METHOD OF CHANGE OF WOOD PHYSICO-MECHANICAL PROPERTIES Russian patent published in 1998 - IPC

FIELD: change of wood physico-mechanical properties. SUBSTANCE: wood is placed in a sealed chamber. Then vacuum up to 0.03 MPa is built in the chamber by evacuating air from it by a vacuum pump. After evacuation of air gaseous ammonia is fed to the chamber under pressure. Then wood is heated to a temperature of 80 to 85 deg. C by heating up the chamber by steam. After that wood is subjected to chemical treatment by circulation of gas-ammonia mixture in the chamber. Pressure, rarefaction and temperature in chamber 1 are monitored by reference to a pressure gauge, vacuum gauge and thermometer respectively. On completion of wood treatment by ammonia, pressure in the chamber is reduced to the atmospheric one (0.1 MPa). After atmospheric pressure is attained in the chamber, vacuum is built in it up to 0.03 MPa. Then pressure in the chamber is increased up to the atmospheric one again by feeding compressed air to it. After the necessary moisture content is attained, wood is ready to thermal treatment at which wood is heated to a temperature of 110 to 120 C and cured at this temperature for 1-5 h. On completion of thermal treatment, the chamber and wood are cooled down to 40-50 C, and wood is unloaded from the chamber. EFFECT: facilitated procedure. 3 cl, 1 dwg