1983 Volume 24 Issue 10 Pages 446-451
It has been found that the tensile strength of the cloths dyed with metal complex dyes often decreases with the repeated bleaching. In this paper, using some chelating agents (EDTA, NTA, IDA, etc.), an attempt was made to prevent this degradation by blocking the metal in dyes, resulting in the decrease of the catalytic decomposition rate of bleaching agent (sodium percarbonate) . The results were summarized as follows:
(1) When sodium percarbonate was added to the solution of metal complex dyes pretreated with these chelating agents, the decolouring of this solution was little observed. But if the solution of the dyes did not treated with these agents, remarkable decolouring was observed.
(2) When the dyed cloths were pretreated with these chelating agents and repeatedly bleached by sodium percarbonate, the tensile strength of he cloths hardly decreased.
(3) Colour difference (ΔE) of the dyed cloths treated with EDTA increased with repeated bleaching, whereas, in the case of IDA, 4E was little observed.
Considering these experimental results, it was shown that IDA was most effective chelating agents to prevent the degradation of the dyed cloths.
