Abstract:

We have examined the photo-stability of acid dyes, derivatives of 1-phenyl-3-methylpyrazol-5-one, in polyamide fibres, including the relationship between the dye’s structure and photo-stability. The part played by the substituents in diazo components was assessed, especially those in ortho positions to azo bonds. It has been found that the photo-destruction of dyes in polyamide fibres proceeds according to the mechanism of photo-oxidation. The light fastness of dyeings depends on the electron density of the azo bond (reaction centre). Some substituents in ortho positions to the azo bond increase the dye’s photo-stability.