Environment-friendly UV-curable alkyd-based non-isocyanate urethanes

Two non-isocyanate polyurethanes (NIPUs) were used as reactive diluents for an alkyd to obtain eco-friendly new UV-curable alkyd-polyurethane coatings. A linseed-based alkyd resin was prepared and formulated with the reactive diluents (NIPUs) and free radical photoinitiator, and then UV-cured. NMRs were used to characterize the alkyd and NIPUs and glass transition temperature (T-g) of cured alkyd-polyurethanes were evaluated by using DSC. Further, spectroscopy and thermal stability of the coatings were evaluated by using ATR-IR spectroscopy and thermogravimetric analysis (TGA), respectively. Moreover, coating properties such as pencil hardness, cross-cut adhesion, pull-off adhesion, impact resistance, and reverse impact resistance were also evaluated. It was found that crosslink density, pencil hardness, adhesion, and T-g were dependent and proportional to the amount of the NIPUs (reactive diluents) showing significant improvement in mechanical and thermal properties compared to the linseed-based alkyd resin.

Automated summary

In this study, two non-isocyanate polyurethanes (NIPUs) were used as reactive diluents to prepare eco-friendly UV-curable alkyd-polyurethane coatings. The results showed that the amount of NIPUs had a significant effect on the hardness, adhesion, and thermal properties of the coatings, resulting in improved mechanical and thermal performance compared to the linseed-based alkyd resin.