Regenerated collagen fiber treatment method, modified regenerated collagen fiber and head ornamental product containing same

Abstract

A regenerated collagen fiber treatment method according to the present invention comprises the following step (i). Step (i): Regenerated collagen fibers having an underwater fiber swelling rate of 200% or greater as calculated by equation (1) are immersed in a fiber treatment agent containing component (A). (A): A copolymer that contains a structural unit derived from an unsaturated monomer having a carboxyl group or a salt thereof and a structural unit derived from an aromatic vinyl compound, and has an acid value of 100 mgKOH / g or greater and a weight average molecular weight of 1500-15000. (1): Underwater fiber swelling rate (%) = [(w1-w2) / w2]×100 (in the equation, w1 represents the mass (g) of the fibers, the mass being measured after placing 1.0 g of the fibers into a container filled with 100 g of ion-exchanged water, sealing the container, immersing the whole sealed container in a water bath at 40°C for 30 minutes, and then removing the fibers from the container, and subjecting the fibers to centrifugal dehydration for 1 minute at a centrifugal force of 220 [×g], and w2 indicates the mass of the fibers, the mass being measured after placing the fibers, for which the mass (w1) has been measured, on a filter paper and drying the fibers at 105°C for 3 hours).

Description

Method for treating regenerated collagen fibers, modified regenerated collagen fibers, and headwear products containing the same

[0001] The present invention relates to a method for treating regenerated collagen fibers, and more particularly to a method for treating regenerated collagen fibers used in textile products such as head accessories, including wigs and extensions.

[0002] Unlike synthetic fibers, regenerated collagen fibers generally have a natural texture and appearance derived from natural materials. Regenerated collagen fibers are usually produced by solubilizing acid-soluble or insoluble collagen with alkali or enzymes to prepare a spinning solution, discharging this solution from a spinning nozzle into a coagulation bath to form fibers, and then drying the fibrous collagen in the final step.

[0003] However, regenerated collagen fibers generally have higher water absorption rates than synthetic fibers due to their higher hydrophilicity, resulting in extremely low mechanical strength when saturated with water. Consequently, their high water absorption significantly reduces their mechanical strength during washing, leading to breakage during subsequent drying, reducing their suitability for use in textile products such as headwear. Regenerated collagen fibers also suffer from poor heat resistance. For example, when heat-set using a hair iron or similar device at high temperatures similar to those used with human hair, they shrink and crimp, resulting in a poor appearance. Furthermore, while plastic synthetic fibers retain the shape they acquire after heat-setting using an iron or similar device even after subsequent washing (they have thermal shape memory), regenerated collagen fibers lose their shape after a single wash (they lack thermal shape memory), resulting in a lack of flexibility in shape-setting compared to conventional plastic synthetic fibers.

[0004] Therefore, various studies have been conducted to solve the above-mentioned problems of naturally derived fibers such as regenerated collagen fibers. For example, it has been reported that in fabrics containing at least 10% wool by weight, cross-linking the wool with an acrylic resin can suppress wear (puffing) due to friction during washing (Patent Document 1). It has also been reported that treating regenerated collagen fibers with a fiber treatment agent containing a specific methylol compound and a specific phenol compound can solve the above-mentioned problems related to water resistance, heat resistance, and thermal shape memory ability that are specific to regenerated collagen fibers (Patent Document 2).

[0005] (Patent Document 1) JP 1-260062 A (Patent Document 2) JP 2022-103113 A

[0006] The present invention provides the following [1] to

[11] : [1] A method for treating regenerated collagen fibers, comprising the following step (i): Step (i): A step of immersing regenerated collagen fibers, the fiber swelling ratio in water of which is calculated by the following formula (1) is 200% or more, in a fiber treatment agent containing the following component (A): (A) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof and a structural unit derived from an aromatic vinyl compound monomer, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1500 to 15000. Fiber swelling ratio in water (%) = [(w1 - w2) / w2] × 100 (1) (wherein w1 represents the mass (g) of the fiber measured by placing 1.0 g of fiber in a container filled with 100 g of ion-exchanged water, sealing the container, immersing the container in a water bath at 40°C for 30 minutes, removing the fiber from the container, and centrifuging and dehydrating it for 1 minute at a centrifugal force of 220 [×g]. where w2 indicates the mass of the fiber measured after the fiber whose mass (w1) has been measured is placed on filter paper and dried at 105°C for 3 hours.] [2] The method for treating regenerated collagen fibers according to [1] above, wherein the regenerated collagen fibers contain the following component (B): (B) a polyvalent metal, or a salt or complex thereof. [3] The method for treating regenerated collagen fibers according to [2] above, wherein component (B) is aluminum, or a salt or complex thereof. [4] The method for treating regenerated collagen fibers according to any one of [1] to [3] above, comprising, prior to step (i), a regenerated collagen fiber production step of discharging an aqueous collagen solution obtained by solubilizing insoluble collagen fibers made from the split hides of livestock animals through a spinning nozzle or a slit, and immersing the resulting solution in an aqueous inorganic salt solution. [5] A modified regenerated collagen fiber comprising the regenerated collagen fiber containing the following component (A): (A) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 to 15,000. [6] The modified regenerated collagen fiber according to [5] above, in which the content of component (A) is 0.1 to 70 mass%. [7] The modified regenerated collagen fiber according to [5] or [6] above, further containing the following component (B):(B) a polyvalent metal, or a salt or complex thereof. [8] The modified regenerated collagen fiber according to [7] above, wherein component (B) is aluminum, or a salt or complex thereof. [9] A method for producing a modified regenerated collagen fiber, comprising a step of treating a regenerated collagen fiber by the regenerated collagen fiber treatment method according to any one of [1] to [4] above.

[10] A method for producing a head ornament product, comprising a step of treating a regenerated collagen fiber by the regenerated collagen fiber treatment method according to any one of [1] to [4] above.

[11] A head ornament product comprising the modified regenerated collagen fiber according to any one of [5] to [8] above as a component.

[0007] 10 is a fluorescent image of the cross section of the modified regenerated collagen fiber obtained in Example 19. Detailed Description of the Invention

[0008] Patent Document 1 proposes a technology for modifying fibers with high-molecular-weight compounds, but it merely involves crosslinking wool with a polymeric compound to form a surface coating. Prior to the filing of this application, there was a problem with the inability of polymeric compounds to penetrate naturally derived fibers, such as regenerated collagen fibers. Patent Document 2, on the other hand, proposes a technology for modifying fibers with polymeric compounds by penetrating regenerated collagen fibers with a methylol compound and a phenolic compound, coordinating phenolic hydroxyl groups within the fibers, and condensing the phenolic compounds with the methylol compound, thereby modifying the fibers from within the fibers with a polymerized condensate. However, this technology for modifying fibers from within the fibers requires the steps of penetrating a monomer into the fibers and polymerizing the monomer within the fibers, which complicates the processing process and limits the ability to process large quantities of regenerated collagen fibers. Therefore, the present invention relates to a method for treating regenerated collagen fibers that allows polymeric compounds to penetrate the fibers, and to modified regenerated collagen fibers.

[0009] The inventors have conducted research in light of the above-mentioned problems and have found that a polymeric compound containing a specific characteristic group specifically penetrates into regenerated collagen fibers having specific properties, and that the specific characteristic group is coordinated to the fibers, thereby solving the above-mentioned problems specific to regenerated collagen fibers, and have completed the present invention.

[0010] The treatment method of the present invention allows a polymeric compound having a molecular weight within a specific range to penetrate into and be retained in regenerated collagen fibers through a simple process. The modified regenerated collagen fibers of the present invention have excellent water resistance and thermal shape memory properties, making them useful for head accessories such as wigs and extensions.

[0011] [Method for Treating Regenerated Collagen Fibers] The method for treating regenerated collagen fibers of the present invention comprises the following step (i), which promotes the penetration and coordination of component (A) into the regenerated collagen fibers and improves the water resistance and thermal shape memory ability, which are issues specific to regenerated collagen fibers.

[0012] Step (i) A step of immersing regenerated collagen fibers having a fiber swelling ratio in water of 200% or more, calculated by the following formula (1), in a fiber treatment agent containing the following component (A):

[0013] (A) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 to 15,000.

[0014] Fiber swelling rate in water (%) = [(w1 - w2) / w2] x 100 (1)

[0015] (Wherein, w1 represents the mass (g) of the fiber measured after placing 1.0 g of fiber in a container filled with 100 g of ion-exchanged water, sealing the container, immersing the container in a water bath at 40°C for 30 minutes, removing the fiber from the container, and centrifuging and dehydrating it for 1 minute at a centrifugal force of 220 [×g]. w2 represents the mass (g) of the fiber measured after placing the fiber whose mass (w1) has been measured on filter paper and drying it at 105°C for 3 hours.)

[0016] In this specification, the "centrifugal force [×g]" in the above formula (1) is a value calculated by the following formula.

[0017] Centrifugal force [× g] = 1.118 × centrifugal radius (m) × [rotation speed (min -1 )] 2 x10 -3

[0018] <Regenerated Collagen Fiber> The regenerated collagen fiber used in the present invention must have a fiber swelling ratio in water calculated by the above formula (1) of 200% or more.

[0019] Even when fiber treatment agents containing polymer compounds are applied to regenerated collagen fibers commonly available on the market, the polymer compounds merely coat the fiber surface and fail to penetrate into the fiber interior. This problem has long been recognized by those skilled in the art and remained unsolved even prior to the filing of this application. Therefore, the present inventors focused on the maximum swelling ratio of regenerated collagen fibers in water and searched for regenerated collagen fibers capable of penetrating into the fiber interior. They found that regenerated collagen fibers with the specific property of having a fiber swelling ratio in water of 200% or more, calculated using the above formula (1), can penetrate into the fiber interior even with high molecular weight compounds. Furthermore, they found that by setting the molecular weight of the polymer compound to 1500 to 15,000 and forming it into a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof and a structural unit derived from an aromatic vinyl compound, the compound can be retained in the fiber after penetration, thereby solving the above-mentioned problems specific to regenerated collagen fibers.

[0020] The regenerated collagen fibers used in the present invention have a fiber swelling ratio in water of 200% or more, but from the viewpoint of promoting penetration into the fibers, it is preferably 250% or more, more preferably 300% or more, and even more preferably 350% or more. Furthermore, from the viewpoint of avoiding easy breakage of the fibers in the fiber processing step due to excessive swelling (from the viewpoint of workability in the fiber processing step), it is preferably 1000% or less, more preferably 800% or less, even more preferably 600% or less, and even more preferably 500% or less. That is, the fiber swelling ratio in water of the regenerated collagen fibers is preferably 250 to 1000%, more preferably 300 to 800%, even more preferably 350 to 600%, and even more preferably 350 to 500%.

[0021] As long as the fiber swelling rate in water is within the above-mentioned range, the regenerated collagen fiber does not need to be 100% collagen, and may contain natural or synthetic polymers or additives to improve quality. Furthermore, the regenerated collagen fiber may be post-processed. The preferred form of the regenerated collagen fiber is filament. The filament is generally taken out from a bobbin-wound or boxed state.

[0022] Suitable regenerated collagen fibers are artificially produced using collagen-derived polymers or oligomers as raw materials, i.e., regenerated collagen fibers made from collagen, which have a fiber swelling ratio in water within the above-mentioned range. Regenerated collagen fibers are typically produced by using a solubilized collagen raw material as a spinning solution, discharging this from a spinning nozzle into a coagulation bath to form fibers, and then drying the fibrous collagen in the final step. Undried regenerated collagen fibers before the drying step satisfy the above-mentioned fiber swelling ratio in water requirement. Such undried regenerated collagen fibers can be produced using known methods up to the drying step. For example, undried regenerated collagen fibers can be produced by solubilizing insoluble collagen fibers made from livestock split hides, discharging the resulting collagen aqueous solution through a spinning nozzle or slit, immersing it in an inorganic salt aqueous solution, and then recovering it without drying. This method is described in detail below.

[0023] The preferred collagen raw material is split skin. Split skin can be obtained, for example, from fresh split skin 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Undried regenerated collagen fibers can be obtained by discharging an aqueous collagen solution through, for example, a spinning nozzle or slit and immersing the resulting solution in an aqueous inorganic salt solution. Examples of aqueous inorganic salt solutions 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 aqueous inorganic salt solutions is adjusted to 10 to 40% by mass. The pH of the aqueous inorganic salt 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 aqueous inorganic salt 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 aqueous inorganic salt 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 aqueous inorganic salt solution is not particularly limited, but can typically be adjusted appropriately depending on the solubility of the inorganic salt.

[0031] The regenerated collagen fibers may be pretreated (crosslinked) by immersing the undried regenerated collagen fibers in an epoxy compound monomer or a solution thereof. The amount of the epoxy compound monomer 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 capable of reacting with epoxy groups contained in the epoxy compound monomer in the regenerated collagen fibers 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 monomer 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.

[0032] The epoxy compound monomer 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 monomer 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.

[0033] The treatment temperature for undried regenerated collagen fibers with epoxy compound monomer 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.

[0034] From the viewpoint of improving water resistance, the regenerated collagen fibers used in the present invention preferably contain a polyvalent metal, or a salt or complex thereof. Examples include one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof. Among these, from the viewpoints of improving water resistance, reducing fiber discoloration, reducing environmental impact, and improving economic efficiency, one or more polyvalent metals selected from aluminum, zirconium, and titanium, or a salt or complex thereof, is preferably used, and more preferably aluminum, a salt or complex thereof. The content of polyvalent metals, or salts or complexes thereof in the regenerated collagen fibers is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, in terms of metal element content, from the viewpoint of improving water resistance. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less. That is, from the above viewpoints, the content of polyvalent metals, or salts or complexes thereof in the regenerated collagen fibers is preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, even more preferably 3.0 to 20% by mass, and even more preferably 5.0 to 10% by mass, in terms of metal element content. In this specification, the "amount of metal elements" is determined by ICP atomic emission spectrometry. For ICP atomic emission spectrometry, an ICP atomic emission analyzer such as an iCAP6500Duo (manufactured by Thermo Fisher Scientific) can be used. The measurement conditions for ICP atomic emission spectroscopy are as follows: The wavelength optimal for the target metal can be selected by checking the spectral profile. For example, for aluminum, it is 396.152 nm. The analytical sample is pretreated using the method described in the Examples, and a calibration curve is created for each target metal.

[0035] <Measurement conditions> 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

[0036] Furthermore, undried regenerated collagen fibers are in a swollen state with water or an aqueous solution of inorganic salts. This swelling is preferably achieved by adding 4 to 15 times the mass of the regenerated collagen fibers with water or an aqueous solution of inorganic salts. If the content of water or an aqueous solution of inorganic salts is less than 4 times, the aluminum salt content in the regenerated collagen fibers tends to be low, resulting in insufficient water resistance. If the content of water or an aqueous solution of inorganic salts is more than 15 times, the strength of the fibers tends to be weak, making them difficult to handle. Therefore, metals may be added so that the amount of metal element falls within the above range. For example, the following treatment can be performed.

[0037] First, the undried regenerated collagen fibers are immersed in an aqueous solution of an aluminum salt, preferably basic aluminum chloride or basic aluminum sulfate represented by the following formula:

[0038] Al(OH) n Cl 3-n , or Al2 (OH) 2n (SO4) 3-n

[0039] [In the formula, n is 0.5 to 2.5.]

[0040] Specific examples include aluminum sulfate, aluminum chloride, and alum. Aluminum salts can be used alone or in combination of two or more. The aluminum salt concentration in the aluminum salt aqueous solution is preferably 0.3 to 5 mass% in terms of aluminum oxide. If the aluminum salt concentration is less than 0.3 mass%, the aluminum salt content in the regenerated collagen fibers will be low, and water resistance will tend to be insufficient. If the aluminum salt concentration exceeds 5 mass%, the treated fibers will tend to become hard and lose their texture.

[0041] The pH of the aluminum salt aqueous solution is usually 2.5 to 5. It can be adjusted using, for example, hydrochloric acid, sulfuric acid, acetic acid, sodium hydroxide, sodium carbonate, etc. If the pH is less than 2.5, the collagen structure tends to be destroyed and denatured, while if it exceeds 5, aluminum salt precipitation occurs, making it difficult to penetrate into the fibers. It is preferable to initially adjust the pH to 2.2 to 3.5 to allow the aluminum salt aqueous solution to sufficiently penetrate into the regenerated collagen fibers, and then add, for example, sodium hydroxide, sodium carbonate, etc. to adjust the pH to 3.5 to 5 to complete the treatment. If a highly basic aluminum salt is used, only the initial pH adjustment to 2.5 to 5 is sufficient.

[0042] The temperature of the aluminum salt aqueous solution is not particularly limited, but is preferably not higher than 50° C. If the temperature exceeds 50° C., the regenerated collagen fibers tend to denature.

[0043] The time for immersing undried regenerated collagen fibers in the aqueous aluminum salt solution is usually 3 hours or more, preferably 6 to 25 hours. If the immersion time is less than 3 hours, the reaction of the aluminum salt will not proceed easily, and the water resistance of the regenerated collagen fibers will tend to be insufficient. There is no particular upper limit to the immersion time, but if the immersion time is within 25 hours, the reaction of the aluminum salt will proceed sufficiently and water resistance will be good.

[0044] In order to prevent the aluminum salt from being rapidly absorbed into the regenerated collagen fibers and causing uneven concentration, an inorganic salt such as sodium chloride, sodium sulfate, or potassium chloride may be added to the aqueous aluminum salt solution as appropriate.

[0045] After treating the regenerated collagen fibers with the epoxy compound monomer or aluminum salt, they may be washed with water, for example, by washing with running water for 10 minutes to 4 hours.

[0046] <Fiber Treatment Agent> The fiber treatment agent contains a specific copolymer as component (A), which contains a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof and a structural unit derived from an aromatic vinyl compound. The bonding state of the monomers that give each structural unit may be block bonding, random bonding, or a combination thereof. Component (A) may be used alone or in combination of two or more types.

[0047] Examples of unsaturated monomers having a carboxy group or a salt thereof include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and salts thereof. Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, oleic acid, and cyclopentenylacetic acid. Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and methylenesuccinic acid. Furthermore, unsaturated dicarboxylic acids can also be used in their acid form by using unsaturated dicarboxylic acid anhydrides and hydrolyzing them with an alkali or the like. Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride and citraconic anhydride. Unsaturated monomers having a carboxy group or a salt thereof can be used alone or in combination of two or more.

[0048] Examples of salts include alkali metal salts, alkaline earth metal salts, and ammonium salts. Examples of alkali metal salts include sodium salts, lithium salts, and potassium salts, and examples of alkaline earth metal salts include calcium salts and magnesium salts. Among these, sodium salts are preferred from the viewpoint of dispersibility. Note that the carboxy group or its salt may be dissociated into a carboxy anion.

[0049] The aromatic vinyl compound is not particularly limited as long as it is an aromatic compound substituted with at least a vinyl group, and examples thereof 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.

[0050] The copolymer of component (A) may contain structural units other than those described above. Examples of the other structural units include, but are not limited to, structural units derived from unsaturated aliphatic hydrocarbon compounds. The other structural units may be one or more. The unsaturated aliphatic hydrocarbon compounds may be linear, branched, or cyclic. 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.

[0051] A suitable embodiment of component (A) is, for example, a copolymer containing structural units derived from one or more selected from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and salts thereof, and structural units derived from an aromatic vinyl compound. Specifically, from the viewpoints of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory ability, one or more selected from 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, styrene-4-vinylbenzoic acid copolymer, and salts thereof are preferred, with styrene-maleic acid copolymer or a salt thereof being more preferred. When the copolymer according to component (A) is in the form of a salt, the counter ion of the salt is not particularly limited, but examples include sodium salt, potassium salt, magnesium salt, calcium salt, and ammonium salt, with sodium salt being preferred. It should be noted that the styrene-maleic acid copolymer can also be prepared by using a styrene-maleic anhydride copolymer and treating it with an alkali or the like to produce a styrene-maleic acid copolymer.

[0052] In the copolymer related to component (A), the molar ratio (u1 / u2) of the structural unit (u1) derived from an unsaturated monomer having a carboxy group or a salt thereof to the structural unit (u2) derived from an 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, from the viewpoints of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory ability.

[0053] The acid value of component (A) is 100 mgKOH / g or more, but from the viewpoints of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory, 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. That is, the acid value is preferably 200 to 1000 mgKOH / g, more preferably 300 to 800 mgKOH / g, even more preferably 400 to 600 mgKOH / g. Herein, the term "acid value" refers to the number of milligrams (mg) of potassium hydroxide required to neutralize the acidic components contained in 1 g of sample, and can be determined by potentiometric titration in accordance with JIS K 0070. When component (A) is a salt, the acid value of the free acid (undissociated acid) is used.

[0054] Specific examples of component (A) 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

[0055] Component (A) has a weight average molecular weight of 1,500 to 15,000. From the viewpoints of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory, the weight average molecular weight is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and preferably 12,000 or less, more preferably 10,000 or less, even more preferably 8,000 or less, and even more preferably 7,000 or less. That is, such a weight average molecular weight is preferably 2,000 to 12,000, more preferably 3,000 to 12,000. Alternatively, it may be preferably 1,500 to 10,000, more preferably 2,000 to 8,000, even more preferably 3,000 to 8,000, and even more preferably 4,000 to 7,000. Herein, the term "weight average molecular weight" refers to the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC), and can be specifically measured by the method described in the Examples.

[0056] The content of component (A) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 1.0% by mass or more, and even more preferably 2.3% by mass or more, from the viewpoint of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory ability. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 30% by mass or less. That is, the content of component (A) in the fiber treatment agent is preferably 0.3 to 60% by mass, more preferably 1.0 to 50% by mass, even more preferably 2.3 to 40% by mass, and even more preferably 2.3 to 30% by mass. In this specification, when component (A) is a salt, the content of component (A) is expressed as a value converted to the free acid.

[0057] From the viewpoints of promoting penetration and coordination into fibers and improving water resistance, heat resistance, and thermal shape memory ability, the pH of the fiber treatment agent is preferably 2.0 or higher, more preferably 3.0 or higher, even more preferably 3.5 or higher, and preferably 11.0 or lower, more preferably 10.0 or lower, even more preferably 9.0 or lower, and even more preferably 6.5 or lower. That is, the pH of the fiber treatment agent is preferably 2.0 to 11.0, more preferably 3.0 to 10.0, even more preferably 3.5 to 9.0, and even more preferably 3.5 to 6.5. In this specification, "pH" refers to the value at 25°C and can be measured with a pH meter.

[0058] The content of component (A) in the fiber treatment agent used in this step may be within the range shown below depending on the pH range of the fiber treatment agent.

[0059] When the pH of the fiber treatment agent is less than 5.5, from the viewpoints of promoting penetration and coordination into the fiber and improving water resistance, heat resistance, and thermal shape memory ability, the content of component (A) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 0.8% by mass or more, even more preferably 1.3% by mass or more, and still more preferably 2.3% by mass or more, and from the viewpoint of improving the feel of the fiber surface, it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. That is, when the pH of the fiber treatment agent is less than 5.5, the content of component (A) in the fiber treatment agent is preferably 0.3 to 30% by mass, more preferably 0.8 to 20% by mass, even more preferably 1.3 to 10% by mass, and still more preferably 2.3 to 10% by mass.

[0060] Furthermore, when the pH of the fiber treatment agent is 5.5 or higher, from the viewpoints of promoting penetration and coordination into the fiber and improving water resistance, heat resistance, and thermal shape memory ability, the content of component (A) in the fiber treatment agent is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and even more preferably 3.0% by mass or more, and from the viewpoint of improving the feel of the fiber surface, it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. That is, when the pH of the fiber treatment agent is 5.5 or higher, the content of component (A) in the fiber treatment agent is preferably 1.0 to 60% by mass, more preferably 2.0 to 50% by mass, and even more preferably 3.0 to 40% by mass.

[0061] The fiber treatment agent used in this step uses water as a medium. The water content in the fiber treatment agent is the remainder excluding component (A) and the optional components described below. For example, the water content in the fiber treatment agent is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and even more preferably 40% by mass or more, and is preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less, even more preferably 95% by mass or less, even more preferably 90% by mass or less, and even more preferably 85% by mass or less. That is, the water content in the fiber treatment agent is preferably 10 to 98% by mass, more preferably 20 to 97% by mass, even more preferably 30 to 96% by mass, even more preferably 40 to 95% by mass, even more preferably 40 to 90% by mass, and even more preferably 40 to 85% by mass.

[0062] <Immersion> As the immersion method, conventionally known methods can be used. For example, a method can be used in which the regenerated collagen fibers are placed in a liquid tank filled with a fiber treatment agent and brought into contact with the fiber treatment agent. The immersion treatment can be performed two or more times. In this case, the same fiber treatment agent or different fiber treatment agents can be used. When different fiber treatment agents are used, for example, fiber treatment agents with different pHs can be used. Specifically, examples include a two-step treatment method that includes a step of treating with a first fiber treatment agent (hereinafter also referred to as the "first agent") containing component (A) and then a step of treating with a second fiber treatment agent (hereinafter also referred to as the "second agent") containing component (A) and having a pH adjusted to be 1.0 or more lower than that of the first fiber treatment agent, and a multi-step treatment method that includes a step of repeating the treatment with the first agent two to three or more times and finally treating with the second agent. After the two-step treatment, a further step of treatment with an additional fiber treatment agent (hereinafter also referred to as "third agent") containing benzoic acid or a salt thereof as component (C) may be carried out. Also, a treatment method including a step of treatment with the first agent and a step of treatment with the third agent may be mentioned. Examples of salts of benzoic acid include alkali metal salts, specifically sodium salts and potassium salts. The amount of each agent used may be selected appropriately within a range that does not impair the effects of the present invention.

[0063] In an additional fiber treatment agent (third agent) containing (C) benzoic acid or a salt thereof, the content of (C) benzoic acid or a salt thereof in the additional fiber treatment agent (third agent) is, from the viewpoint of improving the water resistance and heat resistance of the fiber, preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, still more preferably 40% by mass or less, and still more preferably 35% by mass or less. That is, the content of (C) benzoic acid or a salt thereof in the third agent in the additional fiber treatment agent (third agent) is preferably 0.1 to 60% by mass, more preferably 1 to 55% by mass, even more preferably 5 to 50% by mass, still more preferably 10 to 40% by mass, and still more preferably 20 to 35% by mass. In this specification, when benzoic acid is in the form of a salt, the content is expressed as a value converted into benzoic acid (free acid).

[0064] The amount of fiber treatment agent in which the regenerated collagen fibers are immersed is expressed as a bath ratio relative to the mass of the regenerated collagen fibers (mass of fiber treatment agent / mass of regenerated collagen fibers), and is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, even more preferably 10 or more, even more preferably 20 or more, and is preferably 500 or less, more preferably 250 or less, even more preferably 100 or less, and even more preferably 50 or less. That is, the bath ratio is preferably 2 to 500, more preferably 3 to 250, even more preferably 5 to 100, even more preferably 10 to 100, even more preferably 20 to 100, and even more preferably 20 to 50.

[0065] In this step, the regenerated collagen fibers can be immersed in the fiber treatment agent at room temperature (20°C ± 15°C), or they may be heated. This heating is carried out by heating the fiber treatment agent. This heating may be carried out by immersing the regenerated collagen fibers in a heated fiber treatment agent, or by immersing the regenerated collagen fibers in a low-temperature fiber treatment agent and then heating them. 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, in order to achieve the effects of the present invention by allowing component (A) to penetrate into the regenerated collagen fibers and increasing the interaction with the fiber-constituting molecules of the fibers, such as protein molecules. Furthermore, in order to prevent the regenerated collagen fibers from denaturing and deteriorating due to heat, the temperature is preferably less than 100°C, more preferably 80°C or lower, even more preferably 70°C or lower, even more preferably 60°C or lower, and even more preferably 50°C or lower. That is, the temperature is preferably 20°C or higher and lower than 100°C, more preferably 25 to 80°C, even more preferably 30 to 70°C, still more preferably 30 to 60°C, and still more preferably 30 to 50°C.

[0066] The immersion time in this step is adjusted appropriately depending on the heating temperature, but is, for example, preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, still more preferably 3 hours or more, still more preferably 5 hours or more, and still more preferably 10 hours or more from the viewpoint of exhibiting the effect of improving the elasticity of the regenerated collagen fibers, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 30 hours or less to suppress damage to the regenerated collagen fibers. That is, the immersion time is preferably from 15 minutes to 48 hours, more preferably from 30 minutes to 33 hours, even more preferably from 1 hour to 30 hours, still more preferably from 3 hours to 30 hours, still more preferably from 5 hours to 30 hours, and still more preferably from 10 hours to 30 hours.

[0067] This step 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 regenerated collagen fibers are immersed with a film-like substance, cap, lid, or the like made of a material that is impermeable to water vapor.

[0068] After this step, the regenerated collagen fibers may or may not be rinsed, but rinsing is preferred from the viewpoint of preventing deterioration of the feel of the regenerated collagen fiber surface due to excess component (A).

[0069] It is believed that the treatment in this step allows component (A) to penetrate into the regenerated collagen fibers and strongly coordinate with metals, such as polyvalent metals, within the fibers, resulting in various effects. That is, the regenerated collagen fiber treatment method including step (i) makes it possible to produce modified regenerated collagen fibers containing component (A) within the fibers, and the resulting modified regenerated collagen fibers are fibers with improved water resistance and thermal shape memory ability, which are issues specific to regenerated collagen fibers.

[0070] [Modified Regenerated Collagen Fiber] The modified regenerated collagen fiber of the present invention contains the following component (A): (A) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 to 15,000.

[0071] The structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof may be, for example, derived from an unsaturated monocarboxylic acid or a salt thereof, or derived from an unsaturated dicarboxylic acid or a salt thereof, or a combination thereof. Specific examples of the unsaturated monocarboxylic acid or a salt thereof and the unsaturated dicarboxylic acid or a salt thereof are as described above. The structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof may contain one or more types. The structural unit derived from an aromatic vinyl compound is not particularly limited as long as it is derived from an aromatic compound substituted with at least a vinyl group. Specific examples of the aromatic vinyl compound are as described above. The structural unit derived from an aromatic vinyl compound may contain one or more types. The bonding state of the monomers that give each structural unit may be block bonding, random bonding, or a combination thereof. One or more types of component (A) may be contained.

[0072] Component (A) may contain structural units other than the unsaturated monomers described above. The other structural units may contain one or more types. Examples of the other structural units include, but are not limited to, structural units derived from unsaturated aliphatic hydrocarbon compounds. The unsaturated aliphatic hydrocarbon compounds may be linear, branched, or cyclic. Specific examples of unsaturated aliphatic hydrocarbon compounds are as described above.

[0073] A preferred embodiment of component (A) is, for example, a copolymer containing structural units derived from one or more selected from unsaturated monocarboxylic acids or salts thereof and unsaturated dicarboxylic acids or salts thereof, and structural units derived from an aromatic vinyl compound. Specific examples, from the viewpoints of promoting retention and coordination in the fiber and improving water resistance, heat resistance, and thermal shape memory ability, are 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, styrene-4-vinylbenzoic acid copolymer, or salts thereof, and more preferably styrene-maleic acid copolymer or salts thereof. When the copolymer according to component (A) is in the form of a salt, the counter ion of the salt is not particularly limited, but examples include sodium salt, potassium salt, magnesium salt, calcium salt, and ammonium salt, with sodium salt being preferred.

[0074] In component (A), the molar ratio (u1 / u2) of the structural unit (u1) derived from an unsaturated monomer having a carboxy group or a salt thereof to the structural unit (u2) derived from an 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, from the viewpoints of promoting retention and coordination in the fiber and improving water resistance, heat resistance, and thermal shape memory ability.

[0075] The acid value of component (A) is 100 mgKOH / g or more, but from the viewpoints of promoting retention and coordination in the fiber and improving water resistance, heat resistance, and thermal shape memory ability, 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. That is, the acid value is preferably 200 to 1000 mgKOH / g, more preferably 300 to 800 mgKOH / g, even more preferably 400 to 600 mgKOH / g.

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

[0077] Component (A) has a weight-average molecular weight of 1,500 to 15,000, but from the viewpoints of promoting retention and coordination in the fiber and improving water resistance, heat resistance, and thermal shape memory ability, it is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and preferably 12,000 or less, more preferably 10,000 or less, even more preferably 8,000 or less, even more preferably 7,000 or less. That is, such a weight-average molecular weight is preferably 2,000 to 12,000, more preferably 3,000 to 12,000. Alternatively, it may be preferably 1,500 to 10,000, more preferably 2,000 to 8,000, even more preferably 3,000 to 8,000, even more preferably 4,000 to 7,000.

[0078] From the viewpoint of exhibiting higher water resistance, heat resistance, and thermal shape memory ability, the content of component (A) in the modified regenerated collagen fiber of the present invention is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, and even more preferably 10% by mass or more, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less. That is, the content of component (A) in the modified regenerated collagen fiber of the present invention is preferably 0.1 to 70% by mass, more preferably 0.5 to 65% by mass, even more preferably 1.0 to 60% by mass, even more preferably 3.0 to 55% by mass, even more preferably 5.0 to 50% by mass, and even more preferably 10 to 45% by mass. In this specification, the amount of component (A) is determined by selecting an appropriate method that does not decompose component (A) and can dissolve the regenerated collagen fibers, and then dissolving and extracting the fibers. The extracted solution is then appropriately diluted, and the absorbance is measured using, for example, an ultraviolet-visible-near-infrared spectrophotometer (e.g., V-560 (manufactured by JASCO Corporation)) at an absorption wavelength suitable for the quantification of component (A), and the content of component (A) is calculated from the absorbance. Alternatively, the peak area of ​​a chromatogram created using HPLC / UV or gel permeation chromatography (GPC) at an absorption wavelength suitable for the quantification of component (A) is measured, and the content of component (A) is calculated from the peak area.

[0079] From the viewpoint of improving water resistance, the modified regenerated collagen fibers of the present invention preferably further contain a polyvalent metal, a salt thereof, or a complex thereof as component (B). Examples include one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt thereof or a complex thereof. Of these, from the viewpoints of improving water resistance, reducing fiber discoloration, reducing environmental impact, and improving economic efficiency, one or more polyvalent metals selected from aluminum, zirconium, and titanium, or a salt thereof or a complex thereof, is preferably used, and more preferably aluminum, or a salt thereof or a complex thereof. These may be used alone or in combination of two or more.

[0080] The content of component (B) in the modified regenerated collagen fiber of the present invention 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, and even more preferably 2.0% by mass or more, in terms of improving water resistance, as the amount of metal element. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less. That is, the content of component (B) in the modified regenerated collagen fiber of the present invention is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, even more preferably 1.0 to 20% by mass, and even more preferably 2.0 to 10% by mass, in terms of the amount of metal element. The amount of component (B) in the modified regenerated collagen fiber is quantified, for example, as follows: The regenerated collagen fiber is incinerated, alkali-fused, and dissolved in acid to prepare a solution. Then, this solution is appropriately diluted to prepare a measurement sample, and the metal element is quantified using an ICP atomic emission spectrometer.

[0081] The modified regenerated collagen fibers of the present invention preferably further contain benzoic acid or a salt thereof as component (C), from the viewpoints of promoting retention and coordination within the fibers and improving water resistance, heat resistance, and thermal shape memory. The content of (C) benzoic acid or a salt thereof in the modified regenerated collagen fibers of the present invention is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, from the viewpoints of promoting retention and coordination within the fibers and improving water resistance, heat resistance, and thermal shape memory. It is also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less. That is, the content of (C) benzoic acid or a salt thereof in the modified regenerated collagen fibers of the present invention is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, even more preferably 10 to 30% by mass.

[0082] The modified regenerated collagen fibers of the present invention are fibers with highly improved water resistance, which can be shaped by heat setting due to the coordination of the carboxyl groups or salts thereof of component (A) retained within the fibers. The distribution of component (A) within the fiber cross section can be evaluated by cutting out a cross section of the fiber with a microtome, knife, razor, or the like, depending on the properties of component (A), and then performing linear or area analysis of the cross section using an optical microscope, a fluorescence microscope, a confocal laser microscope, fluorescence imaging, TOF-SIMS, EPMA, TEM / SEM-EDS, microscopic IR, microscopic laser Raman spectroscopy, or the like. More specifically, the distribution can be evaluated by, for example, the following method. When the cross section of the modified regenerated collagen fiber is measured by fluorescence imaging using a confocal laser microscope, if a clear difference in the fluorescence intensity within the fiber in the fluorescence image is observed compared to untreated regenerated collagen fibers, it can be determined that component (A) has penetrated into the fiber. For example, modified regenerated collagen fibers treated with styrene-maleic acid copolymer or a salt thereof as component (A) have a wavelength of 400 nm that is specific to styrene-maleic acid copolymer, and therefore, fluorescence imaging can be performed at an excitation wavelength of 400 nm and a detection wavelength of 425 to 475 nm. An example of a confocal laser microscope that can be used is the AIRHD25 (manufactured by Nikon Corporation).

[0083] [Method for producing modified regenerated collagen fiber] The method for producing modified regenerated collagen fiber of the present invention includes a step of treating regenerated collagen fiber by a regenerated collagen fiber treatment method. Specific aspects of the step of treating regenerated collagen fiber are as explained in the regenerated collagen fiber treatment method. The modified regenerated collagen fiber of the present invention can be suitably used as fiber for head accessories.

[0084] [Head ornament product and manufacturing method thereof] The head ornament product of the present invention comprises the modified regenerated collagen fiber of the present invention as a component element. The modified regenerated collagen fiber of the present invention may be used alone as a head ornament product, or may be mixed with other fibers to form a head ornament product. The other fibers are not particularly limited as long as they are fibers that can be used in head ornament products. Examples of other fibers include polyester fibers, human hair, animal hair, polyvinyl chloride fibers, modacrylic fibers, polyamide fibers, and polyolefin fibers. Among these, polyester fibers are preferred from the viewpoint of excellent heat resistance, flame retardancy, and curl retention, and flame-retardant polyester fibers are more preferred.

[0085] Flame-retardant polyester fibers are not particularly limited, but from the viewpoint of flame retardancy, they preferably contain 5 to 40 parts by mass of a brominated epoxy flame retardant per 100 parts by mass of one or more polyester resins selected from the group consisting of polyalkylene terephthalate and copolymer polyesters mainly composed of polyalkylene terephthalate. In the present invention, "mainly composed of" means containing 50 mol% or more, and "copolyesters mainly composed of polyalkylene terephthalate" refers to copolymer polyesters containing 50 mol% or more of polyalkylene terephthalate. Preferably, "copolyesters mainly composed of polyalkylene terephthalate" contain 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more of polyalkylene terephthalate. The flame-retardant polyester fibers preferably further contain 0 to 5 parts by mass of an antimony compound per 100 parts by mass of polyester resin. The inclusion of an antimony compound improves the flame retardancy of the polyester fibers.

[0086] Suitable head ornament products in the present invention include, for example, hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories, and doll hair. The method for producing a head ornament product of the present invention includes a step of treating regenerated collagen fibers using the regenerated collagen fiber treatment method described above. This allows various head ornament products to be produced. Specific aspects of the step of treating regenerated collagen fibers are as described in the regenerated collagen fiber treatment method. Furthermore, the method for producing a head ornament product using modified regenerated collagen fibers can be any conventionally known method depending on the type of head ornament product, and is not particularly limited.

[0087] With respect to the above-described embodiment, further preferred aspects of the present invention will be disclosed below.

[0088] <1> A method for treating regenerated collagen fibers, comprising the following step (i):

[0089] <2> A method for producing modified regenerated collagen fibers, comprising a step of treating regenerated collagen fibers by a regenerated collagen fiber treatment method including the following step (i):

[0090] <3> A method for producing a head accessory product, comprising a step of treating regenerated collagen fibers by a regenerated collagen fiber treatment method including the following step (i):

[0091] Step (i): A step of immersing regenerated collagen fibers, the fiber swelling ratio in water of which is calculated by the following formula (1) is 200% or more, in a fiber treatment agent containing the following component (A): (A) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof and a structural unit derived from an aromatic vinyl compound monomer, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1500 to 15000. Fiber swelling ratio in water (%) = [(w1 - w2) / w2] × 100 (1) (wherein w1 represents the mass (g) of the fiber measured by placing 1.0 g of fiber in a container filled with 100 g of ion-exchanged water, sealing the container, immersing the container in a water bath at 40°C for 30 minutes, removing the fiber from the container, and centrifuging and dehydrating it for 1 minute at a centrifugal force of 220 [×g]. w2 indicates the mass of the fiber measured after measuring the mass (w1) of the fiber and placing it on a filter paper and drying it at 105°C for 3 hours.

[0092] <4> The method for treating regenerated collagen fibers according to <1>, the method for producing modified regenerated collagen fibers according to <2>, or the method for producing a head accessory product according to <3>, wherein the fiber swelling rate in water is preferably 250% or more, more preferably 300% or more, even more preferably 350% or more, and preferably 1000% or less, more preferably 800% or less, even more preferably 600% or less, and even more preferably 500% or less. <5> The method for treating regenerated collagen fibers according to <1>, the method for producing modified regenerated collagen fibers according to <2>, or the method for producing a head accessory product according to <3>, wherein the fiber swelling rate in water is preferably 250 to 1000%, more preferably 300 to 800%, even more preferably 350 to 600%, and even more preferably 350 to 500%.

[0093] <6> The method for treating regenerated collagen fibers according to any one of <1>, <4> and <5>, the method for producing modified regenerated collagen fibers according to any one of <2>, <4> and <5>, or the method for producing a head accessory according to any one of <3> to <5>, wherein the regenerated collagen fibers preferably contain the following component (B): (B) a polyvalent metal, or a salt or complex thereof.

[0094] <7> The method for treating regenerated collagen fibers according to <6>, the method for producing modified regenerated collagen fibers according to <6>, or the method for producing a head ornament product according to <6>, wherein component (B) is preferably one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof, more preferably one or more polyvalent metals selected from aluminum, zirconium, and titanium, or a salt or complex thereof, and even more preferably aluminum, or a salt or complex thereof.

[0095] <8> The method for treating regenerated collagen fibers according to <6> or <7>, the method for producing a modified regenerated collagen fiber according to <6> or <7>, or the method for producing a head ornament product according to <6> or <7>, wherein the content of component (B) in the regenerated collagen fiber is, in terms of the amount of metal elements, preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.0% by mass or more, still more preferably 5.0% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and still more preferably 10% by mass or less. <9> The method for treating regenerated collagen fibers according to <6> or <7>, the method for producing a modified regenerated collagen fiber according to <6> or <7>, or the method for producing a head ornament product according to <6> or <7>, wherein the content of component (B) in the regenerated collagen fiber is, in terms of the amount of metal elements, preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, even more preferably 3.0 to 20% by mass, and still more preferably 5.0 to 10% by mass.

[0096] <10> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <9> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <9> above, or the method for producing a head ornament product according to any one of <3> to <9> above, preferably including a regenerated collagen fiber production step, prior to step (i), of solubilizing insoluble collagen fibers made from the split hide of livestock animals to obtain an aqueous collagen solution, discharging the resulting solution through a spinning nozzle or a slit, and immersing the resulting solution in an aqueous inorganic salt solution.

[0097] <11> The method for treating regenerated collagen fibers according to <10>, the method for producing modified regenerated collagen fibers according to <10>, or the method for producing a head ornament product according to <10> preferably comprises a crosslinking treatment step of immersing the regenerated collagen fibers in an epoxy compound monomer or a solution thereof after the regenerated collagen fiber production step.

[0098] <12> The method for treating regenerated collagen fibers according to <10>, the method for producing modified regenerated collagen fibers according to <10>, or the method for producing a head ornament product according to <10> preferably comprises a step of immersing the regenerated collagen fibers in an aqueous solution of an aluminum salt after the regenerated collagen fiber production step.

[0099] <13> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <12>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <12>, or the method for producing a head ornament product according to any one of <3> to <12>, wherein component (A) is a copolymer preferably containing a structural unit derived from one or more selected from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and salts thereof, and a structural unit derived from an aromatic vinyl compound.

[0100] <14> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <13> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <13> above, or the method for producing a head ornament product according to any one of <3> to <13> above, wherein component (A) preferably further contains a structural unit derived from an unsaturated aliphatic hydrocarbon compound.

[0101] <15> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <14> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <14> above, or the method for producing a head ornament product according to any one of <3> to <14> above, wherein component (A) is preferably one or more selected from 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, styrene-4-vinylbenzoic acid copolymer, and salts thereof, and more preferably styrene-maleic acid copolymer or a salt thereof.

[0102] <16> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <15>, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <15>, or the method for producing a head ornament product according to any one of <3> to <15>, wherein the molar ratio (u1 / u2) of the structural unit (u1) derived from an unsaturated monomer having a carboxy group or a salt thereof to the structural unit (u2) derived from an 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.

[0103] <17> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <16> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <16> above, or the method for producing a head ornament product according to any one of <3> to <16> above, wherein the acid value of component (A) 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. <18> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <16>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <16>, or the method for producing a head ornament product according to any one of <3> to <16>, wherein the acid value of component (A) is preferably 200 to 1000 mgKOH / g, more preferably 300 to 800 mgKOH / g, and even more preferably 400 to 600 mgKOH / g.

[0104] <19> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <18>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <18>, or the method for producing a head ornament product according to any one of <3> to <18>, wherein the weight-average molecular weight of component (A) is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and preferably 12,000 or less, more preferably 10,000 or less, even more preferably 8,000 or less, and still more preferably 7,000 or less. <20> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <18>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <18>, or the method for producing a head ornament product according to any one of <3> to <18>, wherein the weight-average molecular weight of component (A) is preferably 2,000 to 12,000, more preferably 3,000 to 12,000, and may also be preferably 1,500 to 10,000, more preferably 2,000 to 8,000, even more preferably 3,000 to 8,000, and still more preferably 4,000 to 7,000.

[0105] <21> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <20> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <20> above, or the method for producing a head ornament product according to any one of <3> to <20> above, wherein the content of component (A) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 1.0% by mass or more, even more preferably 2.3% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 30% by mass or less. <22> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <20>, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <20>, or the method for producing a head ornament product according to any one of <3> to <20>, wherein the content of component (A) in the fiber treatment agent is preferably 0.3 to 60% by mass, more preferably 1.0 to 50% by mass, even more preferably 2.3 to 40% by mass, and even more preferably 2.3 to 30% by mass.

[0106] <23> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <22> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <22> above, or the method for producing a head ornament product according to any one of <3> to <22> above, wherein the pH of the fiber treatment agent is preferably 2.0 or more, more preferably 3.0 or more, even more preferably 3.5 or more, even more preferably 4.0 or more, and preferably 11.0 or less, more preferably 10.0 or less, even more preferably 9.0 or less, even more preferably 7.0 or less, even more preferably 6.5 or less. <24> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <22> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <22> above, or the method for producing a head ornament product according to any one of <3> to <22> above, wherein the pH of the fiber treatment agent is preferably 2.0 to 11.0, more preferably 3.0 to 10.0, even more preferably 3.5 to 9.0, and even more preferably 3.5 to 6.5.

[0107] <25> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <24> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <24> above, or the method for producing a head ornament product according to any one of <3> to <24> above, wherein, when the pH of the fiber treatment agent is less than 5.5, the content of component (A) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 0.8% by mass or more, even more preferably 1.3% by mass or more, and further preferably 2.3% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. <26> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <24> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <24> above, or the method for producing a head ornament product according to any one of <3> to <24> above, wherein when the pH of the fiber treatment agent is less than 5.5, the content of component (A) in the fiber treatment agent is preferably 0.3 to 30% by mass, more preferably 0.8 to 20% by mass, even more preferably 1.3 to 10% by mass, and still more preferably 2.3 to 10% by mass.

[0108] <27> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <24> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <24> above, or the method for producing a head ornament product according to any one of <3> to <24> above, wherein, when the pH of the fiber treatment agent is 5.5 or higher, the content of component (A) in the fiber treatment agent is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.0% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less. <28> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <24> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <24> above, or the method for producing a head ornament product according to any one of <3> to <24> above, wherein when the pH of the fiber treatment agent is 5.5 or higher, the content of component (A) in the fiber treatment agent is preferably 1.0 to 60 mass%, more preferably 2.0 to 50 mass%, and even more preferably 3.0 to 40 mass%.

[0109] <29> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <28> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <28> above, or the method for producing a head ornament product according to any one of <3> to <28> above, wherein the fiber treatment agent preferably uses water as a medium, and the content of water in the fiber treatment agent preferably represents the remainder excluding component (A) and any optionally blended components. <30> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <28> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <28> above, or the method for producing a head ornament product according to any one of <3> to <28> above, wherein the fiber treatment agent preferably uses water as a medium, and the water content in the fiber treatment agent is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 40% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less, still more preferably 95% by mass or less, still more preferably 90% by mass or less, still more preferably 85% by mass or less. <31> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <28> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <28> above, or the method for producing a head ornament product according to any one of <3> to <28> above, wherein the fiber treatment agent preferably contains water as a medium, and the water content in the fiber treatment agent is preferably 10 to 98% by mass, more preferably 20 to 97% by mass, even more preferably 30 to 96% by mass, even more preferably 40 to 95% by mass, even more preferably 40 to 90% by mass, and even more preferably 40 to 85% by mass.

[0110] <32> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <31> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <31> above, or the method for producing a head ornament product according to any one of <3> to <31> above, wherein in step (i), the regenerated collagen fibers are preferably immersed in the fiber treatment agent two or more times.

[0111] <33> The method for treating regenerated collagen fibers according to <32>, the method for producing modified regenerated collagen fibers according to <32>, or the method for producing a head ornament product according to <32> preferably comprises a two-step treatment process in which, after treatment with a first fiber treatment agent containing the following component (A), the fiber is treated with a second fiber treatment agent containing the following component (A), the second fiber treatment agent having a pH adjusted to be 1.0 or more lower than that of the first fiber treatment agent. <34> The method for treating regenerated collagen fibers according to <33>, the method for producing modified regenerated collagen fibers according to <33>, or the method for producing a head ornament product according to <33> preferably comprises, after the two-step treatment process, a further step of treatment with an additional fiber treatment agent containing benzoic acid or a salt thereof as component (C). <35> The method for treating regenerated collagen fibers according to <32>, the method for producing a modified regenerated collagen fiber according to <32>, or the method for producing a head ornament product according to <32> preferably comprises a multi-step treatment step of treating the regenerated collagen fibers two or three or more times with a first fiber treatment agent containing the following component (A), followed by treatment with a second fiber treatment agent containing the following component (A), the second fiber treatment agent having a pH adjusted to be 1.0 or more lower than that of the first fiber treatment agent. <36> The method for treating regenerated collagen fibers according to <32>, the method for producing a modified regenerated collagen fiber according to <32>, or the method for producing a head ornament product according to <32> preferably comprises a step of treating with a first fiber treatment agent containing the following component (A), and a step of treating with an additional fiber treatment agent containing benzoic acid or a salt thereof as component (C).

[0112] (A) A copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 to 15,000.

[0113] <37> The method for treating regenerated collagen fibers according to <34> or <36>, the method for producing modified regenerated collagen fibers according to <34> or <36>, or the method for producing a head ornament product according to <34> or <36>, wherein the content of (C) benzoic acid or a salt thereof in the additional fiber treatment agent is, in terms of benzoic acid, preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, still more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, still more preferably 40% by mass or less, and still more preferably 35% by mass or less. <38> The method for treating regenerated collagen fibers according to <34> or <36>, the method for producing modified regenerated collagen fibers according to <34> or <36>, or the method for producing a head ornament product according to <34> or <36>, wherein the content of (C) benzoic acid or a salt thereof in the additional fiber treatment agent is preferably 0.1 to 60% by mass, more preferably 1 to 55% by mass, even more preferably 5 to 50% by mass, still more preferably 10 to 40% by mass, and even more preferably 20 to 35% by mass, in terms of benzoic acid.

[0114] <39> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <38> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <38> above, or the method for producing a head ornament product according to any one of <3> to <38> above, wherein the amount of fiber treatment agent is, in terms of bath ratio to the mass of regenerated collagen fibers (mass of fiber treatment agent / mass of regenerated collagen fibers), preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, even more preferably 10 or more, even more preferably 20 or more, and is preferably 500 or less, more preferably 250 or less, even more preferably 100 or less, even more preferably 50 or less. <40> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <38>, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <38>, or the method for producing a head ornament product according to any one of <3> to <38>, wherein the amount of the fiber treatment agent is, in terms of bath ratio to the mass of the regenerated collagen fibers (mass of fiber treatment agent / mass of regenerated collagen fibers), preferably 2 to 500, more preferably 3 to 250, even more preferably 5 to 100, even more preferably 10 to 100, even more preferably 20 to 100, even more preferably 20 to 50.

[0115] <41> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <40> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <40> above, or the method for producing a head ornament product according to any one of <3> to <40> above, wherein the temperature at which the regenerated collagen fibers are immersed in the fiber treatment agent is preferably 20°C or higher, more preferably 25°C or higher, even more preferably 30°C or higher, and is preferably lower than 100°C, more preferably 80°C or lower, even more preferably 70°C or lower, even more preferably 60°C or lower, and still more preferably 50°C or lower. <42> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <40> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <40> above, or the method for producing a head ornament product according to any one of <3> to <40> above, wherein the temperature at which the regenerated collagen fibers are immersed in the fiber treatment agent is preferably 20°C or higher but lower than 100°C, more preferably 25 to 80°C, even more preferably 30 to 70°C, even more preferably 30 to 60°C, and still more preferably 30 to 50°C.

[0116] <43> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <42> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <42> above, or the method for producing a head ornament product according to any one of <3> to <42> above, wherein the immersion time is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, still more preferably 3 hours or more, still more preferably 5 hours or more, still more preferably 10 hours or more, and preferably 48 hours or less, more preferably 33 hours or less, and still more preferably 30 hours or less. <44> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <42> above, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <42> above, or the method for producing a head ornament product according to any one of <3> to <42> above, wherein the immersion time is preferably from 15 minutes to 48 hours, more preferably from 30 minutes to 33 hours, even more preferably from 1 hour to 30 hours, still more preferably from 3 hours to 30 hours, still more preferably from 5 hours to 30 hours, and still more preferably from 10 hours to 30 hours.

[0117] <45> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <44>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <44>, or the method for producing a head ornament product according to any one of <3> to <44>, preferably wherein step (i) is carried out in an environment in which evaporation of water is suppressed.

[0118] <46> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <45>, the method for producing modified regenerated collagen fibers according to any one of <2> and <4> to <45>, or the method for producing a head ornament product according to any one of <3> to <45>, wherein the fiber treatment agent is a fiber-penetrating agent.

[0119] <47> The method for treating regenerated collagen fibers according to any one of <1> and <4> to <46> above, the method for producing a modified regenerated collagen fiber according to any one of <2> and <4> to <46> above, or the method for producing a head ornament product according to any one of <3> to <46> above, wherein, when the copolymer related to component (A) is in the form of a salt, the salt is preferably an alkali metal salt, an alkaline earth metal salt, or an ammonium salt, more preferably a sodium salt, a lithium salt, a potassium salt, a calcium salt, or a magnesium salt, and even more preferably a sodium salt. <48> The method for treating regenerated collagen fibers according to any one of <34> to <38> above, the method for producing a modified regenerated collagen fiber according to any one of <34> to <38> above, or the method for producing a head ornament product according to any one of <34> to <38> above, wherein, when component (C) is in the form of a salt, the salt is preferably an alkali metal salt, more preferably a sodium salt or a potassium salt, and even more preferably a sodium salt.

[0120] <49> Modified regenerated collagen fibers comprising the following component (A) in the regenerated collagen fibers: (A) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group or a salt thereof 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;

[0121] <50> The modified regenerated collagen fiber according to <49>, wherein component (A) is preferably a copolymer containing a copolymer containing a structural unit derived from one or more selected from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and salts thereof, and a structural unit derived from an aromatic vinyl compound.

[0122] <51> The modified regenerated collagen fiber according to <49> or <50>, wherein component (A) is preferably one or more selected from 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, styrene-4-vinylbenzoic acid copolymer, and salts thereof, and more preferably styrene-maleic acid copolymer or a salt thereof.

[0123] <52> The modified regenerated collagen fiber according to any one of the above items <49> to <51>, wherein component (A) preferably further contains a structural unit derived from an unsaturated aliphatic hydrocarbon compound.

[0124] <53> The modified regenerated collagen fiber according to any one of the above items <49> to <52>, wherein the molar ratio (u1 / u2) of the structural unit (u1) derived from an unsaturated monomer having a carboxy group or a salt thereof to the structural unit (u2) derived from an 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.

[0125] <54> The modified regenerated collagen fiber according to any one of the above items <49> to <53>, wherein when the carboxyl group of component (A) is in the form of a salt, the salt is preferably an alkali metal salt, an alkaline earth metal salt, or an ammonium salt, more preferably a sodium salt, a lithium salt, a potassium salt, a calcium salt, or a magnesium salt, and even more preferably a sodium salt.

[0126] <55> The modified regenerated collagen fiber according to any one of the above <49> to <54>, wherein the acid value of component (A) 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. <56> The modified regenerated collagen fiber according to any one of the above <49> to <54>, wherein the acid value of component (A) is preferably 200 to 1000 mgKOH / g, more preferably 300 to 800 mgKOH / g, even more preferably 400 to 600 mgKOH / g.

[0127] <57> The modified regenerated collagen fiber according to any one of the above <49> to <56>, wherein the weight-average molecular weight of component (A) is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and preferably 12,000 or less, more preferably 10,000 or less, even more preferably 8,000 or less, even more preferably 7,000 or less. <58> The weight-average molecular weight of component (A) is preferably 2,000 to 12,000, more preferably 3,000 to 12,000. Alternatively, it may be preferably 2,000 to 8,000, more preferably 3,000 to 8,000, even more preferably 4,000 to 7,000.

[0128] <59> The modified regenerated collagen fiber according to any one of the above <49> to <58>, wherein the content of component (A) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less. <60> The modified regenerated collagen fiber according to any one of the above <49> to <58>, wherein the content of component (A) is preferably 0.1 to 70% by mass, more preferably 0.5 to 65% by mass, even more preferably 1.0 to 60% by mass, even more preferably 3.0 to 55% by mass, even more preferably 5.0 to 50% by mass, and even more preferably 10 to 45% by mass.

[0129] <61> The modified regenerated collagen fiber according to any one of the above items <49> to <60>, preferably further comprising the following component (B): (B) a polyvalent metal, or a salt or complex thereof.

[0130] <62> The modified regenerated collagen fiber according to <61>, wherein component (B) is preferably one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof, more preferably one or more polyvalent metals selected from aluminum, zirconium, and titanium, or a salt or complex thereof, and even more preferably aluminum, or a salt or complex thereof.

[0131] <63> The modified regenerated collagen fiber according to <61> or <62> above, wherein the content of component (B) is, in terms of the amount of metal elements, 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 2.0% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and still more preferably 10% by mass or less. <64> The modified regenerated collagen fiber according to <61> or <62> above, wherein the content of component (B) is, in terms of the amount of metal elements, preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, even more preferably 1.0 to 20% by mass, and still more preferably 2.0 to 10% by mass.

[0132] <65> A head accessory product comprising the modified regenerated collagen fiber according to any one of <49> to <64> as a component.

[0133] <66> The head accessory product according to <65>, which is selected from hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories and doll hair.

[0134] <Analysis Method> 1. Measurement of fiber swelling ratio of regenerated collagen fiber in water The fiber swelling ratio in water was calculated according to the following formula (1).

[0135] Fiber swelling ratio in water S (%) = [(w1 - w2) / w2] × 100 (1)

[0136] The definitions of each symbol in formula (1) are as follows. w1: 1.0 g of regenerated collagen fibers were immersed in a container containing 100 g of ion-exchanged water, the container was sealed, and the entire container was immersed in a water bath (model number: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) set to 40°C and heated for 30 minutes. The regenerated collagen fibers were then removed from the container and placed in a small centrifuge (H-112, Kokusan Co., Ltd.) and centrifuged for 1 minute at a centrifugal force of 220 [×g] (rotation speed dial "4" (2000 rpm)). The fibers were then removed and immediately weighed, and this was designated weight w1. w2: The regenerated collagen fibers after measuring weight w1 were placed on filter paper and placed in a dryer (SOFW-450SB, AS ONE Corporation) set to 105°C and dried for 3 hours. The fibers were then removed and immediately weighed, and this was designated weight w2.

[0137] 2. Measurement of Weight-Average Molecular Weight of Component (A) The weight-average molecular weight (Mw) in terms of polystyrene was measured by gel permeation chromatography (GPC) under the following conditions. (1) Reagents: Ultrapure water: Milli-Q ultrapure water production system, 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. The resulting solution was filtered to obtain a sample solution. (3) Measurement: GPC measurement was performed using the sample solution and standard solution 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) Standard material: monodisperse polystyrene

[0138] 3. Method for Determining Aluminum in Fibers The amount of aluminum contained in the regenerated collagen fibers after treatment was determined using the following method. (1) Reagents: Sulfuric acid: for precision analysis, Fujifilm Wako Pure Chemical Industries, Ltd. Hydrochloric acid: for metal analysis, Kanto Chemical Co., Ltd. Sodium carbonate: special grade, Fujifilm Wako Pure Chemical Industries, Ltd. Boric acid: special grade, Fujifilm Wako Pure Chemical Industries, Ltd. Aluminum standard solution: for atomic absorption analysis 1000 mg / L, Kanto Chemical Co., Ltd. Ultrapure water: water produced by ultrapure water production system Milli-Q, Millipore Corporation (2) Sample Pretreatment Method: The fiber bundle 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. 0.1 g of sample was accurately weighed into a platinum crucible and heated until no white smoke was produced. A few drops of sulfuric acid were added, and the mixture was heated again until no white smoke was produced. It was then thoroughly incinerated in an electric furnace at 550 °C. 1 g of alkaline flux (sodium carbonate:boric acid = 1:0.4) was added and melted in an electric furnace at 950 °C. 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 sample. (4) Measurement: The prepared samples were measured for each element 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

[0139] 4. Measurement of Acid Value: Measured by potentiometric titration in accordance with JIS K 0070.

[0140] 5. Measurement of pH Each composition was measured as it was at 25° C. using a pH meter (F-52, manufactured by HORIBA).

[0141] 6. Quantitative Analysis of Component (A) in Fibers The quantitative analysis method for component (A) in modified regenerated collagen fibers when styrene-maleic acid copolymer is used is described below. (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 Co., Ltd. (2) Sample Solution: The sample was conditioned at 20°C and 65% relative humidity for 24 hours, then finely chopped. Approximately 50 mg was precisely weighed, and 10 mL of 1 mol / L aqueous sodium hydroxide solution was added and 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 fiber.

[0142] 7. Quantitative Method for Component (C) in Fiber The amount of component (C) contained in the regenerated collagen fibers after treatment is quantified using the following method. (1) Reagents: 6N hydrochloric acid: titrant for volumetric analysis, manufactured by Kanto Chemical Co., Ltd.; Sodium acetate: special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; Acetic acid: special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; Acetonitrile: for LC / MS, manufactured by Kanto Chemical Co., Ltd.; Sodium benzoate: special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; Ultrapure water: water produced by ultrapure water production system Milli-Q, manufactured by Millipore Corporation. (2) Sample Pretreatment Method: The sample is finely chopped, and approximately 10 mg is precisely weighed out. 3 mL of 6N hydrochloric acid is added and the mixture is heated and dissolved at 50°C for 15 hours. After cooling, the mixture is filtered to obtain the sample solution. (3) Preparation of calibration curve solution: Separately, dissolve component (A) in the mobile phase. If there is a dissociation site, such as an acid group, prepare a non-dissociated component (A) at a concentration of 0.1 to 100 μg / mL to prepare a standard solution for drawing a calibration curve. (4) Measurement: Test the sample solution and standard solution using liquid chromatography under the following conditions, and measure the peak area of ​​the sample solution and the peak area of ​​the standard solution. Detector: UV-visible spectrophotometer Measurement wavelength: 230 nm Column: A stainless steel tube with an inner diameter of 21 mm and a length of 150 mm is packed with 5 μm octadecylsilylated silica gel for liquid chromatography. Column temperature: A constant temperature of around 40°C Mobile phase: Dissolve approximately 0.68 g of sodium acetate and 0.91 g of acetic acid in 750 mL of ultrapure water, add 250 mL of acetonitrile, and mix. (5) HPLC / UV Conditions Apparatus: UltiMate 3000 system (manufactured by Thermo Fisher Scientific) Column: L-column 2 ODS, particle size 5 μm, 2.1 × 150 mm (Chemicals Evaluation and Research Institute, Japan) Column temperature: 40°C Mobile phase: 20 mM ammonium acetate, 25% acetonitrile buffer Analysis time: 10 minutes Detector: DAD (diode array detector) Detection wavelength: 230 nm Flow rate: 0.3 mL / min (isocratic elution) Injection volume: 10 μL

[0143] <Raw Materials Used> The materials used in this example are as follows. (1) Regenerated Collagen Fiber (i) Regenerated Collagen Fiber A Production Example 1: Cow split hide was solubilized with alkali according to standard methods to prepare a spinning dope. This was then extruded from a spinning nozzle into a coagulation bath for fiberization, followed by treatment with an epoxy compound 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 per part by mass of the regenerated collagen fibers (equivalent to the dry weight of the fibers) at a temperature adjusted to 30°C while circulating the solution. A 5% aqueous sodium hydroxide solution was then added in portions over approximately 1 to 5 hours to adjust the final pH of the solution after 5 hours to 4.5 to 5.0. The regenerated collagen fibers were then retained in the solution for another 3 hours and thoroughly washed with water to obtain regenerated collagen fiber A. Regenerated collagen fiber A had a fiber swelling ratio in water of 435%. The preparation of the coagulation bath was carried out in accordance with WO 2017 / 159565, and the epoxy compound treatment was carried out in accordance with WO 2014 / 132889.

[0144] (ii) Regenerated Collagen Fiber B 300 fiber bundles (amount that would weigh 1.5 g when dried at 60°C for 1 hour and then left at 20°C and 65% RH for 12 hours) with a length of 30 cm were prepared from regenerated collagen fiber A. Each fiber bundle was hung individually in a dryer (SOFW-450SB, AS ONE Corporation) set to 60°C, a 250 g weight was attached to the bottom end of each fiber bundle, and the fiber was dried for 1 hour with tension applied to the entire fiber, which was used as regenerated collagen fiber B. Shape: Straight Fiber swelling rate in water: 113% Aluminum content: 6.8% by mass

[0145] (iii) Regenerated Collagen Fiber C Production Example 2 Cow 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 form fibers, which were then treated with an epoxy compound and thoroughly washed with water to obtain regenerated collagen fiber C. The regenerated collagen fiber C had a fiber swelling rate in water of 692%. The coagulation bath was prepared according to WO 2017 / 159565, and the epoxy compound treatment was carried out according to WO 2014 / 132889.

[0146] (2) Styrene-maleic acid copolymer (i) Styrene-maleic acid copolymer sodium salt A XIRAN1000HNa (manufactured by Polyscope) was used. Weight average molecular weight (Mw): 9195 Acid value: 475 mg KOH / g Molar ratio of styrene / maleic acid: 1 / 1

[0147] (ii) Styrene-maleic acid copolymer sodium salt B XIRAN2000HNa (manufactured by Polyscope) was used. Weight average molecular weight (Mw): 8143 Acid value: 355 mg KOH / g Molar ratio of styrene / maleic acid: 2 / 1

[0148] (iii) Styrene-maleic acid copolymer sodium salt C XIRAN3000HNa (manufactured by Polyscope) was used. Weight average molecular weight (Mw): 13,803 Acid value: 285 mg KOH / g Molar ratio of styrene / maleic acid: 3 / 1

[0149] (iv) Styrene-maleic acid copolymer sodium salt D Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460 (2002)) and used after hydrolyzing with sodium hydroxide. Weight average molecular weight (Mw): 7049 Hydrogen bond term δH value of Hansen solubility parameter: 11.5 Acid value: 475 mg KOH / g Molar ratio of styrene / maleic acid: 1 / 1

[0150] (v) Styrene-maleic acid copolymer sodium salt E Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460 (2002)) and hydrolyzed with sodium hydroxide before use. Weight average molecular weight (Mw): 3829 Hydrogen bond term δH value of Hansen solubility parameter: 11.5 Acid value: 475 mg KOH / g Molar ratio of styrene / maleic acid: 1 / 1

[0151] (vi) Styrene-maleic acid copolymer sodium salt F Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460 (2002)) and used after hydrolyzing with sodium hydroxide. Weight average molecular weight (Mw): 10,530 Hydrogen bond term δH value of Hansen solubility parameter: 11.5 Acid value: 475 mg KOH / g Molar ratio of styrene / maleic acid: 1 / 1

[0152] (vii) Styrene-maleic acid copolymer sodium salt G Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460 (2002)) and used after hydrolyzing with sodium hydroxide. Weight average molecular weight (Mw): 3288 Hydrogen bond term δH value of Hansen solubility parameter: 11.5 Acid value: 475 mg KOH / g Molar ratio of styrene / maleic acid: 1 / 1

[0153] (3) Sodium benzoate: Wako Special Grade Reagent (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. Molecular weight (M): 122 Acid value: 460 mg KOH / g

[0154] Examples 1 to 15 and Comparative Examples 1 to 3 Regenerated collagen fibers were treated according to the methods described below using compositions formulated as shown in Tables 1 and 2, and various evaluations were carried out. In Comparative Example 1, only (Procedure 1) and (Procedure 6) of the treatment method A described below were carried out and evaluated. The results of Examples 1 to 11 and Comparative Examples 1 and 2 are shown in Table 1, and the results of Examples 12 to 15 and Comparative Example 3 are shown in Table 2, along with the result of Comparative Example 1.

[0155] <Treatment Method> (1) Treatment Method A Regenerated collagen fiber A was treated according to the following procedure. (Procedure 1) Ten 30 cm long fiber bundles (amounts that would weigh 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 regenerated collagen fiber A for each Example and Comparative Example. (Procedure 2) Each fiber bundle was immersed in a separate container in an amount of fiber treatment agent at the bath ratio shown in the table (calculated based on the 1.5 g weight after drying in Procedure 1 above), 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 the temperature shown in the table and left to stand for 5 minutes. The liquid temperature in the container was then raised to the temperature shown in the table, 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 to the temperature shown in the table, and the container was rotated at a rotation speed of 80 rpm, followed by heating and stirring for the time shown in the table. (Procedure 5) 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 and rinsed with running tap water at 30°C for 30 seconds, and the hair flow was adjusted with a comb. (Procedure 6) The fiber bundles were hung one by one in a dryer set to the temperature shown in the table, and a 250 g weight was attached to the bottom end of each fiber bundle. Drying was performed for the time shown in the table with tension applied to the entire fiber. (Procedure 7) The fiber bundles were removed from the dryer, returned to room temperature, and the weight was removed.

[0156] (2) Treatment Method B Regenerated collagen fiber B was treated according to the following procedure. (Procedure 1) Ten 30 cm long fiber bundles each weighing 1.5 g (measured after standing for 12 hours at 20°C and 65% RH) were prepared from regenerated collagen fiber B for each Example and Comparative Example. (Procedure 2) Each fiber bundle was immersed in a separate container in an amount of fiber treatment agent at the bath ratio shown in the table (the bath ratio was calculated based on the 1.5 g fiber weight obtained in Procedure 1 above), 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 the temperature shown in the table and allowed to stand for 5 minutes. The liquid temperature in the container was then raised to the temperature shown in the table, after which the container was 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 to the temperature shown in the table, and the container was rotated at a rotation speed of 80 rpm, followed by heating and stirring for the time shown in the table. (Procedure 5) 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 and rinsed with running tap water at 30°C for 30 seconds, and the hair flow was adjusted with a comb. (Procedure 6) The fiber bundles 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 7) The fiber bundles were removed from the dryer, returned to room temperature, and the weight was removed.

[0157] <Evaluation> 1. Quantitation (i) Weight Increase (%) The weight (W) of the fiber bundle after treatment was measured after leaving it at 20°C and 65% RH for 12 hours, and the weight increase rate from the initial fiber bundle weight of 1.5 g was calculated.

[0158] Weight increase [%] = [(W - 1.5) / 1.5] x 100

[0159] A larger weight increase (%) indicates that a larger amount of component (A) has penetrated into the interior of the fiber, and a weight increase (%) of 0% is considered to indicate that substantially no penetration of component (A) has occurred into the interior of the fiber.

[0160] (ii) Amount (%) of component (A) (Mw 1500-15,000) contained within the fiber: The amount of component (A) in the modified regenerated collagen fiber, "GPC quantitative value Y (%)," was calculated based on the chromatogram obtained by GPC measurement described in "6. Quantitative method for component (A) in fiber" under <Analysis Methods>. Note that "GPC quantitative value Y (%)" is the mass % of component (A) in the fiber and does not coincide with the measured weight increase (%). In other words, since the weight-average molecular weight of the copolymer related to component (A) is 1500-15,000, "GPC quantitative value Y (%)" here does not refer to the amount of the fraction with a molecular weight of 1500-15,000 in the GPC chromatogram, but rather to the quantitative value of the entire copolymer related to component (A), including fractions with molecular weights of less than 1500 and more than 15,000. Therefore, in the case of a copolymer having a weight-average molecular weight of less than 1,500 or more than 15,000, the copolymer does not fall under the category of component (A), and therefore the quantitative value for component (A) is 0. Then, the "theoretical weight gain X (%)" calculated from the "GPC quantitative value Y (%)" was calculated by the following method.

[0161] (iii) Theoretical weight gain (%) Based on the GPC quantitative value Y (%) calculated in (ii) above, the theoretical weight gain X (%) was calculated using the following formula. The theoretical weight gain X (%) is the maximum value when it is assumed that no components are lost from the fiber due to elution or the like.

[0162] Weight increase X [%] = 100Y / (100-Y)

[0163] 2. Water Resistance (1) Elastic Modulus (MPa) When Fibers are Tensioned in Water The elastic modulus when fibers are tensioned in water was measured as follows. Evaluation was performed using a fiber bundle immediately after treatment using the above-mentioned <Treatment Method>. The average value when multiple (five) fibers were evaluated was used as the numerical value. A higher numerical value indicates firmness, resistance to stretching due to external force, and superior durability. Evaluation was performed using the following procedure. (Procedure 1) Five fibers were cut from the fiber bundle, and 3 cm fiber pieces were taken from each, resulting in a total of five 3 cm fiber pieces. (Procedure 2) The fiber pieces were placed in an automatic fiber tensile tester (MTT690, manufactured by DIA-STRON Limited). After the fibers were left immersed in water for 30 minutes, automatic tensile measurement was started to determine the elastic modulus when the fibers were tensioned in water. The cross-sectional area of ​​the fiber in water, which is necessary for determining the elastic modulus, was separately measured directly by optical microscopy.

[0164] (2) Increase in Average Breaking Elongation During Fiber Pulling (%) As an index of water resistance and stretchability (tenacity) during fiber pulling, the average breaking elongation, i.e., the percentage of stretching relative to the original fiber length at which the fiber breaks when pulled, was evaluated for multiple (10) fibers and the average value was used. The evaluation was performed using a fiber bundle immediately after the above-mentioned <Processing Method> treatment, as follows: (Procedure 1) Ten fibers were cut from the base of the fiber bundle. A 3 cm fiber piece was taken from the midpoint between the base and the tip of each fiber, resulting in a total of 10 3 cm hair pieces. (Procedure 2) The fiber pieces were placed in an automatic fiber tensile tester (MTT690, manufactured by DIA-STRON Limited). After leaving the fiber immersed in water for 30 minutes, automatic measurement was started, and the average breaking elongation was determined for the fiber immersed in water. The higher the value, the more elastic, tough and durable the material is.

[0165] According to the following formula, the average breaking elongation (A%) when the regenerated collagen fiber A was pulled without being treated with any chemicals and only dried (only the above-mentioned treatment method A (Step 1) and (Step 6) were performed, hereinafter also referred to as "untreated fiber (Comparative Example 1)") was used as the standard, and the increase (C%) in the average breaking elongation (B%) of the treated fiber bundle from the untreated state was recorded in the table as "increase rate (%) in average breaking elongation when the fiber was pulled."

[0166] Increase in average breaking elongation during fiber tension C (%) = B (%) - A (%)

[0167] (3) Increase in average breaking load when fiber is stretched (gf) The average breaking load when fiber is stretched was used as an index of water resistance when fiber is stretched. Evaluation was performed using a fiber bundle immediately after treatment with the above-mentioned <Treatment Method>. The numerical value was the average value when multiple fibers (10 fibers) were evaluated. The evaluation was performed using the following procedure. (Procedure 1) Ten fibers were cut from the base of the fiber bundle. A 3 cm fiber piece was taken from near the middle between the base and the tip of each fiber, resulting in a total of 10 3 cm hair pieces. (Procedure 2) The fiber pieces were placed in an automatic fiber tensile tester (MTT690, manufactured by DIA-STRON Limited). After leaving the fiber immersed in water for 30 minutes, automatic measurement was started to determine the breaking load when the fiber was stretched while immersed in water. A higher numerical value indicates resistance to breakage due to external force and superior durability.

[0168] According to the following formula, the average breaking load (W0 (gf)) when the regenerated collagen fiber A was pulled after drying without any chemical treatment [untreated fiber (Comparative Example 1)] was used as the standard, and the increase (Y (gf)) in the average breaking load (W1 (gf)) of the treated fiber bundle from the untreated state was recorded in the table as "Increase in average breaking load when the fiber was pulled [gf]".

[0169] Y(gf)=W1(gf)-W0(gf)

[0170] (4) Concentration (ppm) of Component (A) in Fiber Cleaning Solution The concentration of component (A) in the fiber cleaning solution was measured using the following procedure. The evaluation was performed using fiber bundles obtained in Example 1 and Comparative Example 3 immediately after treatment using the above-mentioned <Treatment Method>. (i) Preparation of Fiber Cleaning Solution Fibers were cut from the base of the fiber bundle to prepare 1.0 g of fiber bundle. This 1.0 g of fiber bundle was immersed in a container containing 100 g of ion-exchanged water, the container was sealed, and the container was immersed in a water bath (model number: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) set at 40°C and heated for 1 hour, after which the fibers were removed from the container. The ion-exchanged water remaining in the container was used as the fiber cleaning solution. (ii) Quantification of Component (A) in Fiber Cleaning Solution Quantification was performed by measuring the absorbance at a suitable wavelength using an ultraviolet-visible-near-infrared spectrophotometer. For example, when component (A) was a styrene-maleic acid copolymer sodium salt (XIRAN1000HNa, manufactured by Polyscope), the absorbance at 258 nm was measured using an ultraviolet-visible-near-infrared spectrophotometer (V-560, manufactured by JASCO Corporation), and the concentration of component (A) was calculated from the absorbance. A calibration curve was prepared by diluting "XIRAN1000HNa" manufactured by Polyscope with ion-exchanged water.

[0171] 3. Thermal Shape Memory Ability The thermal shape memory ability was evaluated using a fiber bundle immediately after the treatment described above. 0.5 g of fiber was cut from the base of the fiber bundle to prepare a 22 cm long fiber bundle. In the evaluation of "(I) Shaping (Curl)," if the curl-up ratio I was 7% or less, the treatment was deemed ineffective and subsequent treatments and evaluations were not performed. (I) Shaping (Curl) (Procedure 1) The prepared 22 cm long fiber bundle was wetted with 30°C tap water for 30 seconds, and then the wet fiber bundle was wrapped around a 14 mm diameter plastic rod and secured with a clip. (Procedure 2) The fiber bundle wrapped around the rod was immersed in a 60°C water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) and heated for 1 minute. (Procedure 3) The fiber bundle was removed from the water bath, immersed in 20°C water for 1 minute, removed from the water, and allowed to return to room temperature. (Step 4) The fiber bundle was removed from the rod, combed three times, and then photographed from the side while hanging, 3 minutes after it was removed from the water. (Step 5) From the photograph, the length L of the fiber bundle when it was hung vertically (the distance from the top end of the fiber bundle to the furthest point) was measured.

[0172] (Evaluation Criteria) The length of the fiber bundle when stretched in a straight line was defined as L0, and the length of the fiber bundle after the shaping operation was defined as L. The curl-up ratio calculated according to the following formula = fiber bundle length reduction ratio (I) (%) was defined as the curl winding strength.

[0173] Curl-up ratio I (%) = [(L0 - L) / L0] x 100

[0174] (II) Reshaping (Straightening) (Procedure 1) The fiber bundle evaluated in (1) above was combed to straighten the hair flow, and then slid six times at a speed of 5 cm / sec with a flat iron (AHI-938, manufactured by Miki Electric Industrial Co., Ltd.) set at 180°C. (Procedure 2) Rinse with running tap water at 30°C for 30 seconds and towel dry. (Procedure 3) Hang and air dry for 12 hours at 20°C and 65% RH, then comb through three times, and photograph from the side while hanging. (Procedure 4) From the photograph, the length L (the distance from the top end of the fiber bundle to the furthest point) when the fiber bundle was hung vertically was measured.

[0175] (Evaluation Criteria) The length of the fiber bundle when stretched straight is L0, and the length of the fiber bundle after the shaping operation is L. The straightening rate (ST) (%) calculated according to the following formula was defined as the degree of achievement of straightening. When ST = 100%, the fiber bundle is completely straightened.

[0176] Straightening rate ST (%) = [1 - [(L0 - L) / L0]] x 100

[0177] (III) Reshaping (Curling) (Procedure 1) The fiber bundle evaluated in (2) above was wetted with 30°C tap water for 30 seconds, and then the wet fiber bundle was wound around a 14 mm diameter plastic rod and secured with a clip. (Procedure 2) The fiber bundle wound around the rod was immersed in a 60°C water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) and heated for 1 minute. (Procedure 3) The fiber bundle was removed from the water bath, immersed in 20°C water for 1 minute, removed from the water, and allowed to return to room temperature. (Procedure 4) The fiber bundle was removed from the rod, combed three times, and then photographed from the side while hanging 3 minutes after removal from the water. (Procedure 5) The length L of the fiber bundle when hanging vertically (the distance from the top end of the fiber bundle to the furthest point) was measured from the photograph.

[0178] (Evaluation Criteria) The length of the fiber bundle when stretched in a straight line was defined as L0, and the length of the fiber bundle after the shaping operation was defined as L. The curl-up ratio calculated according to the following formula = fiber bundle length reduction ratio (I) (%) was defined as the curl winding strength.

[0179] Curl-up ratio I (%) = [(L0 - L) / L0] x 100

[0180] 4. Fiber swelling ratio in water (%) The fiber swelling ratio in water was calculated by the following formula (1): Evaluation was carried out using the fiber bundle immediately after treatment by the above-mentioned <Treatment method>.

[0181] Fiber swelling ratio in water S (%) = [(w1 - w2) / w2] × 100 (1)

[0182] The definitions of each symbol in formula (1) are as follows. w1: Fibers were cut from the base of the fiber bundle to prepare a 1.0 g fiber bundle. This 1.0 g fiber bundle was immersed in a container containing 100 g of ion-exchanged water, the mouth of the container was sealed, and the container was immersed in a water bath (model number: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) set to 40 ° C. and heated for 30 minutes. The fibers were then removed from the container and placed in a small centrifuge (H-112, Kokusan Co., Ltd.) and centrifuged for 1 minute at a centrifugal force of 220 [× g] (rotation speed dial "4" (2000 rpm)). The fibers were then removed and immediately weighed, and this was designated weight w1. w2: The fibers after measuring weight w1 were placed on filter paper and placed in a dryer (SOFW-450SB, AS ONE Corporation) set to 105 ° C., dried for 3 hours, and then removed. The weight was immediately measured and designated weight w2.

[0183] 5. Surface feel: The surface feel was evaluated by five expert panelists using the fiber bundle immediately after treatment with the <Treatment method> to evaluate the smoothness of the feel when touched with the hand according to the following criteria, and the total value of the five panelists was used as the evaluation result.

[0184] (Evaluation criteria) 5: Extremely smooth to the touch compared to untreated fiber (Comparative Example 1) 4: Smoother to the touch compared to untreated fiber (Comparative Example 1) 3: Slightly smoother to the touch compared to untreated fiber (Comparative Example 1) 2: No difference in the touch from untreated fiber (Comparative Example 1) 1: Rougher and squeakier than untreated fiber (Comparative Example 1), and the touch is inferior

[0185] 6. Heat Resistance (1) Shrinkage (%) after Contact with Water Vapor at 110°C The shrinkage after contact with water vapor at 110°C was measured using the following procedure. Evaluation was performed using a fiber bundle immediately after treatment using the above-mentioned <Treatment Method>. (Procedure 1) Fibers were cut from the fiber bundle, and both ends of each five-fiber bundle were fixed with tape (Scotch tape, manufactured by 3M) to prepare a sample. 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 110°C for 10 minutes. (Procedure 3) The sample was removed, and the length h 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 H (%) after contact with water vapor at 110°C. The closer H is to 0%, the less likely the sample is to shrink due to heat, indicating better heat resistance.

[0186] Shrinkage rate after contact with water vapor at 110°C H (%) = [(10 - h) / 10] x 100

[0187] (wherein h represents the length (cm) of the sample after heating at 110°C for 10 minutes.)

[0188] The heat resistance of the fibers was evaluated according to the following criteria: The shrinkage rate H0 (%) of regenerated collagen fiber A after contact with water vapor at 110°C in a state where it was dried without any chemical treatment [untreated fiber (Comparative Example 1)] was used as the standard. The heat resistance was evaluated with a score of A to E according to the value of ΔH calculated by ΔH = H0 - H.

[0189] (Evaluation criteria) A: 6<ΔH B: 4<ΔH≦6 C: 2<ΔH≦4 D: 0<ΔH≦2 E: ΔH≦0

[0190] 7. Suppression of Fiber Coloring Suppression of fiber coloring was evaluated by the following procedure. The evaluation was carried out using a fiber bundle immediately after treatment with the above-mentioned <Treatment Method>. (Procedure 1) The color of the fiber near the root, midpoint, and tip on both the front and back of the fiber bundle was measured using a spectrophotometer (color difference meter CR-400, manufactured by Konica Minolta), and the average value of a total of six points was taken as the color measurement value (L, a, b). (Procedure 2) The degree of coloring was evaluated by ΔE using white untreated fiber (Comparative Example 1) as the standard. *abThe color was also measured on the same day that the treatment was carried out.

[0191] ΔE *ab is the value of (L1-L0) where the measured values ​​of the white untreated fiber (Comparative Example 1) are (L0, a0, b0) and the measured values ​​of the treated fiber bundle are (L1, a1, b1). 2 + (a1-a0) 2 +(b1-b0) 2 〕 1 / 2 The coloring suppression effect was evaluated according to the following criteria.

[0192] (Evaluation criteria) 5: ΔE *ab ≦5.0 4:5.0<ΔE *ab ≦10.0 3:10.0<ΔE *ab ≦15.0 2:15.0<ΔE *ab ≦20.0 1:20.0<ΔE *ab

[0193] The modified regenerated collagen fibers treated with the composition of Example 19 were embedded in resin and then cut, and the exposed surface was subjected to fluorescent imaging measurement (excitation wavelength 400 nm, fluorescence detection wavelength 425 to 475 nm) using a confocal laser microscope (A1RHD25, manufactured by Nikon Corporation). The results are shown in Figure 1.

[0194]

[0195]

[0196] Examples 16 to 19 and Comparative Example 4 Regenerated collagen fibers were treated and evaluated according to the methods described below using the compositions formulated as shown in Table 3. When an additional fiber treatment agent (third agent) containing benzoic acid or a salt thereof was used, after treatment with the second agent, (Procedures 2) to (Procedure 5) were repeated using the third agent, and then (Procedure 7) was carried out.

[0197] <Treatment Method> (1) Treatment Method C Regenerated collagen fiber A or regenerated collagen fiber C was treated according to the following procedure. (Procedure 1) Ten 30 cm long fiber bundles (amount that would weigh 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 for each Example. First, the following (Procedure 2) to (Procedure 5) were performed using the first agent shown in the table. (Procedure 2) Each fiber bundle was immersed in a separate container in an amount of fiber treatment agent or additional fiber treatment agent at the bath ratio shown in the table (the bath ratio was calculated based on the 1.5 g weight after drying in Step 1 above), 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 the temperature shown in the table and left to stand for 5 minutes. The liquid temperature in the container was then raised to the temperature shown in the table, 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 to the temperature shown in the table, and the container was rotated at a rotation speed of 80 rpm, followed by heating and stirring for the time shown in the table. (Procedure 5) The container containing the fiber bundle was removed from the dryer and returned to room temperature. The fiber bundle was then removed from the container and rinsed with running tap water at 30°C for 30 seconds, and the hair flow was adjusted with a comb. (Procedure 6) Using the second agent shown in the table, (Procedure 2) to (Procedure 5) were repeated. (Procedure 7) The fiber bundles were hung one by one in a dryer set to the temperature shown in the table, and a 250 g weight was attached to the bottom end of each fiber bundle. The fiber bundles were dried for the time shown in the table with tension applied to the entire fiber. (Procedure 8) The fiber bundles were removed from the dryer, returned to room temperature, and the weight was removed.

[0198] <Evaluation> Evaluation was carried out in accordance with the above-mentioned "1. Weight gain", "2. Water resistance" (1) to (3), "3. Thermal shape memory ability", "4. Fiber swelling ratio in water", "5. Good surface feel", "6. Heat resistance", and "7. Suppression of fiber coloration".

[0199]

Claims

1. A method for treating regenerated collagen fibers, comprising the following step (i): Step (i) is a step of immersing regenerated collagen fibers having a fiber swelling ratio in water of 200% or more, calculated by the following formula (1), in a fiber treatment agent containing component (A): (A) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 1500 to 15000: Fiber swelling ratio in water (%) = [(w1 - w2) / w2] x 100 (1) (wherein w1 represents the mass (g) of the fiber measured after placing 1.0 g of fiber in a container filled with 100 g of ion-exchanged water, sealing the container, immersing the container together in a water bath at 40°C for 30 minutes, removing the fiber from the container, and centrifuging and dehydrating it for 1 minute at a centrifugal force of 220 [x g]. w2 indicates the mass of the fiber measured after the mass (w1) was measured and the fiber was placed on a filter paper and dried at 105° C. for 3 hours.

2. The method for treating regenerated collagen fibers according to claim 1, wherein the regenerated collagen fibers contain the following component (B): (B) a polyvalent metal, or a salt or complex thereof.

3. The method for treating regenerated collagen fibers according to claim 2, wherein component (B) is aluminum, or a salt or complex thereof.

4. A method for processing regenerated collagen fibers according to any one of claims 1 to 3, which includes a regenerated collagen fiber production step, prior to step (i), of discharging an aqueous collagen solution obtained by solubilizing insoluble collagen fibers made from the floor hide of livestock animals through a spinning nozzle or a slit, and immersing the aqueous solution in an aqueous inorganic salt solution.

5. Modified regenerated collagen fiber containing component (A) in the regenerated collagen fiber. (A) is a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group or a salt thereof 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 to 15,000.

6. The modified regenerated collagen fiber according to claim 5, wherein the content of component (A) is 0.1 to 70 mass%.

7. The modified regenerated collagen fiber according to claim 5 or 6, further comprising the following component (B): (B) a polyvalent metal, or a salt or complex thereof.

8. The modified regenerated collagen fiber according to claim 7, wherein component (B) is aluminum, or a salt or complex thereof.

9. A method for producing modified regenerated collagen fibers, comprising a step of treating regenerated collagen fibers with the regenerated collagen fiber treatment method according to any one of claims 1 to 4.

10. A method for producing a head accessory product, comprising a step of treating regenerated collagen fibers with the regenerated collagen fiber treatment method according to any one of claims 1 to 4.

11. A head accessory product comprising the modified regenerated collagen fiber according to any one of claims 5 to 8 as a component.

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