Adhesive composition

Abstract

To provide an adhesive composition which is an aqueous dispersion and can control adhesiveness.SOLUTION: The adhesive composition contains an aqueous dispersion of a polymer (A) having a structural unit represented by the following formula (1) (where R1 represents a hydrogen atom or a methyl group; R2 and R3 are the same or different and each represent a hydrogen atom or an organic group; R4 represents a hydrogen atom or an organic group; and n represents an integer of 1 or more).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive composition, and more particularly to a pressure-sensitive adhesive composition useful for semiconductor processing and the like. [Background technology]

[0002] A pressure-sensitive adhesive composition is a composition containing a pressure-sensitive adhesive that has adhesive strength to an adherend, and is used to form an adhesive layer on various materials, parts, and the like. One application of adhesives is temporary bonding, which bonds components together. For example, in semiconductor processing, semiconductor wafers sliced ​​from silicon single crystals are polished, diced, cleaned, and so on. When dicing a semiconductor wafer, the semiconductor wafer is temporarily attached to a frame with an adhesive or the like, and then cut into individual chips. After cutting, the adhesive used for such temporary bonding must have sufficient adhesive strength, but also be easily removable without leaving any adhesive residue when the temporary bonding is no longer needed.

[0003] Polymers obtained by polymerizing (meth)acrylic acid esters are highly versatile industrially and are used in a variety of applications, including as pressure-sensitive adhesives. Among these, organic solvent-based acrylic pressure-sensitive adhesives exhibit their adhesive properties depending on the design of the base polymer. For example, Patent Document 1 discloses a pressure-sensitive adhesive composition that contains (A) a (meth)acrylic acid ester polymer containing a repeating unit derived from styrene, (B) a monomer having a total of three or more polymerizable carbon-carbon double bonds and / or polymerizable carbon-carbon triple bonds, (C) an oligomer having a total of two or more polymerizable carbon-carbon double bonds and / or polymerizable carbon-carbon triple bonds, and (D) a photopolymerization initiator, in which the (A) polymer is contained in an amount of 40 to 70 parts by mass, the (B) monomer in an amount of 1 to 59 parts by mass, and the (C) oligomer in an amount of 1 to 59 parts by mass [wherein (A) + (B) + (C) = 100 parts by mass]], and the adhesive strength of which can be reduced by irradiation with ultraviolet light.

[0004] Furthermore, vinyl ether group-containing (meth)acrylic acid esters are known as heteropolymerizable monomers having both a radically polymerizable group and an ionically polymerizable group in the molecule. Polymers obtained by polymerizing such heteropolymerizable monomers are also highly versatile and useful industrially, and are also used in adhesive applications. Regarding such polymers, Patent Document 2 discloses an adhesive composition containing a polymer (A) having a structural unit represented by a specific formula, and a crosslinking agent (B) and / or a curing catalyst (C), wherein the polymer (A) has a weight-average molecular weight of 10,000 or more and a molecular weight distribution (weight-average molecular weight / number-average molecular weight) of 5.0 or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-170200 [Patent Document 2] Patent Publication No. 2021-031618 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, various pressure-sensitive adhesive compositions have been developed to date. However, conventional compositions contain organic solvents, and the evaporation of the organic solvent during use of the pressure-sensitive adhesive poses a problem of harm to workers and the environment.

[0007] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a pressure-sensitive adhesive composition which is an aqueous dispersion and whose adhesiveness can be controlled. [Means for solving the problem]

[0008] The present inventors have conducted extensive research into polymers used in pressure-sensitive adhesives and have found that a composition containing an aqueous dispersion of a polymer having structural units derived from a vinyl ether group-containing (meth)acrylic acid ester of a predetermined structure is an aqueous dispersion that can control adhesiveness. This has led to the realization that the above-mentioned problems can be successfully solved, and has led to the present invention.

[0009] The present invention includes the following pressure-sensitive adhesive compositions and the like. [1] The following formula (1); [ka] (In the formula, R 1 represents a hydrogen atom or a methyl group. 2 and R 3 R may be the same or different and represent a hydrogen atom or an organic group. 4 represents a hydrogen atom or an organic group, and n represents an integer of 1 or more. A pressure-sensitive adhesive composition comprising an aqueous dispersion of a polymer (A) having a structural unit represented by the following formula: [2] The pressure-sensitive adhesive composition according to [1], wherein the polymer (A) further has a structural unit derived from a neutral or basic polar group-containing monomer. [3] The pressure-sensitive adhesive composition according to [2] above, wherein the neutral or basic polar group-containing monomer comprises at least one selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, and a hydroxyl group-containing monomer. [4] The pressure-sensitive adhesive composition according to any one of the above [1] to [3], wherein the polymer (A) further has a structural unit derived from a monomer having a homopolymer glass transition temperature of -70°C to -10°C. [5] The pressure-sensitive adhesive composition according to any one of the above [1] to [4], further comprising a photopolymerization initiator. [6] The pressure-sensitive adhesive composition according to any one of [1] to [5] above, which is used for changing adhesive properties. [Effects of the Invention]

[0010] The pressure-sensitive adhesive composition of the present invention has the above-mentioned constitution, is an aqueous dispersion, and has controllable adhesiveness, and therefore can be suitably used in semiconductor processing and the like. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description and can be appropriately modified and applied within the scope of the present invention. Note that combinations of two or more of the individual preferred embodiments of the present invention described below also fall within the scope of preferred embodiments of the present invention. As used herein, "(meth)acryloyl" means "acryloyl" or "methacryloyl", "(meth)acrylate" means "acrylate" or "methacrylate", and "(meth)acrylic" means "acrylic" or "methacrylic".

[0012] [Adhesive composition] The pressure-sensitive adhesive composition of the present invention contains an aqueous dispersion of a polymer (A) having a structural unit represented by the above formula (1). The proportion of the polymer (A) in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 10 to 70% by mass, more preferably 15 to 65% by mass, and even more preferably 20 to 60% by mass, relative to 100% by mass of the pressure-sensitive adhesive composition.

[0013] The pressure-sensitive adhesive composition of the present invention may contain other components in addition to the aqueous dispersion of polymer (A), and the proportion of the other components is not particularly limited, but is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, and even more preferably 1 to 10% by mass, relative to 100% by mass of the pressure-sensitive adhesive composition.

[0014] By including an aqueous dispersion of polymer (A), the pressure-sensitive adhesive composition of the present invention can be made substantially free of organic solvents or can be made to contain a significantly reduced amount of organic solvent. The content of the organic solvent in the pressure-sensitive adhesive composition of the present invention is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.1% by mass or less, based on 100% by mass of the pressure-sensitive adhesive composition. An embodiment in which the content of the organic solvent in the pressure-sensitive adhesive composition is 0% by mass is one of the preferred embodiments of the present invention.

[0015] The pressure-sensitive adhesive composition of the present invention preferably has a coating film having a gel fraction of 60 to 100 mass% after irradiation with ultraviolet light, as measured in tetrahydrofuran solvent. The gel fraction in the present invention is an index showing the solubility of a coating film formed from the pressure-sensitive adhesive composition in tetrahydrofuran solvent, and a higher gel fraction means a lower solubility in tetrahydrofuran solvent. The gel fraction is more preferably 65 to 99% by mass, and even more preferably 70 to 99% by mass. The gel fraction can be measured by the method described in the examples.

[0016] The essential components and optional components contained in the pressure-sensitive adhesive composition of the present invention will be further described below.

[0017] <Polymer (A)> The polymer (A) is not particularly limited as long as it has a structural unit represented by the formula (1), but the proportion of the structural unit represented by the formula (1) is preferably 1 to 60 mass %, more preferably 2 to 50 mass %, and even more preferably 3 to 40 mass %, relative to 100 mass % of all structural units. When the polymer (A) is produced by a phase inversion emulsification method, the content of the structural unit represented by the formula (1) is preferably 10 to 60 mass %, more preferably 15 to 55 mass %, and even more preferably 20 to 50 mass %, relative to 100 mass % of all structural units.

[0018] The polymer (A) preferably has a structural unit derived from a neutral or basic polar group-containing monomer, which further improves the adhesiveness of the composition. The total proportion of structural units derived from neutral or basic polar group-containing monomers in the polymer (A) is preferably 0.1 to 10 mass%, more preferably 0.5 to 9 mass%, and even more preferably 1 to 8 mass%, based on 100 mass% of all structural units.

[0019] The polymer (A) preferably has a structural unit derived from a basic polar group-containing monomer, which further improves the adhesiveness of the composition. The proportion of structural units derived from basic polar group-containing monomers in the polymer (A) is preferably 0.1 to 10 mass %, more preferably 0.5 to 9 mass %, and even more preferably 1 to 8 mass %, relative to 100 mass % of all structural units.

[0020] The polymer (A) preferably has a structural unit derived from an acyclic amino group-containing monomer, which further improves the adhesiveness of the composition. The proportion of structural units derived from acyclic amino group-containing monomers in the polymer (A) is preferably 0.1 to 10 mass %, more preferably 0.5 to 9 mass %, and even more preferably 1 to 8 mass %, relative to 100 mass % of all structural units.

[0021] The polymer (A) may have a structural unit derived from a cyclic amino group-containing monomer. The proportion of structural units derived from cyclic amino group-containing monomers in the polymer (A) is preferably 0 to 5 mass %, more preferably 0.1 to 4 mass %, and even more preferably 0.1 to 3 mass %, relative to 100 mass % of all structural units.

[0022] The polymer (A) preferably has a structural unit derived from a neutral polar group-containing monomer. The proportion of structural units derived from neutral polar group-containing monomers in the polymer (A) is preferably 0.1 to 10 mass %, more preferably 0.5 to 9 mass %, and even more preferably 1 to 8 mass %, relative to 100 mass % of all structural units.

[0023] The polymer (A) preferably has a structural unit derived from a monomer having an amide group, which further improves the adhesiveness of the composition. The proportion of structural units derived from monomers having an amide group in the polymer (A) is preferably 0.1 to 10 mass %, more preferably 0.5 to 9 mass %, and even more preferably 1 to 8 mass %, relative to 100 mass % of all structural units.

[0024] The polymer (A) preferably has a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, and the content thereof is not particularly limited, but is preferably 5 to 90 mass %, more preferably 10 to 87 mass %, and even more preferably 20 to 85 mass %, relative to 100 mass % of all structural units. The polymer (A) preferably has structural units derived from alkyl (meth)acrylates having an alkyl group with 4 to 12 carbon atoms, and the content thereof is not particularly limited, but is preferably 50 to 100 mass % relative to 100 mass % of structural units derived from alkyl (meth)acrylates having an alkyl group with 1 to 12 carbon atoms, more preferably 60 to 99 mass %, and even more preferably 70 to 98 mass %.

[0025] The polymer (A) may have a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 13 to 30 carbon atoms, and the content thereof is not particularly limited, but is preferably 0 to 40 mass %, more preferably 0 to 30 mass %, and even more preferably 0 to 20 mass %, relative to 100 mass % of all structural units. When the polymer (A) is produced by a phase inversion emulsification method, the polymer (A) preferably has structural units derived from alkyl (meth)acrylates having an alkyl group having 13 to 30 carbon atoms, and the content thereof is preferably 1 to 40 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 20 mass %, relative to 100 mass % of all structural units.

[0026] The polymer (A) preferably has a structural unit derived from a monomer whose homopolymer has a glass transition temperature of −70° C. to −10° C. This further improves the adhesiveness of the composition. In the polymer (A), the proportion of structural units derived from monomers having a homopolymer glass transition temperature of −70° C. to −10° C. is preferably 30 to 90% by mass, more preferably 35 to 85% by mass, and even more preferably 40 to 80% by mass, relative to 100% by mass of all structural units.

[0027] The polymer (A) may contain structural units derived from acid group-containing monomers, but the content thereof is preferably 5% by mass or less relative to 100% by mass of all structural units. This sufficiently prevents the formation of a crosslinked structure due to the reaction between the vinyl ether group in the structural unit represented by formula (1) and the acid group in the acid group-containing monomer. The proportion of structural units derived from acid group-containing monomers is more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and most preferably 0% by mass.

[0028] The polymer (A) may have structural units derived from aromatic vinyl monomers, but the content thereof is preferably 5% by mass or less relative to 100% by mass of all structural units. This allows for more sufficient suppression of discoloration due to ultraviolet light. The proportion of structural units derived from aromatic vinyl monomers is more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and most preferably 0% by mass.

[0029] The above polymer (A) may have structural units represented by the above formula (1), and structural units derived from neutral or basic polar group-containing monomers, alkyl (meth) acrylates having an alkyl group with 1 to 30 carbon atoms, acid group-containing monomers, and other monomers other than structural units derived from aromatic vinyl monomers. The content ratio of the structural units derived from other monomers in the above polymer (A) is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, particularly preferably 0 to 1% by mass, and most preferably 0% by mass based on 100% by mass of all structural units.

[0030] The above polymer (A) preferably has a glass transition temperature (Tg) of -70 to 20 °C. Thereby, the adhesiveness is further improved. More preferably, the Tg is -65 to 15 °C, still more preferably -60 to 10 °C, particularly preferably -55 to 10 °C. The Tg of the polymer (A) can be calculated by the following method. <Tg calculation method> In this specification, the glass transition temperature of the polymer (A) uses the glass transition temperature of the homopolymer of the monomer used in the monomer component constituting the polymer (A), and is represented by the formula (I): 1 / Tg = Σ (Wm / Tgm) / 100 (I) 〔In the formula, Wm represents the content rate (mass%) of the monomer m in the monomer component constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of the homopolymer of the monomer m〕 It means the temperature obtained based on the Fox's formula represented by.

[0031] In the present invention, unless otherwise specified, the glass transition temperature of the polymer (A) means the glass transition temperature obtained based on the above formula (I).

[0032] When the polymer (A) is an emulsion particle having a plurality of resin layers, the glass transition temperature of the entire resin layer constituting the emulsion particle means the glass transition temperature calculated from the mass fraction of each monomer in all the monomer components used in the multistage emulsion polymerization and the glass transition temperature of the homopolymer of the corresponding monomer.

[0033] For monomers with unknown glass transition temperatures, such as special monomers and polyfunctional monomers, if the total amount of monomers with unknown glass transition temperatures in the monomer composition is 10% by mass or less, the glass transition temperature can be determined using only monomers with known glass transition temperatures. If the total amount of monomers with unknown glass transition temperatures in the monomer composition exceeds 10% by mass, the glass transition temperature of the polymer can be determined by differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermomechanical analysis (TMA), etc.

[0034] The glass transition temperature of the polymer (A) can be easily adjusted by adjusting the composition of the monomer components. When the polymer (A) is an emulsion particle, the composition of the monomer components can be determined taking into account the glass transition temperature of the polymer constituting the emulsion particle.

[0035] The polymer (A) may have a single layer structure or may be in the form of emulsion particles having a multilayer structure. An embodiment in which the polymer (A) is in the form of emulsion particles having a multilayer structure is one of the preferred embodiments of the present invention. More preferably, the polymer (A) has a core-shell structure.

[0036] The weight average molecular weight of the polymer (A) is not particularly limited, but is preferably 10,000 to 3,000,000, more preferably 20,000 to 2,500,000, still more preferably 50,000 to 2,000,000, and particularly preferably 70,000 to 1,500,000. The weight average molecular weight can be measured using gel permeation chromatography (Tosoh Corporation, product number: HLC-8320GPC, columns: TSKgel G-5000HXL and TSKgel GMHXL-L used in series).

[0037] The average particle size of the polymer (A) is not particularly limited, but is preferably from 10 to 500 nm, more preferably from 20 to 400 nm, and even more preferably from 30 to 300 nm. The average particle size of the polymer (A) can be measured by the method described in the Examples.

[0038] (Vinyl ether group-containing (meth)acrylic acid ester) The structural unit represented by formula (1) in the polymer (A) can be formed by any method without limitation. For example, the structural unit can be formed by a method represented by the following formula (2): [ka] (In the formula, R 1 represents a hydrogen atom or a methyl group. 2 and R 3 R may be the same or different and represent a hydrogen atom or an organic group. 4 represents a hydrogen atom or an organic group, and n represents an integer of 1 or more. Preferably, the structural unit is formed by polymerization of a vinyl ether group-containing (meth)acrylic acid ester represented by the following formula:

[0039] R in the above formulas (1) and (2) 1 represents a hydrogen atom or a methyl group. 1 is preferably a methyl group, as this provides even better adhesiveness. R in the above formulas (1) and (2) 2 and R 3 are the same or different and represent a hydrogen atom or an organic group. 。 R 2 or R 3Examples of the organic group represented by the formula (I) include linear or cyclic monovalent hydrocarbon groups having 1 to 20 carbon atoms, and hydrocarbon groups in which at least a portion of the atoms constituting the hydrocarbon groups have been substituted with halogen atoms, oxygen atoms, nitrogen atoms, or sulfur atoms.

[0040] The chain hydrocarbon group includes a linear or branched aliphatic hydrocarbon group. The aliphatic hydrocarbon group includes saturated hydrocarbon groups such as alkyl groups, and unsaturated hydrocarbon groups such as alkenyl groups, with saturated hydrocarbon groups being preferred. Specific examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a hexyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, a heptyl group, a 2-methylhexyl group, a 3-methylhexyl group, a 2,2-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3-ethylpentyl group, a 2,2,3-trimethylbutyl group, an octyl group, a methylheptyl group, a dimethylhexyl group, a 2-ethylhexyl group, a 3-ethylhexyl group, a trimethylpentyl group, a 3-ethyl-2-methylpentyl group, a 2-ethyl-3-methylpentyl group, a 2,2,3,3- Tetramethylbutyl group, nonyl group, methyloctyl group, 3,7-dimethyloctyl group, dimethylheptyl group, 3-ethylheptyl group, 4-ethylheptyl group, trimethylhexyl group, 3,3-diethylpentyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc. alkyl groups such as vinyl, n-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 1-pentenyl, 2-pentenyl, 2-methyl-1-butenyl, 2-methyl-2-butenyl, 3-methyl-1-butenyl, 1-hexenyl, 2-hexenyl, 1-heptenyl, 2-heptenyl, 1-octenyl, and 2-octenyl; and the like.

[0041] Examples of the cyclic hydrocarbon group include an alicyclic hydrocarbon group and an aromatic hydrocarbon group. Examples of the alicyclic hydrocarbon group include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclododecyl groups. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, a biphenyl group, a methoxyphenyl group, a trichlorophenyl group, an ethylphenyl group, a tolyl group, a xylyl group, and a benzyl group. The halogen atom is preferably chlorine, bromine or fluorine, and more preferably fluorine.

[0042] Among these, the organic group is preferably an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, or an aromatic hydrocarbon group having 6 to 11 carbon atoms, and more preferably an alkyl group having 1 to 2 carbon atoms, a halogenated alkyl group having 1 to 2 carbon atoms, or an aromatic hydrocarbon group having 6 to 8 carbon atoms.

[0043] R in the above formulas (1) and (2) 4 represents a hydrogen atom or an organic group. R 4 Examples of the organic group represented by the formula include the above-mentioned R 2 and R 3 Among them, the organic groups represented by R 4 is preferably a linear or cyclic hydrocarbon group having 1 to 11 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 11 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms.

[0044] In the above formulas (1) and (2), n is an integer of 1 or more, preferably 1 to 10, more preferably 1 to 8, even more preferably 1 to 6, particularly preferably 1 to 4, and most preferably 2.

[0045] Specific examples of vinyl ether group-containing (meth)acrylic acid esters represented by the above formula (2) include 2-vinyloxyethyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate, and polyethylene glycol monovinyl ether (meth)acrylate. Of these, 2-(vinyloxyethoxy)ethyl (meth)acrylate and 2-vinyloxyethyl (meth)acrylate are preferred, and 2-(vinyloxyethoxy)ethyl (meth)acrylate is more preferred.

[0046] (Neutral or basic polar group-containing monomer) The polymer (A) preferably has a structural unit derived from a neutral or basic polar group-containing monomer. In this specification, the term "structural unit derived from a monomer" refers to a structural unit having the same structure as a structural unit formed by polymerization of a monomer (a structure in which the ethylenically unsaturated double bond of a monomer having each unsaturated double bond is opened (a structure in which the double bond (C=C) becomes a single bond (-CC-))). Note that the structural unit having the same structure as a structural unit formed by polymerization of a monomer is not limited to only a structural unit formed by actual polymerization of a monomer, but may also be a structural unit formed by another method as long as it has the same structure as a structural unit formed by polymerization of a monomer.

[0047] The neutral polar group in the neutral polar group-containing monomer is not particularly limited, but examples thereof include a hydroxyl group, an amide group, an ether group, a maleimide group, an isocyanate group, and an oxazoline group. Examples of the monomer having a hydroxyl group include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxy(meth)acrylate, and 4-hydroxymethylcyclohexylmethyl (meth)acrylate.

[0048] Examples of the monomer having an amide group include (meth)acrylamides such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropylacrylamide, N-butyl(meth)acrylamide, N,N-butoxymethyl(meth)acrylamide, N-methylol(meth)acrylamide, acrylloylmorpholine, and diacetone(meth)acrylamide; and lactam monomers such as N-vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, and 1-(2-propenyl)-2-pyrrolidone. Among these, (meth)acrylamides such as diacetone(meth)acrylamide are preferred, and diacetoneacrylamide is more preferred.

[0049] Examples of the monomer having an ether group include cyclic ether group-containing (meth)acrylates such as glycidyl (meth)acrylate, (3,4-epoxycyclohexyl)methyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and (3-ethyloxetan-3-yl)methyl (meth)acrylate; and alkyl ether group-containing (meth)acrylates such as 3-methoxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 2-methoxybutyl (meth)acrylate.

[0050] Examples of the monomer having a maleimide group include N-phenylmaleimide, N-cyclohexylmaleimide, N-laurylmaleimide, N-hexadecylmaleimide, and N-stearylmaleimide. Examples of the monomer having an isocyanate group include 2-(meth)acroyloxyethyl isocyanate and (meth)acroyl isocyanate. An example of a monomer having an oxazoline group is 2-isopropenyl-2-oxazoline.

[0051] The basic polar group in the basic polar group-containing monomer is not particularly limited, and examples thereof include amino groups such as primary to tertiary amino groups, quaternary ammonium salt groups, etc. The amino group may be cyclic or acyclic, but is preferably an acyclic amino group. Examples of the monomer having an acyclic amino group include N,N-dialkylamino group-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and N,N-diethylaminopropyl (meth)acrylate, as well as monomers obtained by adding a quaternizing agent to the above-mentioned monomers, or neutralized products thereof with an acid such as hydrochloric acid or acetic acid; N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylate, and the like. N,N-dialkylamino group-containing (meth)acrylamides such as methacrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide, and monomers obtained by adding a quaternizing agent to the above monomers, or products thereof neutralized with an acid such as hydrochloric acid; monoalkylamino group-containing (meth)acrylates such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate, and products thereof neutralized with an acid such as hydrochloric acid; monoalkylamino group-containing (meth)acrylamides such as monomethylaminoethyl (meth)acrylamide, monoethylaminoethyl (meth)acrylamide, monomethylaminopropyl (meth)acrylamide, monoethylaminopropyl (meth)acrylamide, and products thereof neutralized with an acid such as hydrochloric acid; esters of (meth)acrylic acid and alkanolamines such as 2-aminoethyl (meth)acrylate. and their neutralization with an acid such as hydrochloric acid; N,N-diallylmethylamine and a monomer obtained by adding a quaternizing agent thereto, or a neutralization product thereof with an acid such as hydrochloric acid; allylamine and a neutralization product thereof with an acid such as hydrochloric acid; addition reaction products of unsaturated monomers having a cyclic ether-containing group having 2 to 8 carbon atoms, such as 1-allyloxy-3-dibutylamino-2-ol and 1-allyloxy-3-diethanolamino-2-ol, with an amine compound having 1 to 24 carbon atoms, and a monomer obtained by adding a quaternizing agent thereto, or a neutralization product thereof with an acid such as hydrochloric acid.

[0052] The amine compound having 1 to 24 carbon atoms is not particularly limited as long as it has an amino group and can react with the cyclic ether structure of an unsaturated monomer having a cyclic ether-containing group having 2 to 8 carbon atoms. The number of carbon atoms in the amine compound having 1 to 24 carbon atoms is preferably 1 to 20, and more preferably 1 to 16. Examples of the amine compound having 1 to 24 carbon atoms include primary amines and secondary amines, such as (di)alkylamines having 1 to 24 carbon atoms, (di)alkanolamines having 1 to 24 carbon atoms, and alkylalkanolamines having 1 to 24 carbon atoms. Preferred examples of the (di)alkylamine having 1 to 24 carbon atoms include methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, pentylamine, dipentylamine, hexylamine, dihexylamine, heptylamine, diheptylamine, octylamine, dioctylamine, dodecylamine, and didodecylamine. Preferred examples of the (di)alkanolamine having 1 to 24 carbon atoms include methanolamine, ethanolamine, propanolamine, butanolamine, dimethanolamine, diethanolamine, dipropanolamine, dibutanolamine, and hexanolamine. As the alkylalkanolamine having 1 to 24 carbon atoms, methylethanolamine and the like are preferred.

[0053] As the acyclic amino group-containing monomer, preferred are N,N-dialkylamino group-containing (meth)acrylates and their neutralization products with acids such as hydrochloric acid, and monomers obtained by adding a quaternizing agent to these; N,N-dialkylamino group-containing (meth)acrylamides and their neutralization products with acids such as hydrochloric acid, and monomers obtained by adding a quaternizing agent to these; and among these, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide and their neutralization products with acids such as hydrochloric acid, and monomers obtained by adding a quaternizing agent to these are more preferred. The quaternizing agent is not particularly limited, but examples thereof include common alkylating agents such as alkyl halides such as methyl chloride, ethyl chloride, methyl bromide, and methyl iodide; and alkyl sulfates such as dimethyl sulfate, diethyl sulfate, and di-n-propyl sulfate.

[0054] Examples of the monomer having a cyclic amino group include 1,2,2,6,6-pentamethyl-4-piperidyl(meth)acrylate, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyl-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino- Examples of the monomer include piperidyl group-containing monomers such as 2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine. Of these, 1,2,2,6,6-pentamethyl-4-piperidyl(meth)acrylate or 2,2,6,6-tetramethyl-4-piperidyl(meth)acrylate is preferred.

[0055] The neutral or basic polar group-containing monomer preferably includes at least one selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, and a hydroxyl group-containing monomer. The polar group-containing monomer is more preferably an amino group-containing monomer. In addition, when a monomer has an amino group and an amide group, it is classified as an amino group-containing monomer in this specification.

[0056] (Alkyl (meth)acrylate) The alkyl (meth)acrylate having an alkyl group of 1 to 12 carbon atoms is not particularly limited, but the alkyl group preferably has 2 to 12 carbon atoms, and more preferably 4 to 12 carbon atoms. Examples of the alkyl(meth)acrylate having an alkyl group having 1 to 12 carbon atoms include methyl(meth)acrylate, ethyl(meth)acrylate, 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, sec-pentyl(meth)acrylate, tert-pentyl(meth)acrylate, and neopentyl(meth)acrylate. (meth)acrylate, 1-methylpentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, sec-hexyl (meth)acrylate, tert-hexyl (meth)acrylate, neohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, isoheptyl (meth)acrylate, sec-heptyl (meth)acrylate, tert-heptyl (meth)acrylate, neoheptyl (meth)acrylate, n-octyl (meth)acrylate, 2-Octyl (meth)acrylate, isooctyl (meth)acrylate, sec-octyl (meth)acrylate, tert-octyl (meth)acrylate, neooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, sec-nonyl (meth)acrylate, tert-nonyl (meth)acrylate, neononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, sec-decyl (meth)acrylate, tert-decyl (meth)acrylate, neodecyl (Meth)acrylate, n-undecyl (meth)acrylate, isoundecyl (meth)acrylate, sec-undecyl (meth)acrylate, tert-undecyl (meth)acrylate, neoundecyl (meth)acrylate, n-dodecyl (meth)acrylate, isododecyl (meth)acrylate, sec-dodecyl (meth)acrylate, tert-dodecyl (meth)acrylate, neododecyl (meth)acrylate, cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate,Examples include cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. One or more of these can be used. Among these, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, sec-pentyl (meth)acrylate, tert-pentyl (meth)acrylate, neopentyl (meth)acrylate, 1-methylpentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, sec-hexyl (meth)acrylate, and tert-hexyl (Meth)acrylate, neohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, isoheptyl (meth)acrylate, sec-heptyl (meth)acrylate, tert-heptyl (meth)acrylate, neoheptyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, sec-octyl (meth)acrylate, tert-octyl (meth)acrylate, neooctyl (meth)acrylate, n-nonyl (Meth)acrylate, isononyl (meth)acrylate, sec-nonyl (meth)acrylate, tert-nonyl (meth)acrylate, neononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, sec-decyl (meth)acrylate, tert-decyl (meth)acrylate, neodecyl (meth)acrylate, n-undecyl (meth)acrylate, isoundecyl (meth)acrylate, sec-undecyl (meth)acrylate, tert-undecyl (meth)acrylate, neoundecyl ( (meth)acrylate, n-dodecyl (meth)acrylate, isododecyl (meth)acrylate, sec-dodecyl (meth)acrylate, tert-dodecyl (meth)acrylate, neododecyl (meth)acrylate, more preferably n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, sec-pentyl (meth)acrylate, neopentyl (meth)acrylate, 1-methylpentyl (meth)acrylate,n-Hexyl (meth)acrylate, isohexyl (meth)acrylate, sec-hexyl (meth)acrylate, neohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, isoheptyl (meth)acrylate, sec-heptyl (meth)acrylate, neoheptyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, sec-octyl (meth)acrylate, neooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, sec-nonyl (meth)acrylate, neononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, sec-decyl (meth)acrylate, neodecyl (meth)acrylate Preferred are n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, sec-nonyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, and isododecyl (meth)acrylate. ,

[0057] The alkyl (meth)acrylate having an alkyl group with 13 to 30 carbon atoms is not particularly limited, but the alkyl group preferably has 14 to 25 carbon atoms, and more preferably 15 to 20 carbon atoms. Examples of the alkyl(meth)acrylate having an alkyl group having 13 to 30 carbon atoms include n-tridecyl(meth)acrylate, isotridecyl(meth)acrylate, sec-tridecyl(meth)acrylate, tert-tridecyl(meth)acrylate, neotridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, isotetradecyl(meth)acrylate, sec-tetradecyl(meth)acrylate, tert-tetradecyl(meth)acrylate, neotetradecyl(meth)acrylate, n-pentadecyl(meth)acrylate, ) acrylate, isopentadecyl (meth)acrylate, sec-pentadecyl (meth)acrylate, tert-pentadecyl (meth)acrylate, neopentadecyl (meth)acrylate, n-hexadecyl (meth)acrylate, isohexadecyl (meth)acrylate, sec-hexadecyl (meth)acrylate, tert-hexadecyl (meth)acrylate, neohexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, sec-heptadecyl (meth)acrylate, t ert-heptadecyl (meth)acrylate, neoheptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, sec-octadecyl (meth)acrylate, tert-octadecyl (meth)acrylate, neooctadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, isononadecyl (meth)acrylate, sec-nonadecyl (meth)acrylate, tert-nonadecyl (meth)acrylate, neononadecyl (meth)acrylate, n-icosyl (meth)acrylate acrylate, isohenicosyl (meth)acrylate, sec-henicosyl (meth)acrylate, tert-henicosyl (meth)acrylate, neohenicosyl (meth)acrylate, n-henicosyl (meth)acrylate, isohenicosyl (meth)acrylate, sec-henicosyl (meth)acrylate, tert-henicosyl (meth)acrylate, neohenicosyl (meth)acrylate, n-docosyl (meth)acrylate, isodocosyl (meth)acrylate, sec-docosyl (meth)acrylate, tert-docosyl (meth)acrylate,Neodocosyl(meth)acrylate, n-tricosyl(meth)acrylate, isotricosyl(meth)acrylate, sec-tricosyl(meth)acrylate, tert-tricosyl(meth)acrylate, neotricosyl(meth)acrylate, n-tetracosyl(meth)acrylate, isotetracosyl(meth)acrylate, sec-tetracosyl(meth)acrylate, tert-tetracosyl(meth)acrylate, neotetracosyl(meth)acrylate ) acrylate, n-pentacosyl (meth)acrylate, isopentacosyl (meth)acrylate, sec-pentacosyl (meth)acrylate, tert-pentacosyl (meth)acrylate, neopentacosyl (meth)acrylate, n-hexacosyl (meth)acrylate, isohexacosyl (meth)acrylate, sec-hexacosyl (meth)acrylate, tert-hexacosyl (meth)acrylate, neohexacosyl (meth)acrylate acrylate, n-heptacosyl (meth)acrylate, isoheptacosyl (meth)acrylate, sec-heptacosyl (meth)acrylate, tert-heptacosyl (meth)acrylate, neoheptacosyl (meth)acrylate, n-octacosyl (meth)acrylate, isooctacosyl (meth)acrylate, sec-octacosyl (meth)acrylate, tert-octacosyl (meth)acrylate, neooctacosyl (meth)acrylate, n- Examples include nonacosyl (meth)acrylate, isononacosyl (meth)acrylate, sec-nonacosyl (meth)acrylate, tert-nonacosyl (meth)acrylate, neononacosyl (meth)acrylate, n-triacontyl (meth)acrylate, isotriacontyl (meth)acrylate, sec-triacontyl (meth)acrylate, tert-triacontyl (meth)acrylate, and neotriacontyl (meth)acrylate. One or more of these can be used. Among these, n-hexadecyl (meth)acrylate, isohexadecyl (meth)acrylate, sec-hexadecyl (meth)acrylate, tert-hexadecyl (meth)acrylate, neohexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, sec-heptadecyl (meth)acrylate, tert-heptadecyl (meth)acrylate, neoheptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, sec -Octadecyl (meth)acrylate, tert-octadecyl (meth)acrylate, neooctadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, isononadecyl (meth)acrylate, sec-nonadecyl (meth)acrylate, tert-nonadecyl (meth)acrylate, neononadecyl (meth)acrylate, n-icosyl (meth)acrylate, isoicosyl (meth)acrylate, sec-icosyl (meth)acrylate, tert-icosyl (meth)acrylate, neoicosyl (meth)acrylate, n-henicosyl Docosyl (meth)acrylate, isohexadecyl (meth)acrylate, sec-hexadecyl (meth)acrylate, tert-hexadecyl (meth)acrylate, neohexadecyl (meth)acrylate, n-docosyl (meth)acrylate, isodocosyl (meth)acrylate, sec-docosyl (meth)acrylate, tert-docosyl (meth)acrylate, neodocosyl (meth)acrylate, n-tricosyl (meth)acrylate, isotricosyl (meth)acrylate, sec-tricosyl (meth)acrylate, tert-tricosyl Sil(meth)acrylate, neotricosyl(meth)acrylate, n-tetracosyl(meth)acrylate, isotetracosyl(meth)acrylate, sec-tetracosyl(meth)acrylate, tert-tetracosyl(meth)acrylate, neotetracosyl(meth)acrylate, n-pentacosyl(meth)acrylate, isopentacosyl(meth)acrylate, sec-pentacosyl(meth)acrylate, tert-pentacosyl(meth)acrylate, neopentacosyl(meth)acrylate, n-hexacosyl(meth)acrylate,Isohexacosyl (meth)acrylate, sec-hexacosyl (meth)acrylate, tert-hexacosyl (meth)acrylate, and neohexacosyl (meth)acrylate are preferred, and n-hexadecyl (meth)acrylate, isohexadecyl (meth)acrylate, sec-hexadecyl (meth)acrylate, tert-hexadecyl (meth)acrylate, neohexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, and sec-heptadecyl (meth)acrylate are more preferred. ester, tert-heptadecyl (meth)acrylate, neoheptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, sec-octadecyl (meth)acrylate, tert-octadecyl (meth)acrylate, neooctadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, isononadecyl (meth)acrylate, sec-nonadecyl (meth)acrylate, tert-nonadecyl (meth)acrylate, neononadecyl (meth)acrylate, n-icosyl (meth)acrylate n-Henicosyl (meth)acrylate, isohenicosyl (meth)acrylate, sec-Henicosyl (meth)acrylate, tert-Henicosyl (meth)acrylate, neohenicosyl (meth)acrylate, n-Henicosyl (meth)acrylate, isohenicosyl (meth)acrylate, sec-Henicosyl (meth)acrylate, tert-Henicosyl (meth)acrylate, neohenicosyl (meth)acrylate, n-Docosyl (meth)acrylate, isodocosyl (meth)acrylate, sec-Docosyl (meth)acrylate, tert-Docosyl (meth) )acrylate, neodocosyl(meth)acrylate, n-tricosyl(meth)acrylate, isotricosyl(meth)acrylate, sec-tricosyl(meth)acrylate, tert-tricosyl(meth)acrylate, neotricosyl(meth)acrylate, n-tetracosyl(meth)acrylate, isotetracosyl(meth)acrylate, sec-tetracosyl(meth)acrylate, tert-tetracosyl(meth)acrylate, and neotetracosyl(meth)acrylate are more preferred, and n-hexadecyl(meth)acrylate andIsohexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isooctadecyl (meth)acrylate, n-nonadecyl (meth)acrylate, isononadecyl (meth)acrylate, n-icosyl (meth)acrylate, isoicosyl (meth)acrylate, n-henicosyl (meth)acrylate, isohenicosyl (meth)acrylate, n-docosyl (meth)acrylate, and isodocosyl (meth)acrylate.

[0058] (Acid group-containing monomer) The acid group-containing monomer is not particularly limited as long as it is a monomer having an acid group, and examples thereof include unsaturated monocarboxylic acid monomers such as (meth)acrylic acid, crotonic acid, tiglic acid, 3-methylcrotonic acid, 2-methyl-2-pentenoic acid, itaconic acid, etc., and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts; unsaturated monocarboxylic acid monomers such as maleic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, etc., and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts; and their anhydrides or half esters. carboxylic acid monomers; unsaturated sulfonic acid monomers such as vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-acrylamidopropanesulfonic acid, 2-methacrylamidopropanesulfonic acid, and 2-methacrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, methallyl sulfonic acid, allyloxybenzenesulfonic acid, and 2-hydroxy-3-(2-propenyloxy)propanesulfonic acid. In addition, when a monomer has an acid group and a neutral or basic polar group, it is classified as an acid group-containing monomer in this specification.

[0059] (aromatic vinyl monomer) The aromatic vinyl monomer is not particularly limited, but examples thereof include alkylstyrenes in which the alkyl group has 1 to 4 carbon atoms, such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, tert-methylstyrene, o-tert-butylstyrene, m-tert-butylstyrene, and p-tert-butylstyrene; o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, and p-ethoxystyrene. Examples of the styrene include styrene, alkoxystyrenes in which the alkoxy group has 1 to 4 carbon atoms, such as o-tert-butoxystyrene, m-tert-butoxystyrene, and p-tert-butoxystyrene; halogen atom-containing styrenes, such as o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, o-bromostyrene, m-bromostyrene, and p-bromostyrene; acetoxystyrenes, such as o-acetoxystyrene, m-acetoxystyrene, and p-acetoxystyrene; and vinyltoluene.

[0060] (Other monomers) The polymer (A) may have structural units derived from other monomers other than the structural units represented by the formula (1) and the structural units derived from the neutral or basic polar group-containing monomer, the alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms, the acid group-containing monomer, and the aromatic vinyl monomer. The other monomer is not particularly limited, and examples thereof include (meth)acrylic acid esters such as dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-(acetoacetoxy)ethyl (meth)acrylate, and allyl (meth)acrylate;

[0061] Polymerizable cyclic lactone monomers such as methylene butyrolactone and methylmethylene butyrolactone; Examples of the alkoxylated phenylphenol (meth)acrylate include 1,4-dioxaspiro[4,5]dec-2-yl methacrylic acid, (meth)acryloylmorpholine, tetrahydrofurfuryl acrylate, 4-(meth)acryloyloxymethyl-2-methyl-2-ethyl-1,3-dioxolane, 4-(meth)acryloyloxymethyl-2-methyl-2-isobutyl-1,3-dioxolane, 4-(meth)acryloyloxymethyl-2-methyl-2-cyclohexyl-1,3-dioxolane, 4-(meth)acryloyloxymethyl-2,2-dimethyl-1,3-dioxolane, alkoxylated phenylphenol (meth)acrylate, and polyfunctional monomers.

[0062] Examples of the polyfunctional monomers include triallyl compounds having 9 to 20 carbon atoms, such as triallyl cyanurate (triallyl cyanurate), triallyl isocyanurate, triallyl phosphate, and triallylamine; ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and ethylene oxide-modified 1,6-hexanediol di(meth)acrylate. di(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as 1,9-nonanediol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate having an added mole number of ethylene oxide of 2 to 50, polypropylene glycol di(meth)acrylate having an added mole number of propylene oxide of 2 to 50, and tripropylene glycol di(meth)acrylate; Alkyl di(meth)acrylates having 2 to 4 alkylene oxide groups added in a mole number of 2 to 50; ethoxylated glycerin tri(meth)acrylate, propylene oxide-modified glycerol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol monohydroxytri(meth)acrylate, trimethylolpropane triethoxytri(meth)acrylate, pentaerythritol tri(meth)acrylate Tri(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as acrylate; tetra(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate; penta(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as pentaerythritol penta(meth)acrylate and dipentaerythritol (monohydroxy)penta(meth)acrylate;Examples of suitable hexa(meth)acrylates include hexa(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, such as pentaerythritol hexa(meth)acrylate and dipentaerythritol hexa(meth)acrylate; epoxy group-containing (meth)acrylates, such as bisphenol A di(meth)acrylate, 2-(2'-vinyloxyethoxyethyl)(meth)acrylate and epoxy(meth)acrylate; and polyfunctional (meth)acrylates, such as urethane(meth)acrylate. Among these, preferred are hexa(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms, and more preferred is pentaerythritol hexa(meth)acrylate.

[0063] The polymer (A) preferably has a structural unit derived from a monomer whose homopolymer has a glass transition temperature of −70° C. to −10° C. This brings the glass transition temperature of the polymer (A) into a suitable range. The monomer having a homopolymer glass transition temperature of -70°C to -10°C is not particularly limited, but examples thereof include 2-ethylhexyl acrylate, n-butyl acrylate, 2-octyl acrylate, isoamyl acrylate, and ethyl acrylate. The glass transition temperature is more preferably from -70 to -15°C, and even more preferably from -70 to -20°C.

[0064] (Method for producing polymer (A)) The method for producing the polymer (A) is not particularly limited, but it can be produced by polymerizing a monomer component containing a vinyl ether group-containing (meth)acrylic acid ester represented by the formula (2) above. The present invention also relates to a method for producing a pressure-sensitive adhesive composition, which includes a step of polymerizing a monomer component containing a vinyl ether group-containing (meth)acrylic acid ester represented by the above formula (2) (hereinafter also referred to as a polymerization step). Specific examples and preferred forms of the monomer components used in the production of the polymer (A) and the ratio of the monomer components are the same as those described above for the polymer (A).

[0065] The method for polymerizing the above-mentioned monomer components is not particularly limited, but emulsion polymerization is preferred. The method for emulsion polymerizing the monomer components is not particularly limited, and examples thereof include a method in which an emulsifier is dissolved in a medium such as an aqueous medium, and then the monomer components and a polymerization initiator are added dropwise, and a method in which the monomer components, which have been emulsified in advance using an emulsifier and water, are added dropwise to water or an aqueous medium. The amount of the medium used in the emulsion polymerization may be appropriately determined taking into consideration the amount of nonvolatile components contained in the resulting pressure-sensitive adhesive composition.

[0066] Common emulsification methods include adding an emulsifier to water, then adding the oil component and stirring using a disperser, etc.; adding an emulsifier to the oil component and then pouring it into a large amount of water (hereinafter referred to as the natural emulsification method); and phase inversion emulsification, in which water is added little by little to liquid oil to which an emulsifier has been added while stirring. In phase inversion emulsification, when an aqueous solvent such as water is added to oil droplets, a W / O emulsion is first created. As the amount of aqueous solvent increases, the emulsion thickens and eventually inverts to an O / W emulsion. Phase inversion emulsification is characterized by passing through a phase inversion point, where the particles and the continuous phase that dispersed them are replaced by sufficient shear force to create an emulsion with a narrow particle size distribution and uniform small particle size. Emulsions obtained by phase inversion emulsification are also known to have particularly excellent stability. In the method for producing the polymer (A), the use of a phase inversion emulsification method makes it possible to more sufficiently increase the proportion of the vinyl ether group-containing (meth)acrylic acid ester represented by the formula (2) in the monomer component.

[0067] When the phase inversion emulsification method is used, it is preferable to prepare a composition containing monomer emulsion particles by mixing a monomer component with an aqueous medium, heating the resulting mixture with stirring from the phase inversion temperature of the mixture to a temperature equal to the boiling point of the aqueous medium, and then cooling the mixture to a temperature lower than the phase inversion temperature of the mixture. A preferred embodiment of the present invention is a method for producing the polymer (A) comprising the steps of: mixing a monomer component with an aqueous medium; heating the mixture obtained in the mixing step to a temperature from the phase inversion temperature of the mixture to the boiling point of the aqueous medium while stirring; cooling the mixture obtained after the heating step to a temperature lower than the phase inversion temperature of the mixture; and polymerizing the mixture obtained in the cooling step. In the above mixing step, the monomer component, the aqueous medium, and the emulsifier are preferably mixed together.

[0068] When the phase inversion emulsification method is used, it is preferable to further mix an ester compound having 15 or more carbon atoms in addition to the monomer component, the aqueous medium, and the emulsifier in the mixing step, which further improves the dispersion stability of the resulting monomer emulsion particles. The ester compound may be an ester of a carboxylic acid and an alcohol, and may have 15 or more carbon atoms. The ester compound preferably has 15 to 60 carbon atoms, more preferably 15 to 50 carbon atoms, even more preferably 18 to 40 carbon atoms, and even more preferably 22 to 40 carbon atoms.

[0069] The number of carbon atoms in the carboxylic acid constituting the ester compound is not particularly limited as long as the ester compound has 15 or more carbon atoms, but is preferably 2 to 50, more preferably 4 to 40, even more preferably 5 to 30, and particularly preferably 8 to 20.

[0070] The carboxylic acid may be a saturated fatty acid or an unsaturated fatty acid. Examples of the carboxylic acid include saturated fatty acids such as acetic acid, propionic acid, butyric acid, valeric acid, pivalic acid, caproic acid, enanthic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, and arachidic acid; and acrylic acid, methacrylic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid (paulic acid), erucic acid, and nervonic acid. monounsaturated fatty acids; diunsaturated fatty acids such as linoleic acid, eicosadienoic acid, and docosadienoic acid; triunsaturated fatty acids such as α-linolenic acid, γ-linolenic acid, pinolenic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, and eicosatrienoic acid; tetraunsaturated fatty acids such as stearidonic acid, arachidonic acid, eicosatetraenoic acid, and adrenic acid; pentaunsaturated fatty acids such as bosseopentaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, osbondo acid, sardine acid, and tetracosapentaenoic acid; and hexaunsaturated fatty acids such as docosahexaenoic acid and herring acid.

[0071] The carboxylic acid is preferably an unsaturated fatty acid, more preferably an unsaturated fatty acid having a polymerizable unsaturated bond, and even more preferably acrylic acid or methacrylic acid.

[0072] The number of carbon atoms of the alcohol constituting the ester compound is not particularly limited as long as the ester compound has 15 or more carbon atoms, but is preferably 2 to 50, more preferably 4 to 40, even more preferably 5 to 30, and particularly preferably 8 to 20.

[0073] The alcohol may be a saturated alcohol or an unsaturated alcohol. Examples of the saturated alcohol include aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, and stearyl alcohol; and alicyclic alcohols such as cyclohexanol. Examples of the unsaturated alcohol include (meth)allyl alcohol, 3-buten-1-ol, and 3-methyl-3-buten-1-ol.

[0074] Specific examples of the ester compounds having 15 or more carbon atoms include the above-mentioned alkyl (meth)acrylates having an alkyl group having 13 to 30 carbon atoms; hexadecyl 2-ethylhexanoate, myristyl myristate, stearyl myristate, stearyl 2-ethylhexanoate, stearyl stearate; ethyl myristate, isopropyl myristate, butyl myristate, ethyl palmitate, ethyl stearate, and 2-ethylhexyl stearate. Among these, alkyl (meth)acrylates having an alkyl group with 13 to 30 carbon atoms are preferred. When the ester compound having 15 or more carbon atoms is a compound having a polymerizable unsaturated bond, such as an alkyl (meth)acrylate having an alkyl group having 13 to 30 carbon atoms, the ester compound having 15 or more carbon atoms may be mixed as a monomer component in the mixing step.

[0075] The amount of the ester compound having 15 or more carbon atoms used in the mixing step is preferably 1 to 50% by mass, more preferably 3 to 50% by mass, even more preferably 5 to 50% by mass, still more preferably 5 to 45% by mass, still more preferably 5 to 40% by mass, and particularly preferably 5 to 35% by mass, relative to 100% by mass of the monomer component.

[0076] Examples of aqueous media include water and mixed solvents of water and water-soluble organic solvents. Examples of water-soluble organic solvents include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and tert-butyl alcohol; polyhydric alcohols such as ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, and diethylene glycol; and ketones such as acetone and methyl ethyl ketone. These organic solvents may be used alone or in combination of two or more. The proportion of water in the mixed solvent is preferably 50% by mass or more. When a phase inversion emulsification method is used, a water proportion of 50% by mass or more can further improve the dispersion stability of the monomer emulsion particles. The water proportion is more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. The use of water as the aqueous solvent is one of the preferred embodiments of the present invention.

[0077] The mass ratio of the monomer component to the aqueous medium (monomer component / aqueous medium) is preferably 20 / 80 to 50 / 50. This allows the monomer component and the aqueous medium to be dispersed more uniformly. The mass ratio is more preferably 25 / 75 to 45 / 55, and even more preferably 30 / 70 to 40 / 60.

[0078] The temperature at which the monomer component and the aqueous medium are mixed can be set in consideration of the phase inversion temperature of the mixture of the monomer component and the aqueous medium, and is usually preferably 5 to 45°C, more preferably 5 to 40°C, and even more preferably 5 to 35°C. When mixing the monomer component with the aqueous medium, it is preferable to add the monomer component to the aqueous medium under stirring in order to disperse the monomer component uniformly in the aqueous medium. The means for stirring the aqueous medium is not particularly limited, and for example, the monomer component can be uniformly dispersed in the aqueous medium using a simple stirring device such as a stirring rod or a magnetic stirrer, and there is no need to use special devices such as a mixer for high-viscosity paints or a high-pressure homogenizer.

[0079] Regarding the phase inversion temperatures in the heating step, the lowest phase inversion temperature is defined as the phase inversion start temperature, and the highest phase inversion temperature is defined as the phase inversion end temperature. The phase inversion temperature is not particularly limited, but from the viewpoint of dispersion stability of the monomer emulsion particles, the phase inversion starting temperature is preferably 35°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher. From the viewpoint of stability of the monomer emulsion, the phase inversion ending temperature is preferably 98°C or lower, more preferably 97°C or lower, and even more preferably 96°C or lower.

[0080] The atmosphere in the heating step is not particularly limited, but is preferably an inert gas atmosphere such as nitrogen gas or argon gas, from the viewpoint of avoiding the influence of oxygen contained in the air.

[0081] From the viewpoint of dispersion stability of the monomer emulsion particles, the lower limit of the heating temperature (maximum temperature when heated) of the mixture in the heating step is preferably a temperature equal to or higher than the phase inversion start temperature of the mixture, more preferably a temperature 0.5°C or higher than the phase inversion start temperature, and even more preferably a temperature 1°C or higher than the phase inversion start temperature. Also, from the viewpoint of dispersion stability of the monomer emulsion particles, the lower limit of the heating temperature (maximum temperature when heated) of the mixture is preferably a temperature equal to or higher than the phase inversion end temperature of the mixture, and more preferably 0.5°C or higher than the phase inversion end temperature of the mixture.

[0082] The upper limit of the heating temperature (maximum temperature when heated) of the mixture is usually a temperature below the boiling point of the aqueous medium, preferably a temperature that is 3°C or more lower than the boiling point of the aqueous medium, and more preferably a temperature that is 5°C or more lower than the boiling point of the aqueous medium.

[0083] The cooling step is not particularly limited as long as the mixture is cooled to a temperature equal to or lower than the phase inversion temperature of the mixture. For example, the mixture may be cooled by standing to cool or by air cooling. In the cooling step, the mixture is preferably cooled to a temperature that is at least 10°C lower than the phase inversion onset temperature of the mixture. The temperature to which the mixture is cooled in the cooling step is more preferably at least 20°C lower than the phase inversion onset temperature of the mixture, even more preferably at least 25°C lower than the phase inversion onset temperature, and even more preferably at least 30°C lower than the phase inversion onset temperature.

[0084] Examples of the emulsifier include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and polymeric emulsifiers. These emulsifiers may be used alone or in combination of two or more.

[0085] The anionic emulsifier is not particularly limited, and examples thereof include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate and sodium dodecyl sulfonate; alkylaryl sulfonate salts such as ammonium dodecylbenzenesulfonate and sodium dodecylnaphthalenesulfonate; polyoxyalkylene alkenyl ether sulfate salts such as ammonium polyoxyalkylene alkenyl ether sulfate (for example, manufactured by Kao Corporation, trade name: Ramtel PD-104); polyoxyethylene alkyl sulfate salts; polyoxyethylene alkylaryl sulfate salts; dialkyl sulfosuccinates; arylsulfonic acid-formalin condensates; fatty acid salts such as ammonium laurate and sodium stearylate; and the like. One or more of these may be used.

[0086] The nonionic emulsifier is not particularly limited, but examples thereof include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, condensates of polyethylene glycol and polypropylene glycol, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, and condensates of ethylene oxide and aliphatic amines, and one or more of these can be used.

[0087] When the phase inversion emulsification method is used as the emulsification method, it is preferable to use a nonionic emulsifier. The HLB (hydrophilic-lipophilic balance) of the nonionic emulsifier is preferably 8 or more, more preferably 9 or more, and even more preferably 10 or more, from the viewpoint of improving the dispersion stability of the monomer emulsion particles; and is preferably 17 or less, more preferably 16 or less, and even more preferably 15 or less, from the viewpoint of improving the dispersion stability of the monomer emulsion particles. Furthermore, from the viewpoint of obtaining monomer emulsion particles having a fine particle size, the HLB of the nonionic emulsifier is preferably 14 or less, more preferably 13.5 or less, and even more preferably 13 or less. Therefore, the HLB of the nonionic emulsifier is preferably 8 to 17, more preferably 9 to 16, even more preferably 9 to 15, even more preferably 10 to 14, even more preferably 10 to 13.5, and particularly preferably 10 to 13. The HLB of the nonionic emulsifier is calculated based on the Griffin method using the formula: [HLB of nonionic emulsifier] = 20 × [(molecular weight of hydrophilic part) / (molecular weight of emulsifier)] This is the value calculated by

[0088] The cationic emulsifier is not particularly limited, but examples thereof include alkyl ammonium salts such as dodecyl ammonium chloride, and one or more of these can be used.

[0089] The amphoteric emulsifier is not particularly limited, but examples thereof include betaine ester emulsifiers, and one or more of these can be used.

[0090] The polymer emulsifier is not particularly limited, but examples thereof include poly(meth)acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinylpyrrolidone; polyhydroxyalkyl(meth)acrylates such as polyhydroxyethyl acrylate; and polymers containing one or more of the monomers constituting these polymers as copolymerization components, and one or more of these may be used.

[0091] In addition, as the emulsifier, an emulsifier having a reactive group, i.e., a so-called reactive emulsifier, is preferred from the viewpoint of more fully incorporating the emulsifier into the monomer emulsion particles. When a phase inversion emulsification method is used as the emulsification method, a reactive nonionic emulsifier is preferred.

[0092] The reactive emulsifier is not particularly limited, and examples thereof include propenyl-alkyl sulfosuccinate salts, (meth)acrylic acid polyoxyethylene sulfonate salts, (meth)acrylic acid polyoxyethylene phosphonate salts (e.g., Sanyo Chemical Industries, Ltd., trade name: Eleminol RS-30, etc.), polyoxyethylene alkylpropenyl phenyl ether ammonium sulfate (e.g., Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10, Aqualon BC-10, etc.), allyloxymethyl alkyloxy polyoxyethylene Examples of suitable hydroxypolyoxyethylene sulfonate salts include sulfonate salts of ethylene (e.g., Aqualon KH-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), sulfonate salts of allyloxymethylnonylphenoxyethyl hydroxypolyoxyethylene (e.g., Adeka Reasoap SE-10, manufactured by ADEKA Corporation), allyloxymethylalkoxyethyl hydroxypolyoxyethylene sulfate salts (e.g., Adeka Reasoap SR-10, SR-20, SR-30, manufactured by ADEKA Corporation), and bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfonate salts. phenate salts (e.g., trade name: Antox MS-60, manufactured by Nippon Nyukazai Co., Ltd.), allyloxymethyl alkoxyethyl hydroxypolyoxyethylene (e.g., trade name: Adeka Reasoap ER-20, manufactured by ADEKA Corporation), polyoxyethylene alkylpropenylphenyl ether (e.g., trade name: Aqualon RN-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), allyloxymethyl nonylphenoxyethyl hydroxypolyoxyethylene (e.g., trade name: Adeka Reasoap NE-10, manufactured by ADEKA Corporation), polyoxyethylene Examples of suitable styrene-based propenyl phenyl ether sulfates include ethylene styrenated propenyl phenyl ether sulfates (e.g., trade names: Aqualon AR-10, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene styrenated propenyl phenyl ether sulfates (e.g., trade names: Aqualon AN-10, Aqualon AN-20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and polyoxyalkylene alkenyl ethers (e.g., trade names: Latemul PD-420, Latemul PD-430, and Latemul PD-450, manufactured by Kao Corporation), and one or more of these may be used.

[0093] The amount of the emulsifier is not particularly limited, but is preferably 0.5 to 10% by mass, more preferably 1 to 7% by mass, and even more preferably 1 to 5% by mass, relative to 100% by mass of the monomer. When a phase inversion emulsification method is used as the emulsification method, the amount of the emulsifier is preferably 1 to 60% by mass relative to 100% by mass of the monomer, from the viewpoint of dispersion stability of the monomer emulsion particles, more preferably 5 to 55% by mass, even more preferably 10 to 50% by mass, still more preferably 10 to 50% by mass, and particularly preferably 10 to 45% by mass.

[0094] The polymerization initiator is not particularly limited, and examples thereof include azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-diaminopropane) hydrochloride, 4,4-azobis(4-cyanovaleric acid), and 2,2-azobis(2-methylpropionamidine); persulfates such as potassium persulfate and ammonium persulfate; hydrogen peroxide, benzoyl peroxide, and parachlorobenzoates. Examples of the polymerization initiator include peroxides such as methyl peroxide, lauroyl peroxide, ammonium peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, and methyl ethyl ketone peroxide. These polymerization initiators may be used alone or in combination of two or more.

[0095] The amount of the polymerization initiator is not particularly limited, but is preferably 0.01 to 1% by mass relative to 100% by mass of the polymerizable monomer. If it is 0.01% by mass or more, the polymerization rate can be increased and the amount of remaining unreacted monomer can be more sufficiently reduced, and if it is 1% by mass or less, the water penetration resistance of the coating film can be further improved. A more preferred amount is 0.03 to 0.5% by mass.

[0096] The polymerization initiator may be used in combination with a reducing agent, if necessary, to promote emulsion polymerization. Examples of the reducing agent include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, and glucose; and reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite, sodium hydrogensulfite, and thiourea dioxide. One or more of these may be used. The amount of the reducing agent used is not particularly limited, and is preferably 0.05 to 1 part by mass, for example, relative to 100 parts by mass of the total amount of the monomer components used to form the polymer.

[0097] The method for adding the polymerization initiator is not particularly limited. Examples of the addition method include batch addition, divided addition, continuous dropwise addition, etc. In order to hasten the completion of the polymerization reaction, a portion of the polymerization initiator may be added to the flask before or after the completion of the addition of the monomer components to the reaction system.

[0098] In order to promote decomposition of the polymerization initiator, a suitable amount of a decomposer for the polymerization initiator, such as a reducing agent such as sodium hydrogen sulfite or a transition metal salt such as ferrous sulfate, may be added to the reaction system. If necessary, a suitable amount of additives may be added to the reaction system, such as a chain transfer agent, a compound having a thiol group such as tert-dodecyl mercaptan, a pH buffer, a chelating agent, or a film-forming aid.

[0099] In the polymerization step, a chain transfer agent may be used. This allows the molecular weight of the emulsion to be adjusted. In addition, in the present invention, an embodiment in which no chain transfer agent is used is also one of the preferred embodiments of the present invention. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its esters, 2-ethylhexyl thioglycol, and octyl thioglycolate; methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, and the like. Examples of suitable solvents include alcohols such as ethanol, hexanol, benzyl alcohol, and allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane, and trichloroethylene; carbonyls such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butylaldehyde, furfural, and benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic anhydride, α-methylstyrene, and α-methylstyrene dimer. Among these, mercaptans are preferred, and octyl thioglycolate is more preferred. The amount of the chain transfer agent used is not particularly limited, but can be, for example, 0.01 to 5% by mass, preferably 0.02 to 1% by mass, and more preferably 0.05 to 0.5% by mass, relative to 100% by mass of the polymerizable monomer.

[0100] The atmosphere in which the monomer components are emulsion-polymerized is not particularly limited, but from the viewpoint of increasing the efficiency of the polymerization initiator, an inert gas such as nitrogen gas is preferred.

[0101] The polymerization temperature when emulsion polymerizing the monomer components is not particularly limited, but is usually preferably 50 to 100° C., more preferably 60 to 95° C. The polymerization temperature may be constant or may be changed during the polymerization reaction.

[0102] The polymerization time for emulsion polymerization of the monomer components is not particularly limited and may be set appropriately depending on the progress of the polymerization reaction, but is usually about 2 to 15 hours.

[0103] When the polymer (A) has a multilayer structure, the polymerization reaction can be repeated two or more times to prepare emulsion particles having at least two resin layers.

[0104] <Other Components Other Than Polymer (A)> The pressure-sensitive adhesive composition of the present invention may contain other components in addition to the aqueous dispersion of polymer (A). The other components are not particularly limited, and examples thereof include photopolymerization initiators, polyfunctional monomers, crosslinking agents, viscosity modifiers, antifoaming agents, leveling agents, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, surfactants, storage stabilizers, thermal polymerization inhibitors, plasticizers, wettability improvers, adhesion imparting agents, tackifiers, curing agents, etc. Among these, photopolymerization initiators, polyfunctional monomers, crosslinking agents, viscosity modifiers, antifoaming agents, and leveling agents are preferred. An embodiment in which the pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator is one of the preferred embodiments of the present invention.

[0105] Examples of the photopolymerization initiator include alkylphenone compounds, benzophenone compounds, benzil ketal compounds, α-hydroxyketone compounds, α-aminoketone compounds, oxime compounds, triazine compounds, iodonium salts, and sulfonium salts. Specific examples include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzoyl] alkylphenone compounds such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone; benzophenone, 4,4'-bis(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone; benzophenone compounds such as 2-methylaminobenzophenone and 2-carboxybenzophenone; benzoin compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; thioxanthone compounds such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone; halomethylated triazine compounds such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(4-ethoxycarboxynylnaphthyl)-4,6-bis(trichloromethyl)-s-triazine;Halomethylated oxadiazole compounds such as 2-trichloromethyl-5-(2'-benzofuryl)-1,3,4-oxadiazole, 2-trichloromethyl-5-[β-(2'-benzofuryl)vinyl]-1,3,4-oxadiazole, 4-oxadiazole, and 2-trichloromethyl-5-furyl-1,3,4-oxadiazole; 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, and 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5' biimidazole compounds such as 1,2-tetraphenyl-1,2'-biimidazole; oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); titanocene compounds such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium; benzoate ester compounds such as p-dimethylaminobenzoic acid and p-diethylaminobenzoic acid; and acridine compounds such as 9-phenylacridine. Among these, alkylphenone compounds such as 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone are preferred;Benzophenone compounds such as benzophenone, 4,4'-bis(dimethylamino)benzophenone, and 2-carboxybenzophenone;

[0106] Examples of the polyfunctional monomer include the polyfunctional monomers described in connection with the polymer (A). Examples of the crosslinking agent include hydrazine-based crosslinking agents, melamine-based crosslinking agents, oxazoline-based crosslinking agents, acrylamide-based crosslinking agents, polyamide-based crosslinking agents, epoxy-based crosslinking agents, isocyanate-based crosslinking agents, aziridine-based crosslinking agents, titanate-based crosslinking agents, urea-based crosslinking agents, alkyl alcohol-based urea crosslinking agents, carbodiimide compounds, zirconium compounds, zinc compounds, titanium compounds, and polyvalent metal compounds such as aluminum compounds.

[0107] Examples of the viscosity modifier include polyurethane-based thickeners, acrylic-based thickeners, polyamide-based thickeners, etc. Polyurethane-based thickeners are preferred, and commercially available products include ADEKA NOL UH420, ADEKA NOL UH438, and ADEKA NOL UH450VF (all manufactured by ADEKA Corporation).

[0108] Examples of the defoaming agent include commercially available silicone-based defoaming agents such as polyether-modified silicone oil KF-353, KF-351A, and KF-352A (all manufactured by Shin-Etsu Chemical Co., Ltd.), FS1265, SH200, SH5500, SC5540, SC5570, F-1, and SD5590 (all manufactured by Toray Dow Corning Silicone Co., Ltd.); fluorine atom-containing defoamers such as 3, AO-4OH (all manufactured by Kyoeisha Chemical Co., Ltd.), Megafac F-142D, F-144D, F-178K, F-179, and F-815 (all manufactured by Dainippon Ink and Chemicals, Inc.); and organic copolymers that do not contain Si atoms or F atoms such as Florene AC-202, AC-300, AC-303, AC-326F, AC-900, AC-1190, and AC-2000 (all manufactured by Kyoeisha Chemical Co., Ltd.).

[0109] Examples of the leveling agent include commercially available products such as Polyflow No. 7, No. 38, No. 50E, S, 75, No. 75, No. 77, No. 90, No. 95, No. 300, No. 460, ATF, and KL-245 (all manufactured by Kyoeisha Chemical Co., Ltd.).

[0110] Examples of the ultraviolet absorber include benzotriazole-based and triazine-based ultraviolet absorbers, etc. Commercially available products include TINUVIN P, 234, 320, 326, 327, 328, 213, 400, and 479 (all manufactured by Ciba Specialty Chemicals), and Sumisorb 110, 130, 140, 220, 250, 300, 320, 340, 350, and 400 (all manufactured by Sumitomo Chemical Co., Ltd.).

[0111] Examples of the anti-aging agent include phenol-based anti-aging agents, allylamine-based anti-aging agents, ketone amine-based anti-aging agents, etc. Commercially available products include Antigen W, S, P, 3C, 6C, RD-G, FR, and AW (all manufactured by Sumitomo Chemical Co., Ltd.).

[0112] Examples of the adhesion promoter include a thiol compound having an alkoxysilyl group, a phosphate ester compound, and the like.

[0113] Specific examples of thiol compounds having an alkoxysilyl group that can be used as the adhesion promoter include mercaptoalkyl mono-, di-, or tri-methoxysilanes such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethylmonomethoxysilane, and γ-mercaptopropylmethyldimethoxysilane. Commercially available products include SH6062, AY43-062 (manufactured by Dow Corning Toray Silicone Co., Ltd.), Sila-Ace S810 (manufactured by Chisso Corporation), KBM803, KBM403, and KBE5103 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0114] Specific examples of phosphate ester compounds that can be used as the adhesion promoter include mono[2-(meth)acryloyloxyethyl]phosphate, mono[2-(meth)acryloyloxyethyl]diphenylphosphate, mono[2-(meth)acryloyloxypropyl]phosphate, bis[2-(meth)acryloyloxyethyl]phosphate, bis[2-(meth)acryloyloxypropyl]phosphate, tris[2-(meth)acryloyloxyethyl]phosphate, etc. Commercially available products include Light Ester P-1M, P-2M, Light Acrylate P-1A, P-2A (all manufactured by Kyoeisha Chemical Co., Ltd.), KAYAMER PM-2, PM-21 (all manufactured by Nippon Kayaku Co., Ltd.), etc.

[0115] Examples of the tackifier include alicyclic saturated hydrocarbon resins, rosin esters, terpene phenols, C5 and C9 petroleum resins, etc. Commercially available products include Alcon P-70, P-90, P-100, M-90, M-100, M-135, Arastar 700, KE-359, Tamanol 521, Superester A-75, and A-115 (all manufactured by Arakawa Chemical Industries, Ltd.).

[0116] Examples of the curing agent include compounds having an isocyanate group, and examples of commercially available products include "Coronate" (manufactured by Nippon Polyurethane Industry Co., Ltd.).

[0117] [Uses of the Pressure-Sensitive Adhesive Composition] The adhesive composition of the present invention can control adhesive properties, and therefore can be suitably used in applications requiring adhesive properties to be changed. It can be suitably used in semiconductor processing, etc. The present invention also provides an adhesive property-changeable adhesive containing the adhesive composition of the present invention, whose adhesive properties change upon exposure to ultraviolet light. The pressure-sensitive adhesive composition of the present invention is preferably used for processing semiconductors and the like. More specific uses of the pressure-sensitive adhesive composition of the present invention include a dicing tape (pressure-sensitive adhesive tape) for temporarily fixing a semiconductor wafer to a frame or the like in the dicing step of the semiconductor wafer; a temporary fixing tape for temporarily fixing circuit elements or the like in the manufacturing process of electronic components or the like; a transport tape used when transporting circuit elements or the like in the manufacturing process of semiconductor wafers; and a metal foil-covered film circuit-forming transfer sheet used in the manufacture of multilayer wiring boards.

[0118] The pressure-sensitive adhesive composition of the present invention is suitably used as a pressure-sensitive adhesive sheet. The present invention also relates to a pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive composition of the present invention.

[0119] The pressure-sensitive adhesive sheet is not particularly limited as long as it contains the pressure-sensitive adhesive composition of the present invention, but it is preferably in a form in which a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of the present invention is laminated on a substrate. The pressure-sensitive adhesive sheet can be easily peeled off from an adherend because the pressure-sensitive adhesive layer is effectively cured by irradiation with ultraviolet light, and the adhesive strength is reduced satisfactorily. In this specification, the term "sheet" means a sheet-like object, and for example, tapes and films are also included in the term "sheet."

[0120] The substrate in the pressure-sensitive adhesive sheet is not particularly limited, and examples thereof include synthetic resin, glass, metal, ceramic, etc. Synthetic resin is preferred, and polyethylene terephthalate resin, polyvinyl chloride resin, or polyolefin resin is more preferred. The thickness of the substrate is not particularly limited, but is preferably 10 to 300 μm, more preferably 15 to 200 μm, and even more preferably 20 to 100 μm.

[0121] The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is effectively cured by irradiation with ultraviolet light, and its adhesive strength is sufficiently reduced. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 5 to 1000 μm, more preferably 10 to 500 μm, and even more preferably 10 to 50 μm.

[0122] The method for producing the pressure-sensitive adhesive sheet is not particularly limited, and examples thereof include a method in which a pressure-sensitive adhesive composition is applied to at least one surface of a substrate using a coating device such as an applicator, and then the sheet is dried.

[0123] The amount of ultraviolet light to be irradiated when the adhesive layer in the adhesive sheet of the present invention is cured by ultraviolet light to reduce its adhesive strength is not particularly limited, and may be adjusted depending on the thickness of the adhesive layer on the substrate surface, etc. For example, the integrated amount of ultraviolet light is 10 to 4000 mJ / cm 2 This allows the adhesive layer to be cured more effectively, and the adhesive strength to be reduced more sufficiently. The integrated light amount of ultraviolet light is more preferably 50 to 2000 mJ / cm. 2 and more preferably 100 to 1500 mJ / cm 2 is. As the light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an arc lamp, a gallium lamp, or the like can be used. [Example]

[0124] The present invention will now be described in more detail based on examples, but is not limited to these examples. In the following production examples, examples, and comparative examples, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass." In the following production examples, the abbreviations for each compound mean the following compounds. <Monomer> MMA: Methyl methacrylate VEEA: 2-(2-vinyloxyethoxy)ethyl acrylate BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate LMA: Lauryl methacrylate HEMA: 2-hydroxyethyl methacrylate DAM: Diaceton acrylamide CHMA: Cyclohexyl methacrylate C18A: Stearyl acrylate LA-87: 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (manufactured by ADEKA Corporation, trade name: Adekastab LA-87) AA: Acrylic acid <Emulsifier> SR-10: Reactive anionic emulsifier (manufactured by ADEKA Corporation, trade name: ADEKA REASOAP (registered trademark) SR-10) AN-20: Reactive nonionic emulsifier (manufactured by Daiichi Pharmaceutical Co., Ltd., trade name: Aqualon (registered trademark) AN-20) PD-420: Reactive nonionic emulsifier (Polyoxyalkylene alkenyl ether, manufactured by Kao Corporation, trade name: Latemul PD-420, HLB: 12.6)

[0125] The physical properties of the aqueous dispersions obtained in the following production examples and the resin particles contained in the aqueous dispersions were measured as follows. <Non-volatile content (NV value)> The amount of nonvolatile matter in the aqueous dispersion was determined by weighing 1 g of the aqueous dispersion, drying it in a hot air dryer at 130°C for 30 minutes, and calculating the nonvolatile matter from the residue obtained by the following formula: [Non-volatile content in aqueous dispersion] = ([mass of residue] / [1 g of aqueous dispersion]) × 100 was calculated based on the following.

[0126] <Average particle size> The average particle size of the resin particles contained in the aqueous dispersion or aqueous dispersion composition was measured at a measurement temperature of 25°C using a multi-analyte nanoparticle size measurement system (manufactured by Otsuka Electronics Co., Ltd., product name: nanoSAQLA), which is a particle size measurement device using a dynamic light scattering method, by determining the autocorrelation function using a photon correlation method and then calculating the average particle size (hydrodynamic diameter) using cumulant analysis.

[0127] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the resin particles contained in the aqueous dispersion was calculated based on the Fox equation shown below, using the glass transition temperatures of the homopolymers of the monomers used in the monomer components constituting the acrylic polymer contained in the resin particles. 1 / Tg A =Σ(Wm / Tgm) / 100 [In the formula, Tg A indicates the glass transition temperature (absolute temperature: K) of the resin particle, Wm indicates the content (%) of monomer m in all monomer components constituting the resin particle, and Tgm indicates the glass transition temperature (absolute temperature: K) of a homopolymer of monomer m.

[0128] [Preparation of aqueous dispersion of polymer (A)] <Production Example 1> A flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer, and a reflux condenser was charged with 177.1 parts of deionized water and 4.0 parts of a 25% aqueous solution of surfactant SR-10. The temperature was raised to 60 °C while gently flowing nitrogen gas. When the temperature reached 60 °C, 2.5 parts of a 25% aqueous ammonia solution was charged, and 5% of a pre-emulsion consisting of 10 parts of MMA, 5 parts of VEEA, 67 parts of 2-EHA, 8 parts of LMA, 3 parts of HEMA, 2 parts of DAM, 16.0 parts of a 25% aqueous solution of surfactant SR-10, and 32 parts of deionized water was added as an initial charge. Subsequently, 10% of a mixture of 0.1 parts of PBH (manufactured by NOF Corporation, trade name: Perbutyl (registered trademark) H) and 1.5 parts of deionized water as an initiator, and 10% of a mixture of 0.1 parts of thiourea dioxide and 5 parts of deionized water were added sequentially to initiate polymerization. The remaining pre-emulsion, PBH mixture, and thiourea dioxide mixture were then added dropwise using a dropping funnel over 2 hours, and the mixture was allowed to react while stirring. After the addition, the mixture was aged at 60°C for 2 hours to obtain an aqueous dispersion of copolymer A-1. Filtering through a 300-mesh (JIS mesh, the same applies below) wire mesh yielded aqueous dispersion A-1 of acrylic resin particles with a nonvolatile content of 30%. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-1 are shown in Table 1.

[0129] <Production Example 2> A flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer, and a reflux condenser was charged with 189.4 parts of deionized water and 2.0 parts of a 25% aqueous solution of surfactant AN-20. The temperature was raised to 60 °C while gently flowing nitrogen gas. When the temperature reached 60 °C, 2.5 parts of a 25% aqueous solution of ammonia was charged, and a pre-emulsion 1 consisting of 18 parts of MMA, 0.6 parts of a 25% aqueous solution of surfactant SR-10, 6.0 parts of a 25% aqueous solution of AN-20, and 1 part of deionized water was prepared, of which 20% was added as the initial charge. Subsequently, 10% of a mixture of 0.1 parts of PBH (manufactured by NOF Corporation, trade name: Perbutyl (registered trademark) H) and 1.5 parts of deionized water as an initiator, and 10% of a mixture of 0.1 parts of thiourea dioxide and 5 parts of deionized water were sequentially added to initiate polymerization. The remaining total amount of pre-emulsion 1, 20% of the remaining amount of the PBH mixed solution, and 20% of the remaining amount of the thiourea dioxide mixed solution were added dropwise using a dropping funnel over 30 minutes, and then the mixture was aged at 60°C for 30 minutes. Next, pre-emulsion 2 was prepared, consisting of 5 parts VEEA, 10 parts BA, 47 parts 2-EHA, 8 parts LMA, 3 parts HEMA, 2 parts DAM, 19.4 parts of a 25% aqueous solution of surfactant SR-10, and 12.4 parts deionized water. The entire amount of pre-emulsion 2 and the remaining PBH and thiourea dioxide mixtures were added dropwise over 2 hours using a dropping funnel. The mixture was stirred and allowed to react. After the addition, the mixture was aged at 60°C for 1 hour to obtain an aqueous dispersion of copolymer A-2. Aqueous dispersion A-2 of acrylic resin particles with a nonvolatile content of 30% was obtained by filtering through a 300-mesh (JIS mesh, hereinafter the same) wire mesh. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-2 are shown in Table 1.

[0130] <Production Example 3> A reaction vessel equipped with a stirrer, temperature sensor, cooling tube, nitrogen inlet tube, and dropping funnel was charged with 180 parts of deionized water, 2.8 parts of MMA, 35 parts of VEEA, 8 parts of 2-EHA, 0.5 parts of DAM, 10 parts of CHMA, 12 parts of C18A, 3 parts of LA-87, 6 parts of AN-20, and 22 parts of PD-420. A portion of the resulting mixture was taken out and the phase inversion temperature of the mixture was measured according to the following method. As a result, the phase inversion temperature was 70 ° C (the lower limit temperature is the phase inversion onset temperature, the same applies below) to 75 ° C (the upper limit temperature is the phase inversion end temperature, the same applies below).

[0131] (Method for measuring phase inversion temperature) A 2 L (liter) reaction vessel was equipped with a stirring device and a temperature sensor, and 1000 g of the mixture was placed in the reaction vessel and stirred. The reaction vessel was heated in a water bath, and the electrical conductivity was measured every time the temperature of the mixture in the reaction vessel increased by 1°C using a conductivity meter (manufactured by EUTECH, trade name: Lacom Tester PC450). The electrical conductivity was plotted for each temperature increase, and the temperature at which the electrical conductivity began to decrease continuously with increasing temperature was taken as the phase inversion starting temperature, and the temperature at which the electrical conductivity became 1.00 μS or less was taken as the phase inversion end temperature. In addition, if the electrical conductivity did not become 1.00 μS or less even when the upper limit of the measurable temperature of the conductivity meter was exceeded, the temperature at which the appearance of the mixture did not change even after 3 minutes or more had passed since it reached a temperature higher than the phase inversion starting temperature under stirring was taken as the end point of the phase inversion temperature.

[0132] After measuring the phase inversion temperature of the mixture, the reaction vessel was heated in a water bath under stirring while introducing nitrogen gas into the reaction vessel. After the temperature of the mixture in the reaction vessel reached 90°C, the reaction vessel was removed from the water bath and air-cooled under stirring until the internal temperature reached 40°C or less, thereby obtaining an aqueous dispersion containing monomer emulsion particles. Next, 100 parts of the resulting monomer emulsion particle-containing aqueous dispersion was placed in a separate reaction vessel. 2.8 parts of a 25% aqueous solution of SR-10 was added to the reaction vessel. The mixture was stirred at room temperature for 30 minutes while introducing nitrogen gas into the reaction vessel. The reaction vessel was then placed in a water bath and heated with stirring until the internal temperature of the reaction vessel reached 60°C. 0.5 parts of a 25% aqueous ammonia solution, a mixture of 0.1 parts of PBH (manufactured by NOF Corporation, trade name: Perbutyl® H) as an initiator and 1.5 parts of deionized water, and a mixture of 0.1 parts of thiourea dioxide and 5 parts of deionized water were then added. The contents of the reaction vessel were heated with stirring at 60°C for 6 hours to polymerize the components contained in the monomer emulsion particles, yielding an aqueous dispersion of acrylic resin particles, A-3. The nonvolatile content of A-3 and the average particle size of the acrylic resin particles contained in A-3 are shown in Table 1.

[0133] <Production Example 4> Aqueous dispersion A-4 of acrylic resin particles having a nonvolatile content of 30% was prepared in the same manner as in Production Example 1, except that the types and amounts of the monomer components were changed as shown in Table 1. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-4 are shown in Table 1.

[0134] <Production Example 5> A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, a nitrogen inlet tube, and a dropping funnel was charged with 90 parts of deionized water, 2 parts of MMA, 17 parts of VEEA, 4 parts of 2-EHA, 0.5 parts of DAM, 5 parts of CHMA, 6 parts of C18A, and 15 parts of PD-420, and a portion of the resulting mixture was removed and the phase inversion temperature of the mixture was measured according to the method of Production Example 3. As a result, the phase inversion temperature was 70°C (the lower limit temperature is the phase inversion starting temperature, the same applies hereinafter) to 75°C (the upper limit temperature is the phase inversion end temperature, the same applies hereinafter). After measuring the phase inversion temperature of the mixture, the reaction vessel was heated in a water bath under stirring while introducing nitrogen gas into the reaction vessel. After the temperature of the mixture in the reaction vessel reached 80°C, the reaction vessel was removed from the water bath and air-cooled under stirring until the internal temperature reached 40°C or less, thereby obtaining an aqueous dispersion containing monomer emulsion particles. Next, 3.9 parts of a 25% aqueous solution of SR-10 was added to the obtained monomer emulsion particle-containing aqueous dispersion, and the mixture was stirred at room temperature for 30 minutes while introducing nitrogen gas into the reaction vessel. The reaction vessel was then placed in a water bath and heated with stirring until the internal temperature of the reaction vessel reached 60° C. 0.5 parts of a 25% aqueous ammonia solution, a mixture of 0.05 parts of PBH (manufactured by NOF Corporation, trade name: Perbutyl (registered trademark) H) as an initiator and 0.75 parts of deionized water, and a mixture of 0.05 parts of thiourea dioxide and 2.5 parts of deionized water were then added, and the contents of the reaction vessel were heated at 60° C. for 2 hours with stirring to polymerize the components contained in the monomer emulsion particles. Subsequently, 118 parts of deionized water was added to the reaction vessel, and the temperature was raised to 60°C again. A pre-emulsion consisting of 44 parts 2-EHA, 3.5 parts LMA, 0.5 parts DAM, 6.1 parts of a 25% aqueous solution of surfactant SR-10, and 15.1 parts deionized water was prepared in a separate container. A mixture of the entire pre-emulsion, 0.05 parts PBH (manufactured by NOF Corporation, trade name: Perbutyl® H), and 0.75 parts deionized water, and a mixture of 0.05 parts thiourea dioxide and 2.5 parts deionized water were added dropwise using a dropping funnel over 2 hours, followed by aging at 60°C for 1 hour to prepare aqueous dispersion A-5 of acrylic resin particles with a nonvolatile content of 30%. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-5 are shown in Table 1.

[0135] <Production Example 6> Aqueous dispersion A-6 of acrylic resin particles having a nonvolatile content of 30% was prepared in the same manner as in Production Example 1, except that the types and amounts of the monomer components were changed as shown in Table 1. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-6 are shown in Table 1.

[0136] <Production Example 7> Aqueous dispersion A-7 of acrylic resin particles having a nonvolatile content of 30% was prepared in the same manner as in Production Example 1, except that the types and amounts of the monomer components were changed as shown in Table 1. The average particle size and Tg of the acrylic resin particles contained in aqueous dispersion A-7 are shown in Table 1.

[0137] [Table 1]

[0138] [Examples 1 to 7 and Comparative Examples 1 and 2: Preparation of Pressure-Sensitive Adhesive Compositions] The amount of photopolymerization initiator (trade name: Irgacure 184 (Irg184)) shown in Table 2 was added to the aqueous dispersion composition obtained in each production example, and the mixture was stirred at room temperature using a disperser. In Example 7, dipentaerythritol hexaacrylate was mixed as the polyfunctional monomer. One part of modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-351A) and 0.5 parts of a thickener (manufactured by ADEKA Corporation, trade name: ADEKA NOL UH420) were further added to obtain a pressure-sensitive adhesive composition. The resulting pressure-sensitive adhesive composition was subjected to the evaluation tests described below.

[0139] [Evaluation test] <Evaluation test 1: Adhesion> The pressure-sensitive adhesive composition obtained in each Example or Comparative Example was applied to a PET (polyethylene terephthalate) film substrate (thickness: 25 μm) using an applicator so that the film thickness after drying would be 25 μm, and then dried for 3 minutes at a temperature of 70° C. A release paper (manufactured by San-A Kaken Co., Ltd., product name: K-80HS) was laminated to the dried film to obtain a pressure-sensitive adhesive tape with one adhesive surface. Test tapes were prepared by cutting the pressure-sensitive adhesive sheet into rectangles measuring 50 mm in length and 25 mm in width. The release paper was peeled off the resulting test tape, and the test tape was placed on a glass plate. A 2 kg roll was then rolled back and forth over the adherend. Two test pieces were prepared for each sample, and after leaving them at 23°C for 25 minutes, one of the test pieces was exposed to an ultraviolet ray irradiation device (distance from light source: 10 cm) equipped with an 80 W / cm high-pressure mercury lamp until the irradiation dose reached 1000 mJ. The peel force was measured for both the non-irradiated and irradiated test pieces when peeled at a peel angle of 180° and a peel speed of 300 mm / min, and the adhesive strength to the glass plate was measured before and after UV irradiation.

[0140] <Evaluation Test 2: Gel Fraction> The adhesive composition of each Example and Comparative Example was applied to a glass plate with a release paper attached so that the film thickness after drying would be 25 μm, and then dried at a temperature of 70° C. for 3 minutes to form a coating film. Two of the resulting coatings (4 cm long, 4 cm wide) were peeled off from the substrate to obtain a film. The thickness of the resulting film was measured, and one of the films was exposed to an ultraviolet ray irradiation device (distance from the light source: 10 cm) equipped with an 80 W / cm high-pressure mercury lamp until the irradiation dose reached 1000 mJ. Each of the obtained films was immersed in tetrahydrofuran for 8 hours, filtered through a mesh whose weight had been measured in advance, and dried at 150°C for 2 hours. The total mass of the mesh and the filtration residue was measured, and the filtration residue mass was calculated. The gel fraction was calculated using the formula: [Gel fraction (%)] = {[Filtration residue mass] ÷ [Film weight before immersion]} × 100 The gel fraction was evaluated based on the presence or absence of ultraviolet irradiation.

[0141] <Evaluation Test 3: Adhesion to polyvinyl chloride (PVC) substrate> The pressure-sensitive adhesive composition obtained in each Example or Comparative Example was applied to the surface of a hard polyvinyl chloride plate having a surface of 70 mm x 150 mm using an applicator with a coating width of 50 mm so as to obtain a coating film of 50 mm x 100 mm so that the thickness of the coating film after drying would be 25 μm, and the coating film was dried at room temperature for 10 hours to form a test plate. Twenty-five 2mm squares (5 vertical, 5 horizontal) were cut into the coating surface of the test plate using a sharp blade. After the cuts were made, it was checked to see if the coating had peeled off from the substrate or if any breaks had occurred in the coating other than the cuts. Then, 25mm wide cellophane adhesive tape (Nichiban CT-24) was adhered to the cut areas by rubbing with a finger. The test plate was then left to stand in the air at 25°C for 5 minutes, after which the cellophane adhesive tape was peeled off. The number of peeled squares out of the 25 cut squares was counted, and the adhesion to various substrates was evaluated based on the following evaluation criteria. (Evaluation criteria) ◯: The number of peeled squares is 0 to 10. △: The number of peeled squares is 11 to 18. ×: The number of peeled squares was 19 or more, or the coating film peeled off from the substrate at the time the notch was made, or the coating film broke at a location other than the notch.

[0142] [Table 2]

Claims

1. The following formula (1): 【Chemical 1】 (In the formula, R １ represents a hydrogen atom or a methyl group. ２ and R ３ are the same or different and represent a hydrogen atom or an organic group. ４ represents a hydrogen atom or an organic group; and n represents an integer of 1 or more.

2. The pressure-sensitive adhesive composition according to claim 1 , wherein the polymer (A) further comprises a structural unit derived from a neutral or basic polar group-containing monomer.

3. The pressure-sensitive adhesive composition according to claim 2, wherein the neutral or basic polar group-containing monomer comprises at least one selected from the group consisting of an amino group-containing monomer, an amide group-containing monomer, and a hydroxyl group-containing monomer.

4. The pressure-sensitive adhesive composition according to claim 1, wherein the polymer (A) further comprises a structural unit derived from a monomer having a glass transition temperature of a homopolymer of -70°C to -10°C.

5. The pressure-sensitive adhesive composition according to claim 1 , further comprising a photopolymerization initiator.

6. The pressure-sensitive adhesive composition according to any one of claims 1 to 5, which is used for applications in which adhesiveness is changed.

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