JP7125194B2 - Carboxyl group-containing copolymer - Google Patents

Description

The present invention relates to a carboxyl group-containing copolymer. More particularly, it relates to a carboxyl group-containing copolymer useful as a scale inhibitor and the like.

Polymers with carboxyl groups, typified by sodium poly(meth)acrylate, are used as pigment dispersants (dispersants for inorganic particles), water treatment agents (anti-adhesion agents for scale components), cleaning agents, etc. Widely used. These markets demand polymers with higher performance.

As a method to meet such demands, for example, Patent Document 1 discloses one or more selected from an aryl group having 6 to 20 carbon atoms, an alkyl group having 4 to 20 carbon atoms, and a hydroxyalkyl group having 1 to 8 carbon atoms. A structural unit (n) derived from one or more monomers (N) selected from amino group-containing monomers having an amino group substituted with a group, a structural unit derived from a carboxyl group-containing monomer (B) A water treatment agent is disclosed which contains an amino group-containing copolymer having (b) as an essential structural unit in a specific proportion. Further, Patent Documents 2 to 5 also disclose copolymers of amino group-containing monomers and unsaturated carboxylic acid-based monomers.

JP 2011-72851 A Japanese Patent Publication No. 2008-523162 Japanese translation of PCT publication No. 2015-522697 WO2010/024448 JP 2011-116813 A

As described above, various carboxyl group-containing copolymers have been disclosed. There is a demand for a polymer that exhibits both scavenging ability and carbon black dispersing ability.

The present invention has been made in view of the above-mentioned current situation, and an object thereof is to provide a carboxyl group-containing copolymer that is superior in calcium ion trapping ability and carbon black dispersion performance to conventional carboxyl group-containing copolymers. do.

The present inventors have made various studies on carboxyl group-containing copolymers, and found that structural units derived from unsaturated monocarboxylic acid-based monomers, structural units derived from unsaturated dicarboxylic acid-based monomers, and cationic monomers The inventors have found that a carboxyl group-containing copolymer having a structural unit derived from and are excellent in calcium ion trapping ability and carbon black dispersion performance, conceived that the above problems can be successfully solved, and arrived at the present invention. It is a thing.

That is, the present invention comprises a structural unit (a) derived from an unsaturated monocarboxylic acid monomer (A), a structural unit (b) derived from an unsaturated dicarboxylic acid monomer (B), and a cationic monomer ( It is a carboxyl group-containing copolymer having the structural unit (c) derived from C).
The present invention will be described in detail below.
A combination of two or more of the individual preferred embodiments of the invention described below is also a preferred embodiment of the invention.

The carboxyl group-containing copolymer of the present invention comprises a structural unit (a) derived from an unsaturated monocarboxylic acid monomer (A) and a structural unit (b) derived from an unsaturated dicarboxylic acid monomer (B). and a structural unit (c) derived from the cationic monomer (C).
Since the unsaturated monocarboxylic acid-based monomer (A) is excellent in polymerizability, it is possible to obtain a composition containing a carboxyl group-containing copolymer with a small amount of residual monomers. Also, a carboxyl group-containing copolymer having a sufficiently large weight average molecular weight can be obtained.
Since the unsaturated dicarboxylic acid-based monomer (B) has a high carboxylic acid density, the carboxyl group-containing copolymer of the present invention has a calcium ion trapping ability (hereinafter referred to as Ca trapping (also called Noh). The homopolymer of the unsaturated monocarboxylic acid-based monomer (A) has a low carboxylic acid density, so the Ca scavenging ability is not sufficient. is insufficient, and it is difficult to obtain a polymer having a sufficiently large weight-average molecular weight with only the unsaturated dicarboxylic acid-based monomer (B). By having both of b), the weight average molecular weight is sufficiently large and the Ca-trapping ability is excellent.

The unsaturated monocarboxylic acid-based monomer (A) may be any monomer having one ethylenically unsaturated hydrocarbon group and one group capable of forming a carbanion. For example, (meth) Acrylic acid, crotonic acid, tiglic acid, 3-methylcrotonic acid, 2-methyl-2-pentenoic acid, etc.; these monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts; unsaturated dicarboxylic acids described later Examples thereof include half esters of system monomer (B) and alcohols having 1 to 20 carbon atoms. (Meth)acrylic acid and salts thereof are preferred as the unsaturated monocarboxylic acid-based monomer (A). That is, a carboxyl group-containing copolymer in which the unsaturated monocarboxylic acid-based monomer (A) is (meth)acrylic acid (salt) is one of preferred embodiments of the present invention.
The alcohol having 1 to 20 carbon atoms is not particularly limited, and examples thereof include aliphatic alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol and octanol; alicyclic alcohols such as cyclohexanol. be done.

The unsaturated dicarboxylic acid-based monomer (B) may be a monomer having one ethylenically unsaturated hydrocarbon group and two groups capable of forming a carbanion in the molecule. acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof; and anhydrides thereof. Maleic acid and its salts, and maleic anhydride are preferred as the unsaturated dicarboxylic acid-based monomer (B). That is, a carboxyl group-containing copolymer in which the unsaturated monocarboxylic acid-based monomer (B) is maleic acid (salt) and/or maleic anhydride is one of preferred embodiments of the present invention.

The cationic monomer (C) is not particularly limited as long as it has at least one ethylenically unsaturated group and at least one cationic group. Here, the cationic group is a group having a cation or a group that generates a cation. and other amino groups.

Specific examples of the cationic monomer (C) include (i) N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl ( N, N-dialkylamino group-containing (meth) acrylates such as meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, monomers obtained by adding a quaternizing agent to the above monomers, or hydrochloric acid, acetic acid, etc. Acid neutralized product; (ii) N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl N,N-dialkylamino group-containing (meth)acrylamides such as (meth)acrylamide, monomers obtained by adding a quaternizing agent to the above monomers, or neutralized products thereof with acids such as hydrochloric acid and acetic acid; (iii) monomethyl monoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, 2-(tert-butylamino)ethyl (meth)acrylate, etc. Alkylamino group-containing (meth)acrylates and their neutralized products with acids such as hydrochloric acid and acetic acid; (iv) monomethylaminoethyl (meth)acrylamide, monoethylaminoethyl (meth)acrylamide, monomethylaminopropyl (meth)acrylamide , Monoalkylamino group-containing (meth)acrylamides such as monoethylaminopropyl (meth)acrylamide and neutralized products thereof with acids such as hydrochloric acid and acetic acid; (v) (meth)acrylic acid-2-aminoethyl and the like Esters of (meth)acrylic acid and alkanolamine, and their neutralized products with acids such as hydrochloric acid and acetic acid; (vi) Allylamine and neutralized products thereof with acids such as hydrochloric acid and acetic acid; (vii) C2-8 compounds such as 1-allyloxy-3-dibutylamino-2-ol An addition reaction product of an unsaturated monomer having a cyclic ether-containing group and an amine compound having 1 to 20 carbon atoms, a monomer obtained by adding a quaternizing agent thereto, or a neutralization product thereof with an acid such as hydrochloric acid or acetic acid etc.

Examples of the unsaturated monomer having a cyclic ether-containing group having 2 to 8 carbon atoms include allyl glycidyl ether.
The amine compound having 1 to 20 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 amine compound having 1 to 20 carbon atoms preferably has 1 to 16 carbon atoms, more preferably 2 to 10 carbon atoms, and still more preferably 3 to 8 carbon atoms. Examples of amine compounds having 1 to 20 carbon atoms include neutralized products of primary amines, secondary amines and tertiary amines with acids. Moreover, these amine compounds may have a functional group in addition to the amino group.
Although the functional group is not particularly limited, examples thereof include a hydroxyl group, a carboxyl group, a carbonyl group, an aldehyde group, an ester group, an ether group, a thiol group, a phosphoric acid group, a phosphorous acid group, and a silane group.
Examples of amine compounds having 1 to 20 carbon atoms include (di)alkylamines having 1 to 20 carbon atoms; (di)alkanolamines having 1 to 20 carbon atoms; alkylalkanolamines having 2 to 20 carbon atoms; Acid-neutralized tertiary amines such as trialkylamines having 20 carbon atoms, dialkylalkanolamines having 3 to 20 carbon atoms, and alkyldialkanolamines having 3 to 20 carbon atoms; (di)carboxylic acids having 1 to 20 carbon atoms; Amine etc. are mentioned.

(Di)alkylamines having 1 to 20 carbon atoms include methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, pentylamine, dipentylamine, hexylamine, dihexylamine and heptylamine. , diheptylamine, octylamine, dioctylamine, dodecylamine, didodecylamine and the like are preferred.
As the (di)alkanolamine having 1 to 20 carbon atoms, methanolamine, ethanolamine, propanolamine, butanolamine, dimethanolamine, diethanolamine, dipropanolamine, dibutanolamine, hexanolamine and the like are preferable.
As the alkylalkanolamine having 2 to 20 carbon atoms, methylethanolamine and the like are preferable.

Trialkylamines having 3 to 20 carbon atoms include trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine and the like. Among them, trialkylamines having 3 to 9 carbon atoms such as trimethylamine and triethylamine are preferred, and trimethylamine is more preferred.

Examples of (di)carboxylic acid amines having 1 to 20 carbon atoms include amino acids such as glycine, alanine, valine, leucine, isoleucine, phenylalanine, cysteine, glutamic acid, aspartic acid, and stereoisomers thereof; N-methylaminoacetic acid, N -N-alkylaminoacetic acids such as ethylaminoacetic acid; iminodicarboxylic acids such as iminodiacetic acid and iminodipropionic acid; and 2-aminoterephthalic acid. Among them, iminodicarboxylic acids having 2 to 8 carbon atoms such as iminodiacetic acid and iminodipropionic acid are preferred, and iminodiacetic acid is more preferred.

As the cationic group, the following formulas (1) to (3);

(In formulas (1) and (2), R ¹ and R ² are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, provided that R At least one of ¹ and R ² is a hydrocarbon group optionally having a functional group and having 1 to 20 carbon atoms.In the formula (3), R ³ to R ⁵ are the same or different and each of represents a hydrocarbon group having 1 to 20 carbon atoms which may have W ⁻ represents an anion). That is, the cationic monomer (C) preferably has a group represented by any one of the above formulas (1) to (3).
Examples of the functional group that the hydrocarbon group having 1 to 20 carbon atoms may have include the functional groups that the above-mentioned amine compounds may have.

Cationic monomer (C) preferably also has a hydrophobic group. When the cationic monomer (C) has a hydrophobic group, the carboxyl group-containing copolymer of the present invention exhibits a superior effect in terms of carbon black dispersibility.
That is, the structural unit (a) derived from the unsaturated monocarboxylic acid monomer (A) and the structural unit (b) derived from the unsaturated dicarboxylic acid monomer (B) and the cationic monomer (C) derived A carboxyl group-containing copolymer in which the cationic monomer (C) has a hydrophobic group is also one of the preferred embodiments of the present invention.
The cationic monomer (C) may have a cationic group and a hydrophobic group separately, but preferably has a cationic group with a hydrophobic group.

In the groups represented by the above formulas (1) to (3), if at least one hydrocarbon group having 1 to 20 carbon atoms does not have a functional group or has a hydrophobic functional group, It becomes a cationic group having a hydrophobic group.
The hydrocarbon group having 1 to 20 carbon atoms preferably has no functional group or has a hydrophobic functional group.
Hydrophobic functional groups include, for example, ester groups and the like.
The hydrocarbon group having 1 to 20 carbon atoms preferably has no functional group.

The hydrocarbon group may have a chain structure or a ring structure, but preferably has a chain structure. When the hydrocarbon group has a chain structure, it may be linear or branched.
The hydrocarbon group is preferably an alkyl group, an alkenyl group, or an aryl group, more preferably an alkyl group or an alkenyl group, and still more preferably an alkyl group.
The number of carbon atoms in the hydrocarbon group is preferably 1-20, more preferably 2-18, particularly preferably 3-10, and most preferably 3-8.
The above alkyl group is preferably an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group, more preferably an alkyl group having 2 to 8 carbon atoms, and further A propyl group or a butyl group is preferred.

W ^- in the above formulas (2) and (3) is not particularly limited, but for example, halide ions such as chloride ion, bromide ion and iodine ion; alkyl sulfate ions such as methyl sulfate ion; organic Acid ions and the like can be mentioned.
W 2 ⁻ in the above formula (2) is preferably an ion of an organic acid.
W 2 ⁻ in the above formula (3) is preferably a halide ion or an alkyl sulfate ion.

Both R ¹ and R ² in the above formulas (1) and (2) are preferably hydrocarbon groups having 1 to 20 carbon atoms.
Examples of the cationic group include secondary and tertiary amino groups, neutralized products of secondary and tertiary amino groups with acids, and quaternary ammonium bases, tertiary amino groups and acids of tertiary amino groups. or a quaternary ammonium base is preferred.
If the cationic group is a tertiary amino group, a neutralized product of a tertiary amino group with an acid, or a quaternary ammonium base, the cationic monomer (C) has two hydrophobic groups per molecule. If it has more than this, the hydrophobicity of the copolymer will be further improved, and the carbon black dispersing performance will be more excellent.
A tertiary amino group or a neutralized product of a tertiary amino group with an acid is preferably a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, or a neutralized product thereof with an acid such as hydrochloric acid or acetic acid. More preferably, it is a tertiary amino group, and if the cationic monomer does not have an electric charge, the hydrophobicity of the cationic monomer will be further improved, and the carbon black dispersibility will be more excellent.

As the cationic monomer (C), the following formula (4);

(in formula (4), R ^{6 ,} R ⁷ and R ⁸ are the same or different and represent a hydrogen atom or a methyl group; p and t are the same or different and represent a number from 0 to 5; q, r and s are the same or different and are 0 or 1. A represents a cationic group.

In the above formula (4), R ⁶ to R ⁸ are the same or different and represent a hydrogen atom or a methyl group, and at least one of R ⁶ and R ⁷ is preferably a hydrogen atom.
In the above formula (4), p, t are the same or different and represent a number of 0 to 5, q, r and s are the same or different and represent a number of 0 or 1, but p, q, A preferred combination of r, s, t is (p, q, r, s, t) = (1, 0, 1, 0, 0), (2, 0, 1, 0, 0), (0, 1 , 1,0,3), (0,1,1,0,2), (1,0,1,1,1).
In the above formula (4), A represents a cationic group, preferably a group represented by any one of the above formulas (1) to (3).

More preferably, the cationic monomer (C) is an addition reaction product of an unsaturated monomer having a cyclic ether-containing group having 2 to 8 carbon atoms and a (di)alkylamine having 1 to 20 carbon atoms, More preferred is an addition reaction product of an unsaturated monomer having a cyclic ether-containing group having 2 to 8 carbon atoms and a dialkylamine having 2 to 18 carbon atoms, and particularly preferred is a carbon monomer such as allyl glycidyl ether and dibutylamine. It is an addition reaction product with a dialkylamine of numbers 3-8.

The carboxyl group-containing copolymer of the present invention preferably further has a structural unit (d) derived from the sulfonic acid group-containing monomer (D). That is, the structural unit (a) derived from the unsaturated monocarboxylic acid monomer (A), the structural unit (b) derived from the unsaturated dicarboxylic acid monomer (B), and the cationic monomer (C ) derived structural unit (c) and a carboxyl group-containing copolymer having a structural unit (d) derived from the sulfonic acid group-containing monomer (D) is also one of the preferred embodiments of the present invention . By having the structural unit (d), the copolymer of the present invention has a highly hydrophilic sulfonic acid group, which causes gelation of the copolymer and aggregation of calcium ions and the copolymer. can be suppressed. Under high hardness conditions, the technical significance of having the structural unit (d) is exhibited more effectively.
The sulfonic acid group-containing monomer (D) is not particularly limited as long as it has a sulfonic acid (salt) group and an ethylenically unsaturated hydrocarbon group. For example, 3-(meth)allyloxy-2 -hydroxypropanesulfonic acid, 2-(meth)allyloxyethylenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-styrenesulfonic acid, α-methyl-p-styrenesulfonic acid, vinylsulfonic acid, vinylsulfamine acids, (meth)allylsulfonic acid, isoprenesulfonic acid, 4-(allyloxy)benzenesulfonic acid, 1-methyl-2-propene-1-sulfonic acid, 1,1-dimethyl-2-propene-1-sulfonic acid, 3-butene-1-sulfonic acid, 1-butene-3-sulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamide- Unsaturated sulfonic acids such as 2-phenylpropanesulfonic acid and 2-((meth)acryloyloxy)ethanesulfonic acid, salts thereof, and the like. As the sulfonic acid group-containing monomer (D), the following formula (5);

(In formula (5), R ⁹ represents a hydrogen atom or a methyl group. R ¹⁰ represents a CH ₂ group, a CH ₂ CH ₂ group, or a direct bond. X, Y represent a hydroxyl group or —SO ₃ Z. and Z represents a hydrogen atom, a metal atom, an ammonium group or an organic amine group, provided that at least one of X and Y represents —SO ₃ Z.). That is, the carboxyl group-containing copolymer preferably has a structural unit derived from the monomer represented by the formula (5).
R ⁹ above is preferably a hydrogen atom.
R ¹⁰ above is preferably a CH ₂ group. If R ¹⁰ is a CH ₂ group, the effects of the present invention can be exhibited more effectively.
One of X and Y is preferably a hydroxyl group, and the other is preferably a sulfonic acid (salt) group. More preferably X is a hydroxyl group and Y is a sulfonic acid (salt) group.

More preferred sulfonic acid (salt) group-containing monomers are 3-(meth)allyloxy-2-hydroxy-1-propanesulfonic acid and salts thereof.

The copolymer of the present invention comprises the unsaturated monocarboxylic acid-based monomer (A), the unsaturated dicarboxylic acid-based monomer (B), the cationic monomer (C), and the sulfonic acid group-containing monomer. It may have structural units (e) derived from monomers (E) other than (D).
The above-mentioned other monomer (E) is not particularly limited, but a monomer obtained by adding an alkylene oxide to an unsaturated alcohol such as (meth)allyl alcohol or isoprenol, a (meth)acrylic acid ester of an alkoxyalkylene glycol, and the like. Polyalkylene glycol chain-containing monomers; vinylpyridine, vinyl aromatic monomers having heterocyclic aromatic hydrocarbon groups such as vinylimidazole; N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinyl monomers such as N-vinyl-N-methylformamide, N-vinyl-N-methylacetamide and N-vinyloxazolidone; amides such as (meth)acrylamide, N,N-dimethylacrylamide and N-isopropylacrylamide (Meth) allyl alcohol, hydroxyl group-containing monomers such as isoprenol; butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, etc. Polymer; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate ( hydroxyalkyl meth)acrylate monomers; vinylaryl monomers such as styrene, indene and vinylaniline; isobutylene, vinyl acetate and the like.

The proportion of the structural unit (a) in the copolymer of the present invention is not particularly limited, but it is preferably 10 to 70 mol % with respect to 100 mol % of all structural units. If the proportion of the structural unit (a) is within the above preferred proportion, the weight average molecular weight can be set within a more preferred range. The ratio of the structural unit (a) is more preferably 15 to 60 mol%, still more preferably 20 to 50 mol%, and particularly preferably 25 to 45 mol%.

The ratio of the structural unit (b) in the copolymer of the present invention is not particularly limited, but it is preferably 10 to 70 mol% with respect to 100 mol% of all structural units. If the proportion of the structural unit (b) is within the above preferable proportion, the Ca-trapping ability will be more excellent. The ratio of the structural unit (b) is more preferably 15 to 60 mol%, still more preferably 20 to 50 mol%, and particularly preferably 25 to 45 mol%.

The proportion of the structural unit (c) in the copolymer of the present invention is not particularly limited, but it is preferably 1 to 20 mol % with respect to 100 mol % of all structural units. More preferably 2 to 18 mol %, still more preferably 3 to 15 mol %, particularly preferably 4 to 10 mol %.

The proportion of the structural unit (d) in the copolymer of the present invention is not particularly limited, but it is preferably 1 to 20 mol % with respect to 100 mol % of all structural units. If the proportion of the structural unit (d) is within the above preferable proportion, gelation of the copolymer and aggregation of calcium ions and the copolymer can be more sufficiently suppressed. The ratio of the structural unit (d) is more preferably 2 to 18 mol%, still more preferably 3 to 15 mol%, and particularly preferably 4 to 10 mol%.

The proportion of the structural unit (e) in the copolymer of the present invention is not particularly limited, but it is preferably 0 to 20 mol % with respect to 100 mol % of all structural units. It is more preferably 0 to 15 mol %, still more preferably 0 to 10 mol %, particularly preferably 0 to 5 mol %, most preferably 0 mol %.

The carboxyl group-containing copolymer of the present invention preferably has a weight average molecular weight of 2,000 to 500,000. It is more preferably 3,000 to 100,000, still more preferably 4,000 to 50,000, and particularly preferably 5,000 to 20,000. If the weight-average molecular weight is within the above preferable range, the calcium ion trapping ability will be excellent.
The weight average molecular weight of the copolymer can be measured by the method described in Examples.

In the carboxyl group-containing copolymer of the present invention, 20 to 95 mol% of the carboxyl groups are in the salt form (neutralization rate is 20 to 95 mol) with respect to 100 mol% of all carboxyl groups in the carboxyl group-containing copolymer. %). It is more preferably 30 to 90 mol %, still more preferably 40 to 80 mol %.
Examples of the salt include metal salts, ammonium salts, organic amine salts, and the like. As the metal salt, alkali metal salts such as sodium and potassium are preferred, and sodium salts are more preferred.

<Method for Producing Carboxyl Group-Containing Copolymer of the Present Invention>
The method for producing the carboxyl group-containing copolymer of the present invention is not particularly limited, but it can be produced by polymerizing monomer components, and specific examples and preferred examples of the monomer components are as described above. . Further, the preferred content ratios of the monomers (A), (B), (C), (D) and (E) in the monomer component are the structural units (a) and (b) in the copolymer described above. , (c), (d) and (e).

The polymerization method for obtaining the carboxyl group-containing copolymer of the present invention is not particularly limited, and a commonly used polymerization method or a modified method thereof can be employed. Examples of the polymerization method include radical polymerization methods, and specific examples include oil-in-water emulsion polymerization method, water-in-oil emulsion polymerization method, suspension polymerization method, dispersion polymerization method, precipitation polymerization method, and solution polymerization method. , an aqueous solution polymerization method, a bulk polymerization method, and the like can be employed. Among the polymerization methods exemplified above, it is preferable to employ the solution polymerization method in terms of high safety and reduction in production cost (polymerization cost).

The reaction form of the solution polymerization method is not particularly limited, and the reaction can be carried out in a commonly used form. Examples include a mode in which an agent (hereinafter also referred to as an "initiator") is added dropwise to carry out the reaction. In such a reaction mode, the concentration of each solution to be added dropwise is not particularly limited, and any appropriate concentration can be adopted.
Examples of the form in which the monomer and the initiator are added dropwise to the solvent previously charged in the reaction system to carry out the reaction include, for example, the monomer component, the initiator component, and, if necessary, other may be dissolved in a solvent, or may be appropriately added (dropped) into the reaction system during the polymerization without dissolving in the solvent. Moreover, in this reaction mode, part or all of the total amount of the monomer components used can be previously added (initial charging) to the reaction system before the initiation of polymerization. Preferably, the unsaturated dicarboxylic acid monomer (B), the cationic monomer (C), and optionally a part of the amount of the sulfonic acid group-containing monomer (D) are initially charged. .

In the solution polymerization method, the monomer components are polymerized in a solvent.
As the solvent, it is possible to use only an organic solvent, but it is preferable that water is included. It is more preferable to use 50% by mass or more of water with respect to 100% by mass of the total amount of solvent used. Examples of the organic solvent that can be used alone or together with water include lower alcohols such as ethanol and isopropanol; amides such as N,N-dimethylformamide; ethers such as diethyl ether and dioxane; glycol, glycerin, and polyethylene glycol. Aqueous organic solvents such as the following are suitable.
Only one kind of the solvent may be used, or two or more kinds thereof may be used in combination.
The amount of the solvent used is preferably 40 to 300 parts by mass with respect to 100 parts by mass of the total amount of all monomers.

When the initial charging is performed in the aqueous solution polymerization method, the pH in the reaction system before the initiation of polymerization is preferably 1-7. pH 2-6.8 is more preferred, pH 3-6.6 is more preferred, pH 4-6.4 is particularly preferred, and pH 5-6 is most preferred. If the pH in the reaction system before the initiation of polymerization is 7 or less, the water solubility of the cationic monomer (C) is improved, and the efficiency of the polymerization reaction is improved. Therefore, the proportion of the structural unit (c) in the carboxyl group-containing copolymer of the present invention can be increased.
The method for adjusting the pH is not particularly limited, and a commonly used acid or base can be used. For example, when using an acid-type unsaturated monocarboxylic acid-based monomer (A) and/or an unsaturated dicarboxylic acid-based monomer (B) as a monomer component, it is adjusted with a base and neutralized. When using the unsaturated monocarboxylic acid-based monomer (A) and/or the unsaturated dicarboxylic acid-based monomer (B) of the type, the pH can be adjusted with an acid.
The above-mentioned base is not particularly limited, but examples thereof include hydroxides of alkali metals such as sodium hydroxide.

<Polymerization initiator>
As the polymerization initiator used in the above production method, a commonly used one can be used. Specifically, hydrogen peroxide; persulfates such as sodium persulfate and ammonium persulfate; 2,2′-azobis(2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanovaleric acid, azobis Preferable examples include azo compounds such as isobutyronitrile; organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, and di-t-butyl peroxide. Among these polymerization initiators, hydrogen peroxide, persulfate and 2,2'-azobis(2-amidinopropane) hydrochloride are preferred, and persulfate and 2,2'-azobis(2-amidinopropane) hydrochloride are preferred. Salt is more preferred. These polymerization initiators may be used alone or in combination of two or more.
The total amount of the polymerization initiator used is not particularly limited as long as it is an amount capable of initiating copolymerization of the monomers, but it is preferably 15 g or less per 1 mol of the total amount of all monomer components. More preferably 1 to 12 g.

<Chain transfer agent>
In the above production method, it is preferable to use a chain transfer agent as a molecular weight modifier for the polymer. Examples of the chain transfer agent include compounds capable of generating bisulfites and/or bisulfites such as pyrosulfite (salts), dithionous acid (salts), sulfites (salts), mercaptoethanol, thioglycolic acid, 3- Thiol-based chain transfer agents such as mercaptopropionic acid; halides such as carbon tetrachloride, methylene chloride and bromoform; secondary alcohols such as isopropanol and glycerin; phosphorous acid, hypophosphorous acid and its salts (hypophosphorous acid sodium, potassium hypophosphite, etc.) and salts thereof; Hydrogen sulfites and/or compounds capable of generating hydrogen sulfites are preferred. As the above salt, salts with metal atoms, ammonium or organic amines are suitable.
The amount of the chain transfer agent to be added is not limited as long as the monomer components are polymerized satisfactorily, but it is preferably 1 to 20 g per 1 mol of the total amount of all the monomer components.

<Decomposition catalyst, reducing compound>
In the method for producing a hydrophobic group-containing copolymer of the present invention, in addition to a polymerization initiator and the like, a decomposition catalyst for the polymerization initiator and a reducing compound (also referred to as a reaction accelerator) are used (added to the polymerization system). good too.
A heavy metal ion (or a heavy metal salt) is exemplified as a compound that acts as a decomposition catalyst or a reducing compound for the polymerization initiator. That is, in the method for producing a hydrophobic group-containing copolymer of the present invention, heavy metal ions (or heavy metal salts) may be used (added to the polymerization system) in addition to the polymerization initiator and the like. In this specification, heavy metal ions refer to metals having a specific gravity of 4 g/cm ³ or more.

Specific examples of the heavy metal ions include those described in WO 2010/024448. One or more of these heavy metals can be used. Among these, iron is more preferable.
The ionic valence of the heavy metal ion is not particularly limited. For example, when iron is used as the heavy metal, the iron ion in the initiator may be either Fe ²⁺ or Fe ³⁺ , or a combination thereof. may have been
When iron is used as the heavy metal ion, Mohr's salt (Fe(NH ₄ ) ₂ (SO ₄ ) _{2.6H 2 O} ), ferrous sulfate heptahydrate, ferrous chloride, ferric chloride, etc. It is preferable to use a heavy metal salt or the like.

The content of the heavy metal ions is preferably 0.1 to 10 ppm with respect to the total mass of the polymerization reaction solution at the completion of the polymerization reaction (after neutralization when the neutralization step is performed after the polymerization reaction). is preferred. When the content of heavy metal ions is 0.1 ppm or more, the effects of the heavy metal ions can be exhibited more sufficiently, and when the content is 10 ppm or less, the resulting polymer can have an excellent color tone.

<Polymerization conditions>
The polymerization reaction in the above production method is preferably carried out under pH 1-7 conditions. pH 2-6.8 is more preferred, pH 3-6.6 is more preferred, pH 4-6.4 is particularly preferred, and pH 5-6 is most preferred.
By carrying out the polymerization reaction at pH 7 or less, the water solubility of the cationic group monomer (C) is improved, and the reaction efficiency is improved. Therefore, the proportion of the structural unit (c) in the carboxyl group-containing copolymer of the present invention can be increased. On the other hand, if the polymerization reaction is performed at a pH of 1 or higher, corrosion of the equipment can be suppressed when the equipment such as a vessel and stirring blades for the polymerization reaction are made of metal such as SUS.
The method for adjusting the pH is the same as the method for adjusting the pH in the reaction system before the initiation of polymerization.
As described above, in the method for producing a carboxyl group-containing copolymer of the present invention, the pH in the reaction system before the initiation of polymerization is preferably 1 to 7, and the pH in the reaction system before the initiation of polymerization and in the polymerization reaction A pH of 1-7 is one of the preferred embodiments of the present invention.
In the above production method, when maleic anhydride is used as the unsaturated dicarboxylic acid-based monomer (B), it is preferable to neutralize the maleic anhydride before use in order to increase the solubility of the maleic anhydride. In particular, the technical significance of adjusting the pH in the reaction system before the initiation of polymerization and the pH in the polymerization reaction to 1 to 7 is more effectively exhibited.

In the above production method, the polymerization temperature is appropriately determined depending on the polymerization method, solvent, polymerization initiator, etc. used, but is preferably 70 to 120°C. It is more preferably 75 to 110°C, still more preferably 80 to 105°C, and particularly preferably 85 to 100°C. By setting the polymerization temperature to 70° C. or higher, the solubility of the monomer component is further improved, and the reactivity is further improved.
The polymerization temperature does not need to be kept substantially constant during the polymerization reaction, and the temperature is changed (increased or decreased) over time during the polymerization reaction depending on the dropping method of the monomer component, initiator, etc. may In addition, the polymerization temperature means the temperature of the reaction solution in the polymerization reaction.

In the above production method, an aging step may be provided for the purpose of increasing the polymerization rate of the monomers after the addition of all the raw materials used. Aging time is preferably 1 to 120 minutes.
In the production method described above, the polymerization time is not particularly limited, but is preferably 30 to 420 minutes. In the present invention, the term "polymerization time" refers to the time during which the monomers are added, that is, the time from the start to the end of the addition of the monomers, unless otherwise specified.

In the above production method, a neutralization step may be performed after the polymerization reaction or after the aging step.
Preferably, an alkali component is used in the neutralization step.
As the alkali component, one commonly used can be used, preferably an alkali metal hydroxide, more preferably sodium hydroxide.
The amount of the alkaline component used in the neutralization step can be set so that the neutralization rate of the carboxyl group-containing copolymer is within the above range.

<Application of Carboxyl Group-Containing Copolymer>
The carboxyl group-containing copolymer of the present invention can be used as a coagulant, a flocculant, a printing ink, an adhesive, a soil conditioning (improving) agent, a flame retardant, a skin care agent, a hair care agent, a shampoo, a hair spray, an additive for cosmetics, Anion exchange resins, dye mordants and auxiliaries for fibers and photographic films, pigment spreading agents in papermaking, paper strength agents, preservatives, fabric softeners and paper softeners, lubricating oil additives, water treatment agents, fiber treatment agents, dispersants, scale inhibitors (scale inhibitors), metal ion sealants, thickeners, various binders, emulsifiers, detergents, detergents, and the like.
The carboxyl group-containing copolymer of the present invention can exhibit high performance in aqueous applications, and has high resistance to hard water, high clay dispersibility, and high interaction with surfactants. When used in agents, detergents, etc., it can exhibit better performance.

<Scale inhibitor>
The carboxyl group-containing copolymer of the present invention can be used as a scale inhibitor.
That is, the present invention is also a scale inhibitor containing the carboxyl group-containing copolymer of the present invention.
If necessary, the above-mentioned scale inhibitor may contain other compounding agents such as polymerized phosphates, phosphonates, anticorrosives, slime control agents, chelating agents, and the like.
The above scale inhibitor is useful for preventing scale in cooling water circulation systems, boiler water circulation systems, seawater desalination plants, pulp digesters, black liquor concentration plants and the like. Moreover, any suitable water-soluble polymer may be included as long as it does not affect the performance and effect.

<Cleaning agents/detergents>
The carboxyl group-containing copolymer of the present invention can be used in detergent builders or detergent compositions (detergent compositions). That is, the present invention is also a detergent builder or detergent composition containing the carboxyl group-containing copolymer.
The above detergent builder or detergent composition can be used as a detergent for various purposes such as clothing, kitchen (dishware), home, hair, body, toothpaste, and automobile. It is preferably used for clothes and kitchens, and is preferably used for laundry detergents, kitchen detergents and the like. Examples of kitchen detergents include hand-washing dishwashing detergents and automatic dishwashing detergents.

The content of the carboxyl group-containing copolymer in the detergent composition is not particularly limited. , preferably 0.1 to 15% by mass, more preferably 0.3 to 10% by mass, and still more preferably 0.5 to 5% by mass.

Detergent compositions used in detergent applications typically contain surfactants and additives that are used in detergents. Specific forms of these surfactants and additives are not particularly limited, and conventionally known findings in the field of detergents can be appropriately referred to. Moreover, the detergent composition may be a powder detergent composition or a liquid detergent composition.

Surfactants are one or more selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants. When two or more types are used in combination, the total amount of the anionic surfactant and the nonionic surfactant is preferably 50% by mass or more, more preferably 60% by mass, based on the total amount of the surfactants. or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

Anionic surfactants include alkylbenzene sulfonates, alkyl ether sulfates, alkenyl ether sulfates, alkyl sulfates, alkenyl sulfates, α-olefin sulfonates, α-sulfo fatty acid or ester salts, and alkanesulfonates. , saturated fatty acid salts, unsaturated fatty acid salts, alkyl ether carboxylates, alkenyl ether carboxylates, amino acid type surfactants, N-acyl amino acid type surfactants, alkyl phosphate esters or salts thereof, alkenyl phosphate esters or Salts thereof and the like are preferred. The alkyl group and alkenyl group in these anionic surfactants may be branched to an alkyl group such as a methyl group.

Nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, polyoxyethylene alkylphenyl ethers, higher fatty acid alkanolamides or their alkylene oxide adducts, sucrose fatty acid esters, alkyl glycooxides, fatty acid glycerol mono Esters, alkylamine oxides, and the like are preferred. The alkyl group and alkenyl group in these nonionic surfactants may be branched to an alkyl group such as a methyl group.

A quaternary ammonium salt or the like is suitable as the cationic surfactant. As the amphoteric surfactant, a carboxyl type amphoteric surfactant, a sulfobetaine type amphoteric surfactant and the like are suitable. The alkyl group and alkenyl group in these cationic surfactants and amphoteric surfactants may have branched alkyl groups such as methyl groups.

The blending ratio of the surfactant is usually 10 to 60% by mass, preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and particularly preferably 10% to 60% by mass, based on the total amount of the detergent composition. is 25 to 40% by mass. If the blending ratio of the surfactant is too low, there is a risk that sufficient detergency will not be exhibited, and if the blending ratio of the surfactant is too high, there is a risk that economic efficiency will decrease.

Additives include alkali builders, chelate builders, anti-redeposition agents to prevent redeposition of contaminants such as sodium carboxymethylcellulose, stain inhibitors such as benzotriazole and ethylene-thiourea, soil release agents, and color transfer. Inhibitors, softeners, alkaline substances for pH adjustment, fragrances, solubilizers, fluorescent agents, coloring agents, foaming agents, foam stabilizers, polish agents, disinfectants, bleaching agents, bleaching aids, enzymes, dyes , solvents and the like are suitable. Moreover, it is preferable to mix|blend a zeolite in the case of a powder detergent composition.

The detergent composition may contain other detergent builders in addition to the carboxyl group-containing copolymer of the present invention. Examples of other detergent builders include, but are not limited to, alkali builders such as carbonates, hydrogen carbonates and silicates, tripolyphosphates, pyrophosphates, Glauber's salt, nitrilotriacetate, ethylenediaminetetraacetate, citric acid. acid salts, copolymer salts of (meth)acrylic acid, acrylic acid-maleic acid copolymers, fumarate salts, chelate builders such as zeolite, and carboxyl derivatives of polysaccharides such as carboxymethylcellulose. Counter salts used for the above builders include alkali metals such as sodium and potassium, ammonium, amines and the like.

The total blending ratio of the above additives and other detergent builders is usually preferably 0.1 to 50% by mass with respect to 100% by mass of the detergent composition. More preferably 0.2 to 40% by mass, still more preferably 0.3 to 35% by mass, particularly preferably 0.4 to 30% by mass, most preferably 0.5 to 20% by mass. be. If the mixing ratio of additives/other detergent builders is less than 0.1% by mass, there is a risk that sufficient detergent performance will not be exhibited, and if it exceeds 50% by mass, there is a risk of lowering economic efficiency.

When the detergent composition is a liquid detergent composition, the amount of water contained in the liquid detergent composition is usually preferably 0.1 to 75% by mass, more preferably 0.1 to 75% by mass relative to the total amount of the liquid detergent composition. is 0.2 to 70% by mass, more preferably 0.5 to 65% by mass, even more preferably 0.7 to 60% by mass, particularly preferably 1 to 55% by mass, and most It is preferably 1.5 to 50% by mass.

Protease, lipase, cellulase and the like are suitable as enzymes that can be blended in the detergent composition. Among them, protease, alkaline lipase and alkaline cellulase, which are highly active in an alkaline washing solution, are preferred.

The amount of the enzyme added is preferably 5% by mass or less with respect to 100% by mass of the detergent composition. If it exceeds 5% by mass, no improvement in detergency can be seen, and there is a risk of a decrease in economic efficiency.

The above detergent composition has excellent cleaning effect with little salt deposition even when used in regions with hard water (for example, 100 mg/L or more) with high concentrations of calcium ions and magnesium ions. This effect is particularly pronounced when the detergent composition contains an anionic surfactant such as LAS.

The carboxyl group-containing copolymer of the present invention has the structure described above and is excellent in calcium ion trapping ability and carbon black dispersing ability, so that it can be suitably used for scale inhibitors, cleaning agents, detergents and the like.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited only to these examples. Unless otherwise specified, "part" means "part by weight" and "%" means "% by mass".
(1) weight average molecular weight (Mw)
(2) Ca trapping ability, (3) carbon black dispersing ability, (4) redeposition preventing ability, and (5) beef tallow dispersing ability were measured or quantified by the following methods.

(1) Weight average molecular weight (Mw) measurement device: Tosoh high-speed GPC device (HLC-8320GPC)
Detector: RI
Column: Showa Denko SHODEX Asahipak GF-310-HQ, GF-710-HQ, GF-1G 7B
Column temperature: 40°C
Flow rate: 0.5ml/min
Calibration curve: POLYACRYLIC ACID STANDARD manufactured by Sowa Science Co., Ltd.
Eluent: 0.1N sodium acetate/acetonitrile = 3/1 (mass ratio)

(2) 50 g of aqueous solutions of 0.01 mol/l, 0.001 mol/l, and 0.0001 mol/l were prepared using calcium chloride dihydrate as the calcium ion standard solution for the calibration curve for measuring the Ca trapping ability. , Adjust the pH to a range of 9 to 11 with a 48% NaOH aqueous solution, add 1 ml of a 4 mol / l potassium chloride aqueous solution (hereinafter abbreviated as a 4M-KCl aqueous solution), further stir thoroughly using a magnetic stirrer and weigh. A wire sample solution was prepared. As a calcium ion standard solution for testing, similarly using calcium chloride dihydrate, a required amount (50 g per sample) of a 0.001 mol/l aqueous solution was prepared. Next, 10 mg of a test sample (polymer) was weighed in terms of solid content in a 100 cc beaker, 50 g of the calcium ion standard solution for testing was added, and the mixture was sufficiently stirred using a magnetic stirrer. Furthermore, similarly to the calibration curve sample, the pH was adjusted to within the range of 9 to 11 with a 48% NaOH aqueous solution, and 1 ml of a 4M-KCl aqueous solution was added to prepare a test sample solution. Using the titrator COMTITE-550 manufactured by Hiranuma Sangyo Co., Ltd., the calibration curve sample liquid and the test sample liquid thus prepared were measured with a calcium ion electrode 93-20 and a reference electrode 90-01 manufactured by Orion. did. Calculate the amount of calcium ions captured by the sample (polymer) from the calibration curve and the measured values of the test sample liquid, and calculate the amount captured per 1 g of polymer solid content in mg of calcium carbonate conversion (mgCaCO ₃ /g), and this value was taken as the calcium ion trapping capacity value.

(3) Measurement of carbon black dispersibility A buffer solution and a 0.1% polymer aqueous solution were prepared. The above buffer solution was prepared by adding pure water to 6.76 g of glycine, 5.26 g of sodium chloride and 0.50 g of 48% sodium hydroxide to make the total amount 60.0 g, followed by 0.123 g of calcium chloride dihydrate and chloride. 0.056 g of magnesium hexahydrate was added, and pure water was added to make 1000.0 g. The above 0.1% polymer aqueous solution was prepared by diluting the polymer obtained in Examples 1 to 8 or Comparative Examples 1 to 7 below with an appropriate amount of water to a solid content concentration of 0.1% by mass. .
Next, each of the above solutions and carbon black powder were placed in a 30 ml test tube in a predetermined order and in a predetermined amount. The predetermined sequence and predetermined amounts are as follows: firstly charge 0.03 g of carbon black powder, secondly charge 27.0 g of buffer solution, and finally charge 3 0.1% aqueous polymer solutions. 0 g was charged.
After charging each solution and carbon black powder in this order, the test tube was capped and slowly inverted up and down 60 times to stir the contents. Then, it is left to stand at room temperature for 20 hours, and immediately after 20 hours, the supernatant liquid is placed in a 1 cm quartz cell, and the absorbance at a UV wavelength of 380 nm is measured with a spectrophotometer (measurement device: UV-1800 manufactured by Shimadzu Corporation). This value was taken as the carbon black dispersibility. A higher absorbance indicates better dispersion of the carbon black powder.

(4) Measurement of anti-soil redeposition ability The whiteness of white cotton cloth and cotton/polyester mixed cloth used as samples was measured in advance by reflectance. A colorimetric color difference meter ND-1001DP type (manufactured by Nippon Denshoku Industries Co., Ltd.) or the like can be used for reflectance measurement. Hard water was prepared by adding pure water to 1.47 g of calcium chloride dihydrate to make 10 kg. Pure water was added to 4.0 g of sodium linear alkylbenzene sulfonate (LAS) to make a total of 100 g, and a 4% surfactant aqueous solution was prepared. Set the turgot meter at 25 ° C., put 1000 mL of hard water and 5.0 g of aqueous polymer solution (concentration 1.0%) in a pot, stir for 1 minute, then add 5.0 g of 4% surfactant aqueous solution, JIS class 11 clay 0.5 g was placed in the pot and stirred at 100 rpm for 1 minute. 5.0 g of white cloth was placed in the pot and stirred at 100 rpm for 10 minutes. Drain the white cloth by hand, put 1 L of hard water and the white cloth in a pot, and stir at 100 rpm for 2 minutes. After drying the white cloth again by hand, the white cloth was covered with a pressing cloth and dried while smoothing wrinkles with an iron. . From this measurement result, the redeposition prevention ability is obtained by the following formula.
Redeposition prevention ability (%) = (whiteness after washing) / (whiteness of original white cloth) x 100

(5) Measurement of beef tallow dispersibility First, pure water was added to 0.123 g of calcium chloride dihydrate and 0.056 g of magnesium chloride hexahydrate to make 1000.0 g to prepare hard water. Pure water was added to 83.3 g of 25% sodium polyoxyethylene lauryl ether sulfate and 11.9 g of 35% lauryl dimethylamine oxide to make 100.0 g, followed by stirring. Sodium polyoxyethylene lauryl ether sulfate: lauryl dimethylamine oxide A 25% surfactant aqueous solution was prepared such that the ratio was 5:1. Then, 2 mg of the aqueous polymer solution in terms of solid content, and 0.20 g of the 25% surfactant aqueous solution prepared above were added with hard water to make 20 g of a cleaning composition.
0.10 g of beef tallow was placed in a 50 ml glass screw tube, 20 g of the cleaning composition prepared above was added, stirred, and allowed to stand at 25° C. for 6 hours. After 6 hours, the supernatant was immediately placed in a 1 cm quartz cell, and the absorbance at UV wavelength 380 nm was measured with a spectrophotometer, and this value was taken as beef tallow dispersibility. Higher absorbance indicates better dispersion of beef tallow.

<Example 1>
(Synthesis of monomer)
A method for synthesizing a dibutylamine derivative monomer (AGE-DBA) of allyl glycidyl ether (AGE) is described below.
319.9 g of pure water and 387.0 g of dibutylamine were charged into a 2000 mL capacity four-necked glass flask equipped with a reflux condenser and a stirrer (paddle blades), and the temperature was raised to 60° C. while stirring. Next, 359.5 g of AGE was added over 60 minutes and then reacted for 5 hours. After washing the obtained monomer with pure water and saturated saline, the aqueous layer was removed using a separatory funnel. Moisture in the organic layer was sufficiently removed using sodium sulfate, and sodium sulfate was removed by filtration to obtain 100% AGE-DBA.

(Synthesis of polymer)
27.7 g of pure water and 29.4 g (0.30 mol) of maleic anhydride were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 14.0 g (0.17 mol) of 48% sodium hydroxide (hereinafter abbreviated as 48% NaOH) and 6.6 mg of Mohr's salt were added. Then, while stirring, 75.7 g (0.84 mol) of an 80% acrylic acid aqueous solution (hereinafter abbreviated as 80% AA), an addition reaction product of allyl glycidyl ether (AGE) and dibutylamine (hereinafter, AGE -DBA) 17.1 g (0.06 mol), 15% sodium persulfate aqueous solution (hereinafter abbreviated as 15% NaPS) 48.0 g (relative to the monomer input amount (here, the monomer input amount is 6.0 g / mol), 32.5% sodium hydrogen sulfite aqueous solution (hereinafter abbreviated as 32.5% SBS) 29.5 g ( 8.0 g/mol in terms of the amount added relative to the monomer) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and AGE-DBA, 150 minutes for 15% NaPS, and 110 minutes for 32.5% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 46.0 g (ie, 0.55 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (1) having a solid content concentration of 46% by mass and a final degree of neutralization of 52 mol% was obtained. Polymer (1) had an Mw of 9,500, a Ca trapping ability of 294, and a carbon black dispersing ability of 0.77.

<Example 2>
110.0 g of pure water and 216.2 g (2.205 mol) of maleic anhydride were charged into a 2.5-liter SUS separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 100° C. while stirring. . After raising the temperature, 48% NaOH 155.0 g (1.86 mol), 40% sodium 3-allyloxy-2-hydroxypropanesulfonate aqueous solution (hereinafter abbreviated as 40% HAPS) 133.5 g (0.245 mol), AGE-DBA59 .63 g (0.245 mol) was added. When the pH was measured after charging, it was 4.8. Then, while stirring, 198.6 g (2.205 mol) of 80% AA, 183.8 g (2.205 mol) of 48% NaOH, 98.0 g of 15% NaPS (3.0 g/converted to monomer input amount) were added to the polymerization reaction system. mol), 33.6 g of 35% hydrogen peroxide aqueous solution (hereinafter abbreviated as 35% H ₂ O ₂ ) (2.4 g/mol when converted to the monomer input amount), and 173.9 g of pure water, respectively. It was dropped from the dropping nozzle. The dropping time for each of 80% AA, 48% NaOH and pure water was 120 minutes, 15% NaPS for 150 minutes, and 35% H ₂ O ₂ for 90 minutes. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 100° C. for 35 minutes for aging to complete the polymerization. The pH immediately after completion of polymerization was 6.0. After completion of the polymerization, the reaction solution was allowed to cool, and 57.4 g (ie, 0.69 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (2) having a solid concentration of 49% by mass and a final degree of neutralization of 78 mol% was obtained. Polymer (2) had an Mw of 10,200, a Ca trapping ability of 363, and a carbon black dispersing ability of 0.58.

<Example 3>
36.1 g of pure water and 29.4 g (0.30 mol) of maleic anhydride were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 14.0 g (0.17 mol) of 48% NaOH and 6.0 mg of Mohr's salt were added. Then, while stirring, 65.3 g (0.72 mol) of 80% AA, 29.0 g (0.12 mol) of AGE-DBA, 48.0 g of 15% NaPS (6.0 g when converted to the monomer input amount) were added to the polymerization reaction system. /mol), and 29.5 g of 35% SBS (6.0 g/mol in terms of the amount of added monomer) were dropped from separate dropping nozzles. The dropping times were 150 minutes for 80% AA, 120 minutes for AGE-DBA, 180 minutes for 15% NaPS, and 150 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 41.2 g (ie, 0.49 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (3) having a solid concentration of 38% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (3) had an Mw of 8,600, a Ca trapping ability of 462, and a carbon black dispersing ability of 1.00.

<Example 4>
40.9 g of pure water and 39.0 g (0.30 mol) of itaconic acid were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 14.0 g (0.17 mol) of 48% NaOH and 7.0 mg of Mohr's salt were added. Then, while stirring, 83.6 g (0.93 mol) of 80% AA, 19.6 g (0.08 mol) of AGE-DBA, 52.4 g of 15% NaPS (6.0 g when converted to the monomer input amount) were added to the polymerization reaction system. /mol), and 22.4 g of 35% SBS (6.0 g/mol in terms of the amount of added monomer) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and AGE-DBA, 150 minutes for 15% NaPS, and 120 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 49.7 g (ie, 0.60 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (4) having a solid concentration of 39% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (4) had an Mw of 34,400, a Ca trapping ability of 283, and a carbon black dispersing ability of 1.56.

<Example 5>
(Synthesis of monomer)
A method for synthesizing the iminodiacetic acid derivative monomer of AGE (AGE-IDA) is described below.
151.7 g of pure water, 119.8 g of iminodiacetic acid and 150.0 g of 48% NaOH were charged into a four-necked glass flask with a capacity of 1000 mL equipped with a reflux condenser and a stirrer (paddle blade), and heated to 60°C while stirring. heated up. Next, 102.7 g of AGE was added over 60 minutes, followed by reaction for 5 hours to obtain 50% AGE-IDA.

(Synthesis of polymer)
30.0 g of pure water and 34.3 g (0.35 mol) of maleic anhydride were placed in a 500 ml separable glass flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 16.3 g (0.20 mol) of 48% NaOH and 6.2 mg of Mohr's salt were added. Then, while stirring, 87.0 g (1.0 mol) of 80% AA, 48.0 g (0.08 mol) of 50% AGE-IDA, 55.9 g of 15% NaPS (6 .0 g/mol) and 32.0 g of 35% SBS (8.0 g/mol when converted to the monomer input amount) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and 50% AGE-IDA, 150 minutes for 15% NaPS, and 110 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 53.1 g (ie, 0.64 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (5) having a solid content concentration of 48% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (5) had an Mw of 17,000, a Ca trapping ability of 328, and a carbon black dispersing ability of 0.50.

<Example 6>
(Synthesis of monomer)
A method for synthesizing the diethanolamine derivative monomer of AGE (AGE-DEA) is described below.
235.9 g of diethanolamine was introduced into a 1000 mL capacity four-necked glass flask equipped with a reflux condenser and a stirrer (paddle blades), and the temperature was raised to 60° C. while stirring. Next, 251.1 g of AGE was added over 60 minutes, followed by reaction for 5 hours to obtain 100% AGE-DEA.

(Synthesis of polymer)
32.0 g of pure water and 34.3 g (0.35 mol) of maleic anhydride were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 16.3 g (0.20 mol) of 48% NaOH and 6.2 mg of Mohr's salt were added. Then, while stirring, 87.0 g (1.0 mol) of 80% AA, 25.5 g (0.09 mol) of 80% AGE-DEA, 56.4 g of 15% NaPS (6 .0 g/mol) and 32.2 g of 35% SBS (8.0 g/mol in terms of the monomer input amount) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and 80% AGE-DEA, 150 minutes for 15% NaPS, and 110 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 53.1 g (ie, 0.64 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (6) having a solid content concentration of 48% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (6) had an Mw of 10,200, a Ca trapping ability of 281, and a carbon black dispersing ability of 0.34.

<Example 7>
(Synthesis of monomer)
A method for synthesizing the trimethylamine derivative monomer of AGE (AGE-TMA) is described below.
104.9 g of pure water and 191.1 g of trimethylamine hydrochloride were charged into a 1000 mL capacity four-necked glass flask equipped with a reflux condenser and a stirrer (paddle blades), and heated to 50° C. while stirring. Next, 228.3 g of AGE was added over 120 minutes, followed by reaction for 2 hours to obtain 80% AGE-TMA.

(Synthesis of polymer)
36.2 g of pure water and 29.4 g (0.30 mol) of maleic anhydride were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 14.0 g (0.17 mol) of 48% NaOH and 5.2 mg of Mohr's salt were added. Then, while stirring, 74.6 g (0.8 mol) of 80% AA, 21.8 g (0.08 mol) of 80% AGE-TMA, 48.4 g of 15% NaPS (6 .0 g/mol) and 13.8 g of 35% SBS (4.0 g/mol when converted to the monomer input amount) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and 80% AGE-TMA, 150 minutes for 15% NaPS, and 110 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 45.5 g (ie, 0.55 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (7) having a solid concentration of 47% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (7) had an Mw of 8,500, a Ca trapping ability of 294, and a carbon black dispersing ability of 0.20.

<Example 8>
68.0 g of pure water and 53.9 g (0.55 mol) of maleic anhydride were placed in a 500 ml separable glass flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 100° C. while stirring. After raising the temperature, 36.7 g (0.44 mol) of 48% NaOH and 5.2 mg of Mohr's salt were added. Then, with stirring, 49.5 g (0.5 mol) of 80% AA and 41.2 g (0.5 mol) of 33% sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution (hereinafter abbreviated as 33% AMPS) were added to the polymerization reaction system with stirring. 06 mol), 14.9 g (0.06 mol) of AGE-DBA, 28.6 g of 15% NaPS (3.5 g/mol when converted to the input amount of the monomer), 10.5 g of 35% H ₂ O ₂ (relative to the monomer 3.0 g/mol in terms of input amount) were dropped from separate dropping nozzles. The dropping time was 150 minutes for 80% AA and 33% AMPS, 180 minutes for 15% NaPS, and 120 minutes for AGE-DBA and 35% H ₂ O ₂ . Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 100° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 32.1 g (ie, 0.38 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (8) having a solid content concentration of 46% by mass and a final degree of neutralization of 50 mol% was obtained. Polymer (8) had an Mw of 7,700, a Ca trapping ability of 312, and a carbon black dispersing ability of 0.56.

<Comparative Example 1>
100.0 g of pure water was introduced into a 1.0-liter glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 70° C. while stirring. After raising the temperature, 4.3 mg of Mohr's salt was added. Then, while stirring, 189.0 g (2.10 mol) of 80% AA, 50.4 g (0.21 mol) of AGE-DBA, and 92.3 g of 15% NaPS (6.0 g/converted to monomer input amount) were added to the polymerization reaction system. mol), and 62.6 g (9.5 g/mol in terms of the monomer input amount) of 35% sodium hydrogen sulfite aqueous solution (hereinafter abbreviated as 35% SBS) were dropped from separate dropping nozzles. The dropping time was 180 minutes for 80% AA and 35% SBS, 170 minutes for AGE-DBA, and 190 minutes for 15% NaPS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 70° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 122.5 g (ie, 1.47 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (9) having a solid content concentration of 44% by mass and a final degree of neutralization of 70 mol% was obtained. Polymer (9) had an Mw of 14,700, a Ca trapping ability of 185, and a carbon black dispersing ability of 1.15.

<Comparative Example 2>
100.0 g of pure water was introduced into a 1.0-liter glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 85° C. while stirring. After raising the temperature, 13.3 mg of Mohr's salt was added. Then, while stirring, 80% AA 183.8 g (2.04 mol), 40% HAPS 60.6 g (0.112 mol), AGE-DBA 42.0 g (0.173 mol), 15% NaPS 93.0 g (per unit 6.0 g/mol in terms of monomer input amount) and 39.9 g of 35% SBS (6.0 g/mol in terms of monomer input amount) were dropped from separate dropping nozzles. The dropping times were 180 minutes for 80% AA, 120 minutes for 40% HAPS and AGE-DBA, 210 minutes for 15% NaPS, and 175 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 85° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 111.7 g (ie, 1.34 mol) of 48% NaOH was gradually added dropwise to the reaction solution with stirring to neutralize it. Thus, a polymer (10) having a solid content concentration of 42% by mass and a final degree of neutralization of 70 mol% was obtained. Polymer (10) had an Mw of 9,400, a Ca trapping ability of 144, and a carbon black dispersing ability of 1.28.

<Comparative Example 3>
100.0 g of pure water was introduced into a 1.0-liter glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 85° C. while stirring. After raising the temperature, 14.1 mg of Mohr's salt was added. Next, while stirring, 210.0 g (2.33 mol) of 80% AA, 60.6 g (0.112 mol) of 40% HAPS, and a normal-butanol adduct of allyl glycidyl ether (hereinafter abbreviated as AGE-BuOH) were added to the polymerization reaction system under stirring.21. 0 g (0.112 mol), 102.3 g of 15% NaPS (6.0 g/mol when converted to the input amount of monomer), 43.8 g of 35% SBS (6.0 g/mol when converted to the input amount of monomer) were dropped from separate dropping nozzles. The dropping times were 180 minutes for 80% AA, 120 minutes for 40% HAPS and AGE-BuOH, 210 minutes for 15% NaPS, and 175 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 85° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 128.8 g (ie, 1.55 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (11) having a solid content concentration of 42% by mass and a final degree of neutralization of 70 mol% was obtained. Polymer (11) had an Mw of 7,200, a Ca trapping ability of 185, and a carbon black dispersing ability of 0.90.

<Comparative Example 4>
89.8 g of pure water was introduced into a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 85° C. while stirring. After raising the temperature, 7.0 mg of Mohr's salt was added. Then, under stirring, 126.1 g (1.40 mol) of 80% AA, 17.8 g (0.07 mol) of AGE-DBA, and 23.6 g of 15% NaPS (2.4 g/converted to the monomer input amount) were added to the polymerization reaction system. mol), and 25.8 g of 20% SBS (3.5 g/mol in terms of the monomer input amount) were dropped from separate dropping nozzles. The dropping time was 180 minutes for 80% AA and AGE-DBA, 200 minutes for 20% SBS, and 210 minutes for 15% NaPS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 85° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 70.0 g (ie, 0.84 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (12) having a solid content concentration of 45% by mass and a final degree of neutralization of 60 mol% was obtained. Polymer (12) had an Mw of 11,400, a Ca trapping ability of 189, and a carbon black dispersing ability of 2.26.

<Comparative Example 5>
27.4 g of pure water and 29.4 g (0.30 mol) of maleic anhydride were placed in a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 90° C. while stirring. After raising the temperature, 14.0 g (0.17 mol) of 48% NaOH and 6.0 mg of Mohr's salt were added. Then, while stirring, 96.4 g (1.07 mol) of 80% AA, 54.8 g of 15% NaPS (6.0 g/mol in terms of the monomer input amount), 15.7 g of 35% SBS (relative to 4.0 g/mol in terms of monomer input amount) were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA, 150 minutes for 15% NaPS, and 120 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 90° C. for 60 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 69.5 g (ie, 0.83 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (13) having a solid content concentration of 48% by mass and a final degree of neutralization of 60 mol% was obtained. Polymer (13) had an Mw of 8,200, a Ca trapping ability of 339, and a carbon black dispersing ability of 0.01.

<Comparative Example 6>
81.4 g of pure water was introduced into a 500 ml glass separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 85° C. while stirring. After raising the temperature, 7.4 mg of Mohr's salt was added. Then, under stirring, 80% AA 126.1 g (1.40 mol), 40% HAPS 32.4 g (0.06 mol), AGE-DBA 14.5 g (0.06 mol), 15% NaPS 24.3 g (per unit 2.4 g/mol in terms of monomer input amount) and 26.6 g of 20% SBS (3.5 g/mol in terms of monomer input amount) were dropped from separate dropping nozzles. The dropping times were 180 minutes for 80% AA, 120 minutes for 40% HAPS and AGE-DBA, 210 minutes for 15% NaPS, and 180 minutes for 35% SBS. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 85° C. for 30 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 70.0 g (ie, 0.84 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (14) having a solid content concentration of 41% by mass and a final degree of neutralization of 60 mol% was obtained. Polymer (14) had an Mw of 13,200, a Ca trapping ability of 192, and a carbon black dispersing ability of 1.91.

<Comparative Example 7>
110.0 g of pure water and 216.2 g (2.20 mol) of maleic anhydride were charged into a 2.5-liter SUS separable flask equipped with a reflux condenser and a stirrer, and the temperature was raised to 100° C. while stirring. . After raising the temperature, 270.0 g (3.24 mol) of 48% NaOH and 267.1 g (0.49 mol) of 40% HAPS were added. Then, while stirring, 198.6 g (2.20 mol) of 80% AA, 78.4 g of 15% NaPS (2.4 g/mol in terms of the monomer input amount), 35% H ₂ O ₂ 28 were added to the polymerization reaction system. 0 g (2.0 g/mol in terms of the amount of added monomer) and 147.8 g of pure water were dropped from separate dropping nozzles. The dropping time was 120 minutes for 80% AA and 15% NaPS, 75 minutes for 35% H ₂ O ₂ , and 120 minutes for pure water. Moreover, during each dropping time, each component was dropped continuously at a constant dropping rate.
After completion of the dropwise addition, the reaction solution was kept at 100° C. for 35 minutes for aging to complete the polymerization. After completion of the polymerization, the reaction solution was allowed to cool, and 136.6 g (ie, 1.64 mol) of 48% NaOH was gradually added dropwise to the reaction solution under stirring for neutralization. Thus, a polymer (15) having a solid concentration of 42% by mass and a final degree of neutralization of 79 mol% was obtained. Polymer (15) had an Mw of 8,300, a Ca trapping ability of 367, and a carbon black dispersing ability of 0.01.

Table 1 shows the weight average molecular weight, Ca trapping ability and carbon black dispersing ability of the polymers obtained in Examples 1-8 and Comparative Examples 1-7.
In addition, in Table 1, MA represents maleic acid.

From the results of the above Examples and Comparative Examples, Examples 1 to 8 showed excellent performance in both Ca-capturing ability and carbon black dispersing ability, whereas Comparative Examples 1-7 showed excellent Ca-trapping ability. or carbon black dispersibility. Thus, it was revealed that the polymer having the specific structure of the present invention is excellent in both Ca trapping ability and carbon black dispersing ability.

Claims (8)

A structural unit (a) derived from the unsaturated monocarboxylic acid monomer (A), a structural unit (b) derived from the unsaturated dicarboxylic acid monomer (B), and a cationic monomer (C) derived The ratio of the structural unit (b) is 10 to 50 mol% with respect to 100 mol% of the total structural units, and the weight average molecular weight is 2000 to 500000. A carboxyl group-containing copolymer. A structural unit (a) derived from the unsaturated monocarboxylic acid monomer (A), a structural unit (b) derived from the unsaturated dicarboxylic acid monomer (B), and a cationic monomer (C) derived A carboxyl group-containing copolymer characterized in that the ratio of the structural unit (b) is 10 to 50 mol% with respect to 100 mol% of the total structural units. 3. The carboxyl group-containing copolymer according to claim 1, further comprising a structural unit (d) derived from the sulfonic acid group-containing monomer (D). The carboxyl group-containing copolymer according to any one of claims 1 to 3, wherein the cationic monomer (C) has a hydrophobic group. The cationic monomer (C) has the following formulas (1) to (3);

(In formulas (1) and (2), R ¹ and R ² are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a functional group, provided that R At least one of ¹ and R ² is a hydrocarbon group optionally having a functional group and having 1 to 20 carbon atoms.In the formula (3), R ³ to R ⁵ are the same or different and each of Represents a hydrocarbon group having 1 to 20 carbon atoms which may have W ^- represents an anion). The carboxyl group-containing copolymer according to 1. The carboxyl group-containing copolymer according to any one of claims 1 to 5, wherein the unsaturated monocarboxylic acid-based monomer (A) is (meth)acrylic acid (salt). The carboxyl group-containing copolymer according to any one of claims 1 to 6, wherein the unsaturated dicarboxylic acid-based monomer (B) is maleic acid (salt) and/or maleic anhydride. A scale inhibitor comprising the carboxyl group-containing copolymer according to any one of claims 1 to 7.