GB884143A - Improvements in or relating to x-ray detectable thread - Google Patents

Abstract

Viscose rayon yarn having incorporated therein more than 50% (by weight of the yarn) of an X-ray detectable material is produced by adding an aqueous dispersion of an X-ray detectable material containing viscose as a stabilizer, in an amount which constitutes more than 50% by weight, and preferably not more than 65% of the final weight of the yarn, to viscose subsequently to the main viscose filtration but prior to the spinning machine filtration. The diameter of the holes in the spinneret used may be over 100 microns and the particle diameter of the X-ray detectable material may be less than 5 microns. The material may be pure barium sulphate. The yarn may contain a coloured pigment in addition to the X-ray detectable material. In an example, 7,9 parts by weight of a 60% w/w barium sulphate aqueous dispersion stabilized by about 5% of an ethylene oxide condensation product is diluted with 2,1 parts of soft water and 2,1 parts of a filtered viscose containing 7,5% of cellulose, 7,0% of sodium hydroxide and 2,38% of combined sulphur, and the slurry so prepared is continuously added in the proportion required to the main stream of filtered viscose having the same composition. The mixture is homogenized and, after passage through swansdown spinning machine filters, is extruded through spinnerets having holes of 100 micron diameter into a spinning bath containing 9% of sulphuric acid, 4% of magnesium sulphate, 1% of zinc sulphate and 18% of sodium sulphate to give yarns containing over 50% and up to 64,2% of barium sulphate.