Treatment method for fibers for head ornament product including regenerated collagen fibers

Abstract

Provided is a treatment method for fibers for a head ornament product that include regenerated collagen fibers. The regenerated collagen fibers include modified regenerated collagen fibers that contain a prescribed component (X). The treatment method for the fibers for a head ornament product includes a step (I), a step (II), and a subsequent step (III). Step (I) is for applying a treatment agent composition A that contains a compound (A) that has a pKA value of 1–7 and water and has a pH of 2–6 to the fibers for a head ornament product, step (II) is for attaching a head ornament product that includes the fibers for a head ornament product to hair that has been dyed with a hair dye B, and step (III) is for wetting the hair and the fibers for a head ornament product while the hair and the fibers for a head ornament product are in contact.

Description

Method for treating fibers for headwear products containing regenerated collagen fibers

[0001] The present invention relates to a method for treating fibers for headwear products containing regenerated collagen fibers.

[0002] 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.

[0003] As a method for dyeing fibers, blended fibers containing cellulosic fibers and protein fibers are generally dyed with reactive dyes. For example, according to Patent Document 2, it is known that blended fibers containing rayon and wool can be dyed with reactive dyes to be a solid color with no pattern.

[0004] (Patent Document 1) Japanese Patent Application Laid-Open No. 2000-314084 (Patent Document 2) Japanese Patent Application Laid-Open No. 61-186580

[0005] The present invention relates to the following: [1] A method for treating fibers for head accessories containing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (X): (X) 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, the method comprising the following steps (I) to (III), and further comprising the following step (III) after steps (I) and (II). Step (I): applying a treatment composition A containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, to the fiber for a head accessory; Step (II): attaching a head accessory containing the fiber for a head accessory to hair dyed with hair dye B; and Step (III): wetting the hair and the fiber for a head accessory while they are in contact with each other. [2] A fiber treatment kit for a head accessory, comprising a treatment composition A for treating fiber for a head accessory containing regenerated collagen fibers, and a hair dye B for dyeing the hair, wherein the treatment composition A is a treatment composition containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, and the regenerated collagen fiber comprises modified regenerated collagen fiber containing the following component (X): (X) 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 mgKOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof. Detailed Description of the Invention

[0006] It has been found that treating regenerated collagen fibers with a modifier such as that disclosed in Patent Document 1 actually reduces the elastic modulus in water, making them more susceptible to breakage in a wet state. Furthermore, even in the case of blended fibers containing cellulosic fibers and protein-based fibers as disclosed in Patent Document 2, when blended fibers containing cellulosic fibers and regenerated protein fibers are dyed with reactive dyes, there is a problem in that mottled shading occurs under normal dyeing conditions, and a solid color cannot be obtained. The present inventors have discovered that this problem (the occurrence of shading in dyeing) also occurs when dyeing hair and regenerated collagen fibers.

[0007] The present invention relates to a method for treating fibers for head accessories, which can improve the underwater elastic modulus of fibers for head accessories containing regenerated collagen fibers, reduce the color difference between hair and the fibers for head accessories, and improve the color matching effect.

[0008] The present inventors discovered that the above-mentioned problems can be solved by a treatment method having specific steps, and have thus completed the present invention. The present invention provides a method for treating fibers for head accessories that improves the underwater elastic modulus of fibers for head accessories containing specific modified regenerated collagen fibers, making them less likely to break even when wet, and that reduces the color difference between hair and the fibers for head accessories, thereby improving color matching.

[0009] [Definition] As used herein, "the in-water elastic modulus of regenerated collagen fibers" refers to the tensile modulus of regenerated collagen fibers in water at 20°C. The tensile modulus can be evaluated specifically by the method described in the Examples. As used herein, "reducing the color difference between hair and fibers for head ornaments (including regenerated collagen fibers) and improving color compatibility" refers to a reduction in the color difference between hair and fibers for head ornaments after step (III) defined in the present invention, which is a step of moistening the hair and fibers for head ornaments while they are in contact with each other. This effect can be evaluated specifically by the method described in the Examples.

[0010] [Method for treating fibers for head accessories] The method for treating fibers for head accessories of the present invention (hereinafter also simply referred to as "the method of the present invention") is a method for treating fibers for head accessories containing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (X): (X) a copolymer comprising 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 or more and 15,000 or less, or a salt thereof, wherein the method comprises the following steps (I) to (III), and wherein the following step (III) is performed after the steps (I) and (II). Step (I): Applying a treatment composition A containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, to the fiber for a head accessory; Step (II): Attaching a head accessory containing the fiber for a head accessory to hair dyed with hair dye B; Step (III): Wetting the hair and the fiber for a head accessory while they are in contact with each other. The method of the present invention has the above-mentioned configuration, which improves the underwater elastic modulus of the fiber for a head accessory containing specific modified regenerated collagen fibers, reduces the color difference between the hair and the fiber for a head accessory, and improves the color matching effect.

[0011] The reason why the method of the present invention achieves the above-mentioned effects is unclear, but is presumed to be as follows. The fibers for head accessories to which the method of the present invention is applicable are regenerated collagen fibers containing modified regenerated collagen fibers containing the aforementioned component (X) (hereinafter simply referred to as "modified regenerated collagen fibers"). Component (X) acts as a modifier for the regenerated collagen fibers, improving their water resistance, strength, and other properties. Modified regenerated collagen fibers containing component (X) have carboxy groups within the fibers. Under low pH conditions, the proportion of undissociated (acidic) carboxy groups increases, improving the hydrophobicity of the fibers compared to when the proportion of dissociated (carboxy ion) carboxy groups is high, which is thought to result in an improved underwater modulus. Here, the treatment composition used in step (I) of the present invention has a pH of 2 to 6, and the compound (A) contained in the treatment composition has a pKa value of 1 to 7. In a treatment agent having a pH of 2 or more and 6 or less, compound (A) having the above pKa value exhibits buffering ability, and therefore, by treating modified regenerated collagen fibers with this treatment agent composition, it is thought that the pH inside the fibers can be effectively lowered and the proportion of non-dissociated (acid type) carboxyl groups can be increased in the structural portion derived from component (X) inside the fibers.

[0012] Furthermore, for example, when a head accessory is attached to a portion of the hair, the hair and the modified regenerated collagen fiber have different colors, and even if the hair and the modified regenerated collagen fiber are dyed with the same dye, they will dye differently. However, by using the method of the present invention, in step (III), the dye transfers from the hair dyed with hair dye B to the head accessory fiber containing the modified regenerated collagen fiber, which is thought to reduce the color difference between the hair and the head accessory fiber and improve the color matching effect. The mechanism of action of the present invention is not limited to the above.

[0013] <Head Accessory Product> In this specification, the term "head accessory product" refers to, for example, a hair wig, a toupee, weaving, a hair extension, a braided hair, a hair accessory, or a doll hair. Among these, from the viewpoint of effectively achieving the effects of the present invention, the head accessory product used in the present invention preferably includes at least one selected from the group consisting of a hair wig, a toupee, weaving, and a hair extension, and more preferably includes a hair extension. Furthermore, "fiber for head accessories" refers to the fiber used in the head accessory product. In this application, the fiber for head accessories also includes human hair. The head accessory product in this specification may contain at least a portion of modified regenerated collagen fiber as the fiber for head accessories. However, from the viewpoint of effectively achieving the effects of the present invention, it is preferable that the fiber for head accessories consists solely of modified regenerated collagen fiber.

[0014] <Modified Regenerated Collagen Fiber> The fibers for head accessories to be treated by the method of the present invention include regenerated collagen fibers. The regenerated collagen fibers include modified regenerated collagen fibers containing the following component (X): (X) 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.

[0015] (Component (X)) Component (X) is a modifier for regenerated collagen fibers. The regenerated collagen fibers to be modified by component (X) will be described later. Component (X) 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 (X) 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.

[0016] The structural unit derived from an aromatic vinyl compound in component (X) 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.

[0017] In component (X), the bonding state of the monomers that give each structural unit may be block bonding, random bonding, or a combination thereof.

[0018] Component (X) 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.

[0019] A preferred embodiment of component (X) is, for example, 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. Specific examples of component (X), from the viewpoint of improving the modulus of elasticity in water and improving color compatibility, 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.

[0020] In component (X), 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.

[0021] The acid value of component (X) is 100 mgKOH / g or more, and from the viewpoint of improving the underwater elastic modulus and the color matching effect, 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 (X) 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, even more preferably 400 mgKOH / g or more and 600 mgKOH / g or less. Here, the acid value refers to the number of milligrams of potassium hydroxide required to neutralize 1 g of sample.

[0022] Specific examples of component (X) 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

[0023] Component (X) has a weight average molecular weight of 1,500 or more and 15,000 or less. From the viewpoint of improving the underwater elastic modulus and improving the color matching effect, it 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. The weight average molecular weight of component (X) is 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 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. In this specification, the term "weight average molecular weight" 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.

[0024] (Content of component (X)) From the viewpoint of improving the underwater elastic modulus and improving the color matching effect, the content of component (X) 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, still 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, still 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, still more preferably 40% by mass or less. The content of component (X) 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.

[0025] Furthermore, in this specification, the quantification of component (X) in modified regenerated collagen fibers is carried out by selecting an appropriate method that does not decompose component (X) and that 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 drawn at an absorption wavelength suitable for quantifying component (X) is measured using, for example, GPC / UV, and the content of component (X) is calculated from the peak area. Specifically, the measurement can be carried out by the method described in the Examples.

[0026] (Component (Y): Polyvalent Metal, or Salt or Complex Thereof) From the viewpoint of firmly coordinating the component (X) inside the fiber to improve the modulus of elasticity in water and the color matching effect, the modified regenerated collagen fibers preferably further contain, in addition to the component (X), a polyvalent metal, or a salt or complex thereof as component (Y). Component (Y) also acts as a modifier for the regenerated collagen fibers. Examples of component (Y) 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 may be used alone or in combination of two or more. Among the above, from the viewpoint of improving water resistance, improving the modulus of elasticity in water, and improving the color matching effect, component (Y) preferably includes one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt or complex thereof, and more preferably includes aluminum, or a salt or complex thereof.

[0027] When the modified regenerated collagen fiber contains component (Y), the content of component (Y) in the modified regenerated collagen fiber is, in terms of the metal element amount, 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, from the viewpoints of improving water resistance, improving the underwater elastic modulus, and improving the color matching effect. It is also 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. The content of component (Y) in the modified regenerated collagen fiber is, in terms of the metal element amount, 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 (Y) in the modified regenerated collagen fiber is quantified, for example, as follows: The modified regenerated collagen fiber is incinerated, alkali-fused, and dissolved in acid to prepare a solution. The solution is then appropriately diluted to prepare a measurement sample, and the metal element content is quantified using an ICP emission spectrometer. The metal element content can be specifically measured by the method described in the Examples.

[0028] (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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] [Treatment with a fiber treatment agent containing component (Y)] The modified regenerated collagen fibers used in the present invention preferably contain the component (Y) from the viewpoint of improving water resistance, 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 treatment agent containing component (Y). The fiber treatment agent containing component (Y) is preferably an aqueous solution containing a polyvalent metal salt or polyvalent metal complex corresponding to component (Y). The polyvalent metal salt or polyvalent metal complex preferably contains an aluminum salt or aluminum complex, more preferably 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.

[0042] The content of the polyvalent metal salt and polyvalent metal complex in the fiber treatment agent is preferably 0.3 mass % or more and 5 mass % or less in terms of polyvalent metal oxide (aluminum oxide when the polyvalent metal is aluminum).

[0043] 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.

[0044] 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.

[0045] When treated with a fiber treatment agent containing component (Y), 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 the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass.

[0046] Furthermore, in this step, the treatment conditions for the regenerated collagen fibers may be set using as an index the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) in the regenerated collagen fibers. Specifically, for example, when treatment composition A is applied to the regenerated collagen fibers, from the viewpoint of improving permeability into the fibers and improving the treatment effect, this step may be performed under conditions such that the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) 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; 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 [(X) / (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. On the other hand, when the treatment composition A is immersed in the regenerated collagen fibers, this step may be carried out under conditions such that the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) in the regenerated collagen fibers is, from the viewpoint of improving penetration into the fibers and improving the treatment effect, 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, 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 [(X) / (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.

[0047] Furthermore, the treatment conditions for the regenerated collagen fibers can also be set using as an index the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) in the regenerated collagen fibers. Specifically, for example, when the treatment composition A is applied to the regenerated collagen fibers, from the viewpoint of improving permeability into the fibers and improving the treatment effect, the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) 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, 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 [(Y) / (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 A is immersed in the regenerated collagen fibers, this step can be carried out under conditions such that the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) in the regenerated collagen fibers is, from the viewpoint of improving penetration into the fibers and improving the treatment effect, 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 [(Y) / (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.

[0048] The temperature during treatment with the fiber treatment agent containing component (Y) (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.

[0049] The treatment time (immersion time) with the fiber treatment agent containing component (Y) 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, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less.

[0050] 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.

[0051] [Treatment with a fiber treatment agent containing component (X)] Regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (Y), are treated with a fiber treatment agent containing component (X) to obtain modified regenerated collagen fibers, which are the subject of the method of the present invention.

[0052] From the viewpoint of improving penetration into fibers and improving the treatment effect, the content of component (X) 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 (X) 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.

[0053] The fiber treatment agent containing component (X) 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.

[0054] The fiber treatment agent containing component (X) 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.

[0055] The pH of the fiber treatment agent containing component (X) 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 fibers, 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 fibers. The pH of the fiber treatment agent containing component (X) 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.

[0056] Treatment with a fiber treatment agent containing component (X) can be carried out by immersing regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (Y), in the fiber treatment agent containing component (X).

[0057] When treating with a fiber treatment agent containing component (X), the bath ratio of 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.

[0058] The temperature during treatment with a fiber treatment agent containing component (X) (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 (X) (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.

[0059] The treatment time (immersion time) with the fiber treatment agent containing component (X) 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 (X) 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.

[0060] Treatment with the fiber treatment agent containing component (X) 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.

[0061] 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.

[0062] The treatment with the fiber treatment agent containing component (X) 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 (Y) in the fiber treatment agent containing component (X); and (2) a step of removing the fibers immersed in the fiber treatment agent in step (1) and washing them with water.

[0063] 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.

[0064] 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.

[0065] The number of treatments with the fiber treatment agent containing component (X) 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.

[0066] By carrying out the above modification treatment, component (X) penetrates into the regenerated collagen fibers. Furthermore, when treatment is carried out with a fiber treatment agent containing component (Y), component (X) is strongly coordinated to the polyvalent metal in the fibers. When the method of the present invention is applied to fibers for head accessories containing the modified regenerated collagen fibers, the underwater elastic modulus of the fibers is improved, and the dye in hair dye B, described below, interacts with components (X) and (Y) to more easily remain in the modified regenerated collagen fibers, which is thought to further improve the color matching effect.

[0067] The regenerated collagen fibers to which the method of the present invention is applied may be those that contain 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 improving the underwater elastic modulus and improving the color matching effect, the regenerated collagen fibers to which the method of the present invention is applied are preferably fibers consisting solely of modified regenerated collagen fibers.

[0068] The method of the present invention comprises the following steps (I) to (III), with step (III) following steps (I) and (II): step (I) of applying to the fiber for a head ornament a treatment composition A containing a compound (A) having a pKa value of 1 or more and 7 or less and water, and having a pH of 2 or more and 6 or less; step (II) of wearing a head ornament containing the fiber for a head ornament on hair dyed with hair dye B; and step (III) of wetting the hair and the fiber for a head ornament while they are in contact with each other.

[0069] The fiber for head accessories subjected to steps (I) to (III) contains the modified regenerated collagen fiber. In step (III), the dye migrates from the hair dyed with hair dye B to the fiber for head accessories containing the modified regenerated collagen fiber, thereby dyeing the fiber for head accessories. This reduces the color difference between the hair and the fiber for head accessories, improving the color matching effect.

[0070] Here, the fiber for head accessories used in the method of the present invention may be colored or uncolored, but from the viewpoint of improving the color compatibility between the hair and the fiber for head accessories, it is preferable that the fiber be colored, for example, with a pigment.

[0071] The method of the present invention is either (1) a method comprising the steps (I), (II), and (III) in this order, or (2) a method comprising the steps (II), (I), and (III) in this order. In the method (1), the step (I) is performed before the step (II). That is, after applying the treatment composition A to a fiber for a head ornament (step (I)) and obtaining a head ornament containing the treated fiber for a head ornament, the head ornament is worn on hair dyed with hair dye B (step (II)), and then the hair and the fiber for a head ornament are kept in contact and wet (step (III)). A rinsing step or a washing step with a detergent may be performed between the steps (I) and (II), and a rinsing step is preferably performed. In the method (2), the step (I) is performed after the step (II). That is, after a head ornament containing the fiber for head ornaments is attached to hair dyed with hair dye B (step (II)), treatment composition A is applied to the fiber for head ornaments without removing the head ornament containing the fiber for head ornaments (step (I)) to obtain a head ornament containing dyed fiber for head ornaments. Next, the hair and the dyed fiber for head ornaments are brought into contact with each other and kept in a wet state (step (III)). In step (III), in which treatment composition A is applied to the head ornament containing the fiber for head ornaments, a conventional method such as wrapping the head ornament containing the fiber for head ornaments in aluminum foil, plastic wrap, or the like may be used. Among the above methods, method (1) is preferred from the viewpoint of ease of treatment.

[0072] <Step (I)> In step (I), the treatment composition A is applied to the fiber for head accessories. The fiber for head accessories contains regenerated collagen fibers including the modified regenerated collagen fibers.

[0073] (Treatment Composition A) Treatment composition A contains water and a compound (A) having a pKa value of 1 or more and 7 or less, and has a pH of 2 or more and 6 or less. Note that compound (A) is a compound other than component (X).

[0074] [Compound (A) Having a pKa Value of 1 or More and 7 or Less] Compound (A) has a pKa of 1 or more and 7 or less. Here, pKa is the acid dissociation exponent at 25°C. When compound (A) has multiple dissociation stages, the pKa of any stage may be 1 or more and 7 or less. The acid dissociation exponent pKa is the common logarithm of the reciprocal of the acid dissociation constant (Ka) - log Ka, and is a value described in Chemistry Handbook, Basics II, Revised 4th Edition, edited by the Chemical Society of Japan (published by Maruzen Co., Ltd.). If not described in the literature, it can be determined using a commercially available pH meter (e.g., F-23, manufactured by HORIBA, Ltd., temperature: 25°C) by the method described in the literature "FR Hartley, C. Burgess, and RM Alcock, "Solution Equilibria", John Wilery (1980)."

[0075] From the viewpoint of improving the underwater elastic modulus of the modified regenerated collagen fibers, the pKa of compound (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 compound (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.

[0076] From the viewpoint of improving the elastic modulus of the modified regenerated collagen fibers in water, the pKa of compound (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 treatment composition A. The pKa of compound (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 treatment composition A.

[0077] From the viewpoint of enabling the preparation of a highly concentrated treatment composition with high buffer capacity and further improving the underwater elastic modulus of the modified regenerated collagen fibers after treatment, compound (A) preferably has a solubility of 1 g or more, more preferably 2.5 g or more, even more preferably 5.0 g or more, and even more preferably 10 g or more in 100 g of water at 25°C at pH 3. There is no particular upper limit to the solubility, but it 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 has been adjusted to 3.0 at 25°C using hydrochloric acid or sodium hydroxide as a pH adjuster.

[0078] From the viewpoint of suppressing discoloration of the modified regenerated collagen fibers due to oxidation after treatment, compound (A) preferably has two or less phenolic hydroxyl groups, more preferably one or less, and even more preferably zero.

[0079] <Requirements (1) and (2)> Compound (A) preferably contains a compound (excluding component (X)) that satisfies at least one of the following requirements (1) and (2). When compound (A) satisfies at least one of the following requirements (1) and (2), it is believed that chelate formation between compound (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.

[0080] When compound (A) satisfies requirement (1), Al of compound (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 = [ML n-m] / ([M n+ ]×[L m- ]) is log K. 3+ The chelate stability constant log K with an ion 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.

[0081] When compound (A) satisfies requirement (2), the molecular weight of compound (A) is 1,500 or more. The molecular weight of compound (A) here means the weight-average molecular weight of compound (A) when compound (A) is a polymer. Furthermore, when compound (A) is a salt, the molecular weight of compound (A) does not include the molecular weight of the counter ion that forms the salt.

[0082] When the compound (A) satisfies the requirement (2), the molecular weight of the compound (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 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, from the viewpoint of preventing excessive viscosity that makes application to fibers difficult. When compound (A) satisfies requirement (2), the molecular weight of compound (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 compound (A) is a polymer, the weight average molecular weight of compound (A) refers to the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0083] From the viewpoint of improving the modulus of elasticity in water of the modified regenerated collagen fibers, compound (A) preferably comprises 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 comprises 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.

[0084] The number of acidic groups in compound (A) may be 1 or more. When compound (A) is a compound having a molecular weight of less than 1,500, the number of acidic groups in compound (A) is preferably 1 or more, and preferably 50 or less, more preferably 20 or less, even more preferably 10 or less, and still more preferably 4 or less. That is, the number 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.

[0085] 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, compound (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.

[0086] [Surfactant] The surfactant used as compound (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.

[0087] 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.

[0088] 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.

[0089] Among the anionic surfactants preferably used as compound (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.

[0090] 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.

[0091] 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).

[0092] Among the above, the surfactant used as compound (A) preferably satisfies the above (1) from the viewpoints of improving the modulus of elasticity of the modified regenerated collagen fiber in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage, 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. The composition preferably contains one or more 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 contains one or more selected from the group consisting of sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene lauryl ether sulfates, polyoxyethylene lauryl ether acetates, 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].

[0093] [Polymer] The polymer used as compound (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 (X).

[0094] The anionic polymer used as compound (A) preferably includes 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.

[0095] 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 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.

[0096] 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.

[0097] Examples of anionic polysaccharides used as compound (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.

[0098] 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 compound (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.

[0099] Examples of the amphoteric polymer used as compound (A) include 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-dimethylacrylic acid copolymer (Polyquaternium-12), and N,N-dimethylaminoethyl diethyl methacrylate sulfate-N,N-dimethylacrylic acid copolymer (Polyquaternium-13). 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.

[0100] 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).

[0101] Among the above, the polymer used as compound (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 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, The polyacrylic acid preferably contains at least one selected from the group consisting of 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 contains 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.

[0102] [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.

[0103] The compound (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, compound (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 lauryl sulfate. sodium lauryl sulfate, ammonium lauryl sulfate, 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, 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), 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.

[0104] [Content] 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 compound (A) in treatment composition A 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, and still more preferably 10% by mass or less. The content of compound (A) in treatment composition A 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. When compound (A) contains a polymer, the content of compound (A) in treatment composition A 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 modulus of elasticity of the modified regenerated collagen fibers in water, improving the effect of suppressing mass loss after treatment, and suppressing thermal shrinkage. When the compound (A) contains a polymer, the content of the compound (A) in the treatment composition A 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.

[0105] [Water] The water used in treatment composition A is not particularly limited, and for example, ion-exchanged water, pure water, distilled water, etc. can be used. The water content in treatment composition A is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, and even more preferably 80% by mass or more, and preferably 99.99% by mass or less. The water content in treatment composition A may be the remainder of compound (A).

[0106] [Other Components] In addition to the above-described components, treatment composition A 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, treatment composition A contains, in addition to the above-described components, a cationic or nonionic surfactant, a cationic or nonionic polymer, and a higher alcohol.

[0107] [pH] The pH of treatment composition A 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 treatment composition A 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 treatment composition A is preferably 3.0 or more, more preferably 3.5 or more, even more preferably 4.0 or more, but is 6 or less, preferably 5.5 or less. From the viewpoint of further improving the effect of suppressing mass loss after treatment and from the viewpoint of suppressing thermal shrinkage, the pH of treatment composition A is preferably 3.0 or more and 6 or less, more preferably 3.5 or more and 6 or less, even more preferably 4.0 or more and 6 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.

[0108] [Form, Production Method] The form of treatment composition A 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. Treatment composition A can be used as 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. Treatment composition A can be produced according to conventional methods.

[0109] (Treatment Method) In step (I), the method for applying treatment composition A to the regenerated collagen fibers may be any method that can bring treatment composition A into contact with the regenerated collagen fibers, and examples include a method of applying treatment composition A to dry or wet regenerated collagen fibers, and a method of immersing regenerated collagen fibers in treatment composition A. Of the above, the method of immersing dry regenerated collagen fibers in treatment composition A is preferred.

[0110] In step (I), when the content of compound (A) in treatment composition A is c [% by mass] and the amount of treatment composition A applied per 1 g of fiber is b [g], the total amount of compound (A) applied per 1 g 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 0.10 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 compound (A) in treatment composition A 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 compound (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%.

[0111] From the viewpoint of balancing treatment effect and economy, the amount of treatment composition A applied to the regenerated collagen fibers is preferably a bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition A) 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 a relative humidity of 65% for 24 hours is taken as the dry mass. When the regenerated collagen fibers are immersed in treatment composition A, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition A) 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 a relative humidity of 65% for 24 hours is taken as the dry mass. When applying treatment composition A to regenerated collagen fibers, the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition A) 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.

[0112] When treatment composition A is applied to 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.

[0113] After applying treatment composition A to the regenerated collagen fibers, it is preferable to further carry out a step of leaving the fibers 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.

[0114] When regenerated collagen fibers are immersed in treatment composition A, 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.

[0115] The temperature at which treatment composition A 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.

[0116] The method of the present invention may include a step of rinsing away excess treatment composition A applied to the regenerated collagen fibers after step (I) and before the next step (hereinafter simply referred to as the "rinsing step"). The rinsing step is carried out, for example, by rinsing away excess treatment composition A 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.

[0117] The method of the present invention preferably includes a step of drying the regenerated collagen fibers (hereinafter also referred to simply as a "drying step") after applying treatment composition A to the regenerated collagen fibers, or after a 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.

[0118] <Step (II)> In step (II), a head accessory product containing the fiber for a head accessory product is attached to hair dyed with hair dye B. The head accessory product attached to the hair in step (II) may be a head accessory product containing the modified regenerated collagen fiber after the treatment in step (I), or may be a head accessory product containing the modified regenerated collagen fiber before the treatment in step (I). The modified regenerated collagen fiber may be dyed in advance with a dye or the like, and preferably is dyed after the treatment in step (I). The head accessory product can be attached to the hair by any known method, depending on the type, shape, etc. of the head accessory product.

[0119] (Hair Dye B) The hair to which the head accessory is attached in step (II) is hair dyed with hair dye B. The entire hair does not need to be dyed with hair dye B; at least a portion of the hair needs to be dyed with hair dye B. However, from the viewpoint of improving the color compatibility between the hair and the head accessory fiber containing the modified regenerated collagen fiber, it is preferable that the entire hair be dyed with hair dye B. Hair dye B can be any hair dye that can dye hair, and commercially available hair dyes may be used. However, from the viewpoint of easily penetrating the dye in hair dye B into the head accessory fiber containing the modified regenerated collagen fiber when transferring it to the fiber, and from the viewpoint of improving the fastness of the head accessory fiber after dyeing, hair dye B is preferably a hair dye containing one or more dyes selected from the group consisting of oxidation dyes, acid dyes, and basic dyes, and more preferably a hair dye containing an oxidation dye. The oxidative dye, acid dye, and basic dye contained in hair dye B are preferably as follows, from the viewpoint of improving the dyeability and fastness of regenerated collagen fibers, including modified regenerated collagen fibers.

[0120] [Oxidation Dye] The oxidation dye is not particularly limited, and a precursor, a coupler, or a combination thereof known as an oxidation dye intermediate can be used. The oxidation dye preferably contains a coupler known as an oxidation dye intermediate.Examples of couplers include metaphenylenediamine, 2,4-diaminophenoxyethanol, 2-amino-4-(2-hydroxyethylamino)anisole [=2-amino-4-(β-hydroxyethyl)aminoanisole], 2,4-diamino-5-methylphenetole, 2,4-diamino-5-(2-hydroxyethoxy)toluene, 2,4-dimethoxy-1,3-diaminobenzene, 2,6-bis(2-hydroxyethylamino)toluene, and 2,4-diamino-5-fluorotoluene. , 1,3-bis(2,4-diaminophenoxy)propane, meta-aminophenol, 2-methyl-5-aminophenol [=5-amino-orthocresol], 2-methyl-5-(2-hydroxyethylamino)phenol, 2,4-dichloro-3-aminophenol, 2-chloro-3-amino-6-methylphenol, 2-methyl-4-chloro-5-aminophenol, N-cyclopentyl-meta-aminophenol, 2-methyl-4-methoxy-5-(2-hydroxyethylamino)phenol, 2 -methyl-4-fluoro-5-aminophenol, resorcinol, 2-methylresorcinol, 4-chlororesorcinol, 1-naphthol, 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2-isopropyl-5-methylphenol, 4-hydroxyindole, 5-hydroxyindole, 6-hydroxyindole, 7-hydroxyindole, 6-hydroxybenzomorpholine, 3,4-methylenedioxyphenol, 2-bromo-4,5- Examples thereof include one or more selected from the group consisting of methylenedioxyphenol, 3,4-methylenedioxyaniline, 1-(2-hydroxyethyl)amino-3,4-methylenedioxybenzene, 2,6-dihydroxy-3,4-dimethylpyridine, 2,6-dimethoxy-3,5-diaminopyridine, 2,3-diamino-6-methoxypyridine, 2-methylamino-3-amino-6-methoxypyridine, 2-amino-3-hydroxypyridine, 2,6-diaminopyridine, and salts thereof.

[0121] In this specification, the term "coupler" does not include compounds having a catechin structure. The term "catechin structure" as used herein specifically refers to a structure represented by the following general formula (I):

[0122]

[0123] (In the formula, R A and R B are each independently a hydrogen atom or a hydroxy group. C is a hydrogen atom or an acyl group, and R D is a hydrogen atom or a ring structure-containing group.

[0124] R C The acyl group in R is preferably a group represented by the following general formula (II): D The ring structure-containing group in the formula (III) is preferably a group represented by the following formula (III).

[0125]

[0126]

[0127] (In the above formula, * indicates a bond. R A ~R C is the same as above.)

[0128] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the oxidation dye is preferably an oxidation dye intermediate (B) containing one or more selected from the group consisting of the following components (B1) and (B2): (B1) one or more selected from the group consisting of couplers (B1-1) having a benzene ring, electron-donating groups at the 1st and 3rd positions on the benzene ring, and hydrogen atoms at the 4th and 6th positions, couplers (B1-2) having a pyridine ring, electron-donating groups at the 2nd and 6th positions on the pyridine ring, and hydrogen atoms at the 3rd and 5th positions, and couplers (B1-3) represented by the following general formula (B13):

[0129]

[0130] (In formula (B13), R 11 is -O-(CH2) nR is a divalent group represented by —O— (n is a number of 2 or more and 10 or less). 12 , R 14 , R 22 and R 24 is an electron donating group, R 15 and R 25 is a hydrogen atom. 13 , R 16 , R 23 and R 26 are each independently a hydrogen atom, an alkyl group, or an electron-donating group.

[0131] (B2) One or more couplers other than the component (B1), selected from the group consisting of couplers (B2-1) having a benzene ring, electron-donating groups at the 1- and 2-positions on the benzene ring, and hydrogen atoms at two or more of the 3- to 6-positions, and couplers (B2-2) having a pyridine ring, electron-donating groups at the 2- and 3-positions on the pyridine ring, and hydrogen atoms at two or more of the 4- to 6-positions.

[0132] Component (B1) is a coupler having a specific structure, and due to this structure, component (B1) is likely to form a reaction product of a trimer or higher. Similarly, the coupler of component (B2) is likely to form a reaction product of a dimer or higher due to its specific structure. Therefore, when one or more oxidation dye intermediates (B) selected from the group consisting of components (B1) and (B2) are used, high-molecular-weight reaction products are likely to be produced inside the fiber, which is thought to improve fastness.

[0133] [Component (B1)] Component (B1) is at least one selected from the group consisting of couplers (B1-1) having a benzene ring, electron-donating groups at the 1- and 3-positions on the benzene ring, and hydrogen atoms at the 4- and 6-positions; couplers (B1-2) having a pyridine ring, electron-donating groups at the 2- and 6-positions on the pyridine ring, and hydrogen atoms at the 3- and 5-positions; and couplers (B1-3) represented by the following general formula (B13):

[0134]

[0135] (In formula (B13), R 11 is -O-(CH2) nR is a divalent group represented by —O— (n is a number of 2 or more and 10 or less). 12 , R 14 , R 22 and R 24 is an electron donating group, R 15 and R 25 is a hydrogen atom. 13 , R 16 , R 23 and R 26 are each independently a hydrogen atom, an alkyl group, or an electron-donating group.

[0136] Examples of the electron-donating group in component (B1) include a hydroxy group, a hydroxyalkyl group, an alkoxy group, a hydroxyalkoxy group, a primary to tertiary amino group, an alkylamino group, and a hydrocarbon ring structure having aromaticity.

[0137] <Coupler (B1-1)> The coupler (B1-1) preferably includes a compound represented by the following general formula (B11).

[0138]

[0139] (In formula (B11), R 1 is an electron donating group attached to the carbon atom at the 1st position, R 2 represents a hydrogen atom, an alkyl group or an electron-donating group bonded to the carbon atom at the 2-position, R 3 is an electron donating group attached to the 3-position carbon, R 4 is a hydrogen atom, an alkyl group, or an electron-donating group bonded to the carbon atom at the 5-position. 2 and R 3 may be bonded to each other to form a hydrocarbon ring structure having aromaticity.

[0140] The electron-donating group in general formula (B11) preferably contains one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group, an alkoxy group, a hydroxyalkoxy group, a primary to tertiary amino group, an alkylamino group, and a hydrocarbon ring structure having aromaticity, more preferably contains one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group having from 2 to 8 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, a hydroxyalkoxy group having from 2 to 8 carbon atoms, a primary amino group (-NH2), and an alkylamino group having from 1 to 8 carbon atoms, and even more preferably contains one or more selected from the group consisting of a hydroxy group and a primary amino group (-NH2). The alkyl group preferably contains an alkyl group having from 1 to 8 carbon atoms, more preferably an alkyl group having from 1 to 3 carbon atoms, and even more preferably a methyl group. The hydrocarbon ring structure having aromaticity is represented by R in general formula (B11). 2 and R 3 are bonded to each other to form an aromatic hydrocarbon ring structure, the ring structure includes an aromatic hydrocarbon ring structure having from 5 to 8 ring carbon atoms, more preferably an aromatic hydrocarbon ring structure having from 5 to 6 ring carbon atoms, and even more preferably an aromatic hydrocarbon ring structure having 6 ring carbon atoms.

[0141] In the general formula (B11), R 1 is preferably a hydroxy group or a primary amino group (—NH2). 2 is preferably a hydrogen atom or a methyl group, R 3 is preferably a hydroxy group or a primary amino group (—NH2). 2 and R 3 are bonded to each other to form an aromatic hydrocarbon ring structure having 6 ring carbon atoms. 4 is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

[0142] Specific examples of the compound represented by the general formula (B11) include one or more compounds selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, and 1-naphthol, and preferably include one or more compounds selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol.

[0143] <Coupler (B1-2)> The coupler (B1-2) preferably includes a compound represented by the following general formula (B12).

[0144]

[0145] (In formula (B12), R 5 is an electron donating group attached to the 2-position carbon, R 6 represents a hydrogen atom, an alkyl group or an electron-donating group bonded to the carbon atom at the 4-position, R 7 is an electron donating group attached to the 6-carbon atom.)

[0146] The electron-donating group in general formula (B12) preferably includes one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group, an alkoxy group, a hydroxyalkoxy group, a primary to tertiary amino group, and an alkylamino group, more preferably includes one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group having from 2 to 8 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, a hydroxyalkoxy group having from 2 to 8 carbon atoms, a primary amino group (-NH), and an alkylamino group having from 1 to 8 carbon atoms, even more preferably includes one or more selected from the group consisting of a hydroxy group and a primary amino group (-NH). The alkyl group preferably includes an alkyl group having from 1 to 8 carbon atoms, more preferably an alkyl group having from 1 to 3 carbon atoms, and even more preferably a methyl group.

[0147] In the general formula (B12), R 5 is preferably a hydroxy group or a primary amino group (—NH), and R 6 is preferably a hydrogen atom or a methyl group. 7is preferably a primary amino group (—NH2). A specific example of the compound represented by general formula (B12) is 2,6-diaminopyridine.

[0148] <Coupler (B1-3)> The coupler (B1-3) includes a compound represented by the following general formula (B13).

[0149]

[0150] (In formula (B13), R 11 is -O-(CH2) n R is a divalent group represented by —O— (n is a number of 2 or more and 10 or less). 12 , R 14 , R 22 and R 24 is an electron donating group, R 15 and R 25 is a hydrogen atom. 13 , R 16 , R 23 and R 26 are each independently a hydrogen atom, an alkyl group, or an electron-donating group.

[0151] The electron-donating group, the alkyl group, and preferred embodiments thereof in general formula (B13) are the same as those in general formula (B12).

[0152] In general formula (B13), R 11 In the formula, n is preferably 2 or more and 8 or less, more preferably 2 or more and 4 or less. 12 , R 14 , R 22 and R 24 The electron donating group in R preferably comprises a hydroxy group or a primary amino group (—NH), and more preferably is a primary amino group (—NH). 13 , R 16 , R 23 and R 26 preferably contains a hydrogen atom or a methyl group, and more preferably is a hydrogen atom. A specific example of the coupler represented by general formula (B13) is 1,3-bis(2,4-diaminophenoxy)propane.

[0153] Component (B1) can be one or more selected from the group consisting of the couplers (B1-1), (B1-2), and (B1-3). Among the above, component (B1) preferably includes one or more selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, 1-naphthol, 2,6-diaminopyridine, and 1,3-bis(2,4-diaminophenoxy)propane, and more preferably includes one or more selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol.

[0154] [Component (B2)] Component (B2) is a coupler other than the component (B1), and is at least one selected from the group consisting of couplers (B2-1) having a benzene ring, electron-donating groups at the 1- and 2-positions on the benzene ring, and hydrogen atoms at two or more of the 3- to 6-positions, and couplers (B2-2) having a pyridine ring, electron-donating groups at the 2- and 3-positions on the pyridine ring, and hydrogen atoms at two or more of the 4- to 6-positions.

[0155] <Coupler (B2-1)> The coupler (B2-1) preferably includes a compound represented by the following general formula (B21): However, couplers corresponding to the above-mentioned component (B1) are excluded.

[0156]

[0157] (In formula (B21), R 31 is an electron donating group attached to the carbon atom at the 1st position, R 32 is an electron donating group attached to the 2-position carbon, R 33 ~R 36 are hydrogen atoms, alkyl groups, or electron-donating groups bonded to the 3-, 4-, 5-, and 6-position carbons, respectively. 33 ~R 36 At least two of these are hydrogen atoms.)

[0158] The electron-donating group in general formula (B21) preferably includes one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group, an alkoxy group, a hydroxyalkoxy group, a primary to tertiary amino group, and an alkylamino group, more preferably includes one or more selected from the group consisting of a hydroxy group, a hydroxyalkyl group having from 2 to 8 carbon atoms, an alkoxy group having from 1 to 8 carbon atoms, a hydroxyalkoxy group having from 2 to 8 carbon atoms, a primary amino group (-NH), and an alkylamino group having from 1 to 8 carbon atoms, even more preferably includes one or more selected from the group consisting of a hydroxy group, a hydroxyalkoxy group having from 2 to 8 carbon atoms, and a primary amino group (-NH). The alkyl group preferably includes an alkyl group having from 1 to 8 carbon atoms, more preferably an alkyl group having from 1 to 3 carbon atoms, and even more preferably a methyl group.

[0159] In general formula (B21), R 31 is preferably a hydroxy group, a hydroxyalkoxy group having from 2 to 8 carbon atoms, or a primary amino group (—NH), and more preferably a hydroxy group, a hydroxyethoxy group, or a primary amino group (—NH). 32 is preferably a hydroxy group or a primary amino group (-NH2), more preferably a primary amino group (-NH2).

[0160] Specific examples of the compound represented by formula (B21) include orthoaminophenol and 2,4-diaminophenoxyethanol.

[0161] <<Coupler (B2-2)>> The coupler (B2-2) preferably includes a compound represented by the following general formula (B22).

[0162]

[0163] (In formula (B22), R 37 is an electron donating group attached to the 2-position carbon, R 38 is an electron donating group attached to the 3-carbon atom. 39 ~R 41 are hydrogen atoms, alkyl groups, or electron-donating groups bonded to the 4-, 5-, and 6-position carbons, respectively. 39~R 41 At least two of these are hydrogen atoms.)

[0164] The electron-donating group, the alkyl group, and preferred embodiments thereof in formula (B22) are the same as those in formula (B21).

[0165] In the general formula (B22), R 37 is preferably a hydroxy group or a primary amino group (—NH), and R 38 is preferably a hydroxy group or a primary amino group (—NH), more preferably a primary amino group (—NH). 39 ~R 41 are each independently preferably a hydrogen atom or a methyl group, more preferably R 39 ~R 41 are all hydrogen atoms. Specific examples of the compound represented by general formula (B22) include 2,3-diaminopyridine, 2-amino-3-hydroxypyridine, and salts thereof.

[0166] Component (B2) can be one or more selected from the group consisting of the couplers (B2-1) and (B2-2). Of the above, component (B2) preferably contains coupler (B2-1), and more preferably contains one or more selected from the group consisting of ortho-aminophenol and 2,4-diaminophenoxyethanol.

[0167] Among the above, from the viewpoint of compatibility, the oxidation dye intermediate (B) preferably contains component (B1), more preferably contains one or more selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, 1-naphthol, 2,6-diaminopyridine, and 1,3-bis(2,4-diaminophenoxy)propane. Also, the oxidation dye intermediate (B) preferably contains coupler (B1-1), more preferably contains one or more selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol.

[0168] From the viewpoint of improving dyeability and fastness, the total content of component (B1) and component (B2) in the oxidation dye intermediate (B) is preferably 30% by mass or more, more preferably 40% by mass or more, and 100% by mass or less. Furthermore, when the oxidation dye intermediate (B) contains another oxidation dye intermediate (for example, a precursor of component (B3) described below), the total content of component (B1) and component (B2) in the oxidation dye intermediate (B) may be, for example, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0169] From the viewpoint of improving dyeability and fastness, the content of component (B1) in the oxidation dye intermediate (B) is preferably 30% by mass or more, more preferably 40% by mass or more, and 100% by mass or less. The content of component (B1) in the oxidation dye intermediate (B) may be, for example, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0170] [Component (B3): Precursor] From the viewpoint of further improving dyeability and fastness, the oxidation dye intermediate (B) preferably further contains component (B3): precursor as an oxidation dye intermediate other than components (B1) and (B2). The precursor can be any compound known as a precursor of an oxidation dye intermediate, without any limitation, and examples thereof include paraphenylenediamine, toluene-2,5-diamine, orthochloroparaphenylenediamine, N-phenylparaphenylenediamine, N,N-bis(hydroxyethyl)paraphenylenediamine, 3-methyl-4-aminophenol, 2-hydroxyethylparaphenylenediamine, paraaminophenol, paramethylaminophenol, 4-amino-metacresol, and salts thereof.

[0171] Among the above, from the viewpoint of further improving dyeability and fastness when used in combination with the couplers of components (B1) and (B2), component (B3) preferably contains one or more selected from the group consisting of toluene-2,5-diamine, para-aminophenol, 4-amino-metacresol, 1-hydroxyethyl-4,5-diaminopyrazole, and salts thereof.

[0172] When the oxidation dye intermediate (B) contains component (B3), the content of component (B3) in the oxidation dye intermediate (B) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, from the viewpoint of further improving dyeability and fastness. When the oxidation dye intermediate (B) contains component (B3), the content of component (B3) in the oxidation dye intermediate (B) is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 65% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.

[0173] The oxidation dye intermediate (B) may further contain a coupler other than the components (B1) and (B2). However, from the viewpoint of further improving dyeability and fastness, the total content of the components (B1) to (B3) in the oxidation dye intermediate (B) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably 98% by mass or more, but not more than 100% by mass. That is, the content of couplers other than the components (B1) and (B2) in the oxidation dye intermediate (B) is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably 2% by mass or less, and may even be 0% by mass.

[0174] The molecular weight of the oxidation dye intermediate (B), as a non-dissociated type, is preferably 95 or more, more preferably 100 or more, and even more preferably 105 or more, from the viewpoint of further improving dyeability and fastness, and from the viewpoint of efficiently penetrating into the interior of the fiber and further improving dyeability, the molecular weight of the non-dissociated type is preferably 500 or less, more preferably 300 or less, and even more preferably 200 or less. The molecular weight of the oxidation dye intermediate (B), as a non-dissociated type, is preferably 95 or more and 500 or less, more preferably 100 or more and 300 or less, and even more preferably 105 or more and 200 or less. The molecular weight of the oxidation dye intermediate (B) means the molecular weight of each oxidation dye intermediate in the oxidation dye intermediate (B), and it is preferable that the molecular weights of the non-dissociated types of the components (B1), (B2), and (B3) are all within the above range. Furthermore, the molecular weight of the oxidative dye intermediate (B) in its non-dissociated form means the molecular weight of the oxidative dye intermediate (B) in its non-ionic state, even when the oxidative dye intermediate (B) is a salt, and does not include the molecular weight of the counter ion. This also includes cases where the oxidative dye intermediate (B) has an onium group such as a quaternary ammonium group, but in such cases, the counter ion is similarly not included in the molecular weight.

[0175] When the dye used in hair dye B includes an oxidation dye, hair dye B is preferably a multi-component hair dye comprising a first component and a second component, where the first component contains the oxidation dye intermediate (B), an alkaline agent, and water, and the second component contains hydrogen peroxide and water.

[0176] [Alkaline Agent] The alkaline agent used in the first agent may be either an inorganic alkaline agent or an organic alkaline agent. Examples of the alkaline agent include ammonia; alkanolamines such as mono-, di-, or trimethanolamine, mono-, di-, or triethanolamine; alkylamines such as methylamine, dimethylamine, ethylamine, diethylamine, N-methylethylamine, propylamine, and butylamine; aralkylamines such as benzylamine; and inorganic alkaline compounds such as sodium hydroxide and potassium hydroxide. One or more of these may be used. From the viewpoint of water solubility, the number of carbon atoms in the alkanolamine, alkylamine, or aralkylamine is preferably 10 or less, more preferably 8 or less. Among the above, from the viewpoint of efficiently penetrating the oxidation dye intermediate (B) into the interior of the fiber to further improve dyeability and fastness, the alkaline agent preferably includes one or more selected from the group consisting of ammonia, alkanolamine, alkylamine, aralkylamine, sodium hydroxide, and potassium hydroxide, and more preferably includes one or more selected from the group consisting of ammonia and alkanolamine.

[0177] [Water] The water used in the first agent is not particularly limited, and for example, ion-exchanged water, pure water, distilled water, etc. can be used.

[0178] [Other Components] In addition to the above-mentioned components, the first agent may contain antioxidants, fragrances, preservatives, thickeners, pH adjusters, surfactants, texture improvers, and the like.

[0179] The content of each component in the first pack is preferably within the following range: From the viewpoint of improving dyeability, the content of the oxidation dye intermediate (B) in the first pack is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more, and from the viewpoint of improving formulation stability, it is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 2.0% by mass or less. The content of the oxidation dye intermediate (B) in the first agent is preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 0.02% by mass or more and 3.0% by mass or less, even more preferably 0.05% by mass or more and 3.0% by mass or less, still more preferably 0.1% by mass or more and 3.0% by mass or less, still more preferably 0.2% by mass or more and 3.0% by mass or less, still more preferably 0.3% by mass or more and 3.0% by mass or less, and still more preferably 0.5% by mass or more and 2.0% by mass or less.

[0180] From the viewpoint of improving dyeability, the total content of component (B1) and component (B2) in the first agent is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and still more preferably 0.25% by mass or more, and from the viewpoint of improving formulation stability, it is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, still more preferably 1.5% by mass or less, and still more preferably 1.0% by mass or less. The total content of component (B1) and component (B2) in the first agent is preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 0.02% by mass or more and 3.0% by mass or less, even more preferably 0.05% by mass or more and 2.0% by mass or less, still more preferably 0.1% by mass or more and 1.5% by mass or less, still more preferably 0.2% by mass or more and 1.5% by mass or less, and still more preferably 0.25% by mass or more and 1.0% by mass or less.

[0181] From the viewpoint of improving dyeability and fastness, the content of the alkaline agent in the first agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, from the viewpoint of maintaining constant reactivity, it is preferably 10% by mass or less, more preferably 7.5% by mass or less, and even more preferably 5.0% by mass or less. The content of the alkaline agent in the first agent is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7.5% by mass or less, even more preferably 0.5% by mass or more and 7.5% by mass or less, and even more preferably 1.0% by mass or more and 5.0% by mass or less. The content of the alkaline agent here refers to the effective amount of the alkaline agent.

[0182] The content of water in the first agent is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.98% by mass or less, from the viewpoint of improving the solubility of the oxidative dye intermediate (B) and the alkaline agent and from the viewpoint of improving the handleability when mixed with the second agent. The content of water in the first agent may be the balance of the oxidative dye intermediate (B) and the alkaline agent.

[0183] (pH) From the viewpoint of improving dyeability and fastness, the pH of the first agent is preferably 6 or more, more preferably 8 or more, and even more preferably 10 or more. Furthermore, from the viewpoint of maintaining constant reactivity, the pH is preferably 12.0 or less, more preferably 11.5 or less, and even more preferably 11.0 or less. The pH of the first agent is preferably 6 or more and 12 or less, more preferably 8 or more and 11.5 or less, and even more preferably 10 or more and 11.0 or less. The pH can be measured at 25°C by the method described in the examples.

[0184] (Dosage form, manufacturing method) The dosage form of the first agent is not particularly limited, and can be liquid, paste, cream, gel, foam, spray, wax, etc. depending on the product form, and is preferably a liquid. The first agent can be manufactured according to a conventional method.

[0185] The second agent contains hydrogen peroxide and water. From the viewpoint of improving dyeability and fastness, the content of hydrogen peroxide in the second agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. From the viewpoint of suppressing fiber damage, the content of hydrogen peroxide in the second agent is preferably 10.0% by mass or less, and more preferably 8.0% by mass or less. The content of hydrogen peroxide in the second agent is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, and even more preferably 1.0% by mass or more and 8.0% by mass or less. From the viewpoint of ease of handling, hydrogen peroxide is preferably blended in the form of an aqueous solution. In this specification, the content of hydrogen peroxide in the second agent refers to the effective amount of hydrogen peroxide.

[0186] [Water] The water used in the second agent is not particularly limited, and for example, ion-exchanged water, pure water, distilled water, etc. can be used. From the viewpoint of improving handleability when mixed with the first agent, the content of water in the second agent is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.9% by mass or less. The content of water in the second agent includes the remainder of hydrogen peroxide.

[0187] [Other Components] In addition to the above components, the second agent may contain antioxidants, fragrances, preservatives, thickeners, pH adjusters, surfactants, texture improvers, and the like.

[0188] (pH) The pH of the second agent is preferably 2.5 or higher, more preferably 3.0 or higher, and preferably 6 or lower, more preferably 5 or lower, and even more preferably 4 or lower. The pH of the second agent is preferably 2.5 or higher and 6 or lower, more preferably 2.5 or higher and 5 or lower, and even more preferably 3.0 or higher and 4 or lower. The pH can be measured at 25°C by the method described in the examples.

[0189] (Dosage form, manufacturing method) The dosage form of the second agent is not particularly limited, and can be liquid, paste, cream, gel, foam, spray, wax, etc. depending on the product form, and is preferably liquid. The first agent and the second agent may be the same or different dosage forms, but from the viewpoint of ease of handling during use, it is preferable that they be the same dosage form. The second agent can be manufactured according to a conventional method.

[0190] Multi-component hair dyes are prepared by mixing at least the first and second components at the time of use. Multi-component hair dyes may be prepared by mixing at least the first and second components, and may also include, for example, those prepared by further mixing a third or more components containing other ingredients. The mixing ratio of the first and second components varies depending on the concentrations of the oxidative dye intermediate (B) and alkaline agent in the first component and the hydrogen peroxide in the second component, but the ratio (mass ratio) of the first component to the second component is preferably in the range of 1:0.1 to 1:10, more preferably 1:0.2 to 1:5, and even more preferably 1:0.5 to 1:3.

[0191] [Acidic Dyes] While known acidic dyes can be used without particular limitation as the acidic dye, from the viewpoint of improving the fastness of the modified regenerated collagen fibers after dyeing, the acidic dye preferably includes an acidic dye (C) that has a sulfonic acid group and satisfies at least one of the following conditions (3) and (4): (3) a molecular weight of 500 or more; (4) where Mw is the molecular weight, the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) divided by Mw [(a-b) / Mw] is 0.0045 or less. The molecular weight of the acidic dye here refers to the molecular weight in the undissociated (acid) state. For example, even if at least a portion of the sulfonic acid groups in the acidic dye are in the form of a sulfonate salt, the molecular weight of the acidic dye refers to the molecular weight in the undissociated sulfonic acid state, and does not include the molecular weight of the counterion. Note that this also includes cases where the acidic dye has an onium group such as a quaternary ammonium group, and in such cases, the counterion is similarly not included in the molecular weight. The acid dye (C) may be an acid dye that satisfies either one of the above (3) and (4), or may be an acid dye that satisfies both the above (3) and (4).

[0192] The acid dye (C) contains sulfonic acid groups, which interact with the structural moieties derived from component (X) and component (Y) inside the modified regenerated collagen fibers, making it easier for the acid dye (C) to remain inside the fibers, which is thought to further improve fastness. Furthermore, acid dyes that satisfy condition (3) have a large molecular weight, which makes them less likely to fade after dyeing and improves fastness. Furthermore, because the target of dyeing is regenerated collagen fibers, it is thought that, unlike hair, it is possible to dye the fibers by penetrating the interior of the fibers with the acid dye. When the difference (a - b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) in the acid dye, divided by Mw [(a - b) / Mw], is a predetermined value or less, the repulsion between negative charges between the structural moieties derived from compound (X) in the modified regenerated collagen fibers and the acid dye can be sufficiently reduced, which is thought to improve the fixation of the acid dye to the modified regenerated collagen fibers and further improve dyeability and fastness.

[0193] The number (a) of sulfonic acid groups in the acid dye (C) may be 1 or more, and from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fibers, it is preferably 1 or more, more preferably 2 or more, and preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and still more preferably 3 or less. That is, the number (a) of sulfonic acid groups in the acid dye (C) is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, even more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and still more preferably 2 or more and 3 or less. Here, "the number (a) of sulfonic acid groups in the acid dye (C)" means the number of sulfonic acid groups in the acid dye (C) in an undissociated (acid) state.

[0194] The acid dye (C) may be at least partially in the form of a salt. From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the salt preferably includes 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, calcium, iron, and chromium, even more preferably an ammonium salt or one or more metal salts selected from the group consisting of sodium, calcium, iron, and chromium, and even more preferably a sodium salt.

[0195] From the viewpoint of improving the fastness of the modified regenerated collagen fibers, the acid dye (C) preferably further contains a cationic moiety, such as a quaternary ammonium cationic moiety or an iminium cationic moiety, and from the viewpoint of improving the fastness of the modified regenerated collagen fibers, the acid dye (C) preferably contains an iminium cationic moiety.

[0196] The number of cationic sites (b) in the acid dye (C) may be 0. When the acid dye (C) has cationic sites, from the viewpoint of improving the fastness of the modified regenerated collagen fibers, the number of cationic sites (b) in the acid dye (C) is preferably 1 or more, and preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and still more preferably 2 or less. That is, it is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less. The number of cationic sites (b) in the acid dye (C) is preferably 0 or more and 5 or less, more preferably 0 or more and 4 or less, even more preferably 0 or more and 3 or less, still more preferably 0 or more and 2 or less, and still more preferably 1 or more and 2 or less.

[0197] From the viewpoint of improving the fastness of the modified regenerated collagen fibers, the difference (a-b) between the number of sulfonic acid groups (a) in the acid dye (C) and the number of cationic sites (b) in the acid dye (C) is preferably 1 or more, and preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and still more preferably 2 or less. That is, it is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less.

[0198] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, it is preferable that the acid dye (C) has a small number of carboxy groups, and the number of carboxy groups in the acid dye (C) is preferably 2 or less, more preferably 1 or less, and even more preferably 0.

[0199] (Requirement (3)) An acid dye (C) that satisfies the above (3) has a sulfonic acid group and a molecular weight of at least 500. When the acid dye (C) satisfies the above (3), the molecular weight of the acid dye (C) is preferably at least 520, more preferably at least 540, from the viewpoint of improving the fastness of the modified regenerated collagen fibers after dyeing, and is also preferably at most 1,500, more preferably at most 1,200, even more preferably at most 1,000, still more preferably at most 900, even more preferably at most 800, still more preferably at most 780, and still more preferably at most 750. When the acid dye (C) satisfies the above (1), the molecular weight of the acid dye (C) is preferably 500 or more and 1,500 or less, more preferably 500 or more and 1,200 or less, even more preferably 500 or more and 1,000 or less, still more preferably 500 or more and 900 or less, still more preferably 500 or more and 800 or less, still more preferably 500 or more and 780 or less, still more preferably 520 or more and 750 or less, and still more preferably 540 or more and 750 or less.

[0200] (Requirement (4)) When the acid dye (C) satisfies the above (4), the difference (a-b) between the number of sulfonic acid groups in the acid dye (C) and the number of cationic moieties in the acid dye (C) (a) and (b) is divided by Mw, where Mw is the molecular weight of the acid dye (C) (molecular weight in an undissociated (acid) state). The value [(a-b) / Mw] is, from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, 0.0045 or less, preferably 0.0040 or less, more preferably 0.0035 or less, and even more preferably 0.0025 or less. Furthermore, when the acid dye (C) satisfies the above (4), [(a-b) / Mw] is preferably 0.0005 or more, more preferably 0.0010 or more. When the acid dye (C) satisfies the above (4), [(a-b) / Mw] is preferably 0.0005 or more and 0.0045 or less, more preferably 0.0005 or more and 0.0040 or less, even more preferably 0.0010 or more and 0.0035 or less, and still more preferably 0.0010 or more and 0.0025 or less.

[0201] When the acid dye (C) satisfies the above (4), the molecular weight Mw is preferably 250 or more, more preferably 280 or more, even more preferably 300 or more, and still more preferably 320 or more. Also, it is preferably 1,500 or less, more preferably 1,200 or less, even more preferably 1,000 or less, still more preferably 900 or less, still more preferably 800 or less, still more preferably 780 or less, and still more preferably 750 or less. When the acid dye (C) satisfies the above (4), the molecular weight Mw is preferably 250 or more and 1,500 or less, more preferably 250 or more and 1,200 or less, even more preferably 250 or more and 1,000 or less, still more preferably 250 or more and 900 or less, still more preferably 280 or more and 800 or less, still more preferably 280 or more and 780 or less, still more preferably 280 or more and 750 or less, still more preferably 300 or more and 750 or less, and still more preferably 320 or more and 750 or less.

[0202] The acid dye (C) may satisfy both of the above (3) and (4), and in that case, the molecular weight of the acid dye (C) is 500 or more and [(a-b) / Mw] is 0.0045 or less. The preferred ranges of the molecular weight and [(a-b) / Mw] of the oxidation dye (C) are the same as those described above.

[0203] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the acid dye (C) is preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Green 25 (Color Index No. 61570), Acid Brown 13 (Color Index No. 10410), Acid Red 52 (Color Index No. 45100), Acid Black 1 (Color Index No. 20470), Acid Red 18 (Color Index No. 16255), Acid Red 27 (Color Index No. 16256), or No.16185), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), Acid Red 73 (Color Index No.27290), Acid Blue 1 (Color Index No.42045), Acid Red 184 (Color Index No.15685), Acid Red 35 (Color Index No.18065), Acid Red 14 (Color Index No.14720), Food Red 6 (Color Index No.16155), Acid Orange 3 (Color Index No.10385), Acid Orange 24 (Color Index No.20170), Acid Violet 43 (Color Index No.60730), Acid Blue 62 (Color Index No. 62045), Acid Red 88 (Color Index No.15620)、Acid Yellow 11(Color Index No.18820)、Acid Yellow 36(Color Index No.13065)、Acid Yellow 1(Color Index No.10316)、Acid Orange 7(Color Index No.15510)、Acid Orange 20(Color Index No.14600)、Acid Orange 6(Color Index No.14270)、Food Red 17(Color Index No.16035)、Acid Red 41(Color Index No.16290)、Acid Red 1(Color Index No.18050)、Acid Red 155(Color Index No.18130)、Acid Red 180(Color Index No.18736)、Acid Yellow 17(Color Index No.18965)、Acid Yellow 23(Color Index No.19140)、Acid Red 163(Color Index No.24790)、Food Black 2(Color Index No.27755)、Direct Orange 39(Color Index No.40215)、Acid Blue 7(Color Index No.42080)、Acid Green 9(Color Index No.42100)、Acid Green 22(Color Index No.42170)、Acid Blue 104(Color Index No.42735)、Acid Violet 9(Color Index No.45190)、Acid Red 50(Color Index No.45220)、Acid Violet 50(Color Index No.50325)、Acid Black 2(Color Index No.50420)、Acid Blue 80(Color Index No.61585)、Acid Blue 87(Color Index No.74180)、Acid Red 195(Color Index No.18760)、Acid Red 249(Color Index No.18134), Acid Red 131, and Acid Red 337 (Color Index No. 17102).

[0204] Acid dye (C) is more preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color and one or more selected from the group consisting of Acid Green 1 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Blue 7 (Color Index No. 42080), Acid Green 9 (Color Index No. 42100), Acid Blue 104 (Color Index No. 42735), and Acid Violet 50 (Color Index No. 50325).

[0205] Among the above, from the viewpoint of improving the fastness of the modified regenerated collagen fibers, the acid dye (C) more preferably includes one or more dyes selected from the group consisting of Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Red 52 (Color Index No. 45100), Acid Blue 3 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), and Acid Blue 1 (Color Index No. 42045), which have a cationic moiety number (b) of 1 or more, and even more preferably includes one or more dyes selected from the group consisting of Acid Blue 9 and Acid Red 52.

[0206] [Basic Dye] While known basic dyes can be used without particular limitation as the basic dye, from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the basic dye preferably includes a basic dye (D) (hereinafter also referred to simply as "basic dye (D)") having a value obtained by dividing the number of cationic moieties (a) by Mw (Mw) [(a) / Mw] of 0.00275 or more, where Mw is the molecular weight. Since the number of cationic moieties (a) per molecular weight of the basic dye (D) is a predetermined value or more, it is believed that the electrical interaction with component (X) in the modified regenerated collagen fiber is enhanced, thereby improving the dyeability. Examples of the cationic moiety include quaternary ammonium cationic moieties, imidazolium cationic moieties, pyridinium cationic moieties, pyrrolidinium cationic moieties, piperidinium cationic moieties, iminium cationic moieties, and pyrylium cationic moieties. From the viewpoint of improving the dyeability of the modified regenerated collagen fiber, the basic dye preferably includes an imidazolium cationic moiety or a pyridinium cationic moiety.

[0207] The molecular weight Mw of the basic dye (D) is preferably 200 or more, more preferably 220 or more, even more preferably 240 or more, and still more preferably 250 or more from the viewpoint of improving fastness, and is preferably 500 or less, more preferably 450 or less, even more preferably 400 or less, still more preferably 360 or less, and still more preferably 340 or less from the viewpoint of improving dyeability. The molecular weight Mw of the basic dye (D) is preferably 200 or more and 500 or less, more preferably 220 or more and 450 or less, even more preferably 240 or more and 400 or less, still more preferably 250 or more and 360 or less, and still more preferably 250 or more and 340 or less. In this specification, the molecular weight of the basic dye means a state in which the dye has chloride as a counter ion and the charge is neutralized, i.e., the molecular weight of the chloride.

[0208] The number (a) of cationic moieties in the basic dye (D) may be 1 or more, and is preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and still more preferably 2 or less. The number (a) of cationic moieties in the basic dye (D) is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, still more preferably 1 or more and 2 or less, and still more preferably 1.

[0209] Furthermore, when the molecular weight of the basic dye (D) is Mw, the value obtained by dividing the number of cationic sites (a) by Mw [(a) / Mw] is 0.00275 or more, preferably 0.00280 or more, and even more preferably 0.00290 or more, from the viewpoint of improving dyeability, and is preferably 0.010 or less, more preferably 0.008 or less, even more preferably 0.006 or less, even more preferably 0.005 or less, and even more preferably 0.004 or less. When the molecular weight of the basic dye (D) is Mw, the value obtained by dividing the number of cationic moieties (a) by Mw [(a) / Mw] is 0.00275 or more, preferably 0.00275 or more and 0.010 or less, more preferably 0.00275 or more and 0.008 or less, even more preferably 0.00275 or more and 0.006 or less, still more preferably 0.00275 or more and 0.005 or less, still more preferably 0.00280 or more and 0.005 or less, and still more preferably 0.00290 or more and 0.004 or less.

[0210] From the viewpoint of improving dyeability, the basic dye (D) preferably includes one or more selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, Basic Blue 124, Basic Brown 16 (Color Index No. 12250), Basic Violet 14 (Color Index No. 42510), Basic Black 7 (Color Index No. 51215), Basic Blue 25 (Color Index No. 52025), Basic Blue 6 (Color Index No. 51175), Basic Red 2 (Color Index No. 50240), Basic Red 22 (Color Index No. 11055), Basic Blue 17 (Color Index No. 52040), and Basic Blue 9 (Color Index No. 52015), and more preferably includes one or more selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, Basic Blue 124, and Basic Brown. 16, more preferably at least one selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, and Basic Blue 124, and even more preferably at least one selected from the group consisting of Basic Red 51, Basic Yellow 87, and Basic Orange 31.

[0211] When the dye used in hair dye B is one or more dyes selected from the group consisting of acid dyes and basic dyes, hair dye B is preferably a one-component hair dye. The one-component hair dye contains one or more dyes selected from the group consisting of acid dyes and basic dyes, and water.

[0212] The content of dye in hair dye B (in the case of the multi-component hair dye, hair dye B prepared by mixing the first and second components at the time of use) is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.02% by mass or more, still more preferably 0.03% by mass or more, still more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and still more preferably 0.2% by mass or more, from the viewpoint of improving dyeability, and is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of improving formulation stability. The dye content in hair dye B is preferably 0.005% by mass or more and 3% by mass or less, more preferably 0.01% by mass or more and 3% by mass or less, even more preferably 0.02% by mass or more and 3% by mass or less, still more preferably 0.03% by mass or more and 3% by mass or less, still more preferably 0.05% by mass or more and 3% by mass or less, still more preferably 0.1% by mass or more and 2% by mass or less, and still more preferably 0.2% by mass or more and 1% by mass or less. From the viewpoint of improving handleability, the water content in hair dye B is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.995% by mass or less.

[0213] In addition to the above-mentioned components, hair dye B may contain antioxidants, fragrances, preservatives, thickeners, pH adjusters, surfactants, texture improvers, etc., within the scope of not impairing the effects of the present invention. The formulation of hair dye B is not particularly limited, and can be liquid, paste, cream, gel, foam, spray, wax, etc. depending on the product form, with liquid being preferred. Hair dye B can be produced according to conventional methods.

[0214] (Dyeing Method) There are no particular limitations on the method for dyeing hair with the hair dye B, and conventional methods can be used. When using a commercially available hair dye, it is preferable to dye the hair according to the method described in the instructions attached to the product.

[0215] <Step (III)> In step (III), the hair and the fiber for head accessories are brought into contact with each other and kept in a wet state. By performing this step, dye transfer occurs from the hair dyed with hair dye B to the fiber for head accessories containing modified regenerated collagen fibers, improving the color matching effect. The fiber for head accessories subjected to step (III) is the fiber for head accessories containing modified regenerated collagen fibers after the treatment in step (I).

[0216] The term "wet state" as used herein refers to the state of the hair and the fiber for a head accessory product after a step of increasing the moisture content of the hair and the fiber for a head accessory product. The water content in the fiber for a head accessory product and the hair is not particularly limited, but when the weight of the fiber for a head accessory product after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as 1, the water content in the fiber for a head accessory product, expressed as a mass ratio (water / fiber for a head accessory product), is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.2 or more, still more preferably 0.3 or more, still more preferably 0.5 or more, still more preferably 0.7 or more, and still more preferably 1.0 or more, from the viewpoint of improving color compatibility; and from the viewpoint of easy handling, the water content in the fiber for a head accessory product is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. The water content in the fiber for head ornaments in a wet state is preferably a mass ratio (water / fiber for head ornaments) of 0.05 or more and 5 or less, more preferably 0.10 or more and 5 or less, even more preferably 0.2 or more and 5 or less, still more preferably 0.3 or more and 5 or less, still more preferably 0.5 or more and 3 or less, still more preferably 0.7 or more and 2 or less, and still more preferably 1.0 or more and 2 or less, where the mass of the fiber for head ornaments after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as 1. The method for moistening the hair and the fiber for a head accessory is not particularly limited, and examples thereof include (i) a method of immersing the hair in water, (ii) a method of rinsing with water, (iii) a method of washing with a hair wash composition, (iv) a method of treating with a rinse-off conditioner or treatment and then rinsing with water, (v) a method of applying a water-containing spray or mist, (vi) a method of applying steam, (vii) a method of wrapping with a wet towel, or (vii) a method of wrapping in plastic wrap, aluminum foil, or the like while wet with water, and the like. One or more of these methods can be used.

[0217] Among the above, from the viewpoints of ease of processing and improving the color compatibility between the hair and the fiber for a head accessory containing the modified regenerated collagen fibers, step (III) preferably includes one or more methods selected from the group consisting of (ii) a method of rinsing the hair to which the head accessory is attached with water and (iii) a method of washing the hair with a hair wash composition, and more preferably includes a step of washing the hair and the fiber for a head accessory with a hair wash composition, followed by rinsing with water. The water referred to here may be water at room temperature (5°C or higher and 35°C or lower) or warm water above 35°C. The hair wash composition used in step (III) is not particularly limited, and a commercially available product may be used.

[0218] In step (III), the time for moistening the hair and the fiber for a head accessory product is not particularly limited and can be appropriately selected depending on the method for moistening. From the viewpoint of improving the color compatibility between the hair and the fiber for a head accessory product, the time is preferably 1 second or more, more preferably 5 seconds or more. From the viewpoint of reducing the burden on the hairdresser and the patient, the time is preferably 6 hours or less, more preferably 3 hours or less, and even more preferably 2 hours or less. In step (III), the temperature for moistening the hair and the fiber for a head accessory product is also not particularly limited and can be appropriately selected depending on the method for moistening. From the viewpoint of improving the color compatibility between the hair and the fiber for a head accessory product containing regenerated collagen fibers, the time is preferably above 0°C, more preferably 5°C or more. From the viewpoint of reducing the burden on the hairdresser and the patient, the time is preferably 100°C or less. The temperature referred to here means the temperature of the water used for moistening the hair.

[0219] After step (III), it is preferable to carry out a step of drying the head accessory product and the hair to which it is attached (hereinafter also referred to simply as the "drying step"). The drying step is a step of reducing the moisture content of the head accessory product and the hair to which it is attached. The water content in the head accessory product fibers and hair after drying is not particularly limited, but the water content in the head accessory product fibers is preferably a mass ratio (water / head accessory product fibers) of 0.8 or less, more preferably 0.7 or less, even more preferably 0.5 or less, still more preferably 0.3 or less, even more preferably 0.2 or less, still more preferably 0.1 or less, and even more preferably less than 0.1, when the weight of the head accessory product fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as 1. Drying methods include, for example, towel drying, drying with a hair dryer (cold air or hot air), air drying, and combinations of two or more of these drying processes.

[0220] [Fiber Treatment Kit for Head Accessory Products] The present invention further provides a fiber treatment kit for head accessories, comprising a treatment composition A for treating fibers for head accessories containing regenerated collagen fibers, and a hair dye B for dyeing hair, wherein the treatment composition A is a treatment composition containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, and the regenerated collagen fibers include modified regenerated collagen fibers containing the following component (X): (X) 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 mgKOH / g or more and a weight-average molecular weight of 1,500 to 15,000, or a salt thereof

[0221] The treatment composition A and its preferred embodiments in the fiber treatment kit for head accessories are the same as the treatment composition A used in step (I) above, and the hair dye B and its preferred embodiments are the same as the hair dye B used in dyeing the hair above.

[0222] The head accessory fiber treatment kit can be used, for example, in the following manner. First, hair is dyed with hair dye B. Meanwhile, head accessory fibers are treated with treatment composition A according to the step (I), and a head accessory containing the head accessory fibers is worn on the hair according to the step (II). Next, according to the step (III), the hair and the treated head accessory fibers are kept in contact with each other and kept in a wet state. Alternatively, hair is dyed with hair dye B, and according to the step (II), a head accessory containing head accessory fibers before treatment with treatment composition A is worn on the hair. Next, the head accessory fibers are treated with treatment composition A according to the step (I). Furthermore, according to the step (III), the hair and the treated head accessory fibers are kept in contact with each other and kept in a wet state. By using the fiber treatment kit for head accessories of the present invention in the above-described manner, it is possible to improve the underwater elastic modulus of fibers for head accessories containing specific modified regenerated collagen fibers, reduce the color difference between hair and the fibers for head accessories, and improve the color matching effect.

[0223] [Use] The present invention further provides a use of composition A as a fiber treatment composition for headwear products containing regenerated collagen fibers, wherein composition A contains compound (A) having a pKa value of 1 or more and 7 or less, and water, and has a pH of 2 or more and 6 or less, and the regenerated collagen fibers include modified regenerated collagen fibers containing the following component (X): (X) 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 mgKOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less, or a salt thereof, and wherein a method for treating fibers for headwear products with composition A comprises the following steps (I) to (III), and wherein the method comprises the following step (III) after steps (I) and (II). Step (I): applying the composition A to the fiber for a head accessory; Step (II): attaching a head accessory containing the fiber for a head accessory to hair dyed with hair dye B; and Step (III): wetting the hair and the fiber for a head accessory while they are in contact with each other.

[0224] The composition A and its preferred embodiments are the same as those of the treatment composition A, and the modified regenerated collagen fibers, steps (I) to (III), and their preferred embodiments are also the same as those described above. That is, the compound (A) in the composition A preferably contains a compound that satisfies at least one of the following (1) and (2), and more preferably contains one or more compounds selected from the group consisting of a surfactant that satisfies the following (1), a polymer that satisfies the following (2), and a carboxylic acid compound (excluding surfactants) that has a molecular weight of less than 1,500 and satisfies the following (1). (1) Al 3+ (1) A chelate stability constant log K with an ion is 2 or less. (2) A molecular weight is 1,500 or more. Compound (A) preferably has one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group.

[0225] The compound (A) used in composition A preferably contains one or more compounds selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1500, each of which has one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group; more preferably, it contains one or more compounds 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 1500, and even more preferably, it contains 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, it contains one or more compounds selected from the group consisting of sodium lauryl sulfate, ammonium lauryl sulfate, polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether acetate, N-lauroyl the present invention further comprises one or more selected from the group consisting of sodium lauryl methylalanine, 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, polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene lauryl ether acetate, N-lauroylmethylalanine sodium, lauric acid amidopropyl betaine,It contains one or more selected from the group consisting of 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.

[0226] In relation to the above-described embodiments, the present invention discloses the following: <1> A method for treating fibers for head accessories containing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (X): (X) 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, the method comprising the following steps (I) to (III), and further comprising the following step (III) after steps (I) and (II): Step (I): applying a treatment composition A containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, to the fiber for a head accessory; Step (II): attaching a head accessory containing the fiber for a head accessory to hair dyed with hair dye B; and Step (III): wetting the hair and the fiber for a head accessory while they are in contact with each other. <2> The treatment method of <1>, wherein the head accessory comprises a hair wig, a toupee, weaving, a hair extension, a braided hair, a hair accessory, or a doll hair, and preferably comprises at least one selected from the group consisting of a hair wig, a toupee, weaving, and a hair extension, and more preferably comprises a hair extension. <3> The treatment method according to <1> or <2>, wherein the component (X) contains 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 contains 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 contains styrene-maleic acid copolymer.<4> The treatment method according to any one of <1> to <3>, wherein the molar ratio (u1 / u2) of the structural unit (u1) derived from an unsaturated monomer having a carboxy group to the structural unit (u2) derived from an aromatic vinyl compound monomer in the component (X) is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1. <5> The treatment method according to any one of <1> to <4>, wherein the acid value of the component (X) 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 even more preferably 400 mgKOH / g or more and 600 mgKOH / g or less. <6> The treatment method according to any one of <1> to <5>, wherein the weight-average molecular weight of the component (X) is preferably 3,000 to 15,000, more preferably 5,000 to 15,000, even more preferably 6,000 to 15,000, and still more preferably 6,000 to 10,000. <7> The treatment method according to any one of <1> to <6>, wherein the content of the component (X) in the modified regenerated collagen fibers 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, even more preferably 15% by mass to 40% by mass, and still more preferably 20% by mass to 40% by mass. <8> The treatment method according to any one of <1> to <7>, wherein the modified regenerated collagen fibers further contain, as component (Y), a polyvalent metal, or a salt or complex thereof.<9> The treatment method of <8>, wherein the component (Y) 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. <10> The treatment method of <8> or <9>, wherein the content of component (Y) in the modified regenerated collagen fibers is 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 still more preferably 2.0% by mass or more and 10% by mass or less, in terms of the amount of metal element.

[0227] <11> The treatment method according to any one of <1> to <10>, wherein the fiber for head accessories to be subjected to the treatment is preferably colored. <12> The treatment method according to any one of <1> to <11>, wherein the treatment method is (1) a method having the steps (I), (II), and (III) in this order, or (2) a method having the steps (II), (I), and (III) in this order, preferably (1) a method having the steps (I), (II), and (III) in this order. <13> The treatment method according to <12>, wherein the method (1) preferably includes a rinsing step between steps (I) and (II). <14> The treatment method according to any one of <1> to <13>, wherein the pKa of the compound (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. <15> The treatment method according to any one of <1> to <14>, wherein the pKa of the compound (A) is preferably −3.0 or more and +3.0 or less, more preferably −2.0 or more and +2.0 or less, and even more preferably −1.0 or more and +1.0 or less, relative to the pH value of the treatment composition A. <16> The treatment method according to any one of <1> to <15>, wherein the solubility of the compound (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. <17> The treatment method according to any one of <1> to <16>, wherein the number of phenolic hydroxyl groups in the compound (A) is preferably 1 or less, more preferably 0. <18> When the compound (A) satisfies the above (1), the Al content of the compound (A) is 3+The treatment method according to any one of <1> to <17>, 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. <19> The treatment method according to any one of <1> to <18>, wherein, when the compound (A) satisfies the above (2), the molecular weight of the compound (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, <20> The treatment method according to any one of <1> to <19>, wherein the compound (A) preferably contains a compound having an acidic group, more preferably contains a compound having one or more acidic groups selected from the group consisting of a carboxy group, a sulfate group, a sulfonic acid group, and a phosphate group, even more preferably contains a compound having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group, and still more preferably contains a compound having a carboxy group.

[0228] <21> The treatment method according to any one of <1> to <20>, wherein, when the compound (A) is a compound having a molecular weight of less than 1,500, the number of acidic groups in the compound (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. <22> The treatment method according to <20> or <21>, wherein the compound (A) preferably contains one or more selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1,500, each having the acidic group. <23> The treatment method according to <22>, wherein the surfactant used as the compound (A) preferably contains one or more selected from the group consisting of anionic surfactants and amphoteric surfactants, satisfying the above (1). <24> The treatment method of <23>, wherein 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. <25> The treatment method of <23>, wherein the amphoteric surfactant preferably comprises one or more selected from the group consisting of amine oxide-type amphoteric surfactants, carboxybetaine-type amphoteric surfactants, and sulfobetaine-type amphoteric surfactants, more preferably a carboxybetaine-type amphoteric surfactant, and even more preferably fatty acid amidopropyl betaine.<26> The surfactant used as the compound (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 ethers, <27> The treatment method according to any one of <22> to <26>, wherein the polymer used as the compound (A) is a polymer other than component (X), and preferably contains one or more selected from the group consisting of anionic polymers and amphoteric polymers that satisfy the above-mentioned (2). <28> The treatment method of <27>, 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. <29> The treatment method of <28>, 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. <30> The treatment method of <29>, wherein the (meth)acrylic acid homopolymer comprises one or more selected from the group consisting of polyacrylic acid and polymethacrylic acid.

[0229] <31> The treatment method according to <29>, wherein the anionic (meth)acrylic acid copolymer comprises one or more selected from the group consisting of a (meth)acrylic acid / maleic acid copolymer, a (meth)acrylic acid / itaconic acid copolymer, a (meth)acrylic acid / fumaric acid copolymer, a (meth)acrylic acid / vinyl acetate copolymer, a (meth)acrylic acid / (meth)acrylic acid alkyl ester copolymer, a (meth)acrylic acid / 2-hydroxyethyl methacrylate copolymer, an acrylic acid / acrylic acid alkyl ester / (N-alkyl)acrylamide copolymer, a carboxyvinyl polymer, an (acrylates / C10-30 alkyl acrylate) crosspolymer, a (sodium acrylate / acryloyldimethyltaurine / dimethylacrylamide) crosspolymer, and acrylates crosspolymer 4. <32> The treatment method according to any one of <28> to <31>, wherein the anionic polysaccharide used as compound (A) comprises one or more selected from the group consisting of polysaccharides having a carboxy group and sulfates of polysaccharides. <33> The processing method according to <32>, 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. <34> The processing method according to any one of <28> to <33>, wherein the anionic polysaccharide preferably comprises one or more selected from the group consisting of carboxymethylcellulose, xanthan gum, and carrageenan, more preferably xanthan gum. <35> The processing method according to any one of <27> to <34>, wherein the anionic polymer used as compound (A) preferably comprises one or more selected from the group consisting of polyacrylic acid and anionic polysaccharides, more preferably one or more selected from the group consisting of polyacrylic acid, carboxymethylcellulose, xanthan gum, and carrageenan, even more preferably polyacrylic acid. <36> The amphoteric polymer used as the compound (A) isMethacryloylethyl dimethyl betaine, methacryloylethyl trimethylammonium chloride, methoxypolyethylene glycol methacrylate copolymer (Polyquaternium-49), methacryloylethyl dimethyl betaine, methacryloylethyl trimethylammonium 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 dimethacrylate The treatment method according to any one of <27> to <35>, comprising one or more selected from the group consisting of acrylic acid, methyl acrylate, methacrylamidopropyltrimethylammonium chloride 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). <37> The treatment method according to any one of <27> to <35>, wherein the amphoteric polymer used as the compound (A) preferably contains one or more selected from the group consisting of a structural unit derived from (meth)acrylic acid and a betaine group, 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). <38> The treatment method according to any one of <27> to <35>, wherein the polymer used as the compound (A) preferably satisfies the above (2),The polymer may include 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- The treatment method according to any one of <22> to <37>, comprising one or more selected from the group consisting of 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 one or more selected from the group consisting of polyacrylic acid, xanthan gum, and acrylamide / acrylic acid / dimethyldiallylammonium chloride copolymer (Polyquaternium-39). <39> The treatment method according to any one of <22> to <38>, 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 comprises one or more selected from the group consisting of 2-pyrrolidone-5-carboxylic acid and pyruvic acid. <40> The compound (A) preferably comprises one or more selected from the group consisting of a surfactant, a polymer, and a carboxylic acid compound (excluding surfactants) having a molecular weight of less than 1,500, each having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group, more preferably comprises one or more selected from the group consisting of a surfactant satisfying the above (1), a polymer satisfying the above (2), and a carboxylic acid compound (excluding surfactants) having a molecular weight of less than 1,500, and still more preferably comprises an alkyl sulfate,The surfactant may comprise at least one selected from the group consisting of 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 having a molecular weight of less than 1,500 (excluding surfactants), and more preferably sodium lauryl sulfate, ammonium lauryl sulfate, 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), ... The treatment method according to any one of <1> to <39>, wherein the surfactant contains at least one selected from the group consisting of 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 contains at least one 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.

[0230] <41> The treatment method according to any one of <1> to <40>, wherein the content of compound (A) in the treatment composition A is preferably from 0.01% by mass to 40% by mass, more preferably from 0.05% by mass to 30% by mass, even more preferably from 0.1% by mass to 25% by mass, still more preferably from 0.2% by mass to 20% by mass, still more preferably from 0.5% by mass to 20% by mass, still more preferably from 1.0% by mass to 20% by mass, still more preferably from 1.5% by mass to 15% by mass, and still more preferably from 2.0% by mass to 10% by mass. <42> The treatment method according to any one of <22> to <41>, wherein, when the compound (A) contains a polymer, the content of compound (A) in the treatment composition A is even more preferably from 5% by mass to 10% by mass, and even more preferably from 7.5% by mass to 10% by mass. <43> The treatment method according to any one of <1> to <42>, wherein the water content in the treatment composition A 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. <44> The treatment method according to any one of <1> to <43>, wherein the pH of the treatment composition A 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. <45> The treatment method according to any one of <1> to <44>, wherein the treatment composition A is in the form of a liquid, mist, paste, cream, gel, foam, spray, or wax, and is preferably a liquid. <46> The treatment method according to any one of <1> to <45>, wherein in the step (I), the method of applying the treatment composition A to the regenerated collagen fibers comprises a method of coating the treatment composition A on dry or wet regenerated collagen fibers, or a method of immersing the regenerated collagen fibers in the treatment composition A, and preferably a method of immersing dry regenerated collagen fibers in the treatment composition A.<47> The treatment method according to any one of <1> to <46>, wherein in the step (I), when the content of compound (A) in treatment composition A is c [% by mass] and the amount of treatment composition A applied per 1 g of fiber is b [g], the total amount of compound (A) applied per 1 g 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. <48> The treatment method according to any one of <1> to <47>, wherein in step (I), the amount of treatment composition A applied to the regenerated collagen fibers is such that the bath ratio (dry mass of regenerated collagen fibers:mass of treatment composition A), 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 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. <49> The treatment method of <48>, wherein, when the regenerated collagen fibers are immersed in the treatment composition A, the bath ratio (dry mass of the regenerated collagen fibers:mass of the treatment composition A) is more preferably 1:2 to 1:50, 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 a relative humidity of 65% for 24 hours is taken as the dry mass. <50> The treatment method of <48>, wherein, when the treatment composition A is applied to the regenerated collagen fibers, the bath ratio (dry mass of the regenerated collagen fibers:mass of the treatment composition A) is 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.

[0231] <51> The treatment method according to any one of <46> to <48> and <50>, wherein, when the treatment composition A is applied to the regenerated collagen fibers, the application time is preferably from 10 seconds to 10 minutes, more preferably from 20 seconds to 5 minutes. <52> The treatment method according to any one of <46> to <48> and <50> to <51>, wherein, after the treatment composition A is applied to the regenerated collagen fibers, a step of leaving the fibers 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. <53> The treatment method according to any one of <46> to <49>, wherein, when the regenerated collagen fibers are immersed in the treatment composition A, 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. <54> The treatment method according to any one of <1> to <53>, wherein the temperature when the treatment composition A is applied to the regenerated collagen fibers 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. <55> The treatment method according to any one of <1> to <54>, comprising a step of rinsing away excess treatment composition A applied to the regenerated collagen fibers after performing step (I) and before performing the next step. <56> The treatment method according to any one of <1> to <55>, comprising a step of drying the regenerated collagen fibers after applying the treatment composition A to the regenerated collagen fibers, or after performing a rinsing step, if any. <57> The treatment method of any one of <1> to <56>, wherein the head accessory product attached to the hair in step (II) is a head accessory product containing modified regenerated collagen fibers after the treatment in step (I), or a head accessory product containing modified regenerated collagen fibers before the treatment in step (I), and is preferably a head accessory product containing modified regenerated collagen fibers dyed after the treatment in step (I). <58> The treatment method of any one of <1> to <57>, wherein the hair dye B is preferably a hair dye containing one or more dyes selected from the group consisting of oxidative dyes, acidic dyes, and basic dyes, and more preferably a hair dye containing an oxidative dye.

[0232] <59> The treatment method according to <58>, wherein the oxidation dye is an oxidation dye intermediate (B) containing a coupler, preferably at least one selected from the group consisting of the following components (B1) and (B2): (B1) at least one selected from the group consisting of couplers (B1-1) having a benzene ring, having electron-donating groups at the 1- and 3-positions on the benzene ring, and hydrogen atoms at the 4- and 6-positions, couplers (B1-2) having a pyridine ring, having electron-donating groups at the 2- and 6-positions on the pyridine ring, and hydrogen atoms at the 3- and 5-positions, and couplers (B1-3) represented by the following general formula (B13):

[0233]

[0234] (In formula (B13), R 11 is -O-(CH2) n R is a divalent group represented by —O— (n is a number of 2 or more and 10 or less). 12 , R 14 , R 22 and R 24 is an electron donating group, R 15 and R 25 is a hydrogen atom. 13 , R 16 , R 23 and R 26 are each independently a hydrogen atom, an alkyl group, or an electron-donating group.) (B2) One or more couplers other than the component (B1), selected from the group consisting of couplers (B2-1) having a benzene ring, electron-donating groups at the 1- and 2-positions on the benzene ring, and hydrogen atoms at two or more of the 3- to 6-positions, and couplers (B2-2) having a pyridine ring, electron-donating groups at the 2- and 3-positions on the pyridine ring, and hydrogen atoms at two or more of the 4- to 6-positions.

[0235] <60> The processing method according to <59>, wherein the coupler (B1-1) preferably contains a compound represented by the following general formula (B11):

[0236]

[0237] (In formula (B11), R 1 is an electron donating group attached to the carbon atom at the 1st position, R 2represents a hydrogen atom, an alkyl group or an electron-donating group bonded to the carbon atom at the 2-position, R 3 is an electron donating group attached to the 3-position carbon, R 4 is a hydrogen atom, an alkyl group, or an electron-donating group bonded to the carbon atom at the 5-position. 2 and R 3 may be bonded to each other to form a hydrocarbon ring structure having aromaticity.

[0238] <61> The treatment method according to <60>, wherein the compound represented by general formula (B11) comprises one or more selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, and 1-naphthol, and preferably comprises one or more selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol. <62> The treatment method according to any one of <59> to <61>, wherein the coupler (B1-2) preferably comprises a compound represented by the following general formula (B12):

[0239]

[0240] (In formula (B12), R 5 is an electron donating group attached to the 2-position carbon, R 6 represents a hydrogen atom, an alkyl group or an electron-donating group bonded to the carbon atom at the 4-position, R 7 is an electron donating group attached to the 6-carbon atom.)

[0241] <63> The treatment method according to <62>, wherein the compound represented by general formula (B12) includes 2,6-diaminopyridine. <64> The treatment method according to any one of <59> to <63>, wherein the coupler represented by general formula (B13) includes 1,3-bis(2,4-diaminophenoxy)propane. <65> The treatment method according to any one of <59> to <64>, wherein the component (B1) preferably includes one or more selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, 1-naphthol, 2,6-diaminopyridine, and 1,3-bis(2,4-diaminophenoxy)propane, and more preferably includes one or more selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol.

[0242] <66> The processing method according to any one of <59> to <65>, wherein the coupler (B2-1) preferably contains a compound represented by the following general formula (B21):

[0243]

[0244] (In formula (B21), R 31 is an electron donating group attached to the carbon atom at the 1st position, R 32 is an electron donating group attached to the 2-position carbon, R 33 ~R 36 are hydrogen atoms, alkyl groups, or electron-donating groups bonded to the 3-, 4-, 5-, and 6-position carbons, respectively. 33 ~R 36 At least two of these are hydrogen atoms.)

[0245] <67> The treatment method according to <66>, wherein the compound represented by the general formula (B21) includes at least one member selected from the group consisting of ortho-aminophenol and 2,4-diaminophenoxyethanol.

[0246] <68> The processing method according to any one of <59> to <67>, wherein the coupler (B2-2) preferably contains a compound represented by the following general formula (B22):

[0247]

[0248] (In formula (B22), R 37 is an electron donating group attached to the 2-position carbon, R 38 is an electron donating group attached to the 3-carbon atom. 39 ~R 41 are hydrogen atoms, alkyl groups, or electron-donating groups bonded to the 4-, 5-, and 6-position carbons, respectively. 39 ~R 41 At least two of these are hydrogen atoms.)

[0249] <69> The treatment method according to <68>, wherein the compound represented by general formula (B22) includes 2,3-diaminopyridine, 2-amino-3-hydroxypyridine, or a salt thereof. <70> The treatment method according to any one of <59> to <69>, wherein the component (B2) preferably includes a coupler (B2-1), more preferably one or more selected from the group consisting of ortho-aminophenol and 2,4-diaminophenoxyethanol.

[0250] <71> The processing method according to any one of <59> to <70>, wherein the oxidation dye intermediate (B) preferably contains a component (B1), more preferably one or more selected from the group consisting of meta-aminophenol, resorcinol, meta-phenylenediamine, 2-methylresorcinol, 1-naphthol, 2,6-diaminopyridine, and 1,3-bis(2,4-diaminophenoxy)propane. <72> The processing method according to any one of <59> to <70>, wherein the oxidation dye intermediate (B) preferably contains a coupler (B1-1), more preferably one or more selected from the group consisting of meta-aminophenol, resorcinol, 2-methylresorcinol, and 1-naphthol. <73> The processing method according to any one of <59> to <72>, wherein the oxidation dye intermediate (B) further contains a component (B3): a precursor. <74> The treatment method according to <73>, wherein the component (B3) comprises one or more selected from the group consisting of paraphenylenediamine, toluene-2,5-diamine, orthochloroparaphenylenediamine, N-phenylparaphenylenediamine, N,N-bis(hydroxyethyl)paraphenylenediamine, 3-methyl-4-aminophenol, 2-hydroxyethylparaphenylenediamine, paraaminophenol, paramethylaminophenol, 4-amino-met-cresol, and salts thereof, and preferably comprises one or more selected from the group consisting of toluene-2,5-diamine, paraaminophenol, 4-amino-met-cresol, 1-hydroxyethyl-4,5-diaminopyrazole, and salts thereof. <75> The treatment method according to any one of <59> to <74>, wherein the molecular weight of the oxidation dye intermediate (B) is, as a non-dissociated type, preferably from 95 to 500, more preferably from 100 to 300, and even more preferably from 105 to 200. <76> The processing method according to any one of <58> to <75>, wherein the acid dye preferably contains an acid dye (C) that has a sulfonic acid group and satisfies at least one of the following (3) and (4):(3) The molecular weight is 500 or more. (4) When the molecular weight is Mw, the value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], is 0.0045 or less. <77> The treatment method according to <76>, wherein the number of sulfonic acid groups (a) in the acid dye (C) is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, even more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and still more preferably 2 or more and 3 or less. <78> The treatment method according to <76> or <77>, wherein the cationic moieties include one or more selected from the group consisting of quaternary ammonium cationic moieties and iminium cationic moieties, and preferably include iminium cationic moieties. <79> The processing method according to any one of <76> to <78>, wherein the number of cationic moieties (b) in the acid dye (C) is preferably 0 to 5, more preferably 0 to 4, even more preferably 0 to 3, still more preferably 0 to 2, and still more preferably 1 to 2. <80> The processing method according to any one of <76> to <79>, wherein the difference (a-b) between the number of sulfonic acid groups (a) in the acid dye (C) and the number of cationic moieties (b) in the acid dye (C) is preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, and still more preferably 1 to 2.

[0251] <81> The processing method according to any one of <76> to <80>, wherein when the acid dye (C) satisfies the above (3), the molecular weight of the acid dye (C) is preferably from 500 to 1,500, more preferably from 500 to 1,200, even more preferably from 500 to 1,000, still more preferably from 500 to 900, still more preferably from 500 to 800, still more preferably from 500 to 780, still more preferably from 520 to 750, and still more preferably from 540 to 750. <82> The processing method according to any one of <76> to <81>, wherein, when the acid dye (C) satisfies the above-mentioned (4), [(a-b) / Mw] is preferably 0.0005 or more and 0.0045 or less, more preferably 0.0005 or more and 0.0040 or less, even more preferably 0.0010 or more and 0.0035 or less, and still more preferably 0.0010 or more and 0.0025 or less. <83> The processing method according to any one of <76> to <82>, wherein when the acid dye (C) satisfies the above (4), the molecular weight Mw is preferably from 250 to 1,500, more preferably from 250 to 1,200, even more preferably from 250 to 1,000, still more preferably from 250 to 900, still more preferably from 280 to 800, still more preferably from 280 to 780, still more preferably from 280 to 750, still more preferably from 300 to 750, and still more preferably from 320 to 750. <84> The acid dye (C) is preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Green 25 (Color Index No. 61570), Acid Brown 13 (Color Index No.10410)、Acid Red 52(Color Index No.45100)、Acid Black 1(Color Index No.20470)、Acid Red 18(Color Index No.16255)、Acid Red 27(Color Index No.16185)、Acid Blue 3(Color Index No.42051)、Acid Green 50(Color Index No.44090)、Acid Red 73(Color Index No.27290)、Acid Blue 1(Color Index No.42045)、Acid Red 184(Color Index No.15685)、Acid Red 35(Color Index No.18065)、Acid Red 14(Color Index No.14720)、Food Red 6(Color Index No.16155)、Acid Orange 3(Color Index No.10385)、Acid Orange 24(Color Index No.20170)、Acid Violet 43(Color Index No.60730)、Acid Blue 62(Color Index No.62045)、Acid Red 88(Color Index No.15620)、Acid Yellow 11(Color Index No.18820)、Acid Yellow 36(Color Index No.13065)、Acid Yellow 1(Color Index No.10316)、Acid Orange 7(Color Index No.15510)、Acid Orange 20(Color Index No.14600)、Acid Orange 6(Color Index No.14270)、Food Red 17(Color Index No.16035)、Acid Red 41(Color Index No.16290)、Acid Red 1(Color Index No.18050)、Acid Red 155(Color Index No.18130)、Acid Red 180(Color Index No.18736), Acid Yellow 17 (Color Index No.18965), Acid Yellow 23 (Color Index No.19140), Acid Red 163 (Color Index No.24790), Food Black 2 (Color Index No.27755), Direct Orange 39 (Color Index No.40215), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Green 22 (Color Index No.42170), Acid Blue 104 (Color Index No.42735), Acid Violet 9 (Color Index No.45190), Acid Red 50 (Color Index No.45220), Acid Violet 50 (Color Index No.50325), Acid Black 2 (Color Index No.50420), Acid Blue 80 (Color Index No. 61585), Acid Blue 87 (Color Index No. 74180), Acid Red 195 (Color Index No. 18760), Acid Red 249 (Color Index No. 18134), Acid Red 131, and Acid Red 337 (Color Index No. 17102), and more preferably, Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), Acid Red 73 (Color Index No.27290), Acid Blue 1 (Color Index No.42045), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Blue 104 (Color Index No.42735), and Acid Violet 50 (Color Index and more preferably, the number of cationic moieties (b) is 1 or more, ...42045), more preferably one or more selected from the group consisting of Acid Blue 9 and Acid Red 52. <85> The treatment method according to any one of <58> to <84>, wherein the basic dye preferably contains a basic dye (D) in which, where Mw is the molecular weight, the value obtained by dividing the number of cationic moieties (a) by Mw [(a) / Mw] is 0.00275 or more. <86> The treatment method according to <85>, wherein the cationic moiety contains one or more selected from the group consisting of a quaternary ammonium cationic moiety, an imidazolium cationic moiety, a pyridinium cationic moiety, a pyrrolidinium cationic moiety, a piperidinium cationic moiety, an iminium cationic moiety, and a pyrylium cationic moiety, and preferably contains an imidazolium cationic moiety or a pyridinium cationic moiety. <87> The processing method according to <85> or <86>, wherein the molecular weight Mw of the basic dye (D) is preferably from 200 to 500, more preferably from 220 to 450, even more preferably from 240 to 400, still more preferably from 250 to 360, and still more preferably from 250 to 340. <88> The processing method according to any one of <85> to <87>, wherein the number (a) of cationic moieties in the basic dye (D) is preferably from 1 to 5, more preferably from 1 to 4, even more preferably from 1 to 3, still more preferably from 1 to 2, and still more preferably 1. <89> The processing method according to any one of <85> to <88>, wherein, where Mw is the molecular weight of the basic dye (D), the value obtained by dividing the number of cationic moieties (a) by Mw [(a) / Mw] is preferably 0.00275 or more and 0.010 or less, more preferably 0.00275 or more and 0.008 or less, even more preferably 0.00275 or more and 0.006 or less, still more preferably 0.00275 or more and 0.005 or less, still more preferably 0.00280 or more and 0.005 or less, and still more preferably 0.00290 or more and 0.004 or less. <90> The basic dye (D) is preferably a dye selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, Basic Blue 124, and Basic Brown 16 (Color Index No.12250), Basic Violet 14 (Color Index No. 42510), Basic Black 7 (Color Index No. 51215), Basic Blue 25 (Color Index No. 52025), Basic Blue 6 (Color Index No. 51175), Basic Red 2 (Color Index No. 50240), Basic Red 22 (Color Index No. 11055), Basic Blue 17 (Color Index No. 52040), and Basic Blue 9 (Color Index No. 52015), more preferably, one or more selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, Basic Blue 124, and Basic Brown 16, even more preferably, one or more selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, and Basic Blue 124, and even more preferably, one or more selected from the group consisting of Basic Red 51, Basic Yellow 87, Basic Orange 31, and Basic Blue 124. The treatment method according to any one of <85> to <89>, which includes one or more selected from the group consisting of Basic Orange 31, Basic Orange 87, and Basic Orange 31.

[0252] <91> The treatment method according to any one of <1> to <90>, wherein the wet state in the step (III) is a state after a step of increasing the moisture content of the hair and the fiber for a head accessory, and the water content in the fiber for a head accessory in the wet state is preferably a mass ratio (water / fiber for a head accessory) of 0.05 to 5, more preferably 0.10 to 5, even more preferably 0.2 to 5, still more preferably 0.3 to 5, more preferably 0.5 to 3, even more preferably 0.7 to 2, and still more preferably 1.0 to 2, when the mass of the fiber for a head accessory after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as 1. <92> The treatment method according to any one of <1> to <91>, wherein in the step (III), the method of bringing the hair and the fiber for a head accessory into a wet state comprises one or more of the following methods: (i) immersing the hair, to which the head accessory is attached, in a state in which the hair and the fiber for a head accessory are in contact with each other, (ii) rinsing with water, (iii) washing with a hair wash composition, (iv) treating with a rinse-off conditioner or treatment and then rinsing with water, (v) applying a water-containing spray or mist to the hair, (vi) applying steam, (vii) wrapping with a wet towel, or (vii) wrapping in plastic wrap, aluminum foil, or the like while wet with water. <93> The treatment method of <92>, wherein the step (III) comprises one or more methods selected from the group consisting of (ii) rinsing the hair to which the head accessory is attached with water, and (iii) washing with a hair wash composition, and more preferably comprising a step of washing the hair and the head accessory fiber with a hair wash composition, followed by rinsing with water. <94> The treatment method of any one of <1> to <93>, wherein in the step (III), the time for keeping the hair and the head accessory fiber in a wet state is preferably 1 second or more, more preferably 5 seconds or more, and preferably 6 hours or less, more preferably 3 hours or less, and even more preferably 2 hours or less. <95> The treatment method of any one of <1> to <94>, wherein in the step (III), the temperature for keeping the hair and the head accessory fiber in a wet state is preferably above 0°C, more preferably 5°C or more, and preferably 100°C or less.<96> The treatment method according to any one of <1> to <95>, further comprising, after step (III), a step of drying the head accessory and the hair to which the head accessory is attached. <97> A fiber treatment kit for head accessories, comprising a treatment composition A for treating fibers for head accessories containing regenerated collagen fibers, and a hair dye B for dyeing the hair, wherein the treatment composition A is a treatment composition containing a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, and the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (X): (X) 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 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof. <98> Use of composition A as a fiber treatment composition for head accessories containing regenerated collagen fibers, wherein the composition A contains a compound (A) having a pKa value of 1 to 7, and water, and has a pH of 2 to 6, the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (X): (X) 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 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof, the method for treating the fibers for head accessories with composition A comprising the following steps (I) to (III), Use of composition A, which comprises the following step (III) after the steps (I) and (II):Step (I): applying the composition A to the fiber for head accessories; Step (II): wearing a head accessory comprising the fiber for head accessories on hair dyed with hair dye B; Step (III): wetting the hair and the fiber for head accessories while they are in contact with each other. <99> A treatment composition for treating fibers for head accessories containing regenerated collagen fibers, the composition comprising a compound (A) having a pKa value of 1 or more and 7 or less, and water, and having a pH of 2 or more and 6 or less, the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (X): (X) a copolymer comprising 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, the method for treating the fiber for head accessories with the composition comprising the following steps (I) to (III), A treatment composition comprising the following step (III) after the steps (I) and (II): Step (I) applying the treatment composition to the fiber for a head accessory Step (II) wearing a head accessory containing the fiber for a head accessory on hair dyed with hair dye B Step (III) wetting the hair and the fiber for a head accessory while they are in contact with each other <100> Use of <98> or the treatment composition of <99>, wherein the compound (A) preferably contains a compound that satisfies at least one of the following (1) and (2), more preferably contains one or more selected from the group consisting of a surfactant that satisfies the following (1) and a polymer that satisfies the following (2): (1) Al. 3+(1) A chelate stability constant log K with an ion of 2 or less, and (2) A molecular weight of 1,500 or more. <101> The use of <98> or <100>, or the treatment composition of <99> or <100>, wherein the compound (A) preferably has one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group. <102> The compound (A) preferably contains one or more selected from the group consisting of surfactants, polymers, and carboxylic acid compounds (excluding surfactants) having a molecular weight of less than 1500, each having one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group; more preferably, it 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 1500, each satisfying the above (1); even more preferably, it 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 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, it contains lauryl sulfate. Sodium lauryl sulfate, ammonium lauryl sulfate, 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, the composition 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, 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, the composition contains one or more selected from the group consisting of polyoxyethylene Use of any one of <98>, <100> and <101>, or a treatment composition of any one of <99> to <101>, which contains one or more members selected from the group consisting of sodium ethylene (3) lauryl ether 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.

[0253] <103> A method for treating fibers for head accessories containing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing one or more compounds selected from the following (X1) to (X3) as component (X), the method comprising the following steps (I) to (III), and further comprising the following step (III) after steps (I) and (II): Step (I) is a step of applying to the fibers for head accessories a treatment composition A, the treatment composition A comprising water and one or more compounds (A) selected from the following (A1) to (A4) and having a pKa value of 1 to 7 and satisfying at least one of the following (1) and (2), and having a pH of 2 to 5.5: (1) Al 3+(1) A chelate stability constant log K with an ion is 2 or less. (2) A molecular weight is 1,500 or more. Step (II): A step of attaching a head ornament containing the fiber for a head ornament to hair dyed with hair dye B. Step (III): A step of moistening the hair and the fiber for a head ornament while they are in contact with each other. (X1): A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mg KOH / g or more and 600 mg KOH / g or less and a weight average molecular weight of 3,000 or more and 15,000 or less. (X2): A styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mg KOH / g or more and 600 mg KOH / g or less and a weight average molecular weight of 6,000 or more and 15,000 or less. (X3) 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. (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 1,500 (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 3,000 or more and 50,000 or less, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1,500 (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 sulfate, polyoxyethylene lauryl ether acetate, lauric acid amidopropyl betaine (lauramidopropyl betaine), polyacrylic acid having a weight-average molecular weight of 3,000 to 50,000, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid

[0254] <104> A treatment kit for hair accessories, comprising a treatment composition A for treating hair accessories containing regenerated collagen fibers, and a hair dye B for dyeing hair, wherein the treatment composition A contains, as a component (A), a compound (A) having a pKa value of 1 or more and 7 or less and satisfying at least one of the following (1) and (2), the compound (A) including one or more compounds selected from the following (A1) to (A4), and water, and has a pH of 2 or more and 5.5 or less, wherein: (1) Al 3+(1) A fiber treatment kit for head accessories, comprising modified regenerated collagen fibers containing, as component (X), one component selected from the following (X1) to (X3): (1) a chelate stability constant log K with an ion of 2 or less; (2) a molecular weight of 1,500 or more.(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 1,500 (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 3,000 to 50,000, polysaccharides having a carboxy group, amphoteric polymers, and carboxylic acid compounds having a molecular weight of less than 1,500 (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 sulfate, polyoxyethylene lauryl ether acetate, lauric acid amidopropyl betaine (lauramidopropyl betaine), polyacrylic acid having a weight-average molecular weight of 3,000 to 50,000, acrylamide-acrylic acid-dimethyldiallylammonium chloride copolymer (polyquaternium-39), 2-pyrrolidone-5-carboxylic acid, and pyruvic acid. (X1) 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 3,000 or more and 15,000 or less. (X2) 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. (X3) 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.

[0255] <105> The treatment method of <103> or the kit of <104> above, comprising component (A2) as component (A). <106> The treatment method of <103> or the kit of <104> above, comprising component (A3) as component (A). <107> The treatment method of <103> or the kit of <104> above, comprising component (A4) as component (A). <108> Any one of the treatment methods of <103>, <105> to <107>, or any one of the kits of <104> to <107> above, comprising component (X1) as component (X). <109> Any one of the treatment methods of <103>, <105> to <107>, or any one of the kits of <104> to <107> above, comprising component (X2) as component (X). <110> The treatment method according to any one of <103>, <105> to <107>, or the kit according to any one of <104> to <107>, comprising component (X3) as component (X).

[0256] <111> The treatment method of any one of <103> and <105> to <110>, or the kit of any one of <104> to <110>, wherein the pH of the treatment composition A is from 2 to 4.5. <112> The treatment method of any one of <103> and <105> to <111>, or the kit of any one of <104> to <111>, wherein the content of component (A) in the treatment composition A is from 0.1 to 25% by mass. <113> The treatment method of any one of <103> and <105> to <112>, or the kit of any one of <104> to <112>, wherein the content of component (A) in the treatment composition A is from 1.5 to 15% by mass. <114> The treatment method of any one of <103> and <105> to <113> above, or the kit of any one of <104> to <113> above, wherein the content of component (X) in the modified regenerated collagen fiber is 20% by mass or more and 40% by mass or less. <115> The treatment method of any one of <103> and <105> to <114> above, or the kit of any one of <104> to <114> above, wherein the modified regenerated collagen fiber contains aluminum, a salt thereof, or a complex thereof as component (Y). <116> The treatment method of <115> above, or the kit of <115> above, wherein the content of component (Y) in the modified regenerated collagen fiber is 2.0% by mass or more and 10% by mass or less, expressed as the amount of metal element. <117> The treatment method of any one of <103> and <105> to <116> above, or the kit of any one of <103> and <105> to <116> above, wherein, when applied by coating, the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) in the regenerated collagen fibers is 2.0 or more and 7 or less. <118> The treatment method of any one of <103> and <105> to <116> above, or the kit of any one of <103> and <105> to <116> above, wherein, when applied by immersion, the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) in the regenerated collagen fibers is 0.03 or more and 5 or less.<119> The treatment method of any one of <103>, <105> to <116>, or the kit of any one of <103>, <105> to <116>, and <118>, wherein, when applied by immersion, the mass ratio [(X) / (A)] of the compound (A) in the treatment composition A to the component (X) in the regenerated collagen fibers is 0.10 or more and 0.5 or less. <120> The treatment method of any one of <115> to <117>, or the kit of any one of <115> to <117>, wherein, when applied by painting, the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) in the regenerated collagen fibers is 0.10 or more and 0.2 or less.

[0257] <121> Any one of the treatment methods <115>, <116> and <118> to <119> above, or any one of the kits <115> to <116> and <118> to <119> above, wherein, when applied by immersion, the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) in the regenerated collagen fibers is 0.005 or more and 1.0 or less. <122> Any one of the treatment methods <115> to <116>, <118> to <119> and <121> above, or any one of the kits <115> to <116>, <118> to <119> and <121> above, wherein, when applied by immersion, the mass ratio [(Y) / (A)] of the compound (A) in the treatment composition A to the component (Y) in the regenerated collagen fibers is 0.03 or more and 0.1 or less. <123> The treatment method according to any one of <103> and <105> to <122> above, or the kit according to any one of <104> to <122> above, wherein the hair dye B contains one or more dyes selected from the group consisting of oxidative dyes and basic dyes. <124> The treatment method according to any one of <103> and <105> to <123> above, wherein the step (III) comprises washing the hair on which the head accessory is attached with a hair wash composition, and then rinsing with water.

[0258] 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.

[0259] <pH Measurement> The pH at 25° C. was measured using a pH meter (F-72, manufactured by Horiba Ltd.).

[0260] <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 refractometer)

[0261] <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.

[0262] <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

[0263] <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 with an optical microscope.

[0264] (Elastic modulus in water after treatment in step (I)) Using a fiber bundle after treatment in step (I) using the treatment composition A of each example (steps (II) and (III) were not performed), fiber pieces were collected in the same manner as in the method described in "Elastic modulus in water before treatment", and the elastic modulus in water was measured.

[0265] <Effect of Improving Elastic Modulus in Water> The value of the elastic modulus in water (MPa) after the treatment in step (I) - the elastic modulus in water (MPa) before the treatment is shown as the effect of improving elastic modulus in water in Table 5. The larger the value, the greater the effect of the treatment composition in improving elastic modulus in water.

[0266] <Mass loss rate of fiber after treatment> The mass loss rate was calculated from the mass of the fiber bundle before and after treatment with treatment composition A of each example (steps (II) and (III) were not performed) using the following formula, and is shown in Table 5 and the following. The smaller the value, the smaller the mass loss 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 loss rate (%) = {(mass of fiber bundle before treatment) - (mass of fiber bundle after treatment)} / (mass of fiber bundle before treatment) x 100

[0267] <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 fiber bundles before treatment and immediately after treatment with the treatment composition A of each example (steps (II) and (III) were not performed). (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 samples. At this time, the length of the fibers between the tapes was set to 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 a temperature setting of 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 undergo heat-induced shrinkage and the more excellent the heat resistance is. 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).

[0268] <Heat shrinkage suppression effect (%) of fiber> The heat shrinkage suppression effect (%) was calculated using the following formula based on the shrinkage rate (%) after contact with water vapor at 110°C, and is shown in Table 5 and the following. The larger the value, the greater the effect of the treatment composition in improving heat resistance. Heat shrinkage suppression effect (%) = (shrinkage rate (%) after contact with water vapor at 110°C before treatment) - (shrinkage rate (%) after contact with water vapor at 110°C after treatment)

[0269] Production Example 1 (Production of Regenerated Collagen Fiber X0) 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 mass of an aqueous solution containing 5.0% by mass of aluminum sulfate 14-18 hydrate, 0.65% by mass of citric acid monohydrate, and 1.3% by mass of sodium hydroxide (component (Y))) at 30°C with circulation, with the dry mass being the fiber mass after conditioning at 20°C and 65% relative humidity for 24 hours. A 5% aqueous solution of sodium hydroxide was then added 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 X0.

[0270] Production Example 2 (Production of Modified Regenerated Collagen Fiber X1) The regenerated collagen fiber X0 obtained in Production Example 1 was treated according to the following procedure to obtain modified regenerated collagen fiber X1. (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 X0 for each Example. First, the following (Procedure 2) to (Procedure 5) were carried out using the X1a agent shown in Table 1. The X1a and X1b agents 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 (X). (Procedure 2) The fiber bundles prepared in (Procedure 1) were immersed one bundle at a time in a separate container in an amount of X1a agent such that the bath ratio (mass of fiber bundle after drying in Procedure 1:mass of X1a agent) 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) For the fiber bundle obtained in (Procedure 5), (Procedure 2) to (Procedure 5) were repeated, using the X1b agent shown in Table 1 instead of the X1a agent. However, the heating and stirring time in (Procedure 4) was changed 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.

[0271]

[0272] 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 X1 produced in Production Example 2 above was 31.4% by mass, and the content of aluminum was 5.5% by mass.

[0273] Production Example 3 (Preparation of Hair Dye B1 Containing Oxidative Dye) The components shown in "First Agent" in Table 2 were blended and mixed until uniform to prepare a first agent. Similarly, the components shown in "Second Agent" in Table 2 were blended and mixed until uniform to prepare a second agent. When used, the first agent and the second agent were mixed in a mass ratio of 1:1 to prepare a hair dye B1 containing an oxidative dye, which was used for the evaluation described below.

[0274] Production Example 4 (Preparation of Hair Dye B2 Containing Basic Dye) The components shown in Table 3 were blended and mixed until uniform to prepare Hair Dye B2 containing basic dye.

[0275]

[0276]

[0277] Examples 1 to 19 and Comparative Examples 1 to 21 (Evaluation of fiber treatment method and color matching effect) (Preparation of fiber bundle for evaluation) Modified regenerated collagen fiber X1, regenerated collagen fiber X0, or white hair (Beaulux Co., Ltd.) was used to prepare a fiber bundle for evaluation, 10 cm in length and 1 g in mass. The fiber bundle was washed with a 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.

[0278] (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)

[0279] (Step (I): Treatment of Fibers for Headwear and Measurement of Hue) The components shown in "Treatment Composition A" in Table 5 and subsequent tables were blended and mixed until uniform to prepare the treatment composition A used in each example. The compound (A) used in treatment composition A is as shown in Table 4. Next, a fiber bundle for evaluation made of the fibers for headwear prepared by the method described above and shown in Table 5 and subsequent tables was immersed in treatment composition A in an amount such that the bath ratio (dry mass of fiber:mass of treatment composition A) was 1:30, where the mass of fiber 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 to 40°C and allowed to stand for the time shown in each table to perform 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.

[0280] The color (L0 * , a0 * , b0 * ) was measured using a color difference meter (CR-400, Konica Minolta, Inc.). * , a0 * , b0 * The values ​​were measured at six points per fiber bundle and the average value was calculated.

[0281] (Dyeing of Hair (Hair Bundle) and Measurement of Hue) A hair bundle having a length of 10 cm and a mass of 1 g was prepared using white hair (Beaulux Co., Ltd.) corresponding to the hair. The hair bundle was washed with the plain shampoo having the above composition, rinsed with warm water at 40°C, and thoroughly dried with a hair dryer. The hair bundle was then dyed by the following method. 2 g of hair dye B shown in Table 5 below was applied to the hair bundle. This was placed in a glass petri dish, the opening of which was covered with aluminum foil, and left floating in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set to 30°C for 30 minutes. After leaving for 30 minutes, the fiber bundle was rinsed with warm water at 40°C for 30 seconds to wash away hair dye B, and the operation of lathering with plain shampoo having the above composition for 15 seconds and then rinsing with warm water at 40°C for 15 seconds was repeated twice. Next, a plain conditioner having the following composition was applied for 15 seconds, followed by rinsing with warm water at 40°C for 15 seconds, and then thoroughly drying with cold air from a hair dryer.

[0282] (Composition of plain conditioner) Ingredients (mass %) Trimethylstearylammonium chloride (*1) 1.01 Distearyldimethylammonium chloride (*2) 2.0 Propylene glycol 5.0 Cetanol (*3) 2.0 Isopropyl alcohol 0.4 Methyl parahydroxybenzoate (*4) 0.1 Purified water Remaining amount Total 100.0 *1: 3.6 mass% of Coatamine 86W (manufactured by Kao Corporation, active ingredient 28% by mass) *2: 2.7 mass% of Coatamine D86P (manufactured by Kao Corporation, active ingredient 75% by mass) *3: Kalcol 6870 (manufactured by Kao Corporation) *4: Mekkinsu M (manufactured by Ueno Pharmaceutical Co., Ltd.)

[0283] The hair bundle after dyeing was subjected to the color (L1 * , a1 * , b1 *) was measured using a color difference meter (CR-400, Konica Minolta, Inc.). * , a1 * , b1 * Each of the values ​​was measured at six points per hair bundle and the average value was calculated.

[0284] (Color difference between fiber for headwear products and hair (immediately after dyeing hair: ΔE * Measurement of ab1)) The color difference ΔE between the treated fiber bundle obtained in step (I) and the dyed hair bundle was calculated using the following formula: * ab1 was calculated and shown in Table 5 below. ΔE * The larger the value of ab1, the greater the color difference between the fiber bundle after the step (I) treatment and the hair bundle immediately after dyeing. ΔE * ab1 = [(L1 * -L0 * ) 2 + (a1 * -a0 * ) 2 + (b1 * -b0 * ) 2 〕 1 / 2

[0285] (Steps (II) and (III)) The treated fiber bundle obtained in step (I) and the dyed hair bundle were overlapped. The overlapped fiber bundle was immersed in a container containing 20 g of a solution prepared by diluting the plain shampoo 10 times with purified water. 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, and heated and stirred for 15 minutes. The container containing the fiber bundle was removed from the dryer and returned to room temperature, after which the fiber bundle was removed from the container, rinsed with running tap water at 40°C for 120 seconds, and thoroughly dried with cold air from a dryer.

[0286] (Color difference between fiber for head accessories and hair (after step (III) treatment: ΔE * Measurement of hue (L2 ab2)) The fiber bundle after the above step (III) treatment was measured using a color difference meter in the same manner as above. * , a2 * , b2 *The color (L3) of the hair bundle after the step (III) treatment was also measured using a color difference meter. * , a3 * , b3 * The color difference ΔE between the fiber bundle and the hair bundle after step (II) was calculated using the following formula: * ab2 was calculated and shown in Table 5 below. * ab2 = [(L3 * -L2 * ) 2 + (a3 * -a2 * ) 2 + (b3 * -b2 * ) 2 〕 1 / 2

[0287] (Color compatibility effect between fiber for headwear products and hair) ΔE * ab1-ΔE * The values ​​of ab2 were calculated and shown in Table 5. A larger value indicates a higher color matching effect due to dye transfer from the hair bundle corresponding to the hair to the fiber bundle corresponding to the fiber for the head accessory in step (III).

[0288]

[0289]

[0290]

[0291]

[0292]

[0293] Tables 5 to 8 show that when the method of the present invention is applied to a specific modified regenerated collagen fiber (fiber for head accessories), the effect of improving the underwater elastic modulus is high, and the effect of improving the color compatibility between hair and the fiber for head accessories is also improved.

[0294] 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 using the treating agent composition shown in Table 5 below in the same manner as in the treatment of fiber for headwear products in step (I).

[0295] According to the present invention, a method for treating fibers for head accessories can be provided that can improve the underwater elastic modulus of fibers for head accessories containing specific modified regenerated collagen fibers, reduce the color difference between hair and the fibers for head accessories, and improve the color matching effect.

Claims

1. A method for treating fibers for headwear products containing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (X): (X) 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, the method comprising the following steps (I) to (III), and further comprising the following step (III) after steps (I) and (II). Step (I): applying a treatment composition A containing a compound (A) having a pKa value of 1 or more and 7 or less and water, and having a pH of 2 or more and 6 or less, to the fiber for a head accessory; Step (II): attaching a head accessory containing the fiber for a head accessory to hair dyed with hair dye B; and Step (III): wetting the hair and the fiber for a head accessory while they are in contact with each other.

2. The treatment method according to claim 1, wherein the compound (A) contains a compound that satisfies at least one of the following conditions (1) and (2): (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.

3. The treatment method according to claim 1 or 2, wherein the compound (A) has one or more acidic groups selected from the group consisting of a carboxy group and a sulfate group.

4. The treatment method according to claim 2 or 3, wherein the compound (A) comprises one or more compounds 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 satisfy (1).

5. The treatment method according to any one of claims 1 to 4, wherein step (III) comprises washing the hair to which the head accessory is attached with a hair wash composition, followed by rinsing with water.

6. The treatment method according to any one of claims 1 to 5, wherein step (I) is performed before step (II).

7. A fiber treatment kit for head accessories, comprising a treatment composition A for treating fibers for head accessories containing regenerated collagen fibers, and a hair dye B for dyeing hair, wherein the treatment composition A is a treatment composition containing a compound (A) having a pKa value of 1 to 7 and water, and a pH of 2 to 6, and the regenerated collagen fibers include modified regenerated collagen fibers containing the following component (X): (X) 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

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