METHOD FOR PRODUCTION OF LOW-TOXIC WOOD-PARTICLE BOARDS Russian patent published in 1995 - IPC

FIELD: wood working industry. SUBSTANCE: formed wood-particle briquette 5 is placed between upper heating plate 1 and lower heating plate 2 of hot press heated to 180-190 C. Briquette 5 is compressed with pressure of 3.0 MPa and heated to attain temperature in mat middle layer of 102-107 C. Then, briquette 5 is held for 60-80 s for binder hardening. Further on, press system is communicated with vacuum pump to create rarefaction of 0.1 MPa, and ammonia is supplied at pressure of 0.5-0.6 MPa through system of channels in lower heating plate 2. As a result, vapor-gas mixture is removed from wood-particle briquette 5, and it is saturated with ammonia. Ammonia treatment is lasted for 10-20 s. Ammonia supply is discontinued and its remaining amount is removed from stack by blowing with atmospheric air. Then, before unloading boards from press, they are conditioned by vacuum method with no contact of upper heating plate with treated boards. Rarefaction of 0.2-0.6 MPa is maintained for 24-144 s in hermetically sealed space between plates of hot press. Rarefaction is created from upper and lower sides of pressed boards. EFFECT: higher efficiency. 1 dwg, 1 tbl