GB403049A - A process for manufacturing coloured cellulose material - Google Patents

Abstract

Regenerated cellulose materials in the form of threads, ribbons, films, &c. such as are produced by the viscose and cuprammonium processes, are obtained directly in the dyed condition by adding to the viscose &c. solution an ester salt of a body yielding by acid oxidation a coloured compound, preferably an ester salt of a leuco vat dyestuff, the colour being developed by acid oxidation simultaneously with or subsequently to coagulation. As an alternative, the cellulose solution containing the undeveloped ester salt may be applied to a fabric, and the colour similarly developed during or after coagulation of the effect coating. In the case of cuprammonium solutions, coagulation and development of the colour may take place simultaneously under the influence of the cupric salt set free during the coagulation process; with viscose, the oxidising agent may be added to the coagulation bath, or an oxidising agent such as sodium nitrite which acts only in an acid medium, may be incorporated in the viscose. To obtain particular effects, threads may be made up of a number of filaments differently dyed or even undyed; the undeveloped colour may be superficially removed from a thick thread or film by treatment with water; and the printing-reserve-discharge process may be employed. The examples include processes for the production of coloured viscose and cuprammonium threads in which to the viscose &c. solution there is added a salt of the acid sulphuric ester of leuco-indigo, leuco-6 : 6<1> - diethoxyindizo, leuco - dimethoxydibenzanthrone, leuco - dibenzpyrenequinone, 3 : 3<1>-dichlor-1 : 2 : 2<1> : 1<1>-dianthronequinoneazine, 1 : 2 : 2<1> : 1<1> - dianthronequinoneazine, and of reduced b -aminoanthraquinone or a derivative thereof, and also of the dyestuffs from diazotised b - amino - 3 - chloranthrahydro - quinone - disulphuric acid ester and b -oxynaphthoic-acidanilide; the colour is either developed in the coagulation bath, or more usually in a subsequent bath, suitable oxidising agents being sodium nitrite, bichromate, copper sulphate and ferric chloride. Specifications 186,057, 203,681, 310,478, 312,404, [all in Class 15 (ii), Dyeing, Processes &c. for], and 383,741 are referred to.