TW201901204A - Polarizer set and LCD panel - Google Patents

Abstract

An object of the present invention is to provide a set of polarizing plates which is capable of reducing warping of a liquid crystal panel in a high temperature environment. The set of polarizing plates comprises a front side polarizing plate disposed on the viewing side of the liquid crystal cell and a back side polarizing plate disposed on the back side of the liquid crystal cell; when a laminate in which the front side polarizing plate and the back side polarizing plate are bonded to a glass plate such that the absorption axis of the front side polarizing plate and the absorption axis of the rear side polarizing plate are orthogonal is heated at 85 DEG C, 250 hours, and the tensile modulus of elasticity in the polarizing plate transmission axis direction at 85 DEG C and the tensile modulus of elasticity in the polarizing plate absorption axis direction at 85 DEG C are denoted as Et and Ea, respectively, at least one protective film on a side of the polarizing plate where the laminate is warped in a convex form satisfies Ea / Et ≥ 0.95.

Description

   Polarizer set and LCD panel   

The invention relates to a set of polarizing plates and a liquid crystal panel.

The liquid crystal display device is used in various display monitors by utilizing features such as low power consumption, low voltage operation, light weight, and thinness. A liquid crystal panel constituting a liquid crystal display device has a structure in which a pair of polarizing plates are provided on two areas of a liquid crystal cell.

In Japanese Patent Application Laid-Open No. 2013-37115 (Patent Document 1), a method for suppressing warpage of a liquid crystal panel under a high-temperature environment is disclosed by making a polarizing film included in an optical multilayer body on the front side to be disposed in comparison with The polarizing film included in the optical laminated body opposite to the front side has a thickness of 5 μm or more, and the polarizing film and the reflective polarizing film disposed on the optical laminated body opposite to the front side are further laminated. These methods are effective when a liquid crystal cell having a large thickness (for example, 0.5 mm or more and further 0.7 mm or more) and a reflective polarizing film having a large thickness (for example, 50 μm or more) are used. However, in recent years, each member constituting the polarizing plate has become thinner and has lower rigidity, and it is insufficient for a thin liquid crystal cell to suppress warping of a liquid crystal panel under a high temperature environment.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2013-37115

The present invention aims to provide a set of polarizing plates capable of reducing warpage of a liquid crystal panel under a high temperature environment.

[1] The set of polarizing plates includes a front-side polarizing plate arranged on the viewing side of the liquid crystal cell and a back-side polarizing plate arranged on the back side of the liquid crystal cell; wherein the absorption axis of the front-side polarizing plate is When the absorption axis of the back side polarizing plate is perpendicular, the front side polarizing plate and the back side polarizing plate are bonded to a glass plate to form a laminated body. When the laminated body is heated at 85 ° C. for 250 hours, the laminated body is laminated. At least one protective film of the polarizing plate warped into a convex shape side, the tensile elastic modulus of the polarizing plate in the axial direction at 85 ° C and the tensile elastic modulus of the polarizing plate in the absorption axis direction at 85 ° C, respectively When Et and Ea are expressed, Ea / Et ≧ 0.95 (1) is satisfied.

[2] The set of polarizing plates according to [1], wherein the front-side polarizing plate and the back-side polarizing plate each have a polarizer including a polyvinyl alcohol resin film, and the thickness of the polarizer is 15 μm or less .

[3] The set of polarizing plates according to [1] or [2], wherein the difference between the thickness of the polarizer included in the front-side polarizer and the thickness of the polarizer included in the rear-side polarizer is It is 5 μm or less.

[4] A liquid crystal panel including the set of polarizing plates according to any one of [1] to [3], and a liquid crystal cell, wherein the thickness of the liquid crystal cell is 0.4 mm or less.

According to the polarizing plate set of the present invention, warping of a liquid crystal panel under a high temperature environment can be reduced.

2‧‧‧Polarizer

10, 11, 12‧‧‧ protective film

20, 21, 22‧‧‧ Adhesive layer

30, 31, 32‧‧‧ Adhesive layer

40‧‧‧brightening film

70‧‧‧ glass plate

80‧‧‧Measurement point

100, 101, 400‧‧‧ front side polarizer

200, 201, 401‧‧‧ back side polarizer

300‧‧‧ LCD cell

402‧‧‧polarizing plate

Fig. 1 is a sectional view showing an example of a set of polarizing plates of the present invention.

Fig. 2 is a sectional view showing an example of a liquid crystal panel of the present invention.

Fig. 3 is a schematic cross-sectional view of the evaluation sample after heat treatment.

FIG. 4 is a plan view showing a position where the amount of warpage of the evaluation sample is measured.

A set of a polarizing plate and a liquid crystal panel of the present invention will be described with reference to appropriate drawings. The set of polarizing plates of the present invention includes a front-side polarizing plate arranged on the viewing side of the liquid crystal cell and a back-side polarizing plate arranged on the rear side of the liquid crystal cell.

In one embodiment, the polarizing plate of the present invention includes a member shown in FIG. 1. The set of polarizing plates shown in FIG. 1 (a) includes a front-side polarizing plate 100 and a back-side polarizing plate 200. The front-side polarizing plate 100 is laminated on one side of the polarizer 2 with a protective film 10 laminated thereon through an adhesive layer 30, and is laminated on the other side of the polarizer 2 with an adhesive layer 21 laminated on the protective film 11. Further, an adhesive layer 20 is laminated on the protective film 11.

The back side polarizing plate 200 is formed on one side of the polarizer 2 with a protective film 12 laminated thereon through an adhesive layer 32, and on the other side of the polarizer 2 with a brightness enhancement film 40 laminated with an adhesive layer 21. Further, an adhesive layer 20 is laminated on the protective film 12.

The set of polarizing plates shown in FIG. 1 (b) includes a front-side polarizing plate 101 and a back-side polarizing plate 201. The front-side polarizing plate 101 is attached to one side of the polarizer 2 and a protective film 10 is laminated via an adhesive layer 30, and the other side of the polarizer 2 is laminated to a protective film 11 via an adhesive layer 31. Further, an adhesive layer 20 is laminated on the protective film 11.

The back-side polarizing plate 201 is attached to one side of the polarizer 2 and a protective film 12 is laminated with an adhesive layer 31 therebetween, and a brightening film 40 is laminated with an adhesive layer 22 on the protective film 12. Further, an adhesive layer 20 is layered on another area of the polarizer 2.

In the polarizing plate set shown in FIG. 1, the adhesive layer 20 may be, for example, an adhesive layer for laminating liquid crystal cells on the polarizing plate.

In the set of polarizing plates of the present invention, the shapes of the front-side polarizing plate and the back-side polarizing plate are not particularly limited, and may be rectangular. When the shape of the polarizing plate is a rectangle having long sides and short sides, the absorption axis of the front-side polarizing plate is preferably parallel to the short side, and the absorption axis of the back-side polarizing plate is preferably parallel to the long side.

In the set of polarizing plates of the present invention, when the laminated body including the front-side polarizing plate and the back-side polarizing plate is heated, the protective film of the polarizing plate warped to a convex shape side, the polarizing plate at 85 ° C. When the tensile elastic modulus in the transmission axis direction and the tensile elastic modulus in the absorption axis direction of the polarizing plate at 85 ° C. are expressed as Et and Ea, respectively, the following formula (1) is satisfied. The tensile elastic modulus can be measured by a method described in Examples described later.

Ea / Et ≧ 0.95 (1)

Ea / Et is more preferably 1.05 or more, and still more preferably 1.10 or more. Ea / Et may be 2.5 or less.

When the edge of the laminate is warped to the front-side polarizer, the polarizer warped to the convex side is the back-side polarizer. When the edge of the laminate is warped to the back-side polarizer, the warp becomes The polarizing plate on the convex side is a front-side polarizing plate. Specifically, it will be described with reference to FIG. 3. FIG. 3 is a cross-section of a laminated body in which a front-side polarizing plate 400 and a back-side polarizing plate 401 are bonded to a glass plate 70, respectively, and the laminated body is heat-treated. In FIG. 3 (a), the polarizing plate warped on the convex side refers to the front-side polarizing plate 400, and in FIG. 3 (b), the polarizing plate on the warped convex side refers to the rear-side polarizing plate. 401. The polarizing plate warped into a convex shape may be a front-side polarizing plate or a back-side polarizing plate. In addition to the polarizer that has been subjected to an extension treatment, the rear-side polarizer generally includes a brightness enhancement film that has been subjected to an extension treatment. When the absorption axis direction of the back-side polarizer becomes the long side direction, the Most of the contraction force is larger than that of the front side polarizer.

The shape of the polarizing plate and the shape of the glass plate when bonded to the glass plate are not particularly limited, and preferably a rectangular shape. At this time, the front-side polarizing plate and the back-side polarizing plate may be the same size. When the polarizing plate is bonded to the glass plate, the polarizing plate is bonded so that the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate are perpendicular to each other. At this time, when the polarizing plate has a rectangular shape, the absorption axis of the front-side polarizing plate is preferably parallel to the short side, and the absorption axis of the back-side polarizing plate is preferably parallel to the long side.

In the set of polarizing plates of the present invention, by reducing the distance between the polarizer and the liquid crystal cell, the polarizing plate (especially the back-side polarizing plate) can reduce the force of deformation of the liquid crystal cell accompanying the shrinkage of the polarizer and reduce the high temperature. Influence on the warpage of the LCD panel under the environment.

The distance from the surface near the liquid crystal cell in the polarizer of the back side polarizer to the surface near the polarizer side in the back side polarizer of the liquid crystal cell is preferably 50 μm or less, more preferably 40 μm or less, and more It is preferably 35 μm or less.

The thickness of the glass plate can be, for example, 100 μm or more and 400 μm or less. When the thickness is within this range, it is easy to distinguish which of the front-side polarizing plate and the back-side polarizing plate is a polarizing plate warped to a convex shape side.

The polarizing plate warped into a convex shape side may have a protective film on both sides of the polarizer, preferably at least one protective film at this time satisfies formula (1), and more preferably is a protection layered on the polarizer near the liquid crystal cell side. The film satisfies the formula (1), and more preferably, any protective film satisfies the formula (1). Of course, one protective film may satisfy the formula (1) and the other protective film may not satisfy the formula (1). The protective film herein means a film laminated on a polarizer through an adhesive layer or an adhesive layer.

The tensile elastic modulus Et of the polarizing plate penetration axis direction at 85 ° C. is preferably 500 MPa or more and 10,000 MPa or less, and may be 1,000 MPa or more and 8000 MPa or less. The tensile elastic modulus Ea of the polarizing plate absorption axis direction at 85 ° C is preferably 500 MPa to 10,000 MPa, may be 1000 MPa to 8000 MPa, and may be 2000 MPa to 8000 MPa.

Each member constituting the set of the polarizing plate of the present invention will be described.

(Polarizer)

The polarizer used in the present invention is generally manufactured by the following steps: a step of uniaxially stretching the polyvinyl alcohol-based resin film, and adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with the dichroic dye. A step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with an aqueous solution of boric acid, and a step of washing with water after the treatment with an aqueous solution of boric acid.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin saponified can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and other copolymerizable monomers and the like. 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-based resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl acetal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, and preferably about 1500 to 5,000.

A film made of such a polyvinyl alcohol-based resin is used as a raw material film of a polarizer. A method of forming a polyvinyl alcohol-based resin into a film can be a conventional method. When the thickness of the obtained polarizer is 15 μm or less, the thickness of the polyvinyl alcohol-based raw material film is preferably about 5 to 35 μm, and more preferably 5 to 20 μm. When the film thickness of the raw material film is 35 μm or more, it is necessary to increase the stretching magnification when manufacturing the polarizer, and the size shrinkage of the obtained polarizer tends to become large. On the other hand, when the film thickness of the raw material film is 5 μm or less, the workability during stretching is reduced, and defects such as breakage tend to occur during production.

The uniaxial extension of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dichroic dyeing. When one-axis extension is performed after dyeing, the one-axis extension may be performed before or during the boric acid treatment. Furthermore, one-axis extension can also be performed in these plural stages.

For one-axis extension, one-axis extension can be performed between rollers with different rotation speeds, and one-axis extension can also be performed using a hot roller. In addition, the uniaxial stretching may be a dry stretching in the air, or a wet stretching in which the polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent. The stretching ratio is usually about 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. Specifically, as the dichroic dye, iodine and a dichroic dye can be used. In addition, the polyvinyl alcohol-based resin film is preferably subjected to a dipping treatment with water before the dyeing treatment.

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

On the other hand, when using a dichroic dye as a dichroic dye, the dyeing method of dipping a polyvinyl alcohol-type resin film in the aqueous solution containing a water-soluble dichroic dye is generally used. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ^-4 to 10 parts by weight, preferably about 1 × 10 ^-3 to 1 part by weight, per 100 parts by mass of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) of the aqueous solution is usually about 10 to 1800 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 an aqueous solution containing boric acid.

The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by mass 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, preferably about 5 to 12 parts by weight, per 100 parts by mass of water. The immersion time for an aqueous solution containing boric acid is usually about 60 to 1200 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-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed, for example, by immersing the polyvinyl alcohol-based resin film after the boric acid treatment in water. The water temperature of the water washing treatment is usually about 5 to 40 ° C. The immersion time is usually about 1 to 120 seconds.

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

By drying, the moisture content of the polarizer can be reduced to a practical level. The moisture content of the polarizer 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 polarizer is lost, and the polarizer may be damaged or cracked after it is dried. When the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be deteriorated.

The stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the step of manufacturing the polarizer can be performed according to a method described in Japanese Patent Application Laid-Open No. 2012-159778, for example. The method described in this document is to form a polyvinyl alcohol-based resin layer as a polarizer by applying a polyvinyl alcohol-based resin to a base film.

The reduction in the shrinkage force of the polarizer itself is also effective for reducing warpage in a high temperature environment. The thickness of the polarizer provided with the front-side polarizing plate and the back-side polarizing plate is preferably 15 μm or less, more preferably 2 to 13 μm, and even more preferably 2 to 10 μm.

The difference in thickness between the thickness of the polarizer included in the front-side polarizing plate and the thickness of the polarizer included in the back-side polarizing plate is preferably 5 μm or less, and may also be 3 μm or less. When the polarizing plate warped to the convex shape side satisfies the formula (1), by reducing the thickness difference of the polarizer in this way, the effect of warping on the liquid crystal panel under a high temperature environment can be further reduced.

(Protective film)

The protective film is made of a resin film, and may be made of a transparent resin film. Particularly preferred is made of a material having excellent transparency, mechanical strength, thermal stability, and moisture blocking properties. As used herein, the term "transparent resin film" refers to a resin film in which the monomer transmittance is 80% or more in the visible light region.

When the protective film is laminated on both sides of the polarizer, the protective film may be the same as or different from the other. The protective film of the front-side polarizing plate and the protective film of the rear-side polarizing plate may be the same as each other or may be different from each other.

The resin forming the protective film is not particularly limited, and examples thereof include methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, and acrylic resin. Nitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin Resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyfluorene resin, polyether fluorene resin, polyarylate resin, polymer A film made of amidamine, imine-based resin, and polyimide-based resin.

These resins can be used alone or in combination of two or more. In addition, these resins can also be used after being modified with any suitable polymer. Examples of the polymer modification include copolymerization, cross-linking, modification of molecular ends, control of stereoregularity, and polymerization with different species. In the case of reaction of substances with each other, such as modification.

Among these, the material of the protective film is preferably a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, or a cellulose resin. The polyolefin resin here includes a chain polyolefin resin and a cyclic polyolefin resin.

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

This methyl methacrylate resin is usually obtained by polymerizing a monofunctional monomer having methyl methacrylate as a main component in the presence of a radical polymerization initiator. Coexistence with polyfunctional monomers and chain transfer agents can be used during polymerization as needed.

Although there is no particular limitation on the monofunctional monomer that can be copolymerized with methyl methacrylate, examples include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and formazan. Methacrylates other than methyl methacrylate, such as benzyl acrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, Acrylates such as cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; 2- (hydroxymethyl) acrylate, 3- (hydroxyethyl) ) Hydroxyalkyl acrylates such as methyl acrylate, ethyl 2- (hydroxymethyl) acrylate and butyl 2- (hydroxymethyl) acrylate; unsaturated acids such as methacrylic acid and acrylic acid; chlorostyrene and bromine Halogenated styrenes such as styrene; substituted styrenes such as vinyl toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; maleic anhydride and citraconic acid Unsaturated acid anhydrides such as anhydrides; and phenylmalea Cyclohexylmaleimide and unsaturated acyl imine (PEI) and the like. Such monomers may be used singly or in combination of two or more kinds.

Although the polyfunctional monomer which can be copolymerized with methyl methacrylate is not particularly limited, examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol. Glycols such as alcohol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecyl ethylene glycol di (meth) acrylate, or Those whose two terminal hydroxyl groups of oligomers are esterified with acrylic acid or methacrylic acid; those whose two terminal hydroxyl groups of propylene glycol or its oligomers are esterified with acrylic acid or methacrylic acid; neopentyl glycol di (meth) acrylate, Dihydroxy alcohols such as hexanediol di (meth) acrylate and butanediol di (meth) acrylate are hydroxylated with acrylic acid or methacrylic acid; bisphenol A, ethylene oxide of bisphenol A Acrylic acid or methacrylic acid esterified at the two terminal hydroxyl groups of the product or such halogen substitutions; those with polymethylol such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid, and at the ends of these polyols An epoxy ring-opening addition of propylene acrylate or propylene methacrylate; amber , Dibasic acids such as adipic acid, terephthalic acid, phthalic acid, such halogen substitution products, and alkylene oxide adducts, etc. Epoxy epoxy ring-opening addition; allyl (meth) acrylate; and aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol di (methacrylate), tetraethylene glycol di (methacrylate), and neopentyl glycol di (methacrylate) are preferably used.

As the methyl methacrylate-based resin, it is possible to use a modifier that is reacted between functional groups that is copolymerized in the resin. Examples of the reaction include a de-methanol condensation reaction within a polymer chain of a methyl group of methyl acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, or a carboxyl group of acrylic acid and methyl 2- (hydroxymethyl) acrylate. Dehydration condensation reaction of the hydroxyl polymer chain.

The polyethylene terephthalate resin refers to a resin composed of 80 mol% or more of repeating units composed of ethylene terephthalate, and may also include other dicarboxylic acid components and diol components. Other dicarboxylic acid components are not particularly limited, and examples thereof include isophthalic acid, 4,4'-dicarboxybiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, Adipic acid, sebacic acid, and 1,4-dicarboxycyclohexane.

Other diol components are not particularly limited, and examples thereof include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adducts of bisphenol A, polyethylene glycol, and polyethylene glycol. Propylene glycol and polybutylene glycol.

These dicarboxylic acid components and diol components can be used in combination of two or more kinds as required. Furthermore, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid may be used in combination. As the other copolymerization component, a dicarboxylic acid component or a diol component containing a small amount of an amine bond, an amine ester bond, an ether bond, or a carbonate bond can be used.

The production method of polyethylene terephthalate resin can be the following method: a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as required), and Method for performing polycondensation after transesterification of dialkyl esters of ethylene terephthalate and ethylene glycol (and dialkyl esters of other dicarboxylic acids or other diols as needed), and using a catalyst in the presence of catalyst A method for polycondensing ethylene glycol esters of terephthalic acid (and other dicarboxylic acids as needed) (and other diols as needed) and the like. Furthermore, it is also possible to increase the molecular weight or reduce the low-molecular-weight component by performing solid-phase polymerization as required.

The cyclic polyolefin resin is obtained, for example, by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. The use of such a cyclic polyolefin-based resin is preferable because a protective film having a predetermined retardation value described later can be easily obtained.

Examples of the cyclic polyolefin-based resin include norbornene or norbornene obtained from cyclopentadiene and an olefin or (meth) acrylic acid or an ester thereof by a Diels-Alder reaction. Derivatives are used as monomers, and the monomers undergo metathesis polymerization, followed by hydrogenation. The resins will be obtained from dicyclopentadiene and olefins by Diels-Alder reaction. Tetracyclododecene or its derivative obtained from (meth) acrylic acid or its esters as a monomer, the monomer is subjected to ring-opening metathesis polymerization, and then a resin obtained by hydrogenation; At least two monomers of alkene, tetracyclododecene, these derivatives, and other cyclic olefin monomers are similarly subjected to ring-opening metathesis copolymerization, and then a resin obtained by hydrogenation; Cyclic olefins of alkene, tetracyclododecene or derivatives thereof, resins obtained by addition copolymerization of a chain olefin and / or an aromatic compound having a vinyl group, and the like.

Typical examples of the chain olefin resin are a polyethylene resin and a polypropylene resin. Among them, a homopolymer or copolymer of propylene is suitable, and the copolymer is a comonomer having propylene as a main body and copolymerizable therewith, for example, 1 to 20% by weight of ethylene, preferably 3 to 10% by weight. The proportion of% is obtained by copolymerization.

The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. By containing an alicyclic saturated hydrocarbon resin, it becomes easy to control a retardation value. The content of the alicyclic saturated hydrocarbon resin is preferably 0.1 to 30% by weight, and more preferably 3 to 30% by weight, relative to the polypropylene-based resin. When the content of the alicyclic saturated hydrocarbon resin is less than 0.1% by weight, the effect of controlling the retardation value cannot be sufficiently obtained. On the other hand, when the content exceeds 30% by weight, the alicyclic saturated hydrocarbon resin may occur from the protective film over time. Exuding doubts.

The cellulose resin refers to a part or all of the hydrogen atoms in the hydroxyl groups of the cellulose obtained from cellulose such as cotton linter, wood pulp (broadwood pulp, coniferous pulp) and other raw materials, which are acetyl, propionyl and / or Cellulose organic acid esters or cellulose mixed organic acid esters substituted with butyryl. Examples include cellulose acetate, propionate, butyrate, and mixed esters thereof. Among these, a triethylfluorene-based cellulose film, a diethylfluorene-based cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like are preferred.

A method of using a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, and a cellulose resin as the second protective film for adhering to a polarizer, as long as it is appropriately selected The method of each resin is not particularly limited. For example, the following methods can be used: casting the resin dissolved in the solvent onto a metal belt or drum, drying and removing the solvent to obtain a film; and heating / kneading the resin above its melting temperature, and extruding it with a die. The film is melt-extruded by cooling. The melt extrusion method may be the extrusion of a single-layer film or the simultaneous extrusion of a multilayer film.

A commercially available film can be easily obtained as a protective film. If it is a methyl methacrylate resin film, the product name is exemplified by SUMIPEX (made by Sumitomo Chemical Co., Ltd.), ACRYLITE (registered trademark), ACRYPREN (registered trademark) (all above are made by Mitsubishi Rayon Co., Ltd.), DELLAGLAS (registered trademark) (made by Asahi Kasei Co., Ltd.), PARAGLAS (registered trademark), COMOGLAS (registered trademark) (all above are made by Kuraray Co., Ltd. ) And ACRYLUREA (registered trademark) (manufactured by Japan Catalyst Co., Ltd.). In the case of a polyolefin resin film, each product name is, for example, ZEONOR (registered trademark) (manufactured by ZEON Co., Ltd.), ARTON (registered trademark) (made by JSR Co., Ltd.) and the like. If it is a polyethylene terephthalate-based resin film, each product name is NOVA CLEAR (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemical Corporation). Wait). If it is a polypropylene-based resin film, each product name is, for example, FILMAX CPP film (made by FILMAX), SUNTOX (registered trademark) (made by SUN TOX Co., Ltd.), TOHCELLO (registered trademark) (Tohcello Co., Ltd.) System), Toyobo PIREN FILM (registered trademark) (manufactured by Toyobo Co., Ltd.), TORAYFAN (registered trademark) (manufactured by TORAY FILM Processing Co., Ltd.), NIPPON POLY ACE (manufactured by Japan Poly Ace Co., Ltd.), and Taihe (registered Trademark) FC (manufactured by Fatamura Chemical Co., Ltd.), etc. In addition, if it is a cellulose-based resin film, each product name is, for example, FUJITEC (registered trademark) TD (manufactured by FUJI FILM Co., Ltd.) and KC2UA and Konica Minolta TAC FILM KC (Konica Minolta Limited Company system) and so on.

The protective film and protective film used in the present invention can impart anti-glare properties (haze). The method for imparting anti-glare properties is not particularly limited, and for example, a method in which inorganic fine particles or organic fine particles are mixed with the raw material resin to form a thin film; using the aforementioned multilayer extrusion, one is a resin mixed with fine particles and the other A method of forming a two-layer thin film for a resin without mixed fine particles, or a method of forming a three-layer thin film with a resin mixed with particles as an outer side; and coating and mixing inorganic fine particles or organic fine particles with a hardening adhesive on one side of the film A coating solution made of a resin, a method of hardening a binder resin, and providing an anti-glare layer.

Moreover, the protective film may contain additives as needed. Examples of the additives include lubricants, anticaking agents, heat stabilizers, antioxidants, antistatic agents, light resistance agents, and impact resistance improvers.

From the viewpoints of strength, operability, and the like, the thickness of the protective film is usually about 1 to 50 μm.

Before the protective film is bonded to the polarizer, it is preferable to perform a saponification treatment, a corona treatment, or a plasma treatment.

The protective film on the front side polarizing plate can further be provided with a functional layer such as a conductive layer, a hard coat layer, and a low reflection layer. Furthermore, as the binder resin constituting the anti-glare layer, a resin composition having such functions can be selected.

The protective film satisfying the formula (1) can be produced, for example, by stretching a resin film. If it is a manufacturing method using a sheet film, the stretching method is not particularly limited. It is assumed that in continuous production, an axially-stretched film can be obtained by longitudinally stretching after the film is formed; Obtained biaxially stretched film and so on. The stretching magnification may be, for example, 1.01 or more and 5.00 or less, or 1.01 or more and 3.00 or less.

(Brightening film)

The back side polarizing plate preferably has a brightness enhancement film on the side of the polarizer away from the liquid crystal cell. The thickness of the brightness enhancement film is preferably 35 μm or less, and more preferably 30 μm or less. The thickness of the brightness enhancement film is usually 10 μm or more.

As the brightness enhancement film, a polarization conversion element having a function of separating light emitted from a light source (backlight) into transmitted polarized light, reflected polarized light, or scattered polarized light can be used. The brightness-enhancing film utilizes the reflected polarized light or the scattered polarized light from the backlight to improve the efficiency of emitting linearly polarized light.

The brightness enhancement film may be, for example, an anisotropic reflective polarizer. The anisotropic reflective polarizer can be an anisotropic multiple film that penetrates linearly polarized light in one vibration direction and reflects linearly polarized light in another vibration direction. Examples of the anisotropic multilayer film include the trade name "APF" manufactured by 3M Corporation. The anisotropic reflective polarizer may be, for example, a composite of a cholesteric liquid crystal layer and a λ / 4 plate. The composite may be a trade name "PCF" manufactured by Nitto Denko Corporation. Furthermore, the anisotropic reflective polarizer may be a reflective grating polarizer. The reflective grating polarizer can be a metal grid reflective polarizer that performs fine processing on metal and also generates reflective polarized light in the visible light region. Among these, a brightness enhancement film composed of an anisotropic multiple thin film is preferred.

A functional layer may be formed on a surface of the brightness enhancement film opposite to the bonding surface of the polarizing plate. Examples of the functional layer include a hard coat layer, an anti-glare layer, a light diffusion layer, and a retardation layer having a retardation value of 1/4 wavelength. By this, the adhesion to a backlight tape can be improved, and the uniformity of a displayed image can be improved. Sex.

(Adhesive layer)

An adhesive layer may be laminated on the surface of the polarizing plate. The polarizing plate can be attached to the liquid crystal cell through the adhesive layer. In FIG. 1, which corresponds to the adhesive layer 20, the thickness of the adhesive layer formed of the adhesive is preferably 5 to 25 μm, and more preferably 10 to 25 μm.

The adhesive layer for bonding the front-side polarizing plate to the liquid crystal cell and the adhesive layer for bonding the back-side polarizing plate to the liquid crystal cell may be the same or different from each other.

Furthermore, the brightness enhancement film and the protective film or polarizer can also be laminated by an adhesive. In FIG. 1, these correspond to the adhesive layers 21 and 22. The thickness of the adhesive layer formed from the adhesive is preferably 1 to 20 μm, and more preferably 1 to 10 μm.

The adhesive forming the adhesive layer can be appropriately selected and used, for example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamine, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, and modification. Polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers are used as matrix polymers. The adhesive is particularly preferably an adhesive having excellent optical transparency, exhibiting moderate wettability, cohesiveness, and adhesiveness, and excellent weather resistance and heat resistance.

Various other additives can be blended in the adhesive. Examples of the additive include a silane coupling agent and an antistatic agent.

(Adhesive layer)

The lamination of the protective film and the polarizer, and the lamination of the brightness enhancement film and the polarizer can be performed by, for example, an integrated method using an adhesive. 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. If it is this range, there will be no floating or peeling between a protective film or a brightness enhancement film, and a polarizer, and the adhesive force which does not have a problem practically can be obtained.

Examples of the adhesive include solvent-based adhesives, emulsifier-based adhesives, pressure-sensitive adhesives, rewettable adhesives, polycondensation-based adhesives, solventless adhesives, film-shaped adhesives, and hot-melt adhesives. Moreover, according to need, an adhesion layer may be provided through an anchor layer.

Preferred adhesives include water-soluble adhesives. The water-soluble adhesive is, for example, a polyvinyl alcohol-based resin as a main component. The water-soluble adhesive may be a commercially available one, or may be used in a case where a commercially available adhesive is mixed with a solvent and an additive. Commercially available polyvinyl alcohol-based resins that can be used as water-soluble adhesives include, for example, KL-318 manufactured by Kuraray Corporation.

The water-soluble adhesive may contain a crosslinking agent. As for the type of a crosslinking agent, an amine compound, an aldehyde compound, a methylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt, etc. are preferable, and an epoxy compound is especially preferable. Commercial products of the cross-linking agent include, for example, glyoxal, SUMIREZ RESIN650 (30) manufactured by Taoka Chemical Industry Co., Ltd., and the like.

Further, another preferable adhesive may be an active energy ray-curable adhesive composed of a resin composition which is cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive include a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin, and a photoreactive crosslinker. Examples of the polymerizable compound include a photocurable epoxy-based monomer, a photocurable acrylic monomer, a photocurable monomer of a photocurable amine ester monomer, or an oligomer derived from the photopolymerizable monomer. The photopolymerization initiator may include a substance that generates an active species such as a radical, a cation, or an anion by irradiation with an active energy ray such as ultraviolet rays. The active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator is preferably one containing a photocurable epoxy-based monomer and a photocationic polymerization initiator.

When an active energy ray-curable adhesive is used, after the polarizer and the protective film are bonded, a drying step is performed as required, and then a hardening step of curing the active energy ray-curable adhesive by irradiating the active energy ray is performed. The light source of the active energy ray is not particularly limited, and it is preferably ultraviolet light having a luminous distribution below a wavelength of 400 nm. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, and microwave excitation can be used. Mercury lamps, metal halide lamps, etc.

The said adhesive may also contain additives. Examples of the additives include ion trapping agents, antioxidants, chain transfer agents, sensitizers, adhesion-imparting agents, thermoplastic resins, fillers, flow modifiers, plasticizers, and defoamers.

(Hardened layer of active energy ray-curable resin composition)

The hardened layer of the active energy ray-curable resin composition is useful as a protective layer for protecting the surface of a polarizer. The hardened layer of the active-energy-ray-curable resin composition can be made thinner than a normal protective film, and therefore it is effective in reducing the thickness of a polarizing plate.

The thickness of the hardened layer of the active energy ray-curable resin composition is preferably 0.01 to 20 μm, more preferably 0.01 to 10 μm, and still more preferably 0.01 to 5 μm.

As the active energy ray-curable resin composition forming the hardened layer of the active energy ray-curable resin composition, the same ones as the above-mentioned active energy ray-curable adhesive can be used. The active energy ray-curable resin composition and the active energy ray-curable adhesive may be the same as or different from each other.

(Manufacturing method of polarizing plate)

The members described above can be laminated to each other through, for example, an adhesive layer or an adhesive layer. Moreover, the method of manufacturing a polarizing plate using a release film is also useful.

Hereinafter, a method for manufacturing a front-side polarizing plate and a back-side polarizing plate constituting the polarizing plate of the present invention will be described by taking a set of polarizing plates shown in FIG. 1 (a) as an example.

(Manufacturing method of front side polarizing plate)

A release film, a polarizer 2 and a protective film 10 are prepared, a protective film is bonded to one side of the polarizer with an adhesive therebetween, and a volatile liquid volume layer release film is interposed on the other side of the polarizer. Of course, the lamination of the protective film and the polarizer, and the lamination of the release film and the polarizer can be performed sequentially one by one.

The volatile liquid is, for example, water, a mixture of water and a hydrophilic liquid, and the like. Preferred hydrophilic liquids are those which do not remain after the heat treatment in the second step, and examples thereof include methanol, ethanol, 1-butanol, tetrahydrofuran, acetone, acetonitrile, N, N-dimethylformamide, and diamine. Methyl sulfene, formic acid, acetic acid, etc. Additives such as antistatic agents can also be added to volatile liquids.

The resin forming the release film is not particularly limited, and examples thereof include methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, and acrylic resin. Nitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin Resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyfluorene resin, polyether fluorene resin, polyarylate resin, polymer A film made of amidamine, imine-based resin, and polyimide-based resin.

When the protective film is bonded to the polarizer, on the bonding surface of the polarizer and / or the protective film, in order to improve the adhesion, for example, plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification can be performed. Easy to process. Moreover, in order to improve the wettability of a volatile liquid also to a peeling film, it is useful to perform the same process as a protective film.

When an active energy ray hardening type adhesive is used as the adhesive, the active energy ray is irradiated to harden the adhesive, and then heat treatment is performed to volatilize and remove the volatile liquid. When an aqueous adhesive is used as the adhesive, the polarizer and the protective film are adhered by heat treatment, and the volatile liquid is removed by evaporation. In terms of simplifying the steps, it is preferable to use an aqueous adhesive.

The drying temperature is preferably 30 to 90 ° C. When the temperature is lower than 30 ° C, the time required for drying is long and there is a possibility that appearance defects may occur. In addition, when the drying temperature exceeds 90 ° C, there is a possibility that the polarization performance of the polarizer may be deteriorated due to heat. The drying time may be about 10 to 1,000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

By laminating the peeling film by the polarizer interposing a layer made of a volatile liquid, the heating temperature in this step can be set to, for example, about 60 ° C. or higher and 90 ° C. or lower. That is, even if a higher heating temperature is set, in addition to suppressing the cracking of the polarizer, the shrinkage of the polarizer is small due to the high-temperature heating, so that a single-sided protective polarizer having high dimensional stability can be obtained. By reducing the shrinkage rate of the single-sided protective polarizing plate, when the liquid crystal panel is manufactured using the polarizing plate, the warpage of the liquid crystal panel can be further reduced.

In order to volatilize the volatile liquid used for the laminated layer of the polarizer and the release film by heating, the moisture permeability of at least one of the protective film and the release film is preferably 400 g / m ² ‧24hr or more, more preferably 420 g / m ² ‧24hr or more. When the water vapor transmission rate is within this range, the volatile liquid can be efficiently evaporated and removed in the subsequent second step, so that productivity can be further improved.

The release film is peeled and removed from the single-sided protective polarizer, and the protective film 11 is bonded to the polarizer 2 in the single-sided protective polarizer via an adhesive layer. Further, by forming the adhesive layer 20 on the protective film 11, a front-side polarized light composed of the adhesive layer 20 / the protective film 11 / the adhesive layer 21 / the polarizer 2 / the adhesive layer 30 / the protective film 10 can be obtained. board.

(Manufacturing method of back side polarizing plate)

By the same method as the method for manufacturing the front-side polarizing plate, a release film, a polarizer 2 and a protective film 12 are prepared, a protective film 12 is bonded to one side of the polarizer 2 with an adhesive therebetween, and the other side of the polarizer 2 is prepared The film was peeled off through the volatile liquid volume layer. After the polarizer 2 and the protective film 12 were removed, the volatile liquid was removed, and then the release film was peeled to obtain a single-sided protective polarizing plate.

A brightening film 40 is laminated on the polarizer 2 in the single-sided protective polarizing plate via an adhesive, and an adhesive layer 20 is laminated on the protective film 12, thereby obtaining an adhesive layer 20 / protective film 12 / adhesive. A back side polarizing plate composed of layer 32 / polarizer 2 / adhesive layer 21 / brightening film 40.

The shape of the polarizing plate of the present invention is not particularly limited, and may be rectangular or rectangular with long sides and short sides. When the polarizing plate is manufactured by the roll-to-roll method, it can be cut into a predetermined shape. The polarizing plate of the present invention may have a rectangular shape with a diagonal of 15 inches or less, a rectangular shape with a diagonal of 3 inches or more, or a rectangular shape with a diagonal of 7 inches or more.

(Manufacturing method of liquid crystal panel)

A liquid crystal panel can be obtained by attaching the sets of polarizing plates of the present invention to both sides of a liquid crystal cell, respectively. The bonding is preferably performed through the adhesive layer of the front-side polarizing plate and the adhesive layer of the back-side polarizing plate, respectively. Furthermore, it is preferable that the front-side polarizing plate is laminated on the viewing side of the liquid crystal cell, and the back-side polarizing plate is laminated on the back side of the liquid crystal cell. The liquid crystal panel of the present invention can be suitably applied to a liquid crystal display device. The front-side polarizing plate is preferably attached in such a manner that its absorption axis becomes approximately parallel to the short-side direction of the liquid crystal cell, and the back-side polarizing plate is preferably in such a manner that its absorption axis becomes approximately parallel to the long-side direction of the liquid crystal cell. Perform lamination. In the present specification, the term “parallel about the month” means, for example, that the angle formed is 0 ± 5 °, and preferably 0 ± 1 °.

The liquid crystal cell line has two cell substrates and a liquid crystal layer sandwiched between the substrates. The cell substrate is generally composed of glass, and can also be a plastic substrate. In addition, the liquid crystal cell itself used in the liquid crystal panel of the present invention may be composed of various substances used in the art. According to the set of the polarizing plate of the present invention, even if the thickness of the liquid crystal cell is 0.4 mm or less, warpage can be significantly reduced. In the present invention, the thickness of the liquid crystal cell includes the thickness of the liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer.

    [Example]    

Hereinafter, the present invention will be described in more detail with examples, but the present invention is not limited to these examples. In the examples, the content and percentage used are shown in% and parts, and are based on weight under the restrictions specified. The evaluation methods used in the examples are as follows.

(1) Thickness

The measurement was performed using a digital micrometer MH-15M manufactured by NIKON Corporation.

(2) Tensile elastic modulus

A test piece having a width of 15 mm and a length of 150 mm was cut from the film. Then, using the upper and lower clamps of a tensile tester [AUTOGRAPH (registered trademark) AG-1S tester manufactured by Shimadzu Corporation) with a constant-temperature bath, the interval between the clamps was 100 mm, and the length of the test piece was clamped Both ends in the lateral direction were stretched under an environment of 85 ° C. under a condition of a stretching speed of 50 mm / minute, a stress-strain curve was prepared, and a tensile elastic modulus at 85 ° C. was calculated.

(3) Permeability

The moisture permeability was measured according to JIS Z 0208. Temperature and humidity conditions were set to 40 degrees and 90% RH.

(4) Identification of the polarizing plate warped into a convex shape and measurement of the amount of warping in a high-temperature environment

A sample for evaluation having a configuration of a back-side polarizing plate, a glass plate, and a front-side polarizing plate was left to stand at 85 ° C for 250 hours, and then the front-side polarizing plate was set to the upper side and placed in a two-dimensional measuring device for measurement. On stage. As a two-dimensional measuring instrument, "NEXIV (registered trademark) VMR-12072" manufactured by NIKON Corporation was used. Then, focus on the surface of the measuring table, use this focal point as a reference, focus on 25 points on the surface of the evaluation sample, and measure the height from the focal point used as a reference. The difference between the maximum value and the minimum value of the height of the 25 measurement points is the amount of warpage. The warpage of the edge of the evaluation sample on the front side of the polarizer is set to positive warp, and the edge of the evaluation sample is warped on The warpage on the back side polarizing plate is set to negative warpage. When positive warping, a polarizing plate warped into a convex shape is a back side polarizing plate, and when negative warping, a polarizing plate warped into a convex shape is a front side polarizing plate.

Specifically, the point 80 shown in FIG. 4 is used as a measurement point. The 25 points shown in FIG. 4 are points from a 7 mm area inside the end of the polarizing plate, and are arranged at intervals of about 20 mm in the short side direction and about 35 mm in the long side direction. In FIG. 4, reference numeral 402 denotes a polarizing plate, and 70 denotes a glass plate.

[Manufacturing Example 1] Production of Polarizer

A polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) was dry-stretched to perform a uniaxial extension of about 4 times, and further maintained in a tense state, directly immersed in a pure solution at 40 ° C. After 40 seconds of water, the solution was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water at 28 ° C. of 0.052 / 5.7 / 100 for 30 seconds to perform a dyeing treatment. Then, it was immersed in an aqueous solution of a potassium iodide / boric acid / water weight ratio of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Next, it was washed with pure water at 8 ° C for 15 seconds, and was maintained at a tension of 300N, and then dried at 60 ° C for 50 seconds and then at 75 ° C for 20 seconds. A polarizer with a thickness of 7 μm.

[Production Example 2] Production of water-based adhesive

With respect to 100 parts by weight of water, 3 parts by weight of carboxyl-modified polyvinyl alcohol [trade name "KL-318" purchased from KURARAY Co., Ltd.] was dissolved, and a polyisocyanate belonging to a water-soluble epoxy resin was added to the aqueous solution. 1.5 parts by weight of an amine epoxy-based additive [trade name "SUMIREZ RESIN (registered trademark) 650 (30)", an aqueous solution having a solid content concentration of 30%] purchased from Taoka Chemical Industry Co., Ltd. to prepare an aqueous adhesive.

[Protective film A, B, C, D and release film E]

The following five types of protective films and two types of release films were prepared.

Protective film A: 25KCHCN-TC. A saponified film of a triethyl cellulose film with a hard coat layer, made by Toppan Printing Co., Ltd. The thickness is 32 μm, and the moisture permeability is 450 g / m ² ‧24hr.

Protective film B: ZT12. Cyclic polyolefin resin film made by Japan Zeon Corporation. It has a thickness of 20 μm and is manufactured by extending one axis in the lateral direction.

Protective film C: ZERO TACK (registered trademark). Saponified cellulose triethyl cellulose membrane made by Konica Minolta Co., Ltd. The thickness is 20 μm.

Protective film D: ZF14-023. Cyclic polyolefin resin film made by Japan Zeon Corporation. The thickness is 23 μm.

Release film E: Polymethyl methacrylate resin film made by Sumitomo Chemical Co., Ltd. The thickness is 80 μm and the moisture permeability is 50 g / m ² ‧24hr.

[Example 1]

[Production of front side polarizing plate A]

The polarizer obtained in Production Example 1 was continuously conveyed, and the protective film A was continuously rolled out from the roller of the protective film A, and the release film E was continuously rolled out from the roller of the release film E. Then, a water-based adhesive is injected between the polarizer and the protective film A, and pure water is injected between the polarizer and the release film E, and the protective film A / water-based adhesive / polarizer / pure water is made by a bonding roller. / Laminated film composed of release film E. Next, the laminated film was conveyed and subjected to a heat treatment at 80 ° C for 300 seconds in a drying furnace, thereby drying the water-based adhesive and volatilizing and removing pure water existing between the polarizer and the release film E to obtain a unit with a release film. Surface protection polarizer. The peeling film E was peeled from the one-sided protective polarizing plate with a peeling film, and the one-sided protective polarizing plate was obtained.

An adhesive layer [trade name "# L2" manufactured by Lintec Co., Ltd. with a thickness of 5 [mu] m] was attached to the polarizer of the single-sided protective polarizing plate, and then the protective film B was extended on the adhesive layer. The protective film B is bonded so that the direction becomes the same direction as the direction of the absorption axis of the polarizing plate. Then, an adhesive layer [trade name "#KT", manufactured by Lintec Co., Ltd.] was laminated on the protective film B to have a thickness of 20 µm. 〕. In this manner, a front-side polarizing plate A composed of the protective film A / water-based adhesive / polarizer / adhesive layer / protective film B / adhesive layer was produced.

[Production of the back side polarizing plate D]

The polarizer obtained in Production Example 1 was continuously conveyed, and the protective film C was continuously rolled out from the roller of the protective film C, and the release film E was continuously rolled out from the roller of the release film E. Then, a water-based adhesive is injected between the polarizer and the protective film C, and pure water is injected between the polarizer and the release film E. A laminating roller is used to prepare a protective film C / water-based adhesive / polarizer / pure Laminated film composed of water / release film E. Next, the laminated film was conveyed and subjected to a heat treatment at 80 ° C for 300 seconds in a drying furnace, thereby drying the water-based adhesive and volatilizing and removing pure water existing between the polarizer and the release film E to obtain a unit with a release film. Surface protection polarizer. The peeling film E was peeled from the one-sided protective polarizing plate with a peeling film, and the one-sided protective polarizing plate was obtained.

A 15 μm-thick acrylic adhesive [a carrier-free film with a separation film manufactured by Lintec Co., Ltd.] was coated on the polarizer of the single-sided protective polarizer, and a brightness enhancement film was attached to the adhesive layer [ The brand name "Advanced Polarized Film, Version 3" made by 3M Corporation is 26 μm in thickness. 〕. Then, an adhesive layer [trade name "# K1" manufactured by Lintec Co., Ltd.] was laminated on the protective film C to have a thickness of 15 µm. 〕. In this manner, a back-side polarizing plate D composed of a brightness enhancement film, an adhesive layer, a polarizer, an aqueous adhesive layer, a protective film C, and an adhesive layer was produced.

[Preparation of evaluation samples]

The front-side polarizing plate A is cut into a rectangular shape of 155.25 mm in the transmission axis direction and 95.90 mm in the absorption axis direction, and the back-side polarizing plate D is cut in a rectangular shape of 155.25 mm in the absorption axis direction and 95.90 mm in the transmission axis direction. Next, a glass plate (made by Corning Corporation, model: EAGLE XG (registered trademark)) with a thickness of 0.4 mm was prepared so that the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate were perpendicular to each other with an adhesive therebetween. Layer, and the front-side polarizing plate and the back-side polarizing plate are bonded to a glass plate.

About the obtained evaluation sample, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The polarizing plate warped into a convex shape is a front-side polarizing plate, and the protective film B has a tensile elastic modulus of 1794 MPa at 85 ° C in the transmission axis direction of the front-side polarizing plate, and an absorption axis direction of the front-side polarizing plate. The tensile modulus of elasticity is 2190 MPa. The protective film A has a tensile elastic modulus in the transmission axis direction of the front-side polarizing plate at 85 ° C of 3563 MPa, and a tensile elastic modulus in the absorption axis direction of the front-side polarizing plate is 3010 MPa.

[Example 2]

Except that the protective film B was changed to the protective film D, it was produced in the same manner as the front-side polarizing plate A, and a front surface composed of the protective film A / water-based adhesive / polarizer / adhesive layer / protective film D / adhesive layer was produced. Side polarizer B.

For the back-side polarizing plate, the back-side polarizing plate D used in Example 1 was used. Then, except that the front-side polarizing plate A was changed to the front-side polarizing plate B of this example, the same procedure as in Example 1 was performed to prepare a sample for evaluation.

About the obtained evaluation sample, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The polarizing plate warped into a convex shape side is the front side polarizing plate, and the protective film D has a tensile elastic modulus of 2053 MPa at 85 ° C in the transmission axis direction of the front side polarizing plate, and the absorption axis direction of the front side polarizing plate. The tensile modulus of elasticity is 2058 MPa. The protective film A has a tensile elastic modulus in the transmission axis direction of the front-side polarizing plate at 85 ° C of 3563 MPa, and a tensile elastic modulus in the absorption axis direction of the front-side polarizing plate is 3010 MPa.

[Comparative Example 1]

The protective film B was produced in the same manner as the front-side polarizing plate A, except that the extension direction of the protective film B and the transmission axis direction of the polarizing plate were the same. The front side polarizing plate C composed of the sheet / adhesive layer / protective film B / adhesive layer.

For the back-side polarizing plate, the back-side polarizing plate D used in Example 1 was used. Then, except that the front-side polarizing plate A was changed to the front-side polarizing plate C of this embodiment, the same procedure as in Example 1 was performed to prepare a sample for evaluation.

About the obtained evaluation sample, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The polarizing plate warped into a convex shape is a front-side polarizing plate, and the protective film B has a tensile elastic modulus of 2190 MPa at 85 ° C. in the transmission axis direction of the front-side polarizing plate, and an absorption axis direction of the front-side polarizing plate. The tensile modulus of elasticity is 1794 MPa. The protective film A has a tensile elastic modulus in the transmission axis direction of the front-side polarizing plate at 85 ° C of 3563 MPa, and a tensile elastic modulus in the absorption axis direction of the front-side polarizing plate is 3010 MPa.

As shown in Table 1, the tensile elastic modulus of the protective film of the polarizing plate warped to the convex side is set to Et, Ea, which satisfies Ea / Et ≧ 0.95, and can reduce the amount of warping in a high temperature environment.

    [Industrial availability]    

The set of polarizing plates according to the present invention is useful because it can reduce the warpage of the liquid crystal panel in a high-temperature environment.

Claims (4)

    A polarizing plate set includes a front-side polarizing plate arranged on the viewing side of a liquid crystal cell and a back-side polarizing plate arranged on the back side of the liquid crystal cell; wherein the absorption axis of the front-side polarizing plate and the foregoing The absorption axis of the back-side polarizing plate is vertical. The front-side polarizing plate and the back-side polarizing plate are bonded to a glass plate to form a laminated body. When the laminated body is heated at 85 ° C. for 250 hours, the laminated body is warped. At least one protective film in the polarizing plate on the convex side, the tensile elastic modulus of the polarizing plate at the axial direction of 85 ° C and the tensile elastic modulus of the polarizing plate at the axial direction of absorption at 85 ° C are respectively When Et and Ea are expressed, Ea / Et ≧ 0.95 (1) is satisfied.         According to the set of the polarizing plate described in item 1 of the scope of the patent application, the front-side polarizing plate and the back-side polarizing plate each have a polarizer containing a polyvinyl alcohol resin film, and the thickness of the polarizer is 15 μm. the following.         The set of the polarizing plate according to item 1 or 2 of the scope of patent application, wherein the difference between the thickness of the polarizer included in the front-side polarizing plate and the thickness of the polarizer included in the rear-side polarizing plate is 5 μm or less.         A liquid crystal panel is provided with a set of a polarizing plate and a liquid crystal cell according to any one of claims 1 to 3, wherein the thickness of the liquid crystal cell is 0.4 mm or less.