JP6641346B2 - Refrigeration oil and working fluid composition for refrigerator - Google Patents

Description

  The present invention relates to a refrigerator oil and a working fluid composition for a refrigerator.

  Due to the problem of depletion of the ozone layer in recent years, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) conventionally used as refrigerants for refrigeration equipment are subject to regulation, and HFC (hydrofluorocarbon) is used as a refrigerant instead. Is being done. However, among HFC refrigerants, HFC-134a, which is standardly used as a refrigerant for car air conditioners, has a zero ozone depletion potential (ODP) but a high global warming potential (GWP). It is targeted.

  Under such a background, there is an urgent need to develop a refrigerant having a small influence on the ozone layer and a low GWP. For example, Patent Literature 1 discloses a trifluoroethylene (HFO-1123) refrigerant as a refrigerant having little effect on the ozone layer and having a low GWP.

  When conventional CFCs or HCFCs are used as refrigerants, mineral oils and hydrocarbon oils such as alkylbenzene have been suitably used as refrigeration oils. However, refrigeration oils have compatibility with refrigerants and lubricity depending on the types of refrigerants that coexist. In addition, it is necessary to develop a refrigerating machine oil for each refrigerant because it exhibits unpredictable behavior such as a melt viscosity with a refrigerant and thermal / chemical stability.

International Publication 2012/157776

  An object of the present invention is to provide a refrigerator oil excellent in compatibility with a trifluoroethylene (HFO-1123) refrigerant, and a working fluid composition for a refrigerator containing the refrigerator oil.

  The present invention provides a refrigerating machine oil containing at least one oxygen-containing oil having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less as a base oil and used together with a trifluoroethylene refrigerant.

  The present invention also provides a refrigerating machine comprising: a refrigerating machine oil containing, as a base oil, at least one oxygen-containing oil having a carbon / oxygen molar ratio of 2.5 to 5.8, and a trifluoroethylene refrigerant. A mechanical working fluid composition is provided.

  The refrigerating machine oil preferably contains, as the oxygen-containing oil, an ester of a fatty acid having a branched fatty acid having 4 to 9 carbon atoms in a proportion of 20 to 100 mol% and a polyhydric alcohol.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerating machine oil excellent in compatibility with a trifluoroethylene (HFO-1123) refrigerant | coolant, and the working fluid composition for refrigerators containing this refrigerating machine oil can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The refrigerating machine oil according to the present embodiment contains, as a base oil, at least one oxygen-containing oil having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less, and is used together with a trifluoroethylene refrigerant.

  Further, the working fluid composition for a refrigerator according to the present embodiment includes a refrigerator oil containing at least one oxygen-containing oil having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less as a base oil; And a fluoroethylene refrigerant. The working fluid composition for a refrigerator according to the present embodiment includes a mode containing the refrigerator oil according to the embodiment and a trifluoroethylene refrigerant.

  The base oil according to the present embodiment is at least one oxygen-containing oil having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less. The carbon / oxygen molar ratio of the oxygenated oil is preferably 3.2 or more and 5.0 or less, more preferably 4.0 or more and 5.0 or less from the viewpoint of compatibility and stability with the refrigerant. . The carbon / oxygen molar ratio can be quantitatively analyzed by a general elemental analysis method. As a method of analyzing carbon, there is a method of performing analysis by a thermal conductivity method, a gas chromatography method, or the like after conversion into carbon dioxide by combustion. As a method for analyzing oxygen, a carbon reduction method in which the oxygen is converted into carbon monoxide with carbon and then quantitative analysis is generally performed, and the Shutze-Unterzaucher method is widely used.

  Examples of the oxygen-containing oil include esters, polyvinyl ethers, polyalkylene glycol carbonates, ketones, polyphenyl ethers, silicones, polysiloxanes, perfluoroethers, and the like. Esters, polyvinyl ethers and polyalkylene glycols are preferred, and esters are preferred. More preferred.

  Examples of the ester include an aromatic ester, a dibasic acid ester, a polyol ester, a complex ester, a carbonate ester, and a mixture thereof, and a polyol ester is preferable.

  As the aromatic ester, 1 to 6 valence, preferably 1 to 4 valence, more preferably 1 to 3 valence aromatic carboxylic acid, and 1 to 18 carbon atoms, preferably 1 to 12 aliphatic alcohol Esters and the like are used. Specific examples of the monovalent to hexavalent aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and mixtures thereof. The aliphatic alcohol having 1 to 18 carbon atoms may be linear or branched, and specifically, for example, methanol, ethanol, linear or branched propanol Linear or branched butanol, linear or branched pentanol, linear or branched hexanol, linear or branched heptanol, linear or branched Octanol, linear or branched nonanol, linear or branched decanol, linear or branched undecanol, linear or branched dodecanol, linear or branched Tridecanol, linear or branched tetradecanol, linear or branched pentadecanol, linear or branched hexadecanol, linear or branched heptadecanol, Linear or branched octadecanol and Such as a mixture of these and the like. When a divalent or higher aromatic carboxylic acid is used, it may be a simple ester composed of one kind of aliphatic alcohol or a complex ester composed of two or more kinds of aliphatic alcohols.

  Examples of dibasic acid esters include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, dibasic acids having 5 to 10 carbon atoms such as sebacic acid, methanol, ethanol, propanol, butanol, pentanol, hexanol, Esters with monohydric alcohols having 1 to 15 carbon atoms having a linear or branched alkyl group such as heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, and mixtures thereof are preferred. Used.

  The polyol ester is an ester synthesized from a polyhydric alcohol and a fatty acid. As the fatty acid, a saturated fatty acid is preferably used. The fatty acid preferably has 4 to 9 carbon atoms, and more preferably 5 to 9 carbon atoms. The polyol ester may be a partial ester in which a part of the hydroxyl group of the polyhydric alcohol is not esterified and remains as a hydroxyl group, or may be a complete ester in which all the hydroxyl groups are esterified. It may be a mixture of an ester and a complete ester. The hydroxyl value of the polyol ester is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and still more preferably 3 mgKOH / g or less.

  Among the fatty acids constituting the polyol ester, the proportion of the branched fatty acid is preferably 20 to 100 mol%, more preferably 50 to 100 mol%, even more preferably 70 to 100 mol%, and 90 It is particularly preferable that the content be from 100 to 100 mol%. In particular, the ratio of the branched fatty acid having 4 to 9 carbon atoms is preferably in the above range.

  Specific examples of the branched fatty acid having 4 to 9 carbon atoms include branched butanoic acid, branched pentanoic acid, branched hexanoic acid, branched heptanoic acid, branched octanoic acid, and branched nonane. Acids. More specifically, a fatty acid having a branch at the α-position and / or β-position is preferable, and isobutanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methyl Heptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid and the like are preferable, and among them, 2-ethylhexanoic acid and / or 3,5,5-trimethylhexanoic acid are more preferable.

  Fatty acids may include fatty acids other than branched fatty acids having 4 to 9 carbon atoms. Examples of the fatty acids other than the branched fatty acids having 4 to 9 carbon atoms include linear fatty acids having 4 to 9 carbon atoms (that is, n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octane). Acid, n-nonanoic acid) is preferably used. Among these, pentanoic acid and / or heptanoic acid are more preferred.

  Further, the fatty acid may contain, for example, a fatty acid having 10 to 24 carbon atoms as a fatty acid other than the fatty acid having 4 to 9 carbon atoms. As fatty acids other than fatty acids having 4 to 9 carbon atoms, specifically, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched dodecanoic acid, linear Linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecanoic acid, linear Linear or branched octadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched henicoic acid, linear or branched docosanoic acid, linear Or branched trichosanoic acid, linear or branched tetracosanoic acid, and the like.

  As the polyhydric alcohol constituting the polyol ester, a polyhydric alcohol having 2 to 6 hydroxyl groups is preferably used. The carbon number of the polyhydric alcohol is preferably from 4 to 12, more preferably from 5 to 10. Specifically, hindered alcohols such as neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol and dipentaerythritol are preferred. . Pentaerythritol, or a mixed ester of pentaerythritol and dipentaerythritol) is more preferable because it is particularly excellent in compatibility with a refrigerant and stability in hydrolysis.

  The complex ester is an ester of a fatty acid and a dibasic acid with a monohydric alcohol and a polyol, and the fatty acid, the dibasic acid, the monohydric alcohol and the polyol are dibasic acid esters and polyol esters. The same ones as exemplified in can be used.

  The carbonate is a compound having a carbonate structure represented by the following formula (A) in the molecule. Note that one or more carbonate structures may be present in one molecule.

  As the alcohol constituting the carbonate ester, the above-mentioned aliphatic alcohols and polyols can be used, and polyglycols and those obtained by adding polyglycol to polyols can also be used. Moreover, you may use the thing using carbonic acid, a fatty acid, and / or a dibasic acid.

  Further, among the carbonate esters, those having a structure represented by the following general formula (A-1) are preferable.

[In the above formula (A-1), X ¹ is a hydrogen atom, an alkyl group, a cycloalkyl group or the following general formula (A-2):
_{^{Y 2 - (OA 3) e}} - (A-2)
(In the formula (A-2), Y ² represents a hydrogen atom, an alkyl group or a cycloalkyl group, A ³ represents an alkylene group having 2 to 4 carbon atoms, and e represents an integer of 1 to 50). A ¹ and A ² may be the same or different, each represents an alkylene group having 2 to 4 carbon atoms, Y ¹ represents a hydrogen atom, an alkyl group or a cycloalkyl group, and B represents A represents a residue of a compound having 3 to 20 hydroxyl groups, a represents an integer of 1 to 20, b represents an integer of 0 to 19, and a + b = 3 to 20; c represents an integer of 0 to 50; Each represents an integer of 50]

In the general formula (A-1), X ¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, or a group represented by the general formula (A-2). The number of carbon atoms of the alkyl group is not particularly limited, but is usually 1 to 24, preferably 1 to 18, and more preferably 1 to 12. Further, it may be straight-chain or branched.

  Specific examples of the alkyl group having 1 to 24 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and a Chain or branched pentyl, straight or branched hexyl, straight or branched heptyl, straight or branched octyl, straight or branched nonyl, straight or branched decyl, straight or branched Branched undecyl, straight or branched dodecyl, straight or branched tridecyl, straight or branched tetradecyl, straight or branched pentadecyl, straight or branched hexadecyl, straight or branched Heptadecyl group, straight or branched octadecyl group, straight or branched nonadecyl group, straight or branched icosyl group, straight or branched henicosyl group, straight or branched docosyl group, straight or branched tricosyl group , Linear or branched Tetracosyl and the like group, and the like.

  In addition, specific examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

In the general formula (A-2), examples of the alkylene group having 2 to 4 carbon atoms represented by A ³ include an ethylene group, a propylene group, a trimethylene group, a butylene group, a tetramethylene group, a 1-methyltrimethylene group, Examples thereof include a 2-methyltrimethylene group, a 1,1-dimethylethylene group, and a 1,2-dimethylethylene group.

Y ² in the general formula (A-2) is a hydrogen atom, an alkyl group or a cycloalkylalkyl group. The number of carbon atoms in the alkyl group is not particularly limited, but is usually 1 to 24, preferably 1 to 18, and more preferably 1 to 12. Further, it may be straight-chain or branched. The alkyl group having 1 to 24 carbon atoms, and specific examples include the groups listed in explanation of X ^1.

  In addition, specific examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

Among these, Y ² is preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and is preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, n-hexyl group, iso-hexyl group, n-heptyl group, iso-heptyl group, n-octyl group, iso-octyl group, n-nonyl group, iso-nonyl group, n-decyl group, iso-decyl group, n-undecyl group, iso-undecyl group, n-dodecyl group or iso-dodecyl group More preferably, it is either one. E represents an integer of 1 to 50.

X ¹ is preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a group represented by the general formula (2), and is preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso group. -Propyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, n-hexyl group, iso-hexyl group, n -Heptyl group, iso-heptyl group, n-octyl group, iso-octyl group, n-nonyl group, iso-nonyl group, n-decyl group, iso-decyl group, n-undecyl group, iso-undecyl group, n More preferably, it is any one of a -dodecyl group, an iso-dodecyl group and a group represented by the general formula (2).

  Specific examples of the compound having 3 to 20 hydroxyl groups having B as a residue include the aforementioned polyols.

A ¹ and A ² may be the same or different and each represents an alkylene group having 2 to 4 carbon atoms. Specifically, for example, ethylene group, propylene group, trimethylene group, butylene group, tetramethylene group, 1-methyltrimethylene group, 2-methyltrimethylene group, 1,1-dimethylethylene group, 1,2-dimethylethylene And the like.

Y ¹ is a hydrogen atom, an alkyl group or a cycloalkylalkyl group. The number of carbon atoms in the alkyl group is not particularly limited, but is usually 1 to 24, preferably 1 to 18, and more preferably 1 to 12. Further, it may be straight-chain or branched. The alkyl group having 1 to 24 carbon atoms, and specific examples include the groups listed in explanation of X ^1.

  In addition, specific examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

Among these, Y ¹ is preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and is preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, n-hexyl group, iso-hexyl group, n-heptyl group, iso-heptyl group, n-octyl group, iso-octyl group, n-nonyl group, iso-nonyl group, n-decyl group, iso-decyl group, n-undecyl group, iso-undecyl group, n-dodecyl group or iso-dodecyl group More preferably, it is either one.

  In the above general formulas (A-1) and (A-2), c, d and e represent the degree of polymerization of the polyoxyalkylene moiety, and the polyoxyalkylene moiety may be the same or different in the molecule. In the case of having a plurality of different polyoxyalkylene moieties, the polymerization form of the oxyalkylene group is not particularly limited, and may be a random copolymer or a block copolymer.

  The polyvinyl ether preferably used in the present embodiment has a structural unit represented by the following general formula (1).

[Wherein, R ¹ , R ² and R ³ may be the same or different and each represents a hydrogen atom or a hydrocarbon group, and R ⁴ represents a divalent hydrocarbon group or a divalent ether-bonded oxygen-containing carbon R ⁵ represents a hydrocarbon group, and m represents an integer of 0 or more. When m is 2 or more, a plurality of R ⁴ may be the same or different. ]

The hydrocarbon group represented by R ¹ , R ² and R ³ in the general formula (1) preferably has 1 to 8, more preferably 2 to 7, and still more preferably 3 to 6 carbon atoms. Further, at least one of R ¹ , R ² and R ³ in the general formula (1) is preferably a hydrogen atom, and more preferably all are hydrogen atoms.

The carbon number of the divalent hydrocarbon group and the ether-bonded oxygen-containing hydrocarbon group represented by R ⁴ in the general formula (1) is preferably 1 to 10, more preferably 2 to 8, and still more preferably 3 to 6. is there. Further, the divalent ether-bonded oxygen-containing hydrocarbon group represented by R ⁴ in the general formula (1) may be, for example, a hydrocarbon group having oxygen forming an ether bond in a side chain.

R ⁵ in the general formula (1) is preferably a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, a phenyl group, an aryl group, and an arylalkyl group. Among these, an alkyl group is preferable, and an alkyl group having 1 to 5 carbon atoms is more preferable.

  M in the general formula (1) is preferably from 0 to 20, more preferably from 1 to 18, and even more preferably from 2 to 16. In addition, it is preferable that the average value of m in all the structural units constituting the polyvinyl ether is 0 to 10.

  The polyvinyl ether according to this embodiment may be a homopolymer composed of one kind selected from the structural units represented by the general formula (1), and may be a homopolymer composed of the structural unit represented by the general formula (1). It may be a copolymer composed of two or more kinds selected, or a copolymer composed of the structural unit represented by the general formula (1) and another structural unit. By using polyvinyl ether as a copolymer, lubricating properties, insulating properties, hygroscopic properties, and the like can be further improved while satisfying compatibility of the refrigerating machine oil with the refrigerant. At this time, by appropriately selecting the type of the monomer as the raw material, the type of the initiator, the ratio of the structural units in the copolymer, and the like, it becomes possible to obtain the desired characteristics of the refrigerating machine oil. Therefore, it is possible to freely obtain a refrigerating machine oil according to requirements such as lubricating properties and compatibility depending on the type of the compressor, the material of the lubricating part, the refrigerating capacity, the type of the refrigerant and the like in the refrigerating system or the air conditioning system. The copolymer may be either a block copolymer or a random copolymer.

When the polyvinyl ether according to the present embodiment is a copolymer, the copolymer is a structural unit (1-1) represented by the general formula (1) and in which R ⁵ is an alkyl group having 1 to 3 carbon atoms. ) And a structural unit (1-2) represented by the general formula (1) and wherein R ⁵ is an alkyl group having 3 to 20, preferably 3 to 10, and more preferably 3 to 8 carbon atoms. Is preferred. Particularly preferably an ethyl group as ^{R 5} in the structural unit (1-1), also particularly preferably isobutyl groups as ^{R 5} in the structural unit (1-2). Furthermore, when the polyvinyl ether according to this embodiment is a copolymer containing the above structural units (1-1) and (1-2), the structural unit (1-1) and the structural unit (1-2) Is preferably from 5:95 to 95: 5, more preferably from 20:80 to 90:10, and even more preferably from 70:30 to 90:10. When the molar ratio is within the above range, the compatibility with the refrigerant can be further improved, and the hygroscopicity tends to be reduced.

  The polyvinyl ether according to the present embodiment may be composed of only the structural unit represented by the above general formula (1), but may further include a structural unit represented by the following general formula (2). It may be a polymer. In this case, the copolymer may be either a block copolymer or a random copolymer.

[Wherein, R ^{6 to} R ⁹ may be the same or different from each other, and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. ]

  The polyvinyl ether according to this embodiment is obtained by polymerizing a vinyl ether-based monomer corresponding to the general formula (1), or an olefinic double bond corresponding to the general formula (1) and the vinyl ether-based monomer corresponding to the general formula (2). Can be produced by copolymerization with a hydrocarbon monomer having As the vinyl ether monomer corresponding to the structural unit represented by the general formula (1), a monomer represented by the following general formula (3) is preferable.

^{Wherein, R 1, R 2, R} 3, R 4, R 5 and m ^{is, R 1, R 2, R} 3, R 4, R 5 and the same definition as m, respectively in the general formula (1) Show the contents. ]

  As the polyvinyl ether according to this embodiment, those having the following terminal structure (A) or (B) are preferable.

  (A) One having one end represented by the general formula (4) or (5) and the other end having a structure represented by the general formula (6) or (7).

[Wherein, R ¹¹ , R ²¹ and R ³¹ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴¹ is a divalent having 1 to 10 carbon atoms. It represents a hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group, R ⁵¹ represents a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in the general formula (1). When m is 2 or more, a plurality of R ⁴¹ may be the same or different from each other. ]

[Wherein, R ⁶¹ , R ⁷¹ , R ⁸¹ and R ⁹¹ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. ]

[Wherein, R ¹² , R ²² and R ³² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴² represents a divalent carbon atom having 1 to 10 carbon atoms. It represents a hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group, R ⁵² represents a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in the general formula (1). When m is 2 or more, a plurality of R ⁴¹ may be the same or different. ]

[Wherein, R ⁶² , R ⁷² , R ⁸² and R ⁹² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. ]

  (B) One having one end represented by the general formula (4) or (5) and the other end having a structure represented by the following general formula (8).

[In the formula, R ¹³ , R ²³ and R ³³ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. ]

Among such polyvinyl ether compounds, the following (a), (b), (c), (d) and (e) are particularly suitable as the main components of the refrigerating machine oil according to the present embodiment. is there.
(A) one end has a structure represented by the general formula (4) or (5) and the other end has a structure represented by the general formula (6) or (7); ¹ , R ² and R ³ are all hydrogen atoms, m is an integer of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms. some stuff.
(B) a structure having only the structural unit represented by the general formula (1), wherein one terminal is represented by the general formula (4) and the other terminal is represented by the general formula (6) Wherein R ¹ , R ² and R ³ in the general formula (1) are all hydrogen atoms, m is an integer of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, R ⁵ Is a hydrocarbon group having 1 to 20 carbon atoms.
(C) one terminal has a structure represented by the general formula (4) or (5) and the other terminal has a structure represented by the general formula (8), and R ¹ and R ² in the general formula (1) And R ³ are both hydrogen atoms, m is an integer of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms.
(D) a structure having only the structural unit represented by the general formula (1), wherein one terminal is represented by the general formula (5) and the other terminal is represented by the general formula (8) Wherein R ¹ , R ² and R ³ in the general formula (1) are all hydrogen atoms, m is an integer of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, R ⁵ Is a hydrocarbon group having 1 to 20 carbon atoms.
(E) any one of the above (a), (b), (c) and (d), wherein R ⁵ in the general formula (1) is a hydrocarbon group having 1 to 3 carbon atoms; R ⁵ is a hydrocarbon group having 3 to 20 carbon atoms.

  In the production process of the polyvinyl ether according to the present embodiment, an unsaturated group such as an aryl group may be formed in the molecule due to a side reaction in some cases. However, the thermal stability of the polyvinyl ether itself is improved, and a polymer is formed. From the viewpoint of suppressing the generation of sludge due to the above, and suppressing the generation of peroxide due to a decrease in the antioxidant property (antioxidant property), the polyvinyl ether according to the present embodiment has an unsaturated degree derived from an unsaturated group or the like. Lower ones are preferred. The degree of unsaturation of the polyvinyl ether is preferably 0.04 meq / g or less, more preferably 0.03 meq / g or less, and even more preferably 0.02 meq / g or less. Further, the peroxide value of polyvinyl ether is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, and still more preferably 1.0 meq / kg. The carbonyl value of the polyvinyl ether is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, and even more preferably 20 ppm by weight or less. Further, the hydroxyl value of the polyvinyl ether is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and even more preferably 3 mgKOH / g or less.

  In addition, the degree of unsaturation, the peroxide value and the carbonyl value in the present invention respectively refer to values measured by a standard fat and oil analysis test method established by the Japan Oil Chemists' Society. That is, the degree of unsaturation in the present invention means that a sample is reacted with a whis solution (ICl-acetic acid solution), left in a dark place, excess ICl is reduced to iodine, and the iodine content is titrated with sodium thiosulfate. The iodine value is calculated by converting the iodine value into a vinyl equivalent (meq / g). Further, the peroxide value in the present invention is a value obtained by adding potassium iodide to a sample, titrating the generated free iodine with sodium thiosulfate, and converting the free iodine to the number of milliequivalents per 1 kg of the sample (meq / meq / kg). Further, the carbonyl value in the present invention means that a quinoid ion having a coloring property is produced by reacting 2,4-dinitrophenylhydrazine on a sample, the absorbance of this sample at 480 nm is measured, and cinnamaldehyde is determined in advance as a standard substance. Refers to the value (ppm by weight) converted to the amount of carbonyl based on the calibration curve obtained.

  Polyalkylene glycols have various chemical structures, but polyethylene glycol, polypropylene glycol, polybutylene glycol, and the like are basic compounds, and the unit structures are oxyethylene, oxypropylene, and oxybutylene, each of which is a monomer, ethylene oxide, It can be obtained by ring-opening polymerization using propylene oxide and butylene oxide as raw materials.

Examples of the polyalkylene glycol include a compound represented by the following general formula (9).
^{R α - [(OR β)} f -OR γ] g (9)
[In formula (1), R ^α represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms or a residue of a compound having 2 to 8 hydroxyl groups, and R ^β represents a carbon atom number. Represents an alkylene group of 2 to 4, R ^γ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an acyl group having 2 to 10 carbon atoms, f represents an integer of 1 to 80, and g represents 1 to 8 Represents an integer. ]

In the general formula (9), the alkyl group represented by R ^α or R ^γ may be any of linear, branched and cyclic. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms. If the carbon number of the alkyl group exceeds 10, the compatibility with the working medium tends to decrease.

Further, the alkyl group portion of the acyl group represented by R ^α and R ^γ may be linear, branched, or cyclic. The acyl group preferably has 2 to 10 carbon atoms, and more preferably 2 to 6 carbon atoms. When the carbon number of the acyl group exceeds 10, the compatibility with the working medium is reduced, and phase separation may occur.

When the groups represented by R ^α and R ^γ are both alkyl groups or both acyl groups, the groups represented by R ^α and R ^γ may be the same or different. Further, when g is 2 or more, the groups represented by a plurality of R ^α and R ^γ in the same molecule may be the same or different.

When the group represented by R ^alpha is a residue of a compound having 2-8 hydroxyl groups, the compound may be of the chain, or may be cyclic.

Among the polyalkylene glycols represented by the general formula (9), at least one of R ^α and R ^γ is preferably an alkyl group (more preferably an alkyl group having 1 to 4 carbon atoms), and in particular, methyl A group is preferred from the viewpoint of compatibility with the working medium.

Furthermore, in terms of thermal and chemical stability, it is preferred that both of the R ^alpha and R ^gamma are (more preferably an alkyl group having 1 to 4 carbon atoms) alkyl group is, especially both methyl groups Is preferred.

From the viewpoint of ease of production and cost, one of R ^{α and} R ^γ is preferably an alkyl group (more preferably an alkyl group having 1 to 4 carbon atoms), and the other is preferably a hydrogen atom. Preferably, it is a methyl group and the other is a hydrogen atom. From the viewpoint of lubricity and sludge solubility is preferably both R ^alpha and R ^gamma is a hydrogen atom.

R ^β in the general formula (9) represents an alkylene group having 2 to 4 carbon atoms, and specific examples of such an alkylene group include an ethylene group, a propylene group, and a butylene group. Examples of the oxyalkylene group of the repeating unit represented by OR ^β include an oxyethylene group, an oxypropylene group, and an oxybutylene group. The oxyalkylene groups in the same molecule may be the same, or may contain two or more oxyalkylene groups.

  Among the polyalkylene glycols represented by the general formula (9), from the viewpoint of compatibility with a working medium and viscosity-temperature characteristics, a copolymer containing an oxyethylene group (EO) and an oxypropylene group (PO) is preferred. In such a case, the ratio (EO / (PO + EO)) of the oxyethylene group to the total of the oxyethylene group and the oxypropylene group is 0.1 to 0 in view of the seizure load and the viscosity-temperature characteristics. 0.8, more preferably 0.3 to 0.6.

  Further, the value of EO / (PO + EO) is preferably in the range of 0 to 0.5, more preferably in the range of 0 to 0.2, and more preferably in the range of 0 (0.2). That is, propylene oxide homopolymer) is most preferable.

F in the general formula (9) represents a repeating number of the oxyalkylene group OR ^beta (degree of polymerization) is an integer of 1 to 80. G is an integer of 1 to 8. For example, when ^Rα is an alkyl group or an acyl group, g is 1. If R ^alpha is a residue of a compound having 2-8 hydroxyl groups, g is the number of hydroxyl groups the compound has.

  Further, the product of f and g (fxg) is not particularly limited, but in order to satisfy the above-mentioned required performance as a lubricating oil for refrigerators in a well-balanced manner, the average value of fxg is 6 to 80. Preferably.

  The number average molecular weight of the polyalkylene glycol represented by the general formula (9) is preferably from 500 to 3,000, more preferably from 600 to 2,000, and even more preferably from 600 to 1500, and n is the number average molecular weight of the polyalkylene glycol. Preferably, the number satisfies the above condition. If the number average molecular weight of the polyalkylene glycol is too low, lubricity in the coexistence of a refrigerant will be insufficient. On the other hand, if the number average molecular weight is too high, the composition range showing compatibility with the refrigerant under low temperature conditions becomes narrow, and poor lubrication of the refrigerant compressor and hindrance of heat exchange in the evaporator are likely to occur.

  The hydroxyl value of the polyalkylene glycol is not particularly limited, but is desirably 100 mg KOH / g or less, preferably 50 mg KOH / g or less, more preferably 30 mg KOH / g or less, and most preferably 10 mg KOH / g or less.

The polyalkylene glycol according to the present embodiment can be synthesized using a known method (“Alkylene oxide polymer”, Mitsuta Shibata et al., Kaibundo, issued November 20, 1990). For example, an alcohol ^(R α OH; R α is the formula representing the (9) R ^alpha same definition in) the by addition polymerization of one or more predetermined alkylene oxide, etherified or further terminal hydroxyl group By esterification, a polyalkylene glycol represented by the general formula (9) is obtained. When two or more different alkylene oxides are used in the above-mentioned production process, the resulting polyalkylene glycol may be any of a random copolymer and a block copolymer, but has higher oxidation stability and lubricity. It is preferable that the copolymer is a block copolymer because it tends to be excellent in water resistance, and it is preferable that it is a random copolymer because it tends to be excellent in low-temperature fluidity.

The kinematic viscosity at 100 ° C. of the polyalkylene glycol according to this embodiment is preferably 5 to 20 mm ² / s, preferably 6 to 18 mm ² / s, more preferably 7 to 16 mm ² / s, and still more preferably 8. １５15 mm ² / s, most preferably 10 to 15 mm ² / s. If the kinematic viscosity at 100 ° C. is less than the lower limit, lubricity in the coexistence of the refrigerant becomes insufficient, while if the kinematic viscosity exceeds the upper limit, the composition range showing compatibility with the refrigerant becomes narrower, and the compression of the refrigerant becomes smaller. Poor lubrication of the machine and hindrance of heat exchange in the evaporator are likely to occur. Moreover, kinematic viscosity at 40 ° C. of the polyalkylene glycol is preferably a kinematic viscosity at 40 ° C. is 10 to 200 mm ² / s, more preferably 20 to 150 mm ² / s. If the kinematic viscosity at 40 ° C. is less than 10 mm ² / s, the lubricity and the hermeticity of the compressor tend to decrease, and if it exceeds 200 mm ² / s, the compatibility with the refrigerant under low-temperature conditions Is narrowed, and poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator tend to occur.

  Further, the pour point of the polyalkylene glycol represented by the general formula (9) is preferably −10 ° C. or lower, and more preferably −20 ° C. to −50 ° C. When a polyalkylene glycol having a pour point of −10 ° C. or more is used, the refrigerating machine oil tends to be easily solidified in the refrigerant circulation system at a low temperature.

  In the process of producing the polyalkylene glycol represented by the general formula (9), an alkylene oxide such as propylene oxide may cause a side reaction to form an unsaturated group such as an aryl group in the molecule. When unsaturated groups are formed in the polyalkylene glycol molecule, the thermal stability of the polyalkylene glycol itself decreases, a polymer is formed to form sludge, or the antioxidant (antioxidant) decreases. A phenomenon such as the formation of peroxide is likely to occur. In particular, when a peroxide is generated, it is decomposed to generate a compound having a carbonyl group, and the compound having a carbonyl group generates sludge, which tends to cause clogging of the capillary.

  Therefore, as the polyalkylene glycol according to the present embodiment, those having a low degree of unsaturation due to unsaturated groups and the like are preferable, and specifically, it is preferably 0.04 meq / g or less, and 0.03 meq / g. Or less, and most preferably 0.02 meq / g or less. Further, the peroxide value is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, and most preferably 1.0 meq / kg. Furthermore, the carbonyl value is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, and most preferably 20 ppm by weight or less.

  In the present embodiment, in order to obtain a polyalkylene glycol having a low degree of unsaturation, a low peroxide value and a low carbonyl value, the reaction temperature when reacting propylene oxide is set to 120 ° C. or lower (more preferably 110 ° C. or lower). Is preferred. Also, if an alkaline catalyst is used in the production, if an inorganic adsorbent such as activated carbon, activated clay, bentonite, dolomite, or aluminosilicate is used to remove the catalyst, the degree of unsaturation should be reduced. Can be. In addition, when producing or using the polyalkylene glycol, contact with oxygen can be avoided as much as possible, or an increase in peroxide value or carbonyl value can be prevented by adding an antioxidant.

  The polyalkylene glycol according to the present embodiment needs to have a carbon / oxygen molar ratio within a predetermined range. By selecting and adjusting the type and mixing ratio of the raw material monomers, the molar ratio falls within the above range. Certain polymers can be produced.

  The base oil according to this embodiment may further contain a hydrocarbon-based oil such as a mineral oil, an olefin polymer, a naphthalene compound, or an alkylbenzene, in addition to the oxygen-containing oil. The content of the oxygen-containing oil is preferably 5% by mass or more, more preferably 30% by mass or more, even more preferably 95% by mass or more based on the total amount of the base oil.

  The refrigerating machine oil according to the present embodiment may further contain various additives as necessary. Such additives include acid scavengers, antioxidants, extreme pressure agents, oil agents, defoamers, metal deactivators, antiwear agents, viscosity index improvers, pour point depressants, cleaning dispersants, and the like. No. The content of the additive is preferably 5% by mass or less, more preferably 2% by mass or less, based on the total amount of the refrigerating machine oil.

  It is preferable that the refrigerating machine oil further contains an acid scavenger among the above additives from the viewpoint of further improving the thermal and chemical stability. Examples of the acid scavenger include an epoxy compound and a carbodiimide compound.

  The epoxy compound is not particularly limited, and examples thereof include a glycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an oxirane compound, an alkyloxirane compound, an alicyclic epoxy compound, an epoxidized fatty acid monoester, and an epoxidized vegetable oil. These epoxy compounds can be used alone or in combination of two or more.

  Examples of glycidyl ether type epoxy compounds include n-butylphenyl glycidyl ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, and heptylphenyl glycidyl ether. Octylphenyl glycidyl ether, nonylphenyl glycidyl ether, decylphenyl glycidyl ether, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl ether, neopentyl glycol diglycidyl Ether, trimethylolpropane Li glycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkyleneglycol monoglycidyl ether, and polyalkylene glycol diglycidyl ether.

  Examples of the glycidyl ester type epoxy compound include glycidyl benzoate, glycidyl neodecanoate, glycidyl-2,2-dimethyloctanoate, glycidyl acrylate, and glycidyl methacrylate.

The alicyclic epoxy compound is a compound represented by the following general formula (10) and having a partial structure in which the carbon atom constituting the epoxy group directly constitutes an alicyclic ring.

  Examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and bis (3,4-epoxycyclohexyl) Methyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1.0] hept-3-yl)- Spiro (1,3-dioxane-5,3 ′-[7] oxabicyclo [4.1.0] heptane, 4- (1′-methylepoxyethyl) -1,2-epoxy-2-methylcyclohexane, -Epoxyethyl-1,2-epoxycyclohexane.

  Examples of the allyloxirane compound include 1,2-epoxystyrene and alkyl-1,2-epoxystyrene.

  Examples of the alkyloxirane compound include 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1, Examples thereof include 2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, and 1,2-epoxyicosane.

  Examples of the epoxidized fatty acid monoester include esters of an epoxidized fatty acid having 12 to 20 carbon atoms and an alcohol or phenol or alkylphenol having 1 to 8 carbon atoms. As the epoxidized fatty acid monoester, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxystearic acid are preferably used.

  Epoxidized vegetable oils include epoxy compounds of vegetable oils such as soybean oil, linseed oil, and cottonseed oil.

  Although it does not specifically limit as a carbodiimide compound, For example, dialkyl carbodiimide, diphenyl carbodiimide, and bis (alkylphenyl) carbodiimide can be used. Examples of the dialkylcarbodiimide include diisopropylcarbodiimide, dicyclohexylcarbodiimide, and the like. Examples of bis (alkylphenyl) carbodiimide include ditolylcarbodiimide, bis (isopropylphenyl) carbodiimide, bis (diisopropylphenyl) carbodiimide, bis (triisopropylphenyl) carbodiimide, bis (butylphenyl) carbodiimide, bis (dibutylphenyl) carbodiimide, bis (Nonylphenyl) carbodiimide and the like can be mentioned.

  The content of the base oil in the refrigerating machine oil must be 80% by mass or more based on the total amount of the refrigerating machine oil in order to have excellent properties required for the refrigerating machine oil, such as lubricity, compatibility, thermal and chemical stability, and electrical insulation. Is preferably 90% by mass or more, and more preferably 95% by mass or more.

The kinematic viscosity of the refrigerating machine oil is not particularly limited, but the kinematic viscosity at 40 ° C. is preferably 3 to 1000 mm ² / s, more preferably 4 to 500 mm ² / s, and most preferably 5 to 400 mm ² / s. it can. The kinematic viscosity at 100 ° C. can be preferably 1 to 100 mm ² / s, more preferably ² to 50 mm ² / s.

The volume resistivity of the refrigerating machine oil is not particularly limited, but is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and most preferably 1.0 × 10 ¹¹ Ω · m. m or more. In particular, when used for hermetic refrigerators, high electrical insulation tends to be required. In the present invention, the term “volume resistivity” means a value at 25 ° C. measured in accordance with JIS C 2101 “Test Method for Electrical Insulating Oil”.

  The water content of the refrigerating machine oil is not particularly limited, but can be preferably 200 ppm or less, more preferably 100 ppm or less, and most preferably 50 ppm or less based on the total amount of the refrigerating machine oil. In particular, when used for hermetic refrigerators, it is required that the water content is low from the viewpoint of the thermal and chemical stability of the refrigerator oil and the effect on electrical insulation.

  The acid value of the refrigerating machine oil is not particularly limited, but is preferably for preventing corrosion to metal used for the refrigerating machine or piping, and for preventing decomposition of an ester contained in the refrigerating machine oil according to the present embodiment. Can be 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less. In addition, in this invention, an acid value means the acid value measured based on JISK2501 "Petroleum products and lubricating oil-neutralization number test method."

  The ash content of the refrigerating machine oil is not particularly limited, but is preferably 100 ppm or less, more preferably 50 ppm or less, in order to increase the thermal and chemical stability of the refrigerating machine oil according to the present embodiment and suppress the generation of sludge and the like. . In the present invention, the ash means a value of ash measured in accordance with JIS K2272 “Test method for ash of crude oil and petroleum products and sulfated ash”.

  The refrigerating machine oil according to the present embodiment is used together with a trifluoroethylene (HFO-1123) refrigerant. Further, the working fluid composition for a refrigerator according to the present embodiment contains a trifluoroethylene (HFO-1123) refrigerant.

  The refrigerant used together with the refrigerating machine oil according to the present embodiment and the refrigerant contained in the working fluid composition for a refrigerating machine according to the present embodiment include, in addition to trifluoroethylene (HFO-1123), a saturated fluorocarbon refrigerant, A known refrigerant such as a saturated fluorohydrocarbon refrigerant may be further contained. The content of trifluoroethylene (HFO-1123) is preferably 90% by mass or less, and more preferably 60% by mass or less, based on the total amount of the refrigerant, from the viewpoint of the stability of the refrigerating machine oil in the refrigerant atmosphere. It is more preferably at most 50% by mass, particularly preferably at most 40% by mass, most preferably at most 20% by mass. Further, the content of trifluoroethylene (HFO-1123) is preferably 20% by mass or more, more preferably 40% by mass or more, and more preferably 50% by mass, based on the total amount of the refrigerant, from the viewpoint of GWP reduction. %, More preferably 60% by mass or more, and most preferably 90% by mass or more.

  Examples of the saturated fluorinated hydrocarbon refrigerant include difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2. -Tetrafluoroethane (HFC-134a), 1,1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) ), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,1 Selected from the group consisting of 3,3-pentafluoropropane (HFC-245fa) and 1,1,1,3,3-pentafluorobutane (HFC-365mfc) One or more mixtures can be exemplified that. Among them, difluoromethane (HFC-32) and 1,1,1,2-tetrafluoroethane (HFC-134a) are preferable from the viewpoint of the stability of the refrigerating machine oil under the refrigerant atmosphere and the reduction of GWP.

  Examples of the unsaturated fluorinated hydrocarbon refrigerant include 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 2,3,3 Selected from the group consisting of 3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and 3,3,3-trifluoropropene (HFO-1243zf) Or a mixture of two or more of them. Among these, 2,3,3,3-tetrafluoropropene (HFO-1234yf) is preferable from the viewpoint of the stability of the refrigerating machine oil under the refrigerant atmosphere and the reduction of GWP.

  The mixing ratio of the refrigerating machine oil and the refrigerant in the working fluid composition for the refrigerating machine is not particularly limited, but the refrigerating machine oil is preferably 1 to 500 parts by mass, more preferably 2 to 400 parts by mass with respect to 100 parts by mass of the refrigerant. can do.

  The working fluid composition for a refrigerator according to the present embodiment is preferably used in a room air conditioner or refrigerator having a reciprocating or rotary hermetic compressor, or an open or hermetic car air conditioner. Further, the working fluid composition for a refrigerator and the refrigerating machine oil according to the present embodiment are preferably used for a dehumidifier, a water heater, a freezer, a freezing and refrigerated warehouse, a vending machine, a showcase, a cooling device of a chemical plant, and the like. Further, the working fluid composition for a refrigerator and the refrigerator oil according to the present embodiment are also preferably used for those having a centrifugal compressor.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples.

As base oils 1 to 6, polyol esters of fatty acids and polyhydric alcohols having the compositions shown in Table 1 were prepared. The abbreviations in the table represent the following compounds.
iC4: 2-methylpropanoic acid nC5: n-pentanoic acid iC8: 2-ethylhexanoic acid iC9: 3,5,5-trimethylhexanoic acid nC10: n-decanoic acid iC18: 2-ethylhexadecanoic acid PET: pentaerythritol

Test oils 1 to 7 having the compositions shown in Table 2 were prepared using the base oils 1 to 6 and the additives shown below.
Additive 1: glycidyl neodecanoate additive 2: 2-ethylhexyl glycidyl ether additive 3: bis (diisopropylphenyl) carbodiimide additive 4: diisopropylcarbodiimide

  For each test oil, the following stability tests were performed. Table 2 shows the results.

(Stability test)
The stability test was performed in accordance with JIS K2211-09 (autoclave test). Specifically, 80 g of a test oil whose water content was adjusted to 100 ppm was weighed in an autoclave, and a catalyst (iron, copper, aluminum wire, all having an outer diameter of 1.6 mm × length of 50 mm) and the following: After charging 20 g of any one of the mixed refrigerants A to C, the mixture was heated to 140 ° C., and the acid value (JIS C2101) of the test oil after 150 hours was measured.
Mixed refrigerant A: Mixed refrigerant of 2,3,3,3-tetrafluoropropene (HFO-1234yf) and trifluoroethylene (HFO-1123) (mass ratio (HFO-1234yf / HFO-1123) = 80/20)
Mixed refrigerant B: mixed refrigerant of difluoromethane (HFC-32) and trifluoroethylene (HFO-1123) (mass ratio (HFC-32 / HFO-1123) = 40/60)
Mixed refrigerant C: Mixed refrigerant of 1,1,1,2-tetrafluoroethane (HFC-134a) and trifluoroethylene (HFO-1123) (mass ratio (HFC-134a / HFO-1123) = 20/80)

  In addition, a refrigerant compatibility test shown below was performed on the test oils 1 to 5, and it was confirmed that all the test oils were compatible with the refrigerant.

(Refrigerant compatibility test)
In accordance with JIS-K-2211 "Refrigeration oil""Compatibility test method with refrigerant", 10 g of the test oil is blended with 10 g of each of the mixed refrigerants A to C, and the refrigerant and the refrigerant oil are mixed. At 0 ° C., it was observed whether they were mutually dissolved.

Claims (4)

A carbon / oxygen molar ratio of not less than 3.2 and not more than 5.0, containing at least one oxygen-containing oil selected from the group consisting of polyol esters and polyvinyl ethers as a base oil;
Further containing an acid scavenger,
The content of the oxygenated oil is 95% by mass or more based on the total amount of the base oil;
And trifluoroethylene are used together with the refrigerant containing the difluoro methane, refrigerating machine oil.   The refrigerating machine oil according to claim 1, wherein the content of the trifluoroethylene is 20% by mass or more based on the total amount of the refrigerant. A carbon / oxygen molar ratio of 3.2 or more and 5.0 or less, containing at least one oxygen-containing oil selected from the group consisting of polyol esters and polyvinyl ethers as a base oil, and further containing an acid scavenger; A refrigerating machine oil having a content of the oxygenated oil of 95% by mass or more based on the total amount of the base oil;
A refrigerant containing and trifluoroethylene, a difluoro methane,
And a working fluid composition for a refrigerator.   The working fluid composition for a refrigerator according to claim 3, wherein the content of the trifluoroethylene is 20% by mass or more based on the total amount of the refrigerant.