Process for incremental coating of proppants for hydraulic fracturing and proppants produced therefrom
View Patent ↗A high strength composite particle comprised of a series of incrementally applied resin microlayer coatings such that each of the microlayer partial coatings are interleaved with each other is described. Methods of making the composite particles, as well as methods of using such particles as a proppant in oil and gas well hydraulic fracturing are also described.
1. A process for making a coated particle comprising applying a coupling agent to the surfaces of a particle heated to a temperature of between about 200° F. and 800° F.,
sputtering a resin coat onto a portion of the surface of the particle, thereby forming an island of resin covering less than the entire surface area of the particle, and
forming n additional islands of resin each covering less than the entire surface area of the particle by sputtering a number n of additional resin coats onto the particle in an incremental manner such that the n additional islands are interleafed with one another.
2. The process of claim 1 , further comprising sputtering a reinforcing agent onto at least one resin coat.
3. The process of claim 2 , wherein the reinforcing agent is nanoparticulate talc.
4. The process of claim 2 , wherein the reinforcing agent is a nanoparticle selected from the group consisting of natural clays, synthetic clays, layered clays, inorganic metal oxides, impact modifiers, and mixtures thereof.
5. The process of claim 1 , further comprising applying an encapsulation layer.
6. The process of claim 1 , wherein the particle is selected from the group consisting of silica particles, natural particles, metal particles, ceramic particles, synthetic organic particles, and sintered bauxite.
7. The process of claim 1 , wherein the resin is selected from the group consisting of novolac resins, epoxy resins, resole resins, phenol-aldehyde resins, urea-aldehyde resins, furfuryl alcohol resins, melamine resins, polyester resins, and alkyl resins.
8. The process of claim 1 , wherein the coupling agent is selected from the group consisting of organo-functional silanes, alkoxy zirconates, alkoxy titanates, or mixtures thereof.
9. The process of claim 1 , wherein the number n of additional resin coats is between 1 and 1000.
10. The process of claim 1 , wherein the number n of additional partial coats is between 5 and 100.
11. The process of claim 1 , wherein the resin coat is sputtered by vapor deposition, particle deposition, beam-induced evaporation/deposition, or thermal spraying.
12. The process of claim 1 , wherein the resin coat is sputtered onto the surface by an electrostatic sprayer.
13. The process of claim 1 , wherein the particle is heated to a temperature between 300° F. and 550° F.
14. The process of claim 1 , wherein the particle is heated to a temperature between about 300° F. and 550° F.