} y) × d (2)

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

  The first transparent protective film is composed of a film having both small in-plane and thickness direction retardation. The absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less. However, in a general resin, the wavelength dependence of retardation in both the in-plane and thickness directions is Since it becomes almost linear with respect to the wavelength change, if both the retardation in the thickness direction near the wavelength of 480 nm and 750 nm satisfy the above condition, the above condition is satisfied in the entire range of the wavelength of 480 to 750 nm. Can be seen.

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

  For example, in the solvent casting method, a method of relaxing residual stretching strain in the in-plane direction and residual shrinkage strain in the thickness direction caused by drying the cast resin solution by heat treatment, or the like is employed. In the melt extrusion method, the distance from the die to the cooling drum is reduced as much as possible in order to prevent the resin film from being extruded from the die and cooled, and the extrusion amount and the rotation speed of the cooling drum are also reduced. A method for controlling the film so that the film is not stretched is employed. Moreover, the method of relieving the distortion which remain | survives in the film obtained similarly to the said melt extrusion method by heat processing is also employ | adopted.

  The thickness of the first transparent protective film is preferably 60 μm or less. From the viewpoint of reducing the retardation value in the thickness direction, the thickness is more preferably 30 μm or less, and further preferably 25 μm or less. The thickness of the first transparent protective film is preferably 5 μm or more.

The elastic modulus of the first transparent protective film is preferably 1500 MPa to 3000 MPa, and more preferably 2000 MPa to 2000 MPa, from the viewpoint of workability and the point of not causing problems such as tearing when the polarizing plate is reworked from the panel. 2500 MPa. In order to improve durability under conditions such as 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 hr or less, more preferably 120 g / m ² · 24 hr or less, more preferably 50 g / m ² · 24 hr or less.

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

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

(Second transparent protective film)
The second transparent protective film is preferably made of a material having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. The material for the second transparent protective film is not particularly limited, but for example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin , Acrylonitrile butadiene styrene resin, Acrylonitrile styrene resin, Polyvinyl acetate resin, Polyvinylidene chloride resin, Polyamide resin, Polyacetal resin, Polycarbonate resin, Modified polyphenylene ether resin, Polybutylene terephthalate Examples include films made of resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins, polyimide resins, and the like. The second protective film is disposed on the opposite side of the liquid crystal cell in the liquid crystal display device of the present invention.

  These resins can be used alone or in combination of two or more. These resins can also be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. Modifications such as mixing including the case involving the.

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

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

  This methyl methacrylate resin can be usually obtained by polymerizing a monofunctional monomer mainly composed of methyl methacrylate in the presence of a radical polymerization initiator. In the polymerization, a polyfunctional monomer and a chain transfer agent can coexist if necessary.

  The monofunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylic acid 2 -Methacrylic acid esters other than methyl methacrylate such as ethylhexyl and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-acrylate Acrylic esters such as ethylhexyl and 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, And hydroxyalkyl acrylates such as 2- (hydroxymethyl) butyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; vinyltoluene and α-methylstyrene Substituted styrenes; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide it can. Such monomers may be used alone or in combination of two or more.

  The polyfunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited. For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , The hydroxyl groups at both ends of ethylene glycol or its oligomers such as tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate were esterified with acrylic acid or methacrylic acid Propylene glycol or its oligomers with both terminal hydroxyl groups esterified with acrylic acid or methacrylic acid; Neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate Lilate and hydroxyl group of dihydric alcohol such as butanediol di (meth) acrylate esterified with acrylic acid or methacrylic acid; Bisphenol A, alkylene oxide adduct of bisphenol A, or both terminal hydroxyl groups of these halogen-substituted products Esterified with acrylic acid or methacrylic acid; polyhydric alcohols such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid, and terminal hydroxyl groups of these polyhydric alcohols with glycidyl acrylate or glycidyl methacrylate Epoxy group ring-opening addition; succinic acid, adipic acid, terephthalic acid, phthalic acid, dibasic acids such as halogen substitution products, and alkylene oxide adducts Those with an epoxy group of glycidyl acrylate or glycidyl methacrylate by ring-opening addition; allyl (meth) acrylate; and aromatic divinyl compounds such as divinylbenzene and the like. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

  As the methyl methacrylate resin, those modified by a reaction between functional groups copolymerized with the resin are also used. As the reaction, for example, demethanol condensation reaction in the polymer chain of a methyl ester group of methyl acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, or a carboxyl group of acrylic acid and 2- (hydroxymethyl) acrylic Examples thereof include a dehydration condensation reaction within a polymer chain of a hydroxyl group of methyl acid.

  Commercially available methyl methacrylate resins can be easily obtained. For example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acripet (manufactured by Mitsubishi Rayon Co., Ltd.), Delpet (Asahi Kasei) Co., Ltd.), Parapet (manufactured by Kuraray Co., Ltd.), and Acribuer (manufactured by Nippon Shokubai Co., Ltd.).

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

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

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

  Polyethylene terephthalate resin can be produced by direct polycondensation of terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), dialkyl esters of terephthalic acid and ethylene glycol (and if necessary) A transesterification reaction with a dialkyl ester of another dicarboxylic acid or other diol), and a polycondensation, and an ethylene glycol ester of terephthalic acid (and other dicarboxylic acids as required) For example, a method of polycondensation of other diol ester) in the presence of a catalyst is employed. Furthermore, if necessary, solid-state polymerization can be performed to improve the molecular weight or reduce the low molecular weight components.

  The polypropylene resin refers to a polymer obtained by polymerizing a chain olefin monomer in which 80% or more of the repeating units are propylene monomers among the chain olefin resins.

  Among these, a propylene homopolymer is preferable. Also preferred is a copolymer comprising propylene as a main component and a comonomer copolymerizable therewith in an amount of 1 to 20% by weight, preferably 3 to 10% by weight.

  When using a propylene copolymer, ethylene, 1-butene, and 1-hexene are preferable as a comonomer copolymerizable with propylene. Especially, since it is comparatively excellent in transparency, what copolymerized ethylene in the ratio of 3 to 10 weight% is preferable. By setting the copolymerization ratio of ethylene to 1% by weight or more, an effect of increasing transparency appears. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin is lowered and the heat resistance required for the second transparent protective film may be impaired.

  Among propylene homopolymers, those having a xylene soluble component (CXS (cold xylene soluble) component) at 20 ° C. of 1% by weight or less are more preferred, and those having a CXS component of 0.5% or less are preferred. Further preferred.

  Such a polypropylene-based resin can be easily obtained as a commercial product as described above.

  Cellulosic resins are those in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp) are substituted with acetyl groups, propionyl groups and / or butyryl groups. Further, it refers to a cellulose organic acid ester or a cellulose mixed organic acid ester. Examples include cellulose acetates, propionic acid esters, butyric acid esters, and mixed esters thereof. Among these, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like are preferable.

  As a method of using a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, and a cellulose resin as a second transparent protective film for adhering to a polarizing film, a method corresponding to each resin is appropriately selected. There is no particular limitation. For example, a resin dissolved in a solvent is cast onto a metal band or drum, and a solvent casting method for obtaining a film by drying and removing the solvent, and the resin is heated and kneaded to a temperature higher than its melting temperature and extruded from a die, A melt extrusion method for obtaining a film by cooling is employed. In this melt extrusion method, a single layer film may be extruded or a multilayer film may be simultaneously extruded.

  The film used as the second transparent protective film can be easily obtained as a commercial product. If it is a methyl methacrylate-based resin film, the trade name is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), acrylite, Examples thereof include acryloprene (manufactured by Mitsubishi Rayon Co., Ltd.), Delagrass (manufactured by Asahi Kasei Co., Ltd.), paragrass, comograss (manufactured by Kuraray Co., Ltd.), and acrylic viewer (manufactured by Nippon Shokubai Co., Ltd.). If it is a polyethylene terephthalate-type resin film, Novaclear (made by Mitsubishi Chemical Corporation), a Teijin A-PET sheet (made by Teijin Chemicals Ltd.), etc. are mentioned by a brand name, respectively. For polypropylene-based resin films, FILMAX CPP film (manufactured by FILMAX), Santox (manufactured by Santox Co., Ltd.), Tosero (manufactured by Tosero Co., Ltd.), Toyobo pyrene film (manufactured by Toyobo Co., Ltd.) Trefan (made by Toray Film Processing Co., Ltd.), Nihon Polyace (made by Nippon Polyace Co., Ltd.), Dazai FC (made by Phutamura Chemical Co., Ltd.) For cellulose resin films, Fujitac TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.) and the like can be mentioned.

  The first transparent protective film and the second transparent protective film used in the present invention can be provided with antiglare properties (haze). The method for imparting antiglare properties is not particularly limited. For example, a method of mixing inorganic fine particles or organic fine particles into the raw material resin to form a film, the multilayer extrusion described above, and the like. A method of forming a two-layer film from a resin in which fine particles are mixed and a resin in which fine particles are not mixed in the other, or a method of forming a three-layer film with the resin mixed with particles on the outside, and inorganic on one side of the film A method of coating a coating solution obtained by mixing fine particles or organic fine particles with a curable binder resin, curing the binder resin, and providing an antiglare layer is employed.

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

  Moreover, the 2nd transparent protective film arrange | positioned on the opposite side to the liquid crystal cell side can also contain a well-known additive as needed. However, since transparency is required in optical applications, it is preferable to keep the amount of additives added to a minimum. Known additives include, for example, lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, impact resistance improvers, and the like.

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

  The first transparent protective film and the second transparent protective film are preferably subjected to saponification treatment, corona treatment, plasma treatment and the like prior to bonding with the polarizing film.

  On the first transparent protective film and the second transparent protective film, functional layers such as a conductive layer, a hard coat layer, and a low reflection layer can be further provided. Moreover, the resin composition which has these functions can also be selected for the binder resin which comprises the said glare-proof layer.

(Polarizer)
As a method for laminating the first transparent protective film and the polarizing film and the second transparent protective film and the polarizing film, for example, a method of integrating them using an adhesive is preferable. The thickness of the adhesive layer formed from the adhesive is preferably 0.01 to 35 μm, more preferably 0.01 to 10 μm, and still more preferably 0.01 to 5 μm. Within this range, the first transparent protective film, the second transparent protective film, and the polarizing film do not float or peel off, and an adhesive force having no practical problem can be obtained.

Examples of the adhesive include a solvent-type adhesive, an emulsion-type adhesive, a pressure-sensitive adhesive, a rewet-adhesive, a polycondensation-type adhesive, a solventless-type adhesive, a film-type adhesive, and a hot-melt-type adhesive. Etc. Moreover, an adhesive layer can also be provided through an anchor coat layer as necessary.

  As the adhesive, a water-soluble adhesive is preferable. As this water-soluble adhesive, for example, there is one having a polyvinyl alcohol resin as a main component. A commercially available thing may be used for a water-soluble adhesive, and what mixed the solvent and the additive in the commercially available adhesive may be used. Examples of commercially available polyvinyl alcohol resins that can be used as water-soluble adhesives include KL-318 manufactured by Kuraray Co., Ltd.

  The water-soluble adhesive can contain a crosslinking agent. As a kind of crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt, and the like are preferable, and an epoxy compound is particularly preferable. Examples of commercially available cross-linking agents include Glyoxal and Sumirez Resin 650 (30) manufactured by Sumika Chemtex Co., Ltd.

  Another preferred adhesive is an adhesive made of a resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating.

  When using an adhesive composed of a resin composition containing such an epoxy resin, the adhesive between the polarizing film and the transparent protective film is directed to the active energy ray with respect to the adhesive coating layer interposed between the films to be adhered. Irradiation or heating is performed to cure the curable epoxy resin contained in the adhesive. Curing of the epoxy resin by irradiation with active energy rays or heat is preferably by cationic polymerization of the epoxy resin. In the present invention, the epoxy resin means a compound having two or more epoxy groups in the molecule.

  In the present invention, from the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., the epoxy resin contained in the curable epoxy resin composition that is an adhesive may not contain an aromatic ring in the molecule. preferable. Examples of such epoxy resins include hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, and the like.

  A hydrogenated epoxy resin is obtained by hydrogenating an aromatic ring of an aromatic epoxy resin. Examples of the aromatic epoxy resin include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxy Examples include novolak-type epoxy resins such as benzaldehyde phenol novolak epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol. The hydrogenated epoxy resin is a nuclear hydrogenated polyhydride obtained by selectively subjecting an aromatic polyhydroxy compound such as bisphenol A, which is a raw material for these aromatic epoxy resins, to a nuclear hydrogenation reaction under pressure in the presence of a catalyst. It can be produced by reacting a hydroxy compound with epichlorohydrin. Among these, it is preferable to use hydrogenated bisphenol A glycidyl ether as the hydrogenated epoxy resin.

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

A compound in which a group in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula are removed is bonded to another chemical structure can be an alicyclic epoxy resin. One or more 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 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) exhibits excellent adhesion. Therefore, it is preferably used. Specific examples of suitable alicyclic epoxy resins are shown below, but are not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(In the formula, 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) Epoxycyclohexyl methyl esters of dicarboxylic acid represented by the following formula (III):

(In the formula, 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 ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ 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) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (V):

(In the formula, 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) Diepoxy trispiro compound represented by the following formula (VI):

(In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

  (G) Diepoxy monospiro compound represented by the following formula (VII):

(In the formula, 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 represented by 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 represented by the following formula (IX):

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

  (J) Diepoxytricyclodecanes represented by 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 commercially available or similar, and are more preferably used because they are relatively easily available.

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (I) In which 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 compounds of [In the formula (I), R ¹ = 4-CH ₃ , R ² = 4-CH ₃ compound],
(C) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in the formula (II), R ³ = R ⁴ = H, n = 2 Compound〕,
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [compound of formula (III), wherein R ⁵ = R ⁶ = H, p = 4] ,
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-CH ₃ , p = 4 compound]
(F) etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the formula (V), R ⁹ = R ¹⁰ = H, r = Two compounds].

  Moreover, as an aliphatic epoxy resin, the polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct can be mentioned. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; Diglycidyl ether of glycol; Polyether of polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin A glycidyl ether etc. are mentioned.

  An epoxy resin may be used individually by 1 type, and may use 2 or more types together. The epoxy equivalent of the epoxy resin used by this invention is 30-3,000 g / equivalent normally, Preferably it exists in the range of 50-1,500 g / equivalent. When the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizing plate after curing may be reduced, or the adhesive strength may be reduced. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components contained in the adhesive may be lowered.

  In the present invention, cationic polymerization is preferably used as the curing reaction of the epoxy resin from the viewpoint of reactivity. For that purpose, it is preferable to mix | blend a cationic polymerization initiator with the curable epoxy resin composition which is an adhesive agent. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating with active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., and starts an epoxy group polymerization reaction. Regardless of the type of cationic polymerization initiator, it is preferable from the viewpoint of workability that latency is imparted. Hereinafter, a cationic polymerization initiator that generates a cationic species or Lewis acid upon irradiation of active energy rays and initiates a polymerization reaction of an epoxy group is referred to as a “photo cationic polymerization initiator”, and generates a cationic species or a Lewis acid by heat. The cationic polymerization initiator that initiates the polymerization reaction of the epoxy group is referred to as “thermal cationic polymerization initiator”.

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

  Although it does not specifically limit as a photocationic polymerization initiator, For example, aromatic diazonium salt; Onium salts, such as an aromatic iodonium salt and an aromatic sulfonium salt; Iron-allene complex etc. can be mentioned.

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

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenylsulfide bis ( Hexafluorophosphate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis (hexafluoroantimonate), 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio ] Diphenyl sulfide bis (hexafluorophosphate), 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di ( -Toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4 ' -Diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like.

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

  Commercially available products of these cationic photopolymerization initiators can be easily obtained. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), “UVI-6990” (manufactured by Union Carbide), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA, Inc.), “CI-5102”, “ "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (Nippon Soda Co., Ltd.), "DPI-101", "DPI-102" , "DPI-103", "DPI-105", "MPI-103", "MPI-105", "BBI-101", "BBI-102", "BBI- 03 ”,“ BBI-105 ”,“ TPS-101 ”,“ TPS-102 ”,“ TPS-103 ”,“ TPS-105 ”,“ MDS-103 ”,“ MDS-105 ”,“ DTS-102 ” , “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.

  These photocationic polymerization initiators may be used alone or in admixture of two or more. Among these, aromatic sulfonium salts are particularly preferable because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus can provide a cured product having excellent curability and good mechanical strength and adhesive strength. Used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of epoxy resins, Preferably it is 1 weight part or more, Preferably it is 15 weight part or less. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the epoxy resin, curing becomes insufficient, and mechanical strength and adhesive strength tend to decrease. Moreover, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of epoxy resins, the ionic substance in hardened | cured material will increase and the hygroscopic property of hardened | cured material will become high, and durability. Performance may be degraded.

  When using a photocationic polymerization initiator, the curable epoxy resin composition that is an adhesive may further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes.

  More specific examples of the photosensitizer include, for example, benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o -Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other α, α-diethoxyacetophenone, ben Le, fluorenone, xanthone, uranyl compounds, and halogen compounds and the like, but is not limited thereto. These photosensitizers may be used alone or in combination of two or more. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

  On the other hand, examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These thermal cationic polymerization initiators can be easily obtained as commercial products. For example, “Adeka Opton CP77”, “Adeka Opton CP66” (manufactured by ADEKA Co., Ltd.), “CI” -2639 "," CI-2624 "(manufactured by Nippon Soda Co., Ltd.)," Sun-Aid SI-60L "," Sun-Aid SI-80L "," Sun-Aid SI-100L "(manufactured by Sanshin Chemical Industry Co., Ltd.) Etc.

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

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

  Oxetanes are compounds having a 4-membered ring ether in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3 -Ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, and phenol novolak oxetane . These oxetanes can be easily obtained as commercial products. For example, all of these oxetanes are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. "Aron oxetane OXT-221", "Aron oxetane OXT-212" (manufactured by Toagosei Co., Ltd.) and the like. These oxetanes are usually contained in the curable epoxy resin composition in a proportion of 5 to 95% by weight, preferably 30 to 70% by weight.

  As the polyols, those having no acidic group other than a phenolic hydroxyl group are preferable. For example, a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxyl group, and A polycarbonate polyol etc. can be mentioned. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and preferably 1,000 or less. These polyols are usually contained in the curable epoxy resin composition in a proportion of 50% by weight or less, preferably 30% by weight or less.

  Furthermore, the curable epoxy resin composition is not limited to other additives such as an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, and a thermoplastic resin as long as the effect as an adhesive is not impaired. , Fillers, flow regulators, plasticizers, antifoaming agents, and the like. Examples of the ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based and mixed inorganic compounds. Examples of the antioxidant include hinders. Examples thereof include dophenol antioxidants.

  After the adhesive (epoxy curable adhesive) comprising the curable epoxy resin composition containing the epoxy resin as described above is applied to the adhesive surface of the polarizing film or the transparent protective film, or both adhesive surfaces Bonding on the coated surface of the adhesive, irradiating with active energy rays or heating, this uncured adhesive layer is cured, and the polarizing film and the transparent protective film are cured with a curable epoxy It can bond through the adhesive bond layer which consists of a hardened | cured material layer of a resin composition. The method of applying the adhesive is not particularly limited, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater are employed.

  Here, the adhesive containing the epoxy resin used for adhesion between the polarizing film and the transparent film can basically be used as a solvent-free adhesive that does not substantially contain a solvent component. Since each method has an optimum viscosity range, a solvent may be added to adjust the viscosity. The solvent is preferably one that dissolves the epoxy resin composition well without degrading the optical performance of the polarizing film, and is not particularly limited. For example, hydrocarbons represented by toluene And organic solvents such as esters typified by ethyl acetate.

When the adhesive is cured by irradiation with active energy rays, the light source used is not particularly limited. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a super light source having a light emission distribution at a wavelength of 400 nm or less. High pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, and the like can be mentioned. The light irradiation intensity to the curable epoxy resin composition may vary depending on the composition, but the irradiation intensity in the wavelength region effective for activating the photocationic polymerization initiator is 0.1 to 100 mW / cm ^2. Is preferred. When the light irradiation intensity to the curable epoxy resin composition is less than 0.1 mW / cm ² , the reaction time becomes too long, and when it exceeds 100 mW / cm ² , the heat radiated from the lamp and the curable epoxy resin composition The heat generated during polymerization of the product may cause yellowing of the curable epoxy resin composition or deterioration of the polarizing film. The light irradiation time to the curable epoxy resin composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. Is preferably set to be 10 to 5,000 mJ / cm ² . When the integrated light quantity to the curable epoxy resin composition is less than 10 mJ / cm ² , the generation of active species derived from the photocationic polymerization initiator is not sufficient, and the adhesive may be insufficiently cured. On the other hand, if the integrated light quantity exceeds 5,000 mJ / cm ² , the irradiation time becomes very long, which may be disadvantageous for improving productivity.

  When the adhesive is cured by heat, it can be heated by a generally known method, and the conditions thereof are not particularly limited, but usually the heat blended in the curable epoxy resin composition. Heating is performed at a temperature higher than the temperature at which the cationic polymerization initiator generates cationic species and Lewis acid, and the specific heating temperature is, for example, about 50 to 200 ° C.

  In the range where the polarization degree, transmittance and hue of the polarizing film, transparency and retardation properties of the transparent protective film, and various functions of the polarizing plate are not deteriorated even when cured under the irradiation of active energy rays or heating. It is preferable to cure.

(Characteristics of polarizing plate)
The polarization degree of the polarizing plate of the present invention is preferably 99% or more. More preferably, it is 99.9% or more. The single transmittance is preferably 38 to 45%. More preferably, it is 40 to 44%. When the polarizing plate of the present invention is used on the viewing side of a liquid crystal display device, it is preferable to use a single transmittance of 38 to 43.5%, and when used on the backlight side of a liquid crystal display device, 41 is used. It is preferable to use ˜44.5%. In particular, when the single transmittance of the polarizing plate on the viewing side is lower than the single transmittance of the polarizing plate on the backlight side, a liquid crystal display device with high front contrast can be obtained.

The degree of polarization and the single transmittance are numerical values defined by the following formula.
Single transmittance (λ) = 0.5 × [Tp (λ) + Tc (λ)]
Polarization degree (λ) = 100 × [Tp (λ) −Tc (λ)] / [Tp (λ) + Tc (λ)]

  Here, Tp (λ) is the transmittance (%) of the polarizing film measured in the relationship between the linearly polarized light having the incident wavelength λnm and the parallel Nicol, and Tc (λ) is crossed with the linearly polarized light having the incident wavelength λnm. It is the transmittance | permeability (%) of the polarizing film measured by the relationship of Nicol, and is a measured value obtained by the polarized ultraviolet visible absorption spectrum measurement by a spectrophotometer. In addition, the single transmittance (λ) and polarization degree (λ) obtained for each wavelength are subjected to sensitivity correction called visibility correction, and the visibility correction single transmittance (Ty) and visibility correction polarization degree ( Py). Visibility correction will be described in detail later. Ty and Py can be easily measured with, for example, a spectrophotometer (model number: V7100) manufactured by JASCO Corporation.

(High brightness polarizing plate)
The polarizing plate of the present invention can be formed into a high-intensity polarizing plate by laminating a brightness enhancement film via an adhesive on the side opposite to the surface on which the first transparent protective film is disposed.

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

  Examples of the brightness enhancement film include anisotropic reflective polarizers. An example of the anisotropic reflective polarizer is an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. An example of the anisotropic multi-thin film is a trade name “DBEF” manufactured by 3M (see, for example, JP-A-4-268505). An example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ / 4 plate. An example of such a composite is a product name “PCF” manufactured by Nitto Denko Corporation (see JP-A-11-231130, etc.). An example of the anisotropic reflective polarizer is a reflective grid polarizer. As a reflective grid polarizer, a metal grid reflective polarizer (see US Pat. No. 6,288,840, etc.) that finely processes metal to produce reflected polarized light even in the visible light region, and metal fine particles in a polymer matrix. And a stretched one (see JP-A-8-184701, etc.).

  You may form a functional layer in the surface on the opposite side to the bonding surface with the polarizing plate of a brightness improvement film. Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusing layer, and a retardation layer having a retardation value of ¼ wavelength, thereby improving adhesion to the backlight tape. And the uniformity of the displayed image can be improved.

  Examples of the adhesive that bonds the polarizing plate and the brightness enhancement film include acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy, and fluorine. Those having a base polymer of a rubber-based polymer such as natural rubber or synthetic rubber can be appropriately selected and used. As the pressure-sensitive adhesive, those having excellent optical transparency, moderate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are particularly preferable.

(Adhesive layer)
The pressure-sensitive adhesive layer is not particularly limited as long as it has excellent optical transparency and exhibits pressure-sensitive adhesive properties such as appropriate wettability, cohesiveness, and adhesiveness, but is preferably excellent in durability and the like. Specific examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer include a pressure-sensitive adhesive made of an acrylic resin (also referred to as an acrylic pressure-sensitive adhesive).

  The pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive is not particularly limited, but (butyl) (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and (meth) acrylic acid (Meth) acrylic ester resins such as 2-ethylhexyl and copolymer resins using two or more of these (meth) acrylic esters are preferably used. These resins are copolymerized with polar monomers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Examples thereof include monomers having a polar functional group such as carboxyl group, hydroxyl group, amide group, amino group, and epoxy group, such as acrylate and glycidyl (meth) acrylate. Moreover, a crosslinking agent is normally mix | blended with the adhesive with acrylic resin.

  Various other additives may be blended in the adhesive. Suitable additives include silane coupling agents and antistatic agents. A silane coupling agent is effective in increasing the adhesive strength with glass. Antistatic agents are effective in reducing or preventing the generation of static electricity. That is, when sticking the polarizing plate to the liquid crystal cell through the pressure-sensitive adhesive layer, the surface protective film (separator) that has been temporarily protected by covering the pressure-sensitive adhesive layer is peeled off and then attached to the liquid crystal cell. The static electricity generated when the surface protective film is peeled off causes alignment failure in the liquid crystal in the cell, which may cause display failure of the IPS mode liquid crystal display device. In order to reduce or prevent the generation of such static electricity, the addition of an antistatic agent is effective.

  The thickness of the pressure-sensitive adhesive is preferably 3 to 50 μm. More preferably, it is 3-30 micrometers.

  The storage elastic modulus of the pressure-sensitive adhesive is not particularly limited. For example, when it is desired to suppress warping of the liquid crystal panel in a high-temperature test or a high-temperature and high-humidity test, the storage elastic modulus of the pressure-sensitive adhesive at 23 ° C. is as follows. Those of 0 MPa or less are preferably used. More preferably, it is 0.8 MPa or less, and further preferably 0.5 MPa or less.

  The pressure-sensitive adhesive may or may not contain an acid. Even when an acid is included, it is preferable that the amount of acid is small. Specifically, the amount of acid component in all monomer components is preferably less than 1.0% by weight based on the amount of all monomer components.

In the case where the adhesive layer is made conductive, the resistance value may be appropriately selected. For example, 1 × 10 ⁹ to 1 × 10 ¹¹ so as not to hinder the operation of a touch panel such as a smartphone.
A range of Ω / □ is preferred.

  (Polarizing plate with pressure-sensitive adhesive) The polarizing plate of the present invention can be a polarizing plate with pressure-sensitive adhesive by providing a pressure-sensitive adhesive layer on at least one surface. As this pressure-sensitive adhesive layer, the same pressure-sensitive adhesive as described above can be used.

(High-intensity polarizing plate with adhesive)
The high-intensity polarizing plate of the present invention can be a polarizing plate with an adhesive by providing an adhesive layer on at least one surface. This pressure-sensitive adhesive can be provided on the transparent protective film disposed on the liquid crystal cell side. As the adhesive layer, the same adhesive as described above can be used.

(Use)
The polarizing plate and the high-intensity polarizing plate of the present invention are suitable as components for liquid crystal panels and liquid crystal display devices, but are particularly small and medium-sized such as cellular phones and portable information terminals using thin glass of 0.7 mm or less. It is suitable for liquid crystal display device applications. The size of the polarizing plate and the high-intensity polarizing plate of the present invention is, for example, preferably 55 mm × 41 mm or more, more preferably 154 mm × 87 mm or more, preferably 233 mm × 310 mm or less, more preferably 229 mm × 305 mm or less, More preferably, it is 174 mm × 231 mm.

(Liquid crystal display device)
A polarizing plate and a high-intensity polarizing plate are bonded to an IPS mode liquid crystal cell via an adhesive layer to constitute a liquid crystal panel, and are used in a liquid crystal display device. The same type of polarizing plate or a known polarizing plate can be bonded to the back side of the liquid crystal panel on which the polarizing plate of the present invention is bonded. In particular, the polarizing plate provided with the transparent protective film imparted with the antiglare property is preferably bonded to the viewing side of the liquid crystal panel.

  When configuring a liquid crystal display device, a polarizing plate provided with a cellulose resin film, a polyethylene terephthalate resin film, or a methyl methacrylate resin film imparted with antiglare and light resistance is pasted on the viewing side of the liquid crystal panel. It is preferable to combine them. In addition, a polarizing plate provided with a cellulose resin film, a polyethylene terephthalate resin film, a methyl methacrylate resin film, or a polypropylene resin film is preferably bonded to the back side of the liquid crystal panel. When using a polyethylene terephthalate-based resin film, a methyl methacrylate-based resin film and a polypropylene-based resin film, the water vapor transmission rate and the water absorption rate are small compared to a triacetyl cellulose film which is usually used for a protective film of a polarizing plate, Accordingly, since the dimensional change is small, there is an effect that the durability of the polarizing plate is improved and the deterioration of the display quality due to the environmental change of the display device using the polarizing plate is suppressed. Furthermore, by containing an ultraviolet absorber, an effect of further improving the durability of the polarizing plate using the ultraviolet absorbent as compared with that using a triacetyl cellulose film is exhibited.

  There is no restriction | limiting in the combination of the polarizing plate bonded on the visual recognition side and back side of a liquid crystal panel, and arbitrary combinations can be selected. As an example, a polarizing plate provided with a polyethylene terephthalate-based resin film imparted with antiglare and light resistance on the viewing side of the liquid crystal panel, and a polarizing plate provided with a polypropylene-based resin film on the back side were bonded. A configuration is mentioned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not prescribed | regulated by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The evaluation methods used in the examples are as follows.

(1) Thickness:
Measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) In-plane retardation Re and thickness direction retardation Rth:
It measured with the light of wavelength 590nm, 483nm, or 755nm in 23 degreeC using the phase difference meter based on a parallel Nicol rotation method, and KOBRA-ADH by Oji Scientific Instruments.

(3) Dimensional change rate of polarizing plate The polarizing plate is cut into 100 squares of 100 mm in the absorption axis direction and 100 mm in the transmission axis direction and left in an environment of 85 ° C. for 100 hours. The dimensions of the polarizing plate were measured using a two-dimensional measuring instrument “NEXIV VMR-12072” manufactured by Nikon Corporation. The dimensional change rate of the polarizing plate is calculated by the following equation, where ΔL is the dimensional change obtained 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. The
Dimensional change rate of polarizing plate = ΔL / L ₀

(4) Storage elastic modulus:
The storage elastic modulus (G ′) of the pressure-sensitive adhesive layer was measured according to the following (I) to (III).
(I) Two samples of 25 ± 1 mg are taken out from the pressure-sensitive adhesive layer, and each is formed into a substantially ball shape.
(II) The obtained substantially ball-shaped sample is attached to the upper and lower surfaces of the I-shaped jig, and the upper and lower surfaces are sandwiched between the L-shaped jig. The configuration of the measurement sample is L-shaped jig / adhesive / I-shaped jig / adhesive / L-shaped jig.
(III) The storage elastic modulus (G ′) of the thus prepared sample was measured using a dynamic viscoelasticity measuring device [DVA-220, manufactured by IT Measurement Control Co., Ltd.] at a temperature of 23 ° C., a frequency of 1 Hz, and an initial value. The measurement was performed under the condition of strain 1N.

(5) Adhesion to glass:
The polarizing plate provided with the pressure-sensitive adhesive layer is cut to a width of 25 mm, bonded to a glass plate on the pressure-sensitive adhesive layer side, subjected to a pressure treatment for 20 minutes under the conditions of a temperature of 50 ° C. and a pressure of 5 atm. After leaving at 23 ° C. for 1 day, using AZ1 manufactured by Shimadzu Corporation, in accordance with JIS Z 0237, when peeled off in the 180 ° direction with respect to the length direction of the cut polarizing plate Stress was measured.

(6) Elastic modulus (measured in accordance with JIS K 7161)
The test piece was cut into a width of 15 mm, the test piece was pulled at a rate of 50 mm / min using AZ1 manufactured by Shimadzu Corporation, and the elastic modulus was obtained from the strain stress curve.

(7) Moisture permeability (measured according to JIS Z 0208)
The cross-sectional area was determined as 27 cm ² according to JIS Z 0208. This standard stipulates that the moisture permeability is measured at either 25 ° C. or 40 ° C., but in this specification, a temperature of 40 ° C. is adopted.

(Production Example 1) Production of Polarizing Film (Production of 7 μm Thick Polarizing Film A)
A 20 μm-thick polyvinyl alcohol film (average polymerization degree of about 2,400, saponification degree of 99.9 mol% or more) was uniaxially stretched about 5 times by dry stretching and further kept at 60 ° C. After being immersed in pure water for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a 7 μm thick polarizer in which iodine was adsorbed and oriented on the polyvinyl alcohol film.

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

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

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

(Production Example 2) Preparation of water-soluble adhesive 3 parts of carboxyl group-modified polyvinyl alcohol [KL-318 manufactured by Kuraray Co., Ltd.] is dissolved in 100 parts of water, and the aqueous solution is a water-soluble epoxy compound. 1.5 parts of polyamide epoxy additive [Sumirez resin 650 (30) manufactured by Sumika Chemtex Co., Ltd., aqueous solution with a solid content concentration of 30%] was added to obtain a water-soluble adhesive.

(Production Example 3) Preparation of pressure-sensitive adhesive A pressure-sensitive adhesive layer having a thickness of 20 µm was formed from a commercially available acrylic pressure-sensitive adhesive. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.42 MPa at 23 ° C. Moreover, the adhesive force with respect to glass when this adhesive layer was bonded to the polarizing plate mentioned later and bonded to glass was 5 N / 25mm.

[Example 1] (Reference)
A second transparent protective film made of triacetylcellulose (KC2UA manufactured by Konica Minolta Co., Ltd., thickness 25 μm) is formed on one surface of a polarizing film A (thickness 7 μm) in which iodine is adsorbed and oriented on a polyvinyl alcohol film. Is attached to the other surface (the surface on the liquid crystal cell side) of the first transparent protective film made of cycloolefin polymer [trade name “ZF14” manufactured by Nippon Zeon Co., Ltd. 3.3 times, thickness 23 μm, in-plane retardation at wavelength 590 nm (Re (590)) = 2.1 nm, thickness direction retardation at wavelength 590 nm (Rth (590)) = 2.8 nm, wavelength 483 nm Thickness direction retardation (Rth (483)) = 2.5 nm, thickness direction retardation (Rth (755)) =-4.2 nm at a wavelength of 755 nm, elastic modulus = 231 5 MPa, moisture permeability = 17 g / m ² · 24 hr] was bonded to prepare a polarizing plate. The film-to-film adhesion is performed by applying the previously prepared water-soluble adhesive on the first protective film or the second protective film, respectively, and laminating on the polarizing film via the adhesive, and then at 80 ° C. for 5 minutes. Dried by drying. After the obtained polarizing plate was cured at 40 ° C. for 168 hours, the dimensional change rate was measured and found to be 0.92%.

  An acrylic pressure-sensitive adhesive was applied on the separator to form a pressure-sensitive adhesive layer, which was laminated on the first transparent protective film side to produce a member in which the separator was laminated on the pressure-sensitive adhesive layer of the polarizing plate with the pressure-sensitive adhesive.

  Disassemble the IPS mode liquid crystal display device [Sony Ericsson Mobile Communications mobile phone (model number: W62S)], peel off and remove the polarizing plates on both sides of the liquid crystal cell, and instead use the adhesive of Example 1 Two polarizing plates were bonded to the front side (viewing side) and back side (light incident side) of the liquid crystal cell on the pressure-sensitive adhesive layer side from which each separator was peeled off so as to be in a crossed Nicols state. In this case, the absorption axis of the polarizing plate on the front side (viewing side) was arranged so as to be parallel to the alignment direction when no voltage was applied to the liquid crystal molecules in the liquid crystal cell (black display). This IPS mode liquid crystal display device was assembled and turned on again, and the color shift in the black display state in which no voltage was applied to the liquid crystal cell was measured with an ELDIM liquid crystal viewing angle / chromaticity characteristic measuring device EZ contrast. Δu′v ′ was 0.15.

[Example 2] (Reference)
Polarizing film A (7 μm thick) with iodine adsorbed and oriented on a polyvinyl alcohol film
m) A transparent protective film made of triacetylcellulose [KC2UA manufactured by Konica Minolta Co., Ltd., thickness 25 μm] is bonded to one surface of m), and the other surface (surface on the liquid crystal cell side).
Transparent protective film made of cycloolefin polymer [trade name “ZF14-013” obtained from Nippon Zeon Co., Ltd., thickness 13 μm, 1.9 times the thickness of polarizing film, in-plane retardation at wavelength 590 nm] (Re (590)) = 0.8 nm, thickness direction retardation at a wavelength of 590 nm (Rth (590)) = 3.4 nm, thickness direction retardation at a wavelength of 483 nm (Rth (483)) = 3.5 nm, wavelength Thickness direction retardation at 755 nm (Rth (755)) = 2.8 nm, elastic modulus = 2225 MPa, moisture permeability = 35 g / m ² .24
hr] was bonded to prepare a polarizing plate. The film-to-film adhesion is performed by applying the previously prepared water-soluble adhesive on the first protective film or the second protective film, respectively, and laminating on the polarizing film via the adhesive, and then at 80 ° C. for 5 minutes. Dried by drying. After the obtained polarizing plate was cured at 40 ° C. for 168 hours, the dimensional change rate was measured and found to be 1.21%.

  An acrylic pressure-sensitive adhesive was applied on the separator to form a pressure-sensitive adhesive layer, which was laminated on the first transparent protective film side to produce a member in which the separator was laminated on the pressure-sensitive adhesive layer of the polarizing plate with the pressure-sensitive adhesive. This 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. The color shift Δu′v ′ was 0.15.

[Example 3] (Reference)
A polarizing plate was produced in the same manner except that the polarizing film A having a thickness of 7 μm in Example 1 was changed to the polarizing film B having a thickness of 12 μm. When the dimensional change rate of this polarizing plate was measured, it was 1.00%.

  An acrylic pressure-sensitive adhesive was applied on the separator to form a pressure-sensitive adhesive layer, which was laminated on the first transparent protective film side to produce a member in which the separator was laminated on the pressure-sensitive adhesive layer of the polarizing plate with the pressure-sensitive adhesive. . This 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. The color shift Δu′v ′ was 0.15.

[Example 4]
The brightness enhancement film A was bonded to the transparent protective film side made of triacetyl cellulose of the polarizing plate in Example 1 via an adhesive to produce a high brightness polarizing plate. It was 0.78% when the dimensional change rate of this high-intensity polarizing plate was measured.

  An acrylic pressure-sensitive adhesive is applied on the separator to form a pressure-sensitive adhesive layer, which is laminated on the first transparent protective film side to produce a member in which the separator is stacked on the pressure-sensitive adhesive layer of the high-intensity polarizing plate with pressure-sensitive adhesive did.

  Disassemble the IPS mode liquid crystal display device [Sony Ericsson Mobile Communications mobile phone (model number: W62S)], peel off and remove the polarizing plates on both sides of the liquid crystal cell, and replace the polarizing plate of Example 1 instead. At the front side (viewing side) of the liquid crystal cell, the high-intensity polarizing plate produced in Example 4 is pasted on the adhesive layer side where each separator is peeled off so that the back side (light incident side) is in a crossed Nicols state. Combined. In this case, the absorption axis of the polarizing plate on the front side (viewing side) was arranged so as to be parallel to the alignment direction when no voltage was applied to the liquid crystal molecules in the liquid crystal cell (black display). This IPS mode liquid crystal display device was assembled and turned on again, and the color shift in the black display state in which no voltage was applied to the liquid crystal cell was measured with an ELDIM liquid crystal viewing angle / chromaticity characteristic measuring device EZ contrast. Δu′v ′ was 0.14.

[Example 5] (Comparison)
The brightness enhancement film A was bonded to the second transparent protective film side made of triacetyl cellulose of the polarizing plate in Example 2 via an adhesive to produce a high brightness polarizing plate. It was 1.04% when the dimensional change rate of this high-intensity polarizing plate was measured.

  An acrylic pressure-sensitive adhesive is applied on the separator to form a pressure-sensitive adhesive layer, which is laminated on the first transparent protective film side to produce a member in which the separator is stacked on the pressure-sensitive adhesive layer of the high-intensity polarizing plate with pressure-sensitive adhesive did.

  As in Example 4, the polarizing plate of Example 1 is in a crossed Nicols state on the front side (viewing side) of the liquid crystal cell and the high-intensity polarizing plate produced in Example 5 is on the back side (light incident side). When the color shift was measured after bonding, the color shift Δu′v ′ was 0.14.

[Example 6]
The brightness enhancement film A was bonded to the second transparent protective film side made of triacetyl cellulose of the polarizing plate in Example 3 via an adhesive to produce a high brightness polarizing plate. It was 0.88% when the dimensional change rate of this high-intensity polarizing plate was measured.

  An acrylic pressure-sensitive adhesive is applied on the separator to form a pressure-sensitive adhesive layer, which is laminated on the first transparent protective film side to produce a member in which the separator is stacked on the pressure-sensitive adhesive layer of the high-intensity polarizing plate with pressure-sensitive adhesive did.

  As in Example 4, the polarizing plate of Example 1 is in a crossed Nicols state on the front side (viewing side) of the liquid crystal cell and the high-intensity polarizing plate produced in Example 6 is on the back side (light incident side). When the color shift was measured after bonding, the color shift Δu′v ′ was 0.14.

[Comparative Example 1]
A polarizing plate was prepared in the same manner except that the polarizing film A having a thickness of 7 μm in Example 1 was changed to the polarizing film C having a thickness of 23 μm. When the dimensional change rate of this polarizing plate was measured, it was 1.55%.

  The acrylic adhesive prepared on the previous separator was bonded to the first transparent protective film side made of cycloolefin polymer of this polarizing plate to produce a polarizing plate with an adhesive. This 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. The color shift Δu′v ′ was 0.15.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The polarizing plate of the present invention is suitable for a small and medium-sized liquid crystal display device having a small screen such as a mobile phone or a personal digital assistant, in which a dimensional change occurring in the absorption axis direction is suppressed.

Claims (8)

The first transparent protective film, the polarizing film, and the second transparent protective film are laminated in this order, and are polarizing plates for an IPS mode liquid crystal display device,
The thickness of the polarizing film is 12 μm or less,
The first transparent protective film is
In-plane retardation Re (590) at a wavelength of 590 nm is 10 nm or less,
The absolute value of retardation Rth (590) in the thickness direction at a wavelength of 590 nm is 10 nm or less,
The absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm is 15 nm or less,
The transparent resin film has a thickness that is (23/12) times to 3.3 times the thickness of the polarizing film,
The first transparent protective film and the polarizing film, and the second transparent protective film and the polarizing film are all integrated using an adhesive,
A high-intensity polarizing plate in which a brightness enhancement film is laminated via an adhesive on the opposite side of the polarizing plate on which the first transparent protective film is disposed.   The high-intensity polarizing plate according to claim 1, wherein the first transparent protective film and the polarizing film are bonded with a water-soluble adhesive containing a polyvinyl alcohol-based resin and an epoxy compound.   The high-intensity polarizing plate according to claim 1, wherein the first transparent protective film and the polarizing film are bonded with an adhesive made of a resin composition containing an epoxy resin that is cured by irradiation with active energy rays or heating.   The high-intensity polarizing plate according to claim 3, wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.   The high-intensity polarizing plate according to any one of claims 1 to 4, wherein the second transparent protective film comprises a methyl methacrylate resin film, a polyethylene terephthalate resin film, or a cellulose resin film.   The high-intensity polarizing plate according to any one of claims 1 to 5, wherein the high-intensity polarizing plate is for a mobile phone or a portable information terminal.   An IPS mode liquid crystal display device in which the high-intensity polarizing plate according to claim 1 is disposed on at least one surface of an IPS mode liquid crystal cell.   The IPS mode liquid crystal display device according to claim 7, wherein the IPS mode liquid crystal display device is for a small and medium size.