Patent GB-340929-A (GB)
Title: Improvements in or relating to the manufacture of artificial filaments or threads
IPC: D01F2/30
Filed: 1929-07-02
Abstract: Apparatus for making filaments; cellulose carboxylates and ethers.-Relates to the production of artificial filaments or threads from cellulose acetate or other cellulose derivative by extruding a spinning solution into an evaporative atmosphere and consists in passing the filaments after the formation of a skin-like outer layer thereon into an atmosphere of solvent or other vapour to soften the said outer layer and stretching the thus softened filaments.  Very low deniers e.g. 1,5, 1,0, 0,5 or lower may be obtained.  Following the softening and stretching, the filaments may be passed through a drying atmosphere.  As shown, spinning solution is extruded through a disc, line or other jet 7 into a cell 9 heated by steam elements 10 to cause a fairly rapid evaporation of the solvent from the <PICT:0340929/IV/1> filaments 8 and to produce a skin-like outer layer.  The filaments then pass into a softening chamber 16 through a partition 17. Solvent vapour is supplied to the chamber 16 from a reservoir 19, vaporizer 22 and ring 24 and surplus vapour is withdrawn by an upper ring 25 either by a fan 27 and returned to the reservoir 19 via a condenser 26 or by an exhaust system such as described in Specification 203,092, [Class 2 (ii), Cellulose &c.]. From the chamber 16 the filaments pass to a drying chamber 30 and then around a guide 34 to a cap spinning device 40.  The chamber 30 is fitted with heating coils 31 and is supplied with hot or cold air introduced through a ring 32 and withdrawn through a ring 33.  The solvent-laden air may be led to a solvent recovery apparatus or, as shown, it is conducted through a pipe 15 to the inlet ring 14 of the cell 9, and may be heated in its passage.  The cell 9 may be furnished with a separate supply of hot or cold air.  The air is withdrawn from the cell through a tubular ring 11 near the jet 7 and a control 12 to a header 13 of a recovery system.  Between the chamber 30 and the cap spinning device 40 is arranged a feed roller having smaller and larger diameters 36, 38 connected by a conical portion 37.  In starting up, the filaments are led over the smaller diameter 36 so as to impart little or no stretch. Afterwards the guide 39 is moved to direct the filaments over the portion 37 to the larger diameter 38 to apply stretch.  The apparatus may be disposed horizontally.  The filaments may be subjected to further stretching as described in Specification 323,790, [Class 2 (ii), Cellulose &c.], and may be subjected to lubricating, moistening, sizing or dyeing operations either before or after the feed roller.  To facilitate stretching, plastifiers or high boiling solvents may be added to the spinning solution; thus for cellulose acetate, high boiling solvents such as cyclobutanone, acetyl acetone, diacetone alcohol, dimethyl ethylene glycol, monomethyl ethylene glycol, mono ethyl ethylene glycol; plasticizers such as methyl or ethyl xylene sulphonamides or mixtures thereof may be added to the spinning solutions.  Cellulose derivatives include cellulose formate, acetate, propionate and butyrate; methyl, ethyl or benzyl cellulose; or condensation products of cellulose and glycols or other polyhydric alcohols. Specifications 165,519, 198,023, 277,089, 300,998 and 325,233, [all in Class 2 (ii), Cellulose &c.], also are referred to.