Glucose-Lignin-Based Phenolic Resin: An Environmentally Friendly Low-Formaldehyde Wood Adhesive

In this paper, a low-formaldehyde and environmentally friendly phenol-formaldehyde resin wood adhesive was prepared by directly using lignin to substitute formaldehyde, which was further modified by glucose to improve the physical, mechanical, and curing properties. The results showed that when the replacing amount of lignin to formaldehyde reached 15 wt%, the physical properties of the prepared lignin-based-phenolic resin (LPF) can meet the Chinese national standard, and the bonding strength can increase by 21.9%, from 0.75 MPa to 0.96 MPa, compared with phenolic resin (PF). The addition of glucose boost the performance of wood adhesive, for example, the free phenol content of the obtained glucose-lignin-based phenolic resin (GLPF) significantly reduced by 79.11%, from 5.60–1.17%, the bonding strength (1.19 MPa) of GLPF increased by 19.3% in comparison to LPF, and the curing temperature of GLPF decreased by 13.08%. FT-IR results showed that the main structure of the resin did not change before and after substitution by lignin and modification by glucose. The present study provides a simple and green method for preparing resins.