GB721674A - Improvements in the production of filamentary materials - Google Patents

Abstract

Artificial filamentary materials are produced by urging a fusible filament-forming powdered material against a heated plate having spinning orifices therein, through which orifices the material, fused by heat from the plate, is extruded and withdrawn as filaments, the powdered material supplied to the plate being maintained under a sub-atmospheric pressure. In the apparatus shown in Figs. 1 and 2, a plate 35 is heated by the passage of an electric current from electrodes 42 and is clamped against a vessel 50 so that orifices within the plate communicate with an opening in the vessel. Powdered filament-forming material is supplied from a hopper 58 to a lock chamber 55 between valves 56 and 57, and from the lock <PICT:0721674/IV (a)/1> <PICT:0721674/IV (a)/2> <PICT:0721674/IV (a)/3> <PICT:0721674/IV (a)/4> chamber the powder is admitted to the vessel 50. The need for replenishment of the powder may be determined through an inspection window 59. A vacuum pump connected to the vessel 50 through a tapping 53 maintains a reduced pressure within the vessel, the pressure being recorded on a gauge connected to a tapping 54. The powder is urged against the plate 35 by a tamp 29 vertically reciprocated by a crank 17 and connecting rod 20, the crank being rotated by an electric motor 14. A downward pressure is exerted on the tamp by a spring 28 within an aligning tube 23. The tamp is connected to a tamp rod 21 by a pin and slot connection 25, 26. The vessel 50 is supported upon a bracket 43 and the height of the vessel relative to the tamp may be adjusted by a screw 33. The extruded filaments 78, after being led over a roller 79, have applied thereto a lubricant or anti-static finish at 82 and are wound upon a bobbin 81 in a twisting device 80. The vacuum tapping 53 and the gauge tapping 54 are fitted with gauze filters to prevent the passage of powdered material. In a modification, not shown, several tamps extend into an elongated chamber, the reciprocating mechanism being outside the chamber and the tamps carrying feet of a length equal to the spacing between the units in the series, and in a further modification, Fig. 8, a plurality of tamps 113 operate within a trough 153, the whole mechanism being contained within an evacuated vessel 145 against which is clamped a heated perforated plate 99. In this modification the foot of each tamp works in a slot 155 in a slab 101, Fig. 9. The plates may be heated electrically with arrangements for automatically controlling and recording the temperature (see Group XXXV). Modified arrangements for connecting the tamp 29 to the tamp holder 25 are described, and in one, Fig. 5, a connection 137 may be made to a pressure gauge or to a supply of nitrogen so as to maintain an inert atmosphere about the powder, the nitrogen being continuously withdrawn to maintain the reduced pressure. The filaments may fall away from the spinning orifices under the influence of their own weight or they may be withdrawn at a speed to cause attenuation. The filament-forming powder may be a cellulose ester or ether, polythene, polystyrene, polyhexamethyleneheptamethylene urea (a condensate of hexamethylene diisocyanate and heptamethylene diamine), 4 : 4-polyurethane (from tetramethylene diamine and the dichloroformic ester of 1 : 4-butanediol), polyhexamethylene adipamide, polyaminocaproic acid, polyethylene terephthalate or the polyaminotriazole formed from sebacic dihydrazide and hydrazine described in Specification 612,609 or it may be a mixture of filament-forming materials and may include dyes or pigments. The material may be extruded as narrow bands, ribbons or fibres, and the fibres may be collected in tows for subsequent processing such as stapling. Specifications 719,853 and 719,860 also are referred to.