Zinc-free preparation of rayon fibers

摘要

Rayon fibers having a C-shaped cross section and characterized by low caustic solubility are prepared from an unmodified viscose spinning solution having a salt index below 14 by spinning the viscose solution into a zinc-free coagulation bath containing at least 100 g/l of Na2SO4, at least 175 g/l of (NH4)2SO4 and more than 100 g/l of H2SO4 while the bath is at a temperature above 40 DEG C. The coagulated filament is then stretched in a secondary bath maintained at a temperature over 70 DEG C.