Studies in disperse dye transfer mechanism in polyester–viscose union at elevated temperatures

The thermofixation process of dyeing polyethylene terephthalate–viscose union fabric with disperse dyes has been experimentally studied with a view to understanding the phenomena of dyeing polyester blends. It is shown how the distribution of a disperse dyestuff changes on the terylene and viscose portions of a union during different stages of dyeing by the thermofixation process. Equilibrium adsorption isotherm and rate curves of adsorption of disperse dyes on the polyester portion of the union have been determined. The nature of staining of the viscose portion of the union with different disperse dyes has been investigated. From the presented typical data it is possible to deduce fairly simple semiempirical rules regarding the phenomena of the thermofixation process of dyeing polyester–viscose union. It is pointed out that it is not possible to derive an exact thermodynamic theory to explain the data and describe the molecular mechanisms in such systems.