GB656507A - Textile dyeing - Google Patents

Abstract

Textile fibres are treated with an aqueous solution of a water-soluble organic dyestuff containing a nitro group in an aromatic nucleus and the dyestuff is then reduced on the fibre to convert the nitro group into an azoxy group, e.g. by means of a hot alkaline solution of a reducing sugar or an arsenite. The original dyestuff may be an azo dyestuff or a dyestuff of the anthraquinone series containing a nitro group. If the azoxy dyestuff on the fibre contains an aromatic amino group, it may be diazotized and coupled with a suitable coupling component; similarly, if the azoxy dyestuff can act as a coupling component it may be coupled on the fibre with a diazotized aromatic amine. Other aftertreatments, e.g. treatment with an aldehyde or a metal salt, may also be applied. In example (1), cotton yarn is immersed in a solution containing the dyestuff 4-nitroaniline-2-sulphonic acid -->2 - amino - 8 - naphthol - 6 - sulphonic acid and also sodium carbonate, heated to 70 DEG C. and an aqueous solution of glucose then added. In other examples, the dyestuff is replaced by (2) p - nitroaniline-->2 - benzoylamido - 5-naphthol-7-sulphonic acid; (3) aniline-->2-p-nitrobenzoylamino - 5 - naphthol - 7 - sulphonic acid; (4) p-nitroaniline-->silicylic acid; (5) 4 - nitroaniline - 2 - sulphonic acid-->cresidine and (6) p-nitroaniline-->cresidine. The resulting dyestuff of (5) can be diazotized on the fibre and coupled with b -naphthol.