Sustainable lignin-based powder coatings doped with ZnO displayed excellent UV resistance properties

Lignin with increased polyhydroxyl content (LOH) was prepared via a one-pot synthesis using enzymatically hydrolyzed lignin (EHL) as the raw material. The modified structure and hydroxyl content of LOH were analyzed using FT-IR, 1 H NMR, and 31 P NMR. LOH was blended with zinc oxide (ZnO), polyester resin and hydroxyl alkyl amide (HAA) to prepare polyester powder coatings. The anti-UV properties of the coating were significantly enhanced by the addition of LOH and ZnO. The coating exhibits exceptional adhesion, rating at level 0, and achieves a pencil hardness of 7H. The gel time for the coating is 195 s, and it has a 5-degree Celsius increase in melting temperature, which greatly enhances its storage stability. Considering a range of factors, the formula LOH7.5 % has been identified as the optimal composition. The results of this study demonstrate an easy approach to developing sustainable lignin-based powder coatings with excellent properties.