Patent GB-359971-A (GB)
Title: Improvements in the manufacture and treatment of artificial products of cellulose derivatives
IPC: D01F2/28
Filed: 1930-07-30
Abstract: Comprises the manufacture and treatment of filaments, threads, ribbons, films, fabrics and other materials made of or containing cellulose esters or ethers by concentrating upon the ester or ether a substance having a solvent or swelling action and present initially in a concentration insufficient to exert such action. The process may be applied with or without stretching and the concentration may be carried to the point of coalescence. Solvent or swelling substances include acetone; ethyl alcohol; glycerine; thiocyanates; zinc chloride; acetic, formic and lactic acids; methyl and ethly lactate; mono- and di-ethers or esters or ether esters of olefine glycols and polyolefine glycols, e.g. mono- and di-methyl and ethyl ethers of ethylene and propylene glycols, glycol mono acetate, methyl glycol acetate, dioxane, mono ethyl ether of diethylene glycol; phenols; formaldehyde, acetaldehyde; mono-, di- and triacetins; dichlorethylene; mineral acids, sulphonic or other organo-mineral acids and acid esters of mineral acids; or mixtures of these or solvent mixtures. Diluents include water, alcohols, hydrocarbons, ethers, etc.; the diluent chosen being preferably more volatile than the solvent or softener. The solvent or softener is employed in a concentration such that during the period of application no strong solvent action is exerted. Filaments, threads, ribbons, &c. may be immersed or carried through a bath of the agent or the latter may be applied by spraying or by means of a wick or orifice. The relatively dilute solution of solvent or swelling substance may also be applied continuously with production of filaments, threads, &c., e.g. by spinning into aqueous baths, e.g. as in Specifications 177,868, 179,234, [both in Class 2 (ii), Cellulose &c.], 340,324, 340,325, 340,436, and 340,437; or threads, filaments, &c., produced by wet or dry spinning processes may be carried through baths or sprayed &c. with dilute solutions of swelling &c. agent. Diacetone alcohol, diethyl lactate, lactic acid, diethyl tartrate and like high-boiling solvents are applied in solutions of below 40-45 per cent, advantageously below 25-30 per cent.  The concentration of the solvent or swelling agent may be effected by evaporation of the diluent by heating, applying vacuum, or by a current of air, nitrogen, carbon dioxide, etc.; and may be effected at low, ordinary or high temperatures. Thus, diacetone alcohol &c. applied in a concentration of 15-25 per cent, is concentrated to 50-80 per cent; acetone, applied in ethereal solution of 20-40 per cent, is concentrated to 60-80 per cent or more. Alternatively the concentration may be stopped short and the solvent action brought into play by raising the temperature, if desired, in stages. Filaments &c. may be allowed to coalesce to form a ribbon, straw, &c., or coalescence may be prevented by guides or by the action of an inert liquid.  The concentration may also be effected by passing the threads through a liquid adapted to dissolve away the diluent or through a hot, inert liquid adapted to evaporate the diluent.  The invention is applicable to esters such as cellulose acetate, formate, propionate, butyrate and nitrate, and ethers such as methyl, ethyl and benzyl cellulose.  In an example, cellulose acetate filaments in transit from bobbin to bobbin are passed through a bath comprising ether, dioxane and water in the ratios 50/30/10.  The ether is then removed by passage through the air or preferably through a closed chamber through which warm air passes, or over a warm plate heated to 40-50 DEG  C.  The filaments may be kept apart by curved guides or allowed to coalesce to form a monofil or may be arranged in line to form a ribbon in which case rollers are employed to improve adhesion. Stretching may be effected by passing the filaments around a pair of rollers driven at different speeds.  Dioxane may be subsequently removed, e.g. by a salt solution as in Specification 328,911, [Class 2 (ii), Cellulose, &c.], or by first treating with a 20 per cent solution of dioxane, followed by water.  In a second example filaments of cellulose acetate are passed through a 20-25 per cent aqueous solution of lactic acid and then into a bath containing a petroleum fraction boiling at 250-300 DEG  C. and maintained at 110-130 DEG  C.  Specifications 277,089, 312,203, 323,790, 336,217, and 338,936, [all in Class 2 (ii), Cellulose &c.], also are referred to.