Curing Behavior of UF Resin Modified with Melamine for High Moisture Content Veneers

摘要

Introduction Urea-formaldehyde (UF) resin is one of the most important adhesive resins for the production of wood-based panels. Generally, veneers used for the conventional UF-made plywood must have moisture content of less than 8%. When using a resin capable of bonding veneers with high moisture content of 15 to 20%, the decreased drying time, reduced loss through breakage, and energy saving are feasible in the veneer drying stage. During the standard hot-pressing at high temperatures, however, these high moisture content veneers will cause swelling or blowout by entrapped moisture, starved joint or surface contamination by over penetration of resin, wood loss by veneer compression, etc. It is therefore of critical importance to add proper catalyst to the resin mixture and to select hot-pressing schedule carefully for optimal bond strength. This study aims to discuss the effects of catalyst and extender content on curing behavior of UF resin modified with melamine (UMF) for bonding veneers with high moisture content.