Patent GB-654900-A (GB)
Title: Improvements relating to the manufacture of cellulose ester fibres
Inventor: SOWTER PERCY FREDERICK COMBE
IPC: D01F2/28
Filed: 1948-09-23
Abstract: <PICT:0654900/IV (a)/1> Filaments and yarns having a basis of a cellulose ester of a fatty acid containing 2-4 carbon atoms in the molecule, and suitable for conversion into staple fibre are obtained by extruding a solution of the cellulose ester in acetone into an aqueous solution of diethylene glycol diacetate of concentration below 38 per cent by weight as coagulating bath, stretching the filaments during their passage through the coagulating bath and then subjecting the filaments to the action of a regulating liquid comprising either water alone or an aqueous solution of diethylene glycol diacetate of concentration below 38 per cent by weight, while allowing them to shrink freely.  The regulating liquid may be a diethylene glycol diacetate solution of the same concentration as that used in the coagulating bath but at a lower temperature.  The temperature of the coagulating bath may be 30-35 DEG  C. and that of the regulating bath may be 15-27 DEG  C.  The path of the yarn through the coagulating bath may be 50-90 centimetres and the path of the yarn in contact with the regulating bath may be 3-10 metres.  The yarn is preferably washed thoroughly with water after the treatment. Diethylene glycol diacetate may be recovered from the wash water by treatment with benzene.  If desired, the wash water may be replaced by a solvent for the diethylene glycol diacetate, e.g. petroleum ether. The cellulose acetate yarns obtained have good tenacity and extensibility and may have a considerable degree of crimp.  They are suitable for conversion to staple fibre.  The process is applicable to the production of yarns of cellulose propionate or butyrate as well as cellulose acetate.  The filaments in the form of untwisted yarn may be subjected to the action of the regulating bath while passing over thread-storage thread-advancing rollers or a single thread-storage thread advancing reel so shaped or adjusted as to allow the yarn to shrink freely.  Allowance for a shrinkage of 2-4 per cent is generally sufficient.  A pair of slightly tapered rollers, one of which is arranged skew fashion to the other, may be provided.  The regulating liquid may be applied by causing one of the rollers to dip into a body of the liquid, or it may be applied by spraying, or through hollow perforated rollers.  As shown, filaments emerge from jet 1 which is placed in trough 3 containing the coagulating liquid.  The trough has inlet 4 and overflow 5 for the liquid.  The filaments are led as a single untwisted yarn to godet 7, and then they are passed to rollers 11, 12, between which they pass several times while being advanced axially.  The rollers are tapered. The axis of one of the rollers may be adjusted with respect to that of the other. The yarn is then passed to godet 13.  Godet 7 is driven so as to subject the filaments to stretching while they are passing through the coagulating bath.  Godet 13 is driven so as to allow the yarn to shrink freely while passing between the godets and round the advancing rollers.  When using water as the regulating liquid, rollers 11, 12 may be cylindrical.