Preparation of liquefied bark-based resol resin and its application to particle board

Barks of Taiwan acacia (Acacia confusa) and China fir (Cunninghamia lanceolata) were liquefied in the presence of phenol with sulfuric acid (H2SO4) and hydrochloric acid (HCl) as catalyst. The properties of resins prepared from liquefied bark and the feasibility of liquefied bark-based resol resins in particle board manufacturing were investigated. The viscosity and thermosetting property of liquefied bark-based resol resins were affected by the kind of bark species and the catalyst used. Liquefied bark-based resol resins using China fir bark as raw material had higher viscosity than the ones using Taiwan acacia bark. In the course of thermosetting, liquefied bark-based resol resins using Taiwan acacia bark as raw material had a higher maximum temperature of exothermic peak and onset temperature as well as a larger quantity of exothermic heat than those using China fir bark. Resol resins prepared from bark liquefied with H2SO4 as catalyst had higher viscosity, while resins with HCl as catalyst had a higher maximum temperature and height of exothermic peak and a larger quantity of exothermic heat at thermosetting. Particle board made with A-S adhesive that was prepared from liquefied Taiwan acacia bark with H2SO4 as catalyst had the best particle board properties than those made with other adhesives. For the particle board made with A-S adhesive, its static bending strength and internal bonding strength would be increased as the hot-pressing time extended. The particle board made with hot-pressing temperature of 150degreesC and hot-pressing time of 10 min had the maximum normal and wet static bending strength and internal bonding strength. Its normal static bending strength was 170.8 kgf/cm(2) and the particle board showed satisfactory wet static bending strength and internal bonding strength. (C) 2003 Wiley Periodicals, Inc.