Methods for spinning artificial filaments

摘要

Artificial filaments are produced by continuously extruding a filament-forming material through the holes of a spinneret into a stream of coagulating liquid surrounding and flowing past the spinneret in the general direction of extrusion, directing the filament-forming material in a straight free path through the air as it proceeds from the spinneret and is coagulated to filaments by the action of the coagulating liquid stream, the filaments not coming into contact with any object until they reach a thread-advancing device, forming the coagulating liquid stream into a jet having substantially the same velocity as the filaments and flowing in a free flight through the air along the path of the filaments, the amount of the liquid in the jet being limited to ensure that all the liquid adheres to and travels at substantially the same velocity as the filaments throughout the free flight, and then continuously removing excess liquid from the filaments at the end of the free flight. As shown, viscose from a supply pipe 4 (Fig. 1) is extruded through a spinneret 3 into a stream of acid coagulating liquid supplied to the chamber 9 by means of the metering pump 15 and the conduit 14, which directs a portion of the stream across the face 3a of the spinneret in order to prevent the accumulation of bubbles therein. The liquid flows inwardly over the spinneret face, contacts the filaments leaving the spinneret orifices and joins with the filaments in the main current of flow axially of the spinneret and of the tapered bore 11a in the guiding member 11. The filaments and liquid emerge through the circular opening 11b, which is preferably not more than 2 to 3 cm. distant from the spinneret face and whose diameter may be preselected to limit the diameter of the stream or jet of liquid travelling with the filaments from the spinneret assembly. The opening may be 0.5 to 3.0 mm. and preferably not more than 2 mm. in diameter. The filaments may pass directly from the opening 11b to a thread-advancing device such as the godet 16 (Fig. 2) having an inclined axis and about which the filaments are lapped by means of a roller guide 17. The godet 16 is driven at a peripheral speed equal to the linear speed of the filaments, e.g. 75-200 metres per minute. When the filaments reach the peripheral surface of the godet 16 the excess coagulating liquid leaves the filaments and travels down to the rim 18 of the godet which guides it into the gutter 19. The bundle of filaments from which the liquid has now been removed may pass from the godet 16 to a second thread-advancing device which may comprise a godet 20 and associated lap-displacing guide roller 21. In a modification, the filaments leaving the opening 11b of the spinneret assembly may pass directly to a thread-advancing reel 22 (Figs. 3 and 4) rotating at sufficiently high speed to throw the liquid from the helix of thread carried thereon by centrifugal force. The liquid thus thrown off is received in a guard member 23, provided round the zone of the reel to which the filaments are first led, and discharged through a drain 24 (Fig. 3). Additional coagulating liquid may be supplied by means of pipe 30 (Fig. 4) to the inside deflecting surface 26 of a jacket 25 entirely surrounding the reel. Annular grooves 27 and 28 disposed at each side of the surface 26 serve to lead the surplus additional coagulating liquid to the drain pipes 29 (Fig. 3). Data are furnished indicating the conditions of aperture 11b diameter, spinning speed and rate of coagulating liquid feed which provide the travel of a coagulating liquid of specified composition with viscose filaments at the same speed (without back flow, dripping or overtaking, irrespective of the spinning direction) for yarns of specified total denier and number of filaments. The data given also include the diameter of the liquid jet and the weight of coagulating liquid per unit length of yarn between the spinneret assembly and the take-up device. The process is said to be particularly adapted for high speed spinning and to produce filaments of very uniform characteristics.