GB787407A - Improvements in and relating to the production of artificial filaments - Google Patents

Abstract

<PICT:0787407/IV (a)/1> <PICT:0787407/IV (a)/2> In the production of artificial filaments having a variable denier along their length, a spinning liquid is pumped from a supply line to a jet by two separate paths at a constant rate of flow in each path and one path is intermittently blocked, the flow in this path being diverted to a liquid-receiving channel. The diverted liquid may be returned to the supply line or to a second jet. Suitably, each feed pipe has a pump for delivery of spinning liquid to the jet and a slubbing valve placed in one pipe closes in response to an intermittent signal. As shown, viscose is fed from a supply line 1 to a jet 2 through pipes 3, 7 by gear-pumps 4, 6, the feed pipe 7 from the pump 6 to the jet including an intermittently operated slubbing valve 8. This valve comprises a cylinder 9 housing a piston 10 having a passage 11 which connects the pipes 7, 3 when the piston is in its uppermost position, the connection being interrupted when the piston is held in its lowermost position under the action of a spring 12, and the viscose delivered by the pump 6 being then returned to the supply line 1 through a relief valve 13. The valve 8 is operated by compressed air from a valve 17 having a cylinder 18 housing a piston 19 which, according to its position, connects either a compressed air line 20 or a vent pipe 21 to the cylinder 9 of the valve 8. The piston 19 is urged to the left by a spring 28 but is drawn to the right when a solenoid 22 is energized by the closure of a switch 23, the switch being closed when a cam follower 24 falls into a notch 25 of a rotated notched disc 26. When the piston 19 is drawn to the right, compressed air from pipe 20 enters the cylinder 9 and pushes the piston 10 upwardly until the pipes 7, 3 are connected through the passage 11. Viscose then flows from the pump 6 to the jet 2 through the pipe 3 and, due to the fall in pressure, the relief valve 13 closes. The increased flow of viscose through the jet 2 causes the freshly formed filament to increase in denier, forming a slub. Eventually, the follower 24 is lifted out of the notch 25 of the disc 26 and again rides on a salient portion 27. The solenoid 22 is de-energized, the piston 19 moves over to the left under the action of the spring 28, the compressed air supply is shut off and the cylinder 9 is vented to the atmosphere. The piston 10 falls under the action of its spring, thus shutting off the viscose delivered to the jet 2 by the pump 6, and the denier of the freshly formed filament falls to its constant minimum value. The relief valve 13 is pushed open by the pressure of viscose in the pipe 7 and the throughput of the pump 6 is returned to the line 1 by way of the pipe 30. The length of the slubs formed in the filament can be varied by varying the size of the notches 25 and the rate of rotation of the disc 26. Fig. 2 shows an alternative apparatus in which, when the connection between the pump 6 and the jet 2 is interrupted, viscose is delivered by the pump 6 to a second jet 31 and, when the connection between the pump 6 and the jet 2 is opened, the viscose delivered by the pump 6 passes partly to the jet 2 and partly to the jet 31, the arrangement being such that, when a slub is formed at jet 1 a filament of minimum denier is extruded from jet 31, and vice versa. An alternative construction of slubbing valve is also described (see Group XXIX). The process is applicable to the production of slubbed filaments by wet, dry or melt spinning and, instead of viscose, the starting material may be cellulose acetate, nylon, protein or polyacrylonitrile or like materials. Specifications 579,069 and 703,697 are referred to.