Regenerated collagen fiber treatment method, modified regenerated collagen fiber and headwear product with modified regenerated collagen fiber

Abstract

A method for treating regenerated collagen fibers, which comprises the following step (i). Step (i): a step for impregnating regenerated collagen fibers having a fiber swelling ratio in water of 200% or more as calculated by formula (1) in a fiber treatment agent containing component (A): (A) a copolymer containing 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; the copolymer has an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1500-15000. In the formula, w1 represents the mass (g) of the fiber measured by putting 1.0 g of the fiber into a container filled with 100 g of ion-exchanged water, sealing the container, immersing the container in a water bath at 40 DEG C for 30 minutes, taking out the fiber from the container, and centrifugally dewatering for 1 minute at a centrifugal force of 220 [* g], and w2 represents the mass (g) of the fiber measured by putting the fiber with the mass (w1) measured on a filter paper, and measuring the mass of the fiber after drying at 105 DEG C for 3 hours).

Description

Technical Field

[0001] This invention relates to a method for processing regenerated collagen fibers, particularly a method for processing regenerated collagen fibers used in fiber products such as wigs and hair extensions. Background Technology

[0002] Regenerated collagen fibers typically differ from synthetic fibers, possessing a natural feel and appearance derived from natural materials. They are manufactured by dissolving acid-soluble or insoluble collagen with alkali or enzymes to create a spinning solution, which is then extruded from a spinning nozzle into a coagulation bath for fiberization. Finally, the fibrous collagen is dried in a final process.

[0003] However, compared to synthetic fibers, regenerated collagen fibers are generally more hydrophilic, resulting in higher water absorption and extremely low mechanical strength when containing a large amount of water. Therefore, during washing, the mechanical strength decreases significantly due to the high water absorption, leading to breakage during subsequent drying and reducing their suitability for use in hair accessories and other fiber products. Furthermore, regenerated collagen fibers also suffer from low heat resistance. For example, when using heat setting tools at the same high temperature as human hair, they shrink or curl, compromising their appearance. In addition, while synthetic fibers made of plastic retain their shape after washing (possessing thermal shape memory), regenerated collagen fibers lose their shape after a single wash (lacking thermal shape memory). Therefore, compared to existing synthetic fibers made of plastic, regenerated collagen fibers are less versatile in terms of styling freedom.

[0004] Therefore, various studies have been conducted to address the aforementioned technical problems of naturally derived fibers such as regenerated collagen fibers. For example, it has been reported that cross-linking the wool with acrylic resin in fabrics containing at least 10% by weight of wool can suppress wear (pilling) caused by friction during washing (Patent Document 1). It has also been reported that treating regenerated collagen fibers with a fiber treatment agent containing specific hydroxymethyl compounds and specific phenolic compounds can solve the aforementioned technical problems of water resistance, heat resistance, and thermal shape memory capabilities unique to regenerated collagen fibers (Patent Document 2).

[0005] (Patent Document 1) Japanese Patent Application Publication No. 1-260062

[0006] (Patent Document 2) Japanese Patent Application Publication No. 2022-103113 Summary of the Invention

[0007] The present invention provides the following [1] to

[11] .

[0008] [1] A method for processing regenerated collagen fibers, wherein the method for processing regenerated collagen fibers includes the following steps (i).

[0009] Process (i): A process of impregnating regenerated collagen fibers with a water swelling rate of 200% or more calculated according to the following formula (1) into a fiber treatment agent containing the following component (A).

[0010] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0011] Fiber swelling rate in water (%) = [(w1-w2) / w2]×100 (1)

[0012] In the formula,

[0013] w1 represents the mass (g) of fiber obtained by placing 1.0g of fiber into a container filled with 100g of ion-exchanged water, sealing the container, immersing the fiber together in a 40°C water bath for 30 minutes, removing the fiber from the container, centrifuging it at 220 [×g] for 1 minute to remove water.

[0014] w2 represents the mass of the fiber after it has been measured (w1) is placed on filter paper and dried at 105°C for 3 hours.

[0015] [2] The regenerated collagen fiber processing method as described in [1] above, wherein the regenerated collagen fiber contains the following component (B).

[0016] (B) A polyvalent metal, or its salt or complex.

[0017] [3] The method for processing regenerated collagen fibers as described in [2] above, wherein component (B) is aluminum, or its salt or complex.

[0018] [4] The method for processing regenerated collagen fibers as described in any one of [1] to [3] above, wherein, prior to step (i), the method includes a regenerated collagen fiber manufacturing step in which insoluble collagen fibers made from the hides of livestock are solubilized, the resulting collagen aqueous solution is sprayed out through a spinning nozzle or slit, and then immersed in an inorganic salt aqueous solution.

[0019] [5] A modified regenerated collagen fiber, wherein the modified regenerated collagen fiber is formed by containing the following component (A) in the regenerated collagen fiber.

[0020] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0021] [6] The modified regenerated collagen fiber as described in [5] above, wherein the content of component (A) is 0.1 to 70% by mass.

[0022] [7] The modified regenerated collagen fiber as described in [5] or [6] above, further comprising the following component (B).

[0023] (B) A polyvalent metal, or its salt or complex.

[0024] [8] The modified regenerated collagen fiber as described in [7] above, wherein component (B) is aluminum, or its salt or complex.

[0025] [9] A method for manufacturing modified regenerated collagen fiber, comprising a step of treating the regenerated collagen fiber by any one of the regenerated collagen fiber treatment methods described in any one of [1] to [4] above.

[0026]

[10] A method for manufacturing a headdress product, comprising a step of treating regenerated collagen fibers by any one of the regenerated collagen fiber treatment methods described in any one of [1] to [4] above.

[0027]

[11] A headdress article, wherein the modified regenerated collagen fiber described in any one of [5] to [8] above is a constituent element. Attached Figure Description

[0028] Figure 1 This is a fluorescence imaging image of the cross-section of the modified regenerated collagen fiber obtained in Example 19. Detailed Implementation

[0029] While Patent Document 1 proposes a technique for modifying fibers using high molecular weight compounds, it merely involves cross-linking the polymer with wool to achieve surface coverage. That is, prior to this application, there was a technical problem that polymers could not penetrate into naturally derived fibers such as regenerated collagen fibers. On the other hand, Patent Document 2 describes a technique for modifying fibers using polymers by impregnating regenerated collagen fibers with hydroxymethyl and phenolic compounds, coordinating phenolic hydroxyl groups within the fiber, and using hydroxymethyl compounds to condense the phenolic compounds together. This technique utilizes polymerized condensates to modify the fibers from within. However, when using this technique to modify fibers from within, the steps of monomer impregnation and polymerization within the fiber are essential, making the process cumbersome and limiting its effectiveness in processing large quantities of regenerated collagen fibers.

[0030] Therefore, the present invention relates to a method for treating regenerated collagen fibers that enables polymer compounds to permeate into the fibers, and to modified regenerated collagen fibers.

[0031] In view of the above-mentioned technical problems, the inventors of the present invention have conducted in-depth research and found that: polymeric compounds containing specific characteristic groups can specifically penetrate regenerated collagen fibers with specific properties, and the specific characteristic groups coordinate with the fibers, thus solving the above-mentioned technical problems unique to regenerated collagen fibers, thereby completing the present invention.

[0032] According to the processing method of the present invention, not only can a high molecular weight compound with a specific molecular weight range be impregnated into the regenerated collagen fiber through a simple process, but it can also be retained within the fiber. The modified regenerated collagen fiber of the present invention has excellent water resistance and thermal shape memory properties, and is useful in headwear products such as wigs and hair extensions.

[0033] [Regenerated Collagen Fiber Processing Method]

[0034] The regenerated collagen fiber processing method of the present invention includes the following step (i). This promotes the penetration and coordination of component (A) into the regenerated collagen fiber, and improves the water resistance and thermal shape memory properties, which are technical problems inherent in regenerated collagen fibers.

[0035] Process (i): A process of impregnating regenerated collagen fibers with a water swelling rate of 200% or more calculated according to the following formula (1) into a fiber treatment agent containing the following component (A).

[0036] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0037] Fiber swelling rate in water (%) = [(w1-w2) / w2]×100 (1)

[0038] In the formula,

[0039] w1 represents the mass (g) of fiber obtained by placing 1.0g of fiber into a container filled with 100g of ion-exchanged water, sealing the container, immersing the fiber together in a 40°C water bath for 30 minutes, removing the fiber from the container, centrifuging it at 220 [×g] for 1 minute to remove water.

[0040] w2 represents the mass of the fiber after it has been measured (w1) is placed on filter paper and dried at 105°C for 3 hours.

[0041] In this specification, the “centrifugal force [×g]” in the above formula (1) is a value calculated according to the following formula.

[0042] Centrifugal force [×g] = 1.118 × centrifugal radius (m) × [rotation speed (min)] -1 )] 2 ×10 -3

[0043] <Regenerated Collagen Fiber>

[0044] The regenerated collagen fibers used in this invention must meet the requirement that the fiber swelling rate in water calculated according to the above formula (1) is more than 200%.

[0045] Even when treated with fiber treatment agents containing polymers, commercially available and readily available regenerated collagen fibers only coat the fiber surface and cannot penetrate into the fiber interior. This technical problem has long been recognized by those skilled in the art but remained unsolved prior to this application. Therefore, the inventors of this invention focused on the maximum swelling rate of regenerated collagen fibers in water and explored regenerated collagen fibers capable of penetrating into the fiber interior. They discovered that if a regenerated collagen fiber has a specific property such as a fiber swelling rate of 200% or more in water calculated according to the above formula (1), even high molecular weight compounds can penetrate into the fiber interior. Furthermore, it was found that by setting the molecular weight of the polymer compound to 1500 to 15000 and including structural units derived from unsaturated monomers having carboxyl groups or their salts, and structural units derived from aromatic vinyl compounds, the compound can be retained in the fiber after impregnation, and the aforementioned technical problem unique to regenerated collagen fibers can be solved.

[0046] The regenerated collagen fibers used in this invention have a water swelling rate of 200% or more, and from the viewpoint of promoting fiber penetration, this is preferably 250% or more, more preferably 300% or more, and even more preferably 350% or more. Furthermore, from the viewpoint of avoiding fiber breakage during the fiber processing step due to excessive swelling (from the viewpoint of the operability of the fiber processing step), this 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 water swelling rate of the regenerated collagen fibers is preferably 250–1000%, more preferably 300–800%, even more preferably 350–600%, and even more preferably 350–500%.

[0047] Regenerated collagen fibers only need to have a fiber swelling rate within the above-mentioned range in water; they do not need to be 100% collagen and may contain natural or synthetic polymers or additives for quality improvement. They can also be fibers obtained by further processing regenerated collagen fibers. As for the form of regenerated collagen fibers, filaments are preferred. Filaments are usually taken out in spools or boxes.

[0048] Preferred regenerated collagen fibers are artificially manufactured fibers made from polymers or oligomers derived from collagen, i.e., regenerated collagen fibers made from collagen, and are regenerated collagen fibers with a fiber swelling rate in water within the aforementioned range.

[0049] Regenerated collagen fibers are typically manufactured by preparing a spinning solution from a solubilized collagen raw material, then extruding it from a spinning nozzle into a coagulation bath for fiberization, followed by drying the fibrous collagen in a final process. However, the undried regenerated collagen fibers before the drying process meet the aforementioned requirement of fiber swelling rate in water. Such undried regenerated collagen fibers can be manufactured using existing known methods before the drying process. For example, an example is the undried regenerated collagen fibers recovered without drying after solubilizing insoluble collagen fibers made from animal hides, extruding the resulting collagen aqueous solution through a spinning nozzle or slit, immersing it in an inorganic salt aqueous solution, and then retrieving it. Specific details are provided below.

[0050] As a raw material for collagen, the hide portion is preferred. The hide can be obtained, for example, from fresh hides or salted raw hides obtained from slaughtering livestock such as cattle. These hides are mostly composed of insoluble collagen fibers and are usually used after the reticular attached meat parts and the salt used to prevent spoilage have been removed.

[0051] The insoluble collagen fibers contain impurities such as lipids (glycerides, phospholipids, free fatty acids, etc.) and proteins (glycoproteins, albumin, etc.) other than collagen. These impurities significantly affect the spinning stability, luster, tensile strength, and other qualities, as well as odor, during fiberization. Therefore, it is preferable to pre-treat these impurities by hydrolyzing the fatty components in the insoluble collagen fibers, such as by lime impregnation, to loosen the collagen fibers, followed by conventional leather treatments in the prior art, such as acid-alkali treatment, enzyme treatment, and solvent treatment.

[0052] For insoluble collagen that has undergone this treatment, a solubilization process is performed to cleave the cross-linked peptides. Commonly known methods for this solubilization include alkali dissolution and enzymatic dissolution, or a combination of both.

[0053] When using the alkaline dissolution method, neutralization is preferably performed using an acid such as hydrochloric acid. Alternatively, as an improvement to the alkaline dissolution method known in the prior art, the method described in, for example, Japanese Patent Publication No. 46-15033 can be employed.

[0054] Enzymatic dissolution has the advantage of obtaining solubilized collagen with uniform molecular weight, and is the preferred method adopted in this invention. Such enzymatic dissolution methods can be those described in, for example, Japanese Patent Publication Nos. 43-25829 and 43-27513.

[0055] By further performing pH adjustment, salting out, washing, and solvent treatment on collagen that has undergone such solubilization treatment, high-quality regenerated collagen fibers can be obtained, and therefore these treatments are preferred.

[0056] Soluble collagen is dissolved using acids such as hydrochloric acid, acetic acid, or lactic acid, and adjusted to an aqueous collagen solution with a pH of 2–4.5 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 can be degassed under reduced pressure or filtered to remove fine impurities that are water-insoluble components, as needed. Furthermore, appropriate amounts of stabilizers, water-soluble polymers, and other additives can be added to the collagen aqueous solution as needed, for example, to improve mechanical strength, water and heat resistance, gloss, spinnability, prevent coloring, and prevent corrosion.

[0057] Collagen aqueous solution is sprayed through, for example, a spinning nozzle or slit, and then immersed in an inorganic salt aqueous solution, thereby obtaining undried regenerated collagen fibers. As the inorganic salt aqueous solution, aqueous solutions of water-soluble inorganic salts such as sodium sulfate, sodium chloride, and ammonium sulfate can be used. Typically, the concentration of inorganic salts in these aqueous solutions is adjusted to 10-40% by mass. The pH of the inorganic salt aqueous solution is preferably 2 or higher, more preferably 4 or higher, and preferably 13 or lower, more preferably 12 or lower. This pH adjustment can be achieved using metal salts such as sodium borate and sodium acetate, or hydrochloric acid, boric acid, acetic acid, and sodium hydroxide. When the pH of the inorganic salt aqueous solution is within the above range, the peptide bonds of collagen are less likely to hydrolyze, making it easier to obtain the target fibers. Furthermore, the temperature of the inorganic salt aqueous solution is not particularly limited, but from the viewpoint of preventing denaturation of soluble collagen, maintaining the strength of the fibers after spinning, and easily producing stable yarns, a temperature of 35°C or lower is generally preferred. Moreover, the lower limit of the temperature of the inorganic salt aqueous solution is not particularly limited, and is usually adjusted appropriately according to the solubility of the inorganic salts.

[0058] Undried regenerated collagen fibers can be pretreated (crosslinked) by impregnating them with an epoxy compound monomer or a solution thereof. The amount of epoxy compound monomer is preferably 0.1 equivalents or more, more preferably 0.5 equivalents or more, further preferably 1 equivalent or more, and preferably 500 equivalents or less, more preferably 100 equivalents or less, and further preferably 50 equivalents or less, with the amount of epoxy compound monomer within the regenerated collagen fibers being within the above range. By keeping the amount of epoxy compound monomer within the above range, the regenerated collagen fibers can be sufficiently imparted with a water-insoluble effect, which is also preferred in terms of industrial operability and the environment.

[0059] Epoxy monomers can be used directly or dissolved in various solvents. Examples of solvents include: water; alcohols such as methanol, ethanol, 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 can be used alone or in combination. When using water as a solvent, aqueous solutions of inorganic salts such as sodium sulfate, sodium chloride, and ammonium sulfate can be used as needed. Typically, the concentration of inorganic salts in the aqueous solution is adjusted to 10–40% by mass. Furthermore, the pH of the aqueous solution can be adjusted using metal salts such as sodium borate and sodium acetate, or hydrochloric acid, boric acid, acetic acid, and sodium hydroxide. In this case, from the viewpoint that the reaction between the epoxy groups of the epoxy monomers and the amino groups of collagen is not slowed down and that water insolubility is sufficient, the pH of the aqueous solution is preferably 6 or higher, and more preferably 8 or higher. In addition, since the pH of aqueous solutions of inorganic salts tends to decrease over time, buffers can be used as needed.

[0060] Regarding the processing temperature of undried regenerated collagen fibers using epoxy compound monomers, from the viewpoint that the regenerated collagen fibers do not degrade, the strength of the obtained fibers does not decrease, and it is easy to manufacture stable filaments, it is preferably below 50°C.

[0061] The regenerated collagen fibers used in this invention preferably contain a polyvalent metal, or its salt or complex, from the viewpoint of improving water resistance. Examples include one or more polyvalent metals, or their salts or complexes, selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoints of improving water resistance, reducing fiber discoloration, minimizing environmental impact, and improving economic efficiency, the use of one or more polyvalent metals, or their salts or complexes, selected from aluminum, zirconium, and titanium is preferred; aluminum, or its salts or complexes, is more preferred. Regarding the content of polyvalent metals, or their salts or complexes, in regenerated collagen fibers, from the viewpoint of improving water resistance, it is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, further preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, in terms of elemental mass. Furthermore, from the viewpoint of improving the surface feel of the fibers, it is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and even more preferably 10% by mass or less. That is, from the above viewpoint, the content of polyvalent metals, or their salts or complexes, in regenerated collagen fibers, in terms of elemental mass, is preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, further preferably 3.0 to 20% by mass, and even more preferably 5.0 to 10% by mass. In this specification, the "amount of metal elements" can be quantified using ICP emission spectroscopy analysis. For example, an iCAP6500Duo (manufactured by Thermo Fisher Scientific Inc.) can be used as the ICP emission analysis device during ICP emission spectroscopy analysis. Furthermore, the measurement conditions for ICP emission spectroscopy analysis are as follows: the optimal analytical wavelength for the target metal can be determined by confirming the spectral pattern. For example, for aluminum, it is 396.152 nm. Additionally, the analytical sample can be pretreated according to the methods described in the examples, and calibration curves can be prepared for each target metal.

[0062] <Measurement Conditions>

[0063] •RF power: 1150W

[0064] • Cooling gas flow rate: 12L / min

[0065] • Atomizer flow rate: 0.70L / min

[0066] • Assist gas: 0.5 L / min

[0067] • Pump flow rate: 50 rpm

[0068] Furthermore, the undried regenerated collagen fibers are in a state of swelling with water or an aqueous solution of inorganic salts. This swelling can be in a state where the water or inorganic salt solution contains 4 to 15 times its mass relative to the regenerated collagen fibers. When the water or inorganic salt solution content is less than 4 times, the aluminum salt content in the regenerated collagen fibers is low, and there is a tendency for insufficient water resistance; while when it exceeds 15 times, the fiber strength deteriorates, and there is a tendency for handling to become difficult. Therefore, metals can be included in such a manner that the amount of metal element is within the above-mentioned range. For example, the following treatment can be performed.

[0069] First, the undried regenerated collagen fibers are impregnated in an aqueous solution of an aluminum salt. The preferred aluminum salts are basic aluminum chloride or basic aluminum sulfate, as shown in the following formula.

[0070] Al(OH) n Cl 3-n Or Al2(OH) 2n (SO4) 3-n

[0071] [In the formula, n is 0.5 to 2.5.]

[0072] Specific examples include aluminum sulfate, aluminum chloride, and alum. Aluminum salts can be used alone or in combination of two or more.

[0073] The aluminum salt concentration in the aluminum salt aqueous solution, converted to alumina, is preferably 0.3 to 5% by mass. When the aluminum salt concentration is below 0.3% by mass, the aluminum salt content in the regenerated collagen fiber is low, and there is a tendency for insufficient water resistance; while when it exceeds 5% by mass, the treated fiber becomes hard, and there is a tendency for it to affect the feel.

[0074] The pH of aluminum salt aqueous solutions is typically 2.5–5. It can be adjusted using, for example, hydrochloric acid, sulfuric acid, acetic acid, sodium hydroxide, sodium carbonate, etc. Below 2.5, there is a tendency to damage the structure of collagen and cause denaturation; while above 5, aluminum salt precipitation occurs, making it difficult to penetrate the fibers. For pH, it is preferable to initially adjust to 2.2–3.5 to allow the aluminum salt aqueous solution to fully penetrate the regenerated collagen fibers, and then add, for example, sodium hydroxide or sodium carbonate, to adjust to 3.5–5 to complete the treatment. When using highly alkaline aluminum salts, an initial pH adjustment to 2.5–5 may also be performed.

[0075] Furthermore, the temperature of the aluminum salt aqueous solution is not particularly limited, but is preferably below 50°C. When the temperature exceeds 50°C, there is a tendency for modification of regenerated collagen fibers.

[0076] The immersion time of undried regenerated collagen fibers in an aqueous aluminum salt solution is typically 3 hours or more, preferably 6 to 25 hours. When the immersion time is less than 3 hours, the reaction of the aluminum salt is difficult to proceed, and there is a tendency for the water resistance of the regenerated collagen fibers to become insufficient. Furthermore, there is no particular upper limit to the immersion time; the reaction of the aluminum salt can proceed sufficiently within 25 hours, and the water resistance becomes good.

[0077] In addition, to prevent uneven concentration of aluminum salts from being rapidly absorbed in regenerated collagen fibers, inorganic salts such as sodium chloride, sodium sulfate, and potassium chloride can be appropriately added to the aluminum salt aqueous solution.

[0078] After treating regenerated collagen fibers with epoxy monomers or aluminum salts, they can be washed with water. Washing can be performed, for example, by rinsing with running water for 10 minutes to 4 hours. <Fiber Treatment Agent>

[0079] The fiber treatment agent contains a specific copolymer as component (A), which comprises structural units derived from unsaturated monomers having carboxyl groups or their salts, and structural units derived from aromatic vinyl compounds.

[0080] The bonding state of each structural unit can be block bonding, random bonding, or a combination thereof. In addition, component (A) can be used alone or in combination of two or more.

[0081] Examples of unsaturated monomers having a carboxyl group or its salt include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, or their salts. 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, zeaxanthinic acid, itaconic acid, and methylene succinic acid. Alternatively, unsaturated dicarboxylic acids can also be obtained by using unsaturated dicarboxylic anhydrides, which are then hydrolyzed using alkalis or similar methods to produce an acidic form. Examples of unsaturated dicarboxylic anhydrides include maleic anhydride and citraconic anhydride. Unsaturated monomers having a carboxyl group or its salt can be used alone or in combination of two or more.

[0082] 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; examples of alkaline earth metal salts include calcium salts and magnesium salts. From a dispersive perspective, sodium salts are preferred.

[0083] In addition, the carboxyl group or its salt can also dissociate into a carboxyl anion.

[0084] Furthermore, as aromatic vinyl compounds, there are no particular limitations as long as they are aromatic compounds that at least substituted with vinyl groups. Examples include styrene, α-methylstyrene, p-methylstyrene, 3-vinyltoluene, dimethylstyrene, ethylvinylbenzene, chloromethylstyrene, vinylnaphthalene, and vinylanthracene. Aromatic vinyl compounds can be used alone or in combination of two or more.

[0085] The copolymer of component (A) may also contain structural units other than those described above.

[0086] Other structural units may be derived from, for example, unsaturated aliphatic hydrocarbon compounds, but are not limited to this. There may be one or more such other structural units.

[0087] Unsaturated aliphatic hydrocarbon compounds can be chain-like, branched, or cyclic.

[0088] Examples of unsaturated aliphatic hydrocarbon compounds that are either chain-like or branched include propylene, isobutylene, diisobutylene, triisobutylene, tripropylene, and tetrapropylene.

[0089] Examples of cyclic unsaturated aliphatic hydrocarbon compounds include cyclopentene, cyclohexene, and cyclooctene.

[0090] As a preferred embodiment of component (A), copolymers comprising, for example, one or more structural units derived from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and their salts, and structural units derived from aromatic vinyl compounds may be listed. Specifically, from the viewpoint of promoting penetration and coordination into fibers, and improving water resistance, heat resistance, and thermal shape memory, one or more of styrene-maleic acid copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, vinylbenzoic acid-maleic acid copolymers, vinylbenzoic acid-acrylic acid copolymers, vinylbenzoic acid-methacrylic acid copolymers, styrene-4-vinylbenzoic acid copolymers, and their salts are preferred, with styrene-maleic acid copolymers or their salts being more preferred. When the copolymer of component (A) is in the form of a salt, the equilibrium ion of the salt is not particularly limited, and examples include sodium salts, potassium salts, magnesium salts, calcium salts, ammonium salts, etc., with sodium salts being preferred.

[0091] Among them, styrene-maleic acid copolymer can also be used as styrene-maleic anhydride copolymer, or styrene-maleic acid copolymer can be generated by using alkali, etc.

[0092] In the copolymer of component (A), from the viewpoint of promoting penetration and coordination into the fiber, and improving water resistance, heat resistance and thermal shape memory, the ratio of structural units (u1) derived from unsaturated monomers having carboxyl groups or their salts to structural units (u2) derived from aromatic vinyl compound monomers is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1 in molar ratio (u1 / u2).

[0093] The acid value of component (A) is 100 mg KOH / g or higher. From the viewpoint of promoting penetration and coordination into the fiber, and improving water resistance, heat resistance, and thermal shape memory, it is preferably 200 mg KOH / g or higher, more preferably 300 mg KOH / g or higher, even more preferably 400 mg KOH / g or higher, and preferably 1000 mg KOH / g or lower, more preferably 800 mg KOH / g or lower, even more preferably 600 mg KOH / g or lower. That is, the acid value is preferably 200 to 1000 mg KOH / g, more preferably 300 to 800 mg KOH / g, and even more preferably 400 to 600 mg KOH / g. Here, in this specification, "acid value" refers to the number of milligrams (mg) of potassium hydroxide required to neutralize the acidic component contained in 1 g of sample, which can be determined by potentiometric titration according to JIS K 0070. When component (A) is a salt, the acid value of the free acid (non-dissociated acid) is used.

[0094] Specific examples of components (A) with acid values ​​within the above range can be listed below, such as the following compounds.

[0095] • Styrene-maleic acid copolymer

[0096] (Styrene / maleic acid (molar ratio) = 1 / 1) 475 mg KOH / g

[0097] • Styrene-maleic acid copolymer

[0098] (Styrene / maleic acid (molar ratio) = 2 / 1) 355mgKOH / g

[0099] • Styrene-maleic acid copolymer

[0100] (Styrene / maleic acid (molar ratio) = 3 / 1) 285 mg KOH / g

[0101] The weight-average molecular weight of component (A) is 1500 to 15000. From the viewpoint of promoting penetration and coordination into fibers, and improving water resistance, heat resistance, and thermal shape memory, it is preferably 2000 or more, more preferably 3000 or more, further preferably 4000 or more, and preferably 12000 or less, more preferably 10000 or less, further preferably 8000 or less, and even more preferably 7000 or less. That is, the weight-average molecular weight is preferably 2000 to 12000, more preferably 3000 to 12000. Furthermore, it is preferably 1500 to 10000, more preferably 2000 to 8000, further preferably 3000 to 8000, and even more preferably 4000 to 7000. Here, in this specification, "weight-average molecular weight" refers to the weight-average molecular weight converted from polystyrene as measured by gel permeation chromatography (GPC), which can be specifically determined by the method described in the examples.

[0102] Regarding the content of component (A) in the fiber treatment agent, from the viewpoint of promoting penetration and coordination into the fiber, and improving water resistance, heat resistance, and thermoshape memory, it 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; and from the viewpoint of improving the surface feel of the fiber, 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 a value converted to free acid.

[0103] Regarding the pH of the fiber treatment agent, from the viewpoint of promoting penetration and coordination into the fibers, and improving water resistance, heat resistance, and thermoforming properties, it is preferably 2.0 or higher, more preferably 3.0 or higher, further preferably 3.5 or higher, and preferably 11.0 or lower, more preferably 10.0 or lower, further 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, further 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, which can be measured using a pH meter.

[0104] In addition, the content of component (A) in the fiber treatment agent used in this process can be set to the range shown below, depending on the pH range of the fiber treatment agent.

[0105] When the pH of the fiber treatment agent is less than 5.5, from the viewpoint of promoting penetration and coordination into the fibers, and improving water resistance, heat resistance, and thermoshape memory, 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, further preferably 1.3% by mass or more, and even more preferably 2.3% by mass or more; and from the viewpoint of improving the surface feel of the fibers, 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, further preferably 1.3 to 10% by mass, and even more preferably 2.3 to 10% by mass.

[0106] Furthermore, when the pH of the fiber treatment agent is 5.5 or higher, from the viewpoint of promoting penetration and coordination into the fibers, and improving water resistance, heat resistance, and thermoshape memory, 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. Moreover, from the viewpoint of improving the surface feel of the fibers, 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.

[0107] Furthermore, the fiber treatment agent used in this process uses water as a medium. The water content in the fiber treatment agent is the balance excluding component (A) and any other components described later. For example, the water content in the fiber treatment agent is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, further more preferably 40% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, further preferably 96% by mass or less, further more preferably 95% by mass or less, further more preferably 90% by mass or less, and further 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, further preferably 30 to 96% by mass, further more preferably 40 to 95% by mass, further more preferably 40 to 90% by mass, and further more preferably 40 to 85% by mass.

[0108] <Immersion>

[0109] As an impregnation method, existing and well-known methods can be used. For example, a method of immersing regenerated collagen fibers in a liquid tank filled with a fiber treatment agent, thereby bringing the fibers into contact with the fiber treatment agent.

[0110] Impregnation treatment can be performed more than twice. In this case, the same fiber treatment agent can be used, or different types of fiber treatment agents can be used.

[0111] When using different types of fiber treatment agents, for example, fiber treatment agents with different pH values ​​can be used. Specifically, examples include: a two-step treatment method, which includes treating with a first fiber treatment agent containing component (A) (hereinafter also referred to as "Agent 1"), followed by treating with a second fiber treatment agent containing component (A) (hereinafter also referred to as "Agent 2"), wherein the pH of the second fiber treatment agent is adjusted to be at least 1.0 lower than that of the first fiber treatment agent; and a multi-step treatment method, which includes repeating the treatment with Agent 1 two to three times or more, and finally treating with Agent 2. After the above two-step treatment, a further treatment step can be performed using an additional fiber treatment agent (hereinafter also referred to as "Agent 3") containing benzoic acid or its salt as component (C). Examples also include treatment methods that include the treatment with Agent 1 and the treatment with Agent 3. Alkali metal salts, specifically sodium and potassium salts, can be used as salts of benzoic acid. Furthermore, the amount of each agent used can be appropriately selected within a range that does not impair the effects of the present invention.

[0112] In the additional fiber treatment agent (third agent) containing (C) benzoic acid or its salt, from the viewpoint of improving the water resistance and heat resistance of the fiber, the content of (C) benzoic acid or its salt in the additional fiber treatment agent (third agent) is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 5% by mass or more, even more preferably 10% by mass or more, even 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, even more preferably 40% by mass or less, and even more preferably 35% by mass or less. That is, the content of (C) benzoic acid or its salt 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, even more preferably 10 to 40% by mass, and even more preferably 20 to 35% by mass. Furthermore, in this specification, when benzoic acid is a salt, its content is a value converted to benzoic acid (free acid).

[0113] Regarding the amount of fiber treatment agent used to impregnate regenerated collagen fibers, the bath ratio (mass of fiber treatment agent / mass of regenerated collagen fibers) relative to the mass of regenerated collagen fibers is preferably 2 or more, more preferably 3 or more, further preferably 5 or more, further more preferably 10 or more, further more preferably 20 or more, and preferably 500 or less, more preferably 250 or less, further preferably 100 or less, and further more preferably 50 or less. That is, the above-mentioned bath ratio is preferably 2 to 500, more preferably 3 to 250, further preferably 5 to 100, further more preferably 10 to 100, further more preferably 20 to 100, and further more preferably 20 to 50.

[0114] The impregnation of regenerated collagen fibers in the fiber treatment agent in this process can be carried out at room temperature (20℃±15℃), but heating is also acceptable. This heating can be achieved by raising the temperature of the fiber treatment agent. This heating can be done by impregnating the regenerated collagen fibers in a heated fiber treatment agent, or by impregnating the regenerated collagen fibers in a low-temperature fiber treatment agent followed by heating. Regarding the temperature of the fiber treatment agent, in order to allow component (A) to penetrate into the regenerated collagen fibers and increase the interaction with the fiber constituent molecules, such as protein molecules, thereby achieving the effects of the present invention, a temperature of 20℃ or higher is preferred, more preferably 25℃ or higher, and even more preferably 30℃ or higher is preferred. Furthermore, to prevent the regenerated collagen fibers from being modified and deteriorated due to heat, a temperature below 100℃ is preferred, more preferably below 80℃, even more preferably below 70℃, even more preferably below 60℃, and even more preferably below 50℃. That is, the above-mentioned temperature is preferably above 20°C and below 100°C, more preferably 25-80°C, even more preferably 30-70°C, even more preferably 30-60°C, and even more preferably 30-50°C.

[0115] The soaking time in this process can be appropriately adjusted according to the heating temperature. For example, from the viewpoint of improving the elasticity of regenerated collagen fibers, it is preferably 15 minutes or more, more preferably 30 minutes or more, further preferably 1 hour or more, even more preferably 3 hours or more, even more preferably 5 hours or more, and even more preferably 10 hours or more. In order to inhibit damage to regenerated collagen fibers, it is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 30 hours or less. That is, the soaking time is preferably 15 minutes or more and 48 hours or less, more preferably 30 minutes or more and 33 hours or less, further preferably 1 hour or more and 30 hours or less, even more preferably 3 hours or more and 30 hours or less, even more preferably 5 hours or more and 30 hours or less, and even more preferably 10 hours or more and 30 hours or less.

[0116] This process is preferably carried out in an environment where moisture evaporation is suppressed. Specific methods for suppressing moisture evaporation include covering a container impregnated with a fiber treatment agent made of a membrane, cap, or lid made of a water vapor-impermeable material.

[0117] After this process, the regenerated collagen fibers may or may not be rinsed, but rinsing is preferred from the viewpoint of preventing a decrease in the tactile feel of the regenerated collagen fiber surface due to residual component (A).

[0118] It can be assumed that through this process, component (A) permeates into the regenerated collagen fiber and strongly coordinates with metals within the fiber, such as polyvalent metals, thereby producing various effects. That is, through the regenerated collagen fiber processing method including step (i), it is possible to produce modified regenerated collagen fibers containing component (A), and the resulting modified regenerated collagen fibers are considered to improve the water resistance and thermal shape memory properties, which are technical problems unique to regenerated collagen fibers.

[0119] [Modified regenerated collagen fiber]

[0120] The modified regenerated collagen fiber of the present invention contains the following component (A).

[0121] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 1500.

[0122] The structural unit derived from an unsaturated monomer having a carboxyl group or a salt thereof can be, for example, a structural unit derived from an unsaturated monocarboxylic acid or a salt thereof, a structural unit derived from an unsaturated dicarboxylic acid or a salt thereof, or a combination thereof. Specific examples of unsaturated monocarboxylic acids or salts thereof, and unsaturated dicarboxylic acids or salts thereof, have been described above. The structural unit derived from an unsaturated monomer having a carboxyl group or a salt thereof may be one or more types.

[0123] As a structural unit derived from aromatic vinyl compounds, it can be derived from any aromatic compound that has at least a substituted vinyl group, without particular limitation. Specific examples of aromatic vinyl compounds are described above. Structural units derived from aromatic vinyl compounds may contain one or more types.

[0124] The bonding state of each structural unit can be block bonding, random bonding, or a combination thereof. Component (A) can contain one or more of these.

[0125] Component (A) may also contain structural units other than the unsaturated monomers described above. There may be one or more of these other structural units.

[0126] Other structural units, such as those derived from unsaturated aliphatic hydrocarbon compounds, can be listed, but are not limited to. They can be chain-like, branched, or cyclic. Specific examples of unsaturated aliphatic hydrocarbon compounds have been described above.

[0127] As a preferred embodiment of component (A), copolymers comprising structural units derived from one or more structural units selected from unsaturated monocarboxylic acids or their salts and unsaturated dicarboxylic acids or their salts, and structural units derived from aromatic vinyl compounds may be listed. Specifically, from the viewpoint of promoting retention and coordination into the fiber, and improving water resistance, heat resistance, and thermal shape memory, styrene-maleic acid copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, vinylbenzoic acid-maleic acid copolymers, vinylbenzoic acid-acrylic acid copolymers, vinylbenzoic acid-methacrylic acid copolymers, styrene-4-vinylbenzoic acid copolymers, or their salts, are preferred, with styrene-maleic acid copolymers or their salts being more preferred. When the copolymer of component (A) is in the form of a salt, the equilibrium ion of the salt is not particularly limited; examples include sodium salts, potassium salts, magnesium salts, calcium salts, ammonium salts, etc., with sodium salts being preferred.

[0128] In component (A), the ratio of structural units (u1) derived from unsaturated monomers having carboxyl groups or their salts to structural units (u2) derived from aromatic vinyl compound monomers 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 viewpoint of promoting retention and coordination in the fiber and improving water resistance, heat resistance and thermal shape memory.

[0129] The acid value of component (A) is 100 mg KOH / g or higher. From the viewpoint of promoting retention and coordination in the fiber, and improving water resistance, heat resistance, and thermal shape memory, it is preferably 200 mg KOH / g or higher, more preferably 300 mg KOH / g or higher, even more preferably 400 mg KOH / g or higher, and preferably 1000 mg KOH / g or lower, more preferably 800 mg KOH / g or lower, even more preferably 600 mg KOH / g or lower. That is, the acid value is preferably 200 to 1000 mg KOH / g, more preferably 300 to 800 mg KOH / g, and even more preferably 400 to 600 mg KOH / g.

[0130] Specific examples of components (A) with acid values ​​within the above range can be listed below, such as the following compounds.

[0131] • Styrene-maleic acid copolymer

[0132] (Styrene / maleic acid (molar ratio) = 1 / 1) 475 mg KOH / g

[0133] • Styrene-maleic acid copolymer

[0134] (Styrene / maleic acid (molar ratio) = 2 / 1) 355mgKOH / g

[0135] • Styrene-maleic acid copolymer

[0136] (Styrene / maleic acid (molar ratio) = 3 / 1) 285 mg KOH / g

[0137] The weight-average molecular weight of component (A) is 1500 to 15000. From the viewpoint of promoting retention and coordination in the fiber, and improving water resistance, heat resistance, and thermomorphic memory, it is preferably 2000 or more, more preferably 3000 or more, further preferably 4000 or more, and preferably 12000 or less, more preferably 10000 or less, further preferably 8000 or less, and even more preferably 7000 or less. That is, the weight-average molecular weight is preferably 2000 to 12000, more preferably 3000 to 12000. Furthermore, it is preferably 1500 to 10000, more preferably 2000 to 8000, further preferably 3000 to 8000, and even more preferably 4000 to 7000.

[0138] Regarding the content of component (A) in the modified regenerated collagen fiber of the present invention, from the viewpoint of exhibiting higher water resistance, heat resistance, and thermal shape memory ability, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1.0% by mass or more, further more preferably 3.0% by mass or more, further preferably 5.0% by mass or more, further preferably 10% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, further preferably 60% by mass or less, further more preferably 55% by mass or less, further more preferably 50% by mass or less, and further 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, further preferably 1.0 to 60% by mass, further more preferably 3.0 to 55% by mass, further more preferably 5.0 to 50% by mass, and further more preferably 10 to 45% by mass.

[0139] In this specification, regarding the quantification of component (A), a suitable method is selected that does not decompose component (A) but can dissolve the regenerated collagen fibers, thereby dissolving and extracting the fibers. Then, after appropriately diluting the extraction solution, the absorbance is measured using, for example, a UV-Vis-NIR spectrophotometer (e.g., V-560 (manufactured by Nippon Spectrophotometer Co., Ltd.)) at an absorbance wavelength suitable for the quantification of component (A), and the content of component (A) is calculated based on this absorbance. Alternatively, HPLC / UV or gel permeation chromatography (GPC) can be used to measure the peak area of ​​a chromatogram plotted at an absorbance wavelength suitable for the quantification of component (A), and the content of component (A) is calculated based on this peak area.

[0140] Furthermore, from the viewpoint of improving water resistance, the modified regenerated collagen fiber of the present invention preferably contains a polyvalent metal, or its salt or complex as component (B). Examples include one or more polyvalent metals, or their salts or complexes, selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoints of improving water resistance, reducing fiber discoloration, minimizing environmental impact, and improving economic efficiency, the use of one or more polyvalent metals, or their salts or complexes, selected from aluminum, zirconium, and titanium is preferred, and aluminum, or its salts or complexes, is more preferred. These can be used individually or in combination of two or more.

[0141] Regarding the content of component (B) in the modified regenerated collagen fiber of the present invention, from the viewpoint of improving water resistance, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more, in terms of metal element content. Furthermore, from the viewpoint of improving the surface feel of the fiber, 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, in terms of metal element content, is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, further preferably 1.0 to 20% by mass, and even more preferably 2.0 to 10% by mass.

[0142] The quantification of component (B) in modified regenerated collagen fibers can be performed as follows: The regenerated collagen fibers are ashed, alkali-melted, and then dissolved in acid to prepare a solution. This solution is then appropriately diluted to prepare a sample for analysis, and the metal element is quantified using an ICP emission spectrometer.

[0143] In the modified regenerated collagen fiber of the present invention, from the viewpoint of promoting retention and coordination in the fiber, and improving water resistance, heat resistance and thermal shape memory, it is preferable to further contain benzoic acid or a salt thereof as component (C). Regarding the content of (C) benzoic acid or a salt thereof in the modified regenerated collagen fiber of the present invention, from the viewpoint of maintaining and coordinating in the fiber, and improving water resistance, heat resistance and thermal shape memory, it is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. That is, the content of (C) benzoic acid or a salt thereof in the modified regenerated collagen fiber of the present invention is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and further preferably 10 to 30% by mass.

[0144] The modified regenerated collagen fiber of the present invention is a fiber whose shape is imparted by heat setting by coordinating the carboxyl groups or salts of component (A) retained within the fiber with the fiber, thereby significantly improving its water resistance. Regarding the distribution of component (A) within the fiber cross-section, the fiber cross-section can be cut using a slicer, scalpel, razor, etc., according to the characteristics of component (A), and then evaluated by line or surface analysis of the cross-section using optical microscopy, fluorescence microscopy, confocal laser microscopy with fluorescence imaging, TOF-SIMS, EPMA, TEM / SEM-EDS, microscopic IR, microscopic laser Raman spectroscopy, etc. More specifically, the evaluation can be performed, for example, by the following methods.

[0145] For the cross-section of modified regenerated collagen fibers, fluorescence imaging was performed using confocal laser microscopy. When a significant difference in fluorescence intensity within the fiber was observed compared to untreated regenerated collagen fibers in the fluorescence imaging image, it was determined that component (A) had penetrated into the fiber. For example, since modified regenerated collagen fibers treated with styrene-maleic acid copolymer or its salt as component (A) have a wavelength characteristic of styrene-maleic acid copolymer at 400 nm, fluorescence imaging can be performed with an excitation wavelength of 400 nm and a detection wavelength of 425–475 nm. For example, the AIRHD25 (manufactured by Nikon Corporation) can be used as the confocal laser microscope.

[0146] [Manufacturing method of modified regenerated collagen fiber]

[0147] The method for manufacturing modified regenerated collagen fibers of the present invention includes a step of treating the regenerated collagen fibers using a regenerated collagen fiber treatment method. The specific steps of treating the regenerated collagen fibers are described in the regenerated collagen fiber treatment method.

[0148] The modified regenerated collagen fiber of the present invention is suitable for use as a fiber in headwear products.

[0149] [Headwear and its manufacturing method]

[0150] The headwear product of the present invention incorporates the modified regenerated collagen fiber of the present invention as a constituent element. The modified regenerated collagen fiber of the present invention can be used alone as a headwear product or blended with other fibers to form a headwear product. As for the other fibers, any fiber that can be used in a headwear product is acceptable and is not particularly limited. Examples of other fibers include polyester fibers, human hair, animal hair, polyvinyl chloride fibers, modified polyacrylonitrile fibers, polyamide fibers, and polyolefin fibers. From the viewpoint of excellent heat resistance, flame retardancy, and crimp retention, polyester fibers are preferred, and flame-retardant polyester fibers are more preferred.

[0151] Flame-retardant polyester fibers are not particularly limited. From a flame-retardant viewpoint, it is preferable that 100 parts by weight of a polyester resin selected from one or more polyester resins chosen from alkylene terephthalate and copolyesters with alkylene terephthalate as the main component contains 5 to 40 parts by weight of a brominated epoxy flame retardant. In this invention, "as the main component" means containing 50 mol% or more, and "copolyester with alkylene terephthalate as the main component" means a copolyester containing 50 mol% or more of alkylene terephthalate. Preferably, the "copolyester with alkylene terephthalate as the main component" contains 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more of alkylene terephthalate. The above-mentioned flame-retardant polyester fibers preferably also contain 0 to 5 parts by weight of an antimony compound relative to 100 parts by weight of the polyester resin. By containing an antimony compound, the flame retardancy of the polyester fibers is improved.

[0152] In this invention, preferred headwear products include, for example, hair wigs, wigs, weaving, hair extensions, braids, hair accessories, doll hair, etc.

[0153] The method for manufacturing headwear products of the present invention includes a step of treating regenerated collagen fibers using the regenerated collagen fiber treatment method described above. This enables the manufacture of various headwear products. The specific method for treating the regenerated collagen fibers is as described in the regenerated collagen fiber treatment method. Furthermore, the method for manufacturing headwear products using modified regenerated collagen fibers can employ existing known methods depending on the type of headwear product, and is not particularly limited.

[0154] Regarding the embodiments described above, preferred embodiments of the present invention are further disclosed below.

[0155] <1> A method for processing regenerated collagen fibers, wherein the method for processing regenerated collagen fibers includes the following steps (i).

[0156] <2> A method for manufacturing modified regenerated collagen fiber, wherein the method for manufacturing modified regenerated collagen fiber includes a step of treating the regenerated collagen fiber by a regenerated collagen fiber treatment method including the following step (i).

[0157] <3> A method for manufacturing a headdress, wherein the method comprises: a step of treating regenerated collagen fibers by a regenerated collagen fiber treatment method including the following step (i).

[0158] Step (i) involves impregnating regenerated collagen fibers with a water swelling rate of 200% or more, calculated according to the following formula (1), into a fiber treatment agent containing the following component (A).

[0159] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0160] Fiber swelling rate in water (%) = [(w1-w2) / w2]×100 (1)

[0161] In the formula,

[0162] w1 represents the mass (g) of fiber obtained by placing 1.0g of fiber into a container filled with 100g of ion-exchanged water, sealing the container, immersing the fiber together in a 40°C water bath for 30 minutes, removing the fiber from the container, centrifuging it at 220 [×g] for 1 minute to remove water.

[0163] w2 represents the mass of the fiber after it has been measured (w1) is placed on filter paper and dried at 105°C for 3 hours.

[0164] <4> The method for processing regenerated collagen fibers as described in <1> above, the method for manufacturing modified regenerated collagen fibers as described in <2> above, or the method for manufacturing headwear products as described in <3> above, wherein the fiber swelling rate in water is preferably 250% or more, more preferably 300% or more, further preferably 350% or more, and preferably 1000% or less, more preferably 800% or less, further preferably 600% or less, and further more preferably 500% or less.

[0165] <5> The method for processing regenerated collagen fibers as described in <1> above, the method for manufacturing modified regenerated collagen fibers as described in <2> above, or the method for manufacturing headwear products as described in <3> above, wherein the fiber swelling rate in water is preferably 250-1000%, more preferably 300-800%, further preferably 350-600%, and even more preferably 350-500%.

[0166] <6> The regenerated collagen fiber processing method as described in any one of <1>, <4> and <5> above, the modified regenerated collagen fiber manufacturing method as described in any one of <2>, <4> and <5> above, or the headwear article manufacturing method as described in any one of <3> to <5> above, wherein the regenerated collagen fiber preferably contains the following component (B).

[0167] (B) Polyvalent metals, or their salts or complexes

[0168] <7> The method for processing regenerated collagen fibers as described in <6> above, the method for manufacturing modified regenerated collagen fibers as described in <6> above, or the method for manufacturing headwear products as described in <6> above, wherein component (B) is preferably selected from one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron and copper, or their salts or complexes, more preferably selected from one or more polyvalent metals selected from aluminum, zirconium and titanium, or their salts or complexes, and even more preferably aluminum, or its salts or complexes.

[0169] <8> The regenerated collagen fiber processing method, the modified regenerated collagen fiber manufacturing method, or the headwear product manufacturing method described in <6> or <7> above, wherein the content of component (B) in the regenerated collagen fiber, in terms of metal element content, is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, further preferably 3.0% by mass or more, further more preferably 5.0% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and further more preferably 10% by mass or less.

[0170] <9> The regenerated collagen fiber processing method described in <6> or <7> above, the modified regenerated collagen fiber manufacturing method described in <6> or <7> above, or the headwear product manufacturing method described in <6> or <7> above, wherein the content of component (B) in the regenerated collagen fiber, in terms of metal element content, is preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, further preferably 3.0 to 20% by mass, and even more preferably 5.0 to 10% by mass.

[0171] <10> The regenerated collagen fiber processing method as described in any one of <1>, <4> to <9> above, the modified regenerated collagen fiber manufacturing method as described in any one of <2>, <4> to <9> above, or the headwear article manufacturing method as described in any one of <3> to <9> above, wherein, prior to step (i), it is preferable to include a regenerated collagen fiber manufacturing step of solubilizing insoluble collagen fibers made from the hides of livestock animals, spraying the resulting collagen aqueous solution through a spinning nozzle or slit, and then immersing it in an inorganic salt aqueous solution.

[0172] <11> The method for processing regenerated collagen fibers as described in <10> above, the method for manufacturing modified regenerated collagen fibers as described in <10> above, or the method for manufacturing headwear products as described in <10> above, wherein, preferably, after the regenerated collagen fiber manufacturing step, a cross-linking treatment step is included, in which the regenerated collagen fibers are impregnated in an epoxy compound monomer or a solution thereof.

[0173] <12> The method for processing regenerated collagen fibers as described in <10> above, the method for manufacturing modified regenerated collagen fibers as described in <10> above, or the method for manufacturing headwear products as described in <10> above, wherein, preferably, after the regenerated collagen fiber manufacturing process, the process of immersing the regenerated collagen fibers in an aqueous solution of aluminum salts is performed.

[0174] <13> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <12> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <12> above, or the method for manufacturing headwear articles as described in any one of <3> to <12> above, wherein component (A) is preferably a copolymer comprising one or more structural units derived from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids and their salts, and structural units derived from aromatic vinyl compounds.

[0175] <14> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <13> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <13> above, or the method for manufacturing headwear articles as described in any one of <3> to <13> above, wherein component (A) preferably further comprises structural units derived from unsaturated aliphatic hydrocarbon compounds.

[0176] <15> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <14> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <14> above, or the method for manufacturing headwear articles as described in any one of <3> to <14> above, wherein component (A) is preferably selected from one or more of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinylbenzoic acid-maleic acid copolymer, vinylbenzoic acid-acrylic acid copolymer, vinylbenzoic acid-methacrylic acid copolymer, styrene-4-vinylbenzoic acid copolymer and their salts, and more preferably styrene-maleic acid copolymer or its salt.

[0177] <16> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <15> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <15> above, or the method for manufacturing headwear articles as described in any one of <3> to <15> above, wherein the ratio of structural units (u1) derived from unsaturated monomers having carboxyl groups or their salts to structural units (u2) derived from aromatic vinyl compound monomers is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1 in molar ratio (u1 / u2).

[0178] <17> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <16> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <16> above, or the method for manufacturing headwear articles as described in any one of <3> to <16> above, wherein the acid value of component (A) is preferably 200 mg KOH / g or more, more preferably 300 mg KOH / g or more, further preferably 400 mg KOH / g or more, and preferably 1000 mg KOH / g or less, more preferably 800 mg KOH / g or less, and further preferably 600 mg KOH / g or less.

[0179] <18> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <16> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <16> above, or the method for manufacturing headwear articles as described in any one of <3> to <16> above, wherein the acid value of component (A) is preferably 200 to 1000 mg KOH / g, more preferably 300 to 800 mg KOH / g, and even more preferably 400 to 600 mg KOH / g.

[0180] <19> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <18> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <18> above, or the method for manufacturing headwear articles as described in any one of <3> to <18> above, wherein the weight-average molecular weight of component (A) is preferably 2000 or more, more preferably 3000 or more, further preferably 4000 or more, and preferably 12000 or less, more preferably 10000 or less, further preferably 8000 or less, and even more preferably 7000 or less.

[0181] <20> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <18> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <18> above, or the method for manufacturing headwear articles as described in any one of <3> to <18> above, wherein the weight-average molecular weight of component (A) is preferably 2000 to 12000, more preferably 3000 to 12000, and preferably 1500 to 10000, more preferably 2000 to 8000, further preferably 3000 to 8000, and even more preferably 4000 to 7000.

[0182] <21> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <20> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <20> above, or the method for manufacturing headwear articles as described in 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, further preferably 2.3% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 40% by mass or less, and further more preferably 30% by mass or less.

[0183] <22> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <20> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <20> above, or the method for manufacturing headwear articles as described in any one of <3> to <20> above, 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.

[0184] <23> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <22> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <22> above, or the method for manufacturing headwear articles as described in any one of <3> to <22> above, wherein the pH of the fiber treatment agent is preferably 2.0 or higher, more preferably 3.0 or higher, further preferably 3.5 or higher, further more preferably 4.0 or higher, and preferably 11.0 or lower, more preferably 10.0 or lower, further preferably 9.0 or lower, further more preferably 7.0 or lower, and further more preferably 6.5 or lower.

[0185] <24> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <22> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <22> above, or the method for manufacturing headwear articles as described in 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, further preferably 3.5 to 9.0, and even more preferably 3.5 to 6.5.

[0186] <25> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <24> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <24> above, or the method for manufacturing headwear articles as described in 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, further preferably 1.3% by mass, even more preferably 2.3% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0187] <26> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <24> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <24> above, or the method for manufacturing headwear articles as described in 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, further preferably 1.3 to 10% by mass, and even more preferably 2.3 to 10% by mass.

[0188] <27> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <24> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <24> above, or the method for manufacturing headwear articles as described in 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 higher, more preferably 2.0% by mass or higher, even more preferably 3.0% by mass or higher, and preferably 60% by mass or lower, more preferably 50% by mass or lower, even more preferably 40% by mass or lower.

[0189] <28> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <24> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <24> above, or the method for manufacturing headwear articles as described in 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% by mass, more preferably 2.0 to 50% by mass, and even more preferably 3.0 to 40% by mass.

[0190] <29> The regenerated collagen fiber treatment method as described in any one of <1>, <4> to <28> above, the modified regenerated collagen fiber manufacturing method as described in any one of <2>, <4> to <28> above, or the headwear product manufacturing method as described in 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 the balance excluding component (A) and any other compounded components.

[0191] <30> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <28> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <28> above, or the method for manufacturing headwear articles as described in 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, further preferably 30% by mass or more, further more preferably 40% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, further preferably 96% by mass or less, further more preferably 95% by mass or less, further more preferably 90% by mass or less, and further more preferably 85% by mass or less.

[0192] <31> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <28> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <28> above, or the method for manufacturing headwear products as described in 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 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, even more preferably 40 to 85% by mass.

[0193] <32> The regenerated collagen fiber treatment method as described in any one of <1>, <4> to <31> above, the modified regenerated collagen fiber manufacturing method as described in any one of <2>, <4> to <31> above, or the headwear article manufacturing method as described in any one of <3> to <31> above, wherein, in step (i), it is preferable to impregnate the regenerated collagen fiber with a fiber treatment agent more than twice.

[0194] <33> The regenerated collagen fiber treatment method described in <32> above, the modified regenerated collagen fiber manufacturing method described in <32> above, or the headwear product manufacturing method described in <32> above, wherein preferably, a two-step treatment process is included, wherein after treatment with a first fiber treatment agent containing the following component (A), treatment is performed with a second fiber treatment agent containing the following component (A) and the pH is adjusted to be 1.0 or lower than that of the first fiber treatment agent.

[0195] <34> The method for processing regenerated collagen fibers as described in <33> above, the method for manufacturing modified regenerated collagen fibers as described in <33> above, or the method for manufacturing headwear products as described in <33> above, wherein, preferably, after the two-step processing steps, a step is further included in which an additional fiber treatment agent containing benzoic acid or its salt as component (C) is used for treatment.

[0196] <35> The regenerated collagen fiber treatment method described in <32> above, the modified regenerated collagen fiber manufacturing method described in <32> above, or the headwear product manufacturing method described in <32> above, wherein preferably, it includes a multi-step treatment process, wherein, preferably, after treatment with a first fiber treatment agent containing the following component (A) two to three or more times, treatment is performed with a second fiber treatment agent containing the following component (A) and whose pH is adjusted to be 1.0 or lower than that of the first fiber treatment agent.

[0197] <36> The method for treating regenerated collagen fibers as described in <32> above, the method for manufacturing modified regenerated collagen fibers as described in <32> above, or the method for manufacturing headwear products as described in <32> above, preferably includes 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).

[0198] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0199] <37> The method for treating regenerated collagen fibers as described in <34> or <36> above, the method for manufacturing modified regenerated collagen fibers as described in <34> or <36> above, or the method for manufacturing headwear products as described in <34> or <36> above, wherein the content of (C) benzoic acid or its salt in the added fiber treatment agent, calculated as benzoic acid, is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 5% by mass or more, even more preferably 10% by mass or more, even 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, even more preferably 40% by mass or less, and even more preferably 35% by mass or less.

[0200] <38> The method for treating regenerated collagen fibers as described in <34> or <36> above, the method for manufacturing modified regenerated collagen fibers as described in <34> or <36> above, or the method for manufacturing headwear products as described in <34> or <36> above, wherein the content of (C) benzoic acid or its salt in the added fiber treatment agent, calculated as benzoic acid, is preferably 0.1 to 60% by mass, more preferably 1 to 55% by mass, further preferably 5 to 50% by mass, even more preferably 10 to 40% by mass, and even more preferably 20 to 35% by mass.

[0201] <39> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <38> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <38> above, or the method for manufacturing headwear articles as described in any one of <3> to <38> above, wherein the amount of fiber treatment agent is preferably 2 or more, more preferably 3 or more, further preferably 5 or more, further more preferably 10 or more, further more preferably 20 or more, and preferably 500 or less, more preferably 250 or less, further preferably 100 or less, and further more preferably 50 or less, based on the bath ratio (mass of fiber treatment agent / mass of regenerated collagen fibers) relative to the mass of regenerated collagen fibers.

[0202] <40> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <38> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <38> above, or the method for manufacturing headwear articles as described in any one of <3> to <38> above, wherein the amount of fiber treatment agent is preferably 2 to 500, more preferably 3 to 250, further preferably 5 to 100, further more preferably 10 to 100, further more preferably 20 to 100, and further more preferably 20 to 50, based on the bath ratio (mass of fiber treatment agent / mass of regenerated collagen fibers) relative to the mass of regenerated collagen fibers.

[0203] <41> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <40> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <40> above, or the method for manufacturing headwear articles as described in any one of <3> to <40> above, wherein the immersion temperature of the regenerated collagen fibers 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 preferably lower than 100°C, more preferably lower than 80°C, even more preferably lower than 70°C, even more preferably lower than 60°C, and even more preferably lower than 50°C.

[0204] <42> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <40> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <40> above, or the method for manufacturing headwear articles as described in any one of <3> to <40> above, wherein the immersion temperature of the regenerated collagen fibers in the fiber treatment agent is preferably 20°C or higher and lower than 100°C, more preferably 25 to 80°C, further preferably 30 to 70°C, further more preferably 30 to 60°C, and even more preferably 30 to 50°C.

[0205] <43> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <42> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <42> above, or the method for manufacturing headwear articles as described in any one of <3> to <42> above, wherein the soaking time is preferably 15 minutes or more, more preferably 30 minutes or more, further preferably 1 hour or more, even more preferably 3 hours or more, even more preferably 5 hours or more, even more preferably 10 hours or more, and preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 30 hours or less.

[0206] <44> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <42> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <42> above, or the method for manufacturing headwear articles as described in any one of <3> to <42> above, wherein the soaking time is preferably 15 minutes or more and 48 hours or less, more preferably 30 minutes or more and 33 hours or less, further preferably 1 hour or more and 30 hours or less, even more preferably 3 hours or more and 30 hours or less, even more preferably 5 hours or more and 30 hours or less, and even more preferably 10 hours or more and 30 hours or less.

[0207] <45> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <44> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <44> above, or the method for manufacturing headwear products as described in any one of <3> to <44> above, wherein step (i) is preferably performed in an environment where moisture evaporation is suppressed.

[0208] <46> The method for treating regenerated collagen fibers as described in any one of <1>, <4> to <45> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <45> above, or the method for manufacturing headwear products as described in any one of <3> to <45> above, wherein the fiber treatment agent is a fiber-permeable type.

[0209] <47> The method for processing regenerated collagen fibers as described in any one of <1>, <4> to <46> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <2>, <4> to <46> above, or the method for manufacturing headwear articles as described in any one of <3> to <46> above, wherein, when the copolymer 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.

[0210] <48> The method for processing regenerated collagen fibers as described in any one of <34> to <38> above, the method for manufacturing modified regenerated collagen fibers as described in any one of <34> to <38> above, or the method for manufacturing headwear articles as described in 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 potassium salt, and even more preferably a sodium salt.

[0211] <49> A modified regenerated collagen fiber, wherein the modified regenerated collagen fiber is formed by containing the following component (A) in the regenerated collagen fiber.

[0212] (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

[0213] <50> The modified regenerated collagen fiber as described in <49> above, wherein component (A) is preferably a copolymer comprising structural units derived from one or more structural units selected from unsaturated monocarboxylic acids, unsaturated dicarboxylic acids and their salts, and structural units derived from aromatic vinyl compounds.

[0214] <51> The modified regenerated collagen fiber as described in <49> or <50> above, wherein component (A) is preferably selected from one or more of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinyl benzoic acid-maleic acid copolymer, vinyl benzoic acid-acrylic acid copolymer, vinyl benzoic acid-methacrylic acid copolymer, styrene-4-vinyl benzoic acid copolymer and their salts, and more preferably styrene-maleic acid copolymer or its salt.

[0215] <52> Modified regenerated collagen fiber as described in any one of <49> to <51> above, wherein component (A) preferably further comprises structural units derived from unsaturated aliphatic hydrocarbon compounds.

[0216] <53> The modified regenerated collagen fiber as described in any one of <49> to <52> above, wherein the ratio of structural units (u1) derived from unsaturated monomers having carboxyl groups or their salts to structural units (u2) derived from aromatic vinyl compound monomers is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1 in molar ratio (u1 / u2).

[0217] <54> Modified regenerated collagen fiber as described in any one of <49> to <53> above, 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, lithium salt, potassium salt, calcium salt or magnesium salt, and even more preferably a sodium salt.

[0218] <55> The modified regenerated collagen fiber as described in any one of <49> to <54> above, wherein the acid value of component (A) is preferably 200 mg KOH / g or more, more preferably 300 mg KOH / g or more, further preferably 400 mg KOH / g or more, and preferably 1000 mg KOH / g or less, more preferably 800 mg KOH / g or less, and further preferably 600 mg KOH / g or less.

[0219] <56> The modified regenerated collagen fiber as described in any one of <49> to <54> above, wherein the acid value of component (A) is preferably 200-1000 mgKOH / g, more preferably 300-800 mgKOH / g, and even more preferably 400-600 mgKOH / g.

[0220] <57> The modified regenerated collagen fiber as described in any one of <49> to <56> above, 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.

[0221] <58> The modified regenerated collagen fiber as described in any one of <49> to <56> above, wherein the weight-average molecular weight of component (A) is preferably 2000 to 12000, more preferably 3000 to 12000, and even more preferably 2000 to 8000, more preferably 3000 to 8000, and even more preferably 4000 to 7000.

[0222] <59> The modified regenerated collagen fiber as described in any one of <49> to <58> above, wherein the content of component (A) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1.0% by mass or more, further more preferably 3.0% by mass or more, further preferably 5.0% by mass or more, further preferably 10% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, further preferably 60% by mass or less, further more preferably 55% by mass or less, further more preferably 50% by mass or less, and further more preferably 45% by mass or less.

[0223] <60> Modified regenerated collagen fiber as described in any one of <49> to <58> above, 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, even more preferably 10 to 45% by mass.

[0224] <61> The modified regenerated collagen fiber as described in any one of <49> to <60> above, preferably further comprising the following component (B).

[0225] (B) A polyvalent metal, or its salt or complex.

[0226] <62> The modified regenerated collagen fiber as described in <61> above, wherein component (B) is preferably selected from one or more polyvalent metals, or their salts or complexes, selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron and copper, more preferably from one or more polyvalent metals, or their salts or complexes, selected from aluminum, zirconium and titanium, and even more preferably aluminum, or its salts or complexes.

[0227] <63> The modified regenerated collagen fiber as described in <61> or <62> above, wherein the content of component (B) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1.0% by mass or more, further preferably 2.0% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and further preferably 10% by mass or less.

[0228] <64> The modified regenerated collagen fiber as described in <61> or <62> above, wherein the content of component (B) is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, further preferably 1.0 to 20% by mass, and even more preferably 2.0 to 10% by mass, in terms of metal element content.

[0229] <65> A headdress article, wherein the headdress article has the modified regenerated collagen fiber as any one of <49> to <64> as a constituent element.

[0230] <66> The headdress product as described in <65> above, wherein the headdress product is selected from wigs, wigs, hair weaving, hair extensions, braids, hair ornaments and doll hair.

[0231] [Example]

[0232] <Analytical Methods>

[0233] 1. Determination of the swelling rate of regenerated collagen fibers in water

[0234] The fiber swelling rate in water is calculated according to the following formula (1).

[0235] The fiber swelling rate in water, S (%) = [(w1-w2) / w2] × 100 (1)

[0236] The definitions of each symbol in equation (1) are as follows.

[0237] w1: Immerse 1.0g of regenerated collagen fiber in a container with 100g of ion-exchanged water, seal the container, and immerse the container together in a water bath set to 40°C (model: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) for 30 minutes. After heating, remove the regenerated collagen fiber from the container and place it in a small centrifuge (H-112, KOKUSAN Co. Ltd.). Centrifuge at a centrifugal force of 220 [×g] (speed knob "4" (2000rpm)) for 1 minute to dehydrate, and then immediately measure its weight and set it as weight w1.

[0238] w2: Place the regenerated collagen fiber, after the weight w1 has been measured, on filter paper, put it in a dryer (SOFW-450SB, AS ONE Corporation) set to 105℃ and dry for 3 hours. Take it out and immediately measure its weight, and set it as weight w2.

[0239] 2. Determination of the weight-average molecular weight of component (A)

[0240] The weight-average molecular weight (Mw) of polystyrene was determined by gel permeation chromatography (GPC) under the following conditions.

[0241] (1) Sample

[0242] • Ultrapure water: Water produced by the Milli-Q ultrapure water manufacturing system, manufactured by Millipore.

[0243] • Dimethylformamide (DMF): Premium grade, manufactured by Kanto Chemical Co., Ltd.

[0244] • Lithium bromide monohydrate (LiBr): Premium grade, manufactured by Kanto Chemical Co., Ltd.

[0245] • Phosphoric acid: Extra grade, manufactured by Sigma-Aldrich

[0246] (2) Sample pretreatment method

[0247] Accurately weigh approximately 50 mg of the sample, add 0.5 mL of ultrapure water, then add 10 mL of the mobile phase described later. Filter the solution through a filter and use the resulting solution as the sample solution.

[0248] (3) Measurement

[0249] Using the sample solution and standard solution, GPC determination was performed under the following conditions to determine the converted weight-average molecular weight of polystyrene.

[0250] • Flow rate: 1 mL / min

[0251] • Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr

[0252] • Column: TSKgel α (α) column (manufactured by Tosoh Corporation)

[0253] • Detector: RI (Differential Refraction Detector)

[0254] •Standard reference: Monodisperse polystyrene

[0255] 3. Aluminum quantification method in fibers

[0256] The aluminum content in the treated regenerated collagen fibers was quantified using the following method.

[0257] (1) Sample

[0258] • Sulfuric acid: For precision analysis, manufactured by Fujifilm and Koden Chemical Co., Ltd.

[0259] • Hydrochloric acid: Used for metal analysis, manufactured by Kanto Chemical Co., Ltd.

[0260] • Sodium carbonate: Premium grade, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.

[0261] • Boric acid: Premium grade, manufactured by Fujifilm and Kojun Chemical Co., Ltd.

[0262] • Aluminum standard solution: 1000 mg / L for atomic absorption spectrometry analysis, manufactured by Kanto Chemical Co., Ltd.

[0263] • Ultrapure water: Water produced by the Milli-Q ultrapure water manufacturing system, manufactured by Millipore.

[0264] (2) Sample pretreatment method

[0265] The fiber bundle was suspended in a dryer (SOFW-450SB, AS ONE Corporation) set to 60°C, with a 250g weight installed at the lower end of the fiber bundle, and dried for 1 hour under tension.

[0266] Accurately weigh 0.1 g of the sample into a platinum crucible, heat until no more white fumes are produced, add a few drops of sulfuric acid, and heat again until no more white fumes are produced. Then, thoroughly ashing the sample using a 550°C electric furnace. Next, add 1 g of alkaline melting agent (sodium carbonate:boric acid = 1:0.4) and melt using a 950°C electric furnace. Cover with a watch glass, add 5 mL of ultrapure water and hydrochloric acid (6 mol / L), and heat to dissolve on a hot plate at 70–80°C. After cooling, dilute to 50 mL with ultrapure water. Use this diluted solution as the assay solution.

[0267] (3) Preparation of calibration curve solution

[0268] Calibration curve solutions of 0.1–20 mg / L were prepared using an aluminum standard solution (1000 mg / L). An equivalent amount of alkaline flux and hydrochloric acid was added to each solution.

[0269] (4) Measurement

[0270] The obtained sample was analyzed using an ICP emission spectrometer under the following conditions to determine each element.

[0271] • Analytical apparatus: iCAP6500Duo (manufactured by Thermo Fisher Scientific Inc.)

[0272] • Wavelength: Al 396.152nm

[0273] •RF power: 1150W

[0274] • Cooling gas flow rate: 12L / min

[0275] • Atomizer flow rate: 0.70L / min

[0276] • Assist gas: 0.5 L / min

[0277] • Pump flow rate: 50 rpm

[0278] 4. Determination of acid value

[0279] The determination was performed by potentiometric titration according to JIS K 0070.

[0280] 5. pH measurement

[0281] Each composition was directly measured at 25°C using a pH meter (F-52, manufactured by HORIBA).

[0282] 6. Quantitative method for component (A) in fibers

[0283] The following describes a method for quantifying component (A) in modified regenerated collagen fibers when styrene-maleic acid copolymer is used as component (A).

[0284] (1) Sample

[0285] • 1 mol / L sodium hydroxide aqueous solution: for volumetric analysis, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.

[0286] • Ultrapure water: Water produced by the Milli-Q ultrapure water manufacturing system, manufactured by Millipore.

[0287] • Dimethylformamide (DMF): Premium grade, manufactured by Kanto Chemical Co., Ltd.

[0288] • Lithium bromide monohydrate (LiBr): Premium grade, manufactured by Kanto Chemical Co., Ltd.

[0289] • Phosphoric acid: Extra grade, manufactured by Sigma-Aldrich

[0290] (2) Sample solution

[0291] After conditioning the sample at 20℃ and 65% relative humidity for 24 hours, finely chop it and accurately weigh approximately 50 mg. Add 10 mL of 1 mol / L sodium hydroxide aqueous solution and heat at 50℃ for 3 hours to dissolve. Adjust the pH of the solution to 4.7–5.3. Add 0.5 mL of ultrapure water to the freeze-dried sample, then add 9.5 mL of the mobile phase (described later) for dilution. Filter the diluted solution to prepare the sample solution.

[0292] (3) Preparation of calibration curve solution

[0293] Separately, the styrene-maleic acid copolymer was dissolved in the mobile phase described later, and a concentration of 0.25–5.0 mg / mL was prepared based on the non-dissociated styrene-maleic acid copolymer to prepare a standard solution for the preparation of a calibration curve.

[0294] (4) Measurement

[0295] Using the sample solution and standard solution, perform gel permeation chromatography (GPC) under the following conditions to determine the peak areas of the sample solution and the standard solution. Then, construct a calibration curve based on the peak area results of the standard solution.

[0296] • Flow rate: 0.8 mL / min

[0297] • Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr

[0298] • Column: TSKgel α (α) column (manufactured by Tosoh Corporation)

[0299] • Detector: Ultraviolet-Vis spectrophotometer

[0300] • Measurement wavelength: 267nm

[0301] (5) Calculation of the amount of styrene-maleic acid copolymer

[0302] The amount of styrene-maleic acid copolymer per unit fiber mass was calculated using a calibration curve based on the peak area of ​​the styrene-maleic acid copolymer contained in the modified regenerated collagen fiber.

[0303] 7. Quantitative method for the composition (C) in fibers

[0304] The amount of component (C) contained in the treated regenerated collagen fibers was quantified according to the following method.

[0305] (1) Sample

[0306] • 6N hydrochloric acid: titrant for volumetric analysis, manufactured by Kanto Chemical Co., Ltd.

[0307] • Sodium acetate: Premium grade, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.

[0308] • Acetic acid: Premium grade, manufactured by Fujifilm and Kojun Chemical Co., Ltd.

[0309] • Acetonitrile: For LC / MS, manufactured by Kanto Chemical Co., Ltd.

[0310] • Sodium benzoate: Premium grade, manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.

[0311] • Ultrapure water: Water produced by the Milli-Q ultrapure water manufacturing system, manufactured by Millipore.

[0312] (2) Sample pretreatment method

[0313] The sample was finely chopped, and approximately 10 mg was accurately weighed. Then, 3 mL of 6N hydrochloric acid was added, and the mixture was heated at 50°C for 15 hours to dissolve it. After cooling, the solution was filtered to obtain the sample solution.

[0314] (3) Preparation of calibration curve solution

[0315] Separately, component (A) is dissolved in the mobile phase, and for components with dissociation sites such as acid groups, it is prepared to a concentration of 0.1 to 100 μg / mL based on the non-dissociated component (A) to prepare a standard solution for the preparation of calibration curves.

[0316] (4) Measurement

[0317] For the sample solution and the standard solution, the peak area of ​​the sample solution and the peak area of ​​the standard solution were determined by liquid chromatography under the following conditions.

[0318] • Detector: Ultraviolet-Vis spectrometer

[0319] • Measurement wavelength: 230nm

[0320] • Column: A stainless steel tube with an inner diameter of 21 mm and a length of 150 mm is filled with 5 μm of octadecylsilanized silica gel for liquid chromatography.

[0321] • Column temperature: a constant temperature of around 40℃

[0322] • Mobile phase: Dissolve approximately 0.68 g of sodium acetate and 0.91 g of acetic acid in 750 mL of ultrapure water, then add 250 mL of acetonitrile and mix.

[0323] (5) HPLC / UV conditions

[0324] • Device: UltiMate3000 system (manufactured by Thermo Fisher Scientific Inc.)

[0325] • Column: L-column2 ODS, particle size 5μm, 2.1×150mm (Chemical Substance Evaluation Research Institute)

[0326] • Column temperature: 40℃

[0327] • Mobile phase: 20mM ammonium acetate 25% acetonitrile buffer

[0328] •Analysis time: 10 minutes

[0329] • Detector: DAD (Diode Array Detector)

[0330] • Detection wavelength: 230nm

[0331] • Flow rate: 0.3 mL / min (isocratic elution)

[0332] • Injection volume: 10μL

[0333] <Raw Materials Used>

[0334] The materials used in this embodiment are as follows.

[0335] (1) Regenerated collagen fibers

[0336] (i) Regenerated collagen fiber A

[0337] Manufacturing Example 1

[0338] Bovine hides are dissolved in alkali using conventional methods to prepare a spinning solution. This solution is then sprayed from a spinning nozzle into a coagulation bath for fiberization and epoxy compound treatment to produce regenerated collagen fibers. For each part by weight of this regenerated collagen fiber (converted to its dry weight), 30 parts by weight of an aqueous solution containing 5.0% by weight of aluminum sulfate tetradecahydrate, 0.65% by weight of citric acid monohydrate, and 1.3% by weight of sodium hydroxide is added. The temperature is adjusted to 30°C, and the solution is irrigated while circulating. Then, 5% sodium hydroxide aqueous solution is added in batches over approximately 1-5 hours. After 5 hours, the final pH of the solution is adjusted to 4.5-5.0. The solution is then maintained for 3 hours, followed by thorough washing to obtain regenerated collagen fiber A.

[0339] The water swelling rate of regenerated collagen fiber A was 435%. The coagulation bath was prepared in accordance with International Publication No. 2017 / 159565, and the epoxy compound treatment was carried out in accordance with International Publication No. 2014 / 132889.

[0340] (ii) Regenerated collagen fiber B

[0341] 300 bundles of regenerated collagen fiber A, each 30cm in length, were prepared (weighing 1.5g after drying at 60°C for 1 hour and then at 20°C and 65%RH for 12 hours). Each bundle was suspended individually in a dryer (SOFW-450SB, AS ONE Corporation) set to 60°C, with a 250g weight attached to the bottom of each bundle. The bundles were dried under tension for 1 hour and used as regenerated collagen fiber B.

[0342] • Shape: Straight bar

[0343] • Fiber swelling rate in water: 113%

[0344] • Aluminum content: 6.8% by mass

[0345] (iii) Regenerated collagen fiber C

[0346] Manufacturing Example 2

[0347] The cowhide plates are prepared into a spinning solution by alkali solubilization using conventional methods. The solution is then sprayed from the spinning nozzle into a coagulation bath for fiberization. After treatment with epoxy compounds, the solution is thoroughly washed with water to obtain regenerated collagen fiber C.

[0348] The water swelling rate of regenerated collagen fiber C was 692%. The coagulation bath was prepared in accordance with International Publication No. 2017 / 159565, and the epoxy compound treatment was carried out in accordance with International Publication No. 2014 / 132889.

[0349] (2) Styrene-maleic acid copolymer

[0350] (i) Sodium salt A of styrene-maleic acid copolymer

[0351] Use XIRAN1000HNa (manufactured by Polyscope).

[0352] •Weight-average molecular weight (Mw): 9195

[0353] • Acid value: 475 mg KOH / g

[0354] • Molar ratio of styrene to maleic acid: 1 / 1

[0355] (ii) Sodium salt of styrene-maleic acid copolymer B

[0356] Use XIRAN2000HNa (manufactured by Polyscope).

[0357] •Weight-average molecular weight (Mw): 8143

[0358] • Acid value: 355 mg KOH / g

[0359] • Molar ratio of styrene to maleic acid: 2 / 1

[0360] (iii) Sodium salt of styrene-maleic acid copolymer C

[0361] Use XIRAN3000HNa (manufactured by Polyscope).

[0362] •Weight-average molecular weight (Mw): 13803

[0363] • Acid value: 285 mg KOH / g

[0364] • Styrene / maleic acid molar ratio: 3 / 1

[0365] (iv) Sodium salt of styrene-maleic acid copolymer D

[0366] Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460(2002)), and then used after hydrolysis with sodium hydroxide aqueous solution.

[0367] •Weight-average molecular weight (Mw): 7049

[0368] • The hydrogen bonding term δH value of Hansen's solubility parameter: 11.5

[0369] • Acid value: 475 mg KOH / g

[0370] • Molar ratio of styrene to maleic acid: 1 / 1

[0371] (v) Sodium salt of styrene-maleic acid copolymer E

[0372] Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460(2002)), and then used after hydrolysis with sodium hydroxide aqueous solution.

[0373] •Weight-average molecular weight (Mw): 3829

[0374] • The hydrogen bonding term δH value of Hansen's solubility parameter: 11.5

[0375] • Acid value: 475 mg KOH / g

[0376] • Molar ratio of styrene to maleic acid: 1 / 1

[0377] (vi) Sodium salt of styrene-maleic acid copolymer F

[0378] Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460(2002)), and then used after hydrolysis with sodium hydroxide aqueous solution.

[0379] •Weight-average molecular weight (Mw): 10530

[0380] • The hydrogen bonding term δH value of Hansen's solubility parameter: 11.5

[0381] • Acid value: 475 mg KOH / g

[0382] • Molar ratio of styrene to maleic acid: 1 / 1

[0383] (vii) Sodium salt of styrene-maleic acid copolymer G

[0384] Styrene-maleic anhydride copolymer was synthesized according to the literature (Gunji et al., Color Materials, 75(10), 463-460(2002)), and then used after hydrolysis with sodium hydroxide aqueous solution.

[0385] •Weight-average molecular weight (Mw): 3288

[0386] • The hydrogen bonding term δH value of Hansen's solubility parameter: 11.5

[0387] • Acid value: 475 mg KOH / g

[0388] • Molar ratio of styrene to maleic acid: 1 / 1

[0389] (3) Sodium benzoate

[0390] Wako Special Grade samples were used (manufactured by Fujifilm Wako Pure Chemical Co., Ltd.).

[0391] • Molecular weight (M): 122

[0392] • Acid value: 460 mg KOH / g

[0393] Examples 1-15 and Comparative Examples 1-3

[0394] Using the compositions formulated in Tables 1 and 2, regenerated collagen fibers were treated according to the following methods, and various evaluations were performed. In Comparative Example 1, only steps (1) and (6) of treatment method A were performed for evaluation. The results of Examples 1-11 and Comparative Examples 1-2 are shown in Table 1, and the results of Examples 12-15 and Comparative Example 3 are shown together with the results of Comparative Example 1 in Table 2.

[0395] <Handling Method>

[0396] (1) Processing method A

[0397] Process regenerated collagen fiber A according to the following steps.

[0398] (Step 1)

[0399] In each embodiment and comparative example, 10 fiber bundles with a length of 30 cm were made from regenerated collagen fiber A (the weight of which reached 1.5 g after drying at 60°C for 1 hour and placing at 20°C and 65%RH for 12 hours).

[0400] (Step 2)

[0401] The fiber bundles are impregnated with a amount of fiber treatment agent that reaches the liquor ratio shown in the table (the liquor ratio is calculated based on the dried weight of 1.5g in step 1 above). Each bundle is impregnated in a separate container, and the openings of each container are sealed.

[0402] (Step 3)

[0403] Immerse the container together in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set to the temperature shown in the table and let it stand for 5 minutes. After raising the temperature of the liquid in the container to the temperature shown in the table, remove the container from the water bath.

[0404] (Step 4)

[0405] Place the container containing the fiber bundle on the stirring rotor (VMR-5R, AS ONE Corporation) inside a dryer (SOFW-450SB, AS ONE Corporation) set to the temperature shown in the table, and rotate the container at 80 rpm for the heating and stirring time shown in the table.

[0406] (Step 5)

[0407] Remove the container containing the fiber bundles from the dryer and allow it to return to room temperature. Then, remove the fiber bundles from the container, rinse them with 30°C tap water for 30 seconds, and comb them to guide the direction of the hair.

[0408] (Step 6)

[0409] The fiber bundles are suspended one by one in a dryer set to the temperature recorded in the table. A 250g weight is installed at the lower end of each fiber bundle, and the fibers are dried for the time recorded in the table while the fibers are under tension.

[0410] (Step 7)

[0411] Remove the fiber bundle from the dryer, allow it to return to room temperature, and remove the weights.

[0412] (2) Processing method B

[0413] Regenerated collagen fiber B is processed according to the following steps.

[0414] (Step 1)

[0415] In each of the embodiments and comparative examples, 10 bundles of 1.5g each (measured after being placed at 20°C and 65%RH for 12 hours) and 30cm in length were made from regenerated collagen fiber B.

[0416] (Step 2)

[0417] The fiber bundles are impregnated in a amount of fiber treatment agent that reaches the bath ratio shown in the table (the bath ratio is calculated based on the fiber weight of 1.5g in step 1 above). Each bundle is impregnated in a separate container, and the openings of each container are sealed.

[0418] (Step 3)

[0419] Immerse the container together in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set to the temperature shown in the table and let it stand for 5 minutes. After raising the temperature of the liquid in the container to the temperature shown in the table, remove the container from the water bath.

[0420] (Step 4)

[0421] Place the container containing the fiber bundle on the stirring rotor (VMR-5R, AS ONE Corporation) inside a dryer (SOFW-450SB, AS ONE Corporation) set to the temperature shown in the table, and rotate the container at 80 rpm for the heating and stirring time shown in the table.

[0422] (Step 5)

[0423] Remove the container containing the fiber bundles from the dryer and allow it to return to room temperature. Then, remove the fiber bundles from the container, rinse them with 30°C tap water for 30 seconds, and comb them to straighten the direction of the hair.

[0424] (Step 6)

[0425] The fiber bundles were suspended one by one in a dryer set to 60°C, and a 250g weight was installed at the bottom of each fiber bundle. The fibers were dried for 1 hour under tension.

[0426] (Step 7)

[0427] Remove the fiber bundle from the dryer, allow it to return to room temperature, and remove the weights.

[0428] <Evaluation>

[0429] 1. Quantitative

[0430] (i) Weight increase (%)

[0431] The weight (W) of the treated fiber bundle was measured after 12 hours of exposure at 20°C and 65%RH, and the weight gain relative to the initial fiber bundle weight of 1.5g was calculated.

[0432] Weight increase [%] = [(W-1.5) / 1.5] × 100

[0433] The greater the weight increase (%), the more component (A) has penetrated into the fiber. When the weight increase (%) is 0%, it can be considered that no component (A) has actually penetrated into the fiber.

[0434] (ii) The amount (%) of component (A) contained within the fiber (Mw is 1500 to 15000)

[0435] Based on the chromatogram obtained by GPC as described in "6. Quantitative Method of Component (A) in Fiber" of <Analytical Methods>, the amount of component (A) in modified regenerated collagen fiber, "GPC Quantitative Value Y (%)", is calculated. Here, "GPC Quantitative Value Y (%)" is the mass percentage of component (A) in the fiber, which is not consistent with the measured weight increase (%). That is, regarding the "GPC Quantitative Value Y (%)" mentioned here, since the weight-average molecular weight of the copolymers involved in component (A) is 1500–15000, it is not the amount of the molecular weight fraction of 1500–15000 in the GPC chromatogram, but rather refers to the quantitative value of all copolymers involved in component (A), including fractions with molecular weights less than 1500 and greater than 15000. Therefore, in the case of copolymers with a weight-average molecular weight less than 1500 or greater than 15000, since these copolymers do not belong to component (A), their quantitative value as component (A) is 0.

[0436] Then, the "theoretical weight increase X (%)" is obtained from the "GPC quantitative value Y (%)" using the following method.

[0437] (iii) Theoretical weight increase (%)

[0438] Based on the GPC quantification value Y (%) calculated from (ii) above, the theoretical weight gain X (%) is calculated using the following formula. Wherein, the theoretical weight gain X (%) is the maximum value assuming no loss of components due to dissolution from fibers, etc.

[0439] Weight increase X [%] = 100Y / (100-Y)

[0440] 2. Water resistance

[0441] (1) Elastic modulus of fiber under water tension (MPa)

[0442] The elastic modulus of the fibers under tensile stress in water was determined as described below. Evaluation was performed using fiber bundles that had just been treated using the aforementioned <treatment method>. Furthermore, the average value obtained from evaluating multiple fibers (5 fibers) was used. A higher value indicates better stiffness, resistance to stretching under external forces, and superior durability. The evaluation was conducted according to the following steps.

[0443] (Step 1)

[0444] Five fibers were cut from the fiber bundle, and a 3cm fiber piece was taken from each fiber, resulting in a total of five 3cm fiber pieces.

[0445] (Step 2)

[0446] The fiber sheet was mounted on an automatic fiber tensile testing machine (MTT690, manufactured by DIA-STRON Limited). After the fiber was immersed in water for 30 minutes, the automatic tensile test was started to determine the elastic modulus of the fiber under water tension. The cross-sectional area of ​​the fiber in water necessary for determining the elastic modulus was measured directly by observation using an optical microscope.

[0447] (2) The rate of increase in average breaking elongation during fiber stretching (%)

[0448] As an indicator of the fiber's water resistance and elasticity (toughness) during stretching, the average elongation at break is used, that is, the percentage of the original fiber length at which the fiber breaks after stretching. This is the average value obtained by evaluating multiple (10) fibers. The evaluation is conducted using fiber bundles that have just been treated using the above-described <treatment method> according to the following steps.

[0449] (Step 1)

[0450] Cut 10 fibers from the root of the fiber bundle. Take a 3cm fiber piece from the middle of the root and tip of each fiber, resulting in 10 3cm hair pieces.

[0451] (Step 2)

[0452] The fiber sheet was mounted on an automatic fiber tensile testing machine (MTT690, manufactured by DIA-STRON Limited). After being immersed in water for 30 minutes, the machine automatically measured and calculated the average elongation at break of the fiber in the water-immersed state. A higher value indicates higher elasticity, better toughness, and excellent durability.

[0453] According to the following formula, based on the average elongation at break (A%) of the fiber when stretched, the extent to which the average elongation at break (B%) of the treated fiber bundle increased (C%) relative to the untreated state is recorded in the table as the "increase rate (%) of average elongation at break of fiber when stretched".

[0454] The increase rate of average breaking elongation during fiber stretching C (%) = B (%) - A (%) (3) The increase in average breaking load during fiber stretching (gf)

[0455] The average breaking load of the fiber during tensile testing was used as an indicator of its water resistance. The evaluation was conducted using fiber bundles that had just been treated using the aforementioned <treatment method>. Furthermore, the average value was used when evaluating multiple fibers (10 fibers). The evaluation was performed according to the following steps.

[0456] (Step 1)

[0457] Cut 10 fibers from the root of the fiber bundle. Take a 3cm fiber piece from the middle of the root and tip of each fiber, resulting in 10 3cm hair pieces.

[0458] (Step 2)

[0459] The fiber sheet was mounted on an automatic fiber tensile testing machine (MTT690, manufactured by DIA-STRON Limited). After being immersed in water for 30 minutes, the machine automatically measured and determined the breaking load of the fiber when stretched while immersed in water. The higher the value, the less likely it is to break under external force, and the better its durability.

[0460] According to the following formula, based on the average breaking load (W0 (gf)) of the fiber under dry state (untreated fiber (Comparative Example 1)) without chemical treatment, the extent to which the average breaking load (W1 (gf)) of the treated fiber bundle increased relative to the untreated state (Y (gf)) is recorded in the table as "the increase in average breaking load [gf] of fiber under stretching".

[0461] Y(gf)=W1(gf)-W0(gf)

[0462] (4) Concentration (ppm) of component (A) in the fiber cleaning solution

[0463] The concentration of component (A) in the fiber cleaning solution was determined according to the following steps. Evaluation was performed using fiber bundles that had just been treated using the above-described <treatment method>, i.e., using fiber bundles obtained in Example 1 and Comparative Example 3.

[0464] (i) Preparation of fiber cleaning solution

[0465] Cut fibers from the root of the fiber bundle to make a 1.0g fiber bundle. Immerse this 1.0g fiber bundle in a container containing 100g of ion-exchanged water, seal the container, and immerse the container together in a water bath set to 40°C (model: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) for 1 hour. Then remove the fiber from the container. Use the remaining ion-exchanged water in the container as a fiber cleaning solution.

[0466] (ii) Quantification of component (A) in fiber cleaning solution

[0467] Quantification was performed by measuring the absorbance at a suitable wavelength using a UV-Vis-NIR spectrophotometer. For example, when component (A) is sodium styrene-maleic acid copolymer (XIRAN1000HNa, manufactured by Polyscope), the absorbance at 258 nm was measured using a UV-Vis-NIR spectrophotometer (V-560, manufactured by Nippon Spectrophotometer Co., Ltd.), and the concentration of component (A) was calculated based on this absorbance. A calibration curve was prepared by diluting the Polyscope-manufactured "XIRAN1000HNa" with deionized water.

[0468] 3. Thermal shape memory capability

[0469] The thermal shape memory capability was evaluated using fiber bundles that had just been treated using the above-described processing method. 0.5g of fiber was cut from the root of the fiber bundle to create a 22cm long fiber bundle. In the evaluation of "(I) Shape Imparting (Curling)," if the curling rate I was below 7%, it was considered ineffective, and no further processing or evaluation was performed.

[0470] (I) Shape given (curl)

[0471] (Step 1)

[0472] After wetting the 22cm long fiber bundle with 30℃ tap water for 30 seconds, wrap the wetted fiber bundle around a 14mm diameter plastic rod and fix it with a clip.

[0473] (Step 2)

[0474] The entire fiber bundle wound on the rod is immersed in a 60°C water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) and heated for 1 minute.

[0475] (Step 3)

[0476] Remove the fiber bundle from the water bath, immerse it in water at 20°C for 1 minute, remove it from the water and allow it to return to room temperature.

[0477] (Step 4)

[0478] Remove the fiber bundle from the rod, comb it three times, then take it out of the water. Three minutes after taking it out, take a photo from the front and side while it is suspended.

[0479] (Step 5)

[0480] Measure the length L of the fiber bundle when it is suspended vertically based on the photograph (the distance from the top of the fiber bundle to the farthest point 1).

[0481] (Evaluation Criteria)

[0482] The length of the fiber bundle when it is stretched into a straight line is set as L0, the length of the fiber bundle after the shape is assigned is set as L, and the curling rate calculated according to the following formula = fiber bundle length reduction rate (I) (%) is defined as the curling strength.

[0483] Roll-up rate I (%) = [(L0-L) / L0] × 100

[0484] (II) Reshape (straighten)

[0485] (Step 1)

[0486] After combing the fiber bundles evaluated in (1) above to straighten the hair flow direction, use a straightener (AHI-938, manufactured by Miki Electric Industry Co., Ltd.) set to 180°C to slide 6 times at a speed of 5cm / sec.

[0487] (Step 2)

[0488] Rinse with running tap water at 30°C for 30 seconds, then dry with a towel.

[0489] (Step 3)

[0490] Hang and air dry at 20°C and 65%RH for 12 hours. After combing three times, take photos from the front and side while hanging.

[0491] (Step 4)

[0492] Measure the length L of the fiber bundle when it is suspended vertically based on the photograph (the distance from the top of the fiber bundle to the farthest point 1).

[0493] (Evaluation Criteria)

[0494] Let L0 be the length of the fiber bundle when it is stretched into a straight line, and L be the length of the fiber bundle after the shape assignment operation. Let the straightening rate (ST) (%) calculated according to the following formula be defined as the degree of straightening achievement. When ST=100%, the fiber bundle is completely straightened.

[0495] Straightening rate ST (%) = [1 - [(L0 - L) / L0]] × 100

[0496] (III) Reshape (curl)

[0497] (Step 1)

[0498] After wetting the fiber bundle evaluated in (2) above with tap water at 30°C for 30 seconds, the wetted fiber bundle is wrapped around a plastic rod with a diameter of 14 mm and fixed with a clip.

[0499] (Step 2)

[0500] The entire fiber bundle wound on the rod is immersed in a 60°C water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) and heated for 1 minute.

[0501] (Step 3)

[0502] Remove the fiber bundle from the water bath, immerse it in water at 20°C for 1 minute, remove it from the water and allow it to return to room temperature.

[0503] (Step 4)

[0504] Remove the fiber bundle from the rod, comb it three times, then take it out of the water. Three minutes after taking it out, take a photo from the front and side while it is suspended.

[0505] (Step 5)

[0506] Measure the length L of the fiber bundle when it is suspended vertically based on the photograph (the distance from the top of the fiber bundle to the farthest point 1).

[0507] (Evaluation Criteria)

[0508] The length of the fiber bundle when it is stretched into a straight line is set as L0, the length of the fiber bundle after the shape is assigned is set as L, and the curling rate calculated according to the following formula = fiber bundle length reduction rate (I) (%) is defined as the curling strength.

[0509] Roll-up rate I (%) = [(L0-L) / L0] × 100

[0510] 4. Fiber swelling rate in water (%)

[0511] The fiber swelling rate in water was calculated according to the following formula (1). The evaluation was conducted using fiber bundles that had just been treated using the above-described treatment method.

[0512] The fiber swelling rate in water, S (%) = [(w1-w2) / w2] × 100 (1)

[0513] The definitions of each symbol in equation (1) are as follows.

[0514] w1: Cut the fiber from the root of the fiber bundle to make a 1.0g fiber bundle. Immerse the 1.0g fiber bundle in a container with 100g of ion-exchanged water, seal the container, and immerse the container together in a water bath set to 40°C (model: TBS221FA, manufacturer: Toyo Seisakusho Co., Ltd.) for 30 minutes. Remove the fiber from the container and place it in a small centrifuge (H-112, KOKUSAN Co. Ltd.). Centrifuge at a centrifugal force of 220 [×g] (speed knob "4" (2000rpm)) for 1 minute to dehydrate the fiber. Immediately weigh the fiber and record it as weight w1.

[0515] w2: After the weight w1 has been measured, the fiber is placed on filter paper and dried in a dryer set at 105°C (SOFW-450SB, AS ONE Corporation) for 3 hours. The fiber is then removed and its weight is measured immediately. This weight is recorded as w2.

[0516] 5. Excellent surface feel

[0517] Regarding the evaluation of surface feel, using fiber bundles that have just been treated using the <treatment method>, five professionals evaluated the smoothness of the feel when touched by hand according to the following criteria, and the total value of the five professionals was taken as the evaluation result.

[0518] (Evaluation Criteria)

[0519] 5: Compared to untreated fibers (Comparative Example 1), the texture is extremely smooth to the touch.

[0520] 4: Compared to untreated fibers (Comparative Example 1), the texture is smoother to the touch.

[0521] 3: Compared to untreated fibers (Comparative Example 1), the texture feels slightly smoother to the touch.

[0522] 2: The tactile sensation of the hand was unchanged compared to that of the untreated fiber (Comparative Example 1).

[0523] 1: It is rougher and drier than untreated fibers (Comparative Example 1), and has a poorer tactile feel.

[0524] 6. Heat resistance

[0525] (1) Shrinkage rate (%) after contact with water vapor at 110℃

[0526] The shrinkage rate after contact with 110°C water vapor was determined according to the following steps. The evaluation was performed using fiber bundles that had just been treated using the above-described treatment method.

[0527] (Step 1)

[0528] Cut the fibers from the fiber bundles and fix the ends of the five fiber bundles with tape (Scholes tape, 3M) to make a sample. At this time, the length of the fiber between the tapes is set to 10.0 cm.

[0529] (Step 2)

[0530] Place the sample into an autoclave (model: LSX-700, manufactured by TOMY KOGYO CO.,LTD.) and heat at 110°C for 10 minutes.

[0531] (Step 3)

[0532] Remove the sample and measure the length h of the fibers between the tapes. Calculate the percentage of shrinkage compared to the length before heating, and use this as the shrinkage rate H (%) after contact with 110℃ water vapor. The closer H is to 0%, the less likely the material will shrink due to heat, indicating superior heat resistance.

[0533] Shrinkage rate H (%) after contact with water vapor at 110℃ = [(10-h) / 10]×100

[0534] [In the formula, h represents the length (cm) of the sample after heating at 110℃ for 10 minutes.]

[0535] Then, the heat resistance of the fiber is judged according to the following criteria.

[0536] Based on the shrinkage rate H0 (%) of the untreated regenerated collagen fiber A after contact with water vapor at 110°C, the value of ΔH calculated by ΔH=H0-H is evaluated using scores from A to E.

[0537] (Evaluation Criteria)

[0538] A: 6 < ΔH

[0539] B: 4 < ΔH ≤ 6

[0540] C: 2 < ΔH ≤ 4

[0541] D: 0 < ΔH ≤ 2

[0542] E: ΔH≤0

[0543] 7. Inhibits fiber staining

[0544] Regarding the suppression of coloration in fibers, the following steps are performed for evaluation. The evaluation uses fiber bundles that have just been treated using the above-described <treatment method>.

[0545] (Step 1)

[0546] For the surface of the fiber bundle, the color of the fiber near the root, near the middle, and near the tip was measured using a spectrophotometer (CR-400 colorimeter, manufactured by Konica Minolta). The average value of the six points was taken as the colorimetric value (L, a, b).

[0547] (Step 2)

[0548] Regarding the degree of coloring, using white untreated fiber (Comparative Example 1) as a benchmark, ΔE was used... *ab An evaluation will be conducted. Furthermore, colorimetric measurements will be performed on the same day the processing begins.

[0549] ΔE *abThe following definition applies: when the measured values ​​of the untreated white fiber (Comparative Example 1) are set as (L0, a0, b0) and the measured values ​​of the treated fiber bundle are set as (L1, a1, b1), the result is determined by [(L1-L0)]. 2 +(a1-a0) 2 +(b1-b0) 2 ] 1 / 2 The shading suppression effect is defined and determined according to the following criteria.

[0550] (Evaluation Criteria)

[0551] 5: ΔE *ab ≤5.0

[0552] 4:5.0<ΔE *ab ≤10.0

[0553] 3: 10.0 < ΔE *ab ≤15.0

[0554] 2:15.0<ΔE *ab ≤20.0

[0555] 1:20.0<ΔE *ab

[0556] 8. Fluorescence Imaging Measurement

[0557] Modified regenerated collagen fibers treated with the composition of Example 19 were embedded in resin, then cut, and the exposed surfaces were subjected to fluorescence imaging measurements using a confocal laser microscope (A1RHD25, Nikon Corporation) (excitation wavelength 400 nm, fluorescence detection wavelength 425–475 nm). The results are shown below. Figure 1 .

[0558] [Table 1]

[0559]

[0560] [Table 2]

[0561]

[0562] Examples 16-19 and Comparative Example 4

[0563] Using the composition formulated in Table 3, regenerated collagen fibers were treated and evaluated in various ways as follows. In the presence of an additional fiber treatment agent (agent 3) containing benzoic acid or its salt, after treatment with agent 2, the process was repeated with agent 3 (steps 2) to (steps 5), followed by (step 7).

[0564] <Handling Method>

[0565] (1) Processing method C

[0566] Follow these steps to process regenerated collagen fiber A or regenerated collagen fiber C.

[0567] (Step 1)

[0568] In each embodiment, 10 fiber bundles with a length of 30 cm were made from regenerated collagen fibers (the weight of each bundle was 1.5 g after being dried at 60°C for 1 hour and placed at 20°C and 65%RH for 12 hours).

[0569] First, use the first agent shown in the table to perform the following steps (2) to (5).

[0570] (Step 2)

[0571] Impregnate the fiber bundles with the amount of fiber treatment agent or additional fiber treatment agent that meets the liquor ratio shown in the table (the liquor ratio is calculated based on the dried weight of 1.5g in step 1 above). Impregnate each bundle using a separate container and seal the opening of each container.

[0572] (Step 3)

[0573] Immerse the container together in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set to the temperature shown in the table and let it stand for 5 minutes. After raising the temperature of the liquid in the container to the temperature shown in the table, remove the container from the water bath.

[0574] (Step 4)

[0575] Place the container containing the fiber bundle on the stirring rotor (VMR-5R, AS ONE Corporation) inside a dryer (SOFW-450SB, AS ONE Corporation) set to the temperature shown in the table, and rotate the container at 80 rpm for the heating and stirring time shown in the table.

[0576] (Step 5)

[0577] Remove the container containing the fiber bundles from the dryer and allow it to return to room temperature. Then, remove the fiber bundles from the container, rinse them with 30°C tap water for 30 seconds, and comb them to guide the direction of the hair.

[0578] (Step 6)

[0579] Using the second agent shown in the table, repeat steps (2) to (5).

[0580] (Step 7)

[0581] The fiber bundles are suspended one by one in a dryer set to the temperature recorded in the table. A 250g weight is installed at the lower end of each fiber bundle, and the fibers are dried for the time recorded in the table while the fibers are under tension.

[0582] (Step 8)

[0583] Remove the fiber bundle from the dryer, allow it to return to room temperature, and remove the weights.

[0584] <Evaluation>

[0585] The evaluation was based on the following criteria: “1. Weight gain”, “2. Water resistance” (1) to (3), “3. Thermal shape memory ability”, “4. Fiber swelling rate in water”, “5. Surface feel quality”, “6. Heat resistance” and “7. Inhibition of fiber staining”.

[0586] [Table 3]

[0587]

Claims

1. A method for processing regenerated collagen fibers, wherein, The regenerated collagen fiber treatment method includes the following steps (i). Process (i): A process of immersing regenerated collagen fibers with a water swelling rate of 200% or more, calculated according to the following formula (1), in a fiber treatment agent containing component (A). (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000. Fiber swelling rate in water (%) = [(w1-w2) / w2]×100 (1) In the formula, w1 indicates that 1.0g of fiber was placed in a container filled with 100g of ion-exchanged water, the container was sealed, and the fiber was immersed in a water bath at 40°C for 30 minutes. Afterward, the fiber was removed from the container and centrifuged at 220 ×g for 1 minute to remove water, and the mass of the fiber (in grams) was measured. w2 represents the mass of the fiber measured after placing the fiber with mass w1 on filter paper and drying it at 105°C for 3 hours.

2. The method for treating regenerated collagen fibers as described in claim 1, wherein, The regenerated collagen fiber contains the following component (B). (B) A polyvalent metal, or its salt or complex.

3. The method for treating regenerated collagen fibers as described in claim 2, wherein, Component (B) is aluminum, or its salt or complex.

4. The method for treating regenerated collagen fibers as described in any one of claims 1 to 3, wherein, Prior to step (i), there is a process for manufacturing regenerated collagen fibers, which involves solubilizing insoluble collagen fibers made from the hides of livestock animals, spraying the resulting collagen aqueous solution through a spinning nozzle or slit, and then immersing it in an inorganic salt aqueous solution.

5. A modified regenerated collagen fiber, wherein, The modified regenerated collagen fiber is made by containing component (A) in regenerated collagen fiber. (A) A copolymer comprising structural units derived from unsaturated monomers having a carboxyl group or its salt, and structural units derived from aromatic vinyl compounds, wherein the copolymer has an acid value of 100 mg KOH / g or higher and a weight-average molecular weight of 1500 to 15000.

6. The modified regenerated collagen fiber as described in claim 5, wherein, The content of component (A) is 0.1 to 70% by mass.

7. The modified regenerated collagen fiber as described in claim 5 or 6, wherein, It also contains the following ingredient (B). (B) A polyvalent metal, or its salt or complex.

8. The modified regenerated collagen fiber as described in claim 7, wherein, Component (B) is aluminum, or its salt or complex.

9. A method for manufacturing modified regenerated collagen fibers, wherein, The method includes a step of treating regenerated collagen fibers using the regenerated collagen fiber treatment method according to any one of claims 1 to 4.

10. A method for manufacturing a headdress, wherein, The method includes a step of treating regenerated collagen fibers using the regenerated collagen fiber treatment method according to any one of claims 1 to 4.

11. A headdress product, wherein, The modified regenerated collagen fiber as any one of claims 5 to 8 is a constituent element.

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