Azo reactive dyes: ultrafiltration and application to cotton by exhaustion and digital ink-jet printing

Three reactive dyes have been synthesized by coupling 1-amino-phenyl-4-beta hydroxyethyl sulfone sulfate ester with 1-amino-8-hydroxynaphalene-3,6-disoulphonic acid (H-acid). The dyes synthesized were then purified using ultrafiltration and water-based reactive ink jet inks were prepared for digital printing applications. The dyes were characterized by their spectrophotometrical data ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy, optical emission spectroscopy, X-ray diffraction and elemental analysis. The purity of dyes was checked by thin layer chromatography and their dyeing performance was assessed on cotton fibers by exhaustion (dyeing) and ink-jet printing. Ink-jet inks with the dyes synthesized were prepared and their physical properties were measured in order to evaluate their suitability for ink-jet printing. Color measurements and fastness properties were performed for the dyed and digitally printed samples. Coloristic values of the dyed/ printed samples were as expected, that is, K/ S values of the dyed samples were much higher than those of the printed ones, K/ S values of the samples dyed with the ultrafiltrated dyes were higher than those with the initial dyes and the rest of the coloristic co-ordinates L, a, b, C, H, were in line with strength changes of the dyes before and after ultrafiltration. The dyed samples had excellent wash fastness and medium light fastness. Ultrafiltration slightly improves the fastness properties of the dyed samples.