Effect of chemical modification of lignin on the gluebond performance of lignin-phenolic resins

Lignin obtained from eucalyptus wood by acetic acid pulping was methylolated or phenolated and used to prepare lignin-phenol-formaldehyde resins. The amount of formaldehyde consumed in the methylolation reaction, and supporting comparison of pre- and post-methylolation ¹H and ¹³C NMR spectra, showed the reactivity of the crude acetosolv lignin with formaldehyde to be relatively high. Pine and eucalyptus plywood boards manufactured using the resins prepared with the modified lignins complied with European Standard EN 314-1:1993 for WBP quality boards and gave knife test results similar to those of boards manufactured with a commercial phenol-formaldehyde resin.