Adhesive sheet, optical film with adhesive sheet, and method for manufacturing the adhesive sheet and the optical film with 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 a pressure-sensitive adhesive sheet, an optical film with a pressure-sensitive adhesive sheet, and a method for producing the pressure-sensitive adhesive sheet and the optical film with a pressure-sensitive adhesive sheet. [Background technology]

[0002] Various image display devices, such as 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 the optical films included in the optical laminate and for bonding between the optical laminate and an image display panel. A typical adhesive sheet is a sheet obtained by polymerizing and crosslinking a monomer group including an acrylic monomer, a silicone monomer, and the like to harden the monomer group.

[0003] Patent Document 1 discloses an example of a pressure-sensitive adhesive sheet, which is produced by irradiating a coating layer of a pressure-sensitive adhesive composition disposed between two release liners with light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6688054 Summary of the Invention [Problem to be solved by the invention]

[0005] Formation of an adhesive sheet by curing usually requires energy such as heat or light. According to a method that utilizes light (photocuring method), the amount of energy required to form an adhesive sheet can be reduced compared to, for example, a method (thermal curing method) in which a coating layer containing an adhesive composition and a solvent is thermally cured in an oven. However, from the viewpoint of reducing the environmental load during the production of an adhesive sheet, it is not sufficient to only focus on the amount of energy required to cure the coating layer.

[0006] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet that can be produced with low environmental impact by reducing the amount of release liners that are discarded during the production of the pressure-sensitive adhesive sheet. [Means for solving the problem]

[0007] The present invention relates to 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 pressure-sensitive adhesive sheet is 5 to 100 μm, The pressure-sensitive adhesive composition further comprises an antioxidant, The pressure-sensitive adhesive sheet is provided, 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.

[0008] Further, the present invention relates to The above adhesive sheet, An optical film; The present invention provides an optical film with a pressure-sensitive adhesive sheet.

[0009] Further, the present invention relates to The method for producing the pressure-sensitive adhesive sheet includes 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; A step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, The method for producing a pressure-sensitive adhesive sheet includes repeatedly carrying out steps A and B using the release liner peeled off in step B, thereby reusing the release liner.

[0010] Further, the present invention relates to The present invention provides a method for producing an optical film with a pressure-sensitive adhesive sheet, the method including laminating an optical film and the pressure-sensitive adhesive sheet formed by the above-mentioned production method to form an optical film with the pressure-sensitive adhesive sheet. Effect of the Invention

[0011] According to the present invention, by reducing the amount of release liners that are discarded in the production of a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet that can be produced with low environmental impact can be provided. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view illustrating a schematic example of a pressure-sensitive adhesive sheet of the present invention. [Figure 2A] FIG. 2 is a schematic diagram for explaining a method for measuring the amount of creep for a pressure-sensitive adhesive sheet. [Figure 2B] FIG. 2 is a schematic diagram for explaining a method for measuring the amount of creep for a pressure-sensitive adhesive sheet. [Diagram 3] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet of the present invention. [Figure 4] FIG. 1 is a cross-sectional view that illustrates a schematic example of a release liner that can be used in the method for producing a pressure-sensitive adhesive sheet of the present invention. [Diagram 5] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet of the present invention. [Figure 6] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet of the present invention. [Figure 7] FIG. 1 is a cross-sectional view illustrating a schematic example of an optical film with a pressure-sensitive adhesive sheet of the present invention. [Figure 8] FIG. 1 is a cross-sectional view illustrating a schematic example of an optical film with a pressure-sensitive adhesive sheet of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The pressure-sensitive adhesive sheet according to the first aspect of the present invention is 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 pressure-sensitive adhesive sheet is 5 to 100 μm, The pressure-sensitive adhesive composition further comprises an antioxidant, The antioxidant contains 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.

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

[0015] In a third aspect of the present invention, for example, in the pressure-sensitive 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 pressure-sensitive 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 per 100 parts by weight of the monomer group.

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

[0018] In a sixth aspect of the present invention, for example, in the pressure-sensitive adhesive sheet according to any one of the first to fifth aspects, the pressure-sensitive adhesive composition has a solvent content of 5 wt % or less.

[0019] The optical film with a pressure-sensitive adhesive sheet according to the seventh aspect of the present invention is A pressure-sensitive adhesive sheet according to any one of the first to sixth aspects; An optical film; Equipped with.

[0020] In an eighth aspect of the present invention, for example in the pressure-sensitive adhesive sheet-attached optical film 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] A method for producing a pressure-sensitive adhesive sheet according to a ninth aspect of the present invention comprises the steps of: A method for producing a pressure-sensitive adhesive sheet according to any one of the first to sixth aspects, comprising: 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; A step B of peeling the release liner from the pressure-sensitive adhesive sheet; Including, The release liner peeled off in the step B is used to repeatedly carry out the steps A and B, thereby reusing the release liner.

[0022] A method for producing an optical film with a pressure-sensitive adhesive sheet according to a tenth aspect of the present invention comprises the steps of: The method includes laminating the pressure-sensitive adhesive sheet formed by the manufacturing method according to the ninth embodiment and an optical film to form an optical film with a pressure-sensitive adhesive sheet.

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

[0024] The inventors came up with the idea of ​​further reducing the environmental impact of the PSA sheet manufacturing process by reusing release liners that were previously discarded immediately after peeling, and continued their research based on this idea, resulting in the completion of the present invention.

[0025] [Embodiment of the adhesive sheet] An example of the pressure-sensitive adhesive sheet of this 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 contains 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 is cured by irradiation with light. In this specification, a photocurable pressure-sensitive adhesive composition may be referred to as a photocurable composition.

[0026] The pressure-sensitive adhesive composition further contains an antioxidant D. The antioxidant D contained in the pressure-sensitive adhesive composition contains at least one selected from the group consisting of hindered phenol compounds, hindered amine compounds, and phosphorus compounds, and has a molecular weight of 1000 or less. When the pressure-sensitive adhesive composition contains antioxidant D, there is a tendency for an increase in the peel strength of the release liner with respect to the pressure-sensitive adhesive sheet 1 to be suppressed during production of the pressure-sensitive adhesive sheet 1. This allows the release liner to be reused repeatedly. This reduces the amount of release liner that is discarded, and allows the pressure-sensitive adhesive sheet 1 to be repeatedly produced with low environmental impact.

[0027] The thickness of the adhesive sheet 1 is 5 to 100 μm, preferably 5 to 50 μm, more preferably 5 to 25 μm, and even more preferably 5 to 20 μm. Since the adhesive sheet 1 has a thickness of 100 μm or less, the absolute amount of residual monomers tends to be smaller than that of an adhesive sheet having a thickness of more than 100 μm. Therefore, during the production of the adhesive sheet 1, the surface of the release liner is less likely to be contaminated with residual monomers, and an increase in the peeling force of the release liner with respect to the adhesive sheet 1 tends to be more suppressed. Since the adhesive sheet 1 has a thickness of 100 μm or less, even if the optical film shrinks while laminated with an optical film such as a polarizing film, the edge of the adhesive sheet 1 tends not to shift easily. Therefore, in an optical film with an adhesive sheet using the adhesive sheet 1, appearance defects such as light leakage caused by the shrinkage of the optical film are unlikely to occur even in a high temperature environment of, for example, about 85° C. or more.

[0028] The adhesive sheet 1 may be laminated with the base sheet and release liner used during its production.

[0029] (Adhesive composition) As described above, the pressure-sensitive 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 pressure-sensitive adhesive composition, i.e., 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, or even 80% by weight or more. In this case, an acrylic pressure-sensitive adhesive sheet containing a (meth)acrylic polymer and its crosslinked product as the main components can be formed. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0030] An example of the (meth)acrylic monomer is a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms on the side chain. The number of carbon atoms in 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 (meth)acrylic acid alkyl ester are 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, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like. 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 (meth)acrylic acid alkyl ester may be n-butyl (meth)acrylate.

[0031] The content of the (meth)acrylic acid alkyl ester 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 partially polymerized product is converted into the weight of 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 of the carboxyl group-containing monomer in the monomer group may be, for example, 10% by weight or less, 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, or even 5% by weight or less. The lower limit of the content may be, for example, 0.1% by weight or more, 0.5% by weight or more, or even 1% by weight or more. The monomer group may not contain a carboxyl group-containing monomer.

[0033] The monomer group may contain a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may contain a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may contribute to improving the cohesive strength of the adhesive sheet. Examples of the hydroxyl 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 hydroxyl group-containing monomer is preferably 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. The content of the hydroxyl 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, or even 0.1% by weight or less. The lower limit of the content may be, for example, 0.01% by weight or more, 0.03% by weight or more, or even 0.05% by weight or more. The monomer group may not contain a hydroxyl group-containing monomer.

[0034] In 100 parts by weight of the monomer group, the amount of the hydroxyl group-containing monomer is preferably less than 5 parts by weight. The amount of the hydroxyl 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, or even 1 part by weight or less. The lower limit of the amount is, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, or even 0.05 parts by weight or more.

[0035] In the pressure-sensitive adhesive composition, each of the above-mentioned 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 a coating layer by appropriately increasing the viscosity of the pressure-sensitive adhesive composition.

[0036] As described above, the pressure-sensitive adhesive composition further contains a photopolymerization initiator. An example of the photopolymerization initiator is a photoradical generator that generates radicals when exposed to visible light and / or ultraviolet light having a wavelength shorter than 450 nm.

[0037] Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzil dimethyl 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-ketol such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; and benzophenone compounds such as benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone. Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-diethylthioxanthone and other thioxanthone compounds; 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 and other triazine-based compounds;Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and titanocene compounds. The pressure-sensitive adhesive composition may contain one or more photopolymerization initiators.

[0038] The amount of the photopolymerization initiator 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, based on 100 parts by weight in total of the monomer group and its partial polymer.

[0039] As described above, the pressure-sensitive adhesive composition further contains an antioxidant D. The antioxidant D contains at least one selected from the group consisting of hindered phenol compounds, hindered amine compounds, and phosphorus compounds. The 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 the antioxidant D preferably does not contain a sulfur atom. The pressure-sensitive adhesive composition may contain one or more types of antioxidant 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, or even 400 or less. The smaller the molecular weight of antioxidant D, the more likely it is that an increase in the peeling force of the release liner from the adhesive sheet 1 during production of the adhesive sheet 1 is suppressed. Due to its small molecular weight, antioxidant D is preferably liquid at room temperature (25°C). 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, or even 300 or more.

[0041] Examples of the hindered phenol compounds include dibutylhydroxytoluene (BHT), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF's "Irganox 1076"), isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF's "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 1330"). 3114"), 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADEKA "ADEKA STAB AO-80"), 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate (Sumitomo Chemical "Sumilizer GS"), 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate (Sumitomo Chemical "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 (Cyanox 1790) manufactured by Cytec, etc. The hindered phenol compound is preferably Irganox 1135.

[0042] Examples of hindered amine compounds include bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate (BASF's "Tinuvin 123"), tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (ADEKA's "ADEKA STAB LA-52"), and tetrakis(2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate (ADEKA A company's "ADK STAB LA-57"), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (ADEKA's "ADK STAB LA-72"), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ADEKA's "ADK STAB LA-77Y"), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (ADEKA's "ADK STAB LA-77G"), bis(1-undecanoxy-2,2,6,6-tetramethylpiperidyl) sebacate (ADEKA's "ADK STAB LA-77G") 1,2,2,6,6-Pentamethyl-4-piperidyl carbonate (ADEKA "ADEKA STAB LA-81"), 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (ADEKA "ADEKA STAB LA-82"), 2,2,6,6-tetramethyl-4-piperidyl methacrylate (ADEKA "ADEKA STAB LA-87"), SONGLIGHT1230 (SONGWON), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (SONGWON) "SONGLIGHT2920"), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate ("SONGLIGHT7700" manufactured by SONGWON), N,N'-bisformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine ("Uvinul4050H" manufactured by BASF), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate ("Uvinul4077H" manufactured by BASF), etc. The hindered amine compound is preferably Adeka STAB 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(butoxyethyl)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, phenylbisphenol-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 pressure-sensitive adhesive composition may contain a crosslinking agent. An example of the crosslinking agent is a polyfunctional monomer having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be a (meth)acrylic monomer. An example of the polyfunctional monomer is a monomer having two or more C=C bonds in one molecule, and a monomer having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, methylol groups, etc. in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0046] Examples of crosslinking agents include (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 (NDD A), polyfunctional acrylates such as 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate (such as ester compounds of polyhydric alcohols and (meth)acrylic acid); allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0047] The amount of the crosslinking agent to be added varies depending on the molecular weight, the number of functional groups, etc., but may be, 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, or even 0.5 parts by weight or less, relative to 100 parts by weight in total of the monomer group and its partial polymer. The lower limit of the amount to be added is, for example, 0.01 parts by weight or more, or may be 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 include a chain transfer agent, a silane coupling agent, a viscosity modifier, a tackifier, a plasticizer, a softener, an antiaging agent, a filler, a colorant, a surfactant, an antistatic agent, and an ultraviolet absorbing agent.

[0049] The content of the solvent in the pressure-sensitive adhesive composition is, for example, 5% by weight or less, and may be 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or even 0.5% by weight or less. The pressure-sensitive adhesive composition may be substantially free of a solvent. The phrase "substantially free of a solvent" means that the solvent derived from additives or the like is allowed to be present at a content 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 poise. A pressure-sensitive adhesive composition having a viscosity in the above range is particularly suitable for forming a coating layer.

[0051] (Physical properties and characteristics of adhesive sheets) 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, or even 99% or more.

[0052] The gel fraction of the pressure-sensitive adhesive sheet 1 is, for example, 50% or more, and may be 75% or more, 80% or more, or 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 is, 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 FIG. 2A and FIG. 2B). First, a laminate of the adhesive sheet 1 to be evaluated and the support film 51 is cut into a rectangular shape of 10 mm×50 mm to prepare a test piece 52. The support film 51 is arranged for the purpose of suppressing deformation of the portion of the adhesive sheet 1 to which the load is applied during the test, thereby enabling more accurate measurement of the creep amount. 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 any thickness that does not deform itself under the load, and is, for example, 20 to 200 μm. Next, as shown in FIG. 2A and FIG. 2B, the test piece 52 is attached to the surface of a stainless steel test plate 53 by the adhesive sheet 1 at a joint surface of 10 mm long×10 mm wide. Note that FIG. 2B shows the cross section BB of FIG. 2A. The test piece 52 is attached to the test plate 53 so that no air bubbles are mixed between the test plate 53 and the adhesive sheet 1. After attachment, the test plate 53 and the adhesive sheet 1 are placed in an autoclave at 50°C and 5 atm (absolute pressure) for 15 minutes to homogenize the bond between the test plate 53 and the adhesive sheet 1. Next, the test plate 53 and the test piece 52 are held vertically with the test plate 53 facing upward and left in an atmosphere at 25°C for at least 5 minutes, and then a weight of 500g is fixed to the center of the lower end of the test piece 52 with the test plate 53 fixed, and a load 54 of 500gf is applied vertically downward. The creep amount (displacement amount) of the adhesive sheet 1 relative to the test plate 53 at a time 3600 seconds after the load 54 is started to be applied is measured as the fall amount of the weight. A laser displacement meter can be used to measure the fall amount of the weight.

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

[0056] 3, steps A and B are repeatedly performed using the release liner 13 peeled off in step B. This reuses the release liner 13. Step A using the peeled release liner 13 is performed by forming a first laminate 10 including, in this order, a base sheet 11, a coating layer 12, and the peeled release liner 13, and irradiating the formed first laminate 10 with light 14.

[0057] As described above, in this embodiment, the adhesive composition contains the antioxidant D, which tends to suppress an increase in the peeling force of the release liner 13 from the adhesive sheet 1 during the production of the adhesive sheet 1. In detail, in the above-mentioned step A, a chemical bond is formed between the release liner 13 and the adhesive sheet 1 by irradiation with light 14, and a part of the bond or a functional group formed by decomposition of the bond may remain on the surface of the release liner 13 even after the adhesive sheet 1 is peeled off. As a result, after the step A is performed, the peeling force of the release liner 13 from the adhesive sheet 1 tends to be increased compared to before the step A is performed. The antioxidant D tends to suppress the formation of a chemical bond between the release liner 13 and the adhesive sheet 1. Furthermore, the antioxidant D also tends to suppress the surface of the release liner 13 from being contaminated by the material of the adhesive sheet 1, regardless of the production conditions of the adhesive sheet 1 (such as the light irradiation time).

[0058] In this embodiment, even if steps A and B are repeatedly performed using release liner 13 peeled off in step B during the production of adhesive sheet 1, there is a tendency to suppress an increase in the peel force of release liner 13 against adhesive sheet 1. Because release liner 13 can be reused repeatedly, the amount of release liner 13 that is discarded can be reduced, and adhesive sheet 1 can be produced with low environmental impact.

[0059] <Process A> (Release liner) An example of the substrate of the release liner 13 (hereinafter, "liner substrate") is a resin film. Examples of resins that can be contained in the liner substrate are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, 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 a transmittance for the light 14 irradiated in step A, or may have the same degree of transmittance for the light 14 as the base 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 substrate. The release liner 13 may include a release layer. The release liner 13 in Fig. 4 includes a liner substrate 131 and a release layer 132 formed on one surface of the liner substrate 131. The release liner 13 in Fig. 4 can be used such that the release layer 132 is on the coating layer 12 side.

[0063] The release layer 132 is typically a cured layer of a release agent composition containing a release agent. As the release agent, various types of release agents can be used, 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. The release liner 13 may be provided with a cured layer of a release agent composition containing a silicone-based release agent as a main component (hereinafter, "silicone release layer"). The silicone release layer is particularly suitable for achieving both adhesion to the pressure-sensitive adhesive sheet 1 and releasability. In this specification, the main component means the component with the largest content.

[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 solventless type, and an addition reaction curable silicone material is preferred. An addition reaction curable silicone material is particularly suitable for forming a release layer that has both adhesion and releasability to the pressure-sensitive 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] An example of the addition reaction curing silicone material is a polyorganosiloxane having a vinyl group or an alkenyl group in the molecule. The addition reaction curing silicone material may not have a hydrosilyl group. Examples of the alkenyl group are 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl, and 11-dodecenyl. Examples of the polyorganosiloxane are polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxane, and copolymers of multiple types 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. An example of the crosslinking agent is polyorganosiloxane 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. An example of the curing catalyst is a platinum catalyst. An example of the platinum catalyst is chloroplatinic acid, an olefin complex of platinum, or an olefin complex of chloroplatinic acid. The amount of the platinum catalyst used is, for example, 10 to 1000 ppm (weight basis, platinum equivalent) 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 promoters. Examples of release control agents are unreactive silicone resins, and more specific examples are organosiloxanes such as octamethylcyclotetrasiloxane, and MQ resins. The amount of the release control agent and adhesion promoter used is, for example, 1 to 30% by weight in total based on the total solid content of the composition. Further examples of additives are fillers, antistatic agents, antioxidants, ultraviolet absorbers, plasticizers, and colorants. The amount of the further additives used is, for example, 10% by weight or less in total 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 the liner substrate 131. For coating the release agent composition, various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, 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, or 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, or 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 may have the release layer 132 on the surface on the side of the coating layer 12, and the thickness of the release layer 132 may be 110 nm or less.

[0072] The release liner 13 may be in the form of a sheet or a continuous piece.

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

[0074] The base sheet 11 preferably has excellent transmittance for the light 14 irradiated in the step A.

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

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

[0077] For the base sheet 11, a sheet having a greater peeling strength from the adhesive sheet 1 than the release liner 13 can usually be selected.

[0078] The base sheet 11 may be in the form of a sheet or a continuous length.

[0079] (First laminate and its formation) The first laminate 10 may include an additional layer other than the base sheet 11, the coating layer 12, and the release liner 13. The additional layer may be disposed on the side of the base sheet 11 and / or the release liner 13 opposite to the side of the coating layer 12. The coating layer 12 is preferably in contact with the base 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 then arranging a release liner 13 (or a base sheet 11) on the formed coating layer 12. Alternatively, the first laminate 10 may be formed by applying a pressure-sensitive adhesive composition by pouring it into the space between the base sheet 11 and the release liner 13 that are held at a predetermined distance so 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 release layer 132 side, becomes the side of the coating layer 12 again.

[0081] The coating layer 12 can be formed by 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.

[0082] The thickness of coating layer 12 can be adjusted depending on the intended thickness of pressure-sensitive adhesive sheet 1, and may be, for example, 5 to 100 μm, 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, may be long. The long first laminate 10 can be obtained, for example, by forming the coating layer 12 between the base sheet 11 and the release liner 13 while conveying them, the base sheet 11 and the release liner 13 being unwound from a roll.

[0084] (Light irradiation) The light 14 irradiated to 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 photopolymerization initiator contained in the pressure-sensitive adhesive composition. The light 14 may be irradiated with light having a short wavelength of 300 nm or less cut by a filter or the like, and cutting the short wavelength light is suitable for suppressing deterioration of the base sheet 11 caused by the light 14. The light source of the light 14 is, for example, a light irradiation device equipped 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, and excimer laser. Two or more ultraviolet irradiation lamps may be combined.

[0085] The illumination with light 14 may be continuous or intermittent.

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

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

[0088] The peel strength between release liner 13 and adhesive sheet 1 is smaller than, for example, the peel strength between base sheet 11 and adhesive sheet 1. The peel strength of base sheet 11 from 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 even 3 to 5 N / 50 mm.

[0089] The number of times that release liner 13 is peeled off and reused in the production of pressure sensitive adhesive sheet 1 is not particularly limited, and may be, for example, 3 or more times, 5 or more times, or even 7 or more times.

[0090] The peeled release liner 13 may be wound into a roll and then reused.

[0091] <Peel strength between adhesive sheet and release liner> In this embodiment, the peel strength PS between the release liner 13 and the adhesive sheet 1 after it has been peeled from the adhesive sheet 1 n times, counting from an unused state, is n (n is an integer of 0 or more corresponding to the number of peels; when n=0, the peel force PS0 in an unused state) is preferably 1.0 N / 50 mm or less.

[0092] As an example, the peel force PS0 between an unused release liner 13 and the pressure sensitive adhesive sheet 1 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 peel force PS0 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 peel force PS1 between the release liner 13 and the adhesive sheet 1 after being peeled off once from the adhesive sheet 1 counting from an unused state is preferably 1.0 N / 50 mm or less, and may be 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 lower limit of the peel force PS1 is, for example, 0.01 N / 50 mm or more, and may be 0.03 N / 50 mm or more, 0.05 N / 50 mm or more, 0.08 N / 50 mm or more, or even 0.1 N / 50 mm or more.

[0094] The ratio PS1 / PS0 of the peel force PS1 to the peel force PS0 may be 10 or less, 8 or less, 6 or less, or even 5 or less. The lower limit of the ratio PS1 / PS0 is, for example, 1.1 or more, and may be 2.0 or more.

[0095] Peeling force PS n can be evaluated by the following method using the second laminate 17 formed by performing step A and step B n times using the release liner 13 and then performing step A for the (n+1)th time. In detail, the second laminate 17 formed by performing step A is cut to a width of 50 mm to prepare a test piece, and a 180° peel test is performed in which only the release liner 13 is peeled off from the prepared test piece. The peel test is performed about 0.5 to 1 hour after 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 at 23°C ± 5°C. The peel speed for the peel test is 300 mm / min, and the test temperature is 23°C ± 5°C. If the width of the second laminate 17 is less than 50 mm, the measured value for 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 direction can be defined as the width direction of the test piece. When the base sheet 11 and the release liner 13 are long, the width direction of the test piece can be defined as the width direction of the test piece.

[0096] Next, referring to FIG. 5, another example of a method for producing the adhesive sheet 1 will be described. In this example, a coating layer 12 of an adhesive composition is formed on one side of a long base sheet 11 unwound from a roll 31 by a coating device 32. Next, a long release liner 13 unwound from a roll 33 is placed on the coating layer 12 to form a long first laminate 10. Next, light 14 is irradiated from a light irradiating device 34 to the first laminate 10 to form a long adhesive sheet 1. Next, the release liner 13 is peeled off from a second laminate 17 including the adhesive sheet 1 and wound up on a roll 35. The above steps are performed while the base sheet 11 and the release liner 13 are being transported. The wound release liner 13 is reused. The method of FIG. 5 is particularly suitable for mass production of the adhesive sheet 1.

[0097] Another example of the method for producing the adhesive sheet 1 will be described with reference to Fig. 6. 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 up into a roll 35. The method of Fig. 6 is particularly suitable for mass production of the adhesive sheet 1.

[0098] [Embodiment of Optical Film with Adhesive Sheet] An example of the optical film with an adhesive sheet of this embodiment is shown in Fig. 7. The optical film with an adhesive sheet 20A in Fig. 7 includes an adhesive sheet 1 and an optical film 2. The adhesive sheet 1 may be in direct contact with the optical film 2, or indirect contact with the optical film 2. The optical film with an adhesive sheet 20A may have a structure in which the base sheet used in producing 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 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 (surface having the widest 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, and examples thereof include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing dichroic substances such as iodine and dichroic dyes; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride; etc. Polarizers are typically made of polyvinyl alcohol films (polyvinyl alcohol films include partially saponified ethylene-vinyl acetate copolymer films) and dichroic substances such as iodine.

[0102] The thickness of the polarizer is not particularly limited, and may be, for example, 80 μm or less, 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, and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, a thickness of 20 μm or less) is suppressed in dimensional change, 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 blocking 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-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the protective film may be a thermosetting resin or an ultraviolet-curing resin such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone-based resin. When the polarizing film has two protective films, the materials of the two protective films may be the same or different from each other. For example, a protective film made of a thermoplastic resin may be bonded to one main surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curing resin may be bonded to the other main surface of the polarizer. The protective film may contain one or more types of optional additives, such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

[0104] The thickness of the protective film can be appropriately determined, but is generally about 10 to 200 μm in terms of strength, workability such as handleability, thinness, and the like.

[0105] The polarizer and the protective film are usually adhered to each other via a water-based adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester. Examples of adhesives other than the above-mentioned adhesives include an ultraviolet-curable adhesive and an electron beam-curable adhesive. The electron beam-curable polarizing plate adhesive exhibits suitable adhesion to various protective films. The adhesive may contain a metal compound filler.

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

[0107] The protective film may have a hard coat layer on the surface opposite to the surface bonded to the polarizer, and may also be subjected to treatments for the purposes of anti-reflection, anti-sticking, diffusion, anti-glare, etc.

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

[0109] The retardation film may be one obtained by stretching a polymer film or one obtained by aligning and fixing a liquid crystal material. The retardation film has birefringence, for example, in the in-plane and / or thickness direction.

[0110] Retardation films include anti-reflection retardation films (see JP 2012-133303 A,

[0221] ,

[0222] ,

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

[0225] ,

[0226] ), and tilted orientation retardation films for viewing angle compensation (see JP 2012-133303 A,

[0227] ).

[0111] The specific configuration of the retardation film, for example, the retardation value, arrangement angle, three-dimensional birefringence, whether it is a single layer or a multilayer, and the like, are not particularly limited, and any 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, further 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 oriented and fixed.

[0114] The optical film 20A with 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 off the release liner 13 from a second laminate 17 containing a base sheet 11, an adhesive sheet 1, and a 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-mentioned step A. The peeling off of the release liner 13 may be performed as the above-mentioned 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 with an adhesive sheet 20B 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 with an adhesive sheet 20B may have a structure in which the base sheet used in producing the adhesive sheet 1A is laminated on the adhesive sheet 1A.

[0116] In the optical film 20B with 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 between the optical films 2A and 2B. The adhesive sheet 1B may be made of a known adhesive.

[0117] The optical film with a pressure-sensitive adhesive sheet of this embodiment can be distributed and stored, for example, as a roll of a strip-shaped optical film with a pressure-sensitive adhesive sheet that is rolled up, or as a sheet-shaped optical film with a pressure-sensitive adhesive sheet.

[0118] The optical film with adhesive sheet of this embodiment is typically used in an image display device. The image display device can be formed, for example, by bonding the optical film with adhesive sheet 20A or 20B to an image display panel. The bonding is performed, for example, by an 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: Field Emission Display), or the like. The image display device can be used for home appliances, in-vehicle applications, public information displays (PID), and the like. EXAMPLES

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

[0120] Example 1 [Preparation of release liner A] Addition reaction curing type silicone (LTC761 containing hexenyl group-containing polyorganosiloxane, 30 wt% toluene solution, manufactured by Dow Corning Toray) 30 parts by weight, release control agent (BY24-850 containing unreactive silicone resin, manufactured by Dow Corning Toray) 0.9 parts by weight, and curing catalyst (SRX212 containing platinum catalyst, manufactured by Dow Corning Toray) 2 parts by weight, and toluene / hexane mixed solvent (volume ratio 1: 1) as a dilution solvent were mixed to obtain a silicone-based release agent composition A. The concentration of silicone solids 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, a polyester film, thickness 75 μm) with a wire bar and heated at 130 ° C for 1 minute to prepare 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), 0.1 parts by weight of 4-hydroxybutyl acrylate (HBA), 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one (Omnirad651, IGM Resins BV) as photopolymerization initiators, and 0.05 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad819, IGM Resins BV) were placed in a four-bottom flask and irradiated with ultraviolet light under a nitrogen atmosphere to obtain a partially photopolymerized monomer syrup. The ultraviolet light irradiation was continued until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s. Next, 0.09 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent and 0.3 parts 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 the mixture was mixed uniformly to obtain adhesive composition A.

[0122] [Evaluation of peel strength PS0] The pressure-sensitive adhesive composition A was applied to one side of a base sheet (Lumirror XD500P, a polyester film without a release layer, thickness 75 μm) using an applicator to form a coating layer (thickness 20 μm). Next, release liner A was placed on the formed coating layer to obtain a first laminate. Release liner A was placed so that the release layer was in contact with the coating layer. Next, a light source with an illuminance of 2.42 mW / cm was applied from the side of the base sheet in the first laminate. 2 The coating layer was photocured by irradiating it with ultraviolet light (black light source) for 10 minutes to form a second laminate composed of the base sheet, adhesive sheet (thickness 20 μm) and release liner A.

[0123] A test piece 220 mm long and 50 mm wide (the length direction is the application direction of the adhesive composition) was cut out from the formed second laminate. A 180° peel test was performed on the test piece using a tensile tester to peel only the release liner A in the length direction, and the peel force PS0 was evaluated. The peel test conditions were as described above.

[0124] [Evaluation of peel strength PS1] A second laminate was prepared using the same method as in the evaluation of the peel strength PS0 above, and the release liner A was peeled off from the adhesive sheet. Next, using the peeled release liner A, the formation of a first laminate, the formation of a second laminate by irradiating ultraviolet light, the cutting out of test pieces, and the evaluation of the peel strength were carried out using the same methods as above. This allowed the evaluation of the peel strength PS1.

[0125] Example 2 [Preparation of release liner B] Release liner B having a release layer (thickness 120 nm) on one side was prepared in the same manner as release liner A, except that the thickness of release agent composition A applied to the liner substrate was changed.

[0126] [Evaluation of peel strength PS0] A PSA sheet was produced in the same manner as in Example 1, except for using release liner B. Furthermore, in the same manner as in Example 1, the peel force PS0 was evaluated using a second laminate including the PSA sheet.

[0127] [Evaluation of peel strength PS1] A second laminate was produced using the same method as in the evaluation of the peel strength PS0 above, and the release liner B was peeled off from the adhesive sheet. Next, a pressure-sensitive adhesive sheet was produced using the release liner B peeled off from the adhesive sheet using the same method as in Example 1. Furthermore, the peel strength PS1 was evaluated using the second laminate including the adhesive sheet using the same method as in Example 1.

[0128] (Examples 3 to 5) Except for changing the ultraviolet irradiation conditions when preparing the adhesive sheets as shown in Table 1, adhesive sheets were prepared for each of Examples 3 to 5 using the same method as Example 2, and the peel strengths PS0 and PS1 were evaluated.

[0129] (Examples 6 to 7) Except for using the compound shown in Table 1 as the antioxidant contained in adhesive composition A, adhesive sheets were prepared for each of Examples 6 to 7 in the same manner as in Example 2, and the peel strengths PS0 and PS1 were evaluated.

[0130] Comparative Example 1 Except for not using an antioxidant, adhesive composition B was prepared in the same manner as adhesive composition A. Except for using adhesive composition B, adhesive sheets were prepared in the same manner as in Example 2 for Comparative Example 1, and the peel strengths PS0 and PS1 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 (BASF "Irganox 1135", molecular weight 390) LA-52: Tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (ADEKA "ADEKA STAB LA-52", molecular weight 847) 2112: Tris(2,4-di-t-butylphenyl)phosphite (ADEKA "ADEKA STAB 2112", molecular weight 647)

[0133] As can be seen from Table 1, in the Examples in which adhesive sheets having a thickness of 5 to 100 μm were produced using an adhesive composition containing the above-mentioned antioxidant D, the peel strength PS1 was smaller than that of the Comparative Examples. Thus, in the Examples, even if the release liner is repeatedly used during the production of the adhesive sheet, there is a tendency for an increase in the peel strength of the release liner with respect to the adhesive sheet to be suppressed. This makes it possible to reduce the amount of release liner discarded, and to produce an adhesive sheet with low environmental impact. [Industrial Applicability]

[0134] The pressure-sensitive adhesive sheet of the present invention can be used, for example, in optical laminates and image display devices. [Explanation of symbols]

[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 method for producing an adhesive sheet, comprising: the pressure-sensitive adhesive sheet is formed from a photocurable pressure-sensitive adhesive composition containing a monomer group including a (meth)acrylic monomer and / or a partial polymer of the monomer group, and a photopolymerization initiator; The pressure-sensitive adhesive composition further comprises 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; 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.

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

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

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

6. The method for producing a 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. 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 1 to form an optical film with the pressure-sensitive adhesive sheet.

8. A method for producing an optical film with an adhesive sheet as described in claim 7, wherein the optical film is a film including at least one selected from the group consisting of a polarizing film and a retardation film.

Images