JP2010107953A - Polarizing plate for ips mode liquid crystal display device and ips mode liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate with excellent adhesion of a polarizing film and a protection film and endurance, capable of restraining color shift without deteriorating characteristics of an IPS mode liquid crystal display device having a wide viewing angle. <P>SOLUTION: The polarizing plate for an IPS mode liquid crystal display device has a transparent protection film disposed on both sides of a polarizing film. The transparent protection film disposed on the liquid crystal cell side when used for a liquid crystal display device includes an olefin based resin film having an in-plane retardation at a 590 nm wavelength Re (590) of 10 nm or less, the absolute value of a thickness direction retardation at a 590 nm wavelength Rth (590) of 10 nm or less, and the absolute value of a thickness direction retardation at a 480-750 nm wavelength Rth (480-750) of 15 nm or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate used by being bonded to an IPS mode liquid crystal cell, 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. Therefore, by improving the number of films or sheets constituting these optical members and reducing the film thickness, it is possible to improve the production efficiency and brightness of the liquid crystal display device and to reduce the weight and thickness. Such research is actively conducted.

  On the other hand, as one of liquid crystal display devices, there is an in-plane switching (IPS) mode liquid crystal display device. In this drive mode, image display is performed by driving a nematic liquid crystal that is homogeneously oriented in the absence of an electric field by a lateral electric field. This IPS mode liquid crystal display device has a feature that the viewing angle is wider than liquid crystal display devices in other drive modes. However, there is a problem that the color change (also referred to as a color shift in an oblique direction) of the image depending on the viewing angle is large.

  In order to solve this problem, an IPS mode liquid crystal display device using a retardation film having a specific retardation as a protective film for a polarizing plate has been disclosed (Patent Document 1). Furthermore, it is also disclosed that a polarizing plate using a transparent film having little optical anisotropy and a small retardation as a protective film is used for an IPS mode liquid crystal display device (Patent Document 2).

  Further, in Patent Document 3, a cellulose acylate film having excellent bonding suitability to polyvinyl alcohol (PVA) is improved by further reducing the optical anisotropy, and the in-plane retardation is almost zero, In addition, a film that is optically isotropic and transparent with little change in retardation angle, that is, substantially zero retardation in the thickness direction is disclosed. However, although the cellulose acylate film is excellent in transparency, surface smoothness, and adhesion, it is inferior in durability because it hydrolyzes under high temperature and high humidity.

  Therefore, for the purpose of improving the durability under high temperature and high humidity, it is also disclosed that a polycarbonate film or a cyclic olefin film is used as a protective film having a small retardation change in place of the cellulose acylate film ( For example, Patent Documents 4 and 5). However, when these films are used as a protective film for a polarizing film, the film is hydrophobic and may have poor adhesion to the polarizing film.

JP-A-10-307291 JP 2006-18245 A JP 2005-154664 A JP-A-8-43812 JP-A-8-240714

  An object of the present invention is a polarizing plate capable of suppressing color shift without impairing the characteristics of an IPS mode liquid crystal display device having a wide viewing angle, and a polarizing plate excellent in adhesiveness and durability between a polarizing film and a protective film. It is to provide. Another object of the present invention is to provide an IPS mode liquid crystal display device using this polarizing plate.

  The inventors of the present invention have excellent adhesion between the polarizing film and the transparent protective film, and durability by setting the retardation of the transparent protective film made of an olefin resin disposed on the liquid crystal cell side to a specific range. The inventors have found that an excellent polarizing plate can be produced, and have reached the present invention.

That is, according to the present invention, a polarizing plate for an IPS mode liquid crystal display device in which a transparent protective film is disposed on both sides of a polarizing film,
When used in a liquid crystal display device, the transparent protective film disposed on the liquid crystal cell side 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,
A polarizing plate comprising an olefin resin film having an absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm of 15 nm or less is provided.

  The transparent protective film and the polarizing film are preferably bonded with a water-soluble adhesive containing a water-soluble polyvinyl alcohol resin. Moreover, it is also preferable that this transparent protective film and polarizing film are adhere | attached with the adhesive agent which consists of an epoxy resin composition containing the epoxy resin hardened | cured by irradiation of an active energy ray or a heating. Further, the epoxy resin preferably contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

  The polarizing plate is formed of an acrylic pressure-sensitive adhesive on the outside of the transparent protective film made of the olefin-based resin film, has a storage elastic modulus at 23 ° C. of 0.15 to 10 MPa, and has an adhesive strength with glass of 1 to 1. An adhesive layer that is 30 N / 25 mm can be provided.

  The transparent protective film disposed on the side opposite to the surface on which the olefin resin film of the polarizing film is disposed is preferably composed of a methyl methacrylate resin film, a polyethylene terephthalate resin film, or a polypropylene resin film, Moreover, it is more preferable that these transparent protective films contain an ultraviolet absorber.

  Furthermore, according to the present invention, there is provided an IPS mode liquid crystal display device in which the polarizing plate is disposed on at least one surface of an IPS mode liquid crystal cell.

  The present invention relates to the problem that an olefin resin film used as a protective film or retardation film for a polarizing plate is usually inferior in adhesive strength with a polarizing film, and the retardation of the olefin resin film is a specific value. As a result, it has succeeded in dramatically increasing the adhesive strength with the polarizing film. The details of this effect are still unclear, but as a possible example, the surface state of an olefin resin film that is generally given a certain degree of retardation and used as a retardation film, and the retardation defined by the present invention It is presumed that due to the difference in the surface state of the olefin-based resin film having an adhesive property, the adhesive force with the adhesive through the adhesion to the polarizing film has changed.

  Furthermore, the present invention provides an IPS mode liquid crystal display device excellent in display quality by determining that the specific retardation range effective for improving the adhesive force is also suitable for the IPS mode liquid crystal cell. Is obtained.

Hereinafter, embodiments of the present invention will be described in detail.
(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 such a 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 is not particularly limited, and can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 10 μm to 150 μm.

  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. Further, 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.

  The thickness of the polarizing film thus obtained can usually be about 5 to 40 μm.

(Transparent protective film placed on the liquid crystal cell side)
The transparent protective film disposed on the liquid crystal cell side in the polarizing plate of the present invention 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,
It is composed of an olefin resin film having an absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm of 15 nm or less.

  The olefin resin film used in the present invention includes, for example, cyclic olefin resins obtained by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives using a polymerization catalyst, and chain olefin monomers such as ethylene and propylene. Can be a film made of a chain olefin resin polymerized 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.

  Such a cyclic olefin-based resin can be easily obtained as a commercial product. For example, under the trade name, Topas (Topas Advanced Polymers GmbH), Arton (manufactured by JSR Corporation), Zeonoa, Zeonex ( As mentioned above, Nippon Zeon Co., Ltd.) and Apel (Mitsui Chemicals Co., Ltd.) etc. are mentioned.

  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.

  Such polypropylene-based 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 Noblen (manufactured by Sumitomo Chemical Co., Ltd.), Sun Allomer (manufactured by Sun Allomer Co., Ltd.), and the like.

  The method for producing the transparent protective film from the cyclic olefin-based resin or the chain olefin-based resin is not particularly limited as long as a method corresponding to the resin is 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 transparent protective film is a value obtained by multiplying the in-plane refractive index difference between the thickness direction and 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.
Retardation value in the thickness direction (Rth) = {(n _x + n _y ) / 2−n _z } × d (1)
Plane retardation value _{(Re) = (n x -n} y) × d (2)
(Wherein, n _x is a refractive index in the x direction in the film plane (in-plane slow axis direction), n _y is a refractive index in the y-direction in the film plane (in-plane fast axis direction), _nz is the refractive index in the direction perpendicular to the film surface (thickness direction), and d is the thickness of the film).

  As described above, in the present invention, when the polarizing plate is applied to a liquid crystal display device, the transparent protective film on the liquid crystal cell side has a small in-plane and thickness direction retardation, that is, an almost non-oriented olefin resin. Consists of film. Although the absolute value of retardation Rth (480-750) in the thickness direction at wavelengths of 480 to 750 nm is 15 nm or less, 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 olefin resin film to satisfy the above conditions will be described. In order to reduce Re (590) to 10 nm or less, it is necessary to minimize distortion at the time of stretching remaining in the in-plane direction, and Rth (590) and Rth (480-750) are set to 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.

(Transparent protective film placed on the opposite side of the liquid crystal cell side)
In the polarizing plate used in the present invention, the transparent film is disposed on the side opposite to the liquid crystal cell side with respect to the polarizing film, that is, on the side opposite to the surface on which the olefin resin film having the specific retardation characteristics described above is disposed. The protective film is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. Such a material for 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.

  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, it is preferable to use a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, or a cellulose resin as the material of the transparent protective film disposed on the side opposite to the liquid crystal cell side.

  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 having such a composition, 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.

  Such methyl methacrylate resins can be easily obtained as commercial products. For example, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acripet (manufactured by Mitsubishi Rayon Co., Ltd.), Dell Examples include pets (manufactured by Asahi Kasei Corporation), parapets (manufactured by Kuraray Co., Ltd.), and acrylic viewers (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 transparent protective film may be impaired.

  Among propylene homopolymers, those having a component soluble in xylene at 20 ° C. (CXS (cold xylene soluble) component) 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.

  A method of making a methyl methacrylate resin, a polyethylene terephthalate resin, a polypropylene resin, and a cellulose resin as a transparent protective film for adhering to a polarizing film may be selected as appropriate according to each resin, It is not particularly limited. 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 a transparent protective film placed on the opposite side of the liquid crystal cell side can be easily obtained as a commercial product. For methyl methacrylate resin films, Sumipex (Sumitomo Chemical Co., Ltd.) Company-made), acrylite, acrylene (above, manufactured by Mitsubishi Rayon Co., Ltd.), Delagras (made by Asahi Kasei Co., Ltd.), paragrass, comograss (above, made by Kuraray Co., Ltd.), and acrylic viewer (made by Nippon Shokubai Co., Ltd.) It is done. 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.) In the case of cellulosic resin films, Fujitac TD (manufactured by Fuji Film Co., Ltd.), Konica Minolta TAC film KC (manufactured by Konica Minolta Opto Co., Ltd.) and the like are listed under the trade names.

  The transparent protective film used in the present invention (transparent protective film disposed on the liquid crystal cell side and the opposite side thereof, in particular the transparent protective film disposed on the opposite side of the liquid crystal cell side and serving as the visual recognition side) is antiglare (haze). ) Can be given. 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 inorganic fine particles for imparting antiglare properties are not particularly limited. For example, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, carbonic acid. Examples include calcium and calcium phosphate. Further, the organic fine particles are not particularly limited. For example, crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, and Examples include polyimide particles.

  It is preferable that the haze value of the transparent protective film provided with the antiglare property thus obtained is in the range of 6 to 45%. When the haze value of the antiglare protective film is less than 6%, a sufficient antiglare effect may not appear. On the other hand, if it exceeds 45%, the screen of the liquid crystal display device using this film may be whitish and image quality may be deteriorated.

  This haze value can be measured according to JIS K 7136, for example, using a haze / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.). In measuring the haze value, in order to prevent warping of the film, for example, a measurement sample in which the film surface is bonded to a glass substrate using an optically transparent adhesive so that the antiglare property-imparting surface is the surface. Is preferably used.

  On the transparent protective film (transparent protective film disposed on the liquid crystal cell side and the opposite side thereof), 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.

  The transparent protective film disposed on the side opposite to the liquid crystal cell side (the side opposite to the surface on which the olefin resin film having a predetermined retardation property is disposed) may or may not be stretched. From the viewpoint of reducing the thickness and increasing the strength of the protective film, a biaxially stretched film, for example, a biaxially stretched polyethylene terephthalate resin film is preferable, and suppresses coloring of the display screen without giving a phase difference to the film. From the viewpoint, an unstretched methyl methacrylate resin film or a polypropylene resin film is preferable.

  Moreover, the 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. In particular, the transparent protective film used on the outside of the viewing side polarizing plate preferably contains an ultraviolet absorber as a light-resistant agent. Examples of the ultraviolet absorber include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (5 -Methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di -Tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-amyl-2-hydroxypheny ) Benzotriazole ultraviolet absorbers such as -2H-benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) -2H-benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2- Hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, Examples include 2-hydroxybenzophenone ultraviolet absorbers such as 4'-dimethoxybenzophenone; salicylic acid phenyl ester ultraviolet absorbers such as p-tert-butylphenyl salicylic acid ester and p-octylphenyl salicylic acid ester. It may be used two or more thereof Te. The content of the ultraviolet absorber is usually 0.1% by weight or more and preferably 0.3% by weight or more and 2% by weight or less of the resin film.

  An easy-adhesion layer may be provided on the transparent protective film disposed on the opposite side of the liquid crystal cell side. The method for forming the transparent protective film provided with the easy adhesion layer is not particularly limited. For example, in the case of a polyethylene terephthalate resin, the easy adhesion layer is formed on the film after all the stretching steps have been completed. A method of forming an easy-adhesion layer during the process of stretching the film, that is, between the longitudinal stretching and the transverse stretching process, and a method of forming an easy-adhesion layer immediately before or after being bonded to the polarizing film Etc. are adopted. Among these, from the viewpoint of productivity, a method in which an easy-adhesion layer is formed after longitudinal stretching of a polyethylene terephthalate resin film and then lateral stretching is preferably employed.

  In addition, the transparent protective film (transparent protective film disposed on the liquid crystal cell side and the opposite side thereof) may be subjected to saponification treatment, corona treatment, plasma treatment, etc. prior to bonding with the polarizing film. preferable.

  The thickness of the transparent protective film (transparent protective film disposed on the liquid crystal cell side and the opposite side thereof) is not particularly limited, but is usually about 1 to 500 μm from the viewpoint of strength, handleability and the like. -200 micrometers is preferable and 20-100 micrometers is further more preferable. When the thickness is within this range, the polarizing film is mechanically protected, and even when exposed to high temperature and high humidity, the polarizing film does not shrink and stable optical characteristics can be maintained.

(Lamination method of transparent protective film and polarizing film)
Arbitrary appropriate methods are employ | adopted for lamination | stacking of a transparent protective film (The liquid crystal cell side and the transparent protective film arrange | positioned on the opposite side) and a polarizing film.

  As the lamination method, for example, an adhesive layer is preferably integrated. At this time, the thickness of the adhesive layer is preferably 0.1 to 35 μm, and more preferably 0.5 to 15 μm. If it is this range, neither the floating nor peeling arises between the transparent protective film and polarizing film which are laminated | stacked, and the adhesive force which does not have a practical problem is obtained.

  For the formation of the adhesive layer, an appropriate adhesive can be appropriately used according to the type and purpose of the adherend. For example, there are a solvent-type adhesive, an emulsion-type adhesive, a pressure-sensitive adhesive, a rehumidifying adhesive, a polycondensation-type adhesive, a solventless-type adhesive, a film-like adhesive, and a hot-melt-type adhesive. Moreover, an adhesive layer can also be provided through an anchor coat layer as necessary.

  As the adhesive for forming the adhesive layer, 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.

  Moreover, this 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 such an epoxy-based adhesive, the adhesive between the polarizing film and the transparent protective film is irradiated with active energy rays or heated on the adhesive coating layer interposed between these films, This is performed by curing a 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 the aromatic iodonium salt 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.

(Adhesive layer)
On the transparent protective film which consists of an olefin resin film arrange | positioned at the liquid crystal cell side of the polarizing plate of this invention, an adhesive layer can be provided further.

  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 those having excellent durability and the like are preferably used. 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 the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 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.

  The pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive used in the present invention preferably has a storage elastic modulus at 23 ° C. of 0.15 to 10 MPa and a glass adhesive strength of 1 to 30 N / 25 mm. Is preferred.

  Here, the storage elastic modulus (dynamic elastic modulus) is a commonly used term for viscoelasticity measurement, and gives a strain or stress that changes (vibrates) over time to a sample. This is a value obtained by measuring the mechanical properties of the sample by measuring the stress or strain generated by (dynamic viscoelasticity measurement), and the phase of the strain is 90 degrees out of phase with the stress component. The elastic modulus is calculated from the strain having the same phase as the stress.

  By using a pressure-sensitive adhesive layer having a storage elastic modulus in the above range, in a durability test (heat shock resistance test) in which a high temperature environment and a low temperature environment are repeated, a dimensional change accompanying the contraction of the polarizer that occurs at that time Can be reduced. The storage elastic modulus generally decreases with increasing temperature, but it is more preferable to exhibit a high storage elastic modulus of 0.15 MPa or higher even at a high temperature of about 80 ° C., for example.

  Further, the adhesion to glass is a value measured after the polarizing plate provided with the pressure-sensitive adhesive layer is bonded to glass on the pressure-sensitive adhesive layer side and left at room temperature (23 ° C.) for 24 hours. When the adhesion to glass is within the above range, the polarizing plate can be easily peeled off when an operation for re-attaching the polarizing plate to the liquid crystal cell is required. Considering such peelability (also referred to as reworkability) from the liquid crystal cell, it is more preferable that the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer is in the range of 1 to 10 N / 25 mm. By using such a pressure-sensitive adhesive, it is possible to suppress a phenomenon in which bubbles or the like are generated between the liquid crystal cell and the polarizing plate (liquid crystal cell side transparent protective film).

  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 polarizing plate thus obtained is bonded to an IPS mode liquid crystal cell via an adhesive layer to constitute a liquid crystal panel, and is used for 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, it is preferable to paste a polarizing plate provided with a polyethylene terephthalate resin film or a methyl methacrylate resin film imparted with antiglare and light resistance on the viewing side of the liquid crystal panel. . In addition, a polarizing plate provided with 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. Polyethylene terephthalate-based resin film, methyl methacrylate-based resin film and polypropylene-based resin film have smaller water vapor transmission rate and water absorption rate than the triacetyl cellulose film normally used for the protective film of polarizing plate. Since the change is small, there is an effect that durability of the polarizing plate is improved and display quality deterioration due to an environmental change of a display device using the polarizing plate is suppressed. Furthermore, by containing an ultraviolet absorber, the effect that the durability of the polarizing plate using it is improved 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:
Using a phase difference meter based on the parallel Nicol rotation method and KOBRA-21ADH manufactured by Oji Scientific Instruments Co., Ltd., measurement was performed with light of a wavelength of 590 nm, 483 nm, or 755 nm at 23 ° C.

(3) 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 sample thus prepared was measured using a dynamic viscoelasticity measuring device [DVA-220, manufactured by IT Measurement Control Co., Ltd.], temperature 23 ° C., frequency 1 Hz, initial The measurement was performed under the condition of strain 1N.

(4) 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.

(5) Xylene soluble content of polypropylene resin film at 20 ° C .:
After adding 5 g of polypropylene resin film to 500 ml of boiling xylene and completely dissolving it, the temperature was lowered to 20 ° C. and kept at that temperature for 4 hours. Next, the xylene solution was filtered to separate a precipitate and a filtrate. The solvent was removed from the filtrate, and the dried xylene-dissolved component was obtained by drying under reduced pressure at 70 ° C., and its weight was measured. The xylene soluble content (CXS) was determined from the following equation.
CXS [%] = (Weight of dried xylene-dissolved component [g] / 5 [g]) × 100.

[Example 1]
(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 a polyamide-epoxy additive [Sumika Chemtex Co., Ltd.] which is a water-soluble epoxy compound is dissolved in the aqueous solution. 1.5 parts of an aqueous solution having a solid content concentration of 30%] was added to obtain a water-soluble adhesive.

(Preparation of adhesive layer)
A release treatment surface of a polyethylene terephthalate film (separator) having a thickness of 38 μm obtained by releasing an organic solvent solution in which a copolymer of butyl acrylate and acrylic acid is mixed with a urethane acrylate oligomer and an isocyanate crosslinking agent. Then, it was coated with a die coater so that the thickness after drying was 25 μm and dried to obtain an acrylic pressure-sensitive adhesive. The storage elastic modulus of this pressure-sensitive adhesive layer was 1.4 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.

(Preparation of polarizing plate)
A transparent protective film [KC4UX2, manufactured by Konica Minolta Opto Co., Ltd., thickness 40 μm] made of triacetyl cellulose is bonded to one side of a polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film, and the other side A transparent protective film made of a cycloolefin polymer (obtained from Nippon Zeon Co., Ltd., in-plane retardation (Re (590)) at a wavelength of 590 nm (Re (590)) = 2. Thickness direction retardation (Rth (590)) = 2.8 nm, wavelength direction 483 nm (Rth (483)) = 2.5 nm, thickness direction retardation (Rth) at wavelength 755 nm. (755)) = − 4.2 nm] was bonded to produce a polarizing plate of the present invention. For the pasting, the polarizing film and the transparent protective film were bonded together by using the previously prepared water-soluble adhesive and drying at 80 ° C. for 5 minutes after the pasting. The obtained polarizing plate was then cured at 40 ° C. for 168 hours. Furthermore, the acrylic adhesive prepared on the previous separator was bonded to the transparent protective film side of the cycloolefin polymer of this polarizing plate to prepare a polarizing plate with an adhesive.

(Manufacture of IPS mode liquid crystal display devices)
Disassemble the IPS mode wide 32 type liquid crystal display device [Wooo manufactured by Hitachi, Ltd. (model number: W32L-H9000)] and peel off the upper and lower polarizing plates. Two prepared polarizing plates with pressure-sensitive adhesive 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 the respective separators were 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). When this IPS mode liquid crystal display device is assembled and turned on again, and the color shift in the black display state in which no voltage is applied to the liquid crystal cell is measured with an ELDIM liquid crystal viewing angle / chromaticity characteristic measuring device EZ contrast, the color shift is determined. Δu′v ′ was 0.15.

[Example 2]
(Preparation of epoxy curable adhesive)
100 parts of bis (3,4-epoxycyclohexylmethyl) adipate, 25 parts of diglycidyl ether of hydrogenated bisphenol A, and 4,4′-bis (diphenylsulfonio) diphenyl sulfide bis (hexafluorophosphate as a photocationic polymerization initiator ) 2.2 parts were mixed and then defoamed to prepare an adhesive made of a curable epoxy resin composition. In addition, the photocationic polymerization initiator was blended as a 50% propylene carbonate solution and used as an adhesive as it was.

(Preparation of polarizing plate)
A transparent protective film made of the same triacetyl cellulose as used in Example 1 is bonded to one surface of a polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film, and the other surface (liquid crystal cell side and A transparent protective film made of the same cycloolefin polymer as used in Example 1 was pasted to prepare a polarizing plate of the present invention. For the bonding in this example, the adhesive made of the curable epoxy resin composition prepared above was used, and after bonding, an ultraviolet irradiation device with a belt conveyor (lamp: Fusion D lamp, integrated light quantity 1000 mJ / cm ^2). ) Was irradiated with ultraviolet rays to adhere the polarizing film and the transparent protective film. Then, it was left at room temperature for 1 hour. Furthermore, the acrylic adhesive prepared on the same separator as used in Example 1 was bonded to the transparent protective film side made of cycloolefin polymer of this polarizing plate to prepare a polarizing plate with an adhesive.

(Evaluation)
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]
A transparent protective film made of the same cycloolefin polymer as used in the same example is used as the transparent protective film to be bonded to both surfaces of the polarizing film in Example 2, and a polarizing plate is produced in the same manner as in Example 1. And evaluated. As a result, the color shift Δu′v ′ of the IPS mode liquid crystal display device was 0.15.

[Example 4]
(Production of methyl methacrylate resin film)
70 parts of a copolymer having a weight ratio of methyl methacrylate / methyl acrylate of 96/4 and acrylic rubber particles as an acrylic multilayer polymer having a three-layer structure (the first layer serving as the innermost layer is methyl methacrylate / methacrylic acid) Copolymer with an allyl weight ratio of 99.8 / 0.2, the second layer serving as an intermediate layer is a butyl acrylate / styrene / allyl methacrylate copolymer with a weight ratio of 79/19/2, and is the outermost layer A methyl methacrylate-based resin film having a thickness of 80 μm was produced from 30 parts of a mixture (the third layer is made of a copolymer of methyl methacrylate / ethyl acrylate having a weight ratio of 96/4) by melt extrusion.

(Production and evaluation of polarizing plate)
A polarizing plate was prepared and evaluated in the same manner as in Example 2 except that the transparent protective film made of triacetylcellulose in Example 2 was changed to the methyl methacrylate resin film. As a result, the color shift Δu′v ′ of the IPS mode liquid crystal display device was 0.15.

[Example 5]
(Production and evaluation of polarizing plate using polyethylene terephthalate resin film)
A polarizing plate was prepared and evaluated in the same manner as in Example 2 except that the transparent protective film made of triacetylcellulose in Example 2 was changed to a uniaxially stretched polyethylene terephthalate film (thickness: 40 μm). As a result, the color shift Δu′v ′ of the IPS mode liquid crystal display device was 0.15.

[Example 6]
(Production of polypropylene resin film)
A propylene homopolymer having a melt flow rate of 8 g / min and having an isotactic stereoregularity was formed by an extruder to produce a polypropylene resin film having a thickness of 50 μm. The polypropylene resin film had a xylene soluble content at 20 ° C. of 0.2%.

(Production and evaluation of polarizing plate)
A polarizing plate was prepared and evaluated in the same manner as in Example 2 except that the transparent protective film made of triacetylcellulose in Example 2 was changed to the polypropylene resin film. As a result, the color shift Δu′v ′ of the IPS mode liquid crystal display device was 0.15.

[Comparative Example 1]
The transparent protective film made of cycloolefin polymer in Example 1 was obtained from another cycloolefin polymer (available from Nippon Zeon Co., Ltd., thickness 70 μm, Re (590) = 55 nm, Rth (590) = 124 nm. , Rth (483) = 12.6 nm, Rth (755) = 126 nm], and a polarizing plate was produced in the same manner as in Example 1.

[Comparative Example 2]
The transparent protective film made of the cycloolefin polymer in Example 2 was used as the transparent protective film made of the same cycloolefin polymer used in Comparative Example 1 above [Re (590) = 55 nm, Rth (590) = 124 nm, Rth (483 ) = 126.6 nm, Rth (755) = 126 nm]. A polarizing plate was produced in the same manner as in Example 2.

(Test example)
The adhesive force between the polarizing film and the transparent protective film made of cycloolefin polymer in the polarizing plates obtained in Examples 1 to 6 and Comparative Examples 1 and 2 is 90 degrees as defined in JIS K 6854-1: 1999. Evaluation was made by a peel test. In the 90-degree peel test, the peel rate was 200 mm / min, and a test piece obtained by cutting a polarizing plate into a size of 25 mm wide × 120 mm long was used. This test piece was fixed to soda glass using a sheet-like pressure-sensitive adhesive ["P-3132" (trade name) manufactured by Lintec Corporation], and an autograph "AG-1" manufactured by Shimadzu Corporation was used. Then, the test was performed by peeling between the transparent protective film made of cycloolefin polymer and the polarizing film. The results are shown in Table 1. “Destruction” in the table means that the adhesive strength was so strong that the polarizing film side was broken by the peel test, and measurement was impossible.

  From Table 1, the adhesive force between the polarizing film and the transparent protective film made of cycloolefin polymer in the polarizing plate of the example is very strong, whereas the adhesive force of the comparative example is weak. I understand.

  In each embodiment, the combination of the polarizing plate disposed on the front side (viewing side) and the polarizing plate disposed on the back side (light incident side) of the liquid crystal cell can be changed. For example, a polarizing plate using a polyethylene terephthalate resin film on the viewing side, a combination using a polypropylene resin film on the light incident side, and a polarizing plate using a polyethylene terephthalate resin film on the viewing side. Further, a combination in which a polarizing plate using a methyl methacrylate resin film is disposed on the light incident side may be used.

  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.

Claims (8)

A polarizing plate for an IPS mode liquid crystal display device in which a transparent protective film is disposed on both sides of a polarizing film,
When used in a liquid crystal display device, the transparent protective film disposed on the liquid crystal cell side 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,
A polarizing plate comprising an olefin resin film having an absolute value of retardation Rth (480-750) in the thickness direction at a wavelength of 480 to 750 nm of 15 nm or less.   The polarizing plate according to claim 1, wherein the transparent protective film and the polarizing film are bonded with a water-soluble adhesive containing a polyvinyl alcohol resin and an epoxy compound.   The polarizing plate according to claim 1, wherein the 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.   The polarizing plate according to claim 3, wherein the epoxy resin contains a compound having at least one epoxy group bonded to an alicyclic ring in the molecule.   It is formed from an acrylic adhesive on the outside of the transparent protective film made of the olefin resin film, has a storage elastic modulus at 23 ° C. of 0.15 to 10 MPa, and an adhesive force with glass of 1 to 30 N / 25 mm. The polarizing plate according to claim 1, further comprising a pressure-sensitive adhesive layer.   The transparent protective film disposed on the side opposite to the surface on which the olefin resin film of the polarizing film is disposed is composed of a methyl methacrylate resin film, a polyethylene terephthalate resin film, or a polypropylene resin film. The polarizing plate according to any one of 5.   The polarizing plate of Claim 6 in which the transparent protective film arrange | positioned on the opposite side to the surface where the said olefin resin film is arrange | positioned contains a ultraviolet absorber.   An IPS mode liquid crystal display device comprising the polarizing plate according to claim 1 disposed on at least one surface of an IPS mode liquid crystal cell.