Patent ID: 8138234

Claim:
A method of forming a polyurethane composite material, the method comprising: providing at least a first polyol having first hydroxyl number in the range of about 320 mg KOH/g to about 600 mg KOH/g; and providing at least a second polyol having a second hydroxyl number which is at least about 20 mg KOH/g and is less than the first hydroxyl number; wherein the ratio of first polyol to second polyol is about 3 to about 80; wherein the first polyol and the second polyol are plant based polyester polyols; and wherein the first polyol and the second polyol, when mixed together, have a viscosity of about 1500 cP or less at 20° C.; providing at least one poly or di-isocyanate; providing an inorganic filler; providing a blowing agent consisting essentially of about 0.1 wt % to about 0.4 wt % water based upon the weight of the composite material; and mixing the first polyol, the second polyol, and the poly or di-isocyanate, the inorganic filler, and the blowing agent to form a reaction mixture, and extruding the reaction mixture into an extruded, foaming mixture; and containing the extruded mixture in a mold; and allowing the composite material to cure in the mold; wherein substantially no halogenated hydrocarbons are added; wherein the composite material comprises about 60 to about 85 weight percent of an the inorganic filler; and wherein the composite material has a density in the range of about 30 lb/ft 3 to about 80 lb/ft 3 .