GB959859A - Improvements in the bleaching of textiles - Google Patents

Abstract

959,859. Bleaching cellulosic materials. OLIN MATHIESON CHEMICAL CORPORATION. May 8, 1962 [May 16,1961], No. 17626/62. Headings D1L and D1P. Cellulosic textile materials, e.g. cotton, linen, jute, hemp and regenerated cellulose fibres alone or in admixture with nylon, synthetic polyester or polyacrylonitrile fibres, are bleached by impregnating them with an aqueous solution containing sodium chlorite maintained at a pH of 3-4, heating them in the long arm of a curved shoot having the shape of the letter J in the lower curved portion of which water is circulated at a temperature of from room temperature to 165‹F., passing them through the water and withdrawing them from the short arm of the shoot. The textile material 1 which may previously have been desized, mercerized, impregnated with caustic soda, steamed, washed, impregnated with an acid, e.g. dilute hydrochloric acid, heated and washed until it contains 0.05-0.15% by weight of residual acid, is passed into a saturator 3 which preferably contains 2-15 grams per litre of sodium chlorite, more than 1 mole of sodium nitrate per mole of sodium chlorite and 0.1-1% by weight of a wetting agent, e.g. a salt of an acylalkyl tauride, sulphated alcohol or alkyl aryl sulphonate, at a temperature of room temperature to 120‹F. and is maintained at a pH of 3-4 by the addition of caustic soda or phosphoric, hydrochloric or sulphuric acid. It is then squeezed to a liquor pick-up of 30-120% by rolls 8 and 9 and passed to S-shoot 12, the long vertical arm 13 of which is heated to 180‹-212‹F.by means of a steam jacket and the lower curved portion 14 of which contains water 15 introduced through inlet 16 and withdrawn via standpipe 17. The textile material is preferably kept in the long arm for 15-120 minutes and in the water for 10-30 minutes and is then withdrawn through the opening 19 and the top of the short vertical arm 18.