Patent GB-359975-A (GB)
Title: Improvements in the production of artificial products from solutions of cellulose orcellulose derivatives
IPC: D01F2/06
Filed: 1930-07-30
Abstract: Artificial filaments, yarns, threads, ribbons, bristles, films, &c., are produced by spinning solutions of cellulose or of cellulose derivatives into a liquid medium and removing the same from the medium while the filaments &c. are still liquid or substantially liquid, i.e. the substance is still capable of flowing easily, and thereafter setting the filaments &c. Products of very fine denier or cross section and of considerable strength are thereby obtained. The invention applies particularly to solutions adapted to yield products of regenerated cellulose, and the solution is preferably spun into a liquid which is non-solvent for the cellulose or cellulose derivative and is also a non-solvent for the solvent of the spinning solution. Hydrocarbons or halogenated hydrocarbons are convenient for viscose. The liquid may be of such specific gravity as to enable the spinning solution to rise or fall therein; thus with light hydrocarbons, e.g. benzene, the spinning solution may be directed downwardly, or with a heavy liquid, upward spinning may be used. The specific gravity of the spinning solution may also be adjusted. For starting up, the solution is preferably spun into a coagulating bath and the bath characteristic of the invention then introduced. Some elimination of the solvent of the spinning solution may be permitted provided the products are still liquid or substantially liquid on emergence from the bath; thus viscose may be spun into a bath having a slight solvent power for water, or the hydrocarbons &c. may be mixed with alcohol, acetic, formic or lactic acids &c.  The length of the bath depends upon the amount of "draw-down"; generally a length up to a few inches suffices.  The products are coagulated by any convenient method and regeneration of the cellulose may be simultaneous with or follow coagulation; and is preferably effected by strong mineral acids or esters thereof, sulphonic acids, or other organo-mineral acids as in Specification 335,894, [Class 2 (ii), Cellulose &c.]; alternatively, the products may be treated with the strong mineral acids &c. subsequent to regeneration and preferably continuously with production.  For viscose, the coagulating bath may comprise dilute mineral acids, e.g. sulphuric acid of 5-15-20 per cent strength, preferably mixed with sodium bisulphate or other salts and glucose etc.; for cuprammonium, dilute caustic soda or other alkaline coagulating liquids may be used. In examples, (1) viscose is spun downwardly into a coagulating vessel provided with a partition extending nearly to the bottom, the spinning nozzle being 3-4 inches above the bottom of the partition; on starting, the vessel is filled to a point above the nozzle with a 65-80 per cent aqueous solution of sulphuric acid or a 60-70 per cent solution of benzene sulphonic acid, and the viscose is spun as usual, the threads being carried around a guide arranged at the bottom of the partition and out of the compartment remote from the nozzle; after spinning has begun, benzene is run into the nozzle compartment until it attains a level of 1-2 inches below the nozzle; (2) viscose, preferably obtained from unmatured or slightly matured alkali cellulose, is spun upwardly through a vessel filled with an aqueous solution containing 10 per cent sulphuric acid, 1 per cent ammonium sulphate, 15 per cent sodium sulphate and 10 per cent glucose, the formed filaments being carried around a roller into a bath comprising a 60 per cent aqueous solution of sulphoacetic acid and the yarn being wound on a bobbin rotating in or sprayed with water; after starting up, tetrachlorethane is run into the bath until it covers the nozzle by 1-2 inches.  Reference is made to Specification 359,976 regarding the application to cellulose esters and ethers. Specification 344,474 also is referred to.