Research on the Preparation of Wood Adhesive Active Fillers from Tannin-/Bentonite-Modified Corn Cob

The artificial plywood industry in our country relies heavily on industrial flour as a filler for adhesives. Using abundant corn cob powder as the main raw material, corn cob powder was modified by impregnation with a sodium-based bentonite/bayberry tannin and used as filler for urea–formaldehyde resin (UF) adhesive, with NH4Cl as the curing agent and poplar veneer as the raw material to prepare plywood. The results showed that the modified corn cob powder with a particle size of 250 mesh was uniformly dispersed in the UF adhesive. When used as a filler, the modified corn cob powder effectively prevented the premature curing of the UF adhesive and significantly reduced its viscosity. Compared with flour filler, the bonding strength of the prepared plywood increased by 12.1%–19.6% while the formaldehyde emission decreased by 12.7%–27.8%. The cold pressing performance of the plywoods prepared with modified corn cob flour was comparable to the performance of plywood produced with industrial flour.