| 摘要 |
1,243,549. Bleaching fabrics. E.I. DU PONT DE NEMOURS & CO. 20 Dec., 1968 [20 Dec., 1967], No. 60813/68. Heading D1P. A fabric portions of which are dyed with a sensitive dyestuff, e.g. naphthol, disperse, vat or copper phthalocyanine dyes, is bleached by treating it with an aqueous solution containing a peroxymonosulphate at a concentration sufficient to provide 0.005-1% by weight of active oxygen and a buffering agent which maintains the pH of the bleaching solution in the range 5-8.5. The peroxymonosulphate may be an alkali metal, ammonium or alkaline earth metal peroxymonosulphate and is preferably KHSO 4 KHSO 4 2KHSO 5 . The solution may be adjusted to the desired pH by the addition of sodium, potassium or ammonium hydroxide and may contain as buffering agent tetrasodium pyrophosphate, sodium bicarbonate or a mixture of borax and phosphoric acid or of tetrasodium pyrophosphate and sodium acetate. Bleaching may be effected at ordinary temperatures or at 100‹-212‹F for from 10 minutes to 5 hours. The fabric may be immersed in the bleaching solution maintained at the desired temperature or may be impregnated with bleaching solution in an amount of 50-150% by weight of the fabric and then heated with live steam or a mixture of steam and air. Prior to bleaching the fabric may be scoured with an aqueous solution containing tetrasodium pyrophosphate and soda ash. Fabrics comprising cotton fibres alone or in admixture with polyester fibres may be treated. |
