GB371360A - Improvements in the manufacture of filaments, threads and the like - Google Patents

Abstract

<PICT:0371360/IV/1> <PICT:0371360/IV/2> <PICT:0371360/IV/3> In a wet or semi-wet spinning process, particularly for cellulose acetate or other esters or ethers, a spinning solution is extruded through a coagulating medium to form a plurality of filaments or the like in such a way that these carry away insufficient liquid to cause them to cling together. Thus the filaments may be extruded through a liquid film of limited thickness. By this means spinning speeds of 150-400 or more metres per minute can be attained. The coagulating liquid should be less volatile than the solvent of the spinning solution. Preferably also it should not have a very great precipitating action unless a mat effect is desired. It is advantageous to use a liquid of high plasticizing power as described in Specifications 340,324 and 340,325, for instance a 25-65 per cent aqueous or alcoholic solution of ethyl lactate, diacetone alcohol, diethyl tartrate, mono- and di-acetin, dioxane, lactic acid, and the like, or plasticizing agents, e.g. tricresyl phosphate, or xylene monomethyl sulphonamides, with or without solvents or non-solvents for the cellulose derivatives such as an ester or ether. In one form of apparatus, a hemispherical spinning nozzle 10, Fig. 1, with a ring of perforations 13, is kept covered with a film of coagulating liquid by a surrounding trough 12, the inner edge of which is notched. In a modification the nozzle is of triangular vertical section and has a line of holes along its downwardly-directed apex. Fig. 7 shows a nozzle of the type described in Specification 355,720. It has an annular trough portion 24 with a ring of holes 25 supplied with spinning solution by ducts 26. An interior tube 27 supplies coagulant to a series of holes 28 in the surface inside the ring of spinning holes. Coagulating solution may also be supplied simultaneously from the outside and the inside of a ring of spinning orifices. For upward spinning, the nozzle 19, Fig. 5, may be concave as shown, flat, or convex, the liquid being supplied from the outside of a ring of orifices when the face is concave or from the inside when it is convex; or the spinning holes may be in a line. The nozzle 19 may be swivelled so that spinning is initially effected downwards. After evaporation of the solvents and coagulating liquids, preferably in an ordinary metier, the filaments may be wound with or without twisting. Specification 198,023, [Class 2 (ii), Cellulose &c.], also is referred to.