KR102483096B1 - Pressure-sensitive adhesive composition for polarizing film, pressure-sensitive adhesive layer for polarizing film, polarizing film having a pressure-sensitive adhesive layer, liquid crystal panel and liquid crystal display device - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition for a polarizing film characterized by containing a (meth)acrylic polymer, a pigment, a radical generator and an antioxidant. The pressure-sensitive adhesive composition for polarizing films of the present invention has good temporal stability and can maintain wide color gamut due to dyes.

Description

Pressure-sensitive adhesive composition for polarizing film, pressure-sensitive adhesive layer for polarizing film, polarizing film having a pressure-sensitive adhesive layer, liquid crystal panel and liquid crystal display device

The present invention relates to a pressure-sensitive adhesive composition for polarizing films and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition. Further, the present invention relates to an optical film having a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive layer is formed on at least one surface of a polarizing film. Furthermore, the present invention relates to a liquid crystal panel using the optical film having the pressure-sensitive adhesive layer and a liquid crystal display device having the liquid crystal panel.

It is indispensable for an image display device or the like to arrange polarizing elements on both sides of a liquid crystal cell because of its image forming method, and polarizing films are generally adhered thereto. When attaching the said polarizing film to a liquid crystal cell, an adhesive is normally used. In addition, in order to reduce the loss of light, the adhesion between the polarizing film and the liquid crystal cell is normally adhered to each material using an adhesive. In such a case, a polarizing film having a pressure-sensitive adhesive layer previously provided as a pressure-sensitive adhesive layer on one side of the polarizing film is generally used as the pressure-sensitive adhesive because it has merits such as not requiring a drying step to fix the polarizing film.

Moreover, providing arbitrary hues to a polarizing film and obtaining a high-contrast liquid crystal display body is proposed by adding dye or a pigment to the said adhesive layer and coloring it (patent document 1). In recent years, brightness and sharpness (i.e., wide color gamut) are required for image display devices, and organic EL display devices (OLED) are attracting attention, but wide color gamut is also required for liquid crystal display devices. For example, as a method of wide color gamut of a liquid crystal display device, it is to laminate a polarizing film on one side or both sides of the liquid crystal cell through an adhesive layer containing a dye showing an absorption maximum wavelength in a specific wavelength range (560 to 610 nm). It has been proposed (Patent Documents 2 and 3).

Utility model registration No. 3052812 Specification Japanese Unexamined Patent Publication No. 2011-039093 Japanese Unexamined Patent Publication No. 2014-092611

In general, as the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer for polarizing films, an acrylic pressure-sensitive adhesive composition containing a (meth)acrylic polymer as a base polymer is commonly used. In the acrylic pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer obtained by radical crosslinking may be formed using a radical generating agent (eg, peroxide) as a crosslinking agent in addition to the (meth)acrylic polymer. Further, when the (meth)acrylic polymer in the acrylic pressure-sensitive adhesive composition is prepared by heat or radiation curing of monomer components, a radical polymerization initiator is contained in the pressure-sensitive adhesive composition.

However, it has been found that when a pigment is further contained in the pressure-sensitive adhesive composition containing the radical generator, radicals are generated from the radical generator and the radical decomposes the pigment. As a result, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition gradually fades even if it was originally colored with a pigment. In this way, when the pigment in the pressure-sensitive adhesive layer deteriorates over time, it is difficult to maintain the wide color gamut due to the pigment.

An object of the present invention is to provide a pressure-sensitive adhesive composition for a polarizing film containing a (meth)acrylic polymer, a pigment and a radical generator, which has good stability over time and can maintain photochromic gamut due to the pigment. do.

In addition, the present invention provides a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition for a polarizing film, provides an optical film having a pressure-sensitive adhesive layer having the pressure-sensitive adhesive layer, and furthermore, a liquid crystal panel using the optical film having the pressure-sensitive adhesive layer. It is an object of the present invention to provide a liquid crystal display device using the liquid crystal panel.

As a result of repeated earnest examinations in order to solve the said subject, the present inventors discovered the following adhesive composition for polarizing films, and came to complete this invention.

That is, the present invention relates to a pressure-sensitive adhesive composition for a polarizing film characterized by containing a (meth)acrylic polymer, a pigment, an antioxidant and a radical generator.

In the pressure-sensitive adhesive composition for polarizing films, the dye may have a maximum absorption wavelength in at least one of a wavelength range of 470 to 510 nm and a wavelength range of 570 to 610 nm.

In the pressure-sensitive adhesive composition for a polarizing film, a tetraazaporphyrin-based pigment may be used as the pigment.

In the above-mentioned pressure-sensitive adhesive composition for polarizing film, it is preferable to contain 0.01 to 5 parts by weight of the pigment based on 100 parts by weight of the (meth)acrylic polymer.

In the pressure-sensitive adhesive composition for a polarizing film, a peroxide may be used as the radical generator.

In the pressure-sensitive adhesive composition for a polarizing film, the radical generator is preferably contained in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

In the pressure-sensitive adhesive composition for a polarizing film, a phenol-based antioxidant may be used as the antioxidant.

In the pressure-sensitive adhesive composition for a polarizing film, the antioxidant is preferably contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

In the pressure-sensitive adhesive composition for a polarizing film, it is preferable that the weight ratio (A/B) of the amount (A) of the radical generator and the amount (B) of the antioxidant is 4 or less.

The pressure-sensitive adhesive composition for the polarizing film may further contain a crosslinking agent.

Moreover, this invention relates to the adhesive layer for polarizing films characterized by being formed from the said adhesive composition for polarizing films.

It is preferable that the gel fraction of the said adhesive layer for polarizing films is 50-98 weight%.

When the pressure-sensitive adhesive layer for the polarizing film has a thickness of 20 μm, the absolute value of the difference (T1-T2) between transmittance (T1) before and after storage at 85° C. for 500 hours (T2) is preferably 50% or less.

Claims 11 to 13, characterized in that, when the pressure-sensitive adhesive layer for polarizing film has a thickness of 20 μm, a ratio (T2/T1) of transmittance (T1) before storage at 85° C. for 500 hours and transmittance (T2) after storage is 2 or less. The adhesive layer for polarizing films described in any one of these.

Further, the present invention relates to a polarizing film having a pressure-sensitive adhesive layer, characterized in that the pressure-sensitive adhesive layer for the polarizing film is formed on at least one side of the polarizing film.

Further, the present invention relates to a liquid crystal panel characterized in that a liquid crystal cell and a polarizing film having the pressure-sensitive adhesive layer on at least one surface of the liquid crystal cell are bonded via the pressure-sensitive adhesive layer of the polarizing film having the pressure-sensitive adhesive layer. it's about

Further, the present invention relates to a liquid crystal display device characterized by having the above liquid crystal panel.

The pressure-sensitive adhesive composition for a polarizing film of the present invention contains a pigment in addition to a (meth)acrylic polymer as a base polymer. By absorbing light of a partial wavelength with a dye, the entire color of the liquid crystal display device can be adjusted, and sharpness can be improved by wide color gamut. In particular, a dye having a maximum absorption wavelength in at least one of a wavelength range of 470 to 510 nm and a wavelength range of 570 to 610 nm emits light that is unnecessary for color expression in a wavelength range other than RGB (wavelength range of 470 to 510 nm and wavelength range 570 to 610 nm). can be absorbed to suppress the unnecessary light emission, so it is effective for wide color gamut.

Moreover, the adhesive composition for polarizing films of this invention contains radical generating agents, such as a peroxide. The radical generator functions, for example, as a crosslinking agent for (meth)acrylic polymers, and can control the gel fraction of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for polarizing films within a desired range, thereby providing a good-looking pressure-sensitive adhesive layer. can form

As described above, since a pigment and a radical generator coexist in the pressure-sensitive adhesive composition for a polarizing film of the present invention, discoloration of the pigment due to radicals generated from the radical generator is a concern. However, by containing an antioxidant, the pressure-sensitive adhesive composition for a polarizing film of the present invention captures radicals by the antioxidant to suppress discoloration (decomposition) of pigments, and is stable over time and can maintain photochromic gamut.

The pressure-sensitive adhesive composition for a polarizing film of the present invention contains a (meth)acrylic polymer, a pigment, an antioxidant and a radical generator. Hereinafter, these components are demonstrated.

<(meth)acrylic polymer>

The pressure-sensitive adhesive composition for an optical film of the present invention includes a (meth)acrylic polymer as a main component as a base polymer. The main component refers to the component with the highest content ratio among the total solids contained in the pressure-sensitive adhesive composition, for example, a component that accounts for more than 50% by weight of the total solids contained in the pressure-sensitive adhesive composition, and furthermore, a component that accounts for more than 70% by weight point

The (meth)acrylic polymer usually contains an alkyl (meth)acrylate as a main component as a monomer unit. In addition, (meth)acrylate refers to acrylate and/or methacrylate, and is synonymous with (meth) of the present invention.

Examples of the alkyl (meth)acrylate constituting the main skeleton of the above-mentioned (meth)acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. These may be used alone or in combination. It is preferable that these alkyl groups have 3 to 9 carbon atoms on average.

In addition, from the viewpoint of adhesive properties, durability, adjustment of phase difference, adjustment of refractive index, etc., alkyl (meth)acrylates containing an aromatic ring such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate can be used. there is.

Among the (meth)acrylic polymers, one or more copolymerizable monomers having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group may be introduced by copolymerization for the purpose of improving adhesiveness or heat resistance. there is. Specific examples of such copolymerization monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, Contains hydroxyl groups such as 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methylacrylate. monomer; carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; Contains sulfonic acid groups such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl(meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid monomer; Phosphoric acid group containing monomers, such as 2-hydroxyethyl acryloyl phosphate, etc. are mentioned.

In addition, (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylolpropane (meth)acrylamide, etc. (N-substituted) amide-based monomers; (meth)alkylaminoalkyl monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, N - Succinimide monomers such as acryloylmorpholine; maleimide monomers such as N-cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, and N-phenyl maleimide; N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide Itaconimide-type monomers, such as mead and N-lauryl itaconimide, etc. are also mentioned as an example of the monomer for the modification|reformation objective.

Further, as the modifying monomer, vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole vinyl monomers such as vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate-based monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers, such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; Acrylic acid ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate can also be used. Furthermore, isoprene, butadiene, isobutylene, vinyl ether and the like are exemplified.

Moreover, as a monomer which can be copolymerized other than the above, the silane type monomer containing a silicon atom etc. are mentioned. As a silane-type monomer, for example, 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8- Vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltri Ethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc. are mentioned.

In addition, as the copolymerization monomer, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate rate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, Unsaturated double bonds such as (meth)acryloyl group, vinyl group, etc. of esters of (meth)acrylic acid and polyhydric alcohol, such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate Polyester having two or more unsaturated double bonds such as a (meth)acryloyl group or a vinyl group as the same functional group as the monomer component on the backbone of polyester, epoxy, urethane, etc. ) acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, etc. can also be used.

The (meth)acrylic polymer has an alkyl (meth)acrylate as a main component in the weight ratio of the total monomers, and the ratio of the copolymerized monomer in the (meth)acrylic polymer is not particularly limited, but the ratio of the copolymerized monomer is It is preferably about 0 to 20%, about 0.1 to 15%, and more preferably about 0.1 to 10% in the weight ratio of all constituent monomers.

Among these copolymerization monomers, a hydroxyl group-containing monomer and a carboxyl group-containing monomer are preferably used from the viewpoint of adhesiveness and durability. A hydroxyl group-containing monomer and a carboxyl group-containing monomer can be used together. These copolymerization monomers serve as a reaction site with the crosslinking agent when the pressure-sensitive adhesive composition contains the crosslinking agent. A hydroxyl group-containing monomer, a carboxyl group-containing monomer, etc. are highly reactive with an intermolecular cross-linking agent, and therefore are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. A hydroxyl group-containing monomer is preferable in terms of reworkability, and a carboxyl group-containing monomer is preferable in terms of both durability and reworkability.

When a hydroxyl group-containing monomer is contained as the copolymerization monomer, the ratio is preferably 0.01 to 15% by weight, more preferably 0.03 to 10% by weight, and more preferably 0.05 to 7% by weight. When a carboxyl group-containing monomer is contained as the copolymerization monomer, the ratio is preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight, and more preferably 0.2 to 6% by weight.

The (meth)acrylic polymer of the present invention usually has a weight average molecular weight in the range of 500,000 to 3,000,000. Considering durability, especially heat resistance, it is preferable to use a weight average molecular weight of 700,000 to 2.700,000. Furthermore, it is preferable that it is 800,000-2.500,000. When the weight average molecular weight is smaller than 500,000, it is not preferable from the viewpoint of heat resistance. In addition, when the weight average molecular weight is larger than 3,000,000, it is not preferable because a large amount of diluting solvent is required to adjust the viscosity for application, resulting in an increase in cost. In addition, a weight average molecular weight means the value calculated by measuring by GPC (gel permeation chromatography) and calculated by polystyrene conversion.

For the production of such a (meth)acrylic polymer, known production methods such as solution polymerization, radiation polymerization such as UV polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. In addition, any of a random copolymer, a block copolymer, and a graft copolymer may be sufficient as the obtained (meth)acrylic polymer.

In addition, in solution polymerization, ethyl acetate, toluene, etc. are used as a polymerization solvent, for example. As a specific example of solution polymerization, the reaction is usually carried out under reaction conditions of about 5 to 30 hours at about 50 to 70°C by adding a polymerization initiator under an inert gas stream such as nitrogen.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in radical polymerization are not particularly limited, and can be appropriately selected and used. In addition, the weight average molecular weight of the (meth)acrylic polymer can be controlled by the usage amount of the polymerization initiator and the chain transfer agent and the reaction conditions, and the appropriate usage amount is adjusted according to the type of these.

Examples of the radical polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, and 2,2'-azobis[2-(5). -Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'- dimethylene isobutylamidine) and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057). Crude initiators, persulfates such as potassium persulfate and ammonium persulfate, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t -Butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroylperoxide, di-n-octanoylperoxide, 1,1,3,3-tetra Methylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoylperoxide, t-butylperoxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, peroxide-based initiators such as t-butyl hydroperoxide and hydrogen peroxide, redox-based initiators obtained by combining a peroxide and a reducing agent, such as a combination of a persulfate and sodium hydrogensulfite, and a combination of a peroxide and sodium ascorbate, and the like; is not limited to

The radical polymerization initiator may be used alone or in combination of two or more, but the content as a whole is preferably about 0.005 to 1 part by weight, and about 0.02 to 0.5 part by weight, based on 100 parts by weight of the monomer. it is more preferable

As a chain transfer agent, for example, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolic acid, 2,3-dimercapto-1- Propanol etc. are mentioned. Although a chain transfer agent may be used independently or may mix and use 2 or more types, content as a whole is about 0.1 part by weight or less with respect to 100 parts by weight of the total amount of monomer components.

In addition, as an emulsifier used in the case of emulsion polymerization, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sodium sulfate, etc. anionic and nonionic emulsifiers such as emulsifiers, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene-polyoxypropylene block polymers. These emulsifiers may be used alone or in combination of two or more.

In addition, as a reactive emulsifier, as an emulsifier into which a radically polymerizable functional group such as a propenyl group or an allyl ether group is introduced, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05, BC- 10, BC-20 (above, all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), ADEKA LIASOAP SE10N (manufactured by Asahi Denka Co., Ltd.), and the like. Reactive emulsifiers are preferred because they are introduced into the polymer chain after polymerization and thus have good water resistance. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight, and 0.5 to 1 part by weight based on polymerization stability and mechanical stability, based on 100 parts by weight of the total amount of the monomer components.

<pigment>

Various pigments can be used as the pigment to be blended in the pressure-sensitive adhesive composition of the present invention. Examples of the dye include various compounds such as tetraazaporphyrin, porphyrin, cyanine, azo, pyromethene, squarylium, xanthene, oxonol, and squaraine. From the viewpoint of photochromatic gamut, tetraazaporphyrin-based pigments, porphyrin-based pigments, cyanine-based pigments, squalium-based pigments, and squaraine-based pigments are preferred, and tetraazaporphyrin-based pigments are particularly preferred. The dye is specifically disclosed in Japanese Unexamined Patent Publication No. 2011-116818 and the like. As for the said pigment|dye, only 1 type may be used, and 2 or more types may be used together.

It is preferable that the dye has a maximum absorption wavelength in at least one of a wavelength range of 470 to 510 nm and a wavelength range of 570 to 610 nm. A dye having a maximum absorption wavelength in the above wavelength region can absorb and suppress light emission unnecessary for color expression, and is effective for wide color gamut. As a dye having a maximum absorption wavelength in the above wavelength range, a tetraazaporphyrin-based dye can be suitably used. For example, as a dye exhibiting a maximum absorption wavelength in the wavelength range of 570 to 610 nm, Yamamoto Kasei Co., Ltd. tetraazaporphyrin-based compounds (trade names: PD-320, PD311) and Yamada Chemical Co., Ltd. tetraa azaporphyrin-based compounds (trade name: FDG-007); and the like. In addition, the measurement of the maximum absorption wavelength of the dye was performed with a spectrophotometer (V-570 manufactured by JASCO Corporation).

The content of the pigment in the pressure-sensitive adhesive composition of the present invention is adjusted depending on the absorption wavelength range of the pigment, the extinction coefficient, and the type of (meth)acrylic polymer, but is usually 0.01 to 5 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. It is preferable, more preferably 0.05 to 3 parts by weight, more preferably 0.1 to 1 part by weight. In particular, in the case of using a tetraazaporphyrin-based pigment, the above range is preferable.

<Radical generator>

As the radical generator blended in the pressure-sensitive adhesive composition of the present invention, the radical polymerization initiator used in the production of the above-mentioned (meth)acrylic polymer can be exemplified. Among the above radical polymerization initiators, the radical generator to be blended in the pressure-sensitive adhesive composition is preferably a peroxide.

The radical generating agent can generate radically active species by heating or light irradiation to promote crosslinking of the (meth)acrylic polymer in the pressure-sensitive adhesive composition. As the radical generator, in view of workability and stability, it is preferable to use a peroxide having a half-life temperature of 80°C to 160°C for one minute, and more preferably a peroxide having a half life temperature of 90°C to 140°C.

Examples of the peroxide include di(4-t-butylcyclohexyl)peroxydicarbonate (half-life temperature: 92.1°C for 1 minute), di-sec-butylperoxydicarbonate (half-life temperature: 92.4°C for 1 minute), and t- Butylperoxyneodecanoate (1 minute half-life temperature: 103.5°C), t-hexylperoxypivalate (1 minute half-life temperature: 109.1°C), t-butylperoxypivalate (1 minute half-life temperature: 110.3°C) , dilauroyl peroxide (half-life temperature for 1 minute: 116.4° C.), di-n-octanoyl peroxide (half-life temperature for 1 minute: 117.4° C.), 1,1,3,3-tetramethylbutylperoxy-2 -Ethylhexanoate (half-life temperature for 1 minute: 124.3°C), di(4-methylbenzoyl)peroxide (half-life temperature for 1 minute: 128.2°C), dibenzoyl peroxide (half-life temperature for 1 minute: 130.0°C), t- Butylperoxyisobutyrate (half-life temperature for 1 minute: 136.1°C), 1,1-di(t-hexylperoxy)cyclohexane (half-life temperature for 1 minute: 149.2°C), and the like. Among them, di(4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116.4 ° C.), Dibenzoyl peroxide (half-life temperature for 1 minute: 130.0°C) and the like are preferably used.

The half-life of the peroxide is an indicator of the decomposition rate of the peroxide, and refers to the time until the remaining amount of the peroxide becomes half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in manufacturer catalogs and the like, for example, in NOF Corporation's "Organic Peroxide Catalog 9th Edition (May 2003)" and the like. are listed.

The content of the radical generator (particularly peroxide) in the pressure-sensitive adhesive composition of the present invention is adjusted in consideration of the gel fraction, etc. It is decided. Usually, the content of the radical generator is preferably 0.01 to 2 parts by weight, more preferably 0.04 to 1.5 parts by weight, and more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the (meth)acrylic polymer.

Further, in the (meth)acrylic polymer, a radical polymerization initiator (radical generating agent) that was not used in the polymerization reaction at the time of preparation of the (meth)acrylic polymer may remain. The residual radical generator can be used as a radical generator in the pressure-sensitive adhesive composition. In that case, the amount of the remaining radical generating agent can be quantified, and the radical generating agent can be appropriately blended according to the content of the remaining radical generating agent.

In addition, the decomposition amount of the peroxide remaining after the reaction treatment can be measured by, for example, HPLC (high performance liquid chromatography).

More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 mL of ethyl acetate, shaken and extracted with a shaker at 120 rpm at 25 ° C. for 3 hours, and then allowed to stand at room temperature for 3 days. Next, 10 mL of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and filtered with a membrane filter (0.45 μm). About 10 μL of the obtained extract was injected into HPLC and analyzed. It can be said that the amount of peroxide after reaction treatment. .

<Antioxidant>

Examples of the antioxidant to be incorporated into the pressure-sensitive adhesive composition of the present invention include phenol-based, phosphorus-based, sulfur-based and amine-based antioxidants, and at least one selected from these is used. Among these, phenolic antioxidants are preferable.

Specific examples of the phenolic antioxidant include 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, and 2,6-dicyclohexyl-4- as monocyclic phenolic compounds. Methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2, 6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl -4-ethyl-6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, styrenated mixed cresol, DL-α-tocopherol, stearyl β-(3,5-di -t-butyl-4-hydroxyphenyl)propionate, etc., as a bicyclic phenol compound, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidene Bis(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t- butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol], 2,2 '-ethylidenebis(4,6-di-t-butylphenol), 2,2'-butylidenebis(2-t-butyl-4-methylphenol), 3,6-dioxaoctamethylenebis[ 3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate ], 1,6-hexanediolbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2'-thiodiethylenebis[3-(3,5 -di-t-butyl-4-hydroxyphenyl)propionate] and the like as a tricyclic phenolic compound, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane , 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate, 1,3,5-tris[(3,5-di-t-butyl -4-hydroxyphenyl) propionyloxyethyl] isocyanurate, tris (4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl- 2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene and the like as tetrakis[methylene-3-(3 5-di-t-butyl-4-hydroxyphenyl) propionate] methane, etc., bis(3,5-di-t-butyl-4-hydroxybenzylphosphonic acid ethyl) calcium as a phosphorus-containing phenolic compound, Bis(3,5-di-t-butyl-4-hydroxybenzylphosphonic acid ethyl) nickel etc. are mentioned.

Specific examples of the phosphorus antioxidant include trioctyl phosphite, trilauryl phosphite, tritridecyl phosphite, trisisodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, and phenyldi(tridecyl)phosphite. Phyte, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyltridecylphosphite, triphenylphosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite Pite, tris(butoxyethyl)phosphite, tetratridecyl-4,4'-butylidenebis(3-methyl-6-t-butylphenol)-diphosphite, 4,4'-isopropylidene-di Phenolalkyl phosphite (however, alkyl has about 12 to 15 carbon atoms), 4,4'-isopropylidene bis(2-t-butylphenol)-di(nonylphenyl)phosphite, tris(biphenyl)phosphite , tetra(tridecyl)-1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butane diphosphite, tris(3,5-di-t-butyl-4-hydroxy Hydroxyphenyl) phosphite, hydrogenated 4,4'-isopropylidenediphenol polyphosphite, bis(octylphenyl)/bis[4,4'-butylidenebis(3-methyl-6-t-butylphenol) )] 1,6-hexanediol diphosphite, hexatridecyl-1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenol) diphosphite, tris[4,4'- Isopropylidenebis(2-t-butylphenol)]phosphite, tris(1,3-distearoyloxyisopropyl)phosphite, 9,10-dihydro-9-phosphaphenanthrene-10-oxide , tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, distearylpentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenyl 4, 4'-isopropylidenediphenol pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphites and phenylbisphenol-A-pentaerythritol diphosphites; and the like.

As sulfur-based antioxidants, dialkylthiodipropionates and polyhydric alcohol esters of alkylthiopropionic acids are preferably used. As the dialkylthiodipropionate used herein, a dialkylthiodipropionate having an alkyl group of 6 to 20 carbon atoms is preferable, and the polyhydric alcohol ester of alkylthiopropionic acid is an alkylthio dipropionate having an alkyl group of 4 to 20 carbon atoms. Polyhydric alcohol esters of propionic acid are preferred. Examples of the polyhydric alcohol constituting the polyhydric alcohol ester in this case include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and trishydroxyethyl isocyanurate. Examples of such dialkyl thiodipropionates include dilaurylthiodipropionate, dimyristylthiodipropionate and distearylthiodipropionate. On the other hand, examples of polyhydric alcohol esters of alkylthiopropionic acids include glycerin tributylthiopropionate, glycerintrioctylthiopropionate, glycerintrilaurylthiopropionate, glycerintristearylthiopropionate, and trimethylol. Ethanetributylthiopropionate, trimethylolethanetrioctylthiopropionate, trimethylolethanetrilaurylthiopropionate, trimethylolethanetristearylthiopropionate, pentaerythritoltetrabutylthiopropionate, penta Erythritol tetraoctylthiopropionate, pentaerythritol tetralaurylthiopropionate, pentaerythritol tetrastearylthiopropionate, etc. are mentioned.

Specific examples of the amine antioxidant include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2 Polycondensate of ,6,6-tetramethylpiperidineethanol, N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2 ,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, dibutylamine 1,3,5- Triazine N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4 Polycondensates of -piperidyl)butylamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl} {(2, 2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], tetrakis(2,2 ,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis- (1,2,6,6-pentamethyl-4-piperidyl)-2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate, bis-( N-methyl-2,2,6,6-tetramethyl-4-piperidyl)sebacate, 1,1'-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpipette Rajinone), (Mixt 2,2,6,6-tetramethyl-4-piperidyl/tridecyl)-1,2,3,4-butanetetracarboxylate, (Mixt 1,2,2,6 ,6-pentamethyl-4-piperidyl/tridecyl)-1,2,3,4-butanetetracarboxylate, mix [2,2,6,6-tetramethyl-4-piperidyl/β ,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaspiro(5,5)undecane]diethyl]-1,2,3,4-butanetetra Carboxylate, mixt [1,2,2,6,6-pentamethyl-4-piperidyl/β,β,β',β'-tetramethyl-3,9-[2,4,8,10 -Tetraoxaspiro(5,5)undecane]diethyl]-1,2,3,4-butanetetracarboxylate, N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis [N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro Rho-1,3,5-triazine condensate, poly[6-N-morpholyl-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl- 4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imide], N,N'-bis(2,2,6,6-tetra Condensate of methyl-4-piperidyl)hexamethylenediamine and 1,2-dibromoethane, [N-(2,2,6,6-tetramethyl-4-piperidyl)-2-methyl- 2-(2,2,6,6-tetramethyl-4-piperidyl)imino]propionamide; etc. are mentioned.

The content of the antioxidant in the pressure-sensitive adhesive composition of the present invention is determined from the viewpoint of preventing discoloration of the pigment by the radical generating agent. Usually, the content of the antioxidant is preferably in the range of 0.1 part by weight or more with respect to 100 parts by weight of the (meth)acrylic polymer. On the other hand, as the content of the antioxidant increases, the rate of capturing radicals generated from the radical generator increases. As a result, crosslinking inhibition of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition tends to be inhibited, and the gel fraction of the pressure-sensitive adhesive layer decreases, resulting in poor appearance. From this point of view, the content of the antioxidant is preferably 5 parts by weight or less, more preferably 1.5 parts by weight or less, based on 100 parts by weight of the (meth)acrylic polymer. From the viewpoint of achieving both the securing of the gel fraction and the prevention of discoloration of the dye, the content of the antioxidant is preferably 0.1 to 1.5 parts by weight, more preferably 0.2 to 1.0 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer. and more preferably 0.3 to 0.8 parts by weight.

In addition, the weight ratio (A/B) of the amount (A) of the radical generator and the amount (B) of the antioxidant is usually 4 It is preferably less than or equal to, more preferably 2 or less, still more preferably 1.5 or less. On the other hand, the weight ratio (A/B) is usually preferably 0.01 or more, more preferably 0.05 or more, and more preferably designed to satisfy 0.1 or more.

<Crosslinking agent>

Further, in the present invention, a crosslinking agent (excluding the radical generating agent) may be contained in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer. As the crosslinking agent, an organic crosslinking agent or a polyfunctional metal chelate can be used. Examples of the organic crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. A polyfunctional metal chelate is one in which a multivalent metal is covalently bonded or coordinated with an organic compound. Examples of the polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. . Examples of atoms in organic compounds that form a covalent bond or coordinate bond include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

As a crosslinking agent, an isocyanate type crosslinking agent is preferable. Examples of the compound related to the isocyanate-based crosslinking agent include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate. and isocyanate compounds, isocyanurates, biuret-type compounds obtained by adding these isocyanate monomers to trimethylolpropane, etc., and urethane prepolymers obtained by addition reactions such as polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols. Type isocyanate etc. are mentioned. Particularly preferred is a polyisocyanate compound, which is one selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate, or a polyisocyanate compound derived therefrom. Here, one selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate or a polyisocyanate compound derived therefrom includes hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and isophorone diisocyanate. phorone diisocyanate, polyol-modified hexamethylene diisocyanate, polyol-modified hydrogenated xylylene diisocyanate, trimer-type hydrogenated xylylene diisocyanate, and polyol-modified isophorone diisocyanate; and the like. The polyisocyanate compounds exemplified are preferable because they allow the reaction with hydroxyl groups to proceed rapidly using an acid or base contained in the polymer as a catalyst, particularly contributing to the speed of crosslinking.

In the present invention, when an isocyanate-based crosslinking agent is used in combination as a crosslinking agent, while the inhibition of radical crosslinking by oxygen is effectively suppressed by the antioxidant, the three-dimensional crosslinked network of the pressure-sensitive adhesive layer is efficiently formed by the radical generator (e.g., peroxide). can form As a result, it is possible to more effectively prevent the appearance abnormality at the end portion of the polarizing film.

The amount of the crosslinking agent used is preferably 20 parts by weight or less, more preferably 0.01 to 20 parts by weight, and more preferably 0.03 to 10 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer in the pressure-sensitive adhesive composition. In addition, when the amount of the crosslinking agent is greater than 20 parts by weight, moisture resistance is not sufficient, and peeling easily occurs in a reliability test or the like.

In addition, the pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent. Durability can be improved by using a silane coupling agent. As a silane coupling agent, specifically, for example, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 2-(3,4 -Epoxycyclohexyl) ethyltrimethoxysilane and other epoxy group-containing silane coupling agents, 3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyl dimethoxysilane, 3-triethoxy Amino group-containing silane coupling agents such as silyl-N-(1,3-dimethylbutylidene)propylamine and N-phenyl-γ-aminopropyl trimethoxysilane, 3-acryloxypropyl trimethoxysilane, and 3-meta Isocyanate group containing silane coupling agents, such as (meth)acryl group containing silane coupling agents, such as acryloxypropyl triethoxysilane, and 3-isocyanate propyl triethoxysilane, etc. are mentioned.

The silane coupling agent may be used alone or in combination of two or more, but the content as a whole is preferably 0.001 to 5 parts by weight of the silane coupling agent based on 100 parts by weight of the (meth)acrylic polymer, Furthermore, 0.01 to 1 part by weight is preferable, more preferably 0.02 to 1 part by weight, more preferably 0.05 to 0.6 part by weight. It is an amount that improves durability and appropriately maintains the adhesive strength to optical members such as liquid crystal cells.

Further, in the present invention, polyether-modified silicone can be blended in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer. As polyether-modified silicone, what is disclosed in Unexamined-Japanese-Patent No. 2010-275522 can be used, for example.

Further, in the present invention, the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer may contain other known additives, such as colorants, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, and leveling agents. , softeners, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulates, thin materials, etc. can be suitably added depending on the use. Further, within a controllable range, a redox system may be employed by adding a reducing agent.

The pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition, but in forming the pressure-sensitive adhesive layer, it is necessary to sufficiently consider the effects of the crosslinking treatment temperature and crosslinking treatment time, as well as adjusting the addition amount of the radical generator (eg peroxide) and crosslinking agent. desirable.

Depending on the crosslinking agent used, the crosslinking treatment temperature and crosslinking treatment time can be adjusted. The crosslinking treatment temperature is preferably 170°C or lower.

In addition, such crosslinking treatment may be performed at the temperature during the drying step of the pressure-sensitive adhesive layer, or a crosslinking treatment step may be performed separately after the drying step.

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

It is preferable to control the crosslinking so that the gel fraction of the pressure-sensitive adhesive layer is usually 50% by weight or more. Furthermore, the gel fraction of the pressure-sensitive adhesive layer is preferably controlled to be 60% by weight or more from the viewpoint of high-temperature durability. The gel fraction is preferably 75% by weight or more, more preferably 80% by weight or more. On the other hand, since exfoliation tends to occur in durability tests when the gel fraction is too large, the gel fraction is preferably 98% by weight or less, more preferably 95% by weight or less. The gel fraction was measured according to the method described in the Examples.

In addition, when the pressure-sensitive adhesive layer has a thickness of 20 μm, the absolute value of the difference (T1-T2) between the transmittance (T1) before storage at 85° C. for 500 hours and the transmittance (T2) after storage is preferably 50% or less. 40% or less is preferable, more preferably 30% or less, more preferably 10% or less, and more preferably 5% or less. In addition, usually, the value of (T1-T2) becomes a value of "-" due to discoloration of the dye. On the other hand, when the above value is "+", it indicates that there is substantially no discoloration.

In addition, the ratio of the transmittance (T1) to the transmittance (T2) (T2/T1) of the pressure-sensitive adhesive layer is preferably 2 or less, more preferably 1.5 or less, more preferably 1.3 or less, and more preferably 1.2 or less. is preferred, and more preferably 1.1 or less. In addition, the value of the ratio (T2/T1) usually becomes 1 or more due to discoloration of the dye. On the other hand, when the value is less than 1, it indicates that there is substantially no discoloration.

The polarizing film having the pressure-sensitive adhesive layer of the present invention has a pressure-sensitive adhesive layer formed on at least one side of the polarizing film with the pressure-sensitive adhesive composition.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive composition to a separator or the like subjected to peeling treatment, forming an pressure-sensitive adhesive layer by drying and removing a polymerization solvent, and then transferring the pressure-sensitive adhesive composition to a polarizing film, or a method of transferring the pressure-sensitive adhesive composition to a polarizing film. is applied, and a polymerization solvent or the like is dried and removed to form an adhesive layer on a polarizing film. Further, in the application of the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

As the separator subjected to the peeling treatment, a silicone peeling liner is preferably used. In the step of applying and drying the adhesive composition of the present invention on such a liner to form a pressure-sensitive adhesive layer, as a method of drying the pressure-sensitive adhesive, an appropriate method may be appropriately employed depending on the purpose. Preferably, a method of overheating the coating film is used. The heating and drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. By setting the heating temperature within the above range, a pressure-sensitive adhesive having excellent adhesive properties can be obtained.

As for the drying time, an appropriate time may be appropriately employed. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Moreover, an adhesive layer can be formed after forming an anchor layer on the surface of a polarizing film, or performing various adhesion-facilitating treatments, such as a corona treatment and a plasma treatment. Moreover, you may give an adhesion-facilitating process to the surface of an adhesive layer.

Various methods are used as a method of forming the pressure-sensitive adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Methods, such as an extrusion coating method, are mentioned.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm. Preferably it is 2-50 micrometers, More preferably, it is 2-40 micrometers, More preferably, it is 5-35 micrometers.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peeled sheet (separator) until practical use.

Examples of materials constituting the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth and nonwoven fabric; nets, foam sheets, metal foils, and laminates thereof; Although suitable thin sheets etc. are mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride air. A composite film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, etc. are mentioned.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. If necessary, the separator may also be subjected to release and antifouling treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, or the like, or antistatic treatment such as coating, kneading, or vapor deposition. In particular, peelability from the pressure-sensitive adhesive layer can be further improved by appropriately subjecting the surface of the separator to a peeling treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment.

In addition, the sheet subjected to the peeling treatment used in the production of the polarizing film with an adhesive layer can be used as a separator for the polarizing film with an adhesive layer as it is, and simplification is achieved in terms of the process.

As for the polarizing film, one having a transparent protective film on one side or both sides of the polarizer is generally used.

A polarizer is not specifically limited, Various things can be used. As the polarizer, for example, a dichroic substance such as iodine or a dichroic dye is adsorbed to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, and 1 polyene-based oriented films such as axially stretched ones, dehydrated polyvinyl alcohol products, and dehydrochlorinated polyvinyl chloride products; and the like. Among these, a polarizer composed of a polyvinyl alcohol-based film and a dichroic material such as iodine is suitable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and stretching it uniaxially can be created by, for example, dyeing a polyvinyl alcohol-based film by immersing it in an aqueous solution of iodine, and stretching the polyvinyl alcohol-based film 3 to 7 times its original length. It can also be immersed in aqueous solution, such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride, etc. as needed. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol-based film with water, contamination and anti-blocking agents on the surface of the polyvinyl alcohol-based film can be washed, and swelling of the polyvinyl alcohol-based film also has an effect of preventing unevenness such as dyeing. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or stretching may be followed by dyeing with iodine. It can also be stretched in an aqueous solution such as boric acid or potassium iodide or in a water bath.

In addition, as a polarizer, a thin polarizer with a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 µm. It is preferable that such a thin polarizer has little thickness unevenness, excellent visibility, and excellent durability since it has little dimensional change, and also thinning the thickness as a polarizing film.

As a thin polarizer, typically, Japanese Patent Laid-Open No. 51-069644, Japanese Patent Laid-Open No. 2000-338329, WO2010/100917 pamphlet, PCT/JP2010/001460 specification, or Japanese Patent Application No. 2010-269002 specification B. The thin polarizing film described in the specification of Japanese Patent Application No. 2010-263692 can be mentioned. These thin polarizing films can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a resin substrate for stretching in a laminated state and a step of dyeing. According to this manufacturing method, even if the PVA-based resin layer is thin, it is possible to extend it without defects such as breakage due to stretching because it is supported by the resin base material for stretching.

As the thin polarizing film, among manufacturing methods including a step of stretching and a step of dyeing in a laminate state, WO2010/100917 pamphlet, PCT/JP2010/001460 in that it can be stretched at a high magnification and the polarization performance can be improved. It is preferably obtained by a production method including a step of stretching in a boric acid aqueous solution as described in the specification, or the specification of Japanese Patent Application No. 2010-269002 or the specification of Japanese Patent Application No. 2010-263692, particularly Japanese Patent Application No. 2010-269002 It is preferably obtained by a manufacturing method including a step of auxiliary air stretching before stretching in a boric acid aqueous solution described in the specification of No. 2010-263692 or the specification of Japanese Patent Application No. 2010-263692.

As a material constituting the transparent protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, water barrier properties, isotropy and the like is used. Specific examples of such a thermoplastic resin include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, and cyclic polyolefins. resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. In addition, a transparent protective film is bonded to one side of the polarizer by an adhesive layer, but a (meth)acrylic, urethane-based, acrylic urethane-based, epoxy-based, silicone-based thermosetting resin or ultraviolet curable resin can be used as the transparent protective film on the other side. . One or more types of arbitrary appropriate additives may be contained in the transparent protective film. As an additive, a ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a coloring agent etc. are mentioned, for example. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, there is a risk that the high transparency and the like originally possessed by the thermoplastic resin may not be sufficiently expressed.

The thickness of the transparent protective film is not particularly limited as long as the total thickness of the polarizing film is 100 µm or less, and is, for example, about 10 to 90 µm. Preferably it is 15 to 60 μm, more preferably 20 to 50 μm.

A functional layer (surface layer) such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer may be provided on the surface of the transparent protective film to which the polarizer is not adhered.

The adhesive used for bonding the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot-melt-based, radical-curable, and cation-curable adhesives are used. Suitable.

<liquid crystal panel>

The polarizing film having a pressure-sensitive adhesive layer of the present invention is bonded to at least one surface of a liquid crystal cell through the pressure-sensitive adhesive layer of the polarizing film having the pressure-sensitive adhesive layer to form a liquid crystal panel. The polarizing film having the pressure-sensitive adhesive layer of the present invention is suitably used on the viewing side of a liquid crystal cell.

Any type of liquid crystal cell, such as TN type, STN type, π type, VA type or IPS type, can be used for the liquid crystal cell, but an IPS mode liquid crystal cell is suitably used for the liquid crystal panel of the present invention.

In addition to the polarizing film, other optical layers may be applied to the formation of the liquid crystal panel. The optical layer is not particularly limited, but for example, a liquid crystal panel such as a reflector, a transflective plate, a retardation plate (including a 1/2 or 1/4 wave plate), a visual compensation film, a luminance enhancing film, or the like. An optical layer that may be used for the formation of may be used in one layer or two or more layers on the viewing side and/or the back side of the liquid crystal cell.

<Liquid crystal display device>

The liquid crystal panel is used for the liquid crystal display device, and it is formed by appropriately assembling constituent parts such as a lighting system and attaching a drive circuit as needed. Further, in the formation of the liquid crystal display device, for example, a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, and the like are formed in one or two layers at appropriate locations. can be placed above. In addition, an appropriate liquid crystal display device such as one using a backlight or a reflector for the lighting system can be formed.

Example

The present invention will be specifically described below with reference to examples, but the present invention is not limited by these examples. In addition, all parts and % in each case are based on weight. The room temperature leaving conditions, which are not particularly specified below, are all 23° C. and 65% RH.

<Measurement of weight average molecular weight of (meth)acrylic polymer>

The weight average molecular weight (Mw) of the (meth)acrylic polymer was measured by GPC (gel permeation chromatography). Mw/Mn was also measured in the same way.

・Analyzer: manufactured by Tosoh Corporation, HLC-8120GPC

・Column: manufactured by Tosoh Corporation, G7000H _XL +GMH _XL +GMH _XL

・Column size: 7.8 mmφ × 30 cm each, total 90 cm

Column temperature: 40℃

・Flow rate: 0.8mL/min

・Injection amount: 100μL

・Eluent: tetrahydrofuran

Detector: Differential refractometer (RI)

・Standard sample: polystyrene

<Preparation of polarizing film>

A polyvinyl alcohol film having a thickness of 80 µm was stretched up to 3 times between rolls at different speed ratios at 30°C in a 0.3% iodine solution while dyeing for 1 minute. After that, it was immersed for 0.5 minutes in an aqueous solution containing boric acid at a concentration of 4% and potassium iodide at a concentration of 10% at 60°C, while the total draw ratio was stretched to 6 times. Next, after washing by immersing for 10 seconds in an aqueous solution containing 1.5% potassium iodide at 30°C, drying was performed at 50°C for 4 minutes to obtain a polarizer having a thickness of 30 μm. A triacetyl cellulose film having a thickness of 80 μm subjected to saponification treatment was bonded to both surfaces of the polarizer with a polyvinyl alcohol-based adhesive to prepare a polarizing film.

<Preparation of (meth)acrylic polymer>

A monomer mixture containing 100 parts of butyl acrylate, 0.01 part of 2-hydroxyethyl acrylate, and 5 parts of acrylic acid was charged into a reaction vessel equipped with a cooling pipe, a nitrogen inlet pipe, a thermometer and a stirring device. In addition, with respect to 100 parts of the monomer mixture, 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with 100 parts of ethyl acetate, and nitrogen gas was introduced with gentle stirring to replace nitrogen, and then the flask A polymerization reaction was carried out for 8 hours while maintaining the liquid temperature at around 55°C to prepare an acrylic polymer solution (solid content concentration: 30% by weight) with a weight average molecular weight (Mw) of 1.8 million and Mw/Mn = 4.1.

Example 1

(Preparation of adhesive composition)

Regarding 100 parts of the solid content of the acrylic polymer solution prepared above,

0.23 part of a radical generator (benzoyl peroxide, trade name NYPER BMT manufactured by NOF Corporation);

1 part of an isocyanate-based crosslinking agent (trade name Coronate L manufactured by Tosoh Corporation);

0.25 part of a tetraazaporphyrin-based dye (trade name PD-320 manufactured by Yamamoto Kasei Co., Ltd.: has a maximum absorption wavelength at a wavelength of 595 nm); and

0.25 part of a phenolic antioxidant (product name IRGANOX 1010, manufactured by BASF Japan Ltd.) was blended to obtain an adhesive composition.

(Production of pressure-sensitive adhesive layer)

The pressure-sensitive adhesive composition was uniformly applied on the surface of a polyethylene terephthalate film (PET substrate) treated with a silicone-based release agent using a fountain coater, and dried in an air circulation constant temperature oven at 155° C. for 2 minutes to form a thickness of 20 μm on the surface of the PET substrate. After forming the pressure-sensitive adhesive layer, the same PET substrate as described above was bonded to the pressure-sensitive adhesive layer to obtain an adhesive film having PET substrates on both sides of the pressure-sensitive adhesive layer.

Examples 2 to 12, Comparative Examples 1 to 3

In Example 1, in preparing the adhesive composition, an adhesive film was produced in the same manner as in Example 1, except that the amount of dye, radical generator, and antioxidant was changed as shown in Table 1.

The following evaluation was performed about the adhesive film (adhesive layer) obtained by the said Example and comparative example. Table 1 shows the evaluation results.

<Measurement of gel fraction>

On the polyethylene terephthalate film treated with the silicone-based release agent, each of the PSA compositions in Examples and Comparative Examples before creation of the adhesive film was applied so that the thickness after drying was 20 μm, and after application, the same drying conditions as in each example (temperature , time) to form a pressure-sensitive adhesive layer, and after leaving it to stand for 1 hour under the conditions of a temperature of 23° C. and a humidity of 65% RH, the gel fraction of the pressure-sensitive adhesive layer was measured.

For the gel fraction, take 0.2 g of the pressure-sensitive adhesive layer, wrap it in a pre-weighed fluorine resin (TEMISH NTF-1122, manufactured by Nitto Denko Corporation) (Wa), tie the optical pressure-sensitive adhesive so that it does not leak, and measure the weight (Wb) It was measured and put into a sample bottle. 40 cc of ethyl acetate was added and left to stand for 1 hour or 7 days. Then, the fluororesin was taken out, dried on an aluminum cup at 130°C for 2 hours, the weight (Wc) of the fluororesin containing the sample was measured, and the gel fraction was determined by the following formula (I).

Formula (I): Gel fraction = (W _c -W _a )/(W _b -W _a )×100 (% by weight)

<Measurement of transmittance>

After peeling the PET base material on one side from the adhesive film obtained by the Example and the comparative example, the adhesive layer side was bonded to the alkali-free glass. After that, the other PET was peeled off, and what bonded an acrylic film having a thickness of 60 μm to the exposed pressure-sensitive adhesive layer was used as a sample. The sample was put into an oven at 85° C. for 1000 hours and taken out after performing a durability test. The transmittance (T1) before and after the durability test (T2) of the sample was measured. The transmittance was measured under the condition that the sample was at 23°C. The transmittance was measured for the sample. The acrylic film has no effect on transmittance.

The results are shown in Table 1. In Table 1, the difference (T1-T2) of the transmittance (T1) and the transmittance (T2), and the ratio (T2/T1) are shown together. The transmittance was measured using a spectral transmittance meter having an integrating sphere (Dot-3c from Murakami Color Research Laboratory).

Claims (17)

Contains (meth)acrylic polymers, pigments, radical generators and antioxidants,
The pressure-sensitive adhesive composition for a polarizing film, characterized in that it contains 0.01 to 2 parts by weight of the radical generator based on 100 parts by weight of the (meth)acrylic polymer. According to claim 1,
The said dye has a maximum absorption wavelength in at least one of a wavelength range of 470-510 nm and a wavelength range of 570-610 nm, The adhesive composition for polarizing films characterized by the above-mentioned. According to claim 1 or 2,
The pressure-sensitive adhesive composition for a polarizing film, characterized in that the dye is a tetraazaporphyrin-based dye. According to claim 1 or 2,
The pressure-sensitive adhesive composition for a polarizing film, characterized in that the pigment is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. According to claim 1 or 2,
The pressure-sensitive adhesive composition for a polarizing film, characterized in that the radical generator is a peroxide. delete According to claim 1 or 2,
An adhesive composition for a polarizing film, characterized in that the antioxidant is a phenolic antioxidant. According to claim 1 or 2,
An adhesive composition for a polarizing film, characterized in that the antioxidant is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. According to claim 1 or 2,
The pressure-sensitive adhesive composition for a polarizing film, characterized in that the weight ratio (A / B) of the amount (A) of the radical generator and the amount (B) of the antioxidant is 4 or less. According to claim 1 or 2,
A pressure-sensitive adhesive composition for a polarizing film, characterized by further containing a crosslinking agent. The adhesive layer for polarizing films characterized by being formed of the adhesive composition for polarizing films of Claim 1 or 2. According to claim 11,
A pressure-sensitive adhesive layer for a polarizing film, characterized in that the gel fraction is 50 to 98% by weight. According to claim 11,
In the case of the pressure-sensitive adhesive layer having a thickness of 20 μm, the absolute value of the difference (T1-T2) between transmittance (T1) before storage at 85 ° C. for 500 hours and transmittance (T2) after storage is 50% or less. . According to claim 11,
In the case of the pressure-sensitive adhesive layer having a thickness of 20 μm, the ratio (T2 / T1) of the transmittance (T2) after storage at 85 ° C. for 500 hours and the transmittance (T1) before (T2 / T1) is 2 or less. A polarizing film having a pressure-sensitive adhesive layer characterized in that the pressure-sensitive adhesive layer for polarizing films according to claim 12 is formed on at least one side of the polarizing film. A liquid crystal cell and a polarizing film having the pressure-sensitive adhesive layer according to claim 15 on at least one surface of the liquid crystal cell are bonded together through the pressure-sensitive adhesive layer of the polarizing film having the pressure-sensitive adhesive layer. A liquid crystal display device comprising the liquid crystal panel according to claim 16.