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-Al 2 O 3 nanoparticles (Al 2 O 3 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 Al 2 O 3 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. • Nano Al 2 O 3 and nano-cellulose have positive effects on the modification of raw lacquer, the organic reagent (KH550) makes the nanoparticles disperse uniformly in the raw lacquer. • The composite paint with nanocellulose added makes the wood have higher dimensional stability, and the tangential, radial and volume expansion rates are reduced by 26.56 %, 47.00 % and 29.17 %, respectively. • The wood coated with nano Al 2 O 3 composite lacquer has higher light aging and discoloration resistance, which is 37.07 % higher than that of raw lacquer. • Composite coatings can improve the outdoor performance of wood.