DIFURFURYL DIISOCYANATES - NEW ADHESIVES DERIVED FROM RENEWABLE RESOURCES

The syntheses of difurfuryl diisocyanates [e.g., ethylidenebis(2,5-furandiylmethylene) diisocyanate (EDFI) ] have been reported in the literature. Difurfuryl diisocyanates are structurally similar to diphenylmethane diisocyanate (MDI), which has proven to be an excellent adhesive for bonding wood composites. The MDI resin is synthesized from petroleum-derived chemicals; the EDFI resin is synthesized from biomass-derived chemicals. In this study, the mechanical properties of aspen flakeboards bonded with MDI and EDFI are compared. In general, results show that the strength properties of flakeboards bonded with MDI are only marginally better than those bonded with EDFI. Because EDFI is more viscous than is MDI, less than optimum atomization of the EDFI resin during spraying of the flakes is believed to be largely responsible for the differences in strength property values. The dry internal bond strength values of flakeboards bonded with MDI (1.33 MPa; 193 lb/in.2) and EDFI (0.97 MPa; 140 lb/in.2) at 3% resin content are significantly greater than the 0.41 MPa (60 lb/in.2) required by the American National Standards Institute (ANSI/A208.1) for type-2 medium-density particleboard.