JPH09113728A - Protective film for polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a protective film having excellent scratching resistance, chemical resistance, flexibility, antidazzle property and excellent adhesion property between the protective film and a polarizing film by forming a hardened coating film comprising a compsn. containing a UV-curing polyol acrylate resin on a transparent resin film. SOLUTION: A hardened coating film layer 2 comprising a compsn. containing a UV-curing polyol acrylate resin is formed on at least one surface of a transparent resin film 1. The hardened coating film layer 2 contains inorg. or org. fine particles. Or, an easy adhesion layer 3 containing a hydrophilic polymer compd. may be formed on the opposite surface of the transparent resin film 1 to the surface where the hardened coating film layer 2 is formed. The UV-curing polyol acrylate resin consists of dipenta-erythritol hexaacrylate. Further, a UV absorbent or antioxidant may be added to the compsn. containing the UV- curing polyol acrylate resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a protective film for a polarizing plate. More specifically, it is used for applications requiring optical performance, for example, a transparent resin film which is widely used for a polarizing plate of a liquid crystal display device. And a transparent resin film to which antiglare property is imparted.

[0002]

2. Description of the Related Art Cellulose ester films, especially cellulose triacetate films, are widely used in optical applications such as polarizing plates because they have excellent transparency and can easily form a film having a small anisotropy in refractive index. There is.

In particular, a polarizing plate excellent in abrasion resistance, chemical resistance and antiglare property is obtained by improving and using the above film as a protective film of a polarizing plate to be laminated on an iodine or dichroic dye type polarizing film. Various attempts have been made to make them.

When a liquid crystal display is constructed using such a polarizing plate, an extra protective plate or protective film for the polarizing plate is unnecessary, and a lightweight, thin, highly visible display can be obtained.

Liquid crystal displays are being widely used for displays of calculators, watches, pocket televisions, personal computers, in-vehicle instruments, etc., and as the screen becomes larger, the display becomes thinner, lighter, and higher in image quality. It has become an important goal of development along with commercialization and colorization.

In a conventional liquid crystal display, since a normal polarizing plate is inferior in scratch resistance and chemical resistance, a glass or transparent plastic plate should be provided on the outermost surface of the display body to protect the polarizing plate. did not become.

For this reason, a molded polarizing film, that is, a polarizing film and a transparent plastic film such as cellulose triacetate bonded to each other are bonded to a polyester acrylate resin, (meth) acrylic acid ester resin, acrylic urethane resin, etc. A hardened coating film is provided to improve wear resistance and chemical resistance.
No. 41, JP-A-1-105738, etc., but this method has a drawback that a protective material is required and the polarizing plate itself becomes thick or heavy.

Also, in Japanese Utility Model Publication No. 54-130441, S
A method for improving abrasion resistance by vapor deposition of iO ₂ , silicone apsite, phenol resin, etc. has been proposed, but it is still insufficient in terms of surface hardness and adhesiveness of a plastic substrate.

Japanese Unexamined Patent Publication (Kokai) No. 1-105738 proposes a method for improving scratch resistance and chemical resistance by providing a cured coating film made of an ultraviolet-curable epoxy acrylate resin on one surface of an unsaponified triacetate film. ing. However, if the hardened coating film is thickened to increase the surface hardness, cracks such as cracks are likely to occur, and saponification treatment cannot be performed. Therefore, when exposed to an atmosphere of high temperature and high humidity, the adhesiveness to the polarizing plate Has the drawback that it deteriorates.

In these applications of the polarizing plate, strong adhesion is required between the polarizing film and the protective film in order to exhibit high reliability and durability in various environments. As a method of improving this adhesiveness, in the case of the cellulose triacetate film which is most widely used as a protective film, the surface is saponified in advance with an alkaline solution, and then laminated with a polyvinyl alcohol adhesive or the like to obtain a polarizing film. . However, since the alkali treatment uses a high-concentration alkali solution, it is not preferable in terms of work safety and environmental protection, and further alkali treatment may lead to deterioration of quality such as bleed-out of plasticizer and increase in haze. is there.

Also, before the alkali treatment, antistatic treatment,
When the processing for imparting functionality such as hard coat processing is performed, the effect thereof is diminished by the alkali treatment, so that there is a problem that the functionalization of the protective film is limited after the alkali treatment.

[0012]

Therefore, the object of the present invention is to 1) firstly provide a protective film for a polarizing plate having excellent scratch resistance and chemical resistance, and 2) secondly, the protective film. To provide a protective film for a polarizing plate having excellent adhesiveness between a polarizing plate and a polarizing film 3) Thirdly, to provide a protective film for a polarizing plate having excellent flexibility 4) Fourthly, having an antiglare effect 5) Fifth, the adhesiveness to the polarizing film is excellent, and the UV absorbing ability is deteriorated or colored even when exposed to severe conditions under high temperature and high humidity for a long time. Providing a protective film for a polarizing plate that does not wear 6) Sixth, to provide a cellulose ester film with reduced cost by omitting the saponification treatment step. Other objects will be apparent from the following description.

[0013]

The object of the present invention can be achieved by any of the following constitutions.

(1) A protective film for a polarizing plate comprising a transparent resin film and a cured coating film layer formed on at least one surface of the transparent resin film, the cured coating film layer comprising a composition containing an ultraviolet curable polyol acrylate resin.

(2) The protective film for a polarizing plate as described in (1), wherein the UV-curable polyol acrylate resin is dipentaerythritol hexaacrylate.

(3) The polarized light as described in (1) or (2), characterized in that an easy adhesion layer containing a hydrophilic polymer compound is provided on the opposite surface of the transparent resin film to the side of the cured coating film. Protective film for board.

(4) The cured coating layer contains inorganic fine particles or organic fine particles (1), (2)
Alternatively, the protective film for a polarizing plate according to (3).

(5) An ultraviolet absorber or an antioxidant is contained in the composition containing the ultraviolet curable polyol acrylate resin (1), (2),
The protective film for a polarizing plate according to (3) or (4).

An example of the layer structure of the protective film for a polarizing plate of the present invention is shown in FIG.

In the present invention, as an example, the embodiment of FIG. 1 (a) in which the cured coating layer 2 is applied on the transparent resin film 1 is desirable. Further, an easy-adhesion layer 3 is provided on the surface of the transparent resin film opposite to the cured coating layer 2 as shown in FIG.
Thus, an embodiment in which the polarizing film is bonded is more preferable.

The transparent resin film used in the present invention is not particularly limited and can be appropriately selected and used from known transparent resin films. Examples of such a transparent plastic film include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, cellulose acetate propionate film, cellulose acetate butyrate. Rate film, polyvinyl chloride film,
Polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, polystyrene film, syndiotactic polystyrene film, norbornene resin film, polycarbonate film, polyarylate film, polymethylmethacrylate film, polyacrylate film, polyolefin norbornene resin film , Polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, nylon film, acrylic film and the like, in the present invention, , Especially polyethylene terephthalate film, polyethylene naphthalate Irumu, triacetyl cellulose film (triacetate film), polyarylate film, polymethyl methacrylate film or polycarbonate film is preferably used from the viewpoint of excellent transparency.

Particularly in the case of cellulose triacetate, a plasticizer-containing material such as triphenyl phosphate, biphenyl diphenyl phosphate, dimethyl ethyl phosphate, ethyl phthalyl ethyl glycolate is usually used.

Although these supports differ depending on the polymer species, they can be used properly depending on the application, from a thin film having a thickness of about 1 mm to about 20 μm. The most used layer is in the range of 30 to 150 μm in film thickness. If necessary, the protective film may contain an ultraviolet absorber, a plasticizer, a lubricant, a matting agent and the like.

The UV-curable polyol acrylate resin used in the present invention includes trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, Alkyl-modified dipentaerythritol A photopolymerizable monomer oligomer such as pentaerythritol. These polyol acrylate resins are characterized in that they are highly crosslinkable and have a high curability, have a high hardness and a small curing shrinkage, and have a low odor, low toxicity and relatively high safety.

The above UV-curable polyol acrylate resin may contain other UV-curable resin, for example, UV-curable epoxy resin, as long as its effect is not impaired. A cured coating film obtained by applying a thick film using an acrylate-based resin may have strong curling due to curing shrinkage, which may cause trouble in handling.

On the other hand, the epoxy resin generally has smaller curing shrinkage and curling of the cured coating film than the acrylate resin. The ultraviolet-curable epoxy resin referred to here is a compound containing two or more epoxy groups in the molecule, contains a cationic polymerization initiator, and is an epoxy resin that undergoes a crosslinking reaction when irradiated with ultraviolet rays.

Incidentally, in order to prevent the cured coating film from blocking and to provide an antiglare effect, the cured coating film may contain fine particle powder.

The inorganic fine particle powder used in the present invention includes silicon oxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, barium sulfate, talc,
Examples include kaolin and calcium sulfate.

As the organic fine particle powder, polymethacrylic acid methyl acrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, and further polyolefin resin. Resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluorinated ethylene resin powder and the like can be used.

The volume average particle diameter of these fine particle powders is 0.01 to 10 μm, and the ratio of the ultraviolet curable resin composition to the fine particle powder is 0.1 to 20 parts by weight based on 100 parts by weight of the resin composition. It is desirable to mix them in such a manner that they become parts. To impart the antiglare effect, the volume average particle diameter is 1 to 10 μm.
1 to 15 per 100 parts by weight of the resin composition
Parts by weight are preferred. A volume average particle diameter of 0.01 μm to 5 μm and 0.1 to 5 parts by weight relative to 100 parts by weight of the resin composition are suitable for merely providing antiblocking property.

Further, when the above ultraviolet curable resin is used as an ultraviolet curable resin composition, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetra Methyl thiuram monosulfide, thioxanthone, and n-butylamine, triethylamine, tri-n-butylphosphine, etc. are mixed and used as a photosensitizer.

In the composition containing the UV-curable resin used in the present invention, the polymerization initiator is generally preferably 0.1 to 15 relative to 100 parts by weight of the curable prepolymer.
Parts by weight, more preferably 1 to 10 parts by weight.

The ultraviolet-curable resin composition which can be used in the present invention contains, in addition to the above-mentioned polyol acrylate resin, colorants such as pigments and dyes, defoaming agents, thickeners, and the like, if necessary. Various additives such as a leveling agent, a flame retardant, an ultraviolet absorber and an antioxidant, a filler, a modifying resin and the like can be used in an appropriate amount.

In the present invention, when an ultraviolet curable composition is used as the curable composition, the light source for the irradiation light in the ultraviolet region (hereinafter, also simply referred to as ultraviolet ray) to be used is sunlight, low pressure mercury lamp, high pressure mercury lamp, There are ultra-high pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, etc.

The atmosphere for irradiating the ultraviolet rays may be air or an inert gas such as nitrogen gas or carbon dioxide gas.

The composition containing the ultraviolet curable resin according to the present invention may be applied alone or by diluting it in an organic solvent to a solid content concentration of 10 to 95% by weight, a gravure coater, a spinner coater, a wire bar coater, an extrusion coater. , Coated by a known method such as reverse coater, and after drying,
It is UV-curable. The dry film thickness at this time is arbitrary, but is preferably about 0.1 to 30 μm. More preferably, it is 0.5 μm to 15 μm.

The irradiation time of ultraviolet rays to the ultraviolet-curable composition which can be used in the present invention varies depending on the kind of the irradiation light source in the above-mentioned ultraviolet region, but is preferably 0.5 second to.
It is 5 minutes, more preferably 3 seconds to 2 minutes.

Usually, when the irradiation time is short, a large light source having a high irradiation intensity is required, and when the irradiation time is long, a light source having a low irradiation intensity can be used, but the curing time becomes long, which is disadvantageous in the manufacturing process. Is. However, according to the present invention, an ultraviolet lamp having a power of 200 W or less is used, and the time from 3 seconds to 2 seconds is increased.
It is advantageous that the purpose can be achieved by irradiation of minutes.

The ultraviolet absorber used in the present invention includes salicylic acid derivative (UV-1), benzophenone derivative (UV-2) and benzotriazole derivative (UV-).
3), an acrylonitrile derivative (UV-4), a benzoic acid derivative (UV-5), an organic metal complex salt (UV-6) and the like. Examples of the salicylic acid derivative (UV-1) include phenyl salicylate, 4-tert-butylphenylsalicylic acid and p-octylphenylsalicylic acid, and examples of the benzophenone derivative (UV-2) include:
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-di-hydroxy-4-methoxybenzophenone, 2-
Hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-
Sulfobenzophenone trihydrate, 2-hydroxy-4
-Octoxybenzophenone, 2-hydroxy-4
-Oxybenzylbenzophenone, 2-hydroxy-4-stearyloxybenzophenone, 2,2'-dihydrooxy-4,4'-dimethoxybenzophenone and the like can be mentioned. Benzotriazole derivative (UV-
3) includes 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)
-5-chlorobenzotriazole, 2- (2'-hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-
tert-butylphenyl) benzotriazole, 2-
(3,5-di-tert-acyl-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-
3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ',
5'-diisoamylphenyl) benzotriazole, 2
-(2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like are mentioned, and as an acrylonitrile derivative (UV-4), 2-ethylhexyl-
2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate,
Methyl-α-cyano-β-methyl-β- (p-methoxyphenyl) acrylate and the like can be mentioned. Examples of the benzoic acid derivative (UV-5) include resorcinol-monobenzoate, 2 ′, 4′-di-tert-. Butylphenyl-
3,5-di-tert-butyl-4-hydroxybenzoate and the like can be mentioned. Examples of the organic metal complex salt (UV-6) include nickel bis-octylphenyl sulfamide and [2,2′-thiobis (4-tert). -Octylphenolate)]-n-butylamine nickel, ethyl-
A nickel salt of 3,5-di-tert-butyl-4-hydroxybenzylphosphoric acid and the like can be mentioned.

These ultraviolet absorbers may be used in combination of two or more kinds. The amount of these ultraviolet absorbers is preferably 0.1 to 15% by weight, more preferably 0.5 to 8% by weight, based on the total amount of the ultraviolet curable composition of the present invention.

The antioxidant used in the present invention includes:
For example, a hindered phenol derivative (AO-1), a thiodipropionic acid derivative (AO-2), a phosphite derivative (AO-3) and the like can be mentioned. Specific examples of the hindered phenol derivative (AO-1) include 4,4′-
Thiobis (6-tert-3-methylphenol),
4,4'-butylidene bis (6-tert-butyl-3
-Methylphenol), 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol) 2,
2'-thiobis (6-tert-butyl-4-methylphenol), 2,6-di-tert-butylphenol, 4,4'-methylenebis (6-tert-butylphenol), 4,4'-bis (2,2 6-di-tert-
Butylphenol), 4,4'-methylenebis (6-t
ert-butyl-o-cresol), 4,4'-thiobis (6-tert-butyl-o-cresol), 1,
1,3-Tris (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 2,4,6-
Tris (3,5-di-tert-butyl-4-hydroxybenzyl) mesitylene, 1,3,5-Tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3 -Bis (3,5-
Di-tert-butyl-4-hydroxyphenyl)
-2,2'-bis (2-dodecylthionitoxycarbonyl) propane, 1,6-bis (3,5-bi-tert)
-Butyl-4-hydroxyphenylacetoxy) hexane, 6- (4-hydroxy-3,5-di-tert-butylanilino) -2,4-bis (n-octylthio) -1,3,5-triazine , Tetrabis [β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxymethyl] methane, n-octadecyl-3- (4′-hydroxy-
3 ', 5'-di-tert-butylphenyl) propionate, di-octadecyl-4-hydroxy-
3,5-di-tert-butylbenzylphosphonate,
Di-ethyl-4-hydroxy-3,5-di-ter
Examples thereof include t-butylbenzylphosphonate, and examples of the thiodipropionic acid derivative (AO-2) include dilauryl-3,3′-thio-di-propionate and di-stearylthio-di-propionate. Examples of the phyto derivative (AO-3) include tri-phenyl phosphite, trisnonyl phenyl phosphite, di-phenyl decyl phosphite, and di-cresyl phosphite.

These antioxidants may be used in combination of two or more kinds. The amount of these antioxidants is preferably 0.1 to 15% by weight, more preferably 0.2 to 6% by weight, based on the total amount of the ultraviolet curable composition of the present invention.

In the ultraviolet curable composition of the present invention, as long as it contains at least one selected from the above ultraviolet absorbers and antioxidants, only the ultraviolet absorbers, only the antioxidants, or a combination of both. May be. These may be dissolved directly or may be added after being dissolved in a solvent such as acetone, methanol, ethyl acetate or toluene in advance.

In the constitution of the protective film for a polarizing plate of the present invention, preferably, an ultraviolet curable coating film layer is provided on one side of the transparent resin film, and an easy adhesion layer for adhering to the polarizing film is provided on the opposite side thereof. .

The easily adhesive layer according to the present invention may be one layer or two or more layers. Examples of the hydrophilic polymer compound according to the present invention include -COOH group-containing polymer compounds, preferably -COOH group-containing vinyl acetate-maleic acid copolymers, hydrophilic cellulose derivatives, polyvinyl alcohol derivatives, and natural polymers. Examples thereof include compounds, hydrophilic polyester derivatives, polyvinyl derivatives and the like.

Further, as a more preferable form, —COO
A layer containing an H group-containing vinyl acetate-maleic acid copolymer,
Further on the polarizing film side adjacent to the layer, a hydrophilic cellulose derivative, a polyvinyl alcohol derivative, a natural polymer compound,
It is like providing a layer containing a hydrophilic polyester derivative, a polyvinyl derivative or the like.

The --COOM group-containing copolymer compound used in the present invention is preferably one represented by the following general formula [1] or [2].

[0048]

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In the formula, A is a vinyl monomer, B is a hydrogen atom,
-CO-OM or-(CO) -R, z = 0
Where B is a hydrogen atom, M is hydrogen or a cation, R is —O—R ′ or —N (R ″) (R ′), and R ′ is
Is an alkyl group, an aralkyl group, an aryl group, a heterocyclic residue or a non-metal atom necessary for forming a heterocyclic ring in cooperation with R ″, and R ″ is a hydrogen atom, a lower alkyl group or R ′.
A non-metallic atom required to form a heterocyclic ring in cooperation with R ₁
And R ₂ is a hydrogen atom or a lower alkyl group, and X is
(CO) -O- or -O- (CO)-, R ₃ is a halogenoalkyl or halogenoalkyloxyalkyl group, and m, p, q, r, x, y and z are each mol% of each monomer. The values are shown, where m is 0 to 60 and p is 0 to 10.
0, q is 0 to 100, r is 0 to 100, x is 0 to 60,
y is 0 to 100, z is 0 to 100, and m + p + q +
r = 100 and x + y + z = 100.

In the above general formula, the vinyl monomer is, for example, styrene, or styrene substituted with a nitro group, a fluorine atom, a chlorine atom, a bromine atom, a chloromethyl group, a lower alkyl group, vinyl methyl ether, vinyl ethyl ether, Unsaturated acids such as vinyl chloroethyl ether, vinyl acetate, vinyl chloroacetate, vinyl propionate, acrylic acid, methacrylic acid or itaconic acid, alkyl esters of acrylic acid or methacrylic acid (wherein the alkyl group has 1 to 5 carbon atoms, An unsubstituted alkyl group, or an alkyl group substituted with a chlorine atom or a phenyl group), a phenyl ester of acrylic acid or methacrylic acid (the phenyl group is an unsubstituted phenyl group or a phenyl group substituted with a chlorine atom, a phenyl group, etc.), Acrylonitrile, vinyl chloride, vinylidene chloride There are ethylene, acrylamide, acrylamide substituted with an alkyl group having 1 to 5 carbon atoms, chlorine, phenyl group, etc., vinyl alcohol, glycidyl acrylate, acrolein, etc., preferably styrene, styrene having a substituent, vinyl acetate, vinyl methyl ether. , Alkyl acrylate, acrylonitrile and the like.

In the above formula, the alkyl group represented by R'is preferably one having 1 to 24 carbon atoms, which may be a linear alkyl group, a branched alkyl group or a cycloalkyl group. It may have a substituent, and as the substituent, a hydroxyl group, a hydroxycarbonyl group, a --COOM '(M' represents a cation) group and the like, particularly a carbon atom substituted with a halogen atom such as a fluorine atom. Number 2-18 halogenoalkyl group or carbon number 2
-18 halogenoalkyloxyalkyl groups give favorable results for the purposes of the present invention. The number of halogen atoms substituted on the halogenoalkyl group and the halogenoalkyloxyalkyl group is preferably 1 to 37.
The halogenoalkyl group and the halogenoalkyloxyalkyl group, and the halogenoalkyl group and the halogenoalkyloxyalkyl group represented by R ₃ in the general formula [2] are preferably represented by the following general formula [A].

[0052]

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In the formula, R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each represent a hydrogen atom or a fluorine atom, n represents an integer of 1 to 12, n ₂ represents 0 or 1. When n ₂ is 0, n ₁ is 0, when n ₂ is 1, n ₁ is 2 or 3, and n ₃ is an integer of 1 to 17. However, n ₁ + n ₃ is 1
~ 17. When there are two or more R ₄ in the general formula [A], they may be different groups such that one is hydrogen and the other is a fluorine atom, and R ₅ , R ₆ and R _{7 are also the same.} When there are a plurality of each in the general formula [A], they may be different groups.

Further, the above general formula [1] and general formula [2]
In the above, when R'is a halogenoalkyl group or a halogenoalkyloxyalkyl group as described above, R in the general formula [1] is preferably -O-R '. Further, an aryl group such as a phenyl group represented by R ′ or an aralkyl group such as a benzyl group may have a substituent, and the substituent includes a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom. Examples thereof include a lower alkyl group substituted with, a hydroxyl group, a hydroxycarbonyl group, a cationic oxycarbonyl group, a nitrile group, and a nitro group.

The heterocycle represented by R'or the heterocycle formed by R'and R "is a saturated or unsaturated heterocycle containing an oxygen atom, a sulfur atom or a nitrogen atom, for example, aziridine or pyrrole. , Pyrrolidine, pyrazole, imidazole, imidazoline, triazole, piperidine, piperazine, oxazine, morpholine, thiazine, etc., and a cation represented by M is, for example, ammonium ion, sodium ion, potassium ion. , Cations such as lithium ions.

In the present invention, the —COOM group-containing polymer compound represented by the above general formula [1] or [2] is used alone or in combination of two or more kinds, preferably an average molecular weight of about 500 to 500, Approximately 000 (weight average) is used.

Typical examples of the above-mentioned polymer compound used in the present invention are as follows. However, the present invention is not limited to these.

[0058]

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[0059]

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[0060]

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[0061]

[Chemical 6]

[0062]

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Represented by the above general formula [1] or [2]-
The COOM group-containing polymer compound can be synthesized by a known method. That is, it is well known that a maleic anhydride copolymer is a very general polymer, and these derivatives are also prepared by reacting a maleic anhydride copolymer with an alcohol or amine compatible with them. Easy to get,
It can also be obtained by reacting an alcohol or amines compatible with a maleic anhydride monomer and purifying it and copolymerizing it with another vinyl monomer. Acrylates such as halogenoalkyl and halogenoalkyloxyalkyl are also available in Journal of Polymer Science (Journal).
of Polymer Science, 15 51
5 to 574 (1955) or British Patent 1,121,
It is easily synthesized by the method for synthesizing the monomer and polymer described in the specification of No. 357.

The amount of the polymer compound represented by the general formula [1] or [2] used is preferably 10 to 1000 mg / m ² , and more preferably 20 to 300 mg / m ^2. preferable.

As another example of the hydrophilic polymer compound according to the present invention, preferably a hydrophilic cellulose derivative (for example,
Methylcellulose, carboxymethylcellulose, hydroxycellulose, etc.), polyvinyl alcohol derivatives (eg, polyvinyl alcohol, vinyl acetate-vinyl alcohol copolymer, polyvinyl acetal, polyvinyl formal, polyvinyl benzal, etc.), natural polymer compounds (eg, gelatin, casein) , Gum arabic etc.), hydrophilic polyester derivatives (eg partially sulfonated polyethylene terephthalate etc.), polyvinyl derivatives (eg poly-N-vinylpyrrolidone,
Polyacrylamide, polyvinylindazole, polyvinylpyrazole, etc.).

The hydrophilic polymer compound according to the present invention may be used alone or in combination of two or more kinds.

The solution of the hydrophilic polymer compound according to the present invention can be applied by a known method such as a gravure coater, a dip coater, a reverse roll coater and an extrusion coater. The amount of the polymer according to the present invention is 10 to 1000.
It is in the range of mg / m ² , and 20 to 300 mg / m ² is preferable in view of particularly stable adhesive force and finish after application. The method of applying the coating liquid and then drying it is not particularly limited, but the residual solvent amount after drying is preferably 5 wt% or less. If the amount of residual solvent is large, air bubbles may be generated at the adhesive interface in the drying process after being laminated with the polarizing film, which is not preferable.

The hydrophilic polymer compound solution may optionally contain an ultraviolet absorber, a slip agent, a matting agent, an antistatic agent, a crosslinking agent,
Also, an activator and the like may be added.

A cross-linking agent is particularly preferable for promoting the adhesion of the polarizing film to the polyvinyl alcohol film. Examples of such a cross-linking agent include polyvalent epoxy compounds, aziridine compounds, isocyanate compounds, bright vanes, boron compounds and the like.

Examples of the adhesive used for bonding the treated surface of the protective film and the polarizing film according to the present invention include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latex such as butyl acrylate and the like. Can be given.

[0071]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. In the text, “parts” means “parts by weight”. Further, the coating compositions in Table 1 are shown by weight ratio.

Example 1 Cellulose triacetate film base having a film thickness of 80 μm (Konica Cat 80UV-2 or less manufactured by Konica Corporation)
The coating composition (below) containing the UV-curable resin shown in Table 1 is coated on one side of the coating (abbreviated as AC) to a coating thickness of 10 μm, dried at 80 ° C. for 5 minutes, and then under a high pressure mercury lamp of 60 W / cm. Cured for 4 seconds from a distance of 10 cm. A cured coating layer was provided as described above to prepare Sample 1. Next, 20 ml of the lower layer liquid (1) and the upper layer liquid (1) of the coating composition for an easy-adhesion layer described below, which consist of a hydrophilic compound on the opposite surface (back surface) of Sample 1, were added to the respective samples shown in Table 1 in this order, 20 ml each. / M
^It was applied at a ratio of 2 and dried at 100 ° C. for 10 minutes to obtain samples 2 and 3 according to the present invention.

(Composition) <Ultraviolet curable resin composition (A)> Dipentaerythritol hexaacrylate monomer 60 parts Dipentaerythritol hexaacrylate dimer 20 parts Dipentaerythritol hexaacrylate trimer Component 20 or more Part Diethoxybenzophenone UV initiator 2 parts Silicone surfactant 1 part <Silica fine particles (A)> Nippon Aerosil Co., Ltd. Aerosil R-972 average particle size 16 nm <Solvent> Methyl ethyl ketone: Ethyl acetate: Isopropyl alcohol = 1 : 1: 1 (weight ratio) (Coating composition for easy adhesion layer) Lower layer liquid (1) Exemplified compound (14) 0.5 g Acetone 60 ml Ethyl acetate 30 ml Toluene 10 ml Upper layer liquid (1) Polyvinyl alcohol 0.5 g (Nippon Gosei) Chemical Industry Co., Ltd. Gohsenol N H-26) Saponin 0.03 g (Surfactant manufactured by Merck Co., Ltd.) Pure water 50 ml Methanol 50 ml Example 2 20 W / m ^{2 on} both sides of a polycarbonate film base having a film thickness of 80 μm (hereinafter abbreviated as “PC” manufactured by Teijin Ltd.) /
After performing corona discharge treatment under the condition of min,
After ultrasonically dispersing the composition containing the ultraviolet-curable resin shown in (1) below, each is applied to a coating film thickness of 10 μm and dried at 80 ° C. for 5 minutes, and then 60 W / cm
It was cured for 4 seconds from a distance of 10 cm under a high pressure mercury lamp.
Sample 4 having a cured coating layer was prepared as described above. Next, the coating composition for an easy-adhesion layer was applied to the opposite surface of the sample 1 in the same manner as in Example 1 to form an easy-adhesion layer, and samples 5 and 6 according to the present invention were obtained.

<Ultraviolet curable resin composition (B)> Dipentaerythritol hexaacrylate monomer 50 parts Dipentaerythritol hexaacrylate dimer 20 parts Dipentaerythritol hexaacrylate trimer or more components 20 parts 1,4 -Butanediol diglycidyl ether 10 parts Diethoxybenzophenone UV initiator 2 parts Aromatic sulfonium salt UV initiator 0.5 part Fluorosurfactant 1 part <Solvent> Methyl ethyl ketone: Ethyl acetate: Isopropyl alcohol = 1: 1: 1 (weight ratio) Comparative Example 1 TAC having a film thickness of 80 μm and a concentration of 8 wt% at a temperature of 60 ° C.
Was dipped in the aqueous sodium hydroxide solution for 5 minutes, washed with water and saponified to obtain Sample 7.

Comparative Example 2 A PC having a thickness of 80 μm was saponified in the same manner as in Comparative Example 1 to obtain Sample 8.

Example 3 An ultraviolet curable resin coating composition shown in Table 3 was ultrasonically dispersed on one side of a TAC having a film thickness of 80 μm and applied so as to have a coating film thickness of 10 μm, and dried at 80 ° C. for 5 minutes. , 60W /
It was cured for 4 seconds from a distance of 10 cm under a high pressure mercury lamp of cm. In the same manner as in Example 1 except that the undercoating liquid (1) for the coating composition for easy-adhesion layer of Example 1 was changed to the undercoating liquid (2) having the following composition on the surface opposite to the TAC provided with the above-mentioned cured coating film. , Samples 9 to 14 according to the present invention were obtained.

<Silica Fine Particles (B)> Fuji Silysia Chemical Ltd. Silysia 431 Average Particle Size 2.5 μm <Silicone Resin Fine Particles (C)> Toshiba Silicone Ltd. Tospar 130 Average Particle Size 3 μm <Solvent> Methyl ethyl ketone: ethyl acetate: isopropyl alcohol = 1: 1: 1 (weight ratio) (Coating composition for easy adhesion layer) Lower layer liquid (2) Exemplified compound (15) 0.5 g Acetone 60 ml Ethyl acetate 30 ml Dimethylformamide 10 ml Comparative Example 3 A sample having a cured coating film was prepared using the ultraviolet curable resin coating composition (below) shown in Table 3 in the same manner as in Example 1, and the sample film was saponified in the same manner as in Comparative Example 1. Then, a sample 15 was obtained.

<Ultraviolet curable resin composition (C)> Polyester acrylate resin 100 parts (Somacoat TP-232 manufactured by Somar Industry Co., Ltd.) Polyisocyanate compound 1 part (Coronate L manufactured by Nippon Polyurethane Co., Ltd.) UV Initiator (Irgacure 184 manufactured by Ciba-Geigy Co., Ltd.) 5 parts Example 4 Polyarylate film having a film thickness of 75 μm (manufactured by Unitika Co., Ltd., trade name: Emblate, hereinafter abbreviated as PAR)
After performing corona discharge treatment on both sides of the same under the condition of 20 W / m ² / min, the coating composition containing the ultraviolet curable resin shown in Table 1 is applied to one side in the same manner as in Example 1 to obtain a cured coating film. Samples 16 were prepared by providing the layers. Then, the opposite surface (back surface) was coated with the coating composition for an easy-adhesion layer in the same manner as in Example 1 to form an easy-adhesion layer, and a sample 17 according to the present invention was obtained.

Example 5 20 W / m ² / m on both sides of a polyethylene terephthalate film having a thickness of 75 μm (manufactured by Dia foil Hoechst Co., Ltd., trade name: Diamond foil hereinafter abbreviated as PET)
After the corona discharge treatment under the condition of in, the coating composition containing the ultraviolet curable resin shown in Table 1 was applied to one surface in the same manner as in Example 2 to form a cured coating film layer, and sample 18 was prepared. did. Then, on the opposite surface (back surface), the present invention was carried out in the same manner as in Example 1 except that the underlayer liquid (1) for coating composition for easy adhesion layer of Example 1 was changed to the underlayer liquid (3) having the following composition. A sample 19 of the above was obtained.

(Coating composition for easy-adhesion layer) Lower layer liquid (3) Exemplified compound (4) 1.0 g Saturated polyester resin (trade name: Byron Tg = 67 ° C. manufactured by Toyobo Co., Ltd.) 0.5 g Acetone 40 ml Ethyl acetate 50 ml Dimethylformamide 10 ml Example 6 Syndiotactic polystyrene (SPS) pellets were prepared according to JP-A-3-131843. The SPS pellets were melt extruded at 330 ° C. with an extruder. This molten polymer was extruded through a pipe into an extrusion die and extruded while being electrostatically applied to a cooled casting drum through a die slit to cool the sheet, thereby obtaining an SPS unstretched sheet having a thickness of 1000 μm. The produced sheet was preheated at 115 ° C. and then stretched 3.3 times in the machine direction. It was preheated to 100 ° C. in a tenter and then stretched 3 times in the transverse direction at 130 ° C. Further, while slightly relaxing in the lateral direction, heat setting was performed at 225 ° C. to obtain a 100 μm SPS film.

Next, 20 W / m ^{2 is applied to} both sides of the SPS film.
After performing a corona discharge treatment under the condition of / min, a coating composition containing an ultraviolet curable resin was applied to one surface in the same manner as in Example 2 to form a cured coating film layer, and Sample 20 was prepared. Next, the present invention was carried out in the same manner as in Example 1 except that the lower layer liquid (1) of the coating composition for an easily adhesive layer of Example 1 was changed to the lower layer liquid (4) of the following composition on the opposite surface (back surface). Sample 21 related to
I got

(Coating composition for easy adhesion layer) Lower layer liquid (4) Exemplified compound (14) 0.7 g Polystyrene resin (trade name: Toborex XGPPS550-51, manufactured by Mitsui Toatsu Chemicals, Inc.) 0.3 g Acetone 40 ml Ethyl acetate 50 ml Toluene 10 ml Example 7 A coating containing a UV curable resin on a norbornene-based resin film having a film thickness of 100 μm (trade name of Arton film manufactured by Nippon Synthetic Rubber Co., Ltd., abbreviated as “NRB film” hereinafter) in the same manner as in Example 2. Sample 25 by applying the composition to form a cured coating layer
Was prepared. Then, the opposite surface (back surface) was coated with the coating composition for easy adhesion in the same manner as in Example 2 to form an easy adhesion layer,
A sample 26 according to the present invention was obtained.

Comparative Example 4 A PAR film having a thickness of 75 μm was saponified in the same manner as in Comparative Example 1 to obtain Sample 22.

Comparative Example 5 A PET film having a thickness of 75 μm was saponified in the same manner as in Comparative Example 1 to obtain Sample 23.

Comparative Example 6 The SPS film having a thickness of 100 μm produced in Example 6 was saponified in the same manner as in Comparative Example 1 to obtain Sample 24.

Comparative Example 7 The NRB film produced in Example 7 was saponified in the same manner as in Comparative Example 1 to obtain Sample 27.

Comparative Example 8 A TAC film provided with a cured coating film was saponified in the same manner as in Example 1 by using the ultraviolet curable resin coating composition (below) shown in Table 1 in the same manner as in Example 1. Then, a sample 28 was obtained.

<Ultraviolet curable resin composition (D)> 100 parts by weight of acrylic urethane resin (manufactured by Dainippon Ink and Co., Ltd., trade name: Unidick 17-806) Polyisocyanate compound (manufactured by Nippon Urethane Co., Ltd.) Product name: Coronate L) 1 part by weight UV initiator (manufactured by Ciba-Geigy Co., Ltd., product name: Irgacure 184) 5 parts by weight Next, the polarized light obtained as Examples 1 to 7 and Comparative Examples 1 to 8 above. The protective film for a plate was evaluated by the following method. Tables 1 to 4 show the results of the characteristic evaluation as a single protective film for polarizing plate.
Further, Table 5 shows the results of evaluation of characteristics of the polarizing plate laminated with the polarizing film.

[Evaluation Method] Hereinafter, the measurement according to the present invention,
The evaluation method will be described.

<Characteristic evaluation of the protective film for polarizing plate alone> 1. Scratch resistance of cured coating layer 1) Pencil hardness: JISK5400 is applied correspondingly, load 100
2) Steel wool hardness: Steel wool (# 000
0), a friction of 5 reciprocations is applied with a load of 1 kg (1 reciprocation / s
ec) (Judgment Criteria) O ... No scratches on the surface B: 1 to 10 scratches X ... 11 to 30 scratches XX ... 31 or more scratches

2. Antiglare haze: JISK7105 was applied correspondingly, and a measuring instrument T-2600DA manufactured by Tokyo Denshoku Industries Co., Ltd. was used.

Glossiness: JISK7105 is applied mutatis mutandis, measuring instrument Digital Density Angle Photometer VG-1 manufactured by Tokyo Denshoku Industries Co., Ltd.
Type 0 was used (60 ° gloss).

3. Adhesion between cured coating layer and support (1) Adhesion test of cured coating layer A single-edged razor blade was applied to the surface of the cured coating layer against the surface 9
A cut is made at an angle of 0 ° with a width of 30 mm and a depth that reaches a surface of a transparent plastic film slightly, and a commercially available 25 mm wide cellophane tape is attached across the cut portion, leaving one end of the tape, and there is a curved surface. Rubbing it well with plastic or metal to adhere it well, holding one end of the unattached tape by hand and pulling it horizontally as strongly as possible, peeling off the cured film layer for the attached tape area from the score line. The area ratio was evaluated as follows.

A: Not peeled at all B: Peeled area ratio was less than 10% C: Peeled area ratio was less than 10 to 30% D: Peeled area ratio was 30% That was all.

(2) Adhesion test of cured film layer after high-temperature and high-humidity treatment The protective film for polarizing plate was treated in an oven set at 80 ° C. and 95% RH for 500 hours, and then 23
The sample was left to cool in a room at 55 ° C. and 55% RH, and after 24 hours, the ratio of the peeled area was evaluated in the same manner as in (1) above.

4. Flexibility Apply JISK5400, and bend it by 180 ° so that the surface of the cured coating is outside of the mandrel with a diameter of 2 mm. The bent portion is visually cracked and peeled off (cracked state).
Was examined.

(Judgment Criteria) ∘ No cracks were generated Δ ・ ・ ・ Cracks were generated × ・ ・ ・ Cracks were generated with a crisp sound during bending.

5. Blocking property measurement and evaluation method A sample (width 35 mm, length 950 mm) is wound around a core having a diameter of 50 mm for 6 turns with a load of 1 kg, and both ends of the sample are covered with double-sided tape (width 30 mm, length 5 mm to prevent the sample from loosening). ) And stick.

The core is taken out and left in an atmosphere of 23 ° C. and 55% RH for 24 hours, then the sample is placed on an electronic balance and pushed for 10 minutes for 1 minute, and the stress at that time is measured.

Then, the sample is unwound and wound one turn, and the stress is measured in the same manner.

The blocking force of the sample is calculated by subtracting 6 times the stress of one winding from the stress of six windings.

Samples 1 to 3 of the present invention were compared with Comparative Sample 7, and Samples 4 and 6 of the present invention were compared with Comparative Sample 8.
The samples 16 and 17 of the present invention are compared with the comparative sample 22.
The samples 18 and 19 of the present invention were compared with the comparative sample 23.
The samples 20 and 21 of the present invention were compared with the comparative sample 24.
The samples 25 and 26 of the present invention were evaluated for blocking property against the comparative sample 27.

6. Chemical resistance of cured coating layer Gauze was dipped in each solvent shown in Table 1, the surface of the cured coating was wiped 10 times with the gauze, and after drying at room temperature, the state of the coating surface was observed (criteria). ○: No change △: Slightly whitened ×: The surface of the coating film was whitened and practically unusable.

<Characteristics Evaluation as Polarizing Plate> How to Make Polarizing Film A 120 μm thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part of iodine, 2 parts of potassium iodide and 4 parts of boric acid, and stretched 4 times at 50 ° C. Then, a polarizing film which is a uniaxially stretched polyvinyl alcohol dyed film was obtained.

How to make a polarizing plate A polarizing plate was made by laminating the polarizing film and the protective film samples 1-28 in the following steps.

A protective film sample of 18 cm × 5 cm is placed on a glass plate with the coated surface of the easy-adhesion layer facing up. A polarizing film made of a uniaxially stretched polyvinyl alcohol dye film of the same size as the protective film sample was used to obtain a solid content of 2 wt. Dip both sides of the polarizing film in a polyvinyl alcohol adhesive tank for 1 to 2 seconds, gently remove excess adhesive adhering to the polarizing film, place it on the protective film sample, and add the same as above. Laminate and arrange the following protective film sample so that the easy-adhesion surface of the sample film and the adhesive are in contact. Excess adhesive and the adhesive from the end of the laminate of the polarizing film and the protective film laminated by the above with a hand roller. Remove air bubbles and attach. Hand roller pressure is about 2
The sample obtained in 80 ° C. dryer having a roller speed of about ³ kg / cm ² and a roller speed of about 2 m / min is left for 5 minutes.

Regarding the polarizing plate prepared in this way,
The adhesiveness between the polarizing film and the protective film was evaluated as follows.

1. Initial Adhesion After laminating the polarizing film and the protective film, the peelability was measured by hand, and the degree of occurrence of material destruction was evaluated according to the following three grades.

(Judgment Criteria) ○: Material destruction occurs Δ: Partial material destruction occurs, but the peeling area between the sample film and the polarizing film is large ×: Between the sample film and the polyvinyl alcohol film It comes off.

[0110] 2. Workability A dumbbell cutting machine was used to determine the degree of floating of the punched adhesive surface.

(Judgment Criteria) O: Less than 0.10 mm B: 0.10 to less than 0.15 mm X: 0.15 mm or more 3. Durability A polarizing plate was prepared by the following method using the protective film obtained in each Example and Comparative Example, and each polarizing plate was 5 cm × 7.
It was cut to a size of cm. 6 cm for each of the obtained cut pieces
Each piece was attached to the glass plate by temporarily adhering it to the central part of a glass plate of 8 cm by an acrylic adhesive and then pressing them to completely remove air bubbles between each piece and the glass plate.

The test piece thus produced was tested at 80 ° C. and 95%.
After vertically arranging them in a constant temperature and humidity oven set to RH so that they do not overlap each other and fixing them on a support frame for 1000 hours, (A) Discoloration of polarizing plate, (B) Adhesion of polarizing film and protective film for each piece. The sex was measured.

(A) Evaluation of Discoloration of Polarizing Plate: Value of color difference change ΔE (NBS unit) measured with a color difference meter (manufactured by Suga Test Instruments Co., Ltd.)
Was evaluated.

◯: Less than 2 Δ: Less than 2 to 5 ×: 5 or more (B) Evaluation of adhesiveness between the polarizing film and the protective film: After the treatment at high temperature and high humidity, the film was visually observed to form a polarizing film. The peeled state between the protective films was evaluated.

○: The raised portion of the film is 1 m from the periphery
Less than m △: The raised portion of the film is in the range of 1 to less than 5 around the periphery × ... The raised portion of the film is 5 mm or more in the periphery

[0116]

[Table 1]

[0117]

[Table 2]

[0118]

[Table 3]

[0119]

[Table 4]

[0120]

[Table 5]

As is clear from the results of Tables 1 to 5, the protective film for a polarizing plate of the present invention is excellent in scratch resistance, antiglare property and chemical resistance even as the protective film itself, and further, in the easily adhesive layer. It is confirmed that, even when assembled on a polarizing plate, the protective film for polarizing plate has excellent adhesiveness (difficulty to peel off) with the polarizing film and durability even when assembled into a polarizing plate. Was done.

[0122]

According to the present invention, (1) a protective film for a polarizing plate having excellent scratch resistance and chemical resistance, (2) a protective film for a polarizing plate having excellent adhesion between the protective film and the polarizing film, (3) A protective film for a polarizing plate having excellent flexibility,
(4) Protective film for polarizing plate with anti-glare effect (5) Excellent adhesion to polarizing film and UV absorption ability deteriorates even when exposed to severe conditions under high temperature and high humidity for a long time It is possible to provide a protective film for a polarizing plate which is neither colored nor colored.

[Brief description of the drawings]

FIG. 1 is a sectional view of a layer structure for explaining a layer structure of the present invention.

[Explanation of symbols]

 1 Transparent resin film (support) 2 Cured coating layer 3 Easy adhesion layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C09D 133/08 PGB C09D 133/08 PGB PGC PGC C09J 7/02 JHR C09J 7/02 JHR JJA JJA JJN JJN JLF JLF G02B 1/10 G02B 1/10 Z (72) Inventor, Hitoshi Nara, Tokyo, Hino City, Tokyo 1 Konica Stock Company, in-house (72) Inventor, Naoko Morita 1, Tokyo City, Hino City, Konica Stock Company, Konica Stock Company

Claims (5)

[Claims] 1. A protective film for a polarizing plate, which comprises a transparent resin film and a cured coating film layer formed of a composition containing an ultraviolet curable polyol acrylate resin on at least one surface of the transparent resin film. 2. The protective film for a polarizing plate according to claim 1, wherein the UV-curable polyol acrylate resin is dipentaerythritol hexaacrylate. 3. The protective film for a polarizing plate according to claim 1, wherein an easy-adhesion layer containing a hydrophilic polymer compound is provided on the opposite surface of the transparent resin film to the side of the cured coating film. the film. 4. The protective film for a polarizing plate according to claim 1, 2 or 3, wherein the cured coating film layer contains inorganic fine particles or organic fine particles. 5. The protective film for a polarizing plate according to claim 1, wherein the composition containing the ultraviolet curable polyol acrylate resin contains an ultraviolet absorber or an antioxidant. .