Foam inhibitor for refrigerant oil, method for suppressing foaming in refrigerant oil, use for suppressing foaming in refrigerant oil, refrigerant oil, and working fluid composition

Abstract

This foaming suppressant for a refrigerator oil contains a compound represented by a 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 2 or more].　In the compound represented by formula (1), the hydrogen atom / alkyl group molar ratio is 40 / 60-60 / 40 and the ethylene group / propylene group molar ratio is 10 / 90 or less.

Description

[Technical Field]

[0001] This disclosure relates to foam inhibitors for refrigerant oil, methods for suppressing foaming in refrigerant oil, uses for suppressing foaming in refrigerant oil, refrigerant oil, and working fluid compositions. [Background technology]

[0002] Refrigerant oil used in refrigerators, air conditioners, and other refrigeration equipment is used together with the refrigerant. As the refrigerant is compressed and vaporized, a problem called foaming can occur, where bubbles form in the refrigerant oil. When foaming occurs in refrigerant oil, the operating noise of the refrigerant compressor may increase, and cavitation may occur. In response to this, it has been common practice to suppress foaming of refrigerant oil by adding silicone oil as an antifoaming agent (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-162883 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, adding silicone-based defoamers such as silicone oil to refrigeration oil can cause the defoamer to settle while the compressor is not running, potentially leading to clogging of the piping. Therefore, it is desirable to be able to suppress foaming of refrigeration oil without adding defoamers such as silicone-based defoamers.

[0005] Therefore, one aspect of the present invention aims to suppress foaming of refrigeration oil without adding an antifoaming agent such as a silicone-based antifoaming agent. [Means for solving the problem]

[0006] The present inventors have found that by using a polyalkylene glycol compound as a base oil in which the ratio of terminal hydroxyl groups to terminal alkyl groups and the ratio of ethylene groups to propylene groups are within a specific range, foaming of refrigeration oil can be suppressed without adding an antifoaming agent such as a silicone-based antifoaming agent.

[0007] The present invention includes the following aspects. [1] A foam inhibitor for refrigerant oil containing a compound represented by the following formula (1), [ka] [In the formula, R 1 and R 2 Each is independently a hydrogen atom or an alkyl group, and R 3 [where m is an ethylene group or a propylene group, and m is an integer greater than or equal to 2.] A foaming inhibitor in which the compound represented by formula (1) has a molar ratio of hydrogen atom / alkyl group of 40 / 60 or more and 60 / 40 or less, and a molar ratio of ethylene group / propylene group of 10 / 90 or less. [2] The foaming inhibitor according to [1], wherein the molar ratio of ethylene group / propylene group is 0 / 100.

[0008] [3] A method for suppressing foaming in refrigeration oil containing polyalkylene glycol, comprising the step of selecting a compound represented by the following formula (1) as the polyalkylene glycol, [ka] [In the formula, R 1 and R 2 Each is independently a hydrogen atom or an alkyl group, and R 3 [where m is an ethylene group or a propylene group, and m is an integer greater than or equal to 2.] A method for a compound represented by formula (1), wherein the molar ratio of hydrogen atoms to alkyl groups is 40 / 60 or more and 60 / 40 or less, and the molar ratio of ethylene groups to propylene groups is 10 / 90 or less. [4] The method according to [3], wherein the molar ratio of ethylene group / propylene group is 0 / 100.

[0009] [5] Use for suppressing foaming in a refrigerant oil of a compound represented by the following formula (1), [Chemical formula] [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.] Use of the compound represented by formula (1), wherein the molar ratio of hydrogen atom / alkyl group is 40 / 60 or more and 60 / 40 or less, and the molar ratio of ethylene group / propylene group is 10 / 90 or less. [6] The use according to [5], wherein the molar ratio of ethylene group / propylene group is 0 / 100.

[0010] [7] A refrigerant oil containing a compound represented by the following formula (1) as a base oil, [Chemical formula] [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 refrigerant oil of the compound represented by formula (1), wherein the molar ratio of hydrogen atom / alkyl group is 40 / 60 or more and 60 / 40 or less, and the molar ratio of ethylene group / propylene group is 10 / 90 or less. [8] The refrigerant oil according to [7], wherein the molar ratio of ethylene group / propylene group is 0 / 100. [9] The refrigerant oil according to [7] or [8], used together with a refrigerant containing a hydrocarbon.

[10] An operating fluid composition containing the refrigerant oil according to [7] or [8] and a refrigerant.

[11] The operating fluid composition according to

[10] , wherein the refrigerant contains a hydrocarbon. [Effects of the Invention]

[0011] According to one aspect of the present invention, foaming of refrigerant oil can be suppressed without adding an antifoaming agent such as a silicone-based antifoaming agent. [Modes for carrying out the invention]

[0012] One embodiment of the present invention is a foaming inhibitor for refrigerant oil containing a compound represented by the following formula (1) (hereinafter also referred to as "PAG compound"). [ka] In the formula, R 1 and R 2 Each is independently a hydrogen atom or an alkyl group, and R 3 m is an ethylene group or a propylene group, and m is an integer greater than or equal to 2.

[0013] R 1 and R 2 The alkyl group represented by 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 4. The alkyl group may preferably be an n-butyl group.

[0014] In the PAG compound of this embodiment, R 1 and R 2 The ratio of hydrogen atoms to alkyl groups in (in other words, the ratio of terminal hydroxyl groups to terminal alkyl groups), and R 3 The ratio of ethylene groups to propylene groups (in other words, the ratio of ethylene oxide units (EO units) to propylene oxide units (PO units)) is within a specific range. As a result, when using this PAG compound, foaming of refrigeration oil can be suppressed without the addition of an antifoaming agent.

[0015] Specifically, R 1 and R 2With respect to this, the molar ratio of hydrogen atom / alkyl group (terminal hydroxyl group / terminal alkyl group) is 40 / 60 or more and 60 / 40 or less. The lower limit of this molar ratio may be 41 / 59 or more, 42 / 58 or more, 43 / 57 or more, 44 / 56 or more, 45 / 55 or more, 46 / 54 or more, or 47 / 53 or more. The upper limit of this molar ratio may be 59 / 41 or less, 58 / 42 or less, 57 / 43 or less, 56 / 44 or less, 55 / 45 or less, 54 / 46 or less, 53 / 47 or less, 52 / 48 or less, 51 / 49 or less, 50 / 50 or less, 49 / 51 or less, 48 / 52 or less, 47 / 53 or less, 46 / 54 or less, 45 / 55 or less, 44 / 56 or less, or 43 / 57 or less.

[0016] Also, R 3 Regarding this, the molar ratio of ethylene group / propylene group (molar ratio of EO units / PO units) is 10 / 90 or less. This molar ratio may also be 9 / 91 or less, 8 / 92 or less, 7 / 93 or less, 6 / 94 or less, or 5 / 95 or less, and may also be 0 / 100 or less, 1 / 99 or more, 2 / 98 or more, 3 / 97 or more, 4 / 94 or more, or 5 / 95 or more, and from the viewpoint of further suppressing foaming of refrigeration oil, 0 / 100 (i.e., R 3 (All of them may be propylene groups.)

[0017] The molar ratio of hydrogen atom / alkyl group (terminal hydroxyl group / terminal alkyl group) and the molar ratio of ethylene group / propylene group (EO unit / PO unit) in PAG compounds. 13 This is determined by 13C-NMR measurement. Specifically, the molar ratio of hydrogen atom / alkyl group (terminal hydroxyl group / terminal alkyl group) is: 13 From the spectrum obtained by 13C-NMR measurement, the peaks originating from the carbon atoms constituting the hydrocarbon group having terminal hydroxyl groups and the peaks originating from the carbon atoms constituting the terminal alkyl group can be identified, and the molar ratio of each peak can be appropriately determined using the integral values ​​of each peak. The molar ratio of ethylene group / propylene group (EO units / PO units) is: 13From the spectra obtained by 13C-NMR measurement, peaks originating from the carbon atoms constituting the EO unit and peaks originating from the carbon atoms constituting the PO unit can be identified, and appropriate calculations can be made using information about the EO unit and PO unit, as well as the integral values ​​of each peak.

[0018] PAG compounds are R 1 and R 2 Compounds in which both ends are hydrogen atoms (PAG compounds with hydroxyl groups at both ends), R 1 and R 2 Compounds in which both ends are alkyl groups (PAG compounds with alkyl groups at both ends), and R 1 and R 2 It may be at least one selected from the group consisting of compounds in which one of the atoms is a hydrogen atom and the other is an alkyl group (PAG compounds with a hydroxyl group at one end), and may contain two or more selected from the group consisting of PAG compounds with hydroxyl groups at both ends, PAG compounds with alkyl groups at both ends, and PAG compounds with a hydroxyl group at one end, so as to satisfy the above-mentioned molar ratio of hydrogen atom / alkyl group.

[0019] In one molecule of a PAG compound, R 3 The structural unit (EO unit) is an ethylene group, and R 3 When both structural units (PO units) containing ethylene groups (i.e., when the molar ratio of ethylene groups / propylene groups (EO units / PO units) is greater than 0 / 100 and less than or equal to 10 / 90), the PAG compound may be a random copolymer or a block copolymer.

[0020] In formula (1), m may be 2 or greater, 5 or greater, 10 or greater, or 15 or greater, and may be 40 or less, 35 or less, 30 or less, or 25 or less. The PAG compound may be a mixture of several types of PAG compounds with different values ​​of m. The average value of m may be 2 or greater, 5 or greater, 10 or greater, or 15 or greater, and may be 40 or less, 35 or less, 30 or less, or 25 or less.

[0021] The number-average molecular weight (Mn) of PAG compounds may be 500 or more, 700 or more, 900 or more, 1000 or more, or 1100 or more, and may be 5000 or less, 4500 or less, 4000 or less, 3000 or less, 2000 or less, 1800 or less, 1600 or less, or 1400 or less.

[0022] In this specification, the number-average molecular weight (Mn) refers to the Mn obtained by GPC analysis (converted to polystyrene (standard sample)). Specifically, for example, a solution is prepared using tetrahydrofuran as the solvent, diluted to a sample concentration of 1% by mass, and analyzed using a GPC instrument (e.g., Waters ACQUITY APC UV RI system). The solvent flow rate is set to 0.7 ml / min and the temperature to 40°C, and the analysis is performed using a column with an analyzable molecular weight of 100 to 10000 and a refractive index detector. The relationship between column retention time and molecular weight is determined using a polystyrene standard with a clearly defined molecular weight, and a calibration curve is prepared separately. The molecular weight is then determined from the obtained retention time.

[0023] The kinematic viscosity of PAG compounds at 40°C is 20 mm². 2 / s or more, 30mm 2 / s or more, 40mm 2 / s or more, or 50mm 2 / s or more, and 400mm 2 / s or less, 300mm 2 / s or less, 200mm 2 / s or less, 100mm 2 / s or less, 80mm 2 / s or less, or 60mm 2 It may be less than or equal to / s. The kinematic viscosity of PAG compounds at 100°C is 1 mm 2 / s or more, 3mm 2 / s or more, or 5mm 2 / s or more, 80mm 2 / s or less, 60mm 2 / s or less, 40mm 2 / s or less, 30mm 2 / s or less, 20mm 2 / s or less, or 15mm 2 It can be less than or equal to / s.

[0024] The viscosity index of PAG compounds may be 100 or higher, 120 or higher, 140 or higher, or 160 or higher, and may be 270 or lower, 250 or lower, or 230 or lower. The kinematic viscosity and viscosity index used herein refer to the kinematic viscosity and viscosity index measured in accordance with JIS K2283:2000.

[0025] The foam inhibitor may consist solely of a PAG compound, and may further contain known base oils or additives used in refrigeration oils. The foam inhibitor may be used in any amount in the refrigeration oil. This suppresses foaming of the refrigeration oil. Refrigeration oils may contain polyalkylene glycol as a base oil, but all of the polyalkylene glycol contained in the refrigeration oil may be the foam inhibitor (PAG compound), or 80% or more by mass or 90% or more by mass of the foam inhibitor (PAG compound) may be the foam inhibitor (PAG compound) relative to the total amount of polyalkylene glycol contained in the refrigeration oil.

[0026] Another embodiment of the present invention is a method for suppressing foaming in refrigeration oil containing polyalkylene glycol, comprising the step of selecting the above-mentioned PAG compound as the polyalkylene glycol. More specifically, another embodiment of the present invention can also be described as a method for suppressing foaming (improving foaming properties) in refrigeration oil, comprising the step of selecting the above-mentioned PAG compound based on the relationship between the molar ratio of hydrogen atoms / alkyl groups and the molar ratio of ethylene groups / propylene groups in the above-mentioned PAG compound and the foaming properties of the refrigeration oil. Furthermore, another embodiment of the present invention can also be described as the use of the above-mentioned PAG compound to suppress foaming in refrigeration oil.

[0027] Another embodiment of the present invention is a refrigeration oil containing the above-mentioned PAG compound as a base oil. The content of the PAG compound may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the total amount of the refrigeration oil.

[0028] The refrigeration oil may further contain a base oil. Examples of base oils include mineral oil and synthetic oil. 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 oxygen-containing oils such as polyalkylene glycol compounds other than the PAG compounds mentioned above, esters, and polyvinyl ethers.

[0029] The refrigerant oil may further contain additives. Examples of additives include antioxidants, anti-wear agents, acid scavengers, oxygen scavengers, extreme pressure agents, oiliness agents, defoamers, metal deactivators, viscosity index improvers, pour point depressants, and detergent dispersants. The amount of additives may be 0.1% by mass or more, 1% by mass or more, 10% by mass or less, or 5% by mass or less, based on the total amount of the refrigerant oil.

[0030] The refrigerant oil preferably further contains an antioxidant. Examples of antioxidants include phenolic antioxidants. Examples of phenolic antioxidants 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 antioxidant content may be 0.01% by mass or more, 0.1% by mass or more, 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total amount of the refrigerant oil.

[0031] The refrigeration oil preferably further contains a phosphorus-based anti-wear agent. Examples of phosphorus-based anti-wear agents include phosphate esters, thiophosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorinated phosphate esters, and phosphite esters. Examples of phosphate esters include triaryl phosphates such as tricresyl phosphate (TCP), triphenyl phosphate (TPP), alkylated triphenyl phosphate, and trialkyl phosphates. Examples of thiophosphate esters include triphenylphosphorothionate (TPPT). The content of the phosphorus-based anti-wear agent may be, for example, 0.01% by mass or more, or 0.1% by mass or more, or 5% by mass or less, or 3% by mass or less, based on the total amount of the refrigeration oil.

[0032] The refrigerant oil preferably further contains an acid scavenger. Examples of acid scavengers include epoxy-based acid scavengers. Examples of epoxy-based acid scavengers include glycidyl ether-based acid scavengers having hydrocarbon groups with 6 to 18 carbon atoms, such as 2-ethylhexylglycidyl ether and 4-tert-butylphenylglycidyl ether; glycidyl ester-based acid scavengers having hydrocarbon groups 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 refrigerant oil.

[0033] Because the above-mentioned PAG compounds have excellent defoaming properties, refrigeration oil does not need to contain substantially any defoaming agent, nor does it need to contain substantially any silicone-based defoaming agent. Even if the refrigeration oil contains a silicone-based defoaming agent, the content of the silicone-based defoaming agent in the refrigeration oil may be, on a basis of the total amount of refrigeration oil, preferably 5 ppm by mass or less, 3 ppm by mass or less, 1 ppm by mass or less, or less than 1 ppm by mass in terms of Si atoms.

[0034] The Si content (silicon content) in the refrigeration oil is preferably 5 ppm by mass or less, 3 ppm by mass or less, 1 ppm by mass or less, or less than 1 ppm by mass.

[0035] The kinematic viscosity of refrigerant oil at 40°C is 20 mm². 2 / s or more, 30mm 2 / s or more, 40mm 2 / s or more, or 50mm 2 / s or more, and 400mm 2 / s or less, 300mm 2 / s or less, 200mm 2 / s or less, 100mm 2 / s or less, 80mm 2 / s or less, or 60mm 2 It may be less than or equal to / s. The kinematic viscosity of refrigerant oil at 100°C is 1 mm 2 / s or more, 3mm 2 / s or more, or 5mm 2 / s or more, 80mm 2 / s or less, 60mm 2 / s or less, 40mm 2 / s or less, 30mm 2 / s or less, 20mm 2 / s or less, or 15mm 2 It may be less than or equal to / s. The viscosity index of the refrigeration oil may be 100 or more, 120 or more, 140 or more, or 160 or more, and may be 270 or less, 250 or less, or 230 or less.

[0036] The refrigerant oil described above is used in a refrigerator together with the refrigerant. Another embodiment of the present invention is a working fluid composition containing the above-described refrigerant oil and refrigerant. The content of the refrigerant oil may be 1 part by mass or more, 2 parts by mass or more, 500 parts by mass or less, or 400 parts by mass or less, per 100 parts by mass of refrigerant.

[0037] The refrigerant preferably contains hydrocarbons. The above-mentioned refrigerant oil can suppress foaming and exhibit excellent stability even when used with a hydrocarbon-containing refrigerant.

[0038] 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, n-butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, and n-pentane. The refrigerant may contain only one of these hydrocarbons, or two or more. The refrigerant preferably contains a hydrocarbon that is in gaseous form at 25°C and 1 atm, and more preferably contains at least one selected from the group consisting of propane, n-butane, isobutane, and 2-methylbutane.

[0039] The refrigerant may consist solely of hydrocarbons, or it may contain hydrocarbons and other refrigerants. Examples of other refrigerants include saturated fluorinated hydrocarbons, unsaturated fluorinated hydrocarbons, fluorinated ethers such as perfluoroethers, bis(trifluoromethyl) sulfide, methane trifluoride iodide, ammonia, and carbon dioxide.

[0040] The hydrocarbon content may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of refrigerant.

[0041] Examples of refrigeration equipment include refrigeration systems and air conditioning systems. Examples of refrigeration systems include refrigerators, cold storage warehouses, vending machines, and cooling systems in chemical plants. Examples of air conditioning systems include automotive air conditioners, residential air conditioners, packaged air conditioners, and dehumidifiers.

[0042] As explained above, by using the above-mentioned PAG compound, foaming of refrigeration oil can be suppressed without adding an antifoaming agent such as a silicone-based antifoaming agent. In other words, another embodiment of the present invention is a refrigeration oil with improved foaming properties that contains the above-mentioned PAG compound as a base oil.

[0043] Another embodiment of the present invention can also be described as a method for producing refrigerant oil, comprising the steps of: selecting a PAG compound based on the relationship between the molar ratio of hydrogen atoms / alkyl groups and the molar ratio of ethylene groups / propylene groups in the PAG compound and the foaming properties of the refrigerant oil; and preparing a refrigerant oil containing the selected PAG compound as a base oil. [Examples]

[0044] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0045] Each of the refrigerant oils in the examples and comparative examples was prepared using the following PAG compounds 1 to 8, respectively. Note that none of the refrigerant oils contained defoaming agents such as silicone-based defoamers, and the Si content was less than 1 ppm by mass.

[0046] PAG compound 1: In the above formula (1), R 1 and R 2 In R, the molar ratio of hydrogen atom / alkyl group (n-butyl group) is 50 / 50. 3 The molar ratio of ethylene group / propylene group in is 0 / 100 (R 3 A compound in which all are propylene groups (Mn: 1160, kinematic viscosity at 40°C: 45.58 mm²). 2 / s, 100℃ kinematic viscosity: 9.079mm 2 / s, viscosity index: 186)

[0047] PAG compound 2: In the above formula (1), R 1 and R 2 In R, the molar ratio of hydrogen atom / alkyl group (n-butyl group) is 50 / 50. 3 The molar ratio of ethylene group / propylene group in is 0 / 100 (R 3 A compound in which all are propylene groups (Mn: 1360, kinematic viscosity at 40°C: 57.32 mm²). 2 / s, 100℃ kinematic viscosity: 11.06mm 2 / s, viscosity index: 189)

[0048] PAG-based compound 3: In the above formula (1), R 1 and R 2 The molar ratio of hydrogen atom / alkyl group (n-butyl group) is 43 / 57, and the molar ratio of ethylene group / propylene group in R 3 is 0 / 100 (R 3 are all propylene groups) of the compound (Mn: 771, kinematic viscosity at 40 °C: 29.97 mm 2 / s, kinematic viscosity at 100 °C: 6.275 mm 2 / s, viscosity index: 167)

[0049] PAG-based compound 4: In the above formula (1), R 1 and R 2 The molar ratio of hydrogen atom / alkyl group (n-butyl group) is 42 / 58, and the molar ratio of ethylene group / propylene group in R 3 is 0 / 100 (R 3 are all propylene groups) of the compound (Mn: 1290, kinematic viscosity at 40 °C: 56.25 mm 2 / s, kinematic viscosity at 100 °C: 10.69 mm 2 / s, viscosity index: 184)

[0050] PAG-based compound 5: In the above formula (1), R 1 and R 2 The molar ratio of hydrogen atom / alkyl group (n-butyl group) is 47 / 53, and the molar ratio of ethylene group / propylene group in R 3 is 0 / 100 (R 3 are all propylene groups) of the compound (Mn: 4430, kinematic viscosity at 40 °C: 363.9 mm 2 / s, kinematic viscosity at 100 °C: 57.92 mm 2 / s, viscosity index: 230)

[0051] PAG-based compound 6: In the above formula (1), R 1 and R 2 The molar ratio of hydrogen atom / alkyl group (n-butyl group) is 50 / 50, and the molar ratio of ethylene group / propylene group in R 3 is 5 / 95 of the compound (Mn: 1200, kinematic viscosity at 40 °C: 58.29 mm 2 / s, 100℃ kinematic viscosity: 11.33mm 2 / s, viscosity index: 192)

[0052] PAG compound 7: In the above formula (1), R 1 and R 2 In R, the molar ratio of hydrogen atom / alkyl group (n-butyl group) is 50 / 50. 3 Compounds in which the molar ratio of ethylene group / propylene group is 7 / 93 (Mn: 1390, kinematic viscosity at 40°C: 48.47 mm) 2 / s, 100℃ kinematic viscosity: 9.676mm 2 / s, viscosity index: 190)

[0053] PAG compound 8: In the above formula (1), R 1 and R 2 The molar ratio of hydrogen atoms to alkyl groups (n-butyl groups) in R is 37 / 63. 3 Compounds in which the molar ratio of ethylene group / propylene group is 51 / 49 (Mn: 1340, kinematic viscosity at 40°C: 51.61 mm) 2 / s, 100℃ kinematic viscosity: 11.09mm 2 / s, viscosity index: 214)

[0054] (Evaluation of foaming ability) For each refrigeration oil, the foaming rate / foaming stability (unit: mL) was measured according to Sequence I (tested at 24°C), Sequence II (tested at 93.5°C), and Sequence III (tested at 93.5°C, then cooled to 24°C, and then tested again), as specified in JIS K2518:2003. The results are shown in Table 1.

[0055] [Table 1]

Claims

1. A method for suppressing foaming in refrigeration oil containing polyalkylene glycol, The process includes selecting a compound represented by the following formula (1) as the polyalkylene glycol, 【Chemistry 1】 [In the formula, R １ and R ２ Each is independently a hydrogen atom or an alkyl group, and R ３ [where m is an ethylene group or a propylene group, and m is an integer of 2 or more.] A method in which, in the compound represented by formula (1), the molar ratio of the hydrogen atom to the alkyl group is 40 / 60 or more and 60 / 40 or less, and the molar ratio of the ethylene group to the propylene group is 10 / 90 or less.

2. The method according to claim 1, wherein the molar ratio of the ethylene group to the propylene group is 0 / 100.

3. The use of the compound represented by the following formula (1) to suppress foaming in refrigerant oil, 【Chemistry 2】 [In the formula, R １ and R ２ Each is independently a hydrogen atom or an alkyl group, and R ３ [where m is an ethylene group or a propylene group, and m is an integer of 2 or more.] In the compound represented by formula (1) above, the molar ratio of the hydrogen atom to the alkyl group is 40 / 60 or more and 60 / 40 or less, and the molar ratio of the ethylene group to the propylene group is 10 / 90 or less, for use.

4. The use according to claim 3, wherein the molar ratio of the ethylene group to the propylene group is 0 / 100.

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