JP2024014621A - 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 - Google Patents

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

The present invention relates to an adhesive sheet, an optical film with an adhesive sheet, and a method for producing an adhesive sheet and an optical film with an adhesive sheet.

Various image display devices, typified by liquid crystal display devices and electroluminescent (EL) display devices, generally include an optical laminate including an optical film such as a polarizing film and an adhesive sheet. Adhesive sheets are usually used for bonding between optical films included in an optical laminate and for bonding an optical laminate and an image display panel. A typical pressure-sensitive adhesive sheet is a sheet obtained by curing a group of monomers including acrylic monomers, silicone monomers, etc. by polymerization and crosslinking.

Patent Document 1 discloses an example of an adhesive sheet. In Patent Document 1, a pressure-sensitive adhesive sheet is produced by irradiating a coating layer of a pressure-sensitive adhesive composition placed between two release liners with light.

Patent No. 6688054

Formation of a pressure-sensitive adhesive sheet by curing usually requires energy such as heat or light. According to a method that uses light (photocuring method), the energy required to form an adhesive sheet is lower than, for example, a method of thermally curing a coating layer containing an adhesive composition and a solvent in an oven (thermal curing method). The amount can be reduced. However, from the viewpoint of reducing the environmental load during the production of pressure-sensitive adhesive sheets, it is insufficient to focus only on the amount of energy required to cure the coating layer.

Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet that can be manufactured with a low environmental impact by reducing the amount of waste release liner necessary for manufacturing the pressure-sensitive adhesive sheet.

The present invention
A pressure-sensitive adhesive sheet formed from a photocurable adhesive composition containing a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the monomer group, and a photopolymerization initiator. There it is,
The thickness of the adhesive sheet is 5 to 100 μm,
The adhesive composition further includes an antioxidant,
The present invention provides a pressure-sensitive adhesive sheet in which 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.

Furthermore, the present invention
The above adhesive sheet,
optical film,
An optical film with an adhesive sheet is provided.

Furthermore, the present invention
A method for manufacturing the above-mentioned adhesive sheet,
The manufacturing method includes:
Step A of irradiating a laminate including a base sheet, a coating layer containing the adhesive composition, and a release liner in this order with light to form the adhesive sheet having a thickness of 5 to 100 μm from the coating layer; ,
Step B of peeling off the release liner from the adhesive sheet;
including;
The present invention provides a method for producing a pressure-sensitive adhesive sheet, in which the release liner peeled off in the step B is used to repeatedly perform the step A and the step B to reuse the release liner.

Furthermore, the present invention
A method for producing an optical film with a pressure-sensitive adhesive sheet is provided, which includes laminating the pressure-sensitive adhesive sheet formed by the above-described production method and an optical film to form an optical film with a pressure-sensitive adhesive sheet.

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet that can be manufactured with low environmental impact by reducing the amount of waste release liner necessary for manufacturing the pressure-sensitive adhesive sheet.

FIG. 1 is a cross-sectional view schematically showing an example of a pressure-sensitive adhesive sheet of the present invention. FIG. 3 is a schematic diagram for explaining a method for measuring the amount of creep on a pressure-sensitive adhesive sheet. FIG. 3 is a schematic diagram for explaining a method for measuring the amount of creep on a pressure-sensitive adhesive sheet. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining an example of a method for manufacturing a pressure-sensitive adhesive sheet of the present invention. 1 is a cross-sectional view schematically showing an example of a release liner that can be used in the method for producing a pressure-sensitive adhesive sheet of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining an example of a method for manufacturing a pressure-sensitive adhesive sheet of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining an example of a method for manufacturing a pressure-sensitive adhesive sheet of the present invention. FIG. 1 is a cross-sectional view schematically showing an example of an optical film with an adhesive sheet of the present invention. FIG. 1 is a cross-sectional view schematically showing an example of an optical film with an adhesive sheet of the present invention.

The adhesive sheet according to the first aspect of the present invention is
A pressure-sensitive adhesive sheet formed from a photocurable adhesive composition containing a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the monomer group, and a photopolymerization initiator. There it is,
The thickness of the adhesive sheet is 5 to 100 μm,
The adhesive composition further includes 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 1000 or less.

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

In the 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.

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

In the 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 includes a carboxyl group-containing monomer.

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

The optical film with a pressure-sensitive adhesive sheet according to the seventh aspect of the present invention includes:
An adhesive sheet according to any one of the first to sixth aspects,
optical film,
Equipped with.

In the eighth aspect of the present invention, for example, in the optical film with a pressure-sensitive adhesive sheet according to the seventh aspect, the optical film is a film containing at least one selected from the group consisting of a polarizing film and a retardation film.

The method for producing a pressure-sensitive adhesive sheet according to the ninth aspect of the present invention includes:
A method for producing a pressure-sensitive adhesive sheet according to any one of the first to sixth aspects, comprising:
The manufacturing method includes:
Step A of irradiating a laminate including a base sheet, a coating layer containing the adhesive composition, and a release liner in this order with light to form the adhesive sheet having a thickness of 5 to 100 μm from the coating layer; ,
Step B of peeling off the release liner from the adhesive sheet;
including;
Using the release liner peeled off in step B, the steps A and B are repeated to reuse the release liner.

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

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with arbitrary modifications without departing from the gist of the present invention.

The present inventors came up with the idea of further reducing the environmental load in the manufacturing process of pressure-sensitive adhesive sheets by reusing the release liner, which had been discarded immediately after peeling. Based on this idea, the inventors conducted studies and invented the present invention. completed.

[Embodiment of adhesive sheet]
An example of the adhesive sheet of this embodiment is shown in FIG. The adhesive sheet 1 in FIG. 1 is formed from an adhesive composition. The 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 adhesive composition is a photocurable adhesive composition that is cured by irradiation with light. In this specification, a photocurable adhesive composition may be referred to as a photocurable composition.

The adhesive composition further contains antioxidant D. The antioxidant D contained in the 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. According to the pressure-sensitive adhesive composition containing antioxidant D, an increase in the peeling force of the release liner against the pressure-sensitive adhesive sheet 1 during production of the pressure-sensitive adhesive sheet 1 tends to be suppressed. Therefore, the release liner can be used repeatedly. Thereby, the amount of waste release liner can be reduced, and the adhesive sheet 1 can be repeatedly manufactured with low environmental impact.

The thickness of the 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 adhesive sheet 1 has a thickness of 100 μm or less, the absolute amount of residual monomer tends to be smaller than that of a pressure-sensitive 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 monomer, and an increase in the peeling force of the release liner with respect to the adhesive sheet 1 tends to be further suppressed. Since the pressure-sensitive adhesive sheet 1 has a thickness of 100 μm or less, even if the optical film shrinks while being laminated with an optical film such as a polarizing film, it tends not to shift easily at the end portions. Therefore, in an optical film with a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive sheet 1, appearance defects such as light leakage due to shrinkage of the optical film are unlikely to occur even in a high-temperature environment of about 85° C. or higher, for example.

The adhesive sheet 1 may be laminated with a base sheet or a release liner used in its production.

(Adhesive composition)
As described above, the adhesive composition of the present embodiment includes 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, is 50% by weight or more, 60% by weight or more, 70% by weight or more, and even 80% by weight or more. It may be % by weight or more, and in this case, an acrylic pressure-sensitive adhesive sheet containing a (meth)acrylic polymer and a crosslinked product thereof as main components can be formed. In this specification, (meth)acrylic means acrylic and methacryl. (Meth)acrylate means acrylate and methacrylate.

An example of the (meth)acrylic monomer is a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms in 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 (meth)acrylic acid alkyl esters 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, 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.

The content of (meth)acrylic acid alkyl ester in the monomer group is, for example, 40% by weight or more, 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, It may be 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 to the weight of each monomer before polymerization.

The monomer group may include carboxyl group-containing monomers. The carboxyl group-containing monomer may be a (meth)acrylic monomer, or in other words, the (meth)acrylic monomer may include a carboxyl group-containing monomer. Examples of carboxyl group-containing monomers 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 is, 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. , and further may be 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 does not need to contain carboxyl group-containing monomers.

The monomer group may include a hydroxy group-containing monomer. The hydroxy group-containing monomer may be a (meth)acrylic monomer, or in other words, the (meth)acrylic monomer may include 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 hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, They are 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 or 4-hydroxybutyl (meth)acrylate. The content of the hydroxy group-containing monomer in the monomer group is, for example, 10% by weight or less, 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% by weight or less. It may be 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, and even 0.05% by weight or more. The monomer group does not need to contain hydroxy group-containing monomers.

Out of 100 parts by weight of the monomer group, the 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.

In the adhesive composition, each of the above-mentioned monomers may be contained as a partially polymerized product. The partial polymer may be either a homopolymer or a copolymer. The partial polymer can contribute to stable formation of the coating layer by appropriately increasing the viscosity of the pressure-sensitive adhesive composition.

As mentioned above, the adhesive composition further includes a photopolymerization initiator. An example of the photopolymerization initiator is a photoradical generator that generates radicals using visible light and/or ultraviolet light having a wavelength shorter than 450 nm.

Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; substituted benzoin ethers such as anisole methyl ether; 2,2-diethoxyacetophenone, 2,2-dimethoxy-2- Substituted acetophenones such as phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenylketone; substituted alphaketols 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; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, Benzophenone compounds such as 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropyl Thioxanthone compounds such as thioxanthone, 2,4-diisopropylthioxanthone, 2,4-diethylthioxanthone; 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 compounds; 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], Oxime ester compounds such as O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene) hydroxylamine; bis(2,4,6-trimethylbenzoyl)phenyl Phosphine compounds such as phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, and ethyl anthraquinone; Borate compounds; Carbazole compounds; Imidazole compounds compounds; and titanocene compounds. The adhesive composition may contain one or more photopolymerization initiators.

The amount of the photopolymerization initiator in the adhesive composition is, for example, 0.02 to 10 parts by weight, and 0.05 to 5 parts by weight, based on a total of 100 parts by weight of the monomer group and its partial polymer. It may be.

As mentioned above, the 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. 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. It is preferable that the compound contained in antioxidant D does not contain a sulfur atom. The adhesive composition may contain one or more antioxidants D.

The molecular weight of antioxidant D is 1000 or less. The molecular weight of antioxidant D is preferably 800 or less, may be 500 or less, and even may be 400 or less. The smaller the molecular weight of the antioxidant D is, the more the increase in the release force of the release liner to the adhesive sheet 1 tends to be suppressed during production of the adhesive sheet 1. Note that the 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, or even 300 or more.

Examples of hindered phenol compounds 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" manufactured by BASF), 3,3',3'',5,5',5''-hex-tert-butyl -a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol (BASF "Irganox 1330"), 1,3,5-tris(3,5-di-tert) -butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (“Irganox 3114” manufactured by BASF), 3,9-bis{2-[3 -(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxyoxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (manufactured by ADEKA) "ADK STAB AO-80"), 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate (Sumitomo Chemical's "Sumilyzer GS"), 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate ("Sumilyzer GM" manufactured by Sumitomo Chemical), 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 "Sumilyzer 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) and the like. The hindered phenolic compound is preferably Irganox 1135.

Examples of hindered amine compounds include bis-(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate (“Tinuvin123” manufactured by BASF), tetrakis (1,2,2,6,6- Pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate (ADEKA "ADEKA STAB LA-52"), Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane- 1,2,3,4-tetracarboxylate (“ADEKA STAB LA-57” manufactured by ADEKA), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (“ADEKA STAB LA-57” manufactured by ADEKA) 72"), bis-(2,2,6,6-tetramethyl-4-piperidyl) sebacate ("ADEKA STAB LA-77Y"), bis(2,2,6,6-tetramethyl-4- bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)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-82'') -87"), SONGLIGHT1230 (manufactured by SONGWON), bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate ("SONGLIGHT2920" manufactured by SONGWON), 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 (“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.

Phosphorous compounds include trioctyl phosphite, trilauryl phosphite, tristridecyl phosphite, trisisodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl Phosphite, diphenylisodecylphosphite, diphenyltridecylphosphite, triphenylphosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(butoxyethyl)phosphite phyto, tris(biphenyl)phosphite, tris(3,5-di-t-butyl-4-hydroxyphenyl)phosphite, 9,10-dihydro-9-phosphaphenanthrene-10-oxide, distearylpenta Erythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenyl 4,4'-isopropylidenediphenol pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite Examples include phosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and phenylbisphenol-A-pentaerythritol diphosphite.

The blending amount of the antioxidant is, for example, 0.01 part by weight or more, 0.05 part by weight or more, 0.1 part by weight or more, based on a total of 100 parts by weight of the monomer group and its partial polymer. Furthermore, the amount may be 0.3 parts by weight or more. The upper limit of the blending 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, and even 0.5 parts by weight or less.

The adhesive composition may contain a crosslinking agent. An example of a 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. Examples of polyfunctional monomers include monomers having two or more C=C bonds in one molecule, and one or more C=C bonds in one molecule and one or more epoxy groups, aziridine groups, and oxazolines. It is a monomer having a polymerizable functional group such as a hydrazine group, a hydrazine group, or a methylol group. The polyfunctional monomer is preferably a monomer having two or more C═C bonds in one molecule.

Examples of crosslinking agents are (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, ) acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDDA), 1, Polyfunctional acrylates (ester compounds of polyhydric alcohol and (meth)acrylic acid, etc.) such as 12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; 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, more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate.

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, based on a total of 100 parts by weight of the monomer group and its partial polymer. Below, the amount may be 1 part by weight or less, or even 0.5 part by weight or less. The lower limit of the blending amount is, for example, 0.01 part by weight or more, and may even be 0.05 part by weight or more.

The adhesive composition may contain additives other than those mentioned above. Examples of additives are chain transfer agents, silane coupling agents, viscosity modifiers, tackifiers, plasticizers, softeners, anti-aging agents, fillers, colorants, surfactants, antistatic agents and UV absorbers. It is.

The content of the solvent in the 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. Good too. The adhesive composition may be substantially free of solvent. "Substantially free of solvent" means that the content of solvents derived from additives etc. is, for example, 0.1% by weight or less, preferably 0.05% by weight or less, more preferably 0.01% by weight or less. The intention is to allow it.

The viscosity of the adhesive composition is preferably 5 to 100 poise. An adhesive composition having a viscosity within the above range is particularly suitable for forming a coating layer.

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

The gel fraction of the adhesive sheet 1 is, for example, 50% or more, and may be 75% or more, 80% or more, or even 85% or more.

The creep amount of the 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.

The amount of creep of the adhesive sheet 1 can be evaluated as follows (see FIGS. 2A and 2B). First, a test piece 52 is obtained by cutting a laminate of the adhesive sheet 1 and the support film 51 to be evaluated into a strip of 10 mm x 50 mm. The support film 51 is disposed for the purpose of suppressing deformation of the load-applied portion of the pressure-sensitive adhesive sheet 1 during a test, and thereby measuring the amount of creep with higher accuracy. 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 such that it does not deform itself under the above load, and is, 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 using the adhesive sheet 1 at a joint surface measuring 10 mm in length and 10 mm in width. Note that FIG. 2B is a cross section BB in FIG. 2A. The test piece 52 is attached to the test plate 53 so that air bubbles are not mixed between the test plate 53 and the adhesive sheet 1. Further, after pasting, 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 of 25°C for at least 5 minutes. A weight with a mass of 500 g is fixed at the center of the lower end, and a load 54 of 500 gf is applied vertically downward. The amount of creep (deviation amount) of the adhesive sheet 1 with respect to the test plate 53 at the time point 3600 seconds after the start of applying the load 54 is measured as the amount of fall of the weight. A laser displacement meter can be used to measure the amount of weight fall.

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

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

As described above, in this embodiment, since the adhesive composition contains the antioxidant D, an increase in the peeling force of the release liner 13 with respect to the adhesive sheet 1 tends to be suppressed when the adhesive sheet 1 is manufactured. Specifically, in the above step A, a chemical bond is generated between the release liner 13 and the adhesive sheet 1 by irradiation with the light 14, and a part of the chemical bond or a functional group formed by decomposition of the bond is transferred to the adhesive sheet 1. may remain on the surface of the release liner 13 even after removal. As a result, after carrying out step A, the peeling force of the release liner 13 with respect to the adhesive sheet 1 tends to increase more than before carrying out the process. According to the antioxidant D, there is a tendency that chemical bonding between the release liner 13 and the pressure-sensitive adhesive sheet 1 can be suppressed. Furthermore, the antioxidant D tends to suppress the surface of the release liner 13 from being contaminated with the material of the adhesive sheet 1, regardless of the manufacturing conditions of the adhesive sheet 1 (light irradiation time, etc.).

In this embodiment, even if Step A and Step B are repeatedly performed using the release liner 13 that was peeled off in Step B during the production of the adhesive sheet 1, the release liner 13 can be peeled off from the adhesive sheet 1. The increase in force tends to be suppressed. Since the release liner 13 can be used repeatedly, the amount of waste of the release liner 13 can be reduced, and the adhesive sheet 1 can be manufactured with low environmental impact.

<Process A>
(Release liner)
An example of the base material of the release liner 13 (hereinafter referred to as "liner base material") is a resin film. Examples of resins that can be included in the liner base material are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyether sulfones, polycarbonates, polyamides, polyimides, polyolefins, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride. , polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

The release liner 13 may have the transparency of the light 14 irradiated in step A, or may have the same level of transparency of the light 14 as the base sheet 11 .

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

Release liner 13 may include layers 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 shown in FIG. 4 can be used so that the release layer 132 is on the coating layer 12 side.

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

The silicone mold release agent is, for example, various types of curable silicone materials such as addition reaction type, condensation reaction type, ultraviolet curable type, electron beam curable type, and solvent-free type, with addition reaction curable silicone materials being preferred. The 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.

An example of an addition reaction-curable silicone material is a polyorganosiloxane having a vinyl group or an alkenyl group in the molecule. The addition reaction curable silicone material does not need to have a hydrosilyl group. Examples of alkenyl groups are 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl, and 11-dodecenyl. It is the basis. Examples of polyorganosiloxanes include polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxanes, and a plurality of Si atom-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). It is a copolymer. The polyorganosiloxane is preferably polydimethylsiloxane.

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

The silicone mold release agent composition may also include a curing catalyst. An example of a curing catalyst is a platinum-based catalyst. Examples of platinum-based catalysts are chloroplatinic acid, olefin complexes of platinum, and olefin complexes of chloroplatinic acid. The amount of the platinum-based catalyst used is, for example, 10 to 1000 ppm (by weight, in terms of platinum) based on the total solid content of the composition.

The silicone mold release agent composition may also contain additives. Examples of additives are release control agents and adhesion promoters. Examples of release control agents are unreacted silicone resins, and more specific examples are organosiloxanes such as octamethylcyclotetrasiloxane, and MQ resins. The total amount of the peel 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, UV absorbers, plasticizers and colorants. The amount of further additives used is, for example, up to 10% by weight in total, based on the total solids content of the composition.

The silicone mold release agent composition may include an organic solvent. Examples of organic solvents 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. Solvent: Alcohol solvent such as methanol, ethanol, butanol. Two or more types of organic solvents may be included. The amount of organic solvent used is preferably 80 to 99.9% by weight of the silicone mold release agent composition.

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 base material 131. Application of the release agent composition includes 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. Various coating methods can be applied. For example, hot air drying can be used for heating and drying. The heating temperature and time vary depending on the heat resistance of the liner base material, but are usually about 80 to 150°C and about 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet rays may be used in combination.

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 include the release layer 132 on the surface facing the coating layer 12, and the thickness of the release layer 132 may be 110 nm or less. There may be.

The release liner 13 may be sheet-like or elongated.

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

It is preferable that the base sheet 11 has excellent transparency for the light 14 irradiated in step A.

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

The base sheet 11 may include a release layer on the surface facing the coating layer 12 . Examples of the release layer that the base sheet 11 can include and its manufacturing method are the same as the examples of the release layer that the release liner 13 can include and its manufacturing method. Both the release liner 13 and the base sheet 11 may be provided with a release layer. In this case, both mold release layers may be formed from mold release agent compositions containing the same mold release agent as a main component. Further, the thicknesses of both release layers may be different, and for example, the release layer included in the base sheet 11 may be thicker.

As the base sheet 11, a sheet can usually be selected that has a greater peel strength with respect to the adhesive sheet 1 than the release liner 13.

The base sheet 11 may be sheet-shaped or elongated.

(First laminate and its formation)
The first laminate 10 may include further layers other than the base sheet 11, the coating layer 12, and the release liner 13. The further layer may be arranged 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.

The first laminate 10 is constructed by, for example, 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. It can be formed by Further, the first laminate 10 is formed by pouring and applying the adhesive composition into the space between the base sheet 11 and the release liner 13 which are held at a predetermined interval so that their main surfaces face each other. It's okay. The peeled release liner 13 may be used so that the surface that was on the coating layer 12 side in step A immediately before peeling, for example, the surface on the release layer 132 side, becomes the coating layer 12 side again. .

The coating layer 12 can be formed using a roll coat, a kiss roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, a dip roll coat, a bar coat, a knife coat, an air knife coat, a curtain coat, a lip coat, a die coat, etc. Various application methods can be applied.

The thickness of the coating layer 12 can be adjusted depending on the intended thickness of the 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.

The first laminate 10 may include an elongated base sheet 11, an elongated coating layer 12, and an elongated release liner 13; in other words, even if it is elongated, good. The elongated first laminate 10 can be obtained, for example, by forming the coating layer 12 between the base sheet 11 and the release liner 13 that have been unwound from the roll while being conveyed.

(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 include light with a wavelength in the same region as the absorption wavelength of the photopolymerization initiator included in the adhesive composition. The light 14 may be irradiated by cutting short wavelength light of 300 nm or less with a filter or the like, and cutting off the short wavelength light is suitable for suppressing deterioration of the base sheet 11 due to the light 14. The light source of the light 14 is, for example, a light irradiation device including an ultraviolet irradiation lamp. Examples of UV irradiation lamps are ultraviolet LEDs, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, extra high pressure mercury lamps, metal halide lamps, xenon lamps, microwave excited mercury lamps, black light lamps, chemical lamps, germicidal lamps, and low pressure discharge mercury lamps. , an excimer laser. Two or more ultraviolet irradiation lamps may be combined.

Irradiation of the light 14 may be continuous or intermittent.

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 cumulative amount of light 14 to the first laminate 10 is, for example, 100 to 5000 mJ/cm ² .

<Process B>
In step B, the release liner 13 is peeled off from the second laminate 17 after curing. The second laminate 17 includes a base sheet 11, an adhesive sheet 1, and a 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 adhesive sheet 1 are obtained.

The peeling force between the release liner 13 and the adhesive sheet 1 is smaller than, for example, the peeling force between the base sheet 11 and the adhesive sheet 1. The peeling force of the base sheet 11 to the 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.

The number of times the release liner 13 is peeled off and reused for manufacturing the pressure-sensitive adhesive sheet 1 is not particularly limited, but may be, for example, 3 or more times, 5 or more times, or even 7 or more times.

The peeled release liner 13 may be reused after being wound up into a rolled body.

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

As an example, the peeling force PS ₀ between the release liner 13 in an unused state and the adhesive sheet 1 is not particularly limited, and is, for example, 1.0 N/50 mm or less, 0.5 N/50 mm or less, 0.2 N/ It may be 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.

The peeling force PS 1 between the release liner 13 and the adhesive sheet ₁ after being peeled off from the adhesive sheet 1 once from an unused state is preferably 1.0 N/50 mm or less, and 0.9 N/ 50mm or less, 0.8N/50mm or less, 0.7N/50mm or less, 0.6N/50mm or less, 0.5N/50mm or less, 0.4N/50mm or less, 0.3N/50mm or less, 0.2N/50mm It may be less than or equal to 0.15 N/50 mm. The lower limit of the peeling force PS ₁ is, for example, 0.01 N/50 mm or more, 0.03 N/50 mm or more, 0.05 N/50 mm or more, 0.08 N/50 mm or more, and further 0.1 N/50 mm or more. Good too.

The above ratio PS ₁ /PS ₀ of the peeling force PS ₁ to the peeling force PS ₀ may be 10 or less, 8 or less, 6 or less, or even 5 or less. The lower limit of the ratio PS ₁ /PS ₀ is, for example, 1.1 or more, and may be 2.0 or more.

The peeling force PS _n is determined as follows using the second laminate 17 formed by carrying out Step A and Step B n times using the above-mentioned release liner 13, and then carrying out Step A for the (n+1)th time. It can be evaluated using the following method. Specifically, the second laminate 17 formed by carrying out step A is cut out to a width of 50 mm to prepare a test piece, and a 180° peeling test is performed in which only the release liner 13 is peeled off from the prepared test piece. It can be evaluated by The peel test is carried out after approximately 0.5 to 1 hour has elapsed from the formation of the adhesive sheet 1. From the formation of the adhesive sheet 1 to the implementation of the peel test, the second laminate 17 and the test piece are placed in an air atmosphere at 23° C.±5° C. The peeling speed of the peeling 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 at the original width may be converted to a value per 50 mm width. When the direction in which the coating layer 12 is formed can be determined, the TD perpendicular to the MD, which is the direction, can be determined as the width direction of the test piece. When the base sheet 11 and release liner 13 are elongated, the width direction thereof can be the width direction of the test piece.

Next, with reference to FIG. 5, another example of the method for manufacturing the adhesive sheet 1 will be described. In this example, a coating layer 12 of the adhesive composition is formed on one side of a long base sheet 11 fed out from a roll 31 using a coating device 32 . Next, the elongated release liner 13 unwound from the rolled body 33 is placed on the coating layer 12 to form the elongated first laminate 10. Next, the first laminate 10 is irradiated with light 14 from the light irradiation device 34 to form the elongated adhesive sheet 1. Next, the release liner 13 is peeled off from the second laminate 17 including the adhesive sheet 1 and wound up into a roll 35 . The above steps are performed while conveying the base sheet 11 and release liner 13. The rolled-up release liner 13 is reused. The method shown in FIG. 5 is particularly suitable for mass production of adhesive sheets 1.

Another example of the method for manufacturing the adhesive sheet 1 will be described with reference to FIG. 6. This example is the same as the example shown in FIG. 5 except that the release liner 13 peeled off from the second laminate 17 is not wound up into the roll 35 and is reused for manufacturing the adhesive sheet 1. The method shown in FIG. 6 is particularly suitable for mass production of adhesive sheets 1.

[Embodiment of optical film with adhesive sheet]
An example of the optical film with an adhesive sheet of this embodiment is shown in FIG. The adhesive sheet-attached optical film 20A shown 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 may be in indirect contact with the optical film 2. The adhesive sheet-attached optical film 20A may have a structure in which the base sheet used in producing the adhesive sheet 1 is laminated on the adhesive sheet 1.

The optical film 2 is, for example, a film containing 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 example.

A polarizing film includes a polarizer. A polarizing film typically includes a polarizer and a protective film (transparent protective film). The protective film is placed, for example, in contact with the main surface (the surface with the widest area) of the polarizer. A polarizer may be placed between two protective films. The protective film may be placed on at least one surface of the polarizer.

The polarizer is not particularly limited, and examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, partially saponified ethylene/vinyl acetate copolymer films, iodine, and dichroism. Examples include those obtained by adsorbing dichroic substances such as dyes and uniaxially stretched; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochloric acid treated polyvinyl chloride. A polarizer typically consists of a polyvinyl alcohol film (polyvinyl alcohol films include partially saponified ethylene/vinyl acetate copolymer films) and a dichroic substance such as iodine.

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, 20 μm or less in thickness) has suppressed dimensional changes and can contribute to improving the durability of the optical laminate, especially the durability under high temperatures.

As a material for the protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, and cyclic resins. Examples include 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 or an ultraviolet curing resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone. When the polarizing film has two protective films, the materials of the two protective films may be the same or different. For example, a protective film made of a thermoplastic resin is attached to one main surface of a polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet curable resin is attached to the other main surface of the polarizer. A protective film made of molded resin may be attached. The protective film may contain one or more types of arbitrary additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

The thickness of the protective film can be determined as appropriate, but is generally about 10 to 200 μm from the viewpoint of strength, workability such as handling, thin film properties, etc.

The polarizer and the protective film are usually in close contact with each other via a water-based adhesive or the like. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex, water-based polyurethanes, and water-based polyesters. Examples of adhesives other than the above adhesives include ultraviolet curable adhesives and electron beam curable adhesives. Electron beam-curable adhesives for polarizing plates exhibit suitable adhesion to various types of protective films. The adhesive may include a metal compound filler.

In the polarizing film, a retardation film or the like may be formed on the polarizer instead of the protective film. It is also possible to provide another protective film, a retardation film, etc. on the protective film.

Regarding the protective film, a hard coat layer may be provided on the surface opposite to the surface bonded to the polarizer, and treatments for the purpose of anti-reflection, anti-sticking, diffusion, anti-glare, etc. can also be applied. .

The polarizing film may be a circularly polarizing film.

As the retardation film, one obtained by stretching a polymer film or one obtained by aligning and fixing a liquid crystal material can be used. The retardation film has, for example, birefringence in the plane and/or in the thickness direction.

The retardation film includes a retardation film for antireflection (see JP-A-2012-133303 [0221], [0222], and [0228]) and a retardation film for viewing angle compensation (see JP-A 2012-133303 [0221], [0222], and [0228]). 0225], [0226]), an obliquely oriented retardation film for viewing angle compensation (see JP-A-2012-133303 [0227]), and the like.

The specific structure of the retardation film, for example, retardation value, arrangement angle, three-dimensional birefringence, single layer or multilayer, etc., is not particularly limited, and any known retardation film can be used.

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, particularly preferably 3 to 8 μm.

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.

The adhesive sheet-attached optical film 20A is, for example, formed by peeling off the release liner 13 from the second laminate 17 including the base sheet 11, the adhesive sheet 1, and the release liner 13 in this order. It can be formed by arranging the optical film 2 on the surface and laminating the adhesive sheet 1 and the optical film 2. The second laminate 17 can be formed by the above step A. Peeling of the release liner 13 may be performed as step B above.

Another example of the optical film with adhesive sheet of this embodiment is shown in FIG. The adhesive sheet-attached optical film 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 adhesive sheet-attached optical film 20B may have a structure in which the base sheet used in producing the adhesive sheet 1A is laminated on the adhesive sheet 1A.

In the optical film with adhesive sheet 20B, 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 one using a known adhesive.

The optical film with a pressure-sensitive adhesive sheet of this embodiment can be distributed and stored, for example, as a roll of a band-shaped optical film with a pressure-sensitive adhesive sheet, or as a sheet-shaped optical film with a pressure-sensitive adhesive sheet.

The optical film with adhesive sheet of this embodiment is typically used for image display devices. The image display device can be formed, for example, by joining the optical film 20A or 20B with an adhesive sheet and an image display panel. The bonding is performed using the adhesive sheet 1, for example. 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 example. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), or the like. The image display device can be used for household appliances, in-vehicle applications, public information displays (PID), and the like.

Hereinafter, the present invention will be explained in more detail with reference to Examples. The invention is not limited to the examples shown below.

(Example 1)
[Preparation of release liner A]
Addition reaction curing silicone (LTC761 containing hexenyl group-containing polyorganosiloxane, 30% by weight toluene solution, manufactured by Dow Corning Toray), 30 parts by weight, release control agent (BY24-850 containing unreactive silicone resin, Toray Dow) (manufactured by Corning), 2 parts by weight of a curing catalyst (SRX212 containing platinum catalyst, manufactured by Dow Corning Toray), and a mixed solvent of toluene/hexane (volume ratio 1:1) as a diluting solvent. Silicone mold release agent composition A was obtained. The concentration of silicone solids in mold release agent composition A was 1.0% by weight. Next, mold release agent composition A was applied to one side of the liner base material (Lumirror ) was prepared on one side.

[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 part by weight of 4-hydroxybutyl acrylate (HBA), and 2,2- as a photopolymerization initiator. 0.05 parts by weight of dimethoxy-1,2-diphenylethan-1-one (Omnirad 651, manufactured by IGM Resins BV), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins BV) ) and 0.05 parts by weight were placed in a Lof 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 approximately 20 Pa·s. Next, to 100 parts by weight of monomer syrup, 0.09 parts by weight of 1,9-nonanediol diacrylate (NDDA) was added as a crosslinking agent, and isooctyl-3-(3,5-di-tert- Adhesive composition A was obtained by adding 0.3 parts by weight of butyl-4-hydroxyphenyl) propionate ("Irganox 1135" manufactured by BASF) and uniformly mixing.

[Evaluation of peeling force PS ₀ ]
Adhesive composition A was applied to one side of a base sheet (Lumirror XD500P, which is a polyester film without a release layer, thickness 75 μm) using 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. Release liner A was arranged so that the release layer was in contact with the coating layer. Next, ultraviolet rays (black light source) are irradiated from the base sheet side of the first laminate at an illuminance of 2.42 mW/cm ² and an irradiation time of 10 minutes to photocure the coating layer, and then A second laminate consisting of the material sheet, adhesive sheet (thickness: 20 μm), and release liner A was formed.

A test piece with a length of 220 mm and a width of 50 mm (the length direction is the direction in which the adhesive composition was applied) was cut from the second laminate thus formed. The test piece was subjected to a 180° peel test in which only the release liner A was peeled off in the length direction using a tensile testing machine, and the peel force PS ₀ was evaluated. The conditions for the peel test were as described above.

[Evaluation of peeling force PS ₁ ]
A second laminate was produced by the same method as in the evaluation of the peel force PS ₀ above, and the release liner A was peeled from the adhesive sheet. Next, using the released release liner A, a first laminate was formed, a second laminate was formed by irradiation with ultraviolet rays, a test piece was cut out, and the peel force was evaluated in the same manner as above. Ta. Thereby, the peeling force PS ₁ was evaluated.

(Example 2)
[Preparation 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 base material was changed. did.

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

[Evaluation of peeling force PS ₁ ]
A second laminate was produced by the same method as in the evaluation of the peel force PS ₀ above, and the release liner B was peeled from the pressure-sensitive adhesive sheet. Next, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 using release liner B that had been peeled off from the pressure-sensitive adhesive sheet. Furthermore, using the same method as in Example 1, the peel force PS ₁ was evaluated using the second laminate containing the adhesive sheet.

(Examples 3 to 5)
Adhesive sheets were prepared for each of Examples 3 to 5 by the same method as in Example 2, except that the ultraviolet irradiation conditions when preparing the adhesive sheets were changed as shown in Table 1, and further, peeling was performed. The forces PS ₀ and PS ₁ were evaluated.

(Examples 6-7)
A pressure-sensitive adhesive sheet was prepared for each of Examples 6 to 7 by the same method as in Example 2, except that the compound listed in Table 1 was used as the antioxidant contained in pressure-sensitive adhesive composition A, and further, Peel forces PS ₀ and PS ₁ were evaluated.

(Comparative example 1)
Adhesive composition B was prepared in the same manner as adhesive composition A, except that no antioxidant was used. A pressure-sensitive adhesive sheet was prepared for Comparative Example 1 in the same manner as in Example 2, except that this pressure-sensitive adhesive composition B was used, and the peeling forces PS ₀ and PS ₁ were evaluated.

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 STAB LA-52” manufactured by ADEKA, molecular weight 847)
2112: Tris(2,4-di-t-butylphenyl) phosphite (“ADEKA Stab 2112” manufactured by ADEKA, molecular weight 647)

As can be seen from Table 1, in the examples in which adhesive sheets with a thickness of 5 to 100 μm were prepared using the adhesive composition containing the above-mentioned antioxidant D, the peeling force PS ₁ was a smaller value than in the comparative examples. Met. As described above, in the examples, even if the release liner is repeatedly used during the production of the pressure-sensitive adhesive sheet, the increase in the peeling force of the release liner against the pressure-sensitive adhesive sheet tends to be suppressed. This makes it possible to reduce the amount of release liner waste and to produce adhesive sheets with low environmental impact.

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

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 (10)

A pressure-sensitive adhesive sheet formed from a photocurable adhesive composition containing a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the monomer group, and a photopolymerization initiator. There it is,
The thickness of the adhesive sheet is 5 to 100 μm,
The adhesive composition further includes an antioxidant,
A pressure-sensitive adhesive sheet, wherein 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 pressure-sensitive adhesive sheet according to claim 1, wherein the antioxidant includes a hindered phenol compound. The adhesive sheet according to claim 1, wherein the molecular weight of the antioxidant is 500 or less. The adhesive sheet according to claim 1, wherein the amount of the hydroxy group-containing monomer is less than 5 parts by weight out of 100 parts by weight of the monomer group. The adhesive sheet according to claim 1, wherein the monomer group includes a carboxyl group-containing monomer. The pressure-sensitive adhesive sheet according to claim 1, wherein the content of the solvent in the pressure-sensitive adhesive composition is 5% by weight or less. The adhesive sheet according to any one of claims 1 to 6,
optical film,
Optical film with adhesive sheet. The optical film with an adhesive sheet according to claim 7, wherein the optical film is a film containing at least one selected from the group consisting of a polarizing film and a retardation film. A method for producing a pressure-sensitive adhesive sheet according to any one of claims 1 to 6, comprising:
The manufacturing method includes:
Step A of irradiating a laminate including a base sheet, a coating layer containing the adhesive composition, and a release liner in this order with light to form the adhesive sheet having a thickness of 5 to 100 μm from the coating layer; ,
Step B of peeling off the release liner from the adhesive sheet;
including;
A method for producing a pressure-sensitive adhesive sheet, which comprises repeatedly carrying out the step A and the step B using the release liner peeled off in the step B to reuse the release liner. A method for producing an optical film with a pressure-sensitive adhesive sheet, comprising laminating an optical film and a pressure-sensitive adhesive sheet formed by the production method according to claim 9 to form an optical film with a pressure-sensitive adhesive sheet.

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