Investigation from Synthesis to Crystal Structure to Application of Ecofriendly Disperse Dyes on One-Step Dyeing of PET Fabric

Five disperse dyes (D1–D5) with 2,6-bichlor-4-nitroaniline or 2-chloro-4-nitroaniline as the diazo component and N-substituted anilines as the coupling component were designed and synthesized in order to compare the differences derived from their molecular structure. All the synthesized disperse dyes were characterized by FT-IR, 1H NMR, and elemental analysis. Their spectral property was evaluated with respect to visible absorption properties in various solvents of distinguishable polarity. The synthesized disperse dyes were applied on one-step dyeing of polyethylene terephthalate (PET) fabric. The alkali stability of the dyes in case of one-step dyeing at various NaOH concentrations was discussed by comparing color parameters of the dyed PET fabrics. Besides, the alkali stability of the dyes was investigated with respect to the nature of chemical constitution and the substituents therein by X-ray crystal diffraction analysis. The results show that D4 and D5 have excellent alkali stability and can combine pretreatment and dyeing in an alkali bath, which could be attributed to the head-to-tail compact structure, intramolecular and intermolecular forces and large sterically hindered group (−CH2–Ph). The levelness and color fastness as well as mechanical properties of the dyed PET fabrics with a one-step dyeing method were measured by an ISO standard method.