GB806536A - Continuous bleaching of cellulosic textile materials - Google Patents

Abstract

A continuous process for bleaching cellulosic textile materials comprises the stages, preferably carried out at open width, of (1) passing the materials through trichloroethylene or perchloroethylene and subsequently removing entrained solvent by passing them through hot water; (2) passing the materials through an aqueous hypochlorite solution at a pH of less than 5.5 and temperature below 35 DEG C., the amount of available chlorine being in the range 0.5 to 15 g./l., preferably followed by rinsing in water; and (3) passing the materials through an aqueous solution of a peroxygen compound at a pH of at least 10, and subsequently steaming. The term "hypochlorite solution" includes acidified solutions of sodium hypochlorite, solutions of hypochlorous acid, solutions of chlorine gas in water, with or without buffers, the product of the action of water on chlorine monoxide and solutions of the hydrolysis products of nitrogen trichloride or chlorohydantoin. The organic solvent may be at a temperature of 80 DEG to 87 DEG C. and may be in a series of baths through which it is circulated in a counter direction to the travel of the cloth, which leaves the baths through nip rollers and passes into the flash-off bath, which is at over 73 DEG C. when trichloroethylene is the solvent and at over 86 DEG C. when perchloroethylene is the solvent. The peroxygen compound may be sodium peroxide, sodium percarbonate, sodium perborate or hydrogen peroxide and the aqueous solution thereof may also contain sodium silicate and a neutral or anionic wetting agent. The treatment of cotton and rayon is described. Specifications 747,481 and 803,796 are referred to.