GB426912A - Improvements in the manufacture of artificial filaments, yarns, horse-hair, films, and like products - Google Patents

Abstract

In the manufacture of artificial filaments, threads, bristles, or films, a solution containing a suitable base and a finely divided solid substance prepared by working said substance in a plastic mass containing a thermoplastic cellulose derivative and a softening agent therefor, is extruded into a setting medium or solution. Preferably the base of the plastic mass is the same as that of the spinning solution which latter may be a viscose solution or cuprammonium solution or a solution of a cellulose ester or ether. The substance incorporated may be a delustrant, a coloured pigment, a weighting substance or a metal to give metallic effect (lists of suitable substances are given in the Specification). The amount of substance incorporated will vary according to the substance, and the effect desired, and may vary from 0,1 per cent to 40 per cent. A suitable method of preparing the finely divided substance is to mix the base of the plastic mass with a volatile solvent or a substance which is a solvent at an elevated temperature, add the required amount of solid substance and knead at an elevated temperature. Some solvent evaporates leaving a doughy mass which may be worked between malaxating rolls until the required state of subdivision is attained. During this operation the bulk of the solvent is evaporated leaving a relatively solid mass which may be broken up and dissolved as required into a spinning solution which may be spun by wet or dry spinning processes. The size of the particles of the incorporated substance is usually below 1 micron, and may be less than 0,2 microns. The fine state of subdivision enables a desired depth of colour to be obtained with a smaller amount of pigment than was hitherto necessary. In an example 1 part of cellulose acetate, 1 part of carbon black and 1 \ba1/2\be parts of acetone by weight are worked in a heated kneading machine to a stiff mass, which is then heated between closely spaced heated malaxating rolls until the mass is substantially free from acetone. The resulting sheet is broken into pieces and sufficient is added to a spinning solution containing 1 part by weight of cellulose acetate per three parts by weight of acetone to give a solution containing 0,03 parts of carbon black. Yarns produced from these spinning solutions may be woven or knitted into fabrics.