Pressure sensitive adhesive sheet, optical film having pressure sensitive adhesive sheet, and manufacturing methods of pressure sensitive adhesive sheet and optical film having pressure sensitive adhesive sheet

Abstract

To provide a pressure sensitive adhesive sheet enabling a manufacture with a low environmental load through reducing a waste amount of a release liner required in manufacturing a pressure sensitive adhesive sheet.SOLUTION: A pressure sensitive adhesive sheet 1 includes a monomer group containing a (meth)acrylic monomer and / or a partial polymerization product of the monomer group, and a photo-curable adhesive composition containing a photoinitiator. The pressure sensitive adhesive sheet 1 is 5 to 100 μm thick. The adhesive composition further includes an antioxidant. The antioxidant includes at least one selected from a group consisting of a hindered phenolic compound, a hindered amine-based compound and a phosphorus-based compound and has a molecular mass of 1000 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive sheet, an optical film with an adhesive sheet, and a method for manufacturing an adhesive sheet and an optical film with an adhesive sheet.

Background Art

[0002] Various image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices generally include an optical laminate including an optical film such as a polarizing film and an adhesive sheet. An adhesive sheet is usually used for bonding between optical films included in the optical laminate and for bonding between the optical laminate and the image display panel. As the adhesive sheet, a sheet obtained by curing a monomer group including an acrylic monomer, a silicone monomer, or the like by polymerization and crosslinking is typical.

[0003] Patent Document 1 discloses an example of an adhesive sheet. In Patent Document 1, the adhesive sheet is produced by irradiating a coating layer of an adhesive composition disposed between two release liners with light.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For the formation of an adhesive sheet by curing, energy such as heat or light is usually required. According to a method using light (photo-curing method), for example, the amount of energy required for forming the adhesive sheet can be reduced compared to a method of thermally curing a coating layer containing an adhesive composition and a solvent (thermal curing method). However, from the viewpoint of reducing the environmental load during the production of the adhesive sheet, it is not sufficient to focus only on the amount of energy required for curing the coating layer.

[0006] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet capable of being manufactured with a low environmental load by reducing the amount of release liner waste required for manufacturing the pressure-sensitive adhesive sheet.

Means for Solving the Problems

[0007] The present invention is a pressure-sensitive adhesive sheet formed from a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photocurable pressure-sensitive adhesive composition containing a photopolymerization initiator, wherein the thickness of the pressure-sensitive adhesive sheet is 5 to 100 μm, the pressure-sensitive adhesive composition further contains an antioxidant, and the antioxidant contains at least one selected from the group consisting of a hindered phenol-based compound, a hindered amine-based compound, and a phosphorus-based compound, and has a molecular weight of 1000 or less, to provide a pressure-sensitive adhesive sheet.

[0008] Furthermore, the present invention is the above pressure-sensitive adhesive sheet, an optical film, to provide an optical film with a pressure-sensitive adhesive sheet including the above.

[0009] Furthermore, the present invention is a method for manufacturing the above pressure-sensitive adhesive sheet, wherein the manufacturing method includes a step A of irradiating light on a laminate including a base sheet, a coating layer containing the pressure-sensitive adhesive composition, and a release liner in this order to form the pressure-sensitive adhesive sheet with a thickness of 5 to 100 μm from the coating layer, a step B of peeling the release liner from the pressure-sensitive adhesive sheet, and includes using the release liner peeled in the step B to repeatedly perform the step A and the step B to reuse the release liner, to provide a method for manufacturing a pressure-sensitive adhesive sheet.

[0010] Furthermore, the present invention is Provided is a method for manufacturing an optical film with an adhesive sheet, which includes laminating an adhesive sheet formed by the above manufacturing method and an optical film to form an optical film with an adhesive sheet.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide an adhesive sheet capable of being manufactured with a low environmental load by reducing the amount of release liner waste required for the production of the adhesive sheet.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0013] The adhesive sheet according to the first aspect of the present invention is An adhesive sheet formed from a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photocurable adhesive composition containing a photopolymerization initiator, wherein the thickness of the adhesive sheet is 5 to 100 μm, the adhesive composition further contains an antioxidant, the antioxidant contains at least one selected from the group consisting of a hindered phenol compound, a hindered amine compound, and a phosphorus compound, and has a molecular weight of 1000 or less.

[0014] In a second aspect of the present invention, for example, in the adhesive sheet according to the first aspect, the antioxidant contains a hindered phenol compound.

[0015] In a third aspect of the present invention, for example, in the adhesive sheet according to the first or second aspect, the molecular weight of the antioxidant is 500 or less.

[0016] In a fourth aspect of the present invention, for example, in the adhesive sheet according to any one of the first to third aspects, the blending amount of the hydroxy group-containing monomer is less than 5 parts by weight out of 100 parts by weight of the monomer group.

[0017] In a fifth aspect of the present invention, for example, in the adhesive sheet according to any one of the first to fourth aspects, the monomer group contains a carboxyl group-containing monomer.

[0018] In a sixth aspect of the present invention, for example, in the adhesive sheet according to any one of the first to fifth aspects, the content rate of the solvent in the adhesive composition is 5% by weight or less.

[0019] An optical film with an adhesive sheet according to a seventh aspect of the present invention comprises an adhesive sheet according to any one of the first to sixth aspects, and an optical film.

[0020] ​In the eighth aspect of the present invention, for example, in the optical film with an adhesive sheet according to the seventh aspect, the optical film is a film including at least one selected from the group consisting of a polarizing film and a retardation film.

[0021] The method for manufacturing an adhesive sheet according to the ninth aspect of the present invention is a method for manufacturing an adhesive sheet according to any one of the first to sixth aspects, wherein the manufacturing method includes a step A of irradiating light on a laminate including a base sheet, a coating layer containing the adhesive composition, and a release liner in this order to form the adhesive sheet having a thickness of 5 to 100 μm from the coating layer; a step B of peeling the release liner from the adhesive sheet; and reusing the release liner by repeating step A and step B using the release liner peeled in step B.

[0022] The method for manufacturing an optical film with an adhesive sheet according to the tenth aspect of the present invention is including laminating an adhesive sheet and an optical film formed by the manufacturing method according to the ninth aspect to form an optical film with an adhesive sheet.

[0023] The present invention will be described in detail below. However, the present invention is not limited to the following embodiments and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0024] The inventors of the present invention conceived of further reducing the environmental load in the manufacturing process of the adhesive sheet by reusing the release liner that had been immediately discarded after peeling, and proceeded with studies based on this concept to complete the present invention.

[0025] [Embodiments of the Adhesive Sheet] An example of the pressure-sensitive adhesive sheet of the present embodiment is shown in FIG. 1. The pressure-sensitive adhesive sheet 1 in FIG. 1 is formed from a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition includes a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator. The pressure-sensitive adhesive composition is a photocurable pressure-sensitive adhesive composition that cures upon irradiation with light. In this specification, the photocurable pressure-sensitive adhesive composition may be referred to as a photocurable composition.

[0026] The pressure-sensitive adhesive composition further includes antioxidant D. Antioxidant D contained in the pressure-sensitive adhesive composition includes at least one selected from the group consisting of hindered phenolic compounds, hindered amine compounds, and phosphorus compounds, and has a molecular weight of 1000 or less. According to the pressure-sensitive adhesive composition containing antioxidant D, when manufacturing the pressure-sensitive adhesive sheet 1, an increase in the peel force of the release liner with respect to the pressure-sensitive adhesive sheet 1 tends to be suppressed. Therefore, the release liner can be repeatedly used. Thereby, the amount of waste of the release liner can be reduced, and the pressure-sensitive adhesive sheet 1 can be repeatedly manufactured with a low environmental load. The thickness of the pressure-sensitive adhesive sheet 1 is 5 to 100 μm, preferably 5 to 50 μm, more preferably 5 to 25 μm, and still more preferably 5 to 20 μm. Since the thickness of the pressure-sensitive adhesive sheet 1 is 100 μm or less, the absolute amount of residual monomer tends to be small compared to a pressure-sensitive adhesive sheet having a thickness exceeding 100 μm. Therefore, when manufacturing the pressure-sensitive adhesive sheet 1, the surface of the release liner is less likely to be contaminated with the residual monomer, and an increase in the peel force of the release liner with respect to the pressure-sensitive adhesive sheet 1 tends to be more suppressed. Since the thickness of the pressure-sensitive adhesive sheet 1 is 100 μm or less, even when the optical film contracts in a state of being laminated with an optical film such as a polarizing film, displacement at the end is less likely to occur. Therefore, in the optical film with a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive sheet 1, appearance defects such as light leakage due to the contraction of the optical film are less likely to occur even in a high-temperature environment of about 85° C. or higher.

[0027] The pressure-sensitive adhesive sheet 1 may have a base sheet or a release liner used in its production laminated thereon.

[0028] The pressure-sensitive adhesive sheet 1 may have a base sheet or a release liner used in its production laminated thereon.

[0029] (Adhesive composition) As described above, the adhesive composition of the present embodiment contains a monomer group containing a (meth)acrylic monomer and / or a partial polymer of the monomer group. The content of the (meth)acrylic component in the adhesive composition, that is, the (meth)acrylic monomer and its partial polymer, may be 50% by weight or more, 60% by weight or more, 70% by weight or more, and even 80% by weight or more. In this case, an acrylic adhesive sheet mainly composed of a (meth)acrylic polymer and its crosslinked product can be formed. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0030] Examples of the (meth)acrylic monomer are alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms in the side chain. The number of carbon atoms of the alkyl group may be 7 or less, 6 or less, 5 or less, or even 4 or less. The alkyl group may be linear or branched. Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and octadecyl (meth)acrylate. The alkyl (meth)acrylate may be n-butyl (meth)acrylate.

[0031] The content of the alkyl (meth)acrylate in the monomer group is, for example, 40% by weight or more, and may be 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or even 95% by weight or more. In calculating the content, the weight of the partial polymer is converted to the weight as each monomer before polymerization. In calculating the content, the weight of the partial polymer is converted to the weight as each monomer before polymerization.

[0032] The monomer group may contain a carboxyl group-containing monomer. The carboxyl group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a carboxyl group-containing monomer. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The content rate of the carboxyl group-containing monomer in the monomer group is, for example, 10% by weight or less, and may be 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, 5.5% by weight or less, and even 5% by weight or less. The lower limit of the content rate may be, for example, 0.1% by weight or more, 0.5% by weight or more, and even 1% by weight or more. The monomer group may not contain a carboxyl group-containing monomer.

[0033] The monomer group may contain a hydroxy group-containing monomer. The hydroxy group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a hydroxy group-containing monomer. The hydroxy group-containing monomer can contribute to improving the cohesive force of the pressure-sensitive adhesive sheet. Examples of the hydroxy group-containing monomer are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. The hydroxy group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. The content rate of the hydroxy group-containing monomer in the monomer group is, for example, 10% by weight or less, and may be 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, 0.8% by weight or less, 0.5% by weight or less, 0.3% by weight or less, 0.2% by weight or less, and even 0.1% by weight or less. The lower limit of the content rate may be, for example, 0.01% by weight or more, 0.03% by weight or more, and even 0.05% by weight or more. The monomer group may not contain a hydroxy group-containing monomer.

[0034] Out of 100 parts by weight of the monomer group, the blending amount of the hydroxy group-containing monomer is preferably less than 5 parts by weight. The blending amount of the hydroxy group-containing monomer is more preferably 4 parts by weight or less, and may be 3 parts by weight or less, 2 parts by weight or less, and even 1 part by weight or less. The lower limit of the blending amount may be, for example, 0.01 part by weight or more, 0.03 part by weight or more, and even 0.05 part by weight or more.

[0035] In the pressure-sensitive adhesive composition, each of the above-described monomers may be contained as a partial polymer. The partial polymer may be either a homopolymer or a copolymer. The partial polymer can contribute to the stable formation of the coating layer by moderately increasing the viscosity of the pressure-sensitive adhesive composition.

[0036] As described above, the pressure-sensitive adhesive composition further contains a photoinitiator. Examples of the photoinitiator are photo radical generators that generate radicals by visible light and / or ultraviolet light having a wavelength shorter than 450 nm.

[0037] Examples of the photoinitiator include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyldimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenyl ketone; substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone; aromatic such as 2-naphthalenesulfonyl chloride Sulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; benzophenone-based compounds such as benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone; thioxanthone-based compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-diethylthioxanthone; triazine-based compounds such as 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine; oxime ester-based compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)] and O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; phosphine-based compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone-based compounds such as 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone; borate-based compounds; carbazole-based compounds; imidazole-based compounds; and metallocene-based compounds. The adhesive composition may contain one or more photoinitiators.

[0038] The compounding amount of the photoinitiator in the pressure-sensitive adhesive composition is, for example, 0.02 to 10 parts by weight, and may be 0.05 to 5 parts by weight with respect to a total of 100 parts by weight of the monomer group and its partial polymer.

[0039] As described above, the pressure-sensitive adhesive composition further contains antioxidant D. Antioxidant D contains at least one selected from the group consisting of hindered phenol compounds, hindered amine compounds, and phosphorus compounds. Antioxidant D preferably contains at least one selected from the group consisting of hindered phenol compounds and hindered amine compounds, and particularly preferably contains a hindered phenol compound. The compound contained in antioxidant D preferably does not contain a sulfur atom. The pressure-sensitive adhesive composition may contain one or more antioxidants D.

[0040] The molecular weight of antioxidant D is 1000 or less. The molecular weight of antioxidant D is preferably 800 or less, and may be 500 or less, and further 400 or less. The smaller the molecular weight of antioxidant D, the more the increase in the peel force of the release liner with respect to the pressure-sensitive adhesive sheet 1 is suppressed during the production of the pressure-sensitive adhesive sheet 1. In addition, antioxidant D is preferably liquid at room temperature (25°C) due to its small molecular weight. The lower limit of the molecular weight of antioxidant D is not particularly limited, and may be, for example, 100 or more, 200 or more, and further 300 or more.

[0041] Examples of the hindered phenol compound include dibutylhydroxytoluene (BHT), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate ("Irganox 1076" manufactured by BASF), isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (" "Irganox 1135"), 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol (BASF's "Irganox 1330"), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (BASF's "Irganox 3114"), 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxyoxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADEKA's "Adekastab AO-80"), 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate (Sumitomo Chemical's "Sumilizer GS"), 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl acrylate (Sumitomo Chemical's "Sumilizer GM"), 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1'-diyl = bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate] (Sumitomo Chemical's "Sumilizer GA-80"), 1,3,5-tris(3-hydroxy-4-tert-butyl-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (Cytec's "Cyanox 1790") and the like. The hindered phenol-based compound is preferably Irganox 1135.

[0042] Examples of the hindered amine compounds include bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate (“Tinuvin 123” manufactured by BASF), tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (“Adekastab LA-52” manufactured by ADEKA), tetrakis(2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (“Adekastab LA-57” manufactured by ADEKA), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (“Adekastab LA-72” manufactured by ADEKA), bis-(2,2,6,6-tetramethyl-4-piperidyl) sebacate (“Adekastab LA-77Y” manufactured by ADEKA), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (“Adekastab LA-77G” manufactured by ADEKA), bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate (“Adekastab LA-81” manufactured by ADEKA), 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (“Adekastab LA-82” manufactured by ADEKA), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (“Adekastab LA-87” manufactured by ADEKA), SONG LIGHT 1230 (manufactured by SONGWON), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (“SONG LIGHT 2920” manufactured by SONGWON), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (“SONG LIGHT 7700” manufactured by SONGWON), N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (“Uvinul 4050H” manufactured by BASF), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (“Uvinul 4077H” manufactured by BASF), and the like. The hindered amine compound is preferably Adekastab LA-52.

[0043] Examples of phosphorus compounds include trioctyl phosphite, trilauryl phosphite, tris tridecyl phosphite, tris isodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl)phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, triphenyl phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(butoxyphenyl)phosphite, diethyl) phosphite, tris(biphenyl) phosphite, tris(3,5-di-t-butyl-4-hydroxyphenyl) phosphite, 9,10-dihydro-9-phosphaphenanthrene-10-oxide, 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-methylphenyl) pentaerythritol diphosphite, phenyl bisphenol-A-pentaerythritol diphosphite, and the like.

[0044] The amount of the antioxidant is, for example, 0.01 parts by weight or more, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, or even 0.3 parts by weight or more, based on 100 parts by weight in total of the monomer group and its partial polymer. The upper limit of the amount of the antioxidant is, for example, 5 parts by weight or less, and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even 0.5 parts by weight or less.

[0045] The adhesive composition may contain a crosslinking agent. Examples of the crosslinking agent are polyfunctional monomers having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be a (meth)acrylic monomer. Examples of the polyfunctional monomer are monomers having two or more C=C bonds in one molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, and methylol groups in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0046] Examples of the crosslinking agent are polyfunctional acrylates (ester compounds of polyhydric alcohols and (meth)acrylic acid, etc.) such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDDA), 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate.

[0047] The blending amount of the crosslinking agent varies depending on the molecular weight, the number of functional groups, etc., but is, for example, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less, with respect to a total of 100 parts by weight of the monomer group and its partial polymer. The lower limit of the blending amount may be, for example, 0.01 parts by weight or more, and even 0.05 parts by weight or more.

[0048] The pressure-sensitive adhesive composition may contain additives other than those described above. Examples of the additives are a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softening agent, an antioxidant, a filler, a colorant, a surfactant, an antistatic agent, and an ultraviolet absorber.

[0049] The content rate of the solvent in the pressure-sensitive adhesive composition is, for example, 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, and even 0.5% by weight or less. The pressure-sensitive adhesive composition may not substantially contain a solvent. Not substantially containing a solvent means that solvents and the like derived from additives and the like are allowed at a content rate of, for example, 0.1% by weight or less, preferably 0.05% by weight or less, more preferably 0.01% by weight or less.

[0050] The viscosity of the pressure-sensitive adhesive composition is preferably 5 to 100 poises. The pressure-sensitive adhesive composition having a viscosity within the above range is particularly suitable for forming a coating layer.

[0051] (Physical properties and characteristics of the pressure-sensitive adhesive sheet) The polymerization rate of the monomer group in the pressure-sensitive adhesive sheet 1 is preferably 90% or more. The polymerization rate may be 95% or more, 98% or more, and even 99% or more.

[0052] The gel fraction of the pressure-sensitive adhesive sheet 1 is, for example, 50% or more, 75% or more, 80% or more, and even 85% or more.

[0053] The creep amount of the pressure-sensitive adhesive sheet 1 is, for example, 180 μm or less, and may be 160 μm or less. The lower limit of the creep amount may be, for example, 5 μm or more, and may be 10 μm or more.

[0054] The creep amount of the adhesive sheet 1 can be evaluated as follows (see FIGS. 2A and 2B). First, a laminate of the adhesive sheet 1 to be evaluated and the support film 51 is cut out into a strip shape of 10 mm × 50 mm to obtain a test piece 52. The support film 51 is arranged for the purpose of suppressing the deformation of the portion of the adhesive sheet 1 where the load is applied during the test, thereby measuring the creep amount more accurately. For the support film 51, for example, a resin film such as a polyethylene terephthalate (PET) film can be used. The support film 51 may be an optical film or a laminate including an optical film. The thickness of the support film 51 may be a thickness that does not deform itself due to the above load, for example, 20 to 200 μm. Next, as shown in FIGS. 2A and 2B, the test piece 52 is attached to the surface of the stainless steel test plate 53 with the adhesive sheet 1 at a joint surface of 10 mm in length × 10 mm in width. Note that FIG. 2B is a cross-section B-B of FIG. 2A. The attachment of the test piece 52 to the test plate 53 is performed so that no bubbles are mixed between the test plate 53 and the adhesive sheet 1. After attachment, it is placed in an autoclave at 50°C and 5 atm (absolute pressure) for 15 minutes to homogenize the joint between the test plate 53 and the adhesive sheet 1. Next, the test plate 53 and the test piece 52 are vertically held with the test plate 53 on the upper side and left in an atmosphere of 25°C for at least 5 minutes. Then, with the test plate 53 fixed, a weight of 500 g is fixed to the center of the lower end of the test piece 52 to apply a load of 500 gf vertically downward. The creep amount (displacement amount) of the adhesive sheet 1 with respect to the test plate 53 at the time 3600 seconds after the start of applying the load 54 is measured as the drop amount of the weight. A laser displacement meter can be used to measure the drop amount of the weight.

[0055] (Method for manufacturing an adhesive sheet) The pressure-sensitive adhesive sheet 1 can be produced, for example, by the following method using the above-described pressure-sensitive adhesive composition. First, as shown in FIG. 3, light 14 is irradiated onto a first laminate 10 including a base material sheet 11, a coating layer 12 containing a pressure-sensitive adhesive composition, and a release liner 13 in this order to form a pressure-sensitive adhesive sheet 1 having a thickness of 5 to 100 μm from the coating layer 12 (step A). The irradiation of the light 14 is typically performed from the side of the base material sheet 11. The light 14 passes through the base material sheet 11 and reaches the coating layer 12 to cure the coating layer 12. However, the irradiation of the light 14 may be performed from the side of the release liner 13 or from both sides of the release liner 13 and the base material sheet 11. The formed pressure-sensitive adhesive sheet 1 is sandwiched between the base material sheet 11 and the release liner 13 until the release liner 13 is peeled off, and constitutes a part of a second laminate 17. After step A, the release liner 13 is peeled off from the pressure-sensitive adhesive sheet 1 (step B).

[0056] In the method of FIG. 3, steps A and B are repeatedly performed using the release liner 13 peeled off in step B. Thereby, the release liner 13 is reused. Step A using the peeled release liner 13 forms a first laminate 10 including a base material sheet 11, a coating layer 12, and the peeled release liner 13 in this order, and is performed by irradiating the formed first laminate 10 with light 14.

[0057] As described above, in this embodiment, since the pressure-sensitive adhesive composition contains antioxidant D, when the pressure-sensitive adhesive sheet 1 is manufactured, the increase in the peel strength of the release liner 13 with respect to the pressure-sensitive adhesive sheet 1 tends to be suppressed. Specifically, in the above step A, a chemical bond is formed between the release liner 13 and the pressure-sensitive adhesive sheet 1 by irradiation with light 14, and a functional group formed by a part thereof or decomposition of the bond may remain on the surface of the release liner 13 even after the pressure-sensitive adhesive sheet 1 is peeled off. As a result, after the implementation of step A, the peel strength of the release liner 13 with respect to the pressure-sensitive adhesive sheet 1 tends to increase compared to before the implementation. According to antioxidant D, the formation of a chemical bond between the release liner 13 and the pressure-sensitive adhesive sheet 1 can be suppressed. Further, according to antioxidant D, the surface of the release liner 13 can also be suppressed from being contaminated with the material of the pressure-sensitive adhesive sheet 1 regardless of the manufacturing conditions (such as the irradiation time of light) of the pressure-sensitive adhesive sheet 1.

[0058] In this embodiment, when the pressure-sensitive adhesive sheet 1 is manufactured, even when steps A and B are repeatedly performed using the release liner 13 peeled off in step B, the increase in the peel strength of the release liner 13 with respect to the pressure-sensitive adhesive sheet 1 tends to be suppressed. Since the release liner 13 can be repeatedly used, the amount of waste of the release liner 13 can be reduced, and the pressure-sensitive adhesive sheet 1 can be manufactured with a low environmental load.

[0059] <Step A> (Release liner) Examples of the base material of the release liner 13 (hereinafter, "liner base material") are resin films. Examples of resins that can be contained in the liner base material are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resin, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0060] The release liner 13 may have permeability to the light 14 irradiated in Step A, and may have the same level of permeability to the light 14 as the base material sheet 11.

[0061] The thickness of the release liner 13 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0062] The release liner 13 may include a layer other than the liner base material. The release liner 13 may include a release layer. The release liner 13 in FIG. 4 includes a liner base material 131 and a release layer 132 formed on one surface of the liner base material 131. The release liner 13 in FIG. 4 can be used such that the release layer 132 faces the coating layer 12.

[0063] The release layer 132 is typically a cured layer of a release agent composition containing a release agent. Various release agents such as silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder can be used as the release agent. The release liner 13 may include a cured layer of a release agent composition containing a silicone-based release agent as a main component (hereinafter referred to as a "silicone release layer"). The silicone release layer is particularly suitable for achieving both adhesion and peelability to the adhesive sheet 1. In this specification, the main component means the component with the largest content rate.

[0064] The silicone-based release agent is, for example, various curable silicone materials such as addition reaction type, condensation reaction type, ultraviolet curable type, electron beam curable type, and solvent-free type, and the addition reaction curable silicone material is preferred. The addition reaction curable silicone material is particularly suitable for forming a release layer that achieves both adhesion and peelability to the adhesive sheet 1. The curable silicone material may be a silicone-modified resin in which reactive silicone is introduced into an organic resin such as urethane, epoxy, or alkyd resin by graft polymerization or the like.

[0065] Examples of addition reaction-curable silicone materials are polyorganosiloxanes having a vinyl group or alkenyl group in the molecule. The addition reaction-curable silicone materials may not have a hydrosilyl group. Examples of alkenyl groups are 3-butenyl group, 4-pentenyl group, 5-hexenyl group, 6-heptenyl group, 7-octenyl group, 8-nonenyl group, 9-decenyl group, 10-undecenyl group, and 11-dodecenyl group. Examples of polyorganosiloxanes are polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxanes, and copolymers of plural kinds of Si atom-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). The polyorganosiloxane is preferably polydimethylsiloxane.

[0066] A release agent composition containing a silicone-based release agent as a main component (hereinafter referred to as "silicone release agent composition") usually contains a crosslinking agent. Examples of crosslinking agents are polyorganosiloxanes having a hydrosilyl group. The crosslinking agent may have two or more hydrosilyl groups in one molecule.

[0067] The silicone release agent composition may contain a curing catalyst. Examples of curing catalysts are platinum-based catalysts. Examples of platinum-based catalysts are chloroplatinic acid, olefin complexes of platinum, and olefin complexes of chloroplatinic acid. The amount of platinum-based catalyst used is, for example, 10 to 1000 ppm (weight basis, platinum conversion) based on the total solid content of the composition.

[0068] The silicone release agent composition may contain additives. Examples of additives are release control agents and adhesion improvers. Examples of release control agents are unreacted silicone resins, and more specific examples are organosiloxanes such as octamethylcyclotetrasiloxane, and MQ resin. The total amount of release control agent and adhesion improver used is, for example, 1 to 30% by weight based on the total solid content of the composition. Further examples of additives are fillers, antistatic agents, antioxidants, ultraviolet absorbers, plasticizers, and colorants. The total amount of further additives used is, for example, 10% by weight or less based on the total solid content of the composition.

[0069] The silicone release agent composition may contain an organic solvent. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, n - hexane, and n - heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. Two or more organic solvents may be contained. The amount of the organic solvent used is preferably 80 to 99.9% by weight of the silicone release agent composition.

[0070] The release layer 132 can be formed, for example, by heating and drying a coating film containing a release agent composition formed on a liner substrate 131. For the application of the release agent composition, various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating can be applied. For heating and drying, for example, hot air drying can be applied. The heating temperature and time vary depending on the heat resistance of the liner substrate, but are usually about 80 to 150°C and 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet rays may be used in combination.

[0071] The thickness of the release layer 132 is, for example, 10 to 300 nm. The upper limit of the thickness may be 200 nm or less, 150 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, less than 100 nm, 90 nm or less, 80 nm or less, 70 nm or less, less than 70 nm, and even 65 nm or less. The lower limit of the thickness may be 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, and even 50 nm or more. The thickness of the release layer 132 may be 110 nm or less. In other words, the release liner 13 is provided with the release layer 132 on the side of the coating layer 12, and the thickness of the release layer 132 may be 110 nm or less. The release liner 13 may be in a single - sheet form or a long - strip form.

[0072] The release liner 13 may be in a single - sheet form or a long - strip form.

[0073] (Base material sheet) An example of the base material sheet 11 is a resin film. Examples of the resin contained in the base material sheet 11 are the same as the examples of the resin that can be contained in the liner base material.

[0074] The base material sheet 11 preferably has excellent permeability to the light 14 irradiated in step A.

[0075] The thickness of the base material sheet 11 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0076] The base material sheet 11 may be provided with a release layer on the surface on the side of the coating layer 12. Examples of the release layer that the base material sheet 11 can have and its manufacturing method are the same as the examples of the release layer that the release liner 13 can have and its manufacturing method. Both the release liner 13 and the base material sheet 11 may be provided with a release layer. In this case, both release layers may be formed from a release agent composition containing the same release agent as the main component. Also, the thicknesses of both release layers may be different. For example, the release layer provided on the base material sheet 11 may be thicker.

[0077] For the base material sheet 11, usually, a sheet having a peeling force from the adhesive sheet 1 larger than that of the release liner 13 can be selected.

[0078] The base material sheet 11 may be in a single-sheet form or a long-strip form.

[0079] (The first laminate and its formation) The first laminate 10 may include additional layers other than the base material sheet 11, the coating layer 12, and the release liner 13. The above additional layers may be disposed on the side opposite to the side of the coating layer 12 in the base material sheet 11 and / or the release liner 13. The coating layer 12 is preferably in contact with the base material sheet 11 and the release liner 13.

[0080] The first laminate 10 can be formed, for example, by forming a coating layer 12 on a base sheet 11 (or a release liner 13), and disposing a release liner 13 (or a base sheet 11) on the formed coating layer 12. Alternatively, the first laminate 10 may be formed by pouring an adhesive composition into the space between a base sheet 11 and a release liner 13 held at a predetermined interval such that their main surfaces face each other. The peeled release liner 13 may be used such that the surface that was on the side of the coating layer 12 in step A immediately before peeling, for example, the surface on the side of the release layer 132, becomes the side of the coating layer 12 again.

[0081] For the formation of the coating layer 12, various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coating, etc. can be applied.

[0082] The thickness of the coating layer 12 can be adjusted according to the thickness of the target adhesive sheet 1, and is, for example, 5 to 1 00 μm, and may be 5 to 50 μm, 5 to 25 μm, or even 5 to 20 μm.

[0083] The first laminate 10 may include a long base sheet 11, a long coating layer 12, and a long release liner 13. In other words, it may be long. The long first laminate 10 can be obtained, for example, by forming the coating layer 12 between a base sheet 11 and a release liner 13 while transporting them from a wound body.

[0084] (Irradiation with light) The light 14 irradiated on the first laminate 10 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light 14 may contain light having a wavelength in the same region as the absorption wavelength of the photoinitiator contained in the pressure-sensitive adhesive composition. The light 14 from which short-wavelength light having a wavelength of 300 nm or less is cut by a filter or the like may be irradiated, and cutting the short-wavelength light is suitable for suppressing the deterioration of the base sheet 11 by the light 14. The light source of the light 14 is, for example, a light irradiation device provided with an ultraviolet irradiation lamp. Examples of the ultraviolet irradiation lamp are ultraviolet LED, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, xenon lamp, microwave-excited mercury lamp, black light lamp, chemical lamp, germicidal lamp, low-pressure discharge mercury lamp, excimer laser. Two or more ultraviolet irradiation lamps may be combined.

[0085] The irradiation of the light 14 may be continuous or intermittent.

[0086] The illuminance of the light 14 is, for example, 1 to 20 mW / cm 2 is. The irradiation time of the light 14 is, for example, 5 minutes to 5 hours. The integrated light amount of the light 14 with respect to the first laminate 10 is, for example, 100 to 5000 mJ / cm 2 is.

[0087] <Step B> In step B, the release liner 13 is peeled off from the cured second laminate 17. The second laminate 17 includes the base sheet 11, the pressure-sensitive adhesive sheet 1, and the release liner 13 in this order. By the above peeling, the release liner 13 and the third laminate 15 including the base sheet 11 and the pressure-sensitive adhesive sheet 1 are obtained.

[0088] The peeling force between the release liner 13 and the pressure-sensitive adhesive sheet 1 is, for example, smaller than the peeling force between the base sheet 11 and the pressure-sensitive adhesive sheet 1. The peeling force of the base sheet 11 with respect to the pressure-sensitive adhesive sheet 1 is, for example, 0.1 to 10 N / 50 mm, and may be 1 to 8 N / 50 mm, 2 to 7 N / 50 mm, or further 3 to 5 N / 50 mm.

[0089] The number of times of peeling off the release liner 13 and reusing it for the production of the adhesive sheet 1 is not particularly limited, and may be, for example, 3 times or more, 5 times or more, or even 7 times or more.

[0090] The peeled release liner 13 may be reused after being wound up to form a wound body.

[0091] <Peeling force between the adhesive sheet and the release liner> In this embodiment, the peeling force PS between the release liner 13 and the adhesive sheet 1 after peeling the adhesive sheet 1 n times from the unused state n (n is an integer of 0 or more corresponding to the number of peelings; When n = 0, it is the peeling force PS in the unused state 0 ) is preferably 1.0 N / 50 mm or less is preferable.

[0092] As an example, the peeling force PS between the release liner 13 in the unused state and the adhesive sheet 1 0 is not particularly limited, and may be, for example, 1.0 N / 50 mm or less, 0.5 N / 50 mm or less, 0.2 N / 50 mm or less, 0.15 N / 50 mm or less, 0.12 N / 50 mm or less, 0.1 N / 50 mm or less, 0.08 N / 50 mm or less, or even 0.05 N / 50 mm or less. The peeling force PS 0 may be 0.01 N / 50 mm or more, 0.02 N / 50 mm or more, or even 0.03 N / 50 mm or more.

[0093] The peeling force PS between the release liner 13 and the adhesive sheet 1 after peeling the adhesive sheet 1 once from the unused state 1 is preferably 1.0 N / 50 mm or less, and 0. 9 N / 50 mm or less, 0.8 N / 50 mm or less, 0.7 N / 50 mm or less, 0.6 N / 50 mm or less, 0.5 N / 50 mm or less, 0.4 N / 50 mm or less, 0.3 N / 50 mm or less, 0.2 N / 50 mm or less, or even 0.15 N / 50 mm or less. The peeling force PS1 The lower limit is, for example, 0.01 N / 50 mm or more, and 0.03 N / 50 mm or more , 0.05 N / 50 mm or more, 0.08 N / 50 mm or more, and even 0.1 N / 50 mm or more may be acceptable.

[0094] The above peeling force PS 0 The peeling force PS with respect to 1 The ratio PS 1 / PS 0 may be 10 or less, 8 or less, 6 or less, and even 5 or less. The ratio PS 1 / PS 0 The lower limit may be, for example, 1.1 or more, and even 2.0 or more.

[0095] The peeling force PS n is evaluated by the following method using the second laminate 17 formed by performing steps A and B n times using the above-described release liner 13, and further performing the (n + 1)-th step A. Specifically, it can be evaluated by cutting out the second laminate 17 formed by performing step A into a width of 50 mm to prepare a test piece, and performing a 180° peel test to peel off only the release liner 13 from the prepared test piece. The peel test is performed after about 0.5 to 1 hour has elapsed since the formation of the pressure-sensitive adhesive sheet 1. From the formation of the pressure-sensitive adhesive sheet 1 to the performance of the peel test, the second laminate 17 and the test piece are placed in an air atmosphere of 23°C ± 5°C. The peel rate of the peel test is 300 mm / min, and the test temperature is 23°C ± 5°C. When the width of the second laminate 17 is less than 50 mm, the measured value at the original width may be converted to a value per 50 mm width. When the formation direction of the coating layer 12 can be determined, the TD perpendicular to the MD in the plane can be defined as the width direction of the test piece in that direction. When the base sheet 11 and the release liner 13 are in a long shape, the width direction thereof can be defined as the width direction of the test piece.

[0096] Next, referring to FIG. 5, another example of the method for manufacturing the adhesive sheet 1 will be described. In this example, an application layer 12 of the adhesive composition is formed on one side of the long base material sheet 11 fed out from the winding body 31 by the applicator 32. Next, a long release liner 13 fed out from the winding body 33 is disposed on the application layer 12 to form a long first laminate 10. Next, the first laminate 10 is irradiated with light 14 from the light irradiation device 34 to form the long adhesive sheet 1. Next, the release liner 13 is peeled off from the second laminate 17 including the adhesive sheet 1 and wound around the winding body 35. The above steps are carried out while transporting the base material sheet 11 and the release liner 13. The wound release liner 13 is reused. The method of FIG. 5 is particularly suitable for mass production of the adhesive sheet 1.

[0097] Referring to FIG. 6, another example of the method for manufacturing the adhesive sheet 1 will be described. This example is the same as the example of FIG. 5 except that the release liner 13 peeled off from the second laminate 17 is reused in the production of the adhesive sheet 1 without being wound around the winding body 35. The method of FIG. 6 is particularly suitable for mass production of the adhesive sheet 1.

[0098] [Embodiment of the Optical Film with Adhesive Sheet] An example of the optical film with adhesive sheet of the present embodiment is shown in FIG. 7. The optical film with adhesive sheet 20A in FIG. 7 includes the adhesive sheet 1 and the optical film 2. The adhesive sheet 1 may be in direct contact with the optical film 2 or in indirect contact. The optical film with adhesive sheet 20A may have a structure in which the base material sheet used in the production of the adhesive sheet 1 is laminated on the adhesive sheet 1.

[0099] The optical film 2 is, for example, a film including at least one selected from the group consisting of a polarizing film and a retardation film. The optical film 2 may be a laminated film including a polarizing film and / or a retardation film. The optical film 2 may include a glass-made film. However, the optical film 2 is not limited to the above examples.

[0100] The polarizing film includes a polarizer. The polarizing film typically includes a polarizer and a protective film (transparent protective film). The protective film is disposed, for example, in contact with the main surface (the surface having the largest area) of the polarizer. The polarizer may be disposed between two protective films. The protective film may be disposed on at least one surface of the polarizer.

[0101] The polarizer is not particularly limited. For example, 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, adsorbed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched; a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride. The polarizer typically consists of a polyvinyl alcohol-based film (the polyvinyl alcohol-based film includes an ethylene-vinyl acetate copolymer-based partially saponified film) and a dichroic substance such as iodine.

[0102] The thickness of the polarizer is not particularly limited. For example, it is 80 μm or less, and may be 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness of the polarizer is not particularly limited. For example, it is 1 μm or more, and may be 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, with a thickness of 20 μm or less) has suppressed dimensional changes and can contribute to improving the durability of the optical laminate, particularly the durability at high temperatures.

[0103] As the material of the protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. 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 polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the protective film may be a thermosetting resin such as a (meth)acrylic-based, urethane-based, acrylic-urethane-based, epoxy-based, or silicone-based resin or an ultraviolet-curing type resin. When the polarizing film has two protective films, the materials of the two protective films may be the same as each other or different from each other. For example, a protective film made of a thermoplastic resin may be bonded via an adhesive to one main surface of the polarizer, and a protective film made of a thermosetting resin or an ultraviolet-curing type resin may be bonded to the other main surface of the polarizer. The protective film may contain one or more arbitrary additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc.

[0104] The thickness of the protective film can be appropriately determined, but generally it is about 10 to 200 μm from the viewpoints of workability such as strength and handleability, and thin film properties.

[0105] The polarizer and the protective film are usually adhered via an aqueous adhesive or the like. Examples of the aqueous adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, etc. Examples of other adhesives other than the above adhesives include ultraviolet-curing type adhesives, electron beam-curing type adhesives, etc. The electron beam-curing type adhesive for a polarizing plate exhibits suitable adhesiveness to various protective films. The adhesive may contain a metal compound filler.

[0106] In the polarizing film, instead of the protective film, a retardation film or the like can also be formed on the polarizer. Another protective film or a retardation film or the like can also be provided on the protective film.

[0107] Regarding the protective film, a hard coat layer may be provided on the surface facing the surface adhered to the polarizer, and treatments for the purpose of antireflection, sticking prevention, diffusion, antiglare, etc. can also be performed.

[0108] The polarizing film may be a circularly polarizing film.

[0109] As the retardation film, those obtained by stretching a polymer film or those in which a liquid crystal material is aligned and fixed can be used. The retardation film has, for example, birefringence in the in-plane and / or thickness directions.

[0110] The retardation film includes a retardation film for antireflection (see JP-A-2012-133303

[0221] ,

[0222] ,

[0228] ), a retardation film for viewing angle compensation (see JP-A-2012-133303

[0225] ,

[0226] ), an inclined alignment retardation film for viewing angle compensation (see JP-A-2012-133303

[0227] ), etc.

[0111] The specific configuration of the retardation film, for example, the retardation value, the arrangement angle, the three-dimensional birefringence, whether it is a single layer or a multilayer, etc. are not particularly limited, and a known retardation film can be used.

[0112] The thickness of the retardation film is preferably 20 μm or less, more preferably 10 μm or less, still more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

[0113] The retardation film may include, for example, a quarter-wave plate and / or a half-wave plate in which a liquid crystal material is aligned and fixed.

[0114] The optical film 20A with an adhesive sheet can be formed, for example, by disposing an optical film 2 on the exposed surface of an adhesive sheet 1 formed by peeling a release liner 13 from a second laminate 17 including a base sheet 11, an adhesive sheet 1, and the release liner 13 in this order, and laminating the adhesive sheet 1 and the optical film 2. The second laminate 17 can be formed by the above-described step A. The peeling of the release liner 13 may be performed as the above-described step B.

[0115] Another example of the optical film with an adhesive sheet of the present embodiment is shown in FIG. 8. The optical film 20B with an adhesive sheet in FIG. 8 has a laminated structure in which an adhesive sheet 1A, an optical film 2A, an adhesive sheet 1B, and an optical film 2B are laminated in this order. The optical film 20B with an adhesive sheet may have a structure in which the base sheet used in the production of the adhesive sheet 1A is laminated on the adhesive sheet 1A.

[0116] In the optical film 20B with an adhesive sheet, typically, the optical film 2A is a retardation film and the optical film 2B is a polarizing film. The adhesive sheet 1B functions as an interlayer adhesive for the optical films 2A and 2B. The adhesive sheet 1B may be one using a known adhesive.

[0117] The optical film with an adhesive sheet of the present embodiment can be distributed and stored, for example, as a wound body obtained by winding a strip-shaped optical film with an adhesive sheet or as a sheet-shaped optical film with an adhesive sheet.

[0118] The optical film with an adhesive sheet according to this embodiment is typically used in an image display device. The image display device can be formed, for example, by bonding the optical film 20A or 20B with an adhesive sheet and an image display panel. The bonding is performed, for example, by the adhesive sheet 1. The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to the above examples. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), etc. The image display device can be used for home appliance applications, in-vehicle applications, public information display (PID) applications, etc.

Example

[0119] Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below.

[0120] (Example 1) [Preparation of release liner A] 30 parts by weight of an addition reaction curable silicone (LTC761 containing a hexenyl group-containing polyorganosiloxane, 30 wt% toluene solution, manufactured by Toray Dow Corning), 0.9 parts by weight of a release control agent (BY24-850 containing an unreacted silicone resin, manufactured by Toray Dow Corning), 2 parts by weight of a curing catalyst (SRX212 containing a platinum catalyst, manufactured by Toray Dow Corning), and a toluene / hexane mixed solvent (volume ratio 1:1) as a diluting solvent were mixed to obtain a silicone-based release agent composition A. The concentration of the silicone solid content in the release agent composition A was 1.0 wt%. Next, the release agent composition A was applied to one side of a liner substrate (Lumirror XD500P which is a polyester film, thickness 75 μm) with a wire bar and heated at 130°C for 1 minute to produce a release liner A having a release layer (thickness 60 nm) on one side.

[0121] [Preparation of adhesive composition A] 95.1 parts by weight of n-butyl acrylate (BA), 4.8 parts by weight of acrylic acid (AA), and 0.1 part by weight of 4-hydroxybutyl acrylate (HBA), 0.05 part by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651, manufactured by IGM Resins B.V.) as a photoinitiator, and bis(2,4,6-trimethylbenzoyl ) phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins B.V.) 0.0 5 parts by weight were charged into a four-necked flask and irradiated with ultraviolet rays under a nitrogen atmosphere to obtain a partially photopolymerized monomer syrup. The ultraviolet irradiation was carried out until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 °C) reached about 20 Pa·s. Next, 0.09 part by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent and 0.3 part by weight of isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (BASF's "Irganox 1135") as an antioxidant were added to 100 parts by weight of the monomer syrup and uniformly mixed to obtain an adhesive composition A.

[0122] [Evaluation of peel strength PS 0 On one side of a base sheet (Lumirror XD500P, a polyester film without a release layer, thickness 75 μm), the adhesive composition A was applied with an applicator to form a coating layer (thickness 20 μm). Next, a release liner A was placed on the formed coating layer to obtain a first laminate. The release liner A was placed such that the release layer was in contact with the coating layer. Next, from the side of the base sheet in the first laminate, ultraviolet rays (black light source) were irradiated under the conditions of an illuminance of 2.42 mW / cm 2 , irradiation time of 10 minutes to photocure the coating layer and form a second laminate composed of a base sheet, an adhesive sheet (thickness 20 μm), and a release liner A.

[0123] ​A test piece with a length of 220 mm and a width of 50 mm (the length direction is the coating direction of the pressure-sensitive adhesive composition) was cut out from the formed second laminate. For the test piece, a 180° peel test was carried out using a tensile testing machine to peel off only the release liner A in the length direction, and the peel force PS 0 was evaluated . The conditions of the peel test were as described above

[0124] [Evaluation of peel force PS 1 By the same method as the evaluation of the above peel force PS 0 , a second laminate was produced, and the release liner A was peeled off from the pressure-sensitive adhesive sheet . Next, using the peeled release liner A, the formation of the first laminate, the formation of the second laminate by ultraviolet irradiation, the cutting out of the test piece, and the evaluation of the peel force were carried out in the same manner as above. Thereby, the peel force PS 1 was evaluated

[0125] (Example 2) [Production of release liner B A release liner B having a release layer (thickness: 120 nm) on one side was produced by the same method as the production method of release liner A, except that the thickness of the release agent composition A applied to the liner substrate was changed

[0126] [Evaluation of peel force PS 0 A pressure-sensitive adhesive sheet was produced by the same method as in Example 1, except that release liner B was used. Further, by the same method as in Example 1, the peel force PS 0 was evaluated using the second laminate containing the pressure-sensitive adhesive sheet

[0127] [Evaluation of peel force PS 1 By the same method as the evaluation of the above peel force PS 0 , a second laminate was produced, and the release liner A was peeled off from the pressure-sensitive adhesive sheet ​​​They peeled off the release liner B. Next, using the release liner B peeled off from the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. Further, in the same manner as in Example 1, using the second laminate including the pressure-sensitive adhesive sheet, the peel strength PS 1 was evaluated.

[0128] (Examples 3 to 5) Except that the irradiation conditions of ultraviolet rays when producing the pressure-sensitive adhesive sheet were changed as shown in Table 1, for each of Examples 3 to 5, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 2, and further, the peel strength PS 0 and PS 1 were evaluated.

[0129] (Examples 6 to 7) Except that the compound described in Table 1 was used as the antioxidant contained in the pressure-sensitive adhesive composition A, for each of Examples 6 to 7, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 2, and further, the peel strength PS 0 and PS 1 were evaluated.

[0130] (Comparative Example 1) An adhesive composition B was produced in the same manner as the production method of the adhesive composition A, except that no antioxidant was used. Except that this adhesive composition B was used, for Comparative Example 1, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 2, and further, the peel strength PS 0 and PS 1 were evaluated.

[0131]

Table 1

[0132] The abbreviations in Table 1 are as follows. Irg1135: Isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (「Irganox 1135」 manufactured by BASF, molecular weight 390) LA-52: Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (ADEKA's "ADEKA STAB LA-52", molecular weight 847) 2112: Tris(2,4-di-t-butylphenyl) phosphite (ADEKA's "ADEKA STAB 2112", molecular weight 647)

[0133] As can be seen from Table 1, in the examples where an adhesive composition containing the above antioxidant D was used to produce an adhesive sheet with a thickness of 5 to 100 μm, the peel force PS 1 was a small value compared to the comparative examples. Thus, in the examples, when the release liner is repeatedly used during the production of the adhesive sheet, there is a tendency to suppress the increase in the peel force of the release liner with respect to the adhesive sheet. As a result, the amount of waste of the release liner can be reduced, and the adhesive sheet can be produced with a low environmental load.

Industrial Applicability

[0134] The adhesive sheet of the present invention can be used, for example, in an optical laminate or an image display device.

Explanation of Reference Numerals

[0135] 1 Adhesive sheet 2 Optical film 10 (First) laminate 11 Base sheet 12 Coating layer 13 Release liner 20A, 20B Optical film with adhesive sheet

Claims

1. A pressure-sensitive adhesive sheet formed from a photocurable pressure-sensitive adhesive composition comprising a monomer group including a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator, The thickness of the adhesive sheet is 5 to 100 μm, The pressure-sensitive adhesive composition further comprises an antioxidant, The pressure-sensitive adhesive sheet, wherein the antioxidant comprises at least one selected from the group consisting of hindered phenol compounds, hindered amine compounds, and phosphorus compounds, and has a molecular weight of 1,000 or less.

2. The pressure-sensitive adhesive sheet according to claim 1 , wherein the antioxidant comprises a hindered phenol compound.

3. The pressure-sensitive adhesive sheet according to claim 1 , wherein the molecular weight of the antioxidant is 500 or less.

4. The pressure-sensitive adhesive sheet according to claim 1 , wherein the amount of the hydroxyl group-containing monomer is less than 5 parts by weight per 100 parts by weight of the monomer group.

5. The pressure-sensitive adhesive sheet according to claim 1 , wherein the monomer group includes a carboxyl group-containing monomer.

6. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive composition has a solvent content of 5% by weight or less.

7. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, An optical film; The optical film with adhesive sheet is provided.

8. The optical film with a pressure-sensitive adhesive sheet according to claim 7 , wherein the optical film is a film including at least one film selected from the group consisting of a polarizing film and a retardation film.

9. A method for producing the pressure-sensitive adhesive sheet according to any one of claims 1 to 6, comprising the steps of: The manufacturing method includes: a step A of irradiating light to a laminate including a base sheet, a coating layer including the pressure-sensitive adhesive composition, and a release liner in this order, to form the pressure-sensitive adhesive sheet having a thickness of 5 to 100 μm from the coating layer; Step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, A method for producing a pressure-sensitive adhesive sheet, comprising repeatedly carrying out steps A and B using the release liner peeled off in step B, thereby reusing the release liner.

10. A method for producing an optical film with a pressure-sensitive adhesive sheet, comprising laminating an optical film and the pressure-sensitive adhesive sheet formed by the method according to claim 9 to form an optical film with the pressure-sensitive adhesive sheet.

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