GB1002377A - Process for the preparation of fast dyeings or prints on cellulose materials - Google Patents

Abstract

Materials of natural or regenerated cellulose are coloured by padding them with an aqueous alkaline solution of a coupling component, then dried and subsequently padded or printed with an aqueous acid solution or printing paste or pastes containing a reactive dyestuff and a diazonium compound and finally treating the materials with an aqueous alkaline solution. The reactive dyestuffs may be water-soluble and preferably contain the b -hydroxyethyl-sulphone-sulphuric acid ester group. The coupling components are preferably arylamides of aromatic or heterocyclic o-hydroxy-carboxylic acids or of acyl-acetic acids (many are specified). As diazonium compounds there may be used those which form water-insoluble mono-, dis-or polyazo dyes with the above coupling components including tetrazonium compounds of aromatic diamines. Since certain coupling components can react with the reactive dyes, a water-soluble aldehyde, e.g. formaldehyde, acetaldehyde or furfural, may be included in the acid solution or printing paste containing the reactive dyestuff to inhibit said reaction. The alkaline bath for the final treatment may contain sodium hydroxide or carbonate and large quantities of sodium sulphate or chloride; this treatment may be effected by padding, slop-padding or cover-printing with an alkaline salt solution or print paste followed by a passage through air at room or raised temperature, steaming at 100 DEG C., passing over heated drums or passing through alkaline salt baths at 50-100 DEG C. The diazonium compound and the reactive dyestuff may be applied from the same or separate printing pastes in either sequence, if desired covering each other. Examples of dyeing and printing fabrics of cotton and regenerated cellulose are given.