JPH09281333A - Protective film for polarizing plate and polarizing plate using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a protective film which can be easily adhered to a polarizing film by forming a layer containing copolymers which contain styrenes or vinyl esters, and maleic acid anhydrides, and acrylates or methacrylates as monomers on the surface of the film facing a polarizing film. SOLUTION: A layer containing copolymers and/or hydrolyzed copolymers containing styrenes or vinyl esters, and maleic acid anhydrides, and acrylates or methacrylates as monomers is formed on the surface of a transparent resin film facing a polarizing film. As for the copolymers containing these monomers, copolymers containing -COOM are preferable, and a compd. expressed by formula is more preferable. In formula, A is the structural unit produced by polymn. of styrene monomers or vinyl ester monomers, M is a hydrogen atom or cation, R1 is -O-R' (R' is alkyl group or the like), etc., R2 and R3 are hydrogen atoms or lower alkyl groups, m and p to s represent mol% of the respective monomer, and m is 0 to 60 and p to s are 0 to 100 satisfying m+p+q+r+s=100.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polarizing plate protective film and a polarizing plate, and more particularly to a polarizing plate protective film having excellent adhesiveness and a polarizing plate having excellent durability.

[0002]

2. Description of the Related Art A polarizing plate in which a cellulose triacetate (hereinafter referred to as "TAC") film is bonded as a protective film to a polarizing film which is a dye-uniaxially stretched polyvinyl alcohol (hereinafter referred to as "PVA") film is widely used as a liquid crystal. As a display element, it is used in the display unit of calculators, personal computers, word processors, etc. In recent years, the polarizing plate for liquid crystal, which is being used in a harsh environment such as a liquid crystal display mounted on an automobile, or is being used for a display of a large-sized liquid crystal television, is required to have higher durability. .

Conventionally, the most widely used protective film for a polarizing plate is that the surface of a TAC film is preliminarily saponified with an alkaline solution to improve the adhesiveness with a polarizing film, and the PVA adhesive is used. A polarizing plate is made by bonding it to a polarizing film with an agent or the like.

[0004]

However, since a high-concentration alkaline solution is used to produce a protective film saponified by an alkaline solution as in the prior art, it is necessary to pay sufficient attention to work safety. The production efficiency was not satisfactory. Further, although the adhesion improving technique by the saponification with an alkaline solution is effective for a specific transparent resin film, it is not applicable to all transparent resin films, and various transparent resin films, for example, polycarbonate resins are used. When it is desired to use it as a protective film for a polarizing plate, a new means for easy adhesion becomes necessary. Further, in order to produce a highly durable polarizing plate, good adhesion between the polarizing plate protective film and the polarizing film is important, and a means for imparting excellent adhesiveness was required.

That is, the first object of the present invention is to provide a protective film for a polarizing plate, which is easily adhered to a polarizing film.

A second object of the present invention is to provide a protective film for a polarizing plate having excellent adhesiveness by a method which is safe in work and does not adversely affect the environment.

A third object of the present invention is to provide a polarizing plate having excellent durability.

[0008]

Means for Solving the Problems That is, the present invention provides (1)
On the side where at least the polarizing film of the transparent resin film exists,
A copolymer containing at least styrenes or vinyl esters, maleic anhydrides, acrylic acid esters or methacrylic acid esters as monomers, and / or a layer containing a hydrolyzate of the copolymer, The present invention relates to a protective film for a polarizing plate.

The present invention also provides (2) at least styrenes or vinyl esters, maleic anhydrides, acrylic acid esters or methacrylic acid esters as monomers on the side of the transparent resin film where at least the polarizing film is present. The present invention relates to a polarizing plate using a protective film for a polarizing plate having a layer containing a copolymer containing the same and / or a hydrolyzate of the copolymer.

The present invention also provides (3) at least styrenes or vinyl esters, maleic anhydrides, acrylic acid esters or methacrylic acid esters as monomers on the side of the transparent resin film where at least the polarizing film is present. The present invention relates to a protective film for a polarizing plate, which comprises a layer containing at least one hydrophilic polymer compound on a layer containing the copolymer or / and the hydrolyzate of the copolymer.

The present invention also provides (4) at least styrenes or vinyl esters, maleic anhydrides, acrylic acid esters or methacrylic acid esters as monomers on the side of the transparent resin film where at least the polarizing film is present. A protective film for a polarizing plate having a layer containing at least one hydrophilic polymer compound on a layer containing a copolymer containing the same and / or a hydrolyzate of the copolymer is used. Regarding a polarizing plate.

The transparent resin film according to the present invention is not particularly limited and can be appropriately selected and used from known transparent resin films. As a transparent resin for forming such a film, for example, a cellulose resin such as cellulose triacetate, a polyester resin such as polyethylene terephthalate and polyethylene naphthalate, a polycarbonate resin, a styrene resin such as syndiotactic polystyrene. , And resins containing polyarylate-based resins, norbornene-based polyolefins resins, polysulfone-based resins, etc. as the main components are preferred, but in view of exerting the effect of the present invention, particularly polyester-based resins, polycarbonate-based resins, syndiotactic A styrene resin such as tic polystyrene, a polyarylate resin, a norbornene polyolefin resin and a polysulfone resin are preferable, and a polycarbonate resin is more preferable.

As the polycarbonate-based resin which is particularly preferably used in the present invention, various resins can be used, but from the viewpoint of chemical properties and physical properties, aromatic polycarbonate is preferable, and bisphenol A-based resin is particularly preferable. More preferably, among the bisphenol A derivatives in which benzene ring, cyclohexane ring, aliphatic hydrocarbon group, etc. are introduced into bisphenol A, the anisotropy in the unit molecule obtained by using the derivative introduced asymmetrically with respect to the central carbon Reduced structure polycarbonates are preferred. For example, a benzene ring in which two methyl groups at the central carbon of bisphenol A are substituted, and one hydrogen atom in each benzene ring of bisphenol A is asymmetrically substituted with a methyl group or a phenyl group at the central carbon. The polycarbonate obtained by using it is mentioned.

Specifically, it is obtained from a 4,4'-dihydroxydiphenylalkane or a halogen-substituted product thereof by a phosgene method or a transesterification method, for example, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylmethane.
4'-dihydroxydiphenylethane, 4,4'-dihydroxydiphenylbutane and the like can be mentioned.

The method for producing the polycarbonate resin film used in the present invention is not particularly limited. That is, any of the extrusion method, the solvent casting method, the calendar method and the like may be used. In the present invention, a uniaxially stretched film or a biaxially stretched film may be used, but in view of excellent surface accuracy, the film produced by the solvent casting method has a small optical isotropy and anisotropy. Then, a film produced by an extrusion method is more preferable.

The polycarbonate resin used in the present invention has a glass transition point (Tg) of 110 ° C. or higher and a water absorption rate (value measured in water at 23 ° C. for 24 hours) of 0.3% or less. It is better to use one. More preferably, Tg is 120 ° C. or higher and the water absorption rate is 0.2.
% Or less is good.

The polyester constituting the polyester resin which can be preferably used in the present invention is not particularly limited, but it is a polyester having a film-forming property containing a dicarboxylic acid component and a diol component as main components. is there.

The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, and 2,6-
Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylethanedicarboxylic acid,
Examples thereof include cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, diphenylthioetherdicarboxylic acid, diphenylketonedicarboxylic acid, and phenylindanedicarboxylic acid. As the diol component, ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexane dimethanol,
2,2-bis (4-hydroxyphenyl) propane,
2,2-bis (4-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like can be mentioned.

Among the polyesters containing these as main constituents, from the viewpoints of transparency, mechanical strength, dimensional stability, etc., as dicarboxylic acid components, terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and diol components. Polyesters whose main constituents are ethylene glycol and / or 1,4-cyclohexanedimethanol are preferred. Among them, polyesters containing polyethylene terephthalate or polyethylene-2,6-naphthalate as a main constituent, copolymerized polyesters containing terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and two or more of these polyesters Polyesters whose main constituent is a mixture are preferred.

The polyester constituting the polyester film used in the present invention may be copolymerized with other copolymerization components as long as the effects of the present invention are not impaired, and other polyesters may be mixed. It may be done. Examples of these include the above-mentioned dicarboxylic acid component and diol component, and polyesters composed thereof.

For the purpose of improving the heat resistance of the film, a bisphenol compound, a compound having a naphthalene ring or a cyclohexane ring can be copolymerized. The copolymerization ratio is preferably from 1 to 20 mol% based on the bifunctional dicarboxylic acid constituting the polyester.

The syndiotactic polystyrene resin preferably used in the present invention is a film containing syndiotactic polystyrene (SPS) as a main component, and the stereoregular structure (tacticity) is mainly a syndiotactic structure. That is, it has a three-dimensional structure in which phenyl groups and substituted phenyl groups that are side chains are alternately located in opposite directions with respect to the main chain formed from carbon-carbon bonds, and the main chain of the main chain is a racemo chain. A styrene-based polymer or a composition containing the styrene-based polymer, and a styrene homopolymer can be polymerized by the method described in JP-A-62-117708. JP-A-1-46912 and 1-17.
It can be prepared by forming a film obtained by polymerization according to the method described in No. 8505.

The polyarylate resin preferably used in the present invention is a polycondensation polymer of a bisphenol and an aromatic dicarboxylic acid. Among them, particularly preferable is a condensation of bisphenol A and phthalic acid as main monomers. Examples thereof include polymers.

The norbornene-based polyolefin resin film preferably used in the present invention is an amorphous polyolefin film having a norbornene structure, such as APO manufactured by Mitsui Petrochemical Co., Ltd. or ZEONEX manufactured by Nippon Zeon Co., Ltd. There are ARTON manufactured by Nippon Synthetic Rubber Co., Ltd.

The polysulfone resins preferably used in the present invention include poly (oxy-1,4-phenylene sulfone-1,4-phenylene) and poly (oxy-
1,4-phenylene isopropylidene-1,4-phenyleneoxy-1,4-phenylenesulfonyl-1,4-
Phenylene) is the most suitable.

The transparent resin film preferably used in the present invention may mainly contain the above resins.

It may be formed by mixing with another transparent resin such as a styrene resin, a methyl methacrylate resin or a cellulose acetate resin, and at least one of other transparent resin films such as a cellulose acetate film. The above-mentioned carbonate-based resin or the like may be laminated on the side.

The polarizing film according to the present invention is an element that allows only light having a polarization plane in a certain direction to pass therethrough. A typical polarizing film known at present is a polyvinyl alcohol-based polarizing film.
This includes a polyvinyl alcohol-based film dyed with iodine and a dichroic dye. Those used are those obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxially stretching it, or dyeing it and then uniaxially stretching it, and then preferably subjecting it to a durability treatment with a boron compound. The protective film for a polarizing plate of the present invention is laminated on the surface of the polarizing film to form a polarizing plate.

The copolymer containing at least styrenes or vinyl esters, maleic anhydride, acrylic acid esters or methacrylic acid esters as monomers according to the present invention means styrenes and maleic anhydride as monomers. Copolymers containing acids and methacrylic acid esters, styrenes, maleic anhydrides and methacrylic acid esters, vinyl esters, maleic anhydrides and methacrylic acid esters, vinyl esters It may be a copolymer containing maleic anhydride and methacrylic acid esters.

Examples of styrenes or vinyl esters used as monomers include styrene or nitro groups,
Fluorine atom, chlorine atom, bromine atom Fluoromethyl group, styrene substituted by a lower alkyl group and the like, vinyl methyl ether, vinyl ethyl ether, vinyl chloroethyl ether, vinyl acetate, vinyl chloroacetate, vinyl propionate and the like. Of these, styrene, styrene having a substituent and vinyl acetate are particularly preferable.

Examples of maleic anhydrides used as monomers include maleic anhydride, citraconic anhydride and pyrocinconic anhydride, maleic anhydride having an alkyl group such as γ-methylcitraconic acid and xeronic acid. Can be mentioned.

Examples of acrylic acid esters used as monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate and t-octyl acrylate, 2-chloroethyl acrylate, 2-bromoethyl acrylate, 4 -Halogen-substituted alkyl acrylates such as chlorobutyl acrylate, and substitutions such as cyanoethyl acrylate, 2-acetoxyethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate, 2-chlorocyclohexyl acrylate, 2-methoxyethyl acrylate, etc. Substituted or unsubstituted aryl acrylates such as unsubstituted alkyl acrylates and phenyl acrylates may be mentioned.

Examples of methacrylic acid esters used as monomers include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, sulfopropyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxy. Substituted or unsubstituted alkyl methacrylates such as ethyl methacrylate and acetoacetoxyethyl methacrylate, furfuryl methacrylate, phenyl methacrylate, and substituted or unsubstituted aryl methacrylates such as naphthyl methacrylate, triethylene glycol monomethacrylate, ω- Methoxy polyethylene glycol methacrylate (addition mol number n = 6) and the like can be mentioned.

A particularly preferred copolymer containing the above-mentioned monomers is a copolymer containing -COOM groups.
Those represented by the general formula [1] are most preferable.

[0035]

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In the formula, A represents a structural unit formed by polymerization of a styrene monomer or a vinyl ester monomer, and M represents a hydrogen atom or a cation. R ₁ is -OR 'or -N
(R ′) (R ″), wherein R ′ represents an alkyl group, an aralkyl group, an aryl group, a heterocyclic residue or a nonmetallic atom necessary for forming a heterocycle in cooperation with R ″, R ″ represents a hydrogen atom, a lower alkyl group or a non-metal atom necessary for forming a heterocycle together with R ′, R ₂ and R ₃ each represent a hydrogen atom or a lower alkyl group, and m, p , Q,
r and s are values showing the mol% of each monomer, respectively, m is 0 to 60, p, q, r, and s are each 0 to 10.
0 and m + p + q + r + s = 100.

Further, in the above formula, the alkyl group represented by R 'described in R _1, preferably those having 1 to 24 carbon atoms, may be linear alkyl group, branched alkyl group and cycloalkyl group, Further, the alkyl group may have a substituent, and as the substituent, a hydroxyl group,
A hydroxycarbonyl group, -COOM '(M' represents a cation) group and the like, and particularly a halogenoalkyl group having 2 to 18 carbon atoms or a halogenoalkyloxy having 2 to 18 carbon atoms substituted with a halogen atom such as a fluorine atom. Alkyl groups give particularly favorable results for the purposes of the invention.
The number of halogen atoms substituted in the halogenoalkyl group and the halogenoalkyloxyalkyl group is preferably 1 to
37.

In the present invention, the —COOM group-containing polymer compound represented by the above general formula [1] is used alone or in combination of two or more kinds, and preferably has an average molecular weight of about 500.
Approximately 500,000 (weight average) is used.

Typical examples of the above polymer compound used in the present invention include the following. However, the present invention is not limited to these.

[0040]

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[0041]

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[0042]

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[0043]

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The hydrolyzate of the copolymer which can be used in the present invention may be the one obtained by actively hydrolyzing the copolymer by an alkaline treatment in water or the like. It may be one which is left to be gradually hydrolyzed and is preferably the case where r = 0 in the general formula [1].

The copolymer used in the present invention represented by the above general formula [1] can be synthesized by a known method. For example, Journal of Photogra
fic Science 5,253 (1950), J
annual of theAmerican Che
medical Society 70, 1523 (194)
8) etc.

Used in the protective film for polarizing plate of the present invention,
Copolymer containing styrene or vinyl ester, maleic anhydride, acrylic acid ester or methacrylic acid ester as a monomer or / and a hydrolyzate of the copolymer may be one kind or two or more kinds. may be used in combination, its amount is preferably 10~3000mg / m ^2, and particularly preferably even at 20~1000mg / m ^2.

In the present invention, at least one kind of monomer is further provided on the layer containing a copolymer containing at least styrenes or vinyl esters, maleic anhydrides and acrylic acid esters or methacrylic acid esters as monomers. It is preferable to provide a layer containing a hydrophilic polymer compound because the adhesive force is further enhanced and the effect of the present invention is exhibited.

The hydrophilic polymer compound according to the present invention includes a natural hydrophilic polymer compound and a synthetic hydrophilic polymer compound. Examples of the natural hydrophilic polymer compound include gelatin, casein, gum arabic and the like. Examples of the synthetic hydrophilic polymer compound include hydrophilic cellulose derivatives (eg, methyl cellulose, carboxymethyl cellulose, hydroxy cellulose, etc.), polyvinyl alcohol derivatives (eg, polyvinyl alcohol, vinyl acetate-vinyl alcohol copolymer, polyvinyl Acetal,
Polyvinyl formal, polyvinyl benzal, etc.), hydrophilic polyester derivatives (for example, partially sulfonated polyethylene terephthalate, etc.), polyvinyl derivatives (for example, poly-N-vinylpyrrolidone, polyacrylamide, polyvinyl imidazole, polyvinyl pyrazole, etc.) Etc.

The hydrophilic polymer compound according to the present invention may be used alone or in combination of two or more kinds. Further, the coating liquid containing the hydrophilic polymer compound may contain an ultraviolet absorber, a plasticizer, a slip agent, a crosslinking agent and the like. A cross-linking agent is particularly preferable for promoting the adhesion of the polarizing film with the PVA film. Examples of such a crosslinking agent include polyvalent epoxy compounds, aziridine compounds, isocyanate compounds and alum,
Examples thereof include boron compounds.

The amount of the hydrophilic polymer compound according to the present invention is preferably in the range of 10 to 1000 mg / m ² , and particularly ^{2 in view} of stable adhesive force and finish after coating.
The range of 0 to 300 mg / m ² is preferable.

The thickness of the protective film for a polarizing plate of the present invention produced as described above is not particularly limited, but from the viewpoint of function and easiness of handling, it is 10 to 500 μm, particularly 30 to 3 μm.
00 μm is preferred.

The layer provided on the surface of the transparent resin film of the present invention is in the form of a coating solution in which a desired compound is dissolved or dispersed in a solvent, and is known in the art such as a gravure coater, a dip coater, a reverse roll coater and an extrusion coater. It can be formed by coating on the surface of the protective film by the above method.

The method of applying the coating liquid and then drying it is not limited, but in order to prevent bubbles from being generated at the adhesive interface between the protective film of the present invention and the polarizing film, the residual solvent amount after drying is 5 wt% or less. Is preferred.

Examples of the adhesive used for adhering the protective film for a polarizing plate of the present invention and the polarizing film include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latex such as butyl acrylate and the like. Can be used.

Further, the present invention contains at least styrenes or vinyl esters, maleic anhydrides, acrylic acid esters or methacrylic acid esters as monomers provided on at least the side where the polarizing film is present in the transparent resin film. When the layer containing the copolymer or / and the hydrolyzate of the copolymer is a protective film for a polarizing plate containing inorganic fine particles and / or organic fine particles, the blocking effect can be obtained in addition to the effects of the present invention. It is particularly preferable in that it is improved.

The inorganic fine particles preferably used in the present invention include silicon oxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate and the like, and the organic fine particles include Polymethacrylic acid methyl acrylate resin, silicon resin, polystyrene resin, polycarbonate resin, acrylic styrene resin, benzoguanamine resin, melamine resin, and further polyolefin resin,
Polyester resin, polyamide resin, polyimide resin, polyfluorinated ethylene resin, etc. can be used. The volume average particle diameter of these fine particles is preferably 0.01 to 1
0 μm, coating amount is preferably 0.005-500 mg /
m ² range, particularly preferably 0.01 to 200 m
g / m ² is preferred.

In particular, it is more preferable that the surface of the protective film for a polarizing plate of the present invention, which is opposite to the side where the polarizing film is present, is subjected to curl prevention treatment with an organic solvent.

The anti-curl processing applicable to the present invention means that a good solvent and a poor solvent are mixed with a transparent resin film at an appropriate ratio, and the mixed solvent is a gravure coater, a dip coater, a reverse coater, It can be formed by coating on the surface of the film by a known method such as an extrusion coater. The coating amount of the mixed solvent is preferably in the range of 5 to 50 μm / m ² , and may be adjusted according to the desired curl.

[0059]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these embodiments.

<Preparation of Sample 1 (Comparative Sample)> The following dope composition A was prepared.

Polycarbonate resin 100 parts by weight (viscosity average molecular weight 40,000, bisphenol A type) [2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole] 1.2 parts by weight Methylene Chloride 430 parts by weight Methanol 90 parts by weight Each of the above substances is put into one closed container, and the mixture is placed under pressure for 8 hours.
The dope composition A was obtained by keeping the temperature at 0 ° C. and completely dissolving it while stirring.

Next, this dope composition A was filtered, cooled and kept at 33 ° C. and evenly flowed on a rotating endless stainless steel band having a length of 6 m (effective length of 5.5 m) stretched between two drums. When the solvent was evaporated and the solvent was evaporated until it could be peeled off, after peeling from the stainless steel band, the drying was completed while being conveyed by a number of rolls to obtain a polycarbonate film A having a thickness of 80 μm. This was designated as Sample 1 of the protective film.

<Preparation of Sample 2 (Comparative Sample)> Polycarbonate film A which is Sample 1 has a liquid temperature of 60 ° C. and 8 wt%
Sample 2 was a film obtained by immersing in a sodium hydroxide solution of 3 minutes, washing with water and drying.

<Preparation of Sample 3 (Comparative Sample)> A coating solution a having the following composition was applied in an amount of 20 ml / m ^{2 on} one surface of the polycarbonate film A which is Sample 1, and dried at 100 ° C. for 10 minutes to obtain Sample 3. .

Composition of coating liquid a Comparative compound 1-1 0.5 g Methylene chloride 2.0 ml Ethyl acetate 30 ml Acetone 60 ml Isopropanol 8.0 ml <Preparation of samples 4, 5 and 6 (sample of the present invention)> Polycarbonate as sample 1 Coating liquids b, c, and d having the following compositions on one surface of the film A (on the side where the film is to be attached to the polarizing film)
20 ml / m ^{2 and} dried at 100 ° C. for 10 minutes,
Samples 4, 5 and 6 were obtained.

[0066]

[Table 1]

<Preparation of Samples 7, 8 and 9 (Samples of the Present Invention)> 20 ml / m of a coating solution e having the following composition was further applied to the surfaces of Samples 4, 5 and 6 on which the polarizing film was to be attached.
² Apply each and dry at 100 ° C for 10 minutes to obtain sample 7,
8 and 9 were obtained.

[0068]

[Table 2]

<Preparation of Samples 10 and 11 (Comparative Sample)>
20 ml / m ² of coating liquids f and g having the following compositions were applied to one side of the cellulose triacetate film having a thickness of 80 μm (on the side to be attached to the polarizing film), and the coating liquid was applied at 100 ° C. for 10 minutes.
Samples 10 and 11 were obtained after drying for one minute.

[0070]

[Table 3]

<Preparation of Samples 12 and 13 (Samples of the Present Invention)> A coating solution h having the following composition was applied at 20 ml / m ^{2 on} one surface (side to be bonded to the polarizing film) of a cellulose triacetate film having a thickness of 80 μm. 1 at 100 ° C
Sample 12 was obtained after drying for 0 minutes.

Composition of Coating Liquid h Exemplified Compound 2-1 0.5 g Ethyl acetate 50 ml Acetone 40 ml Isopropanol 10 ml Next, on the side of Sample 12 coated with the coating liquid h, the coating liquids used when Samples 7, 8 and 9 were prepared. 20 ml / m ²
Sample 13 was prepared by coating.

<Preparation of Samples 14 and 15 (Samples of the Present Invention)> On one surface of polycarbonate film A, which is Sample 1, (on the side where the polarizing film is to be attached), a coating solution i having the following composition is applied in an amount of 20 ml / m ^2. After drying at 100 ° C. for 10 minutes, Sample 14 was obtained.

Composition of Coating Liquid i Exemplified Compound 5-1 1.5 g Acetone 85 ml Methylpyrrolidone 5 ml Tetrahydrofuran 10 ml Next, the coating liquid used in preparing Samples 7, 8 and 9 on the side of Sample 14 coated with the above coating liquid i. 20 ml / m ²
Sample 15 was prepared by coating.

<Preparation of Sample 16 (Sample of the Present Invention)> Sample 1
20 m of a coating liquid j having the following composition is applied to one surface of the polycarbonate film A (the side where the polarizing film is to be bonded).
1 / m ^{2 was} applied and dried at 100 ° C. for 10 minutes. On the coating layer, 20 ml / m ^{2 of} the coating liquid e used for preparing Samples 7, 8 and 9 was applied to prepare Sample 16.

Composition of coating liquid j Exemplified compound 5-2 0.5 g Exemplified compound 3-2 1.5 g Acetone 65 ml Methylpyrrolidone 5 ml Methylene chloride 30 ml <Preparation of sample 17 (sample of the present invention)> Syndiotactic polystyrene having a film thickness of 100 μm After corona discharge treatment (treatment intensity 20 W / m ² / min) on one side of the film (hereinafter referred to as SPS) (the side on which the polarizing film is to be attached), a coating solution k having the following composition is applied at 100 ° C. Dry for minutes. On the coating layer, 20 ml / m ^{2 of} the coating liquid e used in preparing Samples 7, 8 and 9 was applied to prepare Sample 17.

Composition of coating liquid k Exemplified compound 3-1 1.5 g Polystyrene resin 0.5 g [trade name: Relex XGPPS550-51, manufactured by Mitsui Toatsu Chemicals, Inc.] Acetone 40 ml Ethyl acetate 45 ml Toluene 10 ml Isopropanol 5 ml <Sample Preparation of 18 (sample of the present invention)> Corona discharge treatment (treatment strength 20
W / m ² / min), and then a coating solution 1 of the following composition
A sample 18 was obtained by applying a coating solution of ml / m ² and drying at 100 ° C. for 10 minutes.

Composition of coating liquid 1 Exemplified compound 2-5 1.5 g Saturated polyester resin 1.0 g [Brand name: Byron, Tg = 67 ° C., Toyobo Co., Ltd.] Acetone 40 ml Ethyl acetate 50 ml N, N-Dimethylformamide 10 ml <Preparation of Sample 19 (Sample of the Present Invention)> Sample 1 was prepared by further applying 20 ml / m ^{2 of} the coating liquid e used in preparation of Samples 7, 8 and 9 to the surface of Sample 18 on the side to be bonded to the polarizing film.
9 was obtained.

The compounds for comparison are shown below.

[0080]

[Chemical 6]

<Production of Polarizing Plates 1 to 19> First, the thickness 12
A 0 μm polyvinyl alcohol film was immersed in an aqueous solution containing 1 part by weight of iodine, 2 parts by weight of potassium iodide, and 4 parts by weight of boric acid, and stretched 4 times at 50 ° C. to obtain a polarizing film.
Next, the polarizing film was prepared by laminating the polarizing film and the protective film samples 1 to 19 in the following steps.

Sample 1 cut to 18 cm × 5 cm
Two sets of 19 are prepared, and one set is placed on a glass plate with the side bonded to the polarizing film facing up.

A polarizing film made of a uniaxially stretched polyvinyl alcohol dyeing film of 18 cm × 5 cm was dipped in a polyvinyl alcohol adhesive tank having a solid content of 2 wt% for 1 to 2 seconds so that 19 sheets were prepared. To do.

The excess adhesive adhered in step (1) is lightly removed and placed on each of the samples (1) to (19).

Another set of samples 1 to 19 prepared in
Place it on top of the one prepared in (to make a sandwich with the same type of sample).

The laminates of Samples 1 to 19 and the polarizing film prepared in 1 and 2 above are laminated using a hand roller while removing excess adhesive and air bubbles.

The laminated film is inserted into a laminator pressurized to ² to 3 kg / cm ² and laminated at a laminating speed of about 2 m / min.

The samples prepared in 1 to 3 were left in a dryer at 80 ° C. for 2 minutes.

The polarizing plates 1 to 19 were prepared using the samples 1 to 19 respectively.

1) Initial Adhesion: After the polarizing film and Samples 1 to 19 were bonded together, they were peeled by hand, and the degree of occurrence of material destruction was evaluated according to the following three grades.

(Judgment Criteria) ◯: Material breakage occurs Δ: Partial material breakage occurs, but the peeling area is large between Samples 1 to 19 and the polarizing film ×: Peeling between sample film and polyvinyl alcohol film 2) Processing Gender: A dumbbell cutter was used to judge the degree of floating of the punched adhesive surface.

(Judgment Criteria) ◯: 0.1 mm or less x: 0.1 mm or more 3) Durability Leave at 500 ° C. for 90 hours under 90% RH conditions (A) and 90 ° C. conditions (B) for 500 hours. The appearance change was observed and the width of peeling from the edge was measured. The evaluation symbols shown in Table 4 are as follows.

◯: Within 0.5 mm Δ: 0.5 to 1.5 mm ×: 1.5 mm or more 4) Transmittance The transmittance of each of Samples 1 to 19 was measured by using MPS-2000 manufactured by Shimadzu Corporation. Used, wavelength 350-700
It was measured in the range of nm.

5) Dimensional shrinkage ratio For each of the samples 1 to 19, 150 mm × 120 m
Cut into m size and 2 at 100mm intervals on the film surface.
Scratch the place (x, y) with a razor, 23 ℃, 55
The humidity was adjusted for 24 hours under the condition of% RH. Next, the dimension between x and y is measured, and the dimension value at this time is defined as L ₀ . Next, after leaving these Samples 1 to 19 in an electric constant temperature bath set at 105 ° C for 7 hours, the humidity was again conditioned under the conditions of 23 ° C and 55% RH for 24 hours, and the dimension between xy was measured. Is measured and the dimension value at this time is defined as L ₁ . The dimensional shrinkage is expressed by the following equation.

Dimensional shrinkage rate (%) = [(L ₁ −L ₀ ) / L ₀ ] × 100 6) Moisture and heat resistance One of the polarizing plates 1 to 19 prepared by the above method, coated with an adhesive, is glass. It stuck on the board and each polarization degree was measured. The degree of polarization was measured by leaving it in a constant temperature and humidity chamber at 65 ° C. and 95% RH for 700 hours, and the rate of change in the degree of polarization was determined.

The degree of polarization as used in the present invention is represented by [(H ₁₁ -H ₁ ) / (H ₁₁ + H ₁ )] ^1/2 × 100 (%), and H ₁₁ is a superposition of two polarizing plates. At that time, the transmittance (%) measured by using a spectrophotometer in a state where the polarizing plates are laminated so that the orientation directions thereof are the same,
H ₁ is the transmittance (%) measured in a state where two polarizing plates are superposed so that the orientation directions of the polarizing plates are orthogonal to each other.

The polarization degree is measured by Tokyo Denshoku Co., Ltd. TOPSC.
AN TC-1800LP was used.

<Judgment Criteria> ○: Polarization degree change rate of 10% or less Δ: Polarization degree change rate of 10 to 25% ×: Polarization degree change rate of 25 to 40% XX: Polarization degree change rate of 40% or more 7) Water resistance Test The polarizing plates 1 to 19 prepared by the above method were immersed in warm water at 60 ° C., and the time until the peeling between the samples 1 to 19 and the polarizing film was measured.

<Judgment Criteria> ◯: Peeling off after 3 hours Δ: Peeling off within 1 to 3 hours x: Peeling off within 1 hour The evaluation results are shown in Table 4.

[0100]

[Table 4]

As is clear from the results shown in Table 4, the protective film sample for a polarizing plate of the present invention is excellent in transparency, adhesiveness, dimensional stability and wet heat resistance.

[0102]

The protective film for polarizing plate according to the present invention comprises
Compared with a protective film for a polarizing plate using a conventional cellulose acetate film, it is superior in dimensional stability and resistance to moist heat, and also has excellent adhesiveness to a PVA film which is a polarizing film, and can be punched in a polarizing plate manufacturing process. It was possible to obtain an excellent protective film for a polarizing plate, which did not peel even after long-term aging under wet heat and high temperature conditions.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09J 131/02 JCW C09J 131/02 JCW 133/04 JDB 133/04 JDB 135/00 JDA 135/00 JDA G02B 1/04 G02B 1/04

Claims (4)

[Claims] 1. A copolymer containing at least a styrene or vinyl ester, a maleic anhydride, an acrylic acid ester or a methacrylic acid ester as a monomer on at least the side of the transparent resin film where the polarizing film is present, or And a protective film for a polarizing plate comprising a layer containing a hydrolyzate of the copolymer. 2. A polarizing plate using the protective film for polarizing plate according to claim 1. 3. A copolymer containing at least a styrene or vinyl ester, a maleic anhydride, an acrylic acid ester or a methacrylic acid ester as a monomer on at least the side where the polarizing film is present in the transparent resin film, or / And a protective film for a polarizing plate, comprising a layer containing at least one hydrophilic polymer compound on a layer containing a hydrolyzate of the copolymer. 4. A polarizing plate using the protective film for polarizing plate according to claim 3.