Investigation of mordant application in reactive dyeing of nylon fabrics

Abstract

Nylon fibers were the first synthetic fibers to be produced on an industrial scale, and they are one of the most consumed synthetic fibers due to their visual and usage properties. Reactive dyes have been commercially produced since the mid-20th century, and they are mostly preferred in dyeing cellulosic fibers. The most important property of reactive dyes is their ability to make covalent bonds within the fiber. Mordants are used mainly in the application of natural dyes to hold and retain the dye molecules in the fiber. In this paper, nylon fabrics were dyed with three reactive dyes having different reactive groups (monochlorotiazine, trifluoropyrimidine and monochlorotriazine/vinylsulfone) in the presence of three chemical mordants (iron (II) sulfate, potassium aluminum sulfate and tannic acid) to obtain better exhaustion and coloration properties. Pre-mordanting, meta-mordanting, and post-mordanting processes were used for dyeing. The dyeings were performed at two dyeing concentrations (0.5% and 2% owf), and at three pH levels (pH 2, 4, and 6). The percentage of dyebath exhaustion (%E), the percentage fixation of the dye which exhausted (%F) and the overall percentage fixation (%T) were calculated after pyridine extraction. Wash and light fastness tests were applied on the dyed samples. The results were discussed via %E, %T and CIELAB color differences (Delta E-ab*). The results revealed that mordant usage improved the coloration properties of reactive dyes on nylon fabrics. The %E and %T results changed according to the independent variations of pH level, mordant chemical and mordanting method. The correct pH level and mordanting method gave the best dyeing and fastness results for the dyes under test.