Tannin structureplays a determinant role in formulating tannin resin and adhesives forindustrial use. Tannin adhesive has been used as a thermosetting woodadhesive for wood panels to reduce formaldehyde emission. Tannin adhesive givesexcellent adhesive performance, good moisture resistance, and tends to give alower formaldehyde emission. Tannin wood adhesive in a non-formaldehydeapproach has a low hardening rate and needs more pressing time thanformaldehyde-based wood adhesives during wood composites production.
Hundreds oftonnes of tannin is produced from wood materials and wood bark for the needs ofleather, beverage and animal feed industry. In industrial use, tannin could beused to replace fossil chemicals in adhesives and insulating foams. Tannin canbe extracted from bark using hot water, after which the extract is dried into apowder. Drying the water extract into powder may not be necessary if the tanninis extracted near the site where glued wood products are manufactured. Tanninbased wood adhesives have been used industrially for exterior wood bonding ofproducts such as particleboard, plywood, glulam, and finger jointing.