Improvements in the spinning of polyacrylonitrile

摘要

In the manufacture of artificial filaments by spinning a solution of polyacrylonitrile, the solvent is regenerated by precipitating barium sulphate therein. The treatment may be effected (1) by addition of a soluble barium compound, preferably barium thiocyanate to the spent solvent; (2) by addition of a barium compound, such as barium carbonate or barium hydroxide, whose solubility in polyacrylonitrile solvent, while low, is greater than that of barium sulphate; or (3) by passing the solvent through a bed comprising such a low-solubility barium compound. The polyacrylonitrile solvent may be a solution of sodium thiocyanate and treatment may be carried out before or after concentration of this solution. The treatment is preferably effected at a raised temperature, e.g. 35 DEG C. or above.