Abstract: To improve the reliability of fire resistance with regard to wood materials containing a fireproofing treatment agent such as a semi-incombustible wood material while also improving both the ease of procuring raw materials and mass productivity, a panel board includes front/back veneers constituting the front and back thereof and a core veneer layer between the front/back veneers. The veneer fiber direction of the front/back veneers is substantially parallel to the lengthwise direction of the panel board. The core veneer layer is a layer obtained by stacking a plurality of sheets of core veneer in the thickness direction. The veneer fiber directions of all of the sheets of the core veneer are substantially orthogonal to the lengthwise direction of panel board. The front/back veneers has a thickness of 1.5-4.0 mm, and the thickness of the core veneer layer 31 is equal to or greater than the total thickness of the front/back veneer 21.

Abstract: The present invention improves the reliability of fire-resistance performance, and suppresses a drop in strength and a drop in Young's modulus for bending, with regard to a structural LVL containing a fireproofing chemical for fire-resistant structural wood material-use. The present invention is the LVL 61 for structural use comprising a plurality of raw material veneers 51 layered in the front-back thickness direction via adhesive layers therebetween. Each of the raw material veneers 51 is a wood material having a fireproofing chemical injected to the interior thereof and is constituted from a site of sapwood part alone, a site of heartwood part alone, or, a site wherein a sapwood part and a heartwood part are mixed. Injection holes 62 are provided, each having a circular cross section and extending in the thickness direction from each of the front surface and the back surface of the LVL 61. The injection holes 62 traverse through the plurality of raw material veneers 51 and the adhesive layers.

Abstract: A seven-layered laminated composite lumber 1 is constructed by stacking veneers 2, whose oven-dry specific gravity is 0.6 or larger, alternately with veneers 3, whose oven-dry specific gravity is 0.4 or less, and by bonding them together. The invention can thus provide a laminated composite lumber that is light in weight, is substantially resistant to warping and distortion, and yet retains the desired bending strength and nail holding power, and a method of producing such a laminated composite lumber.

Abstract: A seven-layered laminated composite lumber 1 is constructed by stacking veneers 2, whose oven-dry specific gravity is 0.6 or larger, alternately with veneers 3, whose oven-dry specific gravity is 0.4 or less, and by bonding them together. The invention can thus provide a laminated composite lumber that is light in weight, is substantially resistant to warping and distortion, and yet retains the desired bending strength and nail holding power, and a method of producing such a laminated composite lumber.

Abstract: Wood is preliminary dried until its moisture content is reduced to 20 to 30%, and then treated by radio frequency heating in two stages, i.e., the first stage where the radio frequency heating is carried out at a temperature of 60.degree. to 120.degree. C., and the second stage where the radio frequency heating is carried out at a temperature of not more than 60.degree. C.

Abstract: A method for preservation treatment of wood comprises the steps of radiating a laser beam on a part of the surface of the wood at the least to form small holes therein, impregnating the wood with a preservative, and then applying high frequency waves to the wood to dry it by dielectric heating.