Modified Regenerated Collagen Fiber, Production Method Therefor, and Headdress Product Containing Same

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.

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.

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.

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.

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.

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.

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).

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:

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

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.

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.

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

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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:

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.

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.

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.

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.

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.

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.

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 %.

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.

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.

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).

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.

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.

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.

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.

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.

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).

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.