Patent GB-727317-A (GB)
Title: Improvements relating to the production of artificial filaments and fibres
IPC: D01F11/02
Filed: 1951-07-13
Abstract: At least one fatty substance containing or consisting of one or more unsaturated fatty acids having at least three and preferably at least four carbon-to-carbon double bonds in the molecule is incorporated in cellulose or a cellulose derivative prior to or during the dissolution of the cellulose or cellulose derivative, and the solution obtained is spun to form artificial filaments which may subsequently be cut to form staple fibre. Additionally, a portion of the fatty substance may be incorporated subsequently to the dissolution of the cellulose or cellulose derivative and prior to the spinning operation.  Alternatively, a fatty substance containing or consisting of one or more unsaturated fatty acids having at least four carbon-to-carbon double bonds in the molecule may be incorporated in cellulosic artificial filaments or fibres subsequently to their formation. The filaments obtained have high wet and dry tenacities.  The fatty substance becomes stably fixed in the filaments and is resistant to extraction by fat solvents.  The cellulosic material or the formed filaments may be treated with a solution or aqueous emulsion of the fatty substance.  In preparing an aqueous emulsion of the fatty substance, it is preferable to avoid the use of soaps, sulphonated compounds or other water-soluble emulsifying agents.  Natural degras, a product extracted from chamois leather saturated with a fish oil, or an artificial degras produced from a fish oil, may be used to assist the emulsification of the fatty substance.  Degras itself may be used as the fatty substance. A fish or sea animal oil such as whale, seal, sardine, herring or cod-liver oil, or chinawood oil, colza oil or linseed oil, or unsaturated fatty acids obtained from these oils, may be used. Provided that they still contain the required number of double bonds in the molecule, oils which have been submitted to oxidation or boiling treatment may be used.  The proportion of fatty substance incorporated may be small, e.g. 0.1 per cent of the weight of the cellulose, or a larger proportion up to saturation may be used.  In an example, wood-pulp sheets are placed in an immersion press, the bath of which is connected to a tank containing an aqueous emulsion of whale oil, and the emulsion is circulated to and from the press, a mechanical emulsifier being included in the circuit.  The sheets are kept immersed in the emulsion for about one hour and the liquid is then pressed out until the sheets retain about their own weight of emulsion.  The sheets are then dried and subsequently used for the production of rayon by the viscose process.  Prior to such use they may be stored for several days or months, and immediately before use they may be washed in boiling water or immersed in dilute caustic soda solution, wrung out and dried.  In the production of viscose, the fatty substance may be incorporated after the conversion of the cellulose to alkali-cellulose or after the xanthation.  The impregnated cellulose may also be used in the production of artificial filaments by the cuprammonium process.  It may be converted into cellulose acetate or nitrate which is then formed into filaments.  The fatty substance may be incorporated into the cellulose ester during dissolution thereof with acetone or other solvent.  If desired, the fatty substance may be incorporated in cellulose pulp prior to the formation of the sheets, e.g. it may be added to the pulp in the refiner.