GB930614A - The production of pigmented regenerated cellulose filaments - Google Patents

Abstract

A step in the continuous production of pigmented regenerated cellulose filaments from a viscose stream comprises introducing a dispersion of a pigment powder in a liquid, e.g. viscose, into the viscose stream at a controlled rate by placing a supply of the pigment dispersion in communication with the viscose stream and with one side of a liquid-impervious, flexible membrane, e.g. of rubber, and supplying a second liquid, e.g. an oil, at a controlled rate, e.g. by pumping, to the other side of the membrane. A suitable diaphragm pump comprises two chambers separated by the liquid-impervious, flexible diaphragm, e.g. of rubber, pumping action being effected by the introduction and withdrawal of the working liquid, e.g. oil, to and from one of the chambers. In the embodiment shown the space enclosed by a tubular diaphragm 4 forms one chamber and the space between the diaphragm and a casing 1 the other. The powder suspension enters and leaves the inner chamber via passages 3a and is prevented from settling by a stirrer 10 which circulates the suspension around an apertured tube 5, as indicated. A body 6 is provided to reduce the volume within tube 5. Oil is pumped into and out of the outer chamber through ports 1a, 1b, the outward flow serving to draw a fresh charge into the inner chamber. In another embodiment the pump comprises two mirror-image, hemispherical ports with a hemispherically shaped diaphragm clamped between them. A continuous supply circuit is described employing three pumps of the second embodiment operating 120 degrees out of phase relative to each other and provided with automatically-actuated valves.