International Telephone and Telegraph Corporation

Peter J Hartmann

Albin F Turbak

Norman A Portnoy

David G Unrau

Rayon fibers having high wet modulus, low wet elongation and low caustic solubility are prepared from an unmodified viscose spinning solution by spinning the viscose solution into a zinc-free coagulation bath containing at least 125 g/l of Na.sub.2 SO.sub.4, at least 125 g/l of (NH.sub.4).sub.2 SO.sub.4 and less than 100 g/l of H.sub.2 SO.sub.4 while the bath is at a temperature above 40.degree. C. The coagulated filament is then stretched in a secondary bath maintained at a temperature over 70.degree. C.

Zinc-free preparation of rayon fibers

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 Na.sub.2 SO.sub.4, at least 175 g/l of (NH.sub.4).sub.2 SO.sub.4 and more than 100 g/l of H.sub.2 SO.sub.4 while the bath is at a temperature above 40.degree. C. The coagulated filament is then stretched in a secondary bath maintained at a temperature over 70.degree. C.

A regenerated cellulosic product is made flame resistant by the addition to the cellulosic solution from which the product is regenerated of from 3 to 7% by weight of colloidal antimony pentoxide and from 5 to 30% by weight of polyvinyl bromide.

Growing community of inventors

Dover, NJ, United States of America

Peter J Hartmann