Synthesis of azo and anthraquinone dyes and dyeing of nylon-6,6 in supercritical carbon dioxide

In this work, thiazole based azo dyes (6A and 6B) and anthraquinone dye derivatives (6C, 6D and 6E) were synthesized from commercially inexpensive starting materials.The advantage of the synthesis of these dyes are quite facile and scale-up is feasible, which favors for an industrial dyeing applications. All the dyes were characterized by spectroscopic techniques such as IR, NMR (H-1 and C-13), HRMS and UV-vis spectroscopy. Preliminary dyeing experiments were carried out with these dye stuffs on nylon 6,6 fabrics to examine the possibility of scaling up supercritical carbon dioxide dyeing to a factory level. All the five dyes (6A-6E) showed good color strength and especially two dyes 6A and 6C exhibited excellent dye fixation. Remarkable results obtained for washing fastness (fading and staining grade of 4-5) and sweat fastness (fading and staining grade of 4-5) for all the dyes (6A-6E). Based on the results, the synthesized dyes could be hopefully applied in near future for the dyeing of nylon 6,6 fabrics on an industrial scale under the ecofriendly and energy-efficient supercritical carbon dioxide medium.