Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
  • C10M171/008—Lubricant compositions compatible with refrigerants
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/283—Esters of polyhydroxy compounds
  • C10M2207/2835—Esters of polyhydroxy compounds used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/011—Cloud point
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/017—Specific gravity or density
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/02—Viscosity; Viscosity index
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/09—Characteristics associated with water
  • C10N2020/097—Refrigerants
  • C10N2020/101—Containing Hydrofluorocarbons
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/10—Inhibition of oxidation, e.g. anti-oxidants
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/66—Hydrolytic stability
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/70—Soluble oils
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/30—Refrigerators lubricants or compressors lubricants

Definitions

• the present invention mainly relates to an ester-based lubricating oil, in particular, and to a lubricating oil for use in a rotary screw compressor utilizing a chlorine-free hydrofluorocarbon (HFC) as the refrigerant.
• HFC chlorine-free hydrofluorocarbon
• Heating, rrefrigeration or air-conditioning systems that typically employ rotary screw compressors are commonly found in office buildings, hotels, shopping malls, food storage and processing facilities, chemical processing, a wide variety of manufacturing plants, etc. Keeping the operating cost low is a key job of building owners as well as manufacturing plant managers. In this regard, the ability to keep heating and cooling cost low is critical; ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) estimates that 50% of building energy consumption is due to heating or cooling. In addition, there are important positive environmental and social impacts if energy efficiency can be improved.
• ASHRAE American Society of Heating, Refrigeration and Air-Conditioning Engineers
• the rotary screw compressor is a type of positive displacement compression machine.
• the key parts of the conventional rotary screw compressor are composed of two meshing, parallel and helical-profiled rotors housed in a casing.
• the movement and design of the rotors allow gas to be drawn into, sealed off and compressed as the gas is transported from the suction port to the discharge port thereof.
• a lubricating oil bridges the gap between the rotors therefore providing a hydraulic seal and transferring mechanical energy between the driving and driven rotors.
• rotary screw compressors The basic requirements of rotary screw compressors are robustness and reliability as they are expected to have a life expectancy of years or even decades while operating continuously with little maintenance work.
• the robustness and energy efficiency of rotary screw compressors have been achieved and are continually pursued by mechanical engineers in precise fitting and tight clearances between the helical rotors, and between the rotors and the chamber for better sealing of the compression cavities; and in precise assembly with the help of adoptions of advanced material and ever progressing modern digital controllers with intelligent algorithm.
• lubricant can be a relatively cost effective way to achieve higher efficiency.
• An optimal outcome would be a lubricating oil that improves both the efficiency and reliability of a compressor.
• Evaporator is a critical component in refrigeration or air-conditioning systems; it is in the evaporator that the actual cooling or heat transfer takes place.
• the evaporators are a type of heat exchangers that transfer heat between substances, which in the case of air-conditioners between refrigerant and air, to be cooled by the refrigerant.
• a common necessity of evaporators is that heat transfer surfaces, whether inside or outside the evaporators, need to be kept clean in order not to impede the heat transfer through conduction. For example, defrosting is commonly deployed for this purpose.
• the impact of a lubricating oil on heat transfer arises from the fact that lubricating oil is pumped out of the discharge port along with the discharged gas.
• HFC hydrofluorocarbon
• a primary objective of the present invention is to provide a method of lubricating a rotary screw compressor, in which a chlorine-free hydrofluorocarbon refrigerant is compressed, which comprises mixing a lubricant composition of the present invention with the chlorine-free hydrofluorocarbon refrigerant.
• Another objective of the present invention is to provide a lubricant composition and a refrigerant working fluid for enhancing performance of a rotary screw compressor, wherein the refrigerant working fluid comprises the lubricant composition of the present invention and a chlorine-free hydrofluorocarbon refrigerant.
• Still another objective of the present invention is to provide a rotary screw compressor comprising the refrigerant working fluid of the present invention.
• a further objective of the present invention is to provide a refrigerating apparatus, or a heat pump system or Air-Conditioner comprising the rotary screw compressor of the present invention.
• a lubricant composition provided in accordance with the present invention comprises a mixed polyester having a formula of (I) or (II): (R 1 CH 2 )(R 2 CH 2 )C[CH 2 -O-CH 2 -C(CH 2 R 3 )(CH 2 R 4 )(CH 2 R 5 )] 2 (I) O-[CH 2 -C(CH 2 R 6 )(CH 2 R 7 )(CH 2 R 8 )] 2 (II) wherein each of R 1 to R 8 is a carboxylate of a C5-C10 monocarboxylic acid, and the mixed polyester has two or more different carboxylates of the C5-C10 monocarboxylic acids.
• the present invention discloses an ester-based lubricating oil and a refrigerant working fluid containing the ester-based lubricating oil and a chlorine-free hydrofluorocarbon refrigerant for a rotary screw compressor.
• the working fluid of the present invention is capable of improving the performance/efficiency of the rotary screw compressor, which in turn improves the performance/efficiency of a refrigerating apparatus, a heat pump system or air-conditioner containing the rotary screw compressor.
• the ester-based synthetic lubricating oil comprises esterification products of dipentaerythritol (DiPE), tripentaerythritol (TriPE) or mixtures thereof and a mixed monocarboxylic acid having chain length of five to ten carbons in the presence or absence of a catalyst followed by purification.
• DiPE dipentaerythritol
• TriPE tripentaerythritol
• a typical reaction temperature ranges from 150 to 250°C (preferably 180 to 240°C, and more preferably 200 to 230°C)
• a typical reaction time ranges from 6 hours to 18 hours (preferably 8 hours to 14 hours, and more preferably 8 hours to 12 hours).
• a typical catalyst can be used in the esterification includes (but not limited to) stannous oxalate, stannous oxide, tetra-n-butyltitanate, tetraisopropyl titanate, and methanesulfonic acid.
• the esterification product typically has a hydroxyl value of below 10 mgKOH/g (preferably below 5 mgKOH/g, and more preferably below 3 mgKOH/g).
• the purification process typically involves removing of water by vacuum, removing of acids by neutralization with NaOH and discoloration by carbon black.
• the final purified polyester product has a total acid number (TAN) less than 0.1 mgKOH/g and a water content less than 50 ppm. The low water content is achieved with the help of bubbling dry nitrogen through the purified polyester product.
• the DiPE, and TriPE can be pure or can have certain amounts of polyols that are commonly found in the commercially available DiPE or TriPE.
• the monocarboxylic acid, especially the C5 monocarboxylic acid and C9 monocarboxylic acid can be linear or branched.
• the C5 monocarboxylic acid includes (but not limited to) 2-methylbutanoic acid, 3-methylbutanoic acid, and a mixture thereof; and the C9 monocarboxylic acid preferably is 3,5,5-trimethyl hexanoic acid.
• the ester(s) as described herein will function satisfactorily as complete lubricants. It is generally preferable, however, for a complete lubricant to contain other materials generally denoted in the art as additives, such as oxidation resistance and thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour and/or floc point depressants, detergents, dispersants, antifoaming agents, acid scavengers, anti-wear agents, and extreme pressure resistant additives. Many additives are multi-functional. For example, certain additives may impart both anti-wear and extreme pressure resistance properties, or function both as a metal deactivator and a corrosion inhibitor. Cumulatively, all additives preferably do not exceed 8% by weight, or more preferably do not exceed 5% by weight, of the total compounded lubricant formulation.
• An effective amount of the foregoing additive types is generally in the range from 0.01 to 5% for the antioxidant component, 0.01 to 5% for the corrosion inhibitor component, from 0.001 to 0.5% for the metal deactivator component, from 0.5 to 5% for the lubricity additives, from 0.01 to 2% for each of the acid scavengers, viscosity index improvers, and pour and/or floc point depressants, from 0.1 to 5% for each of the detergents and dispersants, from 0.001 to 0.1% for anti-foam agents, and from 0.1-2% for each of the anti-wear and extreme pressure resistance components. All these percentages are by weight and are based on the total lubricant composition.
• Suitable oxidation resistance and thermal stability improvers are diphenyl-, dinaphthyl-, and phenylnaphthyl-amines, in which the phenyl and naphthyl groups can be substituted, e.g., N,N'-diphenyl phenylenediamine, p-octyldiphenylamine, p,p-dioctyldiphenylamine, N-phenyl-1-naphthyl amine, N-phenyl-2-naphthyl amine, N-(p-dodecyl)phenyl-2-naphthyl amine, di-1-naphthylamine, and di-2-naphthylamine; phenothazines such as N-alkylphenothiazines; imino(bisbenzyl); and hindered phenols such as 6-(t-butyl) phenol, 2,
• cuprous metal deactivators examples include imidazole, benzamidazole, 2-mercaptobenzthiazole, 2,5-dimercaptothiadiazole, salicylidine-propylenediamine, pyrazole, benzotriazole, tolutriazole, 2-methylbenzamidazole, 3,5-dimethyl pyrazole, and methylene bis-benzotriazole. Benzotriazole derivatives are preferred.
• more general metal deactivators and/or corrosion inhibitors include organic acids and their esters, metal salts, and anhydrides, e.g., N-oleyl-sarcosine, sorbitan monooleate, lead naphthenate, dodecenyl-succinic acid and its partial esters and amides, and 4-nonylphenoxy acetic acid; primary, secondary, and tertiary aliphatic and cycloaliphatic amines and amine salts of organic and inorganic acids, e.g., oil-soluble alkylammonium carboxylates: heterocyclic nitrogen containing compounds, e.g., thiadiazoles, substituted imidazolines, and oxazolines; quinolines, quinones, and anthraquinones; propyl gallate; barium dinonyl naphthalene sulfonate; ester and amide derivatives of alkenyl succinic anhydrides or acids,
• Suitable lubricity additives include long chain derivatives of fatty acids and natural oils, such as esters, amines, amides, imidazolines, and borates.
• Example of suitable viscosity index improvers include polymethacrylates, copolymers of vinyl pyrrolidone and methacrylates, polybutenes, and styrene-acrylate copolymers.
• pour point and/or floc point depressants examples include polymethacrylates such as methacrylate-ethylene-vinyl acetate terpolymers; alkylated naphthalene derivatives; and products of Friedel-Crafts catalyzed condensation of urea with naphthalene or phenols.
• detergents and/or dispersants examples include polybutenylsuccinic acid amides; polybutenyl phosphonic acid derivatives; long chain alkyl substituted aromatic sulfonic acids and their salts; and metal salts of alkyl sulfides, of alkyl phenols, and of condensation products of alkyl phenols and aldehydes.
• Suitable anti-foam agents include silicone polymers and some acrylates.
• suitable acid scavengers are glycidyl ethers and esters.
• Suitable anti-wear and extreme pressure resistance agents include sulfurized fatty acids and fatty acid esters, such as sulfurized octyl tallate; sulfurized terpenes; sulfurized olefins; organopolysulfides; organo phosphorus derivatives including amine phosphates, alkyl acid phosphates, dialkyl phosphates, aminedithiophosphates, trialkyl and triaryl phosphorothionates, trialkyl and triaryl phosphines, and dialkylphosphites, e.g., amine salts of phosphoric acid monohexyl ester, amine salts of dinonylnaphthalene sulfonate, triphenyl phosphate, trinaphthyl phosphate, diphenyl cresyl and dicresyl phenyl phosphates, naphthyl diphenyl phosphate, triphenylphosphorothionate; di
• methylbutanoic acid in the claims means 2-methylbutanoic acid, 3-methylbutanoic acid or a mixture of 2-methylbutanoic acid and 3-methylbutanoic acid.
• a mixed polyol ester (POE) was synthesized in this example by reacting TriPE (tripentaerythritol) and a mixture of 3,5,5-trimethyl hexanoic acid (iC9 acid), 2-methylbutanoic acid (MBA) and n-pentanoic acid (nC5 acid) with a ratio of 2 : 7 : 2 by weight.
• TriPE tripentaerythritol
• iC9 acid 3,5,5-trimethyl hexanoic acid
• MSA 2-methylbutanoic acid
• nC5 acid n-pentanoic acid
• TriPE such as the one marketed by Jiangsu Ruiyang Chemical Co., Ltd. in China
• carboxylic acids such as the one marketed by Dow Chemical
• MBA such as the one marketed by Oxea Corporation in US
• iC9 acid such as the one marketed by KH NeoChem Co. in Japan
• the POE prepared in this example achieves the conflicting requirements of high viscosity as well as high miscibility with the HFC refrigerants such as R-134a (1,1,1,2-tetrafluoroethane, which will be demonstrated in the Example 4).
• the POE of Example 1 has the following physical properties. Test method Typical value Viscosity (40°C), cSt ASTM D445 320 Viscosity (100°C), cSt ASTM D445 24.8 VI ASTM D2270 100 Pour Point, °C ASTM D97 -30 Flash Point, °C ASTM D92 304 Density (15°C) ASTM D4052 1.02
• the innovative POE prepared in this example has a viscosity of ISO 220 at 40°C, it is composed of polyesters from TriPE + (MBA and iC9 acid with a ratio of 30 : 70 by weight) and from DiPE + MBA with a weight ratio of 50 : 50.
• This mixed POE oils can be manufactured by either blending of two POEs made separately or by reacting TriPE and DiPE with MBA, and iC9 acid at controlled conditions. In this example the mixed POE oils was manufactured by blending of two POEs made separately similarly in Example 1.
• the mixed POE prepared in this example has the following physical properties: Test method Typical value Viscosity (40°C), cSt ASTM D445 220 Viscosity (100°C), cSt ASTM D445 18.6 VI ASTM D2270 94 Pour Point, °C ASTM D97 -28 Flash Point, °C ASTM D92 282 Density (15°C) ASTM D4052 1.030
• the innovative POE prepared in this example has a viscosity of ISO 400 at 40°C, it is a blend of DiPE + MBA and TriPE + (neodecanoic acid (neo 10) + MBA with a ratio of 3:1 by weight) with a weight ratio of 45 : 55.
• the mixed POE oils was manufactured by blending of two POEs made separately similarly in Example 1. Even with a profoundly high viscosity of 400 cSt at 40°C, it was found that the POE prepared in this example has a surprisingly high miscibility with HFC refrigerants such as the R-134a which will be demonstrated in the Example 4.
• the POE has the following physical properties: Test method Typical value Viscosity (40°C), cSt ASTM D445 400 Viscosity (100°C), cSt ASTM D445 26.8 VI ASTM D2270 91 Pour Point, °C ASTM D97 -23 Flash Point, °C ASTM D92 283 Density (15°C) ASTM D4052 1.034
• Phase separation temperatures measured at a low temperature was used to indicate the compatibility/miscibility. Taking the 20% oil in refrigerant concentration as an example, 0.6 g of a sample oil and 2.4 g of the refrigerant R-134a were enclosed in a thick PYREX (registered trademark) tube (entire length of 300 mm, outer diameter of 10 mm, and inner diameter of 6 mm) cooled in an ethanol bath containing dry ice and warmed. Then the two-phase separation temperatures were measured visually within a temperature range from +60°C to -60°C. The results are shown in Table 1. Table 1.
• Example 5 Measurements of important refrigeration lubricant properties - water specification, total acid number (TAN) and dielectric strength
• the compressor lubricating oils are required to meet industry recognized quality standards.
• the important ones among them are water specification, total acid number (TAN) and dielectric strength.
• the water content in the POE lubricating oil should be minimized as water can react with esters forming acids. In addition, excessive water in oil may be frozen out on metal surfaces hindering the heat transfer.
• Total acid number (TAN) in the POE lubricating oils should also be minimized as acids not only can cause corrosion but also can catalyze the degradation of esters.
• the dielectric constant is important as the POE lubricating oils are frequently in contact with electric components such as motor in the systems.
• lubricating oils in refrigeration, air-conditioning or heating systems are critical as degraded products can cause filter plugging, corrosion or wear problems. Furthermore, problems caused by the degradation of lubricating oils would be compounded in closed-loop, circulating designs.
• One major difference between lubricating oils used in closed-loop refrigeration, air-conditioning and heating systems and those used in engines or gear applications is that the lubricating oils used in closed-loop refrigeration, air-conditioning and heating systems operate in refrigerant environment instead of the normal atmospheric environment. Therefore, to evaluate the stability of POE lubricating oils used with, for example, R-134a, it is only meaningful that the test is conducted in the R-134a environment, thus adopting the sealed tube test.
• Lubricating oil which can't satisfactorily pass the sealed tube stability test may form acids, deposits, insoluble material which may result in corrosion, valve sticking, plugged filter, plugged capillary tube or viscosity change. All of these could result in excessive energy consumption, poor system performance and/or expensive maintenance work.
• Example 7 Comparison of Compatibility/Miscibility between the lubricating oils prepared in Example 2 vs. two conventional POE lubricating oils with the same viscosity grade in R-134a
• Example 4 The same compatibility/miscibility test used in Example 4 was repeated for two conventional ISO 220 POE lubricating oils (RB 220 and RL 220) and the lubricating oil prepared in Example 2 separately.
• the results are shown in Table 4, wherein the RB 220 of the two conventional ISO 220 POE lubricating oil is mostly composed of polyesters from branched acids while the RL 220 has more linearity.
• the lubricating oil prepared in Example 2 also is an ISO 220 grade.
• Table 4 clearly show the distinction on miscibility between the two conventional ISO 220 POE lubricating oils vs. the lubricating oil prepared in Example 2.
• a mixed polyol ester (POE) was synthesized in this example by reacting DiPE (Dipentaerythritol) and a mixture of 3,5,5-trimethyl hexanoic acid (iC9 acid) and 2-methylbutanoic acid (MBA) with a ratio of 1 : 1 by weight.
• DiPE Dipentaerythritol
• iC9 acid 3,5,5-trimethyl hexanoic acid
• MSA 2-methylbutanoic acid
• the POE prepared in this example achieves the conflicting requirements of high viscosity as well as high miscibility with the HFC refrigerants such as R-134a.
• the POE obtained in this example has the following physical properties. Test method Typical value Viscosity (40°C), cSt ASTM D445 220 Viscosity (100°C), cSt ASTM D445 18.3 VI ASTM D2270 91 Pour Point, °C ASTM D97 -29 Flash Point, °C ASTM D92 282 Density (15°C) ASTM D4052 1.0005
• the miscibility of the POE prepared in this example in the HFC refrigerant such as R-134a is shown as follows: Conc. * Example 9 5% oil ⁇ -60°C 10% oil ⁇ -60°C 20% oil ⁇ -60°C * % is based on the total weight of oil and R-134a refrigerant.

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• 2015
  • 2015-02-11 EP EP15154625.6A patent/EP3056557A1/de not_active Withdrawn

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