GB923897A - Improvements in or relating to the bleaching of cellulosic fibres - Google Patents

Abstract

Copper-contaminated cellulosic fibres, i.e. natural cellulose fibres, e.g. cotton, regenerated cellulose and cellulose derivatives, which may be scoured or unscoured, alone or in admixture with other natural fibres, e.g. wool, and/or synthetic fibres, e.g. nylon, which may also be scoured or unscoured, are bleached by contacting them with an alkaline aqueous hydrogen peroxide bleaching solution containing a water-soluble or water-solubilized protein or polypeptide and a silicate of an alkali metal. Suitable water-soluble or water-solubilized proteins and polypeptides which are preferably used in a concentration of 1-4 gm./litre, are glue, gelatin, egg albumen, solubilized keratin obtained, for example, from animal hooves, feathers or waste wool dissolved with caustic soda or peracetic acid, globular proteins, e.g. the dried blood of animals, collagen and gluten from wheat flour. The solution may also contain a water-soluble salt of an alkaline-earth metal or of magnesium. The concentration of the hydrogen peroxide is preferably 1-15 vol. and the ratio of bleach solution:goods is preferably 1:1 to 30:1. The concentration of silicon dioxide in the solution is preferably 0,5-5,0 gm./litre and the ratio alkali-metal oxide:silicon dioxide in the range 0,5:1 to 5,0:1. Prior to bleaching the fibres may be treated with an aqueous solution of a per-acid, e.g. Caro's acid, at a temperature up to 80 DEG C., scoured at an elevated temperature for several hours in an alkaline solution, treated with a steeping agent consisting of a dilute solution of a mineral acid, e.g. sulphuric acid, are treated as described in Specification 923,896.