Colouring linear polyesters

Linear polyesters are coloured by mixing them with a dyestuff of formula wherein D is a polycyclic dyestuff radical which consists of or includes a group of at least three condensed rings and which is free from sulphonic acid groups; Y is -NH- or -S-; R is hydroxyalkyl or hydroxyalkoxyalkyl; n is 1-3; m is 1-4; and the benzene ring A may be further substituted by chlorine or bromine atoms. The dyestuff is tumbled with the polyester in the form of chips or small granules, possibly in the presence of ethanol, betaethoxyethanol or water, and the mixture thereafter spun into fibres. In the dyestuff, the radical D may be an anthraquinone, 31: 41-phthaloylacridone, 11:91 - anthrapyridone or 11:91 - isothiazoloanthrone, radical. Preferred dyestuffs are those of formula or where T1, T2 and T3 are hydrogen atoms or a group of formula Examples describe the colouration of polyethylene terephthalate.