Abstract: The enzymolysis lignin modified melamine urea formaldehyde resin(ELMUF) was prepared by using the classic alkali-acid-alkali method with enzymolysis lignin(EL), urea(U), formaldehyde(F) and melamine(M) as raw materials. The influences of the amount of EL on the curing time, curing temperature, free formaldehyde content, the strength and formaldehyde release of the plywood obtained from the prepared ELMUF resin were investigated. With the increase of the amount of EL, the free formaldehyde content decreased from 0.26% to 0.12%, the curing time increased from 96 s to 152 s and the viscosity increased from 86 mPa·s to 1 140 mPa·s. The curing process of resins with different amounts of EL was determined by DSC. The results showed that the introduction of EL could reduce the reactivity of the urea-formaldehyde resin. With the increase of the amount of EL, the curing temperature increased from 120.6℃ to 132.0℃, which required the hot pressing process requirements to be more stringent.

Key words: urea-formaldehyde resin, enzymolysis lignin, curing rate, bonding strength