Solution-dyed protein fiber and method for producing same

1. A solution-dyed protein fiber comprising:

a protein fiber comprising at least one material selected from the group consisting of silk fibroin and a polypeptide derived from spider silk proteins; and

a solution-dyeing colorant,

wherein an amount of the silk fibroin in the protein fiber is in a range of 0-100 mass %, and an amount of the polypeptide derived from spider silk proteins therein is in a range of 100-0 mass %, when an amount of the protein fiber is 100 mass %,

the solution-dyeing colorant is dissolved or dispersed in a spinning solution, of which the solution-dyed protein fiber is formed,

the spinning solution further comprises dimethyl sulfoxide, or N,N-dimethylformamide, or a combination thereof, and

at least one material selected from the group consisting of dimethyl sulfoxide and N, N-dimethylformamide is present in the solution-dyed protein fiber.

2. The solution-dyed protein fiber according to claim 1 ,

wherein the solution-dyeing colorant is at least one material selected from the group consisting of dyes and pigments.

3. The solution-dyed protein fiber according to claim 1 ,

wherein the solution-dyeing colorant is at least one material selected from the group consisting of an acid dye, a basic dye, a fluorescent dye, a direct dye, a disperse dye, a plant pigment, a food natural pigment, and a carbon black.

4. The solution-dyed protein fiber according to claim 1 ,

wherein an amount of the solution-dyeing colorant in the solution-dyed protein fiber is in a range from 0.1 to 2 mass % relative to the protein fiber as 100 mass %.

5. The solution-dyed protein fiber according to claim 1 ,

wherein the solution-dyed protein fiber has a diameter in a range from 5 to 200 μm.

6. The solution-dyed protein fiber according to claim 1 ,

wherein the solution-dyed protein fiber further comprises at least one inorganic salt selected from the group consisting of alkali metal halides, alkaline-earth metal halides, alkaline-earth metal nitrate, and sodium thiocyanate.

7. A method for producing a solution-dyed protein fiber,

wherein the solution-dyed protein fiber comprises:

a protein fiber comprising at least one material selected from the group consisting of silk fibroin and a polypeptide derived from spider silk proteins; and

a solution-dyeing colorant,

wherein an amount of the silk fibroin in the protein fiber is in a range of 0-100 mass %, and an amount of the polypeptide derived from spider silk proteins therein is in a range of 100-0 mass %, when an amount of the protein fiber is 100 mass %, and

at least one material selected from the group consisting of dimethyl sulfoxide and N, N-dimethylformamide is present in the solution-dyed protein fiber, and

the method comprises:

dissolving or dispersing the solution-dyeing colorant in a spinning solution, of which the solution-dyed protein fiber is formed, and which further comprises at least one solution selected from the group consisting of dimethyl sulfoxide and N,N-dimethylformamide, thereby forming a coloring liquid;

adding a solvent to the coloring liquid in an amount necessary for a spinning solution;

adding and dissolving protein powder that is capable of forming the protein fiber into the solvent, thereby forming the spinning solution; and

subjecting the spinning solution to wet spinning or dry-wet spinning.

8. The method for producing a solution-dyed protein fiber according to claim 7 ,

wherein an undrawn yarn of the solution-dyed protein fiber after the wet spinning is heat drawn under dry heat.

9. The method for producing a solution-dyed protein fiber according to claim 8 ,

wherein the dry-heat drawing is performed at a temperature of 160° C. or higher and at a draw ratio in a range from 1.05 to 4 times.

10. The method for producing a solution-dyed protein fiber according to claim 8 ,

wherein, before the dry-heat drawing, the undrawn yarn is drawn in water bath in advance.

11. The method for producing a solution-dyed protein fiber according to claim 10 ,

wherein the water-bath drawing is performed at a temperature in a range from 30° C. to 90° C. and at a draw ratio in a range from 1.05 to 6 times.

12. The method for producing a solution-dyed protein fiber according to claim 7 ,

wherein the solution-dyeing colorant is at least one material selected from the group consisting of dyes and pigments.

13. The method for producing a solution-dyed protein fiber according to claim 7 ,

wherein the solution-dyeing colorant is at least one material selected from the group consisting of an acid dye, a basic dye, a fluorescent dye, a direct dye, a disperse dye, a plant pigment, a food natural pigment, and a carbon black.

14. The method for producing a solution-dyed protein fiber according to claim 7 , wherein the solution-dyeing colorant is added in an amount in a range from 0.1 to 2 mass % relative to the protein fiber as 100 mass %.

15. The method for producing a solution-dyed protein fiber according to claim 7 ,

wherein, as the solvent that dissolves the protein powder, the spinning solution includes a solution comprising dimethyl sulfoxide and at least one inorganic salt selected from the group consisting of alkali metal halides, alkaline-earth metal halides, alkaline-earth metal nitrate, and sodium thiocyanate.