Novel process to enhance the dyeability of cotton in supercritical carbon dioxide

A new simple method to improve the dyeability of cotton in supercritical carbon dioxide, which does not require any chemical modification of the cotton, is described here. The affinity of the cotton is enhanced through physical interactions between the pretreatment solvent and the cotton structure. Addition of cosolvents and dissolution of the dye greatly improved the coloration and fixation of the cotton. Experiments with different solvents as pretreatment and as cosolvents were performed. Methanol was found to be the best solvent for the pretreatment. Dimethylsulfoxide (DMSO) as cosolvent and dye carrier provided the highest cotton coloration (K/S 15.3), but a fixation of only 2%. An increase in fixation to 62% was achieved when methanol was the cosolvent and the dye carrier.