Abstract
Three-layer board (OR-board) having flake-type oriented particles (average alignment angle (AAA): 10.7deg.) as the faces and strand-type random-oriented particles as the core, cross-oriented three-layer board (CO-board) in which the core consists of strand-type particles oriented (AAA: 33.9deg.) perpendicular to the direction of the oriented face layer, and three-layer board (RR-board) having random-oriented face and core particles were produced. The effects of the ratio of face layer weight to total board weight (FW) on bending properties and dimensional stability of the boards were investigated. Bending properties in the oriented direction of the OR-board increased with an increase in FW and the ratio of parallel-to-perpendicular (||/⊥) value for modulus of rupture (MOR) and modulus of elasticity (MOE) of OR-board with the FW of 60 percent was about 5 and 4, respectively. Bending properties of the CO-board with the FW of 15 percent corresponded to those of the RR-board. MOE values of the three-layer board estimated from the thickness and MOE of the individual layer were in good agreement with experimental values under MOE of about 50×103kgf/cm2. The ⊥/|| ratio for linear expansion of OR- and CO-board with the FW of 60 percent was 3.8 and 2.9, respectively.
