Patent GB-483731-A (GB)
Title: Improvements in or relating to the manufacture of artificial textile fibres
IPC: D01F2/06
Filed: 1936-08-21
Abstract: Artificial wool, cotton, &c. are made from solutions of casein derived from milk by a process involving the following steps: acid coagulation of the milk at a pH value less than 4,5; solution of the casein so obtained in sodium hydrate or potassium hydrate or mixtures thereof; maturing of the solution until it acquires a viscosity suitable for spinning; spinning such solution into an acid coagulating bath; treating the coagulated fibres in a bath in which formaldehyde forms the basic substance for rendering the fibres sufficiently insoluble to permit washing; washing the fibres; treating the fibres to render them completely insoluble. For the coagulation of the casein there is conveniently added to the milk sufficient sulphuric acid to give pH 2,9-3,0.  The acid may be added in two separate quantities.  The treatment with acid of pH value less than 4,5 may be applied to caseins which have been obtained by coagulation of milk at a pH value in excess of 4,5.  The temperature at which the coagulation is carried out is approximately 20 DEG  C.; after coagulation, the casein is heated with the serum to about 61 DEG  C.  The separated casein may be pressed, or washed and dried, and to it may be added sterilizing agents, or mineral substances such as colloidal metal solutions or finely divided metal oxides in order to obtain mineralized artificial fibres.  For the preparation of the casein solution for spinning there is employed a proportion of alkali to casein in approximately the ratio of 23 litres of 35 DEG  B<\>ae. sodium hydrate to 100 kilos. of casein; the casein is first stirred with water, the caustic alkali is then added and stirring is continued either continuously or at intervals until a uniform product is obtained; the solution is allowed to mature and if necessary is diluted with tap water or by the addition of milk serum obtained in the acid coagulation of the subsequently neutralized casein, or by a solution of sodium lactate, formate or bisulphite, or by a solution of sodium, ammonium or copper sulphate, or by soap solution; 100 kilos of casein are used for making approximately 400 litres of solution; solution and maturing may take place at 24 DEG  C. or generally between 14-34 DEG  C. maturing being accelerated by raising the temperature; when during maturing the viscosity suitable for spinning has been developed, further maturing may be prevented and the solution stabilized by lowering the temperature below the above limit.  To the casein solution there may be added carbon disulphide, sodium sulphide, cellulose xanthogenate, or the products obtained by treating soaps, glycerine &c. with carbon disulphide in the presence of alkali, or generally sulphides or xanthogenates, for the purpose of accelerating the subsequent coagulation of the casein from its solution.  In the use of cellulose xanthogenate, the proportion added has a material effect on the character of the resulting textile fibre; thus, when the proportion of casein to cellulose is high the product resembles natural wool or silk, and when the proportion is low a product resembling cotton is obtained.  By the addition of alkali silicates or solutions in alkali of zinc or aluminium, a mineralized product may be obtained.  The resulting solutions, after filtration, are extruded into an acid coagulating bath, which may contain a substance capable of rendering the filaments insoluble, for example, aluminium salts, or tin salts, or formaldehyde.  Suitable baths are for example sulphuric acid, sodium sulphate, aluminium sulphate or potash alum, and advantageously small quantities of tin salts; or sulphuric acid, aluminium sulphate or potash alum, and sodium chloride, and optionally small quantities of magnesium, zinc or ammonium sulphates &c.  The speed of spinning may vary from 80-120 metres per min; the temperature of the coagulation bath may be between 48-58 DEG  C.; and the length of travel in the bath may be 30 centimetres or more.  In order to permit of washing, the coagulated filaments are first rendered partly insoluble by treatment with formaldehyde preferably with an addition of sodium chloride to prevent swelling of the filaments; the baths may also contain additions of aluminium salts and of acid.  It is preferred to use formaldehyde-sodium chloride baths of increasing concentration, with respect to formaldehyde.  The filaments may be collected on bobbins or in a centrifugal machine, or they may be formed into tufts which are conveniently allowed to fall into a sodium chloride bath to which small quantities of aluminium salts p  or acid are added and optionally formaldehyde; or after treatment with the insolubilizing baths, the filaments may be collected as skeins and then cut to the desired length and subjected to the further treatment.  It is convenient to conduct the initial insolubilizing with the filaments under tension, and then to treat the cut-up fibres with the concentrated bath in which they undergo a desirable twisting.  After the washing and final insolubilizing, the fibres may be subjected to a softening treatment with sulphonated oils alone or mixed with soaps, emulsified fats or oils, glycerine &c.  Such softening treatments are unnecessary if softening agents have been incorporated in the spinning solution.  Specifications 483,807, 483,808, 483,809, and 483,810 are referred to.