GB748954A - Improvements in or relating to methods of spinning fine fibres and like structures - Google Patents

Abstract

In the wet spinning of aqueous salt solutions of polymers containing 85 per cent or more of acrylonitrile, from 2 to 30 per cent by weight of an organic peptizing agent (i.e. an organic compound capable of dissolving or swelling the polymers) is introduced into the spun product either by dissolving from 2 to 30 per cent of the agent, based on the weight of polymer, in the spinning solution, or by passing the freshly spun product through an aqueous bath containing from 5 to 30 per cent of the agent until the spun product has absorbed from 2 to 30 per cent of the agent. Peptizing agents specified are dimethylformamide, 2 - (N - hydroxyethyl N - methylformamide), dimethyl cyanamide, acetonitrile, succinonitrile, nitromethane, nitroethane, 2-nitropropane, unsymmetrical diethylurea, dichloroformal, di-(2-chloroethyl) formal, dimethyl sulphone, tetramethylene cyclic sulphone, 1,4-dioxane, butyrolactone, gamma - phenylvalerolactone, gamma - caprolactone, phenylpyrollidone, oxindole, acetoxindole, para - toluenesulphonamide, phenol, thymol, 4,41 - dihydroxy diphenylmethane, and tertiary butyl phenol. The peptizing agent may be incorporated in the polymer by polymerizing acrylonitrile in an aqueous salt solution containing the agent which serves to lower the molecular weight of the polymer produced, and also, in the case of phenols, accelerate the polymerization. Alternatively the polymer particles may be swelled by contact with the agent and then dissolved in the aqueous salt solution, or the agent may be added directly to the polymer solution. When the peptizing agent is applied to the polymer after spinning the agent may be present in the initial coagulating bath or in any subsequent washing bath. The aqueous salt solutions used may comprise both a solvent salt such as zinc chloride and a non-solvent salt such as calcium chloride.