0023-6152

AA00697606

4772336

The thinned Cryptomeria japonica (Japanese cedar, JC) log with a length of 3.6 m above and the diameter at breast height with an end diameter larger than 25 cm was manufactured to JC veneers by rotary cutting. The veneers were dried at a temperature of 150–160°C for 980–1020 s. The veneers with a width less than 4 feet (ft) were side-glued to reach 4 ft, and the veneers with lengths less than 8 ft were edged by gluing. The veneers were classified manually after the natural defects on veneer surface were patched, and arranged in even/odd plies. The adhesive was urea–formaldehyde resin with the amount of glue of 240–270 g/m2. The prepressing was 6–8 kgf/cm^2, the hot–pressing pressure was 10 kgf/cm^2, the hot–pressing temperature was 100°C, and the hot–pressing time was 60 s/mm from the target thickness preset. The JC laminated veneer lumber (LVL) was mass–produced and compared with Pinus radiate (Radiata pine, RP) LVL. The delamination (%) in boiling water of JC LVL was 24.39%. The modulus of rupture (MOR) and modulus of elasticity in bending, the shearing strength, and the nail withdraw strength of JC LVL were 42.73 MPa, 6.35 GPa, 4.01 MPa, and 13.48 N/mm, respectively. After the 36–week outdoor corridor test, the color differences of JC LVL and RP LVL were 9.75 and 54.73; the contact angle of JC LVL was 35.67° and that of RP LVL was 15.00°; the increase of Ra, Rmax and Rz for JC LVL was 3.70, 21.38 and 15.94%, and those for RP LVL were 110.13, 53.45, and 39.06%; the MOR of JC LVL was decreased by 1.70%, for RP LVL it was 18.65%, and the delamination of JC LVL and RP LVL were 34.52 and 44.72%.