Non-veining urethane resins for foundry sand casting

1. A method of manufacturing a metal shape comprising:

contacting a liquid metal and a surface of a foundry core under conditions wherein vein defects occur, wherein the surface of the foundry core comprises a foundry aggregate, a solid combustible-organic material and a polyurethane resin, and the foundry core layer being essentially free of an anti-veining agent, and wherein the solid combustible-organic material has a moisture content of less than 25 wt % and does not react with any isocyanate functionality;

cooling the liquid metal to a temperature below its melting point thereby forming a metal shape; and then

removing the foundry core from the metal shape.

2. The method of claim 1 , wherein the foundry core comprises the foundry aggregate, the combustible-organic solid and the polyurethane resin.

3. The method of claim 2 , wherein the foundry core is essentially free of the anti-veining agent.

4. The method of claim 1 , wherein the foundry aggregate comprises silica sand, olivine, zircon, chromite, and mixtures thereof.

5. The method of claim 1 , wherein the combustible-organic solid is selected from the group consisting of asphalt; bark; bitumen; powdered carbon; charcoal; bituminous coal; coke; flaked graphite; lignite; malt; crushed synthetic resin; pine resin; sawdust; powdered starch; glucose syrup, powdered sugar; tar; turpentine; wood chips; walnut shell; and a mixture thereof.

6. The method of claim 5 , wherein the combustible-organic material is selected from the group consisting of lignite, malt, glucose syrup, powdered sugar, and a mixture thereof.

7. The method of claim 6 , wherein the combustible-organic material is selected from the group consisting of lignite, glucose syrup, and a mixture thereof.

8. The method of claim 1 , wherein the polyurethane resin is the product of the polymerization of a polyol and an isocyanate.

9. The method of claim 8 , wherein the polyol is triethylene glycol.

10. The method of claim 1 further comprising forming the foundry core from a foundry mix that comprises the foundry aggregate, the combustible-organic solid, a polyol, and an isocyanate.

11. The method of claim 10 further comprising:

polymerizing the polyol and the isocyanate to form the polyurethane resin; and then

curing the polyurethane resin.

12. The method of claim 10 further comprising: coating the foundry core with a graphite wash.

13. The method of claim 1 , wherein the anti-veining agent is selected from the group consisting of iron oxides, titanium dioxide, lithium oxide, sodium bicarbonate, sodium carbonate, shale, fine ground glass particles, particles of wood pre-coated with a resin, granular slag, pulverized sea-coal, alkaline earth or alkaline metal fluoride, lithia-containing materials, and a mixture thereof.

14. The method of claim 1 further comprising limiting a maximum average expansion to less than 0.10 mm based on a Thermal Distortion Test.

15. The method of claim 14 , wherein the maximum average expansion is limited to less than 0.03 mm based on a Thermal Distortion Test.

16. A method of casting vein-free metal shapes comprising:

forming a foundry core that comprises a foundry aggregate, a solid combustible-organic material, a polyurethane resin, and that is essentially free of anti-veining agents, wherein the solid organic combustible-organic material has a moisture content of less than 25 wt % and does not react with any isocyanate functionality;

contacting a liquid metal with the foundry core under the conditions wherein vein defects occur; and then

removing a cooled metal shape from the foundry core; wherein the metal shape is free of or substantially free of vein defects.

17. The method of claim 16 , wherein determining conditions wherein vein defects occur comprises:

contacting a liquid metal with a foundry shape consisting of a polyurethane resin and a foundry aggregate; and

removing a cooled metal shape from the foundry shape; wherein the metal shape comprises vein defects.

18. The method of claim 16 , wherein the anti-veining agent is selected from the group consisting of iron oxides, titanium dioxide, lithium oxide, sodium bicarbonate, sodium carbonate, shale, fine ground glass particles, particles of wood pre-coated with a resin, granular slag, pulverized sea-coal, alkaline earth or alkaline metal fluoride, lithia-containing materials, and a mixture thereof.

19. A method of manufacturing a metal shape comprising:

contacting a liquid metal with a foundry core and a foundry mold, that individually comprise a foundry aggregate, a solid combustible-organic material and a polyurethane resin, and are essentially free of an anti-veining agent, wherein the solid combustible-organic material has a moisture content of less than 25 wt % and does not react with any isocyanate functionality; and then

separating the metal shape from the foundry core and foundry mold;

wherein the foundry core has a maximum average expansion of less than 0.03 mm based on a Thermal Distortion Test.

20. The method of claim 19 further comprising:

recycling the foundry aggregate from the separated foundry core and foundry mold, and

forming a recycled foundry core that is essentially free of an anti-veining agent from the recycled foundry aggregate.

21. The method of claim 20 , wherein forming the foundry core from the recycled foundry aggregate comprises:

admixing the recycled foundry aggregate, a combustible-organic material, a polyol, and an isocyanate;

polymerizing the polyol and isocyanate to form the polyurethane resin; and

shaping the admixture into the foundry core.

22. The method of claim 20 further comprising:

contacting a liquid metal with the recycled foundry core.

23. The method of claim 19 further comprising forming the foundry core and foundry mold from a mixture consisting essentially of the foundry aggregate, the combustible-organic material and the polyurethane resin.

24. The method of claim 19 , wherein the anti-veining agent is selected from the group consisting of iron oxides, titanium dioxide, lithium oxide, sodium bicarbonate, sodium carbonate, shale, fine ground glass particles, particles of wood pre-coated with a resin, granular slag, pulverized sea-coal, alkaline earth or alkaline metal fluoride, lithia-containing materials, and a mixture thereof.

25. The method of claim 19 , wherein the foundry core has a maximum average expansion of less than 0.02 mm based on a Thermal Distortion Test.

26. The method of claim 19 , wherein the foundry core has a maximum average expansion of less than 0.01 mm based on a Thermal Distortion Test.

27. The method of claim 19 , wherein the foundry core has a maximum average expansion of approximately 0.00 mm based on a Thermal Distortion Test.

28. A method of manufacturing a metal shape comprising:

contacting a liquid metal and a surface of a foundry core under conditions wherein vein defects occur, the surface of the foundry core comprises about 90 wt. % to about 99.9 wt. % of a foundry aggregate, about 0.005 wt. % to about 2.2 wt. % of a solid combustible-organic material, about 0.1 wt. % to about 10 wt % of a polyurethane resin, and a non-performance additive, and wherein the solid combustible-organic material has a moisture content of less than 25 wt % and does not react with any isocyanate functionality;

cooling the liquid metal to a temperature below its melting point thereby forming a metal shape; and then

removing the foundry core from the metal shape.

29. The method of claim 1 , wherein the solid combustible-organic material has a moisture content of less 15 wt. %.

30. The method of claim 1 , wherein the solid combustible-organic material has a moisture content of less 10 wt. %.

31. The method of claim 1 , wherein the solid combustible-organic material has a moisture content of less 5 wt. %.

32. The method of claim 1 , wherein the solid combustible-organic material comprises lignite.