Synthesis of fully bio-based branched unsaturated polyester oligomers and UV curing coatings

In this paper, fully bio-based branched unsaturated polyester (BUPE) oligomers were synthesized by one-step solvent-free polycondensation using itaconic acid, isosorbide and glycerol as feedstocks. The branched structure was confirmed by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy ( 1 H NMR). The effect of the branched structure on the properties of BUPE UV curing coatings was investigated. The results showed that the introduction of a glycerol branched structure was favorable for UV curing. The BUPE UV curing coatings based on the glycerol branched structure showed higher gel content and crosslink density, which enhanced the hardness, solvent resistance and mechanical properties of the coatings. In addition, the BUPE UV curing coatings possessed extremely low surface roughness, excellent heat resistance and light transmission properties.