Development of Continuous Steam-Injection Press

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A continuous pressing system with a device of steam-injection from the hotplatem surfaces was designed and feasibility of manufacturing endless particleboard with thickness more than 50 mm was investigated. Fundamental research on the related problems to the steam-injection pressing was also made. The sesults are summarized as follows:1) The press installed trially had steam-injection platens of 800 mm (width) x 1,200 mm (length) and could move reciprocally along the stream of particle mat. It was verified that this type of intermittent press was more simple and adaptable to the steam-injection than conventional continuous presses.2) Particleboard of 100 mm thickness and 0.6 g/cm^3 density was producible by this press with 10 sec 140 c steam-injection followed by 80 sec hot-pressing. This press cycle is 20 times faster than that of conventional hot-pressing.3) The moisture condensation at the joint part of reciprocal pressing reduced the internal bond strength remarkably in some cases. However, the moisture condensation would be eliminated in some extent after some contimuation of production (warming-up).4) Numerical analysis of heat diffusion and temperature distribution in the mat by the finite element method was useful to predict the press cycle.5) It was shown that every resin had its own process of condensation and decomposition under high pressure steam-injection. urea resin had the narrowest time range optimum curing, while phenol and isocyanate resin had the broadest.