GB1354306A - Producing polyvinyl alcohol fibres - Google Patents

Abstract

1354306 Polyvinyl alcohol fibres UNITIKA Ltd 19 April 1971 [11 Dec 1970 26 Dec 1970] 25939/71 Heading B5B [Also in Division C3] A process for producing P.V.A. synthetic fibres comprises spinning a solution comprising: (a) polyvinyl alcohol and 0À4-1À0 wt. per cent of borax, (b) polyvinyl alcohol and 0À5-1À0 wt. per cent of boric acid, or (c) partially saponified polyvinyl alcohol containing 1-15 mole per cent of acetate groups and 0À5-3À0 wt. per cent of borax or boric acid, into an alkaline coagulating bath capable of coagulating P.V.A., and subjecting the spun filaments to drawing, acid treatment, wet heat treatment, water washing and drying, thereby forming filaments containing 0À2-0À4 wt. per cent based on P.V.A., of boric acid, and thereafter hot-drawing said filaments suitably in hot air at up to 3238‹ C., followed by heat-setting of constant length. The spinning solution of type (a) may be prepared by adding an aqueous borax solution in the form of fine droplets to an aqueous P.V.A. solution (which may already contain less than 0À3 wt. per cent based on P.V.A., of borax) with stirring at not less than 85‹ C. The acid treatment is preferably carried out using a mixture of Glauber's salt and sulphuric acid in aqueous solution. The coagulating bath may contain for example Glauber's salt or potassium sulphate, made alkaline with NaOH or KOH.