An ionic liquid additive and its refrigeration oil composition

Abstract

This invention discloses an ionic liquid additive and its composition for refrigeration oil, relating to the technical field of refrigeration oil and ionic liquid additives for refrigeration oil. The ionic liquid additive has the structure of a compound as shown in general formula (1) or (2): in which R1, R2, R3, R4, R5, and R6 independently represent alkyl groups having 1 to 14 carbon atoms, and R7 represents hydrogen or an alkyl group having 1 to 14 carbon atoms. The ionic liquid additive of this invention can improve the friction reduction, wear resistance, and load-bearing capacity of the base oil in refrigeration oil.

Description

Technical Field

[0001] This invention relates to the field of refrigeration oil and ionic liquid additives for refrigeration oil, and particularly to an ionic liquid additive and a refrigeration oil composition thereof. Background Technology

[0002] Refrigeration oil is a specialized lubricant for compressor refrigeration units. It directly affects the function and performance of refrigeration equipment and is crucial for the long-term, high-speed, and efficient operation of the compressor. During operation, some refrigeration oil passes through the cylinders along with the refrigerant and enters the condenser and evaporator from the exhaust port. This requires refrigeration oil to not only possess the characteristics of general lubricants but also to adapt to the specific requirements of the refrigeration system and not adversely affect it. Refrigeration oil used in refrigeration systems must meet numerous performance requirements in practical applications, including good miscibility, reliable lubrication performance, excellent thermal stability, oxidation stability, chemical stability, and material compatibility.

[0003] In recent years, the requirements for the coefficient of performance (COP) of refrigeration systems have been gradually increasing. For refrigeration oils, in order to improve the COP, in addition to improving the stability and anti-wear properties of the oil, it is also necessary to reduce the coefficient of friction at the sliding parts of the refrigeration unit. However, current additive systems for refrigeration oils are insufficient to improve anti-wear properties and sufficiently reduce the coefficient of friction while ensuring stability.

[0004] Ionic liquids are room-temperature molten salts composed of cations and anions. They possess characteristics such as low volatility, high thermal stability, a wide range of liquid stability, suitable viscosity, good electrical conductivity, high polarity, and excellent solubility. These properties closely match the desired performance of an ideal lubricant. Compared to traditional extreme pressure anti-wear agents, the designability of ionic liquid structures, the presence of active elements in their molecules, excellent chemical stability, and higher thermal decomposition temperatures have made them widely popular in the field of tribology.

[0005] The chemical and physical properties of ionic liquids change significantly depending on the presence of anions and cations, each possessing unique advantages and characteristics. For example, imidazole ionic liquids, as cations, exhibit excellent electrochemical performance, and some literature indicates they also have good effects as anti-wear agents. However, their high cost and relatively poor thermal stability make them unsuitable as anti-wear agents for refrigeration oils. Pyridine ionic liquids have good stability, but their synthesis is difficult, also making them unsuitable as refrigeration oil additives. As anions, (PF6)-, (BF4)-, and (AlCl4)-, while possessing high reactivity and readily reacting with friction surfaces to form friction films, are prone to hydrolysis in the presence of moisture, producing HF or HCl, which severely affects the stability of compressors and their refrigeration oils.

[0006] In addition, while conventional ionic liquid lubricants possess excellent tribological properties, they also have several significant drawbacks. For example, ordinary ionic liquids exhibit strong surface corrosion to various metals such as copper, steel, and aluminum; they have poor compatibility with base oils, limiting their applicability as additives. Summary of the Invention

[0007] To address the above problems, this invention proposes an ionic liquid additive with a special structure and its refrigeration oil composition.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] An ionic liquid additive is provided, comprising a compound with the structure shown in general formula (1) or (2):

[0010]

[0011] In the general formula, R1, R2, R3, R4, R5, and R6 each independently represent an alkyl group having 1 to 14 carbon atoms, and R7 represents hydrogen (-H) or an alkyl group having 1 to 14 carbon atoms. The alkyl group includes, but is not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decanyl, and the above alkyl groups can be straight-chain or branched.

[0012] The ionic liquid additive can be a single component of the compounds shown in general formulas (1) and (2), or a mixture of the two in any proportion. Specifically, examples can be given as follows:

[0013]

[0014]

[0015] This invention also provides a refrigeration oil composition, which, by weight percentage, contains 0.01% to 0.5% of the aforementioned ionic liquid additive. Preferably, it contains 0.05% to 0.2% of the ionic liquid additive. If the amount of ionic liquid added is less than 0.01%, the lubrication performance of the refrigeration oil will not be significantly improved; when the amount added is greater than 0.5%, not only will the lubrication performance not be commensurate with the amount added, but it may also lead to a decrease in the stability and copper corrosion resistance of the refrigeration oil.

[0016] Furthermore, the refrigeration oil composition also contains 0.1% to 3% anti-wear agent and more than 95% base oil.

[0017] Preferably, the anti-wear agent is selected from at least one of triphenyl phosphate, tricresyl phosphate, diphenyl-p-tert-butylphenyl phosphate, and triphenyl thiophosphate.

[0018] Preferably, the base oil is selected from at least one of esters and ethers. It is preferably an ester oil, and more preferably a polyol ester.

[0019] For esters, polyol esters with excellent stability are preferred. As polyol esters, esters of pentaerythritol or dipentaerythritol with straight-chain or branched fatty acids having 5 to 9 carbon atoms are preferred; the base oil may be a mixture of various esters. The fatty acids are preferably composed of a mixture of straight-chain or branched acids of C5, C8, and C9, such as n-valeric acid, 2-ethylpropionic acid, 2-methylbutyric acid, 3-methylbutyric acid, n-octanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 5-methylheptanoic acid, 5-methylheptanoic acid, 2-ethylhexanoic acid, 3-ethylhexanoic acid, 4-ethylhexanoic acid, 5-ethylhexanoic acid, n-nonanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 4-methyloctanoic acid, 5-methyloctanoic acid, 6-methyloctanoic acid, 7-methyloctanoic acid, 2-ethylheptanoic acid, 3-ethylheptanoic acid, 4-ethylheptanoic acid, 5-ethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2-ethyl-3-methylhexanoic acid, 2-ethyl-4-methylhexanoic acid, 2-ethyl-5-methylhexanoic acid, etc.

[0020] For ethers, it can be polyvinyl ether, etc.

[0021] In addition, one of the above base oils can be used alone, or two or more can be used in combination.

[0022] The kinematic viscosity of the base oil at 40°C is preferably 5 to 150 mm² / s, and the viscosity index is preferably 70 or higher; the pour point is preferably below -10°C, more preferably below -20°C; and the flash point is preferably above 180°C, more preferably above 200°C.

[0023] In some other embodiments, the refrigeration oil composition of the present invention may also have other additives added as needed to further improve its performance, including antioxidants, acid scavengers, metal deactivators, and antifoaming agents.

[0024] The addition of antioxidants to the refrigeration oil composition of the present invention improves its antioxidant properties. In some other embodiments, the antioxidant is selected from at least one of phenolic antioxidants and amine antioxidants. Phenolic antioxidants include, for example, 2,6-di-tert-butyl-p-cresol (DBPC), 2,6-di-tert-butylphenol, and 4,4'-methylenebis(2,6-di-tert-butyl-phenol); amine antioxidants include, for example, phenyl-α-naphthylamines and dialkylated diphenylamines. These antioxidants can be used alone or in combination of two or more.

[0025] The addition of an acid scavenger to the refrigeration oil composition of the present invention improves its stability. In some other embodiments, the acid scavenger is selected from at least one of epoxy compound acid scavengers (epoxide-based acid scavengers). Epoxide compound acid scavengers include, for example, glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, aryl ethylene oxide compounds, alkyl ethylene oxide compounds, alicyclic ethylene oxide compounds, epoxidized fatty acid monoesters, epoxidized vegetable oils, etc. These acid scavengers can be used alone or in combination of two or more.

[0026] The refrigeration oil composition of the present invention, with the addition of a metal deactivator, can protect metals in the refrigeration system from corrosion. In some other embodiments, the metal deactivator is selected from at least one of benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, and heterocyclic compounds. Examples of benzotriazole and benzotriazole derivatives include methylbenzazole (TTZ), N,N'-dialkylaminomethylenebenzazole, and N,N'-di(2-ethylhexyl)-methyl-1H-benzazole-1-methylamine; examples of thiadiazole and thiadiazole derivatives include thiadiazole polysulfides, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptobenzothiazole, and 2-mercaptobenzothiazole sodium.

[0027] The refrigeration oil composition of the present invention can improve its antifoaming performance by adding an antifoaming agent. The antifoaming agent is selected from at least one of silicone-based and non-silicone-based antifoaming agents. The silicone-based antifoaming agent is, for example, dimethyl silicone oil; the non-silicone-based antifoaming agent is, for example, a homopolymer or copolymer of acrylate or methacrylate.

[0028] There are no particular limitations on the amount of other additives added, but it is preferred to have a mass content of less than 5% based on the total amount of refrigeration oil.

[0029] Compared with other ionic additives, the ionic liquid additive of this invention is simple to synthesize, low in cost, and effective with only a small amount. Furthermore, the ionic liquid additive of this invention contains elements such as P and N, which can react with metal surfaces to form a dense and smooth surface film without corroding the metal. It also does not antagonize other additives in refrigeration oils. These advantages make it particularly suitable for refrigeration oils that require long-term stable and reliable operation in compressors. It exhibits extremely low volatility and good thermal stability, making it suitable as a refrigeration oil additive. Specifically, compared with conventional ionic liquids, the ionic liquid additive of this invention has the following advantages:

[0030] 1. The preparation steps are simple and the product cost is low;

[0031] 2. It has good compatibility with synthetic esters and polyether base oils (high solubility is a prerequisite for additives to be added to lubricating oils);

[0032] 3. It has good compatibility with refrigerants;

[0033] 4. It will not interact with the antioxidants, acid scavengers, and other additives necessary for refrigeration oils;

[0034] 5. A small amount is sufficient to achieve good anti-wear effects;

[0035] 6. It has multiple functions; in addition to improving the friction and wear performance of base oil, it can also protect metal surfaces from corrosion.

[0036] 7. It has good hydrolytic stability.

[0037] Furthermore, it has been verified that the ionic liquid additive of the present invention can play the following roles in refrigeration oil: improving the friction reduction, wear resistance, and load-bearing capacity of the base oil. This ionic liquid additive can form a boundary lubrication film mainly composed of phosphates and chemically adsorbed nitrogen compounds, thereby improving friction and wear phenomena; it has a synergistic effect when compounded with specific phosphorus-containing additives to further improve friction and wear performance; and within a specified addition range, it can protect ferrous metal surfaces from corrosion.

[0038] The refrigeration oil composition of the present invention contains an ionic liquid additive with a specific structure. The ionic liquid additive contains phosphate anions, which readily lose alkyl groups and react with the metal surface to form iron phosphate. It can effectively reduce friction on the friction surface through physical / chemical adsorption, and under harsher conditions, it can react with the surface metal to form a protective film to reduce wear, thus exhibiting good tribological properties. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 The results of the Falex ring-block friction test of the refrigeration oil composition in Example 1 of the present invention are shown.

[0041] Figure 2 The results of the metal stability test of the refrigeration oil composition in Example 1 of the present invention are shown.

[0042] Figure 3 To compare the results of the Falex ring-block friction test of the refrigeration oil composition of Example 1.

[0043] Figure 4 To compare the results of the Falex ring-block friction test of the refrigeration oil composition in Example 3.

[0044] Figure 5 To compare the metal stability test results of the refrigeration oil composition in Example 1.

[0045] Figure 6 The results of the metal stability test of the refrigeration oil composition in Comparative Example 2 were used.

[0046] Figure 7 The results of the metal stability test of the refrigeration oil composition in Comparative Example 3 were used.

[0047] Figure 8 To compare the metal stability test results of the refrigeration oil composition in Example 6.

[0048] Figure 9 To compare the metal stability test results of the refrigeration oil composition in Example 8.

[0049] Figure 10 To compare the metal stability test results of the refrigeration oil composition in Example 9.

[0050] Figure 11 The results of the metal stability test of the refrigeration oil composition of Comparative Example 10 are shown. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0053] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0054] Example Component Description

[0055] 1. Base oil

[0056] In the following examples and comparative examples, the base oil used is a polyol ester, specifically an ester synthesized from pentaerythritol and two fatty acids. The specific composition and performance parameters are shown in Table 1.

[0057] Table 1. Composition and performance parameters of base oils

[0058]

[0059] 2. Ionic liquid additives

[0060] The following base oil ionic liquid additives were used in the following examples and comparative examples:

[0061] Ionic liquid additive 1 [General Formula (4)]: [N8881][DEHP]

[0062]

[0063] This additive can be prepared in the following ways:

[0064] A solution of [N8881]OH / ethanol was prepared from 4.04 g of [N8881]Cl using an anion exchange resin (DOWEX MONOSPHERE 550A UPW(OH)). 3.22 g of HDEHP was added to the solution, and the mixture was stirred at room temperature for 6 h until the solution was neutral. The solution was then rotary evaporated at 70 °C under vacuum for 12 h to obtain a colorless, viscous liquid, [N8881][DEHP].

[0065] Ionic liquid additive 2 [General Formula (3)]: [N8888][DEHP]

[0066]

[0067] This additive can be prepared in the following ways:

[0068] 40.58 g of tetraoctylammonium bromide and 23.2 g of diethylhexylphosphoric acid were added to 90 mL of deionized water and 100 mL of n-hexane and stirred until homogeneous to obtain a suspension. At room temperature, 75 mL of NaOH aqueous solution (2.88 g NaOH and 75 mL of deionized water) was added dropwise to the stirred suspension A. After the addition was complete, the suspension became clear, and stirring was continued for more than 8 hours. After stirring, the suspension was allowed to stand and the upper organic phase was separated. The mixture was washed with deionized water (to ensure the removal of NaBr from the organic phase) to obtain intermediate product A. Product A was distilled under reduced pressure for 4 hours at 70 °C under vacuum using a rotary evaporator to obtain a viscous liquid [N8888][DEHP].

[0069] Ionic liquid additive 3 [General formula (7)]:

[0070]

[0071] Ionic liquid additive 4 [General Formula (5)]: [N888H][DEHP]

[0072]

[0073] Ionic liquid additive 5:

[0074]

[0075] Ionic liquid additive 6:

[0076]

[0077] Ionic liquid additive 7 [General Formula (6)]: [N4444][DEHP]

[0078]

[0079] The ionic liquid additives 1-7 mentioned above are all optional ionic liquid additives of this invention.

[0080] Additive 8: 1-Ethyl-3-methylimidazolium hexafluoroborate, is not an optional ionic liquid additive in this invention.

[0081] Additive 9: N,N,N',N'-tetramethyl-N″,N″-dioctylguanidine tetrafluoroborate, is not an optional ionic liquid additive in this invention.

[0082] 3. Anti-wear agent

[0083] Anti-wear agent 1: Triphenyl thiophosphate, an optional anti-wear agent in this invention.

[0084] Anti-wear agent 2: di-n-butyl phosphite, which is not an optional anti-wear agent in this invention.

[0085] Anti-wear agent 3: Acidic phosphate amine salt additive (commercially available), not an optional anti-wear agent of this invention.

[0086] 4. Antioxidants

[0087] 2,6-Di-tert-butyl-p-cresol is an optional antioxidant in this invention.

[0088] 5. Acid scavenging agent

[0089] Neodecanoic acid glycidyl ester, an optional acid scavenger of the present invention.

[0090] 6. Metal deactivators

[0091] N,N'-dialkylaminomethylenetriazole, an optional metal deactivator in this invention.

[0092] The preparation method of the refrigeration oil composition is as follows: add base oil to a container, then add the required additives, anti-wear agents, antioxidants, acid scavengers, and metal deactivators, and heat and stir at 90°C under vacuum for more than 3 hours to obtain the refrigeration oil composition.

[0093] The performance of the refrigeration oil combination was tested in terms of anti-wear and friction reduction properties, anti-corrosion properties, and stability.

[0094] 1) Falex ring block test

[0095] The test was conducted according to the standard ASTM D2714, "Standard Test Methods for Calibration and Operation of the FALEX Ring and Block Friction Tester and Wear Tester".

[0096] Test materials: steel block, cast iron ring.

[0097] Test start temperature: 25℃.

[0098] Test duration: 1 hour.

[0099] Speed: 1000 rpm.

[0100] Load: 100 lbf.

[0101] Wear resistance is evaluated by the wear mark width (μm) of the test specimen after the test; the smaller the wear mark width, the better the wear resistance. Friction reduction performance is evaluated by the average friction coefficient during the test; the smaller the average friction coefficient, the better the friction reduction performance.

[0102] 2) Metal stability test

[0103] 30g of the refrigeration oil composition, iron rod, aluminum rod, and copper sheet were placed into a 200mL autoclave. The air inside the autoclave was completely removed using a vacuum pump. 15g of R32 refrigerant was then sealed inside. After maintaining the autoclave at 175℃ for one week, the appearance of the iron, copper, and aluminum was visually observed (the copper appearance was recorded according to the grading and level description of the copper sheet corrosion standard color plate in GBT 5096-2017).

[0104] 3) Hydrolysis stability test

[0105] 30g of refrigeration oil with a water content of 1000ppm was placed into a 200mL autoclave. The air inside the autoclave was completely removed using a vacuum pump. 17g of R32 refrigerant was then sealed into the autoclave. The acid value (mgKOH / g) was measured after maintaining the autoclave at 150℃ for one week.

[0106] The refrigeration oil compositions of Examples 1-8 were prepared using the above-described method. The components of the refrigeration oil compositions of Examples 1-8 are shown in Table 1.

[0107] Table 1. Components of the Refrigeration Oil Compositions in Examples 1-8

[0108]

[0109] The above-mentioned performance tests were conducted on the refrigeration oil compositions of Examples 1-8, and the test results are shown in Table 2.

[0110] Table 2 Performance test results of the refrigeration oil compositions in Examples 1-8

[0111]

[0112] The results of the Falex ring-block friction test of the refrigeration oil composition in Example 1 are as follows: Figure 1 As shown, the results of the metal stability test are as follows: Figure 2 As shown.

[0113] The refrigeration oil compositions of Examples 9-14 were prepared using the above-described method. The components of the refrigeration oil compositions of Examples 9-14 are shown in Table 3.

[0114] Table 3 Components of the Refrigeration Oil Compositions in Examples 9-14

[0115]

[0116] The above-mentioned performance tests were conducted on the refrigeration oil compositions of Examples 9-14, and the test results are shown in Table 4.

[0117] Table 4 Performance test results of the refrigeration oil compositions in Examples 9-14

[0118]

[0119]

[0120] As can be seen from the test results in Tables 2 and 4, the refrigeration oil compositions of the present invention (Examples 1-14) exhibit excellent performance in terms of anti-wear properties, hydrolytic stability, and metal stability.

[0121] Based on Example 1, the refrigeration oil compositions of Comparative Examples 1-6 were prepared using the above-described method for preparing refrigeration oil compositions. The components of the refrigeration oil compositions of Comparative Examples 1-6 are shown in Table 5.

[0122] Table 5 Components of the Refrigeration Oil Compositions in Comparative Examples 1-6

[0123]

[0124] The above-described performance tests were conducted on the refrigeration oil compositions of Comparative Examples 1-6, and the test results are shown in Figure 6.

[0125] Table 6 Performance test results of the refrigeration oil compositions in Comparative Examples 1-6

[0126]

[0127] The Falex ring-block friction test results of the refrigeration oil composition in Comparative Example 1 are as follows: Figure 3 As shown; the Falex ring-block friction test results of the refrigeration oil composition of Comparative Example 3 are as follows. Figure 4 As shown.

[0128] The metal stability test results of the refrigeration oil composition in Comparative Example 1 are as follows: Figure 5 As shown; the metal stability test results of the refrigeration oil composition of Comparative Example 2 are as follows. Figure 6 As shown; the metal stability test results of the refrigeration oil composition in Comparative Example 3 are as follows. Figure 7 As shown; the metal stability test results of the refrigeration oil composition of Comparative Example 6 are as follows. Figure 8 As shown.

[0129] A comparison of the experimental results of the above embodiments with those of Comparative Example 1 shows that the wear track width and the average coefficient of friction are significantly reduced, indicating that the anti-wear and friction-reducing properties of the refrigeration oil composition of the present invention are excellent.

[0130] Although the refrigeration oil composition of Comparative Example 2 has slightly better anti-wear and friction-reducing properties than the refrigeration oil composition of the present invention, its hydrolytic stability and metal stability are poor, indicating that the excessive amount of ionic liquid additive 1 will lead to a decrease in stability and has limited improvement in anti-wear and friction-reducing properties.

[0131] The performance of the refrigeration oil composition in Comparative Example 3 was inferior to that in the Example, indicating that the addition of too low an amount of ionic liquid additive 1 had no significant effect on improving the performance of the refrigeration oil composition.

[0132] Although the anti-wear and friction-reducing performance of Comparative Example 4 was improved compared to Comparative Example 1, it was significantly lower than that of the embodiments of the present invention, indicating that the ionic liquid additive and the anti-wear agent have a significant synergistic effect and can significantly improve the anti-wear and friction-reducing performance.

[0133] Comparative Example 5 showed comparable performance to Comparative Example 4, but the low amount of anti-wear additive had little effect on improving the performance of the refrigeration oil composition.

[0134] Comparative Example 6 has similar performance to Example 1, but its stability is lower than that of Example 1. This indicates that excessive amounts of anti-wear agent have limited effect on improving anti-wear performance and may even reduce stability.

[0135] Based on the above embodiments, the refrigeration oil compositions of Comparative Examples 7-10 were prepared using the above-described method for preparing refrigeration oil compositions. The components of the refrigeration oil compositions of Comparative Examples 7-10 are shown in Table 7.

[0136] Table 7 Components of the Refrigeration Oil Compositions in Comparative Examples 7-10

[0137] Components (mass%) Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 base oil 97.88 98.28 97.88 97.88 Ionic liquid additive 1 / 0.1 / / Anti-wear agent 1 0.5 / 0.5 0.5 antioxidants 0.5 0.5 0.5 0.5 Acid scavenger 1 1 1 1 Metal deactivating agents 0.02 0.02 0.02 0.02 Anti-wear agent 2 / 0.1 / / Anti-wear agent 3 0.1 / / / Additive 8 / / 0.1 / Additive 9 / / / 0.1

[0138] The above-mentioned performance tests were conducted on the refrigeration oil compositions of Comparative Examples 7-10, and the test results are shown in Table 8.

[0139] Table 8 Performance test results of the refrigeration oil compositions in Comparative Examples 7-10

[0140]

[0141]

[0142] The metal stability test results of the refrigeration oil composition in Comparative Example 8 are as follows: Figure 9 As shown; the metal stability test results of the refrigeration oil composition of Comparative Example 9 are as follows. Figure 10 As shown; the metal stability test results of the refrigeration oil composition of Comparative Example 10 are as follows. Figure 11 As shown.

[0143] As shown in Table 8, the refrigeration oil composition of the present invention has comparable or better friction and wear performance than Comparative Examples 7-10, but its stability is significantly better than that of Comparative Examples 7-10. It can be seen that the refrigeration oil composition of the present invention significantly improves anti-wear and friction reduction performance while ensuring stability, and its performance is better than that of commercially available anti-wear agents or other ionic liquid additives.

[0144] Therefore, a comparison of the test results in Tables 2, 4, 6, and 8 shows that the refrigeration oil composition of the present invention (Examples 1-14) has significantly better performance in terms of anti-wear properties, hydrolytic stability, and metal stability than Comparative Examples 1-10.

[0145] Furthermore, based on Example 4, the refrigeration oil compositions of Examples 15-20 were prepared using the above-described method for preparing refrigeration oil compositions, as detailed below.

[0146] Example 15: The difference from Example 4 is that the base oil is an ester synthesized from dipentaerythritol and 3-methylbutyric acid, while the other components are the same as in Example 4.

[0147] Example 16: The difference from Example 4 is that the base oil is an ester synthesized from pentaerythritol, isobutyric acid, and 3,5,5-trimethylhexanoic acid, while the other components are the same as in Example 4.

[0148] Example 17: The difference from Example 4 is that the base oil is polyvinyl ether, which is a copolymer of ethyl vinyl ether and isobutyl vinyl ether. Other components are the same as in Example 4.

[0149] Example 18: The difference from Example 4 is that anti-wear agent 1 is replaced with tricresyl phosphate, while the other components are the same as in Example 4.

[0150] Example 19: The difference from Example 4 is that anti-wear agent 1 is replaced with diphenyl tert-butyl phosphate, and the other components are the same as in Example 4.

[0151] Example 20: The difference from Example 4 is that anti-wear agent 1 is replaced with triphenyl phosphate, while the other components are the same as in Example 4.

[0152] The above-mentioned performance tests were conducted on the refrigeration oil compositions of Examples 15-20, and the test results are shown in Table 9.

[0153] Table 9 Performance test results of the refrigeration oil compositions in Examples 15-20

[0154]

[0155] The above description is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment. Therefore, any equivalent or modified implementations made without departing from the spirit of the present invention fall within the protection scope of the present invention.

Claims

1. A refrigeration oil composition characterized in that, The lubricating oil composition comprises 0.01-0.5% of the ionic liquid additive, 0.1-3% of the anti-wear agent and more than 95% of the base oil by weight percentage; The ionic liquid additive is a compound represented by general formula (1) or (2): In the general formula, R1, R2, R3, R4, R5 and R6 independently represent alkyl groups with 1-14 carbon atoms, and R7 represents hydrogen or an alkyl group with 1-14 carbon atoms; The anti-wear agent is at least one selected from triphenyl phosphate, tricresyl phosphate, diphenyl-p-tert-butylphenyl phosphate and triphenyl phosphorothioate; The base oil is at least one selected from ester and ether.

2. The refrigerant oil composition according to claim 1, characterized by, The ester is polyol ester, and the ether is polyvinyl ether.

3. The refrigerant oil composition according to claim 2, characterized by, The polyol ester is at least one selected from esters synthesized from pentaerythritol or dipentaerythritol and straight-chain or branched-chain fatty acids with 5-9 carbon atoms.

4. The refrigeration compressor oil composition according to any one of claims 1 to 3, wherein Other additives are also included, which include antioxidants, acid scavengers, metal deactivators and antifoaming agents.

5. The refrigerant oil composition according to claim 4, characterized by, The antioxidant is at least one selected from phenolic antioxidants and amine antioxidants; the acid scavenger is at least one selected from epoxy compound acid scavengers; the metal deactivator is at least one selected from benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, and heterocyclic compounds; and the antifoaming agent is at least one selected from silicon-based antifoaming agents and non-silicon-based antifoaming agents.

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