Patent GB-820508-A (GB)
Title: Improved process and apparatus for continuous manufacturing of artificial threads according to the wet-spinning method
IPC: D01D5/06
Filed: 1956-09-27
Abstract: <PICT:0820508/IV (a)/1> In the manufacture of artificial threads by the wet-spinning method in which a number of threads after their initial coagulation, but before they have become completely coagulated or fixed, are arranged side-by-side to form a sheet of parallel travelling threads spaced a small distance apart, and the sheet of threads is caused to travel through one or more fixing baths, in which the coagulation of the threads is completed, and finally through one or more after-treatment baths, the sheet of threads is passed through the or each fixing bath by means of a positively-driven roller which is partly immersed in the bath liquid and which has a diameter of at least 40 cm., preferably at least 60 cm., the threads being caused to pass underneath and in contact with a portion of the peripheral surface of the roller and the line at which the sheet of threads first contacts the roller and the line at which the sheet leaves the roller being above the level of the liquid in the bath, and the threads are then exposed to the after-treatment liquids while still assembled in sheet form without being in contact with rollers or other guide means over the greater part of their path of travel through the after-treatment baths.  As shown, a spinning solution is extruded through a row of spinnerets 2 into a spinning bath 1 to form threads 3, each of which passes over a freely rotatable roller 4 through a comb 6 to a common draw-off device 5 comprising three positively-driven rollers on which the threads are arranged side-by-side to form a sheet.  The sheet of threads is then led round a positively-driven roller 7 which has a diameter of 50 cm. and is partly immersed in a fixing liquid in a trough 8 which is concentric with the roller 7.  The sheet of threads then travels to a positively-driven guide roller 9.  The fixing liquid is supplied to the trough 8 through a tube with an overflow and weir 10 and is discharged from the trough 8 through an overflow weir and conduit 11. The lower roller of the draw-off device 5 and the guide roller 9 are so disposed with respect to the roller 7 that the threads arrive on and leave the roller 7 above the level of the fixing liquid in the trough 8.  From the roller 9 the sheet of fixed threads is led to a wash bath 13 via a positively-driven roller 12, in which bath the sheet is immersed by means of non-driven rollers 14 between which the sheet travels through the bath in a free path without support.  The sheet is then passed in a similar manner through each of the series of after-treatment baths 16-19, dried on heated rollers 20 and finally wound.  The process is particularly suitable for spinning viscose, the coagulation, regeneration and after-treatment baths being of conventional type.  The axis of rotation of the roller in the or each fixing bath is preferably above the level of the bath liquid to prevent the acid liquid from reaching the bearings.  The use of a large diameter roller in the fixing bath (or in each fixing bath) renders it possible to arrange the threads very closely together in the sheet without subjecting the threads to a high tension before they have become completely coagulated.