PURPOSE: To obtain silk fibroin powder having the shape of short-cut filament and useful as a cosmetic base, pharmaceutical additive, etc., easily, by heating silk yarn, etc. in water contained in an autoclave under pressure, and drying and pulverizing the treated silk.
CONSTITUTION: Silk fibroin powder is prepared by immersing silk yarn (e.g. cocoon, waste cocoon, raw silk, waste raw silk, silk thread, silk fabrics, etc.) in water contained in an autoclave, heating the yarns in the autoclave under pressure[≥4kg/cm2G (saturation temperature: ≥151°C), preferably 6W13kg/ cm2G (saturation temperature: 164W194°C), for ≥10min, preferably 30W240min], and drying and pulverizing the treated yarns. As an alternative method, the silk yarn heat-treated by the above procedure is further treated in an autoclave under high pressure with saturated steam or superheated steam, and released instantaneously to a low pressure atmosphere to obtain expanded silk yarn, which is dried and pulverized to silk fibroin powder.
AKEDA YOSHIHIRO
HAYASHIYA KEIZOU
