GB547702A - A method for the manufacture of viscose rayon - Google Patents

Abstract

547,702. Artificial filaments. BUDD INTERNATIONAL CORPORATION. Jan. 1, 1941, No. 5. Convention date, June 29, 1940. [Class 2 (ii)] Freshly precipitated filaments obtained from viscose are passed from the precipitating bath to a thread advancing reel or the like and are subjected in sequence to treatment with the various liquids, including desulphuring liquids, required for completing the regeneration and for purifying. The various treatment liquids are allowed to intermingle upon the reel or the like but are so chosen that they do not give rise to undesirable reactions with each other. The liquids are caused to flow in counter current to the direction of advancement of the threads. The reagent used for desulphuring is preferably a cation-active substance employed in acid solution. It may be an aryl or alkyl substituted amine or pyridine derivative, or a fatty acid amide of the asymmetric diethyl-diaminoethane group. If it contains a fatty acid radical it may also be used for lubricating or avivifying the filaments. The filaments may be wound in helical turns round a cage or drum made so as to advance the filaments in axial direction while maintaining the spacing of the helical turns, or they may be wound in loops about two or more rolls with axes in parallel planes but inclined to each other, such an assembly constituting a unitary thread advancing device. At a distance of about 50 cm. from the lower end of the drum hot water may be dropped on the thread, and at a distance of a few centimetres above this there may be dropped on to the thread a warm acidified solution of a cationactive substance. If bleaching is desired, the bleaching agent may be dropped on the thread a short distance still farther up the drum. The coagulating liquid may be sulphuric acid and salt solution. As a result of the counterflow of the liquids, the washing and most of the desulphuring takes place before the water drip is reached. A quantity of cation-active substance is taken up between that point and the desulphurant drip for the purpose of lubrication or avivage. The desulphurant may be a substance which under. acid conditions is soluble in hot water but insoluble in cold water. In this case'it is precipitated together with the associated sulphur as it reaches the lower and colder part of the drum, but it does not interfere with the washing of the acid thread. The filaments may be dried as they pass round the upper part of the drum. The drum may be tapered to allow for shrinkage of the thread. Hydrogen peroxide may be used as the bleaching agent. In some cases the desulphurant and wash water may be introduced together.