Regenerated collagen fiber treatment agent

Abstract

Provided is a regenerated collagen fiber treatment agent composition, wherein the treatment agent composition contains a specific component (A) and water and has a pH between 2 and 6, inclusive, and the regenerated collagen fibers include modified regenerated collagen fibers that contain a specific component (B).

Description

Regenerated collagen fiber treatment agent

[0001] The present invention relates to a treatment agent for regenerated collagen fibers.

[0002] Regenerated collagen fiber, a protein fiber, is suitable for use as a raw material for artificial hair because its properties are similar to those of human hair.

[0003] Modifiers have been studied for improving the texture, mechanical properties, etc. of fibers, hair, etc. For example, Patent Document 1 describes an elasticity-imparting agent that imparts elasticity to fibers, hair, etc. and modifies them, and that contains at least one selected from a gallic acid derivative with a specific structure, proanthocyanidin, chlorogenic acid and its derivatives, phloresin, and tannic acid.

[0004] (Patent Document 1) Japanese Patent Application Laid-Open No. 2000-314084

[0005] The present invention relates to the following: [1] A regenerated collagen fiber treatment composition, the treatment composition containing the following component (A) and water, and having a pH of 2 to 6, the regenerated collagen fiber comprising modified regenerated collagen fiber containing the following component (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, the number of phenolic hydroxyl groups being 2 or less, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+(A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C, and a number of phenolic hydroxyl groups of 2 or less, and further satisfying at least one of the following conditions (1) and (2): (2) a molecular weight of 1,500 or more; (B) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof. [2] A method for treating regenerated collagen fibers, the treatment method comprising a step of applying a regenerated collagen fiber treating composition to the regenerated collagen fibers, the treating composition containing the following component (A) and water, and having a pH of 2 to 6, the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B). (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following conditions (1) and (2) (excluding component (B)): (1) Al 3+ (1) A compound having a chelate stability constant log K with ions of 2 or less (2) A molecular weight of 1,500 or more (B) A copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof [3] A modified regenerated collagen fiber containing the following components (A) and (B): (A) A compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A chelate stability constant log K with ions of 2 or less; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof. [4] A head ornament product containing the modified regenerated collagen fiber described in [3]. Detailed Description of the Invention

[0006] The present inventors have found that treating regenerated collagen fibers with a modifying agent such as that disclosed in Patent Document 1 tends to decrease the modulus of elasticity in water, and that fiber treatment can cause damage and lead to a loss of fiber mass. Therefore, the present invention relates to a regenerated collagen fiber treatment composition that can improve the modulus of elasticity in water of regenerated collagen fibers and suppress loss of mass after treatment.

[0007] The present inventors have discovered that the above-mentioned problems can be solved by a treatment composition for regenerated collagen fibers, which contains specific modified regenerated collagen fibers and contains components that satisfy specific requirements. According to the present invention, it is possible to provide a treatment composition for regenerated collagen fibers that can improve the underwater elastic modulus of specific modified regenerated collagen fibers and suppress mass loss after treatment.

[0008] [Definition] As used herein, the term "elastic modulus in water of regenerated collagen fibers" refers to the tensile modulus of regenerated collagen fibers in water at 20° C. Specifically, the tensile modulus can be evaluated by the method described in the Examples.

[0009] [Regenerated collagen fiber treatment composition] The regenerated collagen fiber treatment composition of the present invention contains the following component (A) and water, and has a pH of 2 to 6, and the regenerated collagen fiber comprises a modified regenerated collagen fiber containing the following component (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+(1) A chelate stability constant log K with ions of 2 or less; (2) A molecular weight of 1,500 or more; (B) A copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof. In the following description, the regenerated collagen fiber treatment composition may be simply referred to as the "treatment composition (of the present invention)." The treatment composition of the present invention has the above-mentioned configuration, which can improve the modulus of elasticity in water of specific modified regenerated collagen fibers containing component (B) and suppress mass loss after treatment.

[0010] The reason why the treatment composition of the present invention exhibits the above-mentioned effects is unclear, but is presumed to be as follows. The modified regenerated collagen fibers that are the target of treatment with the treatment composition of the present invention contain structural moieties derived from component (B) and therefore have carboxy groups inside the fibers. When the proportion of undissociated carboxy groups (acid type) is high, the hydrophobicity of the fibers is improved compared to when the proportion of dissociated carboxy groups (carboxy ions) is high, and this is thought to result in an improved effect on the underwater elastic modulus.

[0011] The treatment composition of the present invention has a pH of 2 to 6, and component (A) contained in the treatment composition has a pKa value of 1 to 7. In a treatment composition with a pH of 2 to 6, component (A) with the above pKa value exhibits buffering ability. Therefore, treating modified regenerated collagen fibers with the treatment composition is thought to effectively lower the pH inside the fibers and increase the proportion of non-dissociated (acid-type) carboxy groups in the structural portion derived from component (B) inside the fibers. When component (A) has a solubility of 1 g or more in 100 g of water at 25°C at pH 3, a highly concentrated treatment composition with high buffering ability can be prepared, effectively improving the modulus of elasticity in water of the treated modified regenerated collagen fibers. Furthermore, when the number of phenolic hydroxyl groups in component (A) is 2 or less, it is thought that discoloration due to oxidation of the treated modified regenerated collagen fibers can be suppressed. Furthermore, component (A) is a compound that satisfies at least one of the above conditions (1) and (2) (excluding component (B)). Regarding requirement (1), Al of component (A) 3+ If the chelate stability constant log K with ions is 2 or less, the ability to form chelates with polyvalent metal ions contained in the regenerated collagen fibers is low, thereby suppressing the elution of polyvalent metal ions. It is believed that this effect can suppress the loss of mass of the modified regenerated collagen fibers after treatment. With regard to requirement (2), if the molecular weight of component (A) is 1500 or more, excessive penetration of component (A) into the interior of the fibers can be suppressed, and the elution of polyvalent metal ions due to chelation with the polyvalent metal ions in the fibers can be suppressed. It is believed that this can suppress the loss of mass of the modified regenerated collagen fibers after treatment. It should be noted that the mechanism of action of the present invention is not limited to the above.

[0012] <Component (A)> Component (A) is a compound that has a pKa value of 1 or more and 7 or less, has a solubility of 1 g or more in 100 g of water at 25°C at pH 3, has 2 or less phenolic hydroxyl groups, and further satisfies at least one of the following (1) and (2) (excluding component (B)). (1) Al 3+ (1) The chelate stability constant log K with ions is 2 or less. (2) The molecular weight is 1,500 or more.

[0013] (pKa) From the viewpoint of improving the modulus of elasticity in water of the modified regenerated collagen fibers, component (A) has a pKa value of 1 or more and 7 or less. Here, pKa refers to the acid dissociation index at 25°C. When component (A) has multiple dissociation stages, the pKa of any stage may be 1 or more and 7 or less. The acid dissociation index (pKa) is the common logarithm of the reciprocal of the acid dissociation constant (Ka) - logKa, and is a value described in the Chemical Handbook, Basics II, 4th Revised Edition, edited by the Chemical Society of Japan (published by Maruzen Co., Ltd.). If not described in this document, it can be determined using a commercially available pH meter (such as F-23, manufactured by HORIBA, Ltd., temperature: 25°C) by the method described in the document "FR Hartley, C. Burgess, and RM Alcock, "Solution Equilibria," John Wilery (1980)."

[0014] From the viewpoint of improving the modulus of elasticity in water of the modified regenerated collagen fibers, the pKa of component (A) is from 1 to 7, preferably from 1.5 or more, more preferably from 2.0 or more, even more preferably from 2.5 or more, and preferably from 6 to 5, more preferably from 4 to 4. The pKa of component (A) is from 1 to 7, preferably from 1.5 to 6, more preferably from 2.0 to 5, even more preferably from 2.5 to 4.

[0015] From the viewpoint of improving the elastic modulus in water of the modified regenerated collagen fibers, the pKa of component (A) is preferably −3.0 or more, more preferably −2.0 or more, even more preferably −1.0 or more, and preferably +3.0 or less, more preferably +2.0 or less, even more preferably +1.0 or less, relative to the pH value of the treatment composition of the present invention. The pKa of component (A) is preferably −3.0 or more and +3.0 or less, more preferably −2.0 or more and +2.0 or less, even more preferably −1.0 or more and +1.0 or less, relative to the pH value of the treatment composition.

[0016] (Water Solubility) Component (A) has a solubility of 1 g or more in 100 g of water at 25°C at pH 3. The solubility of component (A) in 100 g of water is preferably 2.5 g or more, more preferably 5 g or more, and even more preferably 10 g or more, from the viewpoints of making it possible to prepare a highly concentrated treatment composition with high buffering capacity and further improving the modulus of elasticity in water after treatment. The upper limit of the solubility is not particularly limited, but is preferably 100 g or less. Here, the solubility in 100 g of water at 25°C at pH 3 refers to the solubility in 100 g of water whose pH at 25°C has been adjusted to 3 using hydrochloric acid or sodium hydroxide as a pH adjuster.

[0017] (Number of phenolic hydroxyl groups) The number of phenolic hydroxyl groups in component (A) is 2 or less, preferably 1 or less, and more preferably 0, from the viewpoint of suppressing discoloration of the modified regenerated collagen fibers due to oxidation after treatment.

[0018] (Requirements (1) and (2)) Component (A) is a compound that further satisfies at least one of the following (1) and (2) (excluding component (B)). When component (A) satisfies at least one of the following (1) and (2), it is believed that chelate formation between component (A) and polyvalent metal ions contained in the regenerated collagen fibers can be suppressed, and mass loss of the modified regenerated collagen fibers after treatment can be suppressed. (1) Al 3+ (1) The chelate stability constant log K with ions is 2 or less. (2) The molecular weight is 1,500 or more.

[0019] [Requirement (1)] When component (A) satisfies requirement (1), Al of component (A) 3+ The chelate stability constant log K with the metal ion is 2 or less. n+ The chelating agent is L m- The resulting chelate compound was n-m and the molar concentrations of each are [M n+ ][L m- ][ML n-m ] and M n+ +L m- ⇔ML n-m The equilibrium constant for the chelate formation reaction is K: K = [MLn-m ] / ([M n+ ]×[L m- ]) is log K. 3+ The chelate stability constant log K with ions can be determined by potentiometric measurement (A. Albert & et al., "Ionic Constants" (Maruzen), p. 149 (1963)). 3+ The chelate stability constant log K with ions is preferably 1.8 or less, more preferably 1.6 or less, even more preferably 1.4 or less, still more preferably 1.2 or less, still more preferably 1.0 or less, and even more preferably 0.5 or less, from the viewpoint of further improving the effect of suppressing mass loss of the modified regenerated collagen fiber after treatment and from the viewpoint of suppressing thermal shrinkage.

[0020] [Requirement (2)] When component (A) satisfies requirement (2), the molecular weight of component (A) is 1,500 or more. The molecular weight of component (A) here refers to the weight-average molecular weight of component (A) when component (A) is a polymer. Furthermore, when component (A) is a salt, the molecular weight of component (A) does not include the molecular weight of the counter ion that forms the salt.

[0021] When component (A) satisfies requirement (2), the molecular weight of component (A) is preferably 2,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more, from the viewpoint of further improving the effect of suppressing mass loss after treatment and from the viewpoint of suppressing thermal shrinkage; and from the viewpoint of preventing excessive viscosity that makes application to fibers difficult, the molecular weight is preferably 100,000,000 or less, more preferably 50,000,000 or less, even more preferably 5,000,000 or less, still more preferably 2,000,000 or less, still more preferably 100,000 or less, still more preferably 50,000,000 or less, and still more preferably 10,000 or less. When component (A) satisfies requirement (2), the molecular weight of component (A) is preferably 2,000 to 100,000,000, more preferably 3,000 to 50,000,000, even more preferably 3,000 to 5,000,000, still more preferably 3,000 to 2,000,000, still more preferably 3,000 to 100,000, still more preferably 3,000 to 50,000, still more preferably 3,000 to 10,000, and still more preferably 4,000 to 10,000. When component (A) is a polymer, the weight average molecular weight of component (A) refers to the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0022] From the viewpoint of improving the elastic modulus of the modified regenerated collagen fibers in water, component (A) preferably contains a compound having an acidic group, more preferably a compound having one or more acidic groups selected from the group consisting of a carboxy group, a sulfate group, a sulfonate group, and a phosphate group, even more preferably a compound having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group, and even more preferably a compound having a carboxy group. At least a portion of the acidic groups in the compound may be in the form of a salt. The salt preferably contains an ammonium salt or a metal salt, more preferably an ammonium salt, or one or more metal salts selected from the group consisting of alkali metals, alkaline earth metals, and transition metals, more preferably an ammonium salt, or one or more metal salts selected from the group consisting of potassium, sodium, and calcium, even more preferably an ammonium salt, or one or more metal salts selected from the group consisting of sodium and calcium, and even more preferably a sodium salt.

[0023] The number of acidic groups in component (A) may be at least 1. When component (A) is a compound having a molecular weight of less than 1,500, the number of acidic groups in component (A) is preferably at least 1, and preferably at most 50, more preferably at most 20, even more preferably at most 10, and still more preferably at most 4. That is, the number is preferably at least 1 and at most 50, more preferably at least 1 and at most 20, even more preferably at least 1 and at most 10, and still more preferably at least 1 and at most 4.

[0024] From the viewpoints of improving the modulus of elasticity of the modified regenerated collagen fibers in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, component (A) preferably contains one or more compounds selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having an acidic group and having a molecular weight of less than 1,500.

[0025] [Surfactant] The surfactant used as component (A) preferably contains one or more surfactants selected from the group consisting of anionic surfactants and amphoteric surfactants that satisfy the above-mentioned (1). Examples of the anionic surfactant include sulfate ester-type anionic surfactants such as alkyl or alkenyl sulfates and alkyl or alkenyl ether sulfates; carboxylic acid-type anionic surfactants such as saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, and N-acylamino acid salts; sulfonic acid-type anionic surfactants such as alkyl sulfosuccinates, alkyl sulfonates, α-olefin sulfonates, internal olefin sulfonates, alkyl benzene sulfonates, α-sulfofatty acid methyl ester salts, and acyl methyl taurine salts; and phosphate ester-type anionic surfactants such as alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkyl phenyl ether phosphates. These surfactants may be used alone or in combination of two or more.

[0026] The alkyl or alkenyl group and the fatty acid in the anionic surfactant preferably have 8 or more carbon atoms, and preferably 22 or less carbon atoms, more preferably 18 or less carbon atoms, even more preferably 14 or less carbon atoms, and still more preferably 12 or less carbon atoms. That is, the carbon number is preferably 8 to 22, more preferably 8 to 18, even more preferably 8 to 14, and still more preferably 8 to 12 carbon atoms.

[0027] Among the above, from the viewpoints of improving the modulus of elasticity of the modified regenerated collagen fibers in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the anionic surfactant preferably comprises one or more selected from the group consisting of sulfate ester-type anionic surfactants and carboxylic acid-type anionic surfactants, more preferably one or more selected from the group consisting of alkyl or alkenyl sulfates, alkyl or alkenyl ether sulfates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, and N-acylamino acid salts, and even more preferably one or more selected from the group consisting of alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, and N-acylamino acid salts.

[0028] Among the anionic surfactants preferred for use as component (A), alkyl sulfates include sodium lauryl sulfate and ammonium lauryl sulfate, alkyl ether sulfates include polyoxyethylene lauryl ether sulfates such as sodium laureth sulfate, alkyl ether carboxylates include polyoxyethylene lauryl ether acetate, and N-acylamino acid salts include sodium N-lauroylmethylalanine.

[0029] Examples of amphoteric surfactants that satisfy the above (1) include amine oxide-type amphoteric surfactants such as alkyldimethylamine oxide and fatty acid amidopropyldimethylamine oxide; carboxybetaine-type amphoteric surfactants such as alkyldimethylaminoacetic acid betaine and fatty acid amidopropyl betaine; sulfobetaine-type amphoteric surfactants such as N-alkyl-N,N-dimethyl-N-sulfopropylammonium sulfobetaine, alkyl-N,N-dimethyl-N-(2-hydroxysulfopropyl)ammonium sulfobetaine, and N-alkanoylaminopropyl-N,N-dimethyl-N-(2-hydroxysulfopropyl)ammonium sulfobetaine; 2-alkylimidazoline-type amphoteric surfactants such as 2-alkyl-N-carboxymethylimidazolinium betaine and 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine; and amino acid-type amphoteric surfactants such as N-alkyl-β-aminopropionic acid and salts thereof and alkyl (or dialkyl)diethylenetriaminoacetic acid and salts thereof. These may be used alone or in combination of two or more.

[0030] Among the above, from the viewpoints of improving the underwater elastic modulus of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the amphoteric surfactant preferably comprises one or more selected from the group consisting of amine oxide amphoteric surfactants, carboxybetaine amphoteric surfactants, and sulfobetaine amphoteric surfactants, more preferably a carboxybetaine amphoteric surfactant, and even more preferably fatty acid amidopropyl betaine. Fatty acid amidopropyl betaines preferably include those having an acyl group having from 8 to 22 carbon atoms, more preferably from 10 to 18 carbon atoms. Specific examples include lauric acid amidopropyl betaine (lauramidopropyl betaine), palm kernel oil fatty acid amidopropyl betaine, coconut oil fatty acid amidopropyl betaine (cocamidopropyl betaine), etc., and preferably lauric acid amidopropyl betaine (lauramidopropyl betaine).

[0031] Among the above, from the viewpoints of improving the modulus of elasticity of the modified regenerated collagen fibers in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the surfactant used as component (A) preferably satisfies the above (1) and includes at least one surfactant selected from the group consisting of sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, amine oxide-type amphoteric surfactants, carboxybetaine-type amphoteric surfactants, and sulfobetaine-type amphoteric surfactants, and more preferably alkyl or alkenyl sulfates, alkyl or alkenyl ether sulfates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, N-acylamino acid salts, and carboxybetaine-type amphoteric surfactants. more preferably, it contains at least one selected from the group consisting of alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, and fatty acid amidopropyl betaines; and even more preferably, it contains at least one selected from the group consisting of sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether acetate, sodium N-lauroylmethylalanine, lauric acid amidopropyl betaine [lauramidopropyl betaine], palm kernel oil fatty acid amidopropyl betaine, and coconut oil fatty acid amidopropyl betaine [cocamidopropyl betaine].

[0032] [Polymer] The polymer used as component (A) preferably contains at least one polymer selected from the group consisting of anionic polymers and amphoteric polymers that satisfy the above-mentioned condition (2), provided that the polymer is a polymer other than component (B).

[0033] The anionic polymer used as component (A) preferably comprises one or more selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid and anionic polysaccharides. At least a portion of the anionic groups in the anionic polymer may be in the form of a salt. Examples of anionic vinyl polymers containing structural units derived from (meth)acrylic acid include (meth)acrylic acid homopolymers and anionic (meth)acrylic acid copolymers. The anionic (meth)acrylic acid copolymer may be a crosspolymer.

[0034] Examples of the (meth)acrylic acid homopolymer include polyacrylic acid, polymethacrylic acid, etc. The weight-average molecular weight of the (meth)acrylic acid homopolymer is preferably 3,000 to 50,000, more preferably 3,000 to 10,000, and even more preferably 4,000 to 10,000, from the viewpoint of improving the underwater elastic modulus of the modified regenerated collagen fiber and improving the effect of suppressing mass loss after treatment.

[0035] Examples of the anionic (meth)acrylic acid copolymer include (meth)acrylic acid / maleic acid copolymer, (meth)acrylic acid / itaconic acid copolymer, (meth)acrylic acid / fumaric acid copolymer, (meth)acrylic acid / vinyl acetate copolymer, (meth)acrylic acid / (meth)acrylic acid alkyl ester copolymer, (meth)acrylic acid / 2-hydroxyethyl methacrylate copolymer, acrylic acid / acrylic acid alkyl ester / (N-alkyl)acrylamide copolymer, carboxyvinyl polymer, (acrylates / alkyl acrylate (C10-30)) crosspolymer, (sodium acrylate / acryloyldimethyltaurine / dimethylacrylamide) crosspolymer, and acrylates crosspolymer-4.

[0036] Examples of anionic polysaccharides used as component (A) include polysaccharides having a carboxy group (hyaluronic acid, alginic acid, pectinic acid, carboxymethylcellulose, xanthan gum, etc.) and polysaccharide sulfates (carrageenan, keratan sulfate, dermatan sulfate, sulfated starch, heparin, heparan sulfate), and one or more of these can be used. Among these, from the viewpoints of improving the modulus of elasticity in water of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the anionic polysaccharide preferably includes one or more selected from the group consisting of carboxymethylcellulose, xanthan gum, and carrageenan, and more preferably includes xanthan gum.

[0037] Among the above, from the viewpoints of improving the modulus of elasticity in water of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the anionic polymer used as component (A) preferably contains one or more selected from the group consisting of polyacrylic acid and anionic polysaccharides, more preferably contains one or more selected from the group consisting of polyacrylic acid, carboxymethylcellulose, xanthan gum, and carrageenan, and even more preferably contains polyacrylic acid.

[0038] Examples of the amphoteric polymer used as component (A) include methacryloylethyldimethylbetaine, methacryloylethyltrimethylammonium chloride, and methoxypolyethylene glycol methacrylate copolymer (Polyquaternium-49), methacryloylethyldimethylbetaine, methacryloylethyltrimethylammonium chloride, and 2-hydroxyethyl methacrylate copolymer (Polyquaternium-48), vinylpyrrolidone and N,N-dimethylaminoethyl diethyl methacrylate sulfate copolymer (Polyquaternium-11), and N,N-dimethylaminoethyl diethyl methacrylate sulfate and N,N-dimethylacrylic acid copolymer. Examples of such copolymers include acrylic acid, methyl acrylate, and methacrylamidopropyltrimethylammonium chloride (Polyquaternium-52), acrylic acid, and polyethylene glycol dimethacrylate copolymer (Polyquaternium-22), acrylic acid, dimethyldiallylammonium chloride, and acrylamide copolymer (Polyquaternium-39), acrylic acid, methyl acrylate, and methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), and acrylic acid, acrylamide, and methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53). These copolymers may be used alone or in combination of two or more.

[0039] Among the above, from the viewpoints of improving the modulus of elasticity in water of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the amphoteric polymer preferably contains one or more members selected from the group consisting of structural units derived from (meth)acrylic acid and betaine groups, more preferably contains a structural unit derived from (meth)acrylic acid, even more preferably contains one or more members selected from the group consisting of dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), and acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), and even more preferably contains acrylic acid-dimethyldiallylammonium chloride-acrylamide copolymer (Polyquaternium-39).

[0040] Among the above, the polymer used as component (A) preferably satisfies the above (2) from the viewpoints of improving the modulus of elasticity in water of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, and contains at least one polymer selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid, anionic polysaccharides, amphoteric polymers containing structural units derived from (meth)acrylic acid, and amphoteric polymers containing a betaine group, more preferably at least one polymer selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid, anionic polysaccharides, and amphoteric polymers containing structural units derived from (meth)acrylic acid, and even more preferably polyacrylic acid, carboxymethyl cellulose, xanthan gum, or the like. The polyacrylic acid may contain at least one selected from the group consisting of gum, carrageenan, dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), and acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), and more preferably at least one selected from the group consisting of polyacrylic acid, xanthan gum, and acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39). The polyacrylic acid preferably has a weight-average molecular weight of 3,000 to 50,000, more preferably 3,000 to 10,000, and even more preferably 4,000 to 10,000.

[0041] [Carboxylic acid compounds with a molecular weight of less than 1,500 (excluding surfactants)] Examples of the carboxylic acid compound include 2-pyrrolidone-5-carboxylic acid, pyruvic acid, proline, serine, glycine, leucine, arginine, glutamic acid, and histidine, and one or more of these can be used in combination. Among these, from the viewpoints of improving the modulus of elasticity in water of the modified regenerated collagen fiber, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, it is preferable to use one or more compounds selected from the group consisting of 2-pyrrolidone-5-carboxylic acid and pyruvic acid.

[0042] The component (A) can be used alone or in combination of two or more. Among the above, from the viewpoints of improving the modulus of elasticity of the modified regenerated collagen fibers in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, component (A) preferably contains one or more compounds selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having one or more acidic groups selected from the group consisting of carboxy groups and sulfate groups, more preferably one or more compounds selected from the group consisting of surfactants satisfying (1), polymers satisfying (2), and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1500 that satisfy (1), even more preferably one or more compounds selected from the group consisting of alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, fatty acid amidopropyl betaine, anionic vinyl polymers containing structural units derived from (meth)acrylic acid, anionic polysaccharides, amphoteric polymers containing structural units derived from (meth)acrylic acid, amphoteric polymers containing a betaine group, and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1500, and even more preferably sodium lauryl sulfate. sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium N-lauroylmethylalanine, lauric acid amidopropyl betaine [lauramidopropyl betaine], palm kernel oil fatty acid amidopropyl betaine, coconut oil fatty acid amidopropyl betaine [cocamidopropyl betaine], polyacrylic acid, carboxymethylcellulose, xanthan gum, carrageenan, dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid, and even more preferably sodium lauryl sulfate, ammonium lauryl sulfate,It contains one or more selected from the group consisting of sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, N-lauroylmethylalanine sodium, lauric acid amidopropyl betaine, polyacrylic acid, xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid, and even more preferably contains one or more selected from the group consisting of polyoxyethylene (3) lauryl ether sodium sulfate, polyoxyethylene (10) lauryl ether acetate, N-lauroylmethylalanine sodium, lauric acid amidopropyl betaine, polyacrylic acid (molecular weight 5000), polyacrylic acid (molecular weight 25000), xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid.

[0043] <Content of Component (A)> From the viewpoints of improving the underwater elastic modulus of the modified regenerated collagen fibers, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, the content of component (A) in the treatment composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, still more preferably 0.5% by mass or more, still more preferably 1.0% by mass or more, still more preferably 1.5% by mass or more, and still more preferably 2.0% by mass or more. Also, it is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less, still more preferably 20% by mass or less, still more preferably 15% by mass or less, still more preferably 10% by mass or less, and still more preferably 5% by mass or less. The content of component (A) in the treatment composition is preferably 0.01% by mass or more and 40% by mass or less, more preferably 0.05% by mass or more and 30% by mass or less, even more preferably 0.1% by mass or more and 25% by mass or less, still more preferably 0.2% by mass or more and 20% by mass or less, even more preferably 0.5% by mass or more and 20% by mass or less, still more preferably 1.0% by mass or more and 20% by mass or less, still more preferably 1.5% by mass or more and 15% by mass or less, and still more preferably 2.0% by mass or more and 10% by mass or less. The content of component (A) in the treatment composition may also be 1.5% by mass or more and 5% by mass or less. When component (A) contains a polymer, the content of component (A) in the treatment composition is even more preferably 5% by mass or more and even more preferably 7.5% by mass or more, from the viewpoints of improving the underwater elastic modulus of the modified regenerated collagen fibers, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage. When component (A) contains a polymer, the content of component (A) in the treatment composition is even more preferably 5% by mass or more and 10% by mass or less, and even more preferably 7.5% by mass or more and 10% by mass or less.

[0044] <Water> The water used in the treatment composition of the present invention is not particularly limited, and for example, ion-exchanged water, pure water, distilled water, etc. can be used. The water content in the treatment composition is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and preferably 99.99% by mass or less, even more preferably 97% by mass or less. The water content in the treatment composition may be the remainder of component (A). That is, the water content in the treatment composition is preferably 60% by mass or more and 99.99% by mass or less, more preferably 70% by mass or more and 97% by mass or less, even more preferably 75% by mass or more and 97% by mass or less, still more preferably 80% by mass or more and 97% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

[0045] <Other Components> In addition to the above-described components, the treatment composition may contain an antioxidant, a fragrance, a preservative, a pH adjuster, a cationic or nonionic surfactant, a cationic or nonionic polymer, a higher alcohol, a silicone, etc. Preferably, the treatment composition contains, in addition to the above-described components, a cationic or nonionic surfactant, a cationic or nonionic polymer, and a higher alcohol.

[0046] (Cationic Surfactants) Examples of cationic surfactants include (i) alkyltrimethylammonium salts, (ii) alkoxyalkyltrimethylammonium salts, (iii) dialkyldimethylammonium salts, (iv) alkylamidoalkyltrimethylammonium salts, (v) alkyldimethylamines and salts thereof, (vi) alkoxyalkyldimethylamines and salts thereof, and (vii) alkylamidoalkyldimethylamines and salts thereof.

[0047] (i) Examples of alkyltrimethylammonium salts include alkyltrimethylammonium salts having an alkyl group preferably having from 12 to 22 carbon atoms, more preferably from 16 to 20 carbon atoms. Specific examples include cetyltrimethylammonium chloride (cetrimonium chloride), stearyltrimethylammonium chloride (steartrimonium chloride), and behenyltrimethylammonium chloride.

[0048] (ii) Examples of alkoxyalkyltrimethylammonium salts include alkoxyalkyltrimethylammonium salts having an alkoxy group preferably having from 12 to 22 carbon atoms, more preferably from 16 to 20 carbon atoms. Specific examples include stearoxypropyltrimethylammonium chloride, stearoxyethyltrimethylammonium chloride, and stearoxyhydroxypropyltrimethylammonium chloride.

[0049] (iii) Examples of dialkyldimethylammonium salts include dialkyldimethylammonium salts having preferably an alkyl group having from 12 to 22 carbon atoms, more preferably from 16 to 20 carbon atoms. Specific examples include distearyldimethylammonium chloride, dialkyl (C12-15) dimethylammonium salt, dicetyl (C16) dimethylammonium salt, dialkyl (C12-18) dimethylammonium salt, didecyl (C10) dimethylammonium salt, dilauryl (C12) dimethylammonium salt, dicocodimethylammonium salt (C8-16), dimyristyl (C14) dimethylammonium salt, distearyl (C18) dimethylammonium salt, dialachyl (C20) dimethylammonium salt, dibehenyl (C22) dimethylammonium salt, and stearyl lauryl dimethylammonium salt. Commercially available products include the "Cortamin" series manufactured by Kao Corporation, VARISOFT 432PPG (dicetyldimonium chloride) manufactured by EVONIK, rquad PC 2C-75 (dicoccodimonium chloride) manufactured by AkzoNobel, and Lipocard 2C-75 (diacetyldimethylammonium chloride) manufactured by Lion Specialty Chemicals.

[0050] (iv) Examples of alkylamidoalkyltrimethylammonium salts include alkylamidoalkyltrimethylammonium salts having preferably an alkyl group having 11 to 21 carbon atoms, more preferably 13 to 19 carbon atoms, and specific examples thereof include palmitamidopropyltrimethylammonium chloride (palmitamidopropyltrimonium chloride).

[0051] (v) Alkyldimethylamine, (vi) alkoxyalkyldimethylamine, and (vii) alkylamidoalkyldimethylamine react with an acid to form a tertiary amine salt, which becomes a cationic surfactant.

[0052] The alkyl group in (v) alkyldimethylamines and salts thereof, and (vi) alkoxyalkyldimethylamines and salts thereof is preferably an alkyl group having from 12 to 22 carbon atoms, more preferably from 16 to 20 carbon atoms. The alkyl group in (vii) alkylamidoalkyldimethylamines and salts thereof is preferably an alkyl group having from 11 to 21 carbon atoms, more preferably from 15 to 19 carbon atoms.

[0053] (v) Examples of alkyldimethylamines and salts thereof include N,N-dimethylbehenylamine, N,N-dimethylstearylamine, and organic acid salts thereof, with N,N-dimethylbehenylamine lactate and N,N-dimethylstearylamine glycolate being preferred.

[0054] (vi) Examples of alkoxyalkyldimethylamines and salts thereof include N,N-dimethyl-3-hexadecyloxypropylamine, N,N-dimethyl-3-octadecyloxypropylamine, and organic acid salts thereof, and N,N-dimethyl-3-hexadecyloxypropylamine or a salt thereof, and N,N-dimethyl-3-octadecyloxypropylamine (stearoxypropyldimethylamine) or a salt thereof are preferred.

[0055] (vii) Examples of alkylamidoalkyldimethylamines and salts thereof include N-[3-(dimethylamino)propyl]docosanamide, N-[3-(dimethylamino)propyl]stearamide, and organic acid salts thereof, and preferred are the lactate salt of N-[3-(dimethylamino)propyl]docosanamide and the glycolate salt of N-[3-(dimethylamino)propyl]stearamide.

[0056] Other cationic surfactants include the quaternary ammonium salts described in JP-A-2019-34927.

[0057] (Nonionic Surfactants) Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene fatty acid esters, alkyl glucosides, alkyl polyglycosides, alkyl glyceryl ethers, alkenyl glyceryl ethers, higher fatty acid sucrose esters, glycerin fatty acid esters, polyglycerin fatty acid esters, polyoxyethylene hydrogenated castor oil, alkyl saccharides, alkylamine oxides, alkylamidoamine oxides, fatty acid alkanolamides, polyoxyalkylene fatty acid alkanolamides, and (poly)ethylene glycol fatty acid esters.

[0058] Examples of sorbitan fatty acid esters include sorbitan monooleate (HLB: 5.7), sorbitan monostearate (HLB: 5.7), sorbitan monopalmitate (HLB: 6.6), sorbitan distearate (HLB: 3.9), sorbitan dipalmitate (HLB: 5.8), sorbitan tristearate (HLB: 2.1), and sorbitan tripalmitate (HLB: 5.0). Examples of polyoxyalkylene sorbitan fatty acid esters include polyoxyethylene sorbitan fatty acid esters.

[0059] The polyoxyalkylene alkyl ether preferably includes a polyoxyethylene alkyl ether or polyoxypropylene alkyl ether having an alkyl group having from 8 to 22 carbon atoms, more preferably from 8 to 18 carbon atoms, and even more preferably from 8 to 12 carbon atoms, such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxypropylene butyl ether, polypropylene glycol caprylyl ether, etc. Specific examples of commercially available products include "Emulgen 103" (Laureth-3: PEG-3 Lauryl Ether), "Emulgen 116" (Laureth-16: PEG-16 Lauryl Ether), and "Kao Sofcare GP-1" (PPG-3 Caprylyl Ether), all manufactured by Kao Corporation.

[0060] The alkyl glucoside preferably has an alkyl group having 8 to 22 carbon atoms, more preferably 8 to 18 carbon atoms, and even more preferably 8 to 12 carbon atoms. Specific examples include "Mydol 10" (decyl glucoside) manufactured by Kao Corporation, and "Plantaren 2000 N UP" (decyl glucoside) and "Plantacare 818 UP" (coco glucoside) manufactured by BASF.

[0061] The alkyl glyceryl ether is preferably an alkyl glyceryl ether having an alkyl group having from 8 to 22 carbon atoms, more preferably from 8 to 18 carbon atoms, and even more preferably from 8 to 12 carbon atoms. Specific examples thereof include 2-ethylhexyl glyceryl ether, isostearyl glyceryl ether, and "Penetol GE-ID" (isodecyl glyceryl ether) manufactured by Kao Corporation.

[0062] (Cationic Polymer) Examples of cationic polymers include cationic polygalactomannans such as cationic guar gum, cationic tara gum, and cationic locust bean gum; cationic cellulose; cationic hydroxyalkyl celluloses such as cationic hydroxyethyl cellulose and cationic hydroxypropyl cellulose; cationic starch; cationic polyvinyl alcohol; and other quaternary dialkylaminoalkyl (meth)acrylate polymers; diallyl quaternary ammonium salt polymers such as polydiallyldimethylammonium chloride and diallyldimethylammonium chloride / acrylamide copolymer; and vinylimidazolium trichloride / vinylpyrrolidone copolymer. Polymers such as vinylpyrrolidone / alkylaminoalkyl (meth)acrylate copolymers; vinylpyrrolidone / alkylaminoalkyl (meth)acrylate / vinylcaprolactam copolymers; vinylpyrrolidone / (meth)acrylamidopropyl trimethylammonium chloride copolymers; alkylacrylamide / (meth)acrylate / alkylaminoalkylacrylamide / polyethylene glycol (meth)acrylate copolymers; diallyldimethylammonium chloride-acrylamide copolymers (Polyquaternium-7); and cationic polymers described in JP-A-53-139734 and JP-A-60-36407.

[0063] Examples of commercially available cationic polymers include the following: (Cationized guar gum) JAGUAR Excel, JAGUAR C-17, JAGUAR C-14-S (all manufactured by Solvay (Novecare)), etc. (Cationized tara gum) Catinal CTR-100 (manufactured by Toho Chemical Industry Co., Ltd.), etc. (Cationized locust bean gum) Catinal CLB-100 (manufactured by Toho Chemical Industry Co., Ltd.), etc. (Cationized hydroxyethyl cellulose) Polyquaternium-10 (o-[2-hydroxy-3-(trimethylammonio)propyl]hydroxyethyl cellulose chloride): UCARE POLYMER JR-30M, UCARE POLYMER JR-400 (both manufactured by The Dow Chemical Company), Poise C-60H, Poise C-150L (both manufactured by Kao Corporation), etc. Polyquaternium-67: SoftCAT (manufactured by The Dow Chemical Company), etc. (Cationized hydroxypropyl cellulose) Softcare C-HP2W (Kao Corporation) etc. (cationized polyvinyl alcohol) Gohsenex K-434 (Nippon Synthetic Chemical Industry Co., Ltd.), CM318 (Kuraray Co., Ltd.) etc. (polydiallyldimethylammonium chloride) Polyquaternium-6: Mercoat 100 (Lubrizol) etc. (diallyldimethylammonium chloride / acrylamide copolymer) Polyquaternium-7: Mercoat 550 (Lubrizol) etc.

[0064] (Nonionic Polymer) Examples of nonionic polymers include water-soluble polysaccharides such as starch, cellulose, guar gum, tara gum, locust bean gum, and glucomannan; hydroxyalkylated water-soluble polysaccharides such as hydroxyethyl cellulose and hydroxypropyl cellulose; polyalkylene glycols such as polyethylene glycol and polyethylene glycol-polypropylene glycol copolymer; and polyvinyl alcohol.

[0065] (Higher Alcohol) The higher alcohol is preferably an aliphatic primary alcohol having from 12 to 22 carbon atoms, such as cetyl alcohol, oleyl alcohol, stearyl alcohol, isostearyl alcohol, 2-octyldodecanol, myristyl alcohol, behenyl alcohol, cetostearyl alcohol, etc., and one or more of these may be used.

[0066] <pH> The pH of the treatment composition is from 2 to 6 in terms of improving the underwater elastic modulus of the modified regenerated collagen fibers, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage. From the viewpoint of further improving the underwater elastic modulus of the modified regenerated collagen fibers, it is preferably 5.5 or less, more preferably 5.0 or less, even more preferably 4.5 or less, and even more preferably 4.0 or less. The pH of the treatment composition is from 2 to 6 in terms of further improving the underwater elastic modulus of the modified regenerated collagen fibers, it is preferably 2 to 5.5 or less, more preferably 2 to 5.0 or less, even more preferably 2 to 4.5 or less, and even more preferably 2 to 4.0 or less. From the viewpoint of further improving the effect of suppressing mass loss after treatment and suppressing thermal shrinkage, the pH of the treatment composition is preferably 3.0 or more, more preferably 3.5 or more, even more preferably 4.0 or more, and is 6 or less, preferably 5.5 or less. From the viewpoint of further improving the effect of suppressing mass loss after treatment and suppressing thermal shrinkage, the pH of the treatment composition is preferably 3.0 or more and 6.0 or less, more preferably 3.5 or more and 6.0 or less, even more preferably 4.0 or more and 6.0 or less, and still more preferably 4.0 or more and 5.5 or less. The pH of the treatment composition is a value at 25°C, and can be measured specifically by the method described in the examples.

[0067] <Form, Production Method> The form of the treatment composition is not particularly limited, and can be liquid, mist, paste, cream, gel, foam, spray, wax, or other formulations depending on the product form, with liquid being preferred. The treatment composition of the present invention can be used for any of in-bath treatments (types that are applied to fibers for headwear and then rinsed off) such as pre-shampoo treatments, shampoos, hair rinses, hair conditioners, hair treatments, hair packs, and after-shampoo treatments; leave-in treatments (types that are applied to fibers for headwear and then do not rinse off) such as non-aerosol foams, aerosol foams, hair gels, hair mousses, hair mist, hair lotions, hair oils, hair creams, hair milks, hair straighteners, and styling agents; and hair colorants such as temporary hair dyes, semi-permanent hair dyes, and permanent hair dyes. The treatment composition can be produced according to conventional methods.

[0068] <Modified Regenerated Collagen Fiber> The regenerated collagen fiber to be treated with the treatment composition of the present invention includes modified regenerated collagen fiber containing the following component (B): (B) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof

[0069] (Component (B)) Component (B) is a modifier for regenerated collagen fibers. The regenerated collagen fibers to be modified by component (B) will be described later. Component (B) is a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, and is a copolymer or salt thereof having an acid value of 100 mg KOH / g or more and a weight-average molecular weight of 1,500 to 15,000. The structural units derived from the unsaturated monomer having a carboxy group in component (B) may be derived from an unsaturated monocarboxylic acid or an unsaturated dicarboxylic acid, or a combination thereof. Specific examples of unsaturated monomers having a carboxy group include unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, oleic acid, and cyclopentenyl acetic acid. Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and methylene succinic acid. Alternatively, an unsaturated dicarboxylic acid anhydride may be used as the unsaturated monomer having a carboxy group, and may be used in the acid form by hydrolysis with an alkali or the like. Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride and citraconic anhydride. The unsaturated monomer having a carboxy group may be used alone or in combination of two or more.

[0070] The structural unit derived from an aromatic vinyl compound in component (B) is not particularly limited as long as it is derived from an aromatic compound substituted with at least a vinyl group. Specific examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, 3-vinyltoluene, dimethylstyrene, ethylvinylbenzene, chloromethylstyrene, vinylnaphthalene, and vinylanthracene. The aromatic vinyl compounds can be used alone or in combination of two or more.

[0071] In component (B), the bonding state of the monomers that give each structural unit may be block bonding, random bonding, or a combination thereof.

[0072] Component (B) may contain structural units other than the above-mentioned unsaturated monomers. Examples of other structural units include, but are not limited to, structural units derived from unsaturated aliphatic hydrocarbon compounds. Examples of the unsaturated aliphatic hydrocarbon compounds include linear, branched, and cyclic unsaturated aliphatic hydrocarbon compounds. Examples of linear or branched unsaturated aliphatic hydrocarbon compounds include propylene, isobutylene, diisobutylene, triisobutylene, tripropylene, and tetrapropylene. Examples of cyclic unsaturated aliphatic hydrocarbon compounds include cyclopentene, cyclohexene, and cyclooctene. The structural units derived from the above-mentioned unsaturated aliphatic hydrocarbon compounds may include one or more types.

[0073] Suitable embodiments of component (B) include, for example, copolymers containing structural units derived from one or more selected from the group consisting of unsaturated monocarboxylic acids and unsaturated dicarboxylic acids and structural units derived from aromatic vinyl compounds. Specific examples of component (B), from the viewpoint of further improving the modulus of elasticity in water when treated with the treatment composition of the present invention, preferably contain one or more selected from the group consisting of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinylbenzoic acid-maleic acid copolymer, vinylbenzoic acid-acrylic acid copolymer, vinylbenzoic acid-methacrylic acid copolymer, and styrene-4-vinylbenzoic acid copolymer, and more preferably contain styrene-maleic acid copolymer.

[0074] In component (B), the molar ratio (u1 / u2) of the structural unit (u1) derived from the unsaturated monomer having a carboxy group to the structural unit (u2) derived from the aromatic vinyl compound monomer is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1.

[0075] The acid value of component (B) is 100 mgKOH / g or more, and from the viewpoint of further improving the underwater elastic modulus when treated with the treatment composition of the present invention, it is preferably 200 mgKOH / g or more, more preferably 300 mgKOH / g or more, even more preferably 400 mgKOH / g or more, and preferably 1000 mgKOH / g or less, more preferably 800 mgKOH / g or less, even more preferably 600 mgKOH / g or less. The acid value of component (B) is preferably 100 mgKOH / g or more and 1000 mgKOH / g or less, more preferably 200 mgKOH / g or more and 800 mgKOH / g or less, even more preferably 200 mgKOH / g or more and 600 mgKOH / g or less, still more preferably 300 mgKOH / g or more and 600 mgKOH / g or less, still more preferably 400 mgKOH / g or more and 600 mgKOH / g or less. The acid value here refers to the number of milligrams of potassium hydroxide required to neutralize 1 g of sample.

[0076] Specific examples of component (B) having an acid value within the above range include the following compounds: Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 1 / 1) 475 mg KOH / g Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 2 / 1) 355 mg KOH / g Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 3 / 1) 285 mg KOH / g

[0077] Component (B) has a weight average molecular weight of 1,500 or more and 15,000 or less. From the viewpoint of further improving the underwater elastic modulus when treated with the treatment composition of the present invention, the weight average molecular weight is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 6,000 or more, and preferably 10,000 or less, more preferably 9,500 or less, and even more preferably 9,000 or less. Component (B2) has a weight average molecular weight of preferably 1,500 or more and 10,000 or less, more preferably 3,000 or more and 10,000 or less, even more preferably 5,000 or more and 9,500 or less, and even more preferably 6,000 or more and 9,000 or less. The weight average molecular weight of component (B) may also be preferably 3,000 or more and 15,000 or less, more preferably 5,000 or more and 15,000 or less, even more preferably 6,000 or more and 10,000 or less. The term "weight average molecular weight" as used herein refers to a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC), and specifically can be measured by the method described in the examples.

[0078] (Content of component (B)) From the viewpoint of further improving the underwater elastic modulus when treated with the treatment composition of the present invention, the content of component (B) in the modified regenerated collagen fiber is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 3.0% by mass or more, still more preferably 5.0% by mass or more, still more preferably 10% by mass or more, still more preferably 15% by mass or more, still more preferably 20% by mass or more, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, still more preferably 55% by mass or less, still more preferably 50% by mass or less, still more preferably 45% by mass or less, and still more preferably 40% by mass or less. The content of component (B) in the modified regenerated collagen fiber is preferably 0.1% by mass or more and 70% by mass or less, more preferably 0.5% by mass or more and 65% by mass or less, even more preferably 1.0% by mass or more and 60% by mass or less, even more preferably 3.0% by mass or more and 55% by mass or less, even more preferably 5.0% by mass or more and 50% by mass or less, even more preferably 10% by mass or more and 45% by mass or less, even more preferably 15% by mass or more and 40% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less.

[0079] Furthermore, in this specification, the amount of component (B) in the modified regenerated collagen fibers is quantified by selecting an appropriate method that does not decompose component (B) and can dissolve the regenerated collagen fibers, and then dissolving and extracting the fibers. After appropriately diluting the extracted solution, the peak area of ​​a chromatogram created at an absorption wavelength suitable for quantifying component (B) is measured using, for example, GPC / UV, and the content of component (B) is calculated from the peak area. Specifically, this can be measured by the method described in the Examples.

[0080] The mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers of the treatment composition of the present invention may be controlled depending on the mode of use. For example, when the treatment composition is a coating type, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers is preferably 0.2 or more, more preferably 0.5 or more, even more preferably 0.6 or more, still more preferably 0.8 or more, still more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 2.0 or more, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, and is preferably 2000 or less, more preferably 1000 or less, still more preferably 400 or less, still more preferably 200 or less, still more preferably 100 or less, still more preferably 50 or less, still more preferably 20 or less, still more preferably 10 or less, and still more preferably 7 or less. That is, the mass ratio [(B) / (A)] is preferably 0.2 or more and 2000 or less, more preferably 0.5 or more and 1000 or less, even more preferably 0.6 or more and 400 or less, still more preferably 0.8 or more and 200 or less, still more preferably 1.0 or more and 100 or less, still more preferably 1.5 or more and 50 or less, still more preferably 1.5 or more and 20 or less, still more preferably 2.0 or more and 10 or less, and still more preferably 2.0 or more and 7 or less. Furthermore, when the treatment composition is an immersion type, the mass ratio of component (A) in the treatment composition to component (B) in the regenerated collagen fibers [(B) / (A)] is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.03 or more, still more preferably 0.05 or more, still more preferably 0.08 or more, and still more preferably 0.10 or more, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, and can be set to preferably 150 or less, more preferably 100 or less, still more preferably 30 or less, still more preferably 15 or less, still more preferably 5 or less, still more preferably 3 or less, still more preferably 1.5 or less, still more preferably 1.0 or less, and still more preferably 0.5 or less.That is, the mass ratio [(B) / (A)] is preferably 0.01 or more and 150 or less, more preferably 0.02 or more and 100 or less, even more preferably 0.03 or more and 30 or less, still more preferably 0.03 or more and 15 or less, still more preferably 0.03 or more and 5 or less, still more preferably 0.05 or more and 3 or less, still more preferably 0.08 or more and 1.5 or less, still more preferably 0.10 or more and 1.0 or less, and still more preferably 0.10 or more and 0.5 or less.

[0081] (Component (C): Polyvalent Metal, or Salt or Complex Thereof) In order to firmly coordinate component (B) inside the fiber and further improve the underwater elastic modulus when treated with the treatment composition of the present invention, the modified regenerated collagen fibers preferably contain, in addition to component (B), a polyvalent metal, or a salt or complex thereof as component (C). Component (C) also acts as a modifier for the regenerated collagen fibers. Examples of component (C) include one or more polyvalent metals selected from the group consisting of calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof. These can be used alone or in combination of two or more. Among the above, from the viewpoint of improving water resistance and further improving the modulus of elasticity in water when treated with the treatment composition of the present invention, component (C) preferably contains one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt or complex thereof, and more preferably contains aluminum, or a salt or complex thereof.

[0082] When the modified regenerated collagen fibers contain component (C), the content of component (C) in the modified regenerated collagen fibers is, in terms of metal element content, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving water resistance and further improving the underwater elastic modulus when treated with the treatment composition of the present invention. The content of component (C) in the modified regenerated collagen fibers is, in terms of metal element content, preferably 0.1% by mass or more and 40% by mass or less, more preferably 0.5% by mass or more and 30% by mass or less, even more preferably 1.0% by mass or more and 20% by mass or less, and even more preferably 2.0% by mass or more and 10% by mass or less. The amount of component (C) in the modified regenerated collagen fibers is quantified, for example, as follows. The modified regenerated collagen fibers are incinerated, alkali-fused, and dissolved in acid to prepare a solution. This solution is then appropriately diluted to prepare a measurement sample, and the metal elements are quantified using an ICP atomic emission spectrometer. The amounts of the metal elements can be measured specifically by the methods described in the Examples.

[0083] The mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers of the treatment composition of the present invention may be controlled depending on the mode of use. For example, when the treatment composition is a coating type, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers can be set to preferably 0.005 or more, more preferably 0.010 or more, even more preferably 0.02 or more, still more preferably 0.05 or more, and even more preferably 0.10 or more, and preferably 100 or less, more preferably 20 or less, even more preferably 10 or less, still more preferably 5 or less, still more preferably 2 or less, still more preferably 1.0 or less, still more preferably 0.5 or less, and even more preferably 0.2 or less, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage. That is, the mass ratio [(C) / (A)] is preferably 0.005 or more and 100 or less, more preferably 0.010 or more and 20 or less, even more preferably 0.02 or more and 10 or less, still more preferably 0.02 or more and 5 or less, still more preferably 0.05 or more and 2 or less, still more preferably 0.05 or more and 1.0 or less, still more preferably 0.10 or more and 0.5 or less, and still more preferably 0.10 or more and 0.2 or less. Furthermore, when the treatment composition is used for immersion-type regenerated collagen fibers, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers can be set to preferably 0.001 or more, more preferably 0.003 or more, even more preferably 0.005 or more, still more preferably 0.010 or more, still more preferably 0.02 or more, still more preferably 0.03 or more, and preferably 33 or less, more preferably 10 or less, still more preferably 7 or less, still more preferably 3 or less, still more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage.That is, the mass ratio [(C) / (A)] is preferably 0.001 or more and 33 or less, more preferably 0.003 or more and 10 or less, even more preferably 0.005 or more and 7 or less, still more preferably 0.005 or more and 3 or less, even more preferably 0.005 or more and 1.0 or less, still more preferably 0.010 or more and 0.7 or less, still more preferably 0.02 or more and 0.3 or less, still more preferably 0.02 or more and 0.2 or less, and still more preferably 0.03 or more and 0.1 or less.

[0084] (Method for manufacturing modified regenerated collagen fibers) The regenerated collagen fibers that are the raw material for modified regenerated collagen fibers do not need to be 100% collagen, and may contain natural or synthetic polymers or additives to improve quality. Furthermore, they may be post-processed regenerated collagen fibers. Filaments are preferred as the form of regenerated collagen fibers. Filaments are generally taken out from bobbins or boxes.

[0085] Suitable regenerated collagen fibers are artificially produced using collagen-derived polymers or oligomers as raw materials. Regenerated collagen fibers are usually produced by using a solubilized collagen raw material as a spinning dope, discharging this from a spinning nozzle into a coagulation bath to form fibers, and then drying the fibrous collagen in the final step. Here, regenerated collagen fibers before the drying step (hereinafter also referred to as "undried regenerated collagen fibers") can be produced by conventionally known methods. For example, undried regenerated collagen fibers can be obtained by discharging an aqueous collagen solution obtained by solubilizing insoluble collagen fibers made from the split hides of livestock animals through a spinning nozzle or slit, immersing the aqueous solution in an inorganic salt solution, and then recovering the resultant fibers without drying. This method will be specifically described below.

[0086] The collagen raw material used in the production of regenerated collagen fibers is preferably split skins. Split skins are obtained from fresh split skins obtained by slaughtering livestock animals such as cattle, or from salted raw hides. These split skins are mostly composed of insoluble collagen fibers, but are usually used after removing the fleshy part that is usually attached in a mesh-like form and removing the salt used to prevent spoilage and deterioration.

[0087] These insoluble collagen fibers contain impurities such as lipids (e.g., glycerides, phospholipids, and free fatty acids), glycoproteins, albumin, and other proteins other than collagen. These impurities have a significant effect on spinning stability, quality (e.g., gloss and strength and elongation), odor, and other factors during fiberization. Therefore, it is preferable to remove these impurities in advance by, for example, soaking the insoluble collagen fibers in lime to hydrolyze the fat in the fibers and loosen the collagen fibers, and then subjecting the fibers to conventional leather treatments such as acid / alkali treatment, enzyme treatment, and solvent treatment.

[0088] The insoluble collagen thus treated is then subjected to a solubilization treatment to cleave the cross-linked peptide moieties. As a method for such solubilization, a commonly used known alkali solubilization method, an enzyme solubilization method, etc., can be used. Furthermore, the alkali solubilization method and the enzyme solubilization method may be used in combination.

[0089] When the alkali solubilization method is applied, it is preferable to neutralize with an acid such as hydrochloric acid. Note that, as an improved version of the conventional alkali solubilization method, for example, the method described in JP-B-46-15033 may be used.

[0090] The enzymatic solubilization method has the advantage of being able to obtain solubilized collagen with a uniform molecular weight, and is a method that can be suitably employed in the present invention. Examples of such enzymatic solubilization methods that can be employed include those described in Japanese Patent Publication Nos. 43-25829 and 43-27513.

[0091] If the collagen that has been solubilized in this way is further subjected to operations such as pH adjustment, salting out, water washing, and solvent treatment, it is possible to obtain regenerated collagen fibers with excellent quality, and therefore it is preferable to perform these treatments.

[0092] Solubilized collagen is dissolved in an acid such as hydrochloric acid, acetic acid, or lactic acid to obtain a collagen aqueous solution having a pH of 2 to 4.5 and a collagen concentration of 1% by mass or more, preferably 2% by mass or more, and 15% by mass or less, preferably 10% by mass or less. The collagen aqueous solution may be degassed under reduced pressure and stirred, as needed, or filtered to remove water-insoluble fine particles. Furthermore, the collagen aqueous solution may contain appropriate amounts of additives such as stabilizers and water-soluble polymers, as needed, for purposes such as improving mechanical strength, water resistance and heat resistance, gloss, spinnability, coloration prevention, and preservative properties.

[0093] The collagen aqueous solution is extruded, for example, through a spinning nozzle or slit, and then immersed in an inorganic salt aqueous solution to obtain undried regenerated collagen fibers. Examples of the inorganic salt aqueous solution include aqueous solutions of water-soluble inorganic salts such as sodium sulfate, sodium chloride, and ammonium sulfate. Typically, the concentration of the inorganic salt in these inorganic salt aqueous solutions is adjusted to 10 to 40% by mass. The pH of the inorganic salt aqueous solution is preferably 2 or higher, more preferably 4 or higher, and preferably 13 or lower, more preferably 12 or lower. To adjust the pH, for example, metal salts such as sodium borate and sodium acetate, hydrochloric acid, boric acid, acetic acid, and sodium hydroxide can be used. When the pH of the inorganic salt aqueous solution is within the above range, the collagen peptide bonds are less susceptible to hydrolysis, making it easier to obtain the desired fibers. The temperature of the inorganic salt aqueous solution is not particularly limited, but is typically 35°C or lower, which prevents denaturation of soluble collagen, prevents a decrease in the strength of the spun fibers, and facilitates the production of stable threads. The lower limit of the temperature of the inorganic salt aqueous solution is not particularly limited, but can typically be adjusted appropriately depending on the solubility of the inorganic salt.

[0094] Undried regenerated collagen fibers may be pretreated (crosslinked) by immersion in an epoxy compound or a solution thereof. The amount of the epoxy compound is preferably 0.1 equivalents or more, more preferably 0.5 equivalents or more, and even more preferably 1 equivalent or more, relative to the amount of amino groups in the regenerated collagen fibers that can react with the epoxy groups of the epoxy compound, as measured by amino acid analysis, and is also preferably 500 equivalents or less, more preferably 100 equivalents or less, and even more preferably 50 equivalents or less. By using an epoxy compound in this range, the regenerated collagen fibers can be sufficiently insolubilized in water, and this is also preferable from an industrial handleability and environmental standpoint.

[0095] The epoxy compound may be used as is or dissolved in various solvents. Examples of solvents include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; ethers such as tetrahydrofuran and dioxane; halogenated organic solvents such as dichloromethane, chloroform, and carbon tetrachloride; and neutral organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). These solvents may be used alone or in combination of two or more. When water is used as the solvent, an aqueous solution of an inorganic salt such as sodium sulfate, sodium chloride, or ammonium sulfate may be used as needed. Typically, the concentration of the inorganic salt in the aqueous solution is adjusted to 10 to 40% by mass. The pH of the aqueous solution may also be adjusted with, for example, a metal salt such as sodium borate or sodium acetate, or hydrochloric acid, boric acid, acetic acid, or sodium hydroxide. In this case, the pH of the aqueous solution is preferably 6 or higher, more preferably 8 or higher, from the viewpoint of preventing the reaction between the epoxy groups of the epoxy compound and the amino groups of collagen from slowing down and ensuring sufficient insolubilization in water. Furthermore, since the pH of an aqueous solution of an inorganic salt tends to decrease over time, a buffer may be used if necessary.

[0096] The temperature during treatment of undried regenerated collagen fibers with an epoxy compound is preferably 50°C or lower, from the viewpoints of preventing denaturation of the regenerated collagen fibers, preventing a decrease in the strength of the resulting fibers, and facilitating stable production of threads.

[0097] [Treatment with a fiber treating agent containing component (C)] From the viewpoint of improving water resistance, the modified regenerated collagen fibers used in the present invention preferably contain the component (C), and in producing the modified regenerated collagen fibers, it is preferable to treat the undried regenerated collagen fibers obtained by the above method in the following manner. First, the undried regenerated collagen fibers are immersed in a fiber treating agent containing component (C). The fiber treating agent containing component (C) is preferably an aqueous solution containing a polyvalent metal salt or polyvalent metal complex corresponding to component (C). The polyvalent metal salt or polyvalent metal complex preferably contains an aluminum salt or aluminum complex, and more preferably contains an aluminum salt. The aluminum salt is preferably basic aluminum chloride or basic aluminum sulfate represented by the following formula: Al(OH) n Cl 3-n , or Al2(OH) 2n (SO4) 3-n [wherein n is 0.5 to 2.5] Specific examples of the aluminum salt include aluminum sulfate, aluminum chloride, and alum, which can be used alone or in combination of two or more.

[0098] The content of the polyvalent metal salt and polyvalent metal complex in the fiber treatment agent is preferably 0.3% by mass or more and 5% by mass or less in terms of polyvalent metal oxide (aluminum oxide when the polyvalent metal is aluminum).

[0099] In order to prevent the polyvalent metal salt or polyvalent metal complex from being rapidly absorbed into the undried regenerated collagen fibers and causing uneven concentration, inorganic salts such as sodium chloride, sodium sulfate, and potassium chloride may be added to the fiber treatment agent as appropriate.

[0100] The pH of the fiber treatment agent at 25°C is preferably in the range of 2.5 or more and 5 or less, and can be adjusted using, for example, hydrochloric acid, sulfuric acid, acetic acid, sodium hydroxide, sodium carbonate, etc. A pH of 2.5 or more can suppress denaturation of the collagen structure, while a pH of 5 or less reduces the risk of precipitation of polyvalent metal salts or polyvalent metal complexes. It is preferable to initially adjust the pH to 2.2 or more and 3.5 or less to allow the aqueous solution of the polyvalent metal salt or polyvalent metal complex to sufficiently penetrate into the undried regenerated collagen fibers, and then add, for example, sodium hydroxide, sodium carbonate, etc. to adjust the pH to 3.5 or more and 5 or less to complete the treatment. When a highly basic polyvalent metal salt or polyvalent metal complex is used, only the initial pH adjustment of 2.5 or more and 5 or less is sufficient.

[0101] When treating with a fiber treatment agent containing component (C), the bath ratio of undried regenerated collagen fibers to the fiber treatment agent (dry mass of undried regenerated collagen fibers:mass of the fiber treatment agent) is preferably 1:2 to 1:500, more preferably 1:3 to 1:250, even more preferably 1:5 to 1:100, and even more preferably 1:20 to 1:50, when the mass of fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass.

[0102] The temperature during treatment with the fiber treatment agent containing component (C) (liquid temperature of the fiber treatment agent) is not particularly limited, but is preferably 5°C or higher, more preferably 10°C or higher, and is preferably 50°C or lower, more preferably 45°C or lower.

[0103] The treatment time (immersion time) with the fiber treatment agent containing component (C) is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and even more preferably 3 hours or more, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less.

[0104] After treating the undried regenerated collagen fibers with an epoxy compound and / or the fiber treatment agent, the fibers may be washed with water, for example, by washing with running water for 10 minutes to 4 hours.

[0105] [Treatment with a fiber treatment agent containing component (B)] Regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (C), are treated with a fiber treatment agent containing component (B) to obtain modified regenerated collagen fibers that are the target of treatment with the treatment composition of the present invention.

[0106] From the viewpoint of improving penetration into fibers and improving the treatment effect, the content of component (B) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, still more preferably 2.5% by mass or more, still more preferably 3.0% by mass or more, still more preferably 4.0% by mass or more, and is preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less, still more preferably 30% by mass or less, still more preferably 20% by mass or less, still more preferably 10% by mass or less, and still more preferably 5% by mass or less. The content of component (B) in the fiber treatment agent is preferably 0.3% by mass or more and 60% by mass or less, more preferably 0.5% by mass or more and 60% by mass or less, even more preferably 1.0% by mass or more and 40% by mass or less, still more preferably 2.5% by mass or more and 40% by mass or less, still more preferably 3.0% by mass or more and 35% by mass or less, still more preferably 4.0% by mass or more and 30% by mass or less, still more preferably 4.0% by mass or more and 20% by mass or less, still more preferably 4.0% by mass or more and 10% by mass or less, and still more preferably 4.0% by mass or more and 5% by mass or less.

[0107] The fiber treatment agent containing component (B) preferably further contains a pH adjuster. The pH adjuster is not particularly limited as long as it can adjust the pH to the desired level, but examples thereof include alkalis such as sodium hydroxide and potassium hydroxide, and acids such as phosphoric acid, sulfuric acid, and hydrochloric acid.

[0108] The fiber treatment agent containing component (B) further contains water. The water content in the fiber treatment agent is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and still more preferably 70% by mass or more, and is preferably 99.7% by mass or less.

[0109] The pH of the fiber treatment agent containing component (B) at 25°C is preferably 3.0 or higher, more preferably 3.5 or higher, and even more preferably 4.0 or higher, from the viewpoint of suppressing damage to the fiber, and is preferably 7.5 or lower, more preferably 7.0 or lower, and even more preferably 6.5 or lower, from the viewpoint of suppressing damage to the fiber. The pH of the fiber treatment agent containing component (B) at 25°C is preferably 3.0 or higher and 7.5 or lower, more preferably 3.5 or higher and 7.0 or lower, and even more preferably 4.0 or higher and 6.5 or lower. The pH can be measured by the method described in the Examples.

[0110] Treatment with a fiber treatment agent containing component (B) can be carried out by immersing regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (C), in the fiber treatment agent containing component (B).

[0111] When treating with a fiber treatment agent containing component (B), the bath ratio of the regenerated collagen fibers or undried regenerated collagen fibers to the fiber treatment agent (dry mass of regenerated collagen fibers or undried regenerated collagen fibers:mass of the fiber treatment agent) is preferably 1:2 to 1:500, more preferably 1:3 to 1:250, even more preferably 1:5 to 1:100, and even more preferably 1:20 to 1:50, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass.

[0112] The temperature during treatment with a fiber treatment agent containing component (B) (the temperature of the fiber treatment agent) is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 30°C or higher, from the viewpoint of improving penetration into fibers, and is preferably less than 100°C, more preferably 90°C or lower, even more preferably 80°C or lower, still more preferably 70°C or lower, and even more preferably 60°C or lower, from the viewpoint of suppressing damage to fibers. The temperature during treatment with a fiber treatment agent containing component (B) (the temperature of the fiber treatment agent) is preferably 20°C or higher and lower than 100°C, more preferably 20°C or higher and 90°C or lower, even more preferably 25°C or higher and 80°C or lower, still more preferably 25°C or higher and 70°C or lower, and even more preferably 30°C or higher and 60°C or lower. When treating with a fiber treatment agent by heating, the regenerated collagen fibers or undried regenerated collagen fibers may be immersed in the heated fiber treatment agent, or the fiber treatment agent may be heated after immersing the regenerated collagen fibers or undried regenerated collagen fibers in a low-temperature fiber treatment agent.

[0113] The treatment time (immersion time) with the fiber treatment agent containing component (B) is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and still more preferably 3 hours or more from the viewpoint of improving the treatment effect, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less from the viewpoint of suppressing damage to the fiber. The treatment time (immersion time) with the fiber treatment agent containing component (B) is preferably 15 minutes to 48 hours, more preferably 30 minutes to 33 hours, even more preferably 1 hour to 20 hours, and still more preferably 3 hours to 20 hours.

[0114] Treatment with the fiber treatment agent containing component (B) is preferably carried out in an environment in which evaporation of water is suppressed. Specific means for suppressing evaporation of water include covering the container of the fiber treatment agent in which the fibers are immersed with a film-like substance, cap, lid, or the like made of a material that is impermeable to water vapor.

[0115] After treatment with the fiber treatment agent, the resulting modified regenerated collagen fibers are preferably washed with water, for example, by washing with running water for 10 minutes to 4 hours.

[0116] The treatment with the fiber treatment agent containing component (B) may be carried out two or more times. Specifically, it is preferable to carry out the following steps (1) and (2) in this order two or more times: (1) a step of immersing regenerated collagen fibers or undried regenerated collagen fibers obtained by treatment with the fiber treatment agent containing component (C) in the fiber treatment agent containing component (B); and (2) a step of removing the fibers immersed in the fiber treatment agent in step (1) and washing them with water.

[0117] Here, from the viewpoint of improving the treatment effect, the treatment conditions for the first treatment and the second and subsequent treatments are more preferably in the following ranges. Other points are the same as those described above. In the first treatment, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 4.5 or more, more preferably 5.0 or more, and preferably 7.5 or less, more preferably 7.0 or less, and even more preferably 6.5 or less, from the viewpoint of improving penetration into the fiber and suppressing damage to the fiber. Furthermore, in the first treatment, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 4.5 or more and 7.5 or less, more preferably 5.0 or more and 7.0 or less, and even more preferably 5.0 or more and 6.5 or less. In the first treatment, the treatment time (immersion time) in step (1) is preferably 3 hours or more, more preferably 4 hours or more, and even more preferably 6 hours or more, from the viewpoint of improving the treatment effect. Furthermore, from the viewpoint of suppressing damage to the fiber, it is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less. In the first treatment, the treatment time (immersion time) in step (1) is preferably 3 hours or more and 48 hours or less, more preferably 4 hours or more and 33 hours or less, and even more preferably 6 hours or more and 20 hours or less.

[0118] In the second or subsequent treatments, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 3.0 or more, more preferably 3.5 or more, and preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.0 or less, and still more preferably less than 4.5, from the viewpoint of improving the treatment effect. Furthermore, in the second or subsequent treatments, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 3.0 or more and 6.0 or less, more preferably 3.0 or more and 5.5 or less, even more preferably 3.5 or more and 5.0 or less, and still more preferably 3.5 or more and less than 4.5. In the second or subsequent treatments, the treatment time (immersion time) in step (1) is preferably 15 minutes or more, more preferably 30 minutes or more, from the viewpoint of improving the treatment effect, and is preferably 5 hours or less, more preferably 3 hours or less, and still more preferably 2 hours or less, from the viewpoint of suppressing fiber damage. In the second and subsequent treatments, the treatment time (immersion time) in step (1) is preferably 15 minutes to 5 hours, more preferably 15 minutes to 3 hours, and even more preferably 30 minutes to 2 hours.

[0119] The number of treatments with the fiber treatment agent containing component (B) is preferably two or more, preferably five or less, and more preferably three or less, from the viewpoints of improving the treatment effect and productivity. It is preferably two to five times, more preferably two to three times. After the treatment, the resulting modified regenerated collagen fibers are preferably dried. The drying temperature is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of improving the drying speed, and is preferably 100°C or lower, more preferably 80°C or lower, from the viewpoint of suppressing fiber damage. The drying time is preferably 15 minutes or longer, more preferably 30 minutes or longer, and is preferably 48 hours or shorter, more preferably 33 hours or shorter, and even more preferably 20 hours or shorter, from the viewpoint of suppressing fiber damage.

[0120] By carrying out the above modification treatment, component (B) penetrates into the regenerated collagen fibers. Furthermore, when treatment is carried out with a fiber treatment agent containing component (C), component (B) is strongly coordinated to the polyvalent metal in the fibers. It is therefore believed that treating modified regenerated collagen fibers with the treatment agent composition of the present invention can improve the underwater elastic modulus.

[0121] The regenerated collagen fibers to be treated with the treatment composition of the present invention may be those containing at least a portion of the modified regenerated collagen fibers, or may be fibers consisting solely of modified regenerated collagen fibers. From the viewpoint of further improving the underwater elastic modulus after treatment, the regenerated collagen fibers to be treated with the treatment composition of the present invention are preferably fibers consisting solely of modified regenerated collagen fibers.

[0122] [Treatment Method] The present invention provides a method for treating regenerated collagen fibers, the treatment method comprising a step of applying a regenerated collagen fiber treatment composition to the regenerated collagen fibers, the treatment composition containing the following component (A) and water and having a pH of 2 or more and 6 or less, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B): (A) a compound having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, the number of phenolic hydroxyl groups being 2 or less, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A chelate stability constant log K with an ion of 2 or less; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, wherein the copolymer has an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof. In the following description, the method for treating regenerated collagen fibers will also be simply referred to as the "treatment method of the present invention."

[0123] The regenerated collagen fibers, the treatment composition, and preferred embodiments thereof are the same as those described for the regenerated collagen fiber treatment composition.

[0124] The treatment method of the present invention includes a step of applying the treatment composition to the regenerated collagen fibers. The method of applying the treatment composition to the regenerated collagen fibers may be any method that can bring the treatment composition into contact with the regenerated collagen fibers, and examples include a method of applying the composition to dry or wet regenerated collagen fibers, and a method of immersing the regenerated collagen fibers in the composition. Among the above, the method of immersing dry regenerated collagen fibers in the treatment composition is preferred.

[0125] Here, when the content of component (A) in the treatment composition is c [mass %] and the amount of treatment composition applied per 1 g of dry mass of fiber is b [g], the total amount of component (A) applied per 1 g of dry mass of fiber, b × c / 100 [g], is preferably 0.01 g or more, more preferably 0.03 g or more, even more preferably 0.05 g or more, and still more preferably 0.1 g or more, from the viewpoint of improving the underwater elastic modulus of the modified regenerated collagen fiber, and is preferably 10 g or less, more preferably 5 g or less, even more preferably 3 g or less, and still more preferably 1 g or less, from the viewpoint of economic rationality. When the content of component (A) in the treatment composition is c [% by mass] and the amount of treatment composition applied per 1 g of dry mass of fiber is b [g], the total amount of component (A) applied per 1 g of dry mass of fiber, b × c / 100 [g], is preferably 0.01 g or more and 10 g or less, more preferably 0.03 g or more and 5 g or less, even more preferably 0.05 g or more and 3 g or less, and still more preferably 0.1 g or more and 1 g or less. The dry mass of fiber referred to here means the mass of fiber after conditioning for 24 hours at 20°C and a relative humidity of 65%.

[0126] From the viewpoint of balancing treatment effect and economic efficiency, the amount of the treatment composition applied to the regenerated collagen fibers is preferably a bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition) of 1:0.2 to 1:500, more preferably 1:0.2 to 1:200, even more preferably 1:0.5 to 1:100, and still more preferably 1:0.5 to 1:50, when the mass of the fibers after conditioning at 20°C and 65% relative humidity for 24 hours is taken as the dry mass. When the regenerated collagen fibers are immersed in the treatment composition, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition) is even more preferably 1:2 to 1:50, even more preferably 1:5 to 1:50, even more preferably 1:10 to 1:50, and even more preferably 1:10 to 1:40, when the mass of the fibers after conditioning at 20°C and 65% relative humidity for 24 hours is taken as the dry mass. When the treatment composition is applied to the regenerated collagen fibers, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition) is even more preferably 1:0.5 to 1:20, even more preferably 1:0.5 to 1:10, even more preferably 1:0.5 to 1:5, and even more preferably 1:0.5 to 1:3, when the mass of the fibers after conditioning for 24 hours at 20°C and a relative humidity of 65% is taken as the dry mass.

[0127] Furthermore, in this step, the treatment conditions for the regenerated collagen fibers may be set using the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers as an index. Specifically, for example, when the treatment composition is applied to the regenerated collagen fibers, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers may be, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, preferably 0.2 or more, more preferably 0.5 or more, even more preferably 0.6 or more, still more preferably 0.8 or more, even more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 2.0 or more, and may be preferably 2000 or less, more preferably 1000 or less, even more preferably 400 or less, still more preferably 200 or less, still more preferably 100 or less, still more preferably 50 or less, still more preferably 20 or less, still more preferably 10 or less, and still more preferably 7 or less. That is, the mass ratio [(B) / (A)] is preferably 0.2 or more and 2000 or less, more preferably 0.5 or more and 1000 or less, even more preferably 0.6 or more and 400 or less, still more preferably 0.8 or more and 200 or less, still more preferably 1.0 or more and 100 or less, still more preferably 1.5 or more and 50 or less, even more preferably 1.5 or more and 20 or less, still more preferably 2.0 or more and 10 or less, and still more preferably 2.0 or more and 7 or less.On the other hand, when the treatment composition is immersed in the regenerated collagen fibers, this step may be performed under conditions such that the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.03 or more, still more preferably 0.05 or more, still more preferably 0.08 or more, and still more preferably 0.10 or more, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, and is preferably 150 or less, more preferably 100 or less, even more preferably 30 or less, still more preferably 15 or less, still more preferably 5 or less, still more preferably 3 or less, still more preferably 1.5 or less, still more preferably 1.0 or less, and still more preferably 0.5 or less. That is, the mass ratio [(B) / (A)] is preferably 0.01 or more and 150 or less, more preferably 0.02 or more and 100 or less, even more preferably 0.03 or more and 30 or less, still more preferably 0.03 or more and 15 or less, still more preferably 0.03 or more and 5 or less, still more preferably 0.05 or more and 3 or less, still more preferably 0.08 or more and 1.5 or less, still more preferably 0.10 or more and 1.0 or less, and still more preferably 0.10 or more and 0.5 or less.

[0128] Furthermore, the treatment conditions for the regenerated collagen fibers can also be set using the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers as an index. Specifically, for example, when the treatment composition is applied to the regenerated collagen fibers, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers can be performed under conditions such that, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, the mass ratio is preferably 0.005 or more, more preferably 0.010 or more, even more preferably 0.02 or more, still more preferably 0.05 or more, and even more preferably 0.10 or more, and is preferably 100 or less, more preferably 20 or less, even more preferably 10 or less, still more preferably 5 or less, still more preferably 2 or less, still more preferably 1.0 or less, still more preferably 0.5 or less, and even more preferably 0.2 or less. That is, the mass ratio [(C) / (A)] is preferably 0.005 or more and 100 or less, more preferably 0.010 or more and 20 or less, even more preferably 0.02 or more and 10 or less, still more preferably 0.02 or more and 5 or less, still more preferably 0.05 or more and 2 or less, still more preferably 0.05 or more and 1.0 or less, still more preferably 0.10 or more and 0.5 or less, and still more preferably 0.10 or more and 0.2 or less. On the other hand, when the treatment composition is immersed in the regenerated collagen fibers, this step can be performed under conditions such that the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers is preferably 0.001 or more, more preferably 0.003 or more, even more preferably 0.005 or more, still more preferably 0.010 or more, still more preferably 0.02 or more, still more preferably 0.03 or more, and is preferably 33 or less, more preferably 10 or less, still more preferably 7 or less, still more preferably 3 or less, still more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage.That is, the mass ratio [(C) / (A)] is preferably 0.001 or more and 33 or less, more preferably 0.003 or more and 10 or less, even more preferably 0.005 or more and 7 or less, still more preferably 0.005 or more and 3 or less, still more preferably 0.005 or more and 1.0 or less, still more preferably 0.010 or more and 0.7 or less, still more preferably 0.02 or more and 0.3 or less, still more preferably 0.02 or more and 0.2 or less, and still more preferably 0.03 or more and 0.1 or less.

[0129] When the treatment composition is applied to the regenerated collagen fibers, the application time is preferably 10 seconds or more, more preferably 20 seconds or more, and preferably 10 minutes or less, more preferably 5 minutes or less. The application time is preferably 10 seconds or more and 10 minutes or less, more preferably 20 seconds or more and 5 minutes or less.

[0130] After applying the treatment composition to the regenerated collagen fibers, it is preferable to further carry out a step of leaving the composition to stand. The leaving time is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more, from the viewpoint of further improving the underwater elastic modulus after treatment, and is preferably 1 hour or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less, from the viewpoint of suppressing mass loss after treatment and suppressing thermal shrinkage. The leaving time is preferably 1 minute or more and 1 hour or less, more preferably 3 minutes or more and 30 minutes or less, and even more preferably 5 minutes or more and 20 minutes or less.

[0131] When regenerated collagen fibers are immersed in the treatment composition, the immersion time is preferably 10 seconds or more, more preferably 30 seconds or more, from the viewpoint of further improving the underwater elastic modulus after treatment, and is preferably 3 hours or less, more preferably 2 hours or less, and even more preferably 90 minutes or less, from the viewpoint of improving productivity. The immersion time is preferably 10 seconds or more and 3 hours or less, more preferably 10 seconds or more and 2 hours or less, and even more preferably 30 seconds or more and 90 minutes or less.

[0132] The temperature at which the treatment composition is applied to the regenerated collagen fibers is not particularly limited, but from the viewpoint of further improving the underwater elastic modulus after treatment, it is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 20°C or higher, and even more preferably 30°C or higher. Furthermore, from the viewpoint of suppressing mass loss after treatment and suppressing thermal shrinkage, it is preferably 80°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower. The temperature is preferably 5°C or higher and 80°C or lower, more preferably 10°C or higher and 60°C or lower, even more preferably 20°C or higher and 50°C or lower, and even more preferably 30°C or higher and 50°C or lower.

[0133] The treatment method of the present invention may include a step of rinsing away excess treatment composition applied to the regenerated collagen fibers after applying the treatment composition to the regenerated collagen fibers and before carrying out the next step (hereinafter also referred to simply as a "rinsing step"). The rinsing step is carried out, for example, by rinsing away excess treatment composition applied to the regenerated collagen fibers with water. There are no particular restrictions on the temperature of the water, but warm water at 35 to 45°C is preferred.

[0134] The treatment method of the present invention preferably includes a step of drying the regenerated collagen fibers (hereinafter also simply referred to as a "drying step") after applying the treatment composition to the regenerated collagen fibers, or after the rinsing step, if any. The step of drying the regenerated collagen fibers is a step of reducing the moisture content of the regenerated collagen fibers, and includes, for example, towel drying, drying with a hairdryer (cold air or hot air), air drying, and a combination of two or more of these drying treatments in order to actively reduce the moisture content of the regenerated collagen fibers.

[0135] [Modified Regenerated Collagen Fiber] The present invention further provides a modified regenerated collagen fiber containing the following components (A) and (B): (A) a compound having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+(1) A copolymer having a chelate stability constant log K of 2 or less with an ion; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof.

[0136] The modified regenerated collagen fibers are regenerated collagen fibers modified with the components (A) and (B). From the viewpoint of further improving the underwater elastic modulus after the treatment, the regenerated collagen fibers preferably further contain the component (C): a polyvalent metal, a salt thereof, or a complex thereof.

[0137] The modified regenerated collagen fibers of the present invention preferably have a mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers controlled according to the treatment method for the regenerated collagen fibers. That is, when the regenerated collagen fibers are treated by application, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers is preferably 0.2 or more, more preferably 0.5 or more, even more preferably 0.6 or more, still more preferably 0.8 or more, even more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 2.0 or more, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, and is preferably 2000 or less, more preferably 1000 or less, even more preferably 400 or less, still more preferably 200 or less, still more preferably 100 or less, still more preferably 50 or less, still more preferably 20 or less, still more preferably 10 or less, and still more preferably 7 or less. That is, the mass ratio [(B) / (A)] is preferably 0.2 or more and 2000 or less, more preferably 0.5 or more and 1000 or less, even more preferably 0.6 or more and 400 or less, still more preferably 0.8 or more and 200 or less, still more preferably 1.0 or more and 100 or less, still more preferably 1.5 or more and 50 or less, even more preferably 1.5 or more and 20 or less, still more preferably 2.0 or more and 10 or less, and still more preferably 2.0 or more and 7 or less. On the other hand, when the regenerated collagen fibers are treated by immersion, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the regenerated collagen fibers is, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.03 or more, still more preferably 0.05 or more, still more preferably 0.08 or more, and still more preferably 0.10 or more, and is preferably 150 or less, more preferably 100 or less, still more preferably 30 or less, still more preferably 15 or less, still more preferably 5 or less, still more preferably 3 or less, still more preferably 1.5 or less, still more preferably 1.0 or less, and still more preferably 0.5 or less.That is, the mass ratio [(B) / (A)] is preferably 0.01 or more and 150 or less, more preferably 0.02 or more and 100 or less, even more preferably 0.03 or more and 30 or less, still more preferably 0.03 or more and 15 or less, still more preferably 0.03 or more and 5 or less, still more preferably 0.05 or more and 3 or less, still more preferably 0.08 or more and 1.5 or less, still more preferably 0.10 or more and 1.0 or less, and still more preferably 0.10 or more and 0.5 or less.

[0138] Furthermore, the modified regenerated collagen fibers of the present invention preferably have a mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers controlled according to the treatment method for the regenerated collagen fibers. That is, when the regenerated collagen fibers are treated by application, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers is preferably 0.005 or more, more preferably 0.010 or more, even more preferably 0.02 or more, still more preferably 0.05 or more, and even more preferably 0.10 or more, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, and is preferably 100 or less, more preferably 20 or less, even more preferably 10 or less, still more preferably 5 or less, still more preferably 2 or less, still more preferably 1.0 or less, still more preferably 0.5 or less, and even more preferably 0.2 or less. That is, the mass ratio [(C) / (A)] is preferably 0.005 or more and 100 or less, more preferably 0.010 or more and 20 or less, even more preferably 0.02 or more and 10 or less, still more preferably 0.02 or more and 5 or less, still more preferably 0.05 or more and 2 or less, still more preferably 0.05 or more and 1.0 or less, still more preferably 0.10 or more and 0.5 or less, and still more preferably 0.10 or more and 0.2 or less. On the other hand, when the regenerated collagen fibers are treated by immersion, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the regenerated collagen fibers is, from the viewpoints of further improving the underwater elastic modulus after treatment, suppressing mass loss after treatment, and suppressing thermal shrinkage, preferably 0.001 or more, more preferably 0.003 or more, even more preferably 0.005 or more, still more preferably 0.010 or more, still more preferably 0.02 or more, still more preferably 0.03 or more, and is preferably 33 or less, more preferably 10 or less, still more preferably 7 or less, still more preferably 3 or less, still more preferably 1.0 or less, still more preferably 0.7 or less, still more preferably 0.3 or less, still more preferably 0.2 or less, still more preferably 0.1 or less.That is, the mass ratio [(C) / (A)] is preferably 0.001 or more and 33 or less, more preferably 0.003 or more and 10 or less, even more preferably 0.005 or more and 7 or less, still more preferably 0.005 or more and 3 or less, still more preferably 0.005 or more and 1.0 or less, still more preferably 0.010 or more and 0.7 or less, still more preferably 0.02 or more and 0.3 or less, still more preferably 0.02 or more and 0.2 or less, and still more preferably 0.03 or more and 0.1 or less.

[0139] The modified regenerated collagen fibers can be obtained by preparing modified regenerated collagen fibers containing component (B) using the method described above, and then treating the modified regenerated collagen fibers with a regenerated collagen fiber treatment composition containing component (A). The treatment method of the present invention described above can preferably be used as the method for treating modified regenerated collagen fibers.

[0140] [Fiber for head accessories, head accessories] The present invention further provides a fiber for head accessories containing the modified regenerated collagen fiber, and a head accessory containing the fiber. The modified regenerated collagen fiber can be suitably used as a fiber for head accessories as is, or after further dyeing. As used herein, "head accessories" refers to, for example, hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories, doll hair, etc. Furthermore, "fiber for head accessories" refers to fibers used in the head accessories. In this application, fibers for head accessories also include human hair. The head accessory product may contain at least a portion of the modified regenerated collagen fiber, and may contain both the modified regenerated collagen fiber and human hair.

[0141] In relation to the above-described embodiments, the present invention discloses the following: <1> A regenerated collagen fiber treatment composition, the treatment composition containing the following component (A) and water, and having a pH of 2 or more and 6 or less, the regenerated collagen fiber comprising modified regenerated collagen fiber containing the following component (B): (A) a compound having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, the number of phenolic hydroxyl groups being 2 or less, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A copolymer or salt thereof, which has a chelate stability constant log K with an ion of 2 or less, (2) a molecular weight of 1,500 or more, and (B) a copolymer comprising structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, and which has an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less. <2> The regenerated collagen fiber treating composition according to <1>, wherein the pKa of the component (A) is preferably 1.5 or more and 6 or less, more preferably 2.0 or more and 5 or less, and even more preferably 2.5 or more and 4 or less. <3> The regenerated collagen fiber treating composition according to <1> or <2>, wherein the pKa of the component (A) is preferably −3.0 or more and +3.0 or less, more preferably −2.0 or more and +2.0 or less, and more preferably −1.0 or more and +1.0 or less, relative to the pH value of the treating composition. <4> The regenerated collagen fiber treating agent composition according to any one of <1> to <3>, wherein the solubility of the component (A) in 100 g of water at 25°C at pH 3 is preferably 2.5 g or more, more preferably 5 g or more, even more preferably 10 g or more, and preferably 100 g or less. <5> The regenerated collagen fiber treating agent composition according to any one of <1> to <4>, wherein the number of phenolic hydroxyl groups in the component (A) is preferably 1 or less, more preferably 0. <6> When the component (A) satisfies the above (1), the Al content of the component (A) is 3+The regenerated collagen fiber treating agent composition according to any one of <1> to <5>, wherein the chelate stability constant log K with an ion is preferably 1.8 or less, more preferably 1.6 or less, even more preferably 1.4 or less, still more preferably 1.2 or less, still more preferably 1.0 or less, and still more preferably 0.5 or less. <7> The regenerated collagen fiber treating agent composition according to any one of <1> to <6>, wherein, when the component (A) satisfies the above (2), the molecular weight of the component (A) is preferably 2,000 to 100,000,000, more preferably 3,000 to 50,000,000, even more preferably 3,000 to 5,000,000, still more preferably 3,000 to 2,000,000, still more preferably 3,000 to 10,000, <8> The regenerated collagen fiber treating agent composition according to any one of <1> to <7>, wherein the component (A) preferably contains a compound having an acidic group, more preferably a compound having one or more acidic groups selected from the group consisting of a carboxy group, a sulfate group, a sulfonate group, and a phosphate group, even more preferably a compound having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group, and even more preferably a compound having a carboxy group. <9> The regenerated collagen fiber treating agent composition according to any one of <1> to <8>, wherein, when the component (A) is a compound having a molecular weight of less than 1,500, the number of acidic groups in the component (A) is preferably 1 or more and 50 or less, more preferably 1 or more and 20 or less, even more preferably 1 or more and 10 or less, and still more preferably 1 or more and 4 or less. <10> The regenerated collagen fiber treating agent composition according to <8> or <9>, wherein the component (A) preferably contains one or more compounds having an acidic group, selected from the group consisting of surfactants, polymers, and carboxylic acid compounds having a molecular weight of less than 1,500 (excluding surfactants).

[0142] <11> The regenerated collagen fiber treating composition according to <10>, wherein the surfactant used as component (A) preferably contains one or more surfactants selected from the group consisting of anionic surfactants and amphoteric surfactants, and satisfies the above (1). <12> The regenerated collagen fiber treating composition according to <11>, wherein the anionic surfactant preferably contains one or more surfactants selected from the group consisting of sulfate ester-type anionic surfactants and carboxylic acid-type anionic surfactants, more preferably contains one or more surfactants selected from the group consisting of alkyl or alkenyl sulfates, alkyl or alkenyl ether sulfates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, and N-acylamino acid salts, and even more preferably contains one or more surfactants selected from the group consisting of alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, and N-acylamino acid salts. <13> The regenerated collagen fiber treatment composition according to <11>, wherein the amphoteric surfactant preferably comprises at least one selected from the group consisting of an amine oxide amphoteric surfactant, a carboxybetaine amphoteric surfactant, and a sulfobetaine amphoteric surfactant, more preferably a carboxybetaine amphoteric surfactant, and even more preferably a fatty acid amidopropyl betaine.<14> The surfactant used as the component (A) preferably satisfies the above (1) and includes at least one selected from the group consisting of sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, amine oxide-type amphoteric surfactants, carboxybetaine-type amphoteric surfactants, and sulfobetaine-type amphoteric surfactants, more preferably at least one selected from the group consisting of alkyl or alkenyl sulfates, alkyl or alkenyl ether sulfates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, N-acylamino acid salts, and carboxybetaine-type amphoteric surfactants, and even more preferably at least one selected from the group consisting of alkyl sulfates, alkyl ether sulfates, amine oxide-type amphoteric surfactants, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, N-acylamino acid salts, and carboxybetaine-type amphoteric surfactants. The regenerated collagen fiber treating composition according to any one of <10> to <13>, which contains one or more selected from the group consisting of alkyl ether carboxylates, N-acylamino acid salts, and fatty acid amidopropyl betaines, and even more preferably one or more selected from the group consisting of sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium N-lauroylmethylalanine, lauric acid amidopropyl betaine [lauramidopropyl betaine], and palm kernel oil fatty acid amidopropyl betaine, coconut oil fatty acid amidopropyl betaine [cocamidopropyl betaine]. <15> The regenerated collagen fiber treating composition according to any one of <10> to <14>, wherein the polymer used as component (A) is a polymer other than component (B), and preferably contains one or more selected from the group consisting of anionic polymers and amphoteric polymers that satisfy the above (2). <16> The regenerated collagen fiber treating composition according to <15>, wherein the anionic polymer preferably comprises one or more selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid and anionic polysaccharides. <17> The regenerated collagen fiber treating composition according to <16>, wherein the anionic vinyl polymer containing structural units derived from (meth)acrylic acid comprises one or more selected from the group consisting of (meth)acrylic acid homopolymers and anionic (meth)acrylic acid copolymers.<18> The regenerated collagen fiber treating composition according to <17>, wherein the (meth)acrylic acid homopolymer comprises one or more selected from the group consisting of polyacrylic acid and polymethacrylic acid. <19> The regenerated collagen fiber treating composition according to <17>, wherein the anionic (meth)acrylic acid copolymer comprises one or more selected from the group consisting of (meth)acrylic acid / maleic acid copolymer, (meth)acrylic acid / itaconic acid copolymer, (meth)acrylic acid / fumaric acid copolymer, (meth)acrylic acid / vinyl acetate copolymer, (meth)acrylic acid / (meth)acrylic acid alkyl ester copolymer, (meth)acrylic acid / 2-hydroxyethyl methacrylate copolymer, acrylic acid / acrylic acid alkyl ester / (N-alkyl)acrylamide copolymer, carboxyvinyl polymer, (acrylates / alkyl acrylate (C10-30)) crosspolymer, (sodium acrylate / acryloyldimethyltaurine / dimethylacrylamide) crosspolymer, and acrylates crosspolymer-4. <20> The regenerated collagen fiber treatment composition according to any one of <16> to <19>, wherein the anionic polysaccharide used as the component (A) comprises at least one selected from the group consisting of polysaccharides having a carboxy group and sulfates of polysaccharides.

[0143] <21> The regenerated collagen fiber treating composition according to <20>, wherein the polysaccharide having a carboxy group comprises one or more selected from the group consisting of hyaluronic acid, alginic acid, pectinic acid, carboxymethylcellulose, and xanthan gum, and the sulfated polysaccharide comprises one or more selected from the group consisting of carrageenan, keratan sulfate, dermatan sulfate, sulfated starch, heparin, and heparan sulfate. <22> The regenerated collagen fiber treating composition according to any one of <16> to <21>, wherein the anionic polysaccharide preferably comprises one or more selected from the group consisting of carboxymethylcellulose, xanthan gum, and carrageenan, more preferably xanthan gum. <23> The regenerated collagen fiber treatment composition according to any one of <15> to <22>, wherein the anionic polymer used as the component (A) preferably contains one or more selected from the group consisting of polyacrylic acid and anionic polysaccharides, more preferably contains one or more selected from the group consisting of polyacrylic acid, carboxymethyl cellulose, xanthan gum, and carrageenan, and even more preferably contains polyacrylic acid. <24> The amphoteric polymer used as the component (A) is selected from the group consisting of methacryloylethyldimethylbetaine / methacryloylethyltrimethylammonium chloride / methoxypolyethylene glycol methacrylate copolymer (Polyquaternium-49), methacryloylethyldimethylbetaine / methacryloylethyltrimethylammonium chloride / 2-hydroxyethyl methacrylate copolymer (Polyquaternium-48), vinylpyrrolidone / N,N-dimethylaminoethyl diethyl methacrylate sulfate copolymer (Polyquaternium-11), N,N-dimethylaminoethyl diethyl methacrylate sulfate / N,N-dimethylacrylamide / polyethylene glycol dimethacrylate copolymer (Polyquaternium-52), dimethyldiallylammonium chloride / acrylic acid copolymer (Polyquaternium-22), acrylic acid / dimethyldiallylammonium chloride / acrylamide copolymer (Polyquaternium-39), acrylic acid / methyl acrylate / methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47),and acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53). <25> The regenerated collagen fiber treatment composition according to any one of <15> to <23>, wherein the amphoteric polymer used as the component (A) preferably contains one or more selected from the group consisting of structural units derived from (meth)acrylic acid and betaine groups, more preferably contains a structural unit derived from (meth)acrylic acid, even more preferably contains one or more selected from the group consisting of a dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), an acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), an acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), and an acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), and still more preferably contains an acrylic acid-dimethyldiallylammonium chloride-acrylamide copolymer (Polyquaternium-39). <26> The polymer used as the component (A) preferably satisfies the above (2) and includes at least one selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid, anionic polysaccharides, amphoteric polymers containing structural units derived from (meth)acrylic acid, and amphoteric polymers containing a betaine group, more preferably at least one selected from the group consisting of anionic vinyl polymers containing structural units derived from (meth)acrylic acid, anionic polysaccharides, and amphoteric polymers containing structural units derived from (meth)acrylic acid, and even more preferably polyacrylic acid, carboxymethyl cellulose, xanthan gum, carrageenan, dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47),and acrylic acid / acrylamide / methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), and even more preferably one or more selected from the group consisting of polyacrylic acid, xanthan gum, and acrylamide / acrylic acid / dimethyldiallylammonium chloride copolymer (Polyquaternium-39). <27> The regenerated collagen fiber treating composition of any one of <15> to <26>, wherein the carboxylic acid compound (excluding surfactants) having a molecular weight of less than 1,500 comprises one or more selected from the group consisting of 2-pyrrolidone-5-carboxylic acid, pyruvic acid, proline, serine, glycine, leucine, arginine, glutamic acid, and histidine, and preferably one or more selected from the group consisting of 2-pyrrolidone-5-carboxylic acid and pyruvic acid. <28> The component (A) preferably contains one or more selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group, and more preferably contains one or more selected from the group consisting of surfactants satisfying the above (1), polymers satisfying the above (2), and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1,500, and even more preferably contains one or more selected from the group consisting of alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, fatty acid amidopropyl betaines, and anilines containing structural units derived from (meth)acrylic acid. the surfactants are preferably at least one selected from the group consisting of anionic vinyl polymers, anionic polysaccharides, amphoteric polymers containing structural units derived from (meth)acrylic acid, amphoteric polymers containing a betaine group, and carboxylic acid compounds having a molecular weight of less than 1,500 (excluding surfactants), and even more preferably sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium N-lauroylmethylalanine, lauric acid amidopropyl betaine [lauramidopropyl betaine], palm kernel oil fatty acid amidopropyl betaine, coconut oil fatty acid amidopropyl betaine [cocamidopropyl betaine],A group consisting of polyacrylic acid, carboxymethylcellulose, xanthan gum, carrageenan, dimethyldiallylammonium chloride-acrylic acid copolymer (Polyquaternium-22), acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), acrylic acid-methyl acrylate-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-47), acrylic acid-acrylamide-methacrylamidopropyltrimethylammonium chloride copolymer (Polyquaternium-53), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid and more preferably, the regenerated collagen fiber treatment composition according to any one of <1> to <27>, which contains one or more selected from the group consisting of sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium N-lauroylmethylalanine, lauric acid amidopropyl betaine, polyacrylic acid, xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid. <29> The regenerated collagen fiber treating composition according to any one of <1> to <28>, wherein the content of component (A) in the treating composition is preferably 0.01% by mass to 40% by mass, more preferably 0.05% by mass to 30% by mass, even more preferably 0.1% by mass to 25% by mass, still more preferably 0.2% by mass to 20% by mass, even more preferably 0.5% by mass to 20% by mass, still more preferably 1.0% by mass to 20% by mass, still more preferably 1.5% by mass to 15% by mass, and still more preferably 2.0% by mass to 10% by mass. <30> The regenerated collagen fiber treating composition according to <29>, wherein, when component (A) contains a polymer, the content of component (A) in the treating composition is even more preferably 5% by mass to 10% by mass, even more preferably 7.5% by mass to 10% by mass.

[0144] <31> The regenerated collagen fiber treating composition according to any one of <1> to <30>, wherein the water content in the treating composition is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, still more preferably 80% by mass or more, and preferably 99.99% by mass or less. <32> The regenerated collagen fiber treating composition according to any one of <1> to <31>, wherein the treating composition contains, in addition to the above components, a cationic or nonionic surfactant, a cationic or nonionic polymer, and a higher alcohol. <33> The regenerated collagen fiber treating composition according to any one of <1> to <32>, wherein the pH of the treating composition is preferably 3.0 to 6.0, more preferably 3.5 to 6.0, even more preferably 4.0 to 6.0, and still more preferably 4.0 to 5.5. <34> The regenerated collagen fiber treatment composition according to any one of <1> to <33>, wherein the treatment composition is in the form of a liquid, mist, paste, cream, gel, foam, spray, or wax, and is preferably a liquid. <35> The regenerated collagen fiber treatment composition according to any one of <1> to <34>, wherein the component (B) comprises a copolymer containing structural units derived from one or more selected from the group consisting of unsaturated monocarboxylic acids and unsaturated dicarboxylic acids, and structural units derived from an aromatic vinyl compound, and preferably comprises one or more selected from the group consisting of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinylbenzoic acid-maleic acid copolymer, vinylbenzoic acid-acrylic acid copolymer, vinylbenzoic acid-methacrylic acid copolymer, and styrene-4-vinylbenzoic acid copolymer, and more preferably comprises styrene-maleic acid copolymer. <36> The regenerated collagen fiber treatment composition according to any one of <1> to <35>, wherein the molar ratio (u1 / u2) of the structural unit (u1) derived from the unsaturated monomer having a carboxy group to the structural unit (u2) derived from the aromatic vinyl compound monomer in the component (B) is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1.<37> The regenerated collagen fiber treating agent composition according to any one of <1> to <36>, wherein the acid value of the component (B) is preferably 100 mgKOH / g or more and 1,000 mgKOH / g or less, more preferably 200 mgKOH / g or more and 800 mgKOH / g or less, even more preferably 200 mgKOH / g or more and 600 mgKOH / g or less, still more preferably 300 mgKOH / g or more and 600 mgKOH / g or less, and still more preferably 400 mgKOH / g or more and 600 mgKOH / g or less. <38> The regenerated collagen fiber treating agent composition according to any one of <1> to <37>, wherein the weight average molecular weight of the component (B) is preferably 3,000 or more and 15,000 or less, more preferably 5,000 or more and 15,000 or less, even more preferably 6,000 or more and 15,000 or less, and still more preferably 6,000 or more and 10,000 or less. <39> The regenerated collagen fiber treating composition according to any one of <1> to <38>, wherein the content of component (B) in the modified regenerated collagen fiber is preferably 0.1% by mass to 70% by mass, more preferably 0.5% by mass to 65% by mass, even more preferably 1.0% by mass to 60% by mass, still more preferably 3.0% by mass to 55% by mass, even more preferably 5.0% by mass to 50% by mass, still more preferably 10% by mass to 45% by mass, still more preferably 15% by mass to 40% by mass, and even more preferably 20% by mass to 40% by mass. <40> The regenerated collagen fiber treating composition according to any one of <1> to <39>, wherein the modified regenerated collagen fiber further contains, as component (C), a polyvalent metal, or a salt or complex thereof.

[0145] <41> The regenerated collagen fiber treating composition according to <40>, wherein the component (C) comprises one or more polyvalent metals selected from the group consisting of calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt thereof, or a complex thereof, preferably one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt thereof, or a complex thereof, and more preferably aluminum, or a salt thereof, or a complex thereof. <42> The regenerated collagen fiber treating composition according to <40> or <41>, wherein the content of the component (C) in the modified regenerated collagen fiber is, in terms of the amount of metal element, preferably from 0.1 to 40% by mass, more preferably from 0.5 to 30% by mass, even more preferably from 1.0 to 20% by mass, and still more preferably from 2.0 to 10% by mass. <43> A method for treating regenerated collagen fibers, the treatment method comprising a step of applying a regenerated collagen fiber treatment composition to the regenerated collagen fibers, the treatment composition containing the following component (A) and water and having a pH of 2 or more and 6 or less, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B): (A) a compound having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, the number of phenolic hydroxyl groups being 2 or less, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+(44) A copolymer or salt thereof, which has: (1) a chelate stability constant log K with an ion of 2 or less; (2) a molecular weight of 1,500 or more; and (B) a copolymer comprising structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, and having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less. <44> A treatment method according to <43>, wherein the method of applying the treatment composition to regenerated collagen fibers comprises applying the composition to regenerated collagen fibers in a dry or wet state, or immersing regenerated collagen fibers in the composition, and preferably comprises immersing regenerated collagen fibers in a dry state in the composition. <45> The treatment method according to <43> or <44>, wherein the content of component (A) in the treatment composition is c [% by mass] and the amount of the treatment composition applied per 1 g of the dry mass of the fiber is b [g], and the total amount b × c / 100 [g] of component (A) applied per 1 g of the dry mass of the fiber is preferably 0.01 g or more and 10 g or less, more preferably 0.03 g or more and 5 g or less, even more preferably 0.05 g or more and 3 g or less, and still more preferably 0.1 g or more and 1 g or less. <46> The treatment method according to any one of <43> to <45>, wherein the amount of the treatment composition applied to the regenerated collagen fibers is, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass, a bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition), preferably 1:0.2 to 1:500, more preferably 1:0.2 to 1:200, even more preferably 1:0.5 to 1:100, and still more preferably 1:0.5 to 1:50. <47> The treatment method according to <46>, wherein, when the regenerated collagen fibers are immersed in the treatment composition, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition), when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass, is even more preferably 1:2 to 1:50, even more preferably 1:5 to 1:50, even more preferably 1:10 to 1:50, and still more preferably 1:10 to 1:40.<48> The treatment method of <46>, wherein, when the treatment composition is applied to regenerated collagen fibers, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition) is even more preferably 1:0.5 to 1:20, even more preferably 1:0.5 to 1:10, even more preferably 1:0.5 to 1:5, and even more preferably 1:0.5 to 1:3, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass. <49> The treatment method of any one of <44> to <46> and <48>, wherein, when the treatment composition is applied to regenerated collagen fibers, the application time is preferably 10 seconds or more and 10 minutes or less, more preferably 20 seconds or more and 5 minutes or less. <50> The treatment method according to any one of <44> to <46> and <48> to <49>, wherein after the treatment composition is applied to the regenerated collagen fibers, a step of leaving the composition to stand is further carried out, and the leaving time is preferably from 1 minute to 1 hour, more preferably from 3 minutes to 30 minutes, and even more preferably from 5 minutes to 20 minutes.

[0146] <51> The treatment method according to any one of <44> to <47>, wherein, when the regenerated collagen fibers are immersed in the treatment composition, the immersion time is preferably from 10 seconds to 3 hours, more preferably from 10 seconds to 2 hours, and even more preferably from 30 seconds to 90 minutes. <52> The treatment method according to any one of <43> to <51>, wherein the temperature when the treatment composition is applied to the regenerated collagen fibers is preferably from 5°C to 80°C, more preferably from 10°C to 60°C, even more preferably from 20°C to 50°C, and still more preferably from 30°C to 50°C. <53> The treatment method according to any one of <43> to <52>, comprising a step of rinsing away excess treatment composition applied to the regenerated collagen fibers after applying the treatment composition to the regenerated collagen fibers and before performing the next step. <54> The treatment method according to any one of <43> to <53>, comprising a step of drying the regenerated collagen fibers after applying the treatment composition to the regenerated collagen fibers, or after performing the rinsing step, if any. <55> A modified regenerated collagen fiber containing the following components (A) and (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+(56) The modified regenerated collagen fiber according to <55>, further comprising the component (C): a polyvalent metal, a salt thereof, or a complex thereof. <57> A fiber for a head ornament, comprising the modified regenerated collagen fiber according to <55> or <56>. <58> A head ornament, comprising the modified regenerated collagen fiber according to <55> or <56>. <59> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <60> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <61> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <62> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <63> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <64> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <65> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <66> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <67> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <68> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <69> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <70> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <71> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <72> A head ornament, comprising the modified regenerated collagen fiber according to <59> or <59>. <59> The fiber for a head accessory according to <57> or the head accessory according to <58>, wherein the head accessory is a hair wig, a hairpiece, a weaving, a hair extension, a braided hair, a hair accessory, or a doll hair.

[0147] <60> A regenerated collagen fiber treating composition, the treating composition comprising the following component (A) and water, and having a pH of 2 or more and 5.5 or less, the regenerated collagen fiber comprising modified regenerated collagen fibers containing, as component (B), one component selected from the following (B1) to (B3): (A) A compound (excluding component (B)) having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, the number of phenolic hydroxyl groups being 2 or less, and further satisfying at least one of the following (1) and (2), the compound including one or more selected from the following (A1) to (A4): (1) Al 3+(A1) One or more selected from sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, fatty acid amidopropyl betaine, (meth)acrylic acid homopolymers, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A2) One or more selected from alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, fatty acid amidopropyl betaine, polyacrylic acids having a weight-average molecular weight of 3000 to 50000, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A3) One or more selected from polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, N-lauroylmethylalanine sodium, lauric acid amidopropyl betaine (lauramidopropyl betaine), polyacrylic acid having a weight-average molecular weight of 3,000 to 50,000, xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid. (A4) One or more selected from polyoxyethylene lauryl ether acetate, polyacrylic acid having a weight-average molecular weight of 4,000 to 10,000, and 2-pyrrolidone-5-carboxylic acid. (B1) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g to 600 mgKOH / g and a weight-average molecular weight of 3,000 to 15,000. (B2) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 15,000 or less. (B3) A styrene-maleic acid copolymer or a salt thereof having an acid value of 400 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 10,000 or less.

[0148] <61> A method for treating regenerated collagen fibers, the treatment method comprising a step of applying a regenerated collagen fiber treatment composition to the regenerated collagen fibers, the treatment composition containing the following component (A) and water and having a pH of 2 or more and 5.5 or less, the regenerated collagen fibers comprising modified regenerated collagen fibers containing one component selected from the following (B1) to (B3) as component (B): (A) a compound (excluding component (B)) having a pKa value of 1 or more and 7 or less, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2), the compound including one or more selected from the following (A1) to (A4): (1) Al 3+(A1) one or more selected from sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, fatty acid amidopropyl betaine, (meth)acrylic acid homopolymers, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A2) one or more selected from alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, fatty acid amidopropyl betaine, polyacrylic acids having a weight-average molecular weight of 3000 to 50000, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A3) One or more selected from sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium lauroylmethylalanine, lauric acid amidopropyl betaine (lauramidopropyl betaine), polyacrylic acid having a weight-average molecular weight of 3,000 to 50,000, xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid. (A4) One or more selected from polyoxyethylene lauryl ether acetate, polyacrylic acid having a weight-average molecular weight of 4,000 to 10,000, and 2-pyrrolidone-5-carboxylic acid. (B1) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g to 600 mgKOH / g and a weight-average molecular weight of 3,000 to 15,000. (B2) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 15,000 or less. (B3) A styrene-maleic acid copolymer or a salt thereof having an acid value of 400 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 10,000 or less.

[0149] <62> A colored modified regenerated collagen fiber containing the following components (A) and (B): The modified regenerated collagen fiber is obtained by modifying a modified regenerated collagen fiber containing component (B) using a treatment composition containing component (A): (A) A compound (excluding component (B)) having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2), and including one or more compounds selected from the following (A1) to (A4): (1) Al 3+(A1) one or more selected from sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, fatty acid amidopropyl betaine, (meth)acrylic acid homopolymers, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A2) one or more selected from alkyl ether sulfates, alkyl ether carboxylates, N-acylamino acid salts, fatty acid amidopropyl betaine, polyacrylic acids having a weight-average molecular weight of 3000 to 50000, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1500 (excluding surfactants); (A3) One or more selected from sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, sodium lauroylmethylalanine, lauric acid amidopropyl betaine (lauramidopropyl betaine), polyacrylic acid having a weight-average molecular weight of 3,000 to 50,000, xanthan gum, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (Polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid. (A4) One or more selected from polyoxyethylene lauryl ether acetate, polyacrylic acid having a weight-average molecular weight of 4,000 to 10,000, and 2-pyrrolidone-5-carboxylic acid. (B1) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g to 600 mgKOH / g and a weight-average molecular weight of 3,000 to 15,000. (B2) A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 15,000 or less. (B3) A styrene-maleic acid copolymer or a salt thereof having an acid value of 400 mgKOH / g or more and 600 mgKOH / g or less and a weight average molecular weight of 6,000 or more and 10,000 or less.

[0150] <63> The regenerated collagen fiber treating agent composition of <60>, the treating method of <61>, or the modified regenerated collagen fiber of <62>, which contains component (A3) as component (A). <64> The regenerated collagen fiber treating agent composition of <60>, the treating method of <61>, or the modified regenerated collagen fiber of <62>, which contains component (A4) as component (A). <65> The regenerated collagen fiber treating agent composition of any one of <60> and <63> to <64>, the treating method of any one of <61> and <63> to <64>, or the modified regenerated collagen fiber of any one of <62> to <64>, which contains component (B2) as component (B). <66> The regenerated collagen fiber treatment composition according to any one of <60> and <63> to <64>, the treatment method according to any one of <61> and <63> to <64>, or the modified regenerated collagen fiber according to any one of <62> to <64>, which contains component (B3) as component (B).

[0151] <67> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <66>, a treatment method according to any one of <61> and <63> to <66>, or a modified regenerated collagen fiber according to any one of <62> to <66>, wherein the content of component (A) in the treatment composition is 0.2% by mass or more and 20% by mass or less. <68> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <67>, a treatment method according to any one of <61> and <63> to <67>, or a modified regenerated collagen fiber according to any one of <62> to <67>, wherein the content of component (A) in the treatment composition is 1.5% by mass or more and 5% by mass or less. <69> The regenerated collagen fiber treating agent composition of any one of <60> and <63> to <68>, the treating method of any one of <61> and <63> to <68>, or the modified regenerated collagen fiber of any one of <62> to <68>, wherein the content of component (B) in the modified regenerated collagen fiber is 20% by mass or more and 40% by mass or less. <70> The regenerated collagen fiber treating agent composition of any one of <60> and <63> to <69>, the treating method of any one of <61> and <63> to <69>, or the modified regenerated collagen fiber of any one of <62> to <69>, wherein the modified regenerated collagen fiber contains aluminum or a salt or complex thereof as component (C). <71> The regenerated collagen fiber treatment composition according to <70>, the treatment method according to <70>, or the modified regenerated collagen fiber according to <70>, wherein the content of component (C) in the modified regenerated collagen fiber is 2.0% by mass or more and 10% by mass or less as the amount of metal element.

[0152] <72> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <71>, a treatment method according to any one of <61> and <63> to <71>, or a modified regenerated collagen fiber according to any one of <62> to <71>, wherein, when the treatment composition is of a coating type, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the modified regenerated collagen fiber is from 2 to 7. <73> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <71>, a treatment method according to any one of <61> and <63> to <71>, or a modified regenerated collagen fiber according to any one of <62> to <71>, wherein, when the treatment composition is of a dip type, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the modified regenerated collagen fiber is from 0.03 to 5. <74> The regenerated collagen fiber treatment composition of any one of <60>, <63> to <71> and <73>, the treatment method of any one of <61>, <63> to <71> and <73>, or the modified regenerated collagen fiber of any one of <62> to <71> and <73>, wherein, when the treatment composition is of a dipping type, the mass ratio [(B) / (A)] of component (A) in the treatment composition to component (B) in the modified regenerated collagen fiber is 0.10 or more and 0.5 or less. <75> The regenerated collagen fiber treatment composition of any one of <60> and <63> to <72>, the treatment method of any one of <61> and <63> to <72>, or the modified regenerated collagen fiber of any one of <62> to <72>, wherein, when the treatment composition is a coating type, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the modified regenerated collagen fiber is 0.10 or more and 0.2 or less. <76> A treatment composition for regenerated collagen fibers according to any one of <60>, <63> to <71>, and <73> to <74>, a treatment method according to any one of <61>, <63> to <71>, and <73> to <74>, or a modified regenerated collagen fiber according to any one of <62> to <71>, and <73> to <74>, wherein, when the treatment composition is of a dipping type, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the modified regenerated collagen fiber is 0.005 or more and 1.0 or less.<77> A treatment composition for regenerated collagen fibers according to any one of <60>, <63> to <71>, <73> to <74> and <76>, a treatment method according to any one of <61>, <63> to <71>, <73> to <74> and <76>, or a modified regenerated collagen fiber according to any one of <62> to <71>, <73> to <74> and <76>, wherein, when the treatment composition is of a dipping type, the mass ratio [(C) / (A)] of component (A) in the treatment composition to component (C) in the modified regenerated collagen fiber is 0.03 or more and 0.1 or less.

[0153] <78> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <77>, or any one of <61> and <63> to <77>, wherein the water content in the treatment composition is 90% by mass or more. <79> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <78>, or any one of <61> and <63> to <78>, wherein the water content in the treatment composition is 90% by mass or more and 97% by mass or less. <80> A regenerated collagen fiber treatment composition according to any one of <60> and <63> to <79>, or any one of <61> and <63> to <79>, wherein the pH of the treatment composition is 2 or more and 4.5 or less.

[0154] The present invention will be described below with reference to examples, but the present invention is not limited to the scope of the examples. In the examples, various measurements and evaluations were carried out by the following methods.

[0155] <pH Measurement> The pH at 25° C. was measured using a pH meter (F-72, manufactured by Horiba Ltd.).

[0156] <Weight-Average Molecular Weight of Styrene-Maleic Acid Copolymer> In this specification, the weight-average molecular weight of the styrene-maleic acid copolymer was measured under the following conditions, and the weight-average molecular weight in terms of polystyrene was determined. (1) Reagents: Ultrapure water: water produced by an ultrapure water production system, Milli-Q, manufactured by Millipore Corporation; Dimethylformamide (DMF): special grade, manufactured by Kanto Chemical Co., Ltd.; Lithium bromide monohydrate (LiBr): special grade, manufactured by Kanto Chemical Co., Ltd.; Phosphoric acid: special grade, manufactured by Sigma-Aldrich Co., Ltd. (2) Sample Pretreatment Method: Approximately 50 mg of sample was precisely weighed, 0.5 mL of ultrapure water was added, and 10 mL of the mobile phase described below was added to dissolve the solution, which was then filtered to obtain a sample solution. (3) Measurement: Using the sample solution and standard solution, gel permeation chromatography (GPC) was performed under the following conditions to determine the weight-average molecular weight in terms of polystyrene. Flow rate: 1 mL / min Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr Column: TSKgel α (alpha) column (manufactured by Tosoh Corporation) Detector: RI (differential refractive index detector)

[0157] <Quantitative Analysis of Styrene-Maleic Acid Copolymer in Modified Regenerated Collagen Fibers> In this specification, quantitative analysis of the styrene-maleic acid copolymer in modified regenerated collagen fibers was performed using the following method. (1) Reagents: 1 mol / L aqueous sodium hydroxide solution: for volumetric analysis, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Ultrapure water: water produced by an ultrapure water production system, Milli-Q, manufactured by Millipore Corporation Dimethylformamide (DMF): special grade, manufactured by Kanto Chemical Co., Inc. Lithium bromide monohydrate (LiBr): special grade, manufactured by Kanto Chemical Co., Inc. Phosphoric acid: special grade, manufactured by Sigma-Aldrich (2) Sample Solution: The sample (modified regenerated collagen fiber) was conditioned at 20°C and a relative humidity of 65% for 24 hours, then finely chopped, and approximately 50 mg was precisely weighed out. 10 mL of 1 mol / L aqueous sodium hydroxide solution was added and the mixture was dissolved by heating at 50°C for 3 hours. The pH of the solution was adjusted to 4.7-5.3, and the freeze-dried sample was diluted with 0.5 mL of ultrapure water and 9.5 mL of the mobile phase described below. The diluted solution was filtered to prepare the sample solution. (3) Preparation of calibration curve solution: Separately, styrene-maleic acid copolymer was dissolved in the mobile phase described below to prepare a non-dissociated styrene-maleic acid copolymer with a concentration of 0.25-5.0 mg / mL, which was used as the standard solution for drawing the calibration curve. (4) Measurement: Using the sample solution and the standard solution, gel permeation chromatography (GPC) measurements were performed under the following conditions, and the peak areas of the sample solution and the standard solution were determined. A calibration curve was also prepared based on the peak area results of the standard solution. Flow rate: 0.8 mL / min Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr Column: TSKgel α (Alpha) column (manufactured by Tosoh Corporation) Detector: UV-visible spectrophotometer Measurement wavelength: 267 nm (5) Calculation of the amount of styrene-maleic acid copolymer The amount of styrene-maleic acid copolymer per mass of fiber was calculated using a calibration curve created based on the peak area derived from the styrene-maleic acid copolymer contained in the modified regenerated collagen fibers.

[0158] <Quantification of Aluminum in Modified Regenerated Collagen Fibers> In this specification, the quantification of aluminum in modified regenerated collagen fibers was performed using the following method. (1) Reagents: Sulfuric acid: precision analysis grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Hydrochloric acid: metal analysis grade, manufactured by Kanto Chemical Co., Ltd. Sodium carbonate: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Boric acid: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Aluminum standard solution: 1000 mg / L for atomic absorption spectrometry, manufactured by Kanto Chemical Co., Ltd. Ultrapure water: water produced by ultrapure water production system Milli-Q, manufactured by Millipore Corporation. (2) Sample Pretreatment Method: A fiber bundle of modified regenerated collagen fibers was hung in a dryer (SOFW-450SB, AS ONE Corporation) set to 60°C, a 250 g weight was attached to the bottom end of the fiber bundle, and the fiber was dried for 1 hour with tension applied to the entire fiber. The fiber was then removed from the dryer and conditioned at 20°C and 65% relative humidity for 24 hours. 0.1 g of sample (modified regenerated collagen fiber) was precisely weighed into a platinum crucible and heated until no white smoke was produced. Several drops of sulfuric acid were added, and the mixture was heated again until no white smoke was produced. It was then thoroughly incinerated in a 550°C electric furnace. 1 g of alkaline flux (sodium carbonate:boric acid = 1:0.4) was then added and melted in a 950°C electric furnace. A watch glass was placed over the sample, and 5 mL of ultrapure water and hydrochloric acid (6 mol / L) were added. The mixture was heated and dissolved on a hot plate at 70-80°C. After cooling, the solution was adjusted to a constant volume of 50 mL with ultrapure water. This solution was used as the measurement solution. (3) Preparation of Calibration Solutions: Calibration solutions ranging from 0.1 to 20 mg / L were prepared using an aluminum standard solution (1000 mg / L). Alkaline flux and hydrochloric acid were added to each solution to achieve the same concentration as the measurement solution. (4) Measurement: Using the prepared measurement solutions, each element was measured using an ICP atomic emission spectrometer under the following conditions. Analysis device: iCAP6500Duo (manufactured by Thermo Fisher Scientific) Wavelength: Al 396.152 nm RF power: 1150 W Coolant gas flow rate: 12 L / min Nebulizer flow rate: 0.70 L / min Auxiliary gas: 0.5 L / min Pump flow rate: 50 rpm

[0159] Production Example 1 (Production of Regenerated Collagen Fiber C0) Cattle split hide was solubilized with alkali according to a conventional method to prepare a spinning dope, which was then discharged from a spinning nozzle into a coagulation bath to produce regenerated collagen fibers. The regenerated collagen fibers were immersed in 30 parts by weight of an aqueous solution containing 5.0% by weight of aluminum sulfate 14-18 hydrate, 0.65% by weight of citric acid monohydrate, and 1.3% by weight of sodium hydroxide (component (C))) at 30°C with circulation, with the dry mass of the fiber calculated after conditioning at 20°C for 24 hours at a relative humidity of 65%, followed by addition of a 5% aqueous solution of sodium hydroxide in portions over approximately 1 to 5 hours to adjust the final pH of the solution to 4.5 to 5.0 after 5 hours. The regenerated collagen fibers were then retained in the solution for 3 hours and thoroughly washed with water to obtain regenerated collagen fiber C0.

[0160] Production Example 2 (Production of Modified Regenerated Collagen Fiber B1) The regenerated collagen fiber C0 obtained in Production Example 1 was treated according to the following procedure to obtain modified regenerated collagen fiber B1. (Procedure 1) Ten 30 cm long fiber bundles (amount that would result in a mass of 1.5 g when dried at 60°C for 1 hour and then left at 20°C and 65% RH for 12 hours) were prepared from the regenerated collagen fiber C0 for each Example. First, the following (Procedures 2) to (Procedure 5) were carried out using the B1a agent shown in Table 1. Agents B1a and B1b shown in Table 1 were prepared by blending and mixing the respective components listed in Table 1 using styrene-maleic acid copolymer (XIRAN1000HNa, manufactured by Polyscope, weight average molecular weight (Mw): 9195, acid value: 475 mg KOH / g, styrene / maleic acid molar ratio: 1 / 1) as component (B). (Procedure 2) The fiber bundles prepared in (Procedure 1) were immersed one bundle at a time in a separate container in an amount of agent B1a such that the bath ratio (mass of fiber bundle after drying in Procedure 1: mass of agent B1a) was 1:30, and the opening of each container was sealed. (Procedure 3) The container was immersed in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set at 40°C and allowed to stand for 5 minutes. The liquid temperature in the container was then raised to 40°C, and the container was then removed from the water bath. (Procedure 4) The container containing the fiber bundle was placed on a stirring rotor (VMR-5R, AS ONE Corporation) installed in a dryer (SOFW-450SB, AS ONE Corporation) set at 40°C, and the container was rotated at a rotation speed of 80 rpm, followed by heating and stirring for 6 hours. (Procedure 5) The container containing the fiber bundle was removed from the dryer and allowed to return to room temperature. The fiber bundle was then removed from the container, rinsed with running tap water at 30°C for 30 seconds, and the fiber flow was adjusted with a comb. (Procedure 6) The fiber bundle obtained in (Procedure 5) was subjected to (Procedure 2) to (Procedure 5) again, using the B1b agent shown in Table 1 instead of the B1a agent. However, the heating and stirring time in (Procedure 4) was set to 1 hour. (Procedure 7) The fiber bundles obtained in (Procedure 6) were hung one by one in a dryer set to 60°C, and a 250g weight was attached to the bottom end of each fiber bundle. Drying was performed for 1 hour with tension applied to the entire fiber. (Procedure 8) The fiber bundle was removed from the dryer, allowed to return to room temperature, and the weight was removed.

[0161]

[0162] The blending amounts (% by mass) listed in Table 1 are all amounts of active ingredients. The content of styrene-maleic acid copolymer in the modified regenerated collagen fiber B1 produced in Production Example 2 above was 31.4% by mass, and the content of aluminum was 5.5% by mass.

[0163] Examples 1 to 18, Comparative Examples 1 to 22 (Preparation of regenerated collagen fiber treatment compositions) The components shown in Tables 2 and 3 were blended in the blending ratios shown in the tables and mixed until uniform. The pH was then adjusted to the values ​​shown in the tables using hydrochloric acid or sodium hydroxide to prepare regenerated collagen fiber treatment compositions.

[0164] (Preparation of fiber bundle for evaluation) A fiber bundle for evaluation, 10 cm long and 1 g in mass, was prepared using modified regenerated collagen fiber B1 or regenerated collagen fiber C0. The fiber bundle was washed with plain shampoo having the following composition, rinsed with warm water at 40°C, and thoroughly dried with a hair dryer before being used for evaluation.

[0165] (Composition of plain shampoo) Ingredients (mass%) Polyoxyethylene (2) sodium lauryl ether sulfate (*1) 15.5 Lauric acid diethanolamide (*2) 1.5 Edetic acid tetrasodium salt 0.3 Sodium benzoate 1.43 Purified water Remaining amount Total 100.0 *1: Emar 227 (manufactured by Kao Corporation, 57.4 mass% as active ingredient 27 mass%) *2: Aminone L-02 (manufactured by Kao Corporation)

[0166] (Fiber Treatment) The treatment composition obtained in each example was used to treat modified regenerated collagen fiber B1 in Table 2 and regenerated collagen fiber C0, which does not correspond to modified regenerated collagen, in Table 3. Note that no fiber treatment was performed in Comparative Examples 3 and 22. The evaluation fiber bundle prepared by the above method was immersed in an amount of treatment composition such that the bath ratio (dry fiber mass:mass of treatment composition) was 1:30, where the fiber mass after conditioning at 20°C and 65% relative humidity for 24 hours was taken as the dry mass, and the container was sealed. The container was immersed in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set at 40°C and allowed to stand for the time indicated in each table, thereby performing fiber treatment. After standing, the fiber bundle was removed from the container, rinsed with warm water at 40°C, and thoroughly dried with a dryer to obtain a treated fiber bundle.

[0167] The fiber bundles before and after treatment with the treatment composition were evaluated in the following manner, and the results are shown in Tables 2 and 3.

[0168] <Elastic modulus of fiber in water> (Elastic modulus in water before treatment) (Procedure 1) Five fibers were cut from a fiber bundle, and 3 cm fiber pieces were collected from each, resulting in a total of five 3 cm fiber pieces. (Procedure 2) The fiber pieces were set in an automatic fiber tensile tester (MTT690, manufactured by DIA-STRON Limited). After the fiber was left immersed in water at 20°C for 30 minutes, automatic tensile measurement was started, and the elastic modulus of the fiber when tensile in water was determined. The cross-sectional area of ​​the fiber in water, which is necessary to determine the elastic modulus, was separately measured directly by observation under an optical microscope.

[0169] (Elastic modulus in water after treatment) Using the fiber bundles treated with the treatment composition of each example, fiber pieces were collected in the same manner as in the "Elastic modulus in water before treatment" section, and the elastic modulus in water was measured.

[0170] <Effect of Improving Elastic Modulus in Water> The value of the elastic modulus in water (MPa) after treatment minus the elastic modulus in water (MPa) before treatment is shown as the effect of improving elastic modulus in water in Tables 2 and 3. The larger the value, the greater the effect of the treatment composition in improving elastic modulus in water.

[0171] <Fiber Mass Reduction Rate After Treatment> The mass reduction rate was calculated from the mass of the fiber bundle before and after treatment with the treatment composition using the following formula, and is shown in Tables 2 and 3. The smaller the value, the smaller the mass reduction rate after treatment, i.e., the less fiber damage there was, and the better the results. The mass was measured after leaving the fiber bundle to stand for 24 hours or more in an environment of 20°C and 65% RH. Mass reduction rate (%) = {(Mass of fiber bundle before treatment) - (Mass of fiber bundle after treatment)} / (Mass of fiber bundle before treatment) x 100

[0172] <Shrinkage Percentage (%) After Contact with Water Vapor at 110°C> The shrinkage percentage after contact with water vapor at 110°C was measured using the following procedure. Evaluation was performed using a fiber bundle immediately after treatment with each treatment composition. (Procedure 1) Fibers were cut from the fiber bundle, and both ends of each bundle of five fibers were fixed with tape (Scotch tape, manufactured by 3M Corporation) to prepare a sample. The length of the fibers between the tapes was 10.0 cm. (Procedure 2) The sample was placed in an autoclave (model number: LSX-700, manufactured by Tomy Kogyo Co., Ltd.) and heated at 110°C for 10 minutes. (Procedure 3) The sample was removed, and the length h (cm) of the fibers between the tapes was measured. The percentage of shrinkage compared to the length before heating was calculated, and this was taken as the shrinkage percentage H (%) after contact with water vapor at 110°C. The closer H is to 0%, the less likely the sample is to shrink due to heat, indicating better heat resistance. Shrinkage after contact with water vapor at 110°C H (%) = [(10 - h) / 10] x 100 (where h is the length (cm) of the sample after heating at 110°C for 10 minutes).

[0173]

[0174]

[0175] The blending amounts (% by mass) shown in Tables 2 and 3 are all amounts of active ingredient. Note that the components (A) and (A') shown in Tables 2 and 3 were the components shown in Table 4.

[0176]

[0177] Tables 2 and 3 show that the specific modified regenerated collagen fibers treated with the treatment composition of the present invention exhibited a high effect of improving the modulus of elasticity in water and also exhibited little mass loss due to fiber treatment. Furthermore, with the exception of Example 8, the shrinkage rate after contact with water vapor at 110°C was also lower than that of untreated modified regenerated collagen fibers (Comparative Example 3). Visual observation of the treated hair bundles in the above examples revealed no discoloration. In contrast, the modified regenerated collagen fibers of Comparative Examples 1 and 2, which were treated with an acidic compound not corresponding to component (A), exhibited an effect of improving the modulus of elasticity in water, but exhibited a significant increase in the mass loss rate after treatment, despite the short treatment time. In Comparative Examples 4 to 21, in which regenerated collagen fibers other than the specific modified regenerated collagen fibers were treated with the treatment composition, no improvement in the modulus of elasticity in water was observed.

[0178] The effects of the present invention can also be achieved using the modified regenerated collagen fiber shown in Formulation Example 1. Formulation Example 1: XIRAN3000HNa (weight average molecular weight (Mw): 13,803, acid value: 285 mg KOH / g, styrene / maleic acid molar ratio: 3 / 1, manufactured by Polyscope) is used instead of XIRAN1000HNa (manufactured by Polyscope), and the regenerated collagen fiber C0 obtained in Production Example 1 is treated in the same manner as in Production Example 2 to obtain modified regenerated collagen fiber B2. Next, the modified regenerated collagen fiber B2 is treated in the same manner as in (fiber treatment) using the treating agent composition shown in Table 2.

[0179] According to the present invention, it is possible to provide a regenerated collagen fiber treatment composition that can improve the underwater elastic modulus of specific modified regenerated collagen fibers and suppress mass loss after treatment.

Claims

1. A regenerated collagen fiber treatment composition, comprising the following component (A) and water, and having a pH of 2 to 6, and the regenerated collagen fiber comprising modified regenerated collagen fiber containing the following component (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A copolymer having a chelate stability constant log K of 2 or less with an ion; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof.

2. The regenerated collagen fiber treatment composition according to claim 1, wherein component (A) comprises a compound having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group.

3. A regenerated collagen fiber treatment composition according to claim 1 or 2, wherein component (A) comprises one or more selected from the group consisting of surfactants that satisfy (1), polymers that satisfy (2), and carboxylic acid compounds (excluding surfactants) that have a molecular weight of less than 1,500 and that satisfy (1).

4. A regenerated collagen fiber treatment composition according to any one of claims 1 to 3, wherein the content of component (A) in the treatment composition is 0.01% by mass or more and 40% by mass or less.

5. A regenerated collagen fiber treatment composition according to any one of claims 1 to 4, wherein component (B) comprises a styrene-maleic acid copolymer.

6. A method for treating regenerated collagen fibers, the method comprising the step of applying a regenerated collagen fiber treating composition to the regenerated collagen fibers, the treating composition containing the following component (A) and water and having a pH of 2 to 6, the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3 in 100 g of water, having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A copolymer having a chelate stability constant log K of 2 or less with an ion; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof.

7. Modified regenerated collagen fibers containing the following components (A) and (B): (A) a compound having a pKa value of 1 to 7, a solubility of 1 g or more in 100 g of water at 25°C at pH 3, and having 2 or less phenolic hydroxyl groups, and further satisfying at least one of the following (1) and (2) (excluding component (B)): (1) Al 3+ (1) A copolymer having a chelate stability constant log K of 2 or less with an ion; (2) A molecular weight of 1,500 or more; (B) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof.

8. A head accessory product comprising the modified regenerated collagen fiber according to claim 7.

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