HARD CEMENTED CHIP BOARD AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce the cemented chip board having improved fire resistance by forming a cemented chip board comprising: a surface layer that is obtained by hardening a surface layer composition consisting of a wood reinforcing material, a cement composition and water; a rear layer that is obtained by harbening a rear layer composition consisting of the above wood reinforcing material, the above cement composition and water; and an intermediate layer that is placed between the surface layer and the rear layer and consists of a refractory material having low thermal conductivity. SOLUTION: This production comprises: preparing a composition for both a surface layer and a rear layer, (i.e., surface/rear layer composition), which consists of about 15 pts.wt. of a wood reinforcing material such as wood chips of Western hemlock, about 100 pts.wt. of a cement composition ((portland cement)/(alumina cement)/(hemihydrate gypsum)/(sodium citrate)/(slaked lime) composition) and about 50 pts.wt. of water; then, uniformly spreading a half of the amount of the prepared composition on a mold plate; thereafter, placing a refractory material having low thermal conductivity, such as inorganic fiber fabric on the layer of the composition; subsequently, spreading the remainder of the prepared composition on the layer of the refractory material; then, placing a pressing plate on the resulting second layer of the composition; and pressurizing these layers thus formed, from the upper and lower sides with a pressing machine to subject them to integral forming and to produce the objective hard cement chip board 3 consisting of a surface layer 4, an intermediate layer 6 provided with through-holes 61 and a rear layer 5.