Shrinkproofing and feltproofing with acid bromate wetting agent solution

摘要

Wool is rendered shrinkproof and feltproof and may be bleached by impregnating it with an aqueous bromate liquor containing a wetting agent, freeing it from excess impregnating liquor by squeezing so that it has a liquor pick-up of 30-130% by weight, calculated on the air-dry wool, and successively treating it with an acid at a temperature of at least 25 DEG C., an aqueous solution of a reducing agent and an alkaline neutralizing agent. The bromate may be an alkali or alkaline earth metal bromate, e.g. an aqueous solution containing 20-80 g. per litre of potassium bromate, and the bromate solution may contain at least one alkali or alkaline earth metal chloride. The acid which may be inorganic, e.g. hydrochloric, sulphuric and perchloric acids, or organic acid may be applied by immersing the wool in the acid, by spraying the acid on to the wool which may be warmed by means of infra red lamps or in the case of volatile acids, e.g. gaseous HCl, by exposing the impregnated wool to the gaseous or vaporous acid. The reduction is preferably carried out at 30 DEG -50 DEG C. with dilute aqueous solutions containing 0,-1% by weight of the reducing agent, e.g. alkali metal sulphites, bisulphites, thiosulphates and hydrosulphites, and the wool is then neutralized with, for example, dilute aqueous ammonia or a dilute aqueous solution of an alkali metal carbonate or bicarbonate. The handle of the wool may be modified by after treating it with an aqueous soap solution at 30 DEG -50 DEG C. and the wool may subsequently be dyed. Any bromine produced during the acid treatment of the wool may be removed by bubbling a stream of air through the acid bath or by recirculating the acid bath through a column in countercurrent with a stream of air. The wool may be in the form of tops or loose fibres, yarns or woven or knitted fabrics, blankets or felts, alone or in admixture with natural, artificial or synthetic fibres, e.g. cotton, viscose rayon, polyamide, polyester and polyacrylic fibres. Specifications 614,271 and 798,236 are referred to.