The wettability effect of branched polyglycerols used as performance additives for water-based printing inks

Abstract

The aim of this work was to study the influence of primary and secondary hydroxyl groups in the branched polyglycerol on the selected properties of water-based printing ink and copies printed with water-based flexographic printing inks. The branched polyglycerols were synthesized through anionic ring-opening polymerization using trimethylolpropane as a starting material. Obtained polyglycerol exhibited an irregular structure containing primary and secondary or predominantly primary hydroxyl groups in the macromolecule. The analysis (FTIR, 1H NMR, 13C NMR) confirmed the structure of polyglycerols. Obtained polyglycerols were then used as a performance additive in a water-based flexographic printing ink. The contact angles of the printing inks on the printing base were measured. The impact of a small amount of branched polyglycerol on the printing ink color was examined by studying the optical density of a full-tone area, the color values (CIELAB), the total color difference Delta E_{ab}^{*}, and gloss of the dried ink film. In general, the addition of branched polyglycerol containing only primary hydroxyl groups improved the wettability of the plastic film and gloss of printing ink with an acceptable total color difference Delta E_{ab}^{*} in contrast to branched polyglycerol with primary and secondary hydroxyl groups.