JP7847466B2 - Composition containing a cationic group-containing polymer - Google Patents

Description

This invention relates to a composition containing a cationic group-containing polymer. The composition containing the cationic group-containing polymer of this invention can be suitably used as a cosmetic composition such as a skin cosmetic, a topical skin preparation, or a hair cosmetic.

In recent years, due to consumer demand for cleanliness and hygiene, various products with antibacterial treatments have become commercially available. Various antibacterial agents have also been developed for use in these products, including inorganic and organic antibacterial agents. Patent Document 1 describes an antibacterial agent containing a cationic group-containing polymer, wherein the polymer has structural units derived from cationic group-containing monomers and structural units derived from hydrophobic monomers, the proportion of structural units derived from cationic group-containing monomers is 36 to 99.9% by mass relative to 100% by mass of all structural units, the weight-average molecular weight is 4,000 to 1,000,000, and the hydrophobic monomer has a homopolymer solubility parameter of 15 or less.

Japanese Patent Publication No. 2017-214346

When using antibacterial agents as additives in cosmetics such as lotions, the polymer described in Patent Document 1 sometimes suffers from insufficient solubility in water due to its hydrophobic group. While neutralization with acid can improve solubility, the storage stability of these neutralized aqueous solutions was also a requirement.

In view of the above-mentioned problems, the inventors conducted research and found that a composition comprising polymer (A) having structural units derived from cationic group-containing monomers and structural units derived from hydrophobic monomers, and an acid, wherein the total amount of acid per mole of cationic group is 0.10 mol% to 1.50 mol%, exhibits excellent preservative and antibacterial properties when used as a cosmetic, as well as excellent solubility in water and excellent storage stability when dissolved in water. Thus, the present invention was completed.

According to the present invention, it is possible to provide a composition that exhibits excellent preservative and antibacterial properties, excellent solubility in water, and excellent storage stability when dissolved in water. Furthermore, it is possible to provide a cosmetic composition that suppresses stickiness and provides a refreshing feel.

The details of this disclosure are described below.
The composition of this disclosure comprises a polymer (A) having structural units derived from a cationic group-containing monomer and structural units derived from a hydrophobic monomer, and an acid, characterized in that the total amount of acid per mole of cationic group is 0.10 mol% or more and 1.50 mol% or less.
The polymer (A) of the present disclosure has structural units derived from cationic group-containing monomers and structural units derived from hydrophobic monomers.
The structural units derived from cationic group-containing monomers in this disclosure are those with the same structure as a cationic group-containing monomer in which at least one carbon-carbon double bond is replaced by a carbon-carbon single bond, and are not limited to structural units formed by polymerization of cationic group-containing monomers, but may also be structural units formed by post-reactions after polymerization, for example.
The structural units derived from the cationic group-containing monomer in this disclosure are structural units derived from monomers containing cationic groups.

The cationic group in this disclosure is a group having a cation or a group generating a cation, and is not particularly limited, but examples include primary to tertiary amino groups and quaternary ammonium bases. Among the above cationic groups, tertiary amino groups or quaternary ammonium bases are preferred, and tertiary amino groups are more preferred from the viewpoint of having antibacterial properties and low skin irritation. From the viewpoint of skin irritation, primary to tertiary amino groups may also be used.

<Primary to Tertiary Amino Groups>
The primary to tertiary amino groups are represented by the following formula (1):

The structure is preferably represented by the formula (wherein _R1 and _R2 are the same or different, and represent a hydrogen atom and a hydrocarbon group having 1 to 12 carbon atoms). 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 even more preferably an alkyl group. The number of carbon atoms in the hydrocarbon group is preferably 1 to 10, more preferably 1 to 8, particularly preferably 1 to 5, and most preferably 1 to 2.
Preferably, at least one of _R1 and _R2 is a hydrocarbon group having 1 to 12 carbon atoms, and more preferably, both _R1 and _R2 are hydrocarbon groups having 1 to 12 carbon atoms. Among primary to tertiary amino groups, tertiary amino groups are preferred. Dimethylamino groups and diethylamino groups are preferred as tertiary amino groups.

<Quaternary ammonium bases>
The above quaternary ammonium base is given by the following formula (2):

The structure is preferably represented by the formula (wherein _R3 to _R5 are the same or different and represent hydrocarbon groups having 1 to 12 carbon atoms). 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 even more preferably an alkyl group. The number of carbon atoms in _R3 to _R5 is more preferably 1 to 10, even more preferably 1 to 7, and particularly preferably 1 to 5.
The hydrocarbon groups _R3 to _R5 are most preferably methyl or ethyl groups.

<Monomers containing cationic groups>
In this disclosure, a cationic group-containing monomer includes, for example, a monomer containing the above-mentioned primary to tertiary amino groups in its structure, and a monomer containing a quaternary ammonium base in its structure. Specifically, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminopropyl (meth)acrylate, and other N,N-dialkylamino group-containing (meth)acrylates and monomers obtained by adding a quaternizing agent to the above monomers or their neutralization products with acids; N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide, and other N,N-dialkylamino group-containing (meth)acrylamides and monomers obtained by adding a quaternizing agent to the above monomers or their neutralization products with acids; monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, (meth)acrylic acid 2-(tert- Examples include monoalkylamino group-containing (meth)acrylates such as butylamino)ethyl and their neutralization products with acids; monoalkylamino group-containing (meth)acrylamides such as monomethylaminoethyl (meth)acrylamide, monoethylaminoethyl (meth)acrylamide, monomethylaminopropyl (meth)acrylamide, monoethylaminopropyl (meth)acrylamide and their neutralization products with acids; esters of (meth)acrylic acid and alkanolamines such as (meth)acrylic acid-2-aminoethyl and their neutralization products with acids; N,N-diallylmethylamine and monomers obtained by adding a quaternizing agent thereto or their neutralization products with acids; allylamine and their neutralization products with acids; addition reaction products of unsaturated monomers having a cyclic ether-containing group with 2 to 8 carbon atoms, such as 1-allyloxy-3-dibutylamino-2-ol and 1-allyloxy-3-diethanolamino-2-ol, and amine compounds having 1 to 24 carbon atoms, and monomers obtained by adding a quaternizing agent thereto or their neutralization products with acids. Particularly preferred are N,N-dialkylamino group-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and N,N-diethylaminopropyl (meth)acrylate, as well as monomers obtained by adding a quaternizing agent to the above monomers, or their neutralized products with an acid.

<Hydrophobic monomers>
In this disclosure, a structural unit derived from a hydrophobic monomer refers to a structural unit that has the same structure as the structure formed by the polymerization of hydrophobic monomers. That is, a structural unit derived from a hydrophobic monomer is not limited to a structural unit actually formed by the polymerization of hydrophobic monomers; any structural unit that has the same structure and is formed by a different manufacturing method is also included as a structural unit derived from a hydrophobic monomer. For example, a structural unit derived from methyl acrylate, CH2=CH(-COOCH3), can be represented as -CH2-CH(-COOCH3)-.
The above hydrophobic monomers preferably have a solubility parameter of 15 or less in homopolymers (homopolymers) obtained by homopolymerization. However, even if the solubility parameter is 15 or less, monomers that have a cationic group and contain a quaternary ammonium base shall be included in the cationic group-containing monomers.

The solubility parameters in this disclosure are values calculated by the method described on pages 147-154 of "Polymer Engineering and Science" (1974, Vol. 14, No. 2).
The method is outlined below. The solubility parameter (δ) (cal/cm³) 1/2 of a homopolymer is calculated based on the evaporation energy (Δei) and molar volume (Δvi) of the constituent units that make up the homopolymer, using the following calculation method.
δ=(Δei/Δvi)1/2 (cal/cm3)1/2
If the solubility parameter of the homopolymer obtained by polymerizing a hydrophobic monomer alone is 15 or less, the hydrophobicity of the polymer of the present invention is sufficient, improving its affinity for bacterial cell membranes and inhibiting the physiological activity of the cell membranes, thereby exhibiting excellent antibacterial properties.

Examples of the hydrophobic monomers mentioned above include esters (meth)acrylates (hereinafter also called (meth)acrylic acid esters) of (meth)acrylic acid and optionally substituted alcohols; unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, α-allyloxyacrylic acid and their salts; aromatic vinyl monomers such as styrene; olefin monomers such as ethylene and propylene; esters of unsaturated alcohols such as vinyl acetate and carboxylic acids; vinyl halides such as vinyl chloride; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; addition products of unsaturated monomers having a cyclic ether-containing group with 2 to 8 carbon atoms, such as 1-allyloxy-3-butoxypropan-2-ol, and alcohols with 1 to 20 carbon atoms; alkylene oxide adducts of unsaturated alcohols with 2 to 20 carbon atoms, such as ethylene oxide adducts of allyl alcohol, ethylene oxide adducts of metharyl alcohol, and ethylene oxide adducts of isoprenol, and their terminally hydrophobic modified products; and cyclic vinyl monomers such as N-vinylpyrrolidone. The hydrophobic monomer described above is preferably one having an alkyl group with two or more carbon atoms. Having an alkyl group with two or more carbon atoms increases the affinity of the hydrophobic monomer to the cell membrane of microorganisms, thereby further improving its antibacterial properties.
Examples of salts of the above-mentioned unsaturated monocarboxylic acid include metal salts. Examples of metals in the above-mentioned metal salts include alkali metals such as lithium, sodium, and potassium.
Examples of substituents in the above (meth)acrylate include hydroxyl groups; alkoxy groups having 1 to 18 carbon atoms, such as methoxy and ethoxy groups; oxo group-containing groups, such as oxyalkylene groups, sulfonic acid groups, and phosphate groups; halogeno groups, such as fluoro groups; epoxy groups, such as glycidyl groups; and carbonyl groups, such as aldehyde groups.

Examples of alkyl (meth)acrylates that do not have the substituents described above include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, tridecyl (meth)acrylate, cyclohexyl (meth)acrylate and other cycloalkyl (meth)acrylates, n-lauryl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl methacrylate, and the like.

Examples of hydroxyl group-containing (meth)acrylates include hydroxyl group-containing (meth)acrylates with ester groups having 1 to 18 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
Examples of alkoxyalkyl (meth)acrylates include methoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, and trimethylolpropane tripoxy (meth)acrylate.
Examples of oxo group-containing (meth)acrylates include (di)ethylene glycol (methoxy) (meth)acrylates such as ethylene glycol (meth)acrylate, ethylene glycol methoxy (meth)acrylate, diethylene glycol (meth)acrylate, and diethylene glycol methoxy (meth)acrylate; alkoxy polyalkylene glycol (meth)acrylates with 1 to 100 repeating alkylene glycols such as alkoxy polyethylene glycol methacrylate (Anthox LMA-10); sulfopropyl (meth)acrylate; and (meth)acryloyloxyethyl phosphate.

Examples of fluorogroup-containing (meth)acrylates include trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, and other alkyl (meth)acrylates containing fluorogroups with 2 to 6 carbon atoms in the ester group.
Examples of epoxy group-containing (meth)acrylates include glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, and glycidyl allyl ether.
Examples of carbonyl group-containing (meth)acrylates include acetonyl (meth)acrylate, diacetone (meth)acrylate, 2-hydroxypropyl (meth)acrylate acetylacetate, butanediol-1,4-acrylate acetylacetate, 2-(acetoacetoxy)ethyl (meth)acrylate, and (meth)acryloyloxyalkylpropenal.

The polymers of this disclosure preferably contain at least one structural unit derived from a (meth)acrylic acid ester as a structural unit derived from a hydrophobic monomer. The structural unit derived from the (meth)acrylic acid ester is given by the following formula (2):

(In the formula, R5 represents a hydrogen atom or a methyl group. R6 represents a hydrocarbon group having 1 to 30 carbon atoms.)
It is preferable that the structural unit is represented by .

The above (meth)acrylic acid ester and the structural units derived from the above (meth)acrylic acid ester preferably have 1 to 20 carbon atoms in the hydrocarbon group, more preferably 1 to 16, even more preferably 1 to 12, and particularly preferably 2 to 8. When the number of carbon atoms in the hydrocarbon group is 2 to 8, the water solubility and viscosity of the polymer can be kept within a suitable range, and the polymer can be easily manufactured. Furthermore, safety is improved and antibacterial properties are further enhanced.

The hydrocarbon group mentioned above is not particularly limited and includes linear hydrocarbon groups such as alkyl groups, alkenyl groups, and alkynyl groups, as well as aromatic hydrocarbon groups and cyclic hydrocarbon groups such as cycloalkyl groups and cycloalkenyl groups. The hydrocarbon group may be branched, and in the case of branching, the number of carbon atoms in the hydrocarbon group refers to the total number of carbon atoms in the main chain and the branched chain. Examples of alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, dodecyl group, stearyl group, and eicosyl group. Examples of alkenyl groups include vinyl group, allyl group, 1-butenyl group, 2-butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, dodecenyl group, octadecenyl group, and eicosenyl group. Examples of the alkynyl groups mentioned above include ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octinyl group, noninyl group, desinyl group, dodecynyl group, octadecynyl group, and icosinyl group.

Examples of the aromatic hydrocarbon groups include phenyl, benzyl, tolyl, and o-xylyl groups. Examples of the cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. Examples of the cycloalkenyl groups include cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. The hydrocarbon groups are preferably alkyl and alkenyl groups, and more preferably alkyl groups. That is, the (meth)acrylic acid ester is preferably an alkyl (meth)acrylate.

Preferably, the alkyl (meth)acrylate is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or n-octyl (meth)acrylate. More preferably, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate. Particularly preferred is ethyl (meth)acrylate.

<Other ingredients>
The polymers of this disclosure may have structural units derived from monomers other than the cationic group-containing monomers and hydrophobic monomers mentioned above. The other monomers are not particularly limited, and the solubility parameter of the homopolymer of the other monomers may be 15 or less or greater than 15. Whether the solubility parameter of the other monomers is 15 or less or greater than 15, the hydrophobicity of the polymer will be sufficiently maintained as long as the hydrophobic monomers are polymerized in a preferred proportion. Furthermore, from the viewpoint of adjusting viscosity, monomers having two or more ethylenically unsaturated groups may be included regardless of the value of the solubility parameter. Monomers having two or more ethylenically unsaturated groups include esters of (meth)acrylic acid with two or more substituted hydroxyl groups of polyols such as ethylene glycol, propylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, polyglycerin, trimethylolpropane, pentaerythritol, saccharose, sorbitol, and 1,4-butanediol; methacrylic acid esters with two or more substituted hydroxyl groups of the above polyols; ethers of unsaturated alcohols such as allyl alcohol and vinyl alcohol with two or more substituted hydroxyl groups of the above polyols; diallyl phthalate, triallyl phosphate, allyl methacrylate, tetraallyloxyethane, triallyl cyanurate, divinyl adipate, vinyl crotonate, 1,5-hexadiene, and divinylbenzene. These other monomers may be used individually or in combination of two or more. From the viewpoint of improving antibacterial properties, the polymer of the present invention may also be copolymerized with polymerizable metal salts as other monomers. Examples of polymerizable metal salts include heavy metal salts of unsaturated carboxylic acids such as zinc acrylate, zinc methacrylate, and zinc α-allyloxyacrylate.
This disclosure

<Molecular weight>
The weight-average molecular weight of the cationic group-containing polymer contained in the antibacterial agent of the present invention is preferably 4,000 to 1,000,000. When the weight-average molecular weight of the cationic group-containing polymer is within this range, the adsorption of the antibacterial agent to the material on which it is used tends to improve, thereby suppressing washing away during cleaning and tending to improve the antibacterial effect on the material. The weight-average molecular weight is preferably 4,000 to 800,000, more preferably 5,000 to 600,000, even more preferably 6,000 to 400,000, even more preferably 7,000 to 200,000, even more preferably 7,000 to 100,000, and particularly preferably 7,000 to 80,000. The weight-average molecular weight of the cationic group-containing polymer can be measured by the method described in the examples.

<Composition of polymer>
The polymers of this disclosure have 36 to 99.9% by mass of structural units derived from cationic group-containing monomers, based on 100% by mass of the total amount of structural units forming the polymer. Preferably, this is 40 to 99% by mass, more preferably 42 to 98% by mass, even more preferably 43 to 97% by mass, even more preferably 45 to 96% by mass, particularly preferably 47 to 95% by mass, and most preferably 50 to 94% by mass.
The polymers of this disclosure preferably contain 80 parts by mass or more, 90 parts by mass or more, more preferably 95 parts by mass or more, and may also contain 100 parts by mass, of primary to tertiary amines per 100 parts by mass of structural units derived from cationic group monomers, from the viewpoint of low skin irritation.

The polymer of this disclosure preferably has 0.01 to 64% by mass of structural units derived from hydrophobic monomers, based on 100% by mass of the total amount of structural units forming the polymer. More preferably 0.05 to 60% by mass, even more preferably 0.1 to 58% by mass, even more preferably 0.5 to 56% by mass, even more preferably 1 to 54% by mass, particularly preferably 3 to 52% by mass, and most preferably 5 to 50% by mass.
The polymers of this disclosure preferably have a content of hydrophobic monomer-derived structural units in the polymer of 1 to 100% by mass, relative to 100% by mass of cationic group-containing monomer-derived structural units in the polymer. More preferably, it is 2 to 95% by mass, even more preferably 3 to 90% by mass, even more preferably 4 to 85% by mass, even more preferably 5 to 80% by mass, and particularly preferably 10 to 75% by mass. When the content of hydrophobic monomer-derived structural units in the polymer of the present invention is within this range, the antibacterial performance of the polymer tends to improve.

When the polymer of this disclosure has structural units derived from an alkyl (meth)acrylate as structural units derived from a hydrophobic monomer, the proportion of structural units derived from the alkyl (meth)acrylate is preferably 0.01 to 64% by mass, based on 100% by mass of the total amount of structural units forming the polymer. More preferably, it is 1 to 54% by mass, and even more preferably 3 to 52% by mass.
In the polymers of this disclosure, the content of structural units derived from unsaturated monocarboxylic acids is preferably 0 to 10% by mass, relative to 100% by mass of the total amount of structural units forming the polymer, from the viewpoint of storage stability such as promoting hydrolysis of the polymer. More preferably, it is 0 to 8% by mass, and even more preferably 0 to 5% by mass.

In the polymers of this disclosure, the content of structural units derived from unsaturated monocarboxylic acids is preferably 0 to 10% by mass, relative to 100% by mass of the total amount of structural units derived from hydrophobic monomers, from the viewpoint of promoting hydrolysis of the polymer. More preferably, it is 0 to 8% by mass, and even more preferably 0 to 5% by mass.
The polymer of this disclosure preferably has a content of structural units derived from other monomers of 0 to 10% by mass, relative to 100% by mass of the total amount of structural units forming the polymer. More preferably, it is 0 to 8% by mass, and even more preferably 0 to 5% by mass. Among the other monomers, the content of structural units derived from monomers having two or more ethylenically unsaturated groups is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass, and even more preferably 0 to 0.1% by mass, relative to 100% by mass of the total amount of structural units forming the polymer.

<Acid>
In this disclosure, the acid is not particularly limited, but is used, for example, to neutralize primary to tertiary amino groups among structural units derived from cationic group-containing monomers. In the compositions of this disclosure, the acid may exist in the form of a salt after being neutralized by the above-mentioned amino group or other base, or it may exist in an unneutralized form. The acid used for neutralization is not particularly limited, but examples include inorganic acids or organic acids.
Examples of inorganic acids include phosphoric acid, sulfuric acid, nitric acid, and hydrochloric acid, with phosphoric acid being preferred from the viewpoint of storage stability after neutralization and compatibility with cosmetics.
Examples of organic acids include compounds containing carboxyl groups, compounds containing phosphate groups, compounds containing hydroxycarboxylic acid groups, alkyl sulfates, alkyl phosphorics, amino acid derivatives, ascorbic acid, and taurine.

Examples of carboxyl group-containing compounds in this disclosure include compounds having one carboxyl group, such as acetic acid, propionic acid, benzoic acid, and aliphatic monocarboxylic acids; and compounds containing multiple carboxyl groups, such as malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, oxalic acid, and diethylenetriaminepentaacetic acid. Compounds containing multiple carboxyl groups are more preferred. While the above-mentioned compounds containing multiple carboxyl groups may have two or more carboxyl groups, it is preferable, for example, for one molecule to have 2 to 10 carboxyl groups, preferably 2 to 5 carboxyl groups, and preferably 2 to 3 carboxyl groups. When the number of carboxyl groups in one molecule falls within these ranges, the storage stability of the composition in this disclosure tends to improve.

Examples of phosphate-containing compounds in this disclosure include etidronic acid and phytic acid.
Examples of hydroxycarboxylic acids in this disclosure include glycolic acid, lactic acid, hydroxyacrylic acid, oxybutyric acid, glyceric acid, malic acid, tartaric acid, citric acid, mandelic acid, salicylic acid, gluconic acid, and gallic acid, with citric acid, lactic acid, malic acid, tartaric acid, and mandelic acid being more preferred.
Examples of amino acid derivatives of this disclosure include glycine, alanine, valine, leucine, isoleucine, threonine, serine, cysteine, methionine, aspartic acid, asparagine, glutamic acid, diiodotyrosine, lysine, arginine, histidine, phenylalanine, tyrosine, tryptophan, proline, oxyproline, glutamine, and the like, with glutamic acid and aspartic acid being more preferred.

From the viewpoint of solubility in water and storage stability, the acids of this disclosure are preferably phosphoric acid, compounds containing multiple carboxyl groups, compounds containing multiple phosphate groups, compounds containing hydroxycarboxylic acid groups, amino acid derivatives, and ascorbic acid, and more preferably citric acid, lactic acid, succinic acid, malic acid, tartaric acid, glutamic acid, and aspartic acid. When a composition of this disclosure contains an acid selected from the above, the storage stability of the composition tends to improve.
On the other hand, from the viewpoint of odor, the content of acetic acid per 100 parts by mass of the acid of this disclosure is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably no acetic acid at all. In this disclosure, "not included" means intentionally not used.

<Composition>
The composition of this disclosure is characterized by comprising a polymer (A) having structural units derived from cationic group-containing monomers and structural units derived from hydrophobic monomers, and an acid.
The composition disclosed herein contains polymer (A) in 100 parts by mass of composition, which may be 0.00001 parts by mass or more, preferably 0.00005 parts by mass or more, more preferably 0.00007 parts by mass or more, even more preferably 0.0001 parts by mass or more, and may be 5.0 parts by mass or less, preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or less.
The composition disclosed herein may contain 0.00001 parts by mass or more, preferably 0.00005 parts by mass or more, more preferably 0.0001 parts by mass or more, and even more preferably 0.0005 parts by mass or more, from the viewpoint of compatibility and storage stability, 1.0 part by mass or less, preferably 0.7 parts by mass or less, more preferably 0.6 parts by mass or less, and even more preferably 0.5 parts by mass or less.
The composition disclosed herein may contain 0.1 parts by mass or less, preferably 0.05 parts by mass or less, more preferably 0.02 parts by mass or less, from the viewpoint of odor, and it is even more preferable that the composition does not contain acetic acid. In this disclosure, "not containing" means that it is intentionally not used.

In the compositions of this disclosure, the total amount of acid per mole of cationic groups in polymer (A) may be 0.10 mol% or more, preferably 0.15 mol% or more, more preferably 0.20 mol% or more, even more preferably 0.25 mol% or more, and may be 1.50 mol% or less, preferably 1.40 mol% or less, more preferably 1.30 mol% or less, and even more preferably 1.20 mol% or less. When the amount is within the above range, the storage stability of the composition tends to improve.

The compositions of this disclosure may have a total amount of acid per mole of structural units derived from cationic group-containing monomers of 0.10 mol% or more, preferably 0.15 mol% or more, more preferably 0.20 mol% or more, even more preferably 0.25 mol% or more, and may be 1.50 mol% or less, preferably 1.40 mol% or less, more preferably 1.30 mol% or less, and even more preferably 1.20 mol% or less.

The pH of the compositions disclosed herein can be determined according to the intended use.
For example, in skincare applications such as lotions, serums, gels, emulsions, creams, and mist cosmetics; in haircare applications such as shampoos, hair rinses, hair conditioners, hair treatments, hair milks, hair mists, hair growth lotions, hair waxes, hair gels, and hair sprays; and in makeup applications such as liquid foundations and blushes, the pH is preferably 2.5 or higher, more preferably 3.0 or higher, even more preferably 3.5 or higher, preferably 8.0 or lower, more preferably 7.5 or lower, and even more preferably 7.0 or lower. In fatty acid-based body soaps, fatty acid-based facial cleansing foams, and bar soaps, the pH is preferably 7.5 or higher, more preferably 8.0 or higher, even more preferably 8.5 or higher, preferably 12.0 or lower, more preferably 11.5 or lower, and even more preferably 11.0 or lower.
For sun care applications, such as O/W gels and milks, a pH of 4.5 or higher is preferred, 5.0 or higher is more preferred, 5.5 or higher is even more preferred, 9.0 or lower is preferred, 8.5 or lower is more preferred, and 8.0 or lower is even more preferred.

The compositions of this disclosure may contain compounds other than polymer (A) and acids. Compounds other than polymer (A) and acids are not particularly limited, but examples include water, nonionic surfactants, alcohols, thickeners, powder components, pH adjusters, anionic surfactants, cationic surfactants, amphoteric surfactants, oils, humectants, water-soluble polymers, antioxidants, UV absorbers, chelating agents, preservatives, antibacterial agents, colorants, fragrances, etc. For example, 3-hydroxy-2,2'iminodisuccinic acid or its salt (e.g., tetrasodium salt), a biodegradable chelating agent, may be included in the cosmetic compositions of this disclosure because it has antibacterial properties, scum-inhibiting effects, oil oxidation-inhibiting effects, and yellowing-inhibiting effects in the acidic to alkaline range.

In this disclosure, "water" refers to purified water, distilled water, ion-exchanged water, pure water, soft water, hard water, natural water, deep-sea water, alkaline ionized water, and purified water obtained by various other methods.
The compositions of this disclosure preferably contain 1% by mass or more of water, more preferably 5% by mass or more, and more preferably 10% by mass or more, based on 100% by mass of the total cosmetic composition. On the other hand, the cosmetic compositions of this disclosure preferably contain 99% by mass or less of water, more preferably 95% by mass or less, and more preferably 90% by mass or less, based on 100% by mass of the total cosmetic composition. Within these ranges, the feel when used as a cosmetic and the storage stability tend to be further improved.

In this disclosure, a nonionic surfactant is a compound that does not exhibit ionic properties when dissolved in water, but possesses surfactant properties.
Examples of nonionic surfactants in this disclosure include ester-type nonionic surfactants and ether-type nonionic surfactants.
For example, ester-type nonionic surfactants are esters of fatty acids and alcohols, or esters of fatty acids and sugars. Examples include glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, and polyglycerin fatty acid esters. The fatty acid is a carboxylic acid having a hydrocarbon group, and the number of carbon atoms in the hydrocarbon group is preferably 2 to 25, more preferably 8 to 22, and particularly preferably 8 to 18. For example, ether-type nonionic surfactants include alkyl polyalkylene glycols, which are compounds obtained by adding alkylene oxide to a long-chain alcohol, such as alkyl polyethylene glycol and polyoxyethylene alkylphenyl ether.

In the nonionic surfactants of this disclosure, one preferred embodiment is the use of two or more nonionic surfactants with different HLB (Hydrophilic-Lipophilic Balance) values. The HLB (Hydrophilic-Lipophilic Balance) value indicates the degree of affinity of a surfactant to water and oil. For example, if the HLB value is 8 to 16, it can be stably dispersed in water and suitably used as an O/W type emulsifier. If the HLB value is 3 to 6, it has low solubility in water but can be slightly dispersed and suitably used as a W/O type emulsifier.

When using two or more nonionic surfactants with different HLB values, at least one nonionic surfactant with an HLB value of 8 to 16 and one nonionic surfactant with an HLB value of 3 to 6 should be used. Using two nonionic surfactants with different HLB values in this way fixes the bilayer structure constituting the α-gel, resulting in a high-strength bilayer and increased strength and stability of the formed oil droplets. For example, a nonionic surfactant with an HLB value of 8 to 16 is a polyglycerin fatty acid ester, particularly preferably polyglyceryl 5 stearate. For example, a nonionic surfactant with an HLB value of 3 to 6 is a glycerin fatty acid ester, particularly preferably glyceryl stearate.

When using one or more nonionic surfactants selected from those with an HLB value of 8 to 16 and one or more nonionic surfactants selected from those with an HLB value of 3 to 6, it is preferable that the proportion of one or more nonionic surfactants selected from those with an HLB value of 8 to 16 relative to the total mass percent of nonionic surfactants is 30% to 90% by mass. Within this range, the crystalline structure of the α-gel is stable. When mixing two or more types with different HLB values as described above, higher alcohols may be used as needed. Higher alcohols are alcohols having hydrocarbon groups with 8 or more carbon atoms, and the hydrocarbon groups may be linear or branched. Particularly preferable is the use of one or more alcohols with 14 to 22 carbon atoms in combination.
In the nonionic surfactant of this disclosure, when using a nonionic surfactant with an HLB of 8 to 16 as another preferred embodiment, it is preferable to use a higher alcohol when not using one or more nonionic surfactants selected from those with an HLB of 3 to 6. By using such a high HLB nonionic surfactant and a higher alcohol, the bilayer structure constituting the α-gel is fixed, resulting in a high-strength bilayer and increased strength and stability of the formed oil droplets. The higher alcohol is an alcohol having a hydrocarbon group with 8 or more carbon atoms, and the hydrocarbon group may be linear or branched. Particularly preferred is a combination of one or more alcohols having 14 to 22 carbon atoms.
Examples of oils in this disclosure include hydrocarbons such as liquid paraffin and squalane, waxes such as jojoba oil and liquid lanolin, esters such as isopropyl myristate, glyceryl tri-2-ethylhexanoate, diglyceryl diisostearate, and trimethylolpropane tri-2-ethylhexanoate, fats and oils such as castor oil and macadamia nut oil, linear polysiloxanes such as dimethylpolysiloxane and methylphenylpolysiloxane, cyclic polysiloxanes such as octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, and silicone oils such as amino-modified silicones.
Examples of humectants in this disclosure include polyhydric alcohols and sugars, specifically propylene glycol, 1,3-butylene glycol, 1,3-propanediol, dipropylene glycol, 1,2-pentanediol, 1,2-hexanediol, isoprene glycol, diglycerin, methylpropanediol, glycerin, xylitol, sorbitol, maltitol, mannitol, erythritol, and the like.
When the composition of this disclosure contains a polyhydric alcohol, the polyhydric alcohol used as the solvent during the polymerization of polymer (A) may be used as is.
The humectant used in this disclosure may contain two or more humectants. For example, a mixture may be used which is a mixture of a divalent alcohol compound such as propylene glycol, 1,3-butylene glycol, 1,3-propanediol, dipropylene glycol, 1,2-pentanediol, 1,2-hexanediol, isoprene glycol, diglycerin, or methylpropanediol, and a trivalent or higher alcohol compound such as glycerin, xylitol, sorbitol, maltitol, mannitol, or erythritol. Propylene glycol, 1,3-butylene glycol, 1,3-propanediol, dipropylene glycol, 1,2-pentanediol, and 1,2-hexanediol are more preferred as the divalent alcohol compound, propylene glycol, 1,3-butylene glycol, 1,3-propanediol, and dipropylene glycol are even more preferred, and 1,3-butylene glycol is particularly preferred. Glycerin is more preferred as the trivalent or higher alcohol compound. By using a mixture of two or more humectants, improvements in usability and moisturizing properties can be expected. While the mixture may be added separately during the preparation of the cosmetic, it is also preferable to mix them beforehand.
Examples of mixtures containing two or more humectants include combinations of a divalent alcohol compound and a trivalent or higher alcohol compound. The mass ratio of the divalent alcohol compound to the trivalent or higher alcohol compound (mass of the divalent alcohol compound / mass of the trivalent or higher alcohol compound) may be 90.0/10.0 to 99.9/0.1, 95/5 to 99.7/0.3, 99.0/1.0 to 99.5/0.5, 99.0/1.0 to 99.4/0.6, or 99.1/0.9 to 99.3/0.7. Including a trivalent or higher alcohol compound within the above range can be expected to improve the feel and moisturizing effect.
Examples of mixtures containing two or more humectants include a combination of 1,3-butylene glycol and glycerin. The mass ratio of 1,3-butylene glycol to glycerin (mass of 1,3-butylene glycol / mass of glycerin) may be 90.0/10.0 to 99.9/0.1, 95/5 to 99.7/0.3, 99.0/1.0 to 99.5/0.5, 99.0/1.0 to 99.4/0.6, or 99.1/0.9 to 99.3/0.7. Including glycerin within the above range can be expected to improve usability and moisturizing properties.
Examples of colorants in this disclosure include inorganic pigments and natural pigments.
Examples of cooling agents in this disclosure include menthol, menthoxypropanediol, monomenthyl glyceryl ether, menthyl lactate, camphor, eugenol, mint oil, and peppermint oil.

<Method for producing polymer (A)>
The production of polymer (A) of the present invention is not particularly limited, but it can be produced by including a step of polymerizing monomer components (hereinafter also referred to as the "polymerization step"), and specific examples and preferred examples of monomer components are as described above.
The polymer (A) described above is preferably produced by polymerizing the monomer components in the presence of a polymerization initiator. That is, the polymerization step is preferably carried out in the presence of a polymerization initiator. When polymerizing the monomer components, a polymerization initiator can be used as appropriate depending on the polymerization method.

As the polymerization initiators mentioned above, commonly used ones can be used, for example, hydrogen peroxide; persulfates such as sodium persulfate and ammonium persulfate; dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(isobutyric acid)dimethyl, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionate] Suitable polymerization initiators include azo compounds such as [on-amidine]n hydrate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 1,1'-azobis(cyclohexane-1-carbonitride), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(2,4-dimethylvaleronitrile); and organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, and di-t-butyl peroxide. Of these polymerization initiators, azo compounds are preferred. The polymerization initiators are not limited to the examples given above. These polymerization initiators may be used individually or in combination of two or more types.
The amount of polymerization initiator used is not particularly limited as long as it is an amount that can start the polymerization of the monomer components, but is usually 0.01 to 50 parts by mass, preferably 0.05 to 30 parts by mass, and more preferably 0.05 to 20 parts by mass, per 100 parts by mass of the total monomer components.

The cationic group-containing monomer of this disclosure may be used as a quaternary ammonium salt quaternized with a quaternizing agent. The quaternizing agent for the cationic group-containing monomer is as described above. The amount of quaternizing agent used is preferably 0.1 to 1 mole per mole of cationic group-containing monomer.
Regarding the method of quaternizing cationic group-containing monomers, a post-addition method is also preferred, in which the quaternizing agent is added after polymerization of the polymer of the present invention. The amount of quaternizing agent used is preferably 0.1 to 1 mole per mole of cationic group-containing monomer.

In the polymerization method or process described above, suitable methods for adding monomer components and polymerization initiators to the reaction vessel include: a method in which all monomer components are placed in the reaction vessel and copolymerization is carried out by adding the polymerization initiator to the reaction vessel; a method in which a portion of the monomer components are placed in the reaction vessel and copolymerization is carried out by continuously or stepwise (preferably continuously) adding the polymerization initiator and the remaining monomer components to the reaction vessel; a method in which the polymerization solvent is placed in the reaction vessel and the entire amount of monomer components and polymerization initiator is added; and a method in which a portion of one of the monomers (for example, a cationic group-containing monomer) is placed in the reaction vessel and copolymerization is carried out by continuously adding the polymerization initiator and the remaining monomer components to the reaction vessel. Among these methods, copolymerization is preferred by sequentially adding the polymerization initiator and monomer components dropwise to the reaction vessel, as this can narrow (sharpen) the molecular weight distribution of the resulting polymer.

The copolymerization method described above can be carried out by methods such as solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, living polymerization, or graft polymerization, and is not particularly limited, but solution polymerization is preferred. In this case, the solvent that can be used is preferably water alone or a mixed solvent of water and a solvent. When water alone is used, it is preferable because the desolventing step can be omitted. The polymerization method or polymerization step described above can be carried out in batches or continuously. Furthermore, during copolymerization, known solvents can be used as needed, and are particularly suitable: water; monohydric alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butanol, and THF (tetrahydrofuran); polyhydric alcohols such as glycerin, (poly)ethylene glycol, propylene glycol, 1,3-butylene glycol (1,3-butanediol), and dipropylene glycol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, and n-heptane; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; amides such as dimethylformamide; and ethers such as diethyl ether and dioxane. These may be used individually or in combination of two or more. Among these, from the viewpoint of solubility of monomer components and the resulting polymer, it is preferable to use one or more solvents selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms. The above solvents are relatively inexpensive, and the production method of the present invention is economically superior. Furthermore, in the copolymerization method described above, polymerization may be carried out by adding a polyhydric alcohol solvent such as propylene glycol or ethylene glycol to water. By using the polyhydric alcohol solvent in combination with water, the solubility of the polymer can be increased, and soap-free polymerization can be more effectively suppressed. This can more effectively suppress the formation of polymers with poor water solubility and further improve the transparency of the solution. When using the polyhydric alcohol solvent in combination with water, the ratio of the polyhydric alcohol solvent to 100% by mass of water is preferably 0 to 200% by mass. The polymer production method of the present invention may use any chain transfer agent, pH adjuster, buffer, etc., as needed. The obtained polymer may be arbitrarily soluble in water or arbitrarily dispersed, but arbitrarily soluble in water is particularly preferred. The temperature during polymerization is not particularly limited, but is usually 50 to 120°C, and preferably 60 to 110°C. When the polymerization temperature is within the above range, there is a tendency for the amount of residual monomer components to decrease. Furthermore, the polymerization temperature does not need to be kept constant throughout the polymerization reaction. For example, polymerization may be started at room temperature, and the temperature may be raised to the set temperature at an appropriate time or rate, and then maintained at the set temperature. Alternatively, the polymerization temperature may be varied (increased or decreased) over time during the polymerization reaction, depending on the dropwise addition method of monomer components and initiators.

Furthermore, when polymerizing monomer components, it is preferable to stir the mixture as needed to ensure that the monomer components polymerize uniformly.
The polymerization time in the above polymerization is not particularly limited and can be set appropriately according to the progress of the polymerization reaction, but it is usually about 2 to 9 hours. In this invention, "polymerization time" refers to the time spent heating and stirring before dropping the monomer, the time spent adding the monomer, and the maturation time after dropping the monomer.
The pressure within the reaction system in the above polymerization can be normal pressure (atmospheric pressure), reduced pressure, or pressurized pressure, or a combination of these. The atmosphere within the reaction system can be either air or an inert atmosphere.

In the polymerization reaction system described above, the solid content concentration in the aqueous solution at the completion of the polymerization reaction (i.e., the concentration of polymerized monomer solids) is preferably 20% by mass or more, and more preferably 25 to 80% by mass. A high solid content concentration of 20% by mass or more at the completion of the polymerization reaction allows for high-concentration polymerization in a single step. Therefore, the concentration step, which was sometimes necessary in conventional manufacturing methods, can be omitted, enabling efficient production of an antibacterial agent containing polymers. Consequently, the manufacturing efficiency can be significantly increased, resulting in a substantial improvement in the productivity of the antibacterial agent of the present invention and a suppression of increases in manufacturing costs.

The polymer production method of the present invention may include a maturation step after all raw materials have been added, for the purpose of increasing the polymerization rate of the monomers. The maturation time is usually 1 to 240 minutes, preferably 1 to 180 minutes, and more preferably 1 to 120 minutes. If the maturation time is less than 1 minute, the maturation is insufficient and monomer components may remain, which can lead to problems such as toxicity and odor caused by the remaining monomers.
Furthermore, the preferred temperature of the polymer solution during the maturation process is within the same range as the polymerization temperature. Therefore, the temperature here may be maintained at a constant temperature (preferably the temperature at the time the dropping process is completed), or the temperature may be changed over time during maturation.
The method for producing the polymer of this disclosure may include, in addition to the polymerization step described above, other optional steps as needed. Examples of such optional steps include a maturation step, a concentration step, a purification step, a drying step, a dilution step, and so on.

<Method for manufacturing the composition>
The compositions of this disclosure include the step of adding an acid to the polymer (A) obtained by the above manufacturing method. Specific examples and preferred examples of the acid are as described above.
In the method for producing the composition of the present disclosure, the total amount of acid per mole of cationic group monomer of polymer (A) may be 1.50 mol% or less, preferably 1.40 mol% or less, more preferably 1.30 mol% or less, and even more preferably 1.20 mol% or less, from the viewpoint of solubility in water and storage stability when dissolved in water.
The compositions of this disclosure may also contain other additives as described above.

<Application>
The compositions disclosed herein are preferably used in cosmetic applications such as skin cosmetics, topical skin preparations, or hair cosmetics.
The above-mentioned skin cosmetics are not particularly limited, but examples include: skincare cosmetics such as lotions, creams, gels, emulsions, and serums; makeup cosmetics such as liquid foundations, primers, blushes, eyeshadows, mascaras, and lipsticks; cleansing cosmetics such as cleansing creams, facial cleansers, and liquid facial washes; cosmetics such as sunscreens (including quasi-drugs); and bath cosmetics such as bath additives. Topical skin preparations include topical medicines such as liniments, lotions, and ointments.
The above-mentioned hair care products are not particularly limited, but examples include shampoos, conditioners, treatments, waxes, sprays, gels, mists, etc.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".
<Weight average molecular weight (Mw) measurement>
Equipment: Tosoh Corporation EcoSEC HLC-8320GPC
Detector: Differential Refractometer (RI) Detector Column: TSKgel α-M, α-2500 (manufactured by Tosoh Corporation)
Column temperature: 40°C
Flow rate: 0.4mL/min
Injection volume: 20 μL (eluent preparation solution with a sample concentration of 0.4 wt%)
Calibration curve: GL Sciences polyethylene glycol eluent: 0.5 M acetic acid + 0.2 M sodium nitrate/acetonitrile = 50/50 (v/v)

<Compatibility>
A circle (○) indicates uniform mixing, and a cross (×) indicates non-uniform mixing. <Viscosity Measurement> A Type B viscometer (model: BMII) (manufactured by Toki Sangyo Co., Ltd.) was used, and measurements were taken under the following conditions: rotor No. 4, rotation speed 12 rpm, measurement time 60 seconds, and temperature 25°C.
<pH measurement>
The pH was measured using a HORIBA LAQUA pH/ION METER F-72. The measurement temperature was 25°C.
<Storage Stability> The product was stored for one month in incubators at room temperature, 5°C, and 50°C, and evaluated by five expert panelists.
<User Experience> Sensory evaluation was conducted by five expert panelists.
<Evaluation Method for Storage Stability and Usability> Five expert panelists conducted an absolute evaluation of storage stability and usability according to the evaluation criteria below. The average score of these five panelists was then determined according to the judgment criteria below. The judgment criteria were shared for both storage stability and usability.
<Evaluation Criteria> Storage Stability / Usability 3 points: No separation or creaming / Not sticky and moist 1 point: Slight separation or creaming / Slightly sticky 0 points: Separation or creaming / Sticky <Judgment Criteria>
○: 2.5 points or more △: 1.0 point or more but less than 2.5 points ×: Less than 1.0 point

<MIC (Minimum Inhibitory Concentration)>
An aqueous solution containing the copolymer was sequentially diluted twofold in Mueller-Hinton medium to prepare a series of copolymer-containing media. Then, 50 μL of each copolymer-containing medium was added to a 96-well polystyrene plate. Next, colonies of Escherichia coli (NBRC-3972), Staphylococcus aureus (NBRC-13276), or Pseudomonas aeruginosa (NBRC-13275), grown on Mueller-Hinton agar for 18 hours, were suspended in Butterfield buffer to prepare a bacterial suspension of approximately 10 × 10⁸ cells/mL. The prepared bacterial suspension was diluted in Mueller-Hinton medium to approximately 10 × 10⁶ cells/mL and added to the dilution series prepared above in 50 μL increments. After standing at 35°C for 20 hours, the minimum inhibitory concentration (ppm) of the antimicrobial agent in the culture medium where no bacteria were growing was determined as the minimum inhibitory concentration (MIC). The presence or absence of bacterial growth was determined by visual inspection of whether the turbidity was increasing. A MIC value of 300 ppm or less is preferable, 200 ppm or less is more preferable, 100 ppm or less is even more preferable, and 80 ppm or less is particularly preferable. An MIC value of 300 ppm or less is preferable because it prevents the amount of antimicrobial agent added to exert bacteriostatic effects from becoming too large.
<Preservative efficacy test>
The preservative efficacy tests of the compositions disclosed herein were conducted in accordance with the methods described in the Japanese Pharmacopoeia. The target bacteria used were Escherichia coli and Staphylococcus aureus. Bacterial survival rates were measured 4 hours, 3 days, and 7 days after inoculation.
Antimicrobial activity was determined as follows: ○ (antimicrobial activity present) if the bacterial survival rate after 4 hours was 1% or less of the inoculated bacterial count, and the bacterial count continued to decrease after 3 and 7 days; × (no antimicrobial activity) otherwise.

[Synthesis Example - Synthesis of Polymers Containing Cationic Groups]
<Synthesis Example 1>
In a glass separable flask equipped with a thermometer, reflux condenser, and stirrer, 29.4 g of pure water and 100.0 g of 1,3-butanediol (manufactured by KH Neochem Co., Ltd.) were charged and the mixture was heated to 90°C while stirring. Then, under stirring, monomer solution 1 consisting of 60.0 g of 2-(dimethylamino)ethyl methacrylate (N,N-dimethylaminoethyl methacrylate) (manufactured by Kyoeisha Chemical Co., Ltd., hereinafter referred to as DAM), monomer solution 2 consisting of 40.0 g of ethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., hereinafter referred to as EMA), and initiator aqueous solution consisting of 18.3 g of a 10% aqueous solution of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hereinafter referred to as V-50) were added dropwise from separate dropping nozzles to the polymerization reaction system maintained at a constant temperature of 80°C. Regarding the start time of dropwise addition, monomer solutions 1 and 2 and the initiator aqueous solution were added dropwise simultaneously. Monomer solution 1 was added dropwise for 180 minutes, monomer solution 2 for 170 minutes, and the initiator aqueous solution for 210 minutes. After all dropwise addition was complete, the reaction solution was kept at 80°C for another 30 minutes to mature and complete the polymerization. Then, 55.2 g of pure water and 205.5 g of 1,3-butanediol were added to obtain copolymer 1. The solid content of the obtained copolymer 1 was 19.7%, the pH was 9.0, and the weight-average molecular weight was 30,000.

[Manufacturing Example - Preparation of Copolymer-Containing Aqueous Solution]
<Manufacturing Example 1>
Citric acid was added to copolymer 1 to adjust the pH to 6, and the solution was prepared as an aqueous solution with a solid content of 2%.
<Manufacturing Example 2>
The preparation was the same as in Production Example 1, except that citric acid was replaced with lactic acid.
<Manufacturing Example 3>
The preparation was the same as in Production Example 1, except that the citric acid was replaced with phosphoric acid.
<Manufacturing Example 4>
The preparation was the same as in Production Example 1, except that citric acid was replaced with succinic acid.
<Manufacturing Example 5>
The preparation was the same as in Production Example 1, except that the citric acid was replaced with malic acid.
<Manufacturing Example 6>
The preparation was the same as in Production Example 1, except that the citric acid in Production Example 1 was replaced with etidronic acid.
<Manufacturing Example 7>
The preparation was the same as in Production Example 1, except that citric acid was replaced with ascorbic acid.
<Manufacturing Example 8>
The preparation was the same as in Production Example 1, except that the citric acid was replaced with mandelic acid.
<Manufacturing Example 9>
The preparation was the same as in Production Example 1, except that citric acid was replaced with glutamic acid.
<Manufacturing Example 10>
The preparation was the same as in Production Example 1, except that citric acid was replaced with aspartic acid.
<Manufacturing Example 11>
The preparation was the same as in Production Example 1, except that citric acid was replaced with tartaric acid.
<Comparative Manufacturing Example 1>
Deionized water was added to adjust the copolymer 1 to a solid content concentration of 2%.
<Comparative Manufacturing Example 2>
The preparation was the same as in Production Example 1, except that citric acid was replaced with phytic acid.
<Comparative Manufacturing Example 3>
The preparation was the same as in Production Example 1, except that the citric acid was replaced with serine.
<Comparative Manufacturing Example 4>
The preparation was the same as in Production Example 1, except that the citric acid was replaced with taurine.
For Production Examples 1 through 11 and Comparative Production Examples 1 through 4, we evaluated the storage stability, pH, and antimicrobial activity (MIC). The results are shown in Tables 1, 2, and 3.

As shown in Tables 1 and 2, it was found that manufacturing examples 1 through 11 exhibited excellent storage stability.
As shown in Table 3, it was found that manufacturing examples 1 through 11 exhibited excellent antibacterial properties.

[Manufacturing Example - Preparation of Copolymer-Containing Composition]
<Manufacturing Example 12>
(1) Mix 65.5 parts of deionized water, 5.0 parts of 1,3-butylene glycol-P (manufactured by KH Neochem Co., Ltd.), 8.0 parts of concentrated glycerin for cosmetics (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.), and 5.0 parts of Sunsoft α-C (manufactured by Taiyo Kagaku Co., Ltd.), and heat to 80°C ± 5°C while stirring until uniformly dissolved. (2) Mix 5.0 parts of olive squalane (manufactured by Fuyuho Alcohol Industry Co., Ltd.), 5.0 parts of CEH (manufactured by Fuyuho Alcohol Industry Co., Ltd.), 0.5 parts of KF-96A-100CS (manufactured by Shin-Etsu Chemical Co., Ltd.), and 1.0 part of TAISET 50-C (manufactured by Taiyo Kagaku Co., Ltd.), and heat to 80°C ± 5°C while stirring until uniformly dissolved. (3) While keeping (1) warm at 80°C ± 5°C, it was stirred at 5000 rpm using a homomixer (Labo Solution, manufactured by Primix Corporation), and (2) was added little by little to emulsify and make a homogeneous mixture, which was then cooled to 35°C. (4) 5.0 parts of an aqueous solution of copolymer 1, which was prepared by adding citric acid to copolymer 1 to adjust the pH to 6 and making an aqueous solution with a solid content of 2%, was mixed with (3) while stirring to obtain the O/W type emulsion of production example 12.

<Manufacturing Example 13>
Except for changing the citric acid added to copolymer 1 to lactic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 13.
<Manufacturing Example 14>
Except for changing the citric acid added to copolymer 1 to phosphoric acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 14.
<Manufacturing Example 15>
Except for changing the citric acid added to copolymer 1 to succinic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 15.
<Manufacturing Example 16>
Except for changing the citric acid added to copolymer 1 to malic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 16.
<Manufacturing Example 17>
Except for changing the citric acid added to copolymer 1 to etidronic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 17.
<Manufacturing Example 18>
Except for changing the citric acid added to copolymer 1 to ascorbic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 18.
<Manufacturing Example 19>
Except for changing the citric acid added to copolymer 1 to mandelic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 19.
<Manufacturing Example 20>
Except for changing the citric acid added to copolymer 1 to glutamic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 20.
<Manufacturing Example 21>
Except for changing the citric acid added to copolymer 1 to aspartic acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 21.
<Manufacturing Example 22>
Except for changing the citric acid added to copolymer 1 to tartaric acid, the preparation was carried out in the same manner as in Production Example 11 to obtain the O/W type emulsion of Production Example 22.
<Comparative Manufacturing Example 5>
The preparation was carried out in the same manner as in Production Example 11, except that the aqueous solution of copolymer 1, adjusted to a solid content concentration of 2%, was not added, and the O/W type emulsion of Comparative Production Example 5 was obtained.
For manufacturing examples 12 through 22 and comparative manufacturing example 5, we evaluated pH, viscosity, storage stability, usability, and antibacterial properties (storage efficacy test). The results are shown in Table 4.

As shown in Tables 4 and 5, Production Examples 11 to 20, which used polymers containing cationic groups, showed good compatibility when formulated as an O/W type emulsion and also exhibited excellent storage stability. In terms of usability, Production Examples 11 to 20 were as non-sticky and pleasant as Comparative Production Example 5.
Regarding the preservation efficacy test, it was found that production examples 11 to 20, which contained polymers with cationic groups, exhibited antibacterial activity against both E. coli and Staphylococcus aureus. No increase in bacterial count was observed in preservation efficacy tests at 3 and 7 days, indicating that the antibacterial activity was maintained over a long period. Since comparative production example 5 lacked antibacterial activity, it was concluded that polymers containing cationic groups impart antibacterial properties to O/W type emulsions, while also providing excellent storage stability and usability.

Regarding 1,3-butylene glycol and glycerin, mixtures were prepared with mass ratios of 1,3-butylene glycol to glycerin of 90:10, 95:5, 99:1, 99.1:0.9, and 99.4:0.6.
Using the above mixture of 1,3-butylene glycol and glycerin, Production Examples 23 to 27 were prepared as compositions with a polymer containing a cationic group, as shown in Table 6 below. In the table, BG is synonymous with 1,3-butylene glycol.

As shown in Table 6, Production Examples 23 to 27, which used a mixture of 1,3-butylene glycol and glycerin and a polymer containing cationic groups, showed good compatibility when formulated as an O/W type emulsion and exhibited excellent storage stability. Regarding usability, they were non-sticky and pleasant, comparable to Production Example 12 and Comparative Production Example 5.

<Raw materials used>
*1 Citric acid monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*2 Musashino Lactic Acid 50F (manufactured by Musashino Chemical Research Institute Co., Ltd.)
*3 Phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*4 Succinic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*5 DL-malic acid (Fujifilm Wako Pure Chemical Industries)
*6 Kilrest 210SD (manufactured by Kilrest Co., Ltd.)
*7 L(+)-ascorbic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*8 (±)-Mandelic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*9 L-glutamic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*10 L-aspartic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*11 L(+)-Tartaric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*12 50% phytic acid solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*13 L-serine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*14 Taurine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
*15 1,3-Butylene glycol-P (manufactured by KH Neochem)
*16 Concentrated glycerin for cosmetics (manufactured by Sakamoto Pharmaceutical Co., Ltd.)
*17 Sunsoft α-C (manufactured by Taiyo Kagaku Co., Ltd.)
*18-CEH (manufactured by Higher Alcohol Industry Co., Ltd.) *19-Olive Squalane (manufactured by Higher Alcohol Industry Co., Ltd.)
*20-KF-96A-100CS (manufactured by Shin-Etsu Chemical Co., Ltd.)
*21-TAISET 50-C (manufactured by Taiyo Kagaku Co., Ltd.)

Claims (3)

A composition comprising a polymer (A) having structural units derived from a cationic group-containing monomer and structural units derived from ethyl methacrylate, and one or more selected from inorganic phosphoric acid, citric acid, lactic acid, succinic acid, malic acid, etidronic acid, ascorbic acid, mandelic acid, glutamic acid, and aspartic acid, wherein the total amount of acid per mole of cationic group is 0.10 moles or more and 1.50 moles or less, wherein the proportion of structural units derived from the cationic group-containing monomer per 100 parts by mass of polymer (A) is 50% by mass or more and 94 % by mass or less, and the proportion of structural units derived from ethyl methacrylate is 5 % by mass or more and 50% by mass or less. A cosmetic composition using the composition described in claim 1. A method for producing a composition comprising the steps of polymerizing a cationic group-containing monomer and ethyl methacrylate, and adding one or more substances selected from inorganic phosphoric acid, citric acid, lactic acid, succinic acid, malic acid, etidronic acid, ascorbic acid, mandelic acid, glutamic acid, and aspartic acid to the polymer (A) obtained in the first step, wherein the total amount of acid per mole of cationic group is 0.10 moles or more and 1.50 moles or less, and the proportion of structural units derived from the cationic group-containing monomer per 100 parts by mass of the polymer (A) is 50% by mass or more and 94% by mass or less, and the proportion of structural units derived from ethyl methacrylate is 5% by mass or more and 50% by mass or less .