TW201816435A - Polarizing plate set and liquid crystal panel - Google Patents

Abstract

The present invention provides a polarizing plate set capable of reducing warping of liquid crystal panel in high temperature environments. The polarizing plate set comprises a front side polarizing plate disposed on the viewing side of a 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 back side polarizing plate are orthogonal to each other is heated at 85 DEG C for 250 hours, and a tensile elastic modulus in the polarizing plate transmission axis direction at 85 DEG C and a tensile elastic modulus in the polarizing plate absorption axis direction at 85 DEG C are taken as Et and Ea, respectively, the protective film in the polarizing plate on the side where the laminate is warped in a concave shape satisfies Ea, Et/Ea ≥ 1.1.

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 has characteristics such as low power consumption, low voltage operation, light weight and thinness, and can be used for various display elements. A liquid crystal panel constituting a liquid crystal display device has a structure in which a pair of polarizing plates are laminated on both sides of a liquid crystal cell.

The method proposed in Japanese Patent Application Laid-Open No. 2013-37115 (Reference 1) is to make the polarizing film contained in the front side of the optical laminate more than the polarizing film contained in the optical laminate disposed on the side opposite to the front side. The thickness is 5 μm or more, and the polarizing film and the reflective polarizing film included in the optical laminated layer disposed on the side opposite to the front side are laminated to prevent warping of the liquid crystal panel under a high temperature environment. These methods are effective when a large-thickness (for example, 0.5 mm or more, and more than 0.7 mm) liquid crystal cell is used, and a large-thickness (for example, 50 μm or more) reflective polarizing film is used. However, in addition to the thinner and thinner components that make up polarizing plates today, it is not sufficient for thin liquid crystal cells to prevent warping of liquid crystal panels under high temperature environments.

    [Prior technical literature]         [Patent Literature]    

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

An object of the present invention is to provide a set of polarizing plates, which can reduce the warpage of a liquid crystal panel under a high temperature environment.

[1] A set of polarizing plates, comprising a polarizing plate disposed on a front side of a viewing side of a liquid crystal cell and a polarizing plate disposed on a rear side of the liquid crystal cell; The absorption axis of the back-side polarizing plate is orthogonal. The laminated body obtained by bonding the front-side polarizing plate and the back-side polarizing plate to a glass plate. When heated at 85 ° C for 250 hours, the 85 ° C polarizing plate penetrates the axis direction. When the tensile elastic modulus and the tensile elastic modulus in the absorption axis direction of the polarizing plate at 85 ° C are respectively set to Et and Ea, the protective film of the polarizing plate on the side where the laminated body is warped into a concave shape satisfies the following (1) .

Et / Ea ≧ 1.1 (1)

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

[3] The set of polarizing plates according to item [2], wherein the front-side polarizing plate includes a hardened layer of an active energy ray-curable resin composition on at least one side of the polarizer.

[4] The set of polarizing plates according to [2] or [3], wherein the front-side polarizing plate is provided with a protective film on one side of the polarizer and an active energy ray-curable resin on the other side Hardened layer of composition.

[5] The set of polarizing plates according to any one of [2] to [4], wherein the thickness of the polarizing plate provided on the front-side polarizing plate and the polarizing plate provided on the rear-side polarizing plate The difference in thickness is 5 μm or less.

[6] A liquid crystal panel including the polarizing plate set according to any one of [1] to [5], and a liquid crystal cell, wherein the thickness of the liquid crystal panel is 0.4 mm or less.

If the polarizing plate set of the present invention is used, the warpage of the liquid crystal panel under a high temperature environment can be reduced.

1‧‧‧hardened layer

2‧‧‧ polarizer

10, 11‧‧‧ protective film

20, 21‧‧‧ Adhesive layer

30, 31‧‧‧ Adhesive layer

40‧‧‧Brightness improving film

70‧‧‧ glass plate

80‧‧‧Measurement point

402‧‧‧polarizing plate

100, 101, 400‧‧‧ front side polarizer

200, 201, 401‧‧‧ back side polarizer

300‧‧‧LCD unit

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-section of the evaluation sample after heat treatment.

Fig. 4 is a plan view showing the position after measuring the amount of warpage of the evaluation sample.

A set of a polarizing plate and a 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 includes a front-side polarizing plate arranged on the observation side of the liquid crystal cell and a back-side polarizing plate arranged on the back 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 a protective film 10 laminated on one side of the polarizer 2 through the adhesive layer 30, and an active energy ray-curable adhesive layer 1 is layered on the other area of the polarizer 2. An adhesive layer 20 is laminated on the hardened layer 1.

The back-side polarizing plate 200 is formed by laminating the protective film 11 through the adhesive layer 31 on one side of the polarizer 2, and laminating the brightness improving film 40 through the adhesive layer 21 on the protective film 11. An adhesive layer 20 is further formed on the other area of the polarizer 2.

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 a protective film 10 laminated on one side of the polarizer 2 through the adhesive layer 30, and an active energy ray-curable adhesive layer 1 is layered on the other area of the polarizer 2. An adhesive layer 20 is laminated on the hardened layer 1.

The back side polarizing plate 201 is a protective film 11 laminated on one side of the polarizer 2 through the adhesive layer 31, and a brightness improving film 40 is laminated on the other side of the polarizer 2 through the adhesive layer 21. An adhesive layer 20 is laminated on the protective film 11.

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

In the set of polarizing plates of the present invention, it is preferable that the front side polarizing plate and the back side polarizing plate have a protective film on only one side of the polarizer.

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 rectangular, 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 the polarizing plate of the present invention, when the laminated body including the front-side polarizing plate and the back-side polarizing plate is heated, the tensile elasticity of the polarizing plate in the direction of the penetrating axis of the polarizing plate at 85 ° C and at 85 ° C When the tensile elastic modulus in the absorption axis direction of the polarizing plate is Et and Ea, respectively, the protective film of the polarizing plate having a side warped into a concave shape satisfies the following (1). The tensile elastic modulus can be measured by the method described in Examples described later.

Et / Ea ≧ 1.1 (1)

Et / Ea is more preferably 1.15 or more, and more preferably 1.20 or more. Et / Ea may be 2.8 or less.

When the edge of the laminated body is warped toward the front polarizing plate side, the polarizing plate warped to the concave side is the front side polarizing plate, and when the edge of the laminated body is warped toward the back polarizing plate side, it is warped into the concave shape. The polarizing plate on the side is a polarizing plate on the back side. Specifically, it can be described with reference to FIG. 3. FIG. 3 is a schematic cross-section of a laminated body obtained by bonding the front-side polarizing plate 400 and the back-side polarizing plate 401 to the glass plate 70, respectively, after heat treatment. In Fig. 3 (a), the polarizing plate warped on the side is referred to as the back side polarizing plate 401, and in Fig. 3 (b), the polarizing plate warped on the side is referred to as the front side polarizing plate. 400. The polarizing plate on the side warped into the concave shape may be a front-side polarizing plate or a back-side polarizing plate. Since the back side polarizing plate has a brightness improving film that has also been stretched in addition to the polarizing plate that has been stretched, the back side polarizing plate is formed when the absorption axis direction of the back side polarizing plate is set to the long side direction. The shrinkage force during heating is often greater than that of the front-side polarizing plate.

Although the shape of the polarizing plate and the shape of the glass plate when bonded to the glass plate are not particularly limited, a rectangular shape is preferred. In this case, the front polarizing plate and the back polarizing plate can be made the same size. When the polarizing plate is bonded to the glass plate, the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate are bonded orthogonally. At this time, when the polarizing plate is rectangular, 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 to 400 μm. When the thickness is in this range, it is easy to determine which of the front-side polarizing plate and the back-side polarizing plate is a polarizing plate warped on the side.

The polarizing plate on the warped side may have protective films on both sides of the polarizer. In this case, it is better that at least one of the protective films satisfies the formula (1), and the liquid crystal cell laminated on the polarizer is more suitable. It is more preferable that the protective film on the far side satisfies the formula (1), and it is more preferable that any protective film satisfy the formula (1).

The tensile elastic modulus Et at the penetration axis direction at 85 ° C is preferably 500 MPa to 10,000 MPa, and may be 1,000 MPa to 8,000 MPa. The tensile elastic modulus Ea in the absorption axis direction at 85 ° C is preferably 500 MPa to 10,000 MPa, and may be 1,000 MPa to 8,000 MPa.

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

(Polarizer)

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

As the polyvinyl alcohol-based resin film, a polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include copolymers of vinyl acetate and other copolymerizable monomers, in addition to polyvinyl acetate, which is a homopolymer of 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%, and preferably 98 mol% or more. This polyvinyl alcohol-based resin can also be modified, and for example, polyvinyl aldehyde or polyvinyl acetaldehyde modified by aldehydes can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

As a raw material film of a polarizer, the thing obtained by making a polyvinyl alcohol-type resin into a film can be used. The method for forming a polyvinyl alcohol-based resin into a film can be performed by a known method. When considering the thickness of the polyvinyl alcohol-based raw material film so that the thickness of the obtained polarizer becomes 15 μm or less, it 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 m or more, it is necessary to increase the draw ratio at the time of manufacturing the polarizer, and the size shrinkage of the obtained polarizer tends to be large.

On the other hand, when the film thickness of the raw material film is 5 μm or less, the handleability at the time of application of stretching tends to decrease, and problems such as cutting during production tend to occur.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before the dyeing of the dichroic pigment, simultaneously with the dyeing, or after the dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during a boric acid treatment. It is also possible to perform uniaxial stretching at several stages of these processes.

For uniaxial stretching, uniaxial stretching can be performed between rollers with different peripheral speeds, or uniaxial stretching can be performed using hot rollers. The uniaxial stretching may be dry stretching in the air, or wet stretching using a solvent to stretch the polyvinyl alcohol-based resin film in an expanded state. 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. As the dichroic pigment, specifically, iodine or a dichroic dye can be used. The polyvinyl alcohol-based resin film is preferably an immersion treatment in water before the dyeing treatment.

When using iodine as a dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide can be generally used. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of the water system. 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.

The time (dyeing time) for immersion in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye can be generally used. The content of the dichroic dye in the 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 aid. The temperature of the dichroic dye aqueous solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dichroic dyeing is usually 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, and preferably 5 to 12 parts by weight per 100 parts by weight of water. When using iodine as a 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 5 to 12 parts by weight, per 100 parts by weight of water. The time for immersion in an aqueous solution containing boric acid 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 aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

The polyethylene-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be performed by, for example, immersing the polyethylene resin film after the boric acid treatment in water. The temperature of the water in 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 and applying a drying treatment, a polarizer is obtained. 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 drying time is usually about 60 to 600 seconds, and preferably 120 to 600 seconds.

After drying, the moisture content of the polarizer can be reduced to a practical level. The moisture content is usually 5 to 20% by weight, and preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the polarizer may lose flexibility, and the polarizer may be damaged or broken after drying.

When the moisture content is higher than 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 process of manufacturing the polarizer can be performed according to, for example, the method described in Japanese Patent Application Laid-Open No. 2012-159778. In the method described in this document, a polyvinyl alcohol-based resin layer is formed as a polarizer by applying a polyvinyl alcohol-based resin to a base film.

Reducing the shrinkage force of the polarizer itself is also effective for reducing warping in a high temperature environment. The thickness of a polarizer having a front-side polarizer and a back-side polarizer is preferably 15 μm or less, and more preferably 4 to 13 μm. It is better, and more preferably 5 to 10 μm.

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 preferably 5 μm or less, and may be 3 μm or less. When the protective film of the polarizing plate warped to the concave side satisfies the formula (1), the thickness difference of the polarizer can be reduced as described above, and the influence on the warpage of the liquid crystal panel under a high temperature environment becomes smaller.

(Protective film)

The protective film is made of a resin film, and may be made of a transparent resin film. In particular, it is preferable to have a material composition excellent in transparency, mechanical strength, thermal stability, and moisture shielding property. The transparent resin film in this specification refers to a resin film having a monomer transmittance of 80% or more in the visible light domain.

When the two-area protective film of the polarizer is used, the protective film may be the same as each other or may be different from each other. The protective film in the front-side polarizing plate and the protective film in 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, and styrene resin. , Acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate Ester based resin, modified polyphenylene ether based resin, polybutylene terephthalate based resin, polyethylene terephthalate based resin, polyfluorene based resin, polyether based resin, polyarylate based resin , Polyimide resin and polyimide resin.

These resins can be used alone or in combination of two or more. In addition, these resins can also be used after any suitable polymer modification. Examples of such polymer modification include copolymerization, cross-linking, molecular terminal modification, stereoregularity control, and reaction with each other with heterogeneous polymers. Modification of time, etc.

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-based resin referred to here includes a chain-shaped polyolefin-based resin and a cyclic polyolefin-based resin.

The methyl methacrylate resin refers to a polymer containing 50% by weight or more of methyl methacrylate units. The content of the methyl methacrylate unit is preferably 70% by weight or more, and may 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. It can also coexist with polyfunctional monomers or chain transfer agents during polymerization as needed.

The monofunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methyl 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; methyl 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 bromobenzene Halogenated styrenes such as ethylene; substituted styrenes such as ethylene toluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; As well as phenyl-cis-butene diimide and cyclohexyl-cis-butyl Unsaturated fluorene imines such as enediimides and the like. These monomers can be used individually or in combination of 2 or more types.

The polyfunctional monomer copolymerizable with methyl methacrylate is not particularly limited, and examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol 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; alkylene oxide addition of bisphenol A and bisphenol A Products, or these two halogen-substituted products are esterified with acrylic acid or methacrylic acid; polymethyl alcohols such as trimethylolpropane and isopentyl alcohol are esterified with acrylic acid or methacrylic acid; The terminal hydroxyl group of the alcohol is added through the ring opening of the dehydroglyceryl acrylate or the glyceryl methacrylate. Those; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, these halogen substitutes, and these alkylene oxide adducts, etc. Dehydroglyceride epoxy group ring-opening and addition; allyl (meth) acrylate; and aromatic diethylene compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The methyl methacrylate resin can be further modified by a reaction between functional groups that have been copolymerized with 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. Dehydrogenation condensation reaction of the hydroxyl group of the ester in the polymer chain.

Polyethylene terephthalate resin means that more than 80 mol (mol)% of repeating units are resins composed of ethylene terephthalate, and may contain other dicarboxylic acid components and glycols. ingredient. Other dicarboxylic acid components are not particularly limited, and examples thereof include isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, and bis (4-carboxybenzene Group), ethane, adipic acid, sebacic acid, and 1,4-dicarboxycyclohexane.

The 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, and polyethylene glycol. Alcohol, polypropylene glycol and polybutylene glycol.

These dicarboxylic acid components or diol components may be used in combination of two or more kinds as necessary. Further, 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.

As a method for producing a polyethylene terephthalate resin, a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as necessary) can be adopted, and Method for polycondensing a dialkyl ester of dicarboxylic acid and ethylene glycol (and other dialkyl esters of dicarboxylic acid or other diols as needed) after transesterification, and terephthalic acid (and optionally A method of polycondensing ethylene glycol esters of other dicarboxylic acids (and other diol esters as needed) in the presence of a catalyst. In addition, if necessary, solid-phase polymerization may be performed to increase the molecular weight or decrease the low molecular weight component.

The cyclic polyolefin resin is obtained 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 resin is preferred because it is easy to obtain a protective film having a predetermined retardation value described later.

Examples of the cyclic polyolefin-based resin include a ring-opening method in which a norbornene or a derivative thereof obtained by a Diels-Alder reaction of cyclopentadiene and an olefin or (meth) acrylic acid or an ester thereof is used as a monomer. Resin obtained by metathesis polymerization followed by hydrogenation; tetracyclododecene or its derivative obtained by the reaction of dicyclopentadiene with olefins or (meth) acrylic acid or its esters by Diels-Alder as Resin obtained by ring-opening metathesis polymerization of monomers followed by hydrogenation; at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof, and other cyclic olefin monomers Resin obtained by ring-opening metathesis copolymerization followed by hydrogenation; cyclic olefins such as norbornene, tetracyclododecene or derivatives thereof are added with chain olefins and / or aromatic compounds with vinyl groups. Copolymerized resin and the like.

Typical examples of the chain polyolefin resin are a polyethylene resin and a polypropylene resin. Among them, a homopolymer of propylene, or propylene as a main body, and a copolymerizable comonomer, such as ethylene, are copolymerized at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight. Copolymers are suitable.

The polyolefin-based resin may contain an alicyclic saturated hydrocarbon resin. By containing an alicyclic saturated hydrocarbon resin, the retardation value can be easily controlled. The content of the alicyclic saturated hydrocarbon resin is preferably 0.1 to 30% by weight based on the polyolefin resin, and the preferred content is 3 to 20% by weight. If 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, if the content exceeds 30% by weight, the alicyclic saturation exudates from the protective film over time. Concerns about hydrocarbon resins.

Cellulose resin refers to some or all of the hydrogen atoms in the hydroxyl groups of cellulose that can be obtained from cellulose such as cotton wool or wood pulp (broadleaf pulp, coniferous pulp), etc. via ethyl, propyl, and / or butyl Substituted cellulose organic acid esters or cellulose organic acid esters. Examples thereof include those formed from cellulose acetate, propionate, butyrate, and mixed esters thereof. Among them, a triethylfluorene-based cellulose film, a diethylfluorene-based cellulose film, a cellulose acetate propionate film, and a cellulose acetate butyrate film are preferred.

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 a polarizer, as long as it is appropriately selected and compounded The method of the resin is not particularly limited. For example, a solvent casting method in which a resin dissolved in a solvent is cast toward a metal belt or drum, and the solvent is dried and removed to obtain a film, and the resin is heated and kneaded above its melting temperature, extruded from a die, and Cooling to obtain a melt extrusion method of the film. In this melt extrusion method, it may be the extrusion of a single-layer film or the simultaneous extrusion of a multilayer film.

Commercially available products can be easily obtained by using a film as a protective film. For methyl methacrylate resin films, the trade names are Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite (registered trademark), and ACRYPREN. (Registered trademark) (above, made by Mitsubishi Rayon Co. Ltd.), Delaglas (registered trademark) (made by Asahi Kasei Corporation), Paragras (registered trademark), Comograss (registered trademark) (above, Kuraray Co., Ltd.) and Acryviewa (registered trademark) (Japan Catalyst Co., Ltd.). In the case of polyolefin resin films, the trade names are Zeonor (registered trademark) (Japanese Zeon Corporation), Arton (registered trademark) (JSR Corporation), and the like. For polyethylene terephthalate resins, the trade names are Nova Clear (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemicals Co., Ltd.). . For polypropylene-based resin films, the product names that can be cited are FILMAX CPP film (made by FILMAX), SUNTOX (registered trademark) (manufactured by SUN / TOX Co., Ltd.), and Tohcello (registered trademark) (Tocello Co., Ltd.) System), Toyobo Piren Film (registered trademark) (manufactured by Toyobo Co., Ltd.), Torayfan (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), Japan Poriesu (manufactured by Japan Poriesu Co., Ltd.), and Taihe (registered trademark) FC (Futamura Chemical Co., Ltd.) and so on. In the case of a cellulose-based resin film, the trade names are Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA, Konica Minolta TAC Film KC (manufactured by Konica Minolta Co., Ltd.), etc. .

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. For example, a method in which inorganic fine particles or organic fine particles are mixed with the aforementioned raw resin and a film is formed. A method of forming a two-layer film with another resin that has not been mixed with fine particles, or a method of forming a three-layer film by using resin with mixed particles as an outer side, and mixing inorganic fine particles or organic fine particles with a hardening adhesive resin, A method for applying the prepared coating solution to one side of a film and curing the adhesive resin to provide an anti-glare layer.

Moreover, the protective film may contain an additive as needed. Examples of the additive include a slip agent, an anti-caking 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 generally about 1 to 50 μm, and preferably 10 to 40 μm in terms of strength, usability, and the like.

The protective film is preferably subjected to a saponification treatment, a corona treatment, or a plasma treatment before being bonded to the polarizer.

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

The protective film satisfying the formula (1) may be produced by, for example, extending a resin film. The stretching method is not particularly limited, and may be a uniaxially stretched film obtained by transversely stretching after film formation, a biaxially stretched film obtained by longitudinally stretching and then laterally stretching after filming, and the like. The stretching ratio can be made, for example, 1.01 to 5.00, or 1.01 to 3.00.

(Brightness improving film)

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

The brightness improving film is used as 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. Such a brightness improving film can use the re-regressive light from the backlight of reflected polarized light or scattered polarized light to improve the output efficiency of linearly polarized light.

Examples of the brightness improving film include an anisotropic reflective polarizer. Examples of the anisotropic reflective polarizer include an anisotropic multiple film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. Examples of the anisotropic multilayer film include the trade name "APF" manufactured by 3M Corporation. Examples of the anisotropic reflective polarizer include a composite of a cholesteric liquid crystal layer and a λ / 4 plate. Examples of such a compound include the trade name "PCF" manufactured by Nitto Denko Corporation. Examples of the anisotropic reflective polarizer include a reflective grating polarizer. Examples of the reflective grating polarizer include a metal lattice reflective polarizer that performs fine processing on a metal and emits reflective polarized light even in the visible light region. Among them, a brightness improving film formed of an anisotropic multiple thin film is preferred.

A functional layer may be formed on the surface opposite to the adhesion surface of the polarizing plate of the brightness improving film. Examples of the functional layer include a hard coating layer, an anti-glare layer, a light diffusing layer, and a retardation layer having a retardation value of 1/4 wavelength. Based on this, it is possible to improve the adhesion to the backlight or display. The uniformity of the image.

(Adhesive layer)

An adhesive layer may also be laminated on the surface of the polarizing plate. The polarizing plate can be adhered to the liquid crystal cell through the adhesive layer. The adhesive layer 20 in FIG. 1 corresponds to this layer.

The thickness of the adhesive layer formed from 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.

The brightness improving film and the protective film or polarizer may be laminated by an adhesive layer. The adhesive layer 21 in FIG. 1 corresponds to this layer. 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, Modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other polymers are used as matrix polymers. The adhesive is particularly preferably one which is excellent in optical transparency, exhibits moderate wettability, cohesiveness, adhesion characteristics such as weather resistance, and heat resistance.

Various other additives can also 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 or the lamination of the brightness improving film and the polarizer can be performed by, for example, a method of integrating them with 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 even more preferably 0.01 to 5 μm. As long as it is within this range, it is possible to prevent floating or peeling between the protective film or the brightness-improving film and the polarizer, and to obtain a practically problem-free adhesive force.

Examples of the adhesive include a solvent-based adhesive, an emulsion-based adhesive, a pressure-sensitive adhesive, a re-wettable adhesive, a polycondensation-based adhesive, a solventless adhesive, a film-shaped adhesive, and a hot-melt adhesive. If necessary, an adhesive layer may be provided through the anchor coating.

Preferable adhesives include water-soluble adhesives. The water-soluble adhesive is, for example, a polyvinyl alcohol resin as a main component. A commercially available water-soluble adhesive may be used, or a solvent or an additive mixed with a commercially available adhesive may be used. Commercially available polyvinyl alcohol-based resins for water-soluble adhesives include, for example, KL-318 manufactured by Kuraray Co., Ltd. and the like.

The water-soluble adhesive may contain a crosslinking agent. The type of the crosslinking agent is preferably an amine compound, an aldehyde compound, a trimethylol compound, an epoxy compound, an isocyanate compound, a polyvalent metal salt, and the like, and an epoxy compound is particularly preferred. Commercially available products of the crosslinking agent include, for example, glyoxal or Sumirez resin 650 (30) manufactured by Taoka Chemical Industry Co., Ltd., and the like.

Moreover, as another preferable adhesive agent, the active energy ray hardening type adhesive agent formed from the resin composition hardened | cured by irradiation of active energy ray is mentioned. Examples of the active energy ray-curable adhesive include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, those containing a binder resin, and a photoreactive crosslinking agent. Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, a photocurable amine ester monomer, or an oligomer derived from the photopolymerizable monomer. . Examples of the photopolymerization initiator include substances containing active species such as radicals, cations, or anions by irradiation with active energy rays 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 adhered, a drying step may be performed as necessary, and then a step of hardening the active energy ray-curable adhesive by irradiating the active energy ray is performed. Although there is no particular limitation on the light source of the active energy ray, it is preferable to use ultraviolet light with 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 lights, microwave Excite mercury lamps, metal halide lamps, etc.

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

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

The hardened layer of the active energy ray-curable resin composition can be used as a protective layer for protecting the surface of a polarizer. The hardened layer of the active energy ray-curable resin composition is thinner than a general protective film, and is therefore effective for reducing the thickness of a polarizing plate. The hardened layer 1 of the active energy ray-curable resin composition in FIG. 1 corresponds to this.

In the polarizing plate set of the present invention, the polarizing plate (especially the front-side polarizing plate) is preferably a hardened layer having an active energy ray-curable resin composition on at least one side of the polarizer, and the polarizer is near the liquid crystal cell It is more preferable to have a hardened layer of an active energy ray-curable resin composition on the side. In this case, since the distance between the polarizer and the liquid crystal cell can be made smaller, the force for deforming the liquid crystal cell accompanying the shrinkage of the polarizer becomes smaller, and the influence on the warpage of the liquid crystal panel in a high-temperature environment is smaller. In this regard, the distance from the surface of the polarizer liquid crystal cell near the front-side polarizer to the surface of the liquid crystal cell near the polarizer near the front-side polarizer is preferably 30 μm or less, and 25 μm or less. Better.

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 even 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 each other or different from each other.

(Manufacturing method of polarizing plate)

The members described above can be laminated and bonded to each other through, for example, an adhesive layer or an adhesive layer. A method of manufacturing a polarizing plate using a release film may also be adopted.

Hereinafter, a method of manufacturing a front-side polarizing plate and a back-side polarizing plate constituting the polarizing plate of the present invention will be described using the 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 adhered through an adhesive on one side of the polarizer, and a volatile liquid is transmitted on the other side of the polarizer to laminate the release film. Of course, the adhesion of the protective film and the polarizer and the lamination of the release film and the polarizer can also be performed sequentially in order.

Examples of the volatile liquid include water or a mixture of water and a hydrophilic liquid. The hydrophilic liquid system is preferably one that does not remain after the heat treatment in the second step. Examples include methanol, ethanol, 1-butanol, tetrahydrofuran, acetone, acetonitrile, N, N-dimethylformamide, and dimethyl. Hydrazone, formic acid, acetic acid, etc. Additives such as antistatic agents can also be added to the volatile liquid.

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, and styrene resin. , Acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate Ester based resin, modified polyphenylene ether based resin, polybutylene terephthalate based resin, polyethylene terephthalate based resin, polyfluorene based resin, polyether based resin, polyarylate based resin , Polyimide resin and polyimide resin.

When the protective film is bonded to the polarizer, in order to improve the adhesion, the bonding surface of the polarizer and / or the protective film may be subjected to, for example, plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment. Easy to handle next. In addition, the same treatment as that of the protective film for the release film can be used to improve the wettability of the volatile liquid.

When an active energy ray hardening type adhesive is used as the adhesive, the adhesive is hardened by irradiating the active energy ray, followed by heat treatment to volatilize and remove the volatile liquid. When an aqueous adhesive is used as the adhesive, the polarizing plate and the protective film are adhered while being subjected to a heat treatment, and the volatile liquid is removed by evaporation. For the sake of simplicity, it is preferable to use an aqueous adhesive.

The drying temperature is preferably 30 to 90 ° C. If it is lower than 30 ° C, the drying time may be prolonged and the appearance may be poor. In addition, if the drying temperature exceeds 90 ° C, there is a concern that the polarization performance of the polarizer may be deteriorated due to heat. The drying time can be set to about 10 to 1,000 seconds. 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 the polarizer through a layer formed of a volatile liquid, the heating temperature in this step can be increased to, for example, more than 60 ° C. and less than 90 ° C. That is, by setting the heating temperature to a higher temperature, in addition to preventing the polarizer from cracking, the shrinkage of the polarizer can be reduced due to the high-temperature heating, thereby obtaining a single-sided protective polarizer with high dimensional stability. By reducing the shrinkage of the single-sided protective polarizing plate, warping of the liquid crystal panel can be further reduced when a liquid crystal panel is manufactured using the polarizing plate.

In order to volatilize the volatile liquid used in the laminate 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 for} 24 hours or more, and 420 g / m ² better than 24 hours When the moisture permeability 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.

An active energy ray-curable resin composition is coated on the base film so that the cured layer 1 of the active energy ray-curable resin composition is laminated on the polarizer 2. Next, the release film is peeled off from the single-sided protective polarizer, and the polarizer 2 in the single-sided protective polarizer and the active energy ray-curable resin composition on the base film are laminated. The active energy ray-curable resin composition is hardened by irradiating the active energy ray to form a hardened layer 1. The base film is peeled and removed to form an adhesive layer 20 on the hardened layer 1. The hardened layer 1 / polarizer 2 / adhesive layer 30 / protection of the adhesive layer 20 / active energy ray-curable resin composition can be obtained. The film 10 is formed with a front-surface-side polarizing plate.

(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 11 are prepared, the protective film is adhered to one side of the polarizer 2 through an adhesive, and the release film is passed through a volatile liquid. It is laminated on the other side of the polarizer 2. After the polarizer 2 and the protective film 11 were adhered and the volatile liquid was removed, the release film was peeled to obtain a single-sided protective polarizing plate.

The brightness improvement film is laminated on the protective film in the single-sided protective polarizing plate through the adhesive layer, and the adhesive layer 20 is laminated on the polarizer 2 to obtain the adhesive layer 20 / polarizer 2 / adhesive The back-side polarizing plate formed by the agent layer 31 / protective film 11 / adhesive layer 21 / brightness improving film 40.

The shape of the polarizing plate of the present invention is not particularly limited, and may be rectangular. When a polarizing plate is produced in a roll-to-roll manner, 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 adhering the sets of polarizing plates of the present invention to both sides of a liquid crystal cell, respectively. Adhesion is preferably performed through the adhesive layer of the front-side polarizing plate and the adhesive layer of the back-side polarizing plate. Further, it is preferable that the front-side polarizing plate-based layer is on the observation side of the liquid crystal cell, and the back-side polarizing plate-based layer is preferably on the back side of the liquid crystal cell. The liquid crystal panel of the present invention can be applied to a liquid crystal display device. The front-side polarizing plate is preferably adhered such that the absorption axis thereof is approximately parallel to the short-side direction of the liquid crystal cell, and the back-side polarizing plate is adhered such that the absorption axis thereof is approximately parallel to the long-side direction of the liquid crystal cell. good. "Approximately parallel" in this specification means, for example, that the angle formed is 0 ± 5 °, and preferably 0 ± 1 °.

The liquid crystal cell has two unit substrates and a liquid crystal layer held between the substrates. The unit substrate is usually 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 may be composed of various materials used in this field. With the set of polarizing plates of the present invention, even if the thickness of the liquid crystal cell is 0.4 mm or less, warpage can be significantly reduced. The thickness of the liquid crystal cell in the present invention is the thickness of a pair of substrates including a liquid crystal layer and a liquid crystal layer.

    [Example]    

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to the scope of these examples. In the examples, the contents and percentages used are% and parts. Unless otherwise specified, they are based on weight. 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 of the film. Next, hold the long side of the test piece with the upper and lower clamps of a tensile tester equipped with a thermostatic bath [AUTOGRAPH (registered trademark) AG-1S tester manufactured by Shimadzu Corporation) so that the gap between the clamps becomes 100 mm. Both ends in the direction were stretched at a tensile speed of 50 mm / min under an environment of 85 ° C, and a stress-strain curve was prepared to calculate a tensile elastic modulus at 85 ° C.

(3) Permeability

The moisture permeability was measured in accordance with JIS Z 0208. Temperature and humidity conditions are set to 40 degrees and 90% RH.

(4) Judgment of the polarizing plate warped to the concave side and measurement of the amount of warping in a high temperature environment

An evaluation sample having a configuration of a back-side polarizing plate, a glass plate, and a front-side polarizing plate was left to stand in an environment of 85 ° C. for 250 hours, and then the front-side polarizing plate was placed on the upper side and measured in a binary measuring device. On stage. The binary measuring instrument used "NEXIV (registered trademark) VMR-12072" manufactured by Nikon Corporation. Next, the surface of the measuring table was brought into focus, and this was used as a reference. The focus was set at 25 points on the sample surface for evaluation, and the height was measured from the focal point used as the reference. The difference between the maximum value and the minimum value of the heights of the 25 measurement points was used as the amount of warpage. The warpage of the edge warpage of the sample for evaluation on the front side polarizing plate was set to positive warpage, and the evaluation was performed on the side of the back side polarizing plate. The warpage using the edge warpage of the sample is set to negative warpage. In the case of positive warping, the polarizing plate on the side warped into a concave shape is a front side polarizing plate, and in the case of negative warping, the polarizing plate on the side warped into a concave shape is a back 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 in a field located 7 mm from the edge of the polarizer. The short side direction is set at about 20 mm intervals, and the long side direction is set at about 35 mm intervals. Note that reference numeral 402 in FIG. 4 indicates a polarizing plate, and 70 indicates a glass plate.

[Production Example 1] Production of Polarizer

Polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization of about 2,400, saponification degree of 99.9 mol% or more) was uniaxially stretched to about 4 times by dry stretching, and immersed at 40 ° C while maintaining a tight state After 40 seconds of pure water, the dyeing treatment was performed by immersion in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C for 30 seconds. Then, 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. Next, it was washed with pure water at 8 ° C for 15 seconds, and was maintained at a tension of 300N, dried at 60 ° C for 50 seconds, and then dried at 75 ° C for 20 seconds to obtain a directional iodine adsorbed in a polyvinyl alcohol film. A 7 μm-thick polarizer.

[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 polyamine, which is a water-soluble epoxy resin, was added to this aqueous solution 1.5 parts by weight of an epoxy-based additive [trade name "Sumirez Resin Resin (registered trademark) 650 (30) purchased from Taoka Chemical Industry Co., Ltd., 30% by weight solid content]] was prepared as an aqueous adhesive.

[Production Example 3] Active energy ray-curable resin composition

50 parts by mass of an oxetane compound (bifunctional) (OXT221) as a polymer compound, 35 parts by mass of an alicyclic epoxy compound (bifunctional) (CEL2021P), and an aromatic epoxy compound (trifunctional) (TECHMORE 15 parts by mass of VG3101L and 2.25 parts by mass of triarylsulfonium hexafluorophosphate as a photocationic polymerization initiator were mixed to obtain an active energy ray-curable resin composition.

[Protective films A, B, C, D, E and release films F, G]

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

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

Protective film B: ZT12. Cyclic polyolefin resin film made by Japan Zeon Corporation. The thickness was 20 μm, and was obtained by extending the horizontal axis.

Protective film C: Zero Tack (registered trademark). Saponification membrane of triethylfluorinated cellulose membrane made by KONICA MINOLTA Co., Ltd. The thickness is 20 μm.

Protective film D: KC2UAW. Saponification membrane of triethylfluorinated cellulose membrane made by KONICA MINOLTA Co., Ltd. The thickness is 25 μm.

Protective film E: ZEONOR (registered trademark). Cyclic polyolefin resin film made by Japan Zeon Corporation. The thickness is 20 μm.

Release film F: TD80UL. Triethyl cellulose membrane made by Fujifilm Corporation. The thickness is 80 μm, and the moisture permeability is 502 g / m ² ‧ 24 hours.

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

[Example 1]

[Production of front side polarizing plate A]

The protective film A was continuously unwound from the roll of the protective film A while the polarizer obtained in Production Example 1 was continuously conveyed, and the release film G was continuously rolled up by the roll of the release film G. Next, an aqueous adhesive is injected between the polarizer and the protective film A, and pure water is also injected between the polarizer and the release film G, and the protective film A / water-based adhesive / polarizer / pure water / The laminated film formed by releasing the film G. Next, the laminated film was transported and subjected to a heating treatment in a drying oven at 80 ° C. for 300 seconds to dry the aqueous adhesive and evaporate and remove pure water between the polarizer and the release film G to obtain a single surface with a release film. Protect the polarizer. The release film G was peeled from the one-sided protective polarizer with a release film, and the one-sided protective polarizer was obtained.

On the other hand, an active energy ray-curable resin composition prepared in Production Example 3 was applied to one side of a cyclic polyolefin resin film [ZEONOR (registered trademark), manufactured by Japan Zeon Corporation] having a thickness of 50 μm, so that The cured film thickness was approximately 3 μm. A polarizer with the above-mentioned single-sided protective polarizer is adhered to this coating surface, and an ultraviolet irradiation device [the irradiation lamp is "D VALVE" manufactured by Fusion UV Systems] is used so that the cumulative light quantity from 280 to 320 nm becomes 200 mJ / cm ² The active ray-curable resin composition is hardened by irradiating ultraviolet rays from the cyclic polyolefin-based resin film side. The cyclic polyolefin resin film was peeled off, and a corona treatment was applied to the hardened layer of the active energy ray-curable resin composition. An adhesive layer [trade name "# KT" manufactured by Lintec Corporation. The thickness is 20 μm. 〕 Adhered to the hardened layer. In this way, the front-surface-side polarizing plate A was produced by the protective film A / water-based adhesive layer / polarizer / curing layer / active-ray-curable resin composition hardening layer / adhesive layer.

[Production of the back side polarizing plate B]

The polarizer obtained in Production Example 1 was continuously conveyed and the protective film B was continuously unwound from the roll of the protective film B, and the release film F was continuously rolled up by the roll of the release film F. Next, an aqueous adhesive was injected between the polarizer and the corona-treated protective film B, and pure water was injected between the polarizer and the release film F, and a protective film B / water-based adhesive / polarizer was prepared by an adhesive roller. / Pure water / laminated film formed by release film F. Next, the laminated film was transported and subjected to a heating treatment in a drying oven at 80 ° C. for 300 seconds to dry the aqueous adhesive and evaporate and remove pure water between the polarizer and the release film F to obtain a single surface with a release film. Protect the polarizer. The release film F was peeled from the one-sided protective polarizer with a release film, and the one-sided protective polarizer was obtained.

Adhesive layer [trade name "# L2" manufactured by Lintec Corporation. The thickness is 5 μm. ] Adhered to the protective film B of the single-sided protective polarizing plate, and a brightness improving film [trade name, manufactured by 3M Corporation] "Advanced Polarized Film, Version 3" was adhered to the adhesive layer. The thickness was 26 µm. ]]. Then, an adhesive layer [trade name "# KT" manufactured by Lintec Corporation. The thickness is 20 μm.] Was adhered to the polarizer. In this way, a brightness improving film / adhesive layer / protective film B / The back side polarizing plate B consisting of an aqueous adhesive layer, a polarizer, and an adhesive layer.

[Preparation of Evaluation Sample]

The front-side polarizing plate A was cut into a rectangular shape having a transmission axis direction of 155.25 mm and the absorption axis direction was 95.90 mm, and the back-side polarizing plate B was cut into a rectangular shape having an absorption axis direction of 155.25 μm and a transmission axis direction. Next, a glass plate (Corning Company model: EAGLE XG (registered trademark)) with a thickness of 0.4 mm was prepared, and the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate were orthogonal to each other. The front-side polarizing plate and the back-side polarizing plate are adhered to a glass plate through respective adhesive layers.

The obtained evaluation sample was measured for the amount of warpage in a high-temperature environment, and the results are shown in Table 1. The polarizing plate warped to the concave side is a back side polarizing plate, and the protective film B is a 85 ° C back side polarizing plate having a tensile elasticity of 2,190 MPa in the transmission axis direction. The tensile elasticity was 1,786 MPa.

[Example 2]

As the front-side polarizing plate, the front-side polarizing plate A used in Example 1 was used. The back-side polarizing plate is manufactured in the same manner as the back-side polarizing plate B except that the protective film B is changed to the protective film C and the release film F is changed to the release film G. A back side polarizing plate C composed of a brightness improving film / adhesive layer / protective film C / aqueous adhesive layer / polarizer / adhesive layer. Then, the same procedure as in Example 1 was performed except that the back-side polarizing plate B was changed to the back-side polarizing plate C of the embodiment to prepare a sample for evaluation.

The obtained evaluation sample was measured for the amount of warpage in a high-temperature environment, and the results are shown in Table 1. The polarizing plate warped to the concave side is a back side polarizing plate, and the protective film C is a 85 ° C back side polarizing plate having a tensile elasticity of 3,260 MPa in the transmission axis direction. The tensile elastic modulus was 2,890 MPa.

[Example 3]

As the front-side polarizing plate, the front-side polarizing plate A used in Example 1 was used. The rear-side polarizing plate is made in the production of the back-side polarizing plate C. Except that the protective film C is changed to the protective film D, the rest is made in the same manner as the back-side polarizing plate C, and is made of a brightness improving film / adhesive layer / The back side polarizing plate D consisting of the protective film D / water-based adhesive layer / polarizer / adhesive layer. Then, the same procedure as in Example 1 was performed except that the back-side polarizing plate B was changed to the back-side polarizing plate D of the embodiment, to prepare a sample for evaluation.

The obtained evaluation sample was measured for the amount of warpage in a high-temperature environment, and the results are shown in Table 1. The polarizing plate warped to the concave side is a back side polarizing plate, and the protective film D is a tensile elastic modulus of 3,460 MPa in the transmission axis direction of the back side polarizing plate at 85 ° C. The tensile elasticity was 3,031 MPa.

[Comparative Example 1]

As the front-side polarizing plate, the front-side polarizing plate A used in Example 1 was used. The back-side polarizing plate is made in the back-side polarizing plate B. Except that the protective film B is changed to the protective film E, the rest is made in the same manner as the back-side polarizing plate B, and is made of a brightness improving film / adhesive layer / protection. The back side polarizing plate E composed of a film E / aqueous adhesive layer / polarizer / adhesive layer. Then, the same procedure as in Example 1 was performed except that the back-side polarizing plate B was changed to the back-side polarizing plate E of the example, and a sample for evaluation was prepared.

The obtained evaluation sample was measured for the amount of warpage in a high-temperature environment, and the results are shown in Table 1. The polarizing plate warped to the concave side is a back side polarizing plate, and the protective film E is a 85 ° C back side polarizing plate having a tensile elasticity of 1,767 MPa. The tensile elasticity was 1,813 MPa.

As shown in Table 1, when the tensile elastic modulus Et, Ea of the protective film in the polarizing plate warped to the concave side satisfies Et / Ea ≧ 1.1, the amount of warpage in a high-temperature environment can be reduced.

    [Possibility of industrial application]    

By using the polarizing plate set of the present invention, it is useful because the warpage of the liquid crystal panel under a high temperature environment can be reduced.

Claims (6)

    A polarizing plate kit includes a front-side polarizing plate disposed on a viewing side of a liquid crystal cell and a back-side polarizing plate disposed on a back side of the liquid crystal cell, and an absorption axis of the front-side polarizing plate and the back side The laminated body obtained by bonding the polarization axis of the polarizing plate orthogonally to the glass plate by bonding the front-side polarizing plate and the back-side polarizing plate. When heated at 85 ° C for 250 hours, the 85 ° C polarizing plate penetrated the axis direction. When the tensile elastic modulus and the tensile elastic modulus in the absorption axis direction of the polarizing plate at 85 ° C are respectively set to Et and Ea, the protective film in the polarizing plate on the side where the laminated body is warped into a concave shape satisfies the following (1) Et /Ea≧1.1 (1).         According to the set of polarizing plates described in item 1 of the scope of patent application, the front-side polarizing plate and the back-side polarizing plate each have a polarizer formed of a polyvinyl alcohol resin film, and the thickness of the polarizer is 15 μm or less.         The set of polarizing plates according to item 2 of the scope of patent application, wherein the front-side polarizing plate is provided with a hardened layer of an active energy ray-curable resin composition on at least one side of the polarizer.         The set of polarizing plates according to item 2 or 3 of the scope of patent application, wherein the front-side polarizing plate is provided with a protective film on one side of the polarizer and an active energy ray-curable resin composition on the other side. Hardened layer.         The set of polarizing plates according to any one of claims 2 to 4, wherein 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 are The difference is 5 μm or less.         A liquid crystal panel includes a set of polarizing plates according to any one of claims 1 to 5, and a liquid crystal cell. The thickness of the liquid crystal cell is 0.4 mm or less.