Patent GB-362437-A (GB)
Title: Manufacture of artificial threads and other products from cellulose
IPC: C08B13/02
Filed: 1930-05-28
Abstract: In the manufacture of artificial threads and other materials from products of the action on cellulose xanthate of a reagent having a tendency to react with a compound containing a hydroxyl group so as to cause introduction of an organic group or radical in place of the hydrogen of the hydroxyl, a cellulose xanthate poor in, or substantially free from water is contacted with one or more reagents of the type specified, with retention of at least part of the CSS--groups contained in the cellulose xanthate.  The cellulose xanthate may be used in the form of a solid or semi-solid mass such as a paste or lumpy mass, a soft or rigid cake, or a flocculent mass. The water content may be removed by a dehydrating agent such as alcohol, or by evaporation, or the product resulting from the action of carbon bisulphide on alkali cellulose may be employed.  In the manufacture of materials such as plastic masses or thick coatings, the product need not be dissolved, but for the production of threads it is preferred to convert the product into a solution by the addition of water or caustic alkali solution.  In examples, crude cellulose xanthate is kneaded with a -dichlorhydrin, the temperature being allowed to rise as a result of the heat of reaction.  The crude product is cut up or passed through a mincing machine and is dissolved in caustic soda solution to make a solution suitable for spinning threads.  After filtering and ageing, the solution is extruded into sulphuric acid of strengths between 40 and 70 per cent. The thread may be given a long air path after emergence from the bath, and may be stretched by passing over rods or rollers, or if no stretching device is provided, the speed of spinning may be high so as to cause stretching of the threads.  As starting material wood pulp or cotton linters of high viscosity characteristics may be employed and in such cases the content of cellulose in the final spinning solution may be lower than normal.  Instead of using sulphuric acid of plasticizing strength, a more dilute solution may be employed as the coagulating bath and the acid may be mixed with sodium sulphate.  The spinning solution may first be extruded into a coagulating bath comprising ammonium sulphate, or a mixture of dilute sulphuric acid and sodium bisulphate, or sodium sulphate, ammonium sulphate, zinc sulphate and glucose in dilute sulphuric acid, and the coagulated thread is then passed through strong sulphuric acid which may contain a salt such as ammonium sulphate.  The threads are washed and may be heated or steamed before or after drying.  Films may be produced in a similar manner by extrusion through a hopper and slit. A cotton fabric may be impregnated or coated on a padding, backfilling or spreading machine with a solution of the product of cellulose xanthate and a chlorhydrin to which talc, china clay, a dyestuff, mica, or lampblack may be added.  The fabric is then passed through a coagulating or plasticizing bath, washed and dried.  The extensibility of the materials obtained may be further increased by treatment with shrinking agents.  Instead of a -dichlorhydrin, ethylene chlorhydrin, other halogen derivatives or other esters of di- or polyhydric alcohols, inorganic esters of monohydric alcohols, halogen derivatives of ethers aldehydes or ketones, halogen olefines, di- or polyhalogen paraffins, halogen derivatives of oxyalkylamines or oxyaralkylamines, or cyclic ethers of di-or polyhydric alcohols may be used.  Halogen fatty acids may also be used when the process is carried out with the use of a plasticizing bath.  Specifications 12854/12, 231,800, 281,352, 312,197, 323,731, 323,732, 335,906, [all in Class 2 (ii), Cellulose &c.], 357,121, 357,154, and 357,526 are referred to.