Use of an ester of a hydroxycarboxylic acid and a glycol for dyeing polyamide fibres, optionally with a non-volatile tertiary amine, and a dyeing assistant

摘要

A process of dyeing natural or synthetic polyamide fibres in an aqueous exhaustion dyebath comprising an anionic dyestuff, comprising the steps of 1. immersing the fibres to be dyed in the aqueous dyebath which has a temperature of from 20 - 50{C and a pH of 7 - 11 (7- 8.5 when the polyamide is wool); and 2. raising the temperature to a temperature not exceeding 110{C and maintaining it there until exhaustion is substantially complete; there being added to the dyebath, either prior to the commencement of temperature raising or after an alkaline migration period at the boil, an ester of a C 2 - C 3 hydroxycarboxylic acid with a C 2 -C 6 glycol and 0-30% (by weight of the ester) of a tertiary amine which is essentially non-volatile under the process conditions. The esters/tertiary amine mixture in the weight ratio of 70:30 to 95:5 is claimed as a dyeing assistant and allows good exhaustion and level dyeing by causing the pH to fall by an appropriate amount and an appropriate rate. The preferred mixture is ethylene glycol diglycolate and triethanolamine.