A simple pathway for the preparation of an environmentally and high performance glyoxal-based adhesive for plywood

The use of glyoxal to replace formaldehyde for preparing wood adhesive was considered as an effective way to address formaldehyde issue. However, the properties of glyoxal-based resins via continent preparation process were poor, especially the water resistance was pretty low compared with the formaldehyde-based resins. Here, a new glyoxal-polyvinylamine-urea (GPU) copolymer resin with excellent water resistance was presented in this work by using polyvinylamine(PVAm) as a modifier agent to enhance the performance of glyoxal based resins. The bonding strength and water resistance of this new glyoxal-based resin were evaluated via measuring mechanical property of three-plywood produced in our laboratory. The structural features of this resin were characterized by FT-IR, ESI-MS, their curing and thermal behavior were also explored. This resin has a fast curing rate and good thermal stability, and the best dry bonding strength of plywood was 2.37MPa, and the wet bonding strength was 1.10MPa and 0.71MPa after immersed in cold water for 24h and 63 ℃ hot water for 3h, respectively. The enhanced water resistance can be explained by the formation of a better cured resin network verified from the FT-IR, ESI-MS spectroscopy analyses.