Refrigerating lubricating oil and working fluid containing same

Abstract

The freezing lubricating oil is composed of dipentaerythritol ester, the dipentaerythritol ester is formed by reacting dipentaerythritol with a fatty acid component, the fatty acid component comprises mixed acid and C9 branched fatty acid, and the mixed acid is composed of at least two of C7 straight-chain fatty acid, C8 straight-chain fatty acid, C9 straight-chain fatty acid and C10 straight-chain fatty acid. According to the working fluid containing the refrigerant and the freezing lubricating oil, the working fluid contains the freezing lubricating oil, so that the lubricating property is good, and the service life of a compressor can be prolonged.

Description

TECHNICAL FIELD

[0001] The present invention relates to a lubricating composition and its application, in particular, to a refrigeration lubricating oil and its application. BACKGROUND

[0002] In a refrigeration cycle device, such as a refrigerator, an air conditioner, a heat pump water heater, etc., the main components for the refrigeration cycle are a compressor, a condenser, a thermal expansion valve, and an evaporator. The compressor compresses low-pressure and low-temperature refrigerant in a gaseous state into high-pressure and high-temperature refrigerant in a gaseous state. The condenser condenses high-pressure and high-temperature refrigerant in a gaseous state into high-pressure and room-temperature refrigerant in a liquid state. The thermal expansion valve expands and depressurizes high-pressure and room-temperature refrigerant in a liquid state into low-pressure and low-temperature refrigerant in a liquid-gas mixed state. The evaporator evaporates low-pressure and low-temperature refrigerant in a liquid-gas mixed state to absorb heat and become low-pressure and low-temperature refrigerant in a gaseous state.

[0003] In order to reduce the degree of wear of the compressor in operation, to prolong the service life of the compressor, to reduce the heat generated by the operation of the compressor, to improve the efficiency and reliability of the compressor, and to prevent refrigerant from leaking from the compressor, a lubricating oil capable of performing the above functions is usually used together with the refrigerant as a working fluid in the compressor. However, in the refrigeration cycle, the refrigerant is continuously circulated in the compressor, the condenser, the thermal expansion valve, and the evaporator, so it is inevitable that the lubricating oil will leave the compressor with the refrigerant. Therefore, the mutual solubility between the lubricating oil and the refrigerant directly affects the efficiency and operating life of the refrigeration cycle.

[0004] If the mutual solubility between the lubricating oil and the refrigerant is too poor, the solubility of the refrigerant in the lubricating oil is too low, and in the low-temperature environment of the evaporator, the lubricating oil and the refrigerant will separate due to poor mutual solubility, causing the lubricating oil to accumulate on the surface of the evaporator and not return to the compressor. This not only affects the heat transfer efficiency of the refrigerant in the evaporator, but also causes the amount of lubricating oil in the compressor to be insufficient, resulting in compressor failure. If the mutual solubility between the lubricating oil and the refrigerant is too good, the solubility of the refrigerant in the lubricating oil is too high, and the excessive dissolution of the refrigerant in the lubricating oil will cause the kinematic viscosity of the working fluid to be too low, resulting in poor lubrication of the working fluid, and further causing the compressor to be damaged.

[0005] BCPI-240256 page 2 / 11

[0006] Therefore, how to make the lubricating oil and the refrigerant have appropriate mutual solubility is a major focus of lubricating oil development. SUMMARY

[0007] The first object of the present invention is to provide a refrigeration lubricating oil having appropriate mutual solubility with refrigerant.

[0008] The refrigeration lubricant of the present invention is composed of dipentaerythritol ester, which is formed by the reaction of dipentaerythritol and a fatty acid component. The fatty acid component includes a mixed acid and a C9 branched fatty acid. The mixed acid is composed of at least two of a C7 straight-chain fatty acid, a C8 straight-chain fatty acid, a C9 straight-chain fatty acid, and a C10 straight-chain fatty acid.

[0009] The kinematic viscosity of the refrigeration lubricant of the present invention at 40° C. ranges from 120 cSt to 280 cSt.

[0010] In the refrigeration lubricant of the present invention, based on the total amount of the fatty acid component being 100 wt%, the amount of the mixed acid is in the range of 25 wt% to 35 wt%, and the amount of the C9 branched fatty acid is in the range of 65 wt% to 75 wt%.

[0011] In the refrigeration lubricant of the present invention, the mixed acid is composed of the C7 straight-chain fatty acid, the C8 straight-chain fatty acid and the C10 straight-chain fatty acid.

[0012] In the refrigeration lubricant of the present invention, based on the total amount of the mixed acid as 100wt%, the amount of the C7 straight-chain fatty acid ranges from 20wt% to 43wt%, the amount of the C8 straight-chain fatty acid ranges from 31wt% to 40wt%, and the amount of the C10 straight-chain fatty acid ranges from 26wt% to 40wt%.

[0013] In the refrigeration lubricant of the present invention, the C9 branched-chain fatty acid is selected from the group consisting of 2,2-dimethylheptanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid, and any combination thereof.

[0014] In the refrigeration lubricant of the present invention, the fatty acid component consists of the mixed acid and the C9 branched fatty acid.

[0015] In the refrigeration lubricant oil of the present invention, the molar ratio of the dipentaerythritol to the fatty acid component is 1:1.

[0016] A second object of the present invention is to provide a working fluid with high kinematic viscosity.

[0017] BCPI-240256 Page 3 / 11

[0018] The working fluid of the present invention comprises a refrigerant selected from the group consisting of hydrofluoroolefin compounds, hydrofluorocarbon compounds, hydrochlorofluoroolefin compounds, and any combination thereof, and the refrigeration lubricating oil.

[0019] The working fluid of the present invention, the refrigerant is selected from the group consisting of a mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2-tetrafluoroethane, trans-1,3,3,3-tetrafluoropropene, trans-1-chloro-3,3,3-trifluoropropene, and pentafluoropropane.

[0020] The working fluid of the present invention, the refrigerant is selected from the group consisting of a mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2-tetrafluoroethane, trans-1,3,3,3-tetrafluoropropene, trans-1-chloro-3,3,3-trifluoropropene, and pentafluoropropane. DETAILED DESCRIPTION

[0021] The refrigeration lubricating oil of the present invention consists of dipentaerythritol ester formed by reaction of dipentaerythritol and a fatty acid component, the fatty acid component having a mixed acid and a C9 branched fatty acid.

[0022] The mixed acid consists of at least two of C7 straight chain fatty acid (n-heptanoic acid), C8 straight chain fatty acid (n-octanoic acid), C9 straight chain fatty acid (n-nonanoic acid), and C10 straight chain fatty acid (n-decanoic acid), the ratio of which is not limited. In certain embodiments, the mixed acid consists of the C7 straight chain fatty acid, the C8 straight chain fatty acid, and the C10 straight chain fatty acid, the ratio of which is not limited.

[0023] In certain embodiments, the C9 branched fatty acid is selected from the group consisting of 2,2-dimethylheptanoic acid, 2-methyloctanoic acid, 2- ethylheptanoic acid, 3-methyloctanoic acid, 3,5,5-trimethylhexanoic acid, 2- ethyl-2,3,3

[0024] 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,2- diisopropylpropionic acid, and any combination thereof.

[0025] In certain embodiments, the amount of the mixed acid ranges from 25 wt% to 35 wt%, and the amount of the C9 branched fatty acid ranges from 65 wt% to 75 wt%, based on 100 wt% of the total amount of the fatty acid component. In certain embodiments, the amount of the mixed acid is 25 wt%, and the amount of the C9 branched fatty acid is 75 wt%, based on 100 wt% of the total amount of the fatty acid component. In certain embodiments, the amount of the mixed acid is 35 wt%, and the amount of the C9 branched fatty acid is 65 wt%, based on 100 wt% of the total amount of the fatty acid component.

[0026] In certain embodiments, the amount of the C7 linear fatty acid ranges from 20 wt% to 43 wt%, the amount of the C8 linear fatty acid ranges from 31 wt% to 40 wt%, and the amount of the C10 linear fatty acid ranges from 26 wt% to 40 wt%, based on 100 wt% of the total amount of the mixed acid. In certain embodiments, the amount of the C7 linear fatty acid is 20 wt%, the amount of the C8 linear fatty acid is 40 wt%, and the amount of the C10 linear fatty acid is 40 wt%, based on 100 wt% of the total amount of the mixed acid. In certain embodiments, the amount of the C7 linear fatty acid is 43 wt%, the amount of the C8 linear fatty acid is 31 wt%, and the amount of the C10 linear fatty acid is 26 wt%, based on 100 wt% of the total amount of the mixed acid.

[0027] In certain embodiments, the fatty acid component consists of the mixed acid and the C9 branched fatty acid.

[0028] In certain embodiments, the molar ratio of the dipentaerythritol to the fatty acid component is 1 : 1.

[0029] In certain embodiments, the kinematic viscosity of the refrigeration lubricant at 40 °C ranges from 120 cSt to 280 cSt.

[0030] In some embodiments, the refrigeration lubricant of the present application is prepared by a process comprising: esterifying the dipentaerythritol with the fatty acid component in the presence or absence of a catalyst to obtain a crude product comprising the dipentaerythritol ester, and removing water produced during the esterification reaction. The crude product is purified after the esterification reaction to isolate the dipentaerythritol ester. The catalyst is exemplified by, but not limited to, stannous oxalate, stannous oxide, tetrabutyl titanate, tripropyl titanate, or methyl sulfonic acid, etc. The temperature of the esterification reaction is exemplified by, but not limited to, 150°C to 250°C. The removal is specifically by drying to reduce the water content of the crude product to less than 50 ppm. The purification includes neutralizing the unreacted fatty acid component by adding base or distilling to remove the unreacted fatty acid component to reduce the hydroxyl value of the esterification reaction to less than 10 mgKOH / g, and adding activated carbon and filter aid (perlite) to filter to remove the catalyst and other impurities in the crude product.

[0031] The working fluid of the present application comprises the refrigeration lubricant and a refrigerant selected from the group consisting of hydrofluoroolefins (HFOs), hydrofluoro-carbons (HFCs), hydrochlorofluoroolefins (HCFOs), and any combination thereof.

[0032] BCPI-240256 page 5 / 11

[0033] In some embodiments, the refrigerant is selected from the group consisting of a mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2-tetrafluoroethane (e.g., R-513A), trans-1,3,3,3-tetrafluoropropene [R-1234ze(E)], trans-1-chloro-3,3,3-trifluoropropene [R-1233zd(E)], and pentafluoropropane (R245fa).

[0034] In some embodiments, the refrigeration lubricant is used in an amount ranging from 1 wt% to 99 wt% and the refrigerant is used in an amount ranging from 1 wt% to 99 wt%, based on 100 wt% of the total amount of the working fluid. In some embodiments, the refrigeration lubricant is used in an amount ranging from 20 wt% to 95 wt% and the refrigerant is used in an amount ranging from 5 wt% to 80 wt%, based on 100 wt% of the total amount of the working fluid.

[0035] The working fluid is suitable for circulation in a device that performs a refrigeration cycle. In certain embodiments, the device is, for example, a heat pump water heater, and the refrigerant in the working fluid is R-1233zd(E) and / or R245fa. In certain embodiments, the device is, for example, a refrigerator, a water chiller, or the like, and the refrigerant in the working fluid is R-1234ze(E) and / or R-513A.

[0036] The present application will be further described with reference to the following examples, it being understood that these examples are merely illustrative in nature and are not intended to limit the application.

[0037] [Example 1] Refrigeration lubricating oil

[0038] A dipentaerythritol ester is obtained by esterification of dipentaerythritol and a fatty acid component in a molar ratio of 1:1, which is a refrigeration lubricating oil. The fatty acid component is composed of a mixed acid of C7 linear fatty acid, C8 linear fatty acid, and C10 linear fatty acid, and C9 branched fatty acid, and the amount of the mixed acid is 25 wt%, and the amount of the C9 branched fatty acid is 75 wt% based on the total amount of the fatty acid component being 100 wt%. The amount of the C7 linear fatty acid is 20 wt%, the amount of the C8 linear fatty acid is 40 wt%, and the amount of the C10 linear fatty acid is 40 wt% based on the total amount of the mixed acid being 100 wt%.

[0039] [Example 2] Refrigeration lubricating oil

[0040] Example 2 differs from Example 1 in that the amount of the mixed acid is changed to 35 wt%, and the amount of the C9 branched fatty acid is changed to 65 wt% in Example 2. The amount of the C7 linear fatty acid is 43 wt%, the amount of the C8 linear fatty acid is 31 wt%, and the amount of the C10 linear fatty acid is 26 wt% based on the total amount of the mixed acid being 100 wt%.

[0041] [Comparative Example 1] Refrigeration lubricating oil

[0042] Comparative Example 1 is a commercially available refrigeration lubricating oil (source: Lubrizol, model: Solest 220). BCPI-240256, page 6 / 11

[0043] [Application Example 1] Working fluid

[0044] The refrigeration lubricating oil of Example 1 is mixed with the refrigerant "trans-1-chloro-3,3,3-trifluoropropene [R-1233zd(E)]", and a working fluid is obtained.

[0045] [Application Examples 2 to 8] Working fluid

[0046] Examples 2 to 8 differ from Example 1 in that the kind of refrigerant and the kind of refrigeration lubricant are changed as shown in Tables 2 to 5.

[0047] [Comparative Example 1] Working fluid

[0048] The refrigeration lubricant of Comparative Example 1 is mixed with the refrigerant “trans-1-chloro-3,3,3-trifluoropropene [R-1233zd(E)]”, and a working fluid is obtained.

[0049] [Comparative Examples 2 to 4] Working fluid

[0050] Comparative Examples 2 to 4 differ from Comparative Example 1 in that the kind of refrigerant is changed as shown in Tables 2 to 5.

[0051] [Evaluation of properties]

[0052] Kinematic viscosity of refrigeration lubricant at 40°C: The kinematic viscosity of the refrigeration lubricants of Examples 1 to 2 and Comparative Example 1 at 40°C was measured according to the standard test method of ASTM D445-24, using a viscometer (source: Anton Paar, model SVM-3000), and the results are shown in Table 1.

[0053] Phase separation temperature of refrigeration lubricant with respect to refrigerant: According to ANSI / ASHRAE Standard 218-2019, 2 g of the refrigeration lubricant of Example 1 and 8 g of the refrigerant were sealed in a pressure-resistant glass tube, and the pressure-resistant glass tube was placed in a low-temperature oven, and then the low-temperature oven was gradually cooled, and at the same time, the mixing state of the refrigerant and the refrigeration lubricant of Example 1 in the pressure-resistant glass tube was observed. When the refrigerant and the refrigeration lubricant of Example 1 in the pressure-resistant glass tube were phase-separated into two layers, the temperature of the low-temperature oven at that time was the phase separation temperature of the refrigeration lubricant of Example 1 with respect to the refrigerant, that is, the refrigeration lubricant of Example 1 and the refrigerant were mutually soluble at a temperature greater than the phase separation temperature, and the refrigeration lubricant of Example 1 and the refrigerant were not mutually soluble at a temperature below the phase separation temperature. The refrigeration lubricants of Example 2 and Comparative Example 1 were analyzed according to the same test procedure as described above. The test results are shown in Table 1.

[0054] Solubility of refrigerant in refrigerated lubricating oil and kinematic viscosity of working fluid: The working fluid of application example 1 was placed in a pressure vessel in a low temperature and high vacuum environment. The working fluid was heated to 100°C and then gradually cooled to 0°C. The temperature, pressure and kinematic viscosity of the working fluid were monitored during the cooling process. The working fluid was sampled to analyze the actual composition of refrigerant and refrigerated lubricating oil. The monitored temperature, pressure and kinematic viscosity of the working fluid of application example 1 were calculated to draw the solubility curve and the kinematic viscosity curve of the working fluid of application example 1. The actual kinematic viscosity of the working fluid of application example 1 and the solubility of refrigerant in refrigerated lubricating oil under specific operating conditions (oil sump temperature of compressor and pressure of working fluid in compressor) were calculated using the solubility curve and the kinematic viscosity curve. The working fluids of application examples 2 to 8 and the working fluids of comparative application examples 1 to 4 were analyzed according to the same detection process. The test results are shown in Tables 2 to 5.

[0055] Table 1

[0056]

[0057] Table 2

[0058]

[0059] Table 3

[0060]

[0061] Table 4

[0062]

[0063] Table 5

[0064]

[0065] Generally, under the same operating conditions, the higher the actual kinematic viscosity of the working fluid, the better the lubricity of the working fluid, thereby prolonging the service life of the compressor. Referring to Table 2, under the same type of refrigerant in the working fluid and the same operating conditions, the actual kinematic viscosity of the working fluids of application examples 1 and 2 is higher than that of the working fluid of comparative application example 1. Referring to Tables 3 to 5, the same trend is also shown between application examples 3 and 4 and comparative application example 2, between application examples 5 and 6 and comparative application example 3, and between application examples 7 and 8 and comparative application example 4.

[0066] Therefore, the working fluid containing the refrigeration lubricating oil of the present application has higher actual kinematic viscosity, and has better lubricity, thereby prolonging the service life of the compressor.

[0067] In summary, the refrigeration lubricating oil of the present application is composed of dipentaerythritol ester formed by reacting dipentaerythritol with specific fatty acid components, so that the refrigeration lubricating oil has proper mutual solubility with the refrigerant, and the working fluid containing the refrigeration lubricating oil of the present application has higher kinematic viscosity, representing better lubricity of the working fluid, thereby prolonging the service life of the compressor, and achieving the purpose of the present application.

[0068] The above is only an embodiment of the present application, and cannot limit the scope of the present application. Any simple equivalent changes and modifications made according to the claims and description of the present application are still within the scope of the present application.

Claims

1. A refrigerated lubricating oil characterized by: The refrigeration lubricating oil is composed of a dipentaerythritol ester formed by reacting dipentaerythritol with a fatty acid component having a mixed acid composed of at least two of a C7 linear fatty acid, a C8 linear fatty acid, a C9 linear fatty acid, and a C10 linear fatty acid, and a C9 branched fatty acid.

2. The refrigerated lubricating oil of claim 1, wherein: The refrigeration lubricating oil has a kinematic viscosity at 40°C ranging from 120 cSt to 280 cSt.

3. The refrigerated lubricating oil of claim 1, wherein: The mixed acid is used in an amount ranging from 25 wt% to 35 wt%, and the C9 branched fatty acid is used in an amount ranging from 65 wt% to 75 wt%, based on the total amount of the fatty acid component being 100 wt%.

4. The refrigerated lubricating oil of claim 1, wherein: The mixed acid is composed of the C7 linear fatty acid, the C8 linear fatty acid, and the C10 linear fatty acid.

5. The refrigerated lubricating oil according to claim 1 or 4, characterized in that: The C7 linear fatty acid is used in an amount ranging from 20 wt% to 43 wt%, the C8 linear fatty acid is used in an amount ranging from 31 wt% to 40 wt%, and the C10 linear fatty acid is used in an amount ranging from 26 wt% to 40 wt%, based on the total amount of the mixed acid being 100 wt%.

6. The refrigerated lubricating oil of claim 1, wherein: The C9 branched fatty acid is selected from the group consisting of 2,2-dimethylheptanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,2-diisopropylpropanoic acid, and any combination thereof.

7. The refrigerated lubricating oil of claim 1, wherein: The fatty acid component is composed of the mixed acid and the C9 branched fatty acid.

8. The refrigerated lubricating oil of claim 1, wherein: The molar ratio of the dipentaerythritol to the fatty acid component is 1:

1.

9. A working fluid characterized by: The working fluid comprises a refrigerant selected from the group consisting of hydrofluoroolefin compounds, hydrofluorocarbon compounds, hydrochlorofluoroolefin compounds, and any combination thereof, and the refrigeration lubricating oil according to any one of claims 1 to 8.

10. The working fluid of claim 9, wherein: The refrigerant is selected from the group consisting of a mixture of 2,3,3,3-tetrafluoropropene and 1,1,1,2-tetrafluoroethane, trans-1,3,3,3-tetrafluoropropene, trans-1-chloro-3,3,3-trifluoropropene, and pentafluoropropane.

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