# US 8,770,294 B2 · Proppant having a polyamide imide coating > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,294 B2 - Document ID: US8770294B2 - Status: Granted - Kind: B2 - Application number: 13/186,942 - Filed: 2011-07-20 - Published: 2012-01-26 - Granted: 2014-07-08 - Earliest claimed: 2010-07-21 - Assignees: BASF SE - Applicants: Christopher Tanguay; Rajesh Kumar - Inventors: Christopher Tanguay; Rajesh Kumar - Web page: https://patentgrep.com/patent/US8770294B2 ## CPC - C09K 8/805: {Coated proppants} - C09K 8/62: Compositions for forming crevices or fractures - Y10T 428/2991: Coated - Y10T 428/2998: including synthetic resin or polymer - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A proppant comprises a particle and a polyamide imide coating disposed on the particle. A method of forming the proppant comprises the steps of providing the particle, providing the polyamide imide coating, and coating the particle with the polyamide imide coating. ## Claims ### Claim 1 A proppant for hydraulically fracturing a subterranean formation, said proppant comprising: A. a particle; and B. a polyamide imide coating disposed on said particle in an amount of from about 0.5 to about 7.5 percent by weight, based on 100 parts by weight of said particle. ### Claim 2 (depends on 1) The proppant as set forth in claim 1 wherein said particle is selected from the group of minerals, ceramics, sands, nut shells, gravels, mine tailings, coal ashes, rocks, smelter slag, diatomaceous earth, crushed charcoals, micas, sawdust, wood chips, resinous particles, polymeric particles, and combinations thereof. ### Claim 3 (depends on 1) The proppant as set forth in claim 1 wherein said polyamide imide coating is present in said proppant in an amount of from about 1.0 to about 6.0 percent by weight, based on 100 parts by weight of said particle. ### Claim 4 (depends on 1) The proppant as set forth in claim 1 that is thermally stable at temperatures greater than 100° C. ### Claim 5 (depends on 1) The proppant as set forth in claim 1 having a crush strength of 15% or less maximum fines less than sieve size 35 as measured by compressing a 9.4 g sample of said proppant in a test cylinder having a diameter of 1.5 inches for 1 hour at 7500 psi and 93° C. ### Claim 6 (depends on 1) The proppant as set forth in claim 1 wherein said polyamide imide coating comprises the reaction product of an isocyanate and an isocyanate-reactive component. ### Claim 7 (depends on 6) The proppant as set forth in claim 6 wherein said isocyanate comprises polymeric diphenylmethane diisocyanate and has an isocyanate (NCO) content of about 31.5 weight percent. ### Claim 8 (depends on 6) The proppant as set forth in claim 6 wherein said isocyanate and said isocyanate-reactive component react in the presence of a catalyst to form said polyamide imide coating. ### Claim 9 (depends on 8) The proppant as set forth in claim 8 wherein said catalyst is triethylamine. ### Claim 10 (depends on 8) The proppant as set forth in claim 8 wherein said isocyanate is reacted, to form said polyamide imide coating, in an amount of from about 0.01 to about 14 parts by weight, based on 100 parts by weight of said proppant. ### Claim 11 (depends on 6) The proppant as set forth in claim 6 wherein said isocyanate-reactive component is further defined as the reaction product of a carboxylic acid anhydride and an amine. ### Claim 12 (depends on 11) The proppant as set forth in claim 11 wherein said carboxylic acid anhydride comprises an aromatic carboxylic acid anhydride. ### Claim 13 (depends on 11) The proppant as set forth in claim 11 wherein said amine is selected from the group of polyether amines, amino silanes, and combinations thereof. ### Claim 14 (depends on 11) The proppant as set forth in claim 11 wherein said amine is reacted, to form said polyamide imide coating, in an amount of from about 0.001 to about 5 parts by weight, based on 100 parts by weight of said proppant. ### Claim 15 (depends on 6) The proppant as set forth in claim 6 wherein said isocyanate-reactive component comprises a carboxylic acid anhydride. ### Claim 16 (depends on 15) The proppant as set forth in claim 15 wherein said carboxylic acid anhydride is trimellitic anhydride. ### Claim 17 (depends on 15) The proppant as set forth in claim 15 wherein said carboxylic acid anhydride is reacted, to form said polyamide imide coating, in an amount of from about 0.06 to about 14 parts by weight, based on 100 parts by weight of said proppant. ### Claim 18 A method of forming a proppant for hydraulically fracturing a subterranean formation, said method comprising the steps of: A. providing a particle; B. providing a polyamide imide coating; and C. coating the particle with the polyamide imide coating particle in an amount of from about 0.5 to about 7.5 percent by weight, based on 100 parts by weight of the particle. ### Claim 19 (depends on 18) The method as set forth in claim 18 further comprising the step of heating the particle to a temperature greater than 150° C. prior to or simultaneous with the step of coating the particle with the polyamide imide coating. ### Claim 20 (depends on 18) The method as set forth in claim 18 further comprising the step of heating the proppant to further crosslink the polyamide imide coating. ### Claim 21 (depends on 18) The method as set forth in claim 18 further comprising the step of reacting an isocyanate and an isocyanate-reactive component to form the polyamide imide coating. ### Claim 22 (depends on 21) The method as set forth in claim 21 wherein the steps of reacting the isocyanate-reactive component and the isocyanate to form the polyamide imide coating and of coating the particle with the polyamide imide coating are collectively conducted in 20 minutes or less. ### Claim 23 (depends on 21) The method as set forth in claim 21 wherein the step of reacting the isocyanate-reactive component and the isocyanate to form the polyamide imide coating is conducted prior to the step of coating the particle with the polyamide imide coating. ### Claim 24 (depends on 21) The method as set forth in claim 21 wherein the isocyanate-reactive component comprises a carboxylic acid anhydride. ### Claim 25 (depends on 21) The method as set forth in claim 21 further comprising the step of reacting a carboxylic acid anhydride and an amine to form the isocyanate-reactive component. ### Claim 26 (depends on 21) The method as set forth in claim 21 wherein the step of reacting the isocyanate-reactive component and the isocyanate to form the polyamide imide coating is conducted simultaneous with the step of coating the particle with the polyamide imide coating. ### Claim 27 (depends on 26) The method as set forth in claim 26 further comprising the step of heating the proppant to further crosslink the polyamide imide coating. ### Claim 28 (depends on 27) The method as set forth in claim 27 wherein the steps of reacting the isocyanate-reactive component and the isocyanate to form the polyamide imide coating, of coating the particle with the polyamide imide coating, and of heating the proppant to further crosslink the polyamide imide coating are collectively conducted in 1.5 hours or less. ### Claim 29 A method of hydraulically fracturing a subterranean formation which defines a subsurface reservoir with a mixture comprising a carrier fluid and a proppant, the proppant comprising a particle and a polyamide imide coating disposed on the particle in an amount of from about 0.5 to about 7.5 percent by weight, based on 100 parts by weight of said particle, said method comprising the step of pumping the mixture into the subsurface reservoir to cause the subterranean formation to fracture. ### Claim 30 (depends on 29) The method as set forth in claim 29 wherein the polyamide imide coating comprises the reaction product of an isocyanate comprising polymeric diphenylmethane diisocyanate and an isocyanate-reactive component comprising trimellitic anhydride.