EFFECT OF BORON ADDITION TO ADHESIVE AND OR SURFACE COATING ON FIRE-RETARDANT PROPERTIES OF PARTICLEBOARD/

Boron added to urea formaldehyde (UF) resin during manufacture of boar d from waste tea leaves was combined with a fire-retardant coating sys tem containing boron to further reduce combustibility. Boric acid (BA) and borax (BX) were used as boron compounds separately or in a mixtur e of 5:1 (BA:BX, w/w) in aqueous solutions of UF resin. A BA + BX mixt ure was also added to a 40% aqueous solution of trimethylolmelamine (T MM) (as a binding agent) and applied to the board surface. Fire-retard ant properties were determined according to the Japanese Industrial St andard JIS A 1322. Thickness swelling and water absorption levels were not changed remarkably by boron addition to UF resin, while static be nding and internal bond strengths were reduced to some extent. However , EX addition suppressed the adverse effect of BA on board strength, p robably by buffering its acidic pH to almost neutral levels, while BA reduced the glowing or smoldering effect of EX. Panels with or without added boron showed no ignition after the flame source was cut off aft er 13 min. Surface coating with the boron-added TMM improved fire reta rdance. To limit the reduction of strength properties due to boron add ition to the resin, fire-retardant surface coating can be applied to i mpart a required level of fire protection.