METHOD OF MANUFACTURING ACRYLIC FIBERS

摘要

1391690 Wet spinning polyacrylonitrile CESKOSLOVENSKA AKADEMIE VED 20 June 1972 [22 July 1971] 28857/72 Heading B5B Fibres and filaments are prepared by spinning polymers and copolymers of acrylonitrile in nitric acid solution into a coagulating bath containing one or more nitrates and a proportion of the respective neutralizing agent or agents more than sufficient to neutralize the nitric acid introduced by the spinning solution. The concentrations of the nitrate(s) and the neutralizing agent(s) and the level of the liquid in the bath and its temperature are kept constant. In the embodiment shown the spinning solution is spun through spinners 2 into coagulating bath 5 and the resulting fibres stretched in hot washing bath 6 and dried and heat stabilized in the two-roller system 9, 10. Vapours given off by the bath 6 and 8 condense on the roofs 11 and 111 and the condensate led on to the fibre bundle to assist in washing. The washing liquid is led in countercurrent through the system and is used to top up the coagulating bath. In the coagulating bath, the neutralizing agent is urea, added through apparatus 17 and pipe 18. Urea nitrate solution in excess is led off through valve 12 to cooler 13 and drum filter 14. Urea nitrate is recovered by this means and led off through the transporter 20.