GB230029A - - Google Patents

Abstract

In developing ice colours with diazo solutions which are neutral or alkaline with sodium carbonate there is added to the said solution a substance which will destroy the caustic alkali present in the padded material without acidifying the bath; such a substance is an alkali bicarbonate or a suitable metal salt or the two together; decomposition of the diazo bath is thus diminished, especially in continuous dyeing or when using tetrazo compounds. According to examples the following shades are produced on cotton (1) bluish red by padding with an alkaline solution of 2 : 3-oxynaphthoic-p-chloranilide and developing with diazotized m-xylidine containing sodium bicarbonate; (2) black by padding with 2 : 3-oxynaphthoic anilide and developing with tetrazotized 4 : 41-diaminodiphenylamine neutralized with chalk and to which magnesium sulphate is added; (3) dark blue by padding with 2 : 3-oxynaphthoic-a -naphthalide and developing with tetrazotized dianisidine neutralized with chalk and to which sodium bicarbonate and zinc chloride are added; the tetrazo solution in the latter case is made up to strength after development of each bath of cotton.