GB873554A - Process of preparing an aqueous oxidising solution containing alkali and alkaline earth chlorite - Google Patents

Abstract

Foreign substances intimately associated with natural or regenerated cellulose textile fibres, e.g. cotton and regenerated cellulose staple fibre, or with synthetic fibres, e.g. polyamides, are oxidized by a process comprising preparing an aqueous solution of an alkali or alkaline-earth metal chlorite, adding thereto monoethanolamine or a salt thereof, di-ethanolamine or a salt thereof, or triethanolamine or a salt thereof, or mixtures of any of these, or a compound capable of decomposing by hydrolysis to give an ethanolamine, the pH of the solution initially being 7-8,5, impregnating the fibres with this solution at a temperature of 20-50 DEG C., adjusting the moisture content of the fibres to 50-120% of their dry weight and then exposing them to a temperature of 70-100 DEG C. for such a period that the entire process occupies 1-3 hours. The foreign substances associated with the fibres may be natural pigments or impurities or dyes sensitive to chlorites, the oxidizing solution then acting as a bleaching bath, or the foreign substances may be Indigosol dyes, in which case the oxidizing solution acts as a development bath for dyeing purposes, the dye being added to the chlorite solution before adding the ethanolamine compound thereto. The solution preferably contains 5-30 g.p.l. of chlorite and 1-6,6 g.p.l. of a salt of an ethanolamine, the initial temperature being 40 DEG -50 DEG C. Specified ethanolamines are diethanolamine and its hydrochloride, triethanolamine, its hydrochloride and its salts with formic and fluorosilicic acids, the monophthalic acid ester of triethanolamine and the diacetate of diethanolamine.