Effect of Acid Donors on the Dyeing of Nylon Fiber with Acid Milling Dyes

The effective control of pH in the dyeing of nylon fibers with acid milling dyes for high exhaustion and levelness can be accomplished by the gradual pH shift toward acidic region as dyeing proceeds. 1,3-Dichloropropan-2-ol and ethylene glycol diformate were chosen as new pH sliding agents in this study. Their dyeing properties and ability to control the dye bath pH were measured and compared with those of the conventional acid donors such as ammonium sulfate and sodium acetate-acetic acid buffer solution. The small amount of new pH sliding agents lowered the dye bath pH to 4, achieved the percentage exhaustion of more than 95 %, and showed an excellent build-up property. The gradual decrease in the pH of the dye bath containing new pH sliding agents from the start of the dyeing process to the final stage was confirmed. Difference in the levelness of the dyed samples was not observed among the four acid donors and grades of color fastness of the nylon fabrics dyed with various pH control system were found in the similar level.