Effects of molecular structure on dyeing performance and colour fastness of yellow dyestuffs applied to polypropylene fibres in supercritical carbon dioxide

Abstract

Thirteen dyestuffs of four chemical classes (quinophthalone, anthraquinone, isothiazole‐fused anthrone and pyridone azo) were applied for the dyeing of unmodified polypropylene fibres in supercritical carbon dioxide. From these 13 dyestuffs, three dyestuffs that have a pure yellow hue and good dyeability for polypropylene fibres were found. The results of a dyeability test using the 13 dyestuffs suggested that the affinity for polypropylene fibres requires, in the structural character of the dyestuff molecule, not only extreme hydrophobicity but also high aliphaticity. The isothiazole‐fused anthrone nonanamide dyestuff and two types of N‐butyl substituted pyridone azo dyestuffs were examined for build‐up and colour fastness properties. The light fastness of the dyed fabric was not so good. The ratings of fastness to washing, perspiration and rubbing ranged from excellent to fairly good with the increase of the depth of shade. From the relationship between the build‐up curve and the colour fastness, it was found that the dyestuff of the isothiazole‐fused anthrone nonanamide is suitable for polypropylene dyeing in a pale or medium shade, and that the two types of N‐butyl substituted pyridone azo dyestuffs are suitable in a deep shade.