GB548490A - Improved process for stripping dyed textiles - Google Patents

Abstract

548,490. Stripping dyed textiles. LICHTENSTEIN, L. A. May 19, 1941, Nos. 6398 and 15389. [Class 15 (ii)] Dyed textile material is stripped by treatment with an aqueous solution containing a reducing agent and a water-soluble derivative of anthraquinone or of a substituted anthraquinone which on reduction yields the corresponding derivative of anthrahydroquinone. Specified reducing agents are glucose, molasses, sodium sulphide, formaldehyde, sulphite waste liquor, formaldehyde sulphoxylates and hydrosulphites. In examples, (1) a cotton fabric dyed with 4- nitroaniline # 2-naphthol, formed on the fibre, is stripped by a treatment for 15 minutes with an aqueous solution at 80‹C. containing glucose or sodium sulphide, sodium carbonate and sodium anthraquinone-2-sulphonate; (2) a cotton fabric, dyed with Artificial silk black GN, is stripped by a treatment for 15 minutes with a boiling aqueous solution containing Formosul and sodium anthraquinone-2-sulphonate ; (3) wool yarn, dyed with Croceine scarlet 3B, is stripped by a treatment for 15 minutes with an aqueous solution at 80‹C. containing glucose, sodium phenate or ammonia, and sodium anthraquinone-2-sulphonate ; an addition to the solution of a sodium alkylnaphthalenesulphonate is advantageous in preventing felting. Specifications 434,810, 436,076 and 437,884 are referred to. The first Provisional Specification refers also to the use of anthraquinone carboxylates as water-soluble anthraquinone derivatives and gives an example of the stripping of material dyed with the dyestuff, 5-chloro-2-aminotoluene # the 2<SP>1</SP>-toluidide of 2:3-hydroxynaphthoic acid, by a treatment for 10 minutes with an aqueous solution at 80‹C. containing glucose, soda and sodium anthraquinone-2-sulphonate.