Synthesis, Application, and Recovery of Alkali-Clearable Disperse Dyes Containing Azo Pyridone Structure

Carboxylic acid ester disperse dyes containing an azo pyridone structure have a high molar extinction coefficient, excellent washing color fastness, and simple synthetic methods. Dyes were readily synthesized through a conventional diazo coupling reaction between the reactant ethyl p -aminobenzoate and a coupling component containing an azo pyridone structure. Subsequently, the molecular structures of the target products were characterized by FTIR, mass spectrometry, 1 H NMR, 13 C NMR, UV-vis absorption spectroscopy, and elemental analysis. The synthesized dyes were used to dye poly(ethylene terephthalate) fabric, and their washing and rubbing color fastness properties were tested and compared under different post-treatment methods. Moreover, under the condition of alkali clearing, the relationships among different alkali concentrations and clearing effects were studied to determine the optimal alkali clearing process conditions for dyed fabrics, and the minimum alkali consumption required to obtain the best results was determined. It was found that carboxylic ester disperse dyes containing an azo pyridone structure showed good dyeing performance and alkali-clearable properties on polyester fibers. In addition, in hydrolyzate recovery, BaCl 2 (salting out) can be used instead of acidification to recover the dye hydrolyzate, which has good environmental benefits.