Application of manganese-based driers in tung oil: drying behavior, paint film properties, and drying mechanism

Organic chelating ligands can enhance the drying efficiency of manganese (Mn2+)-based driers by altering the spatial and electronic properties. However, the correlation between organic chelating ligands and their ability to dry tung oil remains unclear, as well as the underlying mechanism. In this work, the effects of acetylacetone (Hacac), benzimidazole (benz), and 2,2-bipyridine (bipy) ligands on the Mn2+-mediated drying of tung oil were investigated. The curing process of tung oil was studied by Fourier-transform infrared (FTIR) spectroscopy and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopy. The results showed that strongly -electronegative coordination atoms improved the drying activity of Mn2+. In addition to the type of coordina-tion atoms, their quantity also promoted paint film drying and property improvements. Compared with the pure tung oil, under the action of the drier with the most coordination atoms, the paint film drying time was shortened by 86.58 h, and the hardness, flexibility, and scratch resistance were improved by 3.98%, 16%, and 200 g, respectively. This study helps understand the mechanism by which ligands affect the drying properties of tung oil.