Abstract:

To solve the bleaching problem of grey down, the selective bleaching process was applied. Based on the studies of pretreatment (metal complex), cleaning and bleaching, the factors affecting whiteness and bulkiness in each procedure were investigated and the bleaching parameters were optimized. After combination treatment of selective oxidation bleaching and reduction bleaching, the whiteness of grey down fibers increased from 29% to 68%, while keeping their good bulkiness. SEM and FT-IR analysis indicated that the treatment had little influence on the physical structure of grey down, though it led to some changes in the chemical structure on the surface of the fibers, mainly the oxidation of disulfide bond of cystine. The optimized bleaching technology had excellent bleaching effect which solved the contradictions between whiteness and tendering in the bleaching of grey down, and showed energy saving and consumption reduction.