Abstract
The effects of ethylenediaminetetraacetic acid(EDTA)and ascorbic acid on the dye uptake of oxidative dyes for wool fibers dyed with the couple system of p-phenilenediamine/p-amino-o-cresol(pPDA/pAOC)and p-amino phenol/p-amino-o-cresol(pAP/pAOC)were investigated. The precursor/coupler dyeing solution with both EDTA and ascorbic acid maintains colorless during the dyeing period, indicating that the oxidative coupling reaction was inhibited by collaborative effects of both EDTA and ascorbic acid. When applied at pH10.0 in both pPDA/pAOC and pAP/pAOC dyeing system included EDTA and ascorbic acid, the amount of adsorbed oxidative dye in both dyeing systems was reduced compared with that when applied in the absence of both EDTA and ascorbic acid, although its effect depends on the concentration of hydrogen peroxide. In addition, when applied at pH8.0 in the presence of EDTA and ascorbic acid, a significantly lower level of adsorbed oxidative dye was produced, especially in the case of pPDA/pAOC dyeing system the uptake of bandrowski's bases that is self coupling dye of pPDA was suppressed. It is concluded that the ability of both additives to inhibit also serves at the interface between the dyeing solution and the fiber surface.
