The solubility parameter concept applied to disperse dyeing of polymers

The solubility parameter concept offers a logical link between the theory of solutions and of nonionic (disperse) dyeing. An attempt has been made to apply the concept to correlate the solubility of several disperse dyes in secondary cellulose acetate, cellulose triacetate, and polypropylene with the calculated solubility parameters of both the polymers and the dyes. When the dyes are applied on hydrophilic polymers from an aqueous dispersion, the correlation between the solubility parameter concept and the dye solubility is not close. One of the reasons for this may be the fact that dyeing of the fibers is, in fact, not a solution in the dry fibers, but consists essentially either in displacement of water molecules from the water swollen fibers and/or, perhaps, in additional swelling by the dye. Consideration of this fact and also correcting for the contribution of hydrogen bonding and dipole interactions to the cohesive energy density brings the disperse dye solubility data into a better agreement with the concept. The concept should be applicable without complications to the dyeing of nonpreswollen fibers, such as polypropylene from aqueous dispersion, or any fiber by the Thermosol process and particularly to dyeing from the vapor phase. The few data available appear to support this view.