Lignite-urethane based resins for enhance foundry sand performance

Abstract

Described herein, in a preferred embodiment, is a leonardite-based polyurethane resin binder that may be used, among other applications, as a binder in combination with foundry aggregate, e.g., sand, for molding or casting metal parts. The binders described herein comprise a humic substance, preferably leonardite, first mixed with a foundry aggregate and then the humic-aggregate mixture is combined with a polymerizable polyol, an isocyanate, and a polymerization catalyst to make a polyurethane resin binder in situ in a foundry aggregate, such as sand. The lignite is added as a solid to the foundry aggregate, and improves the binder performance of the lignite-containing part of the binder components.

What is claimed is: 
     
         1 . An article of manufacture comprising: a metal casting;
 wherein the metal casting was made by a process comprising pouring a liquid metal into a foundry shape;   wherein the foundry shape was made from a foundry mix;   wherein the foundry mix was manufactured by admixing a lignite and a foundry aggregate to form a impregnated foundry aggregate;   admixing a polymerizable polyol with the impregnated foundry aggregate;   admixing a polymerizable isocyanate with the impregnated foundry aggregate; and   admixing a polymerization catalyst with the impregnated foundry aggregate.   
     
     
         2 . A method of making a metal casting comprising:
 admixing an organic solid and a foundry aggregate to form a impregnated foundry aggregate,   admixing a polymerizable polyol with the impregnated foundry aggregate,   admixing a polymerizable isocyanate with the impregnated foundry aggregate, and   admixing a polymerization catalyst with the impregnated foundry aggregate; to yield a foundry mix.   
     
     
         3 . The method of  claim 2 , wherein the organic solid is a lignite. 
     
     
         4 . The method of  claim 3 , wherein the lignite has a moisture content of less than about 35 wt. %. 
     
     
         5 . The method of  claim 4 , wherein the lignite has a moisture content of less than about 10 wt. %. 
     
     
         6 . The method of  claim 3 , wherein the lignite is leonardite. 
     
     
         7 . The method of  claim 4 , wherein the leonardite has an average particle size of about 500 nm to about 500 μm. 
     
     
         8 . The method of  claim 2 , wherein the polymerizable polyol is selected from the group consisting of a glycol having a molecular formula of HO—(CH 2 CH 2 O) x —H, where x is a value between 1 and about 25, a glycerol, and a mixture thereof. 
     
     
         9 . The method of  claim 8 , wherein the polymerizable polyol is triethyleneglycol. 
     
     
         10 . The method of  claim 2 , wherein the polymerizable isocyanate is a polymeric 4,4′-methylene bis(phenylisocyanate). 
     
     
         11 . The method of  claim 2 , wherein the polymerization catalyst is selected from the group consisting of 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), pentamethyldipropylenetriamine, bis(dimethylamino ethyl)ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine, tris (3-dimethylamino) propylamine, a liquid tertiary amines, and a mixture thereof. 
     
     
         12 . A foundry shape comprising a foundry aggregate, a lignite, and a urethane resin; wherein the urethane resin is admixed with a mixture of the foundry aggregate and the lignite. 
     
     
         13 . The foundry shape of  claim 12 , wherein the urethane resin is formed by admixing a polymerizable polyol, a polymerizable isocyanate, and a polymerization catalyst. 
     
     
         14 . The foundry shape of  claim 13 , wherein the urethane resin is formed in situ with the mixture of the foundry aggregate and the lignite. 
     
     
         15 . The foundry shape of  claim 14 , wherein a weight percent of the urethane resin in the foundry aggregate is about 0.1 to about 10, based on the weight of foundry aggregate. 
     
     
         16 . The foundry shape of  claim 12 , wherein a weight percentage of the lignite in the mixture of the foundry aggregate and the lignite is about 0.3, based on the weight of the foundry aggregate. 
     
     
         17 . A process of preparing a foundry shape comprising homogeneously mixing a impregnated foundry aggregate, a polymerizable polyol, a polymerizable isocyanate, and a catalysts to form a moldable mixture and forming the moldable mixture into a foundry mold or core.