TWI448749B - Adhesive type optical film peeling method and adhesive type optical film - Google Patents

Description

Adhesive optical film peeling method and adhesive optical film

The present invention relates to a method for peeling off an adhesive optical film from which an adhesive optical film is peeled off from a glass substrate to which an optical film is attached, and an adhesive optical film used in the peeling method. Examples of the optical film include a polarizing plate, a phase difference plate, an optical compensation film, a brightness enhancement film, a viewing angle widening film, and the like.

In the liquid crystal display or the like, it is necessary to arrange a polarizing element on both sides of the liquid crystal cell due to the relationship between the image forming modes, and it is usually attached to the polarizing plate. Further, in order to improve the display quality of the display, various optical elements other than the polarizing plate are used on the liquid crystal panel. For example, a phase difference plate for preventing coloration, a viewing angle expansion film for improving the viewing angle of the liquid crystal display, and a brightness enhancement film for improving the contrast of the display are used. These films are collectively referred to as optical films.

When the above optical film is adhered to the liquid crystal cell, an adhesive is usually used. Further, when the optical film is bonded to the liquid crystal cell and the optical film is bonded, the materials are usually adhered to each other in order to reduce the loss of light. In such a case, there is an advantage that the drying step is not required to fix the optical film. Therefore, an adhesive type optical film in which an adhesive layer is formed on the single surface of the optical film in advance is usually used.

When the adhesive optical film is bonded to the surface of the liquid crystal cell, the bonding position is shifted or a foreign matter is caught, which causes a problem in liquid crystal display. Therefore, the adhesive optical film that has been attached is peeled off. Then, a new adhesive optical film is attached to the surface of the liquid crystal cell again. However, due to the enlargement of the liquid crystal display or the thinning of the liquid crystal cell, it is more and more difficult to peel off the adhesive optical film, especially when the adhesive force of the adhesive layer is strong, the peeling requires a large force. Therefore, there is a problem that the workability is deteriorated, the cell gap of the liquid crystal cell is changed, the display quality is deteriorated, or the liquid crystal cell is damaged. Further, in order to suppress the manufacturing cost, it is required to reuse the peeled adhesive optical film and to rework without peeling off the residue.

As a method for solving the above problems, there is proposed a method of softening or melting and peeling off an adhesive while inserting a heated electric-heated wire or a slicer between a liquid crystal panel and an optical film. Patent Documents 1 and 2); and a method of cutting a slit by cutting a slit on an optical film on a liquid crystal panel, and peeling off the split sheet (Patent Document 3).

Further, a method of immersing a display material adhered with a transparent film via an adhesive in an alkaline solution and peeling off the transparent film and the adhesive from the display material has been proposed (Patent Document 4).

Further, a method of bonding a release sheet to an optical member to be peeled off, peeling off the optical member together with the release sheet (Patent Document 5), and attaching the polarizing plate to the adhesive tape is proposed. Method of peeling (Patent Document 6).

Further, a method of removing a polarizing plate or the like contained on a glass substrate by immersion in concentrated sulfuric acid has been proposed (Patent Document 7); the adhesive is dissolved and removed by using a solvent such as acetone or trichloroethylene to be stripped. Method of polarizing plate (Patent Document 8); a method of removing a polarizing plate by dissolving a polarizing plate in a solvent for a polarizing plate (Patent Document 9); and a peeling interface between the adhesive layer of the adhesive optical film and the substrate A method of performing peeling in the presence of a liquid (Patent Document 10).

However, in the above method, it is necessary to perform a work such as inserting a peeling jig between the liquid crystal panel and the optical film, or cutting only the optical film on the liquid crystal panel. Further, there is a problem that a large amount of paper residue is generated on the liquid crystal panel, or damage to the liquid crystal panel due to the solvent.

Patent Document 1: Japanese Patent Laid-Open No. Hei 11-95210

Patent Document 2: Japanese Patent Laid-Open Publication No. 2002-350837

Patent Document 3: Japanese Patent Laid-Open Publication No. 2001-242448

Patent Document 4: Japanese Patent Laid-Open Publication No. 2001-328849

Patent Document 5: Japanese Patent Laid-Open Publication No. 2002-40259

Patent Document 6: Japanese Patent Laid-Open Publication No. 2002-159955

Patent Document 7: Japanese Patent Laid-Open Publication No. 2001-305502

Patent Document 8: Japanese Patent Laid-Open Publication No. 2001-337305

Patent Document 9: Japanese Patent Laid-Open Publication No. 2005-224715

Patent Document 10: Japanese Patent Laid-Open Publication No. 2005-148638

An object of the present invention is to provide a method for peeling an adhesive optical film and an adhesive optical film used in the peeling method. The adhesive optical film can be peeled off from a glass substrate to which an adhesive optical film is attached. The glass substrate is damaged, and no adhesive residue is generated on the glass substrate, and the adhesive optical film is easily peeled off. In particular, it is an object of the present invention to provide an adhesive optical film which can be peeled off without sticking and can be easily peeled off even when the adhesive optical film is bonded to the glass substrate for a long period of time and the force is increased and the heavy work becomes extremely difficult. Membrane method.

The inventors of the present invention have diligently studied to solve the above problems, and as a result, have found that the above object can be attained by the following peeling method, and the present invention has been completed.

That is, the present invention relates to a method for peeling an adhesive optical film which is obtained by peeling an adhesive optical film from a glass substrate with an optical film to which an adhesive optical film is adhered on a glass substrate, and is characterized in that: The adhesive layer of the optical film is formed of a water-dispersible adhesive, and the peeling method exposes the glass substrate with the optical film to a temperature of 40 ° C or higher and a relative humidity of 80% or more, or a temperature of 50 ° C or more. After the relative humidity is 70% or more, the adhesive optical film is peeled off from the glass substrate.

As described above, by exposing the glass substrate with the optical film to a specific environment (exposure treatment), the adhesion force of the adhesive layer of the adhesive optical film can be sufficiently reduced, so that the glass substrate can be not damaged, and no residual residue can be caused. The adhesive optical film is peeled off from the glass substrate with good workability. According to the peeling method of the present invention, even when the size of the liquid crystal panel is large or the liquid crystal cell is thin, the workability is good. Moreover, according to the peeling method of the present invention, even when the adhesive optical film is bonded to the glass substrate for a long period of time and the adhesive force is increased, the adhesive film can be peeled off without any residue.

Further, by forming the adhesive layer of the above-mentioned adhesive optical film by using a water-dispersible adhesive, the adhesive layer absorbs water by the above-mentioned exposure treatment, and moisture penetrates into the interface between the adhesive layer and the glass substrate, thereby making the adhesive layer The force is reduced sufficiently, so the reworkability is improved. Further, even if it returns to room temperature after the exposure treatment, the force does not rise again, which is preferable in terms of the working procedure.

The above adhesive optical film preferably has an adhesion-promoting layer between the optical film and the adhesive layer. By providing the adhesion-promoting layer, the stability of the adhesive optical film can be preferably adhered to the glass substrate, and the peeling of the adhesive optical film can be carried out without peeling and easily peeling off.

Further, the present invention relates to an adhesive optical film which is used in the above-mentioned method for peeling an adhesive optical film, and has an adhesive layer formed of a water-dispersible adhesive on at least one side of the optical film, The adhesive film is attached to a glass substrate, and after being exposed to an environment having a temperature of 60 ° C and a relative humidity of 30% for 100 hours, the adhesive force is 20 N/25 mm or more, and the temperature is exposed. After 40 ° C or more and a relative humidity of 80% or more, or a temperature of 50 ° C or more and a relative humidity of 70% or more, the adhesion is 10 N / 25 mm or less.

The adhesive optical film of the present invention can be exposed to a specific environment (exposure treatment) even when it is bonded to a glass substrate for a long time and then has a force of up to 20 N/25 mm or more in a high-temperature environment. The adhesion force of the adhesive layer is sufficiently lowered, so that the adhesive optical film can be peeled off from the glass substrate without damaging the glass substrate, without residue of the paste, and with good workability. The adhesive optical film of the present invention can be peeled off with good reworkability even when the size of the liquid crystal panel is large or when the liquid crystal cell is thin.

The optical film-attached glass substrate of the present invention is obtained by attaching an adhesive optical film to a glass substrate, and the adhesive layer of the adhesive optical film is formed of a water-dispersible adhesive.

As the water-dispersible pressure-sensitive adhesive, various water-dispersible pressure-sensitive adhesives such as a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive can be used, and it is preferably colorless and transparent, and is followed by a liquid crystal cell (glass substrate). A good acrylic adhesive.

The water-dispersible acrylic pressure-sensitive adhesive contains an acrylic polymer emulsion obtained by emulsion polymerization of an alkyl (meth)acrylate in the presence of an emulsifier. Further, (meth) acrylate means acrylate and/or methacrylate, and (meth) has the same meaning. The alkyl group of the alkyl (meth)acrylate has a carbon number of about 1 to 14, and specifically, methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate are exemplified. , (3) butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( N-octyl methacrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylate An oxime ester, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, etc. may be used singly or in combination.

In order to adjust the adhesion characteristics of the glass transition point or the adhesive layer of the acrylic polymer, other polymerizable monomers may also be used. In particular, in order to increase the adhesion to the glass substrate, or to introduce a crosslinking point for subsequent crosslinking of the obtained copolymer, and further to increase the cohesive force of the adhesive, it is preferred to use a monomer having a carboxyl group.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, and fumaric acid. , butenoic acid, etc. Among them, acrylic acid and methacrylic acid are particularly preferably used.

The amount of the carboxyl group-containing monomer added is preferably from 0.1 to 10% by weight, more preferably from 1 to 7% by weight, based on the total amount of the monomer component forming the acrylic polymer.

Further, as the other polymerizable monomer, for example, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, a vinyl ester monomer, an aromatic vinyl monomer, or the like can be suitably used for enhancing cohesive force. a heat resistant component, or an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, a guanamine group-containing monomer, an amine group-containing monomer, an epoxy group-containing monomer, N-propylene morpholine, A vinyl ether monomer or the like which enhances the adhesion or has a functional group that functions as a crosslinking point. These monomers may be used singly or in combination of two or more.

Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, 2-(methyl)acrylamido-2-methylpropanesulfonic acid, and (meth)acrylamide. Sulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloxynaphthalenesulfonic acid, and the like.

Examples of the phosphoric acid group-containing monomer include 2-hydroxyethyl acrylonitrile phosphate and mono [poly(oxypropylene) (meth) acrylate] phosphate.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, and vinyl laurate.

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, and α-methylstyrene.

Examples of the acid anhydride group-containing monomer include maleic anhydride and itaconic anhydride.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and (meth)acrylic acid 6 -Hydroxyhexyl ester, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl acrylate , N-methylol (meth) acrylamide, N-hydroxy (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethyl Glycol monovinyl ether and the like.

Examples of the monomer containing a guanamine group include acrylamide, diethyl acrylamide, and the like.

Examples of the monomer having an amine group include N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and N-(A). Base) acryloyl morpholine, alkylaminoalkyl (meth) acrylate, and the like.

Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and allyl glycidyl ether.

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

Further, examples of the polymerizable monomer other than the above include a decane-based monomer containing a ruthenium atom. Examples of the decane-based monomer include 3-(meth)acryloxypropyltrimethoxydecane, vinyltrimethoxydecane, vinyltriethoxydecane, and 4-vinylbutyltrimethoxy. Baseline, 4-vinylbutyltriethoxydecane, 8-vinyloctyltrimethoxydecane, 8-vinyloctyltriethoxydecane, 10-methylpropenyloxydecyltrimethoxy Alkane, 10-propenyloxydecyltrimethoxydecane, 10-methylpropenyloxydecyltriethoxydecane, 10-propenyloxydecyltriethoxydecane, and the like.

The decane-based monomer may be used singly or in combination of two or more. The content of the decane-based monomer is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the acrylic polymer, more preferably 0.01 to 1 part by weight. It is preferred to copolymerize a decane-based monomer to improve durability.

The acrylic polymer preferably has a weight average molecular weight of a solvent-soluble component of 500,000 or more, preferably 1,000,000 or more, more preferably 1.8,000,000 or more. When the weight average molecular weight is less than 500,000, there is a tendency that the cohesive force of the adhesive composition becomes small to cause a residual of the paste. The weight average molecular weight is obtained by GPC (Gel Permeation Chromatography).

The acrylic polymer is prepared by emulsion polymerization (emulsification polymerization). Further, the copolymer obtained may be any of a random copolymer, a block copolymer and the like.

The polymerization initiator, the emulsifier and the like are not particularly limited, and can be appropriately selected and used.

Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, and 2,2'-azobis. [2-(5-Methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'- Azobis(N,N'-dimethylideneisobutane), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine hydrate (Wako Pure Chemicals) Manufactured by the company, VA-057), etc.; azo-based initiator; potassium persulfate, ammonium persulfate, etc.; peroxydicarbonate di(2-ethylhexyl) ester, peroxydicarbonate di(4) -T-butylcyclohexyl)ester, di-second butyl peroxydicarbonate, tert-butyl peroxy neodecanoate, third hexyl peroxypivalate, tert-butyl peroxypivalate , dilauroyl peroxide, di-n-octyl peroxide, 2-ethylperoxyhexanoic acid-1,1,3,3-tetramethylbutyl ester, bis(4-methylbenzhydryl) peroxide, Peroxide system of benzamidine peroxide, tert-butyl peroxyisobutyrate, 1,1-bis(tetrahexyl peroxide)cyclohexane, tert-butyl hydroperoxide, hydrogen peroxide, etc. Starting agent; persulfate and sulfurous acid Combination of sodium, of sodium ascorbate in combination with a peroxide or the like formed by combining the peroxide with a reducing agent of a redox-based initiator and so forth, but are not limited to such.

The polymerization initiator may be used singly or in combination of two or more. The content of the polymerization initiator as a whole is preferably 0.002 to 0.5 part by weight, more preferably 0.005 to 0.2 part by weight based on 100 parts by weight of the monomer. Share.

Examples of the emulsifier include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkylbenzene. Anionic emulsifier such as ammonium ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl sulfosuccinate; polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fat A nonionic emulsifier such as an acid ester or a polyoxyethylene-polyoxypropylene block polymer. These emulsifiers may be used singly or in combination of two or more.

Further, as a reactive emulsifier into which a radical polymerizable functional group such as a propenyl group or an allyl ether group is introduced, for example, AQUALON HS-10, HS-20, HS-1025, KH-10, BC-05, BC -10, BC-20 (manufactured by Daiichi Kogyo Co., Ltd.), ADEKA REASOAP SE10N (manufactured by Asahi Kasei Co., Ltd.), etc. Since the reactive emulsifier is introduced into the polymer chain by polymerization, water resistance is preferred, which is preferable.

The amount of the emulsifier used is preferably 0.5 to 5 parts by weight, more preferably 1 to 4 parts by weight, per 100 parts by weight of the monomer, from the viewpoints of polymerization stability, mechanical stability, and adhesion.

Further, a chain transfer agent can also be used in the polymerization. The molecular weight of the acrylic polymer can be suitably adjusted by using a chain transfer agent.

As the chain transfer agent, for example, lauryl mercaptan, glycidyl mercaptan, 1-dodecanethiol, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2 , 3-dimercapto-1-propanol, and the like.

These chain transfer agents may be used singly or in combination of two or more kinds, and the content of the chain transfer agent as a whole is about 0.001 to 0.5 parts by weight based on 100 parts by weight of the monomer.

As an example of the polymerization operation, for example, the above monomers or comonomers are first mixed, and an emulsifier and water are formulated therein, followed by emulsification to prepare an emulsion. At this time, the monomer may be blended with all or a part of the total amount used, and the remainder is added dropwise during the polymerization. Then, a polymerization initiator and optionally water are added to the emulsion to carry out emulsion polymerization (emulsification polymerization).

Further, the water may be formulated only when the emulsion is prepared, or may be further formulated after the preparation. Further, the amount of water to be added is not particularly limited, and it is preferably prepared so that the solid content of the acrylic polymer after emulsion polymerization (emulsification polymerization) is 30 to 75% by weight, more preferably 35. ~60% by weight.

The method of the emulsion polymerization (emulsification polymerization) is not particularly limited, and can be appropriately selected from a one-time polymerization method, a total amount of addition method, a two-stage polymerization method in which these are combined, and the like.

In the disposable polymerization method, for example, a monomer mixture, an emulsifier, and water are charged into a reaction vessel, and the emulsion is prepared by emulsification by stirring and mixing, and then a polymerization initiator and a reaction are added to the reaction vessel. The required water is used for emulsion polymerization (emulsification polymerization).

Further, in the total amount dropping method, a monomer mixture, an emulsifier, and water are first added, and the dropwise addition liquid is prepared by emulsification by stirring and mixing, and the polymerization initiator and water are charged into the reaction container in advance. Then, the dropwise addition was added to the reaction vessel to carry out emulsion polymerization (emulsification polymerization).

The average particle diameter of the emulsion particles is not particularly limited as long as it is excellent in mechanical stability and coatability, and is usually 0.07 to 3 μm, preferably 0.07 to 1 μm. When the average particle diameter is less than 0.07 μm, the viscosity of the adhesive tends to be too high, and when it exceeds 3 μm, the meltability between the emulsion particles is lowered to cause a decrease in cohesive force.

The water-dispersible acrylic pressure-sensitive adhesive contains the above-mentioned acrylic polymer emulsion as a main component, and may contain a crosslinking agent as needed. Examples of the crosslinking agent include a carbodiimide compound and a An oxazoline group compound, a polyisocyanate compound, a polyamine compound, a melamine resin, a urea resin, an epoxy resin, or the like. The amount of the crosslinking agent to be added is not particularly limited as long as it does not impair the adhesion characteristics, and is usually 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on the solid content of the adhesive. When the amount of the crosslinking agent added is large, the elastic modulus of the adhesive layer tends to be too high, and the adhesion may be lowered. Further, an adhesive component or other various additives can be added.

Further, other known additives may be added to the water-dispersible acrylic pressure-sensitive adhesive. For example, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a decane coupling agent, or the like may be added as appropriate.

The adhesive optical film is formed by forming an adhesive layer on at least one side of the optical film by the above-mentioned adhesive.

As a method of forming the pressure-sensitive adhesive layer, for example, a water-dispersible pressure-sensitive adhesive is applied onto a separation-treated separator or the like, and a polymerization solvent or the like is dried to form an adhesive layer, and then the adhesive layer is formed. A method of transferring onto an optical film; or a method of applying a water-dispersible pressure-sensitive adhesive to an optical film, drying and removing a polymerization solvent or the like to form an adhesive layer, and the like.

As a method of forming the adhesive layer, various methods can be employed. For example, a comma coater, a fountain die coater, a lip coater, a slot die coater, or the like can be used. The method of the coater.

The thickness of the adhesive layer is not particularly limited and is usually about 3 to 500 μm. It is preferably 5 to 100 μm, more preferably 5 to 40 μm.

The adhesive optical film preferably has a tackifying layer between the optical film and the adhesive layer.

As a material for forming the adhesion-promoting layer, a polymer having a functional group reactive with the polymer of the adhesive layer is preferably used, and for example, it may be mentioned An oxazoline-based polymer or an amine-containing polymer.

The adhesion-promoting layer can be formed by directly applying a solution or an aqueous dispersion containing the above polymer to one side or both surfaces of the optical film and drying it.

The thickness of the tackified layer after drying is usually from 1 to 500 nm, preferably from 10 to 450 nm, more preferably from 15 to 400 nm. If the adhesion-promoting layer has a thickness in the above range, the adhesion between the optical film and the adhesive layer can be sufficiently increased.

As an optical film used for the adhesive optical film, a polarizing plate is mentioned, for example. The polarizing plate is generally used for a transparent protective film on one side or both sides of the polarizer.

The polarizer is not particularly limited, and various polarizers can be used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene/vinyl acetate copolymer partial saponified film, which adsorbs iodine or a dichroic dye. The coloring matter is then obtained by uniaxial stretching; and a polyene-based alignment film such as a dehydrated material of polyvinyl alcohol or a dehydrochlorination product of polyvinyl chloride. Among these, a polarizer formed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred. The thickness of the polarizer is not particularly limited and is usually about 5 to 80 μm.

A polarizer in which a polyvinyl alcohol-based film is dyed and uniaxially stretched with iodine can be produced, for example, by immersing a polyvinyl alcohol film in an aqueous solution of iodine for dyeing, and extending the polyvinyl alcohol film to the original length. 3 to 7 times. The polyvinyl alcohol-based film may be immersed in an aqueous solution of potassium iodide or the like, and the aqueous solution may contain boric acid, zinc sulfate, zinc chloride or the like as needed. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, the dirt or the anti-caking agent on the surface of the polyvinyl alcohol-based film can be washed away, and in addition, the polyvinyl alcohol-based film can be swollen to prevent dyeing. Equal uneven effect. The extension may be carried out after dyeing with iodine, or may be extended while dyeing, or may be dyed with iodine after stretching. It can also be extended in an aqueous solution or a water bath such as boric acid or potassium iodide.

As the material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and isotropic property can be used. Specific examples of such a thermoplastic resin include cellulose resins such as cellulose triacetate, polyester resins, polyether oxime resins, polyfluorene resins, polycarbonate resins, polyamide resins, and polyimide resins. , polyolefin resin, (meth)acrylic resin, cyclic polyolefin resin An olefinic resin), a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, and a mixture thereof. Further, a transparent protective film is bonded to one side of the polarizer by an adhesive layer, and (meth)acrylic, urethane-based or urethane-based acrylate is used on the other side. A thermosetting resin such as an epoxy resin or an anthracene oxygen resin or an ultraviolet curable resin is used as a transparent protective film. The transparent protective film may also contain one or more of any suitable additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color preventive agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the above thermoplastic resin in the transparent protective film is preferably from 50 to 100% by weight, more preferably from 50 to 99% by weight, still more preferably from 60 to 98% by weight, particularly preferably from 70 to 97% by weight. . When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency and the like which the thermoplastic resin originally has may not be sufficiently exhibited.

Further, as the transparent protective film, a polymer film disclosed in Japanese Patent Laid-Open Publication No. 2001-343529 (WO 01/37007), for example, contains (A) a substituted and/or unsubstituted quinone imine on the side chain. A resin composition based on a thermoplastic resin and a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group in (B) a side chain. Specific examples include a film containing a resin composition comprising an alternating copolymer of isobutylene and N-methylbutyleneimine and an acrylonitrile-styrene copolymer. As the film, a film formed of a mixed extrusion of a resin composition or the like can be used. Since the phase difference of the films is small and the photoelastic coefficient is small, the unevenness due to the strain of the polarizing plate can be eliminated, and the moisture permeability of the films is small, so that the humidifying durability is excellent. .

The thickness of the transparent protective film can be appropriately determined, and the thickness of the film is usually about 1 to 500 μm from the viewpoints of workability such as strength and workability, and thin layer properties. Particularly preferably, it is 1 to 300 μm, more preferably 5 to 200 μm. It is particularly suitable when the transparent protective film is 5 to 150 μm.

Further, when a transparent protective film is provided on both sides of the polarizer, a protective film formed of the same polymer material may be used on the front and back surfaces thereof, and a protective film formed of a different polymer material or the like may be used.

As the transparent protective film, at least one selected from the group consisting of a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth)acrylic resin is preferably used.

The cellulose resin is an ester of cellulose and a fatty acid. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among these, cellulose triacetate is particularly preferred. Cellulose triacetate is commercially available with more products and is also advantageous from the standpoint of availability or cost. Examples of the commercially available product of cellulose triacetate include "UV-50", "UV-80", "SH-80", and "TD-80U" manufactured by Fuji Film Co., Ltd. "TD-TAC", "UZ-TAC" or "KC Series" manufactured by Konica Corporation. Usually, the in-plane retardation (Re) of the cellulose triacetate is almost zero, and the phase difference (Rth) in the thickness direction is about ~60 nm.

Further, the cellulose resin film having a small retardation in the thickness direction can be obtained, for example, by treating the above cellulose resin. For example, a method in which a base film such as polyethylene terephthalate coated with a solvent such as cyclopentanone or methyl ethyl ketone, polypropylene or stainless steel is bonded to a common cellulose film can be mentioned. After heating and drying (for example, drying at 80 to 150 ° C for 3 to 10 minutes), the substrate film is peeled off; The olefin resin or the (meth)acrylic resin is dissolved in a solvent such as cyclopentanone or methyl ethyl ketone, and the obtained solution is applied onto a common cellulose resin film and dried by heating (for example, 80 to 150). After heating and drying at ° C for about 3 to 10 minutes, the coating film is peeled off and the like.

Further, as the cellulose resin film having a small phase difference in the thickness direction, a fatty acid cellulose resin film having a controlled degree of substitution of a fatty acid can be used. Generally, the cellulose triacetate used has a degree of substitution of about 2.8, and Rth can be reduced by controlling the degree of substitution of acetamidine to preferably 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide or triethyl citrate to the cellulose-based resin. The amount of the plasticizer added is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, still more preferably 1 to 15 parts by weight, per 100 parts by weight of the fatty acid cellulose-based resin.

As a specific example of the cyclic polyolefin resin, it is preferred to lower An olefinic resin. The cyclic olefin-based resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit, and examples thereof include a Japanese Patent Laid-Open No. Hei No. 1-240517, Japanese Patent Laid-Open No. Hei No. Hei No. Hei No. Hei No. Hei. A resin disclosed in Japanese Patent Publication No. 122137 or the like. Specific examples thereof include a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene (typically, a copolymer, a graft polymer formed by modifying an unsaturated carboxylic acid or a derivative thereof, and a hydride or the like. Specific examples of the cyclic olefin include a descending An olefinic monomer.

As the cyclic polyolefin resin, various products are commercially available. Specific examples include the product name "ZEONEX" manufactured by Japan ZEON Co., Ltd., "ZEONOR", the product name "ARTON" manufactured by JSR Co., Ltd., and the product name "TOPAS" manufactured by TICONA, manufactured by Mitsui Chemicals Co., Ltd. The product name is "APEL".

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

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used without departing from the effects of the present invention. For example, poly(meth)acrylate, polymethyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylate copolymer, A Methyl acrylate-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate - Cyclohexyl methacrylate copolymer, methyl methacrylate-(meth)acrylic acid Ester copolymers, etc.). Preferably, a poly(meth)acrylic acid C1-6 alkyl ester such as poly(methyl) acrylate is used. More preferably, methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

Specific examples of the (meth)acrylic resin include, for example, those disclosed in Mitsubishi Rayon (MITSUBISHI RAYON) Co., Ltd., ACRYPET VH or ACRYPET VRL20A, and Japanese Patent Laid-Open No. 2004-70296. A (meth)acrylic resin having a ring structure, a high Tg (meth)acrylic resin obtained by intramolecular crosslinking or intramolecular cyclization.

As the (meth)acrylic resin, a (meth)acrylic resin having a lactone ring structure can also be used. The reason for this is that the (meth)acrylic resin having a lactone ring structure has high heat resistance, high transparency, and can have high mechanical strength by biaxial stretching.

Examples of the (meth)acrylic resin having a lactone ring structure include JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, and JP-A. A (meth)acrylic resin having a lactone ring structure disclosed in JP-A-2005-146084, and the like.

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

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Further, the organic residue may contain an oxygen atom.

The content of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is preferably from 5 to 90% by weight, more preferably from 10 to 8% by weight. 70% by weight, further preferably 10 to 60% by weight, particularly preferably 10 to 50% by weight. When the content ratio of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is less than 5% by weight, the (meth)acrylic resin The heat resistance, solvent resistance, and surface hardness may be insufficient. When the content ratio of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is more than 90% by weight, the (meth)acrylic resin There may be a lack of formability.

The mass average molecular weight (sometimes referred to as a weight average molecular weight) of the (meth)acrylic resin having a lactone ring structure is preferably from 1,000 to 2,000,000, more preferably from 5,000 to 1,000,000, and even more preferably from 10,000 to 10,000. 500000, especially good is 50000~500000. When the mass average molecular weight is outside the above range, it is not preferable from the viewpoint of moldability.

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

For a (meth)acrylic resin having a lactone ring structure, the use of a molded article obtained by injection molding has a higher total light transmittance measured by the method based on ASTM-D-1003. The better, the better is 85% or more, more preferably 88% or more, and even more preferably 90% or more. The total light transmittance is a standard of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

The transparent protective film is generally used in which the front phase difference is less than 40 nm and the thickness direction retardation is less than 80 nm. The front phase difference Re is represented by Re = (nx - ny) × d. The thickness direction phase difference Rth is represented by Rth = (nx - nz) × d. Further, the Nz coefficient is expressed by Nz = (nx - nz) / (nx - ny). [The refractive index of the slow axis direction, the fast axis direction, and the thickness direction of the film is set to nx, ny, nz, and d (nm), respectively, to the thickness of the film. The direction of the slow axis is the direction in which the refractive index in the film plane is the largest]. Further, the transparent protective film is preferably as colorless as possible. A protective film having a phase difference in the thickness direction of -90 nm to +75 nm can be preferably used. By using the phase difference (Rth) in the thickness direction 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 phase difference (Rth) in the thickness direction 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 front phase difference of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. Generally, the front phase difference is controlled within a range of 40 to 200 nm, and the thickness direction phase difference is usually controlled within a range of 80 to 300 nm. When a retardation film is used as the transparent protective film, since the retardation film also functions as a transparent protective film, it can be made thinner.

Examples of the retardation film include a birefringent film formed by subjecting a polymer material to uniaxial or biaxial stretching treatment, an alignment film of a liquid crystal polymer, and an alignment layer supporting a liquid crystal polymer by a film. The thickness of the phase difference plate is also not particularly limited, and is usually 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, and polycarbonate. , polyarylate, polyfluorene, polyethylene terephthalate, polyethylene naphthalate, polyether oxime, polyphenylene sulfide, polyphenylene ether, polyallyl fluorene, polyamine, polyfluorene Imine, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin An olefinic resin) or various binary or ternary copolymers, graft copolymers, blends, and the like. These polymer materials form an alignment (stretching film) by stretching or the like.

Examples of the liquid crystal polymer include various liquid crystal polymers of a main chain type or a side chain type in which a linear atomic group (liquid crystal priming group) which imparts a conjugate property to a liquid crystal alignment property is introduced into a main chain or a side chain of a polymer. . Specific examples of the main chain type liquid crystal polymer include, for example, a nematic alignment polyester liquid crystal polymer, a disc type polymer, or a cholesterol type which is a structure in which a liquid crystal priming unit is bonded to a spacer having a bending property. Polymers, etc. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate or polymalonate as a main chain skeleton, and via a spacer base containing a conjugated atomic group. On the other hand, a liquid crystal original base having a para-substituted cyclic compound unit containing a nematic alignment imparting property is used as a side chain or the like. For the liquid crystal polymer, for example, a solution of a liquid crystal polymer is developed by rubbing a surface of a film of a polyimide film or a polyvinyl alcohol formed on a glass plate, and is oxidized by oblique vapor deposition. The alignment treatment surface of the latter or the like is then subjected to heat treatment to obtain a phase difference plate.

The retardation plate may be, for example, a variety of wave plates or a suitable phase difference corresponding to the purpose of use, for the purpose of compensating for coloring or viewing angle caused by birefringence of the liquid crystal layer, or may be two The above-described phase difference plate is laminated to control optical characteristics such as phase difference.

The phase difference plate can be selected and used corresponding to various uses to satisfy nx=ny>nz'nx>ny>nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, nz> Nx=ny relationship. Furthermore, the so-called ny=nz means 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 satisfying nx>ny>nz, it is preferable to use 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. For example, in a phase difference plate (anode A plate) satisfying nx>ny=nz, it is preferable to use a front phase difference of 100 to 200 nm. For example, in a phase difference plate (cathode A plate) satisfying nz=nx>ny, it is preferable to use a front phase difference of 100 to 200 nm. For example, in a phase difference plate satisfying nx>nz>ny, it is preferable to use a front phase difference of 150 to 300 nm, and an Nz coefficient of more than 0 and 0.7 or less. Further, as described above, for example, nz=ny>nz, nz>nx>ny, or nz>nx=ny can be used.

The transparent protective film can be suitably selected corresponding to the liquid crystal display device to which it is applied. For example, in the case of VA (Vertical Alignment, including MVA (Multi-Domain Vertical Alignment), PVA (Patterned Vertical Alignment)), it is preferable to use a polarizing plate. The transparent protective film of at least one (liquid crystal cell side) has a phase difference. As a specific phase difference, Re = 0 to 240 nm and Rth = 0 to 500 nm are preferable. In the case of a three-dimensional refractive index, it is preferable that nx>ny=nz, nx>ny>nz, nx>nz>ny, nx=ny>nz (anode A plate, biaxial, cathode C plate). In the VA type liquid crystal display device, a combination of an anode A plate and a cathode C plate or a single biaxial film is preferably used. When the polarizing plate is used above and below the liquid crystal cell, the liquid crystal cell can have a phase difference both above and below, or any of the upper and lower transparent protective films can have a phase difference.

For example, in the case of IPS (In-Plane Switching, including FFS (Fringe Field Switching)), one of the polarizing plates can be used with a phase difference or no phase difference. Any of them. For example, in the case where there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference above (the liquid crystal cell side). In the case of having a phase difference, it is preferable that the liquid crystal cell has a phase difference between the upper and lower sides, or that both of the upper and lower sides have a phase difference (for example, the upper side is a biaxial film satisfying the relationship of nx>na>ny). The lower side does not have a phase difference, or the upper side is the anode A plate and the lower side is the anode C plate). In the case of having a phase difference, it is preferable that Re = -500 to 500 nm and Rth = -500 to 500 nm. In terms of three-dimensional refractive index, it is preferable that nx>ny=nz, nx>nz>ny, nz>nx=ny, nz>nx>ny (anode A plate, biaxial, anode C plate).

Further, the film having the phase difference described above may be bonded to a transparent protective film having no phase difference to impart the above-described function to the transparent protective film.

In order to improve the adhesion to the polarizer, the transparent protective film may be subjected to surface modification treatment before the application of 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 suitably formed.

For the surface of the transparent protective film which is not followed by the polarizer, a hard coat layer may be formed or an anti-reflection treatment may be performed, and a treatment for preventing adhesion, diffusion or anti-glare may be employed.

In order to prevent the surface of the polarizing plate from being damaged or the like, the hard coat layer may be a hardened film which is excellent in hardness or sliding properties such as an ultraviolet curable resin such as an acrylic or an oxime. It is formed by being attached to the surface of the transparent protective film. The antireflection treatment is carried out in order to prevent reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like. Further, the anti-adhesive treatment is performed to prevent adhesion to an adjacent layer (for example, a diffusing plate on the backlight side).

Further, the anti-glare treatment is carried out in order to prevent external light from being reflected on the surface of the polarizing plate and to hinder the visibility of the light transmitted through the polarizing plate, and the like, for example, may be formed by a method of sandblasting or embossing. A fine concavo-convex structure is imparted to the surface of the transparent protective film in a suitable manner such as a method of dispersing or a method of blending transparent fine particles. For the fine particles contained in the surface fine uneven structure, for example, cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, or cerium oxide having an average particle diameter of 0.5 to 20 μm can be used. Inorganic fine particles having conductivity, transparent fine particles such as organic fine particles formed of a crosslinked or uncrosslinked polymer. In the case where the surface fine uneven structure is formed, the amount of the fine particles used is usually from 2 to 70 parts by weight, preferably from 5 to 50 parts by weight, per 100 parts by weight of the transparent resin forming the surface fine uneven structure. The anti-glare layer can also serve as a diffusion layer (such as a viewing angle expansion function) for diffusing the polarizing plate through light to expand the viewing angle or the like.

Further, the antireflection layer, the anti-adhesion layer, the diffusion layer or the anti-glare layer may be provided on the transparent protective film itself, or may be separately provided as a separate optical layer different from the transparent protective film.

An adhesive is used in the subsequent treatment of the above polarizer and the transparent protective film. Examples of the adhesive agent include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, an ethylene-based latex, and an aqueous polyester. The above-mentioned adhesive is usually used as an adhesive containing an aqueous solution, and usually contains 0.5 to 60% by weight of a solid. In addition to the above, examples of the adhesive for the polarizer and the transparent protective film include an ultraviolet curable adhesive, an electron beam curable adhesive, and the like. The electron beam-curable polarizing plate exhibits excellent adhesion to the above various transparent protective films by an adhesive. Further, the adhesive used in the present invention may contain a metal compound filler.

In addition, examples of the optical film include a reflector or a reflection-transmissive plate, the retardation plate (including a wave plate of 1/2 or 1/4 or the like), a visual compensation film, a brightness enhancement film, and the like, when a liquid crystal display device or the like is formed. Used as an optical layer. These may be used alone as an optical film, or may be laminated on the above-mentioned polarizing plate in actual use, and one layer or two or more layers may be used.

Particularly preferred is a reflective polarizing plate or a semi-transmissive polarizing plate formed by further laminating a reflecting plate or a semi-transmissive reflecting plate on a polarizing plate, and an elliptically polarizing plate or circularly polarized light formed by further laminating a phase difference plate on the polarizing plate. The plate is further provided with a wide viewing angle polarizing plate formed by a visual compensation film on the polarizing plate, or a polarizing plate formed by further accumulating a brightness enhancing film on the polarizing plate.

The reflective polarizing plate is obtained by providing a reflective layer on a polarizing plate, and is used to form a liquid crystal display device of a type that reflects incident light from a viewing side (display side) for display, and has a built-in backlight The light source is used to make the liquid crystal display device easy to be thinned. The reflective polarizing plate can be formed by a suitable method such as a method of providing a reflective layer containing a metal or the like on one surface of the polarizing plate via a transparent protective layer or the like.

Specific examples of the reflective polarizing plate include a foil containing a reflective metal such as aluminum or a vapor deposited film on one surface of a transparent protective film subjected to a matte treatment, as needed, to form a reflective layer. In addition, the transparent protective film may be formed by containing fine particles to form a fine uneven structure on the surface, and a reflective layer having a fine uneven structure thereon. The reflective layer of the fine uneven structure has the advantage of being able to diffuse incident light by diffuse reflection, thereby preventing directivity or glare, and suppressing unevenness in brightness and the like. Further, the protective film containing fine particles has an advantage that when the incident light and the reflected light thereof are transmitted through the protective film, the light is diffused, and the unevenness of light and dark can be further suppressed. The reflective layer of the fine uneven structure reflecting the fine uneven structure on the surface of the transparent protective film can be directly attached to the transparent protective layer by a vacuum evaporation method, an ion plating method, a sputtering method, or a plating method, for example, in a suitable manner. The surface is formed by methods.

The reflecting plate may be used by providing a reflecting layer on a suitable film of the transparent film instead of being directly provided on the transparent protective film of the polarizing film. Further, since the reflective layer usually contains a metal, it is preferable to prevent the reflectance from being lowered by oxidation, thereby maintaining the initial reflectance for a long period of time, or avoiding the viewpoint of additionally providing a protective layer, etc., and more preferably, the reflective surface is transparent. A form of use in which a protective film, a polarizing plate, or the like is covered.

Further, the semi-transmissive polarizing plate can be obtained by replacing a semi-transmissive reflective layer such as a half mirror which reflects the reflected light in the above-described reflection light and reflects the light. The transflective polarizing plate is usually disposed on the back side of the liquid crystal cell, and can form a liquid crystal display device or the like of the following type: when a liquid crystal display device or the like is used in a relatively bright environment, the transflective polarizing plate is brought from the viewing side ( The incident light is reflected on the display side to display an image, and in a relatively dark environment, an image is displayed using a built-in power source such as a backlight built in the back side of the semi-transmissive polarizing plate. In other words, the semi-transmissive polarizing plate is useful for forming a liquid crystal display device of the type described below, that is, the liquid crystal display device is equivalent to a relatively bright environment, and energy of a light source such as a backlight can be saved, and can be used in a relatively dark environment. Built-in power supply for display.

An elliptically polarizing plate or a circularly polarizing plate formed by further laminating a phase difference plate on a polarizing plate will be described. When a linearly polarized light is converted into elliptically polarized or circularly polarized light, elliptically polarized or circularly polarized light is converted into linearly polarized light, or a polarized direction of linearly polarized light is changed, a phase difference plate or the like is used. In particular, as a phase difference plate that converts linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light, a so-called quarter-wave plate (also referred to as λ/4 plate) is used. A 1/2 wave plate (also known as a λ/2 plate) is commonly used to change the direction of polarization of linearly polarized light.

The elliptically polarizing plate can be effectively used to compensate (prevent) the coloring (blue or yellow) of the super-twisted nematic (STN) type liquid crystal display device due to the birefringence of the liquid crystal layer, thereby performing black and white without the above coloring. The situation shown, etc. Further, the elliptically polarizing plate whose three-dimensional refractive index is controlled can also compensate (prevent) the coloring which occurs when the screen of the liquid crystal display device is viewed from the oblique direction, which is preferable. The circularly polarizing plate can be effectively used, for example, in the case of 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 anti-reflection function.

Further, the elliptically polarizing plate or the reflective elliptically polarizing plate is obtained by laminating a polarizing plate, a reflective polarizing plate, and a phase difference plate in an appropriate combination. The elliptically polarizing plate or the like may be formed by sequentially laminating the liquid crystal display devices in a manufacturing process of a liquid crystal display device by forming a combination of a (reflective) polarizing plate and a phase difference plate, but as described above, When an optical film such as an elliptically polarizing plate is formed, it is excellent in quality stability, laminating workability, and the like, and the manufacturing efficiency of a liquid crystal display device or the like can be improved.

The visual compensation film is used to enlarge the film of the viewing angle so that the image looks clear even when the picture is viewed from a direction that is not slightly inclined perpendicular to the screen of the liquid crystal display device. Such a visual compensation retardation plate includes, for example, an alignment film such as a retardation film or a liquid crystal polymer, or an alignment layer in which a liquid crystal polymer or the like is supported on a transparent substrate. A common phase difference plate is a polymer film having birefringence obtained by uniaxially extending in the plane direction, and a phase difference plate used as a visual compensation film is used for biaxial stretching in the plane direction. a polymer film having birefringence; or a biaxially polarized polymer or a tilted alignment film, which is uniaxially stretched in the plane direction and also has a refractive index in the thickness direction which is extended in the thickness direction. Stretch film and the like. Examples of the oblique alignment film include a method in which a polymer film is followed by a heat shrink film, and a polymer film is stretched or/or shrunk by a contraction force generated by heating, or a liquid crystal is formed. The formation of the polymer oblique alignment, and the like. The material raw material polymer of the phase difference plate is the same as the polymer described in the above retardation plate, and can be used to prevent coloring or the like caused by a change in the viewing angle based on the phase difference of the liquid crystal cell, or to enlarge the visual recognition. A good perspective, etc., is suitable for the purpose.

Further, from the viewpoint of achieving a wide viewing angle of good visibility, it is possible to preferably use an optical alignment film comprising a liquid crystal polymer, particularly an optical fiber of a tilted alignment layer of a disc-type liquid crystal polymer. An optically compensated phase difference plate of the anisotropic layer.

A polarizing plate in which a polarizing plate and a brightness enhancing film are bonded together is usually used on the back side of the liquid crystal cell. The brightness enhancement film exhibits characteristics such as that when a backlight of a liquid crystal display device or the like is incident, or when natural light is incident from the back side, the brightness enhancement film polarizes a specific polarization axis or a specific direction. Circular light is reflected to transmit other light; a polarizing plate formed by laminating a brightness enhancement film and a polarizing plate emits light from a light source such as a backlight to obtain transmitted light of a specific polarization state, and causes light other than the specific polarization state Reflect without passing through. The light reflected on the brightness enhancement film surface is further inverted by a reflection layer or the like provided on the rear side thereof, and then incident into the brightness enhancement film again, and the brightness enhancement film forms part or all of the incident light. By transmitting in a specific polarization state, the amount of light transmitted through the brightness enhancement film is increased, and the polarization which is hard to be absorbed by the polarizer is supplied, so that the amount of light available for liquid crystal display image display or the like is increased, whereby the brightness can be improved. In other words, when a brightness enhancement film is not used, when light is incident from the back side of the liquid crystal cell through the polarizer, the light whose polarization direction does not coincide with the polarization axis of the polarizer is mostly absorbed by the polarizer. Cannot pass the polarizer. That is, although the characteristics of the polarizer used differ depending on the characteristics of the polarizer used, generally about 50% of the light is absorbed by the polarizer, and the amount of light available for liquid crystal image display or the like is correspondingly reduced, resulting in darkening of the image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be incident on the polarizer, and is reflected once on the brightness enhancement film, and further through a reflective layer or the like provided on the rear side of the brightness enhancement film. After the light is inverted, the light is incident on the brightness enhancement film again, and the brightness enhancement film repeats the above operation, so that only the polarization direction of the light reflected and inverted between the two becomes a polarization that can pass through the polarization direction of the polarizer. Since the brightness enhancement film is supplied to the polarizer, the light such as a backlight can be efficiently used for image display of the liquid crystal display device, and the screen can be made bright.

A diffusion plate may be provided between the brightness enhancement film and the reflective layer or the like. The light in a polarized state reflected by the brightness enhancement film advances toward the reflection layer or the like, and the diffusing plate is provided to uniformly diffuse the passed light while eliminating the polarization state thereof to become a non-polarized state. In other words, the operation is performed in such a manner that the light in the natural light state advances toward the reflective layer or the like, is reflected by the reflective layer or the like, and is again incident on the brightness enhancement film through the diffusion plate. In this manner, by providing a diffusing plate that restores the polarized light to the original natural light between the brightness enhancing film and the reflective layer, the brightness of the display screen can be maintained, and the brightness unevenness of the display screen can be reduced, thereby providing uniformity and brightness. Picture. It is considered that by providing the diffusing plate, the number of times of reflection of the initial incident light is moderately increased, and the diffusing function of the diffusing plate is combined with each other, thereby providing a uniform and bright display screen.

As the brightness enhancement film, for example, a multilayer film of a dielectric or a multilayer laminate of a film having a different refractive index anisotropy may be used, and a linear polarized light of a specific polarization axis may be transmitted to allow other light to be transmitted. a characteristic of reflection; and an alignment film such as a cholesteric liquid crystal polymer or a aligning liquid crystal layer supported on the film substrate, exhibiting polarization reflection of any of left-handed or right-handed rotation to make other light Through the characteristics of the person.

Therefore, the brightness enhancement film of the type that transmits the linearly polarized light of the specific polarization axis can directly inject the transmitted light into the polarizing plate in accordance with the polarization axis of the polarizing plate, thereby suppressing the absorption loss caused by the polarizing plate. The transmitted light is transmitted efficiently. On the other hand, a brightness enhancement film of a type that transmits circularly polarized light like a cholesteric liquid crystal layer can also directly emit circularly polarized light into the polarizer, but from the viewpoint of suppressing absorption loss, it is preferable to pass the phase difference. The plate converts the circularly polarized light into a linearly polarized light and then injects it into the polarizing plate. Further, by using a quarter-wave plate as the phase difference plate, circularly polarized light can be converted into linearly polarized light.

A phase difference plate that functions as a quarter-wave plate in a wide-wavelength region such as a visible light region can be obtained, for example, by a phase difference plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm. A phase difference layer exhibiting other phase difference characteristics, for example, a phase difference layer overlapping function which functions as a 1/2 wave plate. Therefore, the phase difference plate disposed between the polarizing plate and the brightness enhancement film may also be a phase difference layer including one or two or more layers.

Further, in the cholesteric liquid crystal layer, by combining the reflection wavelengths to form an arrangement structure in which two or more layers are overlapped, it is possible to obtain a circularly polarized light in a wide wavelength range such as a visible light region, and it is possible to obtain a wide range based on this. The wavelength range is transmitted through circular polarization.

Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separating type polarizing plate. Therefore, a reflective elliptically polarizing plate or a semi-transmissive elliptically polarizing plate formed by combining the above-described reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate may be used.

The optical film formed by laminating the optical layer on the polarizing plate may be formed by sequentially laminating these layers in a manufacturing process of a liquid crystal display device or the like, but having quality stability when an optical film is formed by laminating in advance. It is excellent in assembly workability and the like, and can improve the manufacturing steps of a liquid crystal display device or the like. A suitable attachment mechanism such as an adhesive layer can be used for lamination. When the polarizing plate is connected to another optical layer, an optical axis such as a target can be formed into an appropriate arrangement angle according to the phase difference characteristic of the target.

The optical film-attached glass substrate of the present invention is attached to a glass substrate (liquid crystal cell) to which an adhesive optical film is attached. The adhesive layer of the adhesive optical film is formed of a water-dispersible adhesive containing an emulsifier, and when bonded to a glass substrate, it exhibits high adhesion immediately after adhesion, and is exhibited even in a high-temperature and high-humidity environment. Excellent durability.

The peeling method of the adhesive optical film of the present invention is characterized in that the glass substrate with the optical film is exposed to a temperature of 40 ° C or higher, a relative humidity of 80% or more (condition 1), or a temperature of 50 ° C or more and relative After the humidity is 70% or more (Condition 2), the adhesive optical film is peeled off from the glass substrate.

When the glass substrate with the optical film is exposed to the environment of Condition 1 or Condition 2, the adhesion at the interface between the adhesive layer and the glass substrate is lowered, so that the adhesive optical film can be easily peeled off. Further, even when the adhesive optical film is bonded to the glass substrate for a long time in a high-temperature environment and the adhesion force is 20 N/25 mm or more, the adhesion can be made by exposure to the conditions of Condition 1 or Condition 2. Drop to below 10N/25mm width. Therefore, the glass substrate of a large size can also be excellent in workability and peeling easily. The preferred conditions for the exposure treatment are a temperature of 80 ° C or higher and a relative humidity of 80% or more. Further, the temperature of the exposure treatment is preferably 100 ° C or lower. If the temperature of the exposure treatment exceeds 100 ° C, the liquid crystal display or the like as the adherend may be damaged.

The exposure treatment time is preferably 1 hour or more, more preferably 2 hours or more. When the temperature is less than one hour, the adhesive layer does not sufficiently absorb water, and the adhesion at the interface between the adhesive layer and the glass substrate cannot be sufficiently lowered, so that the glass substrate is damaged or more residual residue is generated during peeling. , resulting in a decline in heavy work. On the other hand, the exposure treatment time is usually 48 hours or less. Since the effect is hardly changed even if it exceeds 48 hours, it is not preferable from the viewpoint of manufacturing efficiency.

Example

Hereinafter, the invention will be specifically described by way of examples, but the invention is not limited to the examples. Furthermore, the parts and % in each case are based on weight.

Manufacturing example 1

(Preparation of monomer pre-emulsion)

88 parts of butyl acrylate, 5 parts of N-cyclohexyl methacrylate, 5 parts of acrylic acid, and mono [poly(oxypropylene) methacrylate] phosphate (the average degree of polymerization of propylene oxide is about 5.0) is added to the vessel. Two parts and 0.03 parts of 3-methacryloxypropyltrimethoxydecane (Shin-Etsu Chemical Co., KBM-503) were mixed and mixed to prepare a monomer mixture. Then, 20 g of a reactive emulsifier (First Industrial Pharmaceutical Co., Ltd., AQUALON HS-1025) and 446 g of ion-exchanged water were added to 500 g of the monomer mixture, and a homogenizer (specialized machine) was used at 5000 (rpm). The temperature was stirred for 5 minutes to carry out emulsification, thereby preparing a monomer pre-emulsion.

(Preparation of water-dispersed acrylic adhesive)

Into a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, 96 g of a monomer pre-emulsion, 275 g of ion-exchanged water, and a reactive emulsifier AQUALON HS-1025 (40 g) were placed, and the reaction vessel was purged with nitrogen. Thereafter, 0.05 g of ammonium persulfate was added and polymerization was carried out at 65 ° C for 1 hour. Then, the temperature in the reaction vessel was raised to 75 ° C, and 0.35 g of ammonium persulfate was added. Thereafter, 869 g of the monomer pre-emulsion was dropwise added to the reaction vessel over 3 hours, and the polymerization was carried out for 3 hours after the dropwise addition. Thereafter, the mixture was subjected to a polymerization reaction at 75 ° C for 3 hours while performing nitrogen substitution to obtain an emulsion having a solid content of 40%. Then, the obtained emulsion was cooled to room temperature, and the pH was adjusted to 8 by adding 10% aqueous ammonia, thereby preparing a water-dispersed acrylic adhesive.

(formation of adhesive layer)

The water-dispersible acrylic pressure-sensitive adhesive was applied to a release film (Mitsubishi Chemical Polyester Film), DIAFOIL MRF38, PET film so that the thickness of the adhesive layer after drying became 23 μm. On one side, and dried at 120 ° C for 2 minutes to form an adhesive layer.

(production of polarizing plate)

A polyvinyl alcohol film having a thickness of 80 μm was stretched to 5 times in an iodine solution at 40 °C. Thereafter, the polyvinyl alcohol film was picked up from the iodine solution, and dried at 50 ° C for 4 minutes to obtain a polarizer. A polarizing plate was produced by laminating a cellulose triacetate film on both surfaces of the polarizer using a polyvinyl alcohol-based adhesive.

(Production of Adhesive Polarizing Plate A)

The water/isopropyl alcohol (1/1 by weight) mixed solution will contain The oxazolyl-based acrylic polymer (Nippon Catalyst (EP), EPOCROS WS-700) was diluted to a solid content of 0.25% to prepare a tackifying coating agent. The adhesion-promoting coating agent was applied to one surface of the above polarizing plate using Meyer bar #5, and dried at 40 ° C for 2 minutes to form a tackified layer. Then, the above adhesive layer was transferred onto the adhesion-promoting layer to form an adhesive polarizing plate A.

(Continues the measurement of force)

The initial adhesion force of the pressure-sensitive polarizing plate A and the adhesion force after 60 ° C / 100 hours were measured by the following methods. As a result, the initial adhesion force was 7.8 (N/25 mm), and the adhesion force after 60 ° C / 100 hours was 36.0 (N / 25 mm).

<initial adhesion>

The adhesive polarizing plate A was cut into a width of 25 mm to obtain a sample, and the sample was crimped to the glass substrate once on the glass substrate (Corning (Corning #1737) by a 2 kg roller, and then attached to the glass substrate, and then It was placed in an autoclave at 50 ° C and 5 atm for 15 minutes, and then cooled to 25 ° C. Then, the sample was peeled from the glass substrate under the conditions of a peeling angle of 180° and a peeling speed of 300 mm/min using a tensile tester, and the adhesion (N/25 mm) at this time was measured.

<60 ° C / adhesion after 100 hours >

The adhesive polarizing plate A was cut into a width of 25 mm to obtain a sample, and the sample was crimped to the glass substrate once on the glass substrate (Corning (Corning #1737) by a 2 kg roller, and then attached to the glass substrate, and then The mixture was placed in an autoclave of 5 atm at 50 ° C for 15 minutes, and then allowed to stand at 60 ° C and a relative humidity of 30% for 100 hours, and then cooled to 25 ° C. Then, the sample was peeled from the glass substrate under the conditions of a peeling angle of 180° and a peeling speed of 300 mm/min using a tensile tester, and the adhesion (N/25 mm) at this time was measured.

Manufacturing Example 2

(Preparation of acrylic polymer solution)

In a reaction vessel equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, 100 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 part of benzoyl peroxide and ethyl acetate were added to prepare a monomer concentration of 80%. Body solution. While stirring the monomer solution, nitrogen gas was introduced for 1 hour to carry out nitrogen substitution, and then the liquid temperature in the reaction vessel was maintained at around 60 ° C and polymerization reaction was carried out for 6 hours to prepare an acrylic polymer solution. The weight average molecular weight of the acrylic polymer was 1.6 million.

(Preparation of acrylic adhesive)

An acrylic pressure-sensitive adhesive was prepared by adding 0.8 parts of a polyfunctional isocyanate compound (Nippon Polyurethane, CORONET L) to 100 parts (solid content) of the above acrylic polymer solution.

(formation of adhesive layer)

The acrylic adhesive was applied to one side of a release film (Mitsubishi Chemical Polyester, DIAFOIL MRF38, PET film) at a temperature of 150 ° C so that the thickness of the adhesive layer after drying became 21 μm. Dry for 3 minutes to form an adhesive layer.

(Production of Adhesive Polarizing Plate B)

The adhesive layer was transferred onto a polarizing plate to form an adhesive polarizing plate B.

(Continues the measurement of force)

The initial adhesion force of the adhesive polarizing plate B and the adhesion force after 60 ° C / 100 hours were measured in the same manner as above. As a result, the initial adhesion force was 14,8 (N/25 mm), and the adhesion after 60 ° C / 100 hours was 31.0 (N / 25 mm).

Manufacturing Example 3

(formation of adhesive layer)

In the water-dispersible acrylic pressure-sensitive adhesive of Production Example 1, a carbodiimide compound (Nippon Textile Co., Ltd., CARBODILITE E-04) as a crosslinking agent was added to obtain an adhesive composition. Further, the amount of the crosslinking agent added was 0.4% by weight based on the solid content of the water-dispersible acrylic pressure-sensitive adhesive. Then, the adhesive composition was applied to one side of a release film (Mitsubishi Chemical Polyester Co., Ltd., DIAFOIL MRF38, PET film) so that the thickness of the adhesive layer after drying became 23 μm. Dry at 120 ° C for 2 minutes to form an adhesive layer.

(Production of Adhesive Polarizing Plate C)

An adhesive polarizing plate C was produced in the same manner as in Production Example 1 except that the above adhesive layer was used.

(Continues the measurement of force)

The initial adhesion force of the adhesive polarizing plate C and the adhesion force after 60 ° C / 100 hours were measured in the same manner as above. As a result, the initial adhesion force was 2.3 (N/25 mm), and the adhesion after 60 ° C / 100 hours was 30 (N / 25 mm) or more.

Manufacturing Example 4

(formation of adhesive layer)

In the water-dispersible acrylic pressure-sensitive adhesive of Production Example 1, a carbodiimide compound (Nissin Textile Co., Ltd., CARBODILITE E-04) as a crosslinking agent was added to obtain an adhesive composition. Further, the amount of the crosslinking agent added was 1.0% by weight based on the solid content of the water-dispersible acrylic pressure-sensitive adhesive. Then, the adhesive composition was applied to one side of a release film (Mitsubishi Chemical Polyester Co., Ltd., DIAFOIL MRF38, PET film) so that the thickness of the adhesive layer after drying became 23 μm. Dry at 120 ° C for 2 minutes to form an adhesive layer.

(Production of Adhesive Polarizing Plate D)

An adhesive polarizing plate D was produced in the same manner as in Production Example 1 except that the above adhesive layer was used.

(Continues the measurement of force)

The initial adhesion force of the pressure-sensitive polarizing plate D and the adhesion force after 60 ° C / 100 hours were measured in the same manner as above. As a result, the initial adhesion force was 2.1 (N/25 mm), and the adhesion force after 60 ° C / 100 hours was 30 (N/25 mm) or more.

Manufacturing Example 5

(formation of adhesive layer)

In the water-dispersible acrylic pressure-sensitive adhesive of Production Example 1, a carbodiimide compound (Nissin Textile Co., Ltd., CARBODILITE E-04) as a crosslinking agent was added to obtain an adhesive composition. Further, the amount of the crosslinking agent added was 1.0% by weight based on the solid content of the water-dispersible acrylic pressure-sensitive adhesive. Then, the adhesive composition was applied to one side of a release film (Mitsubishi Chemical Polyester Co., Ltd., DIAFOIL MRF38, PET film) so that the thickness of the adhesive layer after drying became 30 μm. Dry at 120 ° C for 2 minutes to form an adhesive layer.

(Production of Adhesive Polarizing Plate E)

An adhesive polarizing plate E was produced in the same manner as in Production Example 1 except that the above adhesive layer was used.

(Continues the measurement of force)

The initial adhesion force of the pressure-sensitive polarizing plate E and the adhesion force after 60 ° C / 100 hours were measured in the same manner as above. As a result, the initial adhesion force was 2,6 (N/25 mm), and the adhesion force after 60 ° C / 100 hours was 30 (N/25 mm) or more.

Examples 1 to 12 and Comparative Examples 1 to 3

The adhesive polarizing plate A was cut into a width of 25 mm to obtain a sample, and the sample was re-attached to the glass substrate on a glass substrate (Corning (Corning #1737) by a 2 kg roller, and then attached to the glass substrate, and then The autoclave was placed at 50 ° C for 5 minutes in an autoclave at 15 ° C for 15 minutes, and then left at 60 ° C for 30 hours in a relative humidity of 30%, and then cooled to 25 ° C. Then, the exposure treatment was carried out under the conditions disclosed in Table 1, and cooled to 25 °C. Then, the sample was peeled from the glass substrate under the conditions of a peeling angle of 180° and a peeling speed of 300 mm/min using a tensile tester, and the adhesion force (N/25 mm) at the time of peeling was measured.

Comparative Examples 4 and 5

The adhesion force (N/25 mm) was measured in the same manner as above except that the adhesive polarizing plate B was used.

Example 13, 14

The adhesion force (N/25 mm) was measured in the same manner as above except that the adhesive polarizing plate C was used.

Examples 15, 16

The adhesion force (N/25 mm) was measured in the same manner as above except that the adhesive polarizing plate D was used.

Examples 17, 18

The adhesion force (N/25 mm) was measured in the same manner as above except that the adhesive polarizing plate E was used.

Claims (3)

A method for peeling an adhesive optical film, which is obtained by peeling an adhesive optical film from a glass substrate with an optical film to which an adhesive optical film is adhered on a glass substrate, and is characterized in that an adhesive of an adhesive optical film is used. The layer is formed of a water-dispersible adhesive, and the peeling method is performed by exposing the glass substrate with the optical film to an environment having a temperature of 80° C. or more and a relative humidity of 80% or more for 4 hours or more, and peeling off the adhesion from the glass substrate. Optical film. The method of peeling an adhesive optical film according to claim 1, wherein the adhesive optical film has an adhesion-promoting layer between the optical film and the adhesive layer. An adhesive optical film for use in a method for peeling an adhesive optical film according to claim 1 or 2, comprising an adhesive layer formed of a water-dispersible adhesive on at least one side of the optical film, The adhesive film is attached to a glass substrate, and after being exposed to an environment having a temperature of 60 ° C and a relative humidity of 30% for 100 hours, the adhesive force is 20 N/25 mm or more, and the temperature is exposed. After 4 hours or more in an environment of 80 ° C or more and a relative humidity of 80% or more, the adhesion is 1.2 N / 25 mm or less.