Epoxy novolac coated ceramic particulate
AssigneeMinnesota Mining and Manufacturing Company
InventorsJames L. Gibb, James A. Laird, Leslie G. Berntson
Life of this patent
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Abstract
Ceramic particulate useful as a proppant in hydraulic fracturing and in gravel packing operations is provided which comprises a ceramic (sometimes vitreous) core surrounded by an epoxy resin coating. Novolac epoxy resin compounds without any substantial acid soluble filler are used to coat ceramic particulates similar to those disclosed in U.S. Pat. Nos. 4,680,230 and 4,632,876. The result is a product which combines the excellent solvent resistance of the ceramics with the acid resistance of the resin. The resin coating gives the added benefits of lower specific gravity and improved crush resistance.
Claims11
Coated ceramic particulate comprising:
- (A) fired ceramic particles made from raw materials which comprise:
- (1) mineral particulates comprising a ceramic which melts below 1300.degree. C., vitrifies upon cooling, and has a fired density of less than about 2.9 grams per cubic centimeter;
- and
- (2) sufficient binder to adhere the mineral particulates together after they have been formed into spheroids but before they have been fired;
- and
- (B) a coating 5 to 150 micrometers thick surrounding the ceramic particles which coating comprises cured epoxy cresol novolac resin containing less than one weight percent of fillers which are soluble in aqueous 12:3 molar ratio HCl-HF solutions.
Dependencies are inferred from the claim text.