The Development of Dyes and Methods for Dyeing Polyester

Abstract

Early work on the dyeing of polyester fibre showed that only dyes of very low aqueous solubility had substantivity for the fibre, and that for dyeing at the boil without a carrier only the smallest molecular weight disperse dyes, and selected azoic combinations, had sufficiently high dyeing rate to give adequate colour yield in a practicable time of dyeing. The development of carriers for dyeing at the boil, and of machinery for batchwise dyeing under pressure at temperatues up to 140°C, extended the range of suitable dyes to those of lower dyeing rate but higher heat–fastness properties. As an alternative to exhaust dyeing, polyester may be dyed with disperse dyes by padding followed by dry heat fixation at temperatures up to 220°C, and this method has found its main commercial application in the continuous dyeing of polyester–cellulosic blend fabrics.The development of new disperse dyes has followed these trends in application methods, and the proportion of available dyes having higher heat–fastness properties has steadily increased from about 1950 onwards. Improvements have also taken place over the same period in the physical properties of the dyes, to meet the increasingly severe demands on dispersion properties imposed by the newer dyeing methods.