GB472888A - Improvements in and relating to the manufacture of artificial structures - Google Patents

Abstract

Artificial threads, films, dressings, finishings, printings, cements, adhesives, plates and artificial structures in general are prepared from caustic alkali solutions of cellulose ether xanthates, preferably xanthates of alkali-soluble cellulose ethers, by using for the coagulation of the shaped structure a secondary alkali carbonate, the cellulose ether xanthate employed being made with a proportion of carbon bisulphide not smaller than 20 per cent of the weight of the original cellulose ether, for example, 25--30 or 40--50 per cent of carbon bisulphide. Instead of a cellulose ether xanthate there may be employed a product obtained by bringing together an alkali-soluble cellulose ether and a cellulose xanthate, in this case the minimum proportion of carbon bisulphide being calculated on the sum of the weights of the cellulose ether and the cellulose of the xanthate; or, alternatively, there may be used a product prepared by bringing together a cellulose ether xanthate and an alkali-soluble cellulose ether, in this case the minimum proportion of carbon bisulphide being calculated with respect to the total proportion of cellulose ether, that is, xanthated or otherwise. The cellulose ether xanthate may also contain cellulose xanthate, and in its preparation, particularly its dissolution, a temperature below 5 DEG C., even below -10 DEG C., may be employed, at least temporarily; and the cellulose ether xanthate may be permitted to age beyond the C24, preferably beyond the C36 stage. An aqueous solution of secondary sodium carbonate is preferably used as the coagulation bath; and the bath may also contain a salt of alkaline reaction such as dibasic and tribasic phosphate, an alkali borate, silicate, thiosulphate, acetate, &c., or a neutral salt such as alkali sulphate or chloride, and an organic substance such as glycerine a sugar or turkey red oil. The secondary alkali carbonate may be used as the primary coagulation bath; or the structure may be preliminarily coagulated in a bath, say of ammonium sulphate or chloride, acid sodium silicate, sodium bisulphite, methanol or ethanol, and afterwards the coagulation completed in the bath of secondary alkali carbonate. The coagulated product may be washed with water, or it may be treated, with or without washing, with a bath containing an acid, or a neutral, acid or alkaline salt, or with another bath capable of coagulating viscose etc.; or alternatively the product may be first treated with a cold, warm or hot solution of a primary or secondary alkali carbonate. The cellulose ether xanthate may be derived from an alkyl cellulose, hydroxyalkyl cellulose, alkylhydroxyalkyl cellulose or an hydroxy-acid ether of cellulose; and it may contain not more than one ether group to 2, 4 or even 6 C6H10O5 units. The secondary alkali carbonate may be reconstituted in the coagulation bath by introducing carbon dioxide. Specifications 25246/11, [Class 2 (iii)], 231,808, 231,811, 281,352, 312,197, 323,731, 323,732, 335,906, 335,994, [all in Class 2 (ii)], 341,843, 341,899, 357,121, 357,154, 357,167, 357,526, 357,527, 357,595, 362,437, 367,920, 368,288, 374,964, 385,979, 390,517, 390,518, 390,519, 408,932, 408,950, 459,122, 459,123, 462,283, 462,456, 462,712, 462,713, 469,007, and 470,747 are referred to.