JP2010286754A - Polarizing plate, method for manufacturing the same, and laminated optical member obtained by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate constituted so that a protective film and a polarizing film are stuck via a non-aqueous adhesive allowing coating and laminating even at room temperature. <P>SOLUTION: The polarizing plate is provided which is manufactured by laminating the protective film formed from a transparent resin, to at least one surface of the polarizing film formed from a polyvinyl alcohol resin, via an adhesive layer, wherein the adhesive layer is a cured product of an adhesive composition containing an acrylic curing component, a radical polymerization initiator and a proton generating agent (for example, a cationic polymerization initiator). The polarizing plate is manufactured by forming a coating film layer comprising the adhesive composition on the laminating surface of at least one of the polarizing film and the protective film; laminating the polarizing film to the protective film via the coating film layer of the adhesive composition; and curing the adhesive composition (for example, curing the adhesive composition by irradiating the adhesive composition with active energy rays). A laminated optical member is obtained by laminating another optical layer (for example, a retardation film) on the polarizing plate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polarizing plate in which a protective film is bonded to one side or both sides of a polarizing film made of a polyvinyl alcohol-based resin, and a method for producing the polarizing plate. The present invention also relates to a laminated optical member using this polarizing plate.

  The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. The polarizing plate is usually used by being incorporated in a liquid crystal display device in a state where protective films are laminated on both sides of the polarizing film. It is also known to provide a protective film only on one side of the polarizing film, but even in that case, the other side is not just a protective film, but a film having another optical function, such as a retardation plate, In many cases, it is also pasted to serve as a protective film. As a protective film for a polarizing plate, a triacetyl cellulose film has been used in many cases. However, a cycloolefin resin film has recently been used because of its high moisture permeability.

  Conventionally, in order to bond a protective film and a polarizing film, as described in JP-A-2005-222013 (Patent Document 1), an aqueous adhesive mainly composed of polyvinyl alcohol is often used. ing. However, since water is generally difficult to evaporate, when a water-based adhesive is used, there is a problem in productivity, for example, the drying time must be extended. In addition, some protective films or films having optical functions have low moisture permeability, and when bonding such low moisture permeability films, moisture is more difficult to remove. It was desired.

  To date, as non-aqueous adhesives for polarizing plates, JP-A-8-216316 (Patent Document 2), JP-A-9-159826 (Patent Document 3) and JP-A-2004-70290 (Patent Document 4). It is reported that an ultraviolet curable resin composition as shown in FIG. However, when using such an ultraviolet curable adhesive, it is necessary to heat at the time of application | coating of the adhesive agent, and at the time of bonding of a protective film and a polarizing film, and the bonding process was complicated. Moreover, although the ultraviolet curable adhesive disclosed in these documents strongly adheres to the film made of cycloolefin resin and the polarizing film, the cellulose acetate resin film including triacetyl cellulose and the polarizing film There was a problem that the adhesive strength between them was weak.

  Therefore, JP 2000-321432 A (Patent Document 5) proposes that a polyvinyl alcohol polarizing film and a protective film made of a thermoplastic saturated norbornene resin are bonded with a polyurethane adhesive. Yes. However, the polyurethane adhesive has a problem that it takes a long time to cure, and the adhesive strength is not necessarily sufficient.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 6) discloses that an adhesive mainly composed of an epoxy resin containing no aromatic ring is used for bonding a polyvinyl alcohol polarizing film and a protective film. An adhesion method based on cationic polymerization by heating or irradiation with active energy rays has been proposed.

  JP 2008-174667 A (Patent Document 7) discloses a polyfunctional (meth) acrylic compound having two or more (meth) acryloyl groups in the molecule, a hydroxyl group in the molecule, and a polymerizable property. An active energy ray-curable adhesive composition obtained by blending a hydroxyl group-containing monofunctional (meth) acrylic compound having only one double bond and (meth) acrylate of an alkylene oxide-modified phenol at a predetermined ratio, It has been proposed to be used for adhesion between an alcohol polarizing film and a thermoplastic norbornene resin film.

Japanese Patent Laid-Open No. 2005-222013 JP-A-8-216316 JP-A-9-159826 JP 2004-70290 A JP 2000-32432 A JP 2004-245925 A JP 2008-174667 A

  An object of the present invention is to provide a polarizing plate in which a protective film and a polarizing film are bonded via a non-aqueous adhesive that can be applied and bonded even at room temperature. Another object of the present invention is to protect a film made of cycloolefin resin and a film made of cellulose resin using a non-aqueous adhesive that can be firmly bonded to a polyvinyl alcohol polarizing film. The purpose is to bond the film and the polarizing film.

  As a result of intensive studies to solve such problems, the present inventors have completed the present invention. That is, according to the present invention, a protective film made of a transparent resin is bonded to at least one surface of a polarizing film made of a polyvinyl alcohol resin via an adhesive layer, and the adhesive layer includes an acrylic curing component, a radical A polarizing plate which is a cured product of an adhesive composition containing a polymerization initiator and a proton generator is provided.

  In this polarizing plate, the protective film bonded to at least one surface of the polarizing film via the adhesive layer may be a film made of a cellulose acetate resin. A protective film made of cycloolefin resin is bonded to one side of the polarizing film through the adhesive layer, and a protective film made of cellulose acetate resin is bonded to the other side of the polarizing film through the adhesive layer. And it can also be set as a polarizing plate. A protective film made of a cycloolefin-based resin can be bonded to both surfaces of the polarizing film via the adhesive layer.

In these polarizing plates, the proton generator blended in the adhesive composition may be a compound that generates a proton (H ⁺ ) as it is or by some action, for example, an organic acid that generates an acid as it is, The compound may be an inorganic acid or a compound that generates protons by the action of light or heat. In particular, a compound generally known as a cationic polymerization initiator that generates protons by the action of light or heat is preferred.

  It is preferable that the said adhesive bond layer is hardened | cured by irradiating an active energy ray to the application layer of the said adhesive composition.

  Further, according to the present invention, there is provided a method for producing a polarizing plate by laminating a protective film made of a transparent resin via an adhesive layer on at least one surface of a polarizing film made of a polyvinyl alcohol resin, wherein the polarizing film And an application layer comprising an adhesive composition containing an acrylic curing component, a radical polymerization initiator and a proton generator is formed on at least one bonding surface of the protective film, and the adhesive composition application layer is interposed therebetween. There is also provided a method for producing a polarizing plate, in which the polarizing film and the protective film are bonded together, and then the adhesive composition is cured.

  Furthermore, according to this invention, the laminated optical member which consists of a laminated body of one of the above-mentioned polarizing plates and the optical layer which shows another optical function is also provided. A preferred example of the optical layer constituting this laminated optical member is a retardation plate.

  The polarizing plate of the present invention is either a case where the protective film is a film having a low moisture permeability, such as a film made of a cycloolefin resin, or a film having a high moisture permeability, such as a film made of a cellulose acetate resin. However, the polarizing film and the protective film can be firmly bonded, and the structure of the polarizing plate can be given a degree of freedom. In addition, the adhesive used in the present invention can be applied at room temperature without being dissolved in a diluent such as an organic solvent, and a polarizing plate can be easily produced in the production process.

  Hereinafter, the present invention will be described in detail. The polarizing plate is manufactured by laminating a protective film made of a transparent resin on one or both sides of a polarizing film made of a polyvinyl alcohol resin. Specifically, the polarizing film made of polyvinyl alcohol resin is obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film. And in this invention, the protective film laminated | stacked on the at least single side | surface of the said polarizing film is joined with a polarizing film through a specific adhesive agent.

[Polarized film]
The polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing film. The method for forming a 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, it is about 10-150 micrometers.

  A polarizing film usually has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and a dichroic dye adsorbed. It is manufactured through a step of treating the polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  Uniaxial stretching may be performed before dyeing, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural stages. For the uniaxial stretching, for example, a method of uniaxial stretching between rolls having different peripheral speeds can be employed. Further, it may be a uniaxial stretching method using a heat roll, a dry stretching method such as stretching in the air, or a wet stretching method in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 3 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by dipping in an aqueous solution containing iodine and potassium iodide is usually employed. The iodine content in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the potassium iodide content 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 usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dye solution used for dyeing is usually about 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid treatment after dyeing with the dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, this boric acid-containing aqueous solution preferably further contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The water temperature in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 10 to 120 seconds. After washing with water, a drying process is performed to obtain a polarizing film. The drying process is usually performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually about 60 to 600 seconds, preferably about 120 to 600 seconds.

  In this way, the polyvinyl alcohol 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 to 40 μm. In the present invention, a protective film is laminated on at least one side of this polarizing film, preferably on both sides, to form a polarizing plate. Although the thickness of a protective film is not specifically limited, For example, it is about 20-200 micrometers.

[Protective film]
Although the material of the protective film used for this invention is not specifically limited, Since a target is a polarizing plate used for an optical use, the protective film which consists of resin excellent in transparency is preferable. Examples of the resin constituting the protective film include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, cellulose acetate-based resins such as diacetyl cellulose, triacetyl cellulose, and cellulose acetate propionate, and polyvinylidene chloride. , Polycarbonate, cycloolefin resin, polymethylpentene, polyether ketone, polyether sulfone, polysulfone resin, polyether ketone imide, polyamide, acrylic resin, and the like. In particular, cellulose acetate-based resins and cycloolefin-based resins including triacetyl cellulose are preferable because of excellent transparency and durability.

  In a preferred embodiment, the protective film bonded to at least one surface of the polarizing film can be composed of a film made of a cellulose acetate-based resin. In another suitable form, a protective film made of a cycloolefin-based resin is bonded to one side of the polarizing film, and a protective film made of a cellulose acetate-based resin is bonded to the other side of the polarizing film to form a polarizing plate. You can also. Furthermore, in another suitable form, the protective film which consists of cycloolefin resin can also be bonded on both surfaces of a polarizing film.

  Here, specific examples of cellulose acetate-based resin films, particularly triacetyl cellulose films, are “Fujitack TD80”, “Fujitack TD80UF” and “Fujitack TD80UZ”, Konica Minolta Opt, sold by Fujifilm Corporation. There are "KC8UX2M" and "KC8UY" (both are trade names) sold by Co., Ltd.

  The cycloolefin resin is a heat having a unit derived from a monomer composed of a cyclic olefin (cycloolefin) such as norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene), or a derivative thereof. It is a plastic resin. The cycloolefin-based resin can be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a ring-opening polymer using two or more kinds of cycloolefins, and can also contain cycloolefin and chain olefin or vinyl group. It may be an addition copolymer with an aromatic compound. In addition, a polar group may be introduced.

  Commercially available thermoplastic cycloolefin-based resins include TOPAS ADVANCED POLYMERS GmbH, Germany, and are available from Polyplastics Co., Ltd. “TOPAS”, sold by JSR Co., Ltd. “ARTON” There are “ZEONOR” and “ZEONEX” sold by Nippon Zeon Co., Ltd., “APEL” sold by Mitsui Chemicals, Inc. (all are trade names). Such a cycloolefin-based resin is formed into a film, and a known method such as a solvent casting method or a melt extrusion method is appropriately used for forming the film.

  These thermoplastic cycloolefin resin films can be stretched to give a phase difference, and a cycloolefin resin film having such a phase difference can also be used as a protective film / retardation plate. Cycloolefin resin films with a phase difference are also commercially available. For example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Zeonor” sold by Nippon Zeon Co., Ltd. There are “Film” and “Arton Film” sold by JSR Corporation (both are trade names).

  These thermoplastic cycloolefin resin films are preferably subjected to a surface activation treatment before applying the adhesive. The surface activation treatment here is a treatment for activating the surface of the resin, and examples thereof include a non-contact type corona discharge treatment, a plasma treatment, an ozone treatment, an ultraviolet irradiation treatment, and an organometallic compound. The flame treatment which blows the flame of gas etc. can be mentioned. These are all known treatments for activating the resin surface. Among these, corona discharge treatment is preferable because it is easy to handle and has a large surface activation effect.

  The corona discharge treatment is a treatment for generating a corona discharge by applying a high voltage to an electrode and activating a resin film disposed on the discharge surface. In the corona discharge treatment, the best result may be obtained by changing the type of electrode, the distance between the electrode and the film, the voltage to be applied, the moving speed of the film to be treated, the output of the corona discharge, and the like. For example, the output of the corona discharge can be applied up to about 2 kW, but is preferably 1 kW or less from the viewpoint of safety, and in order to eliminate the possibility of deterioration or coloring of the protective film as much as possible. Is particularly preferably 600 W or less. The moving speed of the film is preferably set to about 3 to 50 m / min. Further, in order to uniformly treat the film surface with corona discharge, the film to be treated may be passed through the corona discharge region a plurality of times and treated.

  When the surface activation treatment is performed on the protective film in this manner, the activation treatment surface is bonded to the polarizing film via an adhesive to produce a polarizing plate.

[adhesive]
In the present invention, a composition containing an acrylic curing component, a radical polymerization initiator, and a proton generator is used as the adhesive. Here, the acrylic curing component is a compound having an acryloyl group or methacryloyl group which is a radical reactive functional group in the molecule, and a monofunctional (meth) having one acryloyl group or methacryloyl group in one molecule. There are acryloyl compounds, bifunctional (meth) acryloyl compounds having two acryloyl groups or methacryloyl groups in one molecule, and polyfunctional (meth) acryloyl compounds having three or more acryloyl groups or methacryloyl groups in one molecule. Among these, it is preferable to blend at least one bifunctional or polyfunctional (meth) acryloyl compound having at least two acryloyl groups or methacryloyl groups in the molecule. (Meth) acrylate monomers in which (meth) acryloyl groups are present in the form of (meth) acrylic acid esters are common, but (meth) acrylamide monomers in the form of (meth) acryloylamino groups are also acrylic cured. Can be an ingredient. Below, the typical compound which can become an acrylic hardening component is illustrated.

  Specific examples of monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. 2-hydroxy-3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, Benzyl (meth) acrylate, isobornyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) Examples thereof include acrylate, ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, and phenoxypolyethylene glycol (meth) acrylate. Other carboxyl group-containing monofunctional (meth) acrylate monomers include 1- [2- (meth) acryloyloxyethyl] phthalic acid, 1- [2- (meth) acryloyloxyethyl] hexahydrophthalic acid, 2-carboxy Examples also include ethyl (meth) acrylate, 1- [2- (meth) acryloyloxyethyl] succinic acid, 4- [2- (meth) acryloyloxyethyl] trimellitic acid, and the like. The monofunctional (meth) acryloyl compound also includes a (meth) acryloylamino group-containing monomer such as 4- (meth) acryloylamino-1-carboxymethylpiperidine.

  Bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) acrylates, aliphatic polyol di (meth) acrylates Di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylates of dioxane glycol or dioxane dialkanol, di (meth) of alkylene oxide adducts of bisphenol A or bisphenol F Representative examples include acrylates, epoxy di (meth) acrylates of bisphenol A or bisphenol F, and the like. Specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexane. Diol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditrimethylolpropane di ( (Meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol Distearate (meth) acrylate, polypropylene glycol di (meth) acrylate, and polytetramethylene glycol di (meth) acrylate. In addition, silicone di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2-bis [4- {2- (2- (meth) acryloyloxyethoxy) ethoxy} phenyl] propane, 2,2-bis [4- {2- (2- (meth) acryloyloxyethoxy) ethoxy} cyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], an acetal compound of hydroxypivalaldehyde and trimethylolpropane [chemical name: 2- (2-hydroxy -1,1-dimethylethyl) -5-ethyl Di (meth) acrylate of 5-hydroxymethyl-1,3-dioxane], also including di (meth) acrylate of tris (hydroxyethyl) isocyanurate, can be a difunctional (meth) acrylate monomer.

  The trifunctional or higher polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol. Trivalent or higher aliphatic polyols such as tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Poly (meth) acrylate is representative. In addition, tri (meth) acrylate of alkylene oxide adduct of glycerin, tri (meth) acrylate of alkylene oxide adduct of trimethylolpropane, 1,1,1-tris [2- {2- (meth) acryloyloxyethoxy} Ethoxy] propane, tris (hydroxyethyl) isocyanurate tri (meth) acrylate, and the like can also be polyfunctional (meth) acrylate monomers.

  In addition, oligomers such as epoxy (meth) acrylate and urethane (meth) acrylate can be an acrylic curing component. When these oligomers are used, the curing shrinkage of the adhesive layer generated during the curing reaction is suppressed. As a result, the generation of internal stress accompanying cure shrinkage of the adhesive layer is suppressed, and the decrease in adhesive strength is reduced.

  Epoxy (meth) acrylate can be produced by addition reaction of polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloyloxy groups in the molecule. Examples of the polyglycidyl ether used for the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

  Urethane (meth) acrylate is a compound having a urethane bond (—NHCOO—) and at least two (meth) acryloyloxy groups in the molecule. Specifically, a urethanization reaction product of a hydroxyl group-containing (meth) acrylate monomer and a polyisocyanate each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule, and a polyol Urethane reaction product of terminal isocyanate group-containing urethane compound obtained by reaction with isocyanate and (meth) acrylate monomer each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule, etc. It can be.

  Examples of the hydroxyl group-containing (meth) acrylate monomer used in the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3- Examples include phenoxypropyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate.

  Examples of the polyisocyanate used for the urethanization reaction with the hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and aromatics among these diisocyanates. Diisocyanates obtained by hydrogenating the above isocyanates (for example, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, Examples thereof include polyisocyanates obtained by increasing the amount of diisocyanate.

  In addition, as polyols used to form terminal isocyanate group-containing urethane compounds by reaction with polyisocyanates, polyester polyols, polyether polyols, etc., as well as aromatic, aliphatic and alicyclic polyols should be used. Can do. Aliphatic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditrimethylol propane, penta Examples include erythritol, dipentaerythritol, dimethylol heptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin and the like. Examples of alicyclic polyols include hydrogenated bisphenol A.

  The polyester polyol is obtained by a dehydration condensation reaction between the above polyols and a polybasic carboxylic acid or an anhydride thereof. The polybasic carboxylic acid or its anhydride includes (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) Examples include phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydride) phthalic acid, and the like.

  The polyether polyol may be a polyoxyalkylene-modified polyol obtained by a reaction of the above-described polyols or dihydroxybenzenes with an alkylene oxide, in addition to the polyalkylene glycol.

  Polyester (meth) acrylate can also be an acrylic curing component. The polyester (meth) acrylate is a compound having an ester bond and at least two (meth) acryloyloxy groups in the molecule. Specifically, it can be obtained by a dehydration condensation reaction using (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Examples of polybasic carboxylic acids or anhydrides used in the dehydration condensation reaction include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, and (anhydrous) pyrone. Examples include merit acid, hexahydro (anhydride) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, and terephthalic acid. Examples of the polyol used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  As commercial products of urethane (meth) acrylate, the trade names are “UV-6100B” and “UV-7600B” (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), “Beam Set 502H” and “Beam Set 575”. "[Above, manufactured by Arakawa Chemical Co., Ltd.]", "EBECRYL 230", and "EBECRYL 8411" [above, manufactured by Daicel-Cytec Co., Ltd.].

  The radical curable acrylic curing components described above can be easily obtained as commercially available adhesives. For example, the “World Lock XVL” series and the “World Lock 8000” are trade names. "Series [above, manufactured by Kyoritsu Chemical Industry Co., Ltd.]", "ThreeBond 3013" and "ThreeBond 3017" (above, manufactured by ThreeBond Co., Ltd.), "Aronix UV-3300" (made by Toagosei Co., Ltd.) Can be mentioned. These commercially available products often contain a radical polymerization initiator described later. In this case, the commercially available product can be used as a mixture of an acrylic curing component and a radical polymerization initiator.

  The radical polymerization initiator blended in the adhesive composition used in the present invention is a compound that generates radicals by the action of heat, ultraviolet rays, etc., and can initiate polymerization of a radical polymerizable compound such as a (meth) acrylic compound. Anything is acceptable. As radical polymerization initiators, compounds such as acetophenone, benzophenone, benzoin ether, and thioxanthone are known. Specific examples include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio ) Phenyl] -2-morpholinopropan-1-one, acetophenone-based initiators such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone, 4,4′- Benzophenone initiators such as diaminobenzophenone; benzoin ether initiators such as benzoinpropyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; others, xanthone, fluorenone, camphorquino , Benzaldehyde, there is such as anthraquinone.

  Examples of commercially available radical polymerization initiators include “Irgacure 184”, “Irgacure 907” and “Darocur 1173” (above, manufactured by Ciba), “Lucirine TPO” (produced by BASF). )and so on.

  A radical polymerization initiator may be used individually, respectively, and 2 or more types may be mixed and used for it. A radical polymerization initiator is normally mix | blended in the ratio of 0.5-20 weight part with respect to 100 weight part of acrylic hardening components, Preferably it is 1-10 weight part, More preferably, it is 3-5 weight part.

  Next, the proton generator compounded in the adhesive composition used in the present invention generates an organic acid or inorganic acid that generates protons only by mixing with the adhesive, or generates protons by the action of heat or ultraviolet rays. It can be a compound. Examples of the organic acid include p-toluenesulfonic acid, methanesulfonic acid, acetic acid, trifluoroacetic acid, and the like, and examples of the inorganic acid include boric acid, hydrogen halide, nitric acid, and the like.

  A compound that generates an acid by the action of heat or ultraviolet rays is generally known as a cationic polymerization initiator, and is an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt; an iron-allene complex There are compounds such as

Examples of the aromatic diazonium salt include the following compounds.
Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Benzenediazonium hexafluoroborate, etc.

Examples of the aromatic iodonium salt include the following compounds.
Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Di (4-nonylphenyl) iodonium hexafluorophosphate and the like.

Examples of the aromatic sulfonium salt include the following compounds.
Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
4,4'-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Moreover, as an iron-allene complex, the following compounds are mentioned, for example.
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

  Among these, aromatic sulfonium salts, in particular, have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus provide a cured product having excellent curability and good mechanical strength and good adhesion to a polarizing film. Therefore, it is preferably used.

These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Irgacure 250” (manufactured by Ciba), “CPI-100P” and “CPI-101A” [ "San Apro Co., Ltd.", "UVA CURE 1590" (Daicel Cytec Co., Ltd.), "CYRACURE UVI-6992" (Dow Chemicals Co., Ltd.), "Sun Aid SI-60L" and "Sun Aid SI-80 “[Sanshin Chemical Industry Co., Ltd.],“ Kayarad PCI-220 ”and“ Kayarad PCI-620 ”(Nippon Kayaku Co., Ltd.),“ UVI-6990 ”(Union Carbide) "Adekaoptomer SP-150", "Adekaoptomer SP-152", "Adekaoptomer SP-170" and "Adekaoptomer SP-172" [above, manufactured by ADEKA Corporation], "CI-5102 "," CIT-1370 "," CIT-1682 "," CIP-1866S "," CIP-2048S "and" CIP-2064S " [Made by Soda Co., Ltd.], “DPI-101”, “DPI-102”, “DPI-103”, “DPI-105”,
“MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI-103”, “BBI-105”,
“TPS-101”, “TPS-102”, “TPS-103”, “TPS-105”, “MDS-103”, “MDS-105”,
“DTS-102” and “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia) and the like.

  From the viewpoint of storage stability of the adhesive, it is preferable to use a compound that generates an acid by the action of heat, ultraviolet rays or the like as a proton generator. Further, it is known as a photocationic polymerization initiator because of easy handling and availability. "Adekaoptomer SP-152", "Adekaoptomer SP-172", "Irgacure 250", "CPI-100P", "CPI-101A", "UVA CURE 1590", "CYRACURE UVI-6992", etc. Are preferably used.

  These proton generators may be used alone or in combination of two or more. The proton generator is blended in a proportion of about 0.05 to 30 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 100 parts by weight of the acrylic curing component in accordance with its solubility. Is a ratio of 0.25 to 3 parts by weight.

  The adhesive used in the present invention includes, in addition to the above acrylic curing component, radical polymerization initiator and proton generator, a resin having no acryloyl group or methacryloyl group in the molecule, reactive diluent, photosensitization. Ordinary additives used for adhesives such as an agent, a silane coupling agent, a leveling agent, and an antioxidant can be further contained.

  Resin that does not have an acryloyl group or methacryloyl group in the molecule is added to the resin mainly for the purpose of alleviating internal stress generated by the acrylic curing component during curing shrinkage. Not what you want. For example, an epoxy resin, a urethane resin, an acrylic ester polymer, a copolymer mainly composed of an acrylic ester, and the like, and a rubber-like elastic body is particularly preferable. These resins having no acryloyl group or methacryloyl group in the molecule may be used alone or in admixture of two or more. When blending a resin having no acryloyl group or methacryloyl group in the molecule, the amount is 1 to 200 parts by weight, preferably 3 to 100 parts by weight, based on 100 parts by weight of the acrylic curing component.

  The reactive diluent is used to easily wet the adhesive composition to the substrate, and has the effect of reducing the viscosity of the adhesive composition by its addition. The reactive diluent is not particularly limited as long as it reacts with the polymerization initiator and does not adversely affect the adhesiveness. Specific examples include oxetane compounds and epoxy compounds that react with a polymerization initiator, although they are different from acrylic curing components.

  The oxetane compound used as the reactive diluent is a compound having a 4-membered ring ether in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl). ) Methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolak Oxetane and the like. These oxetane compounds can be easily obtained as commercial products. As examples of commercially available products, all of them are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT- 211 ”,“ Aron Oxetane OXT-221 ”,“ Aron Oxetane OXT-212 ”(all manufactured by Toagosei Co., Ltd.), and the like.

  Epoxy compounds used as reactive diluents include aromatic epoxy compounds, hydrogenated epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, and the like.

  Examples of aromatic epoxy compounds include bisphenol-type epoxy compounds such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde phenol novolak Examples thereof include novolak-type epoxy resins such as epoxy resins; glycidyl ethers of tetrahydroxydiphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  The hydrogenated epoxy compound selectively hydrogenates an aromatic polyhydroxy compound having at least two phenolic hydroxyl groups in the molecule, which is a raw material of the aromatic epoxy compound, in the presence of a catalyst under pressure. The hydrogenated polyhydroxy compound obtained by glycidyl ether is obtained, and a typical example is diglycidyl ether of hydrogenated bisphenol A. Examples of commercially available products corresponding to hydrogenated epoxy compounds include “JER 827” and “JER YX8000” (both manufactured by Japan Epoxy Resins Co., Ltd.).

  The aliphatic epoxy compound can be an aliphatic polyhydric alcohol or a polyglycidyl ether of an alkylene oxide adduct thereof. Specifically, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol Polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide, propylene oxide, etc.) to aliphatic polyhydric alcohols such as diglycidyl ether, ethylene glycol, propylene glycol and glycerin Examples thereof include glycidyl ether. As commercially available products corresponding to this, “Denacol EX-212”, “Denacol EX-211” (both manufactured by Nagase ChemteX Corporation) and the like can be mentioned.

  The alicyclic epoxy compound is a compound having in the molecule at least one epoxy group (—O—) bonded to the alicyclic ring as shown in the following formula, wherein m is an integer of 2 to 5. To express.

A compound in which one or more hydrogen atoms in (CH ₂ ) _m in the above formula are removed and bonded to another chemical structure can be an alicyclic epoxy compound. Further, the hydrogen forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among these, compounds having an epoxycyclopentane ring (m = 3 in the above formula) and an epoxycyclohexane ring (m = 4 in the above formula) are preferable. Specific examples of the alicyclic epoxy compound include the following.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
Ethylene bis (3,4-epoxycyclohexanecarboxylate),
Bis (3,4-epoxycyclohexylmethyl) adipate,
Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
Diethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
Ethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro- [5.2.2.5.2.2] henicosane (also 3,4-epoxycyclohexanespiro-2 ' , 6′-Dioxanespiro-3 ″, 5 ″ -Dioxanespiro-3 ′ ″, 4 ′ ″-epoxycyclohexane)
4- (3,4-epoxycyclohexyl) -2,6-dioxa-8,9-epoxyspiro [5.5] undecane,
4-vinylcyclohexene dioxide,
1,2: 8,9-diepoxy limonene,
Bis-2,3-epoxycyclopentyl ether,
Dicyclopentadiene dioxide etc.

  Among these, preferable alicyclic epoxy compounds include 1,2: 8,9-diepoxy limonene because of its low viscosity and high dilution effect. This compound is sold by Daicel Chemical Industries, Ltd. under the trade name “Celoxide 3000”.

  These reactive diluents may be used alone or in admixture of two or more. When mix | blending a reactive diluent, the quantity is 1-100 weight part with respect to 100 weight part of acrylic hardening components, Preferably it is 3-50 weight part.

  The photosensitizer is a compound having absorption in a long wavelength region of 400 nm or more of ultraviolet rays, excited by the long wavelength ultraviolet light, and efficiently transmitting energy to the photocationic polymerization initiator. Therefore, when using a photocationic polymerization initiator as a proton generator, it is effective to mix such a photosensitizer. Since the cationic photopolymerization initiator reacts with ultraviolet rays on the relatively short wavelength side, when the ultraviolet rays are in a relatively long wavelength region, the polymerization initiating effect becomes insufficient unless a photosensitizer is added. As a typical compound corresponding to the photosensitizer, 9,10-dibutoxyanthracene can be mentioned. Examples of commercially available products corresponding to photosensitizers include “Anthracure UVS-1331” (manufactured by Kawasaki Kasei Co., Ltd.) under the trade name. Such a photosensitizer may be used independently and may be used in mixture of 2 or more types. When the photosensitizer is blended, the amount is usually 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.5 to 100 parts by weight of the acrylic curing component. ~ 3 parts by weight.

  A silane coupling agent is an organosilicon compound that has both a reactive functional group and a hydrolyzable group, and does not adversely affect the adhesion to the adherend and has a low viscosity. It also has the function. Typical compounds corresponding to this include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and the like. As commercial products of silane coupling agents, the trade names “KBM-303” and “KBM-403” (manufactured by Shin-Etsu Chemical Co., Ltd.), “A-186” and “A-1310” [Above, manufactured by Nippon Unicar Co., Ltd.], “TSL8172” and “TSL8173” [above, manufactured by GE Toshiba Silicone Co., Ltd.]. These silane coupling agents may be used alone or in combination of two or more. When mix | blending a silane coupling agent, the quantity is 0.1-20 weight part normally with respect to 100 weight part of acrylic hardening components, Preferably it is 0.3-10 weight part.

  A leveling agent adjusts the wettability with respect to the film base material of an adhesive agent. Depending on the base material, the adhesive may not wet enough on the film immediately after coating, and the adhesive may repel on the surface of the film, creating parts that are wet with the adhesive and parts that are not wet. There is an action to prevent such a phenomenon. A typical compound corresponding to this is organically modified polysiloxane. The organically modified polysiloxane has a silicone skeleton and an organically modified part, and has a function of lowering the surface tension of the resin surface after coating. In addition, there is a fluorine-based leveling agent that is an oligomer having a hydrophilic group and a lipophilic group together with a perfluoroalkyl group. As for the commercial products of leveling agents, the trade names are “SH 200-100cs” and “ST86PA” (above, manufactured by Toray Dow Corning Co., Ltd.), “BYK-354” and “BYK-361N” (above. , Manufactured by Big Chemie). These leveling agents may be used alone or in admixture of two or more. When a leveling agent is blended, the amount is 0.05 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the acrylic curing component.

  The antioxidant is a compound having an antioxidant ability, and typical examples of the compound include 3,5-di-tert-butyl-4-hydroxytoluene, 2- or 3-tert-butyl-4. -Hydroxyanisole etc. are mentioned. These antioxidants may be used alone or in combination of two or more. When mix | blending antioxidant, the quantity is 0.05-10 weight part with respect to 100 weight part of acrylic hardening components, Preferably it is 0.1-5 weight part.

  Each component demonstrated above is mixed and an adhesive composition is prepared, the adhesive composition is apply | coated to at least one bonding surface of a polarizing film and a protective film, and an adhesive bond layer is formed. The polarizing film and the protective film are bonded via this adhesive layer, and the adhesive layer is cured, and this curing is advantageously performed by irradiation with active energy rays, particularly ultraviolet rays. The thickness of the adhesive layer is usually 50 μm or less after curing, preferably 20 μm or less, and more preferably 10 μm or less. If the adhesive layer becomes too thick, a large amount of energy is required for curing by irradiation with active energy rays, which is not practical.

  When the viscosity of the adhesive composition containing a proton generator is high and it is difficult to make the thickness of the adhesive layer 50 μm or less, a solvent is mixed in the adhesive composition to adjust the viscosity. In that case, a drying step is required, and therefore it is preferable not to use a solvent if possible.

[Production method of polarizing plate]
In the present invention, on the bonding surface of at least one of the polarizing film and the protective film, an application layer of the adhesive composition containing the acrylic curing component, the radical polymerization initiator and the proton generator described above is formed, A polarizing plate is manufactured by laminating a polarizing film and a protective film through the adhesive composition coating layer and then curing the adhesive composition. The coating method of the adhesive composition is not particularly limited, and the coating film thickness can be increased by using a method of dripping or casting the adhesive composition or using any coating equipment such as a die coater, a gravure coater, a bar coater, or a wire bar. A method of applying while controlling can be adopted.

  After bonding a polarizing film and a protective film through an uncured adhesive composition, the adhesive composition is cured and the protective film is fixed on the polarizing film. As described above, this curing is advantageously performed by irradiation with active energy rays.

The light source used for the irradiation of the active energy ray is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp. A metal halide lamp or the like can be used. The light irradiation intensity to the radical curable adhesive is determined for each target composition and is not particularly limited. However, the irradiation intensity in the wavelength region of 320 to 390 nm effective for activation of the initiator is used. Is preferably 10 to 1,000 mW / cm ² . If the light irradiation intensity is less than 10 mW / cm ² , the reaction time becomes too long, and if it exceeds 1,000 mW / cm ² , the heat of the lamp and the heat generated during polymerization of the adhesive cause It may cause yellowing and deterioration of the polarizing film. The light irradiation time to the adhesive layer is controlled for each adhesive to be cured and is not particularly limited. However, the integrated light amount expressed as the product of irradiation intensity and irradiation time is 100 to 5,000 mJ / It is preferably set to be cm ² . If the integrated light intensity is less than 100 mJ / cm ² , the active species derived from the initiator may not be sufficiently generated, and the resulting protective film may be insufficiently cured. However, the irradiation time becomes very long, which is disadvantageous for improving productivity.

  When a proton generator that generates an acid by heat is blended, it may be heated after irradiation with active energy rays, and such heating is usually performed at a temperature of about 50 to 100 ° C.

  In curing the adhesive composition described above, it is preferable to cure the adhesive composition within a range in which various functions of the polarizing plate such as the degree of polarization, transmittance and hue of the polarizing film, and transparency of the protective film do not deteriorate.

[Laminated optical member]
When using a polarizing plate, it can also be set as the laminated optical member which provided the optical layer which shows optical functions other than a polarizing function through a protective film layer. The optical layer laminated on the polarizing plate for the purpose of forming an optical member includes, for example, a liquid crystal display device such as a reflective layer, a transflective reflective layer, a light diffusing layer, a retardation plate, a light collector, and a brightness enhancement film. There are some that are used. The reflective layer, transflective reflective layer, and light diffusing layer are used when forming an optical member comprising a reflective or transflective type, diffusive type, or a polarizing plate of both types. The optical layer laminated on the polarizing plate particularly preferably includes a retardation plate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The materials used in the examples and comparative examples are as follows, and the names enclosed in “” are trade names.

(A) Base component of adhesive (acrylic curing component + radical polymerization initiator)
“World Rock No. 8838”: As an acrylic curing component, it contains 35 to 45% of monofunctional (meth) acrylate and 45 to 55% of modified acrylate oligomer such as epoxy (meth) acrylate, and further radical polymerization. Although the adhesive contains an initiator and a stabilizer in a proportion of 5% or less, the detailed composition is not disclosed by the manufacturer. Liquid, obtained from Kyoritsu Chemical Industry Co., Ltd.

(B) Proton generator (cationic polymerization initiator)
“Adekaoptomer SP-152”: a triphenylsulfonium salt-based cationic polymerization initiator, obtained from ADEKA Corporation. In Table 1, it is abbreviated as “SP-152”.
“Irgacure 250”: a cationic polymerization initiator based on diphenyliodonium salt, having a weight ratio of (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate and solvent propylene carbonate of 3: 1. Mixture, obtained from Ciba Japan. In Table 1, it is abbreviated as “Irg 250”.

(C) Other additives “4HBAGE”: 4-hydroxybutyl acrylate glycidyl ether, obtained from Nippon Kasei Co., Ltd.
“KBM-303”: 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, obtained from Shin-Etsu Chemical Co., Ltd.

[Reference Example] Production of Polarizing Film A polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm is uniaxially stretched about 5 times in a dry process to maintain a tension state. The sample was immersed in pure water at 60 ° C. for 1 minute, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to prepare a polarizing film in which iodine was adsorbed and oriented on the polyvinyl alcohol film.

[Example 1]
In this example, a polarizing plate having a configuration of triacetyl cellulose film / polarizing film / cycloolefin resin film was produced.

(A) Surface Treatment of Protective Film “ZEONOR FILM” (trade name) which is a cycloolefin (norbornene) resin film obtained from Nippon Zeon Co., Ltd. was used as one protective film of the polarizing plate. This cycloolefin-based resin film was passed through a corona treatment device “CT-212” manufactured by Kasuga Denki Co., Ltd., subjected to corona discharge treatment on one side, and used for bonding to a polarizing film. The corona discharge treatment was performed under the conditions of a corona output intensity of 840 W and a conveyor moving speed of 10 m / min.

  In addition, “KC8UX2M”, which is a triacetyl cellulose film obtained from Konica Minolta Opto Co., Ltd., was used as the other protective film of the polarizing plate. This triacetyl cellulose film was subjected to saponification treatment and used for pasting to a polarizing film.

(B) Preparation of Adhesive Composition To 100 parts of the above-mentioned adhesive base component “World Rock No. 8838”, 0.5 parts of the above cationic polymerization initiator “Adekaoptomer SP-152” was added. An adhesive composition was prepared.

(C) Bonding of protective film and polarizing film The corona-treated surface of the cycloolefin-based resin film shown in (a) above, and the saponification-treated surface of the triacetyl cellulose film shown in (a) above, respectively. The adhesive composition prepared in (b) was applied. And the adhesive composition application surface of the cycloolefin resin film on one side of the polyvinyl alcohol polarizing film prepared in the previous reference example, the adhesive composition application surface of the triacetyl cellulose film on the other side of the polarizing film, They were pasted together.

(D) Adhesion of protective film and polarizing film
Using a UV irradiation device manufactured by Fusion (the lamp uses “D bulb” manufactured by the same company), the cycloolefin resin film / uncured adhesive layer / polarizing film / uncured adhesive layer obtained in (c) above. / A laminated film composed of a triacetyl cellulose film is irradiated with ultraviolet rays from the cycloolefin resin film side under the conditions of an illuminance of 250 mW / cm ² and an integrated light quantity of 3,000 mJ / cm ² , and the polarizing film and both surfaces A protective film was adhered to produce a polarizing plate. The illuminance and integrated light intensity were measured at about 320 to 390 nm, which is the wavelength region of ultraviolet rays, using “UV Power Puck” manufactured by Electronic Instrumentation and Technology, Inc.

(E) Evaluation of adhesiveness The protective film of the obtained polarizing plate and the polarizing film were peeled off with fingers to observe the degree of material destruction, and the adhesiveness was evaluated in the following three stages. In the polarizing plate obtained in this example, material destruction occurred both between the polarizing film and the cycloolefin-based resin film and between the polarizing film and the triacetyl cellulose film.

(Adhesion evaluation criteria)
○: Material destruction occurs.
(Triangle | delta): Although material destruction is carried out, it peels partially between a protective film and a polarizing film.
X: It peels between a protective film and a polarizing film.

(F) Evaluation of water resistance The polarizing plate obtained in the above (d) is immersed in warm water at 60 ° C. for 4 hours, and the erosion length (unit: μm) by warm water from the end of the sample (determined by the decoloring region of the polarizing film) ) Was measured with a magnifying glass. As a result, the erosion length was 1,075 μm.

[Examples 2 and 3]
The same base component “World Rock No. 8838” as in Example 1 was used, and the proton generator shown in Table 1 and other additives were blended in the amounts shown in Table 1 to prepare an adhesive composition. Prepared. A polarizing plate was produced in the same manner as in Example 1 except that this adhesive composition was used. Note that “Irgacure 250” used in Example 3 contains 25% of propylene carbonate as a solvent as described above, but the amounts shown in Table 1 are values including the solvent. Each polarizing plate was evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the same base component “World Rock No. 8838” as in Example 1 was used as the adhesive. About the obtained polarizing plate, it evaluated by the method similar to Example 1, and the result was put together in Table 1. FIG.

  As can be seen from the results in Table 1, the adhesive (adhesiveness) between the polarizing film and the protective film and water resistance can be obtained by adding a proton generator to an adhesive in which a radical polymerization initiator is blended with an acrylic curing component. Can be improved.

Claims (9)

A polarizing plate in which a protective film made of a transparent resin is bonded to at least one surface of a polarizing film made of a polyvinyl alcohol-based resin via an adhesive layer,
The polarizing plate, wherein the adhesive layer is a cured product of an adhesive composition containing an acrylic curing component, a radical polymerization initiator, and a proton generator.   The polarizing plate according to claim 1, wherein the protective film bonded to at least one surface of the polarizing film via the adhesive layer is a film made of a cellulose acetate-based resin.   A protective film made of a cycloolefin-based resin is bonded to one side of the polarizing film via the adhesive layer, and a protective film made of a cellulose acetate-based resin is bonded to the other surface via the adhesive layer. The polarizing plate according to claim 1.   The polarizing plate according to claim 1, wherein protective films made of a cycloolefin resin are bonded to both surfaces of the polarizing film via the adhesive layer.   The polarizing plate according to claim 1, wherein the proton generator is a cationic polymerization initiator.   The polarizing plate according to claim 1, wherein the adhesive layer is cured by irradiating the coating layer of the adhesive composition with active energy rays. A method of manufacturing a polarizing plate by laminating a protective film made of a transparent resin via an adhesive layer on at least one surface of a polarizing film made of a polyvinyl alcohol-based resin,
On the bonding surface of at least one of the polarizing film and the protective film, an application layer made of an adhesive composition containing an acrylic curing component, a radical polymerization initiator and a proton generator is formed, and the adhesive composition is applied. A method for producing a polarizing plate, comprising: laminating the polarizing film and the protective film through a layer, and then curing the adhesive composition.   A laminated optical member comprising a laminate of the polarizing plate according to claim 1 and an optical layer having another optical function.   The laminated optical member according to claim 8, wherein the optical layer is a retardation plate.