GB499873A - Improvements in or relating to the treatment of textiles - Google Patents

Abstract

In bleaching cellulosic materials by the process described in the parent Specification the alkaline solution of an oxidizing bleaching agent is a solution containing hydrogen peroxide and sodium carbonate. Such a solution may be obtained, for example, by dissolving together in cold, and preferably hard, water sodium peroxide and sodium bicarbonate. The goods may also be scoured with a liquor containing hydrogen peroxide and sodium carbonate prior to the treatment with the buffered hypochlorite solution and the solution used on a previous batch of material in the alkaline peroxide bleaching step may be used for this purpose after suitable adjustment of its alkali and/or peroxide content. In examples: (1) linen yarn is scoured for 3 hours with a soda ash solution at 65 DEG C., washed, treated in subdued light for 1/2 hour on a reeling machine with a solution at 15 DEG C. of a hypochlorite solution buffered with sodium bicarbonate to pH= 6,5, rinsed, soured with dilute hydrochloric acid, washed, entered into a bath at 35 DEG C. containing sodium peroxide, sodium bicarbonate and sodium silicate with heating to 65 DEG C. during 1/2 hour and continuing at this temperature for 2 1/2 hours, washed and dried to obtain a good half-white bleach; (2) linen yarn is scoured for 2 1/2 hours with a liquor at 65 DEG C. comprising the used peroxide liquor of (1) with an addition of soda ash, washed, treated as in (1) with a buffered hypochlorite solution containing less available chlorine than in (1), rinsed, soured, treated as in (1) with the peroxide bleaching solution, washed, treated for 1/2 hour with another buffered hypochlorite solution containing still less available chlorine, again treated in a similar but weaker peroxide solution, washed, treated again in a still weaker buffered hypochlorite solution, washed and dried to obtain a full white bleach.