GB674869A - Improvements in or relating to the production of artificial yarns - Google Patents

Abstract

<PICT:0674869/IV (a)/1> <PICT:0674869/IV (a)/2> <PICT:0674869/IV (a)/3> <PICT:0674869/IV (a)/4> A plurality of artificial yarns are led continuously with their production and while in warp formation continuously through a series of liquid treatment operations to a final drying operation, the yarns being passed through squeezing rollers at the end of each liquid treatment operation and, during each liquid treatment operation, following a free path out of contact with any substantial body of liquid, whereby frictional drag on the yarns is substantially avoided and the tension on the yarns is held at a low value. The treating liquids may be sprayed on to the yarns, or each yarn may travel through a shallow trough during the liquid treatment. The speed of the squeezing rollers may be controlled so as to allow for shrinkage of the yarns during the treatment and maintain them at a desired tension. The process is particularly applicable to the production and treatment of yarns from viscose, and the treatments may include washing, desulphurizing, bleaching, rinsing, sizing, and dyeing. A lubricant may be applied to the yarns after completion of the liquid treatment and before drying. The apparatus used may comprise in association with means for forming the artificial yarns and arranging them in warp fashion, a plurality of liquid treatment vats disposed in line, a plurality of juxtaposed trough or channel-like elements disposed in the same direction at or on the upper surface of the vats, means for continuously supplying liquid to these elements and for allowing liquid to drain continuously into the vats, and squeezing rollers located between the vats and at the end of the last vat in the line, the arrangement being such that a straight line may be drawn through the elements and the nips of the rollers so as to constitute a straight path for the travel of the yarns from one end of the apparatus to the other. As shown in Fig. 2, viscose is extruded from a large number of spinning nozzles which dip into a coagulating bath 2. The groups of superficially coagulated filaments pass through tubes 4. The sheet formed of the groups of filaments 3 is taken up by rollers 6, 7, 8, and excess of liquid is expelled by the pressure roll 9. The sheet of yarns is stretched while passing through bath 10 which contains hot water or dilute sulphuric acid, stretching being effected by the pull of rolls 11, 12, 13. The sheet 3 then passes in succession through several liquid treatment baths and remains in a plane and horizontal or slightly inclined disposition throughout all these treatments. The first washing device 17 comprises a series of parallel open troughs, one trough being provided for each group of filaments or for each yarn. As shown in Fig. 4, the troughs are formed by corrugations in a metal sheet 17. A sprinkler 18 feeds hot or cold washing liquid to each of the troughs. The metal sheet 17 may be arranged at the upper surface of a vat so that the liquid continuously drains from the troughs into the vat. Surplus liquid is squeezed from the sheet of yarns by rollers 19, 20. The sheet of yarns then passes through similar troughs for further liquid treatments. In the final trough 26, a lubricant such as a solution of cetyl pyridinium bromide may be applied to the sheet. Surplus liquid is expressed by rolls 28, 29 and 30, 31, and the sheet of yarns then passes to a drying chamber. As shown in Fig. 5, the sheet of yarns 3 passes vertically upwards and downwards in the drying chamber around rollers 37-53. The sheet is heated by means of infra-red ray lamps 54-64. Air is injected into the drying chamber 35 from a chamber 65, and the moist air is removed through ducts 66-70. The hot moist air which is extracted from the chamber may be used to heat the fresh air which is fed to the chamber. The rollers may be circumferentially grooved so as to reduce the area of contact with the yarns, and the speeds of the rollers may be adjusted to allow for shrinkage. If desired, some of the rollers may be non-positively driven. Preferably, means are provided for setting up successive local areas of turbulence in the treatment liquids in contact with the yarns. For this purpose the troughs may be provided with tranverse vertical or inclined baffles or with channels or depressions in the bottom or side walls. As shown in Fig. 7, each trough 80 is provided with a treatment liquid inlet 81 and the bottom of the trough is impressed to form spaced projections or barriers 83 extending across the width of the trough. In another construction, the baffle members are U-shaped members comprising wires projecting from the walls of the trough. In another construction, the trough is provided with a series of inlet pipes for treatment liquid, these being located in a side wall of the trough so that local areas of turbulence in the flow of liquid are set up. Specifications 16495/07, [Class 2], 211,446, 311,399, [both in Class 2(ii)], 356,975, 432,692, 602,001, [Group IX], 650,896 and 655,516 are referred to.