JP4800995B2 - Polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to a polarizing plate and a liquid crystal display device.

  Recently, liquid crystal display devices (hereinafter referred to as LCDs) are widely used in place of CRTs because of their thinness, light weight, and low power consumption. The demand for polarizing plates is rapidly increasing with the spread of LCDs. The field of use is also expanding from small products such as conventional calculators and watches to large products such as automotive instruments, PC monitors, and televisions.

  Since the display device is often in use for a long time at all times, the polarizing plate has long-term durability so that the image quality of the LCD is not deteriorated even in long-term use in an environment having temperature and humidity changes. It has come to be required.

In the polarizing plate, a polarizing plate protective film (hereinafter sometimes referred to as a protective layer) is bonded to both sides or one side of a polarizing film having polarizing ability through an adhesive layer.
As a material of the polarizing film, polyvinyl alcohol (hereinafter sometimes referred to as PVA) is mainly used. The polarizing film is formed by stretching and further crosslinking with a boron compound.
As the protective layer, cellulose triacetate (hereinafter sometimes referred to as TAC) is mainly used because it is optically transparent and has low birefringence and a smooth surface.

  However, when cellulose triacetate is used as a protective layer, display image unevenness may occur due to changes in the size of the polarizing film due to changes in temperature and humidity during long-term use, and improvements are desired.

As means for solving these problems, proposals have been made to use a film with low moisture permeability as a protective film (see Patent Document 1), and to provide a layer having low moisture permeability on cellulose acylate. (See Patent Document 2).
However, these have not been sufficiently described in terms of moisture permeability, and it has been found that the improvement effect is not always sufficient for display unevenness that occurs under various temperature and humidity environment conditions. In particular, there is a problem that the effect of improvement cannot be sufficiently obtained with respect to display unevenness and durability under high temperature and low humidity.

In addition, as a method for solving the above-described problem, it has been reported that stress relaxation is imparted by adding a plasticizer or the like to the pressure-sensitive adhesive to suppress peripheral light leakage (see Patent Document 3).
However, as the size of liquid crystal televisions rapidly increases and the durability test conditions of panel manufacturers become severe, the method disclosed in Patent Document 3 suppresses light leakage at the peripheral portion to a level that is practically acceptable. Is no longer possible.
Furthermore, it seems that rapid dehydration and moisture absorption occur when the environment changes suddenly to high temperature and low humidity or high temperature and high humidity conditions. However, this also improves because there is a failure such as peeling at the adhesive part. Is strongly desired.

JP-A-10-101907 JP-A-62-161103 Japanese Patent Laid-Open No. 9-137143

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention is a liquid crystal display which is excellent in durability at high temperature and low humidity and high temperature and high humidity, hardly causes damage due to peeling between members at the time of environmental change, and light leakage in the peripheral portion is remarkably reduced. An object is to provide an apparatus.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by combining a pressure-sensitive adhesive having predetermined characteristics with a low moisture-permeable protective film for polarizing plates.

This invention is based on the said knowledge by the present inventors, and the means for solving the said subject are as follows. That is,
<1> A polarizing plate having a polarizer and protective films provided on both surfaces of the polarizer,
At least one of the protective films is a low moisture-permeable protective film, and an adhesive layer is formed on the other protective film,
The pressure-sensitive adhesive layer is fixed to a substrate with an adhesive area of 10 mm × 25 mm through the pressure-sensitive adhesive layer, and the strain amount A of the pressure-sensitive adhesive layer obtained from a creep test in which a load of 1 kg is applied at 80 ° C. for 1 hour is 100 μm or more. 3,000 μm or less,
The low moisture-permeable protective film has a moisture permeability at 60 ° C. and 40% relative humidity of 100 g / m ² · day or less.
<2> The polarizing plate according to <1>, wherein the pressure-sensitive adhesive layer has a strain amount A of 700 μm or more and 1,300 μm or less.
<3> The polarized light according to any one of <1> to <2>, wherein the protective film has at least a transparent support and a coating layer made of a resin containing a repeating unit derived from a chlorine-containing vinyl monomer. It is a board.
<4> The polarizing plate according to any one of <1> to <3>, wherein the protective film includes at least a transparent support and a coating layer containing a vinyl alcohol resin.
<5> The polarizing plate according to <4>, wherein the coating layer contains a layered inorganic compound.
<6> The polarizing plate according to any one of <3> to <5>, wherein the transparent support is made of cellulose acylates.
<7> The polarizing plate according to any one of <1> to <6>, wherein the low moisture-permeable protective film is made of a resin having an alicyclic structure.
<8> The polarizing plate according to any one of <1> to <7>, wherein at least one of a hard coat layer having hard coat properties and an antireflection layer is formed on a protective film.

  <9> A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 8 and a liquid crystal cell.

  According to the present invention, a polarizing plate which is excellent in durability at high temperature and low humidity and at high temperature and high humidity, hardly causes damage due to peeling between members at the time of environmental change, and a liquid crystal display in which light leakage in the peripheral portion is remarkably reduced. An apparatus can be provided.

  Hereinafter, although the polarizing plate and liquid crystal display device of this invention are demonstrated in detail, the polarizing plate and liquid crystal display device of this invention are not restricted to the form of the following description.

<Adhesive layer>
First, the pressure-sensitive adhesive layer of the present invention (hereinafter sometimes referred to as pressure-sensitive adhesive) will be described in detail.
The strain amount (A: μm) of the pressure-sensitive adhesive layer obtained from a creep test in which a polarizing plate is fixed to a substrate with an adhesive area of 10 mm × 25 mm through a pressure-sensitive adhesive layer and a load of 1 kg is applied at 80 ° C. for 1 hour is 100 μm or more 3 1,000 μm or less, preferably 400 μm or more and 2,000 μm or less, more preferably 500 μm or more and 1,300 μm or less, and particularly preferably 700 μm or more and 1,300 μm or less.
Tg of the pressure-sensitive adhesive layer is preferably −40 ° C. ≦ Tg ≦ −10 ° C., more preferably −20 ° C. ≦ Tg ≦ −10 ° C.

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more and 100 μm or less, more preferably 1 μm or more and 50 μm or less, and particularly preferably 1 μm or more and 20 μm or less.
The gel fraction of the pressure-sensitive adhesive layer is preferably 70% or more and 95% or less. If the gel fraction is too low, polarizing plate processability is lowered.
If the adhesive strength of the pressure-sensitive adhesive is too high, the re-peelability deteriorates. Therefore, the adhesive strength in the 90 ° peel test is preferably 10 N / 25 mm or less.

  An appropriate pressure-sensitive adhesive can be used for forming the pressure-sensitive adhesive layer, and there is no particular limitation on the type thereof. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Cellulose-based adhesives and the like can be mentioned.

  Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

The acrylic pressure-sensitive adhesive is based on an acrylic polymer having a monomer unit of (meth) acrylic acid alkyl ester as a main skeleton.
In addition, (meth) acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and (meth) of the present invention has the same meaning.
Examples of the (meth) acrylic acid alkyl ester constituting the main skeleton of the acrylic polymer include linear or branched alkyl groups having 2 to 20 carbon atoms.
For example, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, (meth) Examples thereof include lauryl acrylate.

In the acrylic polymer, one or more kinds of copolymerization monomers can be introduced by copolymerization for the purpose of improving adhesiveness and heat resistance.
Specific examples of such a copolymerization monomer include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 6 Hydroxyl group-containing monomers such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride Substance-based material -; Caprolactone adduct of acrylic acid; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2 methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxy Examples thereof include sulfonic acid group-containing monomers such as naphthalene sulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

  In addition, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomer; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid t-butylaminoethyl and other (meth) acrylic acid alkylaminoalkyl monomers; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( (Meta) acryloyl- - oxy octamethylene succinimide, also including succinimide-based monomers such as N- acryloyl morpholine as a monomer Examples of the reforming purposes.

  Further, as modifying monomers, vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N- Vinyl monomers such as vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; (Meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxy Glycol acrylic ester monomers such as polypropylene glycol; acrylic acid ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate can also be used. .

  Among these, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used from the viewpoints of adhesion to a liquid crystal cell and durability for optical film applications. These monomers serve as reaction points with the crosslinking agent.

  The pressure-sensitive adhesive layer in the present invention is preferably obtained from a pressure-sensitive adhesive composition containing an acrylic polymer obtained by copolymerizing butyl acrylate and methyl acrylate. The ratio of butyl acrylate to methyl acrylate in the copolymer is preferably 50% or more for butyl acrylate.

  The average molecular weight of the acrylic polymer is not particularly limited, but the mass average molecular weight is preferably about 300,000 to 2.5 million. The acrylic polymer can be produced by various known methods. For example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by mass.

  The pressure-sensitive adhesive is preferably a pressure-sensitive adhesive composition containing a crosslinking agent. Examples of the polyfunctional compound that can be incorporated into the pressure-sensitive adhesive include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a peroxide crosslinking agent. These crosslinking agents can be used alone or in combination of two or more. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound to be covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

The mixing ratio of the base polymer such as the acrylic polymer and the crosslinking agent is not particularly limited. Usually, about 0.001-20 mass parts of crosslinking agents (solid content) are preferable with respect to 100 mass parts of base polymer (solid content).
The pressure-sensitive adhesive layer in the present invention preferably contains 0.02 to 10 parts by mass of an isocyanate-based crosslinking agent with respect to 100 parts by mass of the base polymer (solid content), and 0.1 to 2 parts by mass. .5 parts by mass or less is more preferable.

  Furthermore, the pressure-sensitive adhesive may include a tackifier, a plasticizer, a glass fiber, glass beads, a metal powder, other inorganic powders, a pigment, a colorant, a filler, an antioxidant, if necessary. Various additives may be used as appropriate, such as an agent, an ultraviolet absorber, a silane coupling agent, and the like without departing from the object of the present invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  As the additive, a silane coupling agent is suitable, and the silane coupling agent (solid content) is preferably about 0.001 to 10 parts by mass with respect to 100 parts by mass of the base polymer (solid content). It is preferable to mix about 005-5 mass parts. As the silane coupling agent, those conventionally known can be used without particular limitation. For example, epoxy groups such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane -Containing silane coupling agent, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine Amino group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, (meth) acrylic group-containing silane coupling agents such as 3-methacryloxypropyltriethoxysilane, and isocyanates such as 3-isocyanatopropyltriethoxysilane It can be exemplified containing silane coupling agent.

  In forming the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer may be formed after forming the antistatic layer.

Below, the protective film for polarizing plates of this invention is demonstrated in detail.
[Low moisture permeability protective film]
The low moisture-permeable protective film for polarizing plates of this invention makes a polymer film a base material. In this case, as long as the moisture permeability of the present invention is satisfied, the protective film may be a polymer film itself, or the polymer film may be a base material for the protective film, and a functional layer may be further laminated. There may be a plurality of sex layers.

[Transparent substrate film]
As the transparent substrate film used in the present invention, a cellulose acylate film is preferably used because it is optically uniform, has a smooth surface, and has good secondary workability in producing a polarizing plate. The
The cellulose acylate used in the present invention is an aliphatic carboxylic acid ester or aromatic carboxylic acid ester having about 2 to 22 carbon atoms, and is particularly preferably a lower fatty acid ester of cellulose.
The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate and the like, and JP-A-10-45804 Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in JP-A-8-231761, U.S. Pat. No. 2,319,052 can be used. Alternatively, esters of aromatic carboxylic acid and cellulose described in JP-A No. 2002-179701, JP-A No. 2002-265639, and JP-A No. 2002-265638 are also preferably used.
Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate described later. In addition, these cellulose esters can also be mixed and used.

The degree of substitution (DS) of cellulose acylate means the proportion of acylation of three hydroxyl groups present in the cellulose structural unit (glucose having β1 → 4 glycosidic bonds). The degree of substitution can be calculated by measuring the amount of bound fatty acid per unit mass of cellulose. The measurement method is carried out according to ASTM-D817-91.
The cellulose acylate of the present invention balances the humidity dependence of the retardation and the dimensional stability by appropriately balancing the hydrophobicity of the acyl group and the hydrophilicity of the hydroxyl group. That is, if the alkyl chain in the acyl group is too short on average and / or the hydroxyl group ratio is too high, the humidity dependency of retardation becomes large.
On the other hand, if the alkyl chain in the acyl group is too long on average and / or the hydroxyl group ratio is too high, Tg is lowered and the dimensional stability is deteriorated.
Accordingly, the cellulose triacetate that is preferably used in the present invention preferably has a degree of acetylation of 2.83 or more and 2.91 or less and no other acyl group having 3 or more carbon atoms. The degree of acetylation is more preferably 2.84 or more and 2.89 or less.

In addition, cellulose ester other than cellulose triacetate has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and the substitution degree of propionyl group is Y, the following formula ( It is a cellulose ester that satisfies both a) and formula (b) at the same time.
2.6 ≦ X + Y ≦ 2.9 Equation (a)
0 ≦ X ≦ 2.5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (b)
Among the cellulose esters satisfying the above formula (a) and formula (b), cellulose acetate propionate having 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 (total acyl group substitution degree = X + Y) ) Is preferred. The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

  30-120 micrometers is preferable and, as for the thickness of a transparent base film, 40-80 micrometers is more preferable. If the thickness of the base film is equal to or greater than the lower limit, problems such as a decrease in film strength are unlikely to occur. If the thickness is equal to or less than the upper limit, the mass increases excessively, particularly for large televisions of 20 inches or more. It is preferable because adverse effects such as disadvantages are less likely to occur.

As the polymer film, a resin containing an alicyclic structure is also preferably used.
Specific examples of the resin containing an alicyclic structure include (1) a norbornene polymer, (2) a polymer of a monocyclic olefin, (3) a polymer of a cyclic conjugated diene, and (4) a vinyl fat. Examples thereof include cyclic hydrocarbon polymers and hydrides of (1) to (4) above. Among these, from the viewpoints of heat resistance and mechanical strength, a norbornene polymer hydride, a vinyl alicyclic hydrocarbon polymer, and a hydride thereof are preferable.

[Monomer copolymerizable with chlorine-containing vinyl monomer]
In general, examples of the chlorine-containing vinyl monomer include vinyl chloride and vinylidene chloride. The chlorine-containing polymer can be obtained by copolymerizing these vinyl chloride or vinylidene chloride monomers with a monomer copolymerizable therewith.

  Examples of the copolymerizable monomer include olefins, styrenes, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, itaconic acid diesters, maleic acid esters, fumaric acid diesters, N- Examples thereof include monomers selected from alkylmaleimides, maleic anhydride, acrylonitrile, vinyl ethers, vinyl esters, vinyl ketones, vinyl heterocyclic compounds, glycidyl esters, unsaturated nitriles, unsaturated carboxylic acids and the like.

Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene and the like.
Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, trifluoromethyl styrene, vinyl. And benzoic acid methyl ester.

Specific examples of acrylic esters and methacrylic esters include the following.
Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, 2-phenoxyethyl acrylate, chloroethyl acrylate, Cyanoethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, oct Methacrylate, benzyl methacrylate, cyanoacetoxyethyl methacrylate, chlorobenzyl methacrylate, sulfopropyl methacrylate, N-ethyl-N-phenylaminoethyl methacrylate, 2-methoxyethyl methacrylate, 2- (3-phenylpropyloxy) ethyl methacrylate, dimethylamino Phenoxyethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 3 -Chloro-2-hydro Cypropyl methacrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, diethylene glycol monoacrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, 5-hydroxypropyl Methacrylate, diethylene glycol monomethacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate.

Specific examples of vinyl ethers include the following.
Methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl ether, dimethylaminoethyl Vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthranyl ether .

Specific examples of the vinyl esters include the following.
Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl dimethyl propionate, vinyl ethyl butyrate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, Vinyl butoxy acetoacetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenyl butyrate, vinyl cyclohexyl carboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate.

  Acrylamides include acrylamide, methylacrylamide, ethylacrylamide, propylacrylamide, butylacrylamide, t-butylacrylamide, cyclohexylacrylamide, benzylacrylamide, hydroxymethylacrylamide, methoxyethylacrylamide, dimethylaminoethylacrylamide, phenylacrylamide, dimethylacrylamide, and diethyl. Examples include acrylamide, β-cyanoethyl acrylamide, and N- (2-acetoacetoxyethyl) acrylamide.

  Examples of methacrylamides include methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, benzyl methacrylamide, hydroxymethyl methacrylamide, methoxyethyl methacrylamide , Dimethylaminoethylmethacrylamide, phenylmethacrylamide, dimethylmethacrylamide, diethylmethacrylamide, β-cyanoethylmethacrylamide, N- (2-acetoacetoxyethyl) methacrylamide and the like.

  Further, acrylamides having a hydroxyl group can also be used, and examples thereof include N-hydroxymethyl-N- (1,1-dimethyl-3-oxo-butyl) acrylamide, N-methylolacrylamide, and N-methylol. Examples include methacrylamide, N-ethyl-N-methylol acrylamide, N, N-dimethylol acrylamide, N-ethanol acrylamide, N-propanol acrylamide, N-methylol acrylamide, and the like.

  Examples of the itaconic acid diesters include dimethyl itaconate, diethyl itaconate, and dibutyl itaconate. Examples of maleic acid diesters include diethyl maleate, dimethyl maleate, and dibutyl maleate. Examples of the fumaric acid diesters include diethyl fumarate, dimethyl fumarate, dibutyl fumarate and the like.

Examples of vinyl ketones include methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, and the like. Examples of the vinyl heterocyclic compound include vinyl pyridine, N-vinyl imidazole, N-vinyl oxazolidone, N-vinyl triazole, and N-vinyl pyrrolidone. Examples of glycidyl esters include glycidyl acrylate and glycidyl methacrylate. Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile. Examples of N-alkylmaleimides include N-ethylmaleimide and N-butylmaleimide.

Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like, and further anhydrides such as fumaric acid, itaconic acid and maleic acid.
Two or more kinds of these copolymerizable monomers may be used.

  Examples of the chlorine-containing polymer in the present invention include JP-A-53-58553, JP-A-55-43185, JP-A-57-139109, JP-A-57-139136, JP-A-60. -235818, JP-A 61-108650, JP-A 62-256871, JP-A 62-280207, JP-A 63-256665, and the like.

  The proportion of the chlorine-containing vinyl monomer in the chlorine-containing polymer is preferably from 50 to 99 mass%, more preferably from 60 to 98 mass%, still more preferably from 70 to 97 mass%. If the ratio of the chlorine-containing vinyl monomer is 50% or more, problems such as deterioration of moisture permeability will not occur, and if it is 99% or less, solubility in various solvents is obtained, which is preferable. .

Chlorine-containing polymers are available from Asahi Kasei Chemicals Corporation and Kureha Chemical Corporation. The following are listed as available from Asahi Kasei Chemicals Corporation.
“Saran Resin R241C”, “Saran Resin F216”, “Saran Resin R204”, “Saran Latex L502”, “Saran Latex L529B”, “Saran Latex L536B”, “Saran Latex L544D”, “Saran Latex L549B”, “Saran Latex L551B” “Saran Latex L557”, “Saran Latex L561A”, “Saran Latex L116A”, “Saran Latex L411A”, “Saran Latex L120”, “Saran Latex L123D”, “Saran Latex L106C”, “Saran Latex L131A”, “ “Saran Latex L111”, “Saran Latex L232A”, “Saran Latex L321B”. Saran resin F216 is more preferably used because it is soluble in ketone solvents (such as methyl ethyl ketone and cyclohexanone).
In addition, since Saran Resin R204 has high crystallinity, the moisture permeability of the coating layer can be lowered, and it is difficult to dissolve in a solvent when a layer having a hard coat property described later is applied, and a layer having a hard coat property. It is more preferably used because it is difficult to make a mixed region with.

[Coating layer formed from resin comprising vinyl alcohol polymer or resin containing layered inorganic compound in vinyl alcohol polymer composition]
1- (1) Vinyl alcohol polymer Examples of the vinyl alcohol polymer constituting the coating layer include homopolymers such as polyvinyl alcohol (PVA) and ethylene-vinyl alcohol copolymers (EVOH). It can be illustrated. In addition, these vinyl alcohol polymers may be partially carbonyl-modified, silanol-modified, epoxy-modified, acetoacetyl-modified, amino-modified or ammonium-modified, and a part thereof is a diacetone acrylamide unit. You may use the copolymer containing these. Various vinyl alcohol polymers can be used alone or in combination of two or more.

  The saponification degree of the vinyl alcohol polymer can be selected from the range of 80 mol% or more, but is preferably 96 mol% or more, more preferably 99 mol% or more. The degree of polymerization of the vinyl alcohol polymer is preferably from 200 to 5,000, preferably from 400 to 5,000, more preferably from about 500 to 3,000, from the viewpoint of moisture permeability and coatability.

1- (2) Other components In the present invention, as a component of the resin composition, a vinyl alcohol polymer crosslinking agent can be further added to the vinyl alcohol polymer and the layered inorganic compound described later. The water resistance of the adhesive layer can be improved.
The cross-linking agent that can be used for this purpose is not particularly limited, and any known cross-linking agent can be preferably used. Examples of crosslinking agents include phenolic resin, melamine resin, urea resin, polyamide polyurea, dimethylol urea, dimethylol melamine, polyvalent epoxy compound, dialdehyde compound, polyvalent isocyanate resin, aziridine compound, polyamidoamine epichlorohydrin compound, activity Vinyl compound, dicarbonate compound, hydrazino group-containing compound (other carboxylic acid polyhydrazide compound), colloidal silica, zirconium salt, polyvalent metal salt, boric acid, phosphoric acid, polyacrylic acid, dicarboxylic acid, adipic acid anhydride And titanium compounds such as succinic anhydride, tetraisopropyl titanate, diisopropoxybis (acetylacetone) titanate, and other coupling agents such as 3-glycidpropylmethoxysilane, The use of such a radical generating agent such as id are possible. It is also possible to add a catalyst and other additives for promoting the crosslinking reaction.

  The addition amount of the crosslinking agent is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more in terms of (crosslinking agent / (vinyl alcohol polymer + crosslinking agent)). . In the case where the mass ratio of the crosslinking agent to both the PVA polymer and the crosslinking agent is less than 0.5% by mass, the effect is not exhibited by adding the crosslinking agent. The mass ratio of the crosslinking agent to both the vinyl alcohol polymer and the crosslinking agent is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less. Since some crosslinking agents such as aldehyde-based compounds turn yellow by heat, it is necessary to reduce the amount of such crosslinking agents to be within an allowable range by reducing the amount of addition.

1- (3) Layered inorganic compound In order to improve moisture permeability, it is preferable to disperse the layered inorganic compound in the resin layer. The layered inorganic compound in the present invention is an inorganic compound having a structure in which unit crystal layers are laminated and exhibiting a property of swelling or cleaving by coordinating or absorbing a solvent between the layers.
Examples of such inorganic compounds include swellable hydrous silicates such as smectite group clay minerals (montmorillonite, beidellite, nontronite, saponite, hectorite, soconite, stevensite, etc.), vermiculite group clay minerals (vermiculite, etc.) , Kaolin-type minerals (such as halloysite, kaolinite, enderite, dickite), phyllosilicates (talc, pyrophyllite, mica, margarite, muscovite, phlogopite, tetrasilic mica, teniolite, etc.), jamonite group Examples thereof include minerals (such as antigolite) and chlorite group minerals (such as chlorite, cookite, and nanthite). These swellable layered inorganic compounds may be natural or synthetic.
Such a layered inorganic compound may be one obtained by subjecting the layered inorganic compound as described above to an organic treatment.
The organic treatment can be made organic by adding a compound having an onium ion to the layered inorganic compound. Specifically, by adding an organic agent composed of an organic onium ion to the layered inorganic compound and treating it. It is done.
The organic onium ion is not particularly limited, but monoalkyl primary to quaternary ammonium ions, dialkyl secondary to tertiary ammonium ions, trialkyl tertiary to quaternary ammonium ions, A tetraalkylammonium ion etc. can be mentioned, As an alkyl chain length, a C4-C30 thing is preferable, Furthermore, 6-20, Especially 8-18 are preferable.
In addition to the alkyl chain, primary to quaternary ammonium ions having a polyethylene glycol chain and having ethylene oxide as a structural unit (monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol ammonium ions may be used) may be used. Alternatively, it may be a primary to quaternary ammonium ion of a higher fatty acid, a primary to quaternary ammonium ion of a higher fatty acid ester, or a primary to quaternary ammonium ion of a higher alcohol. Moreover, you may have these multiple types of molecular chains. Further, it may be a secondary to quaternary ammonium ion obtained by adding these molecular chains to a fatty acid acid.
Moreover, these layered inorganic compounds can be used individually or in combination of 2 or more types.

The swellable layered inorganic compound is preferably finely divided from the viewpoint of achieving both gas barrier properties and adhesion between the substrate and the gas barrier layer.
The swellable layered inorganic compound that has been microparticulated is usually plate-shaped or flat-shaped, and the planar shape is not particularly limited, and may be an amorphous shape. The average particle diameter of the swellable layered inorganic compound that has been microparticulated (planar average particle diameter measured by a light scattering method or the like) is preferably, for example, 0.1 to 10 μm, and more preferably 0.5 to 8 μm. 0.8 to 6 μm is particularly preferable. If the particle diameter is smaller than this range, the effect of reducing moisture permeability is not sufficient, and if the particle diameter is large, an increase in haze value, an increase in surface roughness, and the like are not preferable.
The density | concentration of an inorganic compound is 3-60 mass%, Preferably it is 3-50 mass%, More preferably, it is 3-40 mass%. If it is less than this range, the effect of reducing moisture permeability is not sufficient, and if it is too much, an increase in haze value, deterioration of brittleness and the like occur, which is not preferable.

The layered inorganic compound is dispersed in the binder in a state where the interlayer is properly cleaved, thereby extending the diffusion path length of water molecules or clusters to reduce moisture permeability. Therefore, a dispersion treatment for obtaining a state where each layer of the layered inorganic compound is properly cleaved is very important. The dispersion treatment is preferably carried out by high-pressure dispersion treatment a plurality of times in the solution. The treatment pressure is preferably 10 MPa or more, more preferably 20 MPa or more.
The solvent is not particularly specified, but water or a water-soluble solvent (lower alcohols such as methanol, ethanol, isopropyl alcohol, acetone, etc.) can be exemplified for the layered inorganic compound not subjected to organic treatment, and water is particularly preferable. .
Moreover, in order to provide defoaming property, the mixed solvent of water and a lower alcohol can also be used preferably. Examples of the high-pressure dispersion treatment method include a method of high-pressure dispersion by swelling a swellable layered inorganic compound in a solvent and then stirring the mixture with a high-pressure homogenizer.
A method for adjusting the coating solution is not particularly limited, but a method of uniformly dissolving the binder component of the coating layer in the solvent and then mixing with the solvent in which the layered particles are uniformly dispersed is effectively used. Moreover, in order to remove an insoluble matter after solution preparation, it is preferable to filter using the filter which has a mesh larger than the largest particle size of a layered inorganic compound.

1- (4) Formation of Covering Layer A vinyl alcohol polymer or a covering layer made of a vinyl alcohol polymer and a layered inorganic compound can be formed on a transparent material film using a coating method described later.
At this time, in order to optimize the viscosity characteristic of the liquid for the coating apparatus during film formation, a method of adjusting the liquid viscosity of the coating liquid by adding a viscosity modifier such as a thickener to the coating liquid is also used. You can also.
In order to further improve the moisture resistance and water resistance of the coating layer, it is preferable to heat-treat the resin layer at 90 ° C. or higher and 150 ° C. or lower for several minutes after applying the coating layer on the cellulose acylate substrate. It is preferable to heat at 130 ° C. or higher and 150 ° C. or lower.
The heat treatment time is preferably from 1 minute to 20 minutes, more preferably from 5 minutes to 15 minutes, from the viewpoint of productivity and water resistance.
Moreover, it is preferable that the cellulose acylate is previously saponified from the viewpoint of adhesion between the resin layer and the cellulose acylate substrate.

1- (5) The thickness, haze, surface roughness of the coating layer made of vinyl alcohol polymer or vinyl alcohol polymer and layered inorganic compound The thickness of the coating layer is preferably in the range of 1-30 μm, more preferably Is about 3 to 20 μm. The haze value of the produced resin layer is preferably 30% or less, more preferably 10% or less, and still more preferably 8% or less. The internal haze value is preferably 10% or less, more preferably 5% or less, and still more preferably 1% or less.
Further, the arithmetic average roughness Ra of the surface is preferably 0.2 or less, the square root roughness Rq is 0.2 or less, and the ten-point average roughness Rzjis is preferably 1.5 or less.

1- (6) Configuration The coating layer can be provided between the polarizer and the transparent substrate film, or on the opposite side of the polarizer with the transparent substrate film interposed therebetween. Moreover, although it can also provide in these both sides, from the viewpoint of productivity at the time of polarizing plate processing, applicability | paintability of a hard-coat layer, etc., this resin layer was provided between the polarizer and the transparent base film. The case is more preferably used.
However, even when the polarizer is provided with the resin layer on the opposite side across the transparent substrate film, the productivity at the time of polarizing plate processing does not decrease, and the following is described on the resin layer: By providing an easy-adhesion layer, it is possible to further provide a layer having a hard coat property or the like thereon.

A basic configuration of a preferred embodiment of the protective film for polarizing plate of the present invention will be described with reference to the drawings.
Here, FIG. 1A and FIG. 1B are sectional views schematically showing a preferred embodiment of the present invention, but the protective film and polarizing plate of the present invention are not limited to this form.
A protective film 1 of the present invention shown in FIG. 1A includes a transparent base film 2 and a low moisture-permeable coating layer 3 (hereinafter sometimes referred to as a coating layer).
More preferably, a layer 4 having hard coat properties is further provided on the coating layer 3 as shown in FIG. 1B. It is further preferable to add internal scattering properties and surface scattering properties to the layer 4 having hard coat properties.
In addition, it is also preferable to further provide a low refractive index layer on the hard coat layer 4 for the purpose of reducing the surface reflectance. It is also preferable to have an undercoat layer between at least one of the transparent base film 2 and the cover layer 3 and between the cover layer 3 and the hard coat layer 4 from the viewpoint of adhesion between layers, and the undercoat layer has a plurality of layers. It is also preferable that it consists of. It is also preferable to use any one of the undercoat layers as an antistatic layer.
Although FIG. 2A and FIG. 2B are sectional drawings which show typically one preferable embodiment of the polarizing plate using the protective film of this invention, the polarizing plate of this invention is not restricted to this form.
A polarizing plate 5 of the present invention shown in FIGS. 2A and 2B is composed of a protective film 1 of the present invention, a polarizing plate protective film 7 on the side opposite to the polarizer 6, and an adhesive layer 8. The surface of the polarizing plate 5 of the present invention opposite to the coating layer 3 is bonded to the polarizer 6. The polarizing plate protective film 7 on the opposite side is not particularly limited, but is preferably a substrate film made of cellulose acylates without a coating layer from the viewpoint of productivity.
FIG. 3 is a cross-sectional view schematically showing a preferred embodiment of an image display device using the polarizing plate of the present invention using a liquid crystal display device, but the image display device of the present invention is limited to this form. It is not a thing.
The image display device 9 of the present invention shown in FIG. 3 includes the polarizing plate 5 and the liquid crystal cell 10 of the present invention. The polarizing plate 5 of the present invention is preferably used on both sides as shown in FIG. 3, but it is also effective on one side. In the polarizing plate of the present invention, the opposite protective film 7 side is preferably attached to the liquid crystal cell via the pressure-sensitive adhesive layer 8.

  An optical compensation film is also preferably used as the polarizing plate protective film on the opposite side of the low moisture-permeable tack of the present invention, and the optical compensation film is also preferably a base film in which an optical compensation layer is formed on the base film. Further, it is also preferable to use an optical compensation film attached on the opposite polarizing plate protective film via an adhesive.

[Ultraviolet absorber]
It is preferable that one or more kinds of ultraviolet absorbers represented by the following general formula (1) are contained in any of the transparent substrate film, the coating layer, the undercoat layer, and the hard coat layer of the present invention.
The average value of the octanol / water partition coefficient (hereinafter referred to as log P) represented by the following formula (A) relating to the ultraviolet absorber (hereinafter referred to as average log P) and the acylation degree DS of cellulose acylate are represented by the following formula (B). It is more preferable that the cellulose acylate film satisfying the above is used as the transparent substrate film.

(In the general formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or a monovalent organic group, and at least one of R ¹ , R ² and R ³ is Represents an unsubstituted branched or straight chain alkyl group having a total carbon number of 4 to 20, and R ¹ , R ² and R ³ are different from each other

(In the formula (A), _{W n} represents the mass fraction of the n-th ultraviolet absorber, _{(logP) n} represents a logP of n-th ultraviolet absorber)

  5.0 × DS−6.7 ≦ average log P ≦ 5.0 × DS−5.1... Formula (B)

The average value of logP of the ultraviolet absorbent used in the present invention is (5.0 × DS−6.7) or more and (5.0 × DS−5.1) or less, and (5.0 × DS− 6.5) or more and (5.0 × DS-5.2) or less is preferable. If the average value of log P is too large, the surface shape is deteriorated, and if the average value of log P is too small, the retentivity of the ultraviolet absorbent under high temperature and high humidity is deteriorated.
Moreover, the compound represented by General formula (1) has an absorption maximum in the wavelength range of 330-360 nm.

The ultraviolet absorber used in the present invention preferably has a molecular weight of 250 to 1,000 from the viewpoint of volatility, more preferably 260 to 800, still more preferably 270 to 800, and particularly preferably 300 to 800. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The ultraviolet absorber is preferably not volatilized in the process of dope casting for preparing a cellulose acylate film, the process of drying, the coating of the undercoat layer, the coating layer, the layer having hard coat properties, and the process of drying.

(Compound addition amount)
The addition amount of the ultraviolet absorber used in the present invention described above is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on cellulose acylate. It is especially preferable that it is 2-3 mass%.
When added to an undercoat layer, a coating layer, a layer having hard coat properties, etc., it is preferably 0.01 to 10% by mass, and preferably 0.1 to 5% by mass with respect to the total solid content. More preferably, it is 0.2-3 mass% especially preferable.

Next, the moisture permeability will be described in detail.
The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) Can be applied as appropriate.

[Measurement method 1 of moisture permeability]
70 mmφ film sample according to the present invention is conditioned at 60 ° C. and 40% RH for 24 hours, respectively, and from the difference in mass before and after humidity adjustment, using a moisture permeable cup according to JIS Z-0208, moisture permeability = after moisture conditioning The amount of water per unit area (g / m ² ) was calculated by mass-mass before humidity control. The moisture permeability value was not corrected with a blank cup containing no hygroscopic agent.
When measured by the above measurement method, the moisture permeability of a commercially available cellulose acetate film is generally 80 μm thick and the moisture permeability under the above conditions is 350 to 400 g / m ² · day.
In contrast, the upper limit of the moisture permeability of the protective film of the present invention is preferably 100 g / m ² · day or less, more preferably 70 g / m ² · day or less, and 15 g / m ² · day or less. It is particularly preferred.
When the moisture permeability is higher than the above upper limit value, unevenness of the display image occurs due to a change in the size of the polarizing film due to a change in temperature or humidity during long-term use, and the reduction effect is low. Although a minimum in particular does not have a restriction | limiting, It is preferable that it is larger than 0 g / m < ² > * day, and 3 g / m < ² > * or more is preferable from a viewpoint of productivity at the time of polarizing plate processing.
Accordingly, the moisture permeability of the low moisture permeability tack of the present invention is particularly preferably in the range of 3 to 15 g / m ² · day.

When producing a polarizing plate using the protective film for polarizing plates of the present invention as at least one of the surface protective films of two polarizing films, the protective film for polarizing plates is opposite to the coating layer. It is preferable to improve the adhesion on the adhesive surface by hydrophilizing the surface of the transparent substrate film, that is, the surface to be bonded to the polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol. As the hydrophilic treatment, the following saponification treatment is preferably performed.

[Saponification]
(1) Method of immersing in alkaline solution This is a technique in which a protective film for polarizing plate is immersed in an alkaline solution under appropriate conditions, and all surfaces having reactivity with alkali on the entire surface of the film are saponified. It is preferable from the viewpoint of cost because it does not require any equipment.
The alkaline liquid is preferably a sodium hydroxide aqueous solution. As a density | concentration of an alkaline solution, 0.5-3 mol / L is preferable and 1-2 mol / L is more preferable. Moreover, 30-75 degreeC is preferable and, as for the liquid temperature of an alkaline liquid, 40-60 degreeC is more preferable.
The combination of the saponification conditions is preferably a combination of relatively mild conditions, but can be set according to the material and configuration of the light scattering film and the antireflection film, and the target contact angle.
After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkaline component does not remain in the film.

By performing the saponification treatment, the surface of the transparent base film opposite to the surface having the antiglare layer or the antireflection layer is hydrophilized. The protective film for polarizing plate is used by adhering the hydrophilic surface of the transparent substrate film to the polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol.
In the saponification treatment, the lower the contact angle with water on the surface of the transparent substrate film opposite to the side having the antiglare layer or the low refractive index layer, the better from the viewpoint of adhesion to the polarizing film, but on the other hand, In the method, it is important to set the reaction conditions to the minimum necessary because alkali damage is caused from the surface having the antiglare layer and the low refractive index layer to the inside.
When the contact angle to water of the transparent substrate film on the opposite surface is used as an index of damage received by each layer due to alkali, 10 to 50 ° is preferable particularly when the transparent substrate film is triacetyl cellulose. -50 ° is more preferred, and 40-50 ° is even more preferred. If it is 50 degrees or more, a problem arises in the adhesion to the polarizing film, which is not preferable. On the other hand, if it is less than 10 degrees, the damage is too great, and physical strength is impaired.

  Below, the polarizing plate using the low moisture-permeable protective film of this invention and the liquid crystal display device using this polarizing plate are demonstrated.

The protective film (optical film) of this invention comprises a polarizing plate by bonding together at least 1 surface of a polarizer. TAC is preferably used for the other surface of the polarizer.
A normal cellulose acetate film may be used, but a cellulose acetate film produced by a solution casting method and stretched in the width direction in the form of a roll film at a stretch ratio of 10 to 100% may be used.
Furthermore, in the polarizing plate of the present invention, one side may be an optical compensation film having an optically anisotropic layer made of a liquid crystalline compound while the other protective film is the protective film of the present invention.
Further, in the polarizing plate of the present invention, one side is the protective film of the present invention, whereas the other protective film has a Re of 0 to 10 nm and an Rth of -20 to 20 nm (for example, JP 2005-301227 A). No. paragraph number [0095]).

  Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film.

  When the protective film of the present invention is used with a liquid crystal display device or the like, the protective film is preferably disposed on the viewing side opposite to the liquid crystal cell.

Of the two protective films of the polarizer, the film other than the protective film of the present invention is preferably an optical compensation film having an optical compensation layer comprising an optically anisotropic layer. The optical compensation film (retardation film) can improve the viewing angle characteristics of the liquid crystal display screen.
A known film can be used as the optical compensation film, but the optical compensation film described in JP-A-2001-100042 is preferable in terms of widening the viewing angle.

(Optically anisotropic layer made of polymer film)
The optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene-based polymers), polycarbonate, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid ester, polyacrylic acid ester and cellulose ester (eg, cellulose triacetate, Cellulose diacetate), polyaryletherketone, polyamide, polyester, polyimide, polyamideimide or polyesterimide. Specifically, polyamides and polyimides described in JP-A Nos. 2004-4474 and 61-162512 can be used. Moreover, a copolymer or a polymer mixture of these polymers may be used.
The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm. Specifically, for example, the method described in Japanese Patent Application No. 2005-302992 can be used.

It is preferable that the Reλ retardation value and the Rthλ retardation value satisfy the following formulas (1) to (2), respectively, in order to widen the viewing angle of a liquid crystal display device, particularly a VA mode liquid crystal display device. In particular, a cellulose acylate film is preferable when used for a protective film on the liquid crystal cell side of the polarizing plate.
0 nm ≦ Re ₅₉₀ ≦ 200 nm ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (1)
0 nm ≦ Rth ₅₉₀ ≦ 400 nm ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (2)
[In the formula, Re ₅₉₀ and Rth ₅₉₀ are values (unit: nm) at a wavelength λ = 590 nm. ]

Further, when it is desired to reduce the influence of the optical anisotropy of the cellulose acylate film, Re (λ) and Rth (λ) of the protective film (cellulose acylate film) disposed on the liquid crystal cell side are expressed by Equation (3). It is preferable to satisfy (6).
0 ≦ Re ₅₉₀ ≦ 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (3)
｜ Rth ₅₉₀ | ≦ 25 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (4)
｜ Re ₄₀₀ −Re ₇₀₀ ｜ ≦ 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (5)
｜ Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Equation (6)
In the above formulas (3) to (6), Re ₅₉₀ and Rth ₅₉₀ are values at a wavelength λ = 590 nm, Re ₄₀₀ and Rth ₄₀₀ are values at a wavelength λ = 400 nm, Re ₇₀₀ and Rth ₇₀₀ are wavelengths λ = A value at 700 nm (both in nm).

When the cellulose acylate film preferably used in the present invention is used in the VA mode, a mode in which a total of two sheets are used on each side of the cell (two sheets type) and only one of the upper and lower sides of the cell are used. There are two types of forms (single sheet type).
In the case of the two-sheet type, Re ₅₉₀ is preferably 20 to 100 nm, and more preferably 30 to 70 nm. Rth ₅₉₀ is preferably 70 to 300 nm, more preferably 100 to 200 nm.
In the case of a single sheet type, Re ₅₉₀ is preferably 30 to 150 nm, and more preferably 40 to 100 nm. Rth ₅₉₀ is preferably 100 to 300 nm, and more preferably 150 to 250 nm.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used, A method in which a solution obtained by dissolving this in a solvent is applied to a substrate and the solvent is dried to form a film can be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the transparent film of the present invention is preferably used as the base material. Can do. In addition, it is also preferable that the polymer film is prepared on another substrate, and the polymer film is peeled off from the substrate and then bonded to the transparent film of the present invention, and used as an optically anisotropic layer. . In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm.

<Optically anisotropic layer>
Furthermore, the protective film may be a polymer film provided with an optically anisotropic layer. The optically anisotropic layer preferably has an alignment layer and an optically anisotropic layer in this order on a transparent polymer film.

The alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, or formation of a layer having a microgroup.
Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known, but an alignment layer formed by a rubbing treatment of a polymer is particularly preferable.
The rubbing treatment is preferably performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth.
The polymer used for the alignment layer is preferably polyimide, polyvinyl alcohol, or a polymer having a polymerizable group described in JP-A-9-152509.
Further, the thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

  The optically anisotropic layer preferably contains a liquid crystalline compound. The liquid crystal compound used in the present invention particularly preferably has a discotic compound (discotic liquid crystal). The discotic liquid crystal molecule has a disk-like core portion like the triphenylene derivative of D-1, and has a structure in which side chains extend radially therefrom. Further, in order to fix the once aligned state, it is also preferable to further introduce a group that reacts with heat, light or the like. Preferred examples of the discotic liquid crystal are described in JP-A-8-50206.

  The discotic liquid crystal molecules are aligned almost parallel to the film plane with a pretilt angle in the rubbing direction in the vicinity of the alignment layer, and the discotic liquid crystal molecules are oriented so that they are perpendicular to the plane on the opposite air side. is doing. The tilt angle of the discotic liquid crystal molecules near the alignment layer and near the air interface can be controlled by the type of the discotic liquid crystal material, the type of the alignment layer material, the rubbing conditions, and the use of additives. The discotic liquid crystal layer as a whole has a hybrid orientation. With this layer structure, the viewing angle of a liquid crystal display device using the protective film of the present invention can be increased.

  The optically anisotropic layer is generally a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) dissolved in a solvent, coated on the alignment layer, dried, and then discotic nematic. After heating to the phase formation temperature, it is obtained by polymerization by irradiation with UV light or the like and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably 70 to 300 ° C, particularly preferably 70 to 170 ° C.

In addition to the discotic compound added to the optically anisotropic layer, the compound has compatibility with the discotic compound and can give a preferable change in tilt angle to the liquid crystalline discotic compound or inhibit the alignment. Any compound can be used as long as it is not. Among these, additives for controlling the orientation on the air interface side such as polymerizable monomers (eg, compounds having vinyl group, vinyloxy group, acryloyl group and methacryloyl group), fluorine-containing triazine compounds, cellulose acetate, cellulose acetate Mention may be made of polymers such as pionate, hydroxypropylcellulose and cellulose acetate butyrate. These compounds are generally used in an amount of 0.1 to 50% by mass, preferably 0.1 to 30% by mass, based on the discotic compound.
The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

The optically anisotropic layer may be a non-liquid crystalline polymer layer prepared by dissolving a non-liquid crystalline compound in a solvent, applying the solution on a support, and heating and drying. In this case, for example, the non-liquid crystalline compound is excellent in heat resistance, chemical resistance, transparency, and has high rigidity, so polyamide, polyimide, polyester, polyether ketone, polyaryl ether ketone, polyamide imide, polyester imide, etc. These polymers can be used. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is preferable because of its high transparency, high orientation, and high stretchability. Moreover, as a support body, a TAC film is preferable.
In addition, it is also preferable that the laminate of the non-liquid crystal layer and the support is stretched in the horizontal direction of the tenter from 1.05 times to 1.50 times and the support side is bonded to a polarizer.
Furthermore, the optically anisotropic layer may be an alignment solidified layer of cholesteric liquid crystal having a selective reflection wavelength region of 350 nm or less. Examples of the cholesteric liquid crystal are described in JP-A-3-67219, JP-A-3-140921, JP-A-5-61039, JP-A-6-186534, JP-A-9-133810, and the like. Any suitable material showing the selective reflection characteristics can be used. What can be preferably used from the viewpoint of stability of the alignment solidified layer is, for example, a cholesteric liquid crystal composed of a cholesteric liquid crystal polymer, a nematic liquid crystal polymer containing a chiral agent, a compound that forms such a liquid crystal polymer by polymerization treatment with light, heat, or the like. A layer can be formed.
In this case, the optically anisotropic layer can be formed by, for example, a method of coating a cholesteric liquid crystal on a support substrate. In that case, for the purpose of controlling the phase difference or the like, a method of overcoating the same type or different types of cholesteric liquid crystals may be employed as necessary. For the coating treatment, for example, an appropriate method such as a gravure method, a die method, or a dipping method can be adopted. An appropriate material such as a TAC film or other polymer film can be used as the support substrate.

In the above, when forming the optically anisotropic layer, a means for aligning the liquid crystal is employed. The alignment means is not particularly limited, and any appropriate means that can align the liquid crystal compound can be adopted. As an example, there is a method in which liquid crystal is coated on the alignment film and aligned.
In addition, as the alignment film, a rubbing treatment film made of an organic compound such as a polymer, an oblique deposition film of an inorganic compound, a film having a microgroove, or ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate, etc. Examples include a film obtained by accumulating LB films by the Langmuir-Blodgett method of organic compounds. Further examples include an alignment film in which an alignment function is generated by light irradiation. On the other hand, a method of aligning liquid crystal on a stretched film (Japanese Patent Laid-Open No. 3-9325), a method of aligning liquid crystal under application of an electric field or magnetic field, and the like are also included. The alignment state of the liquid crystal is preferably as uniform as possible, and is preferably a solidified layer fixed in the alignment state.

(Liquid crystal display device)
The polarizing plate of the present invention can be advantageously used for an image display device such as a liquid crystal display device, and is preferably used for the outermost layer of the liquid crystal display device.
The liquid crystal display device has a liquid crystal cell and two polarizing plates arranged on both sides thereof, and the liquid crystal cell carries a liquid crystal between two electrode substrates. Furthermore, one optically anisotropic layer may be disposed between the liquid crystal cell and one polarizing plate, or two optically anisotropic layers may be disposed between the liquid crystal cell and both polarizing plates.

  The liquid crystal cell is preferably in TN mode, VA mode, OCB mode, IPS mode or ECB mode.

<TN mode>
In a TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and are twisted and aligned at 60 to 120 °.
The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

<VA mode>
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of Tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (for MVA mode) in order to enlarge the viewing angle. ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

<OCB mode>
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in substantially opposite directions (symmetrically) at the upper and lower portions of the liquid crystal cell. US Pat. No. 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

<IPS mode>
The IPS mode liquid crystal cell is a type in which a nematic liquid crystal is switched by applying a lateral electric field. IDRC (Asia Display '95), p. 577-580 and p. 707-710.

<ECB mode>
In the ECB mode liquid crystal cell, rod-like liquid crystalline molecules are substantially horizontally aligned when no voltage is applied. The ECB mode is one of the liquid crystal display modes having the simplest structure, and is described in detail in, for example, Japanese Patent Application Laid-Open No. 5-203946.

<Brightness enhancement film>
As the brightness enhancement film, a polarization conversion element having a function of separating light emitted from a light source (backlight) into transmitted polarized light, reflected polarized light, or scattered polarized light is used. Such a brightness enhancement film can improve the emission efficiency of linearly polarized light by using retroreflected light from a reflected polarized light or scattered polarized light backlight.
An example is an anisotropic reflective polarizer. An anisotropic reflective polarizer includes an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction.
An example of the anisotropic multi-thin film is DBM manufactured by 3M (see, for example, JP-A-4-268505).
An example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ / 4 plate. An example of such a composite is PCF manufactured by Nitto Denko (see JP-A-11-231130, etc.). An example of the anisotropic reflective polarizer is a reflective grid polarizer.
As a reflective grid polarizer, a metal grid reflective polarizer (see US Pat. No. 6,288,840, etc.) that finely processes metal and emits reflected polarized light in the visible light region, and puts metal fine particles in a polymer matrix. And the like (see JP-A-8-184701, etc.).
Moreover, an anisotropic scattering polarizer is mentioned. An example of the anisotropic scattering polarizer is DRP manufactured by 3M (see US Pat. No. 5,825,543).
Furthermore, there is a polarizing element that can perform polarization conversion in one pass. For example, the one using smectic C * can be mentioned (see JP 2001-201635 A). An anisotropic diffraction grating can be used.

  The polarizing plate of the present invention can be used together with a brightness enhancement film. In the case of using a brightness enhancement film, it is more preferable that the polarizing plate and the brightness enhancement film are in close contact with each other in order to prevent moisture from entering the polarizing plate and suppress light leakage. The adhesive for bonding the polarizing plate and the brightness enhancement film is not particularly limited. For example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers Can be appropriately selected and used. In particular, those excellent in optical transparency, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties and excellent in weather resistance, heat resistance and the like can be preferably used.

<Touch panel>
The film of the present invention can be applied to touch panels described in JP-A-5-127822 and JP-A-2002-48913.

<Organic EL device>
The film of the present invention can be used as a substrate (base film) such as an organic EL element or a protective film.
When the film of the present invention is used for an organic EL device or the like, JP-A-11-335661, JP-A-11-335368, JP-A-2001-192651, JP-A-2001-192652, JP-A-2001-192653, JP-A-2001-335776, JP-A-2001-247859, JP-A-2001-181616, JP-A-2001-181617, JP-A-2002-181816, JP-A-2002-181617, JP-A-2002-056776, etc. The contents described in each publication can be applied. Moreover, it is preferable to use together with the content of each gazette of Unexamined-Japanese-Patent No. 2001-148291, Unexamined-Japanese-Patent No. 2001-221916, and Unexamined-Japanese-Patent No. 2001-231443.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the embodiments of the present invention are not limited to these examples.

<Measurement method>
Hereinafter, a method for measuring various performances described in this specification will be described.

<Moisture permeability>
The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The film sample 70 mmφ according to the present invention is conditioned at 60 ° C. and 40% RH for 24 hours, and according to JIS Z-0208, moisture permeability = mass after moisture conditioning−mass before moisture conditioning. The water content per unit area (g / m ² ) was calculated. Moreover, when measuring the moisture permeability of the protective film having a resin layer containing a vinyl alcohol polymer, set the sample in such an orientation that the resin layer provided on the transparent substrate film is in contact with the measuring cup, The moisture permeability from the transparent substrate film side was measured.

<Measurement of strain amount of adhesive layer in creep test>
A non-alkali glass plate (Corning Corp., 1737, size: 50 × 100 mm, thickness: 1.0 mm) and a polarizing plate cut to 25 mm × 50 mm are bonded via an adhesive so that the bonding area is 10 mm × 25 mm. The substrates were bonded together and left for 1 hour in an environment of 25 ° C. and 65% RH. Thereafter, this sample was fixed in the vertical direction, and a load of 1 kg was applied to the end of the polarizing plate at 25 ° C. and 60% RH for 1 minute.
Next, a load of 1 kg was applied to the end of the polarizing plate at 80 ° C. dry for 1 hour. The strain amount A from the initial state at that time was measured.

<Evaluation of light leakage>
Purchase a commercial TV, LC-26GD3 (manufactured by Sharp Corporation) for VA mode, 32LC100 (manufactured by Toshiba Corporation) for IPS mode, and MRT-191S (manufactured by Mitsubishi Electric Corporation) for TN mode. Then, each polarizing plate was peeled off to make an evaluation TV.
The produced polarizing plate is cut into each screen size, and the transmission axis of the polarizing plate is 45 ° for the TN mode, 135 ° for the rear, 0 ° for the VA mode and IPS mode with respect to the periphery of the panel. The film was attached to both sides of the panel so that the absorption axis of the polarizing plate was perpendicular to the front and back so that the rear was 90 °, and autoclaved at 50 ° C. and a pressure of 0.5 MPa for 30 minutes. Then, after storing at 70 ° C. dry or 60 ° C. and 90% RH for 100 hours, light leakage after 1 hour and 24 hours in an atmosphere of 25 ° C. and 52% RH was evaluated. In addition, it shows in FIG. 4 about the sticking method of a polarizing plate. In FIG. 4, the solid line arrow indicates the direction of the transmission axis in the polarizing plate installed on the viewing side with respect to the liquid crystal cell, and the solid line arrow indicates the polarizing plate installed on the viewing side with respect to the liquid crystal cell. Indicates the direction of the transmission axis of the polarizing plate installed on the backlight side with respect to the liquid crystal cell.

[Evaluation criteria]
The presence or absence of light leakage around the evaluation sample was visually observed and evaluated. 5: No light leakage was observed. 4: Light leakage was slightly observed but there was no practical problem. When light leakage is observed to be weak but there is no practical problem 2: When light leakage is strongly observed but there is no problem in practical use 1: When light leakage is observed at a level where there is a practical problem

<Durability (peeling)>
In a state where the polarizing plate sample conditioned under normal conditions of 25 ° C. and 60% RH is bonded to a glass plate with an adhesive, the heat resistance condition (dry) of 100 ° C. and 100 hours, or 60 ° C. and 95% RH Durability tests were carried out under wet heat and heat resistance conditions (wet) for 720 hours, and the presence or absence of peeling at the bonded interface between the polarizing plate and glass after the test was observed and evaluated.

[Evaluation criteria]
◎: No peeling was observed. ○: Slight peeling with a width of 1 mm or less occurred at the sample end, but there was no practical problem. Δ: Peeling with a width of 1 mm or more and 2 mm or less occurred at the sample end. Level where there is no problem in practical use ×: Level in which peeling exceeding 2 mm in width is clearly observed at the edge of the sample, and there is a problem in practical use

[Adhesion evaluation]
The adhesion between the film layers or between the support and the coating layer was evaluated by the following method.
Nitto Denko Co., Ltd. Polyester adhesive tape with 11 squares and 11 horizontal cuts at 1 mm intervals and a total of 100 squares on the surface of the coated layer. (NO.31B) is pressure-bonded, and the test for peeling off after leaving for 24 hours is repeated three times at the same place, and the presence or absence of peeling is visually observed based on the following evaluation criteria.

[Evaluation criteria]
○: No peeling △: Some peeling, but no problem in practical use ×: There is peeling on the entire surface

<Preparation of adhesive>
<< Preparation of acrylic polymer I >>
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 70 parts of butyl acrylate, 30 parts of methyl acrylate, 3 parts of acrylic acid, 2,2′-azobisisobutyronitrile 0.3 A portion was added together with ethyl acetate and reacted at 60 ° C. for 6 hours under a nitrogen gas stream to obtain an acrylic polymer solution having a mass average molecular weight of 1,200,000.

<< Preparation of Acrylic Polymer II >>
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 70 parts of butyl acrylate, 30 parts of methyl acrylate, 0.3 part of 2,2′-azobisisobutyronitrile together with ethyl acetate In addition, the reaction was carried out at 60 ° C. for 6 hours under a nitrogen gas stream to obtain an acrylic polymer solution having a mass average molecular weight of 1.1 million.

<< Preparation of adhesive A >>
Acrylic polymer I solution and acrylic polymer II solution were mixed at a ratio of 7: 3, and further 3 parts of trimethylolpropane tolylene diisocyanate (100 parts by solid content of Nippon Polyurethane, Coronate L) per 100 parts of solid content of the mixed solution. Was added as a crosslinking agent to obtain an acrylic pressure-sensitive adhesive A.

<< Preparation of adhesives B to H >>
Change the ratio of acrylic polymers I and II and the ratio of trimethylolpropane tolylene diisocyanate in the same manner as adhesive A, and then add trimethylolpropane tolylene diisocyanate (Nihon Polyurethane Co., Ltd., Coronate L). Acrylic pressure-sensitive adhesives B to H were obtained by changing the range of 0.1 to 1.6 parts per 100 parts by mass of the solid content so that the creep values shown in Table 1 were obtained.

<Measurement of gel fraction>
The gel fraction of the obtained adhesives A to H was measured.
The gel fraction was measured according to the gel fraction measuring method described in JP-A No. 2003-34781. Specifically, about 0.1 g of an adhesive that was aged for 7 days on a support at a temperature of 23 ° C. and a humidity of 65% was collected in a sample bottle, added with 30 ml of ethyl acetate, and shaken for 24 hours. The contents of the sample bottle were filtered with a 200-mesh stainless steel wire mesh, the residue on the wire mesh was dried at 100 ° C. for 2 hours, the dry weight was measured, and the following formula was obtained.
Gel fraction (%) = (dry mass (g) / adhesive sampling mass (g)) × 100
As a result, the gel fraction of adhesive A is 91%, the gel fraction of adhesive B is 88%, the gel fraction of adhesive C is 83%, the gel fraction of adhesive D is 77%, and adhesive E The gel fraction of the adhesive was 72%, the gel fraction of the adhesive F was 68%, the gel fraction of the adhesive G was 62%, and the gel fraction of the adhesive H was 53%. These results are shown in Table 1.

< Preparation of coating solution a-1 for coating layer>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating layer coating solution a-1.

[Composition of coating liquid a-1 for coating layer]
-Chlorine-containing polymer: R204 ... 12g
{"Saran Resin R204" manufactured by Asahi Kasei Life & Living Co., Ltd.}
・ Tetrahydrofuran ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 63g

<Preparation of coating solution a-2 for coating layer>
Water and MEB-3 were mixed, and HR-3010 was added, followed by stirring at 95 ° C. for 2 hours. Thereafter, the coating solution was filtered through a polypropylene filter having a pore size of 100 μm to prepare a coating solution a-2 coating solution.

[Composition of coating liquid a-2 for coating layer]
・ Vinyl alcohol polymer HR-3010 (manufactured by Kuraray Co., Ltd.) ・ ・ ・ ・ ・ ・ 5 parts by weight ・ Underwater high-pressure dispersed mica MEB-3 (solid content ratio 8 mass%, manufactured by Coop Chemical)・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 3.1 parts by mass
・ Water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 70 parts by mass

<Preparation of PVA (4%) solution>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a PVA (4%) solution.

[Composition of 4% PVA solution]
・ Pure water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 375g
・ Isopropyl alcohol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 202 g
・ PVA124C ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 24g

  Pure water and isopropyl alcohol were heated to 70 ° C., PVA124C was added little by little while stirring, and stirring was continued until PVA124C was dissolved. After dissolving PVA124C, the temperature was returned to room temperature, and the solvent amount corresponding to the mass decrease was corrected to prepare a coating layer coating solution a-3.

[Composition of coating liquid a-3 for coating layer]
・ Isopropyl alcohol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 19g
・ Pure water ... 47g
・ Tetraethoxysilane ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 27g
・ 0.1N-HCl ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 1.3g
-PVA (4%) ... 106g
・ N, N-dimethylbenzylamine ... 0.002g

<Preparation of coating solution for hard coat layer>
<< Preparation of Sol Solution 1 >>
In a 1,000 mL reaction vessel equipped with a thermometer, a nitrogen introduction tube, and a dropping funnel, 187 g (0.80 mol) of acryloxyoxypropyltrimethoxysilane, 27.2 g (0.20 mol) of methyltrimethoxysilane, 320 g of methanol ( 10 mol) and 0.06 g (0.001 mol) of KF were added, and 15.1 g (0.86 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux.
Then, 120 g of sol solution 1 was obtained by distilling off the low boiling point under reduced pressure and further filtering. As a result of GPC measurement of the substance thus obtained, the mass average molecular weight was 1,500, and among the components higher than the oligomer component, the component having a molecular weight of 1,000 to 20,000 was 30%. Moreover, from the measurement result of ¹ H-NMR, the structure of the obtained substance was a structure represented by the following general formula (2).

Furthermore, the condensation rate α as determined by ²⁹ Si-NMR was 0.56. From this analysis result, it was found that most of the silane coupling agent sol was a linear structure portion.
From the gas chromatography analysis, the raw material acryloxypropyltrimethoxysilane had a residual rate of 5% or less.

<Preparation of coating solution for hard coat layer>
[Composition of coating liquid for hard coat layer]
・ PET-30 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 40.0g
・ DPHA ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 10.0g
・ Irgacure 184 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 2.0g
-SX-350 (30%) ... 2.0g
・ Cross-linked acrylic-styrene particles (30%) ... 13.0g
・ FP-13 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.06g
・ Sol solution 1 ... 11.0g
・ Toluene ... 38.5g

  The coating solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for a hard coat layer.

The compounds used are shown below.
PET-30: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.)
・ Irgacure 184: Polymerization initiator (Ciba Specialty Chemicals Co., Ltd.)
SX-350: average particle size 3.5 μm cross-linked polystyrene particles (refractive index 1.60, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion, used after dispersion for 20 minutes at 10,000 rpm with a Polytron disperser)
Crosslinked acrylic-styrene particles: average particle size 3.5 μm (refractive index 1.55, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion, used after dispersion at 10,000 rpm for 20 minutes with a Polytron disperser)

<Preparation of coating solution for low refractive index layer>
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.44 containing polysiloxane and hydroxyl group (JTA113, solid content concentration 6%, manufactured by JSR Corporation) 13 g, colloidal silica dispersion MEK-ST-L (trade name, average) Particle size 45 nm, solid content concentration 30%, manufactured by Nissan Chemical Co., Ltd.) 1.3 g, sol solution 0.65 g, methyl ethyl ketone 4.4 g, cyclohexanone 1.2 g were added, and after stirring, made of polypropylene with a pore size of 1 μm It filtered with the filter and the low refractive index layer coating liquid was prepared. The refractive index of the layer formed with this coating solution was 1.45.

<Preparation of protective film a-1>
A triacetylcellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) is unwound in a roll form, and the coating solution a-1 for coating layer is directly extruded onto the TAC using a coater having a slot die. did. The film was applied at a conveyance speed of 30 m / min so that the film thickness was 1.5 μm, dried at 80 ° C. for 5 minutes, and wound up.

<Preparation of protective film a-2>
The side on which the coating layer of triacetylcellulose (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) was provided was subjected to saponification treatment at 50 ° C. with a 1 mol / L alkaline solution. Thereafter, coating liquid a-2 for coating layer was applied on the saponified surface of the triacetyl cellulose film under the condition of a conveyance speed of 30 m / min so that the film thickness after drying was 6 μm, and dried at 100 ° C. for 5 minutes. And wound up.

<Preparation of protective film a-3>
<< Corona discharge treatment >>
Thick triacetyl cellulose film 80μm in (TAC-TD80U, Fuji Photo Film Co., Ltd.) in a roll form was unrolled, while transported at the transportation speed 105m / min, GENERAL support under the condition of 727J / ^{m 2} The body surface was subjected to corona discharge treatment.

  The 80 μm-thick triacetyl cellulose film that has been subjected to the corona discharge treatment is unwound in a roll form, and the coating liquid a-3 for the coating layer is applied onto the surface that has been subjected to the corona discharge treatment using a micro gravure coater. , Dried at 120 ° C. for 10 minutes and wound up. The dry film thickness of the coating layer was 0.6 μm.

<Preparation of protective film b>
Using a hot air dryer in which air is passed through pellets of a norbornene-based polymer (trade name: ZEONOR 1420R, manufactured by Nippon Zeon Co., Ltd., glass transition temperature: 136 ° C., saturated water absorption: less than 0.01% by mass). And dried at 110 ° C. for 4 hours.
Then, a short-axis extruder having a coat hanger type T-die having an average surface roughness Ra = 0.04 μm, in which a leaf disk-shaped polymer filter (filtration accuracy 30 μm) is installed, and the tip of the die lip is chrome-plated is used. The pellets were melt extruded at 260 ° C. to obtain a long protective film b having a thickness of 70 μm and a width of 1,340 mm. The saturated water absorption of the obtained long protective film b was 0.01% by mass or less.

<Coating of hard coat layer>
When the protective film coated with the coating layer is unwound in the form of a roll and the coating liquid a-1 or 3 is applied using the coater having a slot die, the coating liquid a-1 or 3 is applied on the coating layer. When the coating liquid a-2 was applied, it was directly extruded onto the surface opposite to the coated surface. After coating at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, and further using a 160 W / cm air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) under a nitrogen purge. The coating layer was cured by irradiating ultraviolet rays with an irradiation amount of 90 mJ / cm ² to form an antiglare layer having an antiglare property having a thickness of 6 μm and wound up.
It coated similarly on the protective film B.

<Coating of low refractive index layer>
The protective film on which the hard coat layer is formed is unwound in the form of a roll, and the coating liquid for the low refractive index layer is applied to the hard coat layer of the protective film on the backup roll using a coater having a slot die. It was extruded and applied directly onto the surface.
After drying at 120 ° C. for 150 seconds and further drying at 140 ° C. for 8 minutes, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with 240 W / cm in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge is used. Then, an ultraviolet ray having an irradiation amount of 300 mJ / cm ² was irradiated to form a low-refractive index layer having a thickness of 100 nm, wound, and a low-refractive index layer was further formed on the protective film on which the hard coat layer was formed.
Regarding the protective film thus produced, the protective film a-1 having the coating layer a-1, the protective film a-2 having the coating layer a-2, and the protective film a-2 having the coating layer a-3 are protected. Let it be film a-3.

<Production of polarizer>
A 120 μm-thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part by mass of iodine, 2 parts by mass of potassium iodide, and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer.

<Other protective films>
Moreover, after immersing the WV film (Fuji Photo Film Co., Ltd. wide view film SA 12B) coated with an optically anisotropic layer in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 120 seconds, Washed and dried.

( Reference Example 1)
<Preparation of polarizing plate>
On the surface of the protective film a-1 that is not coated with the coating layer a-1 and the surface of the saponified WV film that is not coated with the optically anisotropic layer, the polarizer is placed on a completely saponified polyvinyl alcohol 5%. The aqueous solution was bonded as an adhesive to produce the polarizing plate of Reference Example 1.

( Reference Example 2)
<Preparation of polarizing plate>
The polarizer is bonded to the surface of the protective film a-2 on which the vinyl alcohol resin layer and the optically anisotropic layer of the saponified WV film are not applied, using a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive. Then, the film was dried at 70 ° C. to produce the polarizing plate of Reference Example 2.

(Examples 3-6 , Reference Example 7, and Comparative Examples 4-5)
<Preparation of polarizing plate>
In Reference Example 2, Examples 3 to 6, Reference Example 7, and Comparative Examples 4 to 5 were performed in the same manner as Reference Example 2 except that the protective film a-2 and the adhesive were changed as shown in Table 1. A polarizing plate was produced.

(Comparative Examples 1-3)
<Preparation of polarizing plate>
Polarizing plates of Comparative Examples 1 to 3 were produced in the same manner as in Example 1 except that the protective film a-1 in Example 1 was changed to TAC (TD80 manufactured by Fuji Photo Film Co., Ltd.).

( Reference Example 8)
<Preparation of polarizing plate>
Reference Example 1, except that the protective film a-1, and the adhesive was changed as shown in Table 1, in the same manner as in Reference Example 1, a polarizing plate was prepared in Reference Example 8.

Example 9
<Preparation of polarizing plate>
The polarizing plate of Example 9 was bonded to the surface of the protective film b and the saponified WV film on which the optically anisotropic layer was not applied, and the polarizer was bonded using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. Was made.

(Production of liquid crystal display device)
<TN liquid crystal display device>
The polarizing plate provided in the liquid crystal display device (MRT-191S, manufactured by Mitsubishi Electric Corp.) using a TN type liquid crystal cell is peeled off, instead of Examples 3 to 6 and 9, Reference Examples 1, 2, 7 and 8, and The pressure-sensitive adhesives described in Table 1 were used so that the polarizing plate of Comparative Examples 1 to 7 was aligned with the polarizing plate on which the protective film was on the outside (air interface side) and the transmission axis of the polarizing plate was affixed to the product. Pasted through. The evaluation results are shown in Table 2.

As apparent from Table 2, the strain amount A of the pressure-sensitive adhesive layer is 100 μm or more and 3,000 μm or less, and the moisture permeability of the low moisture permeability protective film at 60 ° C. and 40% relative humidity is 100 g / m ² · day. The polarizing plates and liquid crystal display devices of Examples 3 to 6 and 9 and Reference Examples 1, 2, 7 and 8, which are the following, can reduce peripheral unevenness due to light leakage and have durability against peeling damage when the environment changes. The practically preferable performance was improved. Among them, a reference example in which the strain amount A of the pressure-sensitive adhesive layer is 100 μm or more and 1,300 μm or less, and the moisture permeability at 60 ° C. and 40% relative humidity of the low moisture permeability protective film is 15 g / m ² · day or less. The polarizing plates of No. 2 and Examples 3 to 5 and 9 exhibited more preferable performance in peeling evaluation.
Moreover, the strain amount A of the adhesive layer is 500 μm or more and 1,300 μm or less, and the moisture permeability at 60 ° C. and 40% relative humidity of the low moisture permeability protective film is 15 g / m ² · day or less. The polarizing plates and liquid crystal display devices of ˜5 exhibited further preferable performance in peeling evaluation and light leakage evaluation.
Furthermore, the strain amount A of the pressure-sensitive adhesive layer is 700 μm or more and 1,300 μm or less, and the moisture permeability of the low moisture-permeable protective film at 60 ° C. and 40% relative humidity is 15 g / m ² · day or less. The liquid crystal display devices (5) to (5) showed more preferable performance in light leakage evaluation.

<VA liquid crystal display device>
In the VA liquid crystal display device (LC-26GD3 manufactured by Sharp), the VA liquid crystal display device is manufactured in the same manner as the TN liquid crystal display device in the VA liquid crystal display device (LC-26GD3 manufactured by Sharp). Examples 3 to 6 and 9, Reference Examples 1, 2, 7 and 8, and Comparative Examples 1 to 7 were evaluated in the same manner as Examples 3 to 6 and 9, which were applied to a TN liquid crystal display device . Evaluations similar to Reference Examples 1, 2, 7, and 8, and Comparative Examples 1 to 7 were obtained.

<IPS liquid crystal display device>
In the IPS type liquid crystal display device (Th-26LX300, manufactured by Matsushita) whose liquid crystal cell is IPS type, the IPS type liquid crystal display device is manufactured in the same manner as the above TN type liquid crystal display device by changing the WV film to the TAC film. Then, when evaluations similar to those in Examples 3 to 6 and 9, Reference Examples 1, 2, 7, and 8 and Comparative Examples 1 to 7 were performed, Examples 3 to 6 and 9 applied to a TN type liquid crystal display device. Evaluation similar to Reference Examples 1, 2, 7, and 8 and Comparative Examples 1 to 7 was obtained.

FIG. 1A is a cross-sectional view showing a configuration in one embodiment of a polarizing plate protective film of the present invention. FIG. 1B is a cross-sectional view showing a configuration in one embodiment of the protective film for polarizing plate of the present invention. FIG. 2A is a cross-sectional view showing a configuration in one embodiment of the polarizing plate of the present invention. FIG. 2B is a cross-sectional view illustrating a configuration in one embodiment of the polarizing plate of the present invention. FIG. 3 is a cross-sectional view showing a configuration in an embodiment of the liquid crystal display device of the present invention. FIG. 4 is a diagram showing a method of attaching a polarizing plate in one embodiment of the liquid crystal display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Protective film for polarizing plates 2 Transparent base film 3 Cover layer 4 Hard coat layer 5 Polarizing plate 6 Polarizer 7 Protective film for polarizing plates 8 Adhesive layer 9 Liquid crystal cell 10 Liquid crystal display device

Claims (7)

A polarizing plate having a polarizer and protective films provided on both sides of the polarizer,
At least one of the protective films is a low moisture-permeable protective film, and comprises a pressure-sensitive adhesive composition containing an acrylic polymer obtained by copolymerizing at least butyl acrylate and methyl acrylate on the other protective film. An adhesive layer is formed,
The pressure-sensitive adhesive layer is fixed to a substrate with an adhesive area of 10 mm × 25 mm through the pressure-sensitive adhesive layer, and the strain amount A of the pressure-sensitive adhesive layer obtained from a creep test in which a load of 1 kg is applied at 80 ° C. for 1 hour is 400 μm. more than 2, no more than 000μm,
The low moisture-permeable protective film comprises a transparent support, a low moisture-permeable protective film having at least a coating layer containing a vinyl alcohol-based resin and a layered inorganic compound, and a resin having an alicyclic structure. Either
The polarizing plate, wherein the low moisture permeability protective film has a moisture permeability of 100 g / m ² · day or less at 60 ° C. and 40% relative humidity.   The polarizing plate according to claim 1, wherein the strain amount A of the pressure-sensitive adhesive layer is 700 µm or more and 1,300 µm or less. The polarizing plate according to claim 1, wherein the acrylic polymer has a mass average molecular weight of 300,000 to 2.5 million. The polarizing plate according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive composition further contains an isocyanate-based crosslinking agent. The polarizing plate according to claim 1, wherein the transparent support is made of cellulose acylates. The polarizing plate according to claim 1, wherein at least one of a hard coat layer having hard coat properties and an antireflection layer is formed on the low moisture permeation protective film. A liquid crystal display device comprising the polarizing plate according to claim 1 and a liquid crystal cell.