GB708144A - Process for dyeing cellulose fibres with direct-dyeing azo-dyestuffs containing copper or nickel in complex union - Google Patents

Abstract

Cellulose fibres are dyed with direct-dyeing azodyestuffs containing copper or nickel in complex union, in the presence of an aliphatic amine having at least 2 nitrogen atoms each bound to 2 carbon atoms and having at least 2 hydroxyl groups, e.g., amines of the general formula <FORM:0708144/IV(c)/1> in which R1 is hydrogen or an alkyl group having at the most three carbon atoms or a hydroxymethyl group, R2 is hydrogen or a methyl group, and n is a whole number at the most 4 but preferably 2. The amine has a strong restraining action on the dyestuff and equilibrium is attained very rapidly, and at any given amine concentration, quantity of dyestuff and quantity of material to be dyed, the restraining action is constant and independent of the liquor ratio. Aldehydes may be added, if necessary, to restrain the action of the amines. Unlevel dyeings or too strong dyeings which have been produced with cupriferous dyeings by the customary processes may be treated in a bath containing the amine to remove the excess or a greater part of the dyestuff, after which formaldehyde may be added to restrain the action of the amine and the dyeing repeated, if desired, using the dyestuff that is present in the bath. The maximum action of the amine is usually obtained at a concentration of 3 grams per litre. In Example (1), cotton is dyed in a bath containing sodium sulphate, 1, 2-di (b -oxyethylamino)-ethane and the copper compound of the dyestuff obtained from diazotized 2-amino-1-oxybenzene-4-sulphonic acid amide and 5, 5\sv-dioxy-2, 2\sv-dinaphthylamine-7, 7\sv-disulphonic acid, and formaldehyde is then added in several portions. By omitting the formaldehyde a weaker dyeing is obtained but several successive and equal dyeings may be made in the same bath. Several alternative dyestuffs are specified, and a table is given showing how the strength of the dyeing depends on the concentration of the amine. In Example (2), cotton dyed with the copper complex of the disazo dyestuff from diazotized 2-amino-1-oxybenzene-4-sulphonic acid and 5, 5\sv-dioxy-2, 2\sv-dinaphthylurea-7, 7\sv-disulphonic acid is entered into a bath of 1, 2-di-(b -oxyethylamino)-ethane at the boil whereby the dyestuff is practically completely removed; on adding formaldehyde to the bath, the dyestuff is again taken up by the fibre. In Example (3), cotton is dyed in a bath containing the nickel complex of a dyestuff having the formula <FORM:0708144/IV(c)/2> sodium sulphate and 1, 2-di-(b -hydroxyethylamino)-ethane at the boil, followed by the addition of formaldehyde. Specification 676,584 is referred to.