Application of cure-accelerated phenol-formaldehyde (PF) adhesives for three-layer medium density fiberboard (MDF) manufacture

This study was conducted to optimize hot pressing time and adhesive content for the manufacture of three-layer medium density fiberboard (MDF) through the cure acceleration of phenol-formaldehyde (PF) adhesives by adding three carbonates (propylene carbonate, sodium carbonate, and potassium carbonate) in the core layer. Carbonate type, carbonate level, PF resin content, and hot pressing time were evaluated on the basis of the performance of MDF panels prepared. The application of cure-accelerated PF adhesives by the addition of propylene carbonate reduced both PF resin content and total hot pressing time by 38% and 29%, respectively, for the manufacture of quality three-layer MDF panels (19.1 mm thickness) under the hot-pressing temperature of 205 degreesC. The optimum concentration of propylene carbonate for cure acceleration of PF resin was found to be 3 wt% by weight based on the resin solids. Bending properties, on one hand, were independent of carbonate type and level, and complied with the minimum requirements by ANSI. Internal bond (IB) strength, on the other hand, was closely related with carbonate types and level used.