Solution-dyed protein fiber and method for producing same

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.