Dynamic control of moisture during hot pressing of wood composites
Hot pressing is an important step in the manufacture of wood composites. In the conventional pressing system, hot press output often acts as a constraint to increased production. Severe drying of the furnish (e.g., particles, flakes, or fibers) required by this process substantially increases the manufacturing cost and creates air-polluting emissions of volatile organic compounds, which are a main source of air pollution from the forest products industry. Wood composites made in the conventional process have high internal stress and low dimensional stability and strength. The development of a pressing technology to improve the process is limited by the release of vapor pressure during hot pressing. A perforated caul system may enlarge the area for the moisture to escape from the board mat during pressing, and thus, make possible high moisture content (MC) pressing.