GB790326A - Improvements in and relating to acrylonitrile polymer solutions - Google Patents

Abstract

A copolymer of at least 80 per cent of acrylonitrile and up to 20 per cent of a vinyl pyridinium salt in which the anion is thiocyanate, or a blend of a polymer containing at least 80 per cent of acrylonitrile with a polymer of a vinyl pyridiniumsalt in which the anion is thiocyanate so as to give an overall content of not more than 20 per cent of vinyl pyridinium salt, is dissolved in a solvent mixture consisting essentially of water, at least one water-miscible aliphatic liquid containing one alcoholic hydroxyl group and not more than 6 carbon atoms, e.g. methanol, and at least one salt selected from the alkali metal, alkaline earth metal, ammonium and guanidine thiocyanates, lithium bromide and iodide, sodium iodide and zinc chloride, the salt constituting at least 35 per cent by weight of the solvent mixture. The solutions may be spun into threads which can be stretched and dyed. In the example methyl acrylate and 2-vinyl pyridine are copolymerized in bulk in the presence of azodiisobutyronitrile and the resulting copolymer quaternized with dimethyl, sulphate while in solution in a mixture of dimethyl formamide and methanol, sodium thiocyanate is then added in the form of a 50 per cent aqueous solution whereby the thiocyanate salt of the copolymer is precipitated, the resulting copolymer salt is then blended with a copolymer of acrylonitrile and methyl acrylate and dissolved in a solvent mixture as described above. Specifications 692,376, 700,565 and 729,472 are referred to.