KR102571905B1 - Set of polarizing plates and liquid crystal panel - Google Patents

Abstract

[Problem] To provide a set of polarizing plates capable of reducing warping of a liquid crystal panel in a high-temperature environment.
[Solution] A polarizing plate on the front side disposed on the viewing side of a liquid crystal cell and a polarizing plate on the rear side disposed on the rear side of the liquid crystal cell, the absorption axis of the polarizing plate on the front side and the absorption axis of the polarizing plate on the rear side When a laminate in which the polarizing plate on the front side and the polarizing plate on the rear side are bonded to a glass plate with the axes orthogonal to each other is heated at 85 ° C. for 250 hours, the protective film on the polarizing plate on the side where the laminate is bent in a concave shape, A set of polarizers satisfying Et/Ea≥1.1 when the tensile modulus of elasticity in the direction of the transmission axis of the polarizer at 85°C and the tensile modulus of elasticity in the direction of the absorption axis of the polarizer at 85°C are respectively Et and Ea.

Description

Set of polarizer and liquid crystal panel {SET OF POLARIZING PLATES AND LIQUID CRYSTAL PANEL}

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

BACKGROUND OF THE INVENTION [0002] A liquid crystal display device is used for various display devices by taking advantage of characteristics such as low power consumption, low voltage operation, light weight and thin shape, and the like. 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.

In Japanese Unexamined Patent Publication No. 2013-37115 (Patent Document 1), the polarizing film included in the optical layered body on the front side is 5 μm or more thicker than the polarizing film included in the optical layered body disposed on the opposite side of the front side, Further, a method of suppressing warping of a liquid crystal panel in a high-temperature environment is proposed by laminating a polarizing film and a reflective polarizing film included in an optical laminate disposed on the opposite side to the front side. These methods were effective when a liquid crystal cell having a large thickness (eg, 0.5 mm or more, or even 0.7 mm or more) and a reflective polarizing film having a large thickness (eg, 50 µm or more) were used. However, in recent years, each member constituting the polarizing plate has become thinner and weaker, and suppression of warping of the liquid crystal panel in a high-temperature environment has been insufficient for a thin liquid crystal cell.

Patent Document 1: Japanese Unexamined Patent Publication No. 2013-37115

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

[1] having a polarizing plate on the front side disposed on the viewing side of the liquid crystal cell and a polarizing plate on the rear side disposed on the rear side of the liquid crystal cell,

When the laminate in which the polarizing plate on the front side and the polarizing plate on the back side are bonded to a glass plate is heated at 85 ° C. for 250 hours, The protective film in the polarizing plate on the side where the laminate is bent in a concave shape is the tensile modulus of elasticity in the direction of the transmission axis of the polarizing plate at 85 ° C. and the tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate at 85 ° C., respectively, by the following formula A set of polarizers satisfying (1).

Et/Ea≥1.1 (1)

[2] The polarizing plate set according to [1], wherein both the polarizing plate on the front side and the polarizing plate on the rear side have polarizers made of polyvinyl alcohol-based resin films, and both have a thickness of 15 μm or less.

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

[4] The polarizing plate on the front side is provided with a protective film on one side of the polarizer,

The set of the polarizing plate according to [2] or [3], further comprising a cured layer of an active energy ray-curable resin composition on one surface.

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

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

ADVANTAGE OF THE INVENTION According to the polarizing plate set of this invention, the curvature of a liquid crystal panel in a high-temperature environment can be reduced.

1 is a cross-sectional view showing an example of a set of polarizing plates of the present invention.
2 is a cross-sectional view showing an example of the liquid crystal panel of the present invention.
3 is a schematic cross-sectional view of a sample for evaluation after heat treatment.
4 is a plan view showing a position where the amount of warping of the sample for evaluation was measured.

A set of polarizing plates and a liquid crystal panel according to the present invention will be described with reference to the drawings as appropriate. The polarizing plate set of the present invention has a polarizing plate on the front side disposed on the viewing side of the liquid crystal cell and a polarizing plate on the rear side disposed on the rear side of the liquid crystal cell.

In one embodiment, the polarizing plate of the present invention has a member shown in FIG. 1 . The set of polarizing plates shown in Fig. 1 (a) has a polarizing plate 100 on the front side and a polarizing plate 200 on the rear side. In the polarizing plate 100 on the front side, the protective film 10 is laminated on one side of the polarizer 2 via the adhesive layer 30, and the other side of the polarizer 2 is made of an active energy ray curable adhesive. The cured layer 1 is laminated. In addition, an adhesive layer 20 is laminated on the cured layer 1.

In the polarizing plate 200 on the back side, a protective film 11 is laminated on one surface of the polarizer 2 via an adhesive layer 31, and an adhesive layer 21 is provided on the protective film 11. A luminance enhancing film 40 is laminated. Further, a pressure-sensitive adhesive layer 20 is laminated on another surface of the polarizer 2 .

The set of polarizing plates shown in Fig. 1(b) has a polarizing plate 101 on the front side and a polarizing plate 201 on the rear side. In the polarizer 101 on the front side, the protective film 10 is laminated on one side of the polarizer 2 via the adhesive layer 30, and the other side of the polarizer 2 is made of an active energy ray curable adhesive. The cured layer 1 is laminated. In addition, an adhesive layer 20 is laminated on the cured layer 1.

In the polarizing plate 201 on the back side, a protective film 11 is laminated on one surface of the polarizer 2 via an adhesive layer 31, and an adhesive layer 21 is laminated on the other surface of the polarizer 2. ) through which the luminance enhancing film 40 is laminated. In addition, an adhesive layer 20 is laminated on the protective film 11 .

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

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

In the polarizing plate set of the present invention, the shape of the polarizing plate on the front side and the polarizing plate on the rear side is not particularly limited, but may be rectangular. When the shape of the polarizing plate is rectangular, the absorption axis of the polarizing plate on the front side is preferably parallel to the short side, and the absorption axis of the polarizing plate on the back side is preferably parallel to the long side.

In the polarizing plate set of the present invention, when a laminate including a polarizing plate on the front side and a polarizing plate on the back side is heated, the protective film of the polarizing plate on the side bent in a concave shape is the transmission axis of the polarizing plate at 85 ° C. When the tensile modulus of elasticity in the direction and the tensile modulus in the direction of the absorption axis of the polarizing plate at 85° C. are respectively Et and Ea, the following formula (1) is satisfied. The tensile modulus of elasticity 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 even more preferably 1.20 or more. Et/Ea may be 2.8 or less.

When the edge of the laminate is bent toward the polarizing plate on the front side, the polarizing plate on the side bent concavely is the polarizing plate on the front side, and when the edge of the laminate is bent toward the polarizing plate on the rear side, the polarizing plate on the side bent concavely is the rear side is a polarizer of Specifically, it will be described with reference to FIG. 3 . FIG. 3 shows a schematic cross-section of a laminate obtained by bonding a front-side polarizing plate 400 and a rear-side polarizing plate 401 to a glass plate 70, respectively, after heat treatment. In FIG. 3( a ), the concavely curved polarizing plate refers to the back side polarizing plate 401, and in FIG. 3(b), the concavely curved polarizing plate refers to the front side polarizing plate 400 ) points to. The polarizing plate on the side bent in a concave shape may be a polarizing plate on the front side or a polarizing plate on the back side. Since the back-side polarizing plate is often provided with a similarly stretched brightness enhancement film in addition to the stretched polarizer, when the absorption axis direction of the back-side polarizing plate is the long side direction, the back-side polarizer The shrinking force when the polarizing plate is heated is often larger than that of the polarizing plate on the front side.

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 in this case, the polarizing plate on the front side and the polarizing plate on the rear side can be the same size. When bonding a polarizing plate to a glass plate, the absorption axis of the polarizing plate on the front side and the absorption axis of the polarizing plate on the back side are bonded orthogonally. At this time, when the polarizing plate has a rectangular shape, the absorption axis of the polarizing plate on the front side is preferably parallel to the short side, and the absorption axis of the polarizing plate on the back side 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. If the thickness is within this range, it is easy to discriminate which of the polarizing plate on the front side and the polarizing plate on the back side is the polarizing plate on the side bent in a concave shape.

The polarizing plate on the side bent in a concave shape may have a protective film on both sides of the polarizer, and in this case, it is preferable that at least one protective film satisfies Formula (1), and protection laminated on the side far from the liquid crystal cell in the polarizer It is more preferable that the film satisfy Formula (1), and it is still more preferable that any protective film satisfy Formula (1).

The tensile elastic modulus Et in the transmission axis direction at 85°C is preferably 500 MPa or more and 10000 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 10000 MPa or less, and may be 1000 MPa or more and 8000 MPa or less.

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

(polarizer)

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

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate 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 degree of saponification of the polyvinyl alcohol-based 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 or polyvinyl acetal modified with aldehydes can be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

What formed a polyvinyl alcohol-type resin into a film is used as a raw film of a light polarizer. The method of forming a film of polyvinyl alcohol-type resin can be formed into a film by a well-known method. The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, and more preferably 5 to 20 μm, considering that the obtained polarizer has a thickness of 15 μm or less. When the film thickness of the raw film is 35 μm or more, it is necessary to increase the draw ratio when producing the polarizer, and there is a tendency for the dimensional shrinkage of the obtained polarizer to increase.

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

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 perform uniaxial stretching in multiple steps of these.

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

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye is employed. As the dichroic dye, iodine and dichroic dye are specifically used. Moreover, it is preferable to perform the process of immersing a polyvinyl alcohol-type resin film in water before a dyeing process.

When using iodine as a dichroic dye, a method of dyeing by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually adopted. 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. In addition, 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.

In addition, the immersion time (dyeing time) to this aqueous solution is about 20 to 1,800 seconds normally.

On the other hand, when using a dichroic dye as a dichroic dye, a method of dyeing by immersing 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, preferably about 1×10 ^-3 to 1 part by weight, per 100 parts by weight of water. This aqueous solution may contain inorganic salts, 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. In addition, the immersion time (dyeing time) to this aqueous solution is about 10 to 1,800 seconds normally.

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

The amount of boric acid in the aqueous solution containing boric acid is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When using iodine as a dichroic dye, it is preferable that this aqueous solution containing boric acid contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in the 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 boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

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

After water washing, a drying process is given and a polarizer can be obtained. The drying treatment 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, preferably 50 to 80°C. The time of the drying treatment is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

By the drying process, the water 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.

Moreover, when the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be inferior.

In addition, you may perform extending|stretching of the polyvinyl alcohol-type resin film in the manufacturing process of a polarizer, dyeing, boric acid treatment, a water washing process, and a drying process according to the method described in Unexamined-Japanese-Patent No. 2012-159778, for example. In the method described in this document, the polyvinyl alcohol-type resin layer used as a polarizer is formed by coating a base film with polyvinyl alcohol-type resin.

Reducing the shrinkage force of the polarizer itself is also effective for reducing warpage in a high temperature environment, and the thickness of the polarizers provided on the front polarizing plate and the rear polarizing plate is preferably 15 μm or less, and preferably 4 to 13 μm. It is more preferable, and it is still more preferable that it is 5-10 micrometers.

The magnitude of the difference between the thickness of the polarizer of the polarizing plate on the front side and the thickness of the polarizer of the polarizing plate on the rear side is preferably 5 μm or less, and may be 3 μm or less. When the protective film of the polarizing plate on the side bent in a concave shape satisfies Expression (1), by reducing the difference in thickness of the polarizer in this way, the effect on the warping of the liquid crystal panel in a high-temperature environment can be further reduced.

(protective film)

The protective film is composed of a resin film, and may also be composed of a transparent resin film. In particular, it is preferable to use a material having excellent transparency, mechanical strength, thermal stability, and moisture barrier properties. In this specification, a transparent resin film refers to a resin film having a monolithic transmittance of 80% or more in the visible light region.

In the case of laminating protective films on both sides of the polarizer, the same protective films may be used or different protective films may be used. In addition, the protective film in the polarizing plate on the front side and the protective film in the polarizing plate on the back side may use the same or different protective films.

The resin forming the protective film is not particularly limited, but examples thereof include methyl methacrylate-based resins, polyolefin-based resins, cyclic olefin-based resins, polyvinyl chloride-based resins, cellulose-based resins, styrene-based resins, and acrylonitrile. Butadiene-styrene-based resins, acrylonitrile-styrene-based resins, polyvinyl acetate-based resins, polyvinylidene chloride-based resins, polyamide-based resins, polyacetal-based resins, polycarbonate-based resins, modified polyphenylene ether-based resins, and films made of polybutylene terephthalate-based resins, polyethylene terephthalate-based resins, polysulfone-based resins, polyethersulfone-based resins, polyarylate-based resins, polyamideimide-based resins, and polyimide-based resins.

These resins can be used individually or in combination of two or more types. In addition, these resins can also be used after undergoing arbitrary appropriate polymer modification, and this polymer modification includes, for example, copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and a case involving reaction between different polymers. Denaturation, such as mixing, is mentioned.

Among these, it is preferable to use a methyl methacrylate type resin, a polyethylene terephthalate type resin, a polyolefin type resin, or a cellulose type resin as a material of a protective film. The polyolefin-based resin referred to herein includes chain polyolefin-based resins and cyclic polyolefin-based resins.

A methyl methacrylate type resin is a polymer containing 50 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 polymer containing 100% by weight of methyl methacrylate units is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

This methyl methacrylate-based resin can usually be obtained by polymerizing a monofunctional monomer containing methyl methacrylate as a main component in the presence of a radical polymerization initiator. In polymerization, a polyfunctional monomer or a chain transfer agent may coexist 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, benzyl methacrylate, and methacrylic acid. methacrylic acid esters other than methyl methacrylate, such as 2-ethylhexyl acid and 2-hydroxyethyl methacrylate; acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; Hydroxyalkyl acrylic acid esters, such as 2-(hydroxymethyl) methyl acrylate, 3-(hydroxyethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, and 2-(hydroxymethyl) butyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; halogenated styrenes such as chlorostyrene and bromostyrene; substituted styrenes such as vinyltoluene and α-methylstyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; And unsaturated imides, such as phenyl maleimide and cyclohexyl maleimide, etc. are mentioned. These monomers may be used individually, respectively, or may be used 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 di(meth)acrylate. , Ethylene glycol such as tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol di(meth)acrylate, or ester of hydroxyl groups at both ends of oligomers thereof with acrylic acid or methacrylic acid angry; What esterified the hydroxyl groups of both terminals of propylene glycol or its oligomer with acrylic acid or methacrylic acid; What esterified the hydroxyl group of dihydric alcohol, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate, with acrylic acid or methacrylic acid; bisphenol A, an alkylene oxide adduct of bisphenol A, or one obtained by esterifying hydroxyl groups at both ends of halogen-substituted products thereof with acrylic acid or methacrylic acid; Esterification of polyhydric alcohols such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid, and ring-opening addition of epoxy groups of glycidyl acrylate or glycidyl methacrylate to terminal hydroxyl groups of these polyhydric alcohols. ; dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen-substituted products thereof, and alkylene oxide adducts thereof with ring-opening addition of an epoxy group of glycidyl acrylate or glycidyl methacrylate; allyl (meth)acrylate; and aromatic divinyl compounds such as divinylbenzene. Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and neopentyl glycol dimethacrylate are preferably used.

As for the methyl methacrylate-based resin, one modified by performing a reaction between the functional groups copolymerized with the resin is also used. The reaction is, for example, a demethanol condensation reaction in the high molecular chain of the methyl ester group of methyl acrylate and the hydroxyl group of 2-(hydroxymethyl)methyl acrylate or the high molecular chain of the carboxyl group of acrylic acid and the hydroxyl group of 2-(hydroxymethyl)methyl acrylate. internal dehydration condensation reactions; and the like.

The polyethylene terephthalate-based resin means a resin in which 80 mol% or more of repeating units are constituted by ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. Examples of other dicarboxylic acid components include, but are not particularly limited to, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl)ethane, and adip. acid, sebacic acid, and 1,4-dicarboxycyclohexane; and the like.

Examples of the other diol component include, but are not particularly limited to, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, bisphenol A ethylene oxide adduct, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. can

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

As a method for producing polyethylene terephthalate-based resin, a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols as needed), a dialkyl ester of terephthalic acid and ethylene glycol (and other dicarboxylic acids as needed) Polycondensation after transesterification of dialkyl esters of carboxylic acid or other diols), and catalysts for ethylene glycol esters of terephthalic acid (and other dicarboxylic acids, if necessary) (and other diol esters, if necessary) A method of polycondensation in the presence of is employed. Further, solid-state polymerization may be performed as needed to improve molecular weight or reduce low-molecular-weight components.

Cyclic polyolefin resin is obtained by polymerizing cyclic olefin monomers such as norbornene and other cyclopentadiene derivatives in the presence of a catalyst. It is preferable to use such a cyclic polyolefin resin because it is easy to obtain a protective film having a predetermined retardation value described later.

As the cyclic polyolefin resin, for example, cyclopentadiene and olefins or (meth)acrylic acid or esters thereof are subjected to ring-opening metathesis polymerization using norbornene or a derivative thereof obtained by a Diels-Alder reaction as a monomer, Further, resins obtained by subsequent hydrogenation; Obtained by ring-opening metathesis polymerization of dicyclopentadiene and olefins or (meth)acrylic acid or its esters using tetracyclododecene or its derivatives as monomers obtained by Diels-Alder reaction, followed by hydrogenation profit; Resin obtained by similarly ring-opening metathesis copolymerization of at least 2 types of monomers selected from norbornene, tetracyclododecene, derivatives thereof, and other cyclic olefin monomers, followed by hydrogenation; and resins obtained by addition copolymerization of a chain olefin and/or an aromatic compound having a vinyl group to a cyclic olefin such as norbornene, tetracyclododecene or a derivative thereof.

Typical examples of chain polyolefin resins are polyethylene resins and polypropylene resins. Among them, propylene homopolymers or propylene-based copolymers copolymerizable with comonomers such as ethylene in an amount of 1 to 20% by weight, preferably 3 to 10% by weight, are preferably used.

The polypropylene resin may contain an alicyclic saturated hydrocarbon resin. By containing the alicyclic saturated hydrocarbon resin, it becomes easy to control the retardation value. The content of the alicyclic saturated hydrocarbon resin is advantageously 0.1 to 30% by weight relative to the polypropylene resin, and a more preferable 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 is not sufficiently obtained, while if the content exceeds 30% by weight, the alicyclic saturated hydrocarbon resin over time from the protective film may cause bleed-out.

Cellulosic resin is a cellulose obtained from raw material cellulose such as cotton linter or wood pulp (hardwood pulp, conifer pulp), in which some or all of the hydrogen atoms in the hydroxyl groups are substituted with acetyl groups, propionyl groups, and/or butyryl groups. , Cellulose organic acid ester or cellulose mixed organic acid ester. Examples include cellulose acetate esters, propionic acid esters, butyric acid esters, and mixed esters thereof. Among them, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, and a cellulose acetate butylate film are preferred.

The method of using a methyl methacrylate-based resin, a polyethylene terephthalate-based resin, a polyolefin-based resin, and a cellulose-based resin as a second protective film for adhering to a polarizer may be appropriately selected from a method according to each resin, particularly It is not limited.

For example, a solvent casting method in which a resin dissolved in a solvent is cast on a metal band or drum and the solvent is removed by drying to obtain a film, and a film is obtained by heating and kneading the resin to a temperature equal to or higher than its melting temperature, extruding from a die, and cooling. A melt extrusion method is employed. In this melt extrusion method, a single layer film may be extruded or a multilayer film may be extruded simultaneously.

The film used as the protective film can be easily obtained as a commercially available product, and if it is a methyl methacrylate-based resin film, each is a trade name of Smipex (Sumitomo Chemical Co., Ltd.), ACRYLITE (registered trademark), Acriprene (registered trademark) (above, manufactured by Mitsubishi Rayon Co., Ltd.), Deraglass (registered trademark) (manufactured by Asahi Kasei Co., Ltd.), Paraglass (registered trademark), Como Glass (registered trademark) (above) , Shakurare Co., Ltd.), Ac Reviewer (registered trademark) (made by Nippon Shokubai Co., Ltd.), etc. If it is a polyolefin resin film, Zeonoa (registered trademark) (Nippon Zeon Co., Ltd.), Atone (registered trademark) (JSR Corporation), etc. are mentioned as a trade name, respectively. If it is a polyethylene terephthalate-type resin film, Novaclea (registered trademark) (made by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (made by Teijin Chemical Co., Ltd.) etc. are mentioned as a brand name, respectively. . If it is a polypropylene resin film, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Santox Co., Ltd.), Tocello (registered trademark) (manufactured by Tocello Co., Ltd.) , Toyobo Pyrene Film (registered trademark) (manufactured by Toyobo Seki Co., Ltd.), Torepan (registered trademark) (manufactured by Toray Film Co., Ltd.), Nippon Polyace (manufactured by Nippon Polyace Co., Ltd.) ), and Taiko (registered trademark) FC (manufactured by Futamura Chemical Co., Ltd.). In addition, if it is a cellulose-type resin film, Fujitac (registered trademark) TD (made by Fujifilm Co., Ltd.), KC2UA, and Konica Minolta TAC film KC (made by Konica Minolta Co., Ltd.) etc. are mentioned as a brand name, respectively.

The protective film used in the present invention may be imparted with anti-glare properties (haze). The method for imparting anti-glare properties is not particularly limited, but, for example, the method of mixing inorganic fine particles or organic fine particles in the above raw resin to form a film, using the above multilayer extrusion, In addition, a method of forming a two-layer film made of resin with no fine particles mixed thereon, or a method of forming a three-layer film with the resin mixed with particles facing the outside, and mixing inorganic fine particles or organic fine particles with curable binder resin on one side of the film A method of forming an anti-glare layer by coating a coating liquid formed of the above and curing the binder resin is employed.

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

The thickness of the protective film is usually about 1 to 50 µm, and preferably 10 to 40 µm, from the viewpoint of strength and handleability.

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

Functional layers such as a conductive layer, a hard coat layer, and a low reflection layer may be further provided on the protective film of the polarizing plate on the front side. In addition, a resin composition having these functions may be selected as the binder resin constituting the anti-glare layer.

A protective film satisfying Formula (1) can also be manufactured by, for example, stretching a resin film. The stretching method is not particularly limited, but may be a uniaxially stretched film obtained by transverse stretching after film formation, a biaxially stretched film obtained by longitudinal stretching after film formation and then transverse stretching, and the like. 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)

It is preferable that the polarizing plate on the back side has a luminance enhancing film on the far side from the liquid crystal cell in the polarizer. The thickness of the brightness enhancement film is preferably 35 μm or less, and more preferably 30 μm or less.

As the brightness enhancing film, a polarization conversion element having a function of separating light emitted from a light source (backlight) into transmitted polarized light and reflected polarized light or scattered polarized light is used. Such a luminance enhancing film can improve the emission efficiency of linearly polarized light by using retroreflective or scattered polarized light from a backlight.

An anisotropic reflective polarizer is mentioned as a brightness improvement film, for example. Examples of the anisotropic reflective polarizer include an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. As an anisotropic multilayer thin film, for example, the trade name "APF" manufactured by 3M Corporation is exemplified. Further, as the anisotropic reflection polarizer, a composite of a cholesteric liquid crystal layer and a λ/4 plate is exemplified. As such a composite, a trade name "PCF" manufactured by Nitto Denko Co., Ltd. is exemplified. Also, as the anisotropic reflection polarizer, a reflection grid polarizer may be used. Examples of the reflective grid polarizer include metal grid reflective polarizers that produce reflective polarized light even in the visible light region by subjecting metal to microprocessing. Among them, a luminance enhancing film composed of an anisotropic multiple thin film is preferable.

A functional layer may be formed on the surface of the brightness enhancement film opposite to the bonding surface with the polarizing plate. As the functional layer, for example, a hard coat layer, an anti-glare layer, a light diffusion layer, a retardation layer having a retardation value of 1/4 wavelength, and the like can be cited, thereby improving adhesion to the backlight tape and improving the uniformity of displayed images. can

(Adhesive layer)

An adhesive layer may be laminated on the surface of the polarizing plate. A polarizing plate can be bonded to a liquid crystal cell through this adhesive layer. In FIG. 1, the adhesive layer 20 corresponds to this.

The thickness of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive is preferably 5 to 25 μm, more preferably 10 to 25 μm.

The pressure-sensitive adhesive layer for bonding the polarizing plate on the front side to the liquid crystal cell and the pressure-sensitive adhesive layer for bonding the polarizing plate on the rear side to the liquid crystal cell may be the same or different.

Further, the brightness enhancing film and the protective film or polarizer may be laminated with an adhesive layer. In FIG. 1, the adhesive layer 21 corresponds to this. The thickness of the pressure-sensitive adhesive layer formed of 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-based polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy-based, fluorine-based, natural rubber, and synthetic rubbers. It is possible to appropriately select and use a polymer such as rubber or the like as a base polymer. As the pressure-sensitive adhesive, those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness, and adhesion properties, and excellent weather resistance, heat resistance, and the like are preferable.

In addition, various additives may be mix|blended with the adhesive. A silane coupling agent and an antistatic agent are mentioned as an additive.

(adhesive layer)

The lamination of the protective film and the polarizer or the lamination of the brightness enhancement film and the polarizer can be performed by, for example, a method of integrating using an adhesive. The thickness of the adhesive layer formed of the adhesive is preferably 0.01 to 35 μm, more preferably 0.01 to 10 μm, still more preferably 0.01 to 5 μm. If it is this range, lifting or peeling does not arise between a protective film or a brightness improving film, and a polarizer, and adhesive force which does not have a problem in practical use can be obtained.

Examples of the adhesive include solvent-type adhesives, emulsion-type adhesives, pressure-sensitive adhesives, rewritable adhesives, polycondensation-type adhesives, solvent-free adhesives, film adhesives, and hot-melt adhesives. Also, if necessary, an adhesive layer may be formed through the anchor coat layer.

Preferred adhesives include water-soluble adhesives. Some of these water-soluble adhesives have, for example, a polyvinyl alcohol-based resin as a main component. A commercially available water-soluble adhesive may be used, or a commercially available adhesive mixed with a solvent or an additive may be used. Commercially available polyvinyl alcohol-based resins that can be used as water-soluble adhesives include, for example, KL-318 manufactured by Shakurale Co., Ltd.

The water soluble adhesive may contain a crosslinking agent. As the 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. Commercially available products of the crosslinking agent include, for example, glyoxal and Sumirez Resin 650 (30) manufactured by Taoka Kagaku Kogyo Co., Ltd.

Another preferred adhesive is an active energy ray curable adhesive comprising a resin composition that is cured by irradiation with active energy rays. Examples of active energy ray curable adhesives 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, and the like. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from photopolymerizable monomers. Examples of the photopolymerization initiator include substances that generate active species such as radicals, cations, or anions when irradiated with active energy rays such as ultraviolet rays. As an active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, one containing a photocurable epoxy-based monomer and a photocationic polymerization initiator can be preferably used.

When using an active energy ray-curable adhesive, after bonding a polarizer and a protective film, a drying process is performed as needed, and then the hardening process of hardening an active energy ray-curable adhesive by irradiating an active energy ray is performed. The light source of the active energy ray is not particularly limited, but an ultraviolet ray having a luminous distribution with a wavelength of 400 nm or less is preferable, specifically, a low-pressure mercury-vapor lamp, a medium-pressure mercury-vapor lamp, a high-pressure mercury lamp, an ultra-high pressure mercury-vapor lamp, a chemical lamp, a black light lamp, and a microwave excited mercury lamp. , a metal halide lamp, or the like can be used.

The adhesive may contain additives. Examples of additives include ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers and antifoaming agents.

(cured 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 that protects the surface of the polarizer. Since the cured layer of the active energy ray-curable resin composition can be made thinner than a normal protective film, it is effective for thinning the polarizing plate. The cured 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 polarizing plate on the front side) preferably has a hardened layer of an active energy ray-curable resin composition on at least one surface of the polarizer, and is placed on the side closer to the liquid crystal cell in the polarizer. It is more preferable to provide a cured layer of an active energy ray-curable resin composition. In this case, since the distance between the polarizer and the liquid crystal cell can be reduced, the force to deform the liquid crystal cell according to the contraction of the polarizer can be reduced, and the effect on the warping of the liquid crystal panel in a high temperature environment can be further reduced. there is. From this point of view, the distance from the surface of the polarizing plate on the front side close to the liquid crystal cell in the polarizer to the surface of the polarizing plate on the front side of the liquid crystal cell near the polarizer is preferably 30 μm or less, for example, 25 It is more preferable that it is micrometer or less.

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, 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 adhesives can be used. The same active energy ray-curable resin composition and the active energy ray-curable adhesive may be used, or different ones may be used.

(Manufacturing method of polarizing plate)

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

Hereinafter, a set of polarizing plates shown in Fig. 1(a) will be described as an example with respect to a method of manufacturing the front-side polarizing plate and the rear-side polarizing plate constituting the polarizing plate of the present invention.

(Method of manufacturing front-side polarizing plate)

A release film, polarizer 2 and protective film 10 are prepared, the protective film is bonded to one side of the polarizer via an adhesive, and the release film is laminated on the other side of the polarizer via a volatile liquid. . Of course, bonding of the protective film and the polarizer and lamination of the peeling film and the polarizer may be performed sequentially, respectively.

The volatile liquid is, for example, water or a mixture of water and a hydrophilic liquid. It is preferable that the hydrophilic liquid does not remain after the heat treatment in the second step, and examples thereof include methanol, ethanol, 1-butanol, tetrahydrofuran, acetone, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, Formic acid, acetic acid, etc. are mentioned. An additive such as an antistatic agent may be added to the volatile liquid.

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

In bonding the protective film to the polarizer, adhesion-facilitating treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, or saponification treatment is applied to the bonding surface of the polarizer and/or the protective film to improve adhesion. can do It is also useful to treat the release film similarly to a protective film in order to improve the wettability of the volatile liquid.

When an active energy ray-curable adhesive is used as the adhesive, the volatile liquid is volatilized and removed by curing the adhesive by irradiating with active energy rays and then performing heat treatment. When a water-system adhesive is used as an adhesive agent, a volatile liquid is volatilized and removed by heat-processing, adhering a polarizer and a protective film. It is preferable to use a water-based adhesive in view of simplifying the process.

The drying temperature is preferably 30 to 90°C. If the temperature is less than 30°C, the time required for drying is long and there is a possibility that appearance defects may occur. In addition, when the drying temperature exceeds 90°C, there is a possibility that the polarization performance of the polarizer is 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, more preferably 150 to 600 seconds.

By laminating a peeling film on a polarizer through a layer made of a volatile liquid, the heating temperature in this step can be increased to, for example, more than 60°C and up to about 90°C or less. That is, even if the heating temperature is set high, breakage of the polarizer can be suppressed, and the shrinkage rate of the polarizer is small by the high-temperature heating, so that a one-side protection polarizing plate with high dimensional stability can be obtained. By reducing the shrinkage rate of the one-sided protective polarizing plate, when a liquid crystal panel is produced using this polarizing plate, warpage of the liquid crystal panel can be further reduced.

In order to volatilize the volatile liquid used for lamination of the polarizer and the peeling film by heating, the water vapor transmission rate of at least one of the protective film and the peeling film is preferably 400 g / m 2 / 24 hr or more, and 420 g / m 2 / 24 hr More than that is more preferable. Since a volatile liquid can be volatilized and removed efficiently in a subsequent 2nd process as water vapor permeability is this range, productivity can be further improved.

In order to laminate the cured layer 1 of the active energy ray-curable resin composition on the polarizer 2, the active energy ray-curable resin composition is applied on the base film. Next, the release film is peeled off from the single-sided protective polarizing plate, and the polarizer 2 in the single-sided protective polarizing plate and the active energy ray-curable resin composition on the base film are laminated. By irradiating active energy rays, the active energy ray-curable resin composition is cured to form the cured layer 1 . By peeling off the base film and forming the adhesive layer 20 on the cured layer 1, the adhesive layer 20 / cured layer of active energy ray-curable resin composition (1) / polarizer 2 / adhesive layer ( 30)/protective film 10 to obtain a polarizing plate on the front side.

(Method of manufacturing back-side polarizing plate)

By the same method as the manufacturing method of the polarizing plate on the front side, the release film, the polarizer 2 and the protective film 11 are prepared, and the protective film is bonded to one side of the polarizer 2 with an adhesive, A peeling film is laminated on the other surface of the polarizer 2 via a volatile liquid. After the polarizer 2 and the protective film 11 are adhered and the volatile liquid is removed, the peeling film is peeled off to obtain a one-sided protective polarizing plate.

On the protective film in the one-sided protective polarizing plate, the brightness enhancing film is laminated through the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer 20 is laminated on the polarizer 2, whereby the pressure-sensitive adhesive layer 20/polarizer 2/adhesive layer (31)/Protective film (11)/Adhesive layer (21)/Brightness improving film (40) The back side polarizing plate can be obtained.

Although the shape of the polarizing plate of this invention is not specifically limited, A rectangle may be sufficient. 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.

(Method of manufacturing liquid crystal panel)

A liquid crystal panel can be obtained by bonding a set of polarizing plates of the present invention to both surfaces of a liquid crystal cell, respectively. Bonding is preferably carried out through the pressure-sensitive adhesive layer of the polarizing plate on the front side and through the pressure-sensitive adhesive layer of the polarizing plate on the back side, respectively. Further, it is preferable that the polarizing plate on the front side is laminated on the viewing side of the liquid crystal cell, and the polarizing plate on the rear side is laminated on the rear side of the liquid crystal cell. The liquid crystal panel of the present invention can be suitably applied to a liquid crystal display device. The polarizing plate on the front side is preferably bonded so that its absorption axis is substantially parallel to the direction of the short side of the liquid crystal cell, and the polarizing plate on the back side is bonded so that its absorption axis is substantially parallel to the direction of the long side of the liquid crystal cell. it is desirable In the present specification, substantially parallel indicates that the angle formed, for example, is 0±5°, preferably 0±1°.

A liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between these substrates. The cell substrate is generally made of glass in many cases, 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 constituted by various types employed in this field. According to the polarizing plate set of the present invention, even when the thickness of the liquid crystal cell is 0.4 mm or less, warping can be significantly reduced. In the present invention, the thickness of the liquid crystal cell includes the thickness of the liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer.

[Example]

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited by these examples. In the examples, % and parts representing content or usage amount are based on weight unless otherwise specified. In addition, the evaluation method used in the Example is 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. Then, with the vertical grippers of a tensile force tester equipped with a thermostat [manufactured by Shimadzu Seisakusho Co., Ltd. AUTOGRAPH (registered trademark) AG-1S tester], both ends in the long side direction of the test piece were held so that the distance between the grippers was 100 mm. Then, it was pulled at a tensile speed of 50 mm/min in an environment of 85°C, a stress-strain curve was created, and the tensile elastic modulus at 85°C was calculated.

(3) Permeability

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

(4) Determination of the polarizing plate that bends in a concave shape and measurement of the amount of warp in a high-temperature environment

A sample for evaluation having the configuration of a polarizing plate on the back side / glass plate / polarizing plate on the front side was left still in an environment of 85 ° C. for 250 hours, and then placed on a measuring table of a two-dimensional measuring instrument with the polarizing plate on the front side 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 25 points on the sample surface for evaluation were respectively focused using that as a reference, and the heights from the focal point as a reference were measured. The difference between the maximum and minimum heights at the 25 measurement points is the amount of warping, and the bending of the edge of the evaluation sample toward the polarizing plate on the front side is positive warping, the bending of the edge of the evaluation sample toward the polarizing plate on the back side The warpage was made negative warpage. In the case of positive warping, the polarizing plate on the side bent in a concave shape is a front-side polarizing plate, and in the case of negative warping, the polarizing plate on the side bent in a concave shape is a rear-side polarizing plate.

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

[Production Example 1] Production of polarizer

A polyvinyl alcohol film (average polymerization degree of about 2400, saponification degree of 99.9 mol% or more) with a thickness of 20 μm was uniaxially stretched about 4 times by dry stretching, and immersed in pure water at 40 ° C. for 40 seconds while maintaining a tension state. After that, dyeing was performed by immersing 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. 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. Then, after washing with pure water at 8°C for 15 seconds, drying at 60°C for 50 seconds and then at 75°C for 20 seconds while holding at a tension of 300 N, to a thickness where iodine is adsorbed and oriented on the polyvinyl alcohol film. A 7 μm polarizer was obtained.

[Production Example 2] Preparation of water-based adhesive

With respect to 100 parts by weight of water, 3 parts by weight of carboxyl group-modified polyvinyl alcohol [trade name “KL-318” obtained from Shakurale Co., Ltd.] was dissolved, and in the aqueous solution, polyamide epoxy type additive [Taokaka, which is a water-soluble epoxy resin] 1.5 parts by weight of “Sumirez Resin (registered trademark) 650(30)” obtained from Chemical Industry Co., Ltd., an aqueous solution having a solid content concentration of 30% by weight] was added to prepare a water-based adhesive.

[Production Example 3] Active energy ray curable resin composition

As the polymerization compound, 50 parts by mass of an oxetane compound (bifunctional) (OXT221), 35 parts by mass of an alicyclic epoxy compound (bifunctional) (CEL2021P), an aromatic epoxy compound (trifunctional) (15 parts by mass of TECHMORE VG3101L and photocationic polymerization An active energy ray-curable resin composition was obtained by mixing 2.25 parts by mass of triarylsulfonium hexafluorophosphate as an initiator.

[Protective Films A, B, C, D, E and Release Films F, G]

The following 5 types of protective films and 2 types of peeling films were prepared.

Protective film A: 25KCHCN-TC. A film obtained by saponifying a triacetyl cellulose film having a hard coat layer manufactured by Topan Insatsu Co., Ltd. The thickness was 32 μm, and the moisture permeability was 450 g/m 2 24 hr.

Protective film B: ZT12. Nippon Zeon Co., Ltd. cyclic polyolefin resin film. It has a thickness of 20 μm and is produced by transverse uniaxial stretching.

Protective film C: Zerotack (registered trademark). A film obtained by saponifying a triacetyl cellulose film manufactured by Konica Minolta Co., Ltd. The thickness was 20 μm.

Protective film D: KC2UAW. A film obtained by saponifying a triacetyl cellulose film manufactured by Konica Minolta Co., Ltd. The thickness was 25 μm.

Protective film E: ZEONOR (registered trademark). Nippon Zeon Co., Ltd. cyclic polyolefin resin film. The thickness was 20 μm.

Release film F: TD80UL. A triacetyl cellulose film manufactured by Fujifilm Corporation. The thickness was 80 μm, and the moisture permeability was 502 g/m 2 24 hr.

Release film G: Sumitomo Chemical Co., Ltd. polymethyl methacrylate resin film. The thickness was 80 μm, and the moisture permeability was 50 g/m 2 24 hr.

[Example 1]

[Production of polarizing plate A on the front side]

While conveying the polarizer obtained in manufacture example 1 continuously, protective film A was continuously unwound from the roll of protective film A, and peeling film G was continuously unwound from the roll of peeling film G. Next, while injecting water-based adhesive between the polarizer and protective film A, pure water is injected between the polarizer and release film G, and passed through a bonding roll to protect film A/water-based adhesive/polarizer/pure water/release film G It was set as a laminated film consisting of. Next, the laminated film is conveyed, and the water-based adhesive is dried by performing a heat treatment at 80°C for 300 seconds in a drying furnace, and the pure water interposed between the polarizer and the peeling film G is removed by volatilization, and the one-side protection polarizing plate with the peeling film is removed. got The peeling film G was peeled off from the single-sided protective polarizing plate with the peeling film, and the single-sided protective polarizing plate was obtained.

On the other hand, on one side of a 50 μm-thick cyclic polyolefin-based resin film [ZEONOR (registered trademark), manufactured by Nippon Zeon Co., Ltd.], the active energy ray-curable resin composition prepared in Production Example 3 was cured to a film thickness of about 3 μm. It was crafted to become The polarizer of the one-sided protective polarizing plate is bonded to the coated surface, and from the side of the cyclic polyolefin-based resin film, using an ultraviolet irradiation device (a "D bulb" manufactured by Fusion UV Systems is used as a lamp), a wavelength of 280 nm to 320 nm is used. The active energy ray-curable resin composition was cured by irradiating ultraviolet light so that the integrated light amount was 200 mJ/cm 2 . The cyclic polyolefin-based resin film was peeled off, and corona treatment was performed on the cured layer of the active energy ray-curable resin composition. An adhesive layer [trade name "#KT" manufactured by Lintec Co., Ltd. on the cured material layer. The thickness was 20 μm.] were bonded. In this way, polarizing plate A on the front side composed of protective film A/water-based adhesive layer/polarizer/cured layer of active energy ray-curable resin composition/adhesive layer was produced.

[Production of polarizing plate B on the back side]

While conveying the polarizer obtained in manufacture example 1 continuously, the protective film B was continuously unwound from the roll of protective film B, and also the peeling film F was continuously unwound from the roll of peeling film F. Next, while injecting water-based adhesive between the polarizer and corona-treated protective film B, injecting pure water between the polarizer and the peeling film F, passing through a bonding roll, protective film B/water-based adhesive/polarizer/pure water/ It was set as the laminated|multilayer film which consists of peeling film F. Next, while transporting the laminated film and drying the water-based adhesive by performing heat treatment at 80°C for 300 seconds in a drying furnace, the pure water intervening between the polarizer and the peeling film F is removed by volatilization, and the one-sided protective polarizing plate with the peeling film got The peeling film F was peeled off from the single-sided protective polarizing plate with the peeling film, and the single-sided protective polarizing plate was obtained.

An adhesive layer [trade name “#L2” manufactured by Lintec Co., Ltd.] on the protective film B of the one-sided protective polarizing plate. The thickness was 5 μm] was bonded, and a brightness enhancing film [trade name “Advanced Polarized Film, Version 3, manufactured by 3M Co., Ltd., the thickness was 26 μm.]) was further bonded on the pressure-sensitive adhesive layer. After that, the polarizer An adhesive layer [trade name "#KT" manufactured by Lintec Co., Ltd., the thickness was 20 μm] was bonded on the top. In this way, the brightness improving film / adhesive layer / protective film B / water-based adhesive layer / polarizer / A back-side polarizing plate B composed of an adhesive layer was produced.

[Production of evaluation samples]

The polarizing plate A on the front side was cut into a rectangular shape of 155.25 mm in the direction of the transmission axis and 95.90 mm in the direction of the absorption axis, and the polarizing plate B on the back side was cut into a rectangular shape of 155.25 μm in the direction of the absorption axis and 95.90 mm in the direction of the transmission axis. it was foundation Then, a glass plate (manufactured by Corning, product number: EAGLEXG (registered trademark)) having a thickness of 0.4 mm is prepared, and the front surface is passed through each pressure-sensitive adhesive layer so that the absorption axis of the polarizing plate on the front side and the absorption axis of the polarizing plate on the rear side are orthogonal. The polarizing plate on the side and the polarizing plate on the back side were bonded to the glass plate.

About the obtained sample for evaluation, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The concave polarizing plate is the polarizing plate on the back side, and the protective film B has a tensile modulus of elasticity in the direction of the transmission axis of the polarizing plate on the back side at 85°C of 2190 MPa, and a tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate on the back side. was 1786 MPa.

[Example 2] (Comparative)

The polarizing plate A on the front side used in Example 1 was used as the polarizing plate on the front side. Regarding the back-side polarizing plate, in the production of the back-side polarizing plate B, it is produced 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. Thus, a back-side polarizing plate C composed of brightness enhancing film/pressure-sensitive adhesive layer/protective film C/water-based adhesive layer/polarizer/pressure-sensitive adhesive layer was produced. Then, a sample for evaluation was produced in the same manner as in Example 1 except that the polarizing plate B on the back side was changed to the polarizing plate C on the back side in this Example.

About the obtained sample for evaluation, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The concave polarizing plate is the polarizing plate on the back side, and the protective film C has a tensile modulus of elasticity in the direction of the transmission axis of the polarizing plate on the back side at 85°C of 3260 MPa, and a tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate on the back side. was 2890 MPa.

[Example 3] (Comparative)

The polarizing plate A on the front side used in Example 1 was used as the polarizing plate on the front side. Regarding the back-side polarizing plate, in the production of the back-side polarizing plate C, except that the protective film C was changed to the protective film D, it was produced in the same manner as the back-side polarizing plate C, and the brightness enhancement film / pressure-sensitive adhesive layer / A back-side polarizing plate D composed of protective film D/water-based adhesive layer/polarizer/pressure-sensitive adhesive layer was produced. Then, a sample for evaluation was produced in the same manner as in Example 1, except that the polarizing plate B on the back side was changed to the polarizing plate D on the back side in this Example.

About the obtained sample for evaluation, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The concave polarizing plate is the polarizing plate on the back side, and the protective film D has a tensile modulus of elasticity of 3460 MPa in the direction of the transmission axis of the polarizing plate on the back side at 85 ° C., and a tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate on the back side. was 3031 MPa.

[Comparative Example 1]

The polarizing plate A on the front side used in Example 1 was used as the polarizing plate on the front side. Regarding the back-side polarizing plate, in the production of the back-side polarizing plate B, except that the protective film B was changed to the protective film E, it was produced in the same way as the back-side polarizing plate B, and the brightness enhancement film/adhesive layer/ Polarizing plate E on the back side composed of protective film E/water-based adhesive layer/polarizer/pressure-sensitive adhesive layer was produced. Then, a sample for evaluation was produced in the same manner as in Example 1 except that the polarizing plate B on the back side was changed to the polarizing plate E on the back side in this Example.

About the obtained sample for evaluation, the amount of warpage in a high-temperature environment was measured. The results are shown in Table 1. The concave polarizing plate is the polarizing plate on the back side, and the protective film E has a tensile modulus of elasticity in the direction of the transmission axis of the polarizing plate on the back side at 85° C. of 1767 MPa, and a tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate on the back side. was 1813 MPa.

As shown in Table 1, when Et/Ea≥1.1 was satisfied for the tensile modulus Et and Ea of the protective film in the concave-curved polarizing plate, the amount of warping in a high-temperature environment could be reduced.

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

Reference Numerals 1: cured layer of active energy ray-curable resin composition, 2: polarizer, 10, 11: protective film, 20, 21: adhesive layer, 30, 31: adhesive layer, 40: brightness enhancement film, 402: polarizer, 100, 101 , 400: polarizer on the front side, 200, 201, 401: polarizer on the rear side, 300: liquid crystal cell, 70: glass plate, 80: measurement point

Claims (8)

A polarizing plate on the front side disposed on the viewing side of the liquid crystal cell and a polarizing plate on the rear side disposed on the rear side of the liquid crystal cell,
When the laminate in which the polarizing plate on the front side and the polarizing plate on the back side are bonded to a glass plate is heated at 85 ° C. for 250 hours, The protective film in the polarizing plate on the side where the laminate is bent in a concave shape is the tensile modulus of elasticity in the direction of the transmission axis of the polarizing plate at 85 ° C. and the tensile modulus of elasticity in the direction of the absorption axis of the polarizing plate at 85 ° C., respectively, by the following formula (1) is satisfied,
Et/Ea≥1.1 (1)
The polarizing plate on the front side and the polarizing plate on the rear side both have polarizers made of polyvinyl alcohol-based resin films, and both polarizers have a thickness of 15 μm or less,
The distance from the surface of the polarizing plate on the front side closer to the liquid crystal cell in the polarizer to the surface of the polarizing plate on the front side of the liquid crystal cell closer to the polarizer is 30 μm or less,
The polarizing plate on the front side has a protective film on only one side of the polarizer, and the polarizing plate on the rear side has a protective film on only one side of the polarizer,
The protective film of the polarizing plate on the front side is a triacetyl cellulose film, and the protective film of the polarizing plate on the rear side is a cyclic polyolefin-based resin film. delete The polarizing plate set according to claim 1, wherein the polarizing plate on the front side has a hardened layer of an active energy ray-curable resin composition on at least one surface of the polarizing plate. The polarizing plate of claim 1 or 3, wherein the polarizing plate on the front side has a protective film on one side of the polarizer,
A set of polarizing plates equipped with a cured layer of an active energy ray-curable resin composition on one surface. The set of polarizing plates according to claim 1 or 3, wherein a difference between the thickness of the polarizer of the polarizing plate on the front side and the thickness of the polarizing plate of the polarizing plate on the rear side is 5 μm or less. A liquid crystal panel comprising the polarizing plate set according to claim 1 or 3 and a liquid crystal cell, wherein the liquid crystal cell has a thickness of 0.4 mm or less. delete The set of polarizing plates according to claim 1, wherein a hard coat layer or a low reflection layer is provided on the protective film constituting the polarizing plate on the front side.

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