Energy-efficient dyeing of wool fabrics with sulfonic acid derivatives of aniline by oxidation polymerization

Traditionally, wool fibers are dyed with acid dyes at the boil, which is energy-intensive process, and increases the cost of dyeing. The development of alternative energy-efficient dyeing processes is quite attractive to the textile industry to make textile dyeing sustainable. In this work, the feasibility of low-temperature dyeing of wool fabric with several aniline sulfonic acid (ASA) derivatives by oxidative polymerization method was investigated. The effect of dyebath conditions, such as monomer concentration, monomer to oxidant ratio, pH, temperature, and time on the shade produced and color strength was systematically studied. The treatment with various ASAs produced various yellowish-brown color shades with tonal change. The treatment conditions had a great effect on color strength and colorfastness to washing. The optimum treatment conditions were found to be pH 3, 30 °C, and 60 min. The excellent colorfastness to washing exhibited by the ASA-treated fabrics (colorfastness grades from 4 to 4–5) showed that the developed method could be used for the coloration of wool and other polyamide fibers.