GB459123A - Manufacture of cellulose derivatives and of artificial filaments, films and other shaped structures therefrom - Google Patents

Abstract

Cellulose, including its conversion and oxidation products, is etherified in the presence of aqueous caustic alkali with ethyl chloride, the reaction being conducted at a temperature below 70 DEG C., or when the proportion of water present is not less than 11,5 mols. per mol. of caustic alkali, at a temperature below 80 DEG C. The process may be used for making cellulose derivatives containing not more than one ethyl group per 20 molecular units of cellulose, the temperature being kept below 60 DEG C. Simultaneously or consecutively with the etherification by means of ethyl chloride as above described, the cellulose may be treated with an alkylating agent containing another alkyl group than ethyl, a hydroxyalkylating agent, or a monohalogen fatty acid. Furthermore, any of these simple or mixed cellulose ethers may be xanthated. The solutions of the cellulose ethers or the cellulose ether xanthates, obtained by dissolving the cellulose compound in caustic alkali solution, if necessary using the cooling process described in Specification 212,864 [Class 2 (ii)], may be brought into an appropriate shape 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, and 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, e.g. a bath containing not less than 25 per cent and not more than 70 per cent of sulphuric acid. In an example, cellulose is ethylated by means of ethyl chloride at 50 DEG C., and the reaction product after bringing into solution in caustic soda solution, if necessary by cooling to 0 DEG C. or below, is formed into supportless or supported shaped products, such as artificial threads, films, coatings and the like. Further, the solution may be mixed with a dye or 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 shaped cellulose ether solution is subsequently coagulated and if desired plasticized. Examples are also given of the conversion of the cellulose ether into its xanthates, using amounts of carbon disulphide from 200 to 600 parts to each 1000 parts of cellulose. 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 modifications of the above examples, other proportions of ethyl chloride, and mixtures of ethyl chloride with other etherifying agents are used. In further examples, the ethylation is conducted at other temperatures, for example, from 60 to 75 DEG C. An example is also given in which the product of any of the earlier examples is further etherified, e.g. by means of alkylating, aralkylating, and hydroxy-alkylating agents. Specifications 25246/11, [Class 2 (iii)]; 12854/12, 6035/13, 149,320, 177 809, 177,810, 200,816, 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, 457,031, and 459,122 also are referred to.