Patent ID: 6713542
Filing Date: 2004-03-30
Classification: B27N,C08L

Abstract:
A method for producing a fire retardant cellulosic sheet material comprising the steps of:a) provide an aqueous solution of diammonium phosphate and monoammonium phosphate having a concentration of between about 0.325 and 1.0 moles per liter of diammonium phosphate and between 0.325 and 1.0 moles per liter of monoammonium phosphate and wherein the molar concentration of diammonium phosphate and monoammonium phosphate are about equal; b) adding a metal hydroxide to the solution of step a) in an amount between about 0.325 and 1.0 moles per liter to thereby provide a modified solution; c) providing a mass of cellulosic material and adding about 450 to 550 grams of cellulosic material per liter to the modified solution from step b); d) saturating the mass of cellulosic material with the modified solution of step b) by stirring until the mix reaches a uniform dark brown color; e) drying the saturated cellulosic material at a temperature between about 105 and 130 degrees C. until the cellulosic material has a uniform tan color and a moisture content of about 15%; f) providing a mass of glue; g) mixing the glue with a solution of monoammonium phosphate and diammonium phosphate to thereby provide a treated glue; h) mixing the dried saturated cellulosic material from step e) with the treated glue from step g); and i) heating the mixture of the dried saturated cellulosic material and treated glue from step h) at a temperature of about 120Â° C. to 195Â° C. under a pressure of about 350 to 400 psi to thereby provide a fire retardant particle board with enhanced flame and heat resistance.