JP2019148826A - Set of polarizing plates and liquid crystal panel - Google Patents

Abstract

To provide a set of polarizing plates capable of reducing warpage of liquid crystal panel under a high temperature environment.SOLUTION: A set of polarizing plates comprises a laminate including a front side polarizing plate disposed at a visible side of the liquid crystal cell and a back side polarizing plate disposed at a back side of the liquid crystal cell. The front side polarizing plate and the back side polarizing plate are stuck on a glass plate so that an absorption axis of the front side polarizing plate and an absorption axis of the back side polarizing plate crosses each other. When defining a tensile modulus in a transmission axis direction of the polarizing plate at 85°C as Et, and when defining a tensile modulus in an absorption axis direction of the polarizing plate at and 85°C as Ea, at least one protective film on the polarizing plates at a side where a laminate warps into a convex shape when the laminate is heated at 85°C for 250 hours satisfies Ea/Et≥0.95.SELECTED DRAWING: Figure 1

Description

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

  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. A liquid crystal panel constituting a liquid crystal display device has a configuration in which a pair of polarizing plates are laminated on both surfaces of a liquid crystal cell.

  In Japanese Patent Laying-Open No. 2013-37115 (Patent Document 1), the polarizing film included in the optical laminate on the front side is 5 μm than the polarizing film included in the optical laminate disposed on the side opposite to the front side. A method for suppressing warpage of a liquid crystal panel in a high temperature environment by laminating a polarizing film and a reflective polarizing film included in an optical laminate that is thicker than that and disposed on the side opposite to the front side is presented. ing. These techniques were effective when using a liquid crystal cell having a large thickness (for example, 0.5 mm or more, further 0.7 mm or more) and a reflective polarizing film having a large thickness (for example, 50 μm or more). However, in recent years, in addition to thinning of each member constituting the polarizing plate and weakness, suppression of warpage of the liquid crystal panel in a high temperature environment is insufficient for a thin liquid crystal cell.

JP2013-37115A

  An object of this invention is to provide the set of the polarizing plate which can reduce the curvature of the liquid crystal panel in a high temperature environment.

[1] It has 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,
A laminate in which the front side polarizing plate and the rear side polarizing plate are bonded to a glass plate so that the absorption axis of the front side polarizing plate and the absorption axis of the rear side polarizing plate are orthogonal to each other, When heated at 250 ° C. for at least one of the protective films in the polarizing plate on which the laminate warps, the tensile modulus in the polarizing plate transmission axis direction at 85 ° C. and the polarizing plate absorption at 85 ° C. A set of polarizing plates satisfying the following formula (1) when the tensile modulus in the axial direction is Et and Ea, respectively.
Ea / Et ≧ 0.95 (1)
[2] The polarization according to [1], wherein each of the front-side polarizing plate and the rear-side polarizing plate has a polarizer made of a polyvinyl alcohol-based resin film, and the thickness of each of the polarizers is 15 μm or less. A set of boards.
[3] The polarizing plate according to [1] or [2], 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 back side polarizing plate is 5 μm or less. set.
[4] A liquid crystal panel comprising the set of polarizing plates according to any one of [1] to [3] and a liquid crystal cell, wherein the liquid crystal cell has a thickness of 0.4 mm or less.

  According to the set of polarizing plates of the present invention, it is possible to reduce the warpage of the liquid crystal panel in a high temperature environment.

It is sectional drawing which shows an example of the set of the polarizing plate of this invention. It is sectional drawing which shows an example of the liquid crystal panel of this invention. It is a schematic cross section after heat-processing the sample for evaluation. It is a top view which shows the position which measured the curvature amount of the sample for evaluation.

  The polarizing plate set and the liquid crystal panel of the present invention will be described with reference to the drawings as appropriate. The set of polarizing plates of the present invention has 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.

  In one embodiment, the polarizing plate of the present invention has the member shown in FIG. The set of polarizing plates shown in FIG. 1A includes a front side polarizing plate 100 and a back side polarizing plate 200. In the front side polarizing plate 100, the protective film 10 is laminated on one surface of the polarizer 2 via an adhesive layer 30, and the protective film 11 is laminated on the other surface of the polarizer 2 via an adhesive layer 21. Has been. Further, an adhesive layer 20 is laminated on the protective film 11.

  In the back side polarizing plate 200, the protective film 12 is laminated on one surface of the polarizer 2 via an adhesive layer 32, and the brightness enhancement film is further formed on the other surface of the polarizer 2 via an adhesive layer 21. 40 are stacked. Further, an adhesive layer 20 is laminated on the protective film 12.

  In addition, the set of polarizing plates illustrated in FIG. 1B includes a front side polarizing plate 101 and a back side polarizing plate 201. In the front-side polarizing plate 101, the protective film 10 is laminated on one surface of the polarizer 2 via an adhesive layer 30, and the protective film 11 is laminated on the other surface of the polarizer 2 via an adhesive layer 31. Has been. Furthermore, an adhesive layer 20 is laminated on the protective film 11.

  In the back side polarizing plate 201, the protective film 12 is laminated on one surface of the polarizer 2 via the adhesive layer 31, and the brightness enhancement film 40 is laminated on the protective film 12 via the pressure-sensitive adhesive layer 22. ing. Further, an adhesive layer 20 is laminated on the other surface of the polarizer 2.

  In the set of polarizing plates shown in FIG. 1, the pressure-sensitive adhesive layer 20 may be a pressure-sensitive adhesive layer for laminating a polarizing plate on a liquid crystal cell, for example.

  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, but may be rectangular. When the shape of the polarizing plate is a rectangle having a long side and a short side, 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 parallel to the long side. It is preferable that

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

Ea / Et ≧ 0.95 (1)

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

  When the wrinkle of the laminate warps on the front side polarizing plate side, the polarizing plate on the side that protrudes in a convex shape is the back side polarizing plate, and when the wrinkle of the laminate on the back side polarizing plate side warps, it becomes a convex shape The polarizing plate on the warping side is a front side polarizing plate. This will be specifically described with reference to FIG. FIG. 3 shows a schematic cross section after the laminated body in which the front-side polarizing plate 400 and the rear-side polarizing plate 401 are bonded to the glass plate 70 is heat-treated. In FIG. 3A, the polarizing plate on the convex warped side refers to the front side polarizing plate 400, and in FIG. 3B, the convex side of the polarizing plate refers to the rear side polarizing plate. 401 is indicated. The polarizing plate on the side warped in the convex shape may be a front side polarizing plate or a back side polarizing plate. Since the back side polarizing plate often has a brightness enhancement film that has been subjected to the stretching treatment in addition to the polarizer subjected to the stretching treatment, when the absorption axis direction of the back side polarizing plate is the long side direction, The shrinkage force when the back side polarizing plate is heated is often larger than that of the front side polarizing plate.

  The shape of the polarizing plate and the shape of the glass plate when bonded to the glass plate are not particularly limited, but are preferably rectangular, and at this time, the front side polarizing plate and the back side polarizing plate can have 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 orthogonal 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.

  The thickness of the glass plate can be, for example, 100 μm or more and 400 μm or less. When the thickness is in such a range, it is easy to determine which of the front-side polarizing plate and the rear-side polarizing plate is the polarizing plate warped in the concave shape.

The polarizing plate on the convex warped side may have a protective film on both sides of the polarizer, and in this case, at least one of the protective films preferably satisfies the formula (1), from the liquid crystal cell in the polarizer. It is more preferable that the protective film laminated | stacked on the near side satisfy | fills Formula (1), and it is still more preferable that any protective film satisfy | fills Formula (1). Of course, one protective film does not need to satisfy Formula (1) and the other protective film does not have to satisfy Formula (1).
A protective film here refers to the film laminated | stacked on the polarizer through the adhesive bond layer or the adhesive layer.

  The tensile elastic modulus Et in the transmission axis direction at 85 ° C. is preferably 500 MPa or more and 10,000 MPa or less, and may be 1000 MPa or more and 8000 MPa or less. The tensile elastic modulus Ea in the absorption axis direction at 85 ° C. is preferably 500 MPa or more and 10,000 MPa or less, 1000 MPa or more and 8000 MPa or less, or 2000 MPa or more and 8000 MPa or less.

  Each member which comprises the set of the polarizing plate of this invention is demonstrated.

(Polarizer)
The polarizer used in the present invention is usually a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, a dichroic dye It is manufactured through a step of treating the polyvinyl alcohol-based resin film adsorbed with boric acid aqueous solution and a step of washing with water after the treatment with boric acid aqueous solution.

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

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

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

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

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

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

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

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

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

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

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

  After washing with water, a drying process is performed to obtain a polarizer. 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 process, the moisture content of the polarizer 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 polarizer is lost, and the polarizer may be damaged or broken after drying.
On the other hand, if the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be inferior.

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

  Reducing the contraction force of the polarizer itself is also effective in reducing warpage in a high temperature environment, and the thickness of the polarizer provided for the front side polarizing plate and the back side polarizing plate is preferably 15 μm or less. More preferably, it is 4-13 micrometers, and it is further more preferable that it is 5-10 micrometers.

  The difference 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 be 3 μm or less. When the protective film of the polarizing plate on the convex warping side satisfies the formula (1), the influence on the warpage of the liquid crystal panel under a high temperature environment is further reduced by reducing the thickness difference of the polarizer in this way. be able to.

(Protective film)
The protective film is composed of a resin film and can be composed of a transparent resin film. In particular, it is preferable to use a material that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, and the like. In this specification, the transparent resin film means a resin film having a single transmittance of 80% or more in the visible light region.

  When laminating protective films on both sides of the polarizer, the same protective films may be used, or different protective films may be used. Moreover, the same thing may mutually be used for the protective film in a front side polarizing plate, and the protective film in a back side polarizing plate, and a mutually different thing may be used.

  The resin for forming the protective film is not particularly limited. For example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile.・ Butadiene / styrene resins, acrylonitrile / styrene resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, Examples thereof include films made of polyethylene terephthalate resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin, polyimide resin, 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, as the material for the protective film, it is preferable to use 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 is a polymer containing 50% by weight or more of methyl methacrylate units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

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

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

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

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

  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 cyclic polyolefin-based resin is obtained by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. 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.

  As the cyclic polyolefin-based resin, for example, ring-opening metathesis polymerization is performed from cyclopentadiene and olefins or (meth) acrylic acid or esters thereof using norbornene obtained by Diels-Alder reaction or a derivative thereof as a monomer. Resin obtained by hydrogenation; ring-opening metathesis polymerization using dicyclopentadiene and olefins or (meth) acrylic acid or esters thereof by tetracyclododecene or a derivative thereof obtained by Diels-Alder reaction, Resin obtained by subsequent hydrogenation; ring-opening metathesis copolymerization of at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof, and other cyclic olefin monomers, Resins obtained by hydrogenation; resins obtained by addition copolymerization of aromatic compounds having chain olefins and / or vinyl groups with cyclic olefins such as norbornene, tetracyclododecene, or derivatives thereof Can be mentioned.

  Typical examples of the chain polyolefin resin are a polyethylene resin and a polypropylene resin. Among them, a homopolymer of propylene, or a copolymer obtained by copolymerizing propylene as a main component and a comonomer copolymerizable therewith, for example, ethylene in a proportion of 1 to 20% by weight, preferably 3 to 10% by weight. Preferably used.

  The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. By containing the alicyclic saturated hydrocarbon resin, the retardation value can be easily controlled. The content of the alicyclic saturated hydrocarbon resin is advantageously 0.1 to 30% by weight relative to the polypropylene resin, and more preferably 3 to 20% by weight. 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, while when the content exceeds 30% by weight, the protective film Therefore, there is a concern that the alicyclic saturated hydrocarbon resin may bleed out over time.

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

As a method of using a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, and a cellulose resin as a second protective film for adhering to a polarizer, a method corresponding to each resin is appropriately selected. Well, 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 the protective film can be easily obtained as a commercial product, and if it is a methyl methacrylate-based resin film, the trade name is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite (registered trademark), Acriprene (registered trademark) (Mitsubishi Rayon Co., Ltd.), Delagras (registered trademark) (Asahi Kasei Co., Ltd.), Paragrass (registered trademark), Comogras (registered trademark) (manufactured by Kuraray Co., Ltd.), Registered trademark) (manufactured by Nippon Shokubai Co., Ltd.). If it is a polyolefin-type resin film, ZEONOR (registered trademark) (Nippon Zeon Co., Ltd.), Arton (registered trademark) (JSR Co., Ltd.), etc. are mentioned by a brand name, respectively. If it is a polyethylene terephthalate-type resin film, Novaclear (trademark) (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 resin films, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film (Registered trademark) (manufactured by Toyobo Co., Ltd.), Treffan (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), Nihon Polyace (manufactured by Nippon Polyace Co., Ltd.), and Dazai (registered trademark) FC (Futamura Chemical Co., Ltd.) Manufactured). In the case of cellulose-based resin films, Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.) and the like can be mentioned.

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

  Moreover, a protective film can also contain an additive as needed. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, and an impact resistance improver.

  The thickness of the protective film is usually about 1 to 50 μm from the viewpoints of strength and handleability.

  The protective film is preferably subjected to saponification treatment, corona treatment, plasma treatment or the like prior to bonding with the polarizer.

  The protective film for the front-side polarizing plate can further be provided with functional layers such as a conductive layer, a hard coat layer, and a low reflection layer. Moreover, the resin composition which has these functions can also be selected for the binder resin which comprises the said glare-proof layer.

  The protective film satisfying the formula (1) can also be produced, for example, by stretching a resin film. The stretching method is not particularly limited as long as it is a production method using a single-wafer film, but when continuous production is assumed, a uniaxially stretched film obtained by longitudinal stretching after film formation, longitudinal stretching after film formation, and then transverse It can be a biaxially stretched film obtained by stretching. The draw ratio can be, for example, 1.01 or more and 5.00 or less, and may be 1.01 or more and 3.00 or less.

(Brightness enhancement film)
The back side polarizing plate preferably has a brightness enhancement film on the side of the polarizer that is far 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 outgoing light from a light source (backlight) into transmitted polarized light, reflected polarized light, or scattered polarized light is used. Such a brightness enhancement film can improve the output efficiency of linearly polarized light by using retroreflected light from a reflected or scattered polarized backlight.

  Examples of the brightness enhancement film include anisotropic reflective polarizers. An example of the anisotropic reflective polarizer is an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. An example of the anisotropic multi-thin film is a trade name “APF” manufactured by 3M. An example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ / 4 plate. An example of such a composite is a product name “PCF” manufactured by Nitto Denko Corporation. An example of the anisotropic reflective polarizer is a reflective grid polarizer. Examples of the reflective grid polarizer include metal grid reflective polarizers that perform fine processing on metal and emit reflected polarized light even in the visible light region. Of these, a brightness enhancement film comprising an anisotropic multiple thin film is preferred.

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

(Adhesive layer)
An adhesive layer can be laminated on the surface of the polarizing plate. A polarizing plate can be bonded to a liquid crystal cell through the said adhesive layer. In FIG. 1, the pressure-sensitive adhesive layer 20 corresponds to this.
The thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is preferably 5 to 25 μm, and more preferably 10 to 25 μm.

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

  Moreover, a brightness improvement film, a protective film, or a polarizer can also be laminated | stacked by an adhesive layer. In FIG. 1, the adhesive layers 21 and 22 correspond to this. The thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is preferably 1 to 20 μm, and more preferably 1 to 10 μm.

  Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy-based, fluorine-based, natural rubber, What uses rubber-type polymers, such as a synthetic rubber, as a base polymer can be selected suitably, and can be used. As the pressure-sensitive adhesive, those having excellent optical transparency, moderate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are particularly preferable.

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

(Adhesive layer)
Lamination | stacking with a protective film and a polarizer and lamination | stacking with a brightness improvement film and a polarizer can be performed by the method of integrating using an adhesive agent, for example. 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, neither a float nor peeling will arise between a protective film or a brightness improvement film, and a polarizer, and the adhesive force which does not have a problem practically will be obtained.

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

  A preferable adhesive is a water-soluble adhesive. This water-soluble adhesive includes, for example, 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 water-soluble adhesives include KL-318 manufactured by Kuraray Co., Ltd.

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

  Another preferred adhesive is an active energy ray-curable adhesive made of a resin composition that is cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, and those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from the photopolymerizable monomer. As a photoinitiator, what contains the substance which generate | occur | produces active species like a radical, a cation, or an anion by irradiation of active energy rays like an ultraviolet-ray can be mentioned. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photocurable epoxy monomer and a cationic photopolymerization initiator can be preferably used.

  When using an active energy ray-curable adhesive, after bonding a polarizer and a protective film, a drying step is performed as necessary, and then the active energy ray-curable adhesive is irradiated by irradiating active energy rays. A curing step for curing is performed. The light source of the active energy ray is not particularly limited, but ultraviolet light having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low pressure mercury lamp, the medium pressure mercury lamp, the high pressure mercury lamp, the ultrahigh pressure mercury lamp, the chemical lamp, the black light lamp, the micro A wave excitation mercury lamp, a metal halide lamp, etc. can be used.

  The adhesive may contain an additive. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent.

(Hardened layer of active energy ray-curable resin composition)
The cured layer of the active energy ray-curable resin composition is useful as a protective layer for protecting the surface of the polarizer. Since the hardened layer of the active energy ray-curable resin composition can be made thinner than an ordinary protective film, it is effective for making the polarizing plate thinner.

  The thickness of the cured 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 for forming the cured layer of the active energy ray curable resin composition, the same active energy ray curable adhesive as that described above can be used. The active energy ray curable resin composition and the active energy ray curable adhesive may be the same as each other or different from each other.

(Production method of polarizing plate)
The members described above can be bonded to each other by, for example, laminating via an adhesive layer or an adhesive layer. Moreover, the method of manufacturing a polarizing plate using a peeling film is also useful.

  Hereinafter, the manufacturing method of the front-side polarizing plate and the rear-side polarizing plate constituting the polarizing plate of the present invention will be described taking as an example the set of polarizing plates shown in FIG.

(Manufacturing method of front side polarizing plate)
A release film, a polarizer 2 and a protective film 10 are prepared, and a protective film is bonded to one side of the polarizer via an adhesive, and a volatile liquid is provided to the other side of the polarizer. Laminate the release film. Of course, the lamination of the protective film and the polarizer and the lamination of the release film and the polarizer may be sequentially performed.

  The volatile liquid is, for example, water or a mixture of water and a hydrophilic liquid. The hydrophilic liquid is preferably one that does not remain after the heat treatment in the second step. For example, methanol, ethanol, 1-butanol, tetrohydrofuran, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, Examples include formic acid and acetic acid. An additive such as an antistatic agent may be added to the volatile liquid.

  The resin for forming the release film is not particularly limited. For example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile・ Butadiene / styrene resins, acrylonitrile / styrene resins, polyvinyl acetate resins, polyvinylidene chloride resins, polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, Examples thereof include films made of polyethylene terephthalate resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin, polyimide resin, and the like.

  When bonding a protective film to a polarizer, the bonding surface of the polarizer and / or protective film is subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, Ken, in order to improve adhesion. An easy adhesion treatment such as a crystallization treatment can be performed. In addition, it is also useful to perform the same treatment as the protective film in order to improve the wettability of the volatile liquid to the release film.

  When an active energy ray-curable adhesive is used as the adhesive, the active energy rays are irradiated to cure the adhesive, and then the heat treatment is performed to volatilize and remove the volatile liquid. When an aqueous adhesive is used as the adhesive, the volatile liquid is removed by volatilization while adhering the polarizer and the protective film by performing a heat treatment. It is preferable to use a water-based adhesive because the process can be simplified.

  The drying temperature is preferably 30 to 90 ° C. If it is less than 30 ° C., it takes a long time to dry, and there is a possibility that an appearance defect may occur. On the other hand, when the drying temperature exceeds 90 ° C., the polarizing performance of the polarizer may be deteriorated by heat. The drying time can be about 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

  By laminating the release film through a layer made of a volatile liquid on the polarizer, the heating temperature in this step can be increased to, for example, about 60 ° C. or more and 90 ° C. or less. That is, even if the heating temperature is set high, in addition to suppressing the breakage of the polarizer, the high-temperature heating can provide a single-side protective polarizing plate with a small contraction rate of the polarizer and thus high dimensional stability. . By reducing the shrinkage rate of the single-side protective polarizing plate, it is possible to further reduce the warpage of the liquid crystal panel when a liquid crystal panel is produced using the polarizing plate.

In order to volatilize the volatile liquid used for laminating 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 · 24 hr or more, 420 g / M ² · 24 hr or more is more preferable. If the moisture permeability is within this range, the volatile liquid can be efficiently volatilized and removed in the subsequent second step, so that productivity can be further improved.

  The release film is peeled off from the single-side protective polarizing plate, and the protective film 11 is bonded onto the polarizer 2 in the single-side protective polarizing plate via an adhesive layer. Further, by forming the pressure-sensitive adhesive layer 20 on the protective film 11, a front side polarizing plate composed of the pressure-sensitive adhesive layer 20 / protective film 11 / pressure-sensitive adhesive layer 21 / polarizer 2 / adhesive layer 30 / protective film 10 is obtained. It is done.

(Manufacturing method of back side polarizing plate)
By preparing the release film, the polarizer 2 and the protective film 12 by the same method as the method for producing the front side polarizing plate, and bonding the protective film 12 to one surface of the polarizer 2 via an adhesive, A release film is laminated on the other surface of the polarizer 2 via a volatile liquid. After the polarizer 2 and the protective film 12 are bonded and the volatile liquid is removed, the release film is peeled off to obtain a single-side protective polarizing plate.

  The brightness enhancement film 40 is laminated on the polarizer 2 in the single-sided protective polarizing plate via the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer 20 is laminated on the protective film 12, whereby the pressure-sensitive adhesive layer 20 / protective film 12 / adhesion. The back side polarizing plate which consists of the agent layer 32 / polarizer 2 / adhesive layer 21 / brightness improvement film 40 is obtained.

  The shape of the polarizing plate of the present invention is not particularly limited, but may be a rectangle or a rectangle having a long side and a short side. When a polarizing plate is manufactured by a 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.

(Liquid crystal panel manufacturing method)
A liquid crystal panel can be obtained by bonding the set of polarizing plates of the present invention to both surfaces of the liquid crystal cell. Bonding is preferably performed via the pressure-sensitive adhesive layer of the front-side polarizing plate and the pressure-sensitive adhesive layer of the back-side polarizing plate, respectively. Moreover, it is preferable that a front side polarizing plate is laminated | stacked on the visual recognition side of a liquid crystal cell, and a back side polarizing plate is laminated | stacked on the back side of a 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 bonded so that its absorption axis is substantially parallel to the short side direction of the liquid crystal cell, and the back side polarizing plate has its absorption axis substantially parallel to the long side direction of the liquid crystal cell. It is preferable to bond so that it may become. In the present specification, “substantially parallel” means, for example, that the angle formed is 0 ± 5 °, preferably 0 ± 1 °.

  The liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between the substrates. In general, the cell substrate is often made of glass, but may be a plastic substrate. In addition, the liquid crystal cell itself used in the liquid crystal panel of the present invention can be composed of various types employed in this field. According to the set of polarizing plates of the present invention, even when 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.

  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) Tensile modulus A test piece having a width of 15 mm and a length of 150 mm was cut out from the film. Next, with the upper and lower grips of a tensile tester [manufactured by Shimadzu Corporation AUTOGRAPH (registered trademark) AG-1S tester] equipped with a thermostat, the long side direction of the test piece is set so that the distance between the grips becomes 100 mm. The both ends were sandwiched and pulled at a tensile rate of 50 mm / min in an environment of 85 ° C., a stress-strain curve was created, and the tensile modulus at 85 ° C. was calculated.

(3) Water vapor transmission rate The water vapor transmission rate was measured based on JISZ0208. The temperature and humidity conditions were 40 degrees and 90% RH.

(4) Discrimination of polarizing plate warped in convex shape and measurement of warpage amount under high temperature environment An evaluation sample having a configuration of rear side polarizing plate / glass plate / front side polarizing plate was placed in an environment of 85 ° C. After leaving still for 250 hours, it put on the measuring stand of a two-dimensional measuring device with the front side polarizing plate facing up. As the two-dimensional measuring instrument, “NEXIV (registered trademark) VMR-12072” manufactured by Nikon Corporation was used. Next, the surface of the measurement table was focused, and the height from the reference focal point was measured by focusing on 25 points on the evaluation sample surface. The difference between the maximum and minimum heights at 25 measurement points is taken as the amount of warpage, and the warpage of the evaluation sample on the front side polarizing plate side is added to the front side polarizing plate. The warp of the sample warp was regarded as a negative warp. In the case of a positive warp, the polarizing plate on the side warping the convex shape is a back side polarizing plate, and in the case of a negative warping, the polarizing plate on the side warping the convex shape is a front side polarizing plate.

  Specifically, the point 80 shown in FIG. The 25 points shown in FIG. 4 are points in a region 7 mm inside from the end of the polarizing plate, and the short side direction is provided at intervals of about 20 mm, and the long side direction is provided at intervals of about 35 mm. Moreover, in FIG. 4, the code | symbol 402 shows a polarizing plate and 70 shows a glass plate.

[Production Example 1] Production of polarizer A 20 μm-thick polyvinyl alcohol film (average polymerization degree of about 2400, saponification degree of 99.9 mol% or more) is uniaxially stretched about 4 times by dry stretching, and further maintained in a tension state. The sample was immersed in pure water at 40 ° C. for 40 seconds, and then immersed in an aqueous solution having an iodine / potassium iodide / water weight ratio of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds to perform a dyeing treatment. It was. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Subsequently, after washing with pure water at 8 ° C. for 15 seconds, the film is dried at 60 ° C. for 50 seconds and then at 75 ° C. for 20 seconds while being held at a tension of 300 N, and iodine is adsorbed and oriented on the polyvinyl alcohol film. A polarizer having a thickness of 7 μm was obtained.

[Production Example 2] Preparation of water-based adhesive 3 parts by weight of carboxyl group-modified polyvinyl alcohol [trade name “KL-318” obtained from Kuraray Co., Ltd.] was dissolved in 100 parts by weight of water, and a water-soluble epoxy was dissolved in the aqueous solution. 1.5 parts by weight of a resin-based polyamide epoxy additive [trade name “Smileise Resin (registered trademark) 650 (30)” obtained from Taoka Chemical Co., Ltd., aqueous solution with a solid content of 30 wt%] was added. A water-based adhesive was prepared.

[Protective films 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 film obtained by saponifying a triacetylcellulose film with a hard coat layer manufactured by Toppan Printing Co., Ltd. The thickness was 32 μm and the moisture permeability was 450 g / m ² · 24 hr.
Protective film B: ZT12. Cyclic polyolefin resin film made by ZEON Corporation. Thickness is 20 μm, manufactured by transverse uniaxial stretching.
Protective film C: Zerotack (registered trademark). A film obtained by saponifying a triacetyl cellulose film manufactured by Konica Minolta. The thickness was 20 μm.
Protective film D: ZF14-023. Cyclic polyolefin resin film made by ZEON Corporation. The thickness was 23 μm.
Release film E: Polymethyl methacrylate resin film manufactured by Sumitomo Chemical Co., Ltd. The thickness was 80 μm, and the water vapor transmission rate was 50 g / m ² · 24 hr.

[Example 1]
[Preparation of Front Side Polarizing Plate A]
The polarizer obtained in Production Example 1 was continuously conveyed, the protective film A was continuously unwound from the roll of the protective film A, and the release film E was continuously unwound from the roll of the release film E. Next, 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, passing through a bonding roll, and the protective film A / water-based adhesive / A laminated film composed of polarizer / pure water / release film E was used. Subsequently, the laminated film is transported and heated at 80 ° C. for 300 seconds in a drying oven to dry the water-based adhesive and volatilize and remove pure water interposed between the polarizer and the release film E. A single-sided protective polarizing plate with a release film was obtained. The release film E was peeled from the single-side protective polarizing plate with a release film to obtain a single-side protective polarizing plate.

  An adhesive layer [trade name “# L2” manufactured by Lintec Corporation] on the polarizer of the single-side protective polarizing plate. The thickness was 5 μm. ] Was further bonded onto the pressure-sensitive adhesive layer so that the stretching direction of the protective film B and the absorption axis direction of the polarizing plate were in the same direction. Thereafter, an adhesive layer on the protective film B [trade name “#KT” manufactured by Lintec Corporation. The thickness was 20 μm. ] Was pasted. Thus, the front side polarizing plate A which consists of protective film A / water-based adhesive layer / polarizer / adhesive layer / protective film B / adhesive layer was produced.

[Preparation of Rear Polarizing Plate D]
The polarizer obtained in Production Example 1 was continuously conveyed, the protective film C was continuously unwound from the roll of the protective film C, and the release film E was continuously unwound from the roll of the release film E. Next, 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, passing through a bonding roll, and the protective film C / water-based adhesive / A laminated film composed of polarizer / pure water / release film E was used. Subsequently, the laminated film is transported and heated at 80 ° C. for 300 seconds in a drying oven to dry the water-based adhesive and volatilize and remove pure water interposed between the polarizer and the release film E. A single-sided protective polarizing plate with a release film was obtained. The release film E was peeled from the single-side protective polarizing plate with a release film to obtain a single-side protective polarizing plate.

  A 15 μm thick acrylic adhesive (non-carrier film with a separator film manufactured by Lintec Co., Ltd.) is applied on the polarizer of the single-side protective polarizing plate, and a brightness enhancement film [trade name manufactured by 3M Co., Ltd. is formed on the adhesive layer. “Advanced Polarized Film, Version 3. Thickness was 26 μm.]) Was then bonded. Adhesive layer [trade name“ # K1 ”manufactured by Lintec Co., Ltd., thickness was 15 μm. In this way, a back side polarizing plate D composed of a brightness enhancement film / pressure-sensitive adhesive layer / polarizer / water-based adhesive layer / protective film C / pressure-sensitive adhesive layer was produced.

[Preparation of sample for evaluation]
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 rear-side polarizing plate D is 155.25 μm in the absorption axis direction and 95.90 mm in the transmission axis direction. Cut into a rectangular shape. Next, a glass plate having a thickness of 0.4 mm (manufactured by Corning, product number: EAGLE XG (registered trademark)) is prepared, and the absorption axis of the front-side polarizing plate and the absorption axis of the rear-side polarizing plate are orthogonal to each other. The front-side polarizing plate and the rear-side polarizing plate were bonded to the glass plate via the respective adhesive layers.

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

[Example 2]
The protective film B was prepared in the same manner as the front polarizing plate A except that the protective film B was changed to the protective film D, and consisted of protective film A / aqueous adhesive layer / polarizer / adhesive layer / protective film D / adhesive layer. A front side polarizing plate B was prepared.
About the back side polarizing plate, the back side polarizing plate D used in Example 1 was used. And the sample for evaluation was produced like Example 1 except having changed the front side polarizing plate A into the front side polarizing plate B of a present Example.

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

[Comparative Example 1]
The protective film A / water-based adhesive layer / polarizer was prepared in the same manner as the front-side polarizing plate A except that the stretching direction of the protective film B and the transmission axis direction of the polarizing plate were bonded in the same direction. A front-side polarizing plate C composed of / adhesive layer / protective film B / adhesive layer was produced.
About the back side polarizing plate, the back side polarizing plate D used in Example 1 was used. And the sample for evaluation was produced like Example 1 except having changed the front side polarizing plate A into the front side polarizing plate C of a present Example.

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

  As shown in Table 1, when the tensile elastic modulus Et, Ea of the protective film in the polarizing plate on the convex warping side satisfies Ea / Et ≧ 0.95, the amount of warpage in a high temperature environment can be reduced. It was.

  According to the set of polarizing plates of the present invention, warpage of the liquid crystal panel in a high temperature environment can be reduced, which is useful.

2 Polarizer 10, 11, 12 Protective film 20, 21, 22 Adhesive layer 30, 31, 32 Adhesive layer 40 Brightness enhancement film 402 Polarizing plate 100, 101, 400 Front side polarizing plate 200, 201, 401 Back side polarizing Plate 300 Liquid crystal cell 70 Glass plate 80 Measurement point

Claims (4)

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,
A laminate in which the front side polarizing plate and the rear side polarizing plate are bonded to a glass plate so that the absorption axis of the front side polarizing plate and the absorption axis of the rear side polarizing plate are orthogonal to each other, When heated at 250 ° C. for at least one of the protective films in the polarizing plate on which the laminate warps, the tensile modulus in the polarizing plate transmission axis direction at 85 ° C. and the polarizing plate absorption at 85 ° C. A set of polarizing plates satisfying the following formula (1) when the tensile modulus in the axial direction is Et and Ea, respectively.
Ea / Et ≧ 0.95 (1) 2. The set of polarizing plates according to claim 1, wherein each of the front side polarizing plate and the rear side polarizing plate has a polarizer made of a polyvinyl alcohol-based resin film, and the thickness of each of the polarizers is 15 μm or less. . The set of polarizing plates according to claim 1 or 2, wherein the difference between the thickness of the polarizer provided for the front side polarizing plate and the thickness of the polarizer provided for the back side polarizing plate is 5 µm or less. A liquid crystal panel comprising the set of polarizing plates according to claim 1 and a liquid crystal cell, wherein the liquid crystal cell has a thickness of 0.4 mm or less.

Images