Lignin-based Phenol-Formaldehyde Resins from Purified CO₂ Precipitated Kraft lignin (PCO₂KL)

Abstract

To investigate the potential for using purified CO₂-precipitated Kraft lignin (PCO₂KL) with phenol-formaldehyde (PF) for application as an adhesive in plywood production, two lignin replacement procedures were examined to assess lignin’s effect on bond quality. Methylolation and oxidation with hydrogen peroxide (H₂O₂) were carried out to try to increase lignin reactivity. The first procedure involved substitution of 30% of the PF resin solids in the adhesive mix with a solution of methylolated lignin with or without prior oxidation; the second replacement procedure involved direct condensation of lignin or oxidized lignin to replace 25% of phenol. Formulated adhesives were compared to a control phenol-formaldehyde (PF) adhesive prepared in the laboratory. The physical properties (solid content, viscosity and pH values) of formulated resins were determined. PCO₂KL-based adhesives showed comparatively good plywood shear strengths. However, they had lower wood failures than those of test samples made from PF resin only.

Citation

Chen, Yao; Frihart, Charles R.; Cai, Zhiyong; Lorenz, Linda F.; Stark, Nicole M. 2013. Lignin-based Phenol-Formaldehyde Resins from Purified CO₂ Precipitated Kraft lignin (PCO₂KL). In: International Conference on Wood Adhesives, October 9-11, 2013 Toronto, Ontario Canada from CD ISBN: 978-0-935018-37-0; 2013; pp. 601-610.