GB917290A - Process for preparing shaped articles from acrylonitrile polymers - Google Patents

Abstract

Shaped articles, particularly filaments and films, of copolymers of acrylonitrile are produced by extruding a solution in dimethylformamide, dimethylacetamide, dimethylsulphoxide, tetramethylene sulphone or ethylene carbonate, of a copolymer derived from at least 70% by weight of acrylonitrile and at least 1,5% by weight of an ethylenically unsaturated monomer containing a sulphonate group, into an aqueous coagulating bath containing 0 to 65% by weight of the solvent for the copolymer, the bath being at a temperature of 10 DEG to 70 DEG C., preferably 25 DEG to 40 DEG C. The copolymers may with advantage contain up to 28,5% of another ethylenically unsaturated monomer and a list of these is given. The coagulating bath preferably contains not more than 45% by weight of the solvent. Examples are given in which the monomer copolymerized with acrylonitrile is sodium styrene sulphonate, sodium ethylene sulphonate, sodium propene sulphonate, sodium isobutene sulphonate, or alkyloxypropanol sulphonate, and an example is given also in which there is used a terpolymer of acrylonitrile, vinylidene chloride and sodium styrene sulphonate. The sulphonate salt groups are preferably alkali metal or ammonium salts. A long list of suitable sulphonate monomers is given. The content of sulphonate in the copolymer is preferably between 1,5 and 5% and may be up to 10%. The filament or film formed may be passed through a second bath, e.g. water at about 80 DEG to 100 DEG C., to extract residual solvent. It may then be stretched at a draw ratio of 2 to 10 in a heated aqueous medium such as steam at 7 p.s.i.g. pressure. The process produces lustrous, void-free filaments, films &c. without the necessity of using special aftertreatments, and low-solvent concentration coagulation baths at room temperatures may be used. The products have improved dyeability, particularly when basic dyes are used. U.S.A. Specifications 2,451,420, 2,467,553, 2,530,962, 2,622,003, 2,677,590, 2,677,591 and 2,681,265 are referred to.