The Oxidative Polymerization Dyeing for Wool Fiber with p-Phenylenediamine/Resorcinol Dyeing System

The oxidative polymerization dyeing for wool fibers with pPDA/RC model solutions which formulated with the basic components of currently used cream-type oxidative hair dyes was investigated. The species of oxidized dye adsorbed within wool fibers dyed in pPDA/RC model solutions differ from the species in wool fibers dyed with solutions containing oxidative dyes generated by air oxidation in the pPDA/RC mixed solution, indicating that not all oxidative dyes produced in aqueous solutions are dyed. The ratio of oxidation dyes within wool fibers dyed in pPDA/RC model solutions varied slightly depending on the dyeing solution conditions, such as solution pH and pPDA/RC mixing ratio. In the case of the pPDA/RC (1:1) dyeing system, the dye species sorbed onto the fibers differs depending on the pH level of the dye bath. When dyed at pH 8, binuclear and trinuclear dyes, which are coupling dyes of pPDA and RC, adsorbs onto the fibers, whereas when dyed at pH 10, the absorption of trinuclear dye predominates and that of binuclear dye is not observed. These findings suggest that the trinuclear dye generated by the combination of pPDA and RC undergoes oxidative polymerization on the fiber surface and then penetrates into the fibers, unlike the mechanism of trinuclear dye formation in the pPDA alone system. Moreover, in dyeing systems where the mixture ratio of pPDA is higher than the mixture ratio of RC, it was found that the self-oxidative polymerization reaction of pPDA becomes predominant as the amount of pPDA increases and the binuclear and trinuclear dyes of pPDA coexist onto the fibers.