Research on Degumming and Fixing Sericin to Obtain Sericin-fixed Souple Silk Yarns without Formaldehyde

In order to obtain sericin-fixed souple silk yarns, various conditions of degumming and fixing sericin were investigated. When raw silk yarns were degummed with solutions of soap and sodium carbonate and then fixed with sericin-fixing agents, degumming losses of 6–17% were attained. The degumming losses attained by degumming and fixing simultaneously in a solution of soap and sodium carbonate containing sericin-fixing agents were in the range of 6–9 percent. By one-step degumming with detergent after fixing sericin, sericin-fixed souple silk yarns were also obtained. In the case of two-step degumming successively twice at 60°C for 30 minutes and at 80°C for 30 minutes with detergent after fixing sericin at 60–80°C for 15 minutes with melamine and formaldehyde, the degumming losses were in the range of 7–13% and sericin removal was uniform. Two-step degumming was very effective for the elimination of free formaldehyde from silk yarns fixed with melamine and formaldehyde.