FADING OF VINYLSULFONYL REACTIVE DYES ON CELLULOSE IN ADMIXTURE UNDER WET CONDITIONS

The fading of vinylsulfonyl(VS) reactive dyes on cellulose in a binary mixture was investigated under wet conditions. Dyes with a high photosensitivity such as Rose Bengal, a copper phthalocyanine, C.I. Reactive Red 22 and Black 5, gave a positive concentration dependence on the fading of the partner dye or of its own, when the partner or itself was easily oxidized. A preferential surface fading model for reactive dyes on cellulose in a mixture is proposed to explain the fading behavior under wet conditions and the model was experimentally confirmed by the variation in the concentration profiles during the fading for both dyes on film dyed in admixture. A dye which underwent fading more readily when it was oxidized showed accelerated fading when present in a mixture with a dye having high fading sensitivity, compared with the fading of the single dyeing at the same concentration. A dye which faded with moderate ease, when present in a mixture with a dye which faded less readily, showed decreased fading. © 1990.