Production and improvement of high performance particleboards.

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Dimensional stabilization and biological resistance of particleboards made from phenol-formaldehyde (PF) resin-treated particles were investigated. For the treatment with a low-molecular-weight PF-resin, an one-step treatment method was employed. The method is to spray a mixture of the low-molecular-weight resin and the adhesive resin. The relationships between concentrations of PF-resin for impregnation and resin loading (RL) after heat curing were approximately on a straight line. To attain a 15% RL,about 8% resin solutions was used for Japanese cedar.Dimensional stability and mechanical properties of the PF-resin treated boards were affected considerably by the RLs, and as the RL increased, the antiswelling efficiency (ASE) value increased. Smaller molecular weights of resins gave larger ASE valus than larger ones at the same RLs. Results obtained from accelerated laboratory tests of biodegradation suggested that RLs worked well to enhance decay and termite resistance of the boards. For a brown-rot fungus, the weight loss was substantially reduced at 15 % RL,whereas attack was suppressed almost entirely even at low RLs for the white-rot fungus. The splaying treatment employed is a one-step treatment that is considered preferable for time saving and cost efficiency in board production. These boards are worthy of consideration for commercial application.