GB1057700A - Improvements in the production of filaments, yarns and similar products from cellulose triacetate - Google Patents

Abstract

1,057,700. Cellulose triacetate filaments. SOCIETE RHODIACETA. Dec. 22, 1964 [Jan. 17, 1964], No. 52133/64. Heading B5B. Filamentary cellulose triacetate materials are produced by extruding a solution of cellulose triacetate in methylene chloride or a mixture of 80% or more by weight of methylene chloride and 20% or less by weight of an aliphatic alcohol having from 1 to 4 carbon atoms, for example methanol or ethanol, into an evaporative medium circulating in a closed circuit, removing the materials from the circuit when they have become coagulated, cooling the evaporative medium, at a point in the circuit beyond that at which the coagulated materials are removed, to a temperature at which the vapour pressure of the solvent is between 10 and 40% of atmospheric, reheating the medium, and returning the medium to the spinning cell in the neighbourhood of the point of extrusion. The spinning cell may be heated to between 60‹ and 150‹ C.; the evaporative medium, which may be air, is cooled preferably to between - 6‹ and 15‹ C., and reheated preferably to at least 50‹ C., for example to between 60‹ and 110‹ C. Apparatus suitable for the process is illustrated in the figure and comprises a tubular structure 1 in which spinning cell la is heated by jacket 2, cooling zone 1b is provided with jackets 3 and 4 for the passage of a cooling liquid to condense solvent vapour, and reheating zone 1c is provided with heating jacket 5. The spinning solution is extruded through spinneret 6 to form yarn 7 which is drawn from the cell by roller 9 after passing over guide pulley 8. Condensed solvent is drawn off through drain 10. The evaporative medium circulates by means of the drag exerted by the filaments and the difference in density between the vapour-laden medium in zones 1a and 1b and the vapour-free medium in zone 1c Examples describe the production of yarn, at various spinning speeds, from solutions of cellulose triacetate in a 90-10 methylene chloride-methanol solvent mixture, various values being chosen for the temperatures of the cell between the spinneret and where the yarn leaves the cell, of the cooled evaporative medium, and of the reheated medium.