Novel Monosulfonated Azo Dyes: Design, Synthesis, and Application as Disperse Dyes on Polyester Fabrics

This study synthesizes and characterizes a series of disperse dyes based on azo Schiff bases, compounds 8–10. Their structures were identified using various analytical techniques, such as FT-IR, ¹H/¹³C NMR, and mass spectrometry. The study’s primary objective was to investigate the behavior of disperse dyes 8–10 when used for dyeing polyester fabrics under different conditions, including variations in time, temperature, shade, and pH. The polyester fabric was chosen for this research due to its wide usage and popularity in the textile industry. By examining the effect of temperature and time on the dyeing process, it was observed that increasing the dyeing temperature from low to high (ranging from 90 to 120 °C) and extending the dyeing time from 10 to 30 min resulted in higher K/S values for the polyester samples dyed with disperse dyes. Additionally, dyes 9 and 10 exhibited the most excellent K/S values among the tested dyes. Furthermore, the study found that dye 8 showed the best dyeing performance as the pH of the dye bath increased to 6.