Lignite-based urethane resins with enhanced suspension properties and foundry sand binder performance
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 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 mixed with the polymerizable polyol, thickening and dispersing agents as additives to improve the suspension quality and binder performance of the lignite-containing part of the binder components.
1. A foundry mix comprising:
a binder consisting essentially of a lignite-polyurethane resin that is a reaction product of a lignite-polyol suspension that is stable against separation, a polymerizable isocyanate, and a polyurethane polymerization catalyst; and
a foundry aggregate;
wherein the lignite-polyol suspension includes a dispersing agent and passes the static settling test.
2. The foundry mix of claim 1 consisting essentially of:
the lignite-polyurethane resin binder that comprises a reaction product of a lignite-polyol suspension that is stable against separation, the polymerizable isocyanate, and a polyurethane polymerization catalyst; and
the foundry aggregate.
3. The foundry mix of claim 2 , wherein the foundry mix comprises about 0.1 to about 10 parts by weight of the lignite-polyurethane resin and about 100 parts by weight of the foundry aggregate.
4. The foundry mix of claim 2 , wherein the polymerization catalyst is selected from 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, and a mixture thereof.
5. The foundry mix of claim 1 , wherein the lignite-polyurethane resin consists essentially of the reaction product of the lignite-polyol suspension, the polymerizable isocyanate, and the polyurethane polymerization catalyst.
6. The foundry mix of claim 5 , wherein the lignite-polyol suspension consists essentially of lignite, a polyol, a dispersing agent, and optionally a solvent.
7. The foundry mix of claim 1 , wherein the lignite comprises about 0 to about 10 wt. % water, based on the weight of dry lignite.
8. The foundry mix of claim 1 , wherein the lignite is leonardite.
9. The foundry mix of claim 6 , wherein the dispersing agent is a polymer selected from the group consisting of (A) a polymer selected from the group consisting of a monoesterified polyethylene glycol (PEG), a poly(acrylic acid) (PAA), a poly(methacrylic acid) (PMA), a poly(vinyl alcohol) (PVA), a poly(acrylamide), a poly(ethylene imine), a poly(diallyldimethyl ammonium halide), a poly(vinyl methyl ether), and a mixture thereof; (B) a polyvinylpyrrolidone (PVP); (C) a polyvinylpyrrolidone copolymer; and (D) a copolymer of a plurality of monomers selected from the group consisting of propylene oxide, vinyl acetate, vinyl amine, vinyl chloride, acrylamide, acrylonitrile, ethylene, propylene, ethylene oxide, lauryl methacrylate, methyl methacrylate, hydroxystearate, dimethylsiloxane, diallyldimethyl ammonium halide, ethylenimine, acrylic acid, and methacrylic acid; and (E) a mixture thereof.
10. The foundry mix of claim 9 , wherein the polymer is selected from the group consisting of from PEG-100 monostearate, PEG-125 monostearate, PEG-150 monostearate, and a mixture thereof.