Research progress of green adhesives for wood-based panels

Currently, the predominant adhesives utilized in the wood industry are derived from Abstract: Currently, the predominant adhesives utilized in the wood industry are derived from petroleum-based sources, primarily formaldehyde resins. These resins are widely employed in the wood-based panel sector due to their exceptional bonding properties. However, the finite nature of fossil resources, coupled with the environmental pollution resulting from their extraction processes, poses significant risks to ecosystems. Moreover, common formaldehyde adhesives release formaldehyde during application, jeopardizing human health. In contrast, biomass presents an ideal green raw material, characterized by its abundance and renewability. Consequently, there has been increasing interest among researchers in developing green adhesives for wood-based panels. It is of great significance to harness plentiful biomass resources to formulate biomass-based adhesives or to explore inorganic adhesives as viable complements to conventional formaldehyde resin systems. Recent investigations have spotlighted the potential of natural polymers (such as tannin, lignin, proteins, and starch) in the development of biomass-based adhesives. This approach not only mitigates the emission of harmful substances like formaldehyde but also diminishes environmental pollution, thereby enhancing the safety of human habitats. Additionally, biomass adhesives offer significant performance adaptability, fulfilling the diverse needs of the wood industry regarding bond strength, water resistance, and thermal stability. Furthermore, inorganic adhesives have gained traction as a robust complement to traditional organic adhesives. Their implementation in the production of various wood-based panel products is driven by their favorable environmental characteristics and high-temperature stability. Unlike organic adhesives, inorganic formulations do not emit harmful gases during the curing process, resulting in reduced risks to both environmental integrity and human health, thereby enhancing their green credentials. This paper aims to review recent advances in replacing or modifying conventional petroleum-based adhesives with biomass alternatives. It will summarize the historical development and bonding mechanisms of wood adhesives, emphasizing the applications of biomass adhesives, such as tannin, lignin, protein, and starch, as well as inorganic adhesives, including silicate, magnesium oxychloride, magnesium oxysulfide, and phosphate, within the wood-based panel industry. By analyzing the strengths and weaknesses of various adhesive types, this study will evaluate the substitution potential and modifying effects of biomass, discuss its prospects in the wood-based panel sector, predict the future direction of green wood adhesives, and provide fresh insights for the development of new eco-friendly adhesive solutions.