Dyeing Property of Silkworm Cocoon

Abstract

Silk is usually dyed at the fabric or yarn stage. It is difficult to dye silk fibers at the cocoon stage because (1) cocoon loses its original shape and (2) dye cannot penetrate easily into the cocoon shell. This study is the first attempt at dyeing cocoons adequately while retaining their shapes. Cocoons were dyed with a reactive dye under various conditions. When the dyeing process was carried out for several hours without a surfactant, the cocoon shells were not dyed adequately from 293 K to 333 K, furthermore at 333 K the silk filaments on the surfaces of the cocoons came loose and were entangled. In contrast, the cocoon shells were almost completely dyed when a surfactant, namely, sodium dodecyl sulfate, was used; in this case, the concentration of the surfactant was greater than the critical micelle concentration. The results suggest that the use of a surfactant and an appropriate temperature are useful for dyeing cocoons.