TWI418601B - Adhesive composition for optical film, adhesive layer for optical film, manufacturing method thereof, adhesive type optical film, and image display device - Google Patents

Description

Adhesive composition for optical film, adhesive layer for optical film, method for producing the same, adhesive optical film, and image display device

The present invention relates to an adhesive composition for an optical film which is required to be transparent, and an adhesive layer for an optical film formed by the adhesive composition and a method for producing the same. Moreover, the present invention relates to an adhesive optical film in which the above-mentioned adhesive layer for an optical film is formed on at least one surface of an optical film. Further, the present invention relates to an image display device such as a liquid crystal display device or an organic EL display device using the above-described adhesive optical film. As the optical film, a polarizing plate, a phase difference plate, an optical compensation film, a brightness improving film, and the like can be used.

In the case of a liquid crystal display or the like, it is indispensable to arrange a polarizing element on both sides of the liquid crystal cell in view of the image forming method, and a polarizing plate is usually attached. Further, in addition to the polarizing plate on the liquid crystal panel, various optical elements can be used to improve the display quality of the display. For example, a phase difference plate for preventing coloration, a viewing angle widening film for improving the viewing angle of the liquid crystal display, and a brightness improving film for improving the contrast of the display can be used. These films are collectively referred to as optical films.

When the above optical film is attached to a liquid crystal cell, an adhesive is usually used. Further, in order to reduce the optical loss, the optical film and the liquid crystal cell or the optical film are usually adhered to each other using an adhesive. In this case, there is an advantage that the drying step is not required when the optical film is fixed. Therefore, it is generally used as an adhesive optical film in which an adhesive is provided as an adhesive layer on one side of the optical film. Further, a spacer (release film) is usually bonded to the adhesive layer.

The required characteristics required for the above-mentioned adhesive are such that when the optical film is bonded to the liquid crystal cell, the optical film can be peeled off from the liquid crystal panel even when the bonding position or the foreign matter is embedded in the bonding surface. The liquid crystal cell is reused. In the peeling step, re-peelability (secondary workability) in which the optical film does not remain in the slurry and is easily peeled off from the liquid crystal panel is required. In particular, in recent years, in addition to the previous panel fabrication steps, the use of a thin liquid crystal panel using a chemically etched glass has increased, and secondary workability and workability of the optical film of the thin liquid crystal panel have become difficult.

The optical adhesive is usually formed into an adhesive layer on an optical film, and then wound into a roll shape to be subjected to punching. Further, an optical adhesive is used together with an acrylic polymer as a base polymer. As the crosslinking agent, for example, an isocyanate compound is exemplified, but it takes time to form (age) the isocyanate compound in the adhesive layer, and it takes a long time until the transportation. When the processing is directly performed without performing the above-described aging, the workability is deteriorated due to the dirt or the defect of the adhesive. In addition, defects such as scratches may occur during aging. As described above, the optical adhesive is required to have processability capable of processing without causing dirt or defects of the adhesive.

Further, as a crosslinking agent used for an optical adhesive, a peroxide has been proposed. The crosslinking is terminated by the use of a peroxide in connection with the hardening step after drying, thus having the advantage of not requiring aging time. However, when a peroxide is used, the peeling force with respect to the spacer is remarkably increased, and when the spacer is peeled off (release film), there is a problem that the peeling becomes heavy and the production line is stopped. In addition, in recent years, as the thickness of the optical film has progressed, it is required to be lightly peelable with respect to the spacer and to have good workability as compared with the prior art.

Further, the above-mentioned adhesive is required to have no endurance test by heating or humidification which is usually performed as an environmental acceleration test, and the adhesive is caused by the adhesive.

In the prior art, a method of containing a plasticizer or an oligomer component in an acrylic polymer which is a base polymer of an acrylic pressure-sensitive adhesive has been proposed as a method for eliminating the problem of the secondary workability of the liquid crystal panel (Patent Document 1). . However, this acrylic adhesive has not been able to satisfy the secondary workability with respect to the above-described thin liquid crystal panel, the workability as an adhesive optical film, and workability with respect to a spacer.

In addition to the above, as the acrylic pressure-sensitive adhesive used in the optical film, a peroxide is added to the acrylic polymer (Patent Document 2); and as a monomer component of the acrylic polymer, In addition to the alkyl (meth) acrylate, a monomer having a hydroxyl group in the molecule and a monomer having a functional group such as a carboxyl group, a guanamine group, or an amine group in the molecule is used (Patent Documents 3 and 4); The monomer component of the acrylic polymer, in addition to the alkyl (meth)acrylate, is also a nitrogen-containing monomer such as a monomer containing a quinone imine group or a monomer containing a guanamine group, and further used. Oxide and isocyanate compounds (Patent Document 5). However, the acrylic adhesives disclosed in these patent documents are those which can improve the initial durability, but do not satisfy the long-term durability, and do not sufficiently satisfy the secondary workability, and are excellent in workability as an adhesive optical film. The workability of the spacer.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-329837

Patent Document 2: Japanese Patent Laid-Open No. 2006-183022

Patent Document 3: Japanese Patent Laid-Open Publication No. 2004-091499

Patent Document 4: Japanese Patent Laid-Open Publication No. 2004-091500

Patent Document 5: Japanese Patent Laid-Open No. 2007-138147

An object of the present invention is to provide an adhesive composition for an optical film which can form an adhesive layer, which is capable of satisfying secondary workability in which an optical film can be easily peeled off from a liquid crystal panel without leaving a paste. Further, after the adhesive layer is formed on the optical film, the workability of processing without causing dirt or defects of the adhesive can be performed. Further, it is an object of the invention to provide an adhesive composition for an optical film which can form an adhesive layer which is excellent in workability with respect to a spacer.

Moreover, an object of the present invention is to provide an adhesive layer formed by the above-described adhesive composition for an optical film and a method for producing the same. Further, an object of the present invention is to provide an adhesive optical film having the adhesive layer, and to provide an image display device using the above adhesive optical film.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found the following adhesive composition for an optical film, and have completed the present invention.

In other words, the present invention relates to an adhesive composition for an optical film, which comprises a (meth)acrylic polymer and a peroxide as a crosslinking agent, and the (meth)acrylic polymer It is a monomer unit containing 45 to 99.99% by weight of an alkyl (meth)acrylate and 0.01 to 2% by weight of a monomer having a tertiary amino group, and is 100 parts by weight based on the (meth)acrylic polymer. The above peroxide is 0.01 to 2 parts by weight.

In the above-mentioned (meth)acrylic polymer, 100 parts by weight of the (meth)acrylic polymer is further contained in an amount of 0.01 to 2 parts by weight based on the isocyanate crosslinking agent.

It is preferable that the adhesive composition for an optical film contains 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acryl-based polymer.

Preferably, in the above adhesive composition for an optical film, the (meth)acrylic polymer further contains 0.01 to 5% by weight of a carboxyl group-containing monomer and/or 0.01 to 5% by weight of a hydroxyl group-containing monomer. Monomer unit.

In the above adhesive composition for an optical film, as the monomer having a tertiary amino group, N,N-dimethylaminoethyl (meth)acrylate and/or N,N-dimethyl is preferred. Aminopropyl (meth) acrylamide.

It is preferred that the (meth)acrylic polymer has a weight average molecular weight of from 1,000,000 to 3,000,000 in the adhesive composition for an optical film.

Moreover, the present invention relates to an adhesive layer for an optical film which is formed from the above-described adhesive composition for an optical film.

It is preferred that the adhesive layer for the optical film has a gel fraction of 50 to 95% by weight.

Moreover, the present invention relates to a method for producing an adhesive layer for an optical film described above, which comprises applying the above-mentioned adhesive composition for an optical film to a substrate at a temperature of 70 to 160 ° C for a time of 30 〜 It was treated in 240 seconds to harden it.

Further, the present invention relates to an adhesive optical film characterized in that an adhesive layer formed of the above-mentioned optical film adhesive composition is formed on at least one side of the optical film.

Further, the present invention relates to an image display device using at least one of the above-mentioned adhesive optical films.

The above-mentioned adhesive composition for an optical film of the present invention contains, as a base polymer of an adhesive, a (meth)acrylic polymer, a monomer having a tertiary amino group as a monomer in a small amount of 0.01 to 2% by weight. unit. By using the adhesive composition for an optical film having such a configuration, an adhesive layer having the following properties can be formed: workability and secondary workability can be improved, and the adhesive or the dirt of the adhesive during processing can be suppressed, and even if the optical is When the film is peeled off from a thin liquid crystal panel, in particular, a liquid crystal panel using a chemically etched glass, the paste can be easily removed without leaving a paste. Further, the adhesive layer can be peeled off from the liquid crystal panel without breaking the optical film. As a result, the liquid crystal panel can be effectively reused without breaking the thin optical film.

The tertiary amino group-containing monomer contained in the above-mentioned small amount in the (meth)acrylic polymer improves the adhesion of the adhesive layer after the adhesive layer is formed by the crosslinking reaction using the crosslinking agent. Link stability. When the peroxide is used in the above-specified ratio as the crosslinking agent, the crosslinking stability can be particularly improved by using a monomer having a tertiary amino group. Further, as the crosslinking agent, an isocyanate compound can be suitably used in addition to the peroxide. Further, a decane coupling agent can be used within the above-specified range. In particular, when an isocyanate compound or a decane coupling agent is used together with a peroxide, the above-mentioned crosslinking stability is improved, and secondary workability and workability can be improved. In the prior art, an adhesive layer formed of an adhesive composition prepared with an additive such as a decane coupling agent is scattered from the adhesive layer over time due to a decane coupling agent or the like, and thus it is difficult to stably maintain the characteristics of the adhesive layer. . According to the adhesive composition of the present invention, the residual of the decane coupling agent in the adhesive layer can be increased over time, the stability of the product characteristics is improved, and the long-term durability can be satisfied.

Further, in the (meth)acrylic polymer, a monomer having a carboxyl group or a monomer having a hydroxyl group is contained as a monomer unit, whereby durability can be improved and secondary workability can be improved. A (meth)acrylic polymer containing a carboxyl group-containing monomer or a hydroxyl group-containing monomer as a copolymerization component can be improved in secondary workability due to an acid-base interaction or a hydrogen bond of the copolymerization components. At the same time, durability is improved, and problems such as floating or peeling of the adhesive can be suppressed under heating or humidification conditions.

Further, by the adhesive composition of the present invention, a peroxide is used as a crosslinking agent for the tertiary amine group introduced into the (meth)acrylic polymer, thereby forming a advantage as a peroxide crosslinking. The adhesive layer having good productivity and workability can suppress the rise of the peeling force to the spacer (release film). Therefore, the adhesive layer can lightly peel the spacer with respect to the spacer even with the lapse of time, the workability is improved, and the production efficiency can be further improved. In the (meth)acrylic polymer, the combination of the tertiary amine group and the peroxide is faster, and the (meth)acrylic acid is compared with the crosslinking reaction of the spacer with the (meth)acrylic polymer. The cross-linking of the polymers to each other is more preferable, whereby the increase in the peeling force to the spacer can be suppressed.

The adhesive composition for an optical film of the present invention uses a (meth)acrylic polymer containing 45 to 99.99% by weight of an alkyl (meth)acrylate and 0.01 to 2% by weight of a monomer having a tertiary amino group. As a base polymer.

As the alkyl (meth)acrylate, the alkyl group of the alkyl (meth)acrylate has a carbon number of about 2 to 18. The alkyl group may be any of a straight chain and a branched chain. The average carbon number of the above alkyl group is preferably 2 to 14, more preferably the average carbon number is 3 to 12, and even more preferably, the average carbon number is 4 to 9. Further, (meth) acrylate means acrylate and/or methacrylate, and has the same meaning as (meth) of the present invention.

Specific examples of the alkyl (meth)acrylate include ethyl (meth)acrylate, n-butyl (meth)acrylate, second butyl (meth)acrylate, and third (meth)acrylate. Butyl ester, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, (methyl) Isoamyl acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, (meth)acrylic acid Anthracene ester, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, isomyristyl (meth)acrylate, (meth)acrylic acid Tridecyl ester, n-tetradecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and the like. Among them, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like can be exemplified, and these may be used singly or in combination.

In the present invention, the alkyl (meth)acrylate is 45 to 99.99% by weight based on the total monomer component of the (meth)acrylic polymer. It is preferably 85 to 99.99% by weight, more preferably 87 to 99.99% by weight, still more preferably 90 to 99.99% by weight, still more preferably 98 to 99.99% by weight. When the amount of the above (meth)acrylic monomer is too small, it becomes insufficient in adhesion and is not preferable.

Further, examples of the monomer having a tertiary amino group include a monomer having a tertiary amino group and a (meth)acryl fluorenyl group. As the tertiary amino group, a tertiary aminoalkyl group is preferred. Examples of the tertiary amino group-containing monomer include N,N-dialkylaminoalkyl(meth)acrylamide and N,N-dialkylaminoalkyl (meth)acrylate. Specific examples of the monomer having a tertiary amino group include, for example, N,N-dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl (methyl). Acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide, (meth)acrylic acid N,N - dimethylaminoethyl ester, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-diethyl Aminopropyl (meth) acrylamide. Among the monomers having a tertiary amino group, preferred is N,N-dimethylaminoethyl (meth)acrylate and/or N,N-dimethylaminopropyl (methyl). Acrylamide.

Further, even a monomer other than a monomer containing a nitrogen-containing monomer and containing a tertiary amino group, such as maleimide, N-cyclohexylmaleimide, N-phenyl Malaya Maleic imine monomer such as amine; N-(methyl) propylene oxymethylene succinimide or N-(methyl) propylene fluorenyl-6-oxyhexamethylene amber Amber quinone imine monomer such as amine, N-(methyl) propylene decyl-8-oxy octamethylene succinimide; (meth) acrylamide, N, N-dimethyl (A) Acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-A N-substituted amide-based monomers such as oxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, etc.; tert-butylaminoethyl (meth) acrylate, etc. Monomer having a secondary amine group; diacetone (meth) acrylamide, N-vinylacetamide, N, N'-methylenebis(meth) acrylamide, N-vinyl hexene It is also difficult to improve secondary processability and processing, such as guanamine, N-propylene decylmorpholine, N-propenyl hydrazinopyridine, N-methyl propylene hydrazinopiperidine, N-propenylpyridyl pyrrolidine. .

The monomer having a tertiary amino group is used in a ratio of 0.01 to 2% by weight based on the total amount of the monomer component forming the (meth)acrylic polymer. The proportion of the monomer having a tertiary amino group is preferably from 0.01 to 1.5% by weight, more preferably from 0.01 to 1% by weight, still more preferably from 0.01 to 0.5% by weight, still more preferably from 0.05 to 0.45% by weight, Further preferably, it is 0.05 to 0.2% by weight. When the proportion of the monomer having a tertiary amino group is less than 0.01% by weight, the crosslinking stability of the adhesive layer is poor, the secondary workability and workability are not satisfied, and the durability is not considered. Further, crosslinking is not sufficiently promoted, and it is difficult to reduce the gel fraction of the adhesive layer, and the peeling property to the spacer is high, which is not preferable. On the other hand, from the viewpoint of secondary workability and durability, the ratio of the monomer having a tertiary amino group is too large, and the content thereof may be controlled to 2% by weight or less to make the adhesion layer of the adhesive layer Do not improve.

In addition to the above monomers, a monomer containing a carboxyl group-containing monomer and/or a hydroxyl group-containing monomer can improve durability and the like as a monomer component for forming the (meth)acrylic polymer. It is particularly preferred to use a hydroxyl group-containing monomer.

As the carboxyl group-containing monomer, a polymerizable functional group having an unsaturated double bond such as a (meth)acryl fluorenyl group or a vinyl group and having a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Preferred among them is (meth)acrylic acid, and particularly preferred is acrylic acid.

The carboxyl group-containing monomer is used in a proportion of 0.01 to 5% by weight based on the total amount of the monomer components forming the (meth)acrylic polymer. The proportion of the carboxyl group-containing monomer is preferably from 0.01 to 2% by weight, more preferably from 0.01 to 1% by weight, still more preferably from 0.05 to 0.5% by weight. In order to improve durability, it is preferred to contain 0.01% by weight or more of a carboxyl group-containing monomer. On the other hand, when the ratio of the carboxyl group-containing monomer exceeds 5% by weight, the adhesion is enhanced, the peeling becomes heavy, and the secondary workability cannot be satisfied, which is not preferable.

As the hydroxyl group-containing monomer, a polymerizable functional group having an unsaturated double bond such as a (meth)acryl fluorenyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (meth)acrylic acid 4- Hydroxybutyl ester, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, etc. Hydroxyalkyl acrylate, hydroxyethyl (meth) acrylamide; additionally available as (4-hydroxymethylcyclohexyl)methyl acrylate, N-hydroxymethyl (meth) acrylamide, N -hydroxy(meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, caprolactone adduct of acrylic acid, (methyl Polyethylene glycol acrylate, polypropylene glycol (meth) acrylate, and the like. Preferred among these are hydroxyalkyl (meth)acrylates.

The hydroxyl group-containing monomer is used in a proportion of 0.01 to 5% by weight based on the total amount of the monomer components forming the (meth)acrylic polymer. The proportion of the hydroxyl group-containing monomer is preferably from 0.01 to 2% by weight, more preferably from 0.01 to 1.5% by weight, still more preferably from 0.01 to 1% by weight, still more preferably from 0.05 to 0.5% by weight. In order to improve durability, it is preferred to contain 0.01% by weight or more of a hydroxyl group-containing monomer. In particular, when an isocyanate crosslinking agent is used as the crosslinking agent, it is preferred to contain 0.01% by weight or more of a hydroxyl group-containing monomer in order to secure a crosslinking point with the isocyanate group. On the other hand, when the ratio of the hydroxyl group-containing monomer exceeds 5% by weight, the adhesion is enhanced, the peeling becomes heavy, and the secondary workability cannot be satisfied, which is not preferable.

The monomer component forming the (meth)acrylic polymer may be used in the range of 50% by weight or less based on the total amount of the monomers, in addition to the above monomers, within the range not impairing the object of the present invention. Monomers other than the above. The proportion of any monomer is preferably 48% by weight or less, more preferably 45% by weight or less. Examples of the optional monomer include an aromatic ring-containing monomer having a polymerizable functional group of an unsaturated double bond such as a (meth)acryl fluorenyl group or a vinyl group and having an aromatic ring. Specific examples of the aromatic ring-containing monomer include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, and (methyl). 2-Naphthylethyl acrylate, 2-(4-methoxy-1-naphthalenyloxy)ethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxy (meth)acrylate Diethylene glycol ester, thiol (meth) acrylate, phenyl (meth) acrylate, polystyryl (meth) acrylate, and the like.

Examples of the monomer other than the above include an acid anhydride group-containing monomer such as maleic anhydride or itaconic anhydride; styrenesulfonic acid or allylsulfonic acid, and 2-(methyl)acrylamidamine-2-methyl. a sulfonic acid group-containing monomer such as propanesulfonic acid, (meth) acrylamide propyl sulfonic acid, sulfopropyl (meth) acrylate, (meth) propylene phthaloxy naphthalene sulfonic acid; 2-hydroxyethyl a phosphate group-containing monomer such as acryloyl phosphate; a (meth)acrylic acid alkoxyalkyl ester monomer such as methoxyethyl (meth)acrylate or ethoxyethyl (meth)acrylate; .

Further, a vinyl monomer such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene or N-vinyl caprolactam may be used; and a ring containing a glycidyl (meth)acrylate or the like may be used. Acrylic monomer such as oxy group; methacrylate monomer such as methoxyethylene glycol (meth)acrylate or methoxypolypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate An acrylate-based monomer such as fluoro(meth)acrylate, polyoxy(oxy)(meth)acrylate or 2-methoxyethyl acrylate.

Further, examples of the copolymerizable monomer other than the above include a decane-based monomer containing a ruthenium atom. Examples of the decane-based monomer include 3-propenyloxypropyltriethoxydecane, vinyltrimethoxydecane, vinyltriethoxydecane, and 4-vinylbutyltrimethoxydecane. - vinyl butyl triethoxy decane, 8-vinyl octyl trimethoxy decane, 8-vinyl octyl triethoxy decane, 10-methyl propylene decyl decyl trimethoxy decane, 10 - propylene decyl decyl trimethoxy decane, 10-methyl propylene decyl decyl triethoxy decane, 10-propylene decyl decyl triethoxy decane, and the like.

The (meth)acrylic polymer of the present invention usually uses a polymer having a weight average molecular weight of 1,000,000 to 3,000,000. When considering durability, particularly heat resistance, it is preferred to use a polymer having a weight average molecular weight of 1.5 million to 2.5 million. Further better is 1.7 million to 2.5 million, and further better is 1.8 million to 2.5 million. If the weight average molecular weight is less than 1.5 million, it is not preferable from the viewpoint of heat resistance. Further, when the weight average molecular weight is more than 3,000,000, it is not preferable in terms of adhesion and adhesion. The weight average molecular weight is a value calculated by GPC (gel permeation chromatography) and calculated by polystyrene conversion.

A known production method such as solution polymerization, bulk polymerization, emulsion polymerization, or various radical polymerization can be suitably selected for the production of such a (meth)acrylic polymer. Further, the obtained (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

Further, in the solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific solution polymerization example, a polymerization initiator is added under an inert gas stream such as nitrogen, and the reaction is usually carried out under the reaction conditions of about 50 to 70 ° C for about 5 to 30 hours.

The polymerization initiator, the chain transfer agent, the emulsifier, and the like used in the radical polymerization are not particularly limited, and can be appropriately selected and used. Further, the weight average molecular weight of the (meth)acrylic polymer can be controlled by the amount of the polymerization initiator, the amount of the chain transfer agent used, and the reaction conditions, and the appropriate amount can be adjusted depending on the type of the polymer.

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'-couple Nitrogen di(N,N'-dimethylene isobutyl fluorene), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine hydrate (Wako Pure Chemicals) Manufactured by the company, VA-057) and other azo-based initiators, persulfate such as potassium persulfate or ammonium persulfate, di(2-ethylhexyl) peroxydicarbonate and di-dicarbonate (4- Tributylcyclohexyl)ester, dibutyl butyl dicarbonate, tert-butyl peroxy neodecanoate, third hexyl peroxypivalate, tert-butyl peroxypivalate, peroxidation February laurel, di-n-octyl peroxide, peroxy-2-ethylhexanoate (1,1,3,3-tetramethylbutyl) ester, bis(4-methylbenzhydryl) peroxide, Peroxides such as benzamidine peroxide, tert-butyl peroxyisobutyrate, 1,1-di(trihexylperoxy)cyclohexane, tert-butyl hydroperoxide, hydrogen peroxide, etc. Starting agent, persulfate and hydrogen sulfite A combination of sodium, a combination of a peroxide and sodium ascorbate, and the like, and a redox initiator of a peroxide and a reducing agent are combined, but are not limited thereto.

The above polymerization initiators may be used singly or in combination of two or more kinds, and the content as a whole is preferably about 0.005 to 1 part by weight, more preferably about 0.02 to 0.5 part by weight, per 100 parts by weight of the monomer.

Further, when the (meth)acrylic polymer having the above weight average molecular weight is produced by using, for example, 2,2'-azobisisobutyronitrile as a polymerization initiator, 100 parts by weight relative to the total amount of the monomer components. The amount of the polymerization initiator to be used is preferably from about 0.06 to 0.2 parts by weight, more preferably from about 0.08 to about 0.175 parts by weight.

Examples of the chain transfer agent include dodecyl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, mercaptoacetic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propene. Alcohol, etc. The chain transfer agent may be used singly or in combination of two or more kinds, and the content as a whole is about 0.1 part by weight or less based on 100 parts by weight of the total of the monomer components.

Further, examples of the emulsifier used in the case of emulsion polymerization include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkyl. Anionic emulsifier such as sodium phenyl ether sulfate, nonionic emulsification such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, or polyoxyethylene-polyoxypropylene block polymer Agents, etc. These emulsifiers may be used singly or in combination of two or more.

Further, as the reactive emulsifier, as an emulsifier to introduce a radical polymerizable functional group such as an acryl group or an allyl ether group, specifically, for example, AQUALON HS-10, HS-20, KH-10, BC-05 BC-10, BC-20 (all of which are manufactured by First Industrial Pharmaceutical Co., Ltd.), ADEKA REASOAP SE10N (made by Asahi Chemical Co., Ltd.), etc. Since the reactive emulsifier enters the polymer chain after polymerization, the water resistance is improved. The amount of the emulsifier used is preferably from 0.3 to 5 parts by weight, based on 100 parts by weight of the total of the monomer components, and more preferably from 0.5 to 1 part by weight from the viewpoint of polymerization stability or mechanical stability.

Further, the adhesive composition of the present invention contains a peroxide as a crosslinking agent.

As the peroxide of the present invention, if a radical active species is generated by heating or light irradiation to crosslink the base polymer of the adhesive composition, it can be suitably used, taking into consideration operability or stability. It is preferred to use a peroxide having a one-minute half-life temperature of from 80 ° C to 160 ° C, more preferably a peroxide having a one-minute half-life temperature of from 90 ° C to 140 ° C. When the one-minute half-life temperature is too low, the reaction is carried out during storage before coating drying, and the viscosity becomes high and the coating cannot be applied. On the other hand, if the one-minute half-life temperature is too high, there is a temperature at which the crosslinking reaction is carried out. When the temperature is high, a side reaction occurs, and the unreacted peroxide remains excessively, and the crosslinking is carried out over time, which is not preferable.

Examples of the peroxide used in the present invention include di(2-ethylhexyl)peroxydicarbonate (1 minute half-life temperature: 90.6 ° C), and di(4-tert-butylcyclohexyl)peroxydicarbonate. ) ester (1 minute half-life temperature: 92.1 ° C), dibutyl phthalate dihydrate (1 minute half-life temperature: 92.4 ° C), peroxy neodecanoic acid tert-butyl ester (1 minute half-life temperature: 103.5 ° C), Third hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), third butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilaurin peroxide (1 minute half-life temperature: 116.4) °C), di-n-octyl peroxide (1 minute half-life temperature: 117.4 ° C), peroxy-2-ethylhexanoic acid (1,1,3,3-tetramethylbutyl) ester (1 minute half-life temperature: 124.3 ° C), bis(4-methylbenzhydrazide) (1 minute half-life temperature: 128.2 ° C), benzoic acid peroxide (1 minute half-life temperature: 130.0 ° C), isobutyric acid peroxide Ester (1 minute half-life temperature: 136.1 ° C), 1,1-di(trihexylperoxy)cyclohexane (1 minute half-life temperature: 149.2 ° C), and the like. Among them, in terms of excellent self-crosslinking reaction efficiency, it is preferred to use di(4-tert-butylcyclohexyl)peroxycarbonate (1 minute half-life temperature: 92.1 ° C), and dilaurin peroxide (1) Minute half-life temperature: 116.4 ° C), benzoquinone peroxide (1 minute half-life temperature: 130.0 ° C) and the like.

Further, the half-life of the peroxide is an index indicating the decomposition rate of the peroxide, and means the time when the residual amount of the peroxide is half. A related content which is useful for obtaining a half-life decomposition temperature or a half-life time at an arbitrary temperature at any time is disclosed in a manufacturer catalog, etc., for example, disclosed in the "Organic Peroxide Catalogue" of Nippon Oil & Fat Co., Ltd. Edition (May 2003) "etc.

The peroxide may be used singly or in combination of two or more kinds, and the content of the peroxide is preferably 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. It is contained in an amount of 0.04 to 1.5 parts by weight, more preferably 0.05 to 1 part by weight. When the amount is less than 0.01 part by weight, the crosslinking formation is insufficient, the crosslinking stability cannot be improved, and the secondary workability and workability are not preferable. On the other hand, when it exceeds 2 parts by weight, the peeling property from the spacer is difficult, or the adhesive layer is hardened due to durability, and peeling is likely to occur, which is not preferable.

Further, when a peroxide is used as a polymerization initiator, residual peroxide which is not used in the polymerization reaction may be used for the crosslinking reaction. In this case, the residual amount may be quantified and added again as needed. It is used as a predetermined amount of peroxide.

In addition, as a measuring method of the amount of decomposition of the peroxide remaining after the reaction treatment, for example, it can be measured by HPLC (High Performance Liquid Chromatography).

More specifically, for example, about 0.2 g of the reaction-treated adhesive composition may be taken out at a time, immersed in 10 ml of ethyl acetate, and shake-extracted at 25 ° C, 120 rpm for 3 hours using a vibrating machine, and then at room temperature. Allow to stand for 3 days. Then, 10 ml of acetonitrile was added, and the mixture was shaken at 25 ° C and 120 rpm for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into HPLC for analysis, and this was used as the amount of peroxide after the reaction treatment. .

Further, as the crosslinking agent, an organic crosslinking agent or a polyfunctional metal chelate compound can be used together with the peroxide. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, and an imide crosslinking agent. A polyfunctional metal chelate is a compound in which a polyvalent metal is covalently bonded or coordinately bonded to an organic compound. Examples of the polyvalent metal atom 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. . Examples of the atom in the organic compound which is a covalent bond or a coordinate bond 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. Among the above crosslinking agents, an isocyanate crosslinking agent is preferred.

Examples of the isocyanate crosslinking agent include aromatic isocyanates such as toluene diisocyanate and benzodimethyl diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, for example, lower aliphatic polyisocyanates such as dibutyl isocyanate or hexamethylene diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, and isophor are mentioned. An alicyclic isocyanate such as keto diisocyanate, an aromatic diisocyanate such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, benzodimethyl diisocyanate or polymethylene polyphenyl isocyanate , trimethylolpropane/toluene diisocyanate trimer adduct (manufactured by Japan Polyurethane Industry Co., Ltd., trade name Coronate L), trimethylolpropane / diisocyanate hexamethylene diester adduct ( Isocyanate adduct, polyether polyisocyanate, polyester polyglycolate, manufactured by Japan Polyurethane Industry Co., Ltd., trade name: Coronate HL), diisocyanate diisocyanate (manufactured by Japan Polyurethane Industry Co., trade name: Coronatel HX) An isocyanate and an addition product thereof to various polyols, a polyisocyanate which is polyfunctionalized such as an isocyanurate bond, a biuret bond or an allophanate bond.

The isocyanate-based crosslinking agent may be used singly or in combination of two or more kinds, and the content of the entire (meth)acrylic polymer is preferably 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acryl-based polymer. The above isocyanate crosslinking agent is more preferably contained in an amount of from 0.04 to 1.5 parts by weight, still more preferably from 0.05 to 1 part by weight. If it is less than 0.01 part by weight, the cohesive force is insufficient and it is not preferable. On the other hand, when it exceeds 2 parts by weight, peeling is likely to occur in the durability test, which is not preferable.

When the adhesive layer is formed by the above-mentioned crosslinking agent, when a peroxide or an isocyanate crosslinking agent is used as a crosslinking agent in forming an adhesive layer, it is necessary to adjust the addition amount of the crosslinking agent, and the crosslinking treatment is fully considered. The effect of temperature or cross-linking processing time.

For the adjustment of the crosslinking treatment temperature or the crosslinking treatment time, for example, it is preferred to set the decomposition amount of the peroxide contained in the adhesive composition to 50% by weight or more, more preferably 60% by weight or more. More preferably, it is set to 70% by weight or more. When the amount of decomposition of the peroxide is less than 50% by weight, the amount of the peroxide remaining in the adhesive composition increases, and the crosslinking reaction may occur over time after the crosslinking treatment, which is not preferable.

More specifically, for example, at a cross-linking treatment temperature of 1 minute half-life temperature, the decomposition amount of the peroxide is 50% by weight after 1 minute, and the decomposition amount of the peroxide after 2 minutes is 75% by weight, which takes 1 minute. The above cross-linking processing time. Further, for example, if the half-life (half-life) of the peroxide at the crosslinking treatment temperature is 30 seconds, a crosslinking treatment time of 30 seconds or more is required, and for example, a peroxide at a crosslinking treatment temperature is required. If the half-life (half-life) is 5 minutes, a cross-linking treatment time of 5 minutes or more is required.

As described above, depending on the peroxide to be used, assuming that the crosslinking treatment temperature or the crosslinking treatment time is once proportional to the peroxide, the half life (half-life) can be calculated by theoretical calculation, and the addition amount can be appropriately adjusted. . On the other hand, the higher the temperature, the higher the possibility of side reactions, and therefore the crosslinking treatment temperature is preferably 170 ° C or lower.

Further, the crosslinking treatment may be carried out at a temperature at the drying step of the adhesive layer, or may be additionally provided after the drying step.

Further, the crosslinking treatment time can be set in consideration of productivity or workability, and is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

Further, a decane coupling agent can be used in the adhesive composition of the present invention to improve adhesion and durability. As the decane coupling agent, a known decane coupling agent can be suitably used without particular limitation.

Specific examples thereof include 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropyltriethoxydecane, and 3-glycidoxypropylmethyldiethoxydecane. Epoxy-containing decane coupling agent such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane; 3-aminopropyltrimethoxydecane, N-2-(aminoethyl)-3 -Aminopropylmethyldimethoxydecane, 3-triethoxydecyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxydecane Alkane-containing decane coupling agent; (meth) acrylonitrile-based decane coupling agent such as 3-propenyloxypropyltrimethoxydecane or 3-methylpropenyloxypropyltriethoxydecane An isocyanate group-containing decane coupling agent such as 3-isocyanate propyl triethoxy decane. The use of such a decane coupling agent is preferred for improving durability.

The above decane coupling agent may be used singly or in combination of two or more kinds, and the content of the whole (meth)acrylic polymer is preferably 0.01 to 2 parts by weight based on 100 parts by weight of the above (meth)acrylic polymer. More preferably, it contains 0.02 to 0.6 parts by weight, and more preferably contains 0.05 to 0.3 parts by weight. When it is less than 0.01 part by weight, it is not sufficient for improving durability. On the other hand, when the amount is more than 2 parts by weight, the adhesion to the optical member such as the liquid crystal cell is excessively increased, and the secondary workability is lowered.

Further, other known additives may be contained in the adhesive composition of the present invention. For example, a powder such as a coloring agent or a pigment may be appropriately added depending on the intended use, and a dye, a surfactant, a plasticizer, and an adhesive property may be imparted. Agents, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulates, foils, and the like. Further, a redox system to which a reducing agent is added may be used within a controllable range.

The adhesive layer for an optical film of the present invention is formed by the above-described adhesive composition for an optical film. In the present invention, the gel fraction of the adhesive layer is preferably from 50 to 95% by weight from the viewpoint of satisfying workability for light peelability of the spacer. The gel fraction is preferably from 55 to 90% by weight, more preferably from 60 to 90% by weight. The gel fraction is a value determined by the method disclosed in the examples.

The above-mentioned adhesive layer for an optical film can be formed by applying heat treatment and hardening after being applied to a substrate. The adhesive optical film of the present invention is attached to at least one side of the optical film, and the adhesive layer is formed by the above adhesive.

As a method of forming the above-mentioned adhesive layer, for example, a spacer or the like which has been subjected to a release treatment is used as a substrate, and the above-described adhesive composition is applied onto the spacer, and the polymerization solvent or the like is dried to be cured. A method of forming an adhesive layer and then transferring it onto an optical film. Moreover, as a method of forming the above-mentioned adhesive layer, for example, an optical film is used as a substrate, and the above-mentioned adhesive composition is applied directly onto an optical film, and the polymerization solvent or the like is dried and cured to form an adhesive on the optical film. The method of the agent layer. Further, when the adhesive is applied, one or more solvents other than the polymerization solvent may be newly added.

The pressure-sensitive adhesive layer is preferably formed by applying the pressure-sensitive adhesive composition for an optical film to a substrate, for example, at a temperature of 70 to 160 ° C for 30 to 240 seconds. Hardened (dry). The above hardening temperature is preferably from 80 to 160 ° C, more preferably from 100 to 155 ° C. Further, the hardening time is preferably from 30 to 180 seconds, more preferably from 30 to 120 seconds.

In the adhesive composition for an optical film of the present invention, the (meth)acrylic polymer as the base polymer contains a tertiary amino group, and on the other hand, a peroxide is used as a crosslinking agent, whereby the adhesive is used. When the composition is hardened, the hardening treatment can be quickly performed even at a low temperature (120 ° C or lower) as described above. In the case where the adhesive composition for an optical film contains a peroxide as a crosslinking agent, if the adhesive composition is subjected to a curing treatment at the low temperature described above, the peroxide remains and changes with time, for example, The peeling property of the spacer is increased, but the adhesive composition of the present invention can be rapidly hardened even at the above low temperature, and the light peeling property against the spacer can be maintained.

Particularly, in the case where the adhesive composition for an optical film of the present invention contains a decane coupling agent, the above treatment conditions are suitable. In the prior art, when the adhesive composition containing a decane coupling agent is subjected to a hardening treatment at a high temperature of more than 140 ° C for more than 120 seconds, the decane coupling agent is evaporated, the residual amount is reduced, and the long-term durability is insufficient. However, the adhesive composition of the present invention can be rapidly hardened even at the above-mentioned low temperature, and the residual of the decane coupling agent can be maintained over time, and durability can be maintained for a long period of time, and the life of the product can be prolonged.

Further, when the adhesive optical film of the present invention is produced, a tack-adhesive layer may be formed on the surface of the optical film, or an adhesive layer may be formed after various easy-to-treat processes such as corona treatment and plasma treatment. Further, it is also possible to carry out an easy subsequent treatment on the surface of the adhesive layer.

As a method of forming the adhesive layer, various methods can be used. Specific examples thereof include roll coating, contact roll coating, gravure coating, reverse coating, roll coating, spray coating, dip coating, bar coating, knife coating, air knife coating, curtain coating, and lip coating. A method such as lip coating or extrusion coating using a die coater or the like.

The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm. It is preferably 5 to 50 μm, more preferably 10 to 30 μm.

When the above-mentioned adhesive layer is exposed, a sheet (spacer) which is subjected to a release treatment can be applied to protect the adhesive layer until it is used.

Examples of the constituent material of the spacer include a plastic film such as polyethylene, polypropylene, polyethylene terephthalate or polyester film, a porous material such as paper, cloth or non-woven fabric, a mesh, a foamed sheet, and the like. A suitable film such as a metal foil or a laminate of these materials is preferably a plastic film from the viewpoint of excellent surface smoothness.

The plastic film is not particularly limited as long as it protects the film of the pressure-sensitive adhesive layer, and examples thereof include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, and a polymethylpentene film. A polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, or the like.

The thickness of the spacer is usually 5 to 200 μm, preferably about 5 to 100 μm. Further, the spacer may be subjected to mold release and antifouling treatment using a polyfluorene-based, fluorine-based, long-chain alkyl-based or fatty amide-based release agent, cerium oxide powder or the like, or a coating type or a mixed type. Antistatic treatment such as vapor deposition type. In particular, the peeling property from the above-mentioned adhesive layer can be further improved by suitably performing a peeling treatment such as a polyfluorination treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the spacer. The adhesive layer of the present invention is suitable for the release of the spacer, and is particularly suitable for the release treatment by the polyoxygen treatment.

Further, the sheet subjected to the release treatment used in the production of the above-mentioned adhesive optical film can be directly used as a spacer for the adhesive optical film, which can be simplified in terms of steps.

The optical film is used for a user in the formation of an image display device such as a liquid crystal display device, and the type thereof is not particularly limited. For example, a polarizing plate is mentioned as an optical film. The polarizing plate is generally used for a transparent protective film on one side or both sides of a polarizing element.

The polarizing element is not particularly limited, and various polarizing elements can be used. Examples of the polarizing element include adsorption of iodine or dichroism on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film. A dichroic substance of a dye is unidirectionally stretched; a dehydration treatment of polyvinyl alcohol, a polyalkylene alignment film such as a dehydrochlorination treatment of polyvinyl chloride, or the like. Among them, a polarizing element formed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred. The thickness of the polarizing element is not particularly limited, but is usually about 5 to 80 μm.

A polarizing element in which a polyvinyl alcohol-based film is iodine-dyed and then unidirectionally stretched can be produced by, for example, immersing polyvinyl alcohol in an aqueous solution of iodine, and then stretching it to 3 to 7 times the original length. . It may also be immersed in an aqueous solution containing potassium iodide or the like which may contain boric acid or zinc sulfate, zinc chloride or the like as needed. Further, 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 surface of the polyvinyl alcohol-based film can be washed away from the dirt or the blocking inhibitor, and the polyvinyl alcohol-based film can be swollen to prevent uneven dyeing. Non-uniform effect. The stretching may be carried out after dyeing with iodine, or may be carried out while dyeing, or may be dyed with iodine after stretching. It can also be extended in an aqueous solution of boric acid or potassium iodide or in a water bath.

The material constituting the transparent protective film is, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, and isotropic property. Specific examples of such a thermoplastic resin include a cellulose resin such as triacetonitrile cellulose, a polyester resin, a polyether oxime resin, a polyfluorene resin, a polycarbonate resin, a polyamide resin, and a polyimide resin. Polyolefin resin, (meth)acrylic resin, cyclic polyolefin resin An olefinic resin), a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, and the like. Further, a transparent protective film is bonded to one side of the polarizing element by the adhesive layer, and (meth)acrylic, urethane-based, urethane-based, epoxy can be used on the other side. A thermosetting resin such as a polysiloxane or an ultraviolet curable resin is used as a transparent protective film. One or more optional 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, a color preventive agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a colorant, 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 transparency and the like which the thermoplastic resin originally has cannot be sufficiently exhibited.

Further, as the transparent protective film, for example, a polymer film disclosed in Japanese Laid-Open Patent Publication No. 2001-343529 (WO 01/37007) may be mentioned, and for example, it may be mentioned that (A) has a substituted group and/or has no branch. A resin composition substituted with a quinone imino group-containing thermoplastic resin and (B) a thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitrile group on the branch. Specific examples thereof include a resin composition film containing an alternating copolymer of isobutylene and N-methylmaleimide 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 these films have a small phase difference and a small photoelastic coefficient, it is possible to eliminate the unevenness caused by the deformation of the polarizing plate, and since the moisture permeability is small, the humidifying durability is excellent.

The thickness of the transparent protective film can be appropriately determined, and it is usually about 1 to 500 μm from the viewpoints of workability and thin layer properties such as strength and workability. In particular, it is preferably from 1 to 300 μm, more preferably from 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 polarizing element, a protective film formed of the same polymer material may be used on the front and back surfaces, and a protective film formed of a different polymer material or the like may be used.

As the transparent protective film of the present invention, 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 triacetonitrile cellulose, diacetyl cellulose, tripropylene cellulose, and dipropylene cellulose. Particularly preferred among them is triacetyl cellulose. There are many products of triacetin cellulose which are commercially available and are advantageous from the viewpoint of easy availability or cost. As an example of the commercial product of the triacetyl cellulose, the brand name "UV-50", "UV-80", "SH-80", "TD-80", "TD-TAC" manufactured by Fujifilm Co., Ltd. ", "UZ-TAC" or "KC Series" manufactured by Konica Corporation. In general, the in-plane retardation (Re) of the triacetyl cellulose is substantially 0, and the thickness direction retardation (Rth) 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 base film such as polyethylene terephthalate coated with a solvent such as cyclopentanone or methyl ethyl ketone, polypropylene or stainless steel may be bonded to a usual cellulose film and dried by heating ( For example, after performing at about 80 to 150 ° C for about 3 to 10 minutes, the substrate film is peeled off; it is dissolved in a solvent such as cyclopentanone or methyl ethyl ketone. A method in which a solution such as an olefin resin or a (meth)acrylic resin is applied onto a usual cellulose resin film and dried by heating (for example, at 80 to 150 ° C for about 3 to 10 minutes), and then the coating film is peeled off. Wait.

Moreover, as the cellulose resin film having a small phase difference in the thickness direction, a fatty acid cellulose resin film which controls the degree of fat substitution can be used. In the commonly used triacetonitrile cellulose, by controlling the degree of substitution of acetic acid to about 2.8, it is preferred to control the degree of substitution of acetic acid to 1.8 to 2.7 to reduce Rth. R41 can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonyl aniline or ethoxylated triethyl citrate to the above-mentioned fatty acid-substituted cellulose 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 resin.

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

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

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 substantially 0 can be obtained from the (meth)acrylic resin.

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used within a range that does not impair the effects of the present invention. For example, poly(meth)acrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, methacrylic acid Methyl ester-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-methyl Cyclohexyl acrylate copolymer, methyl methacrylate-(meth) acrylate Ester copolymers, etc.). Preferably, a poly(meth)acrylic acid C1-6 alkyl ester such as poly(methyl) acrylate is used. More preferably, a 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, Acrypet VH or Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and a ring structure having a ring structure disclosed in JP-A-2004-70296. An acrylic resin, 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 high heat resistance, high transparency, and 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 pseudo ring 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 also include 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 10%. 70% by weight, further preferably 10 to 60% by weight, particularly preferably 10 to 50% by weight. In the structure of the (meth)acrylic resin having a lactone ring structure, if the content ratio of the lactone ring structure represented by the formula (Chemical Formula 1) is less than 5% by weight, heat resistance, solvent resistance, and surface are present. The hardness becomes insufficient. In the structure of the (meth)acrylic resin having a lactone ring structure, if the content ratio of the lactone ring structure represented by the formula (Chemical Formula 1) is more than 90% by weight, the moldability may be insufficient. .

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

The (meth)acrylic resin having a lactone ring structure, the higher the total light transmittance measured by the method based on ASTM-D-1003, the better the molded product obtained by injection molding is preferably 85%. More preferably, it is 88% or more, and more preferably 90% or more. The total light transmittance is a standard of transparency. If the total light transmittance is less than 85%, there is a possibility that the transparency is 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 film in the slow axis direction, the fast axis direction, and the thickness direction is the thickness of the nx, ny, nz, d (nm) film, respectively. In the slow axis direction, the refractive index in the plane of the film becomes the largest direction]. Further, it is preferred that the transparent protective film be as colored as possible. It is preferred to use a protective film having a phase difference in the thickness direction of -90 nm to +75 nm. By using a protective film having a phase difference (Rth) in the thickness direction of -90 nm to +75 nm, coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be substantially eliminated. The thickness direction retardation (Rth) is further preferably -80 nm to +60 nm, 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. 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 phase difference plate is used as the transparent protective film, the phase difference plate also functions as a transparent protective film, so that the thickness can be reduced.

Examples of the retardation film include a birefringent film obtained 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. The thickness of the phase difference plate is 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. Ester, polyarylate, polyfluorene, polyethylene terephthalate, polyethylene naphthalate, polyether oxime, polyphenylene sulfide, polyphenylene ether, polyaryl fluorene, polyamine, poly phthalate Amine, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin The olefinic resin) or a binary system or a ternary system of various copolymers, graft copolymers, mixtures, and the like. These polymer materials can be an alignment (stretching film) by stretching or the like.

Examples of the liquid crystal polymer include various types of polymers of a main chain type or a branched type in which a conjugated linear atomic group (liquid crystal original) which imparts liquid crystal alignment properties is introduced into a main chain or a branch of a polymer. Specific examples of the main chain liquid crystal polymer include a structure in which a liquid crystal nucleus is bonded to a spacer portion to which flexibility is imparted, for example, a nematic alignment polyester liquid crystal polymer or a disk. A polymer or a cholesterol type polymer or the like. Specific examples of the branched-type liquid crystal polymer include polyfluorene oxide, polyacrylate, polymethacrylate or polymalonate as a main chain skeleton, and have a partition portion containing a conjugated atomic group. The liquid crystal original portion including the para-substituted cyclic compound unit imparting nematic alignment is used as a brancher or the like. The liquid crystal polymer is treated, for example, by rubbing the surface of a film such as polyimide or polyvinyl alcohol formed on a glass plate, or by arranging the oxidized surface of the ruthenium oxide. On the top, a solution of the liquid crystalline polymer is developed and then heat-treated.

The retardation plate may be, for example, various wavelength plates or a coloring or viewing angle for compensating for birefringence of the liquid crystal layer, etc., and may be suitable for the purpose of use, or may be controlled by laminating two or more types of phase difference plates. Those with poor optical properties.

The phase difference plate satisfies the relationship of nx=ny>nz, nx>ny>nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, nz>nx=ny, according to Choose for a variety of uses. 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 actually the same.

For example, a phase difference plate satisfying nx>ny>nz is preferably used in which the front phase difference is 40 to 100 nm, the thickness direction phase difference is 100 to 320 nm, and the Nz coefficient is 1.8 to 4.5. For example, a positive phase plate (positive A-plate) satisfying nx>ny=nz is preferably used to satisfy a front phase difference of 100 to 200 nm. For example, a phase difference plate (negative A-plate) satisfying nz=nx>ny is preferably used to satisfy a front phase difference of 100 to 200 nm. For example, a phase difference plate satisfying nx>nz>ny is preferably used to satisfy 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, nx=ny>nz, nz>nx>ny, or nz>nx=ny can be used.

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

For example, in the case of IPS (In-Plane Switching, including FFS), the transparent protective film on one of the polarizing plates may be used in the case of a phase difference or not. For example, when there is no phase difference, it is preferable that there is no phase difference between the upper and lower sides (cell side) of the liquid crystal cell. In the case of having a phase difference, it is preferable that the liquid crystal cell has a phase difference both above and below, and any one of the upper and lower sides has a phase difference (for example, the upper side is a biaxial film satisfying the relationship of nx>nz>ny, There is no phase difference on the lower side, or the case where the upper side is a positive A plate and the lower side is a positive C plate). In the case of having a phase difference, a range of Re = -500 to 500 nm and Rth = -500 to 500 nm is preferred. 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 preferred.

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

The transparent protective film may be subjected to a surface modification treatment to improve adhesion to the polarizing element before the application of the adhesive. Specific treatments include corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, treatment with a coupling agent, and the like. Further, an antistatic layer can be suitably formed.

The surface of the transparent protective film that is not attached to the polarizing element may be subjected to a hard coat layer or an anti-reflection treatment, a release treatment, or a treatment for diffusion or anti-glare.

The purpose of the hard coat treatment is to prevent the surface of the polarizing plate from being damaged or the like. For example, the surface of the transparent protective film is excellent in hardness or sliding properties formed by a suitable ultraviolet curable resin such as acrylic or polyoxygen. It is formed by hardening a film or the like. The purpose of performing the anti-reflection treatment is to prevent external light from being reflected on the surface of the polarizing plate, and it can be achieved by forming a conventional anti-reflection film or the like. Further, the purpose of performing the anti-sticking treatment is to prevent adhesion to an adjacent layer (for example, a diffusing plate on the backlight side).

In addition, the purpose of performing the anti-glare treatment is to prevent the external light from being reflected on the surface of the polarizing plate and disturbing the identification of the transmitted light of the polarizing plate, for example, by using a sandblasting method or a embossing method to roughen the surface or to arrange the transparent particles. In a suitable manner, a fine uneven structure is formed on the surface of the transparent protective film. The fine particles contained in the formation of the surface fine uneven structure can be used, for example, for cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, or oxidation having an average particle diameter of 0.5 to 20 μm. A transparent fine particle such as an inorganic fine particle which is usually composed of a conductive material, or an organic fine particle composed of a crosslinked or uncrosslinked polymer. When the surface fine uneven structure is formed, the amount of the fine particles used is usually from about 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 may also be a diffusion layer (a viewing angle expanding function or the like) for diffusing the transmitted light of the polarizing plate to expand the viewing angle or the like.

Further, the antireflection layer, the anti-adhesion layer, the diffusion layer, the anti-glare layer, and the like may be provided separately from the transparent protective film as other transparent layers in addition to the transparent protective film itself.

An adhesive is used in the subsequent treatment of the polarizing element and the transparent protective film. Examples of the adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl 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 component. In addition to the above, examples of the adhesive for the polarizing element and the transparent protective film include an ultraviolet curable adhesive, an electron beam curable adhesive, and the like. The adhesive for an electron beam curing type polarizing plate exhibits an appropriate adhesion to the above various transparent protective films. Further, in the adhesive used in the present invention, a metal compound filler may be contained.

In addition, examples of the optical film include a reflector or a semi-transmissive plate, a phase difference plate (including a 1/2 or 1/4 wavelength plate), a viewing angle compensation film, and a brightness improvement film, which are used in formation of a liquid crystal display device or the like. Optical layer. These may be used alone as an optical film, and may be used by laminating one or more layers on the above-mentioned polarizing plate in practical use.

Particularly preferred is a reflective polarizing plate or a semi-transmissive polarizing plate which is formed by laminating a reflecting plate or a semi-transmissive reflecting plate on a polarizing plate; and an elliptically polarizing plate or a circular polarizing plate which is formed by laminating a phase difference plate on a polarizing plate. a wide viewing angle polarizing plate formed by laminating a viewing angle compensation film on a polarizing plate, or a polarizing plate formed by laminating a brightness improving film on a polarizing plate.

The reflective polarizing plate is formed by providing a reflective layer on a polarizing plate, and can be used to form a liquid crystal display device of a type that reflects incident light from the identification side (display side) for display, and can omit a light source such as a built-in backlight. Therefore, there is an advantage that the liquid crystal display device can be easily thinned. The formation of the reflective polarizing plate can be carried out by a suitable method in which a transparent protective layer is equal to a reflective layer containing a metal or the like on one surface of the polarizing plate as needed.

Specific examples of the reflective polarizing plate include a polarizing plate in which a reflective layer containing a reflective metal such as aluminum or a vapor-deposited film is formed on one surface of the transparent protective film subjected to the matte treatment to form a reflective layer. In addition, a reflective polarizing plate or the like which has a fine uneven structure on the surface and a reflective layer having a fine uneven structure thereon is formed by containing fine particles in the transparent protective film. The reflective layer of the fine uneven structure has diffused reflection to diffuse incident light to prevent directivity or appearance from being bright, and the advantage of uneven brightness and the like can be suppressed. Further, the transparent protective film containing fine particles also has an advantage of further suppressing unevenness of light and dark when the incident light and the reflected light thereof are transmitted therethrough. The formation of the reflective layer of the fine uneven structure reflecting the fine uneven structure on the surface of the transparent protective film can be formed on the surface of the transparent protective layer by a vacuum evaporation method, an ion plating method, a sputtering method, or a plating method, for example. It is carried out by directly attaching a metal or the like.

Instead of attaching the reflecting plate directly to the transparent protective film of the polarizing plate, a reflective layer may be provided on a suitable film based on the transparent film to form a reflecting sheet or the like. Further, since the reflective layer usually contains a metal, it is preferably a transparent protective film or a polarized light from the viewpoint of preventing a decrease in reflectance due to oxidation, a viewpoint of maintaining an initial reflectance for a long period of time, or avoiding a separate protective layer. The use of a plate or the like to cover its reflective surface.

Further, the semi-transmissive polarizing plate can be obtained by a semi-transmissive reflective layer which is formed by a half mirror or the like which is reflected by the reflective layer and transmits light. The transflective polarizing plate is usually disposed on the back side of the liquid crystal cell, and can be formed in a relatively bright environment when a liquid crystal display device or the like is used, and reflects the incident light from the identification side (display side) to display an image. In the environment, 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 surface of the transflective polarizing plate is used. In other words, the semi-transmissive polarizing plate can save energy used for light sources such as backlights in a bright environment, and can be used in the formation of a liquid crystal display device or the like of a built-in power source in a dark environment.

An elliptically polarizing plate or a circularly polarizing plate formed by laminating a phase difference plate on a polarizing plate will be described. When the linearly polarized light is changed to elliptically polarized or circularly polarized light, or the elliptically polarized or circularly polarized light is changed to linearly polarized light, or the polarized direction of the linearly polarized light is changed, a phase difference plate or the like can be used. In particular, a so-called quarter-wave plate (also referred to as a λ/4 plate) is used as a phase difference plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A 1/2 wavelength 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 display without the above coloring. Wait. Further, the polarizing plate for controlling the three-dimensional refractive index can also compensate (prevent) the coloring which occurs when the screen of the liquid crystal display device is viewed obliquely. 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 that displays an image in color, and has a function of preventing reflection.

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

The viewing angle compensation film is a film for expanding the viewing angle even when the image of the liquid crystal display device is not viewed perpendicularly to the direction in which the screen is slightly inclined. The viewing angle compensation phase difference 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. In general, a phase difference plate is a polymer film having birefringence which is uniaxially stretched in the surface direction thereof, and a phase difference plate serving as a viewing angle compensation film can be used to have a biaxial extension along the surface direction thereof. a birefringent polymer film, a biaxially stretched film such as a birefringent polymer or a tilted alignment film which is uniaxially stretched in the plane direction thereof and which is extended in the thickness direction thereof to control the refractive index in the thickness direction. Wait. The oblique alignment film may be, for example, a polymer film which is subjected to elongation treatment or/and shrinkage treatment under the action of shrinkage force caused by heating after the heat shrink film is applied, and the liquid crystal polymer is tilted. Orientation, etc. As the material raw material polymer of the phase difference plate, the same as the polymer described in the above-described phase difference plate can be used, and coloring or the like due to a change in the recognition angle based on the phase difference generated by the liquid crystal cell can be used or It is suitable for the purpose of expanding the perspective of good recognition.

Further, from the viewpoint of achieving a wide viewing angle with good visibility, etc., it is possible to preferably use an optical layer supporting an alignment layer containing a liquid crystal polymer, particularly an inclined alignment layer of a discotic liquid crystal polymer, with a triethylene fluorene cellulose film. An optically compensated phase difference plate of an anisotropic layer.

A polarizing plate in which a polarizing plate and a brightness improving film are bonded together is usually provided on the back side of the liquid crystal cell. The brightness-improving film is formed by reflecting a linearly polarized light of a specific polarization axis or a circularly polarized light of a specific direction when a natural light is incident due to a backlight of a liquid crystal display device or the like, or reflection from the back side, and the brightness is transmitted through other characteristics. The polarizing plate in which the film and the polarizing plate are laminated can improve the light transmitted from the light source such as the backlight to obtain the transmitted light of a specific polarized state, and the light other than the specific polarized state is not transmitted and reflected. The light reflected on the brightness improving film surface is reversed again via the reflective layer provided on the rear side, and is again incident on the brightness improving film, and a part or all of the light is transmitted as a specific polarized state, thereby increasing By adjusting the amount of light of the film by the brightness and supplying the polarized light that is difficult to absorb to the polarizing element, the amount of light that can be used in liquid crystal display image display or the like is increased, thereby improving the brightness. In other words, when the light-improving film is not used and light is incident through the polarizing element from the back side of the liquid crystal cell such as a backlight, light having a polarization direction that does not coincide with the polarization axis of the polarizing element is substantially absorbed by the polarizing element, and cannot be absorbed. Through the polarizing element. That is, although it differs depending on the characteristics of the polarizing element to be used, about 50% of the light is absorbed by the polarizing element, so that the amount of light usable in liquid crystal image display or the like is reduced correspondingly, resulting in darkening of the image. The brightness improving film is repeatedly operated such that light having a polarization direction that can be absorbed by the polarizing element is not incident on the polarizing element, but is reflected on the brightness improving film, and further passes through the reflective layer provided on the rear side thereof. When the light is incident on the brightness improving film again, the brightness improving film changes the polarization direction of the light reflected and inverted between the two into a polarized light that can pass through the polarizing direction of the polarizing element. Further, since it is provided to the polarizing element, it is possible to effectively use light such as a backlight in the image display of the liquid crystal display device, so that the screen can be made bright.

A diffusion plate may be provided between the brightness improving film and the reflective layer or the like. The light in the polarized state reflected by the brightness improving film faces the reflecting layer or the like, and the diffusing plate provided can uniformly diffuse the passing light while eliminating the polarized state and becoming a non-polarized state. In other words, the operation of reflecting the light in the natural light state to the reflection layer or the like and reflecting it through the reflection layer and then again entering the brightness improvement film through the diffusion plate is performed. By providing a diffusing plate between the brightness improving film and the reflecting layer or the like to restore the polarized light to the original natural light state, the brightness of the display screen can be maintained while reducing the unevenness of the brightness of the display screen, thereby providing uniformity. And bright picture. By providing the diffusing plate, the number of repeated reflections of the primary incident light can be appropriately increased, and a uniform and bright display screen can be provided by the diffusion function of the diffusing plate.

As the brightness improving film, for example, a multilayer laminated film of a dielectric or a multilayer laminated body of a film having different refractive index anisotropy, which exhibits a characteristic of transmitting a linear polarized light of a specific polarizing axis and reflecting other light, can be used. The alignment film of the liquid crystal polymer or the film which supports the alignment liquid crystal layer on the film substrate or the like which exhibits a characteristic of polarizing light of any of left-handed or right-handed rotation and transmitting other light.

Therefore, by using the brightness improving film of the type that transmits the linearly polarized light of the specific polarization axis described above, the transmitted light is incident on the polarizing plate directly in the direction coincident with the polarization axis, and the absorption loss caused by the polarizing plate can be suppressed. And the light is transmitted efficiently. On the other hand, a brightness improving film of a type such as a cholesteric liquid crystal layer that transmits circularly polarized light can directly enter light onto the polarizing element, but it is preferable to pass the phase difference plate from the viewpoint of suppressing absorption loss. The circularly polarized light is linearly polarized and incident on 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 such as a visible light region can be, for example, a phase difference plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm and displays other phases. The phase difference layer of the difference characteristic is obtained, for example, by a method in which a phase difference layer functioning as a half-wavelength plate overlaps. Therefore, the phase difference plate disposed between the polarizing plate and the brightness improving film may include one or two or more layers of retardation layers.

Further, in the cholesteric liquid crystal layer, a material having a different reflection wavelength may be combined to form an arrangement structure in which two or more layers are stacked, thereby obtaining a circularly polarized light in a wide wavelength range such as a visible light region. Based on this, a transmissive circular polarization of a wider wavelength range is 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 separating type polarizing plate. Therefore, a reflective elliptically polarizing plate or a semi-transmissive elliptically polarizing plate in which the above-described reflective polarizing plate, semi-transmissive polarizing plate, and retardation plate are combined may be used.

The optical film in which the optical layer is laminated on the polarizing plate can be formed by sequentially stacking layers in a manufacturing process such as a liquid crystal display device, but the quality is stabilized or assembled, and the optical film is laminated in advance. Since it is excellent, it has an advantage that the manufacturing steps of a liquid crystal display device or the like can be improved. A suitable bonding means such as an adhesive layer can be used in the laminate. When the polarizing plate is brought into contact with another optical layer, the optical axis of the polarizing plate can be set to an appropriate arrangement angle according to the target phase difference characteristic or the like.

Further, each layer such as an optical film or an adhesive layer of the adhesive optical film of the present invention may be, for example, a salicylate-based compound, a benzophenol-based compound, a benzotriazole-based compound or A method of treating an ultraviolet absorber such as a cyanoacrylate compound or a nickel-salt salt compound, and the like, and having an ultraviolet absorbing ability or the like.

The adhesive optical film of the present invention can be suitably used for formation of various image display devices such as liquid crystal display devices. The formation of the liquid crystal display device can be carried out according to the previous method. In other words, the liquid crystal display device can be generally formed by suitably assembling a liquid crystal cell, an adhesive optical film, and an optional illumination system, and the like, and incorporating the components into a driving circuit or the like. In the present invention, in addition to the adhesive type of the present invention. The optical film is not particularly limited and can be formed according to the previous method. As the liquid crystal cell, for example, any type of liquid crystal cell such as TN type, STN type, π type, VA type, or IPS type can be used.

A liquid crystal display device in which an adhesive optical film is disposed on one side or both sides of a liquid crystal cell, and a liquid crystal display device such as a backlight or a reflector used in an illumination system can be formed. In this case, the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When the optical film is provided on both sides, the same may be the same or different. Further, when forming a liquid crystal display device, one or two or more layers such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a tantalum array, a lens array sheet, a light diffusing plate, and a backlight can be disposed at appropriate positions. And other suitable components.

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 used in an organic EL display device. In general, an organic EL display device is formed by sequentially laminating a transparent electrode, an organic light-emitting layer, and a metal electrode on a transparent substrate to form an illuminant (organic electroluminescence). Here, the organic light-emitting layer is a laminate of various organic thin films, and for example, a laminate including a hole-buried layer such as a triphenylamine derivative and a light-emitting layer containing a fluorescent organic solid such as ruthenium or the like is known. The light-emitting layer is composed of a laminate of an electron-laying layer containing a perylene derivative or the like, or a combination of the hole-laying layer, the light-emitting layer, and the layer of the electron-implanting layer.

The organic EL display device emits light by applying a voltage to a transparent electrode and a metal electrode to implant a hole and an electron in the organic light-emitting layer, and the energy generated by the recombination of the hole and the electron activates the firefly. A light substance that emits light when the excited fluorescent substance returns to the ground state. The recombination mechanism in the middle is the same as that of a general diode, and it can be inferred that the current and the luminous intensity show a strong nonlinearity with respect to the rectifying property with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to take out the light emission in the organic light-emitting layer, and a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is usually used as an anode. On the other hand, in order to improve the luminous efficiency in order to facilitate the electron implantation, it is important to use a substance having a small work function in the cathode, and a metal electrode such as Mg-Ag or Al-Li is usually used.

In the organic EL display device having such a configuration, the organic light-emitting layer is formed of an extremely thin film having a thickness of about 10 nm. Therefore, the organic light-emitting layer is also the same as the transparent electrode, so that the light is substantially completely transmitted. As a result, the light is incident on the surface of the transparent substrate when the light is not emitted, and the light that is transmitted through the transparent electrode and the organic light-emitting layer and reflected on the metal electrode is again emitted toward the surface side of the transparent substrate. Therefore, the organic EL display device is recognized from the outside. The display surface is like a mirror.

In an organic EL display device including an organic electroluminescence device, a polarizing plate may be disposed on a surface side of the transparent electrode, and a phase difference plate may be disposed between the transparent electrode and the polarizing plate, wherein the organic electroluminescent body is used A transparent electrode is provided on the surface side of the organic light-emitting layer that emits light by applying a voltage, and a metal electrode is provided on the back side of the organic light-emitting layer.

Since the retardation plate and the polarizing plate have a function of causing the light reflected from the outside to be reflected by the metal electrode to be polarized, the polarizing action has an effect that the mirror surface of the metal electrode cannot be recognized from the outside. In particular, when the retardation plate is formed of a quarter-wavelength plate and the angle between the polarizing plate and the polarization direction of the phase difference plate is adjusted to π/4, the mirror surface of the metal electrode can be completely shielded.

In other words, the external light incident on the organic EL display device transmits only the linearly polarized light component due to the polarizing plate. The linearly polarized light is generally converted into an elliptically polarized light by a phase difference plate, and is generally circularly polarized when the phase difference plate is a quarter wave plate and the angle between the polarizing plate and the polarization direction of the phase difference plate is π/4.

The circularly polarized light passes through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, and then passes through the organic thin film, the transparent electrode, and the transparent substrate again, and is again converted into linearly polarized light by the phase difference plate. Since the linearly polarized light is orthogonal to the polarizing direction of the polarizing plate, the polarizing plate is not transmitted. As a result, the mirror surface of the metal electrode can be completely shielded.

Example

Hereinafter, the invention will be specifically described by way of examples, but the invention is not limited to the examples. Furthermore, parts and % in each case are based on weight. The evaluation items in the examples and the like were measured in the following manner.

<Measurement of Weight Average Molecular Weight>

The weight average molecular weight of the obtained (meth)acrylic polymer was measured by GPC (gel permeation chromatography). The sample was prepared by dissolving a sample in dimethylformamide to prepare a 0.1% by weight solution, allowing it to stand overnight, and then filtering it with a 0.45 μm membrane filter.

. Analytical device: manufactured by Tosoh, HLC-8120GPC

. Pipe column: manufactured by Tosoh, Super AWM-H, AW4000, AW2500

. Column size: each 6.0mmΦ×150mm

. Lysate: 30 mM lithium bromide, 30 mM-phosphoric acid dimethylformamide solution

Flow rate: 0.4ml/min

Detector: Differential Refractometer (RI)

Column temperature: 40 ° C

Injection volume: 20μl

(production of polarizing plate)

A polyvinyl alcohol film having a thickness of 80 μm was dyed for 1 minute at 30 ° C in a 0.3% iodine solution at a speed ratio of 3 minutes. Thereafter, the film was immersed in an aqueous solution containing 4% of boric acid and 10% of potassium iodide at 60 ° C for 0.5 minutes, and the total stretching ratio was 6 times. Then, it was washed by immersing in an aqueous solution containing potassium iodide at a concentration of 1.5% at 30 ° C for 10 seconds, and then dried at 50 ° C for 4 minutes to obtain a polarizing element. On both surfaces of the polarizing element, a saponified 80 μm thick triacetyl cellulose film was bonded to the both surfaces of the polarizing element to prepare a polarizing plate.

Manufacturing example 1 <Modulation of acrylic polymer>

In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 99.7 parts of butyl acrylate, 0.1 part of N,N-dimethylaminoethyl acrylate, 0.1 part of acrylic acid, and 4-hydroxy acrylate were used. 0.1 part of butyl ester, 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 200 parts of ethyl acetate were placed together, and nitrogen gas was introduced while gradually stirring, and nitrogen was replaced, and then the flask was placed. The liquid temperature in the inside was maintained at around 60 ° C, and polymerization was carried out for 6 hours to prepare an acrylic polymer solution. The weight average molecular weight of the above acrylic polymer was 2.05 million.

Production Examples 2 to 14, and Comparative Production Examples 1 to 7

In the production example 1, an acrylic polymer solution was prepared in the same manner as in Production Example 1, except that at least one of the type and the amount of the monomer component was changed as shown in Table 2. In Production Example 14, toluene was used instead of ethyl acetate as a solvent. The weight average molecular weight of the acrylic polymer obtained in each example is shown in Table 2.

Example 1 (Production of polarizing plate with adhesive layer)

With respect to 100 parts of the solid content of the acrylic polymer solution obtained in Production Example 1, a substituted benzoyl peroxide (manufactured by Nippon Oil & Fat Co., Ltd., Nyper BMT40) as a crosslinking agent was formulated in an amount of 0.3 parts. 0.2 parts of methylolpropane toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L) and 0.1 part of an acrylic adhesive solution of a decane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM573).

Then, the acrylic adhesive solution was applied to one side of a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) which was subjected to polyfluorination treatment as a spacer. On the (polyoxygenated surface), the thickness of the adhesive layer after drying was set to 20 μm, and dried at 155 ° C for 3 minutes (180 seconds) to form an adhesive layer. The adhesive layer was bonded to a polarizing plate and transferred to prepare a polarizing plate with an adhesive layer.

Examples 2 to 15 and Comparative Examples 1 to 8

In the first embodiment, the type of the acrylic polymer solution used in preparing the acrylic pressure-sensitive adhesive solution, the type or amount of the crosslinking agent, and the type or amount of the decane coupling agent are changed as shown in Table 3. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1. Further, in Comparative Example 7, in the preparation of the acrylic adhesive solution, in addition to the crosslinking agent and the decane coupling agent, an acrylic oligomer (weight average molecular weight of 3,000, manufactured by Toagosei Co., Ltd.) was also formulated. , ARFONUP-1000) 15 copies.

Production Examples 15 to 22, and Comparative Manufacturing Examples 8 to 11 <Modulation of acrylic polymer>

In the production example 1, an acrylic polymer solution was prepared in the same manner as in Production Example 1, except that at least one of the type and amount of the monomer component was changed as shown in Table 2. The weight average molecular weight of the acrylic polymer obtained in each example is shown in Table 2.

Example 16 (Production of polarizing plate with adhesive layer)

With respect to 100 parts of the solid content of the acrylic polymer solution obtained in Production Example 15, a substituted benzoyl peroxide (manufactured by Nippon Oil & Fat Co., Ltd., Nyper BMT40) as a crosslinking agent was formulated in an amount of 0.3 parts. 0.1 part of methylolpropane toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L) and 0.1 part of an acrylic adhesive solution of a decane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403).

Then, the acrylic adhesive solution was applied to one side of a polyethylene terephthalate (PET) film (Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) which was subjected to polyfluorination treatment, and dried. The thickness of the adhesive layer was changed to 25 μm, and dried at 100 ° C for 80 seconds to form an adhesive layer. The adhesive layer was bonded to a polarizing plate and transferred to prepare a polarizing plate with an adhesive layer.

Examples 17 to 28 and Comparative Examples 9 to 19

In the first embodiment, the type of the acrylic polymer solution used in preparing the acrylic pressure-sensitive adhesive solution, the type or amount of the crosslinking agent, the amount of the decane coupling agent used, and the drying conditions (temperature, time) are changed to A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the results are shown in Table 3.

The polarizing plate (sample) with the adhesive layer attached with the spacer obtained in the above Examples and Comparative Examples was subjected to the following evaluation. The evaluation results are shown in Table 4 and Table 5.

<Measurement of initial adhesion force>

After the sample was cut to a width of 25 mm, the spacer was peeled off, and then adhered to a 0.7 mm thick alkali-free glass (manufactured by Corning, Inc., 1737) with a 2 kg roller, and attached at 50 ° C, The autoclave at 0.5 MPa was treated for 15 minutes and then aged at 23 ° C for 1 hour. The adhesion (N/25 mm) at the time of peeling off the sample by a tensile tester at a peeling angle of 180° and a peeling speed of 300 mm/min was measured.

<60 ° C / 48 hours after the determination of the adhesion>

After the sample was cut to a width of 25 mm, the spacer was peeled off, and then adhered to a 0.7 mm thick alkali-free glass (manufactured by Corning, Inc., 1737) with a 2 kg roller, and attached at 50 ° C, The autoclave at 0.5 MPa was treated for 15 minutes and then aged at 60 ° C for 48 hours. The adhesion (N/25 mm) at the time of peeling off the sample by a tensile tester at a peeling angle of 180° and a peeling speed of 300 mm/min was measured.

<Secondary workability>

After cutting the above sample to a width of 25 mm, the spacer was peeled off, and then adhered to a 0.7 mm thick alkali-free glass (manufactured by Corning, Inc., 1737) with a 2 kg roller, and then attached, followed by 23 ° C. Cooked for 1 hour. The adhesion force (N/25 mm) and the state of the glass surface when the sample was peeled off at a peeling angle of 180° and a peeling speed of 300 mm/min were visually evaluated by the following tensile test.

◎: No paste remained and peeled off (force: less than 10 N/25 mm).

○: No paste remained and peeled off, but peeling was slightly difficult (force: 10 N/25 mm or more and less than 15 N/25 mm).

△: No paste remained and peeled off, but peeling was difficult (force: 15 N/25 mm or more).

×: A little paste remains.

××: A paste remains.

<Durability>

After the sample was cut into 320 mm × 240 mm, the spacer was peeled off, and then attached to an alkali-free glass (manufactured by Corning, Inc., 1737) having a thickness of 0.7 mm, and treated with an autoclave at 50 ° C and 0.5 MPa for 15 minutes. The above sample was completely adhered to the alkali-free glass. The sample subjected to this treatment was subjected to treatment at 80 ° C, 90 ° C, 100 ° C, 60 ° C / 90% RH, 60 ° C / 95% RH for 500 hours, and then visually evaluated for foaming and peeling on the following basis. The state of floating.

◎: No foaming or peeling.

○: It was confirmed that foaming did not affect the visibility (the maximum diameter was less than 100 μm).

×: It was confirmed that foaming (maximum diameter was 100 μm or more) and peeling were observed.

<gel fraction>

On the polyethylene terephthalate film which was subjected to polyfluorination treatment, each of the adhesive compositions before the preparation of the sample was applied so that the thickness after drying was the same as that of each case (20 μm or 25 μm), after coating, The drying conditions (temperature, time) similar to the respective examples were hardened to form an adhesive layer, and further placed at a temperature of 23 ° C and a humidity of 65% RH for 1 hour, and then the gel was measured for the adhesive layer. rate. The gel fraction is about 0.2 g of the above adhesive layer, and is wrapped in a fluororesin (TEMISH NTF-1122, manufactured by Nitto Denko Corporation) having a weight (Wa) measured in advance so as not to expose the adhesive layer. After bundling, the weight (Wb) was measured, and it was immersed in ethyl acetate of about 40 ml at 7 ° C for 7 days to extract a soluble component. Thereafter, the fluororesin containing the adhesive layer was taken out, and dried on the aluminum cup at 130 ° C for 2 hours, and the weight (Wc) of the fluororesin containing the adhesive layer from which the soluble component was removed was measured.

The measured values were determined by the following formula to determine the gel fraction (% by weight) of the adhesive layer.

Gel fraction (% by weight) = {(Wc-Wa) / (Wb-Wa)} × 100

<Coating productivity>

Regarding the gel fraction A, the drying time B, and the drying temperature C, the evaluation scores were respectively evaluated according to Table 1, and the evaluation was performed based on the values obtained by A × B × C on the following basis.

○: The evaluation is divided into 20 or more

△: The evaluation is divided into 5 or more and 19 or less.

×: 4 or less

<Processability>

After the sample was prepared, 100 pieces of a square sample having a length of 270 mm on one side were punched out within 24 hours, and the operator observed it by visual observation or hand touch to determine whether or not the side surface of the polarizing plate had a feeling of adhesion. Further, it is judged whether or not the surface of the polarizing plate is contaminated by the adhesive. Several pieces of adhesiveness and dirt were evaluated on the basis of the following criteria.

○: There are 0 pieces of any of 100 pieces of adhesiveness and dirt.

△: There are 1 to 5 pieces of any of 100 pieces of adhesiveness and dirt.

×: There are 6 or more of 100 pieces of adhesiveness and dirt.

<peel force to spacer>

After the sample was cut into a width of 50 mm and a length of 100 mm, the peeling force (N/50 mm) when the separator was peeled off from the sample by a tensile tester at a peeling angle of 180° and a peeling speed of 300 mm/min was measured. The peeling force is preferably 0.05 to 0.1 N/50 mm, more preferably 0.05 to 0.09 N/50 mm. If the peeling force is less than 0.05, the problem that the spacer floats from the adhesive layer of the adhesive optical film is likely to occur during the processing. On the other hand, if the peeling force exceeds 0.1 N/50 mm, it is for the panel manufacturer. When the spacer is peeled off from the adhesive layer of the self-adhesive optical film, light peeling becomes difficult, and productivity is deteriorated.

<Separation workability of spacers>

For 100 samples, the state of the separator was peeled off by an automatic peeling device (manufactured by Nitto Denko Corporation), and the judgment was made based on the following criteria.

○: 0 of 100 tablets failed.

×: One or more of the 100 pieces failed.

Table 2 shows the following, BA: butyl acrylate, DMAEA: N,N-dimethylaminoethyl acrylate, DMAPAA: N,N-dimethylaminopropyl acrylamide, ACMO: N-propylene Mercaptomorpholine, AAM: acrylamide, AA: acrylic acid, 4HBA: 4-hydroxybutyl acrylate, 2HEA: 2-hydroxyethyl acrylate, PEA: phenoxyethyl acrylate.

In Table 3, the peroxides were substituted benzoyl peroxide (manufactured by Nippon Oil & Fat Co., Ltd., Nyper BMT40). In the case of an isocyanate crosslinking agent, *01 is trimethylolpropane toluene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate L), *02 is trimethylolpropane phthalyl diisocyanate (Mitsui Takeda Made by Polyurethane Co., Ltd., Takenate D-110N). In the case of the decane coupling agent, *11 is KBM573 manufactured by Shin-Etsu Chemical Co., Ltd., and *12 is KBM403 manufactured by Shin-Etsu Chemical Co., Ltd., and is manufactured by A-100, a comprehensive research company. The *oligomer of the other additive of Comparative Example 7 was an acrylic oligomer (weight average molecular weight: 3,000, manufactured by Toagosei Co., Ltd., ARFONUP-1000) of 15 parts.

As can be seen from Tables 4 and 5, the adhesive layer formed of the adhesive composition for an optical film of the present invention can satisfy secondary workability, durability, and workability, and has light peelability with respect to the spacer, and has workability. . Further, according to the present invention, as described in the coating productivity of Table 5, the above-mentioned adhesive layer having a specific gel fraction can be obtained by a low-temperature, short-time drying condition. In addition, although the coating productivity was not specifically shown in Table 4, the evaluation of the Example of Table 4 was divided into "5" or "6", and the evaluation of coating productivity was "?".

Claims (11)

An adhesive composition for an optical film, which comprises a (meth)acrylic polymer and a peroxide as a crosslinking agent, and the (meth)acrylic polymer contains (meth)acrylic acid The alkyl ester is 45 to 99.99% by weight, and the monomer having a tertiary amino group is 0.01 to 2% by weight as a monomer unit, and the peroxide is 100 parts by weight based on the (meth)acrylic polymer. 0.01~2 parts by weight. The adhesive composition for an optical film according to claim 1, wherein the isocyanate crosslinking agent is further contained in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. The adhesive composition for an optical film according to claim 1, which further contains 0.01 to 2 parts by weight of the decane coupling agent based on 100 parts by weight of the (meth)acrylic polymer. The adhesive composition for an optical film according to claim 1, wherein the (meth)acrylic polymer further contains 0.01 to 5% by weight of the carboxyl group-containing monomer and/or 0.01 to 5% by weight of the hydroxyl group-containing monomer as a monomer. The unit, and the sum of the monomers is 100% by weight. An adhesive composition for an optical film according to claim 1, which comprises a tertiary alkyl group-containing N,N-dimethylaminoethyl (meth)acrylate and/or N,N-dimethylamine Propyl (meth) acrylamide. The adhesive composition for an optical film according to claim 1, wherein the (meth)acrylic polymer has a weight average molecular weight of from 1,000,000 to 3,000,000. An adhesive layer for an optical film, which is formed by the adhesive composition for an optical film according to any one of claims 1 to 6. The adhesive layer for an optical film according to claim 7, wherein the adhesive layer has a gel fraction of 50 to 95% by weight. A method for producing an adhesive layer for an optical film according to claim 7 or claim 8, wherein the adhesive composition for an optical film according to any one of claims 1 to 6 is applied to a substrate. The temperature is 70 to 160 ° C, and the time is 30 to 240 seconds to cure it. An adhesive optical film characterized in that an adhesive layer for an optical film according to claim 7 is formed on at least one side of the optical film. An image display apparatus using at least one adhesive optical film as claimed in claim 10.