The printability properties of a water-based printing ink with a semi-synthetic azo dye from Eucalyptus spp. bark extract

Abstract

The aim of the study was the preparation of azo group containing dye using a feasible and inexpensive method. Azo dyes are one of the most prominent classes of chromophores and widely used as synthetic colorings in food dyes, pharmaceuticals, cosmetics, textile, printing and other industry and as pH indicators. Semi-synthetic natural dyes are regarded as multi-component systems because they are derived from plant-based extracts. The synthesized azo dye (SAD) was obtained as a mixture product from the reaction of Eucalyptus spp. bark ethanol-water extract with the diazonium salt of p-aminobenzoic acid (PABA). The structure of the SAD was investigated using UV-visible, FT-IR, H-1-NMR, LC-MS spectral data. In the LC-MS spectrum of SAD, at m/z 301.2 belong to quercetin ion was detected. The maximum UV-visible absorption of SAD was 431 nm and the extract has no absorption this region. In the FT-IR spectrum, at 1420 cm(-1) azo stretching band was observed. In the H-1-NMR spectrum, carboxylic acid proton exhibited at 12.80 ppm. Since SAD was water-soluble, its performance within a water-based flexographic printing system was examined. It can be concluded that the SAD has high color intensity and can be used as a colorant in water-based printing inks.