KR20050077018A - Polarizing plate and method for producing the same - Google Patents

Abstract

(Problem) In order to laminate | stack a cycloolefin resin film on one surface of the polarizing film which consists of polyvinyl alcohol-type resin, laminate a cellulose acetate film on the other surface, and to make a polarizing plate, an appropriate adhesive agent is applied to each surface. Thus, the adhesive force between each protective film and the polarizing film is increased.

(Solution means) A cycloolefin-based polymer is disposed on one surface of a polarizing film made of polyvinyl alcohol-based resin with an aqueous first adhesive containing a polyester-ionomer-type urethane resin and a compound having a glycidyloxy group interposed therebetween. The resin film was laminated, and on the other side, a cellulose acetate-based film was laminated with an aqueous second adhesive having a composition different from the first adhesive, for example, an aqueous solution of polyvinyl alcohol-based resin, and a polarizing plate. do.

Description

Polarizing plate and manufacturing method thereof {POLARIZING PLATE AND METHOD FOR PRODUCING THE SAME}

In the present invention, a cellulose acetate film is laminated on one surface of a polarizing film made of polyvinyl alcohol-based resin with an adhesive layer interposed therebetween, and a cycloolefin resin film is laminated on the other surface with an adhesive layer interposed therebetween. It relates to a polarizing plate and a manufacturing method thereof.

The polarizing plate is usually a cellulose acetate-based protection represented by a transparent resin film, for example, triacetyl cellulose, with an adhesive layer interposed between one or both surfaces of a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. It is a structure which laminated | stacked the film. This is attached to a liquid crystal cell with an adhesive via the other optical film as needed, and becomes a component part of a liquid crystal display device.

As the use of the liquid crystal display expands, the liquid crystal display device is used in various environments, and high environmental resistance is required for components constituting the liquid crystal display device. For example, in the liquid crystal display device for mobile use represented by a mobile telephone, it is desired to be able to use even under moist heat, and high moisture heat resistance is also requested | required also about the polarizing plate used there. However, in the polarizing plate of the conventional structure, especially when it exposes in a humid heat environment for a long time, polarization performance will fall easily, and there existed a problem that the interface of a polarizing film and a cellulose acetate type film peels easily.

It is proposed to use thermoplastic cycloolefin resin as a protective film of a polarizing plate about such a problem. For example, Japanese Unexamined Patent Application Publication No. Hei 5-212828 (Patent Document 1) laminates a thermoplastic saturated norbornene-based resin sheet on at least one surface of a polyvinyl alcohol-based sheet via an acrylic pressure-sensitive adhesive, and heat-presses it to a polarizing plate. It is described. Japanese Laid-Open Patent Publication No. 6-51117 (Patent Document 2) discloses laminating a protective film made of thermoplastic saturated norbornene-based resin on at least one surface of a polyvinyl alcohol-based polarizing film to form a polarizing plate. As an adhesive agent to be used, the adhesive for dry lamination which mixed the polyurethane-type resin solution and the polyisocyanate resin solution, the styrene-butadiene rubber type adhesive agent, the epoxy type 2 liquid hardening type adhesive agent, etc. are illustrated. Moreover, Unexamined-Japanese-Patent No. 2000-321430 (patent document 3) has a cyclic | annular form with at least one surface of a polyvinyl alcohol-type polarizing film interposed the adhesive bond layer which is a mixture of a polyvinyl alcohol-type adhesive agent and a 2-liquid type adhesive agent. Laminating | stacking the protective film which consists of olefin resin is used as a polarizing plate is described. Moreover, Unexamined-Japanese-Patent No. 2000-321432 (patent document 4) describes that the protective film which consists of a polyvinyl alcohol-type polarizing film and thermoplastic saturated norbornene-type resin is adhere | attached with a polyurethane adhesive, and it is set as a polarizing plate.

However, in pressure sensitive adhesives (also called pressure-sensitive adhesives) such as acrylic, the thickness of itself was inevitably thickened to 10 to 50 µm. In addition, the adhesive for dry lamination, the styrene-butadiene rubber adhesive, the epoxy-based two-liquid curing adhesive, and the like contained an organic solvent, and there were environmental problems and worker health problems. Moreover, when it is going to apply the adhesive agent containing such an organic solvent to the polarizing plate manufacturing equipment which does not use the conventional organic solvent, the complexity of facility remodeling, such as establishment of explosion-proof installation, was accompanied.

On the other hand, the polarizing plate is often required to have a function such as scratch resistance, antistatic property, anti-glare property, antireflection property and the like on its surface. The cycloolefin-based resin film is not necessarily easy to impart a function to the surface thereof compared with a conventional protective film made of cellulose acetate-based resin such as triacetyl cellulose, so that the function is insufficient or impart function. Even if it could, it became expensive product. Therefore, as a protective film of at least one surface of a polarizing plate, a cellulose acetate resin is preferable in many cases.

Conventionally, various proposals are made | formed mainly about making cellulose acetate resin into a protective film, and adhesion | attachment with it and a polyvinyl alcohol-type polarizing film. As an aqueous adhesive which does not contain an organic solvent, Unexamined-Japanese-Patent No. 7-134212 (patent document 5), for example, glyoxal to the polyvinyl alcohol adhesive which adheres a polyvinyl alcohol-type polarizing film and a protective film It is described that compounding a predetermined amount, and also Japanese Unexamined Patent Publication No. 9-258023 (Patent Document 6), similarly, a water-soluble epoxy compound to a polyvinyl alcohol-based adhesive bonding a polyvinyl alcohol-based polarizing film and a protective film It is described that a predetermined amount is blended, and the improvement of adhesiveness is intended. However, when a polyvinyl alcohol polarizing film and a cycloolefin resin film are adhere | attached using these polyvinyl alcohol-type adhesive agents, Moreover, adhesive agents, such as a polyvinyl alcohol-type, urethane type, an acryl type, vinyl acetate type, which are generally known, are used Also in a case, adhesiveness was not necessarily enough by the combination of both films.

(Patent Document 1) JP-A-5-212828

(Patent Document 2) Japanese Unexamined Patent Publication No. Hei 6-51117

(Patent Document 3) Japanese Unexamined Patent Publication No. 2000-321430

(Patent Document 4) Japanese Unexamined Patent Publication No. 2000-321432

(Patent Document 5) Japanese Unexamined Patent Publication No. Hei 7-134212

(Patent Document 6) Japanese Unexamined Patent Publication No. Hei 9-258023

An object of the present invention is to laminate a cycloolefin resin film on one surface of a polarizing film made of polyvinyl alcohol-based resin with an adhesive layer interposed therebetween, and on the other side, a cellulose acetate-based product with an adhesive layer interposed therebetween. In laminating | stacking a film and making it a polarizing plate, it is what improves the adhesive force between a polarizing film and each protective film by applying an appropriate adhesive agent to each surface. Another object of the present invention is to produce a polarizing plate in which a polyvinyl alcohol polarizing film and a protective film are firmly adhered to each other using an aqueous adhesive that does not substantially contain an organic solvent.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching on this objective, as an adhesive agent which bonds a polarizing film and a cycloolefin resin film, it uses the aqueous mixture which mix | blended specific components, and as an adhesive agent which bonds a polarizing film and a cellulose acetate type film, By using a water-based adhesive but with a different composition, it was found that a polarizing plate excellent in the adhesion between the polarizing film and the protective film was obtained, and the present invention was reached.

That is, according to this invention, the 1st adhesive agent formed with the composition containing the polyester-ionomer type urethane resin and the compound which has glycidyloxy group in one surface of the polarizing film which consists of polyvinyl alcohol-type resins The cycloolefin resin film is laminated | stacked through the layer, and the other side is provided with the polarizing plate in which the cellulose acetate type film is laminated | stacked through the 2nd adhesive bond layer of a composition different from the said 1st adhesive bond layer.

Moreover, according to this invention, the one surface of the polarizing film which consists of polyvinyl alcohol-type resin interposes the water-based 1st adhesive agent containing a polyester type ionomer-type urethane resin and the compound which has glycidyloxy group between them. There is also provided a method of manufacturing a polarizing plate by laminating a cycloolefin-based resin film and laminating a cellulose acetate-based film on the other side with an aqueous second adhesive having a composition different from the first adhesive. The aqueous adhesive can be used here in the form which does not contain the organic solvent substantially.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described in detail. In the polarizing plate of the present invention, a cycloolefin-based resin film is laminated on one surface of a polarizing film made of polyvinyl alcohol-based resin with a first adhesive layer interposed therebetween, and on the other side, an acetic acid is placed with a second adhesive layer interposed therebetween. It is manufactured by laminating a cellulose film. As for the polarizing film which consists of polyvinyl alcohol-type resin, a dichroic dye is adsorbed-oriented specifically to the polyvinyl alcohol-type resin film uniaxially stretched. And in this invention, as a 1st adhesive bond layer which bonds the said polarizing film and a cycloolefin resin film, the mixture of the polyester-type ionomer-type urethane resin and the compound which has glycidyloxy group is employ | adopted, and a polarizing film and cellulose acetate As a 2nd adhesive bond layer which bonds a system film, the thing of a composition different from a 1st adhesive bond layer is employ | adopted.

Polyvinyl alcohol-type resin which comprises a polarizing film is obtained by saponifying a polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with it besides the polyvinyl acetate which is a homopolymer of vinyl acetate are illustrated. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamide which has an ammonium group, etc. are mentioned, for example. The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified. For example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes can also be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000.

What formed such polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method of forming a film of polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the film thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, they are about 10 micrometers-150 micrometers.

The polarizing film is usually a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye, and a polyvinyl alcohol-based adsorbed dichroic dye. It manufactures through the process of processing a resin film with aqueous boric acid solution, and the process of washing with water after the process by this boric acid aqueous solution.

Uniaxial stretching may be performed before dyeing, may be performed simultaneously with dyeing, and may be performed after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or may be performed during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these several steps. At the time of uniaxial stretching, you may extend | stretch to 1 axis between rolls from which a rotation speed differs, and you may extend | stretch to 1 axis using a thermal roll. Moreover, dry extending | stretching, such as extending | stretching in air | atmosphere, may be sufficient, and wet extending | stretching extending | stretching in the state swelled with the solvent may be sufficient. A draw ratio is about 3 to 8 times normally.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, what is necessary is just to immerse a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye. As a dichroic dye, an iodine and a dichroic dye are used specifically. Moreover, it is preferable to immerse a polyvinyl alcohol-type resin film with respect to water before a dyeing process.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is about 20-40 degreeC normally, and the immersion time (dyeing time) with respect to this aqueous solution is about 20-1,800 second normally.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. Content of the dichroic dye in this aqueous solution is about 1 * 10 <^-4> -10 weight part normally per 100 weight part of water, Preferably it is about 1 * 10 <^{-3> -1} weight part. This aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. The temperature of the dye aqueous solution used for dyeing is about 20-80 degreeC normally, and the immersion time (dyeing time) with respect to this aqueous solution is about 10-1,800 second normally.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-type resin film in boric acid containing aqueous solution. The amount of boric acid in boric acid containing aqueous solution is about 2-15 weight part normally per 100 weight part of water, Preferably it is about 5-12 weight part. When using iodine as a dichroic dye, it is preferable that this boric acid containing aqueous solution contains potassium iodide. The amount of potassium iodide in the boric-acid containing aqueous solution is about 0.1-15 weight part normally per 100 weight part of water, Preferably it is about 5-12 weight part. Immersion time with boric acid containing aqueous solution is about 60 to 1,200 second normally, Preferably it is about 150 to 600 second, More preferably, it is about 200 to 400 second. The temperature of boric-acid containing aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC, More preferably, it is 60-80 degreeC.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. The water washing treatment is performed by, for example, immersing the polyvinyl alcohol-based resin film treated with boric acid in water. The temperature of the water in a water washing process is about 5-40 degreeC normally, and immersion time is about 1-120 second normally. After water washing, it is dried and a polarizing film is obtained. The drying treatment is usually performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying treatment time is usually about 60 to 600 seconds, and preferably about 120 to 600 seconds.

In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of this polarizing film is about 5-40 micrometers. In this invention, a cycloolefin resin film is laminated | stacked on one surface of this polarizing film through a 1st adhesive bond layer, A cellulose acetate type film is laminated | stacked on the other surface through a 2nd adhesive bond layer, It becomes a polarizing plate.

Cycloolefin resin is a thermoplastic resin which has a monomer unit which consists of cyclic olefins (cycloolefin), such as a norbornene and a polycyclic norbornene-type monomer, for example. The cycloolefin resin may be a hydrogenated product of the ring-opening polymer of the cycloolefin or the ring-opening copolymer using two or more cycloolefins, and an addition copolymer of cycloolefin with an aromatic compound having a linear olefin or vinyl group. You may also. 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 and α-. Methyl styrene, nuclear alkyl substituted styrene, etc. are mentioned. In such a copolymer, the monomer unit 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 monomer unit composed of the cycloolefin may be so relatively small. In such a terpolymer, the monomer unit which consists of linear olefins is about 5 to 80 mol% normally, and the monomer unit which consists of aromatic compounds which have a vinyl group is about 5 to 80 mol% normally.

Examples of commercially available thermoplastic cycloolefin resins include "Topas" sold by Ticona of Germany, "Aton" sold by JSR, and "Zenoor" sold by Nippon Zeon Co., Ltd. ) "," ZEONEX "and" Apel "sold by Mitsui Chemicals. Although the cycloolefin resin is formed into a film to form a film, known methods such as a solvent cast method and a melt extrusion method are suitably used for the film formation. The cycloolefin resin film with a film | membrane is also commercially available, for example, "Essina" and "SCA40" sold by Sekisui Chemical Industry Co., Ltd., "Zenoa film" sold by Optex Co., Ltd. Etc.

The cycloolefin resin film may be uniaxially or biaxially stretched. The draw ratio in this case is about 1.1 to 5 times normally, Preferably it is 1.1 to 3 times.

In this invention, the cellulose acetate film used as the other protective film is a cellulose partial or fully acetate acetate, For example, a triacetyl cellulose film, a diacetyl cellulose film, etc. are mentioned. Commercially available triacetyl cellulose films include "Fujitak TD80", "Fujitak TD80UF" and "Fujitak TD80UZ" sold by Fuji Photo Film Co., Ltd., and "KC8UX2M" sold by Konica Minolta Offto Co., Ltd. And "KC8UY" and the like.

Although the thickness of a protective film is thinner, when it is too thin, intensity | strength will fall and workability will fall, while too thick, a problem, such as transparency will fall or a weight of a polarizing plate will become large. Therefore, the suitable thickness of a cycloolefin resin film is about 5-200 micrometers, for example, Preferably it is 10-150 micrometers, More preferably, it is 20-100 micrometers. In addition, the thickness of a cellulose acetate film is about 20-200 micrometers normally.

The protective film which consists of these cycloolefin resins and / or cellulose acetate resins is surface-treated, such as an anti-glare process, a hard-coat process, an antistatic process, an antireflective process, etc. to the surface on the opposite side to the surface affixed to a polarizing film, You may be. Moreover, the coating layer which consists of a liquid crystalline compound, its high molecular weight compound, etc. may be formed.

The cycloolefin resin film described above is laminated on one surface of the polarizing film with the first adhesive layer interposed therebetween, and the cellulose acetate film described above with the second adhesive layer interposed on the other surface. This is laminated | stacked and it becomes a polarizing plate.

The 1st adhesive agent used for the bonding of a polarizing film and a cycloolefin resin film is made into the mixture of the polyester-type ionomer type urethane resin and the compound which has glycidyloxy group. The polyester ionomer-type urethane resin here is a urethane resin which has a polyester frame | skeleton, and a small amount of ionic component (hydrophilic component) is introduce | transduced in it. Such an ionomer-type urethane resin is suitable as an aqueous adhesive, since it emulsifies in water directly, without using an emulsifier, and becomes an emulsion. Polyester-based ionomer-type urethane resins are known per se and are described, for example, in Japanese Patent Application Laid-open No. Hei 7-97504 as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium. Such polyester ionomer type urethane resin can be manufactured, for example by the following method.

(1) a method of emulsifying a hydrophilic group-containing polyurethane resin obtained by reacting a hydrophilic group-containing compound (A), a polyester polyol (B) and a polyisocyanate (C) in water to obtain an ionomer resin; (2) A hydrophilic group-containing compound (A), a polyester polyol (B) and a polyisocyanate (C) are reacted to disperse the terminal isocyanato group-containing urethane polymer having a hydrophilic group introduced therein in water, and react with a polyamine to react with an ionomer. Method of obtaining a resin;

Examples of the hydrophilic group-containing compound (A) used herein include sulfonic acid group-containing compounds such as 2-hydroxyethanesulfonic acid, sulfosuccinic acid, sulfanilic acid, 2,4-diaminotoluenesulfonic acid, and 2,2-dimethylolpropionic acid. And carboxylic acid group-containing compounds such as dihydroxymaleic acid and 3,4-diaminobenzoic acid, and polyoxyethylene glycol or polyoxyethylene-polyoxypropylene copolymer glycol having at least one active hydrogen in the polymer. .

The polyester polyol (B) is a polyester obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, or a copolyester thereof, in addition to the polyester obtained by the dehydration condensation reaction between the glycol component and the acid component. Can be. Examples of the glycol component used in the polyester polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6 Hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight 300-6,000), dipropylene glycol, tripropylene glycol, 2,2-diethyl-1,3-propanediol , 2-butyl-2-ethyl-1,3-propanediol, 2-pentyl-2-propyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, 2-ethyl- 1,3-hexanediol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, hydroquinone and their alkylene oxide adducts and the like have. Further, the acid component includes succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, Phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-p, p'- Dicarboxylic acids, and anhydrides and ester-forming derivatives of these dicarboxylic acids, p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, and ester-forming derivatives of these hydroxycarboxylic acids.

The polyester ionomer-type urethane resin, in addition to the polyester polyol described above, is used in combination with other high molecular weight polyol components and low molecular weight active hydrogen-containing compounds in a range that does not impair the effects of the present invention. You can do it. As a high molecular weight polyol, polyether polyol, polycarbonate polyol, polyacetal polyol, polyacrylate polyol, polyesteramide polyol, polythioether polyol, etc. are mentioned, for example. As the low molecular weight active hydrogen-containing compound, for example, polyhydroxy compounds such as ethylene glycol, neopentyl glycol, 1,6-hexanediol, glycerin, trimethylolpropane, diamines such as ethylenediamine and piperazine Compounds and the like. Especially, it is a preferable form to use together a low molecular weight active hydrogen containing compound.

Said polyisocyanate (C) is a compound which has at least two isocyanato groups in a molecule | numerator, For example, 2, 4- tolylene diisocyanate, phenylene diisocyanate, 4,4'- diphenylmethane di Isocyanate, 1, 6- hexamethylene diisocyanate, isophorone diisocyanate etc. are mentioned.

Although reaction of these hydrophilic group containing compound (A), polyester polyol (B), and polyisocyanate (C) may be made without a solvent, even if it is carried out in an organic solvent, it does not interfere. The obtained resin is neutralized with a nonvolatile base such as sodium hydroxide or potassium hydroxide, amines such as triethylamine or dimethylethanolamine, or ammonia, and water is added thereto, whereby an aqueous dispersion of polyester ionomer-type urethane resin Obtained.

When polyester-type ionomer-type urethane resin is obtained in the state containing an organic solvent by using an organic solvent for reaction, it is advantageous to use, after removing the organic solvent by distillation etc. Since this urethane resin is an ionomer type, very fine and stable colloid can be formed in water, and it becomes an aqueous adhesive which does not contain the organic solvent.

It is preferable that weight average molecular weights of a polyester type ionomer type urethane resin are 5,000 or more, More preferably, they are 10,000 or more and 300,000 or less. If the weight average molecular weight is less than 5,000, the strength of the adhesive layer cannot be sufficiently obtained, and if the weight average molecular weight is greater than 300,000, the viscosity at the time of making it an aqueous dispersion becomes difficult to handle.

Such a polyester ionomer-type urethane resin is disperse | distributed in water, and becomes an aqueous adhesive. It is preferable in handling that the viscosity of this aqueous adhesive is 2,000 mPa * sec or less, More preferably, it is 1,000 mPa * sec or less, Especially preferably, it is 500 mPa * sec or less. The lower the viscosity, the easier it is to apply the adhesive, and the appearance of the obtained polarizing plate is also good. The solid content concentration of the polyester-based ionomer-type urethane resin in this water-based adhesive agent is preferably in the range of 10 to 70% by weight from the viewpoint of viscosity and adhesive strength, and is particularly preferably 20% by weight or more and 50% by weight or less. More preferred.

In addition to polyethylene glycol, polyoxyethylene, surfactant, etc. may be added to the aqueous dispersion of polyester-type ionomer type urethane resin. Moreover, water-soluble resin, such as polyhydroxyethyl methacrylate, polyhydroxyethyl acrylate, polyacrylic acid, and polyvinyl alcohol-type resin, may be added.

Commercially available polyester-based ionomer-type urethane resins suitable for use in the present invention include, for example, "Hylan AP-20" and "Hylan APX-101H" sold by Dainippon Ink Chemical Co., Ltd. Etc. can be mentioned.

In this invention, the compound which has glycidyloxy group is further mix | blended with polyester-type ionomer type urethane resin as demonstrated above, and it is set as the 1st adhesive agent for bonding a polarizing film and a cycloolefin resin film. By using together the compound which has such glycidyloxy group, the adhesiveness of a polarizing film and a cycloolefin resin film improves. The glycidyloxy group here is group represented by following formula, and should be called also a 2, 3- epoxy propoxy group in pure chemical terms.

It is preferable that especially the said glycidyloxy group is ether bonded. The compound having a glycidyloxy group preferably has at least two glycidyloxy groups in the molecule, and examples thereof include polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polytetramethylene glycol digly Cydyl ether, neopentyl glycol diglycidyl ether, diglycerin diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol Polyglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, polyglycerol polyglycidyl ether, and the like. It is preferable that the molecular weight of the compound which has glycidyloxy group is 5,000 or less in a weight average molecular weight. As a commercial item of the compound which has glycidyloxy group, "CR-5L" etc. which are sold from Dainippon Ink Chemical Co., Ltd. are mentioned, for example.

The mixing ratio of the polyester ionomer-type urethane resin and the compound having a glycidyloxy group is about 5 to 100 parts by weight of the compound having a glycidyloxy group based on 100 parts by weight of the solid content of the polyester-based ionomer type urethane resin. It is preferable to select suitably so that it may become the range of, More preferably, it is preferable to select so that the compound which has glycidyloxy group may become 5 to 60 weight part, Especially preferably, it is 5 to 30 weight part. If the ratio of the compound having a glycidyloxy group is too low, sufficient adhesive strength cannot be obtained, and if the ratio is too large, the viscosity of the adhesive becomes high and difficult to handle.

Aqueous adhesives containing a polyester-ionomer-type urethane resin and a compound having a glycidyloxy group are substantially free of organic solvents, and thus have no risk of causing environmental or worker health problems. A high adhesive force is provided by using together the compound which has a dileoxy group.

On the other hand, the 2nd adhesive agent for bonding of a polarizing film and a cellulose acetate type film is water-based, What is necessary is just to adhere | attach both firmly. The polyester-type ionomer type urethane resin mentioned above can also be used also for a 2nd adhesive agent. However, in this case, it is not necessary to use together the compound which has glycidyloxy group, Therefore, it is set as a composition different from the above-mentioned 1st adhesive bond layer.

When using a polyester ionomer type urethane resin for a 2nd adhesive agent, in order to improve adhesiveness with respect to a cellulose acetate film, the compound which has isocyanato group, especially has at least 2 isocyanato group in a molecule | numerator It is preferable to use a polyisocyanate compound together. As such an isocyanato-group containing compound, 2, 4- tolylene diisocyanate, phenylene diisocyanate, 4,4'- diphenylmethane diisocyanate, 1, 6- hexamethylene diisocyanate, isophorone diisocyanate, for example. Monomers and oligomers such as these, and reactants of these compounds with polyols. Examples of the polyol used for this purpose include 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and the like. Even if the molecular weight of these isocyanato-group containing compounds is a reactant with said oligomer and polyol, 5,000 or less are preferable at a weight average molecular weight. As a preferable commercially available isocyanato-group containing compound, "hydran asysta C1" etc. which are sold from Dainippon Ink Chemical Industry Co., Ltd. are mentioned, for example.

The mixing ratio of the polyester-based ionomer-type urethane resin and the isocyanato-group-containing compound ranges from about 5 to 100 parts by weight of the isocyanato-group-containing compound relative to 100 parts by weight of the solid content of the polyester-based ionomer-type urethane resin. It is preferable to select suitably so that it is more preferable, More preferably, it is preferable to select so that an isocyanato-group containing compound may be in the range of 5-60 weight part, Especially preferably, it is 5-30 weight part. If the ratio of the isocyanato group-containing compound is too low, sufficient adhesive strength cannot be obtained. If the ratio is too large, the viscosity of the adhesive becomes high and it is difficult to handle.

Thus, as a 1st adhesive agent for bonding a polarizing film and a cycloolefin resin film, and a 2nd adhesive agent for bonding a polarizing film and a cellulose acetate film, the composition containing polyester-type ionomer type urethane resin, respectively, can be used. However, when urethane resin is used as an adhesive, sufficient bonding strength can be obtained only after curing at least 12 hours, usually several days or more, at a temperature of room temperature or more after bonding. Therefore, in an uncured state, the adhesive layer is limited to operations such as cutting and attachment to other films, and in particular, in the case of manufacturing at a wide width, the manufacturing cost may increase.

Therefore, when polyvinyl alcohol-type resin is used as a 2nd adhesive agent for bonding of a polarizing film and a cellulose acetate film, the adhesive force which is stable immediately after manufacture of a polarizing plate is obtained at the interface of a polarizing film and a cellulose acetate film. Due to this adhesive force, operations such as cutting and bonding can be easily performed even immediately after the production of the weak adhesive force between the interface between the other polarizing film and the cycloolefin resin film is weak.

In this case, an aqueous solution of polyvinyl alcohol-based resin is used as the second adhesive agent. In addition to partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, polyvinyl alcohol-based resins are modified such as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Polyvinyl alcohol-type resin may be sufficient.

The concentration of the polyvinyl alcohol-based resin in the adhesive is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight based on 100 parts by weight of water. In order to improve adhesiveness, it is preferable to add curable components, such as a glyoxal and a water-soluble epoxy resin, to a polyvinyl alcohol-type adhesive agent, or a crosslinking agent. The water-soluble epoxy resin is, for example, a polyamide obtained by reacting epichlorohydrin with a polyamide polyamine obtained by the reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid. Polyamine epoxy resins. Commercially available products of such polyamide polyamine epoxy resins include "Sumirez Resin 650" and "Semirez Resin 675" sold by Sumitomo Chemical Industries, Ltd., and "Sold by Japan PMC." WS-525 ". The addition amount of these curable components-a crosslinking agent is 1-100 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resins, Preferably it is 1-50 weight part. When there is little addition amount, an adhesive improvement effect becomes small, and when there is much addition amount, there exists a tendency for an adhesive bond layer to become weak.

The method of bonding a polarizing film and a protective film with an adhesive may be generally known in general, for example, by a casting method, a meyer coat method, a gravure coating method, a die coating method, a dip coating method, a spraying method, or the like. The method of apply | coating an adhesive agent to the adhesive surface of a polarizing film and / or a protective film, and superimposing both is mentioned. A casting method is a method of flowing and spreading an adhesive on the surface while moving the polarizing film or the protective film which is a to-be-coated object to the roughly vertical direction, the roughly horizontal direction, or the diagonal direction between them. After apply | coating an adhesive agent, a polarizing film and a protective film are pinched | interposed by a nip roll etc., and are adhere | attached.

Moreover, in order to improve adhesiveness, you may perform suitably surface treatments, such as a plasma treatment, a corona treatment, an ultraviolet irradiation process, a flame | frame (flame) process, a saponification process, to the adhesive surface of a polarizing film and / or a protective film. As a saponification process, the method of immersing in aqueous alkali solution, such as sodium hydroxide and potassium hydroxide, is mentioned.

After laminating | stacking a polarizing film and a protective film, a drying process is performed. A drying process is performed by spraying hot air, for example, and the temperature at that time is suitably selected in the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. Drying time is about 20-1,200 second. After drying, curing at room temperature or a slightly higher temperature, for example, at a temperature of about 20 to 50 ° C. for about 12 to 600 hours is particularly preferable for increasing the adhesive strength of the adhesive layer made of a urethane resin. The thickness of the adhesive bond layer after drying is about 0.001-5 micrometers normally, Preferably it is 0.01 micrometer or more, More preferably, it is 2 micrometers or less, Especially preferably, it is 1 micrometer or less. When the thickness of the adhesive layer becomes thicker than 5 m, the appearance of the polarizing plate tends to be poor.

In the polarizing plate of this invention, you may adhere an optical functional film to the surface of a protective film via an adhesive. As an optical functional film, the optical compensation film which the liquid crystalline compound is apply | coated and orientated on the surface of a base material, the reflective polarization which transmits the polarized light of some kind, and reflects the polarized light which shows the opposite property to it is reflected, for example. Separation film, retardation film made of polycarbonate resin, retardation film made of cyclic polyolefin resin, film with anti-glare function having uneven shape on the surface, film with anti-reflection treatment, reflection film with reflection function on surface, The semi-transmissive reflective film etc. which have a reflection function and a transmission function are mentioned. As a commercial item corresponded to the optical compensation film by which the liquid crystalline compound is apply | coated and oriented on the surface of a base material, "WV film" sold by Fuji Photographic Film Co., Ltd., "NH sold by Shin-Niptsu Sekiyu Co., Ltd." Films "and" NR films "(both trade names). As a commercial item corresponding to the reflective polarization separating film that transmits any kind of polarized light and reflects the opposite property, Minnesota Mining and Manufacturing (3M) (Sumitomo 3M Co., Ltd. in Japan) ) And "DBEF" (trade name). Moreover, as a commercial item corresponded to the retardation film which consists of cyclic polyolefin resin, "Aton" sold by JSR Co., Ltd. "Esshina" sold by Sekisui Chemical Industry Co., Ltd. "Zenooa Film" (all trade names) sold by Optex.

(Example)

Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited by these examples. In the example,% and part which show content-usage-amount are a basis of weight unless there is particular notice.

Example 1

(a) Preparation of Polarizing Film

A polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a degree of saponification of at least 99.9 mol% and a thickness of 75 μm was uniaxially stretched by about 5 times in a dry manner, and then immersed in pure water at 60 ° C. for 1 minute while maintaining tension again. And it was immersed at 28 degreeC for 60 second in the aqueous solution which is 0.05 / 5/100 weight ratio of iodine / potassium iodide / water. Then, it was immersed at 72 degreeC for 300 second in the aqueous solution whose weight ratio of potassium iodide / boric acid / water is 8.5 / 8.5 / 100. Subsequently, after wash | cleaning for 20 second in the pure water of 26 degreeC, it dried at 65 degreeC and obtained the polarizing film in which iodine adsorption-orientated to polyvinyl alcohol.

(b) Preparation of adhesive

Aqueous emulsion of polyester-type ionomer-type urethane resin ("Hylan AP-20" by Dainippon Ink Chemical Co., Ltd., 30% of solid content concentration, viscosity 30 mPasec) polyfunctional glycidyl to 100 parts 5 parts of "CR-5L" by Dainippon Ink Chemical Co., Ltd. which is an ether was added, and it was set as the polyurethane adhesive (A).

Separately, in 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol ("Kurarefobal KL318" manufactured by Kuraray Co., Ltd.) and a water-soluble polyamide epoxy resin ("Sumirez resin 650" manufactured by Sumitomo Chemical Industries, Ltd.) 1.5 parts of (water solution of 30% of solid content concentration) were added, and it was set as the polyvinyl alcohol-type adhesive agent.

(c) Preparation and evaluation of polarizer

On one surface of the polarizing film obtained in (a), a protective film having a thickness of 100 μm made of a corona treated norbornene-based resin was attached using the polyurethane adhesive (A), and on the other surface, the poly Through a vinyl alcohol adhesive, a protective film having a thickness of 80 μm made of triacetyl cellulose subjected to surface saponification was adhered, and dried at 80 ° C. for 7 minutes to obtain a polarizing plate. The norbornene-based resin film was peeled off as the result of peeling the polarizing film and the protective film by inserting the cutter blade in the transmission axis direction at an angle of 45 ° with respect to the normal direction of the film to the surface of the polarizing plate. The film did not peel at all. The polarizing plate in the state which did not insert the blade of a cutter was cured for 9 days at 40 degreeC after that. As a result of testing peeling of a protective film with the method similar to the above about the polarizing plate after hardening, neither surface peeled at all.

Example 2

100 parts of the aqueous emulsion "hydran AP-20" of the same polyester-based ionomer-type urethane resin as used in Example 1 (b) was manufactured by Dainippon Ink and Chemicals Co., Ltd., which is an isocyanato group-containing compound. 7.5 parts and "30 parts" of water were added for "hydran acyta C-1", and it was set as the polyurethane adhesive (B). Except having used this polyurethane adhesive (B) instead of the polyvinyl alcohol adhesive, the polarizing plate was produced by the method similar to (c) of Example 1, and was further cured at 40 degreeC for 9 days. As a result of peeling test of Example 1 about the polarizing plate after curing, neither norbornene-type resin film nor triacetyl cellulose film peeled at all.

According to this invention, a cycloolefin resin film is laminated | stacked on one surface of a polyvinyl alcohol-type polarizing film, and a cellulose acetate film is laminated | stacked as a protective film on the other surface, respectively, and it is excellent in the adhesiveness of a polarizing film and both protective films. A polarizing plate can be manufactured. Moreover, at the time of manufacture of this polarizing plate, since it is not necessary to use an organic solvent, it is excellent in an environmental aspect and safety hygiene, and can be manufactured by the same equipment as the polarizing plate which consists of a conventional transparent protective film / polarizing film, There is no need to invest in large equipment.

Claims (9)

Cycloolefin resin film on one surface of a polarizing film made of polyvinyl alcohol resin, with a first adhesive layer formed of a composition containing a polyester-ionomer-type urethane resin and a compound having a glycidyloxy group Laminated | stacked and the other surface WHEREIN: The cellulose acetate film is laminated | stacked through the 2nd adhesive bond layer of a composition different from the said 1st adhesive bond layer, The polarizing plate characterized by the above-mentioned. The polarizing plate of Claim 1 in which a 2nd adhesive bond layer contains polyester-type ionomer type urethane resin, and is formed with the composition of a composition different from a 1st adhesive bond layer. The polarizing plate of Claim 2 in which the 2nd adhesive bond layer is formed from the composition containing polyester-type ionomer type urethane resin and a polyisocyanate compound. The polarizing plate of Claim 1 in which the 2nd adhesive bond layer is formed from the composition containing polyvinyl alcohol-type resin. On one surface of the polarizing film made of polyvinyl alcohol-based resin, a cycloolefin-based resin film is laminated with a polyester-based ionomer-type urethane resin and an aqueous first adhesive containing a compound having a glycidyloxy group interposed therebetween. And the other surface WHEREIN: The manufacturing method of the polarizing plate characterized by laminating | stacking a cellulose acetate type film | membrane through the water-based 2nd adhesive agent which has a composition different from the said 1st adhesive agent. The method according to claim 5, wherein the second adhesive contains a polyester ionomer-type urethane resin and is a water-based adhesive having a composition different from that of the first adhesive. The method according to claim 6, wherein the second adhesive is an aqueous adhesive containing a polyester-based ionomer-type urethane resin and a polyisocyanate compound. The method of claim 5, wherein the second adhesive is an aqueous solution of polyvinyl alcohol-based resin. The method according to any one of claims 5 to 8, wherein the first adhesive and the second adhesive are both substantially free of an organic solvent.