Refrigerator, working fluid composition, and refrigerator oil

Abstract

A refrigerator comprising a refrigerant circulation system that has a compressor, a condenser, an expansion mechanism, and an evaporator, wherein: the refrigerant circulation system has a member which contains at least one selected from the group consisting of ethylene propylene diene rubbers and hydrogenated nitrile butadiene rubbers; the refrigerant circulation system is filled with a refrigerant containing a hydrocarbon and a refrigerator oil containing a compound represented by formula (1) [in the formula, R1 and R2 are each independently a hydrogen atom or an alkyl group, R3 is an ethylene group or a propylene group, and m is an integer of not less than 2]; and the molar ratio of ethylene group / propylene group in the compound represented by formula (1) is not less than 25 / 75.

Description

Refrigerating machines, working fluid compositions, and refrigeration oils

[0001] The present invention relates to a refrigerator, a working fluid composition, and a refrigerator oil.

[0002] Refrigerators, air conditioners, and other such freezers contain rubber components. For example, hydrogenated nitrile rubber and ethylene propylene diene rubber are known rubbers used in seal members for freezers (see, for example, Patent Document 1). Patent Document 1 describes that hydrogenated nitrile rubber has problems with blister resistance and permeability to refrigerants, while ethylene propylene diene rubber has relatively good blister resistance and permeability but has problems with resistance to refrigerating machine oil.

[0003] JP 2011-79974 A

[0004] According to the investigations of the present inventors, in a refrigerator having components containing hydrogenated nitrile or ethylene propylene diene rubber, when a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a polyalkylene glycol compound are used, the weight of the components may change significantly with use.

[0005] Therefore, one aspect of the present invention aims to suppress weight changes in a refrigerator having components containing hydrogenated nitrile or ethylene propylene diene rubber when using a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a polyalkylene glycol compound.

[0006] The present inventors have found that by appropriately adjusting the ratio of ethylene groups to propylene groups in a polyalkylene glycol-based compound, it is possible to suppress weight changes in components even when a refrigerating machine oil containing the polyalkylene glycol-based compound is used in a refrigerator having components containing hydrogenated nitrile or ethylene propylene diene rubber, together with a refrigerant containing a hydrocarbon.

[0007] [1] A refrigerator equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, wherein the refrigerant circulation system has a member containing at least one selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber, and the refrigerant circulation system is filled with a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or more.] A refrigerator in which the molar ratio of ethylene groups / propylene groups in the compound represented by formula (1) is 25 / 75 or more. [2] The refrigerator according to [1], in which the molar ratio of ethylene groups / propylene groups in the compound represented by formula (1) is 65 / 35 or more. [3] R in formula (1) １ and R ２ is a hydrogen atom. [4] The refrigerator according to [1], wherein the refrigerant circulation system has a member containing ethylene propylene diene rubber, and the molar ratio of ethylene groups to propylene groups in the compound represented by formula (1) is 50 / 50 or more. [5] The refrigerator according to [1], wherein the refrigerant circulation system has a member containing hydrogenated nitrile butadiene rubber, and the molar ratio of ethylene groups to propylene groups in the compound represented by formula (1) is 75 / 25 or less.

[0008] [6] A working fluid composition containing a refrigerant and a refrigerating machine oil, wherein the refrigerant contains a hydrocarbon, and the refrigerating machine oil contains a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３is an ethylene group or a propylene group, and m is an integer of 2 or greater.] A working fluid composition, wherein the molar ratio of ethylene groups / propylene groups in the compound represented by formula (1) is 25 / 75 or greater, and the working fluid composition is used in a refrigerator equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, the refrigerant circulation system having a member containing at least one member selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber.

[0009] [7] A refrigerating machine oil containing a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or greater.] A refrigerating machine oil, wherein the molar ratio of ethylene groups / propylene groups in the compound represented by formula (1) is 25 / 75 or greater, and the refrigerating machine oil is used together with a hydrocarbon-containing refrigerant in a refrigerator equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and the refrigerant circulation system has a member containing at least one selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber.

[0010] According to one aspect of the present invention, in a refrigerator having components containing hydrogenated nitrile or ethylene propylene diene rubber, when a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a polyalkylene glycol compound are used, weight changes of the components can be suppressed.

[0011] According to another aspect of the present invention, when a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a polyalkylene glycol compound are used in a refrigerator having a component containing hydrogenated nitrile or ethylene propylene diene rubber, another object of the present invention is to suppress the generation of impurities that occur during use, and in this case, the generation of the impurities can also be suppressed.

[0012] FIG. 1 is a schematic diagram illustrating an embodiment of a refrigerator.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[0014] Fig. 1 is a schematic diagram showing one embodiment of a refrigerator. As shown in Fig. 1, the refrigerator 10 includes at least a refrigerant circulation system 6 in which a compressor (refrigerant compressor) 1, a condenser (gas cooler) 2, an expansion mechanism 3 (capillary, expansion valve, etc.), and an evaporator (heat exchanger) 4 are sequentially connected by a flow path 5. In one embodiment, the refrigerant circulation system 6 further includes an accumulator 7 between the evaporator 4 and the compressor 1 (on a side of the compressor 1) to suppress or prevent liquid refrigerant from flowing directly into the compressor 1.

[0015] The refrigerant circulation system 6 is filled with a refrigerant and refrigeration oil. In the refrigerant circulation system 6, first, a high-temperature (usually 70 to 120°C) refrigerant discharged from the compressor 1 into the flow path 5 becomes a high-density fluid (such as a supercritical fluid) in the condenser 2. Next, the refrigerant is liquefied by passing through a narrow flow path in the expansion mechanism 3, and then vaporizes in the evaporator 4 to become a low temperature (usually -40 to 0°C). Cooling by the refrigerator 10 utilizes the phenomenon in which the refrigerant absorbs heat from the surroundings when vaporizing in the evaporator 4.

[0016] A small amount of refrigerant and a large amount of refrigerating machine oil coexist under high temperature conditions (usually 70 to 120°C) inside the compressor 1. The refrigerant discharged from the compressor 1 to the flow path 5 is in a gaseous state and contains a small amount (usually 1 to 10% by volume) of refrigerating machine oil as a mist, and a small amount of refrigerant is dissolved in this mist-like refrigerating machine oil (point a in Figure 1).

[0017] In the condenser 2, the gaseous refrigerant is compressed to become a high-density fluid, and a large amount of refrigerant and a small amount of refrigerating machine oil coexist under relatively high temperature conditions (usually 40 to 80°C) (point b in Figure 1). Furthermore, the mixture of a large amount of refrigerant and a small amount of refrigerating machine oil is sent sequentially to the expansion mechanism 3 and the evaporator 4, where it is rapidly cooled (usually -40 to 0°C) (points c and d in Figure 1), and then returned to the compressor 1.

[0018] Examples of such a chiller 10 include refrigeration devices, air conditioners, etc. Examples of refrigeration devices include refrigerators, refrigerated and frozen warehouses, vending machines, cooling devices used in chemical plants, etc. Examples of air conditioners include automotive air conditioners, residential air conditioners, packaged air conditioners, dehumidifiers, etc.

[0019] The refrigerant circulation system 6 includes a member containing at least one selected from the group consisting of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (H-NBR). Such a member may be, for example, an insulating member in the compressor 1, or a sealing member for preventing leakage of the refrigerant and refrigerating machine oil from the compressor 1.

[0020] The refrigerant contains a hydrocarbon. The hydrocarbon is preferably a hydrocarbon having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2 to 4 carbon atoms. Examples of hydrocarbons include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, and normal pentane. The refrigerant may contain only one of these hydrocarbons, or may contain two or more of them. The refrigerant preferably contains a hydrocarbon that is gaseous at 25°C and 1 atmosphere, and more preferably contains at least one selected from the group consisting of propane, normal butane, isobutane, and 2-methylbutane.

[0021] The refrigerant may consist solely of hydrocarbons, or may contain hydrocarbons and other refrigerants, such as saturated fluorohydrocarbons, unsaturated fluorohydrocarbons, fluorinated ethers such as perfluoroethers, bis(trifluoromethyl)sulfide, trifluoroiodomethane, ammonia, and carbon dioxide.

[0022] The hydrocarbon content may be 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % or more, 90 mass % or more, or 95 mass % or more based on the total amount of the refrigerant.

[0023] The refrigerating machine oil contains a compound represented by the following formula (1) (hereinafter also referred to as a "PAG compound"). In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or more.

[0024] R １ and R ２ The alkyl group represented by the formula (I) may be linear or branched. The number of carbon atoms in the alkyl group may be 1 or more, 2 or more, or 3 or more, and may be 16 or less, 12 or less, 8 or less, or 5 or less, or may be 4. The alkyl group may preferably be an n-butyl group.

[0025] The PAG compound is preferably R １ and R ２ and R are both hydrogen atoms (PAG compounds with hydroxyl groups at both ends), or １ and R ２ In one embodiment, from the viewpoint of being able to further suppress the weight change of the component and to suppress the generation of impurities accompanying the use of the refrigerating machine oil (particularly being able to significantly suppress the generation of impurities when the refrigerating machine oil is used together with a component containing EPDM), R １ and R ２ may both be hydrogen atoms.

[0026] The ratio of terminal hydroxyl groups to all terminal groups of a PAG compound (R １ and R ２ R for all of １ and R ２ are hydrogen atoms) may be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 45 mol% or more, 50 mol% or more, 60 mol% or more, or 70 mol% or more, and may be 100 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less.

[0027] The ratio of terminal hydroxyl groups to all terminal groups of the PAG compound is １３ It is determined by C-NMR measurement. Specifically, the ratio is １３ From the spectrum obtained by C-NMR measurement, a peak derived from the carbon constituting the hydrocarbon group having a terminal hydroxyl group and a peak derived from the carbon constituting the terminal hydrocarbon group (such as an alkyl group) can be identified, and the integral value of each peak can be used to appropriately determine the molecular weight.

[0028] In one molecule of a PAG compound, R ３ is an ethylene group, and R ３ is a propylene group. That is, the PAG compound preferably contains both ethylene oxide units (EO units) and propylene oxide units (PO units). In this case, the PAG compound may be a random copolymer or a block copolymer.

[0029] The PAG compound has a molar ratio of ethylene groups to propylene groups (EO units to PO units) (hereinafter also referred to as "EO / PO ratio") of 25 / 75 or more, which makes it possible to suppress weight change in a refrigerator having components containing EPDM or H-NBR when using a refrigerant containing a hydrocarbon and a refrigeration oil containing a polyalkylene glycol compound.

[0030] The EO / PO ratio may be 26 / 74 or more, 27 / 73 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, 45 / 55 or more, 50 / 50 or more, 55 / 45 or more, or 60 / 40 or more, and may be 99 / 1 or less, 95 / 5 or less, 92 / 8 or less, 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, 60 / 40 or less, 55 / 45 or less, 50 / 50 or less, 45 / 55 or less, 40 / 60 or less, or 38 / 62 or less.

[0031] When the refrigerant circulation system 6 has components containing EPDM, the use of a PAG compound having an EO / PO ratio of 25 / 75 or more can significantly suppress the generation of contaminants associated with the use of the refrigerant oil. When the refrigerant circulation system 6 has components containing EPDM, from the viewpoint of further suppressing the generation of contaminants associated with the use of the refrigerant oil, the EO / PO ratio may be preferably 27 / 73 or more, 30 / 70 or more, 35 / 65 or more, 40 / 60 or more, 45 / 55 or more, 50 / 50 or more, or 55 / 45 or more, more preferably 60 / 40 or more, 65 / 35 or more, 70 / 30 or more, 75 / 25 or more, 80 / 20 or more, 85 / 15 or more, or 90 / 10 or more, or may be 99 / 1 or less, 95 / 5 or less, or 92 / 8 or less.

[0032] When the refrigerant circulation system 6 has a component containing H-NBR, from the viewpoint of further suppressing the generation of contaminants associated with the use of the refrigerating machine oil, the EO / PO ratio may be preferably 90 / 10 or less, 85 / 15 or less, 80 / 20 or less, 75 / 25 or less, 70 / 30 or less, 65 / 35 or less, or 60 / 40 or less, and more preferably 55 / 45 or less, 50 / 50 or less, 45 / 55 or less, 40 / 60 or less, 35 / 65 or less, or 30 / 70 or less, or may be 26 / 74 or more or 27 / 73 or more.

[0033] The EO / PO ratio in the PAG-based compound is １３ Specifically, the EO / PO ratio is determined by C-NMR measurement. １３ From the spectrum obtained by C-NMR measurement, peaks derived from carbons constituting EO units and peaks derived from carbons constituting PO units can be identified, and the amount of each peak can be appropriately determined using information on EO units and PO units and the integral values ​​of each peak.

[0034] In formula (1), m may be 2 or more, 5 or more, 10 or more, or 15 or more, and may be 40 or less, 35 or less, 30 or less, or 25 or less. The PAG compound may be a mixture of multiple types of PAG compounds each having a different m value. The average value of m may be 2 or more, 5 or more, 10 or more, or 15 or more, and may be 40 or less, 35 or less, 30 or less, or 25 or less. The number average molecular weight (Mn) of the PAG compound may be 500 or more, 700 or more, or 900 or more, and may be 1800 or less, 1600 or less, or 1400 or less. In other embodiments, the number average molecular weight (Mn) of the PAG compound may be 1250 or less or less than 1250, 1100 or less or less than 1100, 1050 or less or less than 1050, or 1000 or less.

[0035] The number average molecular weight (Mn) in this specification refers to the Mn (value converted to polypropylene glycol (standard sample)) obtained by GPC analysis. Specifically, for example, chloroform is used as a solvent, and a solution with a sample concentration of 2% by mass is prepared by dilution, and analysis is performed using a GPC device (for example, Alliance 2695, manufactured by Waters). The solvent flow rate is set to 1 ml / min, and a column with an analyzable molecular weight of 100 to 10,000 is used, and the analysis is performed using a refractive index detector. Note that the relationship between column retention time and molecular weight is determined using a polypropylene glycol standard with a clear molecular weight, and a calibration curve is separately created, and the molecular weight is determined from the obtained retention time.

[0036] The content of the PAG compound may be 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % or more, or 90 mass % or more based on the total amount of the refrigerating machine oil.

[0037] The refrigeration oil contains a PAG compound as a base oil and may further contain other base oils. Examples of other base oils include mineral oils and synthetic oils. The mineral oil may be paraffinic mineral oil, naphthenic mineral oil, etc. Examples of synthetic oils include synthetic hydrocarbon oils such as poly-α-olefins and alkylbenzenes, and oxygenated oils such as polyalkylene glycol compounds, esters, and polyvinyl ethers other than the PAG compounds.

[0038] The refrigerating machine oil may further contain additives. Examples of the additives include antioxidants, antiwear agents, acid scavengers, oxygen scavengers, extreme pressure agents, oiliness agents, antifoaming agents, metal deactivators, viscosity index improvers, pour point depressants, and detergent dispersants. The content of the additives may be 0.1% by mass or more or 1% by mass or more, and 10% by mass or less or 5% by mass or less, based on the total amount of the refrigerating machine oil.

[0039] The refrigerating machine oil preferably further contains an antioxidant. Examples of the antioxidant include phenol-based antioxidants. Examples of the phenol-based antioxidant include 2,6-di-tert.-butyl-p-cresol (DBPC), 2,6-di-tert.-butyl-phenol, and 4,4'-methylenebis(2,6-di-tert.-butyl-phenol). The content of the antioxidant may be 0.01% by mass or more or 0.1% by mass or more, and may be 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total amount of the refrigerating machine oil.

[0040] The refrigerating machine oil preferably further contains a phosphorus-based antiwear agent. Examples of phosphorus-based antiwear agents include phosphate esters, thiophosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorinated phosphate esters, and phosphites. Examples of phosphate esters include triaryl phosphates such as tricresyl phosphate (TCP), triphenyl phosphate (TPP), and alkylated triphenyl phosphates (e.g., propylated triphenyl phosphate, butylated triphenyl phosphate), and trialkyl phosphates. Examples of thiophosphate esters include triphenylphosphorothionate (TPPT). The content of the phosphorus-based antiwear agent may be, for example, 0.01% by mass or more or 0.1% by mass or more, and 5% by mass or less or 3% by mass or less, based on the total amount of the refrigerating machine oil.

[0041] The refrigerating machine oil preferably further contains an acid scavenger. Examples of the acid scavenger include epoxy-based acid scavengers. Examples of the epoxy-based acid scavengers include glycidyl ether-based acid scavengers having a hydrocarbon group with 6 to 18 carbon atoms, such as 2-ethylhexyl glycidyl ether and 4-tert-butylphenyl glycidyl ether; glycidyl ester-based acid scavengers having a hydrocarbon group with 6 to 18 carbon atoms, such as glycidyl neodecanoate; α-olefin oxide-based acid scavengers having 6 to 18 carbon atoms, such as 1,2-epoxydodecane and 1,2-epoxytetradecane; and alicyclic epoxy-based acid scavengers. The content of the acid scavenger may be 0.01% by mass or more or 0.1% by mass or more, and may be 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total amount of the refrigerating machine oil.

[0042] The kinematic viscosity of the refrigerating oil at 40°C is 20 mm ２ / s or more, 30mm ２ / s or more, or 40 mm ２ / s or more, and 100 mm ２ / s or less, 80mm ２ / s or less, or 60 mm ２ The kinematic viscosity of the refrigerating machine oil at 100°C may be 1 mm / s or less. ２ / s or more, 3mm２ / s or more, or 5 mm ２ / s or more, and ２ / s or less, 20mm ２ / s or less, or 15 mm ２ The viscosity index of the refrigerating machine oil may be 100 or more, 120 or more, or 140 or more, and may be 270 or less, 250 or less, or 230 or less. The kinematic viscosity and viscosity index in this specification refer to the kinematic viscosity and viscosity index measured in accordance with JIS K2283:2000.

[0043] As described above, since a refrigerant and a refrigerating machine oil coexist in the refrigerator 10 (refrigerant circulation system 6), another embodiment of the present invention is a working fluid composition containing the above-mentioned hydrocarbon-containing refrigerant and the above-mentioned PAG-based compound-containing refrigerating machine oil, and is also a working fluid composition used in the above-mentioned refrigerator. In another embodiment, the working fluid composition is also a working fluid composition that can be applied to a refrigerator equipped with a refrigerant circulation system having both a component containing ethylene propylene diene rubber and a component containing hydrogenated nitrile butadiene rubber. In another embodiment, the working fluid composition is also a working fluid composition that can be applied to both a refrigerator equipped with a refrigerant circulation system having a component containing ethylene propylene diene rubber and a refrigerator equipped with a refrigerant circulation system having a component containing hydrogenated nitrile butadiene rubber.

[0044] Another embodiment of the present invention is a refrigerating machine oil containing the above PAG compound, which is used in the above refrigerator together with the above hydrocarbon-containing refrigerant. In another embodiment, the refrigerating machine oil is applicable to a refrigerator equipped with a refrigerant circulation system having both a component containing ethylene propylene diene rubber and a component containing hydrogenated nitrile butadiene rubber. In another embodiment, the refrigerating machine oil is applicable to both a refrigerator equipped with a refrigerant circulation system having a component containing ethylene propylene diene rubber and a refrigerator equipped with a refrigerant circulation system having a component containing hydrogenated nitrile butadiene rubber.

[0045] The content of the refrigerating machine oil may be 1 part by mass or more or 2 parts by mass or more, and may be 500 parts by mass or less or 400 parts by mass or less, per 100 parts by mass of the refrigerant.

[0046] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0047] The following PAG compounds 1 to 6 were used as base oils to prepare refrigerating machine oils for Examples and Comparative Examples. Each refrigerating machine oil contained 0.5 mass% of a phenolic antioxidant (DBPC), 1.0 mass% of a phosphorus-based antiwear agent (TCP), and 0.5 mass% of an epoxy-based acid scavenger (2-ethylhexyl glycidyl ether). The kinematic viscosity of each refrigerating machine oil at 40°C was approximately 44 to 56 mmHg. ２ / s, kinematic viscosity at 100°C is approximately 9 to 11 mm ２ / s, and the viscosity index was about 156 to 213.

[0048] PAG compound 1: In the above formula (1), R １ and R ２ is a hydrogen atom, and R ３ is an ethylene group or a propylene group (EO / PO ratio: 92 / 8), and the average value of m is about 18.4 (Mn: 849).

[0049] PAG compound 2: In the above formula (1), R １ and R ２ is a hydrogen atom or an n-butyl group (ratio of terminal hydroxyl groups to all terminal groups: 65 mol%), R ３ is an ethylene group or a propylene group (EO / PO ratio: 75 / 25), and the average value of m is about 20.8 (Mn: 1050).

[0050] PAG compound 3: In the above formula (1), R １ and R ２ is a hydrogen atom or an n-butyl group (ratio of terminal hydroxyl groups to all terminal groups: 31 mol%), R ３ is an ethylene group or a propylene group (EO / PO ratio: 60 / 40), and the average value of m is about 23.1 (Mn: 1240).

[0051] PAG compound 4: In the above formula (1), R １ and R ２ is a hydrogen atom or an n-butyl group (ratio of terminal hydroxyl groups to all terminal groups: 45 mol%), R ３ is an ethylene group or a propylene group (EO / PO ratio: 35 / 65), and the average value of m is about 18.2 (Mn: 1040).

[0052] PAG compound 5: In the above formula (1), R １ and R ２ is a hydrogen atom or an n-butyl group (ratio of terminal hydroxyl groups to all terminal groups: 50 mol%), R ３ is an ethylene group or a propylene group (EO / PO ratio: 27 / 73), and the average value of m is about 16.7 (Mn: 976).

[0053] PAG compound 6: In the above formula (1), R １ and R ２ is a hydrogen atom or an n-butyl group (ratio of terminal hydroxyl groups to all terminal groups: 50 mol%), R ３ is an ethylene group or a propylene group (EO / PO ratio: 93 / 7), and the average value of m is about 19.8 (Mn: 1200).

[0054] (Evaluation of Weight Change Rate and Amount of Impurities) A ​​mixture of 100 g of each refrigeration oil, the water content of which had been adjusted to 1000 ppm, and 30 g of propane (R290) as a refrigerant, was placed in a 300 mL autoclave. An EPDM member (dumbbell-shaped test piece, length 2.5 cm, width 10.0 cm, thickness 0.2 cm), an H-NBR member (dumbbell-shaped test piece, length 2.5 cm, width 10.0 cm, thickness 0.2 cm), and a PTFE member (dumbbell-shaped test piece, length 2.5 cm, width 10.0 cm, thickness 0.015 cm), whose weights had been measured in advance, was immersed in the mixture and heated at 130 ° C. for 336 hours. After heating, the weights of the EPDM member, H-NBR member, and PTFE member were measured. Using the measured weights of the components before and after heating, the weight change rate (%) was calculated according to the following formula: Weight change rate (%) = (weight of component after heating - weight of component before heating) / weight of component before heating x 100. After heating, each refrigerating machine oil was filtered through a cellulose filter with a pore size of 0.3 μm, with reference to JIS K2276:2003. The filtrate and the filter were thoroughly washed with hexane to remove hexane-soluble components, and the weight of the resulting dried filtrate was measured. The amount of impurities (mg / 100 g) was calculated from the measured weight by converting it into an amount per 100 g of refrigerating machine oil.

[0055] The evaluation results of the weight change rate and the amount of impurities are shown in Table 1.

[0056] As can be seen from Table 1, by using a refrigeration oil containing a PAG compound with an EO / PO ratio of 25 / 75 or more in the presence of a hydrocarbon-containing refrigerant, weight change in both EPDM-containing and H-NBR-containing components can be suppressed (the absolute value of the weight change rate can be reduced). On the other hand, when a PTFE-containing component was used, the weight change rate was the same regardless of the EO / PO ratio of the PAG compound. In other words, the effect of suppressing weight change is a unique effect achieved when using an EPDM-containing component or an H-NBR-containing component.

[0057] Furthermore, refrigerating machine oils containing PAG compounds with an EO / PO ratio of 25 / 75 or more can suppress the generation of contaminants when used with EPDM-containing components and H-NBR-containing components in the presence of a hydrocarbon-containing refrigerant. When refrigerating machine oils are used with H-NBR-containing components and PTFE-containing components, the amount of contaminants is equally low in Examples 1 to 5 and Comparative Example 1. However, when refrigerating machine oils are used with EPDM-containing components, the amount of contaminants is significantly lower in Examples 1 to 5 than in Comparative Example 1. It is surprising that the tendency for the amount of contaminants differs depending on the type of component, and it is particularly surprising that when refrigerating machine oils are used with EPDM-containing components, Examples 1 to 5 can significantly suppress the generation of contaminants compared to Comparative Example 1.

[0058] The above-described effects are also obtained when the content of the phenolic antioxidant (DBPC) is changed to 0.1 to 1 mass%, when the content of the phosphorus-based antiwear agent (TCP) is changed to 0.1 to 3 mass%, and when the content of the epoxy acid scavenger (2-ethylhexyl glycidyl ether) is changed to 0.1 to 3 mass%. Furthermore, similar effects are obtained when TCP is replaced with triphenyl phosphate, propylated triphenyl phosphate, or butylated triphenyl phosphate, and when 2-ethylhexyl glycidyl ether is replaced with 4-t-butylphenyl glycidyl ether, glycidyl neodecanoate, or 1,2-epoxytetradecane. Furthermore, similar effects are obtained when propane (R290) is replaced with isobutane (R600a).

[0059] A refrigerating machine oil containing a PAG compound having an EO / PO ratio of 25 / 75 or more can be suitably used not only with components containing H-NBR but also with components containing EPDM, and is therefore useful as a refrigerating machine oil that can be used for both components containing H-NBR and components containing EPDM.For the same reasons as above, it is also useful as a refrigerating machine oil that can be used for both refrigerators equipped with components containing H-NBR and refrigerators equipped with components containing EPDM.

[0060] REFRIGERATION SYSTEM 7 ACCUMULATOR 10 REFRIGERATOR 2 CONDENSER 3 EXPANSION MECHANISM 4 EVAPORATOR

Claims

1. A refrigerator equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, wherein the refrigerant circulation system has a member containing at least one selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber, and the refrigerant circulation system is filled with a refrigerant containing a hydrocarbon and a refrigerating machine oil containing a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or more.] A refrigerator, wherein the molar ratio of the ethylene group / the propylene group in the compound represented by formula (1) is 25 / 75 or more.

2. The refrigerator according to claim 1, wherein the molar ratio of the ethylene group to the propylene group in the compound represented by formula (1) is 65 / 35 or more.

3. R ​​in the formula (1) １ and R ２ The refrigerator according to claim 2 , wherein is a hydrogen atom.

4. The refrigerator according to claim 1, wherein the refrigerant circulation system has a member containing the ethylene propylene diene rubber, and the molar ratio of the ethylene group / the propylene group in the compound represented by formula (1) is 50 / 50 or more.

5. The refrigerator according to claim 1, wherein the refrigerant circulation system has a member containing the hydrogenated nitrile butadiene rubber, and the molar ratio of the ethylene group to the propylene group in the compound represented by formula (1) is 75 / 25 or less.

6. A working fluid composition containing a refrigerant and a refrigerating machine oil, wherein the refrigerant contains a hydrocarbon, and the refrigerating machine oil contains a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or more.] A working fluid composition, wherein a molar ratio of the ethylene group / the propylene group in the compound represented by formula (1) is 25 / 75 or more, the working fluid composition is used in a refrigerator equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and the refrigerant circulation system has a member containing at least one member selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber.

7. A refrigerating machine oil containing a compound represented by the following formula (1): [In the formula, R １ and R ２ are each independently a hydrogen atom or an alkyl group, and R ３ is an ethylene group or a propylene group, and m is an integer of 2 or more.] A refrigerating machine oil, wherein a molar ratio of the ethylene group / the propylene group in the compound represented by formula (1) is 25 / 75 or more, the refrigerating machine oil is used together with a refrigerant containing a hydrocarbon in a refrigerating machine equipped with a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and the refrigerant circulation system has a member containing at least one selected from the group consisting of ethylene propylene diene rubber and hydrogenated nitrile butadiene rubber.

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