Modacryl filaments and fibers and process for their manufacture

A process for the manufacture of modacryl filaments and fibers from an acetone-insoluble copolymer of acrylonitrile, 20 to 45 weight percent of vinylidene chloride and up to 11.5 weight percent of at least one other compound copolymerizable therewith, said copolymer having a K value of about 95 to 120, which comprises dissolving said copolymer in a solvent to form a spinning solution, forcing the spinning solution so obtained through nozzles into the first of at least three series-connected coagulation baths containing mixtures of the polymer solvent and at least one non-solvent for the polymer, the polymer solvent concentration in the first coagulation bath being from 30% to 70% by weight of said bath and being gradually reduced in successive coagulation baths, the polymer solvent concentration in the first coagulation bath being about 1.2 to 2.0 times that of the second coagulation bath, the polymer solvent concentration in each coagulation bath subsequent to the second bath being reduced by a factor of 1.2 to 3 in each such subsequent bath, the temperatures of the first and second coagulation baths being from 0.degree. to 70.degree. C., those of the third and the following baths being from 20.degree. to 90.degree. C., drawing the spinning tows obtained to a multiple of their length in at least one of these baths and, after removal of the solvent as completely as possible, subjecting said drawn tows to at least one further drawing.