GB1276533A - A process for the production of synthetic acrylic filaments - Google Patents

Abstract

1276533 Spinning acrylonitrile polymer filaments JAPAN EXLAN CO Ltd 10 July 1969 [22 July 1968] 34916/69 Heading B5B Synthetic acrylic filaments are spun from a solution of polyacrylonitrile or an acrylonitrile copolymer containing a major weight proportion of acrylonitrile units, or a mixture thereof, in an inorganic solvent, by a process comprising: (i) spinning the solution into air or an inert gas which does not coagulate the solution, (ii) passing the spun solution into an aqueous coagulating bath, (iii) washing the resulting filaments, (iv) stretching the filaments a first time at between 20‹ and 100‹ C. to more than 1À4 times their original length, (v) drying the filaments until their water content is less than 15 wt. per cent, and (vi) stretching the filaments a second time in the presence of steam. The first stretching is preferably carried out in boiling water, and the second stretching takes place at from 100‹ to 170‹ C. The filaments may be subsequently heat-relaxed. The coagulating liquid is preferably water or an aqueous solution of an inorganic salt, and should be at below 30‹ C. Fig. 2 shows a special coagulating bath arrangement for use in spinning filaments of denier less than 1À0, in which the spinning solution is spun into a funnel 12 and then passes through the main bath 15. Coagulating liquid is fed into the funnel and flows down into the bath and through outlet 18, so that the coagulating liquid and spun solution advance in the same direction and frictional forces are reduced. The acrylonitrile copolymers used contain at least 70 wt. per cent of acrylonitrile units, with units of e.g. methyl acrylate and sodium arylsulphonate. The inorganic solvent is preferably an aqueous solution of sodium thiocyanate.