MODIFIED REGENERATED COLLAGEN FIBER, PRODUCTION METHOD THEREFOR, AND HEADDRESS PRODUCT CONTAINING SAME

Abstract

 The present invention relates to modified regenerated collagen fibers which have improved water resistance and heat resistance problematic in regenerated collagen fibers, impart heat shape memory ability, are excellent in stretchability (tenacity) and the feel of the surfaces, and have no coloring. The modified regenerated collagen fibers of the present invention contain 1.0 mass% or more of the following component (A) as benzoic acid in regenerated collagen fibers: (A) benzoic acid or a salt thereof.

Description

Field of the Invention

[0001] The present invention relates to regenerated collagen fibers to which water resistance, heat resistance, and heat shape memory ability are imparted, and preferably relates to regenerated collagen fibers used in fiber products such as headdress products such as wigs and extensions.

Background of the Invention

[0002] Unlike synthetic fibers, regenerated collagen fibers generally have natural texture and appearance originating from a natural material. The present regenerated collagen fibers are obtained by solubilizing acid-soluble collagen or by solubilizing insoluble collagen with an alkali or an enzyme to obtain a spinning stock solution, and discharging the spinning stock solution into a coagulation bath through a spinning nozzle to form fibers.

[0003] However, regenerated collagen fibers generally have higher hydrophilicity and hence higher water absorption as compared to synthetic fibers, and the regenerated collagen fibers have extremely low mechanical strength when they contain a large amount of water. This leads to deterioration of suitability as a fiber product such as headdress products such that during washing, mechanical strength significantly decreases because of the higher water absorption, and during subsequent drying, rupture occurs.

[0004] Regenerated collagen fibers also have the problem of low heat resistance, so that, for example, if a heat set using a hair iron or the like is performed at a temperature as high as that for human hair, shrinkage or crimping occurs, resulting in impairment of visual quality.

[0005] Further, in plastic synthetic fibers, the shape in a heat set with an iron or the like is continuously memorized even after subsequent washing (there is heat shape memory ability), whereas in regenerated collagen fibers, the shape in a heat set with an iron or the like is lost through subsequent one time washing (there is no heat shape memory ability). Therefore, regenerated collagen fibers may be inferior to conventional plastic synthetic fibers in terms of degree of freedom of shape set.

[0006] The above points are a factor in limiting popularization of regenerated collagen fibers for fiber products. In particular, water resistance, that is, a decrease in mechanical strength when it is wet has a significant impact.

[0007] On the other hand, in the field of human hair fibers, a method is known in which to human hair fibers having essentially no heat shape memory ability, a specific aldehyde derivative and phenolic compound are applied for newly imparting heat shape memory ability (Patent Literature 1).

[0008] Patent Literature 1: JP-A-2019-143281

Summary of the Invention

[0009] The present invention provides modified regenerated collagen fibers comprising 1.0 mass% or more of the following component (A) as benzoic acid in regenerated collagen fibers:

(A) benzoic acid or a salt thereof

[0010] Further, the present invention provides a method for treating regenerated collagen fibers comprising the following (i):

(i) immersing regenerated collagen fibers in a fiber-treating agent comprising the following component (A):

(A) benzoic acid or a salt thereof.

[0011] Further, the present invention provides a method for producing modified regenerated collagen fibers, comprising treating regenerated collagen fibers by the above-described method for treating regenerated collagen fibers.

[0012] Further, the present invention provides a method for producing a headdress product, comprising treating regenerated collagen fibers by the above-described method for treating regenerated collagen fibers.

[0013] Further, the present invention provides a headdress product comprising the above-described modified regenerated collagen fibers as a constituent element.

Detailed Description of the Invention

[0014] In some situations of production of fiber products, fibers are intensively extended, and in the technique disclosed in Patent Literature 1, there are cases where the stretchability (tenacity) of treated fibers is not sufficient. For this reason, it is required to enhance the stretchability of treated fibers for preventing rupture during extension. In the technique disclosed in Patent Literature 1, there are also cases where coloring of fibers is caused.

[0015] Therefore, the present invention relates to modified regenerated collagen fibers which have improved water resistance and heat resistance problematic in regenerated collagen fibers, impart heat shape memory ability, are excellent in stretchability (tenacity) and the feel of the surfaces, and have no coloring.

[0016] The present inventors conducted intensive studies and as a result, found that in modified regenerated collagen fibers containing benzoic acid or a salt thereof, the carboxy group in the benzoic acid or a salt thereof is strongly coordinated with a metal (mainly polyvalent metal) in regenerated collagen fibers, so that the inside of the fibers is hydrophobized and the leakage of benzoic acid or a salt thereof from the fibers is prevented. As a result, the present inventors found that not only water resistance, and heat resistance in both dry state and wet state in the modified regenerated collagen fibers are improved, and the shape can be imparted by a heat set, but also surprisingly, the stretchability (tenacity) is improved as compared to that before treatment and can be enhanced to a level close to that of human hair, and further, no coloring accompanied with modification treatment is caused, leading to completion of the present invention.

[0017] According to the present invention, it is possible to provide modified regenerated collagen fibers which have improved water resistance and heat resistance problematic in regenerated collagen fibers, impart heat shape memory ability, have improved stretchability (tenacity) and the feel of the surfaces, and have no coloring.

[Fibers to be treated in the present invention]

[0018] Fibers to be treated with the fiber treatment of the present invention are artificially produced fibers using a polymer or oligomer derived from collagen as a raw material, that is, regenerated collagen fibers using collagen as a raw material.

[0019] Regenerated collagen fibers can be produced by a known technique, are not required to have a composition of collagen 100%, and may contain a natural or synthetic polymer and additives for improvement of quality. Further, regenerated collagen may be post-processed. Regenerated collagen fibers are preferably in the form of filaments. Filaments are generally taken from fibers wound around a bobbin or packed in a box. It is also possible to directly use filaments coming out from a drying step in a production process of regenerated collagen fibers.

[0020]  As the raw material of collagen used for producing regenerated collagen fibers, a split portion is preferably used. Splits are obtained from fresh splits obtained by sacrificing livestock animals such as cattle and from salt cured hides. A large part of these splits and the like is composed of insoluble collagen fibers, and they are generally used after removing flesh portions adhered in a mesh form, and then removing salts which are used to prevent decomposition and change in quality.

[0021] In the insoluble collagen fibers, there are impurities such as lipids such as glycerides, phosphatides, and free fatty acid; glycoproteins; proteins other than collagen, such as albumin. These impurities have a great influence on spinning stability, qualities such as brilliance and strength and elongation, odor, and the like upon forming fibers. Thus, these impurities are preferably removed in advance, for example, by liming insoluble collagen fibers to hydrolyze the fat content therein, disentangling collagen fibers, and then subjecting the fibers to conventionally and generally performed hide and leather treatment such as acid/alkaline treatment, enzyme treatment, or solvent treatment.

[0022] The insoluble collagen subjected to treatment as described above is subjected to solubilization treatment to cut the cross-linked peptide moiety. As the method for such solubilization treatment, a generally employed known alkaline solubilization method, enzyme solubilization method, or the like can be applied. Further, the above-described alkaline solubilization method and enzyme solubilization method may be used in combination.

[0023] When the alkaline solubilization method is applied, neutralization is preferable with an acid such as hydrochloric acid. As an improved method of the conventionally known alkaline solubilization method, a method described in JP-B-S46-15033 may be used.

[0024]  The enzyme solubilization method has such an advantage that soluble collagen having a uniform molecular weight can be obtained, and is thus a method preferably employed in the present invention. As such an enzyme solubilization method, for example, methods described in JP-B-S43-25829, JP-B-S43-27513, and the like can be employed.

[0025] When collagen subjected to solubilization treatment as described above is further subjected to an operation such as pH adjustment, salting-out, washing with water, or solvent treatment, regenerated collagen fibers excellent in quality can be obtained. Thus, collagen is preferably subjected to the above-described treatment.

[0026] The obtained soluble collagen is, for example, dissolved with an acid such as hydrochloric acid, acetic acid, or lactic acid, and adjusted so as to obtain an aqueous collagen solution having a pH of from 2 to 4.5 and a collagen concentration of 1 mass% or more, preferably 2 mass% or more, and 15 mass% or less, preferably 10 mass% or less. The aqueous collagen solution may be defoamed by stirring under reduced pressure and filtered to remove fine wastes which are water-insoluble contents, as necessary. For example, to improve mechanical strength, water resistance and heat resistance, brilliance, and spinnability, and prevent coloring, corrosion, and the like, an appropriate amount of additive such as a stabilizer or a water-soluble polymer compound may be further formulated in the aqueous collagen solution, as necessary.

[0027] The aqueous collagen solution is discharged through, for example, a spinning nozzle or a slit, and immersed in an aqueous inorganic salt solution, thereby forming regenerated collagen fibers. As the aqueous inorganic salt solution, for example, an aqueous solution of a water-soluble inorganic salt such as sodium sulfate, sodium chloride, or ammonium sulfate is used. The concentration of the inorganic salt in the aqueous inorganic salt solution is generally adjusted to from 10 to 40 mass%. The pH of the aqueous inorganic salt solution is preferably 2 or more, more preferably 4 or more, and preferably 13 or less, more preferably 12 or less. In the adjustment of pH, for example, a metal salt such as sodium borate or sodium acetate, hydrochloric acid, boric acid, acetic acid, or sodium hydroxide may be used. When the pH of the aqueous inorganic salt solution is in the above-described range, the peptide bond of collagen is unlikely hydrolyzed and the intended fibers are easily obtained. The temperature of the aqueous inorganic salt solution is not particularly limited, and desirably, usually 35°C or lower since soluble collagen is not denatured, the strength of spun fibers is not reduced, and stable production of fibers is easy. The lower limit of the temperature of the aqueous inorganic salt solution is not particularly limited, and is generally, appropriately adjusted depending on the solubility of the inorganic salt.

[0028] The regenerated collagen fibers may be subjected to pretreatment (cross-linking treatment) by immersing the regenerated collagen fibers in an epoxy compound or a solution thereof. The amount of the epoxy compound is preferably 0.1 equivalents or more, more preferably 0.5 equivalents or more, further more preferably 1 equivalent or more, and preferably 500 equivalents or less, more preferably 100 equivalents or less, further more preferably 50 equivalents or less with respect to the amount of the amino group capable of reacting with the epoxy compound in the regenerated collagen fibers measured by an amino acid analysis. When the amount of the epoxy compound is in the range, not only the effect of insolubilizing regenerated collagen fibers in water can be sufficiently imparted, but also it is preferable in terms of industrial handleability and environment.

[0029] The epoxy compound is used as it is or by being dissolved in various solvents. Examples of the solvent include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; ethers such as tetrahydrofuran and dioxane; halogen organic solvents such as dichloromethane, chloroform, and carbon tetrachloride; and neutral organic solvents such as dimethylformamide (DMF) and dimethylsulfoxide (DMSO). These solvents may be used alone, or two or more solvents may be used as a mixture. When water is used as the solvent, an aqueous solution of an inorganic salt such as sodium sulfate, sodium chloride, or ammonium sulfate may be used, as necessary. The concentration of the inorganic salt in the aqueous solution of the inorganic salt is generally adjusted to from 10 to 40 mass%. The pH of the aqueous solution may be adjusted by, for example, a metal salt such as sodium borate and sodium acetate; hydrochloric acid, boric acid, acetic acid, or sodium hydroxide. In this case, the pH of the aqueous solution is preferably 6 or more, more preferably 8 or more, from the viewpoint of preventing the reaction between the epoxy group of the epoxy compound and the amino group of collagen from becoming slow and achieving sufficient insolubilization in water. Since the pH of the aqueous solution of the inorganic salt tends to be reduced with time, a buffer may be used, as necessary.

[0030] The treatment temperature of the regenerated collagen fibers by the epoxy compound is preferably 50°C or lower, from the viewpoint of preventing regenerated collagen fibers from being denatured, preventing the strength of the fibers to be obtained from being reduced, and making stable production of fibers easy.

[0031] Then, the regenerated collagen fibers may be subjected to washing with water, oiling, or drying. Washing with water can be performed by, for example, washing the fibers for from 10 minutes to 4 hours with running water. As the oil agent used in oiling, for example, an oil agent composed of an emulsion such as amino modified silicone, epoxy modified silicone, or polyether modified silicone, and a pluronic polyether antistatic agent can be used. The drying temperature is preferably 100°C or lower, more preferably 75°C or lower.

[0032] The regenerated collagen fibers to be treated preferably contain a polyvalent metal, or a salt or complex thereof from the viewpoint of improving water resistance. Examples of the polyvalent metal include calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoint of improving water resistance, reducing coloring of fibers, reducing effects on the environment, and improving economic efficiency, aluminum, zirconium, or titanium is preferably used, and aluminum is more preferably used. The content of the polyvalent metal, or the salt or complex thereof in the regenerated collagen fibers is, as the amount of the metal element, preferably 1.0 mass% or more, more preferably 2.0 mass% or more, further more preferably 3.0 mass% or more, even more preferably 5.0 mass% or more, from the viewpoint of improving water resistance, and preferably 40 mass% or less, more preferably 30 mass% or less, further more preferably 20 mass% or less, even more preferably 10 mass% or less, from the viewpoint of improving the feel of the fiber surfaces.

[0033] That is, the content of the polyvalent metal, or the salt or complex thereof in the regenerated collagen fibers to be treated is, as the amount of the metal element, preferably from 1.0 to 40 mass%, more preferably from 2.0 to 30 mass%, further more preferably from 3.0 to 20 mass%, even more preferably from 5.0 to 10 mass%, from the above viewpoint.

[Method for treating fibers]

(Basic treatment)

[0034] The method for treating fibers of the present invention comprises the following (i), and therefore, it is possible to produce modified regenerated collagen fibers which have improved water resistance and heat resistance problematic in regenerated collagen fibers, impart heat shape memory ability, have improved stretchability (tenacity) and the feel of the surfaces, and have no coloring:

(i) immersing regenerated collagen fibers in a fiber-treating agent comprising the following component (A):

(A) Benzoic acid or a salt thereof.

[0035] The content of the component (A) in the fiber-treating agent used in the step (i) is different depending on the pH range of the fiber-treating agent, and the following range is preferable.

[0036]  When the pH of the fiber-treating agent is 2.0 or more and less than 6.5, the content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably 0.8 mass% or more, more preferably 3.0 mass% or more, further more preferably 5.0 mass% or more, even more preferably 10 mass% or more, even more preferably 15 mass% or more, even more preferably 20 mass% or more, from the viewpoint of imparting higher shape sustainability, water resistance, stretchability (tenacity, that is, high breaking elongation during fiber tensioning), and heat resistance to treated modified regenerated collagen fibers, and preferably 90 mass% or less, more preferably 80 mass% or less, further more preferably 70 mass% or less, even more preferably 50 mass% or less, even more preferably 40 mass% or less, even more preferably 35 mass% or less, from the viewpoint of improving the feel of the fiber surfaces.

[0037] That is, when the pH of the fiber-treating agent is 2.0 or more and less than 6.5, the content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably from 0.8 to 90 mass%, more preferably from 3.0 to 80 mass%, further more preferably from 5.0 to 70 mass%, even more preferably from 10 to 50 mass%, even more preferably from 15 to 40 mass%, even more preferably from 20 to 35 mass%, from the above viewpoint.

[0038] When the pH of the fiber-treating agent is 6.5 or more and 11.0 or less, the content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably 0.8 mass% or more, more preferably 3.0 mass% or more, further more preferably 5.0 mass% or more, even more preferably 10 mass% or more, even more preferably 15 mass% or more, even more preferably 20 mass% or more, even more preferably 25 mass% or more, even more preferably 26 mass% or more, even more preferably 28 mass% or more, even more preferably 30 mass% or more, from the viewpoint of imparting higher shape sustainability, water resistance, stretchability (tenacity, that is, high breaking elongation during fiber tensioning), and heat resistance to treated modified regenerated collagen fibers, and preferably 90 mass% or less, more preferably 80 mass% or less, further more preferably 70 mass% or less, even more preferably 50 mass% or less, even more preferably 45 mass% or less, even more preferably 40 mass% or less, from the viewpoint of improving the feel of the fiber surfaces.

[0039] That is, when the pH of the fiber-treating agent is 6.5 or more and 11.0 or less, the content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably from 0.8 to 90 mass%, more preferably from 3.0 to 80 mass%, further more preferably from 5.0 to 70 mass%, even more preferably from 10 to 70 mass%, even more preferably from 15 to 50 mass%, even more preferably from 20 to 50 mass%, even more preferably from 25 to 45 mass%, even more preferably from 26 to 45 mass%, even more preferably from 28 to 40 mass%, even more preferably from 30 to 40 mass%, from the above viewpoint.

[0040] The fiber-treating agent used in the step (i) has water as a medium. The content of water in the fiber-treating agent is preferably 10 mass% or more, more preferably 20 mass% or more, further more preferably 30 mass% or more, even more preferably 40 mass% or more, and preferably 95 mass% or less, more preferably 90 mass% or less, further more preferably 85 mass% or less.

[0041] That is, the content of water in the fiber-treating agent is preferably from 10 to 95 mass%, more preferably from 20 to 90 mass%, further more preferably from 30 to 85 mass%, even more preferably from 40 to 85 mass%.

[0042] The pH of the fiber-treating agent used in the step (i) is preferably 2.0 or more, more preferably 3.0 or more, further more preferably 3.5 or more, even more preferably 4.0 or more, and preferably 11.0 or less, more preferably 10.0 or less, further more preferably 9.0 or less, from the viewpoint of suppressing damage to and improving durability of regenerated collagen fibers. The pH in the present invention is a value at 25°C.

[0043] That is, the pH of the fiber-treating agent is preferably from 2.0 to 11.0, more preferably from 3.0 to 10.0, further more preferably from 3.5 to 9.0, even more preferably from 4.0 to 9.0, from the viewpoint of suppressing damage to and improving durability of regenerated collagen fibers.

[0044] In the step (i), the regenerated collagen fibers to be subjected to fiber treatment may be dry or wet. For example, the regenerated collagen fibers may be directly treated in a state before drying upon production of the regenerated collagen fibers. The amount of the fiber-treating agent in which the regenerated collagen fibers are immersed is preferably 2.0 or more, more preferably 3.0 or more, further more preferably 5.0 or more, even more preferably 10 or more, even more preferably 20 or more, and preferably 500 or less, more preferably 250 or less, further more preferably 100 or less, in terms of bath ratio to the mass of the regenerated collagen fibers (mass of fiber-treating agent/mass of regenerated collagen fibers).

[0045] That is, the bath ratio is preferably from 2.0 to 500, more preferably from 3.0 to 250, further more preferably from 5.0 to 100, even more preferably from 10 to 100, even more preferably from 20 to 100.

[0046] In the step (i), the regenerated collagen fibers are fixed with a curler or the like in advance, followed by being subjected to the fiber treatment of the present invention under heating. This enables a desired shape to be imparted to the regenerated collagen fibers together with heat shape memory ability and high durability.

[0047] It is preferable that the immersion of the regenerated collagen fibers in the fiber-treating agent in the step (i) be performed under heating, and this heating is performed by heating the fiber-treating agent. This heating may be performed by immersing the regenerated collagen fibers in the fiber-treating agent being heated, or by immersing the regenerated collagen fibers in the fiber-treating agent at a low temperature, and then performing heating. The temperature of the fiber-treating agent is preferably 20°C or higher, more preferably 35°C or higher, further more preferably 45°C or higher to obtain the effect of the present invention by increasing the interaction between the component (A) and fiber-forming molecules in the regenerated collagen fibers, for example, protein molecules, and preferably less than 100°C, more preferably 80°C or lower, further more preferably 70°C or lower, further more preferably 60°C or lower to prevent the regenerated collagen fibers from being modified by heat and deteriorating.

[0048] The immersion time in the step (i) is appropriately adjusted depending on the heating temperature, and is, for example, preferably 15 minutes or more, more preferably 30 minutes or more, further more preferably 1 hour or more, from the viewpoint of exhibiting a stretchability improving effect on regenerated collagen fibers, and is preferably 48 hours or less, more preferably 24 hours or less, further more preferably 12 hours or less, for suppressing damage to regenerated collagen fibers.

[0049] It is preferable to carry out the step (i) in an environment where evaporation of moisture is suppressed. Examples of the specific means for suppressing evaporation of moisture include a method in which a container of the fiber-treating agent in which regenerated collagen fibers are immersed is covered with a film-shaped material, a cap, a lid or the like made of a material impermeable to water vapor.

[0050] After the step (i), the regenerated collagen fibers may be rinsed or may not be rinsed, but are preferably rinsed from the viewpoint of preventing deterioration of the feel of the surfaces of regenerated collagen fibers by an excess component (A).

[0051] The treatment of the step (i) may allow the component (A) to penetrate into the regenerated collagen fibers, to be strongly coordinated with metals in the fibers, for example, polyvalent metals, thereby producing various effects. That is, it is possible to produce modified regenerated collagen fibers containing the component (A) in the fibers by the method for treating regenerated collagen fibers comprising the step (i), and the obtained modified regenerated collagen fibers are fibers which can impart the shape by a heat set, are excellent in water resistance, heat resistance, and tensile elastic modulus, and have highly improved stretchability (tenacity) of the regenerated collagen fibers.

[Modified regenerated collagen fibers]

[0052] Hereinafter, the modified regenerated collagen fibers of the present invention obtained by the above-described method will be described.

(Component (A): Benzoic acid or salt thereof)

[0053] The modified regenerated collagen fibers of the present invention comprise benzoic acid or a salt thereof of the component (A). When the component (A) is a salt, examples of the salt include alkaline metal salts such as sodium salts and potassium salts.

[0054] The content of the component (A) in the modified regenerated collagen fibers of the present invention is, as benzoic acid, 1.0 mass% or more, preferably 5.0 mass% or more, more preferably 10 mass% or more, further more preferably 12 mass% or more, even more preferably 15 mass% or more, from the viewpoint of having higher shape sustainability, water resistance, and heat resistance, and preferably 50 mass% or less, more preferably 40 mass% or less, further more preferably 30 mass% or less, from the viewpoint of improving the feel of the fiber surfaces.

[0055] That is, the content of the component (A) in the modified regenerated collagen fibers of the present invention is, as benzoic acid, preferably from 1.0 to 50 mass%, more preferably from 5.0 to 40 mass%, further more preferably from 10 to 40 mass%, even more preferably from 12 to 40 mass%, even more preferably from 15 to 30 mass%, from the above viewpoint.

(Component (B): polyvalent metal, or salt or complex thereof)

[0056] The modified regenerated collagen fibers of the present invention further preferably contain (B) a polyvalent metal, or a salt or complex thereof, from the viewpoint of improving water resistance. Examples of the polyvalent metal include calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper. From the viewpoint of improving water resistance, reducing coloring of fibers, reducing effects on the environment, and improving economic efficiency, aluminum, zirconium, or titanium is preferably used, and aluminum is more preferably used. These polyvalent metals may be used either alone or in combination of two or more.

[0057] The content of the component (B) in the modified regenerated collagen fibers of the present invention is, as the amount of the metal element, preferably 0.1 mass% or more, more preferably 0.5 mass% or more, further more preferably 1.0 mass% or more, even more preferably 2.0 mass% or more, even more preferably 5.0 mass% or more, from the viewpoint of improving water resistance, and preferably 40 mass% or less, more preferably 30 mass% or less, further more preferably 20 mass% or less, even more preferably 10 mass% or less, even more preferably 7.0 mass% or less, from the viewpoint of improving the feel of the fiber surfaces.

[0058] That is, the content of the component (B) in the modified regenerated collagen fibers of the present invention is, as the amount of the metal element, preferably from 0.1 to 40 mass%, more preferably from 0.5 to 30 mass%, further more preferably from 1.0 to 20 mass%, even more preferably from 2.0 to 10 mass%, even more preferably from 5.0 to 7.0 mass% from the above viewpoint.

[0059] A mass ratio of the content of the component (A) as benzoic acid (component (A) _{amount of benzoic acid}) to the content of the component (B) as a metal element (component (B) _{amount of metal element}), (component (A) amount of benzoic _acid/ component (B) _{amount of metal element}), in the modified regenerated collagen fibers of the present invention is preferably 0.025 or more, more preferably 0.2 or more, further more preferably 0.5 or more, even more preferably 1.0 or more, even more preferably 2.0 or more, even more preferably 2.5 or more, from the viewpoint of having higher shape sustainability, water resistance, and heat resistance, and preferably 100 or less, more preferably 50 or less, further more preferably 20 or less, even more preferably 10 or less, even more preferably 8 or less, even more preferably 6 or less, even more preferably 4 or less, from the viewpoint of having high durability and improving the feel of the fiber surfaces.

[0060] That is, the mass ratio (component (A) _{amount of benzoic acid}/component (B) _{amount of metal element}), in the modified regenerated collagen fibers of the present invention is preferably from 0.025 to 100, more preferably from 0.2 to 50, further more preferably from 0.5 to 20, even more preferably from 1.0 to 10, even more preferably from 2.0 to 8, even more preferably from 2.5 to 6, even more preferably from 2.5 to 4, from the above viewpoint.

[0061] The modified regenerated collagen fibers of the present invention are fibers which can impart the shape by a heat set, are excellent in water resistance, heat resistance, and tensile elastic modulus, and have highly improved stretchability (tenacity) of the regenerated collagen fibers. Therefore, the modified regenerated collagen fibers of the present invention can be preferably used as the fibers for headdress products, and various headdress products can be produced using the fibers.

[0062] In the present invention, examples of suitable headdress products include hair wigs, wigs, weavings, hair extensions, blade hairs, hair accessories, and doll hairs.

[0063] The modified regenerated collagen fibers of the present invention may be used as the headdress products alone, or may be mixed with other fibers to produce headdress products. Other fibers may be fibers which can be used in headdress products and are not particularly limited. Examples of other fibers include polyester fibers, human hair, animal hair, polyvinyl chloride fibers, modacrylic fibers, polyamide fibers, and polyolefin fibers. Among them, polyester fibers are preferable, and flame-retardant polyester fibers are more preferable, from the viewpoint of being excellent in heat resistance, flame retardancy, and curl retention properties.

[0064] The flame-retardant polyester fibers are not particularly limited, and it is preferable to contain from 5 to 40 parts by mass of a brominated epoxy flame retardant with respect to 100 parts by mass of one or more polyester resins selected from the group consisting of polyalkylene terephthalate and copolymerized polyester mainly composed of polyalkylene terephthalate, from the viewpoint of flame retardancy. In the present invention, "mainly composed of" means containing 50 mol% or more, and "copolymerized polyester mainly composed of polyalkylene terephthalate" refers to copolymerized polyester containing 50 mol% or more of polyalkylene terephthalate. Preferably, "copolymerized polyester mainly composed of polyalkylene terephthalate" contains 60 mol% or more, more preferably 70 mol% or more, further more preferably 80 mol% or more of polyalkylene terephthalate. It is preferable that the flame-retardant polyester fibers further contain from 0 to 5 parts by mass of an antimony compound with respect to 100 parts by mass of the polyester resin. By containing the antimony compound, flame retardancy of polyester fibers improves.

[0065] Concerning the embodiments described above, preferred aspects of the present invention will be further disclosed below.

[0066] 

<1> Modified regenerated collagen fibers comprising 1.0 mass% or more of the following component (A) as benzoic acid in regenerated collagen fibers:

(A) benzoic acid or a salt thereof.

<2> The modified regenerated collagen fibers according to <1>, wherein a content of the component (A) is, as benzoic acid, preferably 5.0 mass% or more, more preferably 10 mass% or more, further more preferably 12 mass% or more, even more preferably 15 mass% or more, and preferably 50 mass% or less, more preferably 40 mass% or less, further more preferably 30 mass% or less.

<3> The modified regenerated collagen fibers according to <1> or <2>, preferably, further comprising the following component (B):
(B) a polyvalent metal, or a salt or complex thereof.

<4> The modified regenerated collagen fibers according to <3>, wherein the component (B) is preferably one or more polyvalent metals selected from the group consisting of calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof, more preferably one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt or complex thereof, further more preferably aluminum, or a salt or complex thereof.

<5> The modified regenerated collagen fibers according to <3> or <4>, wherein a content of the component (B) is, as the amount of the metal element, preferably 0.1 mass% or more, more preferably 0.5 mass% or more, further more preferably 1.0 mass% or more, even more preferably 2.0 mass% or more, even more preferably 5.0 mass% or more, and preferably 40 mass% or less, more preferably 30 mass% or less, further more preferably 20 mass% or less, even more preferably 10 mass% or less, even more preferably 7.0 mass% or less.

<6> The modified regenerated collagen fibers according to any one of <1> to <5>, wherein a mass ratio of the content of the component (A) as benzoic acid to the content of the component (B) as a metal element, (component (A) _{amount of benzoic acid}/component (B) _{amount of metal element}) is preferably 0.025 or more, more preferably 0.2 or more, further more preferably 0.5 or more, even more preferably 1.0 or more, even more preferably 2.0 or more, even more preferably 2.5 or more, and preferably 100 or less, more preferably 50 or less, further more preferably 20 or less, even more preferably 10 or less, even more preferably 8 or less, even more preferably 6 or less, even more preferably 4 or less.

<7> A method for treating regenerated collagen fibers comprising the following (i):

(i) immersing regenerated collagen fibers in a fiber-treating agent comprising the following component (A):

(A) benzoic acid or a salt thereof.

<8> The method for treating regenerated collagen fibers according to <7>, comprising a regenerated collagen fiber production step of subjecting insoluble collagen fibers using a split of a livestock animal as a raw material to solubilization treatment, discharging the obtained aqueous soluble collagen solution through a spinning nozzle or a slit, and immersing the aqueous soluble collagen solution in an aqueous inorganic salt solution, before the (i).

<9> The method for treating regenerated collagen fibers according to <8>, preferably comprising a cross-linking treatment step of immersing the regenerated collagen fibers in an epoxy compound or a solution thereof, after the regenerated collagen fiber production step.

<10> The method for treating regenerated collagen fibers according to any one of <7> to <9>, wherein the regenerated collagen fibers comprise the following component (B):
(B) a polyvalent metal, or a salt or complex thereof.

<11> The method for treating regenerated collagen fibers according to <10>, wherein the component (B) is preferably one or more polyvalent metals selected from the group consisting of calcium, magnesium, strontium, barium, zinc, chromium, aluminum, titanium, zirconium, tin, lead, antimony, iron, and copper, or a salt or complex thereof, more preferably one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt or complex thereof, further more preferably aluminum, or a salt or complex thereof.

<12> The method for treating regenerated collagen fibers according to any one of <7> to <11>, wherein a pH of the fiber-treating agent used in the (i) at 25°C is preferably 2.0 or more, more preferably 3.0 or more, further more preferably 3.5 or more, even more preferably 4.0 or more, and preferably 11.0 or less, more preferably 10.0 or less, further more preferably 9.0 or less.

<13> The method for treating regenerated collagen fibers according to any one of <7> to <12>, wherein a pH of the fiber-treating agent used in the (i) is 2.0 or more and less than 6.5, and a content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably 0.8 mass% or more, more preferably 3.0 mass% or more, further more preferably 5.0 mass% or more, even more preferably 10 mass% or more, even more preferably 15 mass% or more, even more preferably 20 mass% or more, and preferably 90 mass% or less, more preferably 80 mass% or less, further more preferably 70 mass% or less, even more preferably 50 mass% or less, even more preferably 40 mass% or less, even more preferably 35 mass% or less.

<14> The method for treating regenerated collagen fibers according to any one of <7> to <12>, wherein a pH of the fiber-treating agent used in the (i) is 6.5 or more and 11.0 or less, and a content of the component (A) in the fiber-treating agent is, as benzoic acid, preferably 0.8 mass% or more, more preferably 3.0 mass% or more, further more preferably 5.0 mass% or more, even more preferably 10 mass% or more, even more preferably 15 mass% or more, even more preferably 20 mass% or more, even more preferably 25 mass% or more, even more preferably 26 mass% or more, even more preferably 28 mass% or more, even more preferably 30 mass% or more, and preferably 90 mass% or less, more preferably 80 mass% or less, further more preferably 70 mass% or less, even more preferably 50 mass% or less, even more preferably 45 mass% or less, even more preferably 40 mass% or less.

<15> The method for treating regenerated collagen fibers according to any one of <7> to <14>, wherein the fiber-treating agent used in the (i) has water as a medium, and a content of water in the fiber-treating agent is preferably 10 mass% or more, more preferably 20 mass% or more, further more preferably 30 mass% or more, even more preferably 40 mass% or more, and preferably 95 mass% or less, more preferably 90 mass% or less, further more preferably 85 mass% or less.

<16> The method for treating regenerated collagen fibers according to any one of <7> to <15>, wherein an amount of the fiber-treating agent in which the regenerated collagen fibers are immersed in the (i) is preferably 2 or more, more preferably 3 or more, further more preferably 5 or more, even more preferably 10 or more, even more preferably 20 or more, and preferably 500 or less, more preferably 250 or less, further more preferably 100 or less, in terms of bath ratio to a mass of the regenerated collagen fibers (mass of fiber-treating agent/mass of regenerated collagen fibers).

<17> The method for treating regenerated collagen fibers according to any one of <7> to <16>, wherein a temperature of the fiber-treating agent in which the regenerated collagen fibers are immersed in the (i) is preferably 20°C or higher, more preferably 35°C or higher, further more preferably 45°C or higher, and preferably less than 100°C, more preferably 80°C or lower, further more preferably 70°C or lower, further more preferably 60°C or lower.

<18> The method for treating regenerated collagen fibers according to any one of <7> to <17>, wherein an immersion time in the (i) is preferably 15 minutes or more, more preferably 30 minutes or more, further more preferably 1 hour or more, and preferably 48 hours or less, more preferably 24 hours or less, further more preferably 12 hours or less.

<19> The method for treating regenerated collagen fibers according to any one of <7> to <18>, wherein it is preferable to carry out the (i) in an environment where evaporation of moisture is suppressed.

<20> A method for producing modified regenerated collagen fibers, comprising treating regenerated collagen fibers by the method for treating regenerated collagen fibers according to any one of <7> to <19>.

<21> A method for producing a headdress product, comprising treating regenerated collagen fibers by the method for treating regenerated collagen fibers according to any one of <7> to <19>.

<22> A headdress product comprising the modified regenerated collagen fibers according to any one of <1> to <6> as a constituent element.

<23> The headdress product according to <22>, wherein the headdress product is selected from the group consisting of hair wigs, wigs, weavings, hair extensions, blade hairs, hair accessories, and doll hairs.

Examples

Examples 1 to 11 and Comparative Examples 1 to 3

[0067] Using compositions whose formulations are shown in Table 1, regenerated collagen fibers were treated by the following method, and various properties were evaluated. The pH of each composition was measured with the prepared composition directly applied to a pH meter (F-52 manufactured by HORIBA, Ltd.) at room temperature (25°C).

<Treatment method>

[0068] 

1. A 22 cm-long tress with 0.50 g of regenerated collagen fibers (*) was immersed in a container containing the fiber-treating agent in such an amount that the bath ratio as shown in the table is achieved, the opening of the container was closed, the container was immersed together with its contents in a water bath (manufacturer: TOYO SEISAKUSHO, Ltd./Model: TBS221FA) at the temperature as shown in the table, and heating was performed for the time as shown in the table.
*: Regenerated collagen fibers manufactured by Kaneka Corporation were purchased in the form of a commercially available extension product, and cut, and the cut fibers were segmented into tresses, and used for evaluation. In this evaluation, extension products having a notation of the use of Ultima 100% as a fiber species, and being white with a color number of 30, and straight in shape, were used.

2. The container containing the tress was taken out from the water bath, and brought back to room temperature.

3. The tress was taken out from the container, then rinsed with running tap water at 30°C for 30 seconds, lathered with evaluating shampoo for 60 seconds, rinsed with running tap water at 30°C for 30 seconds, and lightly drained with a towel, and the tress was dried by a hot air dryer (Nobby White NB 3 000 manufactured by TESCOM Company) while being combed.

<Formulation of evaluating shampoo>

[0069] 

Component	(mass%)
sodium laureth sulfate	15.5
lauramide DEA	1.5
EDTA-2Na	0.3
phosphoric acid	amount required to adjust pH to 7
ion-exchange water	balance
total	100

<Increase in average breaking elongation during fiber tensioning>

[0070] As an index of water resistance and stretchability (tenacity) during fiber tensioning, an average breaking elongation, that is, an average value in evaluation on a plurality of fibers (ten fibers) for the percentage by which the fiber was stretched by tensioning with respect to the original fiber length when rupture occurred was used. The evaluation was performed in the following procedure using a tress immediately after treatment performed as described in <Treatment method> above.

1. Ten fibers were cut from the root of the tress. A 3 cm fiber fragment was taken from near the center between the root and the hair tip of each fiber, so that a total of ten 3 cm hair fragments were obtained.

2. The fiber fragment was set in "MTT690 Miniature Tensile Tester" manufactured by DIA-STRON Limited. After the fiber was allowed to stand for 30 minutes while being immersed in water, automatic measurement was started, and an average breaking elongation was determined in a state where the fiber was immersed in water. A large numerical value indicates that the fiber has high stretchability, and is excellent in tenacity and excellent in durability.

[0071] The degree of increase (C%) in average breaking elongation of the treated tress (B%) with respect to an untreated state when the average breaking elongation during fiber tensioning in an intact state (untreated; Comparative Example 1) at the time of being cut from the commercially available product (A%) is used as a reference is determined from the following expression, and shown as "ratio of increase in average breaking elongation during fiber tensioning [%]" in the table.

<Increase in average breaking load during fiber tensioning>

[0072] As an index of water resistance during fiber tensioning, an average breaking load during fiber tensioning was used. Evaluation was performed using a tress immediately after treatment performed as described in <Treatment method> above. As a numerical value, an average value in evaluation on a plurality of fibers (ten fibers) was used. The evaluation was performed in the following procedure.

1. Ten fibers were cut from the root of the tress. A 3 cm fiber fragment was taken from near the center between the root and the hair tip of each fiber, so that a total of ten 3 cm hair fragments were obtained.

2. The fiber fragment was set in "MTT690 Miniature Tensile Tester" manufactured by DIA-STRON Limited. After the fiber was allowed to stand for 30 minutes while being immersed in water, automatic measurement was started, and a breaking load was determined when the fiber stretched while being immersed in water. A large numerical value indicates that the fiber has suppleness and resilience, and is insusceptible to stretching by an external force, and excellent in durability.

[0073] The degree of increase (Y (gf)) in average breaking load of the treated tress (W₁ (gf)) with respect to an untreated state when the average breaking load during fiber tensioning in an intact state (untreated; Comparative Example 1) at the time of being cut from the commercially available product (W₀ (gf)) is used as a reference is determined from the following expression, and shown as "amount of increase in average breaking load during fiber tensioning [gf]" in the table.

<Shrinkage ratio during set with iron at high temperature>

[0074] As an index of heat resistance, a shrinkage ratio during a set with an iron at a high temperature was used. The evaluation was performed using a tress immediately after treatment performed as described in <Treatment method> above. As a numerical value, an average value in evaluation on a plurality of fibers (five fibers) was used. The evaluation was performed in the following procedure.

1. Five fibers were cut from the root of the tress immediately after treatment performed as described in <Treatment method> above, and marked. The lengths of these five fibers after treatment were measured, and an average value was recorded (length L₁). Then, these marked five fibers after treatment were bundled together with separately prepared two untreated tresses with 0.5 g of regenerated collagen fibers (1 g in total) so as to be sandwiched therebetween to thereby produce a new tress (hereinafter, large tress), and a flat iron (manufactured by Miki Denki Sangyo K.K./Model: AHI-938) set at 180°C was applied throughout the large tress three times at a rate of 5 cm/sec.

2. After the iron operation, marked five fibers after treatment were taken out from the large tress, and the lengths of these marked five fibers after treatment were measured again, and an average value was recorded (length L₂) .

3. The shrinkage ratio during a set with an iron at a high temperature was defined as S_dry = {1 - (L₂/L₁)} × 100 [%]. When S_dry is close to 0%, the fiber is unlikely to shrink by dry heat and thus excellent in heat resistance.

<Shrinkage ratio during hot-water heating>

[0075] As an index of water resistance and heat resistance, a shrinkage ratio during hot-water heating was used. The evaluation was performed using a tress immediately after treatment performed as described in <Treatment method> above. As a numerical value, an average value in evaluation on a plurality of fibers (five fibers) was used. The evaluation was performed in the following procedure.

1. Five fibers were cut from the root of the tress, an average value of the lengths of the fibers was recorded (length L₁), and the fibers were immersed in a water bath (manufacturer: TOYO SEISAKUSHO, Ltd./Model: TBS221FA) at 90°C and heated for 1 minute.

2. After the heating operation, five fibers were taken out, lightly drained with a towel, and dried at ambient temperature and ambient humidity for 30 minutes, and then an average value of the lengths of the fibers was recorded again (length L₂).

3. The shrinkage ratio during hot-water heating was defined as S_wet = {1-(L₂/L₁)} × 100[%]. When S_wet is close to 0%, the fiber is unlikely to shrink by wet heat and thus excellent in heat resistance.

<Heat shape memory ability>

[0076] Evaluation of heat shape memory ability was performed using a tress immediately after treatment performed as described in <Treatment method> above. When the value of the result of "I: shaping (curl)" was 5% or less, it was determined that there was no effect, and subsequent treatment and evaluation were not performed.

• I: Shaping (curl)

[0077] 

1. A 22 cm-long tress with 0.5 g of regenerated collagen fibers was wetted with tap water at 30°C for 30 seconds, and the wet tress was then wound around a plastic rod having a diameter of 14 mm, and fixed with a clip.

2. The tress wound around the rod was immersed in a water bath (manufacturer: TOYO SEISAKUSHO, Ltd./Model: TBS221FA) at 60°C, and heated for 1 minute.

3. The tress was taken out from the water bath, immersed in water at 25°C for 1 minute, and taken out from water to be brought back to room temperature.

4. The tress was removed from the rod, combed three times, and then, hung and photographed right from the side 3 minutes after being taken out from water.

(Evaluation criteria)

[0078] The curling-up ratio = ratio of decrease in tress length (I) (%) determined from the following expression, where L₀ is an untreated tress length (22 cm) and L is a treated tress length, was defined as curling strength.

• II: Reshaping (straight)

[0079] 

1. The tress evaluated in I was combed to eliminate entanglement, and a flat iron (manufactured by Miki Denki Sangyo K.K./Model: AHI-938) set at 180°C was then slid over the tress six times at a rate of 5 cm/sec.

2. The tress was rinsed with running tap water at 30°C for 30 seconds, lathered with evaluating shampoo for 60 seconds, then rinsed with running tap water at 30°C for 30 seconds, and dried with a towel.

3. The tress was hung and naturally dried at 20°C and 65%RH for 12 hours, combed, and then visually observed right from the side while being hung.

(Evaluation criteria)

[0080] The straightening ratio (ST) (%) determined from the following expression, where L₀ is an untreated tress length (22 cm) and L is a treated tress length, was defined as a degree of attainment straightening. The tress is completely straightened when ST is 100%.

• III: Re-reshaping (Curl)

[0081] 

1. The tress evaluated in II was wetted with tap water at 30°C for 30 seconds, and the wet tress was then wound around a plastic rod having a diameter of 14 mm, and fixed with a clip.

2. The tress wound around the rod was immersed in a water bath (manufacturer: TOYO SEISAKUSHO, Ltd./Model: TBS221FA) at 60°C, and heated for 1 minute.

3. The tress was taken out from the water bath, immersed in water at 25°C for 1 minute, and taken out from water to be brought back to room temperature.

4. The tress was removed from the rod, combed three times, and then, hung and photographed right from the side 3 minutes after being taken out from water.

(Evaluation criteria)

[0082] The curling-up ratio = ratio of decrease in tress length (I) (%) determined from the following expression, where L₀ is an untreated tress length (22 cm) and L is a treated tress length, was defined as curling strength.

<Surface feel quality>

[0083] For evaluation of the feel of the surfaces, five skilled panelists performed evaluation on the basis of the following criteria for feel smoothness when the tress immediately after treatment performed as described in <Treatment method> was touched by hand, and a total value for the five panelists was taken as an evaluation result.

(Evaluation criteria)

[0084] 

5: Much smoother hand feel over untreated fibers (Comparative Example 1).

4: Smoother hand feel over untreated fibers (Comparative Example 1).

3: Slightly smoother hand feel over untreated fibers (Comparative Example 1).

2: Comparable in hand feel to untreated fibers (Comparative Example 1).

1: Rougher, more frictional and poorer in hand feel than untreated fibers (Comparative Example 1).

<Suppression of coloring on fibers>

[0085] 

1. For each of the front and the back of the tress, the color in each of the vicinity of the root, the vicinity of the center and the vicinity of the hair tip was measured with a colorimeter (Colorimeter CR-400 manufactured by KONICA MINOLTA, INC.), and an average value for a total of six points was taken as a colorimetric value (L, a, b).

2. The degree of coloring was evaluated by ΔE*ab using an untreated white tress with a color number of 30 (*) (Comparative Example 1) as a reference. The color was measured on the day when the treatment was performed.

(*) Untreated white tress with a color number of 30

[0086] Regenerated collagen fibers manufactured by Kaneka Corporation were purchased in the form of a commercially available extension product, and cut, and the cut fibers were segmented into tresses, and used for evaluation. In this evaluation, extension products having a notation of the use of Ultima 100% as a fiber species, and being white with a color number of 30, and straight in shape, were used.

[0087] These regenerated collagen fibers manufactured by Kaneka Corporation contained aluminum, and each aluminum content measured by the above-described analysis was 6.8 mass%.

[0088] ΔE*ab was defined as [(L₁ - L₀)² + (a₁ - a₀)² + (b₁ - b₀)²]^1/2, where (L₀, a₀, b₀) is a measured value for the untreated white tress with a color number of 30 and (L₁, a₁, b₁) is a measured value for the treated tress, and a coloring suppressing effect was determined on the basis of the following criteria.

<Determination of benzoic acid>

[0089] The amount of benzoic acid contained in treated regenerated collagen fibers was determined by the following method, and shown as "Component (A) _{amount of benzoic acid}" in the table (Comparative Examples 2 and 3 were not measured).

• Reagent

[0090] 

6 N Hydrochloric acid: solution for volumetric titration, manufactured by Kanto Chemical Co., Inc.

Sodium acetate: special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation

Acetic acid: special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation

Acetonitrile: for LC/MS, manufactured by Kanto Chemical Co., Inc.

Sodium benzoate: special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation

Ultrapure water: ultrapure Milli-Q water purification system, manufactured by Millipore

• Determination method

[0091] The sample was cut into small pieces, about 10 mg thereof was precisely weighed, 3 mL of 6 N hydrochloric acid was added, and the mixture was heated for dissolution at 50°C for 15 hours. The mixture was allowed to stand for cooling, and then filtered through a filter to obtain a sample solution. Separately, sodium benzoate was dissolved in a mobile phase and prepared to have a concentration as benzoic acid of from 0.1 to 100 µg/mL, which was used as the standard solution for constructing a calibration curve. The sample solution and the standard solution were tested by liquid chromatography, and the peak area of the sample solution and the peak area of the standard solution were measured.

• Measurement conditions

[0092] 

Detector: ultraviolet visible light spectrophotometer

Measurement wavelength: 230 nm

Column: a stainless tube having an internal diameter of 21 mm and a length of 150 mm was filled with 5 µm of octa-decyl silyl silica gel for liquid chromatography.

Column temperature: constant temperature around 40°C

Mobile phase: 750 mL of ultrapure water was added to about 0.68 g of sodium acetate and 0.91 g of acetic acid, and after dissolution, 250 mL of acetonitrile was added, and the mixture was mixed.

• HPLC/UV conditions

[0093] 

Apparatus: UltiMate 3000 system (manufactured by Thermo Fisher Scientific Inc.)

Column: L column 2 ODS 5 µm 2.1 × 150 mm (Chemicals Evaluation and Research Institute, Japan)

Column temperature: 40°C

Mobile phase: 20 mM ammonium acetate 25% acetonitrile buffer solution

Analysis time: 10 minutes

Detector: DAD (diode array detector)

Detection wavelength: 230 nm

Flow rate: 0.3 mL/min (isocratic elution)

Injection volume: 10 µL

<Determination method for aluminum>

[0094] The amount of aluminum contained in treated regenerated collagen fibers was determined by the following method, and shown as "Component (B) _{amount of Al}" in the table (Comparative Examples 2 and 3 were not measured).

• Reagent

[0095] 

Sulfuric acid: for precision analysis, manufactured by FUJIFILM Wako Pure Chemical Corporation

Hydrochloric acid: for metal analysis, manufactured by Kanto Chemical Co., Inc.

Sodium carbonate: special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation

Boric acid: special grade, manufactured by FUJIFILM Wako Pure Chemical Corporation

Aluminum standard solution: for atomic absorption spectrometry, 1 000 mg/L, manufactured by Kanto Chemical Co., Inc.

Ultrapure water: ultrapure Milli-Q water purification system, manufactured by Millipore

• Sample pretreatment method

[0096] 0.1 g of the sample was precisely weighed in a platinum crucible and heated until white smoke was stopped, a few drops of sulfuric acid was then added, the mixture was heated again until white smoke was stopped and sufficiently subjected to ashing treatment in an electric furnace at 550°C. Thereafter, 1 g of an alkaline flux (sodium carbonate:boric acid = 1:0.4) was added, and the mixture was molten in an electric furnace at 950°C. The platinum crucible was covered with a watch glass, ultrapure water and 5 mL of hydrochloric acid (6 mol/L) were added thereto, the mixture was heated and dissolved with a hot plate at 70 to 80°C, allowed to cool, and then made into a constant volume of 50 mL with ultrapure water, and the obtained solution was used as the measurement solution.

• Preparation of solution for calibration curve

[0097] Using the aluminum standard solution (1 000 mg/L), 0.1 to 20 mg/L of solutions for calibration curve were prepared. The alkaline flux and hydrochloric acid were added to each solution so as to be equivalent to the sample.

• Measurement

[0098] With respect to the prepared sample, each element was measured with an ICP optical emission spectrometer under the following conditions.

Analysis apparatus: iCAP6500Duo (manufactured by Thermo Fisher Scientific Inc.)

Wavelength: Al 396.152 nm

RF power: 1150 W

Coolant gas flow rate: 12 L/min

Nebulizer flow rate: 0.70 L/min

Auxiliary gas: 0.5 L/min

Pump flow rate: 50 rpm

[Table 1]

			Example											Comparative Example
			1	2	3	4	5	6	7	8	9	10	11	1	2	3
Treating agent (mass%)	(A)	Sodium benzoate (on benzoic acid basis)	39.0 (33.0)	37.5 (31.8)	35.0 (29.7)	30.0 (25.4)	30.0 (25.4)	20.0 (16.9)	15.0 (12.7)	5.0 (4.2)	1.0 (0.8)	5.0 (4.2)	5.0 (4.2)	-	-	-
	(A)'	2,3-Naphthalenedicarboxylic acid	-	-	-	-	-	-	-	-	-	-	-	-	5.0	-
		Gallic acid	-	-	-	-	-	-	-	-	-	-	-	-	-	5.0
		Water	Balance	Balance	Balance	Balance	Balance	Balance	Balance	Balance	Balance	Balance	Balance	-	Balance	Balance
	pH adjuster	Hydrochloric acid or sodium hydroxide	*	*	*	*	*	*	*	*	*	*	*		*	*
	Total		100	100	100	100	100	100	100	100	100	100	100	-	100	100
	pH(25°C)		7.0	7.0	7.0	7.0	5.5	5.5	5.5	5.5	5.5	4.0	9.0	-	9.0	9.0
Treatment	Bath ratio		40	40	40	40	40	40	40	40	40	40	40	-	40	40
	Heating condition		50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	50°C 1h	-	50°C 1h	50°C 1h
Treated fibers	Component (A) amount of benzoic acid [mass%]		20.3	22.1	20.8	18.4	35.8	37.5	24.5	14.2	3.3	29.8	6.9	0.10	-	-
	Component (B) amount of Al [mass%]		6.2	6.4	5.9	6.5	5.2	5.0	5.7	6.8	6.5	5.5	7.0	7.0	-	-
	Mass ratio (component (A) amount of benzoic acid/component (B) amount of Al)		3.3	3.5	3.5	2.8	6.9	7.5	4.3	2.1	0.51	5.4	1.0	0.014	-	-
	Durability improvement	Ratio of increase in average breaking elongation during fiber tensioning [%]	78.8	63.2	37.9	24.9	16.2	12.8	9.4	4.1	1.1	3.7	3.7	Reference	0.6	-1.9
		Amount of increase in average breaking load during fiber tensioning [gf]	0.3	2.1	6.8	7.1	20.9	25.8	6.7	16.8	7.6	26.6	13.4	Reference	5.3	-25.8
	Heat resistance improvement	Shrinkage ratio during set with iron at high temperature [%]	5.0	6.0	8.0	9.0	6.0	6.7	10.7	12.7	14.0	8.0	12.0	14.0	13.3	33.3
Effect		Shrinkage ratio during hot-water heating [%]	23.0	23.0	21.6	31.0	27.0	19.0	34.0	40.0	57.0	21.0	56.0	76.0	60.0	43.0
	Heat shape memory	I: Shaping (curl)	29	35	36	36	39	38	33	33	26	35	28	1	20	1
		II: Reshaping (straight)	98	97	100	97	98	98	96	100	96	98	97	90	97	85
		III: Re-reshaping (curl)	30	31	30	34	43	38	33	35	25	33	29	6	25	8
	Surface feel quality		20	20	20	20	20	20	18	16	12	16	16	Reference	8	8
	Suppression of coloring on fibers		5	5	5	5	5	5	5	5	5	5	5	Reference	3	1

*: Amount of pH adjustment

[0099] The tresses treated in Examples above can all be used directly as extensions by attachment to head hair with pins or the like, and can exhibit sufficient performance on the human head.

Claims

1. Modified regenerated collagen fibers comprising 1.0 mass% or more of the following component (A) as benzoic acid in regenerated collagen fibers:

(A) benzoic acid or a salt thereof.

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

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

4. The modified regenerated collagen fibers according to any one of claims 1 to 3, further comprising the following component (B):
(B) a polyvalent metal, or a salt or complex thereof.

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

6. A method for treating regenerated collagen fibers comprising the following (i):

(i) immersing regenerated collagen fibers in a fiber-treating agent comprising the following component (A):

(A) benzoic acid or a salt thereof.

7. The method for treating regenerated collagen fibers according to claim 6, wherein the regenerated collagen fibers comprise the following component (B):
(B) a polyvalent metal, or a salt or complex thereof.

8. The method for treating regenerated collagen fibers according to claim 7, wherein the component (B) is aluminum, or a salt or complex thereof.

9. A method for producing modified regenerated collagen fibers, comprising treating regenerated collagen fibers by the method for treating regenerated collagen fibers according to any one of claims 6 to 8.

10. A method for producing a headdress product, comprising treating regenerated collagen fibers by the method for treating regenerated collagen fibers according to any one of claims 6 to 8.

11. A headdress product comprising the modified regenerated collagen fibers according to any one of claims 1 to 5 as a constituent element.