CATALYTIC FADING OF VINYLSULFONYL REACTIVE DYE MIXTURES ON CELLULOSE UNDER WET CONDITIONS

Vinylsulfonyl reactive dyes on cellulose, present as a mixture of an aminopyrazolinyl azo yellow dye (1) and a phthalocyanine blue dye (2) showed marked catalytic fading of dye 1 under wet conditions, but only a slight fading under dry conditions. The fading was almost completely suppressed in the absence of oxygen and considerably by the addition of the singlet oxygen quencher 1,4-diazabicyclo[2.2.2]octane. Dye 1 on cellophane showed catalytic fading by adsorbing Rose Bengal on the film under wet conditions. The photosensitized fading of dye 1 on cellophane dyed in a mixture was proved by exposing only dye 2 or Rose Bengal to light of wavelength above 520 nm, and was also confirmed to be due to the singlet oxygen mechanism by diagnostic tests. The phenyl groups of dye 1 were not split off from the substrate during the fading of the dye. © 1990.