Manufacture of films of nu-substituted acrylamide copolymers

Claim 1

A PROCESS FOR MANUFACTURE OF A FILM OR FILAMENT OF A LINEAR ADDITION COPOLYMER WHICH IS INSOLUBLE IN WATER AND SOLUBLE IN AN AQUEOUS SOLUTION CONTAINING 25% OF CACL2 AT 25*C. TO THE EXTENT OF AT LEAST 5 PERCENT BY WEIGHT, COMPRISING (A) STIRRING A MIXTURE OF (I) AN N-SUBSTITUTED AMIDE HAVING THE FORMULA CH2=CR-CO-NR''-CH2OR" IN WHICH R IS HYDROGEN OR ALKYL, R'' IS HYDROGEN, METHYL OR HYDROXYETHYL AND R" IS HYDROGEN OR METHYL, (II) AT LEAST ONE OTHER MONO-ETHYLENICALLY UNSATURATED COMPOUND CAPABLE OF BEING COPOLYMERIZED WITH THE N-SUBSTITUTED AMIDE, (III) A WATER-SOLUBLE FREE RADICAL INITIATOR, AND (IV) AN AQUEOUS SALT SOLUTION CONTAINING AT LEAST 10% OF A HALIDE OF A METAL CHOSEN FROM GROUPS I AND II OF THE PERIODIC TABLE, (B) THEREBY TO FORM A WATER INSOLUBLE COPOLYMER CONTAINING AT LEAST 35 MOL PERCENT OF UNITS OF THE NSUBSTITUTED AMIDE, IN SOLUTION, IN THE SALT SOLUTION, (C) FORMING A THIN LAYER OR STREAM OF THE SOLUTION, AND (D) COAGULATING THE THIN LAYER OR STREAM.