Patent GB-304717-A (GB)
Title: Process of and apparatus for manufacturing seamless flexible tubes from cellulose solutions, particularly viscose
IPC: B29C48/09
Filed: 1928-12-07
Abstract: 304,717. Wolff & Co., and Weingand, R. Jan. 25, 1928, [Convention date]. Apparatus for making films.-Seamless tubes of any desired length are prepared from cellulose solutions particularly viscose by allowing the cellulose solution to flow solely by its own weight without the aid of extraneously applied pressure from an annular nozzle along a guide member adapted to the tubular shape and bathed with coagulating liquid in such a manner that the cellulose solution is coagulated internally immediately it issues from the nozzle and at the same moment that it assumes the tubular form. The continuous flow of coagulating liquid round and along the guide member ensures that the resulting tube will slide off the guide member by action of gravity and shrinkage of the tube during this sliding movement is prevented by guiding the moving layer on a solid body during coagulation. The resulting tube detaches itself automaticallv from the lower end of the guide member and is then conducted to the fixing bath, in which coagulation is completed from the outside. Alternatively, a coagulating liquid may be applied to the outside of the tube during its descent along the guide member, which may dip wholly or partially into the fixing bath. The amount of coagulating liquid supplied to the guide member is preferably adjusted so that no excess of liquid accumulates during the formation of the tube and further depends upon the degree of ripeness and the composition of the cellulose solution, the width and thickness of the tube, and the working speed. The annular nozzle may be replaced by any other shaping and feeding arrangement; for example, the guide member may be tapered at its upper end and inserted into a cylindrical tube, so that, by altering the relative lengths of the tube and conical guide member, the thickness of the tube can be modified. In the form of apparatus shown in Fig. 1, the cellulose solution is fed into a funnel 1, which merges into an annular nozzle 2, into the inner rim of which a guide member 3, which may be cylindrical, is fitted. The supply of coagulating liquid to the guide member 3 through tube 4 is controlled by the valve 5, so that the guide member is continuously irrigated all over with coagulating liquid 8 and the cellulose solution immediately coagulated internally on issuing from the nozzle. The descending tube 7 detaches itself automatically from the lower end of the guide member and sinks into the fixing bath 6, in which the external coagulation is effected and the tube is then removed over rollers 9 and treated in a continuous operation with the usual washing, bleaching, desulphurizing, colouring, and plasticizing baths, followed, if desired, by drying. In the apparatus shown in Fig. 2, the annular nozzle is replaced by a cylindrical tube 10, into which the slightly conical upper end 11 of the guide member 3 is inserted, so that the thickness of the tube in course of formation is determined by the space between these two members. The tube 4 may be provided at its lower end with a conical cover 12 and the guide member may be immersed in the fixing bath, so that external coagulation of the tube is effected while it is still supported on the guide member. Alternatively, the tube may be irrigated with precipitant externally by means of an annular nozzle 14.