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US 8,133,933 B2Granted
Binder compositions compatible with thermally reclaiming refractory particulate material from molds used in foundry applications
AssigneeGeorgia-Pacific Chemicals LLC
InventorsRichard Rediger, Edward Lucas
Life of this patent
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Abstract
Phenolic resin binder systems for sand molds, used in metal casting, which improve the quality of thermally reclaimed sand, are described. The substantial or complete elimination of calcium compounds (e.g., calcium stearate and calcium hydroxide, conventionally employed as a mold lubricant and a resin curing catalyst, respectively) allows the thermally reclaimed sand to be reused over multiple thermal reclamation cycles without the adverse effects previously encountered.
Claims22
A molding composition comprising:
- a refractory particulate material suitable for making a mold for casting metallic articles, wherein the refractory particulate material is at least partly coating with a resin mixture comprising:
- a phenolic novolac resin;
- a phenolic resole resin having a viscosity of from about 100 centipoise to about 5,000 centipoise at a temperature of 25° C.;
- hexamine;
- and
- less than 1,000 ppm by weight of calcium based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin wherein the phenolic novolac resin has a dry solids weight of from about 60% to about 99%, based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin, and
- wherein the phenolic resole resin contains from about 55% to about 75% solids.
4 more elements
A method for preparing a molding composition, comprising:
- combining a refractory particulate material and a solid phenolic novolac resin at conditions sufficient to melt said phenolic novolac resin and yield an at least partly coated refractory particulate material;
- and
- adding a phenolic resole resin and hexamine to said at least partly coated refractory particulate material to yield said molding composition, wherein the phenolic resin has a viscosity from about 100 centipoise to about 5,000 centipoise at a temperature of 25° C., wherein the phenolic resole resin contains from about 55% to about 75% solids,
- wherein said phenolic novolac resin and said phenolic resole resin are substantially free of calcium, such that the molding composition has less than 1,000 ppm by weight of calcium based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin, and
- wherein the phenolic novolac resin has a dry solids weight of from about 60% to about 99%, based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin.
2 more elements
Dependencies are inferred from the claim text.