WO2018164049A1 - Adhesive composition for polarized films, adhesive layer for polarized films, polarized film having adhesive layer, liquid crystal panel, and liquid crystal display device - Google Patents

Abstract

The present invention pertains to an adhesive composition for polarized films characterized by containing a (meth)acrylic polymer, a dye, a radical generator, and an antioxidant. The adhesive composition for polarized films according to the present invention has good temporal stability, and can maintain a wider color gamut provided by the dye.

Description

Adhesive composition for polarizing film, adhesive layer for polarizing film, polarizing film with adhesive layer, liquid crystal panel and liquid crystal display device

The present invention relates to a pressure-sensitive adhesive composition for a polarizing film and a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. Moreover, this invention relates to the optical film with an adhesive layer in which the said adhesive layer is formed in the at least single side | surface of a polarizing film. Furthermore, this invention relates to the liquid crystal panel using the said optical film with an adhesive layer, and the liquid crystal display device which has the said liquid crystal panel.

In an image display device or the like, it is indispensable to dispose polarizing elements on both sides of a liquid crystal cell because of its image forming method, and a polarizing film is generally attached. When sticking the said polarizing film to a liquid crystal cell, an adhesive is normally used. Moreover, since adhesion | attachment of a polarizing film and a liquid crystal cell reduces the loss of light normally, each material is closely_contact | adhered using the adhesive. In such a case, the pressure-sensitive adhesive has a pressure-sensitive adhesive layer provided in advance as a pressure-sensitive adhesive layer on one side of the polarizing film because it has a merit that a drying step is not required to fix the polarizing film. A film is generally used.

Further, it has been proposed that a dye or pigment is added to the pressure-sensitive adhesive layer and colored to give a polarizing film an arbitrary hue to obtain a high-contrast liquid crystal display (Patent Document 1). In recent years, brightness and vividness (that is, wide color gamut) have been demanded for image display devices, and organic EL display devices (OLEDs) have been attracting attention. Is required. For example, as a method for widening the color gamut of a liquid crystal display device, a polarizing film is provided on one or both sides of the liquid crystal cell via an adhesive layer containing a dye exhibiting an absorption maximum wavelength in a specific wavelength (560 to 610 nm) range. Lamination is proposed (Patent Documents 2 and 3).

Noto 3052812 specification JP 2011-039093 A JP 2014-092611 A

Generally, an acrylic pressure-sensitive adhesive composition having a (meth) acrylic polymer as a base polymer is used as the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer for a polarizing film. In the acrylic pressure-sensitive adhesive composition, in addition to the (meth) acrylic polymer, a radical generator (for example, peroxide) may be used as a crosslinking agent to form a radical-crosslinked pressure-sensitive adhesive layer. . Further, when the (meth) acrylic polymer in the acrylic pressure-sensitive adhesive composition is prepared by heat or radiation curing of a monomer component, a radical polymerization initiator is contained in the pressure-sensitive adhesive composition.

However, it was found that when a dye was further contained in the pressure-sensitive adhesive composition containing the radical generator, radicals were generated from the radical generator and the radicals decomposed the dye. As a result, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition gradually fades even if it is initially colored with a pigment. Thus, when the dye in the pressure-sensitive adhesive layer deteriorates with time, it has been difficult to maintain a wide color gamut with the dye.

The present invention is a pressure-sensitive adhesive composition for a polarizing film, which contains a (meth) acrylic polymer, a dye and a radical generator, has good stability over time, and can maintain a wide color gamut due to the dye. It aims at providing the adhesive composition for polarizing films.

Moreover, this invention provides the adhesive layer formed with the said adhesive composition for polarizing films, provides the optical film with an adhesive layer which has the said adhesive layer, Furthermore, the said optical with an adhesive layer It is an object of the present invention to provide a liquid crystal panel using a film and to provide a liquid image display device using the liquid crystal panel.

As a result of intensive studies to solve the above problems, the present inventors have found the following pressure-sensitive adhesive composition for polarizing film, and have completed the present invention.

That is, this invention relates to the adhesive composition for polarizing films characterized by containing a (meth) acrylic-type polymer, a pigment | dye, antioxidant, and a radical generator.

In the pressure-sensitive adhesive composition for polarizing film, the dye having a maximum absorption wavelength in at least one of a wavelength region of 470 to 510 nm and a wavelength region of 570 to 610 nm can be used.

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

In the pressure-sensitive adhesive composition for polarizing film, the pigment is preferably contained in an amount of 0.01 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.

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

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

In the pressure-sensitive adhesive composition for polarizing film, the antioxidant may be a phenolic antioxidant.

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

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

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

The present invention also relates to a pressure-sensitive adhesive layer for a polarizing film, which is formed of the pressure-sensitive adhesive composition for a polarizing film.

The polarizing film pressure-sensitive adhesive layer preferably has a gel fraction of 50 to 98% by weight.

When the thickness of the pressure-sensitive adhesive layer for polarizing film is 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 that is 50%. The following is preferable.

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

The present invention also relates to a polarizing film with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer for a polarizing film is formed on at least one side of the polarizing film.

In the present invention, the polarizing film with the pressure-sensitive adhesive layer is bonded to at least one surface of the liquid crystal cell and the liquid crystal cell via the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer. The present invention relates to a liquid crystal panel.

Furthermore, the present invention relates to a liquid crystal display device comprising the liquid crystal panel.

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

Moreover, the pressure-sensitive adhesive composition for polarizing film of the present invention contains a radical generator such as peroxide. The radical generator functions as, for example, a cross-linking agent for the (meth) acrylic polymer, and can control the gel fraction of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for polarizing film to a desired range. A pressure-sensitive adhesive layer having a good appearance can be formed.

As described above, since the dye and the radical generator coexist in the pressure-sensitive adhesive composition for polarizing film of the present invention, there is a concern that the dye may be faded by radicals generated from the radical generator. However, the pressure-sensitive adhesive composition for polarizing film of the present invention contains an antioxidant, captures radicals by the antioxidant, suppresses discoloration (decomposition) of the dye, and is stable over time. Wide color gamut can be maintained.

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

<(Meth) acrylic polymer>
The pressure-sensitive adhesive composition for an optical film of the present invention contains a (meth) acrylic polymer as a main component as a base polymer. The main component refers to a component having the highest content ratio among the total solids contained in the pressure-sensitive adhesive composition, for example, a component that occupies more than 50% by weight of the total solids contained in the pressure-sensitive adhesive composition. Furthermore, it refers to a component occupying more than 70% by weight.

The (meth) acrylic polymer usually contains alkyl (meth) acrylate as a main component as a monomer unit. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

Examples of the alkyl (meth) acrylate that constitutes the main skeleton of the (meth) acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. These can be used alone or in combination. These alkyl groups preferably have an average carbon number of 3 to 9.

Also, alkyl (meth) acrylates containing aromatic rings such as phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are used from the viewpoints of adhesive properties, durability, retardation adjustment, refractive index adjustment, and the like. be able to.

In the (meth) acrylic polymer, one or more having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group for the purpose of improving adhesiveness and heat resistance These copolymerizable monomers can be introduced by copolymerization. Specific examples of such copolymerizable monomers include, for example, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid 6 Hydroxyl-containing monomers such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride Physical group-containing monomer; Caprolactone adduct of crylic acid; styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene Examples thereof include sulfonic acid group-containing monomers such as sulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

Also, (N-substituted) amides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Monomer; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid t-butylaminoethyl, etc. (meth) acrylic alkylaminoalkyl monomers; (meth) acrylic (Meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl acid and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- ( (Meta) acryloyl-8- Succinimide monomers such as xoxyoctamethylene succinimide and N-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; N-methylitaconimide, N-ethylitacon Examples of monomers for modification include itaconimide monomers such as imide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexylitaconimide, N-cyclohexyl leuconconimide, N-lauryl itaconimide, and the like. .

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

Furthermore, examples of copolymerizable monomers other than the above include silane-based monomers containing silicon atoms. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

Examples of copolymer monomers include tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neo Pentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate (Meth) acryloyl such as esterified product of (meth) acrylic acid and polyhydric alcohol such as caprolactone-modified dipentaerythritol hexa (meth) acrylate Groups such as polyfunctional monomers having 2 or more unsaturated double bonds such as vinyl groups, vinyl groups and the like, and functional groups similar to the monomer components on the backbone of polyester, epoxy, urethane, etc. (meth) acryloyl groups, vinyl groups, etc. Polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, or the like to which two or more saturated double bonds have been added can also be used.

The (meth) acrylic polymer has an alkyl (meth) acrylate as a main component in the weight ratio of all constituent monomers, and the ratio of the copolymerizable monomer in the (meth) acrylic polymer is not particularly limited. The ratio of the polymerization monomer 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 the constituent monomers.

Among these copolymer monomers, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferably used from the viewpoint of adhesion and durability. A hydroxyl group-containing monomer and a carboxyl group-containing monomer can be used in combination. These copolymerization monomers serve as reaction points with the crosslinking agent when the pressure-sensitive adhesive composition contains a crosslinking agent. Since a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and the like are rich in reactivity with an intermolecular crosslinking agent, they are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. A hydroxyl group-containing monomer is preferable from the viewpoint of reworkability, and a carboxyl group-containing monomer is preferable from the viewpoint of achieving both durability and reworkability.

When the copolymerization monomer contains a hydroxyl group-containing monomer, the proportion is preferably 0.01 to 15% by weight, more preferably 0.03 to 10% by weight, and even more preferably 0.05 to 7% by weight. preferable. When the copolymerization monomer contains a carboxyl group-containing monomer, the proportion thereof is preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight, and further preferably 0.2 to 6% by weight. preferable.

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. In view of durability, particularly heat resistance, it is preferable to use those having a weight average molecular weight of 700,000 to 2,700,000. Further, it is preferably 800,000 to 2.5 million. A weight average molecular weight of less than 500,000 is not preferable in terms of heat resistance. On the other hand, if the weight average molecular weight is more than 3 million, a large amount of dilution solvent is required to adjust the viscosity for coating, which is not preferable. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

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. Further, the (meth) acrylic polymer obtained may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

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

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

Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl- 2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2, Azo-based initiators such as 2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057), persulfates such as potassium persulfate and ammonium persulfate Salt, di (2-ethylhexyl) peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, di-sec- Tilperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1, 3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylper Peroxides such as oxy) cyclohexane, t-butyl hydroperoxide, hydrogen peroxide, peroxides and sodium bisulfite, peroxides and sodium ascorbate, peroxides and reducing agents And redox initiators combined with The present invention is not limited to.

The radical polymerization initiator may be used alone or in combination of two or more, but the total content is 0.005 to 1 weight with respect to 100 parts by weight of the monomer. Part is preferable, and about 0.02 to 0.5 part by weight is more preferable.

Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

Examples of the emulsifier used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block polymer and the like can be mentioned. These emulsifiers may be used alone or in combination of two or more.

Furthermore, as reactive emulsifiers, emulsifiers into which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05 BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE10N (manufactured by Asahi Denka Kogyo Co., Ltd.) Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is preferably 0.3 to 5 parts by weight with respect to 100 parts by weight of the total amount of monomer components, and more preferably 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability.

<Dye>
Various pigments can be used as the pigment 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, squaraine, and the like. The dye is preferably a tetraazaporphyrin dye, a porphyrin dye, a cyanine dye, a squalium dye, or a squarain dye, and particularly preferably a tetraazaporphyrin dye from the viewpoint of widening the color gamut. Specifically, the dye is disclosed in JP 2011-116818 A. Only 1 type may be used for the said pigment | dye and it can also use 2 or more types together.

The dye preferably 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. The dye having the maximum absorption wavelength in the wavelength range can absorb light emission unnecessary for color expression and suppress the light emission, and is effective for widening the color range. As a dye having a maximum absorption wavelength in the wavelength range, a tetraazaporphyrin-based dye can be suitably used. For example, as a dye exhibiting the maximum absorption wavelength in the wavelength range of 570 to 610 nm, tetraazaporphyrin compounds (trade names: PD-320, PD311) manufactured by Yamamoto Kasei Co., Ltd., tetraazaporphyrin compounds manufactured by Yamada Chemical Industries ( Product name: FDG-007) and the like. The maximum absorption wavelength of the dye was measured with a spectrophotometer (V-570 manufactured by JASCO Corporation).

The content of the dye in the pressure-sensitive adhesive composition of the present invention is adjusted by the absorption wavelength range of the dye, the extinction coefficient, and the type of the (meth) acrylic polymer, but is usually 100 parts by weight of the (meth) acrylic polymer. The amount is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and further preferably 0.1 to 1 part by weight. In particular, the above range is preferable when a tetraazaporphyrin-based dye is used.

<Radical generator>
As a radical generating agent mix | blended with the adhesive composition of this invention, the radical polymerization initiator used in the case of manufacture of the said (meth) acrylic-type polymer can be illustrated. Among the radical polymerization initiators, the radical generator added to the pressure-sensitive adhesive composition is preferably a peroxide.

The radical generator can generate radical active species by heating or light irradiation to advance crosslinking of the (meth) acrylic polymer in the pressure-sensitive adhesive composition. As the radical generator, it is preferable to use a peroxide having a half-life temperature of 80 ° C. to 160 ° C. in consideration of workability and stability, and a peroxide having a temperature of 90 ° C. to 140 ° C. is preferably used. More preferably it is used.

Examples of the peroxide include di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature). : 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5 ° C.), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C.), t -Butylperoxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide (1 minute half-life temperature: 116.4 ° C), di-n-octanoyl peroxide (1 minute half-life temperature) 117.4 ° C.), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C.), di (4-methylbenzoyl) -Oxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C), t-butylperoxyisobutyrate (1 minute half-life temperature: 136.1 ° C) ), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.) and the like. Among them, since the crosslinking reaction efficiency is particularly excellent, 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 (1 minute half-life temperature: 130.0 ° C.) and the like are preferably used.

The half-life of the peroxide is an index representing the decomposition rate of the peroxide, and means the time until the remaining amount of peroxide is halved. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer catalog, for example, “Organic peroxide catalog 9th edition by Nippon Oil & Fats Co., Ltd.” (May 2003) ".

The content of the radical generator (especially peroxide) in the pressure-sensitive adhesive composition of the present invention is adjusted for the workability, reworkability, cross-linking stability, peelability, etc. of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. Therefore, it is determined in consideration of the gel fraction and the like. 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 with respect to 100 parts by weight of the (meth) acrylic polymer. Further, 0.05 to 1 part by weight is preferable.

In the (meth) acrylic polymer, a radical polymerization initiator (radical generator) that has not been used for the polymerization reaction in the 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 residual radical generator can be quantified, and the radical generator can be appropriately blended according to the content of the residual radical generator.

The remaining peroxide decomposition amount 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 was taken out, immersed in 10 mL of ethyl acetate, extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker, and then room temperature. Leave for 3 days. Next, 10 mL of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μL of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

<Antioxidant>
Examples of the antioxidant blended in 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, a phenolic antioxidant is preferable.

Specific examples of the phenolic antioxidant include 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6- Dicyclohexyl-4-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'-butylidenebis (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'-ethylidene Bis (4,6-di-t-butylphenol), 2,2′-butylidenebis (2-t-butyl-4-methylphenol), 3,6-dioxaoctame Tylene bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], triethylene glycol bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1 , 6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thiodiethylene bis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate] and the like as 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-tris (2 , 6-Dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris [(3,5-di-tert-butyl-4-hydroxy Phenyl) propionyloxyethyl] isocyanurate, tris (4-tert-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5 -Di-t-butyl-4-hydroxybenzyl) benzene or the like as a tetracyclic phenol compound, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane or the like, Phosphorus-containing phenol compounds such as bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium, bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) nickel, etc. Can be mentioned.

Specific examples of phosphorus antioxidants include trioctyl phosphite, trilauryl phosphite, tristridecyl phosphite, trisisodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di (tridecyl) phos Phyto, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (Butoxyethyl) phosphite, tetratridecyl-4,4'-butylidenebis (3-methyl-6-tert-butylphenol) -diphosphite, 4,4'-isopropylidene-diphenol alkylphos Phyto (however, alkyl has about 12 to 15 carbon atoms), 4,4'-isopropylidenebis (2-t-butylphenol) di (nonylphenyl) phosphite, tris (biphenyl) phosphite, tetra (tridecyl)- 1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butane diphosphite, tris (3,5-di-tert-butyl-4-hydroxyphenyl) phosphite, hydrogenation -4,4'-isopropylidene diphenol polyphosphite, bis (octylphenyl) bis [4,4'-butylidene bis (3-methyl-6-t-butylphenol)] 1,6-hexanediol diphosphite Hexatridecyl-1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenol) diphos Ite, tris [4,4'-isopropylidenebis (2-tert-butylphenol)] phosphite, tris (1,3-distearoyloxyisopropyl) phosphite, 9,10-dihydro-9-phosphaphenanthrene -10-oxide, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, distearyl pentaerythritol 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-methyl) Phenyl) pentaerythritol diphosphite and phenylbis Such as phenol -A- pentaerythritol diphosphite, and the like.

As the sulfur-based antioxidant, dialkylthiodipropionate and polyhydric alcohol ester of alkylthiopropionic acid are preferably used. The dialkylthiodipropionate used here is preferably a dialkylthiodipropionate having an alkyl group having 6 to 20 carbon atoms, and the polyhydric alcohol ester of alkylthiopropionic acid is an alkyl having 4 to 20 carbon atoms. Polyalkyl alcohol esters of alkylthiopropionic acid having a group are preferred. In this case, examples of the polyhydric alcohol constituting the polyhydric alcohol ester include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and trishydroxyethyl isocyanurate. Examples of such dialkylthiodipropionate include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate. On the other hand, as the polyhydric alcohol ester of alkylthiopropionic acid, for example, glycerin tributylthiopropionate, glycerin trioctylthiopropionate, glycerin trilauryl thiopropionate, glycerin tristearyl thiopropionate, trimethylol ethane tributyl Thiopropionate, trimethylol ethane trioctyl thiopropionate, trimethylol ethane trilauryl thiopropionate, trimethylol ethane tristearyl thiopropionate, pentaerythritol tetrabutyl thiopropionate, pentaerythritol tetraoctyl thiopro Pionate, pentaerythritol tetralauryl thiopropionate, pentaerythritol tetrastearyl thiopropionate, etc. It can be 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 , 6,6-tetramethylpiperidineethanol polycondensate, 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-piperidyl) butylamine polycondensate, 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-pepyridyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n- Butyl malonate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,1 '-(1,2-ethanediyl) bis (3,3,5,5- Tetramethylpiperazinone), Mixed 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, (mixed 1,2,2,6,6-pentamethyl-4- Piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed [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-butanetetracarboxylate, mixed [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-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-tetramethyl-4-piperidyl) hexamethylenediamine And 1,2-dibromoethane condensate, [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6,6-tetramethyl- 4-piperidyl) imino] propionamide and the like Door can be.

The content of the antioxidant in the pressure-sensitive adhesive composition of the present invention is determined from the viewpoint of preventing the dye from fading due to the radical generator. Usually, the content of the antioxidant is preferably in the range of 0.1 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic polymer. On the other hand, when the content of the antioxidant increases, the ratio of capturing radicals generated from the radical generator increases. As a result, cross-linking inhibition of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is liable to occur, and the gel fraction of the pressure-sensitive adhesive layer tends to decrease, 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 with respect to 100 parts by weight of the (meth) acrylic polymer. From the standpoint of ensuring both the gel fraction and preventing fading of the pigment, the content of the antioxidant is 0.1 to 1.5 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. It is preferably 0.2 to 1.0 part by weight, more preferably 0.3 to 0.8 part by weight.

Further, the weight ratio (A / B) between the amount of the radical generator used (A) and the amount of the antioxidant used (B) ensures the gel fraction of the pressure-sensitive adhesive layer and prevents the dye from fading. From the viewpoint of achieving both, it is usually preferably 4 or less, more preferably 2 or less, and even 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 further preferably designed to satisfy 0.1 or more.

<Crosslinking agent>
Furthermore, in this invention, a crosslinking agent (except the said radical generator) can be contained in the adhesive composition which forms an 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 an isocyanate crosslinking agent, an epoxy crosslinking agent, and an imine crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently 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, and Ti. Can be mentioned. Examples of the atom in the organic compound that is covalently or coordinately bonded 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.

As the crosslinking agent, an isocyanate-based crosslinking agent is preferable. Examples of the compound relating to the isocyanate-based crosslinking agent include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, tetramethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and these isocyanate monomers. Examples include isocyanate compounds added with trimethylolpropane, isocyanurates, burette compounds, and urethane prepolymer isocyanates such as polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols that have undergone addition reactions. be able to. Particularly preferred is a polyisocyanate compound, which is one or a polyisocyanate compound derived from one selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate. Here, hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, polyol-modified is selected from the group consisting of hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate or a polyisocyanate compound derived therefrom. Examples include hexamethylene diisocyanate, polyol-modified hydrogenated xylylene diisocyanate, trimer-type hydrogenated xylylene diisocyanate, and polyol-modified isophorone diisocyanate. The exemplified polyisocyanate compound is preferable because the reaction with a hydroxyl group proceeds rapidly, particularly using an acid or base contained in the polymer as a catalyst, and thus contributes to the speed of crosslinking.

In the present invention, when an isocyanate-based crosslinking agent is used in combination as a crosslinking agent, the radical crosslinking agent (for example, peroxide) is used for adhesion while effectively inhibiting the inhibition of radical crosslinking by oxygen with an antioxidant. The three-dimensional crosslinked network of the agent layer can be formed efficiently. As a result, it is possible to more effectively prevent the appearance abnormality at the end of the polarizing film.

The amount of the cross-linking agent used is preferably 20 parts by weight or less, more preferably 0.01 to 20 parts by weight, and further preferably 0.000 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer in the pressure-sensitive adhesive composition. 03 to 10 parts by weight are preferred. When the amount of the crosslinking agent is more than 20 parts by weight, the moisture resistance is not sufficient, and peeling easily occurs in a reliability test or the like.

Furthermore, the pressure-sensitive adhesive composition of the present invention can contain a silane coupling agent. The durability can be improved by using a silane coupling agent. Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3, Epoxy group-containing silane coupling agents such as 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl- Amino group-containing silane coupling agents such as N- (1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltri (Meth) a, such as ethoxysilane Lil group-containing silane coupling agents, such as isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like.

The silane coupling agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. The silane coupling agent is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 1 part by weight, further preferably 0.02 to 1 part by weight, further 0.05 to 0.6 part by weight. Is preferred. This is an amount that improves the durability and appropriately maintains the adhesive force to an optical member such as a liquid crystal cell.

Furthermore, in the present invention, polyether-modified silicone can be blended in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer. As the polyether-modified silicone, for example, those disclosed in JP 2010-275522 A can be used.

Furthermore, in the present invention, the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer may contain other known additives, such as powders such as colorants and pigments, dyes, surfactants, plastics, and the like. Agents, tackifiers, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. Can be added as appropriate according to the intended use. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range.

The pressure-sensitive adhesive composition forms a pressure-sensitive adhesive layer. In forming the pressure-sensitive adhesive layer, the amount of radical generator (for example, peroxide) and crosslinking agent is adjusted, and the crosslinking treatment temperature and crosslinking are adjusted. It is preferable to fully consider the influence of the processing time.

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

Further, such crosslinking treatment may be performed at the temperature during the drying step of the pressure-sensitive adhesive layer, or may be performed by providing a separate crosslinking treatment step 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. Further, 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, more preferably 80% by weight or more. On the other hand, if the gel fraction becomes too large, peeling tends to occur in the durability test. Therefore, the gel fraction is preferably 98% by weight or less, and more preferably 95% by weight or less. The gel fraction is measured according to the method described in the examples.

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 that is 50% or less. It is preferably 40% or less, more preferably 30% or less, further preferably 10% or less, and most preferably 5% or less. Normally, the value of (T1-T2) becomes a value of “−” due to fading of the dye. On the other hand, when the value is “+”, it indicates that there is substantially no fading.

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

The polarizing film with a pressure-sensitive adhesive layer of the present invention is one in which a pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition on at least one side of the polarizing film.

As a method for forming the pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive composition is applied to a release-treated separator, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, and then transferred to a polarizing film, or The pressure-sensitive adhesive composition is prepared by applying the pressure-sensitive adhesive composition to a polarizing film, drying and removing the polymerization solvent, and forming a pressure-sensitive adhesive layer on the polarizing film. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive composition of the present invention on such a liner and drying to form a pressure-sensitive adhesive layer, a method for drying the pressure-sensitive adhesive is appropriately employed depending on the purpose. obtain. Preferably, a method of heating and drying 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, an adhesive having excellent adhesive properties can be obtained.

Appropriate time can be adopted as the drying time. 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.

Also, the pressure-sensitive adhesive layer can be formed after forming an anchor layer on the surface of the polarizing film or performing various easy adhesion treatments such as corona treatment and plasma treatment. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

As the method for forming the pressure-sensitive adhesive layer, various methods are used. 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. Examples thereof include an extrusion coating method.

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

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 the constituent material of the separator include, for example, 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 a thin leaf body etc. can be 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. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator.

In addition, the sheet | seat which carried out the peeling process used in preparation of said polarizing film with an adhesive layer can be used as a separator of the polarizing film with an adhesive layer as it is, and can simplify in the surface of a process.

The polarizing film generally has a transparent protective film on one or both sides of the polarizer.

The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. 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 film with iodine and uniaxially stretching it can be prepared, for example, by dyeing a polyvinyl alcohol film in an aqueous solution of iodine and stretching it 3 to 7 times the original length. it can. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.

As the polarizer, a thin polarizer having a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

As the thin polarizer, typically, JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917, PCT / JP2010 / 001460, or Japanese Patent Application No. 2010- And a thin polarizing film described in Japanese Patent Application No. 269002 and Japanese Patent Application No. 2010-263692. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

As the thin polarizing film, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, WO2010 / 100917 pamphlet, PCT / PCT / PCT / JP 2010/001460 specification, or Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692, the one obtained by a production method including a step of stretching in a boric acid aqueous solution is preferable. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric acid aqueous solution as described in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 is preferable.

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

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. The thickness is preferably 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 can be provided on the surface of the transparent protective film to which the polarizer is not adhered.

The adhesive used for laminating the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent, and water-based, solvent-based, hot-melt-based, radical curable, and cationic curable types are used. However, water-based adhesives or radical curable adhesives are suitable.

<LCD panel>
The polarizing film with the pressure-sensitive adhesive layer of the present invention is bonded to at least one surface of the liquid crystal cell via the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer to form a liquid crystal panel. The polarizing film with an adhesive layer of this invention is used suitably for the visual recognition side of a liquid crystal cell.

The liquid crystal cell may be of any type such as TN type, STN type, π type, VA type, IPS type, etc., but an IPS mode liquid crystal cell is preferably used for the liquid crystal panel of the present invention.

In addition to the polarizing film, other optical layers can be applied to form the liquid crystal panel. The optical layer is not particularly limited. For example, a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, a brightness enhancement film, and the like of a liquid crystal panel. One or two or more optical layers that may be used for formation can be used on the viewing side and / or the back side of the liquid crystal cell.

<Liquid crystal display device>
The liquid crystal display device uses the above-described liquid crystal panel, and is formed by appropriately assembling components such as an illumination system and incorporating a drive circuit as necessary. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged. In addition, an appropriate liquid crystal display device such as a lighting system using a backlight or a reflecting plate can be formed.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically defined 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). It measured similarly about Mw / Mn.
・ Analyzer: manufactured by Tosoh Corporation, HLC-8120GPC
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
・ Column size: 7.8mmφ × 30cm each 90cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8mL / min
・ Injection volume: 100 μL
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
Standard sample: polystyrene

<Creation of polarizing film>
A polyvinyl alcohol film having a thickness of 80 μm was stretched up to 3 times while being dyed for 1 minute in an iodine solution of 0.3% concentration at 30 ° C. between rolls having different speed ratios. Thereafter, the total draw ratio was stretched to 6 times while being immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer having a thickness of 30 μm. A saponified 80 μm thick triacetyl cellulose film 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 introduction pipe, a thermometer, and a stirring device. Further, 0.1 part of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged with 100 parts of ethyl acetate to 100 parts of the monomer mixture, and nitrogen gas was introduced while gently stirring to introduce nitrogen. After the substitution, a polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at around 55 ° C., and an acrylic polymer solution having a weight average molecular weight (Mw) of 1.8 million and Mw / Mn = 4.1 (solid content concentration) 30% by weight) was prepared.

Example 1
(Preparation of adhesive composition)
For 100 parts solid content of the acrylic polymer solution produced above,
0.23 parts 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 parts of a tetraazaporphyrin-based dye (trade name PD-320, manufactured by Yamamoto Kasei Co., Ltd., having a maximum absorption wavelength at a wavelength of 595 nm), and a phenol-based antioxidant (trade name, IRGANOX 1010, manufactured by BASF Japan) 25 parts was blended to obtain an adhesive composition.

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

Examples 2 to 12, Comparative Examples 1 to 3
In Example 1, a pressure-sensitive adhesive film was prepared in the same manner as in Example 1 except that the amounts used of the dye, radical generator, and antioxidant were changed as shown in Table 1 in preparing the pressure-sensitive adhesive composition. did.

The following evaluation was performed on the pressure-sensitive adhesive film (pressure-sensitive adhesive layer) obtained in the above Examples and Comparative Examples. The evaluation results are shown in Table 1.

<Measurement of gel fraction>
On the polyethylene terephthalate film treated with the silicone release agent, each pressure-sensitive adhesive composition before preparation of the pressure-sensitive adhesive film in Examples and Comparative Examples was applied so that the thickness after drying was 20 μm. A pressure-sensitive adhesive layer was formed by curing under the same drying conditions (temperature, time) as in the example, and the gel fraction was measured for the pressure-sensitive adhesive layer after standing for 1 hour under conditions of a temperature of 23 ° C. and a humidity of 65% RH. .
The gel fraction was 0.2 g of the pressure-sensitive adhesive layer, wrapped in a fluororesin (TEMISH NTF-1122, manufactured by Nitto Denko Corporation) (Wa), which was previously weighed, and tied so that the optical pressure-sensitive adhesive did not leak. After that, the weight (Wb) was measured and put into a sample bottle. 40 cc of ethyl acetate was added and left for 1 hour or 7 days. Thereafter, the fluororesin was taken out, dried on an aluminum cup at 130 ° C. for 2 hours, the weight (Wc) of the fluororesin including 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 off the PET substrate on one side from the pressure-sensitive adhesive films obtained in Examples and Comparative Examples, the pressure-sensitive adhesive layer side was bonded to non-alkali glass. Thereafter, the other PET was peeled off, and a 60 μm thick acrylic film was bonded to the exposed pressure-sensitive adhesive layer as a sample. The sample was put in an oven at 85 ° C. for 1000 hours and taken out after a durability test. The transmittance (T1) before the durability test and the subsequent transmittance (T2) of the sample were measured. The transmittance was measured with the sample at 23 ° C. The transmittance was measured for the sample. The acrylic film does not affect the transmittance.
The results are shown in Table 1. Table 1 shows the difference (T1−T2) and the ratio (T2 / T1) between the transmittance (T1) and the transmittance (T2). The transmittance was measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c of Murakami Color Research Laboratory).

 
 

 
 

Claims (17)

A pressure-sensitive adhesive composition for a polarizing film comprising a (meth) acrylic polymer, a pigment, a radical generator and an antioxidant. The pressure-sensitive adhesive composition for a polarizing film according to claim 1, wherein the dye has a maximum absorption wavelength in at least one of a wavelength region of 470 to 510 nm and a wavelength region of 570 to 610 nm. 3. The pressure-sensitive adhesive composition for polarizing film according to claim 1, wherein the dye is a tetraazaporphyrin-based dye. The polarizing film with a pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein 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. The polarizing film pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the radical generator is a peroxide. 6. The pressure-sensitive adhesive composition for a polarizing film according to claim 1, wherein the radical generator is contained in an amount of 0.01 to 2 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. object. 7. The pressure-sensitive adhesive composition for a polarizing film according to claim 1, wherein the antioxidant is a phenolic antioxidant. 8. The pressure-sensitive adhesive composition for a polarizing film according to claim 1, wherein the antioxidant is contained in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. object. 9. The weight ratio (A / B) between the usage amount (A) of the radical generator and the usage amount (B) of the antioxidant is 4 or less. Pressure-sensitive adhesive composition for polarizing film. The pressure-sensitive adhesive composition for a polarizing film according to any one of claims 1 to 9, further comprising a crosslinking agent. A pressure-sensitive adhesive layer for a polarizing film, which is formed of the pressure-sensitive adhesive composition for a polarizing film according to any one of claims 1 to 10. The pressure-sensitive adhesive layer for polarizing film according to claim 11, wherein the gel fraction is 50 to 98% by weight. 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 that is 50% or less. The pressure-sensitive adhesive layer for polarizing film according to claim 11 or 12. When the pressure-sensitive adhesive layer has a thickness of 20 μm, the ratio (T2 / T1) of the transmittance (T1) before storage at 85 ° C. for 500 hours and the transmittance (T2) after that is 2 or less. The pressure-sensitive adhesive layer for a polarizing film according to any one of claims 11 to 13. A polarizing film with a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer for a polarizing film according to any one of claims 12 to 14 is formed on at least one side of the polarizing film. The polarizing film with the pressure-sensitive adhesive layer according to claim 15 is bonded to at least one surface of the liquid crystal cell and the liquid crystal cell via the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer. A characteristic LCD panel. A liquid crystal display device comprising the liquid crystal panel according to claim 16.