Method for producing processed fibers

Abstract

Provided is a method for producing processed fibers having functionality such as photothermal performance, said method making high fixation of a melanin precursor to fibers possible, and improving friction fastness after dyeing.　The method for producing processed fibers includes a step 1 for conducting cationization of fibers, and a step 2 for applying a melanin precursor solution to the cationized fibers.

Description

Manufacturing methods for processed fibers

[0001] This invention relates to a method for producing processed fibers.

[0002] In the apparel industry, the market size for clothing with various functions such as antibacterial properties, deodorizing properties, quick-drying properties, heat retention, shape retention, UV protection, antistatic (static) properties, and conductivity is expanding. In particular, due to consumers' increasing awareness of hygiene and a preference for cleanliness, there is a high demand for antibacterial processed products and deodorizing processed products that eliminate unpleasant odors such as sweat odor, cigarette odor, and age-related odor. Furthermore, for clothing worn in winter, there is a preference for products with thermal properties and antistatic properties that reduce dust adhesion and clinging due to static electricity, thereby enhancing comfort. For example, thermal functional fiber products include fibers that generate heat by absorbing moisture from sweat, as well as synthetic fibers with ceramic particles that have photothermal properties that convert light into heat kneaded into the core. In addition, there have been reports of the production of wool fabric with photothermal properties by adsorbing vanadium ions with photothermal properties onto wool (Patent Document 1).

[0003] On the other hand, melanin is a yellow to black pigment formed in animals and plants, and is known to have functions such as UV absorption, radical scavenging, and antioxidant properties. Because melanin is a highly safe substance derived from living organisms, it is widely used in cosmetics, foods, plastic products, etc., as a UV absorber, antioxidant, and pigment.

[0004] In living organisms, melanin is biosynthesized when tyrosine, a substrate compound, is oxidized by the catalytic action of tyrosinase, a melanin-producing enzyme, to produce dihydroxyindole compounds (5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, etc.) via dopa and dopaquinone, and these dihydroxyindole compounds then polymerize. When using melanin as a dye, it is difficult to penetrate and dye the object to be dyed by using melanin itself, which is a high molecular weight compound. Therefore, low molecular weight compounds such as melanin precursors, dihydroxyindole compounds, are used as dyes to allow melanin to form inside the object to be dyed. For example, a method for dyeing cotton fibers and human gray hair using a dye solution containing 5,6-dihydroxyindole (Patent Document 2), and a method for dyeing fibers with an aqueous solution containing tyrosinase and tyrosine (Patent Document 3) have been reported. According to Patent Documents 2 and 3, cotton fibers dyed black to dark brown can be obtained, but the function of the melanin produced within the fibers is completely unknown.

[0005] (Patent Document 1) Japanese Unexamined Patent Publication No. 2021-42480 (Patent Document 2) Japanese Unexamined Patent Publication No. 2011-46658 (Patent Document 3) Japanese Unexamined Patent Publication No. Hei 9-87977

[0006] The present invention relates to the following 1) and 2): 1) A method for producing processed fibers, comprising step 1 of cationizing fibers and step 2 of applying a melanin precursor solution to the cationized fibers. 2) Processed fibers comprising cation-containing fibers and melanin. Detailed description of the invention

[0007] In functional clothing, there is a demand for materials made from natural fibers, particularly for consumers with sensitive skin. The inventors have discovered that by using a melanin precursor and generating melanin within the fibers, such as natural fibers, it is possible to impart functionality, such as photothermal heating properties, to the fibers. However, they have found that there are problems with the low fixation of the melanin precursor to the fibers, resulting in low productivity, and furthermore, the low fastness to friction after dyeing due to the melanin being generated near the surface of the fiber. Friction fastness is a quality indicator of dyed textile products, representing their resistance to discoloration, fading, and color transfer. Therefore, the present invention relates to a method for producing processed fibers with functionality such as photothermal heating properties, which not only has high penetration of the melanin precursor into the fibers and high fixation of the generated melanin, but also improves the friction fastness after dyeing.

[0008] The inventors have discovered that by treating fibers with a cationizing agent and then applying a melanin precursor solution to the fibers, the penetration of the melanin precursor into the fibers is promoted, and it polymerizes inside the fibers to become melanin, thus fixing it in place. This imparts high functionality to the fibers while improving the friction fastness after dyeing.

[0009] According to the present invention, it is possible to improve the penetration of melanin precursors into fibers and the fixation of the generated melanin, thereby enabling the productive acquisition of processed fibers with robustness against friction and functional properties such as photothermal heat generation.

[0010] The present invention provides a method for producing processed fibers comprising a step 1 of cationizing the fibers and a step 2 of applying a melanin precursor solution to the cationized fibers. The present invention has found that by performing the cationization treatment in step 1 on the fibers prior to step 2, the penetration of the melanin precursor into the fibers is promoted, and it becomes fixed by polymerization into melanin inside the fibers, thereby imparting functionality such as photothermal performance to the fibers while improving the friction fastness after dyeing. The reason for obtaining such effects is not clear, but it is presumed that in the method of the present invention, the cationization treatment makes it easier for the melanin precursor to be incorporated into the inside of the fibers, and melanin, which is an oxidized polymer, is produced inside the fibers rather than on the surface of the fibers.

[0011] <Step 1> Step 1 is a step of cationizing the fibers. In this specification, examples of fibers include natural fibers such as cotton, silk, hemp, wool, paper mulberry, mitsumata, and ganpi; synthetic fibers such as nylon, polyester, and acrylic; cellulose-based regenerated fibers such as rayon; and cellulose fibers such as paper. Among these, natural fibers such as cotton, silk, hemp, wool, paper mulberry, mitsumata, and ganpi are preferred, and cotton, silk, hemp, and wool are more preferred. From the viewpoint of strength as clothing, the fiber thickness is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. Furthermore, from the viewpoint of ease of penetration of melanin precursors, the fiber thickness is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0012] In the present invention, the cationization treatment is preferably carried out by adsorbing or reacting a cationizing agent onto the fibers in the presence of an alkaline compound, from the viewpoint of sufficiently imparting cations to the fibers. The cationizing agent is not particularly limited, and various compounds capable of introducing cationic groups can be used. Examples include quaternary ammonium salts, pyridinium salts, diallyldialkylammonium salt polymers, etc. Examples of quaternary ammonium salts include N-alkyl-N,N,N-trimethylammonium such as lauryltrimethylammonium, cetyltrimethylammonium, stearyltrimethylammonium, oleyltrimethylammonium, N,N-dialkyl-N,N-dimethylammonium, alkylbenzyldimethylammonium, glycidyltrialkylammonium, and 3-chloro-2-hydroxypropyltrialkylammonium, as well as other halide salts of quaternary ammonium. The number of carbon atoms in the alkyl portion is preferably 8 to 18, more preferably 12 to 18. Examples of pyridinium salts include halide salts such as pyridinium chlorides such as dodecylpyridinium and hexadecylpyridinium. Examples of diallyldialkylammonium salt polymers include polydiallyldimethylammonium chloride and polydiallylmethylethylammonium chloride. The cationizing agent can be used alone or in combination of two or more. In particular, from the viewpoint of reactivity and adsorption to fibers, it is preferable to use a quaternary ammonium salt type cationizing agent, and it is more preferable to use at least one cationizing agent selected from dialkyl(C12-C18)dimethylammonium chloride, lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, and benzalkonium chloride.

[0013] Examples of alkali compounds include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide; tertiary amine compounds such as trimethylamine and triethylamine; alkali metal bicarbonates such as sodium bicarbonate; and alkali metal carbonates such as sodium carbonate and potassium carbonate. Among these, sodium hydroxide, which is commonly used in the cationization treatment of fibers, is preferred.

[0014] In cationization treatment, a treatment solution (hereinafter also referred to as "cationic aqueous solution") containing a cationizing agent and, if necessary, an alkaline compound is prepared, and the fibers are immersed in this treatment solution to adsorb or react with the cationizing agent on the fibers. Examples of solvents used in the treatment solution include water, ethanol, lower alcohols such as isopropyl alcohol, buffer solutions such as phosphate buffer and acetate buffer. One or more solvents can be used. Among these, water, ethanol, or mixtures thereof are preferred from the viewpoint of cost. From the viewpoint of preservation, the ethanol concentration is preferably 5% by mass or more, more preferably 10% by mass or more, and also preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less in the solvent.

[0015] In the cationization treatment, the concentration of the cationizing agent in the treatment solution is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, in the treatment solution containing the cationizing agent and optionally an alkaline compound, from the viewpoint of sufficiently imparting cations to the fibers and promoting the permeability and fixation of the melanin precursor. Furthermore, from the viewpoint of cost, it is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. The concentration of the cationizing agent is preferably 0.05 to 3% by mass, more preferably 0.1 to 2% by mass, and even more preferably 0.2 to 1.5% by mass, in the treatment solution containing the cationizing agent and optionally an alkaline compound.

[0016] Furthermore, when using an alkali compound, its concentration is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, in the treatment solution containing the cationizing agent and the alkali compound, from the viewpoint of sufficiently imparting cations to the fibers. Also, from the viewpoint of safety and fiber modification, it is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 1% by mass or less. The concentration of the alkali compound is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 0.5 to 1% by mass, in the treatment solution containing the cationizing agent and the alkali compound.

[0017] In the cationization treatment, the bath ratio of the treatment solution containing the cationizing agent and, if necessary, an alkaline compound, i.e., the mass ratio of the treatment solution to the fibers, is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more, from the viewpoint of ease of immersion, and preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less, from the viewpoint of cost. The mass ratio of the treatment solution to the fibers is preferably 4 to 30, more preferably 6 to 25, and even more preferably 8 to 20.

[0018] The temperature at which the fibers are treated with the cationizing agent is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher, from the viewpoint of sufficiently imparting cations to the fibers and promoting the penetration and fixation of the melanin precursor. From the viewpoint of productivity, it is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower.

[0019] The processing time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more, from the viewpoint of sufficiently imparting cations to the fibers and promoting the penetration and fixation of the melanin precursor. From the viewpoint of productivity, it is preferably within 3 hours, more preferably within 2 hours, and even more preferably within 1 hour. After the cationization treatment, washing with water, drying, etc., are performed as necessary.

[0020] The cationized fibers obtained in this process have a cationization degree (amount of cation introduced relative to the mass of the fiber) that is preferably 0.008 mmol / g or more, more preferably 0.01 mmol / g or more, even more preferably 0.02 mmol / g or more, and even more preferably 0.03 mmol / g or more, from the viewpoint of improving the melanin precursor yield described later. From the viewpoint of cost, it is preferably 0.20 mmol / g or less, more preferably 0.15 mmol / g or less, and even more preferably 0.10 mmol / g or less. The cationization degree (amount of cation introduced relative to the mass of the fiber) is preferably 0.008 mmol / g or more and 0.20 mmol / g or less, more preferably 0.01 mmol / g or more and 0.15 mmol / g or less, even more preferably 0.02 mmol / g or more and 0.15 mmol / g or less, and even more preferably 0.03 mmol / g or more and 0.10 mmol / g or less.

[0021] <Step 2> Step 2 is the step of applying a melanin precursor solution to the cationized fiber. Since the melanin precursor is a compound that polymerizes and is converted to melanin by air oxidation, in this step the melanin precursor penetrates the fiber and then polymerizes inside the fiber to become melanin. Examples of melanin precursors in the present invention include tyrosine, dopa, dopaquinone, and dihydroxyindole compounds. One or more combinations of melanin precursors can be used. In particular, from the viewpoint of efficiently polymerizing to become melanin and exhibiting functionalities such as photothermal performance, one or more selected from tyrosine and dihydroxyindole compounds are preferred, and one or more selected from dihydroxyindole compounds are more preferred. Examples of dihydroxyindole compounds include compounds represented by the following general formula (1) or salts thereof.

[0022]

[0023] (In the formula, the dashed line indicates the presence or absence of a π bond. R 1 R represents a hydroxyl group or an acetoxy group. 2 R represents a hydrogen atom, or -COOR (where R is a hydrogen atom, a methyl group, or an ethyl group). 3(This represents a hydrogen atom, an acetyl group, a methyl group, or an ethyl group.)

[0024] From the viewpoint of ease of penetration into fibers, it is preferable that the dashed line portion in general formula (1) contains a π bond. Also, from the same viewpoint, in general formula (1), R 1 is preferably a hydroxyl group, R 2 R is preferably a hydrogen atom or -COOR (where R is a hydrogen atom, a methyl group, or an ethyl group), more preferably a hydrogen atom or -COOH. 3 Preferably, it is a hydrogen atom.

[0025] Examples of the compound represented by the general formula (1) include 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, methyl 5,6-dihydroxyindole-2-carboxylate, ethyl 5,6-dihydroxyindole-2-carboxylate, N-methyl-5,6-dihydroxyindole, N-methyl-5,6-dihydroxyindole-2-carboxylic acid, N-ethyl-5,6-dihydroxyindole, N-ethyl-5,6-dihydroxyindole-2-carboxylic acid, N-acetyl-5,6-dihydroxyindole, N-acetyl-5,6-dihydroxyindole-2-carboxylic acid, 5-acetoxy-6-hydroxyindole, 5-acetoxy-6-hydroxyindole-2-carboxylic acid, 5,6-dihydroxyindoline, 5,6-dihydroxyindoline-2-carboxylic acid, methyl 5,6-dihydroxyindoline-2-carboxylate, ethyl 5,6-dihydroxyindoline-2-carboxylate, N-methyl-5,6-dihydroxyindoline, N-methyl-5,6-dihydroxyindoline-2-carboxylic acid, N-ethyl-5,6-dihydroxyindoline, N-ethyl-5,6-dihydroxyindoline-2-carboxylic acid, N-acetyl-5,6-dihydroxyindoline, N-acetyl-5,6-dihydroxyindoline-2-carboxylic acid, 5-acetoxy-6-hydroxyindoline, 5-acetoxy-6-hydroxyindoline-2-carboxylic acid, etc. Examples of the salt of the compound represented by the general formula (1) include hydrochloride, hydrobromide, sulfate, phosphate, acetate, propionate, lactate, citrate of the compound, etc. Among them, from the viewpoint of availability, hydrobromide is preferable. In the general formula (1), when R 2 is -COOH, examples of the salt of the compound represented by the general formula (1) include its carboxylate (R 2 is -COO - X + [[ID={8]]X + is a cation such as an alkali metal ion such as Na + , K + , an alkaline earth metal ion such as Ca + , Mg + , or an ammonium ion).

[0026] From the viewpoint of ease of penetration into fibers, the compound represented by general formula (1) or its salt is preferably one or more selected from the group consisting of 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, 5,6-dihydroxyindoline, 5,6-dihydroxyindoline-2-carboxylic acid, and salts thereof; more preferably one or more selected from the group consisting of 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, and 5,6-dihydroxyindoline hydrobromide; even more preferably one or two selected from the group consisting of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid; and even more preferably a combination of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid.

[0027] When 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid are used in combination, from the viewpoint of providing higher photothermal performance and other functionalities, and efficiently imparting functionality, the molar ratio is preferably in the range of 50:50 to 99:1, more preferably in the range of 80:20 to 99:1, and even more preferably in the range of 85:15 to 95:5. The molar ratio of 5,6-dihydroxyindole to 5,6-dihydroxyindole-2-carboxylic acid can be quantified by reverse-phase HPLC.

[0028] The melanin precursor can be commercially available. Alternatively, it can be obtained by previously reported enzymatic or chemical methods. For example, it can be produced by referring to the method described in Japanese Patent Publication No. 4578221 as an enzymatic method, or by referring to the method described in Japanese Patent Publication No. 7212628 as a chemical method.

[0029] As the solvent used in the melanin precursor solution, from the viewpoint of solubilizing the melanin precursor, for example, water; lower alcohols such as ethanol and isopropyl alcohol; lower molecular weight diols and triols having 6 or less carbon atoms such as ethylene glycol, propylene glycol, 1,3-butylene glycol, and glycerin; buffer solutions such as phosphate buffer solution and acetate buffer solution, etc. can be mentioned. The solvent can be used alone or in combination of two or more. Among them, from the viewpoint of cost, water, ethanol or a mixture thereof is preferable. The ethanol concentration is preferably 5% by mass or more, more preferably 10% by mass or more in the solvent, and preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less from the viewpoint of antiseptic property.

[0030] The content of the melanin precursor in the melanin precursor solution is preferably 0.05 mM or more, more preferably 0.1 mM or more, still more preferably 1 mM or more from the viewpoints of imparting functionality such as photothermal performance, improving the melanin precursor yield described later, and improving the rubbing fastness. Also, the upper limit is not particularly limited, but from the viewpoint of cost for functionality, it is preferably 120 mM or less, more preferably 67 mM or less, still more preferably 40 mM or less. The content of the melanin precursor in the melanin precursor solution is preferably 0.05 to 120 mM, more preferably 0.1 to 67 mM, still more preferably 1 to 40 mM.

[0031] In addition to the melanin precursor and the solvent, the melanin precursor solution can appropriately contain additives such as oxidase such as tyrosinase that catalyzes the oxidation reaction of the melanin precursor, surfactant, stabilizer, buffer, fragrance, feel improver, chelating agent, solubilizing agent, preservative, etc. as needed. Also, in order to control the oxidation rate of the melanin precursor, antioxidants such as sodium ascorbate and sodium sulfite can be appropriately contained. The content of the additive can be appropriately set within a range not impairing the object of the present invention.

[0032] The pH (20 °C) of the melanin precursor solution is preferably 2 or more, more preferably 4 or more, still more preferably 6 or more, from the viewpoint of promoting the oxidation of the melanin precursor, and preferably 13 or less, more preferably 12 or less, still more preferably 11 or less, from the viewpoint of suppressing the decomposition of melanin. The pH (20 °C) of the melanin precursor solution is preferably from 2 to 13, more preferably from 4 to 12, still more preferably from 6 to 11.

[0033] In this specification, applying a melanin precursor solution to a cationized fiber means bringing the melanin precursor solution into contact with the fiber, and the means of applying the melanin precursor solution is not particularly limited, and any of methods such as immersing the fiber in the melanin precursor solution, applying the melanin precursor solution directly to the fiber, and spraying the melanin precursor solution onto the fiber may be used. Preferably, it is a method of immersing the fiber in the melanin precursor solution. At this time, it may be under static conditions or under stirring. Also, the applying means may be repeated a plurality of times, for example, 2 times or 3 times.

[0034] The amount of the melanin precursor solution used may be an amount that can impart functionality such as photothermal performance to the fiber, and can be appropriately determined according to its usage form. For example, in the method of immersing the fiber in the melanin precursor solution, the bath ratio of the melanin precursor solution, that is, the mass ratio of the melanin precursor solution / fiber, is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, from the viewpoints of ease of immersion, improving the melanin precursor yield described later, and improving the rubbing fastness, and preferably 100 or less, more preferably 80 or less, still more preferably 60 or less, from the viewpoint of cost. The mass ratio of the melanin precursor solution / fiber is preferably from 4 to 100, more preferably from 6 to 80, still more preferably from 8 to 60.

[0035] The application time is preferably 0.5 hours or more, more preferably 1 hour or more, still more preferably 2 hours or more, from the viewpoint of sufficiently permeating the melanin precursor into the fiber and sufficiently oxidatively polymerizing it inside the fiber to form melanin, and preferably within 24 hours, more preferably within 10 hours, still more preferably within 2 hours, from the viewpoint of productivity.

[0036] Furthermore, regarding the applicable temperature, from the viewpoint of sufficiently penetrating the melanin precursor into the fibers and allowing sufficient oxidative polymerization to occur inside the fibers to form melanin, it is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher. Also, from the viewpoint of operability and safety, it is preferably 90°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower.

[0037] In specific embodiments of the present invention, carrying out step 2 under anaerobic conditions is preferable from the viewpoint of allowing the melanin precursor to penetrate the fibers more thoroughly, to oxidatively polymerize within the fibers to form melanin, and to exhibit high functionality. Furthermore, when step 2 is carried out under anaerobic conditions, it is preferable to include a step of promoting oxidation by leaving the material exposed to air, as described later.

[0038] By performing this process, the melanin precursor penetrates sufficiently into the interior of the fiber and then polymerizes to form melanin, thereby improving its fixation properties. In the present invention, the melanin precursor yield is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more, from the viewpoint of improving friction fastness. The "melanin precursor yield" referred to here can be calculated by the following formula (1), where A is the concentration of the melanin precursor in the solution before immersing the fiber, and B is the concentration of the melanin precursor in the solution after immersing the fiber and after step 2. [1 - (B / A)] × 100 (1)

[0039] In the present invention, after step 2, a step of performing an oxidation-promoting treatment to accelerate the oxidation of the melanin precursor may be included. The oxidation-promoting treatment may be performed by applying the melanin precursor solution to the fibers and leaving it in the air, or by contacting it with an oxidizing agent, oxidation catalyst, metal salt, buffer solution, etc.

[0040] The duration of the oxidation-promoting treatment is preferably 15 minutes or more, more preferably 30 minutes or more, and even more preferably 1 hour or more, from the viewpoint of sufficiently oxidizing the melanin precursor, and preferably within 10 hours, more preferably within 5 hours, and even more preferably within 2 hours, from the viewpoint of productivity.

[0041] The temperature of the fibers during the oxidation acceleration treatment is preferably 5°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher, from the viewpoint of the ease with which the melanin precursor is oxidized, and from the viewpoint of operability and safety, it is preferably 90°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower.

[0042] After applying the melanin precursor solution to the fibers, and after performing an oxidation-promoting treatment to accelerate the oxidation of the melanin precursor, it is preferable to wash and dry the fibers as needed. This removes the melanin generated from the melanin precursor on the fiber surface and suppresses color fading due to friction.

[0043] The present invention provides fibers with photothermal heat generation, antibacterial properties, deodorizing properties, and antistatic properties, resulting in processed fibers with such functionalities. Processed fibers with functionalities such as photothermal heat generation according to the present invention have high abrasion fastness. Therefore, processed fibers according to the present invention are useful for clothing and the like.

[0044] The processed fiber of the present invention contains cation-containing fibers and melanin. The amount of cation introduced relative to the mass of the fiber in the processed fiber of the present invention (degree of cationization) is preferably 0.008 mmol / g or more and 0.20 mmol / g or less, more preferably 0.01 mmol / g or more and 0.15 mmol / g or less, even more preferably 0.02 mmol / g or more and 0.15 mmol / g or less, and even more preferably 0.03 mmol / g or more and 0.10 mmol / g or less. Furthermore, the content of melanin in terms of melanin precursor relative to the mass of the fiber in the processed fiber of the present invention is preferably 0.001 g / g or more, more preferably 0.002 g / g or more and 0.05 g / g or less, and even more preferably 0.01 g / g or more and 0.025 g / g or less.

[0045] With regard to the embodiments described above, the present invention further discloses the following methods for manufacturing processed fibers and processed fibers.

[0046] <1> A method for producing processed fibers, comprising step 1 of cationizing fibers and step 2 of applying a melanin precursor solution to the cationized fibers.

[0047] <2> The method for producing processed fibers according to <1>, wherein the melanin precursor of step 2 contains one or more compounds selected from tyrosine and dihydroxyindoles represented by the following general formula (1) or salts thereof.

[0048]

[0049] (In the formula, the dashed line indicates the presence or absence of a π bond. R 1 R represents a hydroxyl group or an acetoxy group. 2 R represents a hydrogen atom, or -COOR (where R is a hydrogen atom, a methyl group, or an ethyl group). 3) represents a hydrogen atom, an acetyl group, a methyl group, or an ethyl group.) <3> A method for producing processed fibers according to <1> or <2>, wherein the melanin precursor of step 2 contains one or two selected from the group consisting of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid. <4> A method for producing processed fibers according to any one of <1> to <3>, wherein the content of the melanin precursor in the melanin precursor solution of step 2 is 0.05 mM or more. <5> A method for producing processed fibers according to any one of <1> to <4>, wherein the cationization treatment of step 1 is performed using a quaternary ammonium salt type cationizing agent. <6> A method for producing processed fibers according to any one of <1> to <5>, wherein step 2 is performed under anaerobic conditions, and thereafter an oxidation acceleration treatment step is included. <7> A method for producing processed fibers according to any one of <1> to <6>, wherein the cationization treatment of step 1 is performed in the presence of an alkaline compound. <8> A method for producing processed fibers according to any one of <1> to <7>, wherein in the cationization treatment of step 1, a treatment solution is used in which the concentration of the cationizing agent is 0.05 to 3% by mass. <9> A method for producing processed fibers according to <7> or <8>, wherein in the cationization treatment of step 1, a treatment solution is used in which the concentration of the alkali compound is 0.1 to 5% by mass. <10> A method for producing processed fibers according to any one of <1> to <9>, wherein in the cationization treatment of step 1, the mass ratio of the treatment solution containing the cationizing agent to the fiber is 4 to 30. <11> A method for producing processed fibers according to any one of <1> to <10>, wherein the cationization treatment of step 1 is performed at a temperature of 40 to 100°C. <12> A method for producing processed fibers according to any one of <1> to <11>, wherein the cationization treatment of step 1 is performed for 5 minutes to 3 hours. <13> The method for producing processed fibers according to any one of <1> to <12>, wherein the amount of cation introduced relative to the mass of the fiber is 0.008 mmol / g or more and 0.20 mmol / g or less in the fiber obtained by the cationization treatment in step 1. <14> The method for producing processed fibers according to any one of <1> to <13>, wherein the pH of the melanin precursor solution in step 2 at 20°C is 2 to 13. <15> The method for producing processed fibers according to any one of <1> to <14>, wherein the amount of melanin precursor solution used in step 2 is 4 to 100 by mass relative to the fiber.<16> A method for producing processed fibers according to any one of <1> to <15>, wherein the time for applying the melanin precursor solution in step 2 is 0.5 hours or more and 24 hours or less. <17> A method for producing processed fibers according to any one of <1> to <16>, wherein the temperature at which the melanin precursor solution in step 2 is applied is 5°C or more and 90°C or less. <18> A method for producing processed fibers according to any one of <1> to <17>, wherein the melanin precursor yield in step 2 is 50% or more.

[0050] <19> Processed fiber containing cation-containing fibers and melanin. <20> Processed fiber according to <19>, wherein the amount of cation introduced relative to the mass of the fiber is 0.008 mmol / g or more and 0.20 mmol / g or less. <21> Processed fiber according to <19> or <20>, wherein the amount of melanin in terms of melanin precursor relative to the mass of the fiber is 0.001 g / g or more.

[0051] <Experimental Materials> - Cotton fibers: Standard antimicrobial testing fabric obtained from the Japan Textile Evaluation Technology Council was used. - Wool: Wool serge fabric purchased from Irozome Co., Ltd. was used. - Dihydroxyindole (DHI): Prepared according to the method described in prior art (Patent No. 7212628, Kao Corporation). Details are described in "Method for Preparing DHI" below. • Cationizing agent Cotamine D2345P (Kao): Dialkyl (C12-C18) dimethylammonium chloride Cotamine 24P (Kao): Lauryltrimethylammonium chloride Cotamine 60W (Kao): Cetyltrimethylammonium chloride Cotamine 86W (Kao): Stearyltrimethylammonium chloride Sanizol C (Kao): Benzalkonium chloride PDADMAC: Poly(diallyldimethylammonium chloride) (Sigma 409014) CHPTAC: (3-chloro-2-hydroxypropyl)trimethylammonium chloride (Tokyo Chemical Industries C1180) GTAC: Glycidyltrimethylammonium chloride (Tokyo Chemical Industries G0476)

[0052] <Preparation Method of DHI> A stirrer with crescent-shaped blades was set up in a 5L glass three-necked flask to serve as a reactor. 2L of water was added to the reactor, and nitrogen gas was vented from the top of the flask. DOPA was added to the reactor to a concentration of 0.33 wt% and dissolved by stirring at 200 rpm. At this time, the liquid temperature was adjusted to 35°C using a water bath. An oxidizing agent solution was prepared by dissolving 16.8 wt% potassium hexacyanoferrate(III) and 7.2 wt% potassium bicarbonate in water. 0.288 mL of the oxidizing agent solution was added to the reactor containing the DOPA aqueous solution, and the reaction was carried out for 4 hours to obtain an aqueous DHI solution. The pH of the aqueous DHI solution was adjusted to 5.0 by adding a 10 wt% phosphoric acid solution. The following operations were performed in a glove box where the oxygen concentration was kept below 0.1% by venting with nitrogen. The aqueous DHI solution was filtered through a PES 0.2 μm filter. A filtered DHI aqueous solution was added to a 5L glass bottle, followed by the addition of 2L of ethyl acetate as an extractant. The solution was stirred by shaking the glass bottle by hand to perform the extraction. The glass bottle was allowed to stand, and 1.5L of the separated upper layer (ethyl acetate layer) was collected in another glass bottle. 0.7L of washing water (salt concentration: 8.33 wt%, dipotassium hydrogen phosphate / potassium dihydrogen phosphate (mass ratio) = 5.12) containing dipotassium hydrogen phosphate and potassium dihydrogen phosphate dissolved in water was added to this water, and the solution was stirred by shaking the glass bottle by hand to perform the washing. The glass bottle was allowed to stand, and 1.0L of the separated upper layer (ethyl acetate layer) was collected in a round-bottom flask. The collected ethyl acetate layer was completely evaporated using an evaporator (water bath temperature 45°C). 20 wt% ethanol was added to the dried material to adjust the concentration to 1 wt% DHI. Further adjustment to pH 8 by adding 6N sodium hydroxide aqueous solution dropwise was performed to obtain a 1% DHI solution.

[0053] <Method for cationization treatment of fiber pieces> A cation aqueous solution (treatment solution) with the composition shown in Table 1 was prepared, and the treatment solution was added to the fiber pieces cut to approximately 5 x 5 cm in an amount 20 times the mass (bath ratio 20), and left to stand at 70°C for 1 hour. After treatment, the fibers were thoroughly washed with tap water and air-dried.

[0054]

[0055] <Measurement of Cationization Degree> The amount of cation introduced into the fiber (degree of cationization) was measured from the change in mass of the fiber sample before and after cationization treatment.

[0056] <Fiber Treatment Method> The following operations were carried out using a glove box to avoid contact between the DHI solution and fiber samples and oxygen. A 0.05 M sodium phosphate buffer (pH 9.0) containing DHI at the concentrations shown in Tables 2 and 3 was prepared and used as the DHI treatment solution. The DHI treatment solution was added to fibers measuring approximately 15 x 15 cm to a bath ratio of 40 and left to stand at room temperature for 3 hours. After treatment, the fibers were removed to air, left to stand for 30 minutes, thoroughly washed with tap water, and air-dried. The DHI concentration in the solution after fiber immersion was analyzed using the method described in <Method for Measuring the Concentration of Melanin Precursors>, and the DHI yield was calculated.

[0057] <Color Measurement Method> The L, a, and b values ​​of the above fibers were measured using a colorimeter (CR-400, manufactured by Konica Minolta). The difference in L, a, and b values ​​between the dyed and undyed fibers was defined as Δ, and the color difference ΔE = {(ΔL)} 2 + (Δa) 2 + (Δb) 2} 0.5 The result was calculated.

[0058] <Measurement of Photothermal Heat Generation Temperature> Evaluation was conducted according to the light absorption heat retention test (Boken standard BQE A 036). The fibers were placed 30 cm away from a reflector lamp PRF300W (Iwasaki Electric) and irradiated with light at 100 V for 10 minutes (illuminance of the irradiated surface: 12 klx). A thermocouple was placed on the back of the fiber and the temperature rise was measured from the temperature difference between the temperature before and after irradiation. The photothermal heat generation temperature was calculated as (temperature rise of treated fabric) - (temperature rise of untreated fabric).

[0059] <Antibacterial Performance Evaluation Method> The antibacterial activity of the fibers was evaluated according to JIS L1902:2015 bacterial suspension absorption method (quantitative test). Staphylococcus aureus NBRC12732 was used as the bacterial species, and the bacterial count was measured by pour plate culture. The antibacterial activity was calculated using the following formula.

[0060] Bacterial count before culturing on standard cotton cloth before treatment: C0 Bacterial count after 18 hours of culturing on standard cotton cloth before treatment: C tBacterial count before culture in processed cotton fabric before treatment: T0 Bacterial count after 18 hours of culture in processed cotton fabric before treatment: T t Antibacterial activity = (LogC t -LogC0)-(LogT t -LogT0) If LogC0 > LogT0, the following calculation was performed: Antimicrobial activity = LogC t -LogT t

[0061] <Antistatic Evaluation Method> Following JIS L 1094 Method A, a voltage of 10 kV was applied to the test piece for 30 seconds, and the time it took for the charged voltage to be halved (half-life) was measured. In addition, following JIS L 1094 Method B, the frictional voltage was measured when the target fabric was cotton.

[0062] <Abrasion Fastness Measurement> The abrasion fastness of DHI-treated fabric in dry and wet conditions was evaluated according to JIS L 0849 Type II.

[0063] <Method for Measuring the Concentration of Melanin Precursors> 5,6-dihydroxyindole (DHI) was measured as a melanin precursor. Analytical samples were prepared using the following procedure and analyzed by liquid chromatography (HPLC). (Preparation of Analytical Samples) 0.2 mL of the sample was added to 0.5 mL of a 0.1 w / v% phosphoric acid aqueous solution containing 3 w / v% sodium ascorbate and mixed. Then, 9 mL of 0.1 w / v% phosphoric acid was mixed to prepare the analytical sample. (HPLC Conditions) Column: L-column ODS 150-4.6 (5 μm) Mobile Phase: The mixing ratio of mobile phase A and mobile phase B was controlled under the following conditions: Mobile Phase A: 0.1 w / v% phosphoric acid aqueous solution containing 0.1 mol / L potassium dihydrogen phosphate Mobile Phase B: 70% methanol aqueous solution

[0064] Time [min] Mobile Phase A [%] Mobile Phase B [%] 0-5 100 0 5-20 100→0 100→0 Linear Gradient Linear Gradient 20-25 0 100 25-30 100 0

[0065] Flow rate: 1 mL / min; Detection wavelength: 280 nm; Temperature: 40°C

[0066] Examples 1-8, Comparative Example 1, and Reference Example 1: DHI treatment was performed on cationized cotton cloths with the compositions shown in Table 2, and the photothermal performance was evaluated.

[0067]

[0068] In cationized cotton fabrics, the DHI yield was significantly improved compared to untreated cotton fabrics. Furthermore, cationized cotton fabrics exhibited high photothermal performance even with low concentrations of DHI.

[0069] In Example 9 and Reference Example 2, cotton fabrics treated with cationization using the compositions shown in Table 3 were subjected to DHI treatment, and their antibacterial performance was evaluated.

[0070]

[0071] Cationic treated cotton fabric exhibits high antibacterial performance even with low concentrations of DHI treatment.

[0072] In Example 10, Comparative Example 2, and Reference Example 3, wool cloths treated with cationization using the compositions shown in Table 2 were subjected to DHI treatment, and their antistatic performance was evaluated.

[0073]

[0074] Wool fabrics treated with cationization exhibit superior antistatic properties.

[0075] Examples 11-13 and Reference Example 4: Cotton cloth and cationic cotton were given photothermal properties at various DHI concentrations, and their abrasion fastness was evaluated.

[0076]

[0077] In DHI-treated cotton fabrics, cationized cotton fabrics showed improved friction fastness when given photothermal properties equivalent to those of regular cotton fabrics.

Claims

1. A method for producing processed fibers, comprising step 1 of cationizing fibers and step 2 of applying a melanin precursor solution to the cationized fibers.

2. The method for producing processed fibers according to claim 1, wherein the melanin precursor in step 2 contains tyrosine and one or more compounds selected from those represented by the following general formula (1) or salts thereof. (In the formula, the dashed line indicates the presence or absence of a π bond. R 1 R represents a hydroxyl group or an acetoxy group. 2 R represents a hydrogen atom, or -COOR (where R is a hydrogen atom, a methyl group, or an ethyl group). 3 (This represents a hydrogen atom, an acetyl group, a methyl group, or an ethyl group.) 3. The method for producing processed fibers according to claim 1 or 2, wherein the melanin precursor of step 2 contains one or two selected from the group consisting of 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid.

4. A method for producing processed fibers according to any one of claims 1 to 3, wherein the content of melanin precursor in the melanin precursor solution of step 2 is 0.05 mM or more.

5. A method for producing processed fibers according to any one of claims 1 to 4, wherein the cationization treatment in step 1 is performed using a quaternary ammonium salt type cationizing agent.

6. A method for producing processed fibers according to any one of claims 1 to 5, comprising carrying out step 2 under anaerobic conditions, followed by an oxidation acceleration treatment step.

7. A method for producing processed fibers according to any one of claims 1 to 6, wherein the cationization treatment in step 1 is carried out in the presence of an alkaline compound.

8. A method for producing processed fibers according to any one of claims 1 to 7, wherein in the cationization treatment of step 1, a treatment solution is used in which the concentration of the cationizing agent is 0.05 to 3% by mass.

9. The method for producing processed fibers according to claim 7 or 8, wherein in the cationization treatment of step 1, a treatment solution having an alkali compound concentration of 0.1 to 5% by mass is used.

10. A method for producing processed fibers according to any one of claims 1 to 9, wherein in the cationization treatment of step 1, the mass ratio of the treatment solution containing the cationizing agent to the fibers is 4 to 30.

11. A method for producing processed fibers according to any one of claims 1 to 10, wherein the cationization treatment in step 1 is performed at a temperature of 40 to 100°C.

12. A method for producing processed fibers according to any one of claims 1 to 11, wherein the cationization treatment in step 1 is performed for 5 minutes or more and within 3 hours.

13. A method for producing processed fibers according to any one of claims 1 to 12, wherein the amount of cation introduced relative to the mass of the fiber is 0.008 mmol / g or more and 0.20 mmol / g or less, in the fibers obtained by the cationization treatment in step 1.

14. A method for producing processed fibers according to any one of claims 1 to 13, wherein the pH of the melanin precursor solution in step 2 at 20°C is 2 to 13.

15. A method for producing processed fibers according to any one of claims 1 to 14, wherein the amount of melanin precursor solution used in step 2 is 4 to 100 by mass relative to the fiber.

16. A method for producing processed fibers according to any one of claims 1 to 15, wherein the time for applying the melanin precursor solution in step 2 is 0.5 hours or more and 24 hours or less.

17. A method for producing processed fibers according to any one of claims 1 to 16, wherein the temperature at which the melanin precursor solution of step 2 is applied is 5°C or higher and 90°C or lower.

18. A method for producing processed fibers according to any one of claims 1 to 17, wherein when the concentration of the melanin precursor in the melanin precursor solution before immersing the fibers in step 2 is A, and the concentration of the melanin precursor in the melanin precursor solution after immersing the fibers and step 2 is B, the melanin precursor yield calculated by the following formula (1) is 50% or more. [1 - (B / A)] × 100 (1) 19. Processed fibers containing cations and melanin.

20. The processed fiber according to claim 19, wherein the amount of cation introduced relative to the mass of the fiber is 0.008 mmol / g or more and 0.20 mmol / g or less.

21. The processed fiber according to claim 19 or 20, wherein the content of melanin in terms of melanin precursors relative to the mass of the fiber is 0.001 g / g or more.

Images