GB439802A - Improvements in the process of bleaching textile materials - Google Patents

Abstract

Textile materials are bleached by a non-alkaline liquor containing hydrogen peroxide or a compound, such as a percarbonate or perphosphate, yielding hydrogen peroxide in aqueous solution, the liquor being fully inactivated by the addition of an inactivator other than sulphuric, nitric or hydrochloric acid, with application to the materials, before their introduction into the liquor of an activator which is retained by the goods without substantial diffusion into the liquor. the inactivator and the activator are both free from metal of atomic weight above 45. The textiles may be of animal fibres such as hair or wool or of vegetable fibres such as jute. Specified inactivators are phosphates, borates, oxalates, lactates, isobutylnaphthalenesulphonic acid and oleylmethylaminoethanesulphonic acid and glue is specified as an auxiliary inactivator. Specified activators are enzymes, ferments and soap. The goods containing the activator may be subjected to a short wetting with the bleaching liquor, e.g. by immersion, sprinkling or brushing, and the bleaching completed by storing in a moist state or by applying heat. Bleaching may be effected first by a weak and later by one or more stronger solutions and the textile material and the bleaching liquor are preferably moved in opposite directions during the treatment. The following examples are specified: (1) Animal hair, e.g. Angora goats' hair or sheep's wool is washed with soap and water, rinsed so that it retains about 1 per cent of soap, worked into tops which are placed for 2 minutes in an aqueous bath at 40 DEG C. containing hydrogen peroxide and oxalic acid with or without an oxalate, hydroextracted or squeezed and dried. (2) Wool in the form of tops is placed for 30 minutes at room temperature in a solution of potassium permanganate slightly acidified by sulphuric acid or with an addition of magnesium sulphate; the wool, thus stained brown and made slightly alkaline, is rinsed while retaining alkalinity and placed for 2 minutes in a bath at 30--40 DEG C. containing hydrogen peroxide, sulphuric acid and sodium oxalate and, still retaining alkalinity, is placed for 10--30 minutes in a similar bath containing hydrogen peroxide and oxalic acid; it is then rinsed, cleared in a solution containing sodium bisulphite and sulphuric acid, and, if bleaching to a pure white is desired, is further treated for 3--6 hours in a solution of sodium hydrosulphite at 35--45 DEG C. and finally rinsed and acidified; softness in the bleached material may be attained by adding a protective colloid, e.g. glue or tanning matter, to the bleach liquor and its feel may be improved by a preliminary treatment with an aldehyde, e.g. formaldehyde or acetaldehyde or by adding such to the bleach liquor. Specification 404,019 is referred to.