GB459122A - Manufacture of cellulose derivatives and of artificial filaments, films and other shaped structures therefrom - Google Patents

Abstract

Cellulose is etherified in presence of alkali with a proportion of ethyl halide which is smaller than one mol. of ethyl halide per 4 molecular units of cellulose. The cellulose may, simultaneously or consecutively with the treatment with the ethyl halide in the proportions specified, be treated with another alkylating agent, hydroxy-alkylating agent, or halogen fatty acid. The products may be converted to xanthates before they are worked up into technical products, particularly when the ether is insoluble or cannot be made soluble in caustic alkali solution. The products of the reaction may be dissolved directly in caustic alkali solution, if necessary, using the process described in Specification 212,864, [Class 2 (ii)], and the solutions brought into an appropriate shape. The shaped solutions, which may be supportless as with artificial silk, straw, films, bands and the like, or supported on rigid or pliable bases, as with coatings, layers, impregnations, dressings and the like, are coagulated by means of one or more coagulating agents, e.g. such as are used for coagulating viscose. The coagulated products may be plasticized, or the shaped cellulose ether or ether-xanthate solutions may be coagulated and plasticized in one bath. Suitable plasticizing baths are baths containing not less than 25 per cent and not more than 70 per cent of sulphuric acid. In examples, cellulose is etherified by means of ethyl chloride which is present in amount of 30--90 parts per 1000 parts of cellulose. The solutions obtained by dissolving in caustic alkali, if necessary using the cooling process described in Specification 212,864, is poured or extruded into a coagulation bath such as is used for coagulating viscose. Again, the solutions may be applied to a fabric, or may be mixed with a dye or a pigment and printed on to a fabric, or may be used for pasting together sheets of paper or cardboard, or fabrics, or for forming thick plates. In each case, the cellulose ether is subsequently coagulated and if desired plasticized. A number of examples are given of the conversion of the ethyl cellulose into its xanthate using amounts of carbon disulphide from 200 to 600 parts to each 1000 parts of cellulose. The xanthated mass is dissolved in water and caustic soda, if necessary while cooling to 0 DEG C. or below, and the solution worked up into artificial threads, fibres, coatings, and the like. Before working up the solutions of the cellulose ethers or the cellulose ether xanthates, there may be added viscose, softening agents, and the substances which may be contacted with viscose described in Specifications 335,906, [Class 2 (ii)], 341,843, 341,930, 357,121, 357,154, 357,526, 357,549, 385,979 and 390,518. In other examples, the ethyl celluloses obtained are further etherified by means of ethylene chlorhydrin, glycerol alpha-monochlorhydrin, ethylene oxide, or propylene oxide. Specifications 25246/11, [Class 2 (iii)]; 12854/12, 6035/13, 149,320, 177,809, 177,810, 200816, 200,834, 203,346, 203,347, 216,475, 217,166, 281,352, 312,197, 323,731 and 323,732, [all in Class 2 (ii)], and 341,899, 374,964, 390,517, 393,932, 408,932, 408,950 and 457,031 also are referred to.