Fire Retardant Particleboards by Boric Acid and Lithium Compounds

Abstract

Particleboards were manufactured with adhesives containing fire-retardant chemicals. The physical and mechanical properties, and fire resistance properties of the boards were determined and discussed. The fire-retardant chemicals used were boric acid, lithium hydroxide, lithium dihydrogenphosphate and phosphoric acid, and the adhesive was urea-melamine-formaldehyde resin. The fire-retardant adhesive containing boric acid was stabilized by the addition of lithium hydroxide and lithium dihydrogenphosphate. The fire-retardant adhesives imparted excellent fire resistance to the particleboard. The fire-retardant particleboard containing 12-15% resin in oven dry wood particles passed 1st-2nd class extinguishments by JIS A 1322 and the board containing 6-12% resin also passed 2nd-3rd class extinguishments. Increasing the resin content in oven dry wood particles resulted in an effective increase in internal bond strength as well as MOR, a remarkable decrease in thickness swelling in water, and a slight increase in the equilibrium moisture content. Excepting a few results, the internal bond strength and the MOR of the fire retardant particleboards were greater than those of the untreated one, and the thickness swelling of the fire retardant particleboards in water was smaller than that of the untreated one.