Patent GB-541075-A (GB)
Title: Improvements in or relating to the production of artificial filaments, films and similar materials
IPC: D01F2/28
Filed: 1940-05-07
Abstract: 541,075. Artificial filaments, films &c. MONCRIEFF, R. W., WHEATLEY, E. W., and BATES, H. May 7, 1940, No. 8180. [Class 2 (ii)] Artificial filaments, threads, yarns, bristles, foils, films, and like shaped materials are obtained by shaping a fused composition comprising a higher fatty acid ester of cellulose and a volatile aromatic hydrocarbon or halogenated aromatic hydrocarbon which is a solvent for the cellulose ester at room temperature as well as at elevated temperature, and setting the shaped materials by cooling. As cellulose ester there may be used a cellulose butyrate, valerate, capronate, laurate, stearate, aceto-butyrate, or butyro-laurate. The ester may contain 2 or less up to 3 acidyl radicals per glucose unit of the cellulose molecule. The volatile solvent may be benzene, toluene, or a xylene, or monochlorbenzene. The compositions may be produced by making a dilute solution of the cellulose ester and then concentrating by evaporation to form a composition which is solid at ordinary temperature. The composition may be maintained in fused condition by heating as evaporation proceeds and it may be fed directly in that condition to the shaping device. The preliminary dilute solution may contain a .solvent of greater volatility, in addition to the volatile solvent desired in the final composition. The fused composition may be passed through a narrow pipe immersed in a heating medium and communicating directly with the shaping device. Shaping is preferably effected at a temperature of 5-50‹ C. above the melting point of the composition. The composition may be forwarded to an extrusion orifice by gravity or under fluid pressure, or by means of a gear-pump which may be immersed in a bath of non-solvent for the cellulose ester, maintained at the temperature of the composition. Setting of the shaped composition may be effected by cooling in a liquid, gaseous, or vaporous medium. Removal of solvent may take place at the same time as the setting in the cool medium. The filaments or like products may be stretched continuously with production. Residual solvent may be removed from the formed materials by washing with a liquid which is miscible with the solvent, or by evaporation under reduced pressure. The ironing point of the formed filaments may be increased by subjecting them to an esterification treatment. The filaments may be subjected to a saponincation treatment. They may be twisted into yarns and formed into woven, knitted, or other fabrics. Filaments of high denier may be used as artificial horsehair or bristles. The filaments may be formed into staple fibre and crinkled. The films may be used for wrapping or photographic purposes or for the production of splinterless glass. In an example, cotton is pre-treated with acetic acid containing sulphuric acid, pressed, and treated with butyric acid and butyric anhydride. The cellulose butyrate obtained is precipitated from the solution by pouring into water. It is purified by washing with water and dilute sodium carbonate, dissolving and re-precipitating, and then drying. It is dissolved in benzene and the solution is concentrated by evaporation until a 40 per cent concentration is obtained. The solution is passed through a heated stainless steel tube and extruded into air. The filaments are washed with petroleum ether and then dried. Specifications 317,025, 317,026, [both in Class 120 (iii)], 357,565 ; 384,335, 394,702, 409,519, 484,192, [all in Group IX], 523,425, 523,774, 524,897, 529,142, 529,510, 532,673, 532,674, 534,273, 534,775, 535,894, and 540,967 are referred to.