Waterborne polyurethane with excellent UV resistance and strong adhesion modified with tannic acid metal complexes

Due to its high weather resistance, waterborne polyurethane (WPU) is a popular coating material, but it still ages and cracks under continuous exposure to ultraviolet light. In this study, the UV resistance of polyurethanes was enhanced by introducing tannic acid metal complexes into waterborne polyurethanes. Experiments showed that tannic acid metal complexes had strong absorption in the ultraviolet region and that the UV resistance of polymers could be significantly improved by incorporating the complexes into the polyurethane molecular chain by in situ polymerization. The modification effect was most pronounced in the comparative evaluation after introducing TATi. After UV aging for 1656 h, the polyurethane surface showed no apparent damage, and the retention rate of mechanical properties remained 100 %. The polymer also had excellent mechanical properties, water resistance, and adhesion, which provided a new idea for developing biomass-modified polyurethane coatings with both UV resistance and excellent adhesion.