THE CHEMISTRY AND DEVELOPMENT OF PINE TANNIN ADHESIVES FOR EXTERIOR PARTICLEBOARD

Pine tannin-based adhesives obtained by the reaction of polymeric MDI (4,4'-diphenylmethane diisocyanate) with mildly sulphited pine tannin extract are described. Tolerance limits as regards moisture content re sistance, pressing time, proportion of MDI and tannin extract, percent age adhesive solids content and others were studied at laboratory leve l. Industrial results of extended plant production runs of these adhes ive systems showed very encouraging results and are presented. The rea ctions of polymeric MDI with model compounds representing all the diff erent species in the adhesive systems presented were studied by FT-IR and gave an indication, in water solutions, of which species are likel y to react and at what rates. The results obtained also indicate that non-emulsifiable MDI can be successfully used with tannins and other p olyols in water solutions.