Synthesis And Application Of Pyrazolone-containing Carboxyester Dyes

As the most popular biodegradable material, polylactic acid(PLA) fiber draws much attention for its excellent properties and comprehensive applications. However, only limited disperse dyes have good sorption on polylactic acid fiber because of its specific chemical structure, which postponing its further application in textile industry. The fibers and the dyes having similar structures always show high affinity between them. According to this theory,six carboxyester dyes were designed and synthesized in this paper. The dyes are tried to apply to PLA,and PET fabrics in expectation of high dye exhaustion and excellent color fastnesses.The corresponding sulfonyl chloride intermediates are prepared in SOCl2/DMF chlorination system by using the pyrazolone-containing acidic azo dyes as reactants. Then six carboxyester dyes are synthesized by the reaction of the acyl chlorides and different sorts of alcohols in the presence of acid-binding reagent. Then the molecular structures of the carboxyester dyes were characterized by FTIR, 1H NMR and mass spectrometry.All of these carboxyester dyes were applied to poly(lactic acid) fabrics in exhaust dyeing. Moreover, the different dye sorption on PLA fabrics was discussed. In the dyeing results, five carboxyester dyes are suitable for dyeing PLA fabrics and their dye sorptions are all greater than 70%. Excepting the sublimation fastness is 3 grade, the washing and rubbing fastnesses are more than 4 grade. Besides, all six dyes perform excellent dyeing behavior on PET fabrics, the sorption rates are more than 85% with good color fastness. The experiment about water solubility of carboxyester dyes showed that to got excellent dyeing effect, the appropriate water solubility of carboxyester dyes was needed. The data of standard affinity which was measured through dyeing thermodynamic is consistent with the results of the dye sorption on PLA fabrics.