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Light Fading of Solubilized Vat Dyes on Nylon 66 Aftertreated with Hydroquinone

Quantitative measurements were made of the increase in lightfastness of solubilized vat dyes on nylon 66 aftertreated with hydroquinone. The increase is due to the anti- oxidant action of hydroquinone and not to ultraviolet absorption by this aftertreatment agent. The effect of aggregation was also studied, but in the case of two of the five dyes investigated, aggregation does not play any role in improving lightfastness, which is due to the anti-oxidant action of hydroquinone only. For other three dyes, both the factors contributed to improved lightfastness. Aftertreatment with hydroquinone caused changes in particle size distribution of these dyes on nylon 66.