Fire resistance wood-based boards, process for producing same and compositions useful therefor

Abstract

Aqueous solutions or slurries consisting essentially of water, ammonium hydrogen orthophosphate and urea wherein the amount of urea is from about one-half of the orthophosphate to about equal to the orthophosphate on a molar basis are useful in providing a fire-retardant coating on wood fibers when such fibers and a thermosetting resin are consolidated, under the simultaneous application of heat and pressure, to produce a panel having a density of at least 0.5 grams per cubic centimeter. The useful range of compositions thus contain a P:C atomic ratio of from about 1:1 to about 2:1. Such panels are improved by providing, prior to subjecting the fibers to heat and pressure, intimate contact between the fibers, the orthophosphate and urea composition and providing an amount of composition of at least 10% by weight of the fibers whereby upon the application of heat and pressure a chemical reaction occurs and a wood-based, fire-retardant panel having a Class II flame rating and improved structural properties is produced.

Dependencies are inferred from the claim text.