Dyeing agent composition for regenerated collagen fibers

Abstract

A dyeing agent composition for regenerated collagen fibers, wherein the dyeing agent composition comprises a predetermined acidic dye (A) and water, and the regenerated collagen fibers comprise modified regenerated collagen fibers containing a specific component (B).

Description

Dyeing composition for regenerated collagen fibers

[0001] The present invention relates to a dye composition for use on regenerated collagen fibers.

[0002] Regenerated collagen fiber, a protein fiber, is suitable for use as a raw material for artificial hair because its properties are similar to those of human hair. Fibers used as raw materials for artificial hair must have high aesthetic qualities, such as color development and texture.

[0003] Protein fibers are generally colored by dyeing. A dyeing method in which protein fibers are immersed in an aqueous dye solution maintained at 70 to 100°C is used as the dyeing method. For example, Patent Document 1 describes a dyeing method in which wool is immersed in an aqueous dye solution containing an enzyme or the like to improve dye leveling, and then boiled at 100°C for 60 minutes. Patent Document 2 describes a method for dyeing protein fibers such as wool, cashmere, and silk thread at a temperature range of 70 to 90°C, which is lower than conventional dyeing temperatures, by using a specific treating agent. Furthermore, the example discloses an example in which wool is treated with a specific treating agent and then dyed at a dyeing temperature of 85°C.

[0004] (Patent Document 1) JP-A-2-216282 (Patent Document 2) JP-A-7-126988

[0005] The present invention relates to the following: [1] A dye composition for regenerated collagen fibers, the dye composition containing the following component (A) and water, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B). (A) An acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) where Mw is the molecular weight, the value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic sites (b) by Mw, [(a-b) / Mw], is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1500 to 15000, or a salt thereof; [2] A method for dyeing regenerated collagen fibers, the method comprising the step of applying a dye composition for regenerated collagen fibers to the regenerated collagen fibers, the dye composition containing the following component (A) and water, A method for dyeing regenerated collagen fibers, wherein the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (B): (A) an acid dye having sulfonic acid groups and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, of 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof; [3] colored modified regenerated collagen fibers comprising the following components (A) and (B):(A) an acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, (a-b) [(a-b) / Mw], where Mw is the molecular weight, of 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof. [4] A head ornament product comprising the fiber for colored head ornaments according to [3]. Detailed Description of the Invention

[0006] In conventional general dyeing methods for protein fibers, such as those disclosed in Patent Documents 1 and 2, even when special treatment agents are used, the dye cannot be sufficiently absorbed unless treatment is performed at a high temperature exceeding 70° C. Furthermore, when regenerated collagen fibers are dyed using a dyeing method that requires high-temperature conditions exceeding 70° C., there is a problem in that the regenerated collagen fibers shrink.

[0007] In order to solve the above problems, the present inventors attempted to dye regenerated collagen fibers at temperatures below 70°C. However, when the dyeing temperature was low, the chemical reaction between the regenerated collagen fibers and the dye became insufficient, resulting in a problem of reduced dye fastness.

[0008] Therefore, the only practical method for coloring regenerated collagen fibers is to disperse a pigment such as carbon black in the solution spinning process of the regenerated collagen fibers. However, with coloring methods using pigments, the range of colors that can be colored is limited to achromatic colors such as black and gray, as well as chromatic colors such as red, yellow, blue, and purple, but it is difficult to produce vivid colors such as deep black.

[0009] Therefore, the present invention relates to a dye composition for regenerated collagen fibers that uses a dye and has excellent fastness after dyeing.

[0010] The present inventors have found that a dye composition for regenerated collagen fibers containing specific modified regenerated collagen fibers, which uses a specific acid dye, can solve the above-mentioned problems. According to the present invention, a dye composition for regenerated collagen fibers using a dye that has excellent fastness after dyeing can be provided.

[0011] [Definitions] In this specification, "excellent dyeability of regenerated collagen fibers" means that there is a large change in color of regenerated collagen fibers before and after dyeing with a dye composition for regenerated collagen fibers. Furthermore, "fastness" means that there is little color change after the dyed regenerated collagen fibers are washed with water, a detergent, etc. The dyeability and fastness can be specifically evaluated by the methods described in the Examples.

[0012] [Dye composition for regenerated collagen fibers] The dye composition for regenerated collagen fibers of the present invention contains the following component (A) and water, and the regenerated collagen fibers include modified regenerated collagen fibers containing the following component (B). (A) An acid dye having sulfonic acid groups and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) where Mw is the molecular weight, the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) divided by Mw, [(a-b) / Mw], is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight-average molecular weight of 1,500 to 15,000, or a salt thereof. In the following description, the dye composition for regenerated collagen fibers may be simply referred to as the "composition (of the present invention)." Because the composition of the present invention has the above-mentioned configuration, even though it is a dye composition using a dye, it exhibits excellent fastness after dyeing of modified regenerated collagen fibers. The molecular weight of component (A) here means the molecular weight in an undissociated (acid) state. For example, even if at least a portion of the sulfonic acid groups in component (A) are in the form of sulfonate salts, the molecular weight of component (A) means the molecular weight in the undissociated sulfonic acid state, and does not include the molecular weight of the counter ion. Note that this also includes cases where component (A) has an onium group such as a quaternary ammonium group, and in such cases, the counter ion is similarly not included in the molecular weight.

[0013] The reason why the composition of the present invention exhibits the above-mentioned effects is unclear, but is presumed to be as follows. The regenerated collagen fibers to be dyed with the composition of the present invention include modified regenerated collagen fibers (hereinafter simply referred to as "modified regenerated collagen fibers") containing one or more compounds (B) selected from the group consisting of the components (B1) and (B2). Component (B) acts as a modifier for the regenerated collagen fibers. The composition of the present invention includes, as an acid dye, (A) an acid dye having a sulfonic acid group and satisfying at least one of the conditions (1) and (2) (hereinafter simply referred to as "component (A)" or "acid dye (A)"). Furthermore, within the modified regenerated collagen fibers, the structural moiety derived from component (B) interacts with the sulfonic acid group in the acid dye (A), which is thought to facilitate retention of the acid dye within the fiber, thereby further improving fastness. On the other hand, acid dyes with low molecular weights are generally preferred for hair dyeing, as they penetrate deeper into the hair to improve dyeability and fastness. In contrast, regenerated collagen fibers, which are the subject of dyeing with the composition of the present invention, differ from hair in that they do not have a barrier structure such as a cuticle that separates the inside and outside of the fiber. Therefore, if a low-molecular-weight acid dye is used, the color may easily fade after dyeing, and fastness may decrease.

[0014] In contrast, when the acid dye used in the composition of the present invention contains an acid dye that satisfies the above (1), it is thought that the large molecular weight makes it difficult for the color to fade after dyeing, and that this improves fastness. Furthermore, since the object to be dyed is regenerated collagen fibers, it is thought that, unlike hair, it is possible to dye the fibers by penetrating the acid dye into the interior of the fibers.

[0015] When the acid dye used in the composition of the present invention contains an acid dye that satisfies the above-mentioned condition (2), the following can be considered. The modified regenerated collagen fibers that are the target of dyeing with the composition of the present invention contain a structural portion derived from component (B) within the fibers. This structural portion contains an aromatic ring, and therefore, it is believed that the aromatic ring interaction provides a high affinity with acid dyes that also contain aromatic rings, improving the fixability of the acid dye. At the same time, however, this structural portion exhibits anionic properties. Therefore, when an acid dye containing only anionic moieties such as sulfonic acid groups or sulfonate ions is used, charge repulsion occurs between the structural portion derived from component (B) in the modified regenerated collagen fibers and the acid dye, which can be detrimental to the fixability of the acid dye to the fibers. However, when the acid dye contains cationic moieties or has a small number of sulfonic acid groups relative to the molecular weight, this charge repulsion is reduced. Therefore, it is believed that the contribution of aromatic ring interactions to the fixability of the acid dye to the modified regenerated collagen fibers exceeds charge repulsion, improving fixability and further improving dyeability and fastness. That is, when the molecular weight of the acid dye is Mw, if the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic sites (b) in the acid dye is divided by Mw ((a-b) / Mw) and the difference (a-b) is a predetermined value or less, the charge repulsion between the structural portion derived from component (B) in the modified regenerated collagen fiber and the acid dye can be sufficiently reduced, which is thought to improve the fixability of the acid dye to the modified regenerated collagen fiber and further improve dyeability and fastness. Note that the mechanism of action of the present invention is not limited to the above.

[0016] <Component (A): Acid Dye> Component (A) is an acid dye that, from the viewpoint of improving the fastness of the modified regenerated collagen fibers after dyeing, has sulfonic acid groups and satisfies at least one of the following (1) and (2): (1) molecular weight of 500 or more (2) where Mw is the molecular weight, the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) divided by Mw [(a-b) / Mw] is 0.0045 or less Component (A) may be an acid dye that satisfies only one of the above (1) and (2), or may be an acid dye that satisfies both the above (1) and (2).

[0017] The number (a) of sulfonic acid groups in component (A) may be 1 or more, and from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, it is preferably 1 or more, more preferably 2 or more, and preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and still more preferably 3 or less. That is, the number (a) of sulfonic acid groups in component (A) is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, even more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and still more preferably 2 or more and 3 or less. Here, "the number (a) of sulfonic acid groups in component (A)" means the number of sulfonic acid groups in component (A) in an undissociated (acid) state.

[0018] Component (A) may be at least partially in the form of a salt, and from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the salt preferably includes an ammonium salt or a metal salt, more preferably an ammonium salt or one or more metal salts selected from the group consisting of alkali metals, alkaline earth metals, and transition metals, more preferably an ammonium salt or one or more metal salts selected from the group consisting of potassium, sodium, calcium, iron, and chromium, even more preferably an ammonium salt or one or more metal salts selected from the group consisting of sodium, calcium, iron, and chromium, and even more preferably a sodium salt.

[0019] From the viewpoint of improving the robustness of the modified regenerated collagen fiber, it is preferable that component (A) further contains a cationic moiety, such as a quaternary ammonium cationic moiety or an iminium cationic moiety, and from the viewpoint of improving the robustness of the modified regenerated collagen fiber, it preferably contains an iminium cationic moiety.

[0020] The number of cationic sites (b) in component (A) may be 0. When component (A) has cationic sites, from the viewpoint of improving the robustness of the modified regenerated collagen fibers, the number of cationic sites (b) in component (A) is preferably 1 or more, more preferably 1 to 5, even more preferably 1 to 4, still more preferably 1 to 3, and even more preferably 1 to 2. The number of cationic sites (b) in component (A) is preferably 0 to 5, more preferably 0 to 4, even more preferably 0 to 3, still more preferably 0 to 2, and even more preferably 1 to 2.

[0021] From the viewpoint of improving the robustness of the modified regenerated collagen fiber, the difference (a-b) between the number of sulfonic acid groups (a) in component (A) and the number of cationic sites (b) in component (A) is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less.

[0022] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, it is preferable that component (A) has a small number of carboxy groups, and the number of carboxy groups in component (A) is preferably 2 or less, more preferably 1 or less, and even more preferably 0.

[0023] (Requirement (1)) The acid dye (A) that satisfies the above requirement (1) has a sulfonic acid group and a molecular weight of 500 or more.

[0024] When component (A) satisfies the above (1), from the viewpoint of improving the fastness of the modified regenerated collagen fibers after dyeing, the molecular weight of component (A) is preferably 520 or more, more preferably 540 or more, and is also preferably 1,500 or less, more preferably 1,200 or less, even more preferably less than 1,000, still more preferably 900 or less, even more preferably 800 or less, still more preferably 780 or less, and even more preferably 750 or less. When component (A) satisfies the above (1), the molecular weight of component (A) is preferably 500 or more and 1,500 or less, more preferably 500 or more and 1,200 or less, even more preferably 500 or more and less than 1,000, still more preferably 500 or more and 900 or less, even more preferably 500 or more and 800 or less, still more preferably 500 or more and 780 or less, still more preferably 520 or more and 750 or less, still more preferably 520 or more and 750 or less, and still more preferably 540 or more and 750 or less.

[0025] (Requirement (2)) When component (A) satisfies the above (2), the difference (a-b) between the number of sulfonic acid groups in component (A) and the number of cationic moieties in component (A) (b), divided by Mw, [(a-b) / Mw], where Mw is the molecular weight of component (A) (molecular weight in an undissociated (acid) state), is 0.0045 or less, preferably 0.0040 or less, more preferably 0.0035 or less, and even more preferably 0.0025 or less, from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber. This is because a smaller difference between the number of sulfonic acid groups and the number of cationic moieties per molecular weight of component (A) can reduce charge repulsion between the structural moiety derived from component (B) in the modified regenerated collagen fiber and the acid dye (A). Furthermore, when component (A) satisfies the above (2), [(a-b) / Mw] is preferably 0.0005 or more, more preferably 0.0010 or more. When component (A) satisfies the above (2), [(a-b) / Mw] is preferably 0.0005 or more and 0.0045 or less, more preferably 0.0005 or more and 0.0040 or less, even more preferably 0.0010 or more and 0.0035 or less, and still more preferably 0.0010 or more and 0.0025 or less.

[0026] When component (A) satisfies the above (2), the molecular weight Mw is preferably 250 or more, more preferably 280 or more, even more preferably 300 or more, and still more preferably 320 or more. It is also preferably 1,500 or less, more preferably 1,200 or less, even more preferably less than 1,000, still more preferably 900 or less, even more preferably 800 or less, even more preferably 780 or less, and still more preferably 750 or less. When component (A) satisfies the above (2), the molecular weight Mw is preferably 250 or more and 1,500 or less, more preferably 250 or more and 1,200 or less, even more preferably 250 or more and less than 1,000, still more preferably 250 or more and 900 or less, even more preferably 280 or more and 800 or less, even more preferably 280 or more and 780 or less, even more preferably 280 or more and 750 or less, still more preferably 300 or more and 750 or less, and still more preferably 320 or more and 750 or less.

[0027] Component (A) may satisfy both of (1) and (2) above, in which case the molecular weight of component (A) is 500 or more and [(a-b) / Mw] is 0.0045 or less. The preferred ranges of the molecular weight of component (A) and [(a-b) / Mw] are the same as those described above.

[0028] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the acid dye used as component (A) in the present invention is preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Green 25 (Color Index No. 61570), Acid Brown 13 (Color Index No. 10410), Acid Red 52 (Color Index No. 45100), Acid Black 1 (Color Index No. 20470), Acid Red 18 (Color Index No. 16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), Acid Red 73 (Color Index No.27290), Acid Blue 1 (Color Index No.42045), Acid Red 184 (Color Index No.15685), Acid Red 35 (Color Index No.18065), Acid Red 14 (Color Index No.14720), Food Red 6 (Color Index No.16155), Acid Orange 3 (Color Index No.10385), Acid Orange 24 (Color Index No.20170), Acid Violet 43 (Color Index No.60730), Acid Blue 62 (Color Index No.62045), Acid Red 88 (Color Index No.15620)、Acid Yellow 11(Color Index No.18820)、Acid Yellow 36(Color Index No.13065)、Acid Yellow 1(Color Index No.10316)、Acid Orange 7(Color Index No.15510)、Acid Orange 20(Color Index No.14600)、Acid Orange 6(Color Index No.14270)、Food Red 17(Color Index No.16035)、Acid Red 41(Color Index No.16290)、Acid Red 1(Color Index No.18050)、Acid Red 155(Color Index No.18130)、Acid Red 180(Color Index No.18736)、Acid Yellow 17(Color Index No.18965)、Acid Yellow 23(Color Index No.19140)、Acid Red 163(Color Index No.24790)、Food Black 2(Color Index No.27755)、Direct Orange 39(Color Index No.40215)、Acid Blue 7(Color Index No.42080)、Acid Green 9(Color Index No.42100)、Acid Green 22(Color Index No.42170)、Acid Blue 104(Color Index No.42735)、Acid Violet 9(Color Index No.45190)、Acid Red 50(Color Index No.45220)、Acid Violet 50(Color Index No.50325)、Acid Black 2(Color Index No.50420)、Acid Blue 80(Color Index No.61585)、Acid Blue 87(Color Index No.74180)、Acid Red 195(Color Index No.18760)、Acid Red 249(Color Index No.The acid dyes include one or more selected from the group consisting of Acid Red 18134, Acid Red 131, and Acid Red 337 (Color Index No. 17102). Details of these acid dyes are shown in Table 1.

[0029]

[0030] Component (A) is more preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Blue 7 (Color Index No. 42080), Acid Green 9 (Color Index No. 42100), Acid Blue 104 (Color Index No. 42735), and Acid Violet 50 (Color Index No. 50325).

[0031] Among the above, from the viewpoint of improving the robustness of the modified regenerated collagen fibers, component (A) more preferably contains one or more selected from the group consisting of Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Red 52 (Color Index No. 45100), Acid Blue 3 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), and Acid Blue 1 (Color Index No. 42045), which have a cationic moiety number (b) of 1 or more, and even more preferably contains one or more selected from the group consisting of Acid Blue 9 and Acid Red 52.

[0032] The dye composition may contain dyes other than component (A), but from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the content of component (A) in all acid dyes in the dye composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, but 100% by mass or less.

[0033] From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fibers, the content of component (A) in the dye composition is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, even more preferably 0.005% by mass or more, still more preferably 0.01% by mass or more, still more preferably 0.02% by mass or more, still more preferably 0.03% by mass or more, and still more preferably 0.05% by mass or more, and from the viewpoint of improving formulation stability, it is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less, still more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less, and still more preferably 0.1% by mass or less. The content of component (A) in the stain composition is preferably 0.001% by mass or more and 3.0% by mass or less, more preferably 0.002% by mass or more and 3.0% by mass or less, even more preferably 0.005% by mass or more and 1.0% by mass or less, still more preferably 0.01% by mass or more and 0.8% by mass or less, still more preferably 0.02% by mass or more and 0.6% by mass or less, still more preferably 0.03% by mass or more and 0.5% by mass or less, and still more preferably 0.05% by mass or more and 0.2% by mass or less. The content of component (A) in the stain composition may also be 0.03% by mass or more and 0.1% by mass or less.

[0034] The dye composition may further contain a dye other than the acid dye, however, from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber, the content of the dye other than the acid dye in the dye composition is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, even more preferably 0.02% by mass or less, still more preferably 0.01% by mass or less, still more preferably 0.001% by mass or less, still more preferably 0.0001% by mass or less, and may even be 0% by mass.

[0035] <Water> The water used in the composition of the present invention is not particularly limited, and for example, ion-exchanged water, pure water, distilled water, etc. can be used. From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fibers, the content of water in the dye composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.999% by mass or less. The content of water in the dye composition may be the remainder of the acid dye.

[0036] <Other Components> In addition to the above-described components, the dye composition may contain antioxidants, fragrances, preservatives, thickeners, pH adjusters, surfactants, polymers, and the like.

[0037] <pH> The pH of the dye composition is preferably 2.0 or higher, more preferably 2.2 or higher, and even more preferably 2.5 or higher. From the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fibers, the pH is preferably 6 or lower, more preferably 5 or lower, and even more preferably 4 or lower. The pH of the dye composition is preferably 2.0 or higher and 6 or lower, more preferably 2.2 or higher and 5 or lower, and even more preferably 2.5 or higher and 4 or lower. The pH can be measured at 25°C by the method described in the Examples.

[0038] <Form, Production Method> The form of the dye composition is not particularly limited, and can be liquid, paste, cream, gel, foam, spray, wax, or other formulation depending on the product form, with liquid being preferred. The production method of the dye composition is not particularly limited, and the dye composition can be produced by mixing the components by any method. The dye composition of the present embodiment can be preferably obtained by mixing a medium (e.g., water) and other components under heating (e.g., 60 to 80°C) to dissolve them uniformly, and then adding component (A) and mixing them uniformly.

[0039] <Modified regenerated collagen fiber> The regenerated collagen fiber to be dyed with the dye composition of the present invention comprises modified regenerated collagen fiber containing one or more compounds (B) selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof (B2) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight-average molecular weight of 1,500 to 15,000, or a salt thereof

[0040] (Component (B)) Component (B) is one or more compounds selected from the group consisting of components (B1) and (B2) and is a modifier for regenerated collagen fibers. The regenerated collagen fibers to be modified by component (B) will be described later.

[0041] [Component (B1)] Component (B1) is benzoic acid or a salt thereof. When component (B1) is a salt, examples thereof include alkali metal salts such as sodium salts and potassium salts. Specific examples of component (B1) include one or more selected from the group consisting of benzoic acid, sodium benzoate, and potassium benzoate, and preferably one or more selected from the group consisting of benzoic acid and sodium benzoate.

[0042] [Component (B2)] Component (B2) is a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, and is a copolymer or a salt thereof having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1,500 or more and 15,000 or less.

[0043] The structural unit derived from the unsaturated monomer having a carboxy group in component (B2) may be derived from an unsaturated monocarboxylic acid or an unsaturated dicarboxylic acid, or a combination thereof. Specific examples of the unsaturated monomer having a carboxy group include unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. Examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, oleic acid, and cyclopentenylacetic acid. Examples of unsaturated dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and methylenesuccinic acid. Furthermore, an unsaturated dicarboxylic acid anhydride may be used as the unsaturated monomer having a carboxy group, and may be converted into an acid form by hydrolysis with an alkali or the like. Examples of unsaturated dicarboxylic acid anhydrides include maleic anhydride and citraconic anhydride. The unsaturated monomer having a carboxy group may be used alone or in combination of two or more.

[0044] The structural unit derived from an aromatic vinyl compound in component (B2) is not particularly limited as long as it is derived from an aromatic compound substituted with at least a vinyl group. Specific examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, 3-vinyltoluene, dimethylstyrene, ethylvinylbenzene, chloromethylstyrene, vinylnaphthalene, and vinylanthracene. The aromatic vinyl compounds can be used alone or in combination of two or more.

[0045] In component (B2), the bonding state of the monomers that give each structural unit may be block bonding, random bonding, or a combination thereof.

[0046] Component (B2) may contain structural units other than the above-mentioned unsaturated monomers. Examples of other structural units include, but are not limited to, structural units derived from unsaturated aliphatic hydrocarbon compounds. Examples of the unsaturated aliphatic hydrocarbon compounds include linear, branched, and cyclic unsaturated aliphatic hydrocarbon compounds. Examples of linear or branched unsaturated aliphatic hydrocarbon compounds include propylene, isobutylene, diisobutylene, triisobutylene, tripropylene, and tetrapropylene. Examples of cyclic unsaturated aliphatic hydrocarbon compounds include cyclopentene, cyclohexene, and cyclooctene. The structural units derived from the above-mentioned unsaturated aliphatic hydrocarbon compounds may include one or more types.

[0047] A preferred embodiment of component (B2) is, for example, a copolymer containing structural units derived from one or more selected from the group consisting of unsaturated monocarboxylic acids and unsaturated dicarboxylic acids and structural units derived from an aromatic vinyl compound. Specific examples of component (B2), from the viewpoint of further improving dyeability and fastness when dyeing with the dye composition of the present invention, preferably contain one or more selected from the group consisting of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinylbenzoic acid-maleic acid copolymer, vinylbenzoic acid-acrylic acid copolymer, vinylbenzoic acid-methacrylic acid copolymer, and styrene-4-vinylbenzoic acid copolymer, and more preferably contain styrene-maleic acid copolymer.

[0048] In component (B2), the molar ratio (u1 / u2) of the structural unit (u1) derived from the unsaturated monomer having a carboxy group to the structural unit (u2) derived from the aromatic vinyl compound monomer is preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1, from the viewpoint of improving the dyeability and fastness of the modified regenerated collagen fiber.

[0049] The acid value of component (B2) is 100 mgKOH / g or more, and from the viewpoint of further improving dyeability and fastness when dyed with the dye composition of the present invention, it is preferably 200 mgKOH / g or more, more preferably 300 mgKOH / g or more, even more preferably 400 mgKOH / g or more, and preferably 1000 mgKOH / g or less, more preferably 800 mgKOH / g or less, even more preferably 600 mgKOH / g or less. The acid value of component (B2) is preferably 100 mgKOH / g or more and 1000 mgKOH / g or less, more preferably 200 mgKOH / g or more and 800 mgKOH / g or less, even more preferably 200 mgKOH / g or more and 600 mgKOH / g or less, still more preferably 300 mgKOH / g or more and 600 mgKOH / g or less, still more preferably 400 mgKOH / g or more and 600 mgKOH / g or less. Here, the acid value is the number of mg of potassium hydroxide required to neutralize 1 g of sample.

[0050] Specific examples of component (B2) having an acid value within the above range include the following compounds: Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 1 / 1) 475 mg KOH / g Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 2 / 1) 355 mg KOH / g Styrene-maleic acid copolymer (styrene / maleic acid (molar ratio) = 3 / 1) 285 mg KOH / g

[0051] Component (B2) has a weight-average molecular weight of 1,500 or more and 15,000 or less, and from the viewpoint of further improving fastness when dyed with the dye composition of the present invention, it is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 6,000 or more, and preferably 10,000 or less, more preferably 9,500 or less, and even more preferably 9,000 or less. The weight-average molecular weight of component (B2) is preferably 1,500 or more and 10,000 or less, more preferably 3,000 or more and 10,000 or less, even more preferably 5,000 or more and 9,500 or less, and even more preferably 6,000 or more and 9,000 or less. The weight-average molecular weight of component (B2) may also be preferably 3,000 or more and 15,000 or less, more preferably 5,000 or more and 15,000 or less, even more preferably 6,000 or more and 10,000 or less. In this specification, the term "weight average molecular weight" refers to a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC), and specifically can be measured by the method described in the examples.

[0052] The component (B) can be used alone or in combination of two or more. Among the above, from the viewpoint of further improving fastness when dyed with the dye composition of the present invention, the component (B) preferably contains one or more selected from the group consisting of benzoic acid, sodium benzoate, and a styrene-maleic acid copolymer, and more preferably contains a styrene-maleic acid copolymer.

[0053] (Content of component (B)) From the viewpoint of further improving dyeability and fastness when dyed with the dye composition of the present invention, the content of component (B) in the modified regenerated collagen fiber is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, still more preferably 3.0% by mass or more, still more preferably 5.0% by mass or more, still more preferably 10% by mass or more, still more preferably 15% by mass or more, still more preferably 20% by mass or more, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, still more preferably 60% by mass or less, still more preferably 55% by mass or less, still more preferably 50% by mass or less, still more preferably 45% by mass or less, still more preferably 40% by mass or less. The content of component (B) in the modified regenerated collagen fiber is preferably 0.1% by mass or more and 70% by mass or less, more preferably 0.5% by mass or more and 65% by mass or less, even more preferably 1.0% by mass or more and 60% by mass or less, even more preferably 3.0% by mass or more and 55% by mass or less, even more preferably 5.0% by mass or more and 50% by mass or less, even more preferably 10% by mass or more and 45% by mass or less, even more preferably 15% by mass or more and 40% by mass or less, and even more preferably 20% by mass or more and 40% by mass or less.

[0054] When the modified regenerated collagen fiber contains component (B1) as component (B), the content of component (B1) in the modified regenerated collagen fiber means the content converted into benzoic acid.

[0055] The content of component (B) in modified regenerated collagen fibers can be measured by the following method. First, an appropriate solvent that does not decompose component (B) and can dissolve the regenerated collagen fibers is selected, and the fibers are dissolved and extracted. Then, after appropriately diluting the extracted solution, the peak area of ​​a chromatogram plotted at an absorption wavelength suitable for quantifying component (B) is measured using HPLC / UV or GPC / UV, and the content of component (B) is calculated from the peak area. Specifically, the content of component (B) in modified regenerated collagen fibers can be measured by the method described in the Examples.

[0056] The dye composition of the present invention may have a mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition controlled according to the mode of use. For example, when the dye composition is a coat-type dye composition, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, still more preferably 50 or more, still more preferably 100 or more, and still more preferably 200 or more, from the viewpoints of dye compatibility and dye levelness. Furthermore, from the viewpoints of dyeability, storage stability and dye levelness of the dye composition, it can be set to preferably 20,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, still more preferably 2,000 or less, still more preferably 1,000 or less, still more preferably 700 or less, still more preferably 500 or less, and still more preferably 400 or less. That is, the mass ratio [(B) / (A)] is preferably 5 or more and 20,000 or less, more preferably 10 or more and 10,000 or less, even more preferably 20 or more and 5,000 or less, still more preferably 50 or more and 2,000 or less, still more preferably 100 or more and 1,000 or less, still more preferably 100 or more and 700 or less, still more preferably 100 or more and 500 or less, and still more preferably 200 or more and 400 or less. Furthermore, when the dye composition is a dip-type dye, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is, from the viewpoints of dye compatibility, storage stability and dye levelness of the dye composition, preferably 0.1 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, still more preferably 7 or more, and still more preferably 10 or more; and from the viewpoints of dyeability and dye levelness, it can be set to preferably 3,000 or less, more preferably 1,500 or less, still more preferably 750 or less, still more preferably 500 or less, still more preferably 300 or less, still more preferably 100 or less, and still more preferably 60 or less.That is, the mass ratio [(B) / (A)] is preferably 0.1 or more and 3,000 or less, more preferably 1 or more and 1,500 or less, even more preferably 2 or more and 750 or less, still more preferably 5 or more and 500 or less, still more preferably 7 or more and 300 or less, still more preferably 7 or more and 100 or less, and still more preferably 10 or more and 60 or less.

[0057] (Component (C): Polyvalent Metal, or Salt or Complex Thereof) In order to firmly coordinate component (B) within the fiber and thereby further improve dyeability and fastness when dyed using the dye composition of the present invention, the modified regenerated collagen fibers preferably contain, in addition to component (B), a polyvalent metal, or a salt or complex thereof as component (C). Component (C) also acts as a modifier for the regenerated collagen fibers. Examples of component (C) include 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. These may be used alone or in combination of two or more. Among the above, from the viewpoint of improving water resistance and further improving dyeability and fastness when dyeing is performed using the dye composition of the present invention, component (C) preferably contains one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt or complex thereof, and more preferably contains aluminum, or a salt or complex thereof.

[0058] When the modified regenerated collagen fibers contain component (C), the content of component (C) in the modified regenerated collagen fibers is, in terms of metal element content, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving water resistance and further improving dyeability and fastness when dyed with the dye composition of the present invention. The content of component (C) in the modified regenerated collagen fibers is, in terms of metal element content, preferably 0.1% by mass or more and 40% by mass or less, more preferably 0.5% by mass or more and 30% by mass or less, even more preferably 1.0% by mass or more and 20% by mass or less, and even more preferably 2.0% by mass or more and 10% by mass or less. The amount of component (C) in the modified regenerated collagen fibers is quantified, for example, as follows. The modified regenerated collagen fibers are incinerated, alkali-fused, and dissolved in acid to prepare a solution. This solution is then appropriately diluted to prepare a measurement sample, and the metal elements are quantified using an ICP atomic emission spectrometer. The amounts of the metal elements can be measured specifically by the methods described in the Examples.

[0059] The dye composition of the present invention may be adjusted in accordance with the mode of use by controlling the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition. For example, when the dye composition is a coating type and is applied to regenerated collagen fibers, the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is preferably 0.3 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, even more preferably 10 or more, and still more preferably 25 or more, from the viewpoints of dye compatibility, storage stability, and dye levelness of the dye composition. Furthermore, from the viewpoints of dyeability and dye levelness, it can be set to preferably 5,000 or less, more preferably 2,500 or less, even more preferably 1,000 or less, still more preferably 500 or less, still more preferably 200 or less, and still more preferably 100 or less. That is, the mass ratio [(C) / (A)] is preferably 0.3 or more and 5,000 or less, more preferably 1 or more and 2,500 or less, even more preferably 2 or more and 1,000 or less, still more preferably 5 or more and 500 or less, still more preferably 10 or more and 200 or less, and still more preferably 25 or more and 100 or less. Furthermore, when the dye composition is a dip-type dye, the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is, from the viewpoints of dye compatibility, storage stability and dye levelness of the dye composition, preferably 0.04 or more, more preferably 0.1 or more, even more preferably 0.2 or more, still more preferably 0.5 or more, still more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 3 or more; and from the viewpoints of dyeability and dye levelness, it can be set to preferably 750 or less, more preferably 500 or less, still more preferably 150 or less, still more preferably 75 or less, still more preferably 20 or less, still more preferably 15 or less, and still more preferably 12 or less. That is, the mass ratio [(C) / (A)] is preferably 0.04 or more and 750 or less, more preferably 0.1 or more and 500 or less, even more preferably 0.2 or more and 150 or less, still more preferably 0.5 or more and 75 or less, still more preferably 1.0 or more and 20 or less, still more preferably 1.5 or more and 15 or less, still more preferably 1.5 or more and 12 or less, and still more preferably 3 or more and 12 or less.

[0060] (Method for manufacturing modified regenerated collagen fibers) The regenerated collagen fibers that are the raw material for modified regenerated collagen fibers do not need to be 100% collagen, and may contain natural or synthetic polymers or additives to improve quality. Furthermore, they may be post-processed regenerated collagen fibers. Filaments are preferred as the form of regenerated collagen fibers. Filaments are generally taken out from bobbins or boxes.

[0061] Suitable regenerated collagen fibers are artificially produced using collagen-derived polymers or oligomers as raw materials. Regenerated collagen fibers are usually produced by using a solubilized collagen raw material as a spinning dope, discharging this from a spinning nozzle into a coagulation bath to form fibers, and then drying the fibrous collagen in the final step. Here, regenerated collagen fibers before the drying step (hereinafter also referred to as "undried regenerated collagen fibers") can be produced by conventionally known methods. For example, undried regenerated collagen fibers can be obtained by discharging an aqueous collagen solution obtained by solubilizing insoluble collagen fibers made from the split hides of livestock animals through a spinning nozzle or slit, immersing the aqueous solution in an inorganic salt solution, and then recovering the resultant fibers without drying. This method will be specifically described below.

[0062] The collagen raw material used in the production of regenerated collagen fibers is preferably split skins. Split skins are obtained from fresh split skins obtained by slaughtering livestock animals such as cattle, or from salted raw hides. These split skins are mostly composed of insoluble collagen fibers, but are usually used after removing the fleshy part that is usually attached in a mesh-like form and removing the salt used to prevent spoilage and deterioration.

[0063] These insoluble collagen fibers contain impurities such as lipids (e.g., glycerides, phospholipids, and free fatty acids), glycoproteins, albumin, and other proteins other than collagen. These impurities have a significant effect on spinning stability, quality (e.g., gloss and strength and elongation), odor, and other factors during fiberization. Therefore, it is preferable to remove these impurities in advance by, for example, soaking the insoluble collagen fibers in lime to hydrolyze the fat in the fibers and loosen the collagen fibers, and then subjecting the fibers to conventional leather treatments such as acid / alkali treatment, enzyme treatment, and solvent treatment.

[0064] The insoluble collagen thus treated is then subjected to a solubilization treatment to cleave the cross-linked peptide moieties. As a method for such solubilization, a commonly used known alkali solubilization method, an enzyme solubilization method, etc., can be used. Furthermore, the alkali solubilization method and the enzyme solubilization method may be used in combination.

[0065] When the alkali solubilization method is applied, it is preferable to neutralize with an acid such as hydrochloric acid. Note that, as an improved version of the conventional alkali solubilization method, for example, the method described in JP-B-46-15033 may be used.

[0066] The enzymatic solubilization method has the advantage of being able to obtain solubilized collagen with a uniform molecular weight, and is a method that can be suitably employed in the present invention. Examples of such enzymatic solubilization methods that can be employed include those described in Japanese Patent Publication Nos. 43-25829 and 43-27513.

[0067] If the collagen that has been solubilized in this way is further subjected to operations such as pH adjustment, salting out, water washing, and solvent treatment, it is possible to obtain regenerated collagen fibers with excellent quality, and therefore it is preferable to perform these treatments.

[0068] Solubilized collagen is dissolved in an acid such as hydrochloric acid, acetic acid, or lactic acid to obtain a collagen aqueous solution having a pH of 2 to 4.5 and a collagen concentration of 1% by mass or more, preferably 2% by mass or more, and 15% by mass or less, preferably 10% by mass or less. The collagen aqueous solution may be degassed under reduced pressure and stirred, as needed, or filtered to remove water-insoluble fine particles. Furthermore, the collagen aqueous solution may contain appropriate amounts of additives such as stabilizers and water-soluble polymers, as needed, for purposes such as improving mechanical strength, water resistance and heat resistance, gloss, spinnability, coloration prevention, and preservative properties.

[0069] The collagen aqueous solution is extruded, for example, through a spinning nozzle or slit, and then immersed in an inorganic salt aqueous solution to obtain undried regenerated collagen fibers. Examples of the inorganic salt aqueous solution include aqueous solutions of water-soluble inorganic salts such as sodium sulfate, sodium chloride, and ammonium sulfate. Typically, the concentration of the inorganic salt in these inorganic salt aqueous solutions is adjusted to 10 to 40% by mass. The pH of the inorganic salt aqueous solution is preferably 2 or higher, more preferably 4 or higher, and preferably 13 or lower, more preferably 12 or lower. To adjust the pH, for example, metal salts such as sodium borate and sodium acetate, hydrochloric acid, boric acid, acetic acid, and sodium hydroxide can be used. When the pH of the inorganic salt aqueous solution is within the above range, the collagen peptide bonds are less susceptible to hydrolysis, making it easier to obtain the desired fibers. The temperature of the inorganic salt aqueous solution is not particularly limited, but is typically 35°C or lower, which prevents denaturation of soluble collagen, prevents a decrease in the strength of the spun fibers, and facilitates the production of stable threads. The lower limit of the temperature of the inorganic salt aqueous solution is not particularly limited, but can typically be adjusted appropriately depending on the solubility of the inorganic salt.

[0070] Undried regenerated collagen fibers may be pretreated (crosslinked) by immersion 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, and even more preferably 1 equivalent or more, relative to the amount of amino groups in the regenerated collagen fibers that can react with the epoxy groups of the epoxy compound, as measured by amino acid analysis, and is also preferably 500 equivalents or less, more preferably 100 equivalents or less, and even more preferably 50 equivalents or less. By using an epoxy compound in this range, the regenerated collagen fibers can be sufficiently insolubilized in water, and this is also preferable from an industrial handleability and environmental standpoint.

[0071] The epoxy compound may be used as is or dissolved in various solvents. Examples of solvents include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; ethers such as tetrahydrofuran and dioxane; halogenated organic solvents such as dichloromethane, chloroform, and carbon tetrachloride; and neutral organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). These solvents may be used alone or in combination of two or more. 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 needed. Typically, the concentration of the inorganic salt in the aqueous solution is adjusted to 10 to 40% by mass. The pH of the aqueous solution may also be adjusted with, for example, a metal salt such as sodium borate or sodium acetate, or hydrochloric acid, boric acid, acetic acid, or sodium hydroxide. In this case, the pH of the aqueous solution is preferably 6 or higher, more preferably 8 or higher, from the viewpoint of preventing the reaction between the epoxy groups of the epoxy compound and the amino groups of collagen from slowing down and ensuring sufficient insolubilization in water. Furthermore, since the pH of an aqueous solution of an inorganic salt tends to decrease over time, a buffer may be used if necessary.

[0072] The temperature during treatment of undried regenerated collagen fibers with an epoxy compound is preferably 50°C or lower, from the viewpoints of preventing denaturation of the regenerated collagen fibers, preventing a decrease in the strength of the resulting fibers, and facilitating stable production of threads.

[0073] [Treatment with a fiber treating agent containing component (C)] From the viewpoint of improving water resistance, the modified regenerated collagen fibers used in the present invention preferably contain the component (C), and in producing the modified regenerated collagen fibers, it is preferable to treat the undried regenerated collagen fibers obtained by the above method in the following manner. First, the undried regenerated collagen fibers are immersed in a fiber treating agent containing component (C). The fiber treating agent containing component (C) is preferably an aqueous solution containing a polyvalent metal salt or polyvalent metal complex corresponding to component (C). The polyvalent metal salt or polyvalent metal complex preferably contains an aluminum salt or aluminum complex, and more preferably contains an aluminum salt. The aluminum salt is preferably basic aluminum chloride or basic aluminum sulfate represented by the following formula: Al(OH) n Cl 3-n , or Al2(OH) 2n (SO4) 3-n [wherein n is 0.5 to 2.5] Specific examples of the aluminum salt include aluminum sulfate, aluminum chloride, and alum, which can be used alone or in combination of two or more.

[0074] The content of the polyvalent metal salt and polyvalent metal complex in the fiber treatment agent is preferably 0.3 mass % or more and 5 mass % or less in terms of polyvalent metal oxide (aluminum oxide when the polyvalent metal is aluminum).

[0075] In order to prevent the polyvalent metal salt or polyvalent metal complex from being rapidly absorbed into the undried regenerated collagen fibers and causing uneven concentration, inorganic salts such as sodium chloride, sodium sulfate, and potassium chloride may be added to the fiber treatment agent as appropriate.

[0076] The pH of the fiber treatment agent at 25°C is preferably in the range of 2.5 or more and 5 or less, and can be adjusted using, for example, hydrochloric acid, sulfuric acid, acetic acid, sodium hydroxide, sodium carbonate, etc. A pH of 2.5 or more can suppress denaturation of the collagen structure, while a pH of 5 or less reduces the risk of precipitation of polyvalent metal salts or polyvalent metal complexes. It is preferable to initially adjust the pH to 2.2 or more and 3.5 or less to allow the aqueous solution of the polyvalent metal salt or polyvalent metal complex to sufficiently penetrate into the undried regenerated collagen fibers, and then add, for example, sodium hydroxide, sodium carbonate, etc. to adjust the pH to 3.5 or more and 5 or less to complete the treatment. When a highly basic polyvalent metal salt or polyvalent metal complex is used, only the initial pH adjustment of 2.5 or more and 5 or less is sufficient.

[0077] When treating with a fiber treatment agent containing component (C), the bath ratio of undried regenerated collagen fibers to the fiber treatment agent (dry mass of undried regenerated collagen fibers:mass of the fiber treatment agent) is preferably 1:2 to 1:500, more preferably 1:3 to 1:250, even more preferably 1:5 to 1:100, and even more preferably 1:20 to 1:50, when the mass of fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass.

[0078] The temperature during treatment with the fiber treatment agent containing component (C) (liquid temperature of the fiber treatment agent) is not particularly limited, but is preferably 5°C or higher, more preferably 10°C or higher, and is preferably 50°C or lower, more preferably 45°C or lower.

[0079] The treatment time (immersion time) with the fiber treatment agent containing component (C) is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and even more preferably 3 hours or more, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less.

[0080] After treating the undried regenerated collagen fibers with an epoxy compound and / or the fiber treatment agent, the fibers may be washed with water, for example, by washing with running water for 10 minutes to 4 hours.

[0081] [Treatment with a fiber treatment agent containing component (B)] Regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (C), are treated with a fiber treatment agent containing component (B) to obtain modified regenerated collagen fibers that can be dyed with the dye composition of the present invention.

[0082] From the viewpoint of improving penetration into fibers and improving the treatment effect, the content of component (B) in the fiber treatment agent is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, still more preferably 2.5% by mass or more, still more preferably 3.0% by mass or more, and preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. The content of component (B) in the fiber treatment agent is preferably 0.3% by mass or more and 60% by mass or less, more preferably 0.5% by mass or more and 60% by mass or less, even more preferably 1.0% by mass or more and 40% by mass or less, still more preferably 2.5% by mass or more and 40% by mass or less, and still more preferably 3.0% by mass or more and 35% by mass or less.

[0083] When component (B1) is used as component (B), the content of component (B1) in the fiber treatment agent, calculated as benzoic acid, is even more preferably 5.0% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 30% by mass or less, from the viewpoints of improving penetration into fibers and improving the treatment effect. When component (B1) is used as component (B), the content of component (B1) in the fiber treatment agent, calculated as benzoic acid, is preferably 0.3% by mass or more and 60% by mass or less, more preferably 0.5% by mass or more and 60% by mass or less, even more preferably 1.0% by mass or more and 40% by mass or less, still more preferably 2.5% by mass or more and 40% by mass or less, still more preferably 3.0% by mass or more and 35% by mass or less, still more preferably 5.0% by mass or more and 30% by mass or less, still more preferably 10% by mass or more and 30% by mass or less, still more preferably 15% by mass or more and 30% by mass or less, and still more preferably 20% by mass or more and 30% by mass or less.

[0084] When component (B2) is used as component (B), the content of component (B2) in the fiber treatment agent is even more preferably 4.0% by mass or more, and even more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5.0% by mass or less, from the viewpoint of improving penetration into fibers and improving the treatment effect. When component (B2) is used as component (B), the content of component (B2) in the fiber treatment agent is preferably 0.3% by mass or more and 60% by mass or less, more preferably 0.5% by mass or more and 60% by mass or less, even more preferably 1.0% by mass or more and 40% by mass or less, still more preferably 2.5% by mass or more and 40% by mass or less, still more preferably 3.0% by mass or more and 35% by mass or less, still more preferably 4.0% by mass or more and 30% by mass or less, still more preferably 4.0% by mass or more and 20% by mass or less, still more preferably 4.0% by mass or more and 10% by mass or less, and still more preferably 4.0% by mass or more and 5.0% by mass or less.

[0085] The fiber treatment agent containing component (B) preferably further contains a pH adjuster. The pH adjuster is not particularly limited as long as it can adjust the pH to the desired level, but examples thereof include alkalis such as sodium hydroxide and potassium hydroxide, and acids such as phosphoric acid, sulfuric acid, and hydrochloric acid.

[0086] The fiber treatment agent containing component (B) further contains water. The water content in the fiber treatment agent is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and still more preferably 70% by mass or more, and is preferably 99.7% by mass or less.

[0087] The pH of the fiber treatment agent containing component (B) at 25°C is preferably 3.0 or higher, more preferably 3.5 or higher, and even more preferably 4.0 or higher, from the viewpoint of suppressing damage to the fiber, and is preferably 7.5 or lower, more preferably 7.0 or lower, and even more preferably 6.5 or lower, from the viewpoint of suppressing damage to the fiber. The pH of the fiber treatment agent containing component (B) at 25°C is preferably 3.0 or higher and 7.5 or lower, more preferably 3.5 or higher and 7.0 or lower, and even more preferably 4.0 or higher and 6.5 or lower. The pH can be measured by the method described in the Examples.

[0088] Treatment with a fiber treatment agent containing component (B) can be carried out by immersing regenerated collagen fibers, or undried regenerated collagen fibers obtained by treatment with a fiber treatment agent containing component (C), in the fiber treatment agent containing component (B).

[0089] When treating with a fiber treatment agent containing component (B), the bath ratio of the regenerated collagen fibers or undried regenerated collagen fibers to the fiber treatment agent (dry mass of regenerated collagen fibers or undried regenerated collagen fibers:mass of the fiber treatment agent) is preferably 1:2 to 1:500, more preferably 1:3 to 1:250, even more preferably 1:5 to 1:100, and even more preferably 1:20 to 1:50, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass.

[0090] The temperature during treatment with a fiber treatment agent containing component (B) (the temperature of the fiber treatment agent) is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 30°C or higher, from the viewpoint of improving penetration into fibers, and is preferably less than 100°C, more preferably 90°C or lower, even more preferably 80°C or lower, still more preferably 70°C or lower, and even more preferably 60°C or lower, from the viewpoint of suppressing damage to fibers. The temperature during treatment with a fiber treatment agent containing component (B) (the temperature of the fiber treatment agent) is preferably 20°C or higher and lower than 100°C, more preferably 20°C or higher and 90°C or lower, even more preferably 25°C or higher and 80°C or lower, still more preferably 25°C or higher and 70°C or lower, and even more preferably 30°C or higher and 60°C or lower. When treating with a fiber treatment agent by heating, the regenerated collagen fibers or undried regenerated collagen fibers may be immersed in the heated fiber treatment agent, or the fiber treatment agent may be heated after immersing the regenerated collagen fibers or undried regenerated collagen fibers in a low-temperature fiber treatment agent.

[0091] The treatment time (immersion time) with the fiber treatment agent containing component (B) is preferably 15 minutes or more, more preferably 30 minutes or more, even more preferably 1 hour or more, and still more preferably 3 hours or more from the viewpoint of improving the treatment effect, and is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less from the viewpoint of suppressing damage to the fiber. The treatment time (immersion time) with the fiber treatment agent containing component (B) is preferably 15 minutes to 48 hours, more preferably 30 minutes to 33 hours, even more preferably 1 hour to 20 hours, and still more preferably 3 hours to 20 hours.

[0092] Treatment with the fiber treatment agent containing component (B) is preferably carried out in an environment in which evaporation of water is suppressed. Specific means for suppressing evaporation of water include covering the container of the fiber treatment agent in which the fibers are immersed with a film-like substance, cap, lid, or the like made of a material that is impermeable to water vapor.

[0093] After treatment with the fiber treatment agent, the resulting modified regenerated collagen fibers are preferably washed with water, for example, by washing with running water for 10 minutes to 4 hours.

[0094] When component (B2) is used as component (B), the treatment with the fiber treatment agent containing component (B2) may be carried out two or more times. Specifically, it is preferable to carry out the following steps (1) and (2) in this order two or more times: (1) a step of immersing regenerated collagen fibers or undried regenerated collagen fibers obtained by treatment with the fiber treatment agent containing component (C) in a fiber treatment agent containing component (B2); and (2) a step of removing the fibers immersed in the fiber treatment agent in step (1) and washing them with water.

[0095] Here, from the viewpoint of improving the treatment effect, the treatment conditions for the first treatment and the second and subsequent treatments are more preferably in the following ranges. Other points are the same as those described above. In the first treatment, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 4.5 or more, more preferably 5.0 or more, and preferably 7.5 or less, more preferably 7.0 or less, and even more preferably 6.5 or less, from the viewpoint of improving penetration into the fiber and suppressing damage to the fiber. Furthermore, in the first treatment, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 4.5 or more and 7.5 or less, more preferably 5.0 or more and 7.0 or less, and even more preferably 5.0 or more and 6.5 or less. In the first treatment, the treatment time (immersion time) in step (1) is preferably 3 hours or more, more preferably 4 hours or more, and even more preferably 6 hours or more, from the viewpoint of improving the treatment effect. Furthermore, from the viewpoint of suppressing damage to the fiber, it is preferably 48 hours or less, more preferably 33 hours or less, and even more preferably 20 hours or less. In the first treatment, the treatment time (immersion time) in step (1) is preferably 3 hours or more and 48 hours or less, more preferably 4 hours or more and 33 hours or less, and even more preferably 6 hours or more and 20 hours or less.

[0096] In the second or subsequent treatments, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 3.0 or more, more preferably 3.5 or more, and preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.0 or less, and still more preferably less than 4.5, from the viewpoint of improving the treatment effect. Furthermore, in the second or subsequent treatments, the pH at 25°C of the fiber treatment agent used in step (1) is preferably 3.0 or more and 6.0 or less, more preferably 3.0 or more and 5.5 or less, even more preferably 3.5 or more and 5.0 or less, and still more preferably 3.5 or more and less than 4.5. In the second or subsequent treatments, the treatment time (immersion time) in step (1) is preferably 15 minutes or more, more preferably 30 minutes or more, from the viewpoint of improving the treatment effect, and is preferably 5 hours or less, more preferably 3 hours or less, and still more preferably 2 hours or less, from the viewpoint of suppressing fiber damage. In the second and subsequent treatments, the treatment time (immersion time) in step (1) is preferably 15 minutes to 5 hours, more preferably 15 minutes to 3 hours, and even more preferably 30 minutes to 2 hours.

[0097] The number of treatments with the fiber treatment agent containing component (B2) is preferably 2 to 5 times, more preferably 2 to 3 times, from the viewpoint of improving the treatment effect and productivity. After the treatment, the resulting modified regenerated collagen fibers are preferably dried. The drying temperature is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of improving the drying speed, and is preferably 100°C or lower, more preferably 80°C or lower, from the viewpoint of suppressing fiber damage. The drying time is preferably 15 minutes or longer, more preferably 30 minutes or longer, and is preferably 48 hours or shorter, more preferably 33 hours or shorter, and even more preferably 20 hours or shorter, from the viewpoint of suppressing fiber damage.

[0098] By carrying out the above modification treatment, component (B) penetrates into the regenerated collagen fibers. Furthermore, when treatment is carried out with a fiber treatment agent containing component (C), component (B) is strongly coordinated to the polyvalent metal in the fibers. When modified regenerated collagen fibers are dyed using the dye composition of the present invention, the acid dye (A) tends to remain in the modified regenerated collagen fibers, which is thought to improve fastness.

[0099] The regenerated collagen fibers to be dyed with the dye composition of the present invention may be fibers that contain at least a portion of the modified regenerated collagen fibers, or may be fibers consisting solely of modified regenerated collagen fibers. From the viewpoint of further improving fastness, the regenerated collagen fibers to be dyed with the dye composition of the present invention are preferably fibers consisting solely of modified regenerated collagen fibers.

[0100] [Dyeing method] The present invention provides a method for dyeing regenerated collagen fibers, the method comprising a step of applying a dye composition for regenerated collagen fibers to the regenerated collagen fibers, wherein the dye composition contains the following component (A) and water, and the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (B). (A) An acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) where Mw is the molecular weight, the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) divided by Mw, [(a-b) / Mw], is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1500 to 15000, or a salt thereof. In the following description, the method for dyeing regenerated collagen fibers will also be simply referred to as the "dyeing method of the present invention."

[0101] The regenerated collagen fibers, the dye composition, and their preferred embodiments are the same as those described in the dye composition for regenerated collagen fibers.

[0102] The method of the present invention includes a step of applying the regenerated collagen fiber dye composition to the regenerated collagen fibers. The method of applying the regenerated collagen fiber dye composition to the regenerated collagen fibers may be any method that allows the dye composition to come into contact with the regenerated collagen fibers, including, for example, a method of applying the composition to dry or wet regenerated collagen fibers, and a method of immersing the regenerated collagen fibers in the composition. Among these methods, a method of applying the dye composition to dry regenerated collagen fibers or a method of immersing dry regenerated collagen fibers in the dye composition is preferred. From the viewpoint of a balance between dyeability, fastness, and cost-effectiveness, the amount of the dye composition applied to the regenerated collagen fibers is preferably a bath ratio (dry mass of regenerated collagen fibers:mass of dye composition) of 1:0.2 to 1:500, where the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass. When the dye composition is applied to the regenerated collagen fibers, the amount of the dye composition to be applied to the regenerated collagen fibers, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass, is more preferably 1:0.2 to 1:200, even more preferably 1:0.2 to 1:100, still more preferably 1:0.2 to 1:50, even more preferably 1:0.2 to 1:20, even more preferably 1:0.5 to 1:10, even more preferably 1:0.5 to 1:5, and even more preferably 1:0.8 to 1:3 in terms of the bath ratio (dry mass of regenerated collagen fibers:mass of dye composition), Furthermore, when regenerated collagen fibers are immersed in the dye composition, when the mass of the fibers after conditioning for 24 hours at 20°C and a relative humidity of 65% is taken as the dry mass, the bath ratio (dry mass of regenerated collagen fibers:mass of dye composition) is more preferably 1:2 to 1:500, even more preferably 1:3 to 1:250, still more preferably 1:5 to 1:100, even more preferably 1:10 to 1:50, and still more preferably 1:10 to 1:20.

[0103] Furthermore, in this step, the dyeing conditions for the fiber for headwear may be set using the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition as an index. Specifically, for example, when the dye composition is applied to the regenerated collagen fiber, the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, still more preferably 50 or more, even more preferably 100 or more, and still more preferably 200 or more, from the viewpoints of dye compatibility and dye levelness. Furthermore, from the viewpoints of dyeability, storage stability and dye levelness of the dye composition, this step may be performed under conditions such that the mass ratio is preferably 20,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, even more preferably 2,000 or less, even more preferably 1,000 or less, even more preferably 700 or less, even more preferably 500 or less, and still more preferably 400 or less. That is, the mass ratio [(B) / (A)] is preferably 5 or more and 20,000 or less, more preferably 10 or more and 10,000 or less, even more preferably 20 or more and 5,000 or less, still more preferably 50 or more and 2,000 or less, still more preferably 100 or more and 1,000 or less, still more preferably 100 or more and 700 or less, still more preferably 100 or more and 500 or less, and still more preferably 200 or more and 400 or less. On the other hand, when regenerated collagen fibers are immersed in the dye composition, this step may be performed under conditions such that the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is preferably 0.1 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, still more preferably 7 or more, and still more preferably 10 or more, from the viewpoints of dye compatibility, storage stability, and dye levelness of the dye composition; and is preferably 3000 or less, more preferably 1500 or less, even more preferably 750 or less, still more preferably 500 or less, still more preferably 300 or less, still more preferably 100 or less, and still more preferably 60 or less, from the viewpoints of dyeability and dye levelness.That is, the mass ratio [(B) / (A)] is preferably 0.1 or more and 3,000 or less, more preferably 1 or more and 1,500 or less, even more preferably 2 or more and 750 or less, still more preferably 5 or more and 500 or less, still more preferably 7 or more and 300 or less, still more preferably 7 or more and 100 or less, and still more preferably 10 or more and 60 or less.

[0104] Furthermore, the dyeing conditions for the fiber for headwear can be set using the mass ratio [(C) / (A)] of component (C) in the fiber for headwear to the basic dye in the dye composition as an index. Specifically, for example, when the dye composition is applied to regenerated collagen fibers, the mass ratio [(C) / (A)] of component (C) in the fiber for headwear to component (A) in the dye composition is preferably 0.3 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, even more preferably 10 or more, and still more preferably 25 or more, from the viewpoints of dye compatibility, storage stability, and dye levelness of the dye composition; and from the viewpoints of dyeability and dye levelness, the process can be carried out under conditions such that the mass ratio is preferably 5,000 or less, more preferably 2,500 or less, even more preferably 1,000 or less, still more preferably 500 or less, even more preferably 200 or less, and still more preferably 100 or less. That is, the mass ratio [(C) / (A)] is preferably 0.3 or more and 5,000 or less, more preferably 1 or more and 2,500 or less, even more preferably 2 or more and 1,000 or less, still more preferably 5 or more and 500 or less, still more preferably 10 or more and 200 or less, and still more preferably 25 or more and 100 or less. On the other hand, when regenerated collagen fibers are immersed in the dye composition, this step can be carried out under conditions such that the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is preferably 0.04 or more, more preferably 0.1 or more, even more preferably 0.2 or more, still more preferably 0.5 or more, still more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 3 or more, from the viewpoints of dye compatibility, storage stability, and dye levelness of the dye composition; and further, from the viewpoints of dyeability and dye levelness, it is preferably 750 or less, more preferably 500 or less, still more preferably 150 or less, still more preferably 75 or less, still more preferably 20 or less, still more preferably 15 or less, and still more preferably 12 or less.That is, the mass ratio [(C) / (A)] is preferably 0.04 or more and 750 or less, more preferably 0.1 or more and 500 or less, even more preferably 0.2 or more and 150 or less, still more preferably 0.5 or more and 75 or less, still more preferably 1.0 or more and 20 or less, still more preferably 1.5 or more and 15 or less, still more preferably 1.5 or more and 12 or less, and still more preferably 3 or more and 12 or less.

[0105] When the dye composition is applied to regenerated collagen fibers, the application time is preferably 10 seconds or more, more preferably 20 seconds or more, from the viewpoint of further improving dyeability and fastness, and is preferably 10 minutes or less, more preferably 5 minutes or less, from the viewpoint of improving productivity. When the dye composition is applied to regenerated collagen fibers, the application time is preferably 10 seconds or more and 10 minutes or less, more preferably 20 seconds or more and 5 minutes or less.

[0106] After applying the dye composition to the regenerated collagen fibers, it is preferable to further carry out a step of leaving the composition to stand. The leaving time is preferably 1 minute or more, more preferably 3 minutes or more, and even more preferably 5 minutes or more from the viewpoint of further improving dyeability and fastness, and is preferably 1 hour or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less from the viewpoint of improving productivity. The leaving time is preferably 1 minute or more and 1 hour or less, more preferably 3 minutes or more and 30 minutes or less, and even more preferably 5 minutes or more and 20 minutes or less.

[0107] When regenerated collagen fibers are immersed in the dye composition, the immersion time is preferably 10 seconds or more, more preferably 30 seconds or more, from the viewpoint of further improving dyeability and fastness, and is preferably 3 hours or less, more preferably 2 hours or less, and even more preferably 1 hour or less, from the viewpoint of improving productivity. The immersion time is preferably 10 seconds or more and 3 hours or less, more preferably 10 seconds or more and 2 hours or less, and even more preferably 30 seconds or more and 1 hour or less.

[0108] The temperature when the dye composition is applied to the regenerated collagen fibers is not particularly limited, but from the viewpoint of improving the handleability of the dye composition and suppressing thermal shrinkage of the regenerated collagen fibers, it is preferably 40°C or lower, more preferably 35°C or lower. Furthermore, from the viewpoint of further improving dyeability and fastness, it is preferably 5°C or higher, more preferably 10°C or higher. The temperature when the dye composition is applied to the regenerated collagen fibers is preferably 5°C or higher and 40°C or lower, more preferably 10°C or higher and 35°C or lower.

[0109] The dyeing method of the present invention preferably includes a step of rinsing the dye composition applied to the regenerated collagen fibers after applying the dye composition to the regenerated collagen fibers (hereinafter also referred to simply as the "rinsing step"). The rinsing step is carried out, for example, by rinsing the dye composition applied to the regenerated collagen fibers with water. There are no particular restrictions on the temperature of the water, but warm water at 35 to 45°C is preferred.

[0110] The dyeing method of the present invention preferably includes a step of drying the regenerated collagen fibers (hereinafter also simply referred to as a "drying step") after applying the dye composition to the regenerated collagen fibers, or after performing a rinsing step if one is included. The step of drying the regenerated collagen fibers is a step of reducing the moisture content of the regenerated collagen fibers, and includes, for example, towel drying, drying with a dryer (cold air or hot air), air drying, and a combination of two or more of these drying treatments in order to actively reduce the moisture content of the regenerated collagen fibers.

[0111] [Colored modified regenerated collagen fiber] The present invention further provides a colored modified regenerated collagen fiber containing the following components (A) and (B): (A) an acid dye having sulfonic acid groups and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, of 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof.

[0112] The colored modified regenerated collagen fibers are modified regenerated collagen fibers that have been modified with the component (B) and then colored with the component (A). From the viewpoint of further improving dyeability and fastness, the colored modified regenerated collagen fibers preferably further contain the component (C): a polyvalent metal, or a salt or complex thereof.

[0113] The colored modified regenerated collagen fibers of the present invention preferably have a mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition controlled according to the coloring method. That is, when the fiber is colored by application, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, still more preferably 50 or more, even more preferably 100 or more, and still more preferably 200 or more, from the viewpoints of dye compatibility and dye levelness. Furthermore, from the viewpoints of dyeability, storage stability of the dye composition, and dye levelness, it is preferably 20,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, even more preferably 2,000 or less, even more preferably 1,000 or less, even more preferably 700 or less, even more preferably 500 or less, and still more preferably 400 or less. That is, the mass ratio [(B) / (A)] is preferably 5 or more and 20,000 or less, more preferably 10 or more and 10,000 or less, even more preferably 20 or more and 5,000 or less, still more preferably 50 or more and 2,000 or less, still more preferably 100 or more and 1,000 or less, still more preferably 100 or more and 700 or less, still more preferably 100 or more and 500 or less, and still more preferably 200 or more and 400 or less. On the other hand, when the fiber is colored by immersion, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is, from the viewpoints of dye compatibility, storage stability and dye levelness of the dye composition, preferably 0.1 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, still more preferably 7 or more, and still more preferably 10 or more; and, from the viewpoints of dyeability and dye levelness, is preferably 3,000 or less, more preferably 1,500 or less, even more preferably 750 or less, still more preferably 500 or less, still more preferably 300 or less, still more preferably 100 or less, and still more preferably 60 or less.That is, the mass ratio [(B) / (A)] is preferably 0.1 or more and 3,000 or less, more preferably 1 or more and 1,500 or less, even more preferably 2 or more and 750 or less, still more preferably 5 or more and 500 or less, still more preferably 7 or more and 300 or less, still more preferably 7 or more and 100 or less, and still more preferably 10 or more and 60 or less.

[0114] Furthermore, the colored modified regenerated collagen fibers of the present invention are preferably those in which the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is controlled depending on the coloring method. That is, when the fiber is colored by application, in which the dye composition is applied to the regenerated collagen fibers, the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is preferably 0.3 or more, more preferably 1 or more, even more preferably 2 or more, still more preferably 5 or more, even more preferably 10 or more, and still more preferably 25 or more, from the viewpoints of dye compatibility, storage stability, and dye levelness of the dye composition. Furthermore, from the viewpoints of dyeability and dye levelness, it is preferably 5,000 or less, more preferably 2,500 or less, even more preferably 1,000 or less, still more preferably 500 or less, still more preferably 200 or less, and still more preferably 100 or less. That is, the mass ratio [(C) / (A)] is preferably 0.3 or more and 5,000 or less, more preferably 1 or more and 2,500 or less, even more preferably 2 or more and 1,000 or less, still more preferably 5 or more and 500 or less, still more preferably 10 or more and 200 or less, and still more preferably 25 or more and 100 or less. On the other hand, when the fiber is colored by immersion, the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is, from the viewpoints of dye compatibility, storage stability and dye levelness of the dye composition, preferably 0.04 or more, more preferably 0.1 or more, even more preferably 0.2 or more, still more preferably 0.5 or more, still more preferably 1.0 or more, still more preferably 1.5 or more, and still more preferably 3 or more; and, from the viewpoints of dyeability and dye levelness, is preferably 750 or less, more preferably 500 or less, still more preferably 150 or less, still more preferably 75 or less, still more preferably 20 or less, still more preferably 15 or less, and still more preferably 12 or less.That is, the mass ratio [(C) / (A)] is preferably 0.04 or more and 750 or less, more preferably 0.1 or more and 500 or less, even more preferably 0.2 or more and 150 or less, still more preferably 0.5 or more and 75 or less, still more preferably 1.0 or more and 20 or less, still more preferably 1.5 or more and 15 or less, still more preferably 1.5 or more and 12 or less, and still more preferably 3 or more and 12 or less.

[0115] The colored modified regenerated collagen fibers can be obtained by preparing modified regenerated collagen fibers containing one or more compounds (B) selected from the group consisting of component (B1) and component (B2) using the method described above, and then applying the regenerated collagen fiber dye composition to the modified regenerated collagen fibers to dye them. The dyeing method of the present invention described above can be preferably used as a method for dyeing the modified regenerated collagen fibers.

[0116] [Headwear products] The colored modified regenerated collagen fibers can be suitably used in headwear products. In this specification, "headwear products" refers to, for example, hair wigs, hairpieces, weaving, hair extensions, braided hair, hair accessories, doll hair, etc. Furthermore, "fibers for headwear products" refers to fibers used in the above-mentioned headwear products. The headwear products may contain, at least in part, colored fibers for headwear products. In this application, fibers for headwear products also include human hair.

[0117] In relation to the above-described embodiments, the present invention discloses the following: <1> A dye composition for regenerated collagen fibers, the dye composition containing the following component (A) and water, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B). (A) an acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof; <2> The dye composition for regenerated collagen fibers according to <1>, wherein the number of sulfonic acid groups (a) in the component (A) is preferably 1 or more and 6 or less, more preferably 1 or more and 5 or less, even more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and even more preferably 2 or more and 3 or less. <3> The dye composition for regenerated collagen fibers according to <1> or <2>, wherein the cationic moiety comprises one or more selected from the group consisting of a quaternary ammonium cationic moiety and an iminium cationic moiety, and preferably comprises an iminium cationic moiety. <4> The dye composition for regenerated collagen fibers according to any one of <1> to <3>, wherein the number of cationic moieties (b) in the component (A) is preferably 0 or more and 5 or less, more preferably 0 or more and 4 or less, even more preferably 0 or more and 3 or less, still more preferably 0 or more and 2 or less, and even more preferably 1 or more and 2 or less. <5> The dye composition for regenerated collagen fibers according to any one of <1> to <4>, wherein the difference (a-b) between the number of sulfonic acid groups in component (A) (a) and the number of cationic sites in component (A) (b) is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, and still more preferably 1 or more and 2 or less. <6>When the component (A) satisfies the above (1), the molecular weight of the component (A) is preferably 500 or more and 1,500 or less, more preferably 500 or more and 1,200 or less, even more preferably 500 or more and less than 1,000, still more preferably 500 or more and 900 or less, still more preferably 500 or more and 800 or less, still more preferably 500 or more and 780 or less, still more preferably 520 or more and 750 or less, still more preferably 520 or more and 750 or less, and still more preferably 540 or more and 750 or less. <7> The dye composition for regenerated collagen fibers according to any one of <1> to <6>, wherein, when the component (A) satisfies the above (2), [(a-b) / Mw] is preferably 0.0005 or more and 0.0045 or less, more preferably 0.0005 or more and 0.0040 or less, even more preferably 0.0010 or more and 0.0035 or less, and still more preferably 0.0010 or more and 0.0025 or less. <8> The dye composition for regenerated collagen fibers according to any one of <1> to <7>, wherein, when the component (A) satisfies the above (2), the molecular weight Mw is preferably 250 or more and 1,500 or less, more preferably 250 or more and 1,200 or less, 250 or more and even more preferably less than 1,000, still more preferably 250 or more and 900 or less, still more preferably 280 or more and 800 or less, still more preferably 280 or more and 780 or less, still more preferably 280 or more and 750 or less, still more preferably 300 or more and 750 or less, and still more preferably 320 or more and 750 or less. <9> The component (A) is preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Green 25 (Color Index No. 61570), AcidBrown 13(Color Index No.10410)、Acid Red 52(Color Index No.45100)、Acid Black 1(Color Index No.20470)、Acid Red 18(Color Index No.16255)、Acid Red 27(Color Index No.16185)、Acid Blue 3(Color Index No.42051)、Acid Green 50(Color Index No.44090)、Acid Red 73(Color Index No.27290)、Acid Blue 1(Color Index No.42045)、Acid Red 184(Color Index No.15685)、Acid Red 35(Color Index No.18065)、Acid Red 14(Color Index No.14720)、Food Red 6(Color Index No.16155)、Acid Orange 3(Color Index No.10385)、Acid Orange 24(Color Index No.20170)、Acid Violet 43(Color Index No.60730)、Acid Blue 62(Color Index No.62045)、Acid Red 88(Color Index No.15620)、Acid Yellow 11(Color Index No.18820)、Acid Yellow 36(Color Index No.13065)、Acid Yellow 1(Color Index No.10316)、Acid Orange 7(Color Index No.15510)、Acid Orange 20(Color Index No.14600)、Acid Orange 6(Color Index No.14270)、Food Red 17(Color Index No.16035)、Acid Red 41(Color Index No.16290)、Acid Red 1(Color Index No.18050)、Acid Red 155(Color Index No.18130)、Acid Red 180(Color IndexNo.18736), Acid Yellow 17 (Color Index No.18965), Acid Yellow 23 (Color Index No.19140), Acid Red 163 (Color Index No.24790), Food Black 2 (Color Index No.27755), Direct Orange 39 (Color Index No.40215), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Green 22 (Color Index No.42170), Acid Blue 104 (Color Index No.42735), Acid Violet 9 (Color Index No.45190), Acid Red 50 (Color Index No.45220), Acid Violet 50 (Color Index No.50325), Acid Black 2 (Color Index No.50420), Acid Blue 80 (Color Index The dye composition for regenerated collagen fibers according to any one of <1> to <8>, comprising one or more dyes selected from the group consisting of Acid Blue 87 (Color Index No. 61585), Acid Blue 87 (Color Index No. 74180), Acid Red 195 (Color Index No. 18760), Acid Red 249 (Color Index No. 18134), Acid Red 131, and Acid Red 337 (Color Index No. 17102). <10> The component (A) is more preferably Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42093), Acid Green 5 (Color Index No. 42094), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42096), Acid Green 5 (Color Index No. 42097), Acid Green 5 (Color Index No. 42098), Acid Green 5 (Color Index No. 42099), Acid Green 5 (Color Index No. 42090), Acid Green 5 (Color Index No. 42091), Acid Green 5 (Color Index No. 42092), Acid Green 5 (Color Index No. 42093), Acid Green 5 (Color Index No. 42094), Acid Green 5 (Color Index No. 42095), Acid Green 5 (Color Index No. 42096), Acid Green 5 (Color Index No. 42097), Acid Green 5 (Color Index No. 42098), Acid Green 5 (Color Index No. 42099), Acid Green 5 (Color Index No. 42099), Acid Green 5 (Color Index No. 42090), Acid Green 5 (Color Index No. 42091), Acid Green 5 (Color Index No. 42092), Acid Green 5 (Color Index No. 42093), Acid Green 5 (Color Index No. 42094), Acid Green 5 (Color Index No. 42094), Acid GreenAcid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), Acid Red 73 (Color Index No.27290), Acid Blue 1 (Color Index No.42045), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Blue 104 (Color Index No.42735), and Acid Violet 50 (Color Index The dye composition for regenerated collagen fibers according to <9>, further preferably containing one or more dyes selected from the group consisting of Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index No. 42090), Acid Blue 5 (Color Index No. 42052), Acid Green 3 (Color Index No. 42085), Acid Red 52 (Color Index No. 45100), Acid Blue 3 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), and Acid Blue 1 (Color Index No. 42045), each of which has a cationic moiety number (b) of 1 or more, and further preferably containing one or more dyes selected from the group consisting of Acid Blue 9 and Acid Red 52.

[0118] <11> The dye composition for regenerated collagen fibers according to any one of <1> to <10>, wherein the content of component (A) in the total acid dye in the dye composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more and 100% by mass or less. <12> The dye composition for regenerated collagen fibers according to any one of <1> to <11>, wherein the content of component (A) in the dye composition is preferably 0.001% by mass or more and 3.0% by mass or less, more preferably 0.002% by mass or more and 3.0% by mass or less, even more preferably 0.005% by mass or more and 1.0% by mass or less, still more preferably 0.01% by mass or more and 0.8% by mass or less, still more preferably 0.02% by mass or more and 0.6% by mass or less, still more preferably 0.03% by mass or more and 0.5% by mass or less, and still more preferably 0.05% by mass or more and 0.2% by mass or less. <13> The dye composition for regenerated collagen fibers according to any one of <1> to <12>, wherein the content of dyes other than acid dyes in the dye composition is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, even more preferably 0.02% by mass or less, still more preferably 0.01% by mass or less, still more preferably 0.001% by mass or less, even more preferably 0.0001% by mass or less, and even more preferably 0.0001% by mass or less, and may even be 0% by mass. <14> The dye composition for regenerated collagen fibers according to any one of <1> to <13>, wherein the content of water in the dye composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.999% by mass or less. <15> The dye composition for regenerated collagen fibers according to any one of <1> to <14>, wherein the pH of the dye composition is preferably 2.0 or more and 6 or less, more preferably 2.2 or more and 5 or less, and even more preferably 2.5 or more and 4 or less. <16> The dye composition for regenerated collagen fibers according to any one of <1> to <15>, wherein the dye composition is in the form of a liquid, paste, cream, gel, foam, spray, or wax, and is preferably a liquid.<17> The dye composition for regenerated collagen fibers according to any one of <1> to <16>, wherein the component (B1) comprises one or more selected from the group consisting of benzoic acid, sodium benzoate, and potassium benzoate, preferably one or more selected from the group consisting of benzoic acid and sodium benzoate. <18> The dye composition for regenerated collagen fibers according to any one of <1> to <17>, wherein the component (B2) comprises a copolymer containing structural units derived from one or more selected from the group consisting of unsaturated monocarboxylic acids and unsaturated dicarboxylic acids, and structural units derived from an aromatic vinyl compound, preferably one or more selected from the group consisting of styrene-maleic acid copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, vinylbenzoic acid-maleic acid copolymer, vinylbenzoic acid-acrylic acid copolymer, vinylbenzoic acid-methacrylic acid copolymer, and styrene-4-vinylbenzoic acid copolymer, more preferably styrene-maleic acid copolymer. <19> The dye composition for regenerated collagen fibers according to any one of <1> to <18>, wherein the ratio of the structural unit (u1) derived from the unsaturated monomer having a carboxy group to the structural unit (u2) derived from the aromatic vinyl compound monomer in the component (B2) is, in terms of molar ratio (u1 / u2), preferably 1 / 5 to 5 / 1, more preferably 1 / 3 to 3 / 1, and even more preferably 1 / 2 to 2 / 1. <20> The dye composition for regenerated collagen fibers according to any one of <1> to <19>, wherein the acid value of the component (B2) is preferably from 100 mgKOH / g to 1,000 mgKOH / g, more preferably from 200 mgKOH / g to 800 mgKOH / g, even more preferably from 200 mgKOH / g to 600 mgKOH / g, still more preferably from 300 mgKOH / g to 600 mgKOH / g, and still more preferably from 400 mgKOH / g to 600 mgKOH / g.

[0119] <21> The dye composition for regenerated collagen fibers according to any one of <1> to <20>, wherein the weight-average molecular weight of the component (B2) is preferably from 3,000 to 15,000, more preferably from 5,000 to 15,000, even more preferably from 6,000 to 15,000, and still more preferably from 6,000 to 10,000. <22> The dye composition for regenerated collagen fibers according to any one of <1> to <21>, wherein the component (B) preferably contains the component (B2), more preferably a styrene-maleic acid copolymer. <23> The dye composition for regenerated collagen fibers according to any one of <1> to <22>, wherein the content of component (B) in the modified regenerated collagen fibers is preferably 0.1% by mass to 70% by mass, more preferably 0.5% by mass to 65% by mass, even more preferably 1.0% by mass to 60% by mass, still more preferably 3.0% by mass to 55% by mass, even more preferably 5.0% by mass to 50% by mass, still more preferably 10% by mass to 45% by mass, even more preferably 15% by mass to 40% by mass, and still more preferably 20% by mass to 40% by mass. <24> The dye composition for regenerated collagen fibers according to any one of <1> to <23>, wherein the modified regenerated collagen fibers further contain, as component (C), a polyvalent metal, or a salt or complex thereof. <25> The dye composition for regenerated collagen fibers according to <24>, wherein the component (C) comprises 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 thereof, or a complex thereof, preferably one or more polyvalent metals selected from the group consisting of aluminum, zirconium, and titanium, or a salt thereof, or a complex thereof, and more preferably aluminum, or a salt thereof, or a complex thereof. <26> The dye composition for regenerated collagen fibers according to <24> or <25>, wherein the content of component (C) in the modified regenerated collagen fibers is, in terms of the amount of metal element, preferably 0.1% by mass or more and 40% by mass or less, more preferably 0.5% by mass or more and 30% by mass or less, even more preferably 1.0% by mass or more and 20% by mass or less, and even more preferably 2.0% by mass or more and 10% by mass or less.<27> A method for dyeing regenerated collagen fibers, the method comprising the step of applying a dye composition for regenerated collagen fibers to the regenerated collagen fibers, wherein the dye composition contains the following component (A) and water, and the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (B). <28> (A) an acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight-average molecular weight of 1,500 to 15,000, or a salt thereof. The dyeing method of <27>, wherein the method for applying the dye composition to the regenerated collagen fibers includes a method of applying the composition to the regenerated collagen fibers in a dry or wet state, or a method of immersing the regenerated collagen fibers in the composition, and preferably a method of applying the dye composition to the regenerated collagen fibers in a dry state, or a method of immersing the regenerated collagen fibers in the dye composition. <29> The dyeing method of <27> or <28>, wherein the amount of the dye composition applied to the regenerated collagen fibers is preferably a bath ratio (dry mass of regenerated collagen fibers:mass of dye composition), when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass, of 1:0.2 to 1:500.<30> The dyeing method according to <29>, wherein, when the dye composition is applied to the regenerated collagen fibers, the amount of the dye composition applied to the regenerated collagen fibers is, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass, the bath ratio (dry mass of regenerated collagen fibers:mass of dye composition) is more preferably 1:0.2 to 1:200, even more preferably 1:0.2 to 1:100, still more preferably 1:0.2 to 1:50, still more preferably 1:0.2 to 1:20, more preferably 1:0.5 to 1:10, even more preferably 1:0.5 to 1:5, and still more preferably 1:0.8 to 1:3.

[0120] <31> The dyeing method according to <29>, wherein, when the regenerated collagen fibers are immersed in the dye composition, the bath ratio (dry mass of regenerated collagen fibers:mass of dye composition) is more preferably 1:2 to 1:500, even more preferably 1:3 to 1:250, still more preferably 1:5 to 1:100, still more preferably 1:10 to 1:50, and still more preferably 1:10 to 1:20, when the mass of the fibers after conditioning at 20°C and a relative humidity of 65% for 24 hours is taken as the dry mass. <32> The dyeing method according to any one of <28> to <31>, wherein, when the dye composition is applied to the regenerated collagen fibers, the application time is preferably 10 seconds to 10 minutes, more preferably 20 seconds to 5 minutes. <33> The dyeing method according to any one of <28> to <30> and <32>, wherein after applying the dye composition to the regenerated collagen fibers, a step of leaving the fibers to stand is further carried out, and the leaving time is preferably from 1 minute to 1 hour, more preferably from 3 minutes to 30 minutes, and even more preferably from 5 minutes to 20 minutes. <34> The dyeing method according to any one of <28>, <29>, and <31>, wherein, when the regenerated collagen fibers are immersed in the dye composition, the immersion time is preferably from 10 seconds to 3 hours, more preferably from 10 seconds to 2 hours, and even more preferably from 30 seconds to 1 hour. <35> The dyeing method according to any one of <27> to <34>, wherein the temperature when the dye composition is applied to the regenerated collagen fibers is preferably from 5°C to 40°C, and more preferably from 10°C to 35°C. <36> The dyeing method according to any one of <27> to <35>, comprising a step of rinsing the dye composition applied to the regenerated collagen fibers after applying the dye composition to the regenerated collagen fibers. <37> The dyeing method according to any one of <27> to <36>, further comprising a step of drying the regenerated collagen fibers after applying the dye composition to the regenerated collagen fibers, and after a rinsing step, if any. <38> A colored modified regenerated collagen fiber, comprising the following component (A) and component (B):(A) An acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, of 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mg KOH / g or more and a weight average molecular weight of 1,500 to 15,000, or a salt thereof. <39> The colored modified regenerated collagen fiber according to <38>, further containing the component (C): a polyvalent metal, or a salt or complex thereof. <40> A fiber for headwear products, comprising the colored modified regenerated collagen fiber of <38> or <39>.

[0121] <41> A head accessory comprising the colored modified regenerated collagen fiber of <38> or <39>. <42> The fiber for head accessories of <39> or the head accessory of <40>, wherein the head accessory is a hair wig, a hairpiece, weaving, a hair extension, a braided hair, a hair accessory, or a doll hair.

[0122] <43> A dye composition for regenerated collagen fibers, the dye composition containing the following component (A) and water, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B).(A) Acid Black 52 (Color Index No.15711), Acid Green 1 (Color Index No.10020), Food Black 1 (Color Index No.28440), Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index (B) one or more acid dyes selected from the group consisting of Acid Green 50 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Orange 7 (Color Index No. 15510), Acid Red 249 (Color Index No. 18134), Acid Red 131 (no Color Index No.), and Acid Red 337 (Color Index No. 17102); (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight-average molecular weight of 3,000 or more and 15,000 or less.

[0123] <44> A method for dyeing regenerated collagen fibers, the method comprising the step of applying a dye composition for regenerated collagen fibers to the regenerated collagen fibers, wherein the dye composition contains the following component (A) and water, and the regenerated collagen fibers comprise modified regenerated collagen fibers containing the following component (B).(A) Acid Black 52 (Color Index No.15711), Acid Green 1 (Color Index No.10020), Food Black 1 (Color Index No.28440), Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index (B) one or more acid dyes selected from the group consisting of Acid Green 50 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Orange 7 (Color Index No. 15510), Acid Red 249 (Color Index No. 18134), Acid Red 131 (no Color Index No.), and Acid Red 337 (Color Index No. 17102); (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight-average molecular weight of 3,000 or more and 15,000 or less.

[0124] <45> A colored modified regenerated collagen fiber containing the following component (A) and component (B), wherein the colored modified regenerated collagen fiber is obtained by dyeing a modified regenerated collagen fiber containing component (B) using a dye composition containing component (A).(A) Acid Black 52 (Color Index No.15711), Acid Green 1 (Color Index No.10020), Food Black 1 (Color Index No.28440), Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index (B) one or more acid dyes selected from the group consisting of Acid Green 50 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Orange 7 (Color Index No. 15510), Acid Red 249 (Color Index No. 18134), Acid Red 131 (no Color Index No.), and Acid Red 337 (Color Index No. 17102); (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a styrene-maleic acid copolymer or a salt thereof having an acid value of 200 mgKOH / g or more and 600 mgKOH / g or less and a weight-average molecular weight of 3,000 or more and 15,000 or less.

[0125] <46> Component (A) is Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Red 52 (Color Index No.45100), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), and Acid Blue 1 (Color Index No.42045), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Blue 104 (Color Index No.42735), and Acid Violet 50 (Color Index <47> The dye composition of <43> or <46>, the dyeing method of <44> or <46>, or the colored modified regenerated collagen fiber of <45> or <46>, wherein the content of component (A) in the dye composition is 0.03% by mass or more and 0.1% by mass or less.

[0126] <48> The dye composition according to any one of <43>, <46> and <47>, the dyeing method according to any one of <44>, <46> and <47>, or the colored modified regenerated collagen fiber according to any one of <45> to <47>, wherein the component (B2) contains a styrene-maleic acid copolymer or a salt thereof having an acid value of from 200 mgKOH / g to 600 mgKOH / g and a weight-average molecular weight of from 6,000 to 15,000. <49> The dye composition of any one of <43> and <46> to <48>, the dyeing method of any one of <44> and <46> to <48>, or the colored modified regenerated collagen fiber of any one of <45> to <48>, wherein the modified regenerated collagen fiber contains, as component (B2), a styrene-maleic acid copolymer or a salt thereof having an acid value of 400 mgKOH / g or more and 600 mgKOH / g or less and a weight-average molecular weight of 6,000 or more and 10,000 or less. <50> The dye composition of any one of <43> and <46> to <49>, the dyeing method of any one of <44> and <46> to <49>, or the colored modified regenerated collagen fiber of any one of <45> to <49>, wherein component (B) contains component (B2). <51> The dye composition of any one of <43> and <46> to <50>, the dyeing method of any one of <44> and <46> to <50>, or the colored modified regenerated collagen fiber of any one of <45> to <50>, wherein the content of compound (B) in the modified regenerated collagen fiber is 20% by mass or more and 40% by mass or less.

[0127] <52> The dye composition of any one of <43> and <46> to <51>, the dyeing method of any one of <44> and <46> to <51>, or the colored modified regenerated collagen fiber of any one of <45> to <51>, wherein the modified regenerated collagen fiber contains aluminum or a salt or complex thereof as component (C). <53> The dye composition of <52>, the dyeing method of <52>, or the colored modified regenerated collagen fiber of <52>, wherein the content of component (C) in the modified regenerated collagen fiber is 2.0% by mass or more and 10% by mass or less, in terms of the amount of metal element.

[0128] <54> The dye composition of any one of <43> and <46> to <53>, wherein, when the dye composition is a paint-type dye, the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition is from 200 to 400. <55> The dye composition of any one of <43> and <46> to <53>, when the dye composition is a dip-type dye, the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition is from 10 to 60. <56> The dye composition of any one of <43> and <52> to <54>, when the dye composition is a paint-type dye, the mass ratio [(C) / (A)] of component (C) in the fiber for headwear to component (A) in the dye composition is from 25 to 100. <57> The dye composition according to any one of <43>, <52> to <53> and <55>, wherein, when the dye composition is a dip-type dye, the mass ratio [(C) / (A)] of the component (C) in the fiber for head accessories to the component (A) in the dye composition is 3 or more and 12 or less.

[0129] <58> The dyeing method according to any one of <44> and <46> to <53>, wherein, in the case of application by coating, the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition is from 200 to 400. <59> The dyeing method according to any one of <44> and <46> to <53>, in the case of application by immersion, the mass ratio [(B) / (A)] of component (B) in the fiber for headwear to component (A) in the dye composition is from 10 to 60. <60> The dyeing method according to any one of <52> to <53> and <58>, in the case of application by coating, the mass ratio [(C) / (A)] of component (C) in the fiber for headwear to component (A) in the dye composition is from 25 to 100. <61> The dyeing method according to any one of <52> to <53> and <59>, wherein, in the case of application by immersion, the mass ratio [(C) / (A)] of the component (C) in the fiber for head accessories to the component (A) in the dye composition is 3 or more and 12 or less.

[0130] <62> The colored modified regenerated collagen fiber of any one of <45> to <53>, wherein, when colored by application, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is from 200 to 400. <63> The colored modified regenerated collagen fiber of any one of <45> to <53>, wherein, when colored by immersion, the mass ratio [(B) / (A)] of component (B) in the fiber for head accessories to component (A) in the dye composition is from 10 to 60. <64> The colored modified regenerated collagen fiber of any one of <52> to <53> and <62>, wherein, when colored by application, the mass ratio [(C) / (A)] of component (C) in the fiber for head accessories to component (A) in the dye composition is from 25 to 100. <65> The colored modified regenerated collagen fiber according to any one of <52> to <53> and <63>, wherein, when colored by immersion, the mass ratio [(C) / (A)] of the component (C) in the fiber for head accessories to the component (A) in the dye composition is 3 or more and 12 or less.

[0131] <66> A head accessory product comprising the colored modified regenerated collagen fiber according to any one of <45> to <53> and <62> to <65>.

[0132] The present invention will be described below with reference to examples, but the present invention is not limited to the scope of the examples. In the examples, various measurements and evaluations were carried out by the following methods.

[0133] <pH Measurement> The pH at 25° C. was measured using a pH meter (F-72, manufactured by Horiba Ltd.).

[0134] Quantification of Benzoic Acid in Modified Regenerated Collagen Fibers In this specification, the quantification of benzoic acid contained in the modified regenerated collagen fiber B1 obtained in Production Example 2 was carried out using the following method. Reagents: 6N hydrochloric acid: titrant for volumetric analysis, manufactured by Kanto Chemical Co., Ltd. Sodium acetate: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Acetic acid: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Acetonitrile: for LC / MS, manufactured by Kanto Chemical Co., Ltd. Sodium benzoate: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Ultrapure water: water produced by ultrapure water production system Milli-Q, manufactured by Millipore Corporation Quantification Method: The sample (modified regenerated collagen fiber B1) was conditioned at 20°C and a relative humidity of 65% for 24 hours, then finely chopped. Approximately 10 mg of the sample was precisely weighed, and 3 mL of 6N hydrochloric acid was added. The mixture was then heated and dissolved at 50°C for 15 hours. After cooling, the solution was filtered to obtain a sample solution. Separately, sodium benzoate was dissolved in the mobile phase to prepare a standard solution with a benzoic acid concentration of 0.1 to 100 μg / mL. This was used to construct a calibration curve. Liquid chromatography (HPLC) measurements were performed using the sample solution and the standard solution, and the amount of benzoic acid was calculated from the ratio of the peak area of ​​the sample solution to that of the standard solution. Measurement conditions: Detector: UV-Visible Spectrophotometer; Measurement Wavelength: 230 nm; Column: A stainless steel tube with an inner diameter of 21 mm and a length of 150 mm was packed with 5 μm octadecylsilylated silica gel for liquid chromatography. Column temperature: A constant temperature of approximately 40°C. Mobile phase: Approximately 0.68 g of sodium acetate and 0.91 g of acetic acid were dissolved in 750 mL of ultrapure water, followed by the addition of 250 mL of acetonitrile and mixing. HPLC / UV conditions: Apparatus: UltiMate 3000 system (Thermo Fisher Scientific) 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 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

[0135] <Weight-Average Molecular Weight of Styrene-Maleic Acid Copolymer> In this specification, the weight-average molecular weight of the styrene-maleic acid copolymer was measured under the following conditions, and the weight-average molecular weight in terms of polystyrene was determined. (1) Reagents: Ultrapure water: water produced by an ultrapure water production system, Milli-Q, manufactured by Millipore Corporation; Dimethylformamide (DMF): special grade, manufactured by Kanto Chemical Co., Ltd.; Lithium bromide monohydrate (LiBr): special grade, manufactured by Kanto Chemical Co., Ltd.; Phosphoric acid: special grade, manufactured by Sigma-Aldrich Co., Ltd. (2) Sample Pretreatment Method: Approximately 50 mg of sample was precisely weighed, 0.5 mL of ultrapure water was added, and 10 mL of the mobile phase described below was added to dissolve the solution, which was then filtered to obtain a sample solution. (3) Measurement: Using the sample solution and standard solution, gel permeation chromatography (GPC) was performed under the following conditions to determine the weight-average molecular weight in terms of polystyrene. Flow rate: 1 mL / min Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr Column: TSKgel α (alpha) column (manufactured by Tosoh Corporation) Detector: RI (differential refractometer)

[0136] <Quantitative Analysis of Styrene-Maleic Acid Copolymer in Modified Regenerated Collagen Fiber> In this specification, the quantitative analysis of the styrene-maleic acid copolymer in the modified regenerated collagen fiber B2 obtained in Production Example 3 was carried out by the following method. (1) Reagents: 1 mol / L aqueous sodium hydroxide solution: for volumetric analysis, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Ultrapure water: water produced by an ultrapure water production system, Milli-Q, manufactured by Millipore Corporation Dimethylformamide (DMF): special grade, manufactured by Kanto Chemical Co., Inc. Lithium bromide monohydrate (LiBr): special grade, manufactured by Kanto Chemical Co., Inc. Phosphoric acid: special grade, manufactured by Sigma-Aldrich (2) Sample Solution: The sample (modified regenerated collagen fiber) was conditioned at 20°C and a relative humidity of 65% for 24 hours, then finely chopped, and approximately 50 mg was precisely weighed out. 10 mL of 1 mol / L aqueous sodium hydroxide solution was added and the mixture was dissolved by heating at 50°C for 3 hours. The pH of the solution was adjusted to 4.7-5.3, and the freeze-dried sample was diluted with 0.5 mL of ultrapure water and 9.5 mL of the mobile phase described below. The diluted solution was filtered to prepare the sample solution. (3) Preparation of calibration curve solution: Separately, styrene-maleic acid copolymer was dissolved in the mobile phase described below to prepare a non-dissociated styrene-maleic acid copolymer with a concentration of 0.25-5.0 mg / mL, which was used as the standard solution for drawing the calibration curve. (4) Measurement: Using the sample solution and the standard solution, gel permeation chromatography (GPC) measurements were performed under the following conditions, and the peak areas of the sample solution and the standard solution were determined. A calibration curve was also prepared based on the peak area results of the standard solution. Flow rate: 0.8 mL / min Mobile phase: DMF containing 60 mM phosphoric acid and 50 mM LiBr Column: TSKgel α (Alpha) column (manufactured by Tosoh Corporation) Detector: UV-visible spectrophotometer Measurement wavelength: 267 nm (5) Calculation of the amount of styrene-maleic acid copolymer The amount of styrene-maleic acid copolymer per mass of fiber was calculated using a calibration curve created based on the peak area derived from the styrene-maleic acid copolymer contained in the modified regenerated collagen fibers.

[0137] <Quantification of Aluminum in Modified Regenerated Collagen Fibers> In this specification, the quantification of aluminum in modified regenerated collagen fibers was performed using the following method. (1) Reagents: Sulfuric acid: precision analysis grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Hydrochloric acid: metal analysis grade, manufactured by Kanto Chemical Co., Ltd. Sodium carbonate: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Boric acid: special grade, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Aluminum standard solution: 1000 mg / L for atomic absorption spectrometry, manufactured by Kanto Chemical Co., Ltd. Ultrapure water: water produced by ultrapure water production system Milli-Q, manufactured by Millipore Corporation. (2) Sample Pretreatment Method: A fiber bundle of modified regenerated collagen fibers was hung in a dryer (SOFW-450SB, AS ONE Corporation) set to 60°C, a 250 g weight was attached to the bottom end of the fiber bundle, and the fiber was dried for 1 hour with tension applied to the entire fiber. The fiber was then removed from the dryer and conditioned at 20°C and 65% relative humidity for 24 hours. 0.1 g of sample (modified regenerated collagen fiber) was precisely weighed into a platinum crucible and heated until no white smoke was produced. Several drops of sulfuric acid were added, and the mixture was heated again until no white smoke was produced. It was then thoroughly incinerated in a 550°C electric furnace. 1 g of alkaline flux (sodium carbonate:boric acid = 1:0.4) was then added and melted in a 950°C electric furnace. A watch glass was placed over the sample, and 5 mL of ultrapure water and hydrochloric acid (6 mol / L) were added. The mixture was heated and dissolved on a hot plate at 70-80°C. After cooling, the solution was adjusted to a constant volume of 50 mL with ultrapure water. This solution was used as the measurement solution. (3) Preparation of Calibration Solutions: Calibration solutions ranging from 0.1 to 20 mg / L were prepared using an aluminum standard solution (1000 mg / L). Alkaline flux and hydrochloric acid were added to each solution to achieve the same concentration as the measurement solution. (4) Measurement: Using the prepared measurement solutions, each element was measured using an ICP atomic emission spectrometer under the following conditions. Analysis device: iCAP6500Duo (manufactured by Thermo Fisher Scientific) 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

[0138] Production Example 1 (Production of Regenerated Collagen Fiber C0) Cattle split hide was solubilized with alkali according to a conventional method to prepare a spinning dope, which was then discharged from a spinning nozzle into a coagulation bath to produce regenerated collagen fibers. The regenerated collagen fibers were immersed in 30 parts by mass of an aqueous solution containing 5.0% by mass of aluminum sulfate 14-18 hydrate, 0.65% by mass of citric acid monohydrate, and 1.3% by mass of sodium hydroxide (component (C))) at 30°C with circulation, with the dry mass being the fiber mass after conditioning at 20°C and 65% relative humidity for 24 hours. A 5% aqueous solution of sodium hydroxide was then added in portions over approximately 1 to 5 hours to adjust the final pH of the solution to 4.5 to 5.0 after 5 hours. The fibers were then left in the solution for another 3 hours and thoroughly washed with water to obtain regenerated collagen fiber C0.

[0139] Production Example 2 (Production of Modified Regenerated Collagen Fiber B1) The regenerated collagen fiber C0 obtained in Production Example 1 was treated according to the following procedure to obtain modified regenerated collagen fiber B1. (Procedure 1) Ten 30 cm fiber bundles (amount that would weigh 1.5 g when dried at 60°C for 1 hour and then left at 20°C and 65% RH for 12 hours) were prepared from the regenerated collagen fiber C0 for each Example and Comparative Example. (Procedure 2) Benzoic acid (Wako Special Grade Reagent, Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight: 122), component (B1), was dissolved in water, and the pH was adjusted to 6.0 with a pH adjuster (sodium hydroxide) to prepare a fiber treatment agent containing 25.4 mass% benzoic acid. The fiber bundles were immersed in a separate container in an amount of fiber treatment agent such that the bath ratio (mass of fiber bundle after drying in Step 1: mass of fiber treatment agent) was 1:30, and the opening of each container was sealed. (Procedure 3) The entire container was immersed in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set to 40°C and left to stand for 5 minutes. The liquid temperature in the container was raised to 40°C, and then the container was removed from the water bath. (Procedure 4) The container containing the fiber bundle was placed on a stirring rotor (VMR-5R, AS ONE Corporation) installed in a dryer (SOFW-450SB, AS ONE Corporation) set to 40°C, and the container was rotated at a rotation speed of 80 rpm and heated and stirred for 3 hours. (Procedure 5) The container containing the fiber bundle was removed from the dryer and allowed to return to room temperature. The fiber bundle was then removed from the container and rinsed with running tap water at 30°C for 30 seconds, and the flow of the fibers was adjusted with a comb. (Step 6) The fiber bundles were hung one by one in a dryer set at 60°C, and a 250g weight was attached to the bottom end of each fiber bundle, and dried for 1 hour with tension applied to the entire fiber. (Step 7) The fiber bundles were removed from the dryer, returned to room temperature, and the weight was removed.

[0140] The content of benzoic acid in the modified regenerated collagen fiber B1 produced in Production Example 2 above was 27.3% by mass calculated as benzoic acid, and the content of aluminum was 5.7% by mass.

[0141] Production Example 3 (Production of Modified Regenerated Collagen Fiber B2) The regenerated collagen fiber C0 obtained in Production Example 1 was treated according to the following procedure to obtain modified regenerated collagen fiber B2. (Procedure 1) Ten 30 cm long fiber bundles (amount sufficient to yield a mass of 1.5 g when dried at 60°C for 1 hour and then left at 20°C and 65% RH for 12 hours) were prepared from the regenerated collagen fiber C0 for each Example. First, the following (Procedure 2) to (Procedure 5) were carried out using the B2a agent shown in Table 2. Agents B2a and B2b shown in Table 2 were prepared by blending and mixing the respective components listed in Table 2 using styrene-maleic acid copolymer (XIRAN1000HNa, manufactured by Polyscope, weight average molecular weight (Mw): 9195, acid value: 475 mg KOH / g, styrene / maleic acid molar ratio: 1 / 1) as component (B2). (Procedure 2) The fiber bundles prepared in (Procedure 1) were immersed in a container, one bundle at a time, in an amount of B2a agent such that the bath ratio (mass of fiber bundle after drying in Procedure 1: mass of B2a agent) was 1:30, and the opening of each container was sealed. (Procedure 3) The container was immersed in a water bath (TBS221FA, Toyo Seisakusho Co., Ltd.) set at 40°C and left to stand for 5 minutes. The liquid temperature in the container was then raised to 40°C, and the container was then removed from the water bath. (Procedure 4) The container containing the fiber bundle was placed on a stirring rotor (VMR-5R, AS ONE Corporation) installed in a dryer (SOFW-450SB, AS ONE Corporation) set at 40°C, and the container was rotated at a rotation speed of 80 rpm, and heated and stirred for 6 hours. (Procedure 5) The container containing the fiber bundle was removed from the dryer and allowed to return to room temperature. The fiber bundle was then removed from the container, rinsed with running tap water at 30°C for 30 seconds, and the fiber flow was adjusted with a comb. (Procedure 6) The fiber bundle obtained in (Procedure 5) was subjected to (Procedure 2) to (Procedure 5) again, using the B2b agent shown in Table 2 instead of the B2a agent. However, the heating and stirring time in (Procedure 4) was set to 1 hour. (Procedure 7) The fiber bundles obtained in (Procedure 6) were hung one by one in a dryer set to 60°C, and a 250g weight was attached to the bottom end of each fiber bundle. Drying was performed for 1 hour with tension applied to the entire fiber. (Procedure 8) The fiber bundle was removed from the dryer, allowed to return to room temperature, and the weight was removed.

[0142] The blending amounts (% by mass) listed in Table 2 are all amounts of active ingredients. The content of styrene-maleic acid copolymer in the modified regenerated collagen fiber B2 produced in Production Example 3 above was 31.4% by mass, and the content of aluminum was 5.5% by mass.

[0143] <Preparation of dye composition for regenerated collagen fibers> Examples 1 to 7, Comparative Example 1 The components shown in Table 3 were blended in the blending ratios shown in Table 3 and mixed until uniform. The pH was then adjusted to 3.0 using lactic acid or sodium hydroxide to prepare a dye composition for regenerated collagen fibers.

[0144] <Evaluation of dye compositions for regenerated collagen fibers> Examples 8 to 15, Comparative Example 2 Using the dye compositions obtained, dyeability and fastness were evaluated by the following methods. The results are shown in Table 3.

[0145] <Dyeability (color difference before and after dyeing ΔE * ab1)> (Dyeing step) A fiber bundle having a length of 10 cm and a mass of 1 g was prepared using the modified regenerated collagen fibers described in Table 3. The fiber bundle was washed with plain shampoo having the following composition, then rinsed with warm water at 40°C, and thoroughly dried with a dryer. The hue (L0) of the fiber bundle (before dyeing) was * , a0 * , b0 * ) was measured using a color difference meter (CR-400, Konica Minolta, Inc.). * , a0 * , b0 *The values ​​for each were measured at six points per fiber bundle, and the average value was calculated. Next, the fiber bundle was immersed in a container in an amount of dye composition such that the bath ratio shown in the table (the bath ratio was calculated based on 1 g of the dry mass of the fiber) was determined when the mass of the fiber after conditioning for 24 hours at 20°C and a relative humidity of 65% was taken as the dry mass, and the container was sealed. The container was left to stand in a dryer (SOFW-450SB, AS ONE Corporation) set to the temperature shown in the table. After leaving for 30 minutes, the fiber bundle was rinsed with warm water at 40°C for 30 seconds to wash away the dye composition, and the operation of lathering with a plain shampoo having the following composition for 15 seconds and then rinsing with warm water at 40°C for 15 seconds was repeated twice. Next, a plain conditioner having the following composition was applied for 15 seconds, followed by rinsing with warm water at 40°C for 15 seconds, and the fiber bundle was thoroughly dried with cold air from a dryer. The dried fiber bundle (dyed fiber bundle) was measured for hue (L1 * , a1 * , b1 * The color difference ΔE before and after dyeing of the fiber bundle was calculated using the following formula: * ab1 was calculated and shown in Table 3. ΔE * A larger ab1 value means higher staining ability.

[0146] ΔE * ab1 = [(L1 * -L0 * ) 2 + (a1 * -a0 * ) 2 + (b1 * -b0 * ) 2 〕 1 / 2

[0147] (Composition of plain shampoo) Ingredients (mass%) Polyoxyethylene (2) sodium lauryl ether sulfate (*1) 15.5 Lauric acid diethanolamide (*2) 1.5 Edetic acid tetrasodium salt 0.3 Sodium benzoate 1.43 Purified water Remaining amount Total 100.0 *1: Emar 227 (manufactured by Kao Corporation, 57.4 mass% as active ingredient 27 mass%) *2: Aminone L-02 (manufactured by Kao Corporation)

[0148] (Composition of plain conditioner) Ingredients (mass %) Trimethylstearylammonium chloride (*1) 1.01 Distearyldimethylammonium chloride (*2) 2.0 Propylene glycol 5.0 Cetanol (*3) 2.0 Isopropyl alcohol 0.4 Methyl parahydroxybenzoate (*4) 0.1 Purified water Remaining amount Total 100.0 *1: 3.6 mass% of Coatamine 86W (manufactured by Kao Corporation, active ingredient 28% by mass) *2: 2.7 mass% of Coatamine D86P (manufactured by Kao Corporation, active ingredient 75% by mass) *3: Kalcol 6870 (manufactured by Kao Corporation) *4: Mekkinsu M (manufactured by Ueno Pharmaceutical Co., Ltd.)

[0149] <Fastness (color difference ΔE before and after washing) *ab2)> The dyed fiber bundle obtained in the above "dyeability" evaluation was used as the "fiber bundle before washing." The fiber bundle before washing was immersed in a container containing 15 g of a solution prepared by diluting the plain shampoo 10 times with purified water, and the container containing the fiber bundle was placed on a stirring rotor (VMR-5R, AS ONE Corporation) installed in a dryer (SOFW-450SB, AS ONE Corporation) set at 40°C, and the container was rotated at a rotation speed of 80 rpm, and heated and stirred for 90 minutes. The container containing the fiber bundle was removed from the dryer and returned to room temperature, after which the fiber bundle was removed from the container, rinsed with running tap water at 40°C for 30 seconds, and thoroughly dried with cold air from a dryer. The dried fiber bundle (fiber bundle after washing) was measured for hue (L2 * , a2 * , b2 * The color difference ΔE before and after washing of the fiber bundle was calculated using the following formula: * ab2 was calculated and shown in Table 3. ΔE * The smaller the value of ab, the higher the robustness.

[0150] ΔE * ab2 = [(L1 * -L2 * ) 2 + (a1 * -a2 * ) 2 + (b1 * -b2 * ) 2 〕 1 / 2 The blending amounts (mass %) shown in Table 3 are all amounts of active ingredients.

[0151]

[0152] Table 3 shows that the dye composition of the present invention has better dye fastness after dyeing of a specified modified regenerated collagen fiber than the dye composition of Comparative Example 1, which uses an acid dye that does not fall under component (A).

[0153] The effects of the present invention can also be achieved using the modified regenerated collagen fiber shown in Formulation Example 1. Formulation Example 1: XIRAN3000HNa (weight average molecular weight (Mw): 13,803, acid value: 285 mg KOH / g, styrene / maleic acid molar ratio: 3 / 1, manufactured by Polyscope) is used instead of XIRAN1000HNa (manufactured by Polyscope), and the regenerated collagen fiber C0 obtained in Production Example 1 is treated in the same manner as in Production Example 3 to obtain modified regenerated collagen fiber B3. Next, using the dye composition shown in Table 3, the modified regenerated collagen fiber B3 is treated in the same manner as in the procedure shown under <Dyeability>.

[0154] The effects of the present invention can also be achieved by using the staining composition of Formulation Example 2 shown in Table 4 or the staining compositions of Formulation Examples 3 to 8 shown in Table 5.

[0155]

[0156]

[0157] According to the present invention, a dye composition for regenerated collagen fibers that uses a dye and has excellent fastness after dyeing can be provided.

Claims

1. A dye composition for regenerated collagen fibers, the dye composition containing the following component (A) and water, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B): (A) An acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) where Mw is the molecular weight, the value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1500 to 15000, or a salt thereof.

2. The component (A) is Acid Black 52 (Color Index No.15711), Acid Green 1 (Color Index No.10020), Food Black 1 (Color Index No.28440), Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), Acid Red 73 (Color Index No.27290), Acid Blue 1 (Color Index No.42045), Acid Red 184 (Color Index No.15685), Acid Red 35 (Color Index No.18065), Acid Red 14 (Color Index No.14720), Food Red 6 (Color Index No.16155), Acid Orange 3 (Color Index No.10385), Acid Orange 24 (Color Index No.20170), Acid Violet 43 (Color Index No.60730), Acid Blue 62 (Color Index No.62045), Acid Red 88 (Color Index No.15620), Acid Yellow 11 (Color Index No.18820)、Acid Yellow 36(Color Index No.13065)、Acid Yellow 1(Color Index No.10316)、Acid Orange 7(Color Index No.15510)、Acid Orange 20(Color Index No.14600)、Acid Orange 6(Color Index No.14270)、Food Red 17(Color Index No.16035)、Acid Red 41(Color Index No.16290)、Acid Red 1(Color Index No.18050)、Acid Red 155(Color Index No.18130)、Acid Red 180(Color Index No.18736)、Acid Yellow 17(Color Index No.18965)、Acid Yellow 23(Color Index No.19140)、Acid Red 163(Color Index No.24790)、Food Black 2(Color Index No.27755)、Direct Orange 39(Color Index No.40215)、Acid Blue 7(Color Index No.42080)、Acid Green 9(Color Index No.42100)、Acid Green 22(Color Index No.42170)、Acid Blue 104(Color Index No.42735)、Acid Violet 9(Color Index No.45190)、Acid Red 50(Color Index No.45220)、Acid Violet 50(Color Index No.50325)、Acid Black 2(Color Index No.50420)、Acid Blue 80(Color Index No.61585)、Acid Blue 87(Color Index No.74180)、Acid Red 195(Color Index No.18760)、Acid Red 249(Color Index No.18134), Acid Red 131, and Acid Red 337 (Color Index No. 17102).

3. The component (A) is Acid Black 52 (Color Index No. 15711), Acid Green 1 (Color Index No. 10020), Food Black 1 (Color Index No. 28440), Food Green 3 (Color Index No. 42053), Acid Green 5 (Color Index No. 42095), Acid Blue 9 (Color Index). No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Green 25 (Color Index No.61570), Acid Brown 13 (Color Index No.10410), Acid Red 52 (Color Index No.45100), Acid Black 1 (Color Index No.20470), Acid Red 18 (Color Index No.16255), Acid Red 27 (Color Index No.16185), Acid Blue 3 (Color 3. The dye composition for regenerated collagen fibers according to claim 1, comprising one or more dyes selected from the group consisting of Acid Green 50 (Color Index No. 42051), Acid Green 50 (Color Index No. 44090), Acid Red 73 (Color Index No. 27290), Acid Blue 1 (Color Index No. 42045), Acid Orange 7 (Color Index No. 15510), Acid Red 249 (Color Index No. 18134), Acid Red 131 (no Color Index No.), and Acid Red 337 (Color Index No. 17102).

4. A dye composition for regenerated collagen fibers according to any one of claims 1 to 3, wherein the number of cationic sites (b) is 1 or more.

5. The component (A) is Food Green 3 (Color Index No.42053), Acid Green 5 (Color Index No.42095), Acid Blue 9 (Color Index No.42090), Acid Blue 5 (Color Index No.42052), Acid Green 3 (Color Index No.42085), Acid Red 52 (Color Index). No.45100), Acid Blue 3 (Color Index No.42051), Acid Green 50 (Color Index No.44090), and Acid Blue 1 (Color Index No.42045), Acid Blue 7 (Color Index No.42080), Acid Green 9 (Color Index No.42100), Acid Blue 104 (Color Index No.42735), and Acid Violet 50 (Color Index The regenerated collagen fiber dye composition according to any one of claims 1 to 4, comprising one or more dyes selected from the group consisting of dyes containing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 39, 39, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 6. A dye composition for regenerated collagen fibers described in any one of claims 1 to 5, wherein the content of component (A) in the dye composition is 0.001% by mass or more and 3.0% by mass or less.

7. A dye composition for regenerated collagen fibers according to any one of claims 1 to 6, wherein component (B) includes component (B2).

8. A dye composition for regenerated collagen fibers according to any one of claims 1 to 7, wherein component (B2) comprises a styrene-maleic acid copolymer.

9. A method for dyeing regenerated collagen fibers, the method comprising the step of applying a dye composition for regenerated collagen fibers to the regenerated collagen fibers, the dye composition containing the following component (A) and water, and the regenerated collagen fibers comprising modified regenerated collagen fibers containing the following component (B). (A) An acid dye having a sulfonic acid group and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) where Mw is the molecular weight, the value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], is 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing a structural unit derived from an unsaturated monomer having a carboxy group and a structural unit derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight average molecular weight of 1500 to 15000, or a salt thereof.

10. Colored modified regenerated collagen fiber containing the following components (A) and (B): (A) an acid dye having sulfonic acid groups and satisfying at least one of the following conditions (1) and (2): (1) a molecular weight of 500 or more; (2) a value obtained by dividing the difference (a-b) between the number of sulfonic acid groups (a) and the number of cationic moieties (b) by Mw, [(a-b) / Mw], where Mw is the molecular weight, of 0.0045 or less; (B) one or more compounds selected from the group consisting of the following components (B1) and (B2): (B1) benzoic acid or a salt thereof; (B2) a copolymer containing structural units derived from an unsaturated monomer having a carboxy group and structural units derived from an aromatic vinyl compound, the copolymer having an acid value of 100 mgKOH / g or more and a weight-average molecular weight of 1,500 to 15,000, or a salt thereof.

11. A headwear product comprising the colored modified regenerated collagen fiber according to claim 10.

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