GB797194A - Improvements in the manufacture of artificial filamentary materials - Google Patents

Abstract

<PICT:0797194/IV (a)/1> In a process for the wet-spinning of artificial filaments in which the latter, after leaving the coagulant, pass over a stationary friction device adapted to remove adherent liquid from them on their way to a washing device, there is applied to the filaments, shortly or immediately before they reach or as they leave the friction device, a liquid which is freely miscible with the coagulant and also with the liquid to be used for washing the filaments, and which is substantially without solvent or swelling action on the filaments. The liquid applied to the filaments is preferably used washing liquid containing about 5-12 per cent of a solvent or swelling agent derived from the coagulant. The filaments may be produced by wet-spinning an acetone solution of cellulose acetate into an aqueous solution of a swelling agent or solvent for the cellulose acetate which boils at a temperature considerably above 100 DEG C., e.g. diethylene glycol diacetate, or by spinning an acetic acid solution of cellulose triacetate into aqueous acetic acid, or by spinning a solution of cellulose triacetate in a mixture of methylene chloride and methanol or ethanol into methanol or ethanol. As shown, a number of untwisted cellulose acetate filament bundles 2, formed by wet spinning an acetone solution of cellulose acetate into aqueous diethylene glycol diacetate, are drawn from their respective spinning devices 21 over the stripping rollers 22 (for example, such as are described in Specification 787,563) by the godets 1 having associated skew idler rollers 1a, and fed to the yarn guide 3, where they unite to form the tow 4. The tow 4 passes in a zig-zag path over and under a set of smooth horizontal parallel, slightly offset, friction bars 5, where part of the residual coagulant is wiped off, to a washing device 6 comprising a pair of positively driven thread-storing thread-advancing skew rollers 7, 8 supported on the member 9 and inclined to the horizontal. Washin4 liquid is sprayed on to the higher end of the lower roller 8 from a nozzle 10 fed by a pipe 11, and falls from the roller into a trough 12, provided with a constant level run-off 13. Used washing liquid is pumped by means of the pump 15 through the pipe 14 from the run-off 13 to a nozzle 16 situated immediately above the tow as it passes over the final bar of the friction device 5. The washing liquid sprayed on to the roller 8 may be either water or a fairly concentrated or substantially anhydrous 1-3 carbon atom monohydric alcohol, especially ethyl alcohol. The bulk of the used washing liquid collecting in the trough 12, which may contain about 8-11 per cent of diethylene glycol diacetate, is passed to a solvent recovery plant. The washed tow carrying with it less than 1 per cent of its weight of diethylene glycol diacetate is deposited by means of a godet 17, of the type described in Specification 787,555, [Group IX], in the rotating sliver can 20. The process reduces the tendency for the individual filaments in each bundle to cohere when the tow leaves the friction device on its way to the washing device. Specification 787,556 also is referred to.