Effects of FlU Molar Ratio and Melamine Content on the Properties of Urea-Melamine-Formaldehyde (UMF) Resins

摘要

Introduction Formaldehyde-based resins arc most widely using adhesives for manufacturing wood-based composites. The low cost of UF resins affords them to use for production of low cost wood composites. However, its fatal weakness against moisture allows them to use for interior applications only. Cured UF resins are not water resistant, thus it causes many problems; change dimensions and then disintegrates. In addition, When UF resin bonded boards are contact with moisture for a long time, those emits formaldehyde and causes sick house syndrome. Therefore, the formaldehyde emission has been one of the most important issues of UF resin in the last few decades. Both the reversible curing mechanism of UF resins and the low resistance against hydrolysis of cured UF resins are major factors affecting formaldehyde emission of UF resin bonded wood-based boards. The formaldehyde emission during curing on board manufacturing or during using boards has been controlled and reduced greatly by technical advancement. The hydrolysis mechanisms of cured UF resins were investigated and the reversible reaction schemes of UF resins were revealed. Numerous researches focused on the formaldehyde emission and the water resistant were done on UF resins but few of them have been reported. Therefore, this study was done to examine the effects of F/U mole ratio and melamine content on the properties of UMF resin adhesives.