Reciprocating Compressor Lubricant

Abstract

A refrigeration lubricant having at least one thiophosphorus additive for use in hydrofluorocarbon refrigeration systems, the thiophosphorus additive being capable of improving the stability and metal and / or refrigerant compatibility of the refrigeration lubricant.

Description

[Technical field]

[0001] The disclosed technology relates to lubricants for use in reciprocating compressor systems where the refrigerant includes a hydrofluorocarbon ("hydrofluorocarbon, HFC") refrigerant. [Background technology]

[0002] Lubricants for use in low backpressure / low temperature conditions have successfully utilized a combination of corrosion inhibitors or metal deactivators and antioxidants to inhibit the oxidation and corrosivity of the lubricant-refrigerant combination in reciprocating compressors. In medium backpressure / medium temperature reciprocating compressors with an operating envelope in which the condensing temperature is in the range of 100-140°F (37.8-60.0°C) and the evaporating temperature is in the range of 5-55°F (-15-12.8°C), the lubricants are not stable and may result in an increase in the acid number and / or darkening of the lubricant. An increase in the acid number of the lubricant may result in degradation (deposits, oxidation, and / or corrosion) of the compressor metal parts, including parts made of steel, aluminum, or copper. This situation may be exacerbated in copper systems if sulfur-containing additives are used in the lubricant, as it is known that sulfur can contribute to copper corrosion. Thus, prior to the present technology, sulfur-containing metal passivators were avoided in refrigeration systems with copper parts. Summary of the Invention

[0003] The disclosed technology provides lubricants that have improved stability in high pressure / high temperature environments, thereby resulting in reduced deterioration of compressor metal parts. Thus, refrigeration lubricants are disclosed that include at least one oil of lubricating viscosity that is an oxygenate and at least one thiophosphorus additive. Despite having sulfur, these thiophosphorus additives are surprisingly effective in reducing metal corrosion, including copper corrosion, compared to refrigeration lubricants that have sulfur-containing metal passivators, such as dimercaptothiadiazole.

[0004] The at least one thiophosphorus additive may be a thiophosphorus acid, salt, ester, or combination thereof. Suitable examples of thiophosphorus esters include, but are not limited to, alkyl-substituted thiophosphate esters, such as dialkyl dithiophosphate esters. Suitable examples of thiophosphorus salts include, but are not limited to, alkyl-substituted thiophosphate salts, such as triphenylthiophosphate. In some embodiments, the at least one thiophosphorus additive may include dialkyl dithiophosphate esters and / or triphenylthiophosphate (O,O,O-triphenyl phosphorothioate). The at least one thiophosphorus additive may be present at 0.1 to 2 wt. %, based on the total weight of the refrigeration lubricant.

[0005] The refrigeration lubricant disclosed herein may further comprise at least one phosphorus anti-wear additive. Suitable phosphorus anti-wear additives include, but are not limited to, alkenyl phosphite, butylated triphenyl phosphate, tricresyl phosphate, dimethyl octadecyl phosphonate, or combinations thereof. The at least one phosphorus anti-wear additive may be present at 0.1 to 4 wt. %, based on the total weight of the refrigeration lubricant.

[0006] In some embodiments, the refrigeration lubricant may further promote at least one metal passivator and / or at least one corrosion inhibitor, such as dimercaptothiadiazole and / or benzotriazole. The refrigeration lubricant of claim 10, wherein the at least one metal passivator and / or the at least one corrosion inhibitor is substantially free of sulfur, such as benzotriazole.

[0007] In yet another embodiment, the refrigeration lubricant may further comprise at least one other additive that is an antifoaming agent, an antioxidant, an acid scavenger, or a combination thereof. Suitable antifoaming agents include polydimethylsiloxanes. Suitable antioxidants include alkylated ester phenols, alkaryl amines, di-tertbutyl cresol, or a combination thereof. Suitable acid scavengers include epoxides.

[0008] Antifoaming agents, if present, may be present at 0.01 to 0.5% by weight, based on the total weight of the refrigeration lubricant.Antioxidants, if present, may be present at 0.05 to 1% by weight, based on the total weight of the refrigeration lubricant.

[0009] Suitable oxygenates for use in refrigeration lubricants include at least one alcohol, ester oil, ether oil, or combinations thereof. In some embodiments, the oxygenate may include at least one polyol ester, at least one polyalkylene glycol, or combinations thereof. In yet other embodiments, the oxygenate may include at least one polyol ester, such as a polyol ester derived from a reaction mixture of neopentyl glycol, pentaerythritol, and 2-ethylhexanoic acid.

[0010] The lubricant composition described above may be used in combination with a hydrofluorocarbon ("HFC") refrigerant. Thus, disclosed is a composition comprising a refrigeration lubricant as described above and at least one hydrofluorocarbon ("HFC") refrigerant. Suitable HFC refrigerants include, but are not limited to, R32, R-134a, R-404A, R-410A, or combinations thereof.

[0011] Such compositions comprising a refrigeration lubricant and an HFC refrigerant are suitable for use in a refrigeration system comprising a compressor and a condenser. The compressor may be a reciprocating compressor. In some embodiments, the refrigeration system comprises copper and / or copper alloy components. The disclosed compositions are suitable for use in refrigeration systems having a condensing temperature in the range of 100-140°F (37.8-60.0°C) and an evaporating temperature in the range of 5-55°F (-15-12.8°C).

[0012] Also disclosed is a method for improving the metal compatibility and / or reducing metal corrosion of a composition comprising a refrigeration lubricant comprising at least one oil of lubricating viscosity that is an oxygenate by adding at least one thiophosphorus additive to the refrigeration lubricant. The composition may further comprise at least one hydrofluorocarbon ("HFC") refrigerant, such as R-32, R-134a, R-404A, or R-410A. In some embodiments, a method for improving the compatibility and / or stability of a refrigeration lubricant with a hydrofluorocarbon ("HFC") refrigerant is disclosed. The method may include adding at least one thiophosphorus additive to the refrigeration lubricant.

[0013] 1. Use of a thiophosphorus additive in a composition comprising a refrigeration lubricant comprising at least one oil of lubricating viscosity that is an oxygenate to improve metal compatibility and / or reduce metal corrosion of the composition and / or improve the compatibility and / or stability of the refrigeration lubricant with a hydrofluorocarbon ("HFC") refrigerant, e.g., R-32, R-134a, R-404A, or R-410A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Various preferred features and embodiments are described below by way of non-limiting examples: Refrigeration lubricants comprising at least one oil of lubricating viscosity that is an oxygenate and at least one thiophosphorus additive, which have good metal compatibility and / or reduce corrosion of metals, including copper-containing metals.

[0015] Oxygenate As used herein, oxygenates refer to organic compounds that contain oxygen as one of their components. These include organic compounds that have at least one aprotic or protic oxygen for every six carbon atoms. Oxygenates also include organic compounds that have at least one aprotic or protic oxygen for every seven carbon atoms, or one aprotic or protic oxygen for every eight carbon atoms, or at least one aprotic or protic oxygen for every twelve carbon atoms. Oxygenates also include organic compounds that have at least one aprotic or protic oxygen for every sixteen carbon atoms, or one aprotic or protic oxygen for every twenty carbon atoms.

[0016] The oxygenates can include, for example, alcohols, ester oils, and ether oils. The oxygenates can be present in the refrigeration lubricant as at least 45% by weight of an oil of lubricating viscosity, based on the total weight of the refrigeration lubricant. In some examples, the oxygenates can be present at at least 50% by weight to at least 80% by weight. In other embodiments, the oxygenates can be present at at least 80% by weight to at least 90% by weight, or at least 95% by weight. In still other embodiments, the oxygenates can be present at at least 96%, 97%, 98% or at least 99% by weight, based on the total weight of the lubricant composition.

[0017] Alcohols suitable for use as oils of lubricating viscosity include monohydric alcohols such as ethanol, methanol, propylene alcohol derivatives such as n-butanol and tert-butanol, and isopropyl alcohol, and higher branched alcohols include pentanol, hexanol, heptanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol, and combinations thereof. Examples of branched alcohols include 2-ethylhexanol, isooctanol, isodecanol, and isododecanol. As used herein, alcohol also includes polyols such as propylene glycol, ethylene glycol, 1,4-butanediol, pentaerythritol, trimethylolpropane, and the like.

[0018] Suitable ethers for use as oils of lubricating viscosity include those produced from petrochemical and renewable feedstocks. Examples include methyl tertiary butyl ether (MTBE), tertiary amyl methyl ether (TAME), ethyl tertiary butyl ether (ETBE) and tertiary amyl ethyl ether (TAEE). Other examples of ethers include tert-hexyl methyl ether (THEME) and diisopropyl ether. Polyethers are also contemplated herein under the term "ether" and include, for example, diethylene glycol dibutyl ether. Low molecular weight oligomers of polyalkylene glycols (i.e., polyalkylene oxides), including polyethylene glycol (PEG), polypropylene glycol (PPG), and mixed polymers thereof, may also be suitable.

[0019] Ester oils suitable for use as oils of lubricating viscosity include esters of monocarboxylic acids and monohydric alcohols, di-esters of diols and monocarboxylic acids and di-esters of dicarboxylic acids and monohydric alcohols, polyol esters of monocarboxylic acids, and polyesters of monohydric alcohols and polycarboxylic acids, and mixtures thereof. Esters can be broadly divided into two categories: synthetic and natural.

[0020] Synthetic esters suitable for use as oils of lubricating viscosity may include esters of monocarboxylic acids (such as acetic acid, propionic acid, neopentanoic acid, 2-ethylhexanoic acid, and the like) and dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, linoleic acid, alkyl malonic acids, and alkenyl malonic acids) with any of a variety of monohydric alcohols (e.g., butyl alcohol, pentyl alcohol, neopentyl alcohol, hexyl alcohol, octyl alcohol, iso-octyl alcohol, nonyl alcohol, decyl alcohol, isodecyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, diecocyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid. Other synthetic esters include those containing C5-C 12Included are those made from monocarboxylic acids and polyols and polyol ethers, such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. The esters can also be monoesters of monocarboxylic acids and monohydric alcohols.

[0021] Suitable esters also include esters of hydroxy-substituted carboxylic acids, such as tartaric acid, malic acid, glycolic acid, and hydroxy fatty acids (eg, 12-hydroxystearic acid), in combination with monohydric alcohols, as discussed above.

[0022] Natural (or bio-based) esters refer to materials derived from renewable biological resources, organisms, or entities, and are distinct from materials derived from petroleum or equivalent raw materials. Suitable natural esters in heat transfer fluids include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglyceride esters, such as fatty acid methyl esters (or FAMEs). Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related materials. Other triglyceride sources include, but are not limited to, algae, tallow, and zooplankton.

[0023] In some embodiments, the oil of lubricating viscosity is an oxygenate comprising at least one polyol ester ("polyolester, POE") oil, the polyol ester oil comprising a polyol esterified with at least one (mono)carboxylic acid having at least 5 carbon atoms. In yet other embodiments, the polyol ester oil comprises a polyol esterified with a mixture of (mono)carboxylic acids or their anhydrides, the (mono)carboxylic acids or anhydrides individually having from 5 to 13 carbon atoms. The C5 carboxylic acids or anhydrides are preferably C6 to C8 carboxylic acids or anhydrides. 13Suitable ratios for the carboxylic acid or anhydride include, but are not limited to, 95:5 to 5:95. In yet another embodiment, the mixture of (mono)carboxylic acids or their anhydrides comprises at least three C5-C 13 carboxylic acids or anhydrides. Suitable polyols include, but are not limited to, trimethylolpropane, dipentaerythritol, neopentyl glycol, monopentaerythritol, polypentaerythritol, or combinations thereof. In some embodiments, the POE may include esters and / or complex esters of aromatic polycarboxylic acids or their anhydrides. The complex esters may be composed of oligomeric units composed of polyols (which may include, but are not limited to, trimethylolpropane, dipentaerythritol, neopentyl glycol, monopentaerythritol, polypentaerythritol) and polyacids or acid anhydrides (which may include, but are not limited to, succinic acid, glutaric acid, adipic acid, citric acid, trimellitic acid, pyromellitic acid), or any mixture thereof. The complex esters may be fully or partially capped with functional (mono)carboxylic acids or (mono)alkyl alcohols, or glycol ethers capped singly, or any mixture thereof.

[0024] As used herein, "(mono)carboxylic acid" or "(mono)alkyl alcohol" means that the (mono) is optional, i.e., the carboxylic acid or alkyl alcohol compound may be mono or poly. However, in some embodiments of the disclosed technology, only monocarboxylic acids and / or monoalkyl alcohols are present.

[0025] In some embodiments, the oxygenate may include an aromatic ester. Suitable aromatic esters are not overly limited. The aromatic hydrocarbon used to make the aromatic ester may have 1-5, or 1-4, or 2-4 carboxylic acid functional groups. In some embodiments, the aromatic hydrocarbon may be an aromatic carboxylic acid, an aromatic polycarboxylic anhydride, an aromatic polycarboxylic ester, or a mixture thereof. Without limiting the disclosed technology to one theory of operation, it is believed that when a carboxyl group is directly bonded to an aromatic ester, the freedom of rotation around that bond is limited. This results in a more rigid molecule with a higher neat viscosity compared to the molecular weight of the aromatic ester. In some embodiments, the aromatic ester may be prepared using a polycyclic aromatic acid or anhydride, such as 1,8-naphthalic acid.

[0026] The (mono)alkyl alcohol used to prepare the aromatic ester is at least one C4-C 15 Or C8~C 13 It may comprise a straight chain or branched chain alcohol. In some embodiments, the (mono)alkyl alcohol is 10 Alcohol and C 13 It may contain alcohol. 10 C for alcohol 13 Suitable ratios of the (mono)alkyl alcohol include, but are not limited to, 95:5 to 5:95. In yet another embodiment, the (mono)alkyl alcohol is a branched chain C 10 and branched chain C 13 The (mono)alkyl alcohol may comprise a C 10 Alkyl alcohol and C 13 It is a mixture with alkyl alcohols, both of which are branched chain.

[0027] The glycol ethers used to make the aromatic esters may include alkylene glycols, which have the general structure R1 (-O-R2): x-OR3, where R1 and R3 may be individually hydrogen or C1-C4 hydrocarbyl groups, and R2 may be a monoether or a single, alternating, or randomly distributed polyether subunit. Alternatively, the aromatic ester may be a complex ester in which a non-doubly capped PAG group links two aromatic acids together. In some embodiments, the oxygenate may include at least one aromatic ester that is a benzoate, phthalate, trimellitate, pyromellitate, or mixtures thereof.

[0028] In some examples, the oil of lubricating viscosity is an oxygenate comprising at least one alcohol, ester oil, ether oil, or combinations thereof. In some embodiments, the oxygenate may comprise at least one polyol ester, at least one polyalkylene glycol, or combinations thereof. In yet other embodiments, the oxygenate may comprise at least one polyol ester, such as a polyol ester derived from a reaction mixture of neopentyl glycol, pentaerythritol, and 2-ethylhexanoic acid.

[0029] In other embodiments, the refrigeration lubricant may contain other known lubricants instead of or in addition to the oxygenates listed above. Suitable lubricants include those in Groups I to V of the American Petroleum Institute (API) Base Oil Compatibility Guidelines, namely:

[0030] [Table A]

[0031] The refrigeration lubricant may include mineral oil or synthetic oil, such as polyalphaolefin oil and / or polyester oil, and mixtures thereof. In certain embodiments, the refrigeration lubricant includes a mineral oil base stock, which may be one or more of Group I, Group II, and Group III base oils or mixtures thereof. In yet other embodiments, the refrigeration lubricant may include other common base oils, such as alkylbenzenes, polyalkylene glycols, and polyvinyl ethers.

[0032] Performance Additives In some embodiments, the refrigeration lubricant comprises at least one thiophosphorus additive as described above. The at least one thiophosphorus additive may be a thiophosphorus acid, salt, ester, or combination thereof. The thiophosphorus additive may have a structure as follows:

[0033] [ka] In the formula, R 1 and R 2 are each independently hydrogen or C1-C 20 may be a hydrocarbyl group, X may be O or S, R 3 is hydrogen, C1-C 20 Hydrocarbyl group, or R 4 (O=C)OR 5 wherein R 4 may be a C1-C8 hydrocarbyl group, R 5 is hydrogen or C1-C 20 It may be a hydrocarbyl group.

[0034] R 1 , R 2 , R 3 , and R 5 Each of the above is independently a straight chain, branched chain, or cyclic C1-C 20 In some embodiments, R 1 , R 2 , R 3 , and R 5Any of R may individually be a linear, branched, or cyclic C1-C8, C2-C8, C4-C8, C4-C6, or C4-C5 hydrocarbyl group. 4 may be a C2 to C6 linear, branched, or cyclic hydrocarbyl group. In some embodiments, R 4 may be a C2 hydrocarbyl group or a branched C3 hydrocarbyl group, and / or R 5 may be a C1 to C4 or C5 hydrocarbyl group.

[0035] In some embodiments, the at least one thiophosphorus additive is an alkyl-substituted thiophosphate ester. In such embodiments, X may be S, and R 3 is R 4 (O=C)OR 5 wherein R 4 may be a C1-C8 hydrocarbyl group, R 5 is hydrogen or C1-C 20 or a C1-C4 or C5 hydrocarbyl group; R 1 and R 2 are each independently linear, branched, or cyclic C1-C 20 , or a C2-C8, or a C4-C8 hydrocarbyl group. In some embodiments, the at least one thiophosphorus additive may be a dialkyl dithiophosphate. In some examples, the dialkyl dithiophosphate may have a structure of Formula (I), where X may be S and R 3 is R 4 (O=C)OR 5 may be also possible.

[0036] In some examples, the dialkyldithiophosphate may have a structure of formula (II):

[0037] [ka] In the formula, R 1 and R 2may individually be a linear or branched chain C1-C4 or C5 hydrocarbyl group, R 4 may be a C2 hydrocarbyl group or a branched C3 hydrocarbyl group, R 5 may be a straight or branched chain C1 to C4 or C5 hydrocarbyl group.

[0038] In some embodiments, the at least one thiophosphorus additive may be an alkyl-substituted thiophosphate. In such embodiments, X may be O, and R 3 is hydrogen or C1-C 20 In yet another embodiment, X can be O, and R 1 , R 2 , and R 3 are each independently linear, branched, or cyclic C1-C 20 , or a C2 to C8, or a C4 to C8 hydrocarbyl group. In yet other embodiments, X can be O, and R 1 , R 2 , and R 3 may all be cyclic C5-C6 hydrocarbyl groups, for example, triphenylthiophosphate (O,O,O-triphenylphosphorothioate).

[0039] In some examples, the refrigeration lubricant includes at least two thiophosphorus additives, one additive may be a dialkyl dithiophosphate ester and one additive may be triphenyl thiophosphate (O,O,O-triphenyl phosphorothioate). The at least one thiophosphorus additive may be present in the refrigeration lubricant at 0.1 to 2 wt.%, or 0.2 to 1 wt.%, or 0.3 to 0.6 wt.%, based on the total weight of the refrigeration lubricant. These various ranges typically apply to all of the thiophosphorus additives present in the overall composition. However, in some embodiments, these ranges may also apply to individual thiophosphorus additives.

[0040] In some examples, the refrigeration lubricant comprises at least one thiophosphorus additive as described above and at least one antiwear agent. In some examples, the antiwear agent may be a phosphorus antiwear agent. Thus, in some embodiments, the refrigeration lubricant comprises at least one thiophosphorus additive and at least one phosphorus antiwear agent.

[0041] The phosphorus antiwear agent may be a metal-free organophosphorus antiwear agent. The organic phosphorus antiwear agent may contain sulfur or may be sulfur-free. In some embodiments, the phosphorus antiwear agent may be sulfur-free. The phosphorus antiwear agent may be a phosphite, a phosphonate, an alkyl phosphate ester, an amine or ammonium phosphate, or a mixture thereof.

[0042] Phosphites such as dihydrocarbon and trihydrocarbon phosphites, for example, dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentyl phenyl phosphite; dipentyl phenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphites; amine salts or derivatives of alkyl and dialkyl phosphoric acids, for example, the amine salt of the reaction product of a dialkyl dithiophosphoric acid with propylene oxide, which is subsequently further reacted with P2O5, and mixtures thereof.

[0043] The amine phosphate may be an amine salt of (i) a monohydrocarbyl phosphate, (ii) a dihydrocarbyl phosphate, (iii) a hydroxy-substituted diester of phosphoric acid, or (iv) a phosphorylated hydroxy-substituted di- or triester of phosphoric acid. The amine salt of the phosphorus antiwear agent may be a salt of a primary amine, a secondary amine, a tertiary amine, or mixtures thereof.

[0044] The amine phosphate may be derived from a mono- or dihydrocarbyl phosphate (typically an alkyl phosphate), or a mixture thereof. The alkyl of the mono- or dihydrocarbyl phosphate may include a linear or branched alkyl group of 3 to 36 carbon atoms. The hydrocarbyl group of the linear or branched hydrocarbyl phosphate may contain 4 to 30, or 8 to 20 carbon atoms. Examples of suitable hydrocarbyl groups of the hydrocarbyl phosphate may include isopropyl, n-butyl, sec-butyl, amyl, 4-methyl-2-pentyl (i.e., methylamyl), n-hexyl, n-heptyl, n-octyl, iso-octyl, 2-ethylhexyl, nonyl, 2-propylheptyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, oleyl, or combinations thereof. In one embodiment, the phosphate is a mixture of mono-(2-ethyl)hexyl phosphate and di-(2-ethyl)hexyl phosphate.

[0045] Examples of suitable primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as fatty amines such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleamine. Other useful fatty amines include commercially available fatty amines such as Armeen™ amines (products available from Akzo Chemicals, Chicago, Ill.), such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S, and Armeen SD, where the letter designation refers to the fatty group, such as coco, oleyl, tallow, or stearyl groups.

[0046] Thus, in some examples, the refrigeration lubricant includes at least one phosphorus anti-wear additive that is an alkenyl phosphite, a butylated triphenyl phosphate, a tricresyl phosphate, a dimethyl octadecyl phosphonate, or a combination thereof. The metal-free phosphorus anti-wear agent may be present in the lubricant composition in an amount of 0.1 to 4 wt.%, or 0.1 to 3 wt.%, or 0.2 to 1 wt.%, or 0.3 to 0.6 wt.%.

[0047] In yet other embodiments, the refrigeration lubricant comprises at least one thiophosphorus additive, at least one phosphorus antiwear agent, and at least one metal passivator, which may comprise a corrosion inhibitor and / or a metal deactivator. Metal passivators suitable for use in the refrigeration lubricant are not overly limited and may include both metal deactivators and corrosion inhibitors.

[0048] Suitable metal deactivators include triazoles or substituted triazoles. For example, tolyltriazole or tolutriazole may be utilized in the disclosed lubricant compositions. Suitable examples of metal deactivators include: (i) one or more tolu-triazoles, such as N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, commercially available under the trade name Irgamet 39 by BASF, CAS Registry Number 94270-86-70; (ii) one or more fatty acids derived from animal and / or vegetable sources, and / or hydrogenated forms of such fatty acids, such as Neo-Fat™ available from Akzo Nobel Chemicals, Ltd.

[0049] Suitable corrosion inhibitors include: (i) N-methyl-N-(1-oxo-9-octadecenyl)glycine, CAS Registry Number 110-25-8; (ii) tert-alkyl and (C 12 ~C 14 ) Phosphoric acid, mono- and diisooctyl esters, reacted with primary amines, CAS Registry Number 68187-67-7; (iii) dodecanoic acid; (iv) triphenyl phosphorothioate, CAS Registry Number 597-82-0; and (v) Phosphoric acid, mono- and dihexyl esters, tetramethylnonylamine, and C 11 - 14 and compounds with alkyl amines.

[0050] In one embodiment, the metal passivator is composed of a corrosion additive and a metal deactivator. One useful additive is an N-acyl derivative of sarcosine, such as an N-acyl derivative of sarcosine. One example is N-methyl-N-(1-oxo-9-octadecenyl)glycine. This derivative is available from BASF under the trade name SARKOSYL™ O. Another additive is an imidazoline, such as Amine O™, available from Ciba-Geigy.

[0051] Thus, in some examples, the refrigeration lubricant may have at least one metal passivator comprising a dimercaptothiadiazole, a benzotriazole, or a combination thereof. The metal passivator may be present in the refrigeration lubricant at 0.009-0.5 wt. %, based on the total weight of the lubricant. In some embodiments, the metal passivator may be present at 0.01-0.5 wt. %, or 0.01-0.3 wt. %, or 0.02-0.25 wt. %, or even 0.02-0.07 wt. %, based on the total weight of the refrigeration lubricant. These various ranges typically apply to all of the metal passivators present in the overall composition. However, in some embodiments, these ranges may also apply to individual corrosion inhibitors and / or metal deactivators. The above ranges may apply to the combined amounts of all corrosion inhibitors and metal deactivators present in the overall composition.

[0052] In any of these embodiments, the composition may further comprise one or more additional performance additives in addition to the additives described above. Suitable examples of performance additives include antioxidants, antifoam agents, acid scavengers, or mixtures thereof.

[0053] Suitable antioxidants for use in refrigeration lubricants are not overly limited. Suitable antioxidants include butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), phenyl-a-naphthylamine (PANA), octylated / butylated diphenylamine, high molecular weight phenolic antioxidants, hindered bisphenolic antioxidants, di-alpha-tocopherol, and di-tertiary butyl phenol.

[0054] In some embodiments, the antioxidant includes: (i) hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), CAS registration number 35074-77-2, commercially available from BASF; (ii) N-phenylbenzenamine, reaction products with 2,4,4-trimethylpentene, commercially available from BASF, CAS Registry Number 68411-46-1; (iii) phenyl-a- and / or phenyl-b-naphthylamines, such as N-phenyl-ar-(1,1,3,3-tetramethylbutyl)-1-naphthalenamine, commercially available from BASF; (iv) tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, CAS registration number 6683-19-8; (v) Thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), CAS Registry Number 41484-35-9 (also listed in 21 CFR §178.3570 as thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate); (vi) butylated hydroxytoluene (BHT); (vii) butylated hydroxyanisole (BHA); (viii) bis(4-(1,1,3,3-tetramethylbutyl)phenyl)amine, available from BASF; and (ix) Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, thiodi-2,1-ethanediyl ester, commercially available from BASF.

[0055] In one embodiment, the refrigeration lubricant may include an antioxidant that is an alkylated ester phenol, an alkaryl amine, a di-tertbutyl cresol, or a combination thereof. The antioxidant may be present in the refrigerant lubricant at 0.02% to 1% or 2% by weight, or 0.05% to 1% by weight, or 0.1 to 0.5% by weight, or 0.1 to 0.3% by weight, based on the total weight of the refrigerant lubricant. These various ranges typically apply to all of the antioxidants present in the overall composition. However, in some embodiments, these ranges may also apply to individual antioxidants.

[0056] In yet other embodiments, the refrigeration lubricant may further comprise at least one other additive that is an antifoam agent, an acid scavenger, or a combination thereof.

[0057] Antifoaming agents include polysiloxanes; copolymers of ethyl acrylate and 2-ethylhexyl acrylate; and optionally vinyl acetate; demulsifiers including fluorinated polysiloxanes, trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides, and (ethylene oxide-propylene oxide) polymers. The disclosed technology also provides a method for the preparation of C5-C 17 In combination with alcohol, it may be used with a silicone-containing defoamer. In yet another embodiment, the additional defoamer may include organosilicones such as polydimethylsiloxane, polyethylsiloxane, polydiethylsiloxane, polyacrylates and polymethacrylates, trimethyl-trifluoro-propylmethylsiloxane, etc. In one embodiment, the defoamer may be polydimethylsiloxane.

[0058] The acid scavenger may include alkoxides having an alkyl group of about 1 to about 12 carbon atoms, or 1 to 10 carbon atoms, or 1 to 4 or 6 or 8 carbon atoms. The carbons may be straight or branched, saturated or unsaturated. Examples of alkoxides include methoxide, ethoxide, isopropoxide, and tert-butoxide. In one embodiment, the acid scavenger comprises an epoxide. The metal passivator may be present in the refrigeration lubricant at 0.009 to 0.5 wt. %, based on the total weight of the lubricant composition. In some embodiments, the metal passivator may be present at 0.01 to 0.5 wt. %, or 0.02 to 0.3 wt. %, or 0.05 to 0.25 wt. %, or even 0.02 to 0.07 wt. %, based on the total weight of the refrigeration lubricant.

[0059] The amounts of each chemical component described are exclusive of any solvents or diluent oils that may be customarily present in commercially available materials, i.e., expressed on an active chemical basis, unless otherwise indicated. However, unless otherwise indicated, each chemical or composition referred to herein should be construed as being a commercial grade material that may contain isomers, by-products, derivatives, and other such materials that are normally understood to be present in commercial grades.

[0060] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include: Hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic, aliphatic, and alicyclic substituted aromatic substituents, as well as cyclic substituents in which the ring is completed through another portion of the molecule (e.g., two substituents taken together form a ring); Substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); Hetero substituents, i.e., in the context of the present invention, include those that have a predominantly hydrocarbon character but contain other than carbon in a ring or chain otherwise composed of carbon atoms, and include substituents such as pyridyl, furyl, thienyl, and imidazolyl.Heteroatoms include sulfur, oxygen, and nitrogen.In general, there are no more than two, or no more than one non-hydrocarbon substituent for every 10 carbon atoms in the hydrocarbyl group, and alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0061] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may differ from those initially added. For example, metal ions (e.g., of a detergent) may migrate to other acidic or anionic sites of other molecules. The products formed thereby may not be easily explained, including the products formed when the composition of the present invention is used in its intended application. Nevertheless, all such modifications and reaction products are included within the scope of the present invention. The present invention encompasses the composition prepared by mixing the components described above.

[0062] The refrigeration lubricant is useful in refrigeration systems that use hydrofluorocarbon ("HFC") refrigerants. Examples of HFC refrigerants include, but are not limited to, R-32 (difluoromethane), R-404A (a blend of 44% by weight C2HF5, 52% by weight C2H3F3, and 4% by weight C2H2F4), R-134a (1,1,1,2-tetrafluoroethane), R-410A (a blend of 50% by weight CH2F2 and 50% by weight C2HF5), or combinations thereof.

[0063] Refrigeration systems typically have a compressor and are charged with both a refrigeration lubricant and a refrigerant. In some embodiments, the compressor may be a reciprocating compressor. In some embodiments, the refrigeration system includes copper and / or copper alloy components. The disclosed compositions are suitable for use in refrigeration systems having a condensing temperature in the range of 100-140°F (37.8-60.0°C) and an evaporating temperature in the range of 5-55°F (-15-12.8°C).

[0064] A method for improving metal compatibility and / or reducing metal corrosion of a composition is disclosed. The composition includes a refrigeration lubricant that includes at least one oil of lubricating viscosity that is an oxygenate. The method can include adding at least one thiophosphorus additive as described above to the refrigeration lubricant. In some embodiments, the composition can further include at least one hydrofluorocarbon ("HFC") refrigerant, such as R-32, R-134a, R-404A, or R-410A.

[0065] Also disclosed are methods and uses for improving the compatibility and / or stability of a refrigeration lubricant with a hydrofluorocarbon ("HFC") refrigerant. The methods and uses include adding at least one thiophosphorus additive to a refrigeration lubricant. Also disclosed are methods and uses of the thiophosphorus additive to improve metal compatibility and / or reduce metal corrosion in a composition comprising a refrigeration lubricant that includes at least one oil of lubricating viscosity that is an oxygenate.

[0066] The refrigeration lubricants disclosed herein have improved stability and metal and / or refrigerant compatibility, which may be better understood with reference to the following examples. EXAMPLES

[0067] Several lubricant samples were prepared to evaluate the lubricant's stability and compatibility with various metals.

[0068] Stability and compatibility of lubricants and R-410A at 175℃ Five different lubricants are combined with R-410A refrigerant. R-410A is a non-azeotropic blend of 50% by weight difluoromethane (CH2F2, referred to as R-32) and 50% by weight pentafluoroethane (CHF2CF3, referred to as R-125). The lubricant compositions are provided in Table 1 below.

[0069] [Table 1] 1-Thiophosphorus additives are dithiophosphate esters The 2-thiophosphorus additive is triphenylthiophosphate. 3-Phosphorus antiwear agent is butylated triphenyl phosphate 4-MP represents a metal passivator 5-AO indicates antioxidant activity

[0070] For each lubricant, four sealed tubes are prepared. The first three tubes contain refrigerant and lubricant in a 2:8 ratio (1.6 g lubricant to 0.4 g refrigerant). One metal catalyst (copper, aluminum, or steel) is also placed in each tube. The fourth tube contains more lubricant and refrigerant mixture in the same 2:8 ratio (2.0 g lubricant to 0.5 g refrigerant, metal catalyst). Visual evaluation of both the liquid and metal catalyst is made and recorded. The tubes are then aged at a constant temperature of 175° C. for 14 days. After aging, the first three tubes are visually inspected for changes in lubricant color, opacity, particulate loading, corrosion of the metal catalyst, and copper plating on the surface of the steel catalyst. Visual results are obtained and recorded.

[0071] The color of lubricants is measured according to ASTM D1500. For this color test, a liquid sample is placed in a test container and compared to a colored glass disc using a colorimeter and a standard light source. The glass disc values ​​range from 0.5 to 8.0.

[0072] The visual results are set forth in Table 2 below.

[0073] [Table 2]

[0074] As can be seen from the visual test results above, the lubricants of the present invention were closer in color to the unaged sample, indicating less degradation of the lubricants when exposed to 175°C for 14 days. Color values ​​were 2.75 for Examples 1 and 2 (Inv1 and Inv2) and 2.5 for Examples 3 and 4 (Inv3 and Inv4) compared to 3.0 for the comparative example (Comp Ex). The lubricants of the present invention were also more compatible with metal coupons, especially copper. The metal coupons of Inv3 and Inv4 maintained the luster of all metals, a significant improvement over the comparative lubricants.

[0075] The sample tubes are then opened and the lubricants are degassed from these tubes. The lubricants are then analyzed for Total Acid Number ("TAN") (using ASTM D974) and for decomposition acids (total organic acids) using Ion Chromatography ("IC"). If fluoride is present in the lubricant, it can indicate incompatibility with HFC refrigerants. The IC results are shown in Table 3 below.

[0076] [Table 3] 1-Total organic acids

[0077] As shown above, Inv3 and Inv4 have smaller changes in TAN after aging than Comp Ex.

[0078] Stability and compatibility of lubricants and R-32 at 200℃ Additional samples of the comparative example (Comp Ex) and invention examples 3 and 4 (Inv3 and Inv4) are prepared using R-32 refrigerant. R-32 is difluoromethane (CH2F2). The aging test is also repeated on these samples, except that the samples are kept at 200°C for 14 days. The performance of the lubricants is also tested using visual and IC tests as described above. The visual results are listed in Table 5 below.

[0079] [Table 5]

[0080] As can be seen from the visual test results above, the lubricants of the present invention were closer in color to the unaged sample, indicating less lubricant degradation when exposed to 200°C for 14 days. The Comp Ex also had dark deposits on the tube walls and bottom. The lubricants of the present invention were also more compatible with the metal coupons, especially copper. The IC results are shown in Table 6 below.

[0081] [Table 6] 1-Total organic acids

[0082] As shown above, Inv3 and Inv4 have a smaller change in TAN than Comp Ex after aging at 200° C. Inv3 and Inv4 are also more compatible with HFC refrigerants as indicated by the lower concentration of fluoride in the lubricant.

[0083] Each of the documents mentioned above is incorporated herein by reference, including any prior application to which priority is claimed, whether or not specifically listed above. The reference of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of one of ordinary skill in the art in any jurisdiction. Except in the examples or where otherwise expressly indicated, all quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, should be understood as being modified by the word "about". It should be understood that the upper and lower limits of amounts, ranges, and ratios described herein can be independently combined. Similarly, the ranges and amounts for each element of the present invention can be used together with ranges or amounts for any of the other elements.

[0084] As used herein, the transitional term "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. However, in each occurrence of "comprising" herein, the term is also intended to encompass, as alternative embodiments, the phrases "consisting essentially of" and "consisting of," where "consisting" excludes any unspecified element or step, and "consisting essentially of" permits the inclusion of additional, unrecited elements or steps that do not materially affect the basic and novel characteristics of the composition or method under consideration.

[0085] While certain representative embodiments and details have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention, which in this regard should be limited only by the scope of the claims that follow.

Claims

1. 1. A refrigeration lubricant comprising at least one oil of lubricating viscosity which is an oxygenate, at least one thiophosphorus additive, and at least one phosphorus antiwear additive, a. the at least one thiophosphorus additive is triphenyl thiophosphate; b) A refrigeration lubricant, wherein the at least one phosphorus anti-wear additive comprises an alkenyl phosphite, butylated triphenyl phosphate, tricresyl phosphate, dimethyl octadecyl phosphonate, or a combination thereof.

2. 2. The refrigeration lubricant of claim 1, wherein the at least one thiophosphorus additive comprises O,O,O-triphenyl phosphorothioate.

3. 2. The refrigeration lubricant of claim 1, wherein the at least one thiophosphorus additive is present at 0.1 to 2 wt. % (or 0.2 to 1 wt. %, or 0.3 to 0.6 wt. %), based on the total weight of the refrigeration lubricant.

4. 2. The refrigeration lubricant of claim 1, wherein the at least one phosphorus antiwear additive is present at 0.1 to 4 wt. %, based on the total weight of the refrigeration lubricant.

5. 2. The refrigeration lubricant of claim 1, wherein the lubricant further comprises at least one metal passivator and / or at least one corrosion inhibitor, such as dimercaptothiadiazole and / or benzoletriazole.

6. 6. The refrigeration lubricant of claim 5, wherein the at least one metal passivator and / or the at least one corrosion inhibitor is present at 0.009 to 0.5 wt. %.

7. 6. The refrigeration lubricant of claim 5, wherein the at least one metal passivator and / or the at least one corrosion inhibitor is substantially free of sulfur.

8. 10. The refrigeration lubricant of claim 1, further comprising at least one other additive which is an antifoaming agent (e.g., polydimethylsiloxane), an antioxidant (e.g., alkylated ester phenol, alkaryl amine, or di-tertbutyl cresol), an acid scavenger (e.g., epoxide), or a combination thereof.

9. 9. The refrigeration lubricant of claim 8, wherein the antifoaming agent, if present, is present at 0.01 to 0.5 wt. %, based on the total weight of the refrigeration lubricant.

10. 9. The refrigeration lubricant of claim 8, wherein the antioxidant, if present, is present at 0.05 to 1 wt. %, based on the total weight of the refrigeration lubricant.

11. 10. The refrigeration lubricant of claim 1, wherein the oxygenate comprises at least one alcohol, an ester oil, an ether oil, or a combination thereof.

12. 12. The refrigeration lubricant of claim 11, wherein the oxygenate comprises at least one polyol ester, at least one polyalkylene glycol, or a combination thereof.

13. 13. The refrigeration lubricant of claim 12, wherein the oxygenate comprises at least one polyol ester, such as a polyol ester derived from a reaction mixture of neopentyl glycol, pentaerythritol, and 2-ethylhexanoic acid.

14. A composition comprising the refrigeration lubricant of claim 1 and at least one hydrofluorocarbon ("HFC") refrigerant.

15. The HFC refrigerant is R-32 (difluoromethane), R-404A (44% by weight of C ２ HF ５ , 52 wt% C ２ H ３ F ３ , and 4 wt.% C ２ H ２ F ４ a blend of R-134a (1,1,1,2-tetrafluoroethane), R-410A (50% by weight of CH ２ F ２ and 50 wt.% C ２ HF ５ 15. The composition of claim 14, comprising at least one of:

16. A refrigeration system comprising a compressor, a condenser, and the composition of claim 14.

17. 17. The refrigeration system of claim 16, wherein the compressor is a reciprocating compressor.

18. 17. The refrigeration system of claim 16, wherein the refrigeration system includes copper and / or copper alloy components.

19. 17. The refrigeration system of claim 16, wherein the condensing temperature is in the range of 100 to 140°F (37.8 to 60.0°C) and the evaporating temperature is in the range of 5 to 55°F (-15 to 12.8°C).

20. 1. A method for improving metal compatibility and / or reducing metal corrosion in a composition comprising a refrigeration lubricant comprising at least one oil of lubricating viscosity that is an oxygenate, said method comprising adding at least one thiophosphorus additive to said refrigeration lubricant, said at least one thiophosphorus additive being triphenylthiophosphate.

21. 21. The method of claim 20, wherein the composition further comprises at least one hydrofluorocarbon ("HFC") refrigerant, for example, R-32, R-134a, R-404A, or R-410A.

22. 1. A method for improving the compatibility of a refrigeration lubricant with a hydrofluorocarbon ("HFC") refrigerant and / or its stability, said method comprising adding at least one thiophosphorus additive to said refrigeration lubricant, said at least one thiophosphorus additive being triphenylthiophosphate.

23. 1. Use of a thiophosphorus additive and at least one phosphorus antiwear additive in a composition comprising a refrigeration lubricant comprising at least one oil of lubricating viscosity which is an oxygenate to improve metal compatibility of and / or reduce metal corrosion of said composition, comprising: a. the at least one thiophosphorus additive is triphenyl thiophosphate; b) The use wherein the at least one phosphorus anti-wear additive comprises an alkenyl phosphite, butylated triphenyl phosphate, tricresyl phosphate, dimethyl octadecyl phosphonate, or a combination thereof.

24. 24. The use of the additive of claim 23, wherein the composition further comprises at least one hydrofluorocarbon ("HFC") refrigerant, such as R-32, R-134a, R-404A, or R-410A.

25. 1. Use of a thiophosphorus additive in a refrigeration lubricant to improve the compatibility of the refrigeration lubricant with and / or the stability of a hydrofluorocarbon ("HFC") refrigerant, such as R-32, R-134a, R-404A, or R-410A, wherein the thiophosphorus additive is triphenylthiophosphate.

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