Modified regenerated collagen fiber, production method therefor, and headdress product containing the same

Abstract

To provide modified regenerated collagen fibers that improve water resistance and heat resistance, which are points at issue in regenerated collagen fibers, acquire thermal shape memory, improve elasticity (tenacity) and surface feel, and are free from coloring.SOLUTION: Modified regenerated collagen fibers contain the following component (A): benzoic acid or a salt thereof in an amount of 1.0 mass% or more, calculated as benzoic acid, in the regenerated collagen fibers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to regenerated collagen fibers that are given water resistance, heat resistance, and thermal shape memory ability, and more preferably to regenerated collagen fibers used in textile products such as wigs, hair extensions, and other headwear. [Background technology]

[0002] Regenerated collagen fibers generally possess a natural texture and appearance derived from natural materials, unlike synthetic fibers. These regenerated collagen fibers are obtained by solubilizing acid-soluble or insoluble collagen with alkali or enzymes to create a spinning stock, which is then extruded through a spinning nozzle into a coagulation bath to form fibers.

[0003] However, regenerated collagen fibers generally have higher hydrophilicity than synthetic fibers, resulting in a high water absorption rate and extremely low mechanical strength when saturated with water. Consequently, their high water absorption rate significantly reduces their mechanical strength during washing, leading to breakage during subsequent drying and ultimately reducing their suitability as textile products such as headwear.

[0004] Furthermore, regenerated collagen fibers have the problem of low heat resistance. For example, when styling with a hair iron or similar device, if they are styled at the same high temperatures as human hair, they will shrink and become frizzy, spoiling their appearance.

[0005] Furthermore, while plastic synthetic fibers retain their shape after heat setting with an iron, etc., even after subsequent washing (they have thermal shape memory), regenerated collagen fibers lose their shape after a single wash (they lack thermal shape memory). Therefore, they are inferior to conventional plastic synthetic fibers in terms of the degree of freedom in shape setting.

[0006] The points mentioned above have been factors hindering the widespread adoption of regenerated collagen fibers in textile products. The impact of reduced water resistance, specifically the decrease in mechanical strength when wet, was particularly significant. On the other hand, in the field of human hair fibers, a method is known in which a specific aldehyde derivative and a phenol compound are reacted with human hair fibers that do not inherently possess thermal shape memory ability to newly impart thermal shape memory ability (Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-143281 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the manufacturing of textile products, fibers are sometimes stretched strongly, and the technology described in Patent Document 1 sometimes did not result in sufficient elasticity (toughness) of the treated fibers. Therefore, there was a need to improve the elasticity of the treated fibers in order to prevent breakage during stretching. Furthermore, in the technology described in Patent Document 1, the fibers sometimes became discolored.

[0009] Therefore, the present invention relates to a modified regenerated collagen fiber that has improved water resistance and heat resistance, which are problems with regenerated collagen fibers, and is given thermal shape memory ability, as well as having excellent elasticity (toughness) and surface feel, and is also colorless. [Means for solving the problem]

[0010] As a result of diligent research, the inventors have discovered that modified regenerated collagen fibers containing benzoic acid or its salts exhibit strong coordination of the carboxyl groups of the benzoic acid or its salts to the metals (mainly polyvalent metals) within the regenerated collagen fibers. This results in the fiber's interior becoming hydrophobic while preventing the leakage of benzoic acid or its salts from the fibers. Consequently, these modified regenerated collagen fibers exhibit improved water resistance and heat resistance in both dry and wet conditions. Not only can they be shaped by heat setting, but surprisingly, their elasticity (toughness) also improves compared to before treatment, reaching a level close to that of human hair. Furthermore, there is no discoloration associated with the modification process. These findings have led to the completion of the present invention.

[0011] The present invention provides a modified regenerated collagen fiber containing the following component (A) as benzoic acid in an amount of 1.0% by mass or more in the regenerated collagen fiber. (A) Benzoic acid or its salt

[0012] Furthermore, the present invention provides a method for processing regenerated collagen fibers, which includes the following step (i). Step (i) A step of immersing regenerated collagen fibers in a fiber treatment agent containing the following component (A). (A) Benzoic acid or its salt

[0013] Furthermore, the present invention provides a method for producing modified regenerated collagen fibers, which includes a step of treating the regenerated collagen fibers by the above-described regenerated collagen fiber treatment method.

[0014] Furthermore, the present invention provides a method for manufacturing a head ornament product, which includes a step of treating regenerated collagen fibers by the above-described method for treating regenerated collagen fibers.

[0015] Furthermore, the present invention provides a head accessory product that includes the above-mentioned modified regenerated collagen fibers as a component. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide modified regenerated collagen fibers that improve the water resistance and heat resistance, which are problems of regenerated collagen fibers, impart heat shape memory ability, improve stretchability (toughness) and surface feel, and are not colored.

Embodiments for Carrying Out the Invention

[0017] 〔Fibers to be Treated in the Present Invention〕 The fibers to be treated in the fiber treatment of the present invention are fibers artificially produced using collagen-derived polymers or oligomers as raw materials, that is, regenerated collagen fibers using collagen as a raw material.

[0018] Regenerated collagen fibers can be produced by known techniques, and the composition does not have to be 100 % collagen, and natural or synthetic polymers or additives for quality improvement may be included. Furthermore, it may be a post-processed regenerated collagen fiber. As the form of the regenerated collagen fiber, a filament is preferable. Filaments are generally taken out from those wound on a bobbin or in a boxed state. Also, the filaments coming out of the drying process in the production process of the regenerated collagen fiber can be directly used.

[0019] For the raw material of collagen used in the production of regenerated collagen fibers, it is preferable to use the floor skin part. The floor skin is obtained from, for example, fresh floor skin obtained by slaughtering livestock animals such as cows or salted raw skins. These floor skins and the like are mostly composed of insoluble collagen fibers, but are usually used after removing the fleshy parts adhering in a net-like manner and removing the salt content used for preventing spoilage and deterioration.

[0020] These insoluble collagen fibers contain impurities such as lipids including glycerides, phospholipids, and free fatty acids, glycoproteins, and proteins other than collagen such as albumin. These impurities have a significant impact on spinning stability, quality such as luster and strength, and odor during the fiberization process. Therefore, it is preferable to remove these impurities beforehand by, for example, lime-soaking the insoluble collagen fibers to hydrolyze the fat content and loosen the collagen fibers, followed by conventional leather treatments such as acid / alkali treatment, enzyme treatment, and solvent treatment.

[0021] Insoluble collagen that has undergone the above-described treatment is subjected to solubilization treatment in order to cleave the cross-linked peptide portions. As for the solubilization treatment method, commonly used known methods such as alkaline solubilization and enzymatic solubilization can be applied. Furthermore, the alkaline solubilization method and the enzymatic solubilization method may be used in combination.

[0022] When applying the aforementioned alkali solubilization method, it is preferable to neutralize with an acid such as hydrochloric acid. Alternatively, an improved version of the conventionally known alkali solubilization method, as described in Japanese Patent Publication No. 46-15033, may be used.

[0023] The aforementioned enzyme solubilization method has the advantage of being able to obtain solubilized collagen with a uniform molecular weight, and is a method that can be suitably adopted in the present invention. As such an enzyme solubilization method, for example, the method described in Japanese Patent Publication No. 43-25829, Japanese Patent Publication No. 43-27513, etc., can be adopted.

[0024] When collagen that has undergone this solubilization treatment is further subjected to operations such as pH adjustment, salting out, washing with water, and solvent treatment, it is possible to obtain regenerated collagen fibers with superior quality, and therefore it is preferable to perform these treatments.

[0025] The obtained solubilized collagen is dissolved in an acid such as hydrochloric acid, acetic acid, or lactic acid to adjust the collagen aqueous solution to have a pH of 2 to 4.5 and a collagen concentration of 1% by mass or more, preferably 2% by mass or more, and 15% by mass or less, preferably 10% by mass or less. The collagen aqueous solution may be degassed under reduced pressure stirring as needed, or filtered to remove fine debris that is insoluble in water. Furthermore, the collagen aqueous solution may be further mixed with appropriate amounts of additives such as stabilizers and water-soluble polymer compounds as needed, for purposes such as improving mechanical strength, water and heat resistance, gloss, spinnability, preventing discoloration, and preservation.

[0026] The collagen aqueous solution is extruded, for example, through a spinning nozzle or slit, and immersed in an inorganic salt aqueous solution to form regenerated collagen fibers. As the inorganic salt aqueous solution, for example, an aqueous solution of a water-soluble inorganic salt such as sodium sulfate, sodium chloride, or ammonium sulfate is used. Typically, the concentration of the inorganic salt in these inorganic salt aqueous solutions is adjusted to 10 to 40% by mass. The pH of the inorganic salt aqueous solution is preferably 2 or higher, more preferably 4 or higher, preferably 13 or lower, and more preferably 12 or lower. For adjusting this pH, for example, metal salts such as sodium borate or sodium acetate, hydrochloric acid, boric acid, acetic acid, or sodium hydroxide can be used. When the pH of the inorganic salt aqueous solution is within the above range, the peptide bonds of collagen are less susceptible to hydrolysis, making it easier to obtain the desired fibers. The temperature of the inorganic salt aqueous solution is not particularly limited, but it is usually desirable to keep it below 35°C because it prevents denaturation of soluble collagen, does not reduce the strength of the spun fibers, and facilitates the production of stable yarn. The lower limit of the temperature of the inorganic salt aqueous solution is not particularly limited, but it can usually be adjusted appropriately according to the solubility of the inorganic salt.

[0027] The regenerated collagen fibers may be pre-treated (crosslinked) by immersing them in an epoxy compound or a solution thereof. The amount of epoxy compound is preferably 0.1 equivalents or more, more preferably 0.5 equivalents or more, even more preferably 1 equivalent or more, and preferably 500 equivalents or less, more preferably 100 equivalents or less, and even more preferably 50 equivalents or less, relative to the amount of amino groups in the regenerated collagen fibers that can react with the epoxy compound, as measured by amino acid analysis. The amount of epoxy compound being within the above range is preferable in terms of industrial handling and environmental friendliness, as it sufficiently imparts a water-insolubilizing effect to the regenerated collagen fibers.

[0028] Epoxy compounds can be used as is or dissolved in various solvents. Examples of solvents include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; ethers such as tetrahydrofuran and dioxane; halogenated organic solvents such as dichloromethane, chloroform, and carbon tetrachloride; and neutral organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). These solvents may be used individually or in mixtures of two or more. When water is used as a solvent, aqueous solutions of inorganic salts such as sodium sulfate, sodium chloride, and ammonium sulfate may be used as needed. Typically, the concentration of the inorganic salt in the aqueous solution is adjusted to 10-40% by mass. The pH of the aqueous solution may also be adjusted using metal salts such as sodium borate and sodium acetate, or hydrochloric acid, boric acid, acetic acid, or sodium hydroxide. In this case, the pH of the aqueous solution is preferably 6 or higher, more preferably 8 or higher, from the viewpoint of ensuring that the reaction between the epoxy group of the epoxy compound and the amino group of collagen is not slowed down and that insolubilization in water is sufficient. Furthermore, since the pH of aqueous solutions of inorganic salts tends to decrease over time, a buffer may be used if necessary.

[0029] From the viewpoint of preventing the regenerated collagen fibers from denature, maintaining the strength of the resulting fibers, and facilitating the stable production of yarn, the treatment temperature of the regenerated collagen fibers with the epoxy compound is preferably 50°C or lower.

[0030] The regenerated collagen fibers may then be washed, oiled, and dried. Washing can be done, for example, by running water for 10 minutes to 4 hours. As the oiling agent, for example, an emulsion of amino-modified silicone, epoxy-modified silicone, polyether-modified silicone, and a Pluronic-type polyether-based antistatic agent can be used. The drying temperature is preferably 100°C or lower, more preferably 75°C or lower.

[0031] From the viewpoint of improving water resistance, the regenerated collagen fibers to be treated are preferably those containing polyvalent metals, their salts, or complexes. Examples of polyvalent metals include calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoint of improving water resistance, reducing discoloration of the fibers, reducing environmental impact, and improving economic efficiency, aluminum, zirconium, and titanium are preferably used, and aluminum is more preferably used. From the viewpoint of improving water resistance, the content of polyvalent metals, their salts, or complexes in the regenerated collagen fibers is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, as a metal element amount. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less. In other words, the content of polyvalent metals, or their salts or complexes, in the regenerated collagen fibers to be processed is, from the above viewpoint, preferably 1.0 to 40% by mass, more preferably 2.0 to 30% by mass, even more preferably 3.0 to 20% by mass, and even more preferably 5.0 to 10% by mass, as the amount of metal elements.

[0032] [Fiber processing method] (Basic procedures) The fiber processing method of the present invention includes the following step (i), which improves the water resistance and heat resistance, which are problems of regenerated collagen fibers, imparts thermal shape memory ability, and also improves elasticity (toughness) and surface feel, and produces modified regenerated collagen fibers that are free of discoloration. Step (i) A step of immersing regenerated collagen fibers in a fiber treatment agent containing the following component (A). (A) Benzoic acid or its salt

[0033] The content of component (A) in the fiber treatment agent used in step (i) varies depending on the pH range of the fiber treatment agent, but the range shown below is preferred.

[0034] When the pH of the fiber treatment agent is 2.0 or higher and less than 6.5, from the viewpoint of imparting high shape retention, water resistance, elasticity (toughness, i.e., high elongation at break when the fiber is tensile) and heat resistance to the modified and regenerated collagen fibers after treatment, the content of component (A) in the fiber treatment agent is preferably 0.8% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more as benzoic acid. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% 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. In other words, when the pH of the fiber treatment agent is 2.0 or higher and less than 6.5, the content of component (A) in the fiber treatment agent is, from the above viewpoint, preferably 0.8 to 90% by mass, more preferably 3.0 to 80% by mass, even more preferably 5.0 to 70% by mass, even more preferably 10 to 50% by mass, even more preferably 15 to 40% by mass, and even more preferably 20 to 35% by mass, as benzoic acid.

[0035] Furthermore, when the pH of the fiber treatment agent is 6.5 or higher and 11.0 or lower, from the viewpoint of imparting high shape retention, water resistance, elasticity (toughness, i.e., high elongation at break when the fiber is tensile) and heat resistance to the modified and regenerated collagen fibers after treatment, the content of component (A) in the fiber treatment agent is preferably 0.8% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, even more preferably 26% by mass or more, even more preferably 28% by mass or more, and even more preferably 30% by mass or more, and from the viewpoint of improving the feel of the fiber surface, it is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less. In other words, when the pH of the fiber treatment agent is 6.5 or higher and 11.0 or lower, the content of component (A) in the fiber treatment agent is, from the above viewpoint, preferably 0.8 to 90% by mass, more preferably 3.0 to 80% by mass, even more preferably 5.0 to 70% by mass, even more preferably 10 to 70% by mass, even more preferably 15 to 50% by mass, even more preferably 20 to 50% by mass, even more preferably 25 to 45% by mass, even more preferably 26 to 45% by mass, even more preferably 28 to 40% by mass, and even more preferably 30 to 40% by mass, as benzoic acid.

[0036] The fiber treatment agent used in step (i) uses water as a medium. The water content in the fiber treatment agent is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and also preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. In other words, the water content in the fiber treatment agent is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, even more preferably 30 to 85% by mass, and even more preferably 40 to 85% by mass.

[0037] The pH of the fiber treatment agent used in step (i) is preferably 2.0 or higher, more preferably 3.0 or higher, even more preferably 3.5 or higher, even more preferably 4.0 or higher, and also preferably 11.0 or lower, more preferably 10.0 or lower, and even more preferably 9.0 or lower, from the viewpoint of suppressing damage to regenerated collagen fibers and improving durability. Note that the pH values ​​in this invention are those at 25°C. In other words, the pH of the fiber treatment agent is preferably 2.0 to 11.0, more preferably 3.0 to 10.0, even more preferably 3.5 to 9.0, and even more preferably 4.0 to 9.0, from the viewpoint of suppressing damage to regenerated collagen fibers and improving their durability.

[0038] In step (i), the regenerated collagen fibers to be subjected to fiber treatment may be dry or wet. For example, they may be treated directly in the state before drying during the production of the regenerated collagen fibers. The amount of fiber treatment agent used to immerse the regenerated collagen fibers is preferably 2.0 or more, more preferably 3.0 or more, even more preferably 5.0 or more, even more preferably 10 or more, even more preferably 20 or more, and also preferably 500 or less, more preferably 250 or less, and even more preferably 100 or less, in terms of the bath ratio (mass of fiber treatment agent / mass of regenerated collagen fibers) to the mass of the regenerated collagen fibers. In other words, the bath ratio is preferably 2.0 to 500, more preferably 3.0 to 250, even more preferably 5.0 to 100, even more preferably 10 to 100, and even more preferably 20 to 100.

[0039] Furthermore, in step (i), the regenerated collagen fibers may be fixed in advance with a curler or the like, and then subjected to the fiber treatment of the present invention under heating. By doing so, the regenerated collagen fibers can be given thermal shape memory ability, high durability, and the desired shape simultaneously.

[0040] In step (i), the immersion of regenerated collagen fibers into the fiber treatment agent is preferably carried out under heating, and this heating is performed by warming the fiber treatment agent. This heating may be carried out by immersing the regenerated collagen fibers in a heated fiber treatment agent, or by immersing the regenerated collagen fibers in a low-temperature fiber treatment agent and then heating it. The temperature of the fiber treatment agent is preferably 20°C or higher, more preferably 35°C or higher, and even more preferably 45°C or higher, in order to obtain the effects of the present invention by increasing the interaction between component (A) and the fiber constituent molecules in the regenerated collagen fibers, such as protein molecules. Furthermore, in order to prevent the regenerated collagen fibers from denature and degrading due to heat, the temperature is preferably less than 100°C, more preferably 80°C or lower, even more preferably 70°C or lower, and even more preferably 60°C or lower.

[0041] The immersion time in step (i) is adjusted as appropriate depending on the heating temperature, but for example, from the viewpoint of exhibiting an effect of improving the elasticity of the regenerated collagen fibers, it is preferably 15 minutes or more, more preferably 30 minutes or more, and even more preferably 1 hour or more, and in order to suppress damage to the regenerated collagen fibers, it is preferably 48 hours or less, more preferably 24 hours or less, and even more preferably 12 hours or less.

[0042] Step (i) is preferably carried out in an environment in which the evaporation of moisture is suppressed. Specific means of suppressing the evaporation of moisture include covering the container of the fiber treatment agent in which the regenerated collagen fibers are immersed with a film-like substance, cap, lid, etc., made of a material that does not allow water vapor to pass through.

[0043] After step (i), the regenerated collagen fibers may be rinsed, or they may not be rinsed. However, rinsing is preferable from the viewpoint of preventing a decrease in the feel of the surface of the regenerated collagen fibers due to excess component (A).

[0044] It is believed that the processing in step (i) causes component (A) to penetrate into the regenerated collagen fibers and strongly coordinate with metals, such as polyvalent metals, within the fibers, thereby producing various effects. In other words, the regenerated collagen fiber processing method including step (i) can produce modified regenerated collagen fibers containing component (A) within the fibers. The resulting modified regenerated collagen fibers can be shaped by heat setting, and exhibit excellent water resistance, heat resistance, and tensile modulus, resulting in fibers with significantly improved elasticity (toughness) compared to regenerated collagen fibers.

[0045] [Modified and regenerated collagen fiber] The modified regenerated collagen fibers of the present invention obtained by the above method will be described below.

[0046] (Component (A): Benzoic acid or its salt) The modified regenerated collagen fiber of the present invention contains benzoic acid or a salt thereof as component (A). Examples of cases where component (A) is a salt include alkali metal salts such as sodium salts and potassium salts.

[0047] From the viewpoint of having higher shape retention, water resistance and heat resistance, the content of component (A) in the modified regenerated collagen fiber of the present invention is 1.0% by mass or more, preferably 5.0% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, and even more preferably 15% by mass or more, as benzoic acid. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. In other words, from the above viewpoint, the content of component (A) in the modified regenerated collagen fiber of the present invention is preferably 1.0 to 50% by mass, more preferably 5.0 to 40% by mass, even more preferably 10 to 40% by mass, even more preferably 12 to 40% by mass, and even more preferably 15 to 30% by mass, as benzoic acid.

[0048] (Component (B): Polyvalent metal, or its salt or complex) The modified regenerated collagen fibers of the present invention preferably further contain (B) a polyvalent metal, or a salt thereof or a complex thereof, from the viewpoint of improving water resistance. Examples of polyvalent metals include calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoint of improving water resistance, reducing discoloration of the fibers, reducing environmental impact, and improving economic efficiency, aluminum, zirconium, and titanium are preferably used, and aluminum is more preferably used. Any of these can be used individually or in combination of two or more.

[0049] From the viewpoint of improving water resistance, the content of component (B) in the modified regenerated collagen fiber of the present invention is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, and even more preferably 5.0% by mass or more, as a metal element amount. Furthermore, from the viewpoint of improving the feel of the fiber surface, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 7.0% by mass or less. In other words, from the above viewpoint, the content of component (B) in the modified regenerated collagen fiber of the present invention is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass, even more preferably 1.0 to 20% by mass, even more preferably 2.0 to 10% by mass, and even more preferably 5.0 to 7.0% by mass, as a metal element amount.

[0050] The content of component (B) as a metal element in the modified regenerated collagen fiber of the present invention (component (B)) 金属元素量 The content of component (A) as benzoic acid relative to (component (A)) 安息香酸量 ) Mass ratio (component (A) 安息香酸量 ) / (Component (B) 金属元素量From the viewpoint of having higher shape retention, water resistance and heat resistance, the value is preferably 0.025 or higher, more preferably 0.2 or higher, even more preferably 0.5 or higher, even more preferably 1.0 or higher, even more preferably 2.0 or higher, and even more preferably 2.5 or higher. Furthermore, from the viewpoint of having high durability and improving the feel of the fiber surface, the value is preferably 100 or lower, more preferably 50 or lower, even more preferably 20 or lower, even more preferably 10 or lower, even more preferably 8 or lower, even more preferably 6 or lower, and even more preferably 4 or lower. In other words, in the modified regenerated collagen fiber of the present invention, the mass ratio (component (A) 安息香酸量 ) / (Component (B) 金属元素量 From the above viewpoint, the value is preferably 0.025 to 100, more preferably 0.2 to 50, even more preferably 0.5 to 20, even more preferably 1.0 to 10, even more preferably 2.0 to 8, even more preferably 2.5 to 6, and even more preferably 2.5 to 4.

[0051] The modified regenerated collagen fiber of the present invention can be shaped by heat setting, has excellent water resistance, heat resistance, and tensile modulus, and is a fiber that greatly improves the elasticity (toughness) of regenerated collagen fiber. Therefore, the modified regenerated collagen fiber of the present invention can be suitably used as a fiber for headwear products, and various headwear products can be manufactured using this fiber. Suitable headwear products in this invention include, for example, hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories, doll hair, and the like.

[0052] The modified regenerated collagen fiber of the present invention may be used alone as a headwear product, or it may be mixed with other fibers to form a headwear product. The other fibers can be any fiber that can be used in a headwear product, and are not particularly limited. Examples of other fibers include polyester fibers, human hair, animal hair, polyvinyl chloride fibers, modacrylic fibers, polyamide fibers, polyolefin fibers, etc. Among these, polyester fibers are preferred from the viewpoint of excellent heat resistance, flame retardancy, and curl retention, and flame-retardant polyester fibers are more preferred.

[0053] The flame-retardant polyester fiber is not particularly limited, but from the viewpoint of flame retardancy, it is preferable to include 5 to 40 parts by mass of a brominated epoxy flame retardant per 100 parts by mass of one or more polyester resins selected from the group consisting of polyalkylene terephthalate and copolymer polyesters mainly composed of polyalkylene terephthalate. In the present invention, "mainly composed of" means that it is contained in an amount of 50 mol% or more, and "copolymer polyester mainly composed of polyalkylene terephthalate" means a copolymer polyester containing 50 mol% or more of polyalkylene terephthalate. Preferably, the "copolymer polyester mainly composed of polyalkylene terephthalate" contains 60 mol% or more of polyalkylene terephthalate, more preferably 70 mol% or more, and even more preferably 80 mol% or more. The flame-retardant polyester fiber is further preferably composed of 0 to 5 parts by mass of an antimony compound per 100 parts by mass of polyester resin. The inclusion of an antimony compound improves the flame retardancy of the polyester fiber.

[0054] With respect to the embodiments described above, preferred embodiments of the present invention are further disclosed below.

[0055] <1> Modified regenerated collagen fiber containing the following component (A) as benzoic acid in an amount of 1.0% by mass or more. (A) Benzoic acid or its salt

[0056] <2> The content of component (A) is preferably 5.0% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, even more preferably 15% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. <1> Modified and regenerated collagen fibers as described above.

[0057] <3> Preferably, it further contains the following component (B) <1> or <2> Modified and regenerated collagen fibers as described above. (B) Polyvalent metals, or their salts or complexes

[0058] <4> Component (B) is preferably one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or their salts or complexes; more preferably one or more polyvalent metals selected from aluminum, zirconium, and titanium, or their salts or complexes; even more preferably aluminum or its salts or complexes. <3> Modified and regenerated collagen fibers as described above.

[0059] <5> The content of component (B) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, even more preferably 5.0% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 7.0% by mass or less. <3> or <4> Modified and regenerated collagen fibers as described above.

[0060] <6> The mass ratio of the benzoic acid content of component (A) to the metallic element content of component (B) (component (A)) 安息香酸量 ) / (Component (B) 金属元素量) is preferably 0.025 or higher, more preferably 0.2 or higher, even more preferably 0.5 or higher, even more preferably 1.0 or higher, even more preferably 2.0 or higher, even more preferably 2.5 or higher, and also preferably 100 or less, more preferably 50 or less, even more preferably 20 or less, even more preferably 10 or less, even more preferably 8 or less, even more preferably 6 or less, and even more preferably 4 or less. <1> ~ <5> Modified regenerated collagen fiber as described in any one of the items.

[0061] <7> A method for processing regenerated collagen fibers, including the following step (i). Step (i) A step of immersing regenerated collagen fibers in a fiber treatment agent containing the following component (A). (A) Benzoic acid or its salt

[0062] <8> Prior to step (i), the process includes a step for producing regenerated collagen fibers, in which an aqueous solution of solubilized collagen obtained by solubilizing insoluble collagen fibers made from the hides of livestock animals is extruded through a spinning nozzle or slit and immersed in an aqueous solution of inorganic salts. <7> The method for processing regenerated collagen fibers as described above.

[0063] <9> Preferably, after the regenerated collagen fiber manufacturing step, the process includes a crosslinking step in which the regenerated collagen fiber is immersed in an epoxy compound or a solution thereof. <8> The method for processing regenerated collagen fibers as described above.

[0064] <10> The regenerated collagen fiber contains the following component (B): <7> ~ <9> A method for processing regenerated collagen fibers as described in any one of the items. (B) Polyvalent metals, or their salts or complexes

[0065] <11> Component (B) is preferably one or more polyvalent metals selected from calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or their salts or complexes; more preferably one or more polyvalent metals selected from aluminum, zirconium, and titanium, or their salts or complexes; even more preferably aluminum or its salts or complexes. <10> The method for processing regenerated collagen fibers as described above.

[0066] <12> The pH of the fiber treatment agent used in step (i) at 25°C is preferably 2.0 or higher, more preferably 3.0 or higher, even more preferably 3.5 or higher, even more preferably 4.0 or higher, and also preferably 11.0 or lower, more preferably 10.0 or lower, and even more preferably 9.0 or lower. <7> ~ <11> A method for processing regenerated collagen fibers as described in any one of the items.

[0067] <13> The pH of the fiber treatment agent used in step (i) is 2.0 or higher and less than 6.5, and the content of component (A) in the fiber treatment agent is preferably 0.8% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, and also preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% 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. <7> ~ <12> A method for processing regenerated collagen fibers as described in any one of the items.

[0068] <14> The pH of the fiber treatment agent used in step (i) is 6.5 or higher and 11.0 or lower, and the content of component (A) in the fiber treatment agent is preferably 0.8% by mass or more, more preferably 3.0% by mass or more, even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, even more preferably 26% by mass or more, even more preferably 28% by mass or more, even more preferably 30% by mass or more, and also preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less. <7> ~ <12> A method for processing regenerated collagen fibers as described in any one of the items.

[0069] <15> The fiber treatment agent used in step (i) is water-based, and the water content in the fiber treatment agent is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and also preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. <7> ~ <14> A method for processing regenerated collagen fibers as described in any one of the items.

[0070] <16> In step (i), the amount of fiber treatment agent used to immerse the regenerated collagen fibers is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, even more preferably 10 or more, even more preferably 20 or more, and also preferably 500 or less, more preferably 250 or less, and even more preferably 100 or less, in terms of the bath ratio (mass of fiber treatment agent / mass of regenerated collagen fibers) to the mass of the regenerated collagen fibers. <7> ~ <15> A method for processing regenerated collagen fibers as described in any one of the items.

[0071] <17> The temperature of the fiber treatment agent in which the regenerated collagen fibers are immersed in step (i) is preferably 20°C or higher, more preferably 35°C or higher, even more preferably 45°C or higher, and also preferably less than 100°C, more preferably 80°C or lower, even more preferably 70°C or lower, and even more preferably 60°C or lower. <7> ~ <16> A method for processing regenerated collagen fibers as described in any one of the items.

[0072] <18> The immersion time in step (i) is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and also preferably 48 hours or less, more preferably 24 hours or less, and even more preferably 12 hours or less. <7> ~ <17> A method for processing regenerated collagen fibers as described in any one of the items.

[0073] <19> Preferably, step (i) is carried out in an environment in which the evaporation of moisture is suppressed. <7> ~ <18> A method for processing regenerated collagen fibers as described in any one of the items.

[0074] <20> <7> ~ <19> A method for producing modified regenerated collagen fibers, comprising the step of treating regenerated collagen fibers by the regenerated collagen fiber treatment method described in any one of the items.

[0075] <21> <7> ~ <19> A method for manufacturing a head ornament product, comprising the step of treating regenerated collagen fibers by the regenerated collagen fiber treatment method described in any one of the items.

[0076] <22> <1> ~ <6> A head accessory product containing modified and regenerated collagen fibers as a component, as described in any one of the items.

[0077] <23> Choose from hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories, and doll hair. <22> Headwear products as described above. [Examples]

[0078] Examples 1-11, Comparative Examples 1-3 The compositions shown in Table 1 were used to treat regenerated collagen fibers according to the method described below, and various evaluations were performed. The pH of each composition was measured directly using a pH meter (HORIBA F-52) at room temperature (25°C) after preparation.

[0079] <Processing method> 1. A 22cm long bundle of 0.50g of regenerated collagen fiber (*) was immersed in a container containing the amount of fiber treatment agent shown in the bath ratio in the table. The container was then sealed and the container was immersed in a water bath at the temperature shown in the table (manufacturer: Toyo Seisakusho Co., Ltd. / model number: TBS221FA) and heated for the time shown in the table. * Kaneka Corporation's regenerated collagen fibers were purchased in the form of commercially available hair extension products, and the fibers were cut and divided into small bundles for evaluation. For this evaluation, the extension products used were those labeled as using 100% Ultima fiber, with a color count of 30 (white) and a straight shape. 2. Remove the container containing the hair bundles from the water bath and allow them to return to room temperature. 3. Remove the hair strands from the container, rinse with 30°C running tap water for 30 seconds, lather with the evaluation shampoo for 60 seconds, rinse with 30°C running tap water for 30 seconds, lightly towel dry, and then dry the hair strands with a warm air dryer (Tescom Nobby White NB3000) while combing.

[0080] <Formula for the evaluation shampoo> Ingredients (mass%) Sodium laureth sulfate 15.5 Lauramide DEA 1.5 EDTA-2Na 0.3 Amount of phosphoric acid to adjust pH to 7 Ion-exchanged water Balance Total 100

[0081] <Increase in average elongation at break during fiber tension> As an indicator of water resistance and elasticity (toughness) when fibers are stretched, the average elongation at break, that is, the percentage of the original fiber length at which break occurs when the fiber is stretched under tension, was evaluated using the average value obtained from multiple fibers (10 fibers). The evaluation was performed using hair bundles immediately after being treated with the above <treatment method>, following the procedure below. 1. Ten fibers were cut from the base of the hair bundle. A 3cm fiber piece was taken from the middle of the base and tip of each fiber, resulting in a total of 10 3cm hair pieces. 2. The fiber samples were placed in a DIA-STRON limited "MTT690 Automatic Fiber Tensile Tester". After being left immersed in water for 30 minutes, automatic measurement was started, and the average elongation at break while the fibers were immersed in water was determined. A higher value indicates greater elasticity, superior toughness, and superior durability. According to the following formula, the average elongation at break (A%) when fibers are pulled in their untreated state (untreated; Comparative Example 1) is used as the baseline. The table shows the percentage increase (C%) in the average elongation at break (B%) of treated hair bundles compared to the untreated state, as indicated in "Percentage increase in average elongation at break [%]". C(%) = B(%) - A(%)

[0082] <Increase in average breaking load during fiber tension> As an indicator of water resistance during fiber tensile stress, the average breaking load during fiber tensile stress was used. The evaluation was performed using fiber bundles immediately after treatment using the above-described <treatment method>. Furthermore, the average value obtained when evaluating multiple fibers (10 fibers) was used as the numerical value. The evaluation was performed according to the following procedure. 1. Ten fibers were cut from the base of the hair bundle. A 3cm fiber piece was taken from the middle of the base and tip of each fiber, resulting in a total of 10 3cm hair pieces. 2. The fiber samples were placed in a DIA-STRON limited "MTT690 Automatic Fiber Tensile Testing Machine". After being left immersed in water for 30 minutes, automatic measurement was started, and the breaking load when the fiber was stretched while immersed in water was determined. A higher value indicates greater stiffness and resilience, greater resistance to stretching by external forces, and superior durability. According to the following formula, based on the average breaking load (W0 (gf)) during fiber tension in the as-cut state (untreated; Comparative Example 1) from commercially available products, the increase in the average breaking load (W1 (gf)) of the tuft after treatment compared to the untreated state was described in the table as "Increase in average breaking load during fiber tension [gf]" in terms of how much (Y (gf)) it increased. Y (gf) = W1 (gf) - W0 (gf)

[0083] <Shrinkage rate during high-temperature iron setting> As an index of heat resistance, the shrinkage rate during high-temperature iron setting was used. The evaluation was performed using the tuft immediately after being treated by the above <Treatment method>. Also, as the numerical value, the average value when evaluating with a plurality of (5) fibers was used. The evaluation was performed according to the following procedure. 1. Five fibers were cut from the root of the tuft immediately after being treated by the above <Treatment method> and marked. The lengths of these five treated fibers were measured, and the average value was recorded (designated as length L1). Then, these five marked treated fibers were bundled together so as to be sandwiched between two tufts (total 1 g) of 0.5 g of untreated regenerated collagen fibers prepared separately to create a new tuft (hereinafter referred to as a large tuft), and a flat iron set at 180 °C (manufactured by Miki Electric Industry Co., Ltd. / Model number: AHI-938) was applied to the entire large tuft three times at a speed of 5 cm / sec. 2. After the ironing operation, the five marked treated fibers were taken out from the large tuft, and the lengths of each of these five marked treated fibers were measured again and the average value was recorded (designated as length L2). 3. Shrinkage rate S during high-temperature iron setting dry = {1 - (L2 / L1)} x 100 [%] was defined. The closer S dry is to 0%, the less likely shrinkage due to dry heat occurs, indicating excellent heat resistance.

[0084] <Shrinkage rate during hot water heating> As an index of water resistance and heat resistance, the shrinkage rate during hot water heating was used. The evaluation was performed using the tuft immediately after being treated by the above <Treatment method>. Also, as the numerical value, the average value when evaluating with a plurality of (5) fibers was used. The evaluation was performed according to the following procedure. 1. Five fibers were cut from the base of the hair bundle, the average length of each fiber was recorded (referred to as length L1), and then the bundle was immersed in a 90°C water bath (manufacturer: Toyo Seisakusho Co., Ltd. / model number: TBS221FA) and heated for 1 minute. 2. After the heating process, five fibers were removed, lightly dried with a towel, and dried at room temperature and humidity for 30 minutes. The average length of each fiber was then recorded (denoted as length L2). 3. Shrinkage rate (S) during hot water heating wet We defined it as = { 1 - (L2 / L1)} x 100 [%]. wet The closer the value is to 0%, the less likely shrinkage due to moist heat is to occur, indicating superior heat resistance.

[0085] <Thermal shape memory ability> The thermal shape memory ability was evaluated using hair bundles immediately after being treated with the above-described processing method. If the result of "I: Shape imparting (curl)" was 5% or less, it was considered to have no effect, and no further processing or evaluation was performed. • I: Shaping (curling) 1. A 22cm long bundle of 0.5g of regenerated collagen fiber was wet with 30°C tap water for 30 seconds, then the wet bundle was wrapped around a 14mm diameter plastic rod and secured with a clip. 2. The hair bundles wrapped around the rod were immersed in a 60°C water bath (manufacturer: Toyo Seisakusho Co., Ltd. / model number: TBS221FA) and heated for 1 minute. 3. Remove the hair bundles from the water bath, immerse them in 25°C water for 1 minute, remove them from the water, and allow them to return to room temperature. 4. Remove the hair bundle from the rod, comb it through three times, and then, three minutes after taking it out of the water, take a picture of it hanging from the side.

[0086] (Evaluation Criteria) Let L0 be the length of the untreated hair bundle (22 cm) and L be the length of the treated hair bundle. The curl-up rate = hair bundle length reduction rate (I) (%), calculated according to the following formula, was defined as the curl strength. I = [(L0 - L) / L0] × 100

[0087] • II: Reshaping (Straight) 1. After detangling the hair strands evaluated in step I with a comb, a flat iron (manufactured by Miki Electric Industry Co., Ltd. / model number: AHI-938) set to 180°C was slid through them 6 times at a speed of 5 cm / sec. 2. Rinse with running tap water at 30°C for 30 seconds, lather with the evaluation shampoo for 60 seconds, rinse with running tap water at 30°C for 30 seconds, and towel dry. 3. The items were hung up and air-dried at 20°C and 65% RH for 12 hours. After combing them through, they were visually inspected from the side while still hanging.

[0088] (Evaluation Criteria) The straightening rate (ST) (%), calculated according to the following formula, is defined as the degree of straightening achieved, with the untreated hair bundle length being L0 (22 cm) and the treated hair bundle length being L. When ST = 100%, the hair bundle is completely straightened. ST = [1 - (L0 - L) / L0] × 100

[0089] • III: Reshaping (curling) 1.II The hair bundles evaluated were wet with 30°C tap water for 30 seconds, then the wet hair bundles were wrapped around a 14mm diameter plastic rod and secured with a clip. 2. The hair bundles wrapped around the rod were immersed in a 60°C water bath (manufacturer: Toyo Seisakusho Co., Ltd. / model number: TBS221FA) and heated for 1 minute. 3. Remove the hair bundles from the water bath, immerse them in 25°C water for 1 minute, remove them from the water, and allow them to return to room temperature. 4. Remove the hair bundle from the rod, comb it through three times, and then, three minutes after taking it out of the water, take a picture of it hanging from the side.

[0090] (Evaluation Criteria) Let L0 be the length of the untreated hair bundle (22 cm) and L be the length of the treated hair bundle. The curl-up rate = hair bundle length reduction rate (I) (%), calculated according to the following formula, was defined as the curl strength. I = [(L0 - L) / L0] × 100

[0091] <Good surface texture> The surface texture was evaluated using hair strands immediately after treatment using the <treatment method>. Five expert panelists evaluated the smoothness of the texture when touched by hand according to the following criteria, and the sum of the five evaluations was used as the final result. (Evaluation Criteria) 5: It has an extremely smooth texture compared to untreated fibers (Comparative Example 1). 4: It has a smoother feel compared to untreated fibers (Comparative Example 1). 3: It has a slightly smoother texture compared to the untreated fibers (Comparative Example 1). 2: The texture is the same as the untreated fiber (Comparative Example 1). 1: It is rougher and has a less pleasant feel than untreated fibers (Comparative Example 1).

[0092] <Suppression of discoloration of fibers> 1. For both the front and back of each hair strand, the color was measured near the root, mid-length, and tip using a colorimeter (Konica Minolta CR-400), and the average of the six points was used as the color value (L, a, b). 2. The degree of coloring was evaluated using ΔE*ab, with untreated hair strands of color no. 30 white (*) (Comparative Example 1) as the baseline. Color measurements were taken on the same day the treatment was performed. (*) Untreated hair bundles of color number 30 white We purchased Kaneka Corporation's regenerated collagen fibers in the form of commercially available hair extension products, cut the fibers from them, and divided them into small bundles for evaluation. For this evaluation, we used extension products that were labeled as using 100% Ultima fiber, with a color count of 30 (white) and a straight shape. Furthermore, these Kaneka-manufactured regenerated collagen fibers contain aluminum, and the aluminum content, as determined by the aforementioned analytical method, was 6.8% by mass in all cases. ΔE*ab is calculated by taking the measurements of an untreated hair bundle with color number 30 white as (L0, a0, b0) and the measurements of a treated hair bundle as (L1, a1, b1), where (L1-L0) 2 +(a1-a0) 2+(b1-b0) 2 ] 1 / 2 The color-inhibiting effect was determined according to the following criteria, as defined by [the formula]. 5:ΔE*ab ≤ 5.0 4:5.0 < ΔE*ab ≤ 10.0 3:10.0 < ΔE*ab ≤ 15.0 2:15.0 < ΔE*ab ≤ 20.0 1:20.0< ΔE*ab

[0093] <Quantitative determination of benzoic acid> The amount of benzoic acid contained in the regenerated collagen fibers after processing was quantified by the following method and listed in the table as "Component (A)". 安息香酸量 This was shown as "[...] (Measurements were not taken for Comparative Examples 2 and 3). ·reagent 6N hydrochloric acid: titration solution for volumetric analysis, manufactured by Kanto Chemical Co., Ltd. Sodium acetate: Special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Acetic acid: Special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Acetonitrile: For LC / MS, manufactured by Kanto Chemical Co., Ltd. Sodium benzoate: Special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Ultrapure water: MilliQ ultrapure water produced by Millipore. ·Quantitative method The sample was finely chopped, approximately 10 mg was accurately weighed, 3 mL of 6N hydrochloric acid was added, and the mixture was heated and dissolved at 50°C for 15 hours. After cooling, the solution was filtered and used as the sample solution. Separately, sodium benzoate was dissolved in the mobile phase and prepared to a concentration of 0.1 to 100 μg / mL of benzoic acid, which was used as the standard solution for constructing the calibration curve. The sample solution and standard solution were tested by liquid chromatography, and the peak areas of the sample solution and the standard solution were measured. • Measurement conditions Detector: UV-Vis spectrophotometer Measurement wavelength: 230nm Column: A stainless steel tube with an inner diameter of 21 mm and a length of 150 mm was packed with 5 μm octadecylsilylated silica gel for liquid chromatography. Column temperature: Constant temperature around 40°C Mobile phase: Approximately 0.68 g of sodium acetate and 0.91 g of acetic acid were dissolved in 750 mL of ultrapure water, and then 250 mL of acetonitrile was added and mixed. ·HPLC / UV conditions Equipment: UltiMate3000 system (manufactured by Thermo Fisher Scientific) Column: L column 2 ODS 5μm 2.1×150mm (Chemicals Evaluation and Research Institute) Column temperature: 40℃ Mobile phase: 20 mM ammonium acetate 25% acetonitrile buffer Analysis time: 10 minutes Detector: DAD (Diode Array Detector) Detection wavelength: 230nm Flow rate: 0.3 mL / min (isocratic elution) Injection volume: 10μL

[0094] <Method for determining aluminum content> The amount of aluminum contained in the regenerated collagen fibers after processing was quantified by the following method and recorded in the table as "Component (B)". Al量 This was shown as "[...] (Measurements were not taken for Comparative Examples 2 and 3). ·reagent Sulfuric acid: For precision analysis, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Hydrochloric acid: For metal analysis, manufactured by Kanto Chemical Co., Ltd. Sodium carbonate: Special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Boric acid: Special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Aluminum standard solution: 1000 mg / L for atomic absorption spectrometry, manufactured by Kanto Chemical Co., Ltd. Ultrapure water: MilliQ ultrapure water produced by Millipore. • Sample pretreatment method 0.1 g of the sample was accurately weighed into a platinum crucible and heated until no more white smoke was produced. A few drops of sulfuric acid were then added, and the mixture was heated again until no more white smoke was produced. The mixture was then thoroughly ashed in an electric furnace at 550°C. Subsequently, 1 g of alkaline flux (sodium carbonate:boric acid = 1:0.4) was added and the mixture was melted in an electric furnace at 950°C. A watch glass was placed over the melted mixture, and 5 mL of ultrapure water and hydrochloric acid (6 mol / L) were added. The mixture was heated and dissolved on a hot plate at 70-80°C, and after cooling, the volume was adjusted to 50 mL with ultrapure water to obtain the measurement solution. • Preparation of calibration curve solution Calibration curve solutions ranging from 0.1 to 20 mg / L were prepared using an aluminum standard solution (1000 mg / L). Alkaline flux and hydrochloric acid were added to each solution to a concentration similar to that of the sample. ·measurement The prepared samples were subjected to elemental measurements using an ICP emission spectrometer under the following conditions. Analytical instrument: iCAP6500Duo (manufactured by Thermo Fisher Scientific) Wavelength: Al 396.152nm RF Power: 1150W Coolant gas flow rate: 12 L / min Nebulizer flow rate: 0.70 L / min Auxiliary gas: 0.5 L / min Pump flow rate: 50 rpm

[0095] [Table 1]

[0096] Furthermore, the hair bundles processed in the above embodiments can all be used as extensions by securing them to the hair with pins or the like, and can perform adequately on a human head.

Claims

1. Modified regenerated collagen fiber containing the following component (A) as benzoic acid in an amount of 1.0% by mass or more. (A) Benzoic acid or its salt

2. The modified regenerated collagen fiber according to claim 1, wherein the content of component (A) is 1.0 to 50% by mass as benzoic acid.

3. The modified regenerated collagen fiber according to claim 1, wherein the content of component (A) is 5.0 to 40% by mass as benzoic acid.

4. Furthermore, the modified regenerated collagen fiber according to any one of claims 1 to 3 contains the following component (B). (B) Polyvalent metals, or their salts or complexes

5. The modified regenerated collagen fiber according to claim 4, wherein component (B) is aluminum, or a salt thereof or a complex thereof.

6. A method for processing regenerated collagen fibers, including the following step (i). Step (i) A step of immersing regenerated collagen fibers in a fiber treatment agent containing the following component (A). (A) Benzoic acid or its salt

7. The regenerated collagen fiber contains the following component (B), as described in claim 6. Gen fiber processing method. (B) Polyvalent metals, or their salts or complexes

8. The recycled material according to claim 7, wherein component (B) is aluminum, or a salt or complex thereof. A method for processing collagen fibers.

9. A method for producing modified regenerated collagen fibers, comprising the step of treating regenerated collagen fibers by the regenerated collagen fiber treatment method described in any one of claims 6 to 8.

10. A method for producing a head ornament, comprising the step of treating regenerated collagen fibers by the regenerated collagen fiber treatment method described in any one of claims 6 to 8.

11. A head ornament product comprising modified regenerated collagen fibers as a component, according to any one of claims 1 to 3.