KR20040090456A - Polarizing plates and processes for preparing them - Google Patents

Abstract

PURPOSE: A polarizing plate having stacked protective layers and a fabricating method thereof are provided to improve an adhesive characteristic of a protective film by using a mixture of a urethane adhesive and a polyvinyl resin of a particular composition as an adhesive. CONSTITUTION: A polarizing plate is formed by stacking a protective film on one side or both sides of polyvinyl-alcohol polarizing film by using an adhesive layer. The protective film is formed with a cycloolefin resin. The adhesive layer includes an urethane adhesive and a polyvinyl resin. The polyvinyl-alcohol resin is formed with acetic acid vinyl and unsaponifiable matter as a copolymer thereof.

Description

Polarizer and its manufacturing method {POLARIZING PLATES AND PROCESSES FOR PREPARING THEM}

This invention relates to the polarizing plate which laminated | stacked the protective film on the at least single side | surface of a polarizing film, and its manufacturing method.

As a polarizing film, what adsorbed the dichroic dye to the polyvinyl alcohol-type resin film conventionally is used. And the iodine type polarizing film which uses iodine as a dichroic dye, and the dye type polarizing film which uses a dichroic dye as a dichroic dye are known. These polarizing films are usually at least one side thereof, preferably a protective film such as triacetyl cellulose is bonded to both sides via an adhesive made of an aqueous solution of polyvinyl alcohol-based resin to form a polarizing plate. However, the polarizing plate of such a structure has the problem that polarization performance falls easily when it uses for a long time under wet heat, and that the cross section of a protective film and a polarizing film is easy to peel off.

It is proposed to use thermoplastic cycloolefin resin as a protective film of a polarizing plate about such a problem. For example, Japanese Laid-Open Patent Publication No. 5-212828 (Patent Document 1) laminates a thermoplastic saturated norbornene-based resin sheet on at least one side of a polyvinyl alcohol-based sheet with an acrylic adhesive, and heat-presses the same to form a polarizing plate. It is described. In Japanese Unexamined Patent Application Publication No. 2000-321430 (Patent Document 2), at least one side of a polyvinyl alcohol-based polarizing film is used as a cyclic olefin resin through an adhesive layer which is a mixture of a polyvinyl alcohol adhesive and a two-component type adhesive. The polarizing plate which laminated | stacked the protective film which consists of is described. Moreover, Unexamined-Japanese-Patent No. 2000-321432 (patent document 3) describes the polarizing plate with which the protective film which consists of a polyvinyl alcohol-type polarizing film and thermoplastic saturated norbornene-type resin is adhere | attached with a polyurethane-type adhesive agent.

However, in adhesives (also called pressure-sensitive adhesives) such as acrylics, the thickness of itself is inevitably thickened to 10 to 50 µm. In the case where a polyvinyl alcohol-based polarizing film and a cycloolefin resin film are adhered using a generally known polyvinyl alcohol-based, urethane-based, acryl-based, or vinyl acetate-based adhesive, adhesiveness is sufficiently sufficient by a combination of double-sided films. I could not say.

On the other hand, mainly intended to make a conventional triacetyl cellulose etc. as a protective film, various proposals are made also about the adhesion | attachment with it and a polyvinyl alcohol-type polarizing film. For example, Japanese Patent Laid-Open No. 8-101307 (Patent Document 4) describes a polarizing plate in which a polyvinyl alcohol-based polarizing film and a support (protective film) are laminated with an adhesive consisting of polyester polyol and aliphatic polyisocyanate. have. In addition, JP-A-9-258023 (Patent Document 5) describes a polarizing plate in which a protective film is bonded through a polyvinyl alcohol-based adhesive containing a water-soluble epoxy compound on at least one side of the polyvinyl alcohol-based polarizing film.

[Patent Document 1] Japanese Patent Application Laid-Open No. 5-212828

[Patent Document 2] Japanese Unexamined Patent Publication No. 2000-321430

[Patent Document 3] Japanese Unexamined Patent Publication No. 2000-321432

[Patent Document 4] Japanese Patent Application Laid-Open No. 8-101307

[Patent Document 5] Japanese Patent Application Laid-Open No. 9-258023

An object of the present invention is to increase the adhesion between them by using a suitable adhesive in laminating a protective film made of cycloolefin resin to a polyvinyl alcohol polarizing film to form a polarizing plate.

The present inventors earnestly studied for this purpose, and as a result of laminating a protective film made of cycloolefin resin to a polyvinyl alcohol polarizing film, a mixture of a urethane adhesive and a polyvinyl alcohol resin having a specific composition is used as an adhesive. By using it, it discovered that the polarizing plate excellent in the adhesiveness of a polarizing film and a protective film was obtained, and reached this invention.

That is, according to this invention, the polarizing plate which laminates the protective film which consists of cycloolefin resin through the adhesive bond layer on the single side | surface or both surfaces of a polyvinyl alcohol-type polarizing film, An adhesive bond layer contains a urethane type adhesive agent and polyvinyl alcohol-type resin This polyvinyl alcohol-based resin is provided with a polarizing plate which is a saponified product of a copolymer of vinyl acetate and other monomers copolymerizable therewith.

This polarizing plate is laminated | stacked the protective film which consists of cycloolefin resin through the adhesive bond layer on the single side | surface or both surfaces of a polyvinyl alcohol-type polarizing film, Comprising: With an urethane type adhesive agent and vinyl acetate as an adhesive agent and the other monomer copolymerizable with this A mixture of an aqueous solution of a polyvinyl alcohol-based resin, which is a saponified copolymer, and an aqueous solution of a urethane-based adhesive and a polyvinyl alcohol-based resin are applied to the surface of a polarizing film or a protective film within 5 minutes after mixing to laminate both. It is advantageously produced by the method of carrying out the process.

Effects of the Invention

According to this invention, the polarizing plate excellent in the adhesiveness of the protective film which consists of a polyvinyl alcohol-type polarizing film and cycloolefin resin can be manufactured compared with the case where a conventional adhesive agent is used.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described in detail. A polarizing film consists of polyvinyl alcohol-type resin, For example, the dye-based polarizing film which adsorbed and oriented a dichroic dye to the iodine type polarizing film which adsorbed the iodine to the polyvinyl alcohol-type resin film, and the polyvinyl alcohol-type resin film And polyene polarizing films obtained by partially dehydrating these films. Polyvinyl alcohol-type resin is obtained by saponifying a polyvinyl acetate type resin normally. As polyvinyl acetate type resin, besides polyvinyl acetate which is a homopolymer of vinyl acetate, the copolymer of vinyl acetate and the other monomer copolymerizable with this, for example, a poly (ethylene-vinyl acetate) copolymer, etc. are mentioned. These polyvinyl alcohol-based resins may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may also be used.

An iodine type polarizing film or a dye type polarizing film adsorbs and orients an iodine or a dichroic dye by performing uniaxial stretching and dyeing with iodine or a dichroic dye to the raw film which consists of these polyvinyl alcohol-type resins. The thickness of a polyvinyl alcohol polarizing film is about 5-50 micrometers, for example.

In this invention, the protective film which consists of cycloolefin resin is laminated | stacked on one side or both sides of such a polyvinyl alcohol-type polarizing film, and it is set as a polarizing plate. Cycloolefin resin is thermoplastic resin which has a unit of the monomer which consists of cyclic olefins (cycloolefin), such as a norbornene and a polycyclic norbornene-type monomer, for example. The cycloolefin resin may be a copolymer of a cycloolefin, an aromatic compound having a chain olefin, or a vinyl group. It is also effective to introduce a polar group.

In the case of using a copolymer of a cycloolefin with a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group include styrene, α-methyl styrene, and nuclear alkyl substitution. Styrene and the like. In such a copolymer, the unit of the monomer which consists of cycloolefin may be 50 mol% or less, for example, about 15-50 mol% may be sufficient. In particular, in the case of using a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, the unit of the monomer consisting of the cycloolefin may be a relatively small amount. In such a terpolymer, the unit of the monomer which consists of linear olefins is about 5 to 80 mol% normally, and the unit of the monomer which consists of an aromatic compound which has a vinyl group is about 5 to 80 mol% normally.

Commercially available thermoplastic cycloolefin resins include, for example, "Topas" sold by Ticona of Germany, "Aton" sold by JSR, and "ZEONOR" sold by Nippon Xeon, Inc. "ZEONEX" and "Apel" sold by Mitsui Chemicals. Such a cycloolefin-based resin can be formed into a film, but a known method such as a solvent cast method or a melt extrusion method can be suitably used for the film formation. The cycloolefin resin film formed into a film is also marketed, For example, "S thinner", "SCA40", etc. which are sold from Sekisui Chemical Co., Ltd. are mentioned.

Although it is preferable that the thickness of a protective film is thin, when too thin, intensity | strength will fall and workability will fall, while too thick, problems, such as transparency fall or the curing time required after lamination, will arise. Therefore, the suitable thickness of a protective film is about 5-200 micrometers, for example, Preferably it is 10-150 micrometers, More preferably, it is 20-100 micrometers.

The protective film which consists of such cycloolefin resin may be joined by the single side | surface of a polarizing film, and may be bonded by both surfaces. When bonding the protective film which consists of cycloolefin resin to both surfaces of a polarizing film, two protective films may be the same kind, and may be another kind. When bonding the protective film which consists of cycloolefin resin to the single side | surface of a polarizing film, the protective film which consists of resins other than cycloolefin resin can be bonded to the opposite surface. As a protective film which consists of resins other than cycloolefin resin, For example, the film which consists of acetyl cellulose resins, such as a triacetyl cellulose and a diacetyl cellulose, polyester, such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate The film which is excellent in optical transparency, such as the film which consists of system resin, and the film which consists of polycarbonate resin, is mentioned.

The protective film which consists of a polarizing film and cycloolefin resin is laminated | stacked using the mixed adhesive agent of a urethane type adhesive agent and polyvinyl alcohol-type resin. When laminating | stacking the protective film which consists of cycloolefin resin on both surfaces of a polarizing film, such a mixed adhesive agent is adhere | attached on both surfaces of a polarizing film, and the protective film which consists of cycloolefin resin is adhere | attached. On the other hand, when laminating | stacking the protective film which consists of cycloolefin resin on one side of a polarizing film, and laminating | stacking the protective film which consists of another resin on the other surface, the same adhesive agent may be applied to both surfaces of a polarizing film, and a polarizing film The said mixed adhesive agent is applied for adhesion | attachment of the protective film which consists of a cycloolefin resin, and another adhesive agent can also be applied for adhesion | attachment of the protective film which consists of resin other than a polarizing film and cycloolefin resin. For example, when laminating | stacking the protective film which consists of acetyl cellulose resin on one surface of a polarizing film, the adhesive agent which consists of polyvinyl alcohol-type resin can also be used for both adhesion.

The urethane-based adhesive includes a one-component type composed of a prepolymer having a terminal isocyanate group and a two-component type composed of a functional group reacting with an isocyanate group, particularly a hydroxyl group, and a two-component type composed of a curing agent having an isocyanate group, but can be used in the present invention. In one-part type, terminal isocyanate group reacts with surrounding moisture, for example, moisture in a polarizing film, or moisture in air, or reacts with the active hydrogen group of a film surface, and expresses adhesiveness.

Examples of the main ingredient having a hydroxyl group constituting one of the two-component urethane adhesives include polyether polyols, polyester polyols, acrylic polyols, ethylene-vinyl acetate polyols, and polyamide polyols. The polyether polyol is, for example, polyethylene glycol, polypropylene glycol, ethylene oxide / propylene oxide copolymer, or the like. Polyester polyols are, for example, polycondensates of dibasic acids and diols. An acrylic polyol is a (meth) acrylic acid ester which has a hydroxyl group, such as (meth) acrylic acid hydroxyethyl, (meth) acrylic acid hydroxypropyl, and (meth) acrylic acid hydroxybutyl, and (meth) acrylic acid or its alkyl ester, for example. Copolymer. The ethylene-vinyl acetate-based polyol is a partially saponified product of an ethylene-vinyl acetate copolymer or a copolymer of three or more members in which another monomer copolymerizable therewith is copolymerized. Examples of the third monomer used in this case include unsaturated carboxylic acids and The salt, acrylic esters, linear olefins other than ethylene, vinyl ethers, unsaturated nitriles, vinyl halides, allyl compounds, vinyl silyl compounds, aromatic compounds having a vinyl group, and the like can be mentioned. The polyamide-based polyol is an amide bond formed by, for example, using diamines such as ethylenediamine, propylenediamine, and hexamethylenediamine as raw materials when producing the polyester polyol.

The urethane-based adhesives include organic solvents in which polyols are dissolved in organic solvents and water-based solutions in which polyols are dissolved in water. However, in the present invention, the urethane adhesive is mixed with an aqueous solution of polyvinyl alcohol resin. Is preferably used. Commercially available products that are the subject of two-component urethane adhesives include, for example, "EL-436A" sold by Toyo Morton Co., Ltd. as a polyester polyol, and "EA-W151A" sold by Toyo Moton Co., Ltd. as an acrylic polyol. have.

The curing agent constituting the other one of the two-component urethane-based adhesive is a compound having an isocyanate group at the molecular end, for example, polyisocyanate monomers such as tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diocyanate and isophorone diisocyanate. In addition, the adduct body which these multiple molecules added to polyhydric alcohols, such as a trimethylol propane, and the trifunctional isocyanurate body in which 3 molecules of diisocyanate formed the isocyanurate ring in the part of each single terminal isocyanate group And polyisocyanate-modified products such as biuret bodies in which three molecules of diisocyanate are formed by hydration and decarbonation at a portion of each single-ended isocyanate group.

It is preferable that the hardening | curing agent of a two-component urethane type adhesive agent can be disperse | distributed to water and used. As a commercial item which is a hardening | curing agent of a two-component urethane type adhesive agent, "EL-436B" and "EA-W151B" etc. which are all sold from Toyo Morton Co., Ltd. are mentioned, for example.

Polyvinyl alcohol-based resin mixed with the urethane-based adhesive is used in the form of an aqueous solution. In addition to the vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl alcohol-type resin used as an adhesive agent is obtained by saponifying the copolymer of vinyl acetate and the other monomer copolymerizable with this. Acetacetyl-modified polyvinyl obtained by reacting diketene by a known method with a modified polyvinyl alcohol-based polymer partially modified with these hydroxyl groups, for example, a homopolymer of vinyl acetate or a saponified copolymer Alcohol and the like. In this invention, the vinyl alcohol type copolymer which is a saponified substance of the copolymer of vinyl acetate and the other monomer copolymerizable to this among the polyvinyl alcohol type adhesive agents is used. When vinyl alcohol homopolymer is used, sufficient adhesive force between a polyvinyl alcohol polarizing film and cycloolefin resin is hard to be obtained.

In the copolymer of vinyl acetate and other monomers, vinyl acetate is mainly used, and the copolymerization ratio of both is about 70 to 99.9 mol% of vinyl acetate and about 0.1 to 30 mol% of other monomers. Other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids and salts thereof, acrylic esters, chain olefins, vinyl ethers, unsaturated nitriles, vinyl halides, allyl compounds, vinyl silyl compounds, aromatic compounds having vinyl groups, and the like. However, among these, those copolymerized with unsaturated carboxylic acids or salts thereof are preferable. Therefore, as polyvinyl alcohol-type resin which comprises the adhesive agent in this invention, the saponified material of the copolymer of vinyl acetate and the monomer which has a carboxyl group, ie, carboxyl group-modified polyvinyl alcohol, is used preferably. In addition, the "carboxyl group" used in this specification is a concept containing -COOH and its salt.

Commercially available carboxyl group-modified polyvinyl alcohols include, for example, "Gurerefobal KL506", "Gurerefobal KL318" and "Gurerefobal KL118" sold by Kuraray Co., Ltd., respectively. "Gosenal T-330" and "Gosenal T-350" sold from Japan, "DR-0415" sold by Denki Chemical Industries, Ltd., JAPAN VAM & POVAL CO., LTD. "AF-17", "AT-17", "AP-17", etc. which are sold from the above can be mentioned.

The molecular weight of polyvinyl alcohol-type resin is about 10,000-1 million normally, Preferably it is 20,000-400,000, More preferably, it is 40,000-120,000. In dissolving such a polyvinyl alcohol-based resin in water to form an adhesive, the concentration of the polyvinyl alcohol-based resin is not particularly limited, but is, for example, (0.1 to 10) / in a weight ratio of polyvinyl alcohol-based resin / water. It is about 100, Preferably it is (1-5) / 100.

The water-soluble epoxy compound, glyoxazole, glutaraldehyde, zinc chloride, a melamine type compound, etc. can also be mixed with the adhesive agent which is a mixture of a urethane type adhesive agent and polyvinyl alcohol-type resin. These components are normally mixed with the aqueous solution of polyvinyl alcohol-type resin. In order to improve the adhesiveness of a protective film and a polarizing film especially, it is preferable to mix | blend a water-soluble epoxy compound.

As a water-soluble epoxy compound, the polyamide obtained by making epichlorohydrin react with the polyamide polyamine obtained by reaction of the polyalkylene polyamine like diethylene triamine and triethylene tetramine, and the dicarboxylic acid like adipic acid, for example Epoxy resin etc. are mentioned. As a commercial item of such a polyamide epoxy resin, "Sumirez resin 650" and "Sumirez resin 675" sold by Sumitomo Chemical Industries, Ltd., "WS-525" sold by Nippon PMC Corporation, for example. "And so on.

When mix | blending a water-soluble epoxy compound with polyvinyl alcohol-type resin aqueous solution, the ratio of water-soluble epoxy compound / polyvinyl alcohol-type resin is about (5-100) / 100 normally in solid content weight ratio, Preferably it is (5-50) / 100. to be. When the amount of the water-soluble epoxy compound is less than this range, the effect of preventing the peeling of the protective film is less, and when too large, the adhesive layer tends to be weak. In addition to the water-soluble epoxy compound, zinc chloride, tin chloride, zinc fluoride, tertiary amine, quaternary ammonium salt, imidazole compound and the like may be added to the aqueous polyvinyl alcohol-based resin solution.

In the present invention, a mixture of a urethane-based adhesive and a polyvinyl alcohol-based resin is used as the adhesive, but the ratio of both is about 1 to 500 parts by weight of the polyvinyl alcohol-based resin as a solid content relative to 100 parts by weight of the solid content of the urethane-based adhesive. It is preferable to use. Solid content of polyvinyl alcohol-type resin with respect to 100 weight part of solid content of a urethane type adhesive agent becomes like this. More preferably, it is 5-200 weight part, More preferably, it is 10-100 weight part, The functional group of the main body and hardening | curing agent in a urethane type adhesive agent What is necessary is just to decide suitably according to the ratio of.

As means for improving the adhesion between the adhesive and the polarizing film and / or the protective film, the polarizing film and / or the protective film may be subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation, primer coating treatment, saponification treatment, or the like. You can also carry out.

The method of bonding a polyvinyl alcohol-type polarizing film and a protective film is not specifically limited, For example, an adhesive is apply | coated uniformly to the surface of a polyvinyl alcohol-type polarizing film or a protective film, and the other film is rolled up on an application surface The method of joining and drying by etc. are mentioned.

A urethane adhesive and a polyvinyl alcohol-based resin aqueous solution are mixed to prepare an adhesive, and a polarizing film and a protective film are laminated using the adhesive. The mixture of the urethane-based adhesive and a polyvinyl alcohol-based resin aqueous solution is used to form a polarizing film and a protective film. It is preferable that the time until lamination | stacking applied in between is made into 5 minutes or less. If the time from lamination to mixing becomes long, precipitation or separation may occur in the mixed adhesive, which may cause problems such as deterioration of adhesiveness and deterioration of appearance. The time from mixing to lamination is more preferably within 3 minutes, even more preferably within 1 minute.

Usually, after preparing a mixed adhesive, it is apply | coated under the temperature of 15-40 degreeC, and joining temperature is the range of about 15-30 degreeC normally. After bonding, the drying treatment is carried out to remove a solvent such as water contained in the adhesive. The drying temperature at this time is usually in the range of 30 to 85 ° C, preferably 40 to 80 ° C. Thereafter, in an environment of 15 to 85 ° C, preferably 20 to 50 ° C, more preferably 35 to 45 ° C, curing is usually performed for about 0.1 to 100 days to cure the adhesive. Since the productivity worsens when this curing period is long, the curing period is preferably about 0.5 to 30 days, and more preferably 1 to 7 days.

In this way, the polarizing plate by which the protective film which consists of cycloolefin resin was bonded to the single side | surface or both surfaces of a polyvinyl alcohol-type polarizing film through the adhesive bond layer containing a urethane type adhesive agent and polyvinyl alcohol-type resin is obtained.

In the present invention, a protective film, in particular a protective film made of cycloolefin resin, functions as a retardation film, a function as a brightness enhancement film, a function as a reflective film, a function as a semi-transmissive film, a function as a diffusion film, a function as an optical compensation film And optical functions. In this case, for example, such a function can be provided by laminating an optical functional film such as a retardation film, a brightness enhancement film, a reflective film, a semi-transmissive reflective film, a diffusion film, an optical compensation film on the surface of the protective film. In addition, such a function can also be provided to the protective film itself. For example, the function as a retardation film can be provided by giving an extending | stretching process to the said protective film. Two or more layers of cholesteric liquid crystals having different center wavelengths of selective reflection by forming fine pores in the protective film in the same manner as described in JP-A-2002-169025 and JP-A-2003-29030. By superimposing a layer, the function as a brightness improving film can be provided. By forming a metal thin film on the said protective film by vapor deposition, sputtering, etc., the function as a reflective film or a semi-transmissive reflective film can be provided. By coating the resin solution containing microparticles | fine-particles on the said protective film, the function as a diffusion film can be provided. Furthermore, by coating and aligning a liquid crystal compound on the protective film, a function as an optical compensation film can be imparted.

EXAMPLE

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited to these examples. In the examples,% and parts indicating content to amount of use are based on weight unless otherwise specified.

Example 1

(a) Preparation of Polarizing Film

The polyvinyl alcohol film (polymerization degree 2,400, saponification degree 99.9 mol% or more) was uniaxially stretched by 5 times the draw ratio by dryness, and immersed in pure water at 60 ° C. for 60 seconds while maintaining the tension state. Next, iodine / potassium iodide / water was dyed by immersion for 60 seconds in an aqueous solution of 0.05 / 5/100 by weight ratio. Potassium iodide / boric acid / water was then immersed in an aqueous solution of 6 / 7.5 / 100 by weight ratio at 73 ° C. for 300 seconds. After wash | cleaning for 10 second with the pure water of 15 degreeC again, it dried at 50 degreeC and obtained the iodine type polarizing film.

(b) Preparation of adhesive

100 parts of "EL-436A" made by TOYOMOTON Co., Ltd. which is the main polyester polyol prepolymer as a urethane-based adhesive (an aqueous solution of 35% solid content concentration), is made of "EL-436B" made by TOYOMOTON Co., Ltd. which is an isocyanate-based curing agent 30 parts (which is 100% of active ingredient) were mix | blended, and water was added again, and it diluted so that solid content concentration might be 20%. On the other hand, as a polyvinyl alcohol-based adhesive, a carboxyl group-modified polyvinyl alcohol "Gurarefoval KL318" of Kuraray Co., Ltd. (a saponification of the copolymer of the molar ratio of vinyl acetate and sodium itacate about 98: 2, saponification degree 85-) 90 mol%, the molecular weight about 85,000) 3% aqueous solution was prepared. The obtained urethane type adhesive agent and polyvinyl alcohol-type aqueous solution were mixed by the weight ratio 1: 1 (20: 3 by solid content weight ratio), and it was set as the mixed adhesive agent.

(c) protective film

The film of 40 micrometers in thickness which formed into the film by the cycloolefin resin "ZEONOR" by Nippon Zeon Co., Ltd. was made into the 1st protective film. Moreover, "Fujitack UV80" which is a triacetyl cellulose film of thickness 80 micrometers made by Fujishashin Film Co., Ltd. was made into the 2nd protective film.

(d) Preparation of polarizing plate with a protective film

After mixing the mixed adhesive prepared by the method of (b) to both surfaces of the iodine type polarizing film obtained by (a) within 1 minute, apply | coating to the one surface of the 1st protective film which consists of said cycloolefin resin Corona treatment is performed on one side under the conditions of 250 w · min / m 2, the corona treatment surface is bonded within 30 seconds after the corona treatment, and the other surface is made of the triacetyl cellulose which is subjected to saponification treatment on the surface. 2 protective films were bonded together by the saponification process surface, it dried at 70 degreeC for 5 minutes, and it was set as the polarizing plate. This polarizing plate was further cured at 40 ° C for 2 days.

(e) Evaluation of adhesive strength: peel test

A cutter blade was placed in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of cycloolefin resin of the polarizing plate after curing, and peeling of the polarizing film and this protective film was attempted. I could not. Also about the surface of the 2nd protective film which consists of triacetyl cellulose, peeling test was performed similarly, and also it could not peel.

Example 2

"EA-W151B" manufactured by Toyo Moton Co., Ltd., an isocyanate-based curing agent, is used for 100 parts of "EA-W151A" (made by Toyota Moton Co., Ltd.), which is an acrylic polyol, which is a major urethane adhesive. 20 parts of components) were combined, and water was added again, and the solid content was diluted to 40%. Except having changed the urethane type adhesive agent into what was prepared here, like this Example 1, this urethane type adhesive agent and the polyvinyl alcohol-type aqueous solution were mixed by weight ratio 1: 1, and it was set as a mixed adhesive agent, and it used the same method as Example 1 using this. The polarizing plate was produced.

The cutter blade was inserted in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of cycloolefin resin of the obtained polarizing plate, and peeling of the polarizing film and this protective film was attempted, but the peeling was possible. There was no. The peeling test was similarly performed also on the surface of the 2nd protective film which consists of triacetyl cellulose, and also it could not peel.

Example 3

3 parts of carboxyl-modified polyvinyl alcohol "Gurerefobal KL318" of Kuraray Co., Ltd. is dissolved with respect to 100 parts of water, and "Sumirez resin 650" of Sumitomo Chemical Co., Ltd. which is a water-soluble polyamide epoxy resin is further dissolved there. 1.5 parts of "(water solution of 30% of solid content) was added, and it was set as the adhesive agent. A polarizing plate was produced in the same manner as in Example 1 except that the polyvinyl alcohol adhesive was changed to one prepared here.

The cutter blade was inserted in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of cycloolefin resin of the obtained polarizing plate, and peeling of the polarizing film and this protective film was attempted, but the peeling was possible. There was no. The peeling test was similarly performed also on the surface of the 2nd protective film which consists of triacetyl cellulose, and also it could not peel.

Example 4

The cycloolefin resin film and the brand name "SAC40" (40 micrometers in thickness) made by Sekisui Chemical Co., Ltd. were corona-treated on 250W.min / m <2> conditions, and it was set as the protective film. Using the same polarizing film and adhesive as in Example 1, a polarizing plate was produced under the same conditions as in Example 1 except that the protective film was applied to both surfaces of the polarizing film. The cutter blade was placed in the transmission axis direction at an angle of 45 ° to the film normal line direction on one side of the obtained polarizing plate, and the peeling of the polarizing film and the protective film on one side was tested, but could not be peeled off.

Example 5

Corona treatment was performed on a film having a thickness of 40 μm by pressing a copolymer having a molar ratio of ethylene: norbornene: styrene of 49:22:29 at 250 W · min / m 2, to form a protective film. Using the same polarizing film and adhesive as in Example 1, a polarizing plate was produced under the same conditions as in Example 1 except that the protective film was applied to both surfaces of the polarizing film. The cutter blade was placed in the transmission axis direction at an angle of 45 ° to the film normal line direction on one side of the obtained polarizing plate, and the peeling of the polarizing film and the protective film on one side was tested, but could not be peeled off.

Comparative Example 1

Except for using the urethane adhesive whose main agent is "EA-W151A" made by Toyomoton Co., Ltd., and the hardening | curing agent is "EA-W151B" made by Toyo Moton Co., Ltd. independently, and not adding polyvinyl alcohol-type resin aqueous solution, A polarizing plate was produced in the same manner as in Example 2. The cutter blade was inserted in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of the cycloolefin resin of the obtained polarizing plate, and peeling of the polarizing film and the protective film was attempted. there was. The protective film was not peeled off by the same peeling test on the surface of the second protective film made of triacetyl cellulose.

Comparative Example 2

The polarizing plate was produced in the same manner as in Example 3 except that the polyvinyl alcohol-based adhesive agent in which the water-soluble polyamide epoxy resin was added to the carboxyl group-modified polyvinyl alcohol aqueous solution was used alone, and the urethane-based adhesive was not added. The cutter blade was inserted in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of the cycloolefin resin of the obtained polarizing plate, and peeling of the polarizing film and the protective film was attempted. there was. About the 2nd protective film surface which consists of triacetyl cellulose, the protective film did not peel by the same peeling test.

Comparative Example 3

Under the same conditions as in Example 1, except that a 4.8% solution of polyvinyl alcohol "163-03045" (soaping degree of about 88%, polymerization degree of about 500) obtained from Wako Pure Chemical Industries, Ltd. was used as the polyvinyl alcohol adhesive. The polarizing plate was produced. The cutter blade was inserted in the transmission axis direction at an angle of 45 ° with respect to the film normal direction to the surface of the first protective film made of the cycloolefin resin of the obtained polarizing plate, and peeling of the polarizing film and the protective film was attempted. there was. About the 2nd protective film surface which consists of triacetyl cellulose, the protective film did not peel by the same peeling test.

Comparative Example 4

A polarizing plate was produced in the same manner as in Example 3 except that the polarizing film and the protective film were bonded one hour after mixing the urethane adhesive and the polyvinyl alcohol resin aqueous solution. As a result, precipitation generate | occur | produced in the liquid mixture and the external appearance of the obtained polarizing plate worsened.

By using the mixture of a urethane type adhesive agent and polyvinyl alcohol-type resin of a specific composition as an adhesive agent, the polarizing plate excellent in the adhesiveness of a polarizing film and a protective film can be obtained.

Claims (7)

A polarizing plate formed by laminating a protective film made of cycloolefin resin on one or both sides of a polyvinyl alcohol polarizing film through an adhesive layer, the adhesive layer containing a urethane adhesive and a polyvinyl alcohol resin, and the polyvinyl alcohol The system resin is a saponified product of a copolymer of vinyl acetate and other monomers copolymerizable therewith. The polarizing plate of Claim 1 whose cycloolefin resin is a copolymer which contains the unit of the monomer which consists of cycloolefin in 15-50 mol% ratio. The polarizing plate of Claim 1 or 2 whose urethane type adhesive agent is a two-component type which has a polyester main body and an isocyanate type hardening | curing agent as a main component. The polarizing plate according to any one of claims 1 to 3, wherein the polyvinyl alcohol-based resin constituting the adhesive layer is a saponified product of a copolymer of vinyl acetate and a monomer having a carboxyl group. The polarizing plate according to any one of claims 1 to 4, wherein the adhesive layer further contains a water-soluble epoxy compound. The protective film which consists of cycloolefin resin is a function as a retardation film, a function as a brightness enhancement film, a function as a reflective film, a function as a semi-transmissive film, and a function as a diffusion film in any one of Claims 1-5. And a function selected from a function as an optical compensation film. In manufacturing a polarizing plate by laminating a protective film made of cycloolefin resin on one or both sides of a polyvinyl alcohol polarizing film through an adhesive layer, the adhesive includes a urethane adhesive and vinyl acetate and other monomers copolymerizable therewith. Using a mixture of an aqueous solution of a polyvinyl alcohol-based resin that is a saponified product of the copolymer of, and applying an aqueous solution of a urethane-based adhesive and a polyvinyl alcohol-based resin to the surface of the polarizing film or protective film within 5 minutes after mixing, both Method of manufacturing a polarizing plate, characterized in that for carrying out the step of laminating.