GB399822A - Improvements in processes and apparatus for the manufacture of artificial filaments and like materials - Google Patents

Abstract

<PICT:0399822/IV/1> <PICT:0399822/IV/2> <PICT:0399822/IV/3> <PICT:0399822/IV/4> <PICT:0399822/IV/5> In the production of artificial filaments by the dry-spinning< > method, the supply pipe or other means of supply for the spinning solution passes through a zone of evaporative atmosphere which is hotter than that into which the filaments are extruded, and the cool current of evaporative atmosphere into which the filaments are initially extruded is substantially prevented from entering the neighbourhood of the supply means. Preferably the zone around the supply means is insulated from that around the spinning jet. Heating devices may be situated in the zone around the supply means, or the usual cell heating devices may be disposed so as to effect differential heating of the air, and the hot air current set up by convection is caused to pass to the region of the supply means with the aid of baffles or similar devices. A tubular shield may be placed around the jet to direct cool air to the jet and hotter air to the supply means, and to keep the two currents apart. The baffles, plates, or shields are preferably made of insulating material such as asbestos. If desired, cooler air may be injected in the region of the jet and prevented from contacting with the filter-candle or other solution supply means, and it may be derived from the external atmosphere. If desired it may be taken from the lower part of the cell and made to pass up a conduit by convection or other means. The draw-off devices are situated so as to prevent the cooler air around the jet from passing to the region of the supply means. Insulation between jet and supply means may be effected by two parallel plates perforated for passage of hot air to the supply means but having between them a substantially dead zone, and it is possible with this arrangement to place a draw-off device between the plates. In constructions where the filter-candle is outside the spinning cell, the supply pipe within the cell is made of large diameter, or in the form of a coil or other pipe of long length, in order that the spinning solution may be heated by the hot air of the cell. As shown in Fig. 1, a spinning cell 10 is arranged for downward spinning with counter-current of evaporative medium such as air. The air heated by pipes 21 rises up the cell close to the walls and passes an insulating baffle-plate 23 into the zone around the filter-candle 12. By means of the perforated plate 27, the hot air is brought into close contact with the filter-candle as it passes towards the draw-off 29. The cooler air in the middle of the cell passes upwardly to the jet zone and a draw-off 25. As shown in Fig. 2, the jet is surrounded by an insulating curtain 32, inside which cool air passes to the jet and then to a draw-off 25. A small quantity of cool air may pass through the perforation of the plate 34. Hot air flows outside the curtain 32, past additional heating pipes 33, close to the filter-candle 12, and through the plate 27 to draw-off 29. As shown in Fig. 3, the hot air is deflected into contact with the filter-candle 12 by means of cowls 36. Cool air passes up the cone 37 and then passes to the upper part of the cell outside the cowls 36. The cowls and the cone are preferably insulated. As shown in Fig. 4, cool air enters the cone 40 around the jet and is removed by the draw-off 42. Hot air is kept out of contact with the jet by means of the cone 40, and it passes through a perforated tube 41 surrounding the filter-candle on its way to the draw-off 43. As shown in Fig. 5, cool air is introduced in the region of the jet through a pipe 47 and withdrawn by the device 25. Hot air passes up the sides of the cell through the plate 52 into the vicinity of the filter-candle, and then through the plate 27 to the draw-off 29. The outlets and inlets for the evaporative medium are preferably provided with valves or calibrated disc orifices. Specifications 343,936 and 364,654 are referred to.