GB759169A - Improvements in or relating to the continuous de-aeration of viscous spinning solutions - Google Patents

Abstract

<PICT:0759169/IV(a)/1> <PICT:0759169/IV(a)/2> Viscose spinning solutions for the manufacture of artificial threads and films are continuously deaerated by passing the solution upwardly through a vertical or nearly vertical pipe into a chamber which is maintained at a reduced pressure and from which the deaerated solution is finally discharged, the flow of solution up the pipe, the dimensions of the pipe, the supply of solution to the pipe and the reduced pressure together being so adjusted that, in an intermediate region of the pipe, the pressure on the solution is below the vapour pressure of the solution, the conditions in the pipe in and above said region being such that the bubbles, as they are formed, move upwards substantially at the same speed as the solution and the cooling of the solution as a result of boiling being such that, at the upper end of the pipe, boiling ceases. The vertical pipe may be provided with obstructions, e.g. sieves, to retard the rise of bubbles. The spinning solution may be preheated and specified solutions are, in addition to viscose and cuprammonium cellulose solutions, those of polyamides in benzene, polyacrylonitrile in dimethylformamide, cellulose acetate in acetone and copolymers of acrylonitrile in organic solvents. As shown (Fig. 1), viscose from a reservoir 1 flows through pipe 3, heater 4 and valve 5 to the vertical pipe 2, the upper end of which discharges into a chamber 10 maintained under reduced pressure. Air and gases are withdrawn at 11 and the deaerated viscose is discharged through pipe 6. In a modification (Fig. 2) viscose from heater 4 is fed through a pipe 7 with a narrowed end 8 into a concentric vertical pipe 2 provided with obstructions in the form of sieves 9.ALSO:<PICT:0759169/III/1> <PICT:0759169/III/2> Viscous spinning solutions for the manufacture of artificial threads and films are continuously deaerated by passing the solution upwardly through a vertical or nearly vertical pipe into a chamber which is maintained at a reduced pressure and from which the deaerated solution is finally discharged, the flow of solution up the pipe, the dimensions of the pipe, the supply of solution to the pipe and the reduced pressure together being so adjusted that, in an intermediate region of the pipe, the pressure on the solution is below the vapour pressure of the solution, the conditions in the pipe in and above said region being such that the bubbles, as they are formed, moved upwards substantially at the same speed as the solution and the cooling of the solution as a result of boiling being such that, at the upper end of the pipe, boiling ceases. The vertical pipe may be provided with obstructions, e.g. sieves, to retard the rise of bubbles. The spinning solution may be preheated, and specified solutions are those of viscose, cuprammonium cellulose, polyamides, polyacrylonitrile and cellulose acetate. As shown (Fig. 1), viscose from a reservoir 1 flows through pipe 3, heater 4 and valve 5 to the vertical pipe 2, the upper end of which discharges into a chamber 10 maintained under reduced pressure. Air and gases are withdrawn at 11 and the deaerated viscose is discharged through pipe 6. In a modification (Fig. 2), viscose from heater 4 is fed through a pipe 7 with a narrowed end 8 into a concentric vertical pipe 2 provided with obstructions in the form of sieves 9.