GB189924938A - Improvements in, and relating to, the Manufacture of Colouring Matters. - Google Patents

Abstract

24,938. Lake, H. H., [Firm of K. Oehler]. Dec. 15. Dyes, artificial.-Polyazo dyes, which dye unmordanted cotton brown to black and greenishblack shades and resist the action of soap, are produced by combining diazo compounds in an alkaline solution with the monoazo dyes obtained from a diazotized amidonaphthol sulphonic acid and a sulphonic or carboxylic acid of a m-phenylenediamine or of m-toluylenediamine, the combination of the diazo compound being effected with the naphthalene nucleus of the said monoazo dye. When a diazotized p-diamine, such as benzidine, tolidine, or dianisidine is used, combination may be further effected with a second molecule of a monoazo dye or with a molecule of an amine, phenol, amidophenol, or a sulphonic or carboxylic acid thereof. An example is given in which tetrazotized benzidine, tolidine, or dianisidine is poured into an alkaline solution of the sodium salt of the azo dye prepared from amidonaphthol monosulphonic acid-G and toluylenediamine sulphonic acid, and the intermediate product thus formed is combined with the sodium salt of 2 :8-amidonaphthol sulphonic acid-G, or 2 :8-amidonaphthol disulphonic acid, or 2-amido- 5-naphthol-7-sulphonic acid. In another example, the tetrazotized p-diamine is combined with two molecular proportions of the monoazo dye. The new dyes give a pure white discharge with bisulphite and zinc dust or with stannous chloride. They may also be diazotized in substance or upon the fibre, or combined with diazo compounds, thus yielding very full and heavy dark shades of a fast character.