Application of Soy Flour Modified Resins to Hot and Cold Pressed Veneer

Soy flour can be substituted in polymeric diphenylmethane diisocyanate (pMDI) resin for bonding plywood. Resin bleed-through is avoided by prepressing at 95°C. The boards have greater wet and dry strength than do those prepared from melamine-urea-formaldehyde (MUF) resin. Soy flour can also be substituted in emulsion polymer isocyanates for cold-press applications. The soy increases dry strength but keeps the wet strength unchanged. The optimal level of soy flour substitution is about 20 percent in all cases as determined by infrared spectroscopy.