Method for producing regenerated cellulose fibers having excellent flameproofness

Abstract

Regenerated cellulose fibers having very good flameproofness are obtained by adding a polyphosphonate having the following formula: ##STR1## wherein R.sub.1 is ethylene or propylene; R.sub.2 and R.sub.3 are methyl or ethyl which may be the same or different; R.sub.4 is an alkyl group having 1 to 4 carbon atoms, or an aralkyl group in which the alkyl substituent has 1 to 4 carbon atoms and the hydrogen atoms in said alkyl and aralkyl groups may be substituted with chlorine or bromine; R.sub.5 is an aromatic group having 1 to 20 carbon atoms or an unsaturated or saturated aliphatic or alicyclic group having 1 to 20 carbon atoms or a combination thereof and R.sub.5 may contain carbonyl group, sulfonyl group or nitrogen; X is halogen, and n is an integer from 1 to 1000, to a viscose and then spinning the viscose by conventionally accepted procedures. The retention of the polyphosphonate flameproofing agent in the fibers can be markedly increased by this procedure.

Dependencies are inferred from the claim text.