GB966488A - Improved dyeing process - Google Patents

Abstract

Fibres of polyolefins, e.g. stereoregular polypropylene, and of polyacetals, e.g. polyformaldehyde, containing compounds of polyvalent metals are dyed with a metallisable dyestuff which is devoid of -SO3H groups and treated with an aqueous solution of a sequestering agent. The specified polyvalent metals are Zn, Cu, Ni, Cr, Co, Mg, Al, Ca, Ti, Zr, Pr, Ce and La while the exemplified compounds are zinc, aluminium, nickel and magnesium stearate, chromium oleate, zinc nonanoate and calcium oxide. The metallisable dyestuffs may be of the anthraquinone, azo, formazan, azamethine or heterocyclic series; they may be water-insoluble or may carry water-solubilizing substituents such as -COOH groups or salts thereof provided that the complex formed between the dye and the metal in the fibre is water-insoluble. Of the suitable azo dyes specified some contain hydroxy, alkoxy, carboxy, carbalkoxy or amino groups in ortho-position to the azo linkage or a heterocyclic N atom adjacent to the azo linkage to form the metallising system whereas in others the azo linkage forms no part of the metallising system, e.g. in azo dyes from 8-hydroxyquinoline, 4-hydroxybenzthiazole, 4-hydroxyacridine, 7-hydroxyindazole, salicylaldoxime, and the like. Numerous dyes from all the above series are specified. The specified sequestering agents are sorbitol, pyrophosphates, triphosphates, oxalates, citrates, tartrates, gluconates, thioglycollates, aminotriacetic acid, hydroxyethylalkylenediaminetriacetic acid, diethylenetriaminepentaacetic acid and especially ethylenediaminetetraacetic acid and their water-soluble salts. The treatment with sequestering agent may be carried out at 50-150 DEG C. before, after or together with the dyeing. Preferably the fibre is first scoured with a bath also containing sequestering agent and the dyed from a dyebath containing sequestering agent. Examples are given. Specifications 935,125, 966,487 and 966,489 are referred to.