JP2009086452A - Method for manufacturing adhesive optical film, adhesive optical film and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive optical film including an adhesive layer laminated on at least one side of an optical film, which is reduced in curling and improved in adhesion without retention of adhesive or crack of adhesive. <P>SOLUTION: In the method for manufacturing an adhesive optical film including a step of laminating an adhesive layer on at least one side of an optical film, the laminating step is performed by performing surface activation treatment to a surface of the optical film and a surface of the adhesive layer to which the laminating step is performed, and then mutually laminating the surface of the optical film and the surface of the adhesive layer which are subjected to the surface activation treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive optical film having a step of laminating a pressure-sensitive adhesive layer on at least one surface of an optical film and a method for producing the same. The present invention also relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the adhesive optical film. Examples of the optical film include a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, and a laminate of these.

  In addition, the present invention improves the adhesion between the optical film and the pressure-sensitive adhesive layer in the pressure-sensitive adhesive optical film obtained by laminating the pressure-sensitive adhesive layer on at least one surface of the optical film. The present invention relates to a method for suppressing curling of an adhesive optical film.

  In liquid crystal displays, it is indispensable to place polarizing elements on both sides of the glass substrate that forms the outermost surface of the liquid crystal panel due to its image forming method. Generally, a transparent protective film is attached to one or both sides of a polarizer. A combined polarizing plate is attached to the outermost surface of the liquid crystal panel. In addition to the polarizing plate, various optical elements have been used on the outermost surface of the liquid crystal panel in order to improve the display quality of the display. For example, a retardation film for preventing coloring, a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for increasing the contrast of the display are used. These films are collectively called optical films.

  When sticking the optical film on the outermost surface of the liquid crystal panel, an adhesive is usually used. In addition, since the optical film can be instantly fixed to the outermost surface of the liquid crystal panel and has a merit that a drying process is not required to fix the optical film, the adhesive is preliminarily applied to one side of the optical film. It is provided as a layer. That is, an adhesive optical film is generally used for attaching the optical film to the outermost surface of the liquid crystal panel.

  Necessary characteristics required for the pressure-sensitive adhesive are as follows: (1) When an optical film is bonded to the outermost surface of the liquid crystal panel, the optical film is also used in the case where the bonding position is wrong or a foreign object is caught in the bonding surface. The film can be peeled off from the outermost surface of the liquid crystal panel, and can be bonded again (rework). (2) It has stress relaxation properties to prevent optical unevenness caused by dimensional change of the optical film. (3) Environmental promotion For example, there is no problem caused by the pressure-sensitive adhesive with respect to a durability test such as heating and humidification that is usually performed as a test.

  In particular, with regard to the reworkability of (1) above, in the conventional adhesive optical film, since the adhesiveness between the adhesive layer and the optical film substrate is low, when peeling the adhesive optical film from the liquid crystal panel, There has been a problem that a part of the pressure-sensitive adhesive of the pressure-sensitive optical film remains on the surface of the liquid crystal panel (hereinafter referred to as pressure-sensitive adhesive residue).

  In addition, the display frame using a liquid crystal panel has recently become narrower and display quality may be significantly deteriorated due to defects occurring at the edge of the liquid crystal panel. Became. There are various defects at the end of the optical film, but the most common is a problem that the adhesive is missing at the end (hereinafter referred to as adhesive lack). This occurs when the end of the optical film hits an object during handling of the optical film and a part of the pressure-sensitive adhesive layer is missing. Many of these problems occur in conventional adhesive optical films.

  As a method for improving the adhesion between the optical film and the pressure-sensitive adhesive layer, a method of subjecting the surface of the optical film on which the pressure-sensitive adhesive layer is formed to surface activation treatment such as corona treatment or plasma treatment has been proposed (Patent Literature). 1, 2). In any of these methods, the surface of the pressure-sensitive adhesive layer is surface-activated so that the pressure-sensitive adhesive layer and the optical film are more strongly adhered. However, when these surface activation treatments are applied to the pressure-sensitive adhesive layer, the resulting pressure-sensitive adhesive optical film tends to be curled. Further, in many cases, the adhesiveness cannot be sufficiently improved depending on the material of the optical film only by performing the surface activation treatment on the pressure-sensitive adhesive layer.

JP-A-7-174918 Japanese Unexamined Patent Publication No. 64-81827

  The present invention is an adhesive optical film in which an adhesive layer is laminated on at least one surface of an optical film, curling is suppressed, adhesiveness is good, adhesive remains, and adhesive does not lack. An object of the present invention is to provide a mold optical film and a manufacturing method thereof.

  Another object of the present invention is to provide an image display device using the adhesive optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found the following method for producing an adhesive optical film and completed the present invention.

That is, the present invention is a method for producing an adhesive optical film having a step of laminating an adhesive layer on at least one side of an optical film,
In the laminating step, the surface of the optical film on which the laminating step is performed and the surface of the pressure-sensitive adhesive layer are subjected to surface activation treatment, and then the surface of the surface-treated optical film and the surface of the pressure-sensitive adhesive layer are laminated. It is related with the manufacturing method of the adhesive optical film characterized by performing by this.

  In the method for producing an adhesive optical film, the surface activation treatment is preferably at least one treatment selected from plasma treatment, corona discharge treatment, ultraviolet treatment, electron beam treatment and ozone treatment.

  In the method for producing an adhesive optical film, the surface activation treatment is a plasma treatment, and the plasma treatment is performed in at least one gas selected from nitrogen gas, oxygen gas, ammonia gas, argon gas, and helium gas. It is preferable to carry out with. Further, the surface activation treatment of the surface of the optical film and the surface of the pressure-sensitive adhesive layer is performed by plasma treatment, and the plasma treatment of at least one surface of the surface of the optical film and the surface of the pressure-sensitive adhesive layer is performed. It is preferable to carry out in a gas containing oxygen gas.

  Moreover, this invention relates to the adhesive optical film obtained by the said manufacturing method.

  The present invention also relates to an image display device using at least one adhesive optical film. One or a plurality of adhesive optical films of the present invention are used in combination according to various usage modes of an image display device such as a liquid crystal display device.

In the present invention, when producing an adhesive optical film by laminating an adhesive layer on at least one side of an optical film,
After performing surface activation treatment on the surface of the optical film and the surface of the pressure-sensitive adhesive layer on which the lamination is performed, by laminating the surface of the optical film subjected to the surface activation treatment and the surface of the pressure-sensitive adhesive layer, The present invention relates to a method for improving the adhesion between an optical film and a pressure-sensitive adhesive layer in the obtained pressure-sensitive adhesive optical film and suppressing curling of the pressure-sensitive adhesive optical film.

  In the production method of the pressure-sensitive adhesive optical film of the present invention, the surface of the optical film and the surface of the pressure-sensitive adhesive layer are bonded to each other after the surface activation treatment is performed on both surfaces. Yes. By applying such a surface activation treatment, curling is suppressed, adhesion with various optical films and pressure-sensitive adhesive layers is improved, and a pressure-sensitive adhesive optical film having no pressure-sensitive adhesive residue and pressure-sensitive adhesive is obtained. it can. The surface activation treatment on both the optical film surface and the pressure-sensitive adhesive layer surface suppresses curling and improves the adhesion, but the surface activation treatment does not clarify the reason for the hydroxyl and carbonyl groups on both surfaces. It is considered that the adhesion is improved by increasing the number of active groups such as carboxyl groups and peroxide groups to polarize the surface. In addition, by adhering the polarized both surfaces, the adhesion at the laminated interface is improved, and the stress balance on the optical film side and the pressure-sensitive adhesive layer side is improved and curling is suppressed. Conceivable.

  The production method of the pressure-sensitive adhesive optical film of the present invention is performed by laminating a pressure-sensitive adhesive layer on at least one surface of the optical film. In addition, the said adhesive layer may provide the single side | surface of the optical film, and may have it on both surfaces of the optical film.

  An appropriate pressure-sensitive adhesive can be used for forming the pressure-sensitive adhesive layer, and the type thereof is not particularly limited. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Examples thereof include cellulose-based pressure-sensitive adhesives.

  Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

  The acrylic pressure-sensitive adhesive is based on an acrylic polymer having a monomer unit of (meth) acrylic acid alkyl ester as a main skeleton. The (meth) acrylic acid alkyl ester refers to an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, and (meth) in the present invention has the same meaning. Examples of the (meth) acrylic acid alkyl ester constituting the main skeleton of the acrylic polymer include linear or branched alkyl groups having 1 to 20 carbon atoms. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic Illustrative examples include isononyl acid, isomyristyl (meth) acrylate, and lauryl (meth) acrylate. These can be used alone or in combination. The average carbon number of these alkyl groups is preferably 3-9.

  In the acrylic polymer, one or more kinds of copolymerization monomers can be introduced by copolymerization for the purpose of improving adhesiveness and heat resistance. Specific examples of such copolymerization monomers include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 6 Hydroxyl group-containing monomers such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride Monomer-containing monomer; Caprolac of acrylic acid Adducts such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, etc. And sulfonic acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate.

  In addition, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomer; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid t-butylaminoethyl and other (meth) acrylic acid alkylaminoalkyl monomers; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( (Meta) acryloyl- -Succinimide monomers such as oxyoctamethylene succinimide and N-acryloylmorpholine; Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; N-methylitaconimide, N-ethyl Itaconimide monomers such as itaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, etc. are listed as examples of monomers for modification purposes. It is done.

  Further, as modifying monomers, vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N- Vinyl monomers such as vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; (Meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid meth Glycol acrylic ester monomers such as polypropylene glycol; acrylic acid ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate may also be used. it can.

  Although the ratio of the copolymerization monomer in the acrylic polymer is not particularly limited, it is preferably about 0 to 30%, more preferably about 0.1 to 15% in the weight ratio of all the constituent monomers.

  Among these copolymer monomers, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used from the viewpoint of adhesiveness and durability. These monomers serve as reaction points with the crosslinking agent. Since a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and the like are rich in reactivity with an intermolecular crosslinking agent, they are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer.

  When a hydroxyl group-containing monomer and a carboxyl group-containing monomer are contained as a copolymerization monomer, the acrylic polymer has (meth) acrylic acid alkyl ester 88 to 99.89% by weight, carboxyl group-containing, in the weight ratio of all constituent monomers. It preferably contains 0.1 to 10% by weight of monomer and 0.01 to 2% by weight of hydroxyl group-containing monomer. The (meth) acrylic acid alkyl ester is more preferably 90.5 to 99.77% by weight, and further preferably 93 to 99.35% by weight. The carboxyl group-containing monomer is more preferably 0.2 to 8% by weight, and further preferably 0.6 to 6% by weight. The hydroxyl group-containing monomer is more preferably 0.03 to 1.5% by weight, and even more preferably 0.05 to 1% by weight.

  The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 300,000 to 2.5 million. The acrylic polymer can be produced by various known methods. For example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

  The pressure-sensitive adhesive is preferably a pressure-sensitive adhesive composition containing a crosslinking agent. Examples of the polyfunctional compound that can be blended in the pressure-sensitive adhesive include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a peroxide crosslinking agent. These crosslinking agents can be used alone or in combination of two or more. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. can give. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

  The blending ratio of the base polymer such as the acrylic polymer and the crosslinking agent is not particularly limited, but is usually preferably about 0.001 to 20 parts by weight of the crosslinking agent (solid content) with respect to 100 parts by weight of the base polymer (solid content). Furthermore, about 0.01-15 weight part is preferable. As said crosslinking agent, an isocyanate type crosslinking agent is preferable. The isocyanate-based crosslinking agent is preferably about 0.001 to 2 parts by weight, more preferably about 0.01 to 1.5 parts by weight with respect to 100 parts by weight of the base polymer (solid content).

  Furthermore, the pressure-sensitive adhesive may include a tackifier, a plasticizer, glass fiber, glass beads, metal powder, other inorganic powders, a pigment, a colorant, a filler, an antioxidant, if necessary. Various additives may be used as appropriate, such as an agent, an ultraviolet absorber, a silane coupling agent, and the like without departing from the object of the present invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  As the additive, a silane coupling agent is suitable, and the silane coupling agent (solid content) is preferably about 0.001 to 10 parts by weight with respect to 100 parts by weight of the base polymer (solid content). It is preferable to add about 005 to 5 parts by weight. As the silane coupling agent, those conventionally known can be used without particular limitation. For example, epoxy groups such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane -Containing silane coupling agent, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine Amino group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, (meth) acrylic group-containing silane coupling agents such as 3-methacryloxypropyltriethoxysilane, and isocyanates such as 3-isocyanatopropyltriethoxysilane Base It can be exemplified a silane coupling agent.

  Examples of the optical film used in the pressure-sensitive adhesive optical film of the present invention include a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, ( B) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film of the present invention, it is preferable to use at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, and “UZ” manufactured by Fujifilm Corporation. -TAC "and" KC series "manufactured by Konica. In general, these triacetyl celluloses have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 1).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are low. May be insufficient. If the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of moldability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when it is incorporated in a polarizing plate as a transparent protective film, it has excellent durability. Although the upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary, ternary copolymers, graft copolymers Examples thereof include polymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers can be prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  For example, in a phase difference plate that satisfies nx> ny> nz, a surface plate having a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5 is used. Is preferred. For example, in a retardation plate (positive A plate) that satisfies nx> ny = nz, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, for a retardation plate (negative A plate) that satisfies nz = nx> ny, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, in a retardation plate satisfying nx> nz> ny, it is preferable to use a retardation plate having a front phase difference of 150 to 300 nm and an Nz coefficient exceeding 0 to 0.7. As described above, for example, a material satisfying nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used.

  The transparent protective film can be appropriately selected according to the applied liquid crystal display device. For example, in the case of VA (including Vertical Alignment, MVA, and PVA), it is desirable that at least one of the polarizing plates (cell side) has a retardation. As specific phase differences, it is desirable that Re = 0 to 240 nm and Rth = 0 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> ny> nz, nx> nz> ny, nx = ny> nz (positive A plate, biaxial, negative C plate) are desirable. In the VA type, it is preferable to use a combination of a positive A plate and a negative C plate, or one biaxial film. When polarizing plates are used above and below the liquid crystal cell, both the upper and lower sides of the liquid crystal cell may have a phase difference, or any one of the upper and lower transparent protective films may have a phase difference.

  For example, in the case of IPS (including In-Plane Switching, FFS), both cases where the transparent protective film on one side of the polarizing plate has a phase difference and does not have a phase difference can be used. For example, when there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference both above and below (cell side). In the case where the liquid crystal cell has a phase difference, it is desirable that the liquid crystal cell has a phase difference in the upper and lower sides, or the upper and lower sides have a phase difference (for example, nx> nz> ny on the upper side). Biaxial film satisfying the relationship, when there is no retardation on the lower side, positive A plate on the upper side, and positive C plate on the lower side). When it has a phase difference, it is desirable that Re = −500 to 500 nm and Rth = −500 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> nz> ny, nz> nx = ny, nz> nx> ny (positive A plate, biaxial, positive C plate) are desirable.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can be provided.

  The transparent protective film may be subjected to surface modification treatment in order to improve adhesiveness with the polarizer before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, and treatment with a coupling agent. Further, an antistatic layer can be appropriately formed.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable polarizing plate adhesive exhibits suitable adhesion to the various transparent protective films. The adhesive used in the present invention can contain a metal compound filler.

  In addition, as an optical film, for example, for formation of a liquid crystal display device such as a reflection plate, an anti-transmission plate, the retardation plate (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. The optical layer which may be used is mentioned. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a visual compensation film is further laminated on a plate, or a polarizing plate in which a luminance enhancement film is further laminated on a polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. In addition, the transparent protective film may contain fine particles to form a surface fine concavo-convex structure, and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by, for example, applying metal to the surface of the transparent protective layer by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the screen.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in power source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate can be used to form liquid crystal display devices that can save energy when using a light source such as a backlight in a bright atmosphere and can be used with a built-in power supply even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The visual compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a visual compensation phase difference plate include a phase difference plate, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film that is uniaxially stretched in the plane direction, whereas a retardation plate used as a visual compensation film is biaxially stretched in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. can give. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  In addition, from the viewpoint of achieving a wide viewing angle with good visibility, an optical compensation position in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A phase difference plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and accordingly, the amount of light that can be used for liquid crystal image display or the like is reduced and the image becomes dark. The brightness enhancement film reflects light that has a polarization direction that is absorbed by the polarizer without being incident on the polarizer, and is reflected by the brightness enhancement film, and then inverted through a reflective layer or the like provided behind the brightness enhancement film. The brightness enhancement film transmits only the polarized light in which the polarization direction of the light reflected and inverted between the two is allowed to pass through the polarizer. Since the light is supplied to the polarizer, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the light in the natural light state is directed toward the reflection layer or the like, reflected through the reflection layer or the like, and again passes through the diffusion plate and reenters the brightness enhancement film. In this way, by providing a diffuser plate that returns polarized light to the original natural light between the brightness enhancement film and the reflective layer, the brightness of the display screen is maintained, and at the same time, the brightness of the display screen is reduced and uniform. Can provide a bright screen. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things such as a thing can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is, but from the point of suppressing absorption loss, the circularly polarized light is converted into linearly polarized light through a retardation plate. It is preferably incident on the polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate at a wide wavelength in the visible light region or the like exhibits, for example, a retardation plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method in which a phase difference layer, for example, a phase difference layer that functions as a half-wave plate is superimposed. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer having a reflection structure that reflects circularly polarized light in a wide wavelength range such as a visible light range can be obtained by combining two or more layers with different reflection wavelengths to form an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-described reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with a target phase difference characteristic.

  In addition, each layer such as an optical film or an adhesive layer of the pressure-sensitive adhesive optical film of the present invention includes, for example, an ultraviolet ray such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. What gave the ultraviolet absorptivity by systems, such as a system processed with an absorber, may be used.

  The pressure-sensitive adhesive optical film of the present invention is produced by laminating a pressure-sensitive adhesive layer on the optical film. Examples of the lamination of the pressure-sensitive adhesive layer on the optical film include a method of transferring the pressure-sensitive adhesive layer with a release sheet provided with the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer can be formed on the release sheet by applying and drying a pressure-sensitive adhesive solution or the like on the release sheet. As the coating method, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method can be employed. Although the thickness of an adhesive layer is not specifically limited, It is preferable to set it as about 10-40 micrometers.

  As a constituent material of the release sheet, paper, polyethylene, polypropylene, polyethylene terephthalate and other synthetic resin films, rubber sheets, paper, cloth, non-woven fabric, nets, foam sheets and metal foils, and appropriate thin leaf bodies such as laminates thereof Etc. In order to improve the peelability from the pressure-sensitive adhesive layer, the surface of the release sheet may be subjected to a low-adhesive release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment as necessary.

  The surface of the optical film and the surface of the pressure-sensitive adhesive layer on which the laminating step is performed are subjected to a surface activation treatment before the laminating step. Examples of the surface activation treatment include plasma treatment, corona discharge treatment, ultraviolet treatment, electron beam treatment, and ozone treatment. As the surface activation treatment, plasma treatment and corona discharge treatment are preferable from the viewpoint of adhesion. The surface activation treatment performed on the surface of the optical film and the surface of the pressure-sensitive adhesive layer may be the same or different on both surfaces.

  The plasma treatment is performed, for example, by discharging in a gas atmosphere containing at least one gas such as nitrogen gas, oxygen gas, ammonia gas, argon gas, and helium gas under reduced pressure or atmospheric pressure by a plasma discharge machine. It can be carried out. The plasma treatment is a chemical reaction treatment using plasma of the gas or the like generated under the above conditions. As conditions for the low-pressure plasma, a pressure of 0.01 to 1 torr is usually employed. The plasma conditions under atmospheric pressure are usually an atmosphere of an inert gas such as argon gas, nitrogen gas, or helium, or an active gas such as oxygen gas or ammonia gas is mixed with the inert gas. It is preferable to carry out in the atmosphere. The ratio when the inert gas and the active gas are mixed is preferably about 1 to 20% by weight of the active gas with respect to about 80 to 99% by weight of the inert gas. Furthermore, it is preferable that it is 5-10 weight% of active gas with respect to 90-95 weight% of inert gas. Further, in the case where the surface activation treatment of the surface of the optical film and the surface of the pressure-sensitive adhesive layer is both plasma treatment, and plasma on at least one of the surface of the optical film and the surface of the pressure-sensitive adhesive layer The treatment is preferably performed in a gas containing an active gas (in an inert gas) in terms of curling suppression effect and adhesion improving effect. In particular, it is preferably in a gas containing oxygen gas (in an inert gas).

In the plasma treatment, the frequency is about 1 to 40 kHz, preferably 3 to 35 kHz, and the input power density (power: W divided by electrode area: cm ² ) is about 0.1 to 10 W / cm ² , preferably Is 0.5 to ² W / cm ² . Under atmospheric pressure, the gas flow rate is preferably about 1 to 500 L / min. The treatment time is preferably about 0.1 seconds to 10 minutes. The treatment time can be appropriately adjusted. For example, when the optical film and the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer provided on the release sheet) are bonded together in a continuous line, for example, the line speed is 1 to 50 m / The processing time can be controlled by setting to min, preferably 5 to 30 m / min.

  Corona discharge treatment, for example, by providing a gap between the electrode and the roll, applying a high voltage between them to cause discharge, and placing an optical film or an adhesive layer between the electrode and the roll be able to. As specific conditions, for example, the output is about 0.05 to 2.5 kW, preferably 0.5 to 1.5 kW. Examples of the electrode include a roll electrode and a bar electrode. The gap width is about 0.5 to 10 mm, preferably 1 to 3 mm. The processing time is about 0.1 second to 10 minutes. The treatment time can be appropriately adjusted. For example, when the optical film and the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer provided on the release sheet) are bonded together in a continuous line, for example, the line speed is 1 to 50 m / The processing time can be controlled by setting to min, preferably 5 to 30 m / min.

As the ultraviolet treatment, for example, an ultraviolet ray source such as a hydrogen discharge tube, a xenon discharge tube, a mercury lamp, or a laser is used, and the ultraviolet ray having a wavelength of 150 to 2000 nm is irradiated for about 5 to 60 minutes. More specific conditions can be used: a DeePUV manufactured by Nippon Battery Co., Ltd., a low pressure mercury lamp wavelength of 254.185 nm, an output of 1 kW, and a distance between the lamp and the sample of 50 mm. The electron beam treatment is performed under a pressure of 10 ⁻⁵ to 10 ⁻⁷ torr, a beam current value of 1 to 10 mA, a processing speed of 3 to 6 m / min, a titanium foil thickness of 15 to 35 μm, an acceleration voltage of 150 to 250 kV, and an irradiation amount of 0. It can be about 5-120 Mrad. The ozone treatment can be performed according to a conventional method.

  The pressure-sensitive adhesive optical film of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an adhesive optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that an adhesive optical film is used. As the liquid crystal cell, an arbitrary type such as an arbitrary type such as a TN type, STN type, π type, VA type, or IPS type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an adhesive optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. The optical film (polarizing plate or the like) of the present invention can also be applied to an organic EL display device. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight.

Example 1
(Optical film)
A 80 μm-thick polyvinyl alcohol film was stretched 5 times in an iodine solution and dried to obtain a polarizer. An optical film (polarizing plate) was prepared by pasting saponified 80 μm thick triacetyl cellulose films on both sides of this polarizer with a polyvinyl alcohol adhesive.

(Preparation of acrylic polymer)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate and 2,2′-azobisisobutyrate A solution was prepared by adding 0.3 parts of ronitrile with ethyl acetate. Next, the solution was stirred while blowing nitrogen gas and reacted at 55 ° C. for 8 hours to obtain a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Furthermore, the acrylic polymer solution which added ethyl acetate to the solution containing this acrylic polymer and adjusted solid content concentration to 30% was obtained.

(Formation of adhesive layer)
As a cross-linking agent, 100 parts by weight of the solid content of the acrylic polymer solution is a cross-linking agent mainly composed of a compound having an isocyanate group of 0.5 part (trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.). And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KMB-403”) as a silane coupling agent in this order, Was prepared. The pressure-sensitive adhesive solution was applied to the surface of a release sheet composed of a peeled polyethylene terephthalate film (thickness 38 μm) so that the thickness after drying was 25 μm and dried to form a pressure-sensitive adhesive layer.

(Surface activation treatment: plasma treatment)
About the surface of the adhesive layer formed in the single side | surface of the said polarizing plate and the peeling process surface of the said release sheet, the plasma processing was respectively performed in nitrogen gas atmosphere. The plasma treatment conditions were: output: 0.15 kW, input power density: 1 W / cm ² (electrode area: 150 cm ² ), frequency: 5 kHz, gas flow rate of 10 L / min, and line speed of 2 m / min.

(Creation of adhesive optical film)
The adhesive layer formed on the release treatment surface of the release sheet subjected to the surface activation treatment is bonded to one surface of the polarizing plate subjected to the surface activation treatment, the adhesive layer is transferred, and the adhesion type An optical film (adhesive polarizing plate) was created.

Example 2
In Example 1, an adhesive optical film (adhesive polarizer) was prepared in the same manner as in Example 1 except that the plasma treatment was performed in a mixed gas atmosphere of 95% nitrogen gas and 5% oxygen gas, respectively. Obtained.

Example 3
In Example 1, an adhesive optical film (adhesive polarizing plate) was prepared in the same manner as in Example 1 except that the plasma treatment was performed in a mixed gas atmosphere of 95% nitrogen gas and 5% ammonia gas, respectively. Obtained.

Example 4
In Example 1, a pressure-sensitive adhesive optical film was used in the same manner as in Example 1 except that a 100 μm-thick norbornene resin (JSR Co., Arton) film biaxially stretched was used as the optical film. (Adhesive phase difference plate) was obtained.

Example 5
In Example 1, the plasma treatment was performed in a nitrogen gas atmosphere on one side of the polarizing plate, while in the mixed gas atmosphere of 95% nitrogen gas and 5% oxygen gas on the surface of the pressure-sensitive adhesive layer. Except for this, an adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 1.

Example 6
In Example 1, the plasma treatment was performed in a mixed gas atmosphere of 95% nitrogen gas and 5% ammonia gas on one side of the polarizing plate, while 95% nitrogen gas and oxygen on the surface of the pressure-sensitive adhesive layer. An adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 1 except that it was performed in a mixed gas atmosphere of 5% gas.

Example 7
In Example 1, an adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 1 except that corona treatment was performed instead of plasma treatment. The corona treatment conditions were: output: 0.1 kW, bar electrode, gap 1 mm, and line speed 2 m / min.

Comparative Example 1
In Example 1, an adhesive optical film (adhesive polarizer) was obtained in the same manner as in Example 1 except that the plasma treatment was performed only on one side of the polarizer.

Comparative Example 2
In Example 1, an adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 1 except that the plasma treatment was performed only on the surface of the adhesive layer.

Comparative Example 3
In Example 7, an adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 7 except that the corona treatment was performed only on one side of the polarizing plate.

Comparative Example 4
In Example 7, an adhesive optical film (adhesive polarizing plate) was obtained in the same manner as in Example 7 except that the corona treatment was performed only on the surface of the adhesive layer.

Comparative Example 5
In Example 1, an adhesive optical film (adhesive polarizing plate) was prepared in the same manner as in Example 1 except that the plasma treatment was not performed on one side of the polarizing plate and the surface of the adhesive layer. Obtained.

  The following evaluation was performed about the adhesive optical film obtained by the said Example and comparative example. The evaluation results are shown in Table 1.

(Adhesive remaining)
The adhesive-type polarizing film prepared as described above was cut into 50 sheets of 50 mm × 1500 mm and bonded onto a glass plate (a non-alkali glass plate # 1737 manufactured by Corning), and 15 in an atmosphere of 50 ° C. × 5 MPa. I left it for a while. Next, the adhesive polarizing film was peeled off from the glass at a rate of 300 mm / min in the 180 ° direction. Thereafter, the number of samples (adhesion number) in which the adhesive was adhered on the glass was visually confirmed.

(Adhesive missing)
The adhesive polarizing film prepared as described above is punched out to a size of 25 mm × 150 mm with a Thomson blade type, and the cut end (25 mm width side) is continuous 20 times on a glass plate (a non-alkali glass plate # 1737 manufactured by Corning). In contact. Then, the said contact part of each adhesive optical film was confirmed visually, and the following references | standards evaluated.
A: No adhesive chipping with a depth of 150 μm or more.
Δ: Depth of adhesive is more than 150 μm and less than 300 μm, but there is no practical problem.
X: There is a lack of adhesive having a depth of 300 μm or more.

(Adhesion)
The pressure-sensitive adhesive polarizing film prepared as described above was cut into a size of 25 mm × 150 mm, and the pressure-sensitive adhesive layer surface thereof and the vapor-deposited surface of a vapor-deposited film in which indium-tin oxide was vapor-deposited on the surface of a 50 μm-thick polyethylene terephthalate film After being bonded so as to be in contact with each other, it was left in an environment of 23 ° C./60% RH for 20 minutes or more. Then, after peeling off the edge part of a polyethylene terephthalate film by hand and confirming that the adhesive has adhered to the polyethylene terephthalate film side, 180 degree direction was used using the Shimadzu Corporation tensile tester AG-1. The stress (N / 25 mm) when peeled at a speed of 300 mm / min was measured (25 ° C.).

(curl)
The pressure-sensitive adhesive polarizing film prepared as described above was punched into a size of 100 mm × 150 mm with a Thomson blade and was allowed to stand on a glass plate (a non-alkali glass plate # 1737 manufactured by Corning). The distance (curl amount) between the cut end (100 mm width side) and the glass was measured and evaluated according to the following criteria.
○: No curling of 10 m or more.
Δ: There is curl of more than 10 mm and less than 20, but there is no practical problem.
X: There is curl of 30 mm or more.

Claims (7)

In the method for producing an adhesive optical film having a step of laminating an adhesive layer on at least one side of the optical film,
In the laminating step, the surface of the optical film on which the laminating step is performed and the surface of the pressure-sensitive adhesive layer are subjected to surface activation treatment, and then the surface of the surface-treated optical film and the surface of the pressure-sensitive adhesive layer are laminated. The manufacturing method of the adhesive optical film characterized by performing by this.   2. The method for producing an adhesive optical film according to claim 1, wherein the surface activation treatment is at least one treatment selected from plasma treatment, corona discharge treatment, ultraviolet treatment, electron beam treatment and ozone treatment. .   The surface activation treatment is a plasma treatment, and the plasma treatment is performed in a gas containing at least one selected from nitrogen gas, oxygen gas, ammonia gas, argon gas, and helium gas. A method for producing an adhesive optical film according to 1 or 2.   The surface activation treatment of the surface of the optical film and the surface of the pressure-sensitive adhesive layer are both plasma treatment, and the plasma treatment of at least one surface of the surface of the optical film and the surface of the pressure-sensitive adhesive layer is oxygen 4. The method for producing an adhesive optical film according to claim 3, wherein the method is performed in a gas containing a gas.   An adhesive optical film obtained by the production method according to claim 1.   An image display device using at least one adhesive optical film according to claim 4. When producing an adhesive optical film by laminating an adhesive layer on at least one side of the optical film,
After performing surface activation treatment on the surface of the optical film and the surface of the pressure-sensitive adhesive layer on which the lamination is performed, by laminating the surface of the optical film subjected to the surface activation treatment and the surface of the pressure-sensitive adhesive layer, A method for improving the adhesion between the optical film and the pressure-sensitive adhesive layer in the obtained pressure-sensitive adhesive optical film and suppressing curling of the pressure-sensitive adhesive optical film.