Adhesive application method in MDI-UF particleboard manufacture

Abstract

Chinese wood-based composite manufacturers are plagued with serious formaldehyde emission (F-emission) problems. In this study, we investigated the use of an emulsifiable diphenylmethane-4, 4 -diisocyanate (MDI) -urea formaldehyde (UF) mixture adhesive in particleboard manufacture, in order to decrease F-emission to below 9 mg per 100 g board. We paid close attention to the effect of NH₄Cl on MDI-UF curing and the method of adhesive application by differential scanning calorimetric (DSC) analysis and compared mechanical properties. Both results showed that the acidic agent NH₄Cl did hinder EMDI-UF curing and it also affected the adhesive application method. We are of the opinion that when EMDI and UF are mixed first, without adding NH₄Cl and then sprayed onto particles, mechanical properties will be improved and F-emissions will meet E1 grade requirements.