Adhesive composition and adhesive sheet

Abstract

To provide an adhesive composition for producing an adhesive sheet suitable for reducing a keratin exfoliation amount when removed from a skin.SOLUTION: An adhesive composition includes: a (meth)acrylic polymer that has a constitutional unit U1 derived from a first (meth)acrylic acid alkyl ester having an alkyl group having 1 to 7 carbon atoms, a constitutional unit U2 derived from a second (meth)acrylic acid alkyl ester having an alkyl group having 8 to 12 carbon atoms and a constitutional unit U3 derived from a carboxyl group-containing monomer; a nonion-based emulsifier; and an organic liquid component including a carboxylate ester.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet. [Background technology]

[0002] A known example of an adhesive sheet is a medical adhesive sheet that is attached to the skin, etc. Medical adhesive sheets are used for purposes such as protecting affected areas, transdermal drug absorption, and fixing gauze or tubes. Such adhesive sheets usually have an adhesive layer, and can be attached to the skin, etc. via this adhesive layer.

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

[0004] [Patent Document 1] Patent No. 4763416 Summary of the Invention [Problem to be solved by the invention]

[0005] When an adhesive sheet is peeled off from the skin, the adhesive sheet tends to peel off keratin, which can damage the skin. Adhesive sheets made using conventional adhesive compositions have room for improvement in the amount of keratin peeled off when peeled off from the skin.

[0006] An object of the present invention is to provide a pressure-sensitive adhesive composition for producing a pressure-sensitive adhesive sheet suitable for reducing the amount of keratin peeled off when peeled from the skin. [Means for solving the problem]

[0007] The present invention provides a (meth)acrylic polymer including 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; A nonionic emulsifier, an organic liquid component containing a carboxylic acid ester; The present invention provides a pressure-sensitive adhesive composition comprising:

[0008] Furthermore, the present invention provides A pressure-sensitive adhesive sheet is provided, which comprises a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition for producing a pressure-sensitive adhesive sheet suitable for reducing the amount of keratin peeled off when peeled from the skin. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically showing a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating a test for measuring the moisture permeability of a pressure-sensitive adhesive layer. DETAILED DESCRIPTION OF THE INVENTION

[0011] The pressure-sensitive adhesive composition according to the first aspect of the present invention comprises: a (meth)acrylic polymer including 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; A nonionic emulsifier, an organic liquid component containing a carboxylic acid ester; Includes.

[0012] In the second aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to the first aspect, 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.

[0013] In a third aspect of the present invention, for example, in the PSA composition according to the first or second aspect, the organic liquid component contains glyceryl tricaprylate.

[0014] 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.

[0015] In a fifth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fourth aspects, the second (meth)acrylic acid alkyl ester comprises at least one selected from the group consisting of 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate.

[0016] 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 (meth)acrylic acid alkyl ester has 1 to 5 carbon atoms.

[0017] In a seventh aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to sixth aspects, the first (meth)acrylic acid alkyl ester includes at least one selected from the group consisting of n-butyl acrylate and isobutyl acrylate.

[0018] 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 comprises acrylic acid.

[0019] 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 wt %.

[0020] 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 contains an anionic emulsifier.

[0021] In an eleventh aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to the tenth aspect, at least one selected from the group consisting of the anionic emulsifier and the nonionic emulsifier has a polymerizable group.

[0022] In a twelfth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to the tenth or eleventh aspect, at least one selected from the group consisting of the anionic emulsifier and the nonionic emulsifier has an oxyethylene group, and the average number of moles of the oxyethylene group added is 10 or more.

[0023] In a thirteenth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the tenth to twelfth aspects, the anionic emulsifier comprises an alkyl sulfate ester salt.

[0024] In a fourteenth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the tenth to thirteenth aspects, the amount of the anionic emulsifier blended is 1 part by weight or more relative to 100 parts by weight of the (meth)acrylic polymer.

[0025] 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 comprises polyoxyethylene-1-(allyloxymethyl) alkyl ether.

[0026] In a sixteenth aspect of the present invention, for example, in the pressure-sensitive adhesive composition according to any one of the first to fifteenth aspects, the amount of the nonionic emulsifier blended is 3 parts by weight or more relative to 100 parts by weight of the (meth)acrylic polymer.

[0027] A pressure-sensitive adhesive sheet according to a seventeenth aspect of the present invention comprises a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of the first to sixteenth aspects.

[0028] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0029] <Embodiments of Pressure-Sensitive Adhesive Composition> The pressure-sensitive adhesive composition of the present embodiment contains a (meth)acrylic polymer, a nonionic emulsifier, and an organic liquid component. The (meth)acrylic polymer contains a structural unit U1 derived from a first (meth)acrylic acid alkyl ester having an alkyl group of 1 to 7 carbon atoms, a structural unit U2 derived from a second (meth)acrylic acid alkyl ester having an alkyl group of 8 to 12 carbon atoms, and a structural unit U3 derived from a carboxyl group-containing monomer. The organic liquid component contains a carboxylic acid ester. In this specification, (meth)acrylic means acrylic and / or methacrylic.

[0030] According to the investigations of the present inventors, a pressure-sensitive adhesive sheet produced using a pressure-sensitive adhesive composition that combines the above components is suitable for reducing the amount of keratin peeled off when peeled from the skin.

[0031] The pressure-sensitive adhesive composition of the present embodiment may further contain an anionic emulsifier in addition to the above components.

[0032] [(Meth)acrylic polymer] In the present embodiment, the (meth)acrylic polymer is preferably emulsified in the pressure-sensitive adhesive composition. As an example, the pressure-sensitive adhesive composition may contain water as a dispersion medium, and the (meth)acrylic polymer may be emulsified in this water. In this specification, a (meth)acrylic polymer emulsified in water may be referred to as a "water-dispersed polymer." A pressure-sensitive adhesive composition containing an emulsified (meth)acrylic polymer may be referred to as an "emulsion-based pressure-sensitive adhesive composition."

[0033] The (meth)acrylic polymer may be emulsified in the pressure-sensitive adhesive composition and may have a particulate form. In other words, the pressure-sensitive adhesive composition may contain particles of the (meth)acrylic polymer. The particles of the (meth)acrylic polymer may not aggregate in the pressure-sensitive adhesive composition but may exist as single particles (primary particles), or may aggregate in the pressure-sensitive adhesive composition to form aggregates. The particles may be of a core-shell type having a core and a shell covering the core.

[0034] As described above, the (meth)acrylic polymer is a copolymer containing structural units U1 to U3. Examples of the copolymer include a random copolymer, a block copolymer, and a graft copolymer. The pressure-sensitive adhesive composition may contain two or more types of (meth)acrylic polymers.

[0035] As described above, the first (meth)acrylic acid alkyl ester has an alkyl group having 1 to 7 carbon atoms. In the first (meth)acrylic acid alkyl ester, the number of carbon atoms in the alkyl group is preferably 6 or less, and may be 5 or less, or even 4 or less. The lower limit of the number of carbon atoms in the alkyl group may be 2 or more. The number of carbon atoms in the alkyl group is preferably 1 to 5, and more preferably 1 to 4.

[0036] Examples of the first (meth)acrylic acid alkyl ester 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, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, isoheptyl (meth)acrylate, etc. The first (meth)acrylic acid alkyl ester preferably contains at least one selected from the group consisting of n-butyl acrylate and isobutyl acrylate, and more preferably contains n-butyl acrylate.

[0037] The content of the structural unit U1 derived from the first (meth)acrylic acid alkyl ester in the (meth)acrylic polymer is, for example, 20% by weight or more, and may be 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, and may be 90% by weight or less, 80% by weight or less, 70% by weight or less, or even 60% by weight or less.

[0038] As described above, the second (meth)acrylic acid alkyl ester has an alkyl group having 8 to 12 carbon atoms. In the second (meth)acrylic acid alkyl ester, the number of carbon atoms in the alkyl group is preferably 9 or more. The number of carbon atoms in the alkyl group may be 11 or less, or may be 10 or less. The number of carbon atoms in the alkyl group is preferably 9 to 12.

[0039] Examples of the second (meth)acrylic acid alkyl ester 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, n-dodecyl (meth)acrylate, etc. The second (meth)acrylic acid alkyl ester preferably contains at least one selected from the group consisting of 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate, and more preferably contains isononyl acrylate.

[0040] 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, and may be 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, and may be 10% by weight or more, 20% by weight or more, 30% by weight or more, or even 40% by weight or more.

[0041] The (meth)acrylic polymer may contain a structural unit derived from a tertiary (meth)acrylic acid alkyl ester having an alkyl group having 13 or more carbon atoms, but it is preferable that the polymer does not contain this structural unit.

[0042] In the (meth)acrylic polymer, the content of structural units derived from (meth)acrylic acid alkyl ester is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or even 95% by weight or more. The upper limit of this content is not particularly limited, and is, for example, 99% by weight or less.

[0043] In the (meth)acrylic polymer, the structural unit U3 derived from a carboxyl group-containing monomer can contribute to stabilizing the particles of the (meth)acrylic polymer in the pressure-sensitive adhesive composition. The carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, (meth)acryloyloxyethyl succinate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The carboxyl group-containing monomer preferably contains acrylic acid.

[0044] The content of the structural unit U3 derived from a carboxyl group-containing monomer in the (meth)acrylic polymer is, for example, 0.1% by weight or more, and may be 1% by weight or more, 2% by weight or more, or even 3% by weight or more. The upper limit of the content of the structural unit U3 is, for example, 25% by weight or less, and may be 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 the structural unit U3 is preferably 1 to 7% by weight, and more preferably 2 to 4% by weight.

[0045] The (meth)acrylic polymer preferably further contains a structural unit U4 derived from a silane monomer. The silane monomer is a radically polymerizable compound having a silicon atom, and is preferably a silane compound having a (meth)acryloyl group. The silane monomer more preferably has an alkoxysilyl group. Examples of the silane monomer include 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, and 8-vinyloctyltriethoxysilane.

[0046] The silane monomer undergoes hydrolysis during emulsification and / or emulsion polymerization in the presence of water, for example, to form a silanol group (—SiOH). That is, when a (meth)acrylic polymer is synthesized using the silane monomer in the presence of water, the structural unit U4 derived from the silane monomer has, for example, a silanol group. In this case, when a pressure-sensitive adhesive layer is produced from the pressure-sensitive adhesive composition, the silanol groups undergo a condensation reaction with each other, resulting in crosslinking of 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 pressure-sensitive adhesive layer.

[0047] 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, and 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 even 0.05% by weight or less.

[0048] The (meth)acrylic polymer may or may not further contain structural units derived from other monomers copolymerizable with the (meth)acrylic acid alkyl ester. Examples of such other monomers include sulfoxyl group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, and acrylamidomethylpropanesulfonic acid; hydroxyl group-containing monomers such as (meth)acrylic acid hydroxyethyl ester and (meth)acrylic acid hydroxypropyl ester; amide group-containing monomers such as (meth)acrylamide, dimethyl (meth)acrylamide, N-butylacrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; (meth)acrylic acid alkylaminoalkyl esters such as (meth)acrylic acid aminoethyl ester, (meth)acrylic acid dimethylaminoethyl ester, and (meth)acrylic acid tert-butylaminoethyl ester; (meth)acrylic acid methoxyethyl ester, and (meth)acrylic acid ethoxyethyl ester. (Meth)acrylic acid alkoxyalkyl esters such as esters; (meth)acrylic acid methoxyethylene glycol ester, (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid methoxyethylene glycol ester, (meth)acrylic acid methoxydiethylene glycol ester, (meth)acrylic acid methoxypolyethylene glycol ester, (meth)acrylic acid methoxypolypropylene glycol ester; and vinyl monomers such as (meth)acrylonitrile, vinyl acetate, vinyl propionate, N-vinyl-2-pyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidine, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylcaprolactam, vinyloxazole, and vinylmorpholine. The other monomers may be used alone or in combination of two or more.

[0049] In the (meth)acrylic polymer, the content of structural units derived from other monomers may be, for example, greater than 0% by weight, 0.1% by weight to 50% by weight, 1% by weight to 30% by weight, 2% by weight to 20% by weight, or even 3% by weight to 10% by weight.

[0050] The glass transition temperature (Tg) of the (meth)acrylic polymer is, for example, -10°C to 30°C, as a theoretically calculated value obtained by the FOX formula, and may be -5°C to 20°C, 0°C to 15°C, or even 5°C to 10°C.

[0051] The weight average molecular weight of the (meth)acrylic polymer is, for example, 1,000 to 10,000,000, and may be 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 the amounts of polymerization initiator, chain transfer agent, emulsifier, etc. used during polymerization, reaction conditions, etc.

[0052] The (meth)acrylic polymer can be synthesized, for example, by emulsion polymerization using an emulsion of the raw material monomers. In emulsion polymerization, an emulsifier (surfactant), a polymerization initiator, and, if necessary, a chain transfer agent, can be appropriately used. Examples of emulsion polymerization methods include a batch charge method (batch polymerization method), a monomer dropping method, and a monomer emulsion dropping method. In the monomer dropping method, a continuous dropping method or a divided dropping method can be appropriately selected. These methods can be appropriately combined. The reaction conditions for emulsion polymerization can be appropriately adjusted depending on the monomers, etc., and, for example, the polymerization temperature is 20°C to 100°C, and the polymerization time is 30 minutes to 24 hours.

[0053] In the emulsion polymerization, it is preferable to use an anionic emulsifier, a nonionic emulsifier, or the like as the emulsifier. As an example, the anionic emulsifier or nonionic emulsifier contained in the pressure-sensitive adhesive composition of the present embodiment corresponds to the emulsifier used in the emulsion polymerization. Details of the emulsifier will be described later.

[0054] Examples of the polymerization initiator include 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), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] Examples of initiators include azo initiators such as ammonium persulfate, potassium persulfate, and the like; 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 hydrogen sulfite, or a combination of a peroxide and sodium ascorbate, with azo initiators being preferred. The amount of polymerization initiator used is, for example, 0.005 to 1 part by weight per 100 parts by weight of the (meth)acrylic polymer (or monomers for synthesizing the (meth)acrylic polymer).

[0055] 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, or may be 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 monomers for synthesizing the (meth)acrylic polymer).

[0056] The dispersion medium used in the emulsion polymerization preferably contains water. The dispersion medium may contain an organic solvent together with water. The amount of the dispersion medium used is, for example, 30 to 80 parts by weight, or may be 40 to 70 parts by weight, per 100 parts by weight of the (meth)acrylic polymer (or monomers for synthesizing the (meth)acrylic polymer).

[0057] The (meth)acrylic polymer can also be synthesized by a method other than emulsion polymerization. In this case, the PSA composition can be prepared by dispersing the synthesized (meth)acrylic polymer in a dispersion medium using an emulsifier (anionic emulsifier or nonionic emulsifier).

[0058] 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.

[0059] In the pressure-sensitive adhesive composition, the average particle size of the (meth)acrylic polymer particles is, for example, 1000 nm or less, and may be 700 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or even 200 nm or less. When the average particle size of the (meth)acrylic polymer particles is 300 nm or less, the compatibility of the (meth)acrylic polymer with the organic liquid component tends to be good. The lower limit of the average particle size of the (meth)acrylic polymer particles is not particularly limited, and may be, for example, 50 nm or more, or 100 nm or more. In this specification, "average particle size" refers to the volume-based average particle size (volume average particle size) measured by dynamic light scattering. The average particle size of the (meth)acrylic polymer particles can be adjusted by, for example, the reaction conditions during the synthesis of the (meth)acrylic polymer.

[0060] [Anionic emulsifiers and nonionic emulsifiers] The anionic emulsifier and the nonionic emulsifier are, for example, components that emulsify the (meth)acrylic polymer in the pressure-sensitive adhesive composition. The nonionic emulsifier also tends to function as a component that adjusts the surface hardness of the pressure-sensitive adhesive layer. As described above, the anionic emulsifier and the nonionic emulsifier may be the emulsifier used during emulsion polymerization to synthesize the (meth)acrylic polymer. These emulsifiers may be added after the synthesis of the (meth)acrylic polymer.

[0061] At least one emulsifier selected from the group consisting of anionic emulsifiers and nonionic emulsifiers may have a polymerizable group. Examples of the polymerizable group contained in the emulsifier include groups containing a polymerizable unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. The emulsifier containing a polymerizable group can function as a monomer during emulsion polymerization to synthesize a (meth)acrylic polymer. For example, an emulsifier functioning as a monomer is copolymerized with a (meth)acrylic acid alkyl ester or the like during emulsion polymerization and incorporated into the (meth)acrylic polymer. Thus, in the pressure-sensitive adhesive composition of this embodiment, at least one of the anionic emulsifier and the nonionic emulsifier may be incorporated into the (meth)acrylic polymer. In other words, in the pressure-sensitive adhesive composition of this embodiment, the (meth)acrylic polymer may further contain a structural unit derived from at least one of the anionic emulsifier and the nonionic emulsifier. In this specification, the emulsifier incorporated into the (meth)acrylic polymer is also considered a component of the pressure-sensitive adhesive composition.

[0062] At least one selected from the group consisting of anionic emulsifiers and nonionic emulsifiers may have an oxyethylene group. In this case, the average number of moles of oxyethylene groups added in the emulsifier is, for example, 5 or more, and may be 10 or more. The upper and lower limits of the average number of moles of oxyethylene groups added are not particularly limited, but are preferably 20 or more and 50 or less.

[0063] Examples of anionic emulsifiers include sulfate ester salts and sulfonate ester salts. Examples of sulfate ester salts include alkyl sulfate ester salts such as sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, and polyoxyethylene alkyl phenyl ether sodium sulfate. Examples of sulfonate ester salts include sodium dodecylbenzenesulfonate. The above-mentioned compounds may have any substituent. For example, polyoxyethylene alkyl ether ammonium sulfate may have an allyloxymethyl group, or may be polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate. The anionic emulsifier preferably contains an alkyl sulfate ester salt.

[0064] Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers. The above-mentioned compounds may have any substituent. For example, the polyoxyethylene alkyl ether may have an allyloxymethyl group, or may be polyoxyethylene-1-(allyloxymethyl) alkyl ether. It is particularly preferable that the nonionic emulsifier contains polyoxyethylene-1-(allyloxymethyl) alkyl ether.

[0065] The amount of the anionic emulsifier to be added is, for example, 0.1 parts by weight or more, and may be 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, relative to 100 parts by weight of the (meth)acrylic polymer (or monomers for synthesizing the (meth)acrylic polymer). The upper limit of the amount of the anionic emulsifier to be added may be, for example, 10 parts by weight or less, 5 parts by weight or less, or even 3 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer. The PSA composition may not contain an anionic emulsifier.

[0066] The amount of the nonionic emulsifier to be added is, for example, 0.1 parts by weight or more, and may be 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, or even 3 parts by weight or more, relative to 100 parts by weight of the (meth)acrylic polymer (or monomers for synthesizing the (meth)acrylic polymer). The upper limit of the amount of the nonionic emulsifier to be added is, for example, 10 parts by weight or less, and may even be 5 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer.

[0067] [Organic liquid component] As described above, the pressure-sensitive adhesive composition of the present embodiment contains an organic liquid component. The organic liquid component tends to reduce the modulus of the pressure-sensitive adhesive layer in the low deformation region, maintain good adhesion to the skin, reduce stratum corneum 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, the amount of stratum corneum peeled off when the pressure-sensitive adhesive layer is peeled from the skin tends to be significantly reduced. The organic liquid component is also suitable for improving the moisture permeability of a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer.

[0068] The organic liquid component is preferably a component that is liquid at room temperature (25°C) and is compatible with the (meth)acrylic polymer. Here, "compatible" means that the organic liquid component is uniformly dissolved and incorporated into the (meth)acrylic polymer in the pressure-sensitive adhesive composition, and separation cannot be confirmed visually. It is preferable that the organic liquid component is unlikely to migrate from the pressure-sensitive adhesive sheet to medical tools, medical equipment, etc. when the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer is in use.

[0069] As described above, the organic liquid component contains a carboxylic acid ester. The carboxylic acid ester preferably does not contain functional groups other than ester groups (e.g., thiol groups). 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 a linear or branched chain. 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.

[0070] The alcohol constituting the carboxylic acid ester may be a monohydric alcohol or a polyhydric alcohol. The hydric number 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 even 1 to 5. Examples of the alcohol include ethanol, isopropanol, 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.

[0071] Specific examples of carboxylic acid esters include ethyl myristate, isopropyl myristate, isocetyl myristate, octyldodecyl myristate, isopropyl palmitate, isostearyl palmitate, butyl stearate, isocetyl stearate, isopropyl isostearate, hexyl laurate, isostearyl laurate, cetyl lactate, myristyl lactate, diethyl phthalate, octyldodecyl oleate, hexyldecyl dimethyloctanoate, cetyl 2-ethylhexanoate, isocetyl 2-ethylhexanoate, stearyl 2-ethylhexanoate, and amber. Examples of suitable carboxylic acid esters include dioctyl adipate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimellitate, triisocetyl trimellitate, propylene glycol dicaprylate, propylene glycol dicaprate, propylene glycol diisostearate, glyceryl monocaprylate, glyceryl tricaprylate, glyceryl tri-2-ethylhexanoate, glyceryl tricaprate, glyceryl trilaurate, glyceryl triisostearate, glyceryl trioleate, trimethylolpropane tri-2-ethylhexanoate, and sorbitan trioleate. The organic liquid component preferably contains glyceryl tricaprylate as the carboxylic acid ester.

[0072] The amount of the organic liquid component is, for example, 10 parts by weight or more, and may be 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, or even 70 parts by weight or more, relative to 100 parts by weight of the (meth)acrylic polymer. The greater the amount of the organic liquid component, the more likely the moisture permeability of the pressure-sensitive adhesive layer is to be improved. From the viewpoint of ensuring sufficient adhesive strength of the pressure-sensitive adhesive layer, the upper limit of the amount of the organic liquid component may be, for example, 120 parts by weight or less, 100 parts by weight or less, or even 80 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer. The amount of the organic liquid component is preferably 30 to 80 parts by weight, more preferably 40 to 80 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer.

[0073] [Dispersion medium] The PSA composition may further contain a dispersion medium. In particular, it is preferable that the PSA composition contains water as the dispersion medium. The PSA composition is typically an oil-in-water (O / W) emulsion. A PSA composition containing water as the dispersion medium can significantly reduce the amount of organic solvent emitted by heating during the production of a PSA layer. This not only reduces the amount of fuel required to combust the organic solvent removed by heating in a deodorizing furnace or the like, but also reduces the amount of CO2 emitted by the combustion of the organic solvent. However, the PSA composition may contain an organic solvent as well as water as the dispersion medium. The content of the dispersion medium in the PSA composition is not particularly limited and is, for example, 10% by weight to 90% by weight.

[0074] [Additives] The PSA composition may further contain additives other than those mentioned above. Examples of the additives include a crosslinking agent, a tackifier, a thickener, a plasticizer, a softener, a filler, and a pigment.

[0075] [Physical properties of adhesive composition] The pressure-sensitive adhesive composition is preferably neutral. In a neutral pressure-sensitive adhesive composition, particles of the (meth)acrylic polymer are less likely to aggregate and tend to be highly stable. The pH of the pressure-sensitive adhesive composition is, for example, 6.0 to 8.0, and may be 6.5 to 7.5. The pH of the pressure-sensitive adhesive composition is preferably 7.0.

[0076] The viscosity of the pressure-sensitive adhesive composition is, for example, 500 mPa·s or less, or may be 300 mPa·s or less, or even 100 mPa·s or less, under conditions of pH 7.0 and temperature 25°C. A pressure-sensitive adhesive composition having a viscosity of 500 mPa·s or less can be said to have sufficient coatability for practical use. The lower limit of the viscosity of the pressure-sensitive adhesive composition is, for example, 10 mPa·s or more.

[0077] <Embodiments of the pressure-sensitive adhesive sheet> As shown in Fig. 1, the pressure-sensitive adhesive sheet 10 of this embodiment includes a pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive layer 1 is formed from the pressure-sensitive adhesive composition described above, and more specifically, is a cured product of the pressure-sensitive adhesive composition. In this specification, the term "pressure-sensitive adhesive sheet" is used to encompass "pressure-sensitive adhesive tape."

[0078] The pressure-sensitive adhesive sheet 10 may further comprise a substrate 2 that supports the pressure-sensitive adhesive layer 1, and a release liner 3 disposed on the surface of the pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive layer 1 is, for example, located between the substrate 2 and the release liner 3, and is in direct contact with both the substrate 2 and the release liner 3. As an example, the pressure-sensitive adhesive sheet 10 can be used by peeling off the release liner 3 and then attaching the pressure-sensitive adhesive layer 1 to an object (e.g., skin). The pressure-sensitive adhesive sheet 10 is not limited to the above structure. For example, the pressure-sensitive adhesive sheet 10 may be composed of only the pressure-sensitive adhesive layer 1. The pressure-sensitive adhesive sheet 10 may also comprise two pressure-sensitive adhesive layers 1 and two release liners 3, and may have a structure in which the release liner 3, pressure-sensitive adhesive layer 1, substrate 2, pressure-sensitive adhesive layer 1, and release liner 3 are laminated in this order, for example.

[0079] [Adhesive layer] The thickness of the pressure-sensitive adhesive layer 1 is not particularly limited, and is, for example, 10 to 80 μm.

[0080] The gel fraction of the pressure-sensitive adhesive layer 1 is, for example, 20% to 80%, and may be 40% to 80%.

[0081] In this embodiment, the moisture permeability P of the pressure-sensitive adhesive layer 1 determined by the following test is 800 g / (m 2 24 hours or more is preferable. Test: A laminate consisting of a 30 μm thick adhesive layer 1 and a 30 μm thick polyurethane film is prepared. The laminate is attached to a glass container so as to close the opening of the glass container containing water. The glass container is left for 24 hours under conditions of a temperature of 40°C and a humidity of 30% RH, and the weight of water that has permeated the laminate from inside the glass container is determined. The opening area (m 2 The ratio of the weight (g) to the moisture permeability (P) is determined as the moisture permeability (P).

[0082] A detailed method for measuring the moisture permeability P of the adhesive layer 1 will be described below with reference to FIG. 2. First, a 25 μm thick adhesive layer 1 having the same composition as the adhesive layer 1 is formed on a release liner to prepare a laminate of the release liner and the adhesive layer 1. The adhesive layer 1 can be prepared by the method described below. Next, the entire surface of the adhesive layer 1 of the obtained laminate is overlaid on a polyurethane film 5 (30 μm thick), and the two are pressed together by rolling a 2 kg roller back and forth once. The polyurethane film 5 used has sufficiently higher moisture permeability than the adhesive layer 1 and has little effect on the value of the moisture permeability P. Next, the release liner is peeled off from the adhesive layer 1 to prepare a laminate 20 composed of the adhesive layer 1 and the polyurethane film 5. The laminate 20 is cut to adjust its shape and dimensions as necessary. As an example, the laminate 20 is adjusted to have a circular shape in plan view and a diameter of 50 mm.

[0083] 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 cylindrical container with a bottom, an inner diameter of 40 mm, and a height of 40 mm. The volume of the water 35 contained in the glass container 30 is, for example, 10 mL. Next, the laminate 20 is attached to the glass container 30 so as to close the opening 31 of the glass container 30 (FIG. 2). More specifically, the adhesive layer 1 of the laminate 20 is attached to the end face of the glass container 30, thereby sealing the internal space of the glass container 30. In this way, the measurement object 50 is obtained.

[0084] Next, the glass container 30 (specifically, the measurement object 50) is placed in a commercially available thermo-hygrostat and left for 24 hours under conditions of a temperature of 40°C and a humidity of 30%RH. At this time, a portion of the water 35 evaporates, permeates the laminate 20, and is 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 measurement object 50 after being left for 24 hours from the weight W1 (g) of the measurement object 50 immediately after production is determined as the weight W (g) of the water (specifically, water vapor) that permeated the laminate 20 from the inside of the glass container 30. The opening area A (m2 The ratio W / A of the weight W (g) of water that has permeated the laminate 20 to the area A (m 2 ) can be calculated, for example, by the formula (r / 2) based on the inner diameter r (m) of the glass container 30. 2 ×π.

[0085] The moisture permeability P of the pressure-sensitive adhesive layer 1 is preferably 900 g / (m 2 24h) or more, and 930g / (m 2 ·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 even 1400g / (m 2 The upper limit of the moisture permeability P is not particularly limited, and may be, for example, 5000 g / (m 2 24h) or less, 3000g / (m 2 24 hours or less may be acceptable.

[0086] [Base material] The substrate 2 is, for example, a layered member that supports the pressure-sensitive adhesive layer 1. The substrate 2 may be a single layer or a laminate having multiple layers. From the viewpoint of suppressing the skin from becoming damp when the pressure-sensitive adhesive sheet 10 is attached to the skin, the substrate 2 preferably has sufficiently higher moisture permeability than the pressure-sensitive adhesive layer 1.

[0087] The substrate 2 may be non-porous or porous. When the substrate 2 is porous, moisture permeability tends to be less likely to decrease even if the substrate 2 is thick. The porous substrate 2 preferably has water vapor permeability that allows water vapor to pass through, but is water-impermeable that does not substantially allow liquid water to pass through.

[0088] Examples of materials for the substrate 2 include urethane-based polymers such as polyether urethane and polyester urethane; amide-based polymers such as polyether polyamide block polymers; acrylic polymers such as polyacrylate; polyolefin-based polymers such as polyethylene, polypropylene, and ethylene / vinyl acetate copolymer; and polyester-based polymers such as polyether polyester. From the viewpoint of moisture permeability, the substrate 2 preferably contains a urethane-based polymer or an amide-based polymer, and particularly preferably contains a urethane-based polymer. As an example, the substrate 2 may be a polyurethane film made of a urethane-based polymer, or may be a laminate in which a layer containing a polyolefin-based polymer is laminated on a polyurethane film.

[0089] The thickness of the substrate 2 is not particularly limited, and may be, for example, 10 to 100 μm, or 20 to 40 μm.

[0090] From the viewpoint of conformability when the pressure-sensitive adhesive sheet 10 is attached to the skin, the substrate 2 has a tensile strength of, for example, 100 to 900 kg / cm 2 and the 100% modulus is 10 to 100 kg / cm 2 It is preferable that:

[0091] [Release liner] Any known release liner can be used as the release liner 3. The release liner 3 includes, for example, a liner substrate and a release layer formed on one surface of the liner substrate. Materials for the liner substrate include those mentioned above for the substrate 2. The release layer can be formed by applying a release treatment agent to the surface of the liner substrate. Examples of release treatment agents include silicone-based release treatment agents, long-chain alkyl-based release treatment agents, fluorine-based release treatment agents, and molybdenum sulfide-based release treatment agents.

[0092] 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.

[0093] [Manufacturing method of adhesive sheet] The pressure-sensitive adhesive sheet 10 of this embodiment can be produced, for example, by the following method. First, the above-mentioned pressure-sensitive adhesive composition is applied onto a release liner 3 to form a coating film. The method for applying the pressure-sensitive adhesive composition is not particularly limited, and for example, spin coating, dip coating, etc. can be used. The pressure-sensitive adhesive composition may also be applied using a wire bar or the like.

[0094] Next, the coating film is dried to form the pressure-sensitive 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, and may be 100°C or higher. The heating time of the coating film is, for example, 1 minute or longer.

[0095] Next, the substrate 2 is attached to the pressure-sensitive adhesive layer 1. In this way, the pressure-sensitive adhesive sheet 10 can be produced.

[0096] [Characteristics of adhesive sheet] The adhesive sheet 10 of this embodiment tends to be able to be attached with sufficient strength to an object (especially skin) via the adhesive layer 1. As an example, the adhesive sheet 10 preferably has an adhesive strength F to a bakelite plate of 0.1 N / 10 mm or more.

[0097] The adhesive strength F can be measured by the following method. First, a test piece is prepared by cutting the adhesive sheet 10 to a size of 100 mm length x 10 mm width. Next, the release liner 3 is removed from the test piece to expose the surface of the adhesive layer 1. The entire surface of the adhesive layer 1 is placed on a bakelite, and a 2 kg roller is moved back and forth once to press the two together. Next, using a commercially available tensile tester, the test piece is peeled from the bakelite at a peel speed of 300 mm / min and a peel angle of 180°. The force required to peel the test piece from the bakelite is measured once every 0.5 seconds at a point where the value is relatively stable. The average of the measured values ​​is determined as the adhesive strength F. The above test is performed in an atmosphere of 23°C.

[0098] The adhesive strength 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 strength 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, or even 1.0 N / 10 mm or less.

[0099] [Uses of adhesive sheets] The adhesive sheet 10 of this embodiment is typically for medical use. Specifically, the adhesive sheet 10 can be used for adhesive bandages, surgical tapes, first-aid adhesive plasters, large adhesive plasters, dressing materials, poultices, drapes, etc. The adhesive sheet 10 can also be used as a transdermal absorption preparation by carrying a drug on the adhesive layer 1. The adhesive sheet 10 may also be used for purposes other than medical use. [Example]

[0100] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0101] Example 1 The monomer components were emulsified in a container using 47 parts by weight of isononyl acrylate (iNA), 50 parts by weight of butyl acrylate (BA), 3 parts by weight of acrylic acid (AA), and 0.03 parts by weight of 3-methacryloyloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Silicones 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. The mixture was stirred using a homomixer to emulsify the monomer components, thereby obtaining a monomer emulsion.

[0102] A reaction vessel (separable flask) equipped with a condenser, nitrogen inlet, thermometer, and stirrer was charged with 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. The mixture was 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 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 then aged for another 3 hours. This yielded a dispersion containing a (meth)acrylic polymer.

[0103] Next, 4.73 parts by weight of 10% aqueous ammonia was added to the dispersion to neutralize the dispersion and adjust the pH to about 7. Furthermore, 0.6 parts by weight of a thickener (Aron B-500, manufactured by Toagosei Co., Ltd.) and 60 parts by weight of glyceryl tricaprylate (Coconard RK, manufactured by Kao Corporation) as an organic liquid component were added to the dispersion to obtain the pressure-sensitive adhesive composition of Example 1.

[0104] (Examples 2 to 14 and Comparative Examples 1 to 5) The pressure-sensitive adhesive compositions of Examples 2 to 14 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that the types and amounts of materials used were changed as shown in Tables 1 and 2. In Comparative Examples 1 and 2, no organic liquid component was added. In Comparative Examples 3 to 5, no nonionic emulsifier was added. In Tables 1 and 2, the amount of emulsifier used is the total amount of the emulsifier used to prepare the monomer emulsion and the amount added separately to the monomer emulsion.

[0105] [evaluation] The pressure-sensitive 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. This coating film was then dried at 130°C for 3 minutes to form a pressure-sensitive adhesive layer (30 μm thick). The pressure-sensitive adhesive layer was bonded to a substrate to obtain a pressure-sensitive adhesive sheet for evaluation. A polyurethane film (30 μm thick) (Esmer URS210, manufactured by Nihon Matai Co., Ltd.) was used as the substrate.

[0106] (Appearance change) An evaluation adhesive sheet measuring 10 mm x 50 mm was prepared, and the release liner was peeled off from the evaluation adhesive sheet. The exposed adhesive layer was placed on the subject's forearm and pressed with a 2 kg roller. In this state, the evaluation adhesive sheet was left in an environment of 23°C and 50% RH for 6 hours. Changes in the appearance of the evaluation adhesive sheet after leaving it were evaluated according to the following criteria. Evaluation criteria ◯: No peeling can be visually confirmed. ×: Peeling occurs at the edge.

[0107] (Amount of exfoliation) A 10mm x 50mm adhesive sheet for evaluation was prepared, and the release liner was peeled off from the adhesive sheet for evaluation. The exposed adhesive layer was placed on the subject's forearm and pressed with a 2kg roller. In this state, the adhesive sheet for evaluation was left in an environment of 23°C and 50% RH for 6 hours, and then peeled off from the forearm. The adhesive sheet for evaluation was peeled off using a peel tester (Shimadzu Corporation, AGX-V) at a peel speed of 300mm / min.

[0108] Next, the surface of the adhesive layer of the peeled evaluation adhesive sheet was stained with a keratin staining solution (aqueous solution of 1% Gentian Violet and 0.5% Brilliant Green) for 10 minutes and then washed with water. The stained surface of the adhesive layer was observed with an optical microscope (Keyence Corporation, VX-7000). In the microscopic image, areas with attached keratin were identified, and the total area of ​​each area was calculated by image processing. The ratio of this total value to the surface area of ​​the adhesive layer in the microscopic image was considered to be the amount of keratin peeled, and was evaluated according to the following criteria. Evaluation criteria ◎: The amount of keratin peeled off is less than 10%. Good: The amount of keratin peeled was 10% or more but less than 20%. △: The amount of keratin peeled is 20% or more but less than 30%. ×: The amount of keratin peeled is 30% or more.

[0109] (moisture permeability) Using the pressure-sensitive adhesive sheet for evaluation, the moisture permeability P of the pressure-sensitive adhesive layer was measured by the method described above, and evaluated according to the following criteria. Evaluation criteria ◎: Moisture permeability P is 1200g / (m 2 24 hours or more). ○: Moisture permeability P is 1000g / (m 2 ·24h) or more 1200g / (m 2 - Less than 24h. △: Moisture permeability P is 800g / (m 2 ·24h) or more 1000g / (m 2 - Less than 24h. ×: Moisture permeability P is 800g / (m 2 - Less than 24h.

[0110] [Table 1]

[0111] [Table 2]

[0112] The abbreviations in Table 1 are as follows: 2EHA: 2-ethylhexyl acrylate nOcA: n-octyl acrylate iNA: Isononyl acrylate iDAA: isodecyl acrylate LA: n-dodecyl acrylate BA: n-butyl acrylate iBA: isobutyl acrylate MMA: methyl methacrylate AA: acrylic acid KBM-503: 3-methacryloyloxypropyltrimethoxysilane (Shin-Etsu Silicones Co., Ltd., KBM-503) 1-LSH: 1-dodecanethiol KH-10: Polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (Aqualon KH-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) SR-10: Polyoxyethylene alkyl ether ammonium sulfate (ADEKA Corporation, Adeka Reasoap SR-10) KN-30: Polyoxyethylene-1-(allyloxymethyl) alkyl ether (Aqualon KN-30, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ER-30: Allyloxypolyoxyethylene (ADEKA Corporation, Adeka Reasoap ER-30) Coconard RK: Glyceryl tricaprylate (Kao Corporation, Coconard RK)

[0113] As can be seen from Tables 1 and 2, the evaluation adhesive sheets prepared using the adhesive compositions of the Examples had better results in the evaluation of the amount of keratin peeling compared to the Comparative Examples, and were suitable for reducing the amount of keratin peeling. [Industrial Applicability]

[0114] The pressure-sensitive adhesive sheet produced using the pressure-sensitive adhesive composition of the present embodiment can be used by being attached to an object such as the skin. [Explanation of symbols]

[0115] 1. Adhesive layer 2 Base material 3 Release liner 10 adhesive sheet

Claims

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

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

3. The pressure-sensitive adhesive composition according to claim 1 , wherein the organic liquid component comprises glyceryl tricaprylate.

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

5. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the second (meth)acrylic acid alkyl ester comprises at least one selected from the group consisting of 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, and n-dodecyl acrylate.

6. The pressure-sensitive adhesive composition according to claim 1, wherein the number of carbon atoms in the alkyl group of the first (meth)acrylic acid alkyl ester is 1 to 5.

7. The pressure-sensitive adhesive composition according to claim 1, wherein the first (meth)acrylic acid alkyl ester comprises at least one selected from the group consisting of n-butyl acrylate and isobutyl acrylate.

8. The pressure-sensitive adhesive composition according to claim 1 , wherein the carboxyl group-containing monomer comprises acrylic acid.

9. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the structural unit U3 in the (meth)acrylic polymer is 2 to 4 wt %.

10. The pressure-sensitive adhesive composition according to claim 1 , further comprising an anionic emulsifier.

11. The pressure-sensitive adhesive composition according to claim 10, wherein at least one selected from the group consisting of the anionic emulsifier and the nonionic emulsifier has a polymerizable group.

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

13. The pressure-sensitive adhesive composition according to claim 10 , wherein the anionic emulsifier comprises an alkyl sulfate ester salt.

14. The pressure-sensitive adhesive composition according to claim 10 , wherein the amount of the anionic emulsifier blended is 1 part by weight or more based on 100 parts by weight of the (meth)acrylic polymer.

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

16. The pressure-sensitive adhesive composition according to claim 1, wherein the amount of the nonionic emulsifier blended is 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 any one of claims 1 to 16.

Images