JP2022162175A - Copolymer, and method for producing the same, and aqueous dispersoid - Google Patents

Abstract

To provide a copolymer that is excellent in low-temperature reactivity; is used as a crosslinker to give a coating layer having excellent physical properties and gives an aqueous dispersoid having excellent stability.SOLUTION: A copolymer contains an oxazoline group- or epoxy group-containing monomer-derived constitutional unit, an anionic surfactant-derived constitutional unit, and a nonionic surfactant-derived constitutional unit and has a glass transition temperature of lower than 10°C.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a copolymer, a method for producing the same, and an aqueous dispersion. More particularly, the present invention relates to aqueous crosslinkers having, for example, aqueous dispersion stability and good reactivity at low temperatures.

Conventionally, a polymer having a structural unit derived from an oxazoline group or an epoxy group-containing monomer reacts with a polymer having a carboxyl group, a hydroxyl group, a thiol group, etc. to form a crosslinked structure, resulting in an excellent film. It is known to have mechanical and chemical properties. Therefore, polymers having structural units derived from oxazoline group- or epoxy group-containing monomers can be used in automobiles, building materials (inorganic, metal, etc.), construction materials, metals, glass, plastics, woodworking, various (metals, inorganics, glass, synthetic high Molecules, etc.) Widely used for various applications such as paints for fibers, surface treatment agents, coating agents, binders including sizing agents and treatment agents, pressure-sensitive adhesives, adhesives, sealants, films, molded products, cast products, etc. ing.

For example, Patent Literature 1 describes a reactive emulsion in which fine particles of an acrylic emulsion are used as a core portion, and an oxazoline group-containing polymer layer is formed as a shell portion around the core portion.

Further, in Patent Document 2, an aqueous An aqueous resin composition is disclosed, wherein the polymer (A0) is composed of two or more polymers having different Tg.

JP 2008-536951 JP 2013-057081

Coatings, pressure-sensitive adhesives, and adhesives in which a polymer having a structural unit derived from a monomer containing an oxazoline group or an epoxy group is used to form a cross-linking reaction with another polymer having a substituent group that reacts with an oxazoline group or an epoxy group. Agents contribute to improving physical properties such as water resistance and blocking resistance, but have the problem of poor reactivity at low temperatures.

In addition, from the viewpoint of environmental protection and work safety and health, there is a demand for water-based dispersion, and improvement in the stability of aqueous dispersions containing a polymer having a structural unit derived from an oxazoline group- or epoxy group-containing monomer is required. Under the circumstances, it has been found that the stability of the aqueous dispersion is lowered when the content of the structural unit derived from the oxazoline group- or epoxy group-containing monomer is increased.

An object of the present invention is to provide a copolymer which is excellent in low-temperature reactivity and physical properties of coating films when used as a cross-linking agent, and which is excellent in stability when made into an aqueous dispersion.

The inventors have studied in view of the above problems, structural units derived from oxazoline group- or epoxy group-containing monomers, structural units derived from anionic surfactants, and structures derived from nonionic surfactants A copolymer having a unit and a glass transition temperature of less than 10 ° C. is excellent in low-temperature reactivity and physical properties of a coating film when used as a crosslinking agent, and is excellent in stability when made into an aqueous dispersion. He found this and completed the present invention.

According to the present invention, it is possible to provide a copolymer which is excellent in low-temperature reactivity and physical properties of a coating film when used as a cross-linking agent, and which is excellent in stability when made into an aqueous dispersion.

The present invention will be described in detail below.

In the following description, unless otherwise specified, “%” means “% by mass” and “part” means “part by mass”, and “A to B” indicating the range means A or more B Indicates that: Further, in the present invention, "(meth)acrylate" means "acrylate" or "methacrylate", and "(meth)acryl" means "acryl" or "methacryl".

As used herein, the term "resin" indicates a broader concept than polymers. The resin may contain one or more types of polymers, and may further contain materials other than polymers as necessary.

[Copolymer of the present disclosure]
The copolymer of the present disclosure is a copolymer having a structural unit derived from an oxazoline group- or epoxy group-containing monomer, a structural unit derived from an anionic surfactant, and a structural unit derived from a nonionic surfactant. is preferred.

In the present disclosure, the structural unit derived from an oxazoline group- and/or epoxy group-containing monomer usually means that at least one of the unsaturated bonds contained in the oxazoline group- and/or epoxy group-containing monomer is a carbon A structural unit having a structure replaced with a saturated bond such as a carbon single bond (hereinafter also referred to as structural unit A). Structural unit A is not limited to a structural unit formed by polymerization of a monomer containing an oxazoline group and/or an epoxy group. It may be a structural unit formed by the method of. Other monomers to be described later also refer to structural units having a structure in which at least one unsaturated bond contained in each monomer is replaced with a saturated bond such as a carbon-carbon single bond.

In the present disclosure, oxazoline group- and/or epoxy group-containing monomers include oxazoline group-containing monomers and epoxy group-containing monomers.

In the present disclosure, an oxazoline group-containing monomer is a compound having at least one oxazoline group and at least one polymerizable unsaturated bond. The oxazoline group-containing monomers of the present disclosure include, for example, vinyloxazolines {e.g., vinyloxazoline (2-vinyl-2-oxazoline, etc.), vinyloxazoline having substituents [e.g., alkyl-vinyloxazoline (e.g., 2 -vinyl-4-methyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4-propyl-2-oxazoline, 2 -vinyl-4-butyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-5-ethyl-2-oxazoline, 2-vinyl-5-propyl-2-oxazoline, 2-vinyl -C _1-20 alkyl-vinyloxazoline such as 5-butyl-2-oxazoline, preferably C _1-10 alkyl-vinyloxazoline, more preferably mono- or di-C _1-4 alkyl-vinyloxazoline)], etc.}, isopropenyl oxazolines {e.g. isopropenyl oxazoline (2-isopropenyl-2-oxazoline etc.), substituted isopropenyl oxazoline [e.g. alkyl-isopropenyl oxazoline (e.g. 2-isopropenyl-4-methyl-2 -oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-4-propyl-2-oxazoline, 2-isopropenyl-4 -butyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-5-propyl-2-oxazoline, 2-isopropenyl -C _1-20 alkyl-isopropenyl oxazoline such as 5-butyl-2-oxazoline, preferably C _1-10 alkyl-isopropenyl oxazoline, more preferably mono or di C _1-4 alkyl-isopropenyl oxazoline), etc.] etc.}, and allyloxazolines corresponding thereto.

Among these, isopropenyloxazolines are preferred, and 2-isopropenyl-2-oxazoline is particularly preferred.

The oxazoline group-containing monomers may be used alone or in combination of two or more.

The epoxy group-containing monomer of the present disclosure is a monomer having an epoxy group and a copolymerizable unsaturated bond. However, in the present disclosure, a monomer containing both an epoxy group and an oxazoline group is included in the oxazoline group-containing monomer. The epoxy group-containing monomer is a monofunctional epoxy group-containing monomer having one epoxy group in one molecule from the viewpoint of forming an adhesive layer having excellent bending properties while having adhesiveness and heat resistance. A body is preferred. Examples of epoxy group-containing monomers include unsaturated carboxylic acid glycidyl esters and vinyl group-containing glycidyl ethers, but the present invention is not limited to these examples. These epoxy group-containing monomers may be used alone or in combination of two or more.

Examples of unsaturated carboxylic acid glycidyl esters include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate [3,4-epoxycyclohexylmethyl (meth)acrylate], monoglycidyl itaconate [itaconic acid, monoglycidyl ester], monoglycidyl butene tricarbonate [butene tricarboxylic acid monoglycidyl ester], etc., but the present invention is not limited to these examples. These unsaturated carboxylic acid glycidyl esters may be used alone or in combination of two or more. Vinyl group-containing glycidyl ethers include, for example, vinyl glycidyl ether, allyl glycidyl ether, glycidyloxyethyl vinyl ether, etc., but the present invention is not limited to these examples. These vinyl group-containing glycidyl ethers may be used alone or in combination of two or more. Among the epoxy group-containing monomers, glycidyl (meth)acrylate is preferred from the viewpoint of improving adhesiveness, heat resistance and bendability.

The content of the structural unit derived from the oxazoline group-containing monomer in the copolymer of the present disclosure is 1 mass in the copolymer from the viewpoint of improving the low-temperature reactivity and the physical properties of the coating film when used as a cross-linking agent. % or more (e.g., 3% by mass or more) is preferable, 5% by mass or more is more preferable, 10% by mass or more is even more preferable, 15% by mass or more is particularly preferable, and from the viewpoint of polymerization stability, 50% by mass or less is preferable. , is more preferably 40% by mass or less, more preferably 35% by mass or less, and particularly preferably 25% by mass or less.

The content ratio of the structural unit derived from the epoxy group-containing monomer in the copolymer of the present disclosure is 1 mass in the copolymer from the viewpoint of improving the low-temperature reactivity and the physical properties of the coating film when used as a crosslinking agent. % or more (e.g., 3% by mass or more) is preferable, 5% by mass or more is more preferable, 10% by mass or more is even more preferable, 15% by mass or more is particularly preferable, and from the viewpoint of polymerization stability, 50% by mass or less is preferable. , is more preferably 40% by mass or less, more preferably 35% by mass or less, and particularly preferably 25% by mass or less.

In addition, in the present disclosure, it is preferable that the structural unit derived from the oxazoline group- and/or epoxy group-containing monomer essentially includes a structural unit derived from the oxazoline group-containing monomer. By essentially including a structural unit derived from an oxazoline group-containing monomer, it can be expected that the physical properties of the coating film formed by the low-temperature reactivity and crosslinking reaction will be good, and it can be used as an aqueous dispersion and a coating composition. Good storage stability can be expected.

In the copolymer of the present disclosure, from the viewpoint of improving low-temperature reactivity, stability during emulsion polymerization, and stability when made into an aqueous dispersion, an anionic surfactant-derived structural unit and a nonionic surfactant-derived It is preferable to have a structural unit of

Structural units derived from anionic surfactants and structural units derived from nonionic surfactants of the present disclosure refer to nonionic surfactants contained in anionic surfactants having reactive groups and nonionic surfactants having reactive groups. A structural unit having a structure in which at least one saturated bond is replaced by a saturated bond such as a carbon-carbon single bond. Having a reactive group means a surfactant that has an unsaturated double bond in the monomer and is polymerizable with other monomers. ) having a radically polymerizable double bond such as an acryloyl group, an allyl group, or a propenyl group; Hereinafter, a structural unit derived from a surfactant having a reactive group is also referred to as a structural unit B, a structural unit derived from an anionic surfactant is referred to as structural unit b1, and a structural unit derived from a nonionic surfactant is referred to as structural unit b2. .

Preferred examples of the anionic surfactant having a reactive group of the present disclosure include an anionic surfactant represented by the following formula (1) and an anionic surfactant represented by the following formula (2). mentioned.

Among these, as an anionic surfactant having a reactive group, for example, from the viewpoint of industrial productivity, more specifically, the (meth)acrylic resin emulsion can be maintained at a low viscosity and is excellent in handleability, An anionic surfactant represented by the following formula (1) is more preferred.

In formula (1), R ^1a represents an aliphatic alkyl group having 6 to 24 carbon atoms, and X ^1a represents —SO ₃ NH ₄ or —SO ₃ Na.

In formula (1), n1 represents the average number of added moles of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n1 is an integer of 5-50, preferably an integer of 10-30.

Examples of commercially available anionic surfactants represented by formula (1) include Aqualon (registered trademark) KH-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate [oxyethylene Average number of moles of added groups: 10], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) KH-05 [active ingredient: polyoxyethylene-1-(allyloxymethyl) Ammonium alkyl ether sulfate [average number of added moles of oxyethylene group: 5], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Adekaria Soap (registered trademark) SR-20 [active ingredient: polyoxyethylene -1-(Allyloxymethyl)alkyl ether ammonium sulfate [average number of added moles of oxyethylene group: 20], amount of active ingredient: 100% by mass, ADEKA Corporation] and the like.

In formula (2), R ^2a represents a substituent represented by formula (A) below or an aliphatic alkyl group having 6 to 24 carbon atoms, and R ^3a represents a methyl group.

In formula (2), X ^2a represents -SO ₃ M, -COOM, or PO ₃ M.

M represents an alkali metal atom, an alkaline earth metal atom, or an ammonium group.

Specific examples of alkali metal atoms include a sodium atom and a potassium atom.

Specific examples of alkaline earth metal atoms include calcium atoms and barium atoms.

X ^2a is preferably —SO ₃ NH ₄ , for example.

In formula (2), n2 represents the average added mole number of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n2 is an integer of 5-50, preferably an integer of 10-30.

In formula (A), m represents an integer of 1 to 3, preferably 2, for example, from the viewpoint of surface activity.

Examples of commercially available anionic surfactants represented by formula (2) include Aqualon (registered trademark) HS-10 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 10], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) BC-10 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 10], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) BC-20 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 20], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) AR-10 [active ingredient: polyoxyethylene styrenated propenylphenyl ether sulfate ester ammonium [average of oxyethylene group Number of added moles: 10], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) AR-20 [active ingredient: polyoxyethylene styrenated propenylphenyl ether sulfate ester ammonium [oxyethylene Average number of moles of added group: 20], amount of active ingredient: 97% by mass, Daiichi Kogyo Seiyaku Co., Ltd.] and the like.

As the anionic surfactant having a reactive group, from the viewpoint of the water resistance and polymerization stability of the coating film, the Adekari Soap SR series (Adekari Soap SR-10, SR-20, etc.) is preferable. (registered trademark) SR-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate [average number of added moles of oxyethylene group: 10], amount of active ingredient: 100% by mass, ADEKA Corporation ] is more preferable.

In the copolymer of the present disclosure, the content of structural units derived from an anionic surfactant is preferably 0.1% by mass or more with respect to 100% by mass of the copolymer, from the viewpoint of improving polymerization stability. 0.5 or more is more preferable, and from the viewpoint of improving water resistance, 5% by mass or less is preferable, and 2% by mass or less is more preferable.

As the nonionic surfactant having a reactive group of the present disclosure, a nonionic surfactant represented by the following formula (3) and a nonionic surfactant represented by the following formula (4) are preferred examples. mentioned.

Among these, as a nonionic surfactant having a reactive group, for example, from the viewpoint of excellent copolymerizability with a monomer, nonionic surfactants represented by the following formula (3) are more preferred. preferable.

In formula (3), R ^1b represents an aliphatic alkyl group having 6 to 24 carbon atoms, and X ^1b represents a hydrogen atom.

In formula (3), n3 represents the average number of added moles of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n3 is an integer of 5-40, preferably an integer of 10-30.

In formula (4), R ^2b represents an aliphatic alkyl group having 6 to 24 carbon atoms, R ^3b represents a methyl group, and X ^2b represents a hydrogen atom.

In formula (4), n4 represents the average added mole number of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n4 is an integer of 10-50, preferably an integer of 10-30.

Commercially available examples of nonionic surfactants represented by formula (3) include Adekari Soap (registered trademark) ER-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl) alkyl ether [oxy Average number of added moles of ethylene group: 10], amount of active ingredient: 100% by mass, ADEKA Corporation], Adekari Soap (registered trademark) ER-30 [active ingredient: polyoxyethylene-1-(allyloxymethyl) Alkyl ether [average number of added moles of oxyethylene group: 30], amount of active ingredient: 65% by mass, ADEKA Corporation], Adekari Soap (registered trademark) ER-40 [active ingredient: polyoxyethylene-1-( allyloxymethyl)alkyl ether [average number of added moles of oxyethylene group: 40], amount of active ingredient: 60% by mass, ADEKA Corporation] and the like.

As the nonionic surfactant having a reactive group, from the viewpoint of the water resistance and polymerization stability of the coating film, the Adekariasoap ER series is preferable, and examples of commercially available nonionic surfactants having a reactive group Adekari Soap (registered trademark) ER-20 [active ingredient: polyoxyethylene-1-(allyloxymethyl) alkyl ether [average number of added moles of oxyethylene group: 20], amount of active ingredient: 100 mass% , ADEKA Co., Ltd.] is more preferable.

In the copolymer of the present disclosure, the content of structural units derived from nonionic surfactants is preferably 1% by mass or more, and 2% by mass, with respect to 100 parts by mass of the copolymer, from the viewpoint of improving polymerization stability. The above is more preferable, and from the viewpoint of improving water resistance, it is preferably 6% by mass or less, and more preferably 5% by mass or less.

In the copolymer of the present disclosure, it is preferable that the content of the structural unit derived from the nonionic surfactant is larger than the structural unit derived from the anionic surfactant, and the content of the structural unit derived from the anionic surfactant and the content ratio of the structural unit derived from the nonionic surfactant is preferably 5/95 to 40/60 from the viewpoint of improving the stability of the aqueous dispersion containing the copolymer, and 10/90 to 30/70 is more preferred, 15/85 to 25/75 is more preferred, and 17/83 to 23/77 is particularly preferred.

The copolymer of the present disclosure includes structural units derived from oxazoline group- or epoxy group-containing monomers, structural units derived from anionic surfactants, and structural units derived from other monomers other than structural units derived from nonionic surfactants. It may have a structural unit (also referred to as structural unit C). Structural units derived from other monomers are structural units obtained by polymerizing other monomers described below.

Other monomers include, for example, alkyl group-containing (meth)acrylic acid ester monomers, hydroxyl group-containing (meth)acrylic acid ester monomers, carboxyl group-containing monomers, aromatic vinyl monomers, maleimide group containing monomers, amide group-containing monomers, N-substituted (meth)acrylamide monomers, olefinic monomers, halogen-containing monomers, alkyl group-containing (meth)acrylic acid ester monomers Aromatic vinyl monomers, maleimide group-containing monomers, and vinyl cyanide monomers are preferable, and aromatic vinyl monomers are more preferable from the viewpoint of heat resistance. An alkyl group-containing (meth)acrylic acid ester monomer is preferred from the viewpoint of improving the physical properties of the film.

Examples of aromatic vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, dimethylstyrene and tert-methylstyrene. , α-chlorostyrene, β-chlorostyrene, divinylbenzene, etc., but the present invention is not limited to these examples. These aromatic vinyl monomers may be used alone or in combination of two or more. Aromatic vinyl monomers may have functional groups such as alkyl groups such as methyl groups and tert-butyl groups, nitro groups, nitrile groups, alkoxyl groups, acyl groups, sulfone groups and hydroxyl groups on the benzene ring. good. Among the aromatic vinyl monomers, styrene is preferred from the viewpoint of heat resistance and low dielectric properties. The aromatic vinyl monomer may contain an oligomer of the aromatic vinyl monomer as long as the object of the present invention is not hindered.

Examples of the alkyl group-containing (meth)acrylic acid ester monomers include linear or branched alkyl group-containing (meth)acrylic acid ester monomers having 1 to 20 carbon atoms.

Examples of alkyl group-containing (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylic acid n-butyl, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate , isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, Examples include heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, and cyclohexyl (meth)acrylate. The alkyl group-containing (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

The alkyl group-containing (meth)acrylic acid ester monomer is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms, and a (meth)acrylic acid ester having an alkyl group having 2 to 10 carbon atoms. Alkyl acrylates are more preferred, and alkyl (meth)acrylates having an alkyl group of 4 to 8 carbon atoms are even more preferred.

In addition, as the alkyl group-containing (meth) acrylic acid ester monomer of the present disclosure, an acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms is preferable, and an acrylic acid ester having an alkyl group having 2 to 10 carbon atoms Acid alkyl esters are more preferred, and acrylic acid alkyl esters having an alkyl group of 4 to 8 carbon atoms are even more preferred.

Maleimide group-containing monomers include, for example, maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-sec-butylmaleimide, N-tert-butyl Maleimide, N-amylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-nonylmaleimide, N-decylmaleimide, N-decylmaleimide, N-undecylmaleimide, N-dodecylmaleimide (N- Laurylmaleimide), N-tridecylmaleimide, N-tetradecylmaleimide, N-pentadecylmaleimide, N-hexadecylmaleimide, N-heptadecylmaleimide, N-octadecylmaleimide (N-stearylmaleimide), N-nonadecylmaleimide , N-allylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-hydroxyphenylmaleimide, N-methylphenylmaleimide, N-dimethylphenylmaleimide, N-ethylphenylmaleimide, N-diethylphenylmaleimide, N-phenylmethyl Maleimide, N-methoxyphenylmaleimide, N-chlorophenylmaleimide, N-dichlorophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide, etc., but the present invention is not limited to these examples. . These maleimide group-containing monomers may be used alone or in combination of two or more.

The hydroxyl group-containing (meth)acrylic acid ester monomer includes hydroxyalkyl (meth)acrylate (eg, 2-hydroxyethyl (meth)acrylate).

Carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, Carboxyl group-containing monomers such as itaconic acid monobutyl ester and vinyl benzoic acid are included, but the present invention is not limited to such examples.

Nitrogen atom-containing monomers include N-vinylpyrrolidone, dimethylaminoethyl (meth)acrylate, acrylonitrile, diacetoneacrylamide and the like, but the present invention is not limited to these examples.

From the viewpoint of improving heat resistance, the content of the structural unit derived from the aromatic vinyl monomer of the present disclosure is preferably 0.1% by mass or more, and 0.3% by mass or more with respect to 100 parts by mass of the copolymer. More preferably, from the viewpoint of low-temperature reactivity, it is preferably 40% by mass or less, more preferably 10% by mass or less, and more preferably 5% by mass or less.

From the viewpoint of improving heat resistance, the content of the structural unit derived from the aromatic vinyl monomer of the present disclosure is preferably 0.1% by mass or more with respect to 100 parts by mass of the structural unit derived from the other monomer. 3% by mass or more is more preferable, 0.5% by mass or more is still more preferable, and from the viewpoint of low-temperature reactivity, 40% by mass or less is preferable, 35% by mass or less is more preferable, and 30% by mass or less is even more preferable.

The content ratio of structural units derived from the alkyl group-containing (meth) acrylic acid ester monomer of the present disclosure is preferably 40% by mass or more, and 50% by mass with respect to 100 parts by mass of the copolymer, from the viewpoint of low-temperature reactivity. % or more, 60 mass % or more, 70 mass % or more, and 75 mass % or more, in this order, preferably 95 mass % or less, and more preferably 90 mass % or less, and 85 mass % or less.

The content of the structural unit derived from the alkyl group-containing (meth) acrylic acid ester monomer of the present disclosure is 50% by mass or more with respect to 100 parts by mass of the structural unit derived from other monomers, from the viewpoint of low-temperature reactivity. It is preferably 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more, in that order, preferably less than 100% by mass, and more preferably 99.5% by mass or less.

The glass transition temperature (Tg) of the copolymer (nonvolatile content) of the present disclosure is not particularly limited, but from the viewpoint of low temperature reactivity, it is preferably less than 10 ° C., more preferably 0 ° C. or less, and -10 ° C. or less. More preferably -20 ° C. or lower, particularly preferably -30 ° C. or lower in that order, from the viewpoint of blocking resistance of the coating film, -100 ° C. or higher is preferable, -80 ° C. or higher is more preferable, -70 ° C. or higher, 60 ° C. or higher , −50° C. or higher, in this order is more preferable.

The glass transition temperature can be measured by differential calorimetry, but may be estimated from the following Fox equation.

In the calculation formula (1), Tg' is the Tg (absolute temperature) of the polymer. W ₁ ', W ₂ ', . . . W _n ' are mass fractions of each monomer relative to the total monomer components. T ₁ , T ₂ , . . . _Tn are the glass transition temperatures (absolute temperatures) of homopolymers (single polymers) composed of respective monomer components.

The Tg values of representative homopolymers used for calculating the glass transition temperature (Tg) of the polymerizable monomer component by the above formula (1) are shown below.
2-isopropenyl-2-oxazoline (IPO): 100°C
Styrene (St): 100°C
Butyl acrylate (BA): -54°C
The copolymer of the present disclosure may be dissolved in a solution or may be an aqueous dispersion dispersed in water, but from the viewpoint of environmental protection and occupational safety and health, it is preferably an aqueous dispersion. .

The aqueous solvent of the present disclosure includes, for example, water and a mixed solvent of water and a water-soluble organic solvent. 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; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, Examples include polyhydric alcohols such as diethylene glycol; ketones such as acetone and methyl ethyl ketone; however, the present invention is not limited to these examples. These aqueous media may be used alone or in combination of two or more.

The content of water in the aqueous solvent of the present disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more, from the viewpoint of improving the dispersion stability of the emulsion particle-containing aqueous dispersion. Furthermore, it is more preferably 80% by mass or more, and the upper limit of the content is 100% by mass. Among water-based solvents, water is preferred. The emulsion particle-containing aqueous dispersion of the present invention may contain, for example, additives as long as the object of the present invention is not hindered. Examples of the additives include coloring agents such as pigments, leveling agents, UV absorbers, UV stabilizers, antioxidants, polymerization inhibitors, fillers, coupling agents, rust inhibitors, antibacterial agents, and metal deactivators. agent, wetting agent, antifoaming agent, surfactant, reinforcing agent, plasticizer, lubricant, antifogging agent, anticorrosion agent, pigment dispersant, flow control agent, peroxide decomposer, mold bleaching agent, fluorescence Brightening agent, organic flame retardant, inorganic flame retardant, anti-dripping agent, melt flow modifier, anti-static agent, anti-algae agent, anti-mold agent, flame retardant agent, slip agent, metal chelating agent, anti-blocking agent , heat stabilizers, processing stabilizers, dispersants, thickeners, rheology control agents, foaming agents, anti-aging agents, preservatives, antistatic agents, silane coupling agents, antioxidants, film formation aids, etc. However, the invention is not limited to only such exemplifications. These additives may be used alone or in combination of two or more. Since the amount of these additives varies depending on the type of the additive and cannot be generally determined, it is preferable to appropriately determine the amount according to the type of the additive.

[Method for producing the copolymer of the present disclosure]
A method for producing a copolymer of the present disclosure includes a step of polymerizing an oxazoline group- or epoxy group-containing monomer, an anionic surfactant having a reactive group, and a nonionic surfactant having a reactive group. Having a reactive group means a surfactant that has an unsaturated double bond in the monomer and is polymerizable with other monomers. ) having a radically polymerizable double bond such as an acryloyl group, an allyl group, or a propenyl group;

In the method for producing the copolymer of the present disclosure, the oxazoline group- or epoxy group-containing monomer is also referred to as monomer A.

The oxazoline group-containing monomer of the present disclosure used in the method for producing the copolymer of the present disclosure includes, for example, vinyloxazolines {eg, vinyloxazoline (2-vinyl-2-oxazoline, etc.), vinyloxazoline having a substituent [For example, alkyl-vinyloxazolines (e.g., 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2- Vinyl-4-propyl-2-oxazoline, 2-vinyl-4-butyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-5-ethyl-2-oxazoline, 2-vinyl- C _1-20 alkyl-vinyloxazoline such as 5-propyl-2-oxazoline, 2-vinyl-5-butyl-2-oxazoline, preferably C _1-10 alkyl-vinyloxazoline, more preferably mono- or di-C _{1- 4} alkyl-vinyl oxazoline), etc.}, isopropenyl oxazolines {e.g., isopropenyl oxazoline (2-isopropenyl-2-oxazoline, etc.), isopropenyl oxazoline having substituents [e.g., alkyl-isopropenyl oxazoline (e.g., , 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-4-propyl -2-oxazoline, 2-isopropenyl-4-butyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-5 -C _1-20 alkyl-isopropenyloxazoline, preferably C _1-10 alkyl-isopropenyloxazoline such as propyl-2-oxazoline, 2-isopropenyl-5-butyl-2-oxazoline, more preferably mono or di-C _1-4 alkyl-isopropenyl oxazoline)] and the like}, corresponding allyl oxazolines, and the like.

Among these, isopropenyloxazolines are preferred, and 2-isopropenyl-2-oxazoline is particularly preferred.

The oxazoline group-containing monomers may be used alone or in combination of two or more.

Examples of methods for polymerizing the monomer components of the present disclosure include bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., but the present invention is limited only to such examples. is not. Among these polymerization methods, the solution polymerization method and the emulsion polymerization method are preferable, and the emulsion polymerization method is more preferable, since a polymer having an oxazoline group in a side chain can be easily prepared.

Examples of the epoxy group-containing monomer used in the method for producing the copolymer of the present disclosure include unsaturated carboxylic acid glycidyl esters and vinyl group-containing glycidyl ethers, but the present invention is limited only to such examples. not something. These epoxy group-containing monomers may be used alone or in combination of two or more.

Examples of unsaturated carboxylic acid glycidyl esters include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate [3,4-epoxycyclohexylmethyl (meth)acrylate], monoglycidyl itaconate [itaconic acid, monoglycidyl ester], monoglycidyl butene tricarbonate [butene tricarboxylic acid monoglycidyl ester], etc., but the present invention is not limited to these examples. These unsaturated carboxylic acid glycidyl esters may be used alone or in combination of two or more. Vinyl group-containing glycidyl ethers include, for example, vinyl glycidyl ether, allyl glycidyl ether, glycidyloxyethyl vinyl ether, etc., but the present invention is not limited to these examples. These vinyl group-containing glycidyl ethers may be used alone or in combination of two or more. Among the epoxy group-containing monomers, glycidyl (meth)acrylate is preferred from the viewpoint of improving adhesiveness, heat resistance and bendability.

In the method for producing the copolymer of the present disclosure, the amount of the oxazoline group-containing monomer used is the amount of the monomer used in the copolymer from the viewpoint of improving the low-temperature reactivity and the physical properties of the coating film when used as a crosslinking agent. With respect to 100 parts by mass of the body, 1% by mass or more (e.g., 3% by mass or more) is preferable, 5% by mass or more is more preferable, 10% by mass or more is still more preferable, and 15% by mass or more is particularly preferable. Therefore, it is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less, and particularly preferably 25% by mass or less.

In the method for producing a copolymer of the present disclosure, the amount of the epoxy group-containing monomer used is determined from the viewpoint of improving the low-temperature reactivity and physical properties of the coating film when used as a cross-linking agent. With respect to 100 parts by mass of the body, 1% by mass or more (e.g., 3% by mass or more) is preferable, 5% by mass or more is more preferable, 10% by mass or more is still more preferable, and 15% by mass or more is particularly preferable. Therefore, it is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less, and particularly preferably 25% by mass or less.

In addition, in the present disclosure, it is preferable to use an oxazoline group-containing monomer as the oxazoline group- and/or epoxy group-containing monomer. By essentially containing the oxazoline group-containing monomer, it can be expected that the physical properties of the coating film formed by the low-temperature reactivity and cross-linking reaction will be good, and the storage stability when used as an aqueous dispersion will be good. can be expected to become

In the method for producing a copolymer of the present disclosure, an anionic surfactant having a reactive group from the viewpoint of improving low-temperature reactivity, stability during emulsion polymerization, and stability when made into an aqueous dispersion, and reactivity It is preferred to use a nonionic surfactant having a group. Having a reactive group means a surfactant that has an unsaturated double bond in the monomer and is polymerizable with other monomers. ) having a radically polymerizable double bond such as an acryloyl group, an allyl group, or a propenyl group; Hereinafter, a surfactant having a reactive group is also referred to as a monomer B, an anionic surfactant having a reactive group as a monomer b1, and a nonionic surfactant having a reactive group as a monomer b2. To tell.

Preferred examples of the anionic surfactant having a reactive group of the present disclosure include an anionic surfactant represented by the following formula (1) and an anionic surfactant represented by the following formula (2). mentioned.

Among these, as an anionic surfactant having a reactive group, for example, from the viewpoint of industrial productivity, more specifically, the (meth)acrylic resin emulsion can be maintained at a low viscosity and is excellent in handleability, An anionic surfactant represented by the following formula (1) is more preferred.

In formula (1), R ^1a represents an aliphatic alkyl group having 6 to 24 carbon atoms, and X ^1a represents —SO ₃ NH ₄ or —SO ₃ Na.

In formula (1), n1 represents the average number of added moles of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n1 is an integer of 5-50, preferably an integer of 10-30.

Examples of commercially available anionic surfactants represented by formula (1) include Aqualon (registered trademark) KH-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate [oxyethylene Average number of moles of added groups: 10], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) KH-05 [active ingredient: polyoxyethylene-1-(allyloxymethyl) Ammonium alkyl ether sulfate [average number of added moles of oxyethylene group: 5], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Adekaria Soap (registered trademark) SR-20 [active ingredient: polyoxyethylene -1-(Allyloxymethyl)alkyl ether ammonium sulfate [average number of added moles of oxyethylene group: 20], amount of active ingredient: 100% by mass, ADEKA Corporation] and the like.

In formula (2), R ^2a represents a substituent represented by formula (A) below or an aliphatic alkyl group having 6 to 24 carbon atoms, and R ^3a represents a methyl group.

In formula (2), X ^2a represents -SO ₃ M, -COOM, or PO ₃ M.

M represents an alkali metal atom, an alkaline earth metal atom, or an ammonium group.

Specific examples of alkali metal atoms include a sodium atom and a potassium atom.

Specific examples of alkaline earth metal atoms include calcium atoms and barium atoms.

X ^2a is preferably —SO ₃ NH ₄ , for example.

In formula (2), n2 represents the average added mole number of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n2 is an integer of 5-50, preferably an integer of 10-30.

In formula (A), m represents an integer of 1 to 3, preferably 2, for example, from the viewpoint of surface activity.

Examples of commercially available anionic surfactants represented by formula (2) include Aqualon (registered trademark) HS-10 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 10], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) BC-10 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 10], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) BC-20 [active ingredient: polyoxyethylene nonylpropenylphenyl ether ammonium sulfate [average number of moles of oxyethylene groups added : 20], active ingredient amount: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) AR-10 [active ingredient: polyoxyethylene styrenated propenylphenyl ether sulfate ester ammonium [average of oxyethylene group Number of added moles: 10], amount of active ingredient: 99% by mass, Daiichi Kogyo Seiyaku Co., Ltd.], Aqualon (registered trademark) AR-20 [active ingredient: polyoxyethylene styrenated propenylphenyl ether sulfate ester ammonium [oxyethylene Average number of moles of added group: 20], amount of active ingredient: 97% by mass, Daiichi Kogyo Seiyaku Co., Ltd.] and the like.

As the anionic surfactant having a reactive group, from the viewpoint of the water resistance and polymerization stability of the coating film, the Adekari Soap SR series (Adekari Soap SR-10, SR-20, etc.) is preferable. (registered trademark) SR-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate [average number of added moles of oxyethylene group: 10], amount of active ingredient: 100% by mass, ADEKA Corporation ] is more preferable.

In the method for producing a copolymer of the present disclosure, the amount of the anionic surfactant having a reactive group used is 0.1% by mass or more with respect to 100% by mass of the copolymer from the viewpoint of improving polymerization stability. is preferred, 0.5 or more is more preferred, and from the viewpoint of improving water resistance, 5% by mass or less is preferred, and 2% by mass or less is more preferred.

As the nonionic surfactant having a reactive group of the present disclosure, a nonionic surfactant represented by the following formula (3) and a nonionic surfactant represented by the following formula (4) are preferred examples. mentioned.

Among these, as a nonionic surfactant having a reactive group, for example, from the viewpoint of excellent copolymerizability with a monomer, nonionic surfactants represented by the following formula (3) are more preferred. preferable.

In formula (3), R ^1b represents an aliphatic alkyl group having 6 to 24 carbon atoms, and X ^1b represents a hydrogen atom.

In formula (3), n3 represents the average number of added moles of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n3 is an integer of 5-40, preferably an integer of 10-30.

In formula (4), R ^2b represents an aliphatic alkyl group having 6 to 24 carbon atoms, R ^3b represents a methyl group, and X ^2b represents a hydrogen atom.

In formula (4), n4 represents the average added mole number of oxyethylene groups (also referred to as "average number of repeating oxyethylene units"). n4 is an integer of 10-50, preferably an integer of 10-30.

Commercially available examples of nonionic surfactants represented by formula (3) include Adekari Soap (registered trademark) ER-10 [active ingredient: polyoxyethylene-1-(allyloxymethyl) alkyl ether [oxy Average number of added moles of ethylene group: 10], amount of active ingredient: 100% by mass, ADEKA Corporation], Adekari Soap (registered trademark) ER-30 [active ingredient: polyoxyethylene-1-(allyloxymethyl) Alkyl ether [average number of added moles of oxyethylene group: 30], amount of active ingredient: 65% by mass, ADEKA Corporation], Adekari Soap (registered trademark) ER-40 [active ingredient: polyoxyethylene-1-( allyloxymethyl)alkyl ether [average number of added moles of oxyethylene group: 40], amount of active ingredient: 60% by mass, ADEKA Corporation] and the like.

As the nonionic surfactant having a reactive group, Adekari Soap ER series (Adekari Soap ER-10, ER-20, etc.) is preferable from the viewpoint of the water resistance and polymerization stability of the coating film. Examples of commercially available nonionic surfactants having number: 20], amount of active ingredient: 100% by mass, ADEKA Corporation] is more preferred.

In the method for producing a copolymer of the present disclosure, it is preferable that the content of the nonionic surfactant is higher than the amount of the anionic surfactant, and the amount of the nonionic surfactant having a reactive group used is From the viewpoint of improving polymerization stability, it is preferably 1% by mass or more, more preferably 2% by mass or more, with respect to 100 parts by mass of the copolymer, and from the viewpoint of improving water resistance, preferably 6% by mass or less, and 5% by mass. The following are more preferred.

In the method for producing the copolymer of the present disclosure, it is preferable that the content ratio of the structural unit derived from the nonionic surfactant is larger than the structural unit derived from the anionic surfactant, and the anionic surfactant having a reactive group The mass ratio of the content of the agent and the amount of the nonionic surfactant having a reactive group is preferably 5/95 to 40/60 from the viewpoint of improving the stability of the aqueous dispersion containing the copolymer. , more preferably 10/90 to 30/70, more preferably 15/85 to 25/75, and particularly preferably 17/83 to 23/77.

In the method for producing a copolymer of the present disclosure, oxazoline group- or epoxy group-containing monomers, reactive anionic surfactants, and other monomers other than reactive nonionic surfactants (monomers C) may also be used.

Other monomers include, for example, alkyl group-containing (meth)acrylic acid ester monomers, hydroxyl group-containing (meth)acrylic acid ester monomers, carboxyl group-containing monomers, aromatic vinyl monomers, maleimide group containing monomers, amide group-containing monomers, N-substituted (meth)acrylamide monomers, olefinic monomers, halogen-containing monomers, alkyl group-containing (meth)acrylic acid ester monomers Aromatic vinyl monomers, maleimide group-containing monomers, and vinyl cyanide monomers are preferable, and aromatic vinyl monomers are more preferable from the viewpoint of heat resistance. An alkyl group-containing (meth)acrylic acid ester monomer is preferred from the viewpoint of improving the physical properties of the film.

Examples of aromatic vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, dimethylstyrene and tert-methylstyrene. , α-chlorostyrene, β-chlorostyrene, divinylbenzene, etc., but the present invention is not limited to these examples. These aromatic vinyl monomers may be used alone or in combination of two or more. Aromatic vinyl monomers may have functional groups such as alkyl groups such as methyl groups and tert-butyl groups, nitro groups, nitrile groups, alkoxyl groups, acyl groups, sulfone groups and hydroxyl groups on the benzene ring. good. Among the aromatic vinyl monomers, styrene is preferred from the viewpoint of heat resistance and low dielectric properties. The aromatic vinyl monomer may contain an oligomer of the aromatic vinyl monomer as long as the object of the present invention is not hindered.

Examples of the alkyl group-containing (meth)acrylic acid ester monomers include linear or branched alkyl group-containing (meth)acrylic acid ester monomers having 1 to 20 carbon atoms.

Examples of alkyl group-containing (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylic acid n-butyl, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate , isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, Examples include heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, and cyclohexyl (meth)acrylate. The alkyl group-containing (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

The alkyl group-containing (meth)acrylic acid ester monomer is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms, and a (meth)acrylic acid ester having an alkyl group having 2 to 10 carbon atoms. Alkyl acrylates are more preferred, and alkyl (meth)acrylates having an alkyl group of 4 to 8 carbon atoms are even more preferred.

In addition, as the alkyl group-containing (meth) acrylic acid ester monomer of the present disclosure, an acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms is preferable, and an acrylic acid ester having an alkyl group having 2 to 10 carbon atoms Acid alkyl esters are more preferred, and acrylic acid alkyl esters having an alkyl group of 4 to 8 carbon atoms are even more preferred.

Maleimide group-containing monomers include, for example, maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-sec-butylmaleimide, N-tert-butyl Maleimide, N-amylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-nonylmaleimide, N-decylmaleimide, N-decylmaleimide, N-undecylmaleimide, N-dodecylmaleimide (N- Laurylmaleimide), N-tridecylmaleimide, N-tetradecylmaleimide, N-pentadecylmaleimide, N-hexadecylmaleimide, N-heptadecylmaleimide, N-octadecylmaleimide (N-stearylmaleimide), N-nonadecylmaleimide , N-allylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-hydroxyphenylmaleimide, N-methylphenylmaleimide, N-dimethylphenylmaleimide, N-ethylphenylmaleimide, N-diethylphenylmaleimide, N-phenylmethyl Maleimide, N-methoxyphenylmaleimide, N-chlorophenylmaleimide, N-dichlorophenylmaleimide, N-trichlorophenylmaleimide, N-tribromophenylmaleimide, etc., but the present invention is not limited to these examples. . These maleimide group-containing monomers may be used alone or in combination of two or more.

The hydroxyl group-containing (meth)acrylic acid ester monomer includes hydroxyalkyl (meth)acrylate (eg, 2-hydroxyethyl (meth)acrylate).

Carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, Carboxyl group-containing monomers such as itaconic acid monobutyl ester and vinyl benzoic acid are included, but the present invention is not limited to such examples.

Nitrogen atom-containing monomers include N-vinylpyrrolidone, dimethylaminoethyl (meth)acrylate, acrylonitrile, diacetoneacrylamide and the like, but the present invention is not limited to these examples.

In the method for producing the copolymer of the present disclosure, the amount of the aromatic vinyl monomer used is 0.1% by mass or more with respect to 100 parts by mass of the monomer used in the copolymer from the viewpoint of improving heat resistance. It is preferably 0.3% by mass or more, more preferably 40% by mass or less, more preferably 10% by mass or less, and more preferably 5% by mass or less from the viewpoint of low-temperature reactivity.

In the method for producing the copolymer of the present disclosure, the amount of the aromatic vinyl monomer used is preferably 0.1% by mass or more relative to 100 parts by mass of other monomers, from the viewpoint of improving heat resistance. 3% by mass or more is more preferable, 0.5% by mass or more is still more preferable, and from the viewpoint of low-temperature reactivity, 40% by mass or less is preferable, 35% by mass or less is more preferable, and 30% by mass or less is even more preferable.

In the method for producing a copolymer of the present disclosure, the amount of the alkyl group-containing (meth)acrylic acid ester monomer used is 40% by mass or more with respect to 100 parts by mass of the copolymer from the viewpoint of low-temperature reactivity. Preferably, the order of 50% by mass or more, 60% by mass or more, 70% by mass or more, and 75% by mass or more is more preferable, 95% by mass or less is preferable, and 90% by mass or less, and 85% by mass or less is more preferable.

In the method for producing the copolymer of the present disclosure, the amount of the alkyl group-containing (meth)acrylic acid ester monomer used is 50 parts by mass with respect to 100 parts by mass of structural units derived from other monomers, from the viewpoint of low-temperature reactivity. It is preferably 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, and 95% by mass or more in this order, preferably less than 100% by mass, and 99.5% by mass or less. more preferred.

The polymerization method is not particularly limited, and known polymerization methods such as suspension polymerization, emulsion polymerization and dispersion polymerization can be employed. Among these, emulsion polymerization is preferred.

In the method for producing the copolymer of the present disclosure, a solvent-based solvent or an aqueous solvent may be used, but it is preferable to use an aqueous solvent from the viewpoint of environmental protection and occupational safety and health.

The aqueous solvent of the present disclosure includes, for example, water and a mixed solvent of water and a water-soluble organic solvent. 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; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, Examples include polyhydric alcohols such as diethylene glycol; ketones such as acetone and methyl ethyl ketone; however, the present invention is not limited to these examples. These aqueous media may be used alone or in combination of two or more.

The content of water in the aqueous solvent of the present disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more, from the viewpoint of improving the dispersion stability of the emulsion particle-containing aqueous dispersion. , Still more preferably, it is 80% by mass or more, and the upper limit of the content is 100 parts by mass. Among the aqueous solvents, water is preferable. In the method for producing a copolymer of the present disclosure, the polymerization initiator is not particularly limited. For example, azo compounds such as 2,2-azobis(2-diaminopropane) hydrochloride; persulfates such as potassium persulfate; peroxides such as hydrogen peroxide; and the like. Specifically, for example, azo oily compounds (e.g., azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile) etc.), aqueous compounds (e.g. anionic 4,4-azobis (4-cyanovaleric acid), cationic 2,2-azobis (2-methylpropionamidine)); redox oily peroxides (e.g. , benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, etc.), aqueous peroxides (eg, potassium persulfate and ammonium peroxide, etc.); In addition, only 1 type may be used for a polymerization initiator and it may use 2 or more types together.

The amount of the polymerization initiator to be used is not particularly limited, but is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.1% by mass, based on 100 parts by mass of all the monomer components. 5% by mass is preferable.

The addition method is not particularly limited, and may be, for example, any method such as batch charging, divided charging, or continuous dropwise addition. Furthermore, in order to hasten the completion of the polymerization, part of the polymerization initiator may be added before or after the completion of dropping the polymerizable monomer component in the final stage.

In the method for producing the copolymer of the present disclosure, for example, a reducing agent such as sodium bisulfite or a transition metal salt such as ferrous sulfate may be added for the purpose of promoting decomposition of the polymerization initiator. In the emulsion polymerization step, if necessary, known additives such as pH buffers, chelating agents, chain transfer agents, and film-forming aids may be added. Chain transfer agents include compounds having a thiol group such as t-dodecylmercaptan. Examples of film-forming aids include 2,2,4-trimethyl-1,3-pentanediol isobutyrate. The amount of the additive used is not particularly limited, but is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on 100% by mass of the resin emulsion.

In the method for producing the copolymer of the present disclosure, surfactants other than the anionic surfactant having a reactive group and the nonionic surfactant having a reactive group may be used.

Surfactants other than anionic surfactants with reactive groups and nonionic surfactants with reactive groups are cationic surfactants with reactive groups, surfactants with no reactive groups agents.

In the method for producing a copolymer of the present disclosure, the content of surfactants other than the anionic surfactant having a reactive group and the nonionic surfactant having a reactive group is 100 parts by mass of the total surfactant. is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably not substantially used. The term "substantially not used" is not limited to not used at all, but also includes the case of slightly used. In particular, when the use of a large amount of surfactant may cause physical property problems, the surfactant may be used in a small amount that does not cause the problem, and the polymerization may be carried out. As the surfactant, a known surfactant that can be used in the emulsion polymerization method can be used.

In the method for producing a copolymer of the present disclosure, the atmosphere during polymerization is not particularly limited, but from the viewpoint of increasing the efficiency of the polymerization reaction, an inert gas such as nitrogen gas is preferable.

In the method for producing the copolymer of the present disclosure, the polymerization temperature 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.

In the method for producing a copolymer of the present disclosure, the polymerization time is not particularly limited, and may be appropriately set according to the progress of the reaction. For example, the polymerization time is in the range of 2 to 24 hours. is preferred, more preferably in the range of 4 to 8 hours.

[Applications of the copolymer of the present disclosure]
Common uses of the copolymer or aqueous dispersion of the present disclosure include various inks such as flexographic printing inks and inkjet printer inks, road marking paints, conductive paints, plastic paints, and inorganic building material paints. , metal paints, leather paints, and repair paints; primers for organic substrates, inorganic substrates, and difficult-to-adhere substrates; binders for water-repellent finishing and finishing; Various fiber processing agents such as processing binders and tire cord processing agents; various lamination adhesives such as dry laminates and extrusion laminates; various adhesives such as wood adhesives and structural adhesives; antistatic agents; Conductive rollers to be used; top coats; adhesives; various cosmetics such as manicures and hair setting agents;

<Production Example 1 (Production of a polymer having a 2-oxazoline group)>
A flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer and dropping funnel was charged with 692 parts of deionized water. 31.5 parts of a 25% aqueous solution of an anionic surfactant (“ADEKARI SOAP SR-10/ADEKA Co., Ltd.”) and a nonionic surfactant (“ADEKARI SOAP ER-20”/ADEKA Co., Ltd.) were added to a dropping funnel. A pre-emulsion consisting of 94.4 parts, 167.6 parts deionized water, 624.8 parts butyl acrylate, 3.9 parts styrene, 157.4 parts 2-isopropenyl-2-oxazoline and 6 parts divinylbenzene is prepared. Then, 65 parts corresponding to 6% of the total amount of all the polymerizable monomer components was added to the flask, adjusted to pH 9.0 with an appropriate amount of 25% by mass aqueous ammonia, and slowly heated to 70°C by introducing nitrogen gas. I warmed up. Then, 152 parts of a 2.5% by mass aqueous solution of potassium persulfate was injected to initiate polymerization. The rest of the pre-emulsion was then added dropwise evenly over 180 minutes. Nitrogen gas was continuously blown during the reaction, and after the dropping was completed, the dropping funnel was washed with 125 parts of deionized water, poured into the flask, the internal temperature was raised to 80°C, and stirring was continued for 3 hours to complete the reaction. After that, the mixture was cooled and filtered through a 300-mesh wire mesh to separate aggregates to obtain an aqueous dispersion of a polymer having a 2-oxazoline group (polymer (A)) with a pH of 8.0. When the non-volatile content was measured, it was 40.0% by mass. The glass transition temperature of the polymer was -34°C as estimated by the Fox formula. In addition, the average particle size (volume average particle size) of the emulsion particles contained in the aqueous dispersion was measured using a particle size distribution analyzer (“NICOMP Model 380” manufactured by Particle Sizing Systems) using a dynamic light scattering method.
The amount of each monomer and surfactant used in Table 1 is shown as a ratio (parts by mass) to 100 parts by weight of the total amount of all polymer components. Table 1 shows the evaluation results of various physical properties of the obtained aqueous dispersion.

<Production Examples 2 to 12>
A water dispersion was obtained in the same manner as in Production Example 1 except that the surfactant and monomer components listed in Table 1 were used for polymerization. Table 1 shows the results of evaluating various physical properties of these materials. Various physical properties were evaluated as follows.
<Tg>
It was calculated using the following Fox formula from the monomer composition used for polymerization.

計算式（１）中、Ｔｇ’は、重合体のＴｇ（絶対温度）である。Ｗ_１’、Ｗ_２’、・・・Ｗ_ｎ’は、全単量体成分に対する各単量体の質量分率である。Ｔ_１、Ｔ_２、・・・Ｔ_ｎは、それぞれ各単量体成分からなるホモポリマー（単独重合体）のガラス転移温度（絶対温度）である。なおジビニルベンゼン（ＤＶＢ）を含む重合性単量体については該ＤＶＢを除いて算出したＴｇを該重合性単量体成分のガラス転移温度とした。

In the calculation formula (1), Tg' is the Tg (absolute temperature) of the polymer. W ₁ ', W ₂ ', . . . W _n ' are mass fractions of each monomer relative to the total monomer components. T ₁ , T ₂ , . . . _Tn are the glass transition temperatures (absolute temperatures) of homopolymers (single polymers) composed of respective monomer components. As for the polymerizable monomer containing divinylbenzene (DVB), the Tg calculated excluding the DVB was taken as the glass transition temperature of the polymerizable monomer component.

The Tg value of each homopolymer is shown below.
2-isopropenyl-2-oxazoline (IPO): 100°C
Styrene (St): 100°C
Butyl acrylate (BA): -54°C

<Non-volatile content (NV)>
About 1 g of the obtained water-based resin composition was weighed and dried at 150° C. for 30 minutes in a hot air dryer, and the remaining amount after drying was calculated as a non-volatile content, and the ratio to the weight before drying was calculated and displayed as % by mass.
formula:
[Non-volatile content (mass%) in aqueous resin composition]
= ([Dry residue] ÷ [1 g of aqueous resin composition]) × 100

<pH>
The value at 25° C. was measured with a pH meter (“F-23” manufactured by Horiba, Ltd.).
<Viscosity>
It was measured at 30 min-1 and 25°C with a BM type viscometer (manufactured by Tokyo Keiki Co., Ltd.). When measuring the viscosity, the rotor was selected according to the viscosity.
<Average particle size>
The volume average particle size was measured using a particle size distribution analyzer (“NICOMP Model 380” manufactured by Particle Sizing Systems) using a dynamic light scattering method.

<Emulsibility>
In a flask, 782.4 parts by mass of deionized water and a certain amount of each surfactant used in Examples 1 to 8 and Comparative Examples 1 to 4 (3 masses with respect to the total amount of deionized water and the monomer mixture %) was added to prepare an aqueous solution. Ease of emulsification when a monomer mixture having the same composition as the above monomer mixture was added to the aqueous solution was evaluated according to the following criteria.
A: The monomer mixture was added all at once and emulsified by stirring at 300 rpm for 15 minutes.
B: Emulsification is not possible when the monomer mixture is added all at once, but emulsification is possible when the monomer mixture is added in 10 portions and stirred at 300 rpm for 15 minutes after each addition. rice field.
C: Could not be emulsified.

<Polymerization stability>
The mass of the separated aggregates was measured immediately after the emulsion polymerization, and the ratio (%) to the total amount of the aqueous dispersion was calculated and evaluated according to the following criteria. Table 1 shows the results.
A: Less than 0.1% aggregate amount B: 0.1 to 1.0% aggregate amount
C: the aggregate amount is greater than 1.0%

<Mechanical stability>
Each aqueous dispersion obtained was subjected to a Maron mechanical stability test under the following conditions. As a tester, a trade name: "No. 156 Maron Mechanical Stability Tester" manufactured by Yasuda Seiki Seisakusho Co., Ltd. was used. After the test, the sample was filtered through a 100-mesh wire mesh and the mass of aggregate collected was measured. The ratio of the mass of the generated aggregates to the amount of the sample used in the test was calculated and evaluated according to the following criteria. Table 1 shows the results. The smaller the aggregation rate, the better the mechanical stability.
A: Aggregate amount less than 0.03% B: Aggregate amount 0.03 to 0.1%
C: The amount of aggregates is greater than 0.1% (test conditions)
Sample amount: 70g
Load: 10kg
Rotation speed: 1000rpm
Test time: 10 minutes

<Water whitening resistance>
Each of the resulting aqueous dispersions was dried on a glass plate (length: 15 cm, width: 7 cm) in an atmosphere of 23±2° C. and 65±3% relative humidity to a film thickness of 150 μm. It was applied using an applicator as shown. The glass plate was allowed to stand in this atmosphere for 2 minutes, then heated at 120° C. for 30 minutes and allowed to cool, thereby producing a glass plate having a coating film formed thereon.
After the opening of a glass tube with a diameter of 30 mm and a length of 30 mm was placed on the coating film of the glass plate on which this coating film was formed and adhered, ionization was performed so that the coating film inside the glass tube was in contact with water. After 10 mL of exchanged water was poured into the glass tube, it was left for 24 hours in an atmosphere of 23±2° C. and 65±3% relative humidity. After that, the state of the coating film in contact with the ion-exchanged water was visually observed and evaluated based on the following evaluation criteria. The smaller the change in the coating film after the test compared to the coating film before the start of the test, the better the resistance to water whitening.
(Evaluation criteria)
A: No change is observed in the coating film.
B: Part of the coating film is slightly clouded.
C: Whitening is observed over the entire coating film.

<Production Example 2 (Production of acrylic emulsion having an acid group)>
A flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer and dropping funnel was charged with 376.5 parts of deionized water. Hytenol N-08 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 15% by weight aqueous solution of polyoxyethylene nonylphenyl ether sulfate ammonium salt) was added to the dropping funnel, 70.8 parts, 2-ethylhexyl acrylate 131 parts, styrene 205 parts and acrylic acid. A pre-emulsion consisting of 17 parts was prepared, 5 mass % of the total amount of all polymerizable monomer components was added to the flask, nitrogen gas was slowly introduced, and the temperature was raised to 80°C. Then, 21 parts by mass of a 5% by mass aqueous solution of potassium persulfate was injected to initiate polymerization. After 10 minutes, the remaining monomer mixture was added dropwise over 3 hours. Nitrogen gas was continuously blown during the reaction to keep the temperature in the flask at 80±1°C. After the completion of dropping, the same temperature is maintained for 1 hour, then cooled, adjusted to pH 8.5 with 9 parts by mass of 25% by mass ammonia water, and an acrylic emulsion with a non-volatile content of 44.1% by mass and pH 8.5 (polymer (B)) obtained.

<Evaluation of coating properties>
Polymer having a 2-oxazoline group produced in Examples 1-8 and Comparative Examples 1-4 (polymer (A)) was blended to 5 parts by mass to obtain a coating composition (clear coating). The coating compositions obtained were tested for the following various properties. Table 1 shows the results.

<Low temperature reactivity>
Each clear paint is applied to a glass plate (length: 15 cm, width: 7 cm) in an atmosphere with a temperature of 23 ± 2 ° C and a relative humidity of 65 ± 3%. was applied using By drying the glass plate in this atmosphere for 24 hours,
A glass plate having a coating film formed thereon was produced. From the glass plate on which the coating film is formed, the coating film is peeled off with a cutter blade, and the stripped coating film (free film) is cut into a size of 25 mm × 25 mm to prepare a test piece. After measuring the mass (W ₁ ) of the test piece, immerse it in ethyl acetate under this atmosphere for 24 hours, remove the insoluble matter by filtration, dry the insoluble matter, and then weigh the insoluble matter (W ₂ ) was measured. Low-temperature reactivity was evaluated based on the following evaluation criteria in comparison with the results of a blank containing no polymer having a 2-oxazoline group. The higher the gel fraction increase rate, the better the low-temperature reactivity.
A: Gel fraction increase rate of 30% or more.
B: Gel fraction increase rate 0% to 30%
C: Gel fraction does not increase.
The gel fraction is given by the formula:
[Gel fraction] = [[mass of test piece (W ₁ )] ÷ [mass of insoluble matter (W ₂ )]] × 100
sought based on

<Tensile test>
The coated glass plate used in the low-temperature reactivity test was stripped off with a cutter blade, and the stripped coating (free film) was used as a film for strength measurement. The film for strength measurement was stored for 24 hours in a constant temperature and humidity room (temperature 25° C., humidity 60% RH). Then, it was gripped by a chuck of a tensile tester (manufactured by Shimadzu Corporation, product name: Autograph AGS-100D) and subjected to a tensile test according to JIS P-8113.

<Film strength>
The tensile strength of the film formed from the acrylic emulsion clear paint (paint not blended with the polymer (A)) produced in Production Example 2 by the above tensile test was taken as a blank, and the blank and Examples 1 to 8 and comparison The tensile strength was compared with the films formed from the clear paints containing the aqueous dispersions of Examples 1-4. The results were evaluated according to the following criteria.
A: The strength increased by more than 1.5 times compared to the blank.
B: The strength was 1.0 to 1.5 times that of the blank.

<Film elongation>
The elongation of the film formed from the acrylic emulsion clear paint (paint not blended with the polymer (A)) produced in Production Example 2 by the above tensile test was used as a blank, and the blank, Examples 1 to 8, and Comparative Example. The elongation was compared with the film formed from each clear paint containing 1 to 4 aqueous dispersions. The results were evaluated according to the following criteria.
A: The elongation became greater than 1.5 times compared to the blank.
B: The elongation was 1.0 to 1.5 times that of the blank.

The surfactants and monomers in Table 1 are as follows.
<Surfactant>
-Anionic surfactant-
Adekaria Soap SR-10: Ether sulfate type ammonium salt (manufactured by ADEKA Co., Ltd.)
Adekaria Soap SR-20: Ether sulfate type ammonium salt (manufactured by ADEKA Co., Ltd.)
Aqualon HS-10: Polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (Daiichi Kogyo Seiyaku Co., Ltd.)
Aqualon KH-10: polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Hitenol LA-10: polyoxyethylene alkyl ether sulfate (Daiichi Kogyo Seiyaku Co., Ltd.)
Hitenol N-08: polyoxyethylene nonylphenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd.)

-Nonionic surfactant-
Adekari Soap ER-20: Aqualon RN-20 manufactured by ADEKA Co., Ltd.: Polyoxyethylene nonylpropenylphenyl ether and polyoxyethylene nonylphenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Aqualon KN-20: Polyoxyethylene 1-(allyloxymethyl) alkyl ether (Daiichi Kogyo Seiyaku Co., Ltd.)

<monomer>
BA: butyl acrylate St: styrene DVB: divinylbenzene MMA: methyl methacrylate IPO: 2-isopropenyl-2-oxazoline 2EHA: 2-ethylhexyl acrylate

Claims (11)

A copolymer having a structural unit derived from an oxazoline group- or epoxy group-containing monomer, a structural unit derived from an anionic surfactant, and a structural unit derived from a nonionic surfactant, and having a glass transition temperature of less than 10°C . 2. The copolymer according to claim 1, wherein the content of the structural unit derived from the oxazoline group- or epoxy group-containing monomer is 10% by mass or more and 30% by mass or less with respect to 100 parts by mass of the copolymer. 3. The copolymer according to claim 1, wherein the mass ratio of structural units derived from the anionic surfactant and structural units derived from the nonionic surfactant is 5/95 to 40/60. 4. The copolymer according to any one of claims 1 to 3, which has a structural unit derived from an alkyl group-containing (meth)acrylic acid ester having 2 to 10 carbon atoms. 5. The copolymer according to any one of claims 1 to 4, which has a structural unit derived from an aromatic vinyl compound. An aqueous dispersion containing the copolymer according to any one of claims 1 to 5. A cross-linking agent comprising the copolymer according to any one of claims 1 to 5 or the aqueous dispersion according to claim 6. A coating composition comprising the copolymer according to any one of claims 1 to 5, the aqueous dispersion according to claim 6, or the cross-linking agent according to claim 7. A coating film obtained using the coating composition according to claim 8 . A copolymer having a glass transition temperature of less than 10°C, comprising a step of polymerizing an oxazoline group- or epoxy group-containing monomer, an anionic surfactant having a reactive group, and a nonionic surfactant having a reactive group. Production method. 11. The method for producing the copolymer according to claim 10, wherein the copolymer is polymerized in an aqueous solvent.