Enhanced wood protection and sustainability via nano-modified raw lacquer coatings: Preparation, properties, and performance evaluation

Raw lacquer is a natural polymer-based anticorrosive coating. However, the long curing time, poor acid and alkali resistance, and insufficient mechanical strength of raw lacquer limit its application in the coating field. In this study, nanocomposite coatings for wood surfaces were developed using raw lacquer as the matrix, which incorporated nano-Al₂O₃ nanoparticles (Al₂O₃ NPs) and redispersible cellulose nanofibers (CNFs) as nanofillers. The results revealed that the composite coating improved the moisture resistance and aging resistance of wood. The modified Al₂O₃ NP/lacquer (QA) and modified CNF/lacquer (QF) coatings improved the hardness (6 H) and gloss of the wood. Particularly, the QA- and QF-coated wood achieved gloss values of 6.9 and 5.1 GU, respectively. The addition of NPs reduced the drying time of QA and QF coatings by 27.8 % and 66.7 %, respectively, compared with raw lacquer (Q) coating. Scanning electron microscopy and Fourier-transform infrared analysis confirmed that NP incorporation enhanced the polymerization of the paint film. Consequently, QA- and QF-coated wood exhibited higher moisture and aging resistance than Q-coated wood, which reduced water absorption rates by 13.73 % and 6.6 %, respectively. In a humid environment, QF-coated wood exhibited the highest dimensional stability. Moreover, the QA-coated wood surface exhibited the highest resistance to UV-induced discoloration, with a 37.07 % improvement in aging resistance. This study provides a green and simple approach for improving the outdoor performance of raw lacquer as a wood coating.