PURPOSE: To reduce the dimensional change due to deaeration, enhance the rigidity under wet state and consequently prevent the strength of the board concerned from lowering, by a method wherein formaldehyde source is mixed with board stock to attain a uniform formalization under catalyst by making contact with wooden fiber having a great surface area and combination with cellulose.
CONSTITUTION: Board stock, which is prepared by splitting or crushing wood such as broad leaved wood material, after being applied with urea resin-based adhesive, is formed under heat and pressure into sheet in order to obtain porous board. In this case, the sheet is formed under the condition that formaldehyde source is added to the board stock and kneaded together. Under the state that the board is placed in the reaction device of gas circulating system so as to traverse the direction of gas flow, sulfurous acid gas as catalyst is introduced in the reaction device so as to pierce the board at 120°C to circulate for about 60min in order to formalize the interior of the board.
NORIMOTO KYO
SASAKI HIKARI
YAMAMOTO AKIO
SAWADA NORITOSHI
| JPH01144008U | 1989-10-03 |