Adhesive composition and adhesive sheet

Abstract

Provided is an adhesive composition for producing an adhesive sheet suitable for reducing the amount of cutin peeling when peeled from the skin. This adhesive composition contains a (meth) acrylic polymer, a nonionic emulsifier, and an organic liquid component containing a carboxylic acid ester. The (meth) acrylic polymer includes a structural unit U1 derived from a first alkyl (meth) acrylate having an alkyl group having 1-7 carbon atoms, a structural unit U2 derived from a second alkyl (meth) acrylate having an alkyl group having 8-12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer.

Description

Technical Field

[0001] The present invention relates to an adhesive composition and an adhesive sheet. Background Art

[0002] As an example of an adhesive sheet, medical adhesive sheets are known for use on the skin, etc. Medical adhesive sheets are used for purposes such as protecting affected areas, promoting transdermal absorption of drugs, and securing gauze and catheters. Such adhesive sheets typically include an adhesive layer, which allows the sheet to be adhered to the skin, etc., via the adhesive layer.

[0003] The PSA layer of the PSA sheet can be formed by curing a PSA composition containing a polymer. For example, Patent Document 1 discloses an emulsion-type acrylic PSA containing a (meth)acrylic polymer as a material for the PSA layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4763416 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] When peeling a PSA sheet from the skin, the PSA sheet tends to remove keratin from the skin, causing damage to the skin. PSA sheets made using existing PSA compositions have room for improvement in the amount of keratin removed when peeling from the skin.

[0009] An object of the present invention is to provide a PSA composition suitable for producing a PSA sheet that reduces the amount of keratin removed when peeled from the skin.

[0010] Solutions to the Problem

[0011] The present invention provides an adhesive composition comprising a (meth)acrylic polymer, a nonionic emulsifier, and an organic liquid component containing a carboxylic acid ester. The (meth)acrylic polymer comprises a structural unit U1 derived from a first (meth)acrylic acid alkyl ester having an alkyl group with 1 to 7 carbon atoms, a structural unit U2 derived from a second (meth)acrylic acid alkyl ester having an alkyl group with 8 to 12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer.

[0012] Furthermore, the present invention provides a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition described above.

[0013] Effects of the Invention

[0014] According to the present invention, a PSA composition suitable for producing a PSA sheet that reduces the amount of keratin removed when peeled from the skin can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a cross-sectional view schematically showing a pressure-sensitive adhesive sheet according to one embodiment of the present invention.

[0016] Figure 2 This is a diagram for explaining a test for measuring the moisture permeability of an adhesive layer.

[0017] Explanation of symbols

[0018] 1 Adhesive layer

[0019] 2. Substrate

[0020] 3 Release liner

[0021] 10 adhesive sheet DETAILED DESCRIPTION

[0022] The first embodiment of the present invention comprises a pressure-sensitive adhesive composition comprising a (meth)acrylic polymer, a nonionic emulsifier, and an organic liquid component containing a carboxylic acid ester. The (meth)acrylic polymer comprises a structural unit U1 derived from a first alkyl (meth)acrylate having an alkyl group having 1 to 7 carbon atoms, a structural unit U2 derived from a second alkyl (meth)acrylate having an alkyl group having 8 to 12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer.

[0023] In the second aspect of the present invention, for example, in the pressure-sensitive adhesive composition of the first aspect, the amount of the organic liquid component blended is 40 to 80 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer.

[0024] In a third aspect of the present invention, for example, in the PSA composition of the first or second aspect, the organic liquid component includes tricaprylin.

[0025] In a fourth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to third aspects, the alkyl group of the second alkyl (meth)acrylate has 9 to 12 carbon atoms.

[0026] In a fifth aspect of the present invention, for example, in the adhesive composition according to any one of the first to fourth aspects, the second alkyl (meth)acrylate includes at least one selected from 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate.

[0027] In a sixth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fifth aspects, the alkyl group of the first alkyl (meth)acrylate has 1 to 5 carbon atoms.

[0028] In a seventh aspect of the present invention, for example, in the adhesive composition according to any one of the first to sixth aspects, the first alkyl (meth)acrylate includes at least one selected from n-butyl acrylate and isobutyl acrylate.

[0029] In an eighth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to seventh aspects, the carboxyl group-containing monomer includes acrylic acid.

[0030] In a ninth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to eighth aspects, the content of the structural unit U3 in the (meth)acrylic polymer is 2 to 4% by weight.

[0031] In a tenth aspect of the present invention, for example, the pressure-sensitive adhesive composition according to any one of the first to ninth aspects further comprises an anionic emulsifier.

[0032] In the eleventh aspect of the present invention, for example, in the pressure-sensitive adhesive composition of the tenth aspect, at least one selected from the anionic emulsifier and the nonionic emulsifier has a polymerizable group.

[0033] In the twelfth aspect of the present invention, for example, in the PSA composition of the tenth or eleventh aspect, at least one selected from the anionic emulsifier and the nonionic emulsifier has an oxyethylene group, and the average number of added moles of the oxyethylene group is 10 or more.

[0034] In a 13th aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the 10th to 12th aspects, the anionic emulsifier includes an alkyl sulfate salt.

[0035] In a fourteenth aspect of the present invention, for example, in the PSA composition according to any one of the tenth to thirteenth aspects, the anionic emulsifier is contained in an amount of 1 part by weight or more per 100 parts by weight of the (meth)acrylic polymer.

[0036] In a fifteenth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fourteenth aspects, the nonionic emulsifier includes polyoxyethylene-1-(allyloxymethyl)alkyl ether.

[0037] In a sixteenth aspect of the present invention, for example, in the PSA composition according to any one of the first to fifteenth aspects, the nonionic emulsifier is contained in an amount of 3 parts by weight or more per 100 parts by weight of the (meth)acrylic polymer.

[0038] The adhesive sheet according to the seventeenth aspect of the present invention includes an adhesive layer formed from the adhesive composition according to any one of the first to sixteenth aspects.

[0039] Hereinafter, the present invention will be described in detail. However, the following description is not intended to limit the present invention to specific embodiments.

[0040] <Embodiments of Adhesive Composition>

[0041] The adhesive composition of this embodiment includes a (meth)acrylic polymer, a nonionic emulsifier, and an organic liquid component. The (meth)acrylic polymer includes a structural unit U1 derived from a first alkyl (meth)acrylate having an alkyl group with 1 to 7 carbon atoms, a structural unit U2 derived from a second alkyl (meth)acrylate having an alkyl group with 8 to 12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer. The organic liquid component includes a carboxylate. It should be noted that, in this specification, (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0042] According to the research conducted by the present inventors, a PSA sheet produced using a PSA composition comprising the above-mentioned components is suitable for reducing the amount of keratin removed when peeled from the skin.

[0043] The pressure-sensitive adhesive composition of the present embodiment may further contain an anionic emulsifier in addition to the above-mentioned components.

[0044] [(Meth)acrylic polymer]

[0045] In this embodiment, the (meth)acrylic polymer is preferably emulsified in the PSA composition. As one example, the PSA composition may contain water as a dispersion medium, and the (meth)acrylic polymer may be emulsified in the water. In this specification, a (meth)acrylic polymer emulsified in water may be referred to as a "water-dispersible polymer." A PSA composition containing an emulsified (meth)acrylic polymer may also be referred to as an "emulsion-type PSA composition."

[0046] The (meth) acrylic polymer may be emulsified in the adhesive composition and have the shape of particles. In other words, the adhesive composition may contain particles of the (meth) acrylic polymer. The particles of the (meth) acrylic polymer may exist in the adhesive composition as single particles (primary particles) without agglomeration, or may agglomerate to form aggregates in the adhesive composition. The particles may be core-shell type having a core and a shell covering the core.

[0047] As described above, the (meth)acrylic polymer is a copolymer containing structural units U1 to U3. Examples of the copolymer include random copolymers, block copolymers, and graft copolymers. The pressure-sensitive adhesive composition may contain two or more (meth)acrylic polymers.

[0048] As described above, the first alkyl (meth)acrylate has an alkyl group having 1 to 7 carbon atoms. In the first alkyl (meth)acrylate, the alkyl group preferably has 6 or less carbon atoms, can be 5 or less, and further can be 4 or less carbon atoms. The lower limit of the number of carbon atoms in the alkyl group can be 2 or more. The alkyl group preferably has 1 to 5 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0049] Examples of the first alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, and isoheptyl (meth)acrylate. The first alkyl (meth)acrylate preferably includes at least one selected from n-butyl acrylate and isobutyl acrylate, and more preferably includes n-butyl acrylate.

[0050] The content of the structural unit U1 derived from the first alkyl (meth)acrylate in the (meth)acrylic polymer is, for example, 20% by weight or more, 30% by weight or more, 40% by weight or more, or even 50% by weight or more. The upper limit of the content of the structural unit U1 is, for example, 95% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, or even 60% by weight or less.

[0051] As described above, the second alkyl (meth)acrylate has an alkyl group with 8 to 12 carbon atoms. In the second alkyl (meth)acrylate, the alkyl group preferably has 9 or more carbon atoms. The alkyl group may have 11 or less carbon atoms, or 10 or less carbon atoms. The alkyl group preferably has 9 to 12 carbon atoms.

[0052] Examples of the second alkyl (meth)acrylate include n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-undecyl (meth)acrylate, and n-dodecyl (meth)acrylate. The second alkyl (meth)acrylate preferably comprises at least one selected from 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate, and more preferably comprises isononyl acrylate.

[0053] The content of the structural unit U2 derived from the second alkyl (meth)acrylate in the (meth)acrylic polymer is, for example, 80% by weight or less, 70% by weight or less, 60% by weight or less, or even 50% by weight or less. The lower limit of the content of the structural unit U2 is, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, or even 40% by weight or more.

[0054] The (meth)acrylic polymer may contain a structural unit derived from a third alkyl (meth)acrylate having an alkyl group having 13 or more carbon atoms, but preferably does not contain such a structural unit.

[0055] In the (meth)acrylic polymer, the content of structural units derived from an alkyl (meth)acrylate is, for example, 50% by weight or greater, 60% by weight or greater, 70% by weight or greater, 80% by weight or greater, 90% by weight or greater, or even 95% by weight or greater. The upper limit of this content is not particularly limited, but is, for example, 99% by weight or less.

[0056] In the (meth)acrylic polymer, the structural unit U3 from the carboxyl group-containing monomer can contribute to the stabilization of the particles of the (meth)acrylic polymer in the adhesive composition. The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and containing polymerizable unsaturated double bonds such as a (meth)acryloyl group and a vinyl group. Examples of the carboxyl group-containing monomer include: (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, (meth)acryloyloxyethylsuccinic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. Preferably, the carboxyl group-containing monomer comprises acrylic acid.

[0057] The content of structural units U3 derived from carboxyl group-containing monomers in the (meth)acrylic polymer is, for example, 0.1% by weight or more, 1% by weight or more, 2% by weight or more, or even 3% by weight or more. The upper limit of the content of structural units U3 is, for example, 25% by weight or less, 20% by weight or less, 10% by weight or less, 7% by weight or less, or even 4% by weight or less. The content of structural units U3 is preferably 1 to 7% by weight, and more preferably 2 to 4% by weight.

[0058] The (meth) acrylic polymer preferably further comprises a structural unit U4 from a silane monomer. The silane monomer is a free radical polymerizable compound having a silicon atom, preferably a silane compound having a (meth) acryloyl group. It is further preferred that the silane monomer has an alkoxysilyl group. As the silane monomer, there can be mentioned: 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 10-(meth)acryloyloxydecyltrimethoxysilane, 10-(meth)acryloyloxydecyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, etc.

[0059] Silane monomers, for example, hydrolyze during emulsification and / or emulsion polymerization in the presence of water to form silanol groups (-SiOH). That is, when a (meth)acrylic polymer is synthesized using a silane monomer in the presence of water, the structural unit U4 derived from the silane monomer, for example, has a silanol group. In this case, when the adhesive layer is made from the adhesive composition, a condensation reaction occurs between the silanol groups, thereby crosslinking the (meth)acrylic polymer (silanol crosslinking). According to this method, a structure in which multiple (meth)acrylic polymer particles are crosslinked with each other is formed in the adhesive layer.

[0060] In the (meth)acrylic polymer, the content of the structural unit U4 derived from the silane monomer is, for example, 0.01% by weight or more. The upper limit of this content is, for example, 10% by weight or less, and may be 1% by weight or less, 0.1% by weight or less, or further 0.05% by weight or less.

[0061] The (meth)acrylic polymer may further contain or not contain structural units derived from other monomers that can be copolymerized with the alkyl (meth)acrylate. Other monomers may be sulfonyl group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, and acrylamidomethylpropanesulfonic acid; hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; amide group-containing monomers such as (meth)acrylamide, dimethyl (meth)acrylamide, N-butylacrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxymethylpropane (meth)acrylamide; alkylaminoalkyl (meth)acrylates such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate; methoxyethyl (meth)acrylate, and (meth)acrylic acid. (Meth)acrylates containing alkoxy groups (or containing ether bonds in the side chains) such as ethoxyethyl (meth)acrylate; (meth)acrylates containing alkoxy groups (or containing ether bonds in the side chains) such as methoxyethyl (meth)acrylate; (meth)acrylates containing methoxyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; (meth)acrylonitrile, vinyl acetate, vinyl propionate, N-vinyl-2-pyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidine, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylcaprolactam, vinyl vinyl monomers such as oxazole and vinylmorpholine. The other monomers may be one type or two or more types.

[0062] In the (meth)acrylic polymer, the content of structural units derived from other monomers may be, for example, greater than 0% by weight, but may be 0.1% to 50% by weight, 1% to 30% by weight, 2% to 20% by weight, or further 3% to 10% by weight.

[0063] The glass transition temperature (Tg) of the (meth)acrylic polymer is, as a theoretically calculated value obtained by the FOX equation, for example, -10°C to 30°C, -5°C to 20°C, 0°C to 15°C, or even 5°C to 10°C.

[0064] The weight average molecular weight of the (meth)acrylic polymer is, for example, 1,000 to 10,000,000, 5,000 to 5,000,000, 10,000 to 1,000,000, or even 50,000 to 800,000. The weight average molecular weight of the (meth)acrylic polymer can be controlled by adjusting the amount of the polymerization initiator, chain transfer agent, emulsifier, etc. used during polymerization, the reaction conditions, and the like.

[0065] (Meth) acrylic polymers can be synthesized, for example, by emulsion polymerization using an emulsion of a monomer group as a raw material. In the emulsion polymerization, an emulsifier (surfactant), a polymerization initiator, a chain transfer agent as needed, etc. can be appropriately used. As methods of emulsion polymerization, a one-time feeding method (one-time polymerization method), a monomer dropping method, a monomer emulsion dropping method, etc. can be mentioned. In the monomer dropping method, a continuous dropping method or a batch dropping method can be appropriately used. These methods can be appropriately combined. The reaction conditions of the emulsion polymerization can be appropriately adjusted according to the monomer group, etc. As an example, the polymerization temperature is 20°C to 100°C, and the polymerization time is 30 minutes to 24 hours.

[0066] In emulsion polymerization, anionic emulsifiers, nonionic emulsifiers, and the like are preferably used as emulsifiers. As an example, the anionic emulsifiers and nonionic emulsifiers contained in the adhesive composition of this embodiment correspond to the emulsifiers used in emulsion polymerization. Details of emulsifiers will be described later.

[0067] Examples of the polymerization initiator include azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, tert-butyl hydroperoxide, and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; aromatic carbonyl compounds; and redox initiators such as a combination of a persulfate and sodium bisulfite and a combination of a peroxide and sodium ascorbate. Azo initiators are preferred. The amount of the polymerization initiator used is, for example, 0.005 to 1 part by weight relative to 100 parts by weight of the (meth)acrylic polymer (or a monomer group for synthesizing the (meth)acrylic polymer).

[0068] Examples of the chain transfer agent include mercaptans such as dodecanethiol. The amount of the chain transfer agent used is, for example, 0.001 to 0.5 parts by weight, 0.01 to 0.4 parts by weight, or even 0.01 to 0.04 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer (or the monomer group used to synthesize the (meth)acrylic polymer).

[0069] The dispersion medium used in the emulsion polymerization preferably contains water. The dispersion medium may contain an organic solvent in addition to water. The amount of the dispersion medium used is, for example, 30 to 80 parts by weight, or 40 to 70 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer (or the monomer group used to synthesize the (meth)acrylic polymer).

[0070] It should be noted that the (meth)acrylic polymer can also be synthesized by methods other than emulsion polymerization. In this case, the synthesized (meth)acrylic polymer can be dispersed in a dispersion medium using an emulsifier (anionic emulsifier, nonionic emulsifier) ​​to prepare a pressure-sensitive adhesive composition.

[0071] The content of the (meth)acrylic polymer in the pressure-sensitive adhesive composition is not particularly limited, and is, for example, 10% by weight to 90% by weight.

[0072] In the adhesive composition, the average particle size of the particles of the (meth) acrylic polymer is, for example, less than 1000 nm, can be less than 700 nm, less than 500 nm, less than 400 nm, less than 300 nm, and further can be less than 200 nm. When the average particle size of the particles of the (meth) acrylic polymer is less than 300 nm, there is a tendency that the compatibility of the (meth) acrylic polymer with the organic liquid component becomes good. The lower limit of the average particle size of the particles of the (meth) acrylic polymer is not particularly limited, for example, it is more than 50 nm, and can be more than 100 nm. In this specification, "average particle size" refers to the average particle size (volume average particle size) of the volume basis measured by the dynamic light scattering method. It should be noted that the average particle size of the particles of the (meth) acrylic polymer can be adjusted by the reaction conditions during the synthesis of the (meth) acrylic polymer.

[0073] [Anionic emulsifiers and nonionic emulsifiers]

[0074] Anionic emulsifiers and nonionic emulsifiers, for example, are components that emulsify (meth)acrylic polymers in adhesive compositions. Nonionic emulsifiers also tend to function as components that adjust the surface hardness of the adhesive layer. As described above, anionic emulsifiers and nonionic emulsifiers can be emulsifiers used during emulsion polymerization to synthesize (meth)acrylic polymers. These emulsifiers can also be added after the synthesis of the (meth)acrylic polymer.

[0075] At least one selected from anionic emulsifiers and nonionic emulsifiers may have a polymerizable group. As polymerizable groups contained in the emulsifier, groups containing polymerizable unsaturated double bonds such as (meth)acryloyl and vinyl groups can be cited. Emulsifiers containing polymerizable groups can function as monomers during emulsion polymerization for synthesizing (meth)acrylic polymers. As an example, an emulsifier that functions as a monomer is copolymerized with (meth)acrylic acid alkyl esters and the like during emulsion polymerization and introduced into a (meth)acrylic polymer. As such, in the adhesive composition of this embodiment, at least one of anionic emulsifiers and nonionic emulsifiers can be introduced into a (meth)acrylic polymer. In other words, in the adhesive composition of this embodiment, the (meth)acrylic polymer may further contain structural units from at least one of anionic emulsifiers and nonionic emulsifiers. In this specification, the emulsifier introduced into a (meth)acrylic polymer is also considered a component of the adhesive composition.

[0076] At least one selected from the anionic emulsifier and the nonionic emulsifier may contain an oxyethylene group. In this case, the average number of moles of oxyethylene added to the emulsifier is, for example, 5 or more, or 10 or more. The upper and lower limits of the average number of moles of oxyethylene added are not particularly limited, but are preferably 20 or more and 50 or less.

[0077] As anionic emulsifiers, sulfate salts, sulfonate salts, etc. can be mentioned. As sulfate salts, alkyl sulfate salts such as sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl ether ammonium sulfate, polyoxyethylene alkylphenyl ether ammonium sulfate, and polyoxyethylene alkylphenyl ether sodium sulfate can be mentioned. As sulfonate salts, sodium dodecylbenzenesulfonate, etc. can be mentioned. It should be noted that the above-mentioned compounds can also have arbitrary substituents. As an example, polyoxyethylene alkyl ether ammonium sulfate can have an allyloxymethyl group, and can be polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate. Anionic emulsifiers preferably include alkyl sulfate salts.

[0078] As nonionic emulsifiers, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, etc. can be mentioned. It should be noted that the above-mentioned compounds can also have arbitrary substituents. As an example, polyoxyethylene alkyl ethers can have an allyloxymethyl group, such as polyoxyethylene-1-(allyloxymethyl)alkyl ether. Nonionic emulsifiers particularly preferably contain polyoxyethylene-1-(allyloxymethyl)alkyl ether.

[0079] The amount of the anionic emulsifier blended per 100 parts by weight of the (meth)acrylic polymer (or the monomer group used to synthesize the (meth)acrylic polymer) is, for example, 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 0.8 parts by weight or more, or even 1 part by weight or more. The upper limit of the amount of the anionic emulsifier blended per 100 parts by weight of the (meth)acrylic polymer is, for example, 10 parts by weight or less, 5 parts by weight or less, or even 3 parts by weight or less. The adhesive composition may not contain an anionic emulsifier.

[0080] The amount of the nonionic emulsifier blended per 100 parts by weight of the (meth)acrylic polymer (or the monomer group used to synthesize the (meth)acrylic polymer) is, for example, 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 0.8 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, and further, 3 parts by weight or more. The upper limit of the amount of the nonionic emulsifier blended per 100 parts by weight of the (meth)acrylic polymer is, for example, 10 parts by weight or less, and further, 5 parts by weight or less.

[0081] [Organic liquid ingredients]

[0082] As described above, the adhesive composition of the present embodiment includes an organic liquid component. According to the organic liquid component, there is a tendency to reduce the modulus of the adhesive layer in the low deformation zone, maintain good adhesion relative to the skin, reduce keratin damage during peeling, and also reduce pain during peeling. In particular, by combining the organic liquid component with a (meth) acrylic polymer and a nonionic emulsifier, there is a tendency to significantly reduce the amount of keratin peeled when the adhesive layer is peeled from the skin. The organic liquid component is also suitable for improving the moisture permeability of the adhesive layer formed by the adhesive composition comprising a (meth) acrylic polymer.

[0083] The organic liquid component is a component that is liquid at room temperature (25°C) and is preferably compatible with the (meth)acrylic polymer. It should be noted that "compatible" means that the organic liquid component dissolves uniformly in the adhesive composition and is incorporated into the (meth)acrylic polymer, with no visible separation observed. Preferably, when a PSA sheet having an adhesive layer is used, the organic liquid component is unlikely to migrate from the PSA sheet to medical devices, medical equipment, etc.

[0084] As described above, the organic liquid component contains carboxylic acid ester. Carboxylic acid ester preferably does not contain any functional group other than an ester group (e.g., a thiol group). The carboxylic acid constituting the carboxylic acid ester may be a monobasic acid or a polybasic acid. The carboxylic acid may be a saturated fatty acid or an unsaturated fatty acid. The carboxylic acid may be linear or branched. The number of carbon atoms in the carboxylic acid is not particularly limited, and may be, for example, 1 to 18, 5 to 18, or even 8 to 18. Examples of the carboxylic acid include myristic acid, myristoleic acid, palmitic acid, isopalmitic acid, stearic acid, isostearic acid, lauric acid, caprylic acid, capric acid, lactic acid, phthalic acid, oleic acid, dimethyloctanoic acid, 2-ethylhexanoic acid, succinic acid, adipic acid, sebacic acid, trimellitic acid, linoleic acid, and linolenic acid.

[0085] The alcohol constituting the carboxylic acid ester may be a monohydric alcohol or a polyhydric alcohol. The valence of the polyhydric alcohol is, for example, 2 to 4. The alcohol may be linear or branched. The number of carbon atoms in the alcohol is not particularly limited, and may be, for example, 1 to 18, 1 to 10, or 1 to 5. Examples of the alcohol include ethanol, isopropyl alcohol, butanol, hexanol, octanol, myristyl alcohol, cetyl alcohol, isocetyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, hexyldecanol, octyldodecanol, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.

[0086] Specific examples of carboxylic acid esters include ethyl myristate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isopropyl palmitate, isostearyl palmitate, butyl stearate, isocetyl stearate, isostearyl isostearate, hexyl laurate, isostearyl laurate, cetyl lactate, myristyl lactate, diethyl phthalate, octyldodecyl oleate, hexyldecyl dimethyl octanoate, cetyl 2-ethylhexanoate, isocetyl 2-ethylhexanoate. Wax esters, stearyl 2-ethylhexanoate, dioctyl succinate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitate, triisocetyl trimellitate, propylene glycol dicaprylate, propylene glycol dicaprate, propylene glycol diisostearate, glyceryl monocaprylate, tricaprylate, glyceryl tri-2-ethylhexanoate, tricaprate, glyceryl trilaurate, glyceryl triisostearate, glyceryl trioleate, trimethylolpropane tri-2-ethylhexanoate, sorbitan trioleate, etc. The organic liquid component preferably contains tricaprylic acid glyceryl as the carboxylic acid ester.

[0087] The amount of the organic liquid component added relative to 100 parts by weight of the (meth) acrylic polymer is, for example, 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, and further 70 parts by weight or more. The greater the amount of the organic liquid component added, the more the moisture permeability of the adhesive layer tends to improve. From the perspective of fully ensuring the adhesive force of the adhesive layer, the upper limit of the amount of the organic liquid component added relative to 100 parts by weight of the (meth) acrylic polymer is, for example, 120 parts by weight or less, 100 parts by weight or less, and further 80 parts by weight or less. The amount of the organic liquid component added relative to 100 parts by weight of the (meth) acrylic polymer is preferably 30 to 80 parts by weight, and more preferably 40 to 80 parts by weight.

[0088] [Dispersion medium]

[0089] The adhesive composition may further contain a dispersion medium. It is particularly preferred that the adhesive composition contain water as a dispersion medium. The adhesive composition is typically an oil-in-water (O / W) emulsion. According to the adhesive composition containing water as a dispersion medium, the discharge amount of the organic solvent removed by heating can be greatly reduced when the adhesive layer is produced. As a result, not only can the fuel required to burn the organic solvent removed by heating in a deodorizing furnace, etc. be reduced, but the discharge amount of CO2 generated by the combustion of the organic solvent can also be reduced. However, it should be noted that the adhesive composition may also contain an organic solvent as a dispersion medium in addition to water. The content of the dispersion medium in the adhesive composition is not particularly limited, and is, for example, 10% to 90% by weight.

[0090] [additive]

[0091] The adhesive composition may further contain additives other than those mentioned above. Examples of the additives include crosslinking agents, tackifiers, thickeners, plasticizers, softeners, fillers, pigments, and the like.

[0092] [Physical Properties of Adhesive Composition]

[0093] The adhesive composition is preferably neutral. Neutral adhesive compositions tend to have a high stability due to the (meth)acrylic polymer particles being less likely to aggregate. The pH of the adhesive composition is, for example, 6.0 to 8.0, or 6.5 to 7.5. The pH of the adhesive composition is preferably 7.0.

[0094] The viscosity of the adhesive composition at pH 7.0 and a temperature of 25°C is, for example, 500 mPa·s or less, 300 mPa·s or less, or even 100 mPa·s or less. An adhesive composition having a viscosity of 500 mPa·s or less is considered to have sufficient coatability for practical use. The lower limit of the viscosity of the adhesive composition is, for example, 10 mPa·s or greater.

[0095] <Embodiments of Pressure-Sensitive Adhesive Sheet>

[0096] like Figure 1 As shown, the adhesive sheet 10 of this embodiment includes an adhesive layer 1. The adhesive layer 1 is formed from the above-mentioned adhesive composition, and more specifically, is a cured product of the adhesive composition. It should be noted that in this specification, the term "adhesive sheet" is used as a term including "adhesive tape."

[0097] The adhesive sheet 10 may further include a substrate 2 supporting the adhesive layer 1 and a release liner 3 disposed on the surface of the adhesive layer 1. The adhesive layer 1 is, for example, located between the substrate 2 and the release liner 3, and is in direct contact with the substrate 2 and the release liner 3, respectively. As an example, the adhesive sheet 10 can be used by sticking the adhesive layer 1 to an object (e.g., skin) after peeling off the release liner 3. It should be noted that the adhesive sheet 10 is not limited to the above-mentioned structure. For example, the adhesive sheet 10 may consist only of the adhesive layer 1. In addition, the adhesive sheet 10 may include two adhesive layers 1 and two release liners 3, for example, it may have a structure in which a release liner 3, an adhesive layer 1, a substrate 2, an adhesive layer 1, and a release liner 3 are sequentially stacked.

[0098] [Adhesive layer]

[0099] The thickness of the adhesive layer 1 is not particularly limited, and is, for example, 10 to 80 μm.

[0100] The gel fraction of the pressure-sensitive adhesive layer 1 is, for example, 20% to 80%, or may be 40% to 80%.

[0101] In this embodiment, the moisture permeability P of the adhesive layer 1 determined by the following test is preferably 800 g / (m 2 ·24h) or more.

[0102] Test: A laminate consisting of a 30 μm thick adhesive layer 1 and a 30 μm thick polyurethane film was prepared. The laminate was attached to a glass container containing water so as to seal the opening of the glass container. The glass container was left at a temperature of 40°C and a humidity of 30% RH for 24 hours, and the weight of water that permeated the laminate from the interior of the glass container was determined. This weight (g) was calculated relative to the opening area (m2) of the opening. 2 ) is determined as the moisture permeability P.

[0103] Below, refer to Figure 2 The detailed method for measuring the moisture permeability P of the adhesive layer 1 is described. First, an adhesive layer 1 having a thickness of 25 μm and the same composition as that of the adhesive layer 1 is formed on a release liner to produce a laminate of the release liner and the adhesive layer 1. The adhesive layer 1 can be produced by the method described below. Next, the surface of the adhesive layer 1 of the obtained laminate is entirely superimposed on a polyurethane film 5 (thickness 30 μm), and a 2 kg roller is reciprocated once to press them together. As the polyurethane film 5, a polyurethane film having a sufficiently high moisture permeability compared to the adhesive layer 1 and having almost no effect on the value of the moisture permeability P is used. Next, a laminate 20 consisting of the adhesive layer 1 and the polyurethane film 5 is produced by peeling the release liner from the adhesive layer 1. As needed, the laminate 20 is cut and its shape and size are adjusted. As an example, the laminate 20 is adjusted to have a circular shape when viewed from above and its diameter is 50 mm.

[0104] Next, a glass container 30 containing water (distilled water) 35 is prepared. The glass container 30 has an opening 31 and is, for example, a bottomed cylindrical shape with an inner diameter of 40 mm and a height of 40 mm. The volume of water 35 contained in the glass container 30 is, for example, 10 mL. Next, the laminate 20 is attached to the glass container 30 ( Figure 2 Specifically, the adhesive layer 1 of the laminate 20 is attached to the end surface of the glass container 30 to seal the interior of the glass container 30. The object to be measured 50 is thus obtained.

[0105] Next, the glass container 30 (more specifically, the object to be measured 50) is placed in a commercially available constant temperature and humidity machine and left for 24 hours at a temperature of 40°C and a humidity of 30% RH. At this time, a portion of the water 35 vaporizes and permeates the laminate 20, being released from the inside of the glass container 30 to the outside. The value (W1-W2) obtained by subtracting the weight W2 (g) of the object to be measured 50 after being left for 24 hours from the weight W1 (g) of the object to be measured 50 immediately after production is determined as the weight W (g) of water (more specifically, water vapor) that has permeated the laminate 20 from the inside of the glass container 30. The weight W (g) of the water that has permeated the laminate 20 can be calculated relative to the opening area A (m2) of the opening 31 of the glass container 30. 2 ) is determined as the moisture permeability P. It should be noted that the opening area A (m 2 ) For example, the inner diameter r (m) of the glass container 30 can be calculated by the formula (r / 2) 2 ×π and perform calculations.

[0106] The moisture permeability P of the adhesive layer 1 is preferably 900 g / (m 2 ·24h) above, can be 930g / (m2 24h) or more, 950g / (m 2 24h) or more, 980g / (m 2 24h) or more, 1000g / (m 2 24h) or more, 1100g / (m 2 24h) or more, 1200g / (m 2 24h) or more, 1300g / (m 2 ·24h) or more, and can be further 1400g / (m 2 The upper limit of the moisture permeability P is not particularly limited, and is, for example, 5000 g / (m 2 ·24h) or less, can be 3000g / (m 2 ·24h) or less.

[0107] [Base material]

[0108] The substrate 2 is, for example, a layered member that supports the adhesive layer 1. The substrate 2 may be a single layer or a laminate having multiple layers. From the perspective of suppressing the stuffiness of the skin when the adhesive sheet 10 is applied to the skin, the substrate 2 preferably has a sufficiently higher moisture permeability than the adhesive layer 1.

[0109] The substrate 2 may be non-porous or porous. If the substrate 2 is porous, the moisture permeability tends to be less likely to decrease even if the substrate 2 is thick. The porous substrate 2 is preferably water vapor permeable, allowing water vapor to pass through, but is also substantially water impermeable, preventing liquid water from passing through.

[0110] Examples of materials for the substrate 2 include: urethane polymers such as polyether urethane and polyester urethane; amide polymers such as polyether polyamide block polymers; acrylic polymers such as polyacrylates; polyolefin polymers such as polyethylene, polypropylene, and ethylene / vinyl acetate copolymers; and polyester polymers such as polyether polyesters. From the perspective of moisture permeability, the substrate 2 preferably comprises a urethane polymer or an amide polymer, with a urethane polymer being particularly preferred. For example, the substrate 2 may be a polyurethane film composed of a urethane polymer, or a laminate comprising a polyolefin polymer laminated on a polyurethane film.

[0111] The thickness of the substrate 2 is not particularly limited, and is, for example, 10 to 100 μm, or 20 to 40 μm.

[0112] From the viewpoint of the followability when the pressure-sensitive adhesive sheet 10 is applied to the skin, the tensile strength of the substrate 2 is preferably 100 to 900 kg / cm 2 , 100% modulus is 10~100kg / cm2 .

[0113] [Release liner]

[0114] As the release liner 3, a known release liner can be used as appropriate. The release liner 3 comprises, for example, a backing substrate and a release layer formed on one side of the backing substrate. Examples of the material for the backing substrate include the materials described above for the substrate 2. The release layer can be formed by applying a release agent to the surface of the backing substrate. Examples of the release agent include silicone-based release agents, long-chain alkyl-based release agents, fluorine-based release agents, and molybdenum sulfide-based release agents.

[0115] The thickness of the release liner 3 is not particularly limited, and may be, for example, 5 to 100 μm, or 10 to 50 μm.

[0116] [Method for producing adhesive sheet]

[0117] The adhesive sheet 10 of this embodiment can be manufactured, for example, by the following method. First, the adhesive composition described above is applied to the release liner 3 to form a coating film. The adhesive composition application method is not particularly limited, and examples thereof include spin coating and dip coating. Alternatively, the adhesive composition can be applied using a wire rod or the like.

[0118] Next, the coating film is dried to form the adhesive layer 1. The coating film can be dried, for example, under heating conditions. The heating temperature of the coating film is, for example, 50°C or higher, or 100°C or higher. The heating time of the coating film is, for example, 1 minute or longer.

[0119] Next, the substrate 2 is bonded to the pressure-sensitive adhesive layer 1. In this manner, the pressure-sensitive adhesive sheet 10 can be produced.

[0120] [Properties of adhesive sheets]

[0121] The adhesive sheet 10 of this embodiment tends to be able to be adhered to an object (particularly skin) with sufficient strength via the adhesive layer 1. As an example, the adhesive force F of the adhesive sheet 10 to a Bakelite board is preferably 0.1 N / 10 mm or greater.

[0122] The above-mentioned adhesive force F can be measured by the following method. First, the adhesive sheet 10 to be evaluated is cut into 100 mm in length and 10 mm in width to prepare a test piece. Next, the release liner 3 is removed from the test piece to expose the surface of the adhesive layer 1. The surface of the adhesive layer 1 is superimposed on the bakelite board as a whole, and a 2 kg roller is reciprocated once to press them together. Next, a commercially available tensile testing machine is used to peel the test piece from the bakelite board at a peeling speed of 300 mm / min and a peeling angle of 180°. At this time, the force required to peel the test piece from the bakelite board is measured at intervals of 1 time / 0.5s at a location where the numerical value is relatively stable. The average value of the measured values ​​obtained is determined as the adhesive force F. It should be noted that the above-mentioned test was carried out in an atmosphere of 23°C.

[0123] The adhesive force F is preferably 0.3 N / 10 mm or more, and may be 0.5 N / 10 mm or more. The upper limit of the adhesive force F is, for example, 5.0 N / 10 mm or less, and may be 4.0 N / 10 mm or less, 3.0 N / 10 mm or less, 2.0 N / 10 mm or less, and further may be 1.0 N / 10 mm or less.

[0124] [Applications of adhesive sheets]

[0125] The adhesive sheet 10 of this embodiment is typically a medical adhesive sheet. Specifically, the adhesive sheet 10 can be used for adhesive bandages, surgical tape, emergency bandages, large bandages, dressings, pastes, drapes, and the like. The adhesive sheet 10 can also be used as a percutaneous absorption preparation by loading a pharmaceutical agent onto the adhesive layer 1. It should be noted that the adhesive sheet 10 can also be used for purposes other than medical applications.

[0126] Example

[0127] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0128] (Example 1)

[0129] In a container, 47 parts by weight of isononyl acrylate (iNA), 50 parts by weight of butyl acrylate (BA), 3 parts by weight of acrylic acid (AA), 0.03 parts by weight of 3-methacryloyloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Silicone Co., Ltd.), 0.02 parts by weight of 1-dodecanethiol (1-LSH) as a chain transfer agent, 0.96 parts by weight of polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate (Aqualon KH-10, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as an anionic emulsifier, 3.84 parts by weight of polyoxyethylene-1-(allyloxymethyl)alkyl ether (Aqualon KN-30, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as a nonionic emulsifier, and 52.68 parts by weight of water were added and stirred using a homomixer to emulsify the monomer components. Thus, a monomer emulsion was obtained.

[0130] In a reaction vessel (separable flask) equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer, 3.62 parts by weight of the above-mentioned monomer emulsion, 0.04 parts by weight of polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate, 0.16 parts by weight of polyoxyethylene-1-(allyloxymethyl) alkyl ether, and 50.47 parts by weight of water were added, and stirred for 1 hour while introducing an inert gas. Next, 0.1 parts by weight of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate was added as a polymerization initiator, and the mixture was reacted at 60°C for 40 minutes. Furthermore, 177.81 parts by weight of the above-mentioned monomer emulsion was added dropwise over 3 hours, and the mixture was further aged for 3 hours. Thus, a dispersion containing a (meth)acrylic polymer was obtained.

[0131] Next, 4.73 parts by weight of 10% aqueous ammonia was added to the dispersion to neutralize the dispersion and adjust its pH to approximately 7. Furthermore, 0.6 parts by weight of a thickener (ARON B-500, manufactured by Toagosei Co., Ltd.) and 60 parts by weight of tricaprylin (COCONARD RK, manufactured by Kao Corporation) as an organic liquid component were added to the dispersion to obtain the adhesive composition of Example 1.

[0132] (Examples 2 to 14 and Comparative Examples 1 to 5)

[0133] The adhesive compositions of Examples 2 to 14 and Comparative Examples 1 to 5 were obtained by the same method as in Example 1, except that the types and amounts of the materials used were changed as shown in Tables 1 and 2. Note that no organic liquid component was added in Comparative Examples 1 and 2. No nonionic emulsifier was added in Comparative Examples 3 to 5. The amount of emulsifier used in Tables 1 and 2 is the sum of the amount used to prepare the monomer emulsion and the amount added separately to the monomer emulsion.

[0134] [evaluate]

[0135] The adhesive compositions of the Examples and Comparative Examples were applied to a release liner (PET-50-SCA1, manufactured by Fujiko Co., Ltd.) to prepare a coating film. Subsequently, the coating film was dried at 130°C for 3 minutes to form an adhesive layer (30 μm thick). The adhesive layer was bonded to a substrate to obtain an adhesive sheet for evaluation. A polyurethane film (30 μm thick) (ESMER URS210, manufactured by Nihon Matai Co., Ltd.) was used as the substrate.

[0136] (Appearance changes)

[0137] Prepare a 10 mm x 50 mm PSA sheet for evaluation. Remove the release liner from the sheet. Place the exposed PSA layer on the subject's forearm and press it with a 2 kg roller. Leave the sheet in this state in an environment at 23°C and 50% RH for 6 hours. Changes in the appearance of the sheet after exposure were evaluated according to the following criteria.

[0138] Evaluation benchmark

[0139] ◯: No peeling was observed by visual observation.

[0140] ×: There is peeling at the edge.

[0141] (Amount of exfoliation)

[0142] Prepare a 10 mm x 50 mm adhesive sheet for evaluation and peel the release liner from the adhesive sheet. Place the exposed adhesive layer on the subject's forearm and press it with a 2 kg roller. After leaving the adhesive sheet in an environment of 23°C and 50% RH for 6 hours, peel it from the forearm. Peeling of the adhesive sheet was performed using a peel tester (Shimadzu Corporation, AGX-V) at a peel speed of 300 mm / min.

[0143] Next, the surface of the adhesive layer in the peeled evaluation adhesive sheet was stained with a keratin staining solution (Gentian Violet 1%, Brilliant Green 0.5% aqueous solution) for 10 minutes and then rinsed with water. The stained surface of the adhesive layer was observed using an optical microscope (Keyence VX-7000). In the microscope image, areas with keratin attached were identified, and the total area of ​​each area was calculated through image processing. The ratio of this total value to the surface area of ​​the adhesive layer in the microscope image was considered the amount of keratin peeling, and evaluation was performed according to the following criteria.

[0144] Evaluation benchmark

[0145] ◎: The amount of keratin peeling is less than 10%.

[0146] ○: The amount of keratin removal was 10% or more and less than 20%.

[0147] △: The amount of keratin peeling is 20% or more and less than 30%.

[0148] ×: The amount of keratin exfoliation was 30% or more.

[0149] (Moisture Permeability)

[0150] The moisture permeability P of the pressure-sensitive adhesive layer was measured using the pressure-sensitive adhesive sheet for evaluation by the above-mentioned method and evaluated according to the following criteria.

[0151] Evaluation benchmark

[0152] ◎: Moisture permeability P is 1200g / (m 2 ·24h) or more.

[0153] ○: Moisture permeability P is 1000g / (m 2 24h) and less than 1200g / (m 2 ·24h).

[0154] △: moisture permeability P is 800g / (m 2 24h) and less than 1000g / (m 2 ·24h).

[0155] ×: Moisture permeability P is 800g / (m 2 ·24h).

[0156]

[0157]

[0158] The abbreviations in Table 1 are as follows.

[0159] 2EHA: 2-ethylhexyl acrylate

[0160] nOcA: n-octyl acrylate

[0161] iNA: Isononyl acrylate

[0162] iDAA: Isodecyl Acrylate

[0163] LA: n-dodecyl acrylate

[0164] BA: n-butyl acrylate

[0165] iBA: Isobutyl acrylate

[0166] MMA: Methyl Methacrylate

[0167] AA: Acrylic acid

[0168] KBM-503: 3-methacryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., KBM-503)

[0169] 1-LSH: 1-dodecanethiol

[0170] KH-10: Polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KH-10)

[0171] SR-10: Polyoxyethylene alkyl ether ammonium sulfate (ADEKA REASOAP SR-10)

[0172] KN-30: Polyoxyethylene-1-(allyloxymethyl) alkyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KN-30)

[0173] ER-30: Allyloxypolyethylene (ADEKA, ADEKA REASOAP ER-30)

[0174] COCONARD RK: Glyceryl tricaprylate (manufactured by Kao Corporation, COCONARD RK)

[0175] As shown in Tables 1 and 2, the PSA sheets for evaluation produced using the PSA compositions of the Examples gave good results in the evaluation of the amount of keratin detachment compared to the Comparative Examples, indicating that they are suitable for reducing the amount of keratin detachment.

[0176] Industrial Applicability

[0177] The pressure-sensitive adhesive sheet produced using the pressure-sensitive adhesive composition of this embodiment can be adhered to an object such as skin and used.

Claims

1. A pressure-sensitive adhesive composition comprising a (meth)acrylic polymer, a nonionic emulsifier, and an organic liquid component containing a carboxylic acid ester, wherein the (meth)acrylic polymer comprises a structural unit U1 derived from a first alkyl (meth)acrylate having an alkyl group with 1 to 7 carbon atoms, a structural unit U2 derived from a second alkyl (meth)acrylate having an alkyl group with 8 to 12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer.

2. The adhesive composition according to claim 1, wherein The blending amount of the organic liquid component is 40 to 80 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer.

3. The adhesive composition according to claim 1, wherein The organic liquid component comprises tricaprylin.

4. The adhesive composition according to claim 1, wherein The number of carbon atoms of the alkyl group of the second alkyl (meth)acrylate is 9 to 12.

5. The adhesive composition according to claim 1, wherein The second alkyl (meth)acrylate includes at least one selected from 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate.

6. The adhesive composition according to claim 1, wherein The number of carbon atoms of the alkyl group of the first alkyl (meth)acrylate is 1 to 5.

7. The adhesive composition according to claim 1, wherein The first alkyl (meth)acrylate includes at least one selected from n-butyl acrylate and isobutyl acrylate.

8. The adhesive composition according to claim 1, wherein The carboxyl group-containing monomer includes acrylic acid.

9. The adhesive composition according to claim 1, wherein The content of the structural unit U3 in the (meth)acrylic polymer is 2 to 4% by weight. 10 . The adhesive composition according to claim 1 , further comprising an anionic emulsifier.

11. The adhesive composition according to claim 10, wherein At least one selected from the anionic emulsifier and the nonionic emulsifier has a polymerizable group.

12. The adhesive composition according to claim 10, wherein At least one selected from the anionic emulsifier and the nonionic emulsifier has an oxyethylene group, and the average number of added moles of the oxyethylene group is 10 or more.

13. The adhesive composition according to claim 10, wherein The anionic emulsifier includes an alkyl sulfate salt.

14. The adhesive composition according to claim 10, wherein The amount of the anionic emulsifier to be added is 1 part by weight or more relative to 100 parts by weight of the (meth)acrylic polymer.

15. The adhesive composition according to claim 1, wherein The nonionic emulsifier includes polyoxyethylene-1-(allyloxymethyl) alkyl ether.

16. The adhesive composition according to claim 1, wherein The nonionic emulsifier is added in an amount of 3 parts by weight or more based on 100 parts by weight of the (meth)acrylic polymer. 17 . A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1 .

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