Green Approach to Dye PET and Nylon 6 Fabrics with Novel Pyrazole Disperse Dyes under Supercritical Carbon Dioxide and Its Aqueous Analogue

The development of a water-free dyeing process for synthetic fabrics is of great importance for the textile industry due to environmental and economic reasons. In this study, a series of novel 3-(3-chlorophenyl)-1-phenyl-4-(diazenyl derivatives)-1H-pyrazol-5-amine dyes were specifically synthesized for use with supercritical carbon dioxide. The new dyes were characterized by MS, IR, and NMR spectral data, and the results were found to be in good agreement with the proposed structures. The new dyestuffs were applied to dye polyester and nylon 6 fabrics under supercritical carbon dioxide and aqueous media. The color uptake expressed through the color strength (K/S) was assessed, and the values obtained showed that the dyeing of polyester and nylon 6 fabrics using the scCO2 method was significantly better than that using the aqueous method. The fastness properties of all the dyed fabrics were evaluated and exhibited excellent results. Raman micro spectroscopy indicated conclusively that the dye absorbance took place through all layers of the fabrics. Elimination of water and its costly processing can now be achieved in the dyeing of synthetic fabrics.