GB481854A - Improvements in dyeing cotton and artificial silk from regenerated cellulose - Google Patents

Abstract

Mordant dyes, dyeing with; regenerated celluloses, dyeing.-Cotton and artificial silk from regenerated cellulose are dyed by mordanting with a chrome mordant, consisting of a chromic chromate or mixture of a chromate and a chromic salt, and dyeing, with a mordant dyestuff, in the same bath. In order to avoid precipitations in the dye bath it may be necessary to add an alkali salt of an oxy carboxylic acid of the aliphatic series. The acid may be introduced as its chromic salt, for example chromic lactate or chromic tartrate. In examples: (1) viscose hanks are dyed a fast green in an aqueous bath containing the dyestuff, 4-nitraniline-2-sulphonic acid --> (acid) 1-amino-8-naphthol-3.6-disulphonic acid (alkaline) \sM 3-amino-4-sulphobenzene-azo-salicylic acid (cf. Specification 422,287), chromic chromate, (prepared by dissolving sodium bichromate and chromium chloride in water) and sodium chloride; the temperature of the bath is raised to 90 DEG C. and acetic acid is added towards the end of the process; (2) viscose artificial silk is dyed a vivid blue in a bath containing Erio-chromazurol S, chromic chromate, sodium tartrate and sodium chloride, acetic acid being added as in (1); (3) sodium chromate and chromic lactate are mixed together in the form of a powder to constitute the mordant, which is used to dye viscose hanks as in (1) a red-brown with p-amino-salicylic acid --> (acid) 2 - amino - 5 - naphthol - 7 - sulphonic acid (alkaline) \sM 1-amino-4-chlorobenzene-3-sulphonic acid; (4) cotton is dyed as in (3). The Specification as open to inspection under Sect. 91 comprises also an example of dyeing viscose hanks with the dyestuff described in example 1 of Specification 255,086, [Class 2 (iii)], with the use of the chromic chromate mordant. The use, in the dyebath, of sodium lactate and citrate is also referred to. This subject-matter does not appear in the Specification as accepted.