JP6775551B2 - Polarizing plate set and liquid crystal panel - Google Patents

Description

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

Liquid crystal display devices are used in various display devices by taking advantage of their features such as low power consumption, operation at low voltage, light weight and thinness. The liquid crystal panel constituting the liquid crystal display device has a structure in which a pair of polarizing plates are laminated on both sides of the liquid crystal cell.

According to Japanese Patent Application Laid-Open No. 2013-37115 (Patent Document 1), the polarizing film contained in the optical laminate on the front side is 5 μm more than the polarizing film contained in the optical laminate arranged on the side opposite to the front side. A method for suppressing warpage of a liquid crystal panel in a high temperature environment has been presented by making the thickness as thick as possible and further laminating a polarizing film and a reflective polarizing film contained in an optical laminate arranged on the side opposite to the front side. ing. These methods could be effective when a thick liquid crystal cell (for example, 0.5 mm or more, further 0.7 mm or more) and a thick (for example, 50 μm or more) reflective polarizing film were used. However, in addition to the fact that each member constituting the polarizing plate has become thinner and weaker in recent years, it has been insufficient to suppress the warp of the liquid crystal panel in a high temperature environment for a thin liquid crystal cell.

Japanese Unexamined Patent Publication No. 2013-37115

An object of the present invention is to provide a set of polarizing plates capable of reducing warpage of a liquid crystal panel in a high temperature environment.

[1] It has a front side polarizing plate arranged on the visual side of the liquid crystal cell and a back side polarizing plate arranged on the back side of the liquid crystal cell.
A laminate in which the front-side polarizing plate and the back-side polarizing plate are bonded to a glass plate so that the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate are orthogonal to each other is formed at 85 ° C. The protective film on the polarizing plate on the side where the laminate warps in a concave shape when heated for 250 hours is the tensile elasticity in the polarizing plate transmission axis direction at 85 ° C. and the polarizing plate absorption axial direction at 85 ° C. A set of polarizing plates satisfying the following equation (1) when the tensile elasticity is Et and Ea, respectively.
Et / Ea ≧ 1.1 (1)
[2] The polarized light according to [1], wherein both the front-side polarizing plate and the back-side polarizing plate have a polarizing element made of a polyvinyl alcohol-based resin film, and the thickness of the polarizing element is 15 μm or less. A set of boards.
[3] The set of polarizing plates according to [2], wherein the front-side polarizing plate includes a cured layer of an active energy ray-curable resin composition on at least one surface of the polarizing element.
[4] The front-side polarizing plate is provided with a protective film on one surface of the polarizer.
The set of polarizing plates according to [2] or [3], which comprises a cured layer of an active energy ray-curable resin composition on the other surface.
[5] The method according to any one of [2] to [4], wherein the magnitude of the difference between the thickness of the polarizer provided by the front polarizing plate and the thickness of the polarizer provided by the back polarizing plate is 5 μm or less. A set of polarizing plates.
[6] A liquid crystal panel comprising the set of the polarizing plate according to any one of [1] to [5] and a liquid crystal cell, wherein the thickness of the liquid crystal cell is 0.4 mm or less.

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

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

The set of the polarizing plate and the liquid crystal panel of the present invention will be described with reference to the drawings as appropriate. The set of polarizing plates of the present invention has a front-side polarizing plate arranged on the visual 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 has the member shown in FIG. The set of polarizing plates shown in FIG. 1A has a front-side polarizing plate 100 and a back-side polarizing plate 200. In the front side polarizing plate 100, a protective film 10 is laminated on one surface of the polarizing element 2 via an adhesive layer 30, and a cured layer 1 of an active energy ray-curable adhesive is formed on the other surface of the polarizing element 2. It is laminated. Further, the pressure-sensitive adhesive layer 20 is laminated on the cured layer 1.

In the back-side polarizing plate 200, a protective film 11 is laminated on one surface of the polarizing element 2 via an adhesive layer 31, and a brightness improving film 40 is further laminated on the protective film 11 via an adhesive layer 21. ing. Further, an adhesive layer 20 is laminated on the other surface of the polarizer 2.

Further, the set of polarizing plates shown in FIG. 1B has a front-side polarizing plate 101 and a back-side polarizing plate 201. In the front side polarizing plate 101, a protective film 10 is laminated on one surface of the polarizing element 2 via an adhesive layer 30, and a cured layer 1 of an active energy ray-curable adhesive is formed on the other surface of the polarizing element 2. It is laminated. Further, the pressure-sensitive adhesive layer 20 is laminated on the cured layer 1.

In the back-side polarizing plate 201, a protective film 11 is laminated on one surface of the polarizing element 2 via an adhesive layer 31, and a brightness improving film is formed on the other surface of the polarizer 2 via an adhesive layer 21. 40 are laminated. Further, the adhesive layer 20 is laminated on the protective film 11.

In the set of polarizing plates shown in FIG. 1, the pressure-sensitive adhesive layer 20 may be, for example, a pressure-sensitive adhesive layer for laminating a polarizing plate 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 are provided with a protective film only on one side of the polarizing element.

In the set of polarizing plates of the present invention, the shapes of the front-side polarizing plate and the back-side polarizing plate are not particularly limited, but may be rectangular. When the shape of the polarizing plate is 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 polarizing plates of the present invention, when the laminate provided with the front side polarizing plate and the back side polarizing plate is heated, the protective film possessed by the polarizing plate on the side warped in a concave shape is polarized at 85 ° C. When the tensile elastic modulus in the transmission axis direction of the plate and the tensile elastic modulus in the absorption axis direction of the polarizing plate at 85 ° C. are Et and Ea, respectively, the following equation (1) is satisfied. 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 further preferably 1.20 or more. Et / Ea may be 2.8 or less.

If the edge of the laminated body is warped toward the front polarizing plate side, the polarizing plate on the side that warps the concave shape is the front polarizing plate, and if the edge of the laminated body is warped toward the back polarizing plate side, it becomes concave. The polarizing plate on the warped side is the polarizing plate on the back side. A specific description will be given with reference to FIG. FIG. 3 shows a schematic cross section of a laminate in which a front-side polarizing plate 400 and a back-side polarizing plate 401 are bonded to a glass plate 70, respectively, after being heat-treated. In FIG. 3A, the polarizing plate on the side warped in the concave shape refers to the polarizing plate 401 on the back side, and in FIG. 3B, the polarizing plate on the side warped in the concave shape is the polarizing plate on the front side. Refers to 400. The polarizing plate on the side that warps the concave shape may be a front-side polarizing plate or a back-side polarizing plate. Since the back side polarizing plate often includes a stretched polarizing element and a similarly stretched brightness improving film, when the absorption axis direction of the back side polarizing plate is the long side direction, The shrinkage force when the back side polarizing plate is heated is often larger than that of the front side polarizing plate.

The shape of the polarizing plate and the shape of the glass plate when bonded to the glass plate are not particularly limited, but are preferably rectangular, and at this time, the front side polarizing plate and the back side polarizing plate can have the same size. .. When the polarizing plate is attached to the glass plate, the absorption axis of the front side polarizing plate and the absorption axis of the back side polarizing plate are attached so as to be orthogonal to each other. At this time, when the polarizing plate has a rectangular shape, the absorption axis of the front side polarizing plate is preferably parallel to the short side, and the absorption axis of the back side polarizing plate is preferably parallel to the long side.

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

The polarizing plate on the side warped in the concave shape may have protective films on both sides of the polarizer. In this case, it is preferable that at least one protective film satisfies the formula (1), from the liquid crystal cell in the polarizer. It is more preferable that the protective film laminated on the distant side satisfies the formula (1), and it is further preferable that any protective film satisfies the 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 set of polarizing plates 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 the polyvinyl alcohol-based resin film with a dichroic dye, and a dichroic dye. It is produced through a step of treating a polyvinyl alcohol-based resin film on which the above-mentioned material is adsorbed with an aqueous boric acid solution and a step of washing with water after the treatment with the aqueous boric acid solution.

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, and copolymers of vinyl acetate and other monomers copolymerizable. 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 also be used. 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.

A film made of a polyvinyl alcohol-based resin is used as a raw film for a polarizer. As a method for forming a film of a polyvinyl alcohol-based resin, a known method can be used for forming a film. The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, considering that the thickness of the obtained polarizing element is 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 the dimensional shrinkage of the obtained polarizer tends to be large.
On the other hand, when the film thickness of the raw film is 5 μm or less, the handleability at the time of stretching is lowered, and defects such as cutting tend to occur easily during manufacturing.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. If the uniaxial stretching is performed after staining, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Moreover, uniaxial stretching may be performed in these a plurality of steps.

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

As a method of dyeing the polyvinyl alcohol-based resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye is adopted. Specifically, iodine or a dichroic dye is used as the dichroic dye. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide for dyeing is usually adopted. The iodine content in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C.
The immersion time (staining time) in this 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 immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is usually adopted. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, preferably about 1 × 10 ^-3 to 1 part by weight. 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 (staining time) in this aqueous solution is usually about 10 to 1,800 seconds.

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

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

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

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

By the drying treatment, the moisture content of the polarizer is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. If the moisture content is less than 5% by weight, the polarizer loses its flexibility, and the polarizer may be damaged or broken after its drying.
If the water content exceeds 20% by weight, the thermal stability of the polarizer may be inferior.

Further, the stretching, dyeing, boric acid treatment, washing step, and drying step of the polyvinyl alcohol-based resin film in the polarizing element manufacturing step may 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 serving as a polarizer is formed by coating a base film with a polyvinyl alcohol-based resin.

Reducing the contraction force of the polarizer itself is also effective in reducing warpage in a high temperature environment, and the thickness of the polarizer provided by the front-side polarizing plate and the back-side polarizing plate is preferably 15 μm or less. It is more preferably 4 to 13 μm, and even more preferably 5 to 10 μm.

The size of the difference between the thickness of the polarizer provided on the front polarizing plate and the thickness of the polarizer provided on the back polarizing plate is preferably 5 μm or less, and may be 3 μm or less. When the protective film of the polarizing plate on the side that warps the concave shape satisfies the formula (1), the influence on the warp of the liquid crystal panel in a high temperature environment is further reduced by reducing the thickness difference of the polarizer in this way. be able to.

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

When the protective films are laminated on both sides of the polarizer, the same protective films may be used, or different protective films may be used. Further, the protective film on the front side polarizing plate and the protective film on the back side polarizing plate may be the same or different from each other.

The resin forming the protective film is not particularly limited, but for example, methyl methacrylate-based resin, polyolefin-based resin, cyclic olefin-based resin, polyvinyl chloride-based resin, cellulose-based resin, styrene-based resin, and acrylonitrile. -Butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene tephthalate resin, Examples thereof include a film made of a polyethylene teftale resin, a polysulfone resin, a polyether sulfone resin, a polyarylate resin, a polyamideimide resin, a polyimide resin and the like.

These resins can be used alone or in combination of two or more. In addition, these resins can be used after performing any appropriate polymer modification, and the polymer modification includes, for example, copolymerization, cross-linking, molecular end modification, stereoregularity control, and reaction between dissimilar polymers. Modifications such as mixing, including cases accompanied by.

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

The methyl methacrylate-based resin is 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 polymer having 100% by weight of methyl methacrylate 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 the polymerization, a polyfunctional monomer or a chain transfer agent can coexist if necessary.

The monofunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited, but for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2 methacrylic acid. -Methacrylic acids other than methyl methacrylate such as ethylhexyl and 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-acrylic acid Acrylic acid esters such as ethylhexyl and 2-hydroxyethyl acrylate; methyl 2- (hydroxymethyl) acrylate, methyl 3- (hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, and 2-( Hydroxyalkyl acrylic acid esters such as 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 acrylic acid and methacrylic acid; unsaturated acid anhydrides such as maleic acid anhydride and citraconic acid anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide can be mentioned. Such monomers may be used alone or in combination of two or more.

The polyfunctional monomer that can be copolymerized with methyl methacrylate is not particularly limited, but for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate. , Tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecaethylene glycol di (meth) acrylate and other ethylene glycols or their oligomers are esterified with acrylic acid or methacrylic acid. Those; those obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with acrylic acid or methacrylic acid; such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, and butanediol di (meth) acrylate. The hydroxyl groups of divalent alcohols esterified with acrylic acid or methacrylic acid; bisphenol A, the alkylene oxide adduct of bisphenol A, or the hydroxyl groups at both ends of these halogen substituents esterified with acrylic acid or methacrylic acid; Polyhydric alcohols such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid, and glycidyl acrylate or glycidyl methacrylate epoxy group added by ring opening to the terminal hydroxyl group of these polyhydric alcohols; succinic acid. , Adipic acid, terephthalic acid, phthalic acid, dibasic acids such as halogen substituents thereof, and alkylene oxide adducts thereof to which an epoxy group of glycidyl acrylate or glycidyl methacrylate is ring-opened; allyl (meth). Acrylate; and aromatic divinyl compounds such as divinylbenzene can be mentioned. Of these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

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

The polyethylene terephthalate resin means a resin in which 80 mol% or more of the repeating unit is composed of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. The other dicarboxylic acid components are not particularly limited, but are, for example, isophthalic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, and adipic acid. , Sebacic acid, 1,4-dicarboxycyclohexane and the like.

Other diol components are not particularly limited, but are propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. And so on.

If necessary, two or more of these dicarboxylic acid components and diol components can be used in combination. Further, hydroxycarboxylic acids such as p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid can also be used in combination. Further, as another copolymerization component, a dicarboxylic acid component containing a small amount of amide bond, urethane bond, ether bond, carbonate bond or the like, or a diol component may be used.

Methods for producing polyethylene terephthalate resins include a method of directly polycondensing terephthalic acid and ethylene glycol (and other dicarboxylic acids or other diols if necessary), a dialkyl ester of terephthalic acid and ethylene glycol (and, if necessary). A method of polycondensing after an ester exchange reaction with a dialkyl ester of another dicarboxylic acid or another diol, and an ethylene glycol ester of a terephthalic acid (and another dicarboxylic acid if necessary) (and, if necessary). A method of polycondensing (another diol ester) in the presence of a catalyst is adopted. Further, solid-phase polymerization can be performed as needed to improve the molecular weight or reduce the low molecular weight components.

Cyclic polyolefin-based resins are 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, ring-opening metathesis polymerization is carried out from cyclopentadiene and olefins or (meth) acrylic acid or esters thereof using norbornene or a derivative thereof obtained by a deal alder reaction as a monomer, followed by ring-opening metathesis polymerization. Resin obtained by hydrogenation; ring-opening metathesis polymerization is performed using tetracyclododecene or a derivative thereof obtained by a deal alder reaction from dicyclopentadiene and olefins or (meth) acrylic acid or esters thereof as a monomer. Resin obtained by subsequent hydrogenation; at least two monomers selected from norbornene, tetracyclododecene, derivatives thereof, and other cyclic olefin monomers are similarly ring-opened metathesis copolymerized and subsequently obtained by hydrogenation. Resins: Resins obtained by addition-copolymerizing a cyclic olefin such as norbornene, tetracyclododecene, or a derivative thereof with an aromatic compound having a chain olefin and / or a vinyl group.

Typical examples of chain polyolefin resins are polyethylene resins and polypropylene resins. Among them, a homopolymer of propylene or a copolymer obtained by copolymerizing propylene as a main component and a copolymerizable comonomer, for example, ethylene at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight. It is preferably used.

The polypropylene-based resin may contain an alicyclic saturated hydrocarbon resin. By containing the alicyclic saturated hydrocarbon resin, the retardation value can be easily controlled. The content of the alicyclic saturated hydrocarbon resin is preferably 0.1 to 30% by weight, more preferably 3 to 20% by weight, based on the polypropylene resin. 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, while if the content exceeds 30% by weight, the protective film There is a concern that bleed-out of the alicyclic saturated hydrocarbon resin may occur over time.

The cellulosic resin is obtained by substituting a part or all of hydrogen atoms in the hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (perforated tree pulp, coniferous tree pulp) with acetyl group, propionyl group and / or butyryl group. Also, it refers to a cellulose organic acid ester or a cellulose mixed organic acid ester. For example, those composed of acetic acid ester of cellulose, propionic acid ester, butyric acid ester, mixed ester thereof and the like can be mentioned. Among them, triacetyl cellulose film, diacetyl cellulose film, cellulose acetate propionate film, cellulose acetate butyrate film and the like are preferable.

As a 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, a method corresponding to each resin can be appropriately selected. Well, it is not particularly limited.
For example, a solvent casting method in which a resin dissolved in a solvent is cast on a metal band or a drum and the solvent is dried and removed to obtain a film, and a resin is heated and kneaded above its melting temperature and extruded from a die. A melt extrusion method is adopted in which a film is obtained by cooling. In this melt extrusion method, a single-layer film may be extruded, or a multilayer film may be extruded at the same time.

Commercially available products can be easily obtained for the films used as protective films. For methyl methacrylate-based resin films, the trade names are Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrylite (registered trademark), and Acryplen (registered trademark) (above, Mitsubishi Rayon Co., Ltd.), Delaglass (registered trademark) (Asahi Kasei Co., Ltd.), Paragrass (registered trademark), Comoglass (registered trademark) (above, Kuraray Co., Ltd.), and Acriviewer ( Registered trademark) (manufactured by Nippon Catalyst Co., Ltd.) and the like. For polyolefin resin films, the trade names include Zeonoa (registered trademark) (Zeon Corporation) and Arton (registered trademark) (JSR Corporation). For polyethylene terephthalate resin films, trade names include NovaClear (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (manufactured by Teijin Chemicals Ltd.). For polypropylene-based resin films, the trade names are FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Toyobo Co., Ltd.), and Toyobo Pyrene film. (Registered Trademark) (Toyobo Co., Ltd.), Trefan (Registered Trademark) (Toray Film Processing Co., Ltd.), Nihon Polyace (Nippon Polyace Co., Ltd.), and Taiko (Registered Trademark) FC (Futamura Chemical Co., Ltd.) (Made), etc. In the case of cellulosic resin films, the trade names include Fujitac (registered trademark) TD (manufactured by Fujifilm Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.).

The protective film and the protective film used in the present invention can be imparted with antiglare (haze). The method for imparting antiglare is not particularly limited, but for example, a method of mixing inorganic fine particles or organic fine particles in the raw material resin to form a film, or using the above-mentioned multi-layer extrusion, on one side. A method of forming a two-layer film from a resin in which fine particles are mixed and a resin in which fine particles are not mixed in the other, or a method of forming a three-layer film with the resin in which particles are mixed on the outside, and an inorganic substance on one side of the film. A method of coating a coating liquid obtained by mixing fine particles or organic fine particles with a curable binder resin and curing the binder resin to provide an antiglare layer or the like is adopted.

The protective film may also contain additives, if necessary. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a lightproofing agent, an impact resistance improving agent and the like.

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

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

The protective film of the front side polarizing plate may be further provided with functional layers such as a conductive layer, a hard coat layer, and a low reflection layer. Further, a resin composition having these functions can be selected as the binder resin constituting the antiglare layer.

A protective film satisfying the formula (1) can also be produced, for example, by stretching a resin film. The stretching method is not particularly limited, and may be a uniaxially stretched film obtained by laterally stretching after film formation, a biaxially stretched film obtained by longitudinally stretching after film formation, and then laterally stretching. The draw ratio can be, for example, 1.01 or more and 5.00 or less, and may be 1.01 or more and 3.00 or less.

(Brightness improvement film)
The backside polarizing plate preferably has a brightness improving film on the side of the polarizer far from the liquid crystal cell. The thickness of the luminance improving film is preferably 35 μm or less, and more preferably 30 μm or less.

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

Examples of the brightness improving film include an anisotropic reflection polarizer. Examples of the anisotropic reflective polarizer include an anisotropic multilayer thin 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 thin film include the trade name "APF" manufactured by 3M. Further, as the anisotropic reflection polarizer, a composite of a cholesteric liquid crystal layer and a λ / 4 plate can be mentioned. Examples of such a complex include the trade name "PCF" manufactured by Nitto Denko KK. Further, as the anisotropic reflection polarizer, a reflection grid polarizer can be mentioned. Examples of the reflection grid polarizer include a metal grid reflection polarizer in which the metal is finely processed to generate reflected polarized light even in the visible light region. Of these, a brightness improving film made of an anisotropic multilayer thin film is preferable.

A functional layer may be formed on the surface of the brightness improving film opposite to the surface to be bonded to the polarizing plate. Examples of the functional layer include a hard coat layer, an antiglare layer, a light diffusion layer, and a retardation layer having a retardation value of 1/4 wavelength, thereby improving the adhesion to the backlight tape. And the uniformity of the displayed image can be improved.

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

The pressure-sensitive adhesive layer for attaching the front-side polarizing plate to the liquid crystal cell and the pressure-sensitive adhesive layer for attaching the back-side polarizing plate to the liquid crystal cell may be the same or different from each other. You may use the one.

Further, the brightness improving film and the protective film or the polarizer can also be laminated by an adhesive layer. In FIG. 1, the pressure-sensitive adhesive layer 21 corresponds to this. The thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive is preferably 1 to 20 μm, 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, and natural rubbers. A polymer using a rubber-based polymer such as synthetic rubber as a base polymer can be appropriately selected and used. As the pressure-sensitive adhesive, those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesiveness, and excellent weather resistance and heat resistance are preferable.

In addition to this, various additives may be blended in the pressure-sensitive adhesive. Examples of the additive include a silane coupling agent and an antistatic agent.

(Adhesive layer)
Lamination of the protective film and the polarizer and the lamination of the brightness improving film and the polarizer can be performed, for example, by 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. Within this range, no floating or peeling occurs between the protective film or the brightness improving film and the polarizer, and a practically acceptable adhesive force can be obtained.

Adhesives include, for example, solvent-based adhesives, emulsion-type adhesives, pressure-sensitive adhesives, re-wet-sensitive adhesives, polycondensation-type adhesives, solvent-free adhesives, film-like adhesives, and hot-melt adhesives. And so on. Further, if necessary, an adhesive layer may be provided via the anchor coat layer.

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

The water-soluble adhesive can contain a cross-linking agent. As the type of the cross-linking agent, amine compounds, aldehyde compounds, methylol compounds, epoxy compounds, isocyanate compounds, polyvalent metal salts and the like are preferable, and epoxy compounds are particularly preferable. Commercially available products of the cross-linking agent include, for example, glyoxal and Sumire's resin 650 (30) manufactured by Taoka Chemical Co., Ltd.

Further, as another preferable adhesive, an active energy ray-curable adhesive composed of a resin composition that is cured by irradiation with active energy rays can be 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 cross-linking agent, and the like. Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and an oligomer derived from a photopolymerizable monomer. Examples of the photopolymerization initiator include those containing a substance that generates an active species such as a radical, a cation, or an anion by irradiation with an active energy ray such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

When an active energy ray-curable adhesive is used, the active energy ray-curable adhesive is obtained by adhering the polarizer and the protective film, performing a drying step as necessary, and then irradiating the active energy ray. Perform a curing step to cure. The light source of the active energy ray is not particularly limited, but ultraviolet rays having an emission distribution having a wavelength of 400 nm or less are preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, and a micro lamp. A wave-excited mercury lamp, a metal halide lamp, or the like can be used.

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

(Curing 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 that of a normal protective film, it is effective for making the polarizing plate thinner. The cured layer 1 of the active energy ray-curable resin composition in FIG. 1 corresponds to this.

In the set of polarizing plates of the present invention, the polarizing plate (particularly the front side polarizing plate) preferably has a cured layer of an active energy ray-curable resin composition on at least one surface of the polarizing element, and the liquid crystal in the polarizing element. It is more preferable to provide a cured layer of the active energy ray-curable resin composition on the side closer to the cell. In this case, since the distance between the polarizer and the liquid crystal cell can be reduced, the force for deforming the liquid crystal cell due to the contraction of the polarizer is reduced, and the influence on the warp of the liquid crystal panel in a high temperature environment is exerted. It can be made smaller. From this point of view, the distance from the surface of the polarizing element of the front-side polarizing plate near the liquid crystal cell to the surface of the liquid crystal cell near the polarizer of the front-side polarizing plate may be, for example, 30 μm or less. It is preferably 25 μm or less, and more preferably 25 μm 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, and even 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 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 may be different from each other.

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

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

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

The volatile liquid is, for example, water, a mixture of water and a hydrophilic liquid, and the like. The hydrophilic liquid preferably does not remain after the heat treatment in the second step, for example, methanol, ethanol, 1-butanol, tetrohydrofuran, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, etc. Examples thereof include formic acid and acetic acid. Additives such as antistatic agents may be added to the volatile liquid.

The resin forming the release film is not particularly limited, but for example, methyl methacrylate-based resin, polyolefin-based resin, cyclic olefin-based resin, polyvinyl chloride-based resin, cellulose-based resin, styrene-based resin, and acrylonitrile. -Butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene tephthalate resin, Examples thereof include a film made of a polyethylene teftale resin, a polysulfone resin, a polyether sulfone resin, a polyarylate resin, a polyamideimide resin, a polyimide resin and the like.

When the protective film is attached to the polarizer, plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) treatment, and Ken are applied to the polarizing element and / or the bonding surface of the protective film in order to improve the adhesiveness. Easy-adhesion processing such as conversion processing can be performed. It is also useful to perform the same treatment on the release film as the 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 irradiating the adhesive with active energy rays to cure the adhesive and then performing a heat treatment. When a water-based adhesive is used as the adhesive, the volatile liquid is volatilized and removed while adhering the polarizer and the protective film by heat treatment. It is preferable to use a water-based adhesive because the process can be simplified.

The drying temperature is preferably 30 to 90 ° C. If the temperature is lower than 30 ° C., it takes a long time to dry and the appearance may be deteriorated. If the drying temperature exceeds 90 ° C., the polarization performance of the polarizer may deteriorate due to heat. The drying time can be about 10 to 1000 seconds, preferably 60 to 750 seconds, and more preferably 150 to 600 seconds from the viewpoint of productivity.

By laminating a release film on the polarizer via a layer made of a volatile liquid, the heating temperature in this step can be raised to, for example, more than 60 ° C and 90 ° C or less. That is, even if the heating temperature is set high, in addition to being able to suppress the fracture of the polarizer, the high-temperature heating makes it possible to obtain a single-sided protective polarizing plate having a small shrinkage rate of the polarizer and therefore high dimensional stability. .. By reducing the shrinkage rate of the single-sided protective polarizing plate, the warp of the liquid crystal panel can be further reduced when a liquid crystal panel is manufactured using this polarizing plate.

To volatilize the volatile liquid to be used for laminating the polarizer and the release film by heating, the moisture permeability of at least one film of the protective film and the release film is preferably at 400g / m 2 ^· 24hr or more, 420 g / ^m is more preferably 2 · 24 hr or more. When the moisture permeation is in this range, the volatile liquid can be efficiently volatilized and removed in the subsequent second step, so that the 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 with 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 pressure-sensitive adhesive layer 20 on the cured layer 1, the pressure-sensitive adhesive layer 20 / active energy ray-curable resin composition cured layer 1 / polarizing element 2 / adhesive layer 30 / A front-side polarizing plate made of the protective film 10 is obtained.

(Manufacturing method of backside polarizing plate)
A release film, a polarizer 2, and a protective film 11 are prepared by the same method as the method for manufacturing a front-side polarizing plate, and a protective film is attached to one surface of the polarizer 2 via an adhesive, and polarized light is formed. A release film is laminated on the other surface of the child 2 via a volatile liquid. The polarizing element 2 and the protective film 11 are adhered to each other to remove the volatile liquid, and then the release film is peeled off to obtain a single-sided protective polarizing plate.

By laminating a brightness improving film on the protective film of the single-sided protective polarizing plate via an adhesive layer and laminating the pressure-sensitive adhesive layer 20 on the polarizer 2, the pressure-sensitive adhesive layer 20 / polarizer 2 / adhesive layer A backside polarizing plate composed of 31 / protective film 11 / adhesive layer 21 / brightness improving film 40 can be obtained.

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

(Manufacturing method of liquid crystal panel)
A liquid crystal panel can be obtained by laminating a set of polarizing plates of the present invention on both sides of a liquid crystal cell. It is preferable that the bonding is performed via the pressure-sensitive adhesive layer of the front-side polarizing plate and the pressure-sensitive adhesive layer of the back-side polarizing plate. Further, it is preferable that the front side polarizing plate is laminated on the visible side of the liquid crystal cell, and the back side polarizing plate is laminated on the back side of the liquid crystal cell. The liquid crystal panel of the present invention can be suitably applied to a liquid crystal display device. The front side polarizing plate is preferably bonded so that its absorption axis is substantially parallel to the short side direction of the liquid crystal cell, and the back side polarizing plate is preferably attached so that its absorption axis is substantially parallel to the long side direction of the liquid crystal cell. It is preferable to bond them so that they are. In the present specification, substantially parallel means, for example, that the angle formed is 0 ± 5 °, preferably 0 ± 1 °.

The liquid crystal cell has two cell substrates and a liquid crystal layer sandwiched between the substrate. The cell substrate is generally made of glass, but may be a plastic substrate. In addition, the liquid crystal cell itself used for the liquid crystal panel of the present invention can be composed of various cells used in this field. According to the set of polarizing plates of the present invention, even if the thickness of the liquid crystal cell is 0.4 mm or less, the warp can be remarkably reduced. In the present invention, the thickness of the liquid crystal cell includes the thickness of the liquid crystal layer and the thickness of a pair of substrates sandwiching the liquid crystal layer.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not defined by these examples. In the examples,% and parts representing the content or the amount used are based on weight unless otherwise specified. The evaluation method used in the examples is as follows.

(1) Thickness:
The measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) Tensile Elastic Modulus A test piece having a width of 15 mm and a length of 150 mm was cut out from the film. Next, with the upper and lower grippers of a tensile tester equipped with a constant temperature bath [AUTOGRAPH (registered trademark) AG-1S tester manufactured by Shimadzu Corporation], the distance between the grippers is 100 mm in the long side direction of the test piece. Both ends were sandwiched and pulled at a tensile speed of 50 mm / min in an environment of 85 ° C. to create a stress-strain curve, and the tensile elastic modulus at 85 ° C. was calculated.

(3) Moisture Permeability The moisture permeability was measured based on JIS Z 0208. The temperature and humidity conditions were 40 degrees and 90% RH.

(4) Discrimination of the polarizing plate on the side that warps the concave shape and measurement of the amount of warpage in a high temperature environment An evaluation sample having a configuration of a back side polarizing plate / glass plate / front side polarizing plate is placed in an environment of 85 ° C. After allowing to stand for 250 hours, the polarizing plate on the front side was placed on the measuring table of the two-dimensional measuring instrument with the polarizing plate on the upper side. As the two-dimensional measuring instrument, "NEXIV (registered trademark) VMR-12072" manufactured by Nikon Corporation was used. Next, the surface of the measuring table was focused and used as a reference, and 25 points on the evaluation sample surface were focused on, and the height from the reference focus was measured. The difference between the maximum and minimum heights at 25 measurement points is the amount of warpage, and the warp of the edge of the evaluation sample on the front side polarizing plate side is a positive warp, and the back side polarizing plate side is for evaluation. The warp of the edge of the sample was regarded as a negative warp. In the case of a positive warp, the polarizing plate on the side that warps the concave shape is the front polarizing plate, and in the case of a negative warp, the polarizing plate on the side that warps the concave shape is the back plate.

Specifically, the point 80 shown in FIG. 4 was set as the measurement point. The 25 points shown in FIG. 4 are points in a region 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. Further, in FIG. 4, reference numeral 402 indicates a polarizing plate, and 70 indicates a glass plate.

[Production Example 1] Preparation of Polarizer A polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) was uniaxially stretched about 4 times by dry stretching to maintain a tense state. After immersing it in pure water at 40 ° C. for 40 seconds, it is immersed in an aqueous solution with a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds for dyeing. It was. 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. Subsequently, after washing with pure water at 8 ° C. for 15 seconds, while holding at a tension of 300 N, the iodine was adsorbed and oriented on the polyvinyl alcohol film by drying at 60 ° C. for 50 seconds and then at 75 ° C. for 20 seconds. A polarizer having a thickness of 7 μm was obtained.

[Production Example 2] Preparation of water-based adhesive 3 parts by weight of carboxyl group-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd.] is dissolved in 100 parts by weight of water, and a water-soluble epoxy is dissolved in the aqueous solution. Add 1.5 parts by weight of a polyamide epoxy-based additive that is a resin [trade name "Smilase Resin (registered trademark) 650 (30)" obtained from Taoka Chemical Industry Co., Ltd., an aqueous solution with a solid content concentration of 30% by weight]. To prepare a water-based adhesive.

[Production Example 3] Active energy ray-curable resin composition As a 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) (TECHMORE VG3101L was mixed with 15 parts by mass and 2.25 parts by mass of triarylsulfonium hexafluorophosphate as a photocationic polymerization initiator to obtain an active energy ray-curable resin composition.

[Protective films A, B, C, D, E and release films F, G]
The following 5 types of protective films and 2 types of release films were prepared.
Protective film A: 25KCHCN-TC. A film obtained by saponifying a triacetyl cellulose film with a hard coat layer manufactured by Toppan Printing Co., Ltd. The thickness is 32 [mu] m, the moisture permeability was 450g ^/ m 2 · 24hr.
Protective film B: ZT12. Cyclic polyolefin resin film manufactured by Zeon Corporation. It has a thickness of 20 μm and is manufactured by lateral uniaxial stretching.
Protective film C: Zero Tuck (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®. Cyclic polyolefin resin film manufactured by Zeon Corporation. The thickness was 20 μm.
Release film F: TD80UL. Triacetyl cellulose film manufactured by FUJIFILM Corporation. The thickness is 80 [mu] m, the moisture permeability was 502g ^/ m 2 · 24hr.
Release film G: Polymethylmethacrylate resin film manufactured by Sumitomo Chemical Co., Ltd. The thickness is 80 [mu] m, the moisture permeability was ^50g / m 2 · 24hr.

[Example 1]
[Preparation of front side polarizing plate A]
The polarizer obtained in Production Example 1 was continuously conveyed, the protective film A was continuously unwound from the roll of the protective film A, and the release film G was continuously unwound from the roll of the release film G. Next, a water-based adhesive is injected between the polarizer and the protective film A, pure water is injected between the polarizer and the release film G, and the protective film A / water-based adhesive / is passed through a bonding roll. A laminated film composed of a polarizer / pure water / release film G was prepared. The laminated film is subsequently conveyed and heat-treated at 80 ° C. for 300 seconds in a drying furnace to dry the water-based adhesive and volatilize and remove the pure water interposed between the polarizing element and the release film G. , A single-sided protective polarizing plate with a release film was obtained. The release film G was peeled off from the single-sided protective polarizing plate with a release film to obtain a single-sided protective polarizing plate.

On the other hand, the active energy ray-curable resin composition prepared in Production Example 3 has a thickness of about 50 μm after curing on one side of a cyclic polyolefin resin film [ZEONOR (registered trademark), manufactured by Nippon Zeon Corporation]. It was coated so as to be 3 μm. The polarizer of the single-sided protective polarizing plate is attached to the coated surface, and from the cyclic polyolefin resin film side, an ultraviolet irradiation device [the lamp uses a "D valve" manufactured by Fusion UV Systems) is used to 280 nm to 320 nm. The active energy ray-curable resin composition was cured by irradiating ultraviolet rays so that the integrated light amount of the above was 200 mJ / cm ² . The cyclic polyolefin resin film was peeled off, and the cured layer of the active energy ray-curable resin composition was subjected to corona treatment. Adhesive layer on the cured product layer [Product name "#KT" manufactured by Lintec Corporation. The thickness was 20 μm. ] Was pasted together. In this way, a front side polarizing plate A composed of a protective film A / an aqueous adhesive layer / a polarizer / a cured layer of an active energy ray-curable resin composition / an adhesive layer was produced.

[Preparation of backside polarizing plate B]
The polarizer obtained in Production Example 1 was continuously conveyed, the protective film B was continuously unwound from the roll of the protective film B, and the release film F was continuously unwound from the roll of the release film F. Next, a water-based adhesive is injected between the polarizer and the corona-treated protective film B, and pure water is injected between the polarizer and the release film F, and the protective film B / water-based is passed through a bonding roll. A laminated film composed of an adhesive / a polarizer / pure water / a release film F was prepared. The laminated film is subsequently conveyed and heat-treated at 80 ° C. for 300 seconds in a drying furnace to dry the water-based adhesive and volatilize and remove the pure water interposed between the polarizer and the release film F. , A single-sided protective polarizing plate with a release film was obtained. The release film F was peeled from the single-sided protective polarizing plate with a release film to obtain a single-sided protective polarizing plate.

Adhesive layer on the protective film B of the single-sided protective polarizing plate [trade name "# L2" manufactured by Lintec Corporation. The thickness was 5 μm. ] Was affixed, and a brightness improving film [trade name "Advanced Polarized Film, Version 3 manufactured by 3M Co., Ltd., the thickness was 26 μm.]) Was further affixed on the pressure-sensitive adhesive layer. An adhesive layer [trade name "#KT" manufactured by Lintec Co., Ltd., which had a thickness of 20 μm] was attached to the film. In this way, the brightness improving film / adhesive layer / protective film B / water-based adhesive A backside polarizing plate B composed of a layer / a polarizer / an adhesive layer was produced.

[Preparation of evaluation sample]
The front side polarizing plate A is cut into a rectangular shape of 155.25 mm in the transmission axis direction and 95.90 mm in the absorption axis direction, and the back side polarizing plate B is cut into a rectangular shape of 155.25 μm in the absorption axis direction and 95.90 mm in the transmission axis direction. It was cut into a rectangular shape. Next, a glass plate having a thickness of 0.4 mm (manufactured by Corning Inc., product number: EAGLE XG (registered trademark)) is prepared so that the absorption axis of the front polarizing plate and the absorption axis of the back polarizing plate are orthogonal to each other. The front-side polarizing plate and the back-side polarizing plate were attached to the glass plate via the respective pressure-sensitive adhesive layers.

The amount of warpage of the obtained evaluation sample was measured in a high temperature environment. The results are shown in Table 1. The polarizing plate on the side warped in the concave shape is the back side polarizing plate, and the protective film B has a tensile elastic modulus in the transmission axis direction of the back side polarizing plate at 85 ° C., and the absorption axis of the back side polarizing plate. The tensile modulus in the direction was 1786 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 was manufactured in the same manner as the back side polarizing plate B except that the protective film B was changed to the protective film C and the release film F was changed to the release film G in the preparation of the back side polarizing plate B. A backside polarizing plate C composed of a brightness improving film / adhesive layer / protective film C / water-based adhesive layer / polarizer / adhesive layer was produced. Then, an evaluation sample was prepared in the same manner as in Example 1 except that the back side polarizing plate B was changed to the back side polarizing plate C of this example.

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

[Example 3]
As the front-side polarizing plate, the front-side polarizing plate A used in Example 1 was used. The back side polarizing plate was manufactured in the same manner as the back side polarizing plate C except that the protective film C was changed to the protective film D in the production of the back side polarizing plate C, and the brightness improving film / adhesive layer / protection was produced. A backside polarizing plate D composed of a film D / an aqueous adhesive layer / a polarizer / an adhesive layer was produced. Then, an evaluation sample was prepared in the same manner as in Example 1 except that the back side polarizing plate B was changed to the back side polarizing plate D of this example.

The amount of warpage of the obtained evaluation sample was measured in a high temperature environment. The results are shown in Table 1. The polarizing plate on the side warped in the concave shape is the back side polarizing plate, and the protective film D has a tensile elastic modulus in the transmission axis direction of the back side polarizing plate at 85 ° C., and the absorption axis of the back side polarizing plate. The tensile modulus in the direction was 3031 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 was manufactured in the same manner as the back side polarizing plate B except that the protective film B was changed to the protective film E in the production of the back side polarizing plate B, and the brightness improving film / adhesive layer / protective film was produced. A backside polarizing plate E composed of E / water-based adhesive layer / polarizer / adhesive layer was produced. Then, an evaluation sample was prepared in the same manner as in Example 1 except that the back side polarizing plate B was changed to the back side polarizing plate E of this example.

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

As shown in Table 1, when the tensile elastic moduli Et and Ea of the protective film on the polarizing plate on the side warped in the concave shape satisfy Et / Ea ≧ 1.1, the amount of warpage in a high temperature environment can be reduced. It was.

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

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 improving film 402 Polarizing plate 100, 101, 400 Front side polarizing plate 200, 201, 401 Polarizing plate on the back side 300 Liquid crystal cell 70 Glass plate 80 Measuring point

Claims (6)

It has a front-side polarizing plate arranged on the visual side of the liquid crystal cell and a back-side polarizing plate arranged on the back side of the liquid crystal cell.
The absorption axis of the front side polarizing plate is parallel to the short side,
The absorption axis of the back side polarizing plate is parallel to the long side,
Both the front-side polarizing plate and the back-side polarizing plate have a polarizer made of a polyvinyl alcohol-based resin film .
Before SL front-side polarizing plate has a pressure-sensitive adhesive layer, the adhesive layer is an adhesive layer for laminating the polarizer to the liquid crystal cell,
The front-side polarizing plate is a single-sided protective polarizing plate having a protective film on only one side of the polarizer.
The back side polarizing plate has a brightness improving film, and the brightness improving film is a stretched film.
The back-side polarizing plate is a single-sided protective polarizing plate having a protective film on only one side of the polarizer.
The protective film included in the back-side polarizing plate has a thickness of 20 μm to 25 μm.
The distance from the surface of the polarizing element of the front-side polarizing plate close to the liquid crystal cell to the surface of the liquid crystal cell close to the polarizer of the front-side polarizing plate is 30 μm or less.
A laminate in which the front-side polarizing plate and the back-side polarizing plate are bonded to a glass plate so that the absorption axis of the front-side polarizing plate and the absorption axis of the back-side polarizing plate are orthogonal to each other is formed at 85 ° C. The protective film on the polarizing plate on the side where the laminate warps in a concave shape when heated for 250 hours is the tensile elasticity in the polarizing plate transmission axis direction at 85 ° C. and the polarizing plate absorption axial direction at 85 ° C. When the tensile elasticity is Et and Ea, respectively, the following equation (1) is satisfied.
The polarizing plate on the side warped in the concave shape is the back side polarizing plate.
A set of polarizing plates with a polarizer thickness of 5 to 10 μm.
1.23 ≧ Et / Ea ≧ 1.13 (1) The set of polarizing plates according to claim 1, wherein the front-side polarizing plate and the back-side polarizing plate have a rectangular shape with a diagonal of 15 inches or less. The set of polarizing plates according to claim 2, wherein the front-side polarizing plate includes a cured layer of an active energy ray-curable resin composition on at least one surface of the polarizing element. The front-side polarizing plate, a set of polarizing plate according to claim 2 or 3 also cormorants one surface comprising a cured layer of an active energy ray curable resin composition. The set of polarizing plates according to any one of claims 2 to 4, wherein the magnitude of the difference between the thickness of the polarizing element provided on the front side polarizing plate and the thickness of the polarizer provided on the back side polarizing plate is 5 μm or less. A liquid crystal panel comprising the set of the polarizing plate according to any one of claims 1 to 5 and a liquid crystal cell, wherein the thickness of the liquid crystal cell is 0.4 mm or less.

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