Correlation of solubility data of azo disperse dyes with the dye uptake of poly(ethylene terephthalate) fibres in supercritical carbon dioxide

Solubility data of disperse azo dyes in supercritical carbon dioxide are presented for dyeings of poly(ethylene terephthalate) fibres with CI Disperse Red 167:1, carried out at 200–300 bar and 80–120 °C, with varying amounts of adulterants. The same dyeings were also carried out in water for comparison. Scanning electron micrographs were taken of the dyes which show a growth of dye crystals during treatment in supercritical carbon dioxide. The paper reports that at 120 °C, melting of the pure dye CI Disperse Red 167:1 is observed. The presence of adulterants in the dye formulations help prevent agglomeration by acting as spacers between the dye molecules. Dyeings of PETP carried out under conditions of the highest solubility of the dye in supercritical carbon dioxide do not necessarily result in a very high dye uptake. This was shown by pressure‐ and temperature‐dependent dyeing experiments of PETP in supercritical carbon dioxide.