Investigation of low mole ratio UF and UMF resins aimed at lowering the formaldehyde emission potential of wood composite boards

Abstract

Urea-melamine-formaldehyde (UMF) resins with 2.5% and 5.0% melamine levels added at the beginning of the third step of the typical urea-formaldehyde (UF) synthesis procedure were synthesized with an F/(U+M) mole ratio of 1.05 and evaluated as particleboard binders to investigate the positive effects of melamine on the formaldehyde content and physical performance of boards. Resins were tested for storage properties and analyzed by 13C NMR. Curing catalysts were studied, curing rates were measured, and laboratory particleboards were prepared and tested for formaldehyde contents as well as strength and water-soak test values. The UMF resins resulted in slower curing rates but had adequate board strength values. The formaldehyde content values were within the newly created California emission law (5.2 to 8.0 mg/100 g board). Another objective of this work was to establish the baseline performance of these resins for use in subsequent studies that will aim to reveal the effects of methylene-ether group contents on formaldehyde emissions.