GB675621A - Improvements in or relating to the production of artificial filaments - Google Patents

Abstract

Apparatus for spinning fine filaments from thermoplastic material comprises a positive displacement pump in combination with a screw-type extruder mounted in close proximity therewith to discharge heated material directly into the pump, a plurality of separated axially spaced passages extending circumferentially within the extruder wall, means for supplying heating medium independently to each of the passages, and means for supplying a cooling <PICT:0675621/IV (a)/1> medium to each of the passages, and a spinneret mounted adjacent to and connected with the pump to receive material discharged from the pump. The thermoplastic material may be a polyamide, polycarbonamide; copolymer of vinyl chloride with vinyl acetate or vinylidene chloride; polyacrylonitrile; copolymer of acrylonitrile with vinyl chloride, vinylidene chloride, vinyl pyridine, or isobutylene; cellulose acetate or aceto butyrate, or other cellulose ester. As shown in Fig. 1, the screw-extrusion device 5 has a helically threaded rotatable member 8 of which the spindle 11 is tapered with respect to the interior surface 9 of the barrel or casing so that there is progressively less clearance between the wall 9 and the spindle towards the discharge end. The depth of the thread 10 decreases as the diameter of the spindle increases. The resinous material is thus brought into more frequent and intimate contact with the heated surfaces of member 8 and casing 9 as it passes through device 9 and becomes denser and more plastic or fluid. Air or other gas carried within the mass of resinous particles is forced rearwardly toward the lower pressure area at the feed end of the extruder where it escapes. Heating of the casing is effected by circulating a heated fluid through passages 12, 13, 14. Fluid cooling medium may be supplied through line 16. Liquid or gaseous heating medium is supplied through line 20. Valves are provided to control the supply of heating or cooling medium so that the temperature at any portion of the extruder walls may be adjusted as desired. The spindle 11 is hollow so that heating fluid may be circulated therethrough. If desired the spindle 11 may be heated electrically. From the screw-extruder device 5, the melted resinous material passes directly into the extrusion head 6 and the intake port 45 of the gear-wheel pump 7. The extrusion head and the pump are electrically heated. The delivery port of the pump is contiguous with passage 55 of the extruder head. Passage 55 terminates in nozzle 56 which is threaded to receive a housing 58 for screens or filters. A spinneret 61 is secured to housing 58. A shroud 64 surrounds the spinneret and the freshly formed filaments. Inert gas may be introduced through tube 65.