| 摘要: | This article reports the results of a study of nylon 6 fiber dyed in a low-temperature hydrogen peroxide-glyoxal redox system. It was expected that the dyed fiber would have better dye fastness and higher economic value than would conventional fiber. In addition, this article presents the proposed mechanism for and model of a free-radical dyeing system as well as a derived theoretical equation. From the experimental results, it was found that formation of covalent bonds by the coupling of the dye and the fiber radical in free-radical dyeing was only 25%-40%, whereas with the conventional type of ionic dyeing, it was almost 60%-75%. Because the initiation efficiency of free-radical formation is affected by many factors, such as the pH of the dye bath and the concentrations of the oxidant and reductant, the aims Of this Study were to investigate the formation of free radicals and the effects on dye uptake of the concentrations of dye, oxidant, and reductant and of the fiber amine end group. In addition, the dyeing properties of dyed fiber were investigated, and the dyeing order and rate constant of the rate equation were evaluated from the experimental data. From the experimental results, the following conclusions were drawn. (1) The hydrogen peroxide-glyoxal redox system produced many free radicals in the dye bath as temperature reached 70 degrees C. (2) The amine end group in the nylon fiber was the main site of ionic and covalent bonding between nylon 6 fiber and dye. (3) The proposed model of free-radical dyeing showed, from the fit of the experimental data into the equation and the evaluation of the equation parameters, that the order fit the theoretical value well, with the rate constant dependent on the dyeing conditions; at pH = 3, it could match the equation's best (rate equation of the proposed model: d[D](R)/dt = k(A)[GO](1)[H2O](m)[D](1/2)[F](1/2)). (4) The optimum dyeing conditions in the hydrogen peroxide-glyoxal redox system were: [H2O2] = 0.15-0.20M, [glyoxal] = 0.07-0.10M, pH = 3, dyeing temperature = 70 degrees C, and dyeing time = 45-50 min. (5) The redox dyeing system had better dye fastness than did the conventional system. (c) 2006 Wiley Periodicals, Inc. |
