A STUDY OF THE KINETICS OF COLD PAD BATCH DYEING WITH FIBER REACTIVE DYES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

The kinetics of cold pad batch dyeing cotton fabric with fiber reactive dye was studied under the constraints of the commercial dyeing process. The dichlorotriazinyl dye, C.I. Reactive Red 2, was purified from commercial product and characterized. The reactivity of the dye was found in terms of chloride release during dye hydrolysis, as measured by a solid-state chloride ion electrode. The substantivity of both commercial, and purified samples of this dye was evaluated in the pad batch system to assess the true (versus macro) character of the rate constants.; An ion pair HPLC procedure was developed and used to separate and quantitate the dye forms present during dyeing experiments. A laboratory procedure was developed which allowed dye samples to be extracted from the fiber at various times during the batching step.; Rate constants were determined for the pseudo first order, and second order dye hydrolysis and fixation reactions during the first eight minutes of fiber reactive dyeing under various conditions, to evaluate the effect of the dye to alkali ratio, and the amount of salt in the pad batch. During this time about three quarters of the dye was bound to the fiber.; Pseudo first order, and second order hydrolysis constants were consistent with reported values for batch dyeing systems. Rate constants for hydrolysis of dye in solution and in the fiber were about the same, as were the second order constants for hydrolysis and fixation reactions within the fiber phase. The rate of hydrolysis of dye-fiber bonds was found to be negligible during the first eight minutes of dyeing. Substantivity studies showed that during the first minute of dyeing, at least 50% of dye applied was substantively held by the fiber.