# US 6,296,782 B1 · Polyol ester lubricants for refrigerator compressors operating at high temperatures

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- Number: US 6,296,782 B1
- Document ID: US6296782B1
- Status: Granted
- Kind: B1
- Application number: 08/825,840
- Filed: 1997-04-04
- Granted: 2001-10-02
- Earliest claimed: 1992-06-03
- Assignees: Henkel Corporation
- Inventors: Nicholas E. Schnur; Eugene R. Zehler
- Web page: https://patentgrep.com/patent/US6296782B1

## CPC

- C09K 5/045: {containing only fluorine as halogen}
- C08G 75/029: Modification with organic compounds
- C08K 5/37: Thiols
- C08L 81/02: Polythioethers; Polythioether-ethers
- C10M 105/38: of polyhydroxy compounds
- C10M 105/42: Complex esters, i.e. compounds containing at least three esterified carboxyl groups and derived from the combination of at least three different types of the following five types of compound: monohydroxy compounds, polyhydroxy compounds, monocarboxylic acids, polycarboxylic acids and hydroxy carboxylic acids
- C10M 105/48: of carbonic acid
- C10M 129/10: having hydroxy groups bound to a carbon atom of a six-membered aromatic ring
- C10M 129/72: of polycarboxylic acids
- C10M 129/76: containing free hydroxy or carboxyl groups
- C10M 133/12: having amino groups bound to a carbon atom of a six-membered aromatic ring
- C10M 133/44: Five-membered ring containing nitrogen and carbon only
- C10M 135/06: Esters, e.g. fats
- C10M 135/18: thiocarbamic type, e.g. containing the groups [IMAGE cpc-sch-C10M-1027.gif]
- C10M 135/30: containing hydroxy groups; Derivatives thereof
- C10M 137/04: Phosphate esters
- C10M 137/08: Ammonium or amine salts
- C10M 169/04: Mixtures of base-materials and additives
- C10M 171/008: {Lubricant compositions compatible with refrigerants}
- H01B 3/307: {Other macromolecular compounds}
- C08L 23/06: Polyethylene
- C09K 2205/22: All components of a mixture being fluoro compounds
- C09K 2205/24: Only one single fluoro component present
- C10M 2203/06: Well-defined aromatic compounds
- C10M 2205/026: Butene
- C10M 2207/023: having hydroxy groups bound to carbon atoms of six-membered aromatic rings
- C10M 2207/024: having at least two phenol groups but no condensed ring
- C10M 2207/026: with tertiary alkyl groups
- C10M 2207/027: Neutral salts thereof
- C10M 2207/08: Aldehydes; Ketones
- C10M 2207/121: having hydrocarbon chains of seven or less carbon atoms
- C10M 2207/122: monocarboxylic
- C10M 2207/123: polycarboxylic
- C10M 2207/125: having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
- C10M 2207/128: containing hydroxy groups; Ethers thereof
- C10M 2207/129: having hydrocarbon chains of thirty or more carbon atoms
- C10M 2207/16: Naphthenic acids
- C10M 2207/22: Acids obtained from polymerised unsaturated acids
- C10M 2207/281: of (cyclo)aliphatic monocarboxylic acids
- C10M 2207/282: of (cyclo)aliphatic oolycarboxylic acids
- C10M 2207/283: of polyhydroxy compounds
- C10M 2207/2835: used as base material
- C10M 2207/284: of aromatic monocarboxylic acids
- C10M 2207/285: of aromatic polycarboxylic acids
- C10M 2207/286: of polymerised unsaturated acids
- C10M 2207/287: Partial esters
- C10M 2207/288: containing free carboxyl groups
- C10M 2207/289: containing free hydroxy groups
- C10M 2207/30: Complex esters, i.e. compounds containing at leasst three esterified carboxyl groups and derived from the combination of at least three different types of the following five types of compounds: monohydroxyl compounds, polyhydroxy xompounds, monocarboxylic acids, polycarboxylic acids or hydroxy carboxylic acids
- C10M 2207/301: used as base material
- C10M 2207/302: derived from the combination of monocarboxylic acids, dicarboxylic acids and dihydroxy compounds only and having no free hydroxy or carboxyl groups
- C10M 2207/325: used as base material
- C10M 2207/34: Esters having a hydrocarbon substituent of thirty or more carbon atoms, e.g. substituted succinic acid derivatives
- C10M 2209/084: Acrylate; Methacrylate
- C10M 2211/022: aliphatic
- C10M 2211/06: Perfluorinated compounds
- C10M 2215/04: having amino groups bound to acyclic or cycloaliphatic carbon atoms
- C10M 2215/06: having amino groups bound to carbon atoms of six-membered aromatic rings
- C10M 2215/064: Di- and triaryl amines
- C10M 2215/065: Phenyl-Naphthyl amines
- C10M 2215/066: Arylene diamines
- C10M 2215/067: Polyaryl amine alkanes
- C10M 2215/068: having amino groups bound to polycyclic aromatic ring systems, i.e. systems with three or more condensed rings
- C10M 2215/08: Amides [having hydrocarbon substituents containing less than thirty carbon atoms]
- C10M 2215/082: containing hydroxyl groups; Alkoxylated derivatives
- C10M 2215/086: Imides [having hydrocarbon substituents containing less than thirty carbon atoms]
- C10M 2215/102: Ureas; Semicarbazides; Allophanates
- C10M 2215/12: Partial amides of polycarboxylic acids
- C10M 2215/14: Containing carbon-to-nitrogen double bounds, e.g. guanidines, hydrazones, semicarbazones
- C10M 2215/22: Heterocyclic nitrogen compounds
- C10M 2215/221: Six-membered rings containing nitrogen and carbon only
- C10M 2215/223: Five-membered rings containing nitrogen and carbon only
- C10M 2215/224: Imidazoles
- C10M 2215/225: the rings containing both nitrogen and oxygen
- C10M 2215/226: Morpholines
- C10M 2215/26: Amines
- C10M 2215/28: Amides; Imides
- C10M 2215/30: Heterocyclic compounds
- C10M 2217/028: containing monomers having an unsaturated radical bound to a nitrogen-containing hetero ring
- C10M 2217/06: Macromolecular compounds obtained by functionalisation op polymers with a nitrogen containing compound
- C10M 2219/02: Sulfur-containing compounds obtained by sulfurisation with sulfur or sulfur-containing compounds
- C10M 2219/022: of hydrocarbons, e.g. olefines
- C10M 2219/024: of esters, e.g. fats
- C10M 2219/044: Sulfonic acids, Derivatives thereof, e.g. neutral salts
- C10M 2219/062: having carbon-to-sulfur double bonds
- C10M 2219/066: Thiocarbamic type compounds
- C10M 2219/068: Thiocarbamate metal salts
- C10M 2219/082: containing sulfur atoms bound to acyclic or cycloaliphatic carbon atoms
- C10M 2219/087: containing hydroxy groups; Derivatives thereof, e.g. sulfurised phenols
- C10M 2219/088: Neutral salts
- C10M 2219/089: Overbased salts
- C10M 2219/10: Heterocyclic compounds containing sulfur, selenium or tellurium compounds in the ring
- C10M 2219/102: containing sulfur and carbon only in the ring
- C10M 2219/104: containing sulfur and carbon with nitrogen or oxygen in the ring
- C10M 2219/106: Thiadiazoles
- C10M 2219/108: Phenothiazine
- C10M 2223/04: Phosphate esters
- C10M 2223/041: Triaryl phosphates
- C10M 2223/042: Metal salts thereof
- C10M 2223/043: Ammonium or amine salts thereof
- C10M 2223/045: Metal containing thio derivatives
- C10M 2223/047: Thioderivatives not containing metallic elements
- C10M 2223/06: having phosphorus-to-carbon bonds
- C10M 2223/061: Metal salts
- C10M 2223/065: containing sulfur
- C10M 2227/061: Esters derived from boron
- C10M 2229/02: Unspecified siloxanes; Silicones
- C10M 2229/05: containing atoms other than silicon, hydrogen, oxygen or carbon
- C10N 2010/10: Groups 5 or 15
- C10N 2020/069: {Linear chain compounds}
- C10N 2020/071: {Branched chain compounds}
- C10N 2020/101: {Containing Hydrofluorocarbons}
- C10N 2040/00: Specified use or application for which the lubricating composition is intended
- C10N 2040/30: Refrigerators lubricants {or compressors lubricants}
- C10N 2040/32: Wires, ropes or cables lubricants
- C10N 2040/34: Lubricating-sealants
- C10N 2040/36: Release agents {or mold release agents}
- C10N 2040/38: {Conveyors or chain belts}
- C10N 2040/40: {Generators or electric motors in oil or gas winning field}
- C10N 2040/42: {Flashing oils or marking oils}
- C10N 2040/44: {Super vacuum or supercritical use}
- C10N 2040/50: {Medical uses}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- 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)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- C10N: INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS

## Abstract

A high quality lubricant for compressors operated during at least part of their compression cycle at temperatures above and below normal human comfort temperatures, especially those using chlorine free hydrofluorocarbon refrigerant working fluids, is provided by mixed esters of hindered polyols, most desirably pentaerythritol, with a mixture of carboxylic acids including iso-pentanoic acid, trimethylhexanoic acid, and preferably n-pentanoic acid.

## Claims

### Claim 1

A refrigerant working fluid consisting essentially of a substantially chlorine-free, fluoro-group containing organic refrigerating heat transfer fluid and a balance of a composition of matter suitable for serving as a lubricant or lubricant base stock, said composition forming a single phase with refrigerating heat transfer fluid between −55° C. and +71° C. and consisting essentially of polyol ester molecules that are made by reacting (i) a mixture of alcohol molecules selected from the group consisting of trimetbylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and tritrimethylolpropane in which at least about 75% of the hydroxyl groups in the mixture of alcohols are moieties of PE molecules and (ii) a mixture of acid molecules selected from the group consisting of all the straight and branched chain monobasic carboxylic acids with from four to twelve carbon atoms each, with the alcohol moieties and acyl groups in the mixture of esters selected subject to the further constraints that (a) a total of at least about 5% of the acyl groups in the mixture are acyl groups from iC5 acid; (b) the ratio of the percent of acyl groups in the mixture that contain 8 or more carbon atoms and are unbranched to the percent of acyl groups in the mixture that are both branched and contain not more than five carbon atoms is not greater than about 1.56; (c) the percent of acyl groups in the ester mixture that contain at least nine carbon atoms whether branched or not is not greater than about 81; (d) a total of at least about 20% of the acyl groups in the mixture are from 3,5,5-trimethylhexanoic acid; (e) at least 98% of the monobasic acid molecules in the acid mixture consist of molecules having either five or nine carbon atoms each; and (f) at least about 29% of the acyl groups are from one of the trimethylhexanoic acids and not more than about 0.4% of the acyl groups in the mixture are from dibasic acids.

### Claim 2 (depends on 1)

A refrigerant working fluid according to claim 1 and consisting essentially of a substantially chlorine-free, fluoro-group containing organic refrigerating heat transfer fluid and a balance of a composition of matter suitable for serving as a lubricant or lubricant base stock, said composition forming a single phase with refrigerating heat transfer fluid between −55° C. and +71° C. and consisting essentially of polyol estermolecules that are made by reacting (i) a mixture of alcohol molecules selected from the groups consisting of trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and tritrimethylolpropane in which at least about 75% of the hydroxyl groups in the mixture of alcohols are moieties of PE molecules and (ii) a mixture of acid molecules selected from the group consisting of all straight and branched chain monobasic carboxylic acids with from four to twelve carbon atoms each, with the alcohol moieties and acyl groups in the mixture of esters selected subject to the further constraints that (a) a total of at least about 10% of the acyl groups in the mixture are acyl groups from iC5 acid; (b) the ratio of the percent of acyl groups in the mixture that contain 8 or more carbon atoms and are unbranched to the percent of acyl groups in the mixture that are both branched and contain not more than five carbon atoms is not greater than about 1.00; (c) the percent of acyl groups in the ester mixture that contain at least nine carbon atoms whether branched or not is not greater than about 67; (d) a total of at least about 20% of the acyl groups in the mixture are from 3,5,5-trimethylhexanoic acid; (e) at least 98% of the monobasic acid molecules in the acid mixture consist of molecules having either five or nine carbon atoms each; and (f) at least about 29% of the acyl groups are from one of the trimethylhexanoic acids and not more than about 0.4% of the acyl groups in the mixture are from dibasic acids.

### Claim 3 (depends on 2)

A refrigerant working fluid according to claim 2 in which the composition of matter further includes up to 8% by weight of one or more additives selected from the group consisting of oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour and floc point depressants, detergents, dispersants, anti-foaming agents, anti-wear agents, and extreme pressure resistant additives.

### Claim 4 (depends on 1)

A refrigerant working fluid according to claim 1 in which the composition of matter further includes up to 8% by weight of one or more additives selected from the group consisting of oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour and floc point depressants, detergents, dispersants, antifoaming agents, anti-wear agents, and extreme pressure resistant additives.

### Claim 5 (depends on 1)

A refrigerant working fluid according to claim 1 in which the heat transfer fluid is selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethanes and mixtures thereof.

### Claim 6 (depends on 2)

A refrigerant working fluid according to claim 2 in which the heat transfer fluid is selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethanes and mixtures thereof.

### Claim 7 (depends on 1)

A refrigerant working fluid according to claim 1 in which the heat transfer fluid is 1,1,1,2-tetrafluoroethane.

### Claim 8 (depends on 1)

A process for operating a refrigerator comprising cyclic compression, liquefaction, expansion, and evaporation of a refrigerant working fluid according to claim 1.

### Claim 9

A refrigerant working fluid consisting essentially of a substantially chlorine-free, fluoro-group containing organic refrigerating heat transfer fluid and a balance of a composition of matter suitable for serving as a lubricant or lubricant base stock, said composition forming a single phase with refrigerating heat transfer fluid between −55° C. and 71° C. and consisting essentially of polyol ester molecules that are made by reacting (i) a mixture of alcohol molecules selected from the group consisting of trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and tritrimethylolpropane in which at least about 85% of the hydroxyl groups in the mixture of alcohols are moieties of PE molecules and (ii) a mixture of acid molecules selected from the group consisting of all the straight and branched chain monobasic carboxylic acids with from four to twelve carbon atoms each, with the alcohol moieties and acyl groups in the mixture of esters selected subject to further constraints that (a) a total of at least about 7% of the acyl groups in the mixture are acyl groups from iC5 acid; (b) the ration of the percent of acyl groups in the mixture that contain 8 or more carbon atoms and are unbranched to the percent of acyl groups in the mixture that are both branched and contain not more than five carbon atoms is not greater than about 1.21; (c) the percent of acyl groups in the ester mixture that contain at least nine carbon atoms whether branched or not is not greater than about 67; (d) a total of at least about 20% of the acyl groups in the mixture are from 3,5,5-trimethylhexanoic acid; (e) at least 98% of the monobasic acid molecules in the acid mixture consist of molecules having either five or nine carbon atoms each; and (f) at least about 29% of the acyl groups are from one of the trimethylhexanoic acids and not more than about 0.4% of the acyl groups in the mixture are from dibasic acids.

### Claim 10 (depends on 9)

A refrigerant working fluid according to claim 9 and consisting essentially of a substantially chlorine-free, fluoro-group containing organic refrigerating heat transfer fluid and a balance of a composition of matter suitable for serving as a lubricant or lubricant base stock, said composition forming a single phase with refrigerating heat transfer fluid between −55° C. and +175° C. and consisting essentially of polyol ester molecules that are made by reacting (i) a mixture of alcohol molecules selected from the group consisting of trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and tritrimethylolpropane in which at least about 95% of the hydroxyl groups in the mixture of alcohols are moieties of PE molecules and (ii) a mixture of acid molecules selected from the group consisting of all the straight and branched chain monobasic carboxylic acids with from four to twelve carbon atoms each, with the alcohol moieties and acyl groups in the mixture of esters selected subject to the further constraints that (a) a total of at least about 13% of the acyl groups in the mixture are acyl groups from iC5 acid; (b) the ratio of the percent of acyl groups in the mixture that contain 8 or more carbon atoms and are unbranched to the percent of acyl groups in the mixture that are both branched and contain not more than five carbon atoms is not greater than about 1.00; (c) the percent of acyl groups in the ester mixture that contain at least nine carbon atoms whether branched or not is not greater than about 67; (d) a total of at least about 20% of the acyl groups in the mixture are from 3,5,5-trimethylhexanoic acid; (3) at least 98% of the monobasic acid molecules in the acid mixture consist of molecules having either five or nine carbon atoms each; and (f) at least about 35% of the acyl groups in the mixture are from one of the trimethylhexanoic acids and not more than about 0.4% of the acyl groups in the mixture are from dibasic acids.

### Claim 11 (depends on 9)

A refrigerant working fluid according to claim 9 in which the composition of matter further includes up to 8% by weight of one or more additives selected from the group consisting of oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour and floc point depressants, detergents, dispersants, anti-foaming agents, anti-wear agents, and extreme pressure resistant additives.

### Claim 12 (depends on 9)

A refrigerant working fluid according to claim 9 in which the heat transfer fluid is selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethanes and mixtures thereof.

### Claim 13 (depends on 9)

A process for operating a refrigerator comprising cyclic compression, liquefaction, expansion, and evaporation of a refrigerant working fluid according to claim 9.

### Claim 14

A refrigerant working fluid consisting essentially of a substantially chlorine-free, fluoro-group containing organic refrigerating heat transfer fluid and a balance of a composition of matter suitable for serving as a lubricant or lubricant base stock, said composition forming a single phase with refrigerating heat transfer fluid between −55° C. and +71° C. and consisting essentially of polyol ester molecules that are made by reacting (i) a mixture of alcohol molecules selected from the group consisting of trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and tritrimethylolpropane in which at least about 90% of the hydroxyl groups in the mixture of alcohols are moieties of PE molecules and (ii) a mixture of acid molecules selected from the group consisting of all the straight and branched chain monobasic carboxylic acids with from four to twelve carbon atoms each, with the alcohol moieties and acyl groups in the mixture of esters selected subject to the further constraints that (a) a total of at least about 10% of the acyl groups in the mixture are acyl groups from iC5 acid; (b) the ratio of the percent of acyl groups in the mixture that contain 8 or more carbon atoms and are unbranched to the percent of acyl groups in the mixture that are both branched and contain not more than five carbon atoms is not greater than about 1.00; (c) the percent of acyl groups in the ester mixture that contain at least nine carbon atoms whether branched or not is not greater than about 49; (d) a total of at least about 20% of the acyl groups in the mixture are from 3,5,5-trimethylhexanoic acid; (e) at least 98% of the monobasic acid molecules in the acid mixture consist of molecules having either five or nine carbon atoms each; and (f) at least about 29% of the acyl groups are from one of the trimethylhexanoic acids and not more than about 0.4% of the acyl groups in the mixture are from dibasic acids.

### Claim 15 (depends on 14)

A refrigerant working fluid according to claim 14 in which the composition of matter further includes up to 8% by weight of one or more additives selected from the group consisting of oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour and floe point depressants, detergents, dispersants, anti-foaming agents, anti-wear agents, and extreme pressure resistant additives.

### Claim 16 (depends on 14)

A refrigerant working fluid according to claim 14 in which the heat transfer fluid is selected from the group consisting of pentafluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, tetrafluoroethanes and mixtures thereof.