GB619564A - Improvements in or relating to the manufacture of cellulose acetate filaments, filmsor the like - Google Patents

Abstract

<PICT:0619564/IV(a)/1> <PICT:0619564/IV(a)/2> <PICT:0619564/IV(a)/3> <PICT:0619564/IV(a)/4> Filaments, films and the like of cellulose acetate are dried throughout their section by the action of a radio frequency electrostatic field applied as they issue from the spinning orifice through which the solution or suspension of acetylated cellulose is forced, the dried filaments or films being subsequently wound up on a collecting device. If desired, the member in which the spinning orifice is situated, and the winding device or a guide roller receiving the filaments may form the heating electrodes, thus concentrating the lines of force along the filaments or film instead of transversely thereto and giving the maximum heating effect. The atmosphere in the spinning cabinet may, if desired, be saturated or supersaturated with acetone or other suitable solvent to prevent initial rapid drying out of the outside surface of the filaments. In Fig. 1, a spinneret 12 centrally disposed near the upper end of a spinning cabinet 13 is connected to the negative or earth side of a source of radio frequency energy 20. The positive pole is connected to an insulated guide 18 over which the filaments 17 are drawn, this guide being disposed beneath a central aperture 16 in the lower end of the cabinet. To prevent rapid initial drying an atmosphere saturated or supersaturated with acetone or other suitable solvent is injected through a nozzle 33 mounted in the wall of the cabinet. The base of the cabinet carries a drainage tube 14 for drawing off condensed solvent. To prevent the filaments from being wound in a positively charged condition, a further guide 19 is interposed between the guide 18 and the wind-up roll 23, this guide 19 being connected to the negative side of the source of energy, thus earthing the filaments. Alternatively, the guide 18 may be replaced by a guide 24 (Fig. 2) midway along the cabinet, and the guide 19 by a guide 25 beneath the outlet aperture 16. Fig. 3 shows a modification using spaced heating electrodes 26 and 27; in this case the electrostatic field lies transversely to the filaments 17. A cavity resonator 29 (Fig. 4) may also be employed, the filaments passing therethrough and being heated by micro-waves passing along a wave-guide 30 into the resonator.