Structure–property relationships for azo disperse dyes on polyurethane fibre

Using two series of monoazo disperse dyes, the relationships between the molecular structure of dye and its dyeing properties, such as adsorption behaviour, fastness properties and distribution on polyurethane–polyester blends, were thoroughly investigated. Correlation analysis of experiment data revealed that the partition coefficient between octanol and water (CLogP) is the main factor affecting dye sorption. A greater level of CLogP tends to have a greater isotherm coefficient and better rubbing and washing fastness on polyurethane fibre, as well as a greater distribution ratio between the components of the blend. The dye dipole moment is negatively correlated with various degrees of washing fastness. The dye with two terminal hydroxy groups exhibited notable sorption on the polyurethane component and has the largest partition ratio on polyurethane–polyester in the blend. Corresponding regression analysis equations were identified.