GB399795A - Improvements in the production of artificial silk and like products - Google Patents

Abstract

<PICT:0399795/IV/1> <PICT:0399795/IV/2> Solutions of cellulose acetate or other cellulose derivative are extruded into a current of evaporative medium, and, in the vicinity of the spinning orifices, there is introduced a current of additional evaporative medium from the external atmosphere, this additional current being induced by heat. The additional current may be superimposed upon a current of evaporative medium flowing with or against the filaments, and it may be introduced symmetrically or from one side, inside or outside of the bundle of filaments, and at different levels. The temperature of the additional medium may be less than that in the main body of the cell and the additional medium may be prevented from entering the zone surrounding the spinning solution supply pipe or filter. The air current induced by heat and drawn from the external atmosphere may be mixed with solvent vapours or with non-solvent vapours, by passage through a vessel containing liquid or loosely packed with porous material saturated with liquid, or steam may be injected into the vessel. The means for heating the additional evaporative medium may be the same as or additional to that for heating the main body of the cell. As shown in Fig. 2, a spinning jet 6 is placed in a cell 5. Evaporative medium passes in countercurrent to the direction of the filaments through a valve 11, and additional medium enters through the valve 14 into a chamber 15 from which it issues in the vicinity of the spinning jet. The rising current of hot air is induced by steam pipes 17. Evaporative medium is withdrawn from the cell through pipes having valves 18, 19. A baffle plate 21 is provided for maintaining the atmosphere in the vicinity of the dope supply pipe 27 at a higher temperature than that in the region of the jet. As shown in Fig. 3, the main current of evaporative medium enters the cell 5 through the pipe and valve 11, while additional medium is introduced through two vertical conduits 24, 25 positioned in proximity to steam pipes 9, heat from which produces a rising current of air in the conduits. Evaporative medium leaves the cell through a pipe and valve 19. Specifications 325,233, [Class 2 (ii), Cellulose &c.], 341,075, 396,792, and 399,822 are referred to.