Abstract: A process is disclosed for dyeing a textile substrate, in particular for dyeing polyester yarns. The substrate to be dyed is placed in an autoclave and a supercritical fluid containing at least one dyestuff is applied to it, i.e. passed through it. The supercritical fluid is pumped continuously via a circulation system allocated to the autoclave, and, in order to terminate the dyeing process, the pressure and/or temperature is lowered and/or the volume is increased. Immediately before and/or during the pressure and/or temperature reduction and/or volume increase, as much as possible of any residual dye which has not been transferred to the substrate is removed from the fluid.

Abstract: The description relates to a process for dyeing a textile substrate in at least one supercritical fluid, preferably for dyeing spools of yarn in supercritical carbon dioxide, where the textile substrate is placed in an autoclave in which the supercritical fluid containing at least one dye is caused to flow over or in it. The at least one dye is brought into contact with the supercritical fluid in loose, molten, solution and/or dispersion form to produce a stable solution of the dye in said fluid, avoiding the originally dissolved dye's deposition from the solution or the formation of dye agglomerates therein having a particle size of over 30 .mu.m and advantageously over 15 .mu.m.

Abstract: A method for the dyeing of a textile substrate, particularly for the dyeing of a polyester yarn wound upon a bobbin, is described, in which the textile substrate to be dyed is arranged within an autoclave and superfused, respectively perfused, with a supercritical fluid containing at least one dye, whereby an auxiliary fluid is loaded with the at least one dye, whereby the auxiliary fluid in brought into contact with the supercritical fluid and whereby hereafter the textile substrate is perfused, respectively superfused, with the supercritical fluid containing the at least one dye.