Dyeing polyester fibres with disperse dyes in supercritical CO2

The isothermal sorption of a series of thiadiazolyl azo dyes to be used as disperse dyes for polyester fibres has been carried out using supercritical CO2 as the dyeing medium. The experiments were recorded at temperatures from 80 to 120°C and pressures from 2500 to 4000 psi. The results obtained in supercritical CO2 were compared with those of traditional dyeing in water. The study showed that the disperse dyes used generally exhibited high substantivity towards PET fibres and excellent fastness and, that the extent of dye absorbed by the fibre in supercritical fluid, at 80°C and 3500 psi, was similar to that obtained in aqueous medium at 120°C in the presence of dispersing agents.