Composite material including rigid foam with inorganic fillers

1. A synthetic lumber article formed from a composite material, said composite material comprising a polyurethane foam and a plurality of inorganic filler particles dispersed therein, said polyurethane foam formed from a reaction mixture comprising:

a first polyether polyol having a first molecular weight and a functionality of about 3 or less;

a second polyether polyol having a second molecular weight and a functionality of about 3 or greater, the second molecular weight less than said first molecular weight;

an aromatic hydrocarbon present in amount of up to about 5 weight percent based on the total weight of said composite material;

at least one polyisocyanate,

wherein a weight ratio of an amount of the first polyol in the reaction mixture to an amount of the second polyol in the reaction mixture is between about 1:1 to about 5:1, the plurality of inorganic filler particles is present in an amount of about 50 wt % to about 85 wt % based on the total weight of the composite material, the inorganic filler particles include fly ash and glass fibers, wherein a weight ratio of the fly ash to the glass fibers ranges from 6.87:1 to 7.77:1, and the composite material has a density of 52.1 lb/ft 3 or less and has an average flexural stress of at least 2330 psi.

2. The synthetic lumber article of claim 1 , wherein the density ranges from 30 lb/ft 3 to 52.1 lb/ft 3 .

3. The synthetic lumber article of claim 1 , wherein the glass fibers are present in an amount of 1 wt % to about 15 wt % based on the total weight of the composite material.

4. The synthetic lumber article of claim 1 , wherein the weight ratio of said first polyol to the second polyol is between about 1.5:1to about 3:1.

5. The synthetic lumber article in accordance with claim 1 , wherein the reaction mixture further comprises a blowing agent.

6. The synthetic lumber article of claim 5 , wherein the blowing agent comprises water.

7. The synthetic lumber article of claim 1 , wherein the reaction mixture further comprises a first catalyst comprising an amine compound.

8. The synthetic lumber article of claim 7 , wherein the reaction mixture further comprises a second catalyst comprising an organometallic compound.

9. A method of producing a composite material comprising a polyurethane foam and a plurality of inorganic particles dispersed therein, the method comprising:

mixing a first polyether polyol having a first molecular weight and a functionality of about 3 or less with a second polyether polyol having a second molecular weight and a functionality of greater than 3 to form a polyol mixture wherein a ratio of an amount of the first polyol in the mixture to an amount of the second polyol in the mixture is between about 1:1 to about 5:1, the second molecular weight less than the first molecular weight;

adding up to about 5 weight percent based on the total weight of the composite material of an aromatic hydrocarbon;

adding an amount of about 50 wt % to about 85 wt % of the plurality of inorganic filler particles to the mixture, the plurality of inorganic filler particles include fly ash and glass fibers, wherein a weight ratio of the fly ash to the glass fibers ranges from 6.87:1 to 7.77:1;

adding at least one polyisocyanate to the polyol mixture; and

extruding the mixture into a mold to form a composite material having a density of 52.1 lb/ft 3 or less and has an average flexural stress of at least 2330 psi.

10. The method of claim 9 further comprising adding a blowing agent to the mixture.

11. The method of claim 9 further comprising adding a first catalyst comprising an amine compound.

12. The method of claim 11 further comprising adding a second catalyst comprising an organometallic compound.