Lignite-based urethane resins with enhanced suspension properties and foundry sand binder performance
View Patent ↗Described herein, in the 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, combined with a polymerizable isocyanate, a polymerizable polyol, and a polymerization catalyst to make a polyurethane resin binder in situ in a foundry aggregate, such as sand.
1. A lignite-isocyanate suspension comprising:
a lignite and an isocyanate; wherein the suspension is stable against separation for at least 24 hours, and the isocyanate group is about 15 weight percent (wt %) to about 90 wt % based on the total weight of the lignite-isocyanate suspension.
2. The suspension of claim 1 further comprising a stabilization agent.
3. A process of making a lignite-isocyanate suspension comprising:
admixing a lignite, an isocyanate, a dispersing agent, and a thickening agent at a temperature in a range of about 30 to about 150° C., wherein the isocyanate group is about 15 wt % to about 90 wt % based on the total weight of the lignite-isocyanate suspension.
4. A kit for binding an aggregate comprising:
a lignite-isocyanate suspension, and
a polymerizable polyol;
wherein the lignite-isocyanate suspension comprises a lignite, a polymerizable isocyanate, a dispersing agent, and a thickening agent, and the isocyanate group is about 15 wt % to about 90 wt % based on the total weight of the lignite-isocyanate suspension, and the suspension is stable against separation for at least 24 hours.
5. A foundry mix comprising
a lignite-polyurethane resin; and a foundry aggregate; wherein the lignite-polyurethane resin is manufactured from a lignite-isocyanate suspension and a polymerizable polyol; wherein the lignite-isocyanate suspension comprises about 15 wt % to about 90 wt % isocyanate group based on the total weight of the lignite-isocyanate suspension and lignite-isocyanate suspension is stable against separation for at least 24 hours.
6. An article of manufacture comprising: a metal casting;
wherein the metal casting is made by a process comprising pouring a liquid metal into a foundry shape;
wherein the foundry shape is made from a foundry mix;
wherein the foundry mix comprises a lignite-polyurethane resin and a foundry aggregate;
wherein the lignite-polyurethane resin is manufactured from a lignite-isocyanate suspension and a polymerizable polyol; and
wherein the lignite-isocyanate suspension comprises 15 wt % to about 90 wt % isocyanate group based on the total weight of the lignite-isocyanate suspension and the lignite-isocyanate suspension stable against separation for at least 24 hours.
7. The lignite-isocyanate suspension of claim 1 , wherein the lignite has a mean particle size in a range of about 50 nm to 500 μm.
8. The lignite-isocyanate suspension of claim 7 , wherein the lignite has a mean particle size in the range of about 500 nm to about 400 μm.
9. The lignite-isocyanate suspension of claim 8 , wherein the lignite has a mean particle size in the range of about 50 nm to about 200 μm.
10. The lignite-isocyanate suspension of claim 1 , further comprising a dispersing agent selected from the group consisting of polyethylene glycol/poly(oxyethylene) (PEG), polypropylene glycol, poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(acrylamide), poly(ethylene imine), poly(diallyldimethyl ammonium halide), and poly(vinyl methyl ether).
11. The suspension of claim 10 further comprising a thickening agent.
12. The suspension of claim 11 wherein the thickening agent is a homopolymer or copolymer selected from the group consisting of polyethylene glycol/poly(oxyethylene) (PEG), poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(acrylamide), poly(ethylene imine), poly(diallyldimethyl ammonium halide), and poly(vinyl methyl ether); a gelatin, and a polysaccharide.
13. The suspension of claim 12 , wherein the thickening agent is polyethylene glycol.
14. The suspension of claim 13 , wherein the polyethylene glycol has a weight average molecular weight in the range of about 1,000 to about 60,000 Dalton.
15. The suspension of claim 14 , wherein the polyethylene glycol has a weight average molecular weight in the range of about 2,000 to about 30,000 Dalton.
16. The suspension of claim 15 , wherein the polyethylene glycol has a weight average molecular weight in the range of about 4,000 to about 10,000 Dalton.
17. The lignite-isocyanate suspension of claim 10 , wherein the lignite has a mean particle size in a range of about 50 nm to 500 μm.
18. The lignite-isocyanate suspension of claim 17 , wherein the lignite has a mean particle size in the range of about 500 nm to about 400 μm.
19. The lignite-isocyanate suspension of claim 17 , wherein the lignite has a mean particle size in the range of about 50 nm to about 200 μm.
20. A process of making a lignite-isocyanate suspension comprising:
admixing a lignite and an isocyanate, wherein the suspension is stable against separation for at least 24 hours, and the isocyanate group is about 15 wt % to about 90 wt % based on the total weight of the lignite-isocyanate suspension.