Dyeing properties of silk produced by silkworms reared on artificial and mulberry leaf diets

The dyeing properties were investigated for silk proteins produced by silkworms reared entirely on an artificial diet (A) and a mulberry leaf diet (M). The dyeing experiments were carried out with CI acid orange 7 at pH 3.9 and 60°C. The sericin contents of the A and the M raw silk samples were determined to be 26.0% and 23.7%, respectively. The equilibrium dye uptake and the dyeing rate of the A silk fibroin were almost the same as those of the M silk fibroin. The equilibrium dye uptake on each silk sericin was 3–4 times higher than that of the silk fibroin. On the other hand, the equilibrium dye uptake of the A silk sericin was higher than that of the M silk sericin, but the dyeing rate of the former was slower than that of the latter.