# US 5,705,086 A · Refrigeration oils comprising esters of hindered alcohols > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,086 A - Document ID: US5705086A - Status: Granted - Kind: A - Application number: 08/633,266 - Filed: 1996-04-16 - Granted: 1998-01-06 - Earliest claimed: 1996-04-16 - Assignees: Mobil Oil Corporation - Inventors: Susan C. Ardito; Henry Ashjian; G. James Johnston - Web page: https://patentgrep.com/patent/US5705086A ## CPC - C10M 171/008: {Lubricant compositions compatible with refrigerants} - C09K 5/045: {containing only fluorine as halogen} - C10M 105/38: of polyhydroxy compounds - C09K 2205/24: Only one single fluoro component present - C10M: LUBRICATING COMPOSITIONS (well drilling compositions C09K8/02); USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION (mould release, i.e. separating, agents for metals B22C3/00, for plastics or substances in a plastic state, in general B29C33/56, for glass C03B40/02; textile lubricating compositions D06M11/00, D06M13/00, D06M15/00; immersion oils for microscopy G02B21/33) - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract Improved refrigeration lubricants useful in compression refrigeration units are esters, exhibit an excellent balance of performance characteristics, notably in the combination of good miscibility, hydrolytic stablity, wear resistance coupled with a viscosity within the range required in many commercial refrigeration units. These esters are of a hindered dihydric or trihydric alcohol such as trimethylolpentanediol and a fatty acid, where at least 80 number percent of the acyl groups are straight chain groups. ## Claims ### Claim 1 A composition suitable for use in a vapor compression refrigeration unit, the composition comprising a lubricant and a refrigerant comprising a hydrofluorocarbon; the lubricant comprising an ester of a hindered alcohol and at least one C.sub.4 -C.sub.18 fatty acid in which at least 70 numb percent of acyl groups from the fatty acid are straight chain acyl groups, wherein the hindered alcohol comprises at least one primary alcohol group and at least one secondary alcohol group, wherein no carbon atom that bears a hydroxy group is adjacent to either a methylene group or a methyl group, and wherein the lubricant has a 4 Ball Wear Volume (.mu.m.sup.3) of less than 1. ### Claim 2 (depends on 1) The composition of claim 1 in which the lubricant has the following properties: R-134a miscibility temperature: Less than -35.degree. C. Hydrolytic stability (.DELTA.TAN,mj KOH/g): Less than 1. ### Claim 3 (depends on 1) The composition of claim 1 wherein the lubricant has a viscosity at 40.degree. C. from 4 to 15 cSt. ### Claim 4 (depends on 1) The composition of claim 1 which comprises an ester of a hindered dihydric or trihydric alcohol and at least one C.sub.4 -C.sub.18 fatty acid, where the hindered alcohol comprises at least one primary alcohol group and at least one secondary alcohol group, and wherein no carbon atom that bears a hydroxy group is adjacent to either a methylene group or a methyl group. ### Claim 5 (depends on 1) The composition of claim 1 in which at least 80 number percent of the acyl groups from the fatty acid(s) are straight chain acyl groups. ### Claim 6 (depends on 1) The composition of claim 1 in which the fatty acid(s) is/are C.sub.5 -C.sub.9 acids. ### Claim 7 (depends on 4) The composition of claim 4 in which the esters are derived from a mixture of at least 80 weight percent straight chain C.sub.5 -C.sub.9 fatty acid(s) and 20 weight percent or less branch chain C.sub.5 -C.sub.9 fatty acids. ### Claim 8 (depends on 4) The composition of claim 4 in which the alcohol comprises 2,2,4-trimethylpentane-1,3-diol. ### Claim 9 (depends on 1) The composition of claim 1 in which the refrigerant comprises a hydrofluorocarbon having 1-2 carbon atoms and 1-6 fluorine atoms. ### Claim 10 (depends on 9) A composition according to claim 9 wherein the refrigerant comprises 60-100 weight percent of the hydrofluorocarbon. ### Claim 11 (depends on 9) A composition according to claim 9 wherein the refrigerant comprises R-134a. ### Claim 12 (depends on 9) A composition according to claim 9 wherein the refrigerant comprises 60-100 weight percent of R-134a. ### Claim 13 (depends on 9) A composition according to claim 9 wherein the refrigerant consists essentially of 1,1,1,2-tetrafluoroethane. ### Claim 14 (depends on 9) A composition according to claim 9 further comprising up to 50% of a second ester of a neopentyl polyol. ### Claim 15 (depends on 14) A composition of claim 14 in which the neopentyl polyol ester is derived from a branched chain fatty acid having 5-12 carbon atoms. ### Claim 16 (depends on 15) A composition according to claim 15 wherein the branched fatty acid is 2-ethylhexanoic acid. ### Claim 17 (depends on 15) A composition according to claim 15 comprising up to 25% of the second ester. ### Claim 18 (depends on 14) A composition according to claim 14 wherein the neopentyl polyol is monopentaerythritol. ### Claim 19 (depends on 9) A method for lubricating a vapor compression heat transfer unit comprising contacting moving parts of the unit with the composition of claim 9. ### Claim 20 (depends on 1) In a vapor compression cycle heat transfer unit comprising a lubricant, a refrigerant, a means for evaporating the refrigerant, a means for compressing the refrigerant, a means for condensing the refrigerant, and a means for expanding the refrigerant; the improvement wherein the lubricant is the lubricant of claim 1 and the refrigerant is hydrofluorocarbon.