Effects of Auxiliaries on Acid Dyeing of Shrink-Proofed Wool Fibers

The sorption behavior of an acid dye for shrink-proofed wool fibers, which were treated by means of three methods, Kroy, DCCA, and THPP (phosphorus compound) method, was investigated, to be compared with that of untreated fibers. The sorption isotherms for the wool fibers were determined and analyzed using dual sorption mechanism in order to calculate the sorption parameters, the number of binding sites for Langmuir type sorption, the intrinsic binding constant for Langmuir type sorption, and the partition coefficient. The number of binding sites for the wool fiber treated using Kroy method was lower than those for the other wool fibers in buffer solutions. Kroy treatment made the intrinsic binding constant lower in pH4 buffer solutions. Three cationic bolaform electrolytes were used as dyeing auxiliaries for the acid dyeing of the shrink-proofed wool fibers. Their effects were dependent on the structure of the bolaform electrolytes. In the case of the bolaform electrolyte containing hydroxyl and amino groups, the number of binding sites was increased, while the degree of the increase was different between two substituents. Furthermore, the addition of the bolaform electrolytes having hydroxyl groups made the partition coefficients higher. Such effects changed with different shrink-proofing methods.