GB400662A - Improvements in the production of artificial filaments - Google Patents

Abstract

In apparatus for the production of artificial filaments by the evaporative method, the filtering-device which precedes the spinning jet is <PICT:0400662/IV/1> provided with an internal passage whereby evaporative medium may be passed through the body of the spinning solution contained in the filter. The evaporative medium heats the spinning solution prior to extrusion. Some of the evaporative medium which passes through the cell may be led outside the filtering-device. As shown in the drawing, spinning solution passes down a pipe 4 to a filtering-device 3 wherein it passes through the perforated wall 10 and filter material 9 to the annular space 8, and is extruded from the annular jet 11. Heated air passes upwardly through the cell and is withdrawn through the pipe 13, some of the air passing through a passage 5 constructed within the filtering-device, while the remainder travels outside the casing 7 and through a gap 15 in a plate 14. The proportions of air passing externally and internally of the filtering-device are determined by the ratio of the area of the gap 15 to the total area of the passages 6. Shields 16 direct the rising currents of air heated by pipes 17, to the outside of the filter body. The air passing through the conduit 5 although cooler than that passing externally, still has a considerable heating effect on the spinning solution prior to filtration. The apparatus may be used for the production of filaments of cellulose acetate or other cellulose ester or of ethyl cellulose or other cellulose ether. Specification 300,998, [Class 2 (ii), Cellulose &c.], is referred to. The Provisional Specification describes also the use of a jacket around the filtering-device, or solution-supply pipe, hot air being directed towards and through the jacket in order to heat the solution. The air for heating the spinning solution may be introduced from the external atmosphere independently of that forming the main current within the cell. Cold air may be introduced into the cell in the neighbourhood of the jet.