GB982794A - Methods and apparatus for wet spinning artificial filaments - Google Patents

Abstract

982,794. Wet spinning artificial filaments. MONSANTO CO. March 30, 1962 [April 11, 1961], No. 12426/62. Heading B5B. In a process for wet spinning artificial filaments wherein the filaments after leaving the spin bath are passed through a wash-stretch zone to an aqueous wash liquid, the wash liquid in the inlet zone of the wash-stretch zone adjacent to the coagulating bath is maintained at a precisely controlled temperature between 88‹ and 98‹ C., and the wash liquid in the remainder of the wash-stretch zone is maintained at a precisely controlled temperature between 80‹ and 90‹ C., the temperature in the inlet zone being higher than in the remainder of the wash-stretch zone. As shown in Figs. 1 and 2, the spinning solution is extruded through a spinneret 1 into a conventional spin bath 2 and the filaments 6 thereby formed are drawn over feed rolls 3 and 4 and directed into an inclined shoot 5. In passing through the shoot 5, the filaments 6 first pass over a shorter inclined shoot 7 which is mounted on spacers 8 in the inlet portion of the shoot 5. Water, or a mixture of water and a solvent for the filament material miscible with water, at a precisely controlled temperature between 88‹ and 98‹ C. is sprayed on to the upper portion of the inclined shoot 7 by a pipe 9. Water, or a water-solvent mixture at a precisely controlled temperature between 80‹ and 90‹ C. and at a lower temperature than the water or water-solvent mixture delivered by the pipe 9 is sprayed on to the upper portion of the inclined shoot 5 from a pipe 10. This wash liquid runs down the shoot 5, passes under the shoot 7 and is discharged from the lower end of the shoot 5. The wash liquid which passes down the shoot 5 countercurrent to the tow of filaments is for the purpose of removing spinning solution solvent from the fibres. The filaments are drawn beneath the guide rod 16 along the bottom of the upper portion of the shoot 5 and over draw rolls 11 and 12 from which they then pass to a relaxer 13. The tow is then drawn out of the relaxer and dried by the heated rolls 14 and 15. The spinning solution may be a solution of a copolymer of 94% acrylonitrile and 6% vinyl acetate in dimethylacetamide and the spin bath may be an aqueous solution of dimethylacetamide having a concentration of 55%. The stretch ratio between the feed rolls 3, 4 and the draw rolls 11, 12 may be, for example, 5À2. The relaxer 13 may be a metal box provided with a perforated cover and a number of perforated pipes for introducing saturated steam into the box. The peripheral speed of the rolls 14, 15 is less than that of the rolls 11, 12 to allow relaxation or controlled shrinkage of the tow in the relaxer. The relaxation may, for example, be 24%. Specification 775,892 is referred to.