Synthesis and application of phthalimide disperse dyes

Three azo dyes had been synthesized using N-propyl substituted, dibromo-substituted and dicyano-substituted phthalimides as diazo components. All of the synthesized intermediates and dyes have been characterized by MS, 1H-NMR and IR analyses. The dyeing behaviour and fastness properties of these dyes had been investigated. The absorption maxima of the dyes were observed in the range 360 to 700 nm. The results indicated that dyes caused hypsochromism effect after -Br substitution and dyes caused bathochromism effect after -CN substitution. IR spectra of hydrolyzed dye showed that C=O groups appeared under relatively mild alkaline conditions. Compared with electron density, steric hindrance effect is an more important influence factor than electron density in hydrolysis reaction process. Exhaustion of dyed polyester/elastane fabrics decreased obviously as the pH value increased. In order to ensure dyeing levelness, heating rate of prepared dyes will be strictly controlled. Due to alkali-clearable property and interaction energy of dye-fiber and dye-dye, the dyes have good colorfastness.