GB743625A - Improvements in the production of artificial filamentary material containing effect materials - Google Patents

Abstract

<PICT:0743625/IV(a)/1> A spinning solution and a liquid concentrate containing an effect material are continuously fed at a fixed rate ratio into a blending zone wherein they are thoroughly intermixed to form a spinning blend which is then extruded to form a filamentary material, the rates at which the spinning solution and concentrate are fed to the blending zone being so controlled by means operated by the pressure of the spinning blend after it has left the blending zone that this pressure is kept substantially constant. If desired, part of the spinning blend coming from the blending zone may be passed back to the blending zone. The liquid concentrate may be continously circulated through a system which includes a storage zone, and a minor proportion of the circulating concentrate is continuously withdrawn from the system at a point outside the storage zone and added to the spinning solution. More than one concentrate may be employed and streams of the different concentrates may be circulated through separate systems before being added to the spinning solution. The concentrate may be made by forming a dispersion of finely divided solid effect material in a solution of filament-forming material, passing the dispersion through a filter, and then recycling it one or more times through the same filter. The spinning solution may be a solution of cellulose acetate or other cellulose derivative or of polyacrylonitrile, vinyl chloride-vinyl acetate copolymers, or other polyvinyl compounds. It may be a cuprammonium cellulose solution or viscose. The effect material may be a pigment, dye, fire-retardant, filler, softening agent, size, resin, catalytic agent, or lubricant, e.g. titanium dioxide, zinc oxide, china clay, mica, diacetyl-benzidine, ochre, red lead, Prussian blue, chrome green, burnt umber, pearl essence, nacreous mercurous chloride, lamp - black, beta - chloronaphthalene, glycol oleate, and glycerol stearate. As shown in Fig. 1, different liquid concentrates are supplied from separate vessels 11 from each of which a pipe 12 leads to a storage vessel 13 provided with a stirrer 14. A pipe 17 leads from the bottom of the storage vessel through pump 16 and valve 18 to a supply header 19, from which proceed a number of supply pipes 21. A pipe 211 and relief valve 2111 connect the output side of pump 16 with the top of vessel 13. Each supply pipe 21 leads through a pipe 22 to a return header 23 which leads back to vessel 13. Each pipe 21 also leads through pump 27 to a pipe 28 which has a pump 29 for the supply of spinning solution. Pipe 28 leads to the input side of a rotary blender 30 from which pipe 31 leads to one end of a spinning header 32, a pipe 33 leading from the other end through pump 34 to the pipe 28 between pump 29 and the point at which the first of the supply pipes 21 comes in. Pipes 36 lead from the spinning header 32 to metering pumps 37 and spinning jets 38. Pumps 27, 29, 34, are of the positive displacement type, e.g. gear-wheel pumps. A pressure-responsive control 51 is connected to pipe 31 on the output side of the blender 30. For driving pumps 27, 29 and 34 there may be provided a motor which drives a main shaft through a positive infinitely variable transmission device which is controlled by means of the pressure-responsive control 51. The main shaft drives the pumps 29, 34 and the blender 30 directly through belting and also drives pumps 27 through belting and individual positively variable transmission devices. In operation, it is preferred to cause 50 per cent or more of the concentrate leaving vessel 13 to return through pipe 211 and to cause at least 75 per cent of the remainder to return through pipes 22 and 23, the rest being fed by pump 27 to the pipe 28. Spinning solution is fed into pipe 28 by the pump 29. From blender 30, the spinning blend is passed to the header 32 at a rate substantially greater than that at which it is withdrawn by the metering pumps 37, and the excess of the blend is fed back to pipe 28 by pump 34. The apparatus enables the proportions of the several effect materials in the spinning blend to be maintained constant as long as desired and enables the pressure of the blend presented to the metering pumps 37 to remain constant, so giving rise to a very high degree of uniformity in the filamentary product.