GB362460A - Manufacture of artificial threads and other products from cellulose - Google Patents

Abstract

Artificial threads and other products are made from viscoses using the ordinary spinning or coagulating baths, while employing viscoses having viscosities much in excess of the viscosity of viscose normally used for spinning threads, and as compared with glycerine of 1,26 specific gravity, not substantially smaller than 50 per cent of the amount of the cellulose contained in 100 parts of the viscose, preferably not substantially smaller than 75-100 per cent of such amount. In particular, it is preferred to use viscoses the viscosity of which is not less than \bac<4>-6c<2>/4a\be, preferably not less than \bac<4>-6c<2>/3a\be, where c and a represent respectively the percentages of cellulose and alkali in the viscose, and in the case of viscoses containing 3 per cent or less of cellulose, a viscosity not less than \ba2c/a\be, preferably not less than \ba3c/a\be. By the use of such viscoses, threads having a high dry and wet tenacity are obtained without the use of plasticizing spinning baths. For the preparation of viscoses of these high viscosities, there may be employed a parent cellulose of high primary viscosity, a low temperature in the shredding of the alkali cellulose and in its maturing if that takes place, and a low temperature in the sulphidizing step. Examples are given of the spinning of threads, the manufacture of films, and the coating of fabrics. In these examples, the viscoses employed contain 3-6 per cent of cellulose and 5-8 per cent of alkali, and have viscosities between 1,2 and 45; and the threads leaving the coagulation baths, after passage through the air are led round a number of rods or rollers placed angularly to one another so as to permit of additional stretching of the threads which are finally wound up on bobbins running in dilute acid; alternatively, rollers running at varying speeds may be used to effect the stretching of the threads. After washing and before or after drying, the threads may be heated or steamed at high temperatures. The extensibility of the threads may be improved by treatment with shrinking agents, for example, according to the processes of Specifications 281,352, 312,197, 323,731, and 323,732, [all in Class 2 (ii), Cellulose &c.]. The viscoses may also be used in the manufacture of films, as coatings, dressings, sizings, adhesives and cements, in the manufacture of book cloth, artificial leather, plates and plastic compositions, and as thickening agents for pigments &c. Specifications 213,931, 264,161, 274,521, 274,690, 281,351, 298,548, and 317,608, [all in Class 2 (ii), Cellulose &c.], also are referred to.