JP6796438B2 - Refrigerating machine oil and working fluid composition for refrigerating machine - Google Patents

Description

The present invention relates to chiller oil and working fluid compositions for chillers.

Refrigerators such as refrigerators and air conditioners are equipped with a compressor for circulating the refrigerant in the refrigerant circulation system. The compressor is filled with refrigerating machine oil to lubricate the sliding members. Refrigerating machine oil is required to have characteristics such as lubricity and compatibility with a refrigerant.

Refrigerating machine oils generally contain additives that are selected according to such required properties. For example, a phosphorus-based additive is known as an additive that improves lubricity (particularly wear resistance). Patent Document 1 discloses a lubricating oil composition for a refrigerator containing a phosphorus-based additive composed of a phosphoric acid triester such as tricresyl phosphate and triphenyl phosphate.

Japanese Unexamined Patent Publication No. 2008-266423

However, there is still room for improvement in lubricity (particularly seizure resistance) of the refrigerating machine oil containing a phosphorus-based additive such as tricresyl phosphate as disclosed in Patent Document 1.

In view of such circumstances, the present inventors have focused on improving seizure resistance and developed refrigerating machine oil. That is, an object of the present invention is to provide a refrigerator oil and a working fluid composition for a refrigerator having excellent seizure resistance.

［式（Ａ）中、Ｒ^１及びＲ^２はそれぞれ独立に１価の炭化水素基を表し、Ｒ^３は２価の炭化水素基を表し、Ｘは−ＣＯＯＲ^４基を含む極性基を表す。Ｒ^４は水素原子又は１価の炭化水素基を表す。］ The present invention provides a refrigerating machine oil containing a lubricating oil base oil and a compound represented by the following formula (A).

[In the formula (A), R ¹ and R ² each independently represent a monovalent hydrocarbon group, R ³ represents a divalent hydrocarbon group, and X represents a polar group containing -COOR ⁴ groups. R ⁴ represents a hydrogen atom or a monovalent hydrocarbon group. ]

The present invention also provides a working fluid composition for a refrigerator containing the above-mentioned refrigerating machine oil and a refrigerant.

According to the present invention, it is possible to provide a refrigerator oil and a working fluid composition for a refrigerator having excellent seizure resistance.

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

［式（Ａ）中、Ｒ^１及びＲ^２はそれぞれ独立に１価の炭化水素基を表し、Ｒ^３は２価の炭化水素基を表し、Ｘは−ＣＯＯＲ^４基を含む極性基を表す。Ｒ^４は水素原子又は１価の炭化水素基を表す。］ The refrigerating machine oil contains a lubricating oil base oil and a compound represented by the following formula (A).

[In the formula (A), R ¹ and R ² each independently represent a monovalent hydrocarbon group, R ³ represents a divalent hydrocarbon group, and X represents a polar group containing -COOR ⁴ groups. R ⁴ represents a hydrogen atom or a monovalent hydrocarbon group. ]

Examples of the lubricating oil base oil include hydrocarbon oils and oxygen-containing oils. Examples of the hydrocarbon oil include mineral oil-based hydrocarbon oils and synthetic hydrocarbon oils. Examples of the oxygen-containing oil include esters, ethers, carbonates, ketones, silicones, polysiloxanes and the like.

Mineral oil-based hydrocarbon oils are solvent-removed, solvent-refined, hydrorefined, hydrocracked, and solvent-desorbed from lubricating oil distillates obtained by atmospheric distillation and vacuum distillation of paraffin-based and naphthen-based crude oils. It can be obtained by purification by methods such as brazing, hydrocarbon removal, white clay treatment, and sulfuric acid washing. These purification methods may be used alone or in combination of two or more.

Examples of the synthetic hydrocarbon oil include alkylbenzene, alkylnaphthalene, polyα-olefin (PAO), polybutene, ethylene-α-olefin copolymer and the like.

The alkylbenzene may be at least one selected from the group consisting of the following alkylbenzenes (a1) and alkylbenzenes (a2).
Alkylbenzene (a1): Alkylbenzene having 1 to 4 alkyl groups having 1 to 19 carbon atoms and having a total number of carbon atoms of 9 to 19 (preferably 1 alkyl group having 1 to 15 carbon atoms). Alkylbenzene having ~ 4 and having a total number of carbon atoms of 9 to 15 alkyl groups)
Alkylbenzene (a2): Alkylbenzene having 1 to 4 alkyl groups having 1 to 40 carbon atoms and having a total carbon number of 20 to 40 of the alkyl groups (preferably 1 alkyl group having 1 to 30 carbon atoms). Alkylbenzene having ~ 4 and having a total number of carbon atoms of 20 to 30 alkyl groups)

Specific examples of the alkyl group having 1 to 19 carbon atoms of the alkylbenzene (a1) include a methyl group, an ethyl group, a propyl group (including all isomers, the same applies hereinafter), a butyl group, a pentyl group, and a hexyl. Examples thereof include group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecil group and eicosyl group. These alkyl groups may be linear or branched, and are preferably branched from the viewpoint of stability, viscosity characteristics and the like. The alkyl group is more preferably a branched alkyl group derived from an oligomer of an olefin such as propylene, butene or isobutylene, especially from the point of view of availability.

The number of alkyl groups in alkylbenzene (a1) is 1 to 4, preferably 1 or 2 (ie, monoalkylbenzene, dialkylbenzene, or a mixture thereof) from the viewpoint of stability and availability. is there.

The alkylbenzene (a1) may be an alkylbenzene having a single structure, and satisfies the condition that it has 1 to 4 alkyl groups having 1 to 19 carbon atoms and the total number of carbon atoms of the alkyl groups is 9 to 19. As long as it is alkylbenzene, it may be a mixture of alkylbenzenes having different structures.

Specific examples of the alkyl group having 1 to 40 carbon atoms of the alkylbenzene (a2) include a methyl group, an ethyl group, a propyl group (including all isomers, the same applies hereinafter), a butyl group, a pentyl group, and a hexyl. Group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecil group, icosyl group, henicosyl group, docosyl group, Tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, hentoriacontyl group, dotriacontyl group, tritoriacontyl group, tetratriacontyl group, pentatriacontyl group, hexa Examples thereof include a triacontyl group, a heptatriacontyl group, an octatriacontyl group, a nonatriacontyl group and a tetracontyl group. These alkyl groups may be linear or branched, and are preferably branched from the viewpoint of stability, viscosity characteristics and the like. The alkyl group is more preferably a branched alkyl group derived from an oligomer of an olefin such as propylene, butene or isobutylene, especially from the point of view of availability. Alkyl groups are more preferably linear or branched from linear alkylating agents such as linear paraffin, linear α-olefins or halides thereof, from the point of higher flammability. It is an alkyl group, more preferably a branched alkyl group.

The number of alkyl groups in alkylbenzene (a2) is 1 to 4, preferably 1 or 2 (ie, monoalkylbenzene, dialkylbenzene, or a mixture thereof) from the viewpoint of stability and availability. is there.

The alkylbenzene (a2) may be an alkylbenzene having a single structure, and satisfies the condition that it has 1 to 4 alkyl groups having 1 to 40 carbon atoms and the total number of carbon atoms of the alkyl groups is 20 to 40. As long as it is alkylbenzene, it may be a mixture of alkylbenzenes having different structures.

The poly α-olefin (PAO) is a compound obtained by polymerizing several molecules of a linear olefin having 6 to 18 carbon atoms having a double bond on only one of the terminals and then hydrogenating the polyα-olefin (PAO). The poly α-olefin may be, for example, an isoparaffin having a molecular weight distribution centered on a trimer or tetramer of α-decene having 10 carbon atoms or α-dodecene having 12 carbon atoms.

Examples of the ester include aromatic esters, dibasic acid esters, polyol esters, complex esters, carbonic acid esters, and mixtures thereof. The ester is preferably a polyol ester or a complex ester.

Polypolyesters are esters of polyhydric alcohols and fatty acids. The fatty acid is preferably a saturated fatty acid. The carbon number of the fatty acid is preferably 4 to 20, more preferably 4 to 18, still more preferably 4 to 9, and particularly preferably 5 to 9. The polyol ester may be a partial ester in which some of the hydroxyl groups of the polyhydric alcohol are not esterified and remain as hydroxyl groups, or may be a complete ester in which all the hydroxyl groups are esterified, or a partial ester. 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, still more preferably 3 mgKOH / g or less.

The proportion of fatty acids having 4 to 20 carbon atoms among the fatty acids constituting the polyol ester is preferably 20 to 100 mol%, more preferably 50 to 100 mol%, still more preferably 70 to 100 mol%, and particularly preferably 90. ~ 100 mol%.

Specific examples of fatty acids having 4 to 20 carbon atoms include butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid and pentadecanoic acid. , Hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanic acid and valeric acid. These fatty acids may be linear or branched. The fatty acid is preferably a fatty acid having a branch at the α-position and / or β-position, and more preferably 2-methylpropanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethyl. It is selected from pentanic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid and 2-ethylhexadecanoic acid, more preferably 2-methylpropanoic acid and 3,5,5-. Selected from trimethylhexanoic acid.

The fatty acid may contain a fatty acid other than the fatty acid having 4 to 20 carbon atoms. The fatty acid other than the fatty acid having 4 to 20 carbon atoms may be, for example, a fatty acid having 21 to 24 carbon atoms. The fatty acid having 21 to 24 carbon atoms may be henicoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid or the like, and may be linear or branched.

The polyhydric alcohol constituting the polyol ester is preferably a polyhydric alcohol having 2 to 6 hydroxyl groups. The polyhydric alcohol preferably has 4 to 12 carbon atoms, more preferably 5 to 10 carbon atoms. The polyhydric alcohol is preferably a hindered such as neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, dipentaerythritol. It is an alcohol, and is more preferably pentaerythritol, dipentaerythritol, or a mixed ester of pentaerythritol and dipentaerythritol because it is particularly excellent in compatibility with a refrigerant and hydrolysis stability.

The complex ester is, for example, an ester synthesized by the following method (a) or (b).
(A) By adjusting the molar ratio of the polyhydric alcohol to the polybasic acid, an ester intermediate in which some of the carboxyl groups of the polybasic acid remain without esterification is synthesized, and then the remaining carboxyl groups are obtained. Method of esterification with monohydric alcohol (b) By adjusting the molar ratio of polyhydric alcohol to polybasic acid, an ester intermediate in which some of the hydroxyl groups of the polyhydric alcohol remain without esterification is synthesized. Next, a method of esterifying the remaining hydroxyl group with a monohydric fatty acid.

The complex ester obtained by the method (b) above is slightly inferior in stability to the complex ester obtained by the method (a) above because a relatively strong acid is produced when hydrolyzed when used as a refrigerating machine oil. There is a tendency. Therefore, the complex ester is preferably a complex ester obtained by the method (a) having higher stability.

The complex ester preferably has at least one selected from polyhydric alcohols having 2 to 4 hydroxyl groups, at least one selected from polybasic acids having 6 to 12 carbon atoms, and 4 to 18 carbon atoms. It is an ester synthesized from at least one selected from a monohydric alcohol and a monohydric fatty acid having 2 to 12 carbon atoms.

Examples of the polyhydric alcohol having 2 to 4 hydroxyl groups include neopentyl glycol, trimethylolpropane, pentaerythritol and the like. Polyhydric alcohols having 2 to 4 hydroxyl groups are preferably neopentyl glycol and trimethylol from the viewpoint of ensuring a suitable viscosity when a complex ester is used as a base oil and obtaining good low temperature characteristics. Neopentyl glycol is more preferred because it is selected from propane and can be widely adjusted in viscosity.

From the viewpoint of excellent lubricity, the polyhydric alcohol constituting the complex ester is preferably a dihydric alcohol having 2 to 10 carbon atoms other than neopentyl glycol, in addition to the polyhydric alcohol having 2 to 4 hydroxyl groups. Is further contained. Examples of dihydric alcohols having 2 to 10 carbon atoms other than neopentyl glycol include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, 2-methyl-1,3-propanediol, and 3-methyl-1,5. -Pentanediol, 2,2-diethyl-1,3-pentanediol and the like can be mentioned. The dihydric alcohol is preferably butanediol from the viewpoint of excellent characteristics of the lubricating oil base oil. Examples of butanediol include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol. Butanediol is preferably selected from 1,3-butanediol and 1,4-butanediol from the viewpoint of obtaining good properties. The amount of divalent alcohol having 2 to 10 carbon atoms other than neopentyl glycol is preferably 1.2 mol or less, more preferably 0.8 mol or less, based on 1 mol of the polyhydric alcohol having 2 to 4 hydroxyl groups. It is mol or less, more preferably 0.4 mol or less.

Examples of the polybasic acid having 6 to 12 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and trimellitic acid. The polybasic acid is preferably selected from adipic acid and sebacic acid, and more preferably adipic acid, from the viewpoint of excellent balance of properties of the synthesized ester and easy availability. The amount of the polybasic acid having 6 to 12 carbon atoms is preferably 0.4 mol to 4 mol, more preferably 0.5 mol to 3 mol, based on 1 mol of the polyhydric alcohol having 2 to 4 hydroxyl groups. It is mol, more preferably 0.6 mol to 2.5 mol.

Examples of monohydric alcohols having 4 to 18 carbon atoms include fatty alcohols such as butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, and oleyl alcohol. These monohydric alcohols may be linear or branched. The monohydric alcohol having 4 to 18 carbon atoms is preferably a monohydric alcohol having 6 to 10 carbon atoms, and more preferably a monohydric alcohol having 8 to 10 carbon atoms from the viewpoint of the balance of characteristics. The monohydric alcohol is more preferably selected from 2-ethylhexanol and 3,5,5-trimethylhexanol from the viewpoint of improving the low temperature characteristics of the synthesized complex ester.

Examples of monovalent fatty acids having 2 to 12 carbon atoms include ethane acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptic acid, octanoic acid, nonanoic acid, decanoic acid, and dodecanoic acid. These monovalent fatty acids may be linear or branched. The monovalent fatty acid having 2 to 12 carbon atoms is preferably a monovalent fatty acid having 8 to 10 carbon atoms, and among these, 2-ethylhexanoic acid and 3,5,5-trimethyl are more preferable from the viewpoint of low temperature characteristics. It is a hexanoic acid.

Examples of the ether include polyvinyl ether, polyalkylene glycol, polyphenyl ether, perfluoro ether, and a mixture thereof. The ether is preferably selected from polyvinyl ether and polyalkylene glycol, and more preferably polyvinyl ether.

［式（１）中、Ｒ^５０、Ｒ^５１及びＲ^５２は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭化水素基を表し、Ｒ^５３は２価の炭化水素基又は２価のエーテル結合酸素含有炭化水素基を表し、Ｒ^５４は炭化水素基を表し、ｍは０以上の整数を表す。ｍが２以上である場合には、複数のＲ^５３は互いに同一でも異なっていてもよい。］ Polyvinyl ether has a structural unit represented by the following formula (1).

[In formula (1), R ⁵⁰ , R ⁵¹ and R ⁵² may be the same or different from each other and represent hydrogen atoms or hydrocarbon groups, respectively, where R ⁵³ is a divalent hydrocarbon group or a divalent ether bond. It represents an oxygen-containing hydrocarbon group, R ⁵⁴ represents a hydrocarbon group, and m represents an integer greater than or equal to 0. When m is 2 or more, the plurality of R ^53s may be the same or different from each other. ]

The hydrocarbon groups represented by R ⁵⁰ , R ⁵¹ and R ⁵² have preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 8 or less, more preferably 7. Below, it is more preferably 6 or less. Preferably at least one of R ^{50, R 51} and ^{R 52} is a hydrogen ^atom, and more preferably all R ^{50, R 51} and ^{R 52} are hydrogen atoms.

The number of carbon atoms of the divalent hydrocarbon group represented by R ⁵³ and the ether-bonded oxygen-containing hydrocarbon group is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 10 or less. , More preferably 8 or less, still more preferably 6 or less. The divalent ether-bonded oxygen-containing hydrocarbon group represented by R ⁵³ may be, for example, a hydrocarbon group having oxygen forming an ether bond in the side chain.

R ⁵⁴ is preferably a hydrocarbon group having 1 to 20 carbon atoms. Examples of this hydrocarbon group include an alkyl group, a cycloalkyl group, a phenyl group, an aryl group, and an arylalkyl group. The hydrocarbon group is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms.

m is preferably 0 or more, more preferably 1 or more, still more preferably 2 or more, and preferably 20 or less, more preferably 18 or less, still more preferably 16 or less. The average value of m in all the structural units constituting the polyvinyl ether is preferably 0 to 10.

The polyvinyl ether may be a copolymer composed of one type selected from the structural units represented by the formula (1), or may be composed of two or more types selected from the structural units represented by the formula (1). It may be a copolymer to be used, or it may be a copolymer composed of a structural unit represented by the formula (1) and another structural unit. Since the polyvinyl ether is a copolymer, the lubricity, the insulating property, the hygroscopic property and the like can be further improved while satisfying the 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 is possible to obtain the desired characteristics of the refrigerating machine oil. The copolymer may be either a block copolymer or a random copolymer.

When the polyvinyl ether is a copolymer, the copolymer is preferably represented by the above formula (1) and has a structural unit (1-1) in which R ⁵⁴ is an alkyl group having 1 to 3 carbon atoms and the above. It has a structural unit (1-2) represented by the formula (1) and in which R ⁵⁴ is an alkyl group having 3 to 20 carbon atoms. The carbon number of R ⁵⁴ in the structural unit (1-2) is preferably 3 to 10, and more preferably 3 to 8. R ⁵⁴ in the structural unit (1-1) is particularly preferably an ethyl group, and R ⁵⁴ in the structural unit (1-2) is particularly preferably an isobutyl group. When the polyvinyl ether is a copolymer having the above structural units (1-1) and (1-2), the molar ratio of the structural unit (1-1) to the structural unit (1-2) is preferably It is 5:95 to 95:10, more preferably 20:80 to 90:10, and even more preferably 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 lowered.

The polyvinyl ether may be composed of only the structural units represented by the above formula (1), or may be a copolymer further having the structural units represented by the following formula (2). .. In this case, the copolymer may be either a block copolymer or a random copolymer.

［式（２）中、Ｒ^５５〜Ｒ^５８は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜２０の炭化水素基を表す。］

[In formula (2), R ^{55 to} R ⁵⁸ may be the same or different from each other, and represent hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, respectively. ]

The polyvinyl ether is represented by, for example, the polymerization of a vinyl ether-based monomer corresponding to the structural unit represented by the formula (1), or the vinyl ether-based monomer corresponding to the structural unit represented by the formula (1) and the formula (2). It is produced by copolymerization with a hydrocarbon monomer having an olefinic double bond corresponding to the structural unit to be formed. As the vinyl ether-based monomer corresponding to the structural unit represented by the formula (1), the monomer represented by the following formula (3) is suitable.

［式中、Ｒ^５０、Ｒ^５１、Ｒ^５２、Ｒ^５３、Ｒ^５４及びｍは、それぞれ式（１）中のＲ^５０、Ｒ^５１、Ｒ^５２、Ｒ^５３、Ｒ^５４及びｍと同一の定義内容を示す。］

^{Wherein, R 50, R 51, R} 52, R 53, R 54 and ^{m, R 50, R 51, R} 52, R 53, R 54 and the same definition and m, respectively formula (1) Is shown. ]

Polyvinyl ether preferably has the following terminal structure (I) or (II).

(I) A structure in which one end is represented by the formula (4) or (5) and the other end is represented by the formula (6) or (7).

［式（４）中、Ｒ^５９、Ｒ^６０及びＲ^６１は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜８の炭化水素基を示し、Ｒ^６２は炭素数１〜１０の２価の炭化水素基又は２価のエーテル結合酸素含有炭化水素基を示し、Ｒ^６３は炭素数１〜２０の炭化水素基を示し、ｍは式（１）中のｍと同一の定義内容を示す。ｍが２以上の場合には、複数のＲ^６２は互いに同一でも異なっていてもよい。］

[In formula (4), R ⁵⁹ , R ⁶⁰ and R ⁶¹ may be the same or different from each other, and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁶² has 1 to 10 carbon atoms. It indicates a divalent hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group, R ⁶³ indicates a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in the formula (1). Shown. When m is 2 or more, the plurality of R ^62s may be the same or different from each other. ]

［式（５）中、Ｒ^６４、Ｒ^６５、Ｒ^６６及びＲ^６７は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜２０の炭化水素基を示す。］

[In formula (5), R ⁶⁴ , R ⁶⁵ , R ⁶⁶ and R ⁶⁷ 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. ]

［式（６）中、Ｒ^６８，Ｒ^６９及びＲ^７０は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜８の炭化水素基を示し、Ｒ^７１は炭素数１〜１０の２価の炭化水素基又は２価のエーテル結合酸素含有炭化水素基を示し、Ｒ^７２は炭素数１〜２０の炭化水素基を示し、ｍは式（１）中のｍと同一の定義内容を示す。ｍが２以上の場合には、複数のＲ^７１は同一でも異なっていてもよい。］

[In formula (6), R ⁶⁸ , R ⁶⁹ and R ⁷⁰ may be the same or different from each other, and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁷¹ has 1 to 10 carbon atoms. It indicates a divalent hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group, R ⁷² indicates a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in the formula (1). Shown. When m is 2 or more, the plurality of R ^71s may be the same or different. ]

［式（７）中、Ｒ^７３、Ｒ^７４、Ｒ^７５及びＲ^７６は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜２０の炭化水素基を示す。］

[In formula (7), R ⁷³ , R ⁷⁴ , R ⁷⁵ and R ⁷⁶ 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. ]

(II) A structure in which one end is represented by the above formula (4) or (5) and the other end is represented by the following formula (8).

［式（８）中、Ｒ^７７、Ｒ^７８及びＲ^７９は互いに同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜８の炭化水素基を示す。］

[In formula (8), R ⁷⁷ , R ⁷⁸ and R ⁷⁹ may be the same or different from each other, and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. ]

Among such polyvinyl ethers, the polyvinyl ethers (a), (b), (c), (d) and (e) listed below are particularly suitable as the base oil.
(A) It has a structure in which one end is represented by the formula (4) or (5) and the other end is represented by the formula (6) or (7), and R ⁵⁰ , R in the formula (1). Both ⁵¹ and R ⁵² are hydrogen atoms, m is an integer of 0 to 4, R ⁵³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, and R ⁵⁴ is a hydrocarbon group having 1 to 20 carbon atoms. ..
(B) It has only the structural unit represented by the formula (1), and has a structure in which one end is represented by the formula (4) and the other end is represented by the formula (6). , R ⁵⁰ , R ⁵¹ and R ⁵² in the formula (1) are all hydrogen atoms, m is an integer of 0 to 4, R ⁵³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, and R ⁵⁴ is 1 carbon atom. Polyvinyl ether which is a hydrocarbon group of ~ 20.
(C) It has a structure in which one end is represented by the formula (4) or (5) and the other end is represented by the formula (8), and R ⁵⁰ , R ⁵¹ and R ⁵² in the formula (1). Is a hydrogen atom, m is an integer of 0 to 4, R ⁵³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, and R ⁵⁴ is a hydrocarbon group having 1 to 20 carbon atoms.
(D) It has only the structural unit represented by the formula (1), and has a structure in which one end is represented by the formula (5) and the other end is represented by the formula (8). , R ⁵⁰ , R ⁵¹ and R ⁵² in the formula (1) are all hydrogen atoms, m is an integer of 0 to 4, R ⁵³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, and R ⁵⁴ is 1 carbon atom. Polyvinyl ether which is a hydrocarbon group of ~ 20.
(E) A structural unit according to any one of (a), (b), (c) and (d) above, wherein R ⁵⁴ in the formula (1) is a hydrocarbon group having 1 to 3 carbon atoms and the R. A polyvinyl ether having a structural unit in which ⁵⁴ is a hydrocarbon group having 3 to 20 carbon atoms.

The weight average molecular weight of polyvinyl ether is preferably 500 or more, more preferably 600 or more, and preferably 3000 or less, more preferably 2000 or less, still more preferably 1500 or less. When the weight average molecular weight of polyvinyl ether is 500 or more, the refrigerating machine oil is excellent in lubricity in the presence of a refrigerant. When the weight average molecular weight is 3000 or less, the composition range showing compatibility with the refrigerant is widened under low temperature conditions, and it is possible to suppress poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator.

The number average molecular weight of polyvinyl ether is preferably 500 or more, more preferably 600 or more, and preferably 3000 or less, more preferably 2000 or less, still more preferably 1500 or less. When the number average molecular weight of polyvinyl ether is 500 or more, the refrigerating machine oil is excellent in lubricity in the presence of a refrigerant. When the number average molecular weight is 3000 or less, the composition range showing compatibility with the refrigerant under low temperature conditions becomes wide, and it is possible to suppress poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator.

The weight average molecular weight and the number average molecular weight of the polyvinyl ether mean the weight average molecular weight and the number average molecular weight (polystyrene (standard sample) conversion value) obtained by GPC analysis, respectively. The weight average molecular weight and the number average molecular weight can be measured, for example, as follows.

Chloroform is used as a solvent and diluted to prepare a solution having a polyvinyl ether concentration of 1% by mass. The solution is analyzed using a GPC apparatus (Waters Alliance 2695). A column with a solvent flow rate of 1 ml / min and an analyzable molecular weight of 100 to 10000 is used, and the analysis is carried out using a refractive index detector. The relationship between the column retention time and the molecular weight is determined using a polystyrene standard having a clear molecular weight, a calibration curve is prepared separately, and the molecular weight of the sample is determined from the obtained retention time.

The degree of unsaturation of polyvinyl ether is preferably 0.04 meq / g or less, more preferably 0.03 meq / g or less, still more preferably 0.02 meq / g or less. The peroxide value of polyvinyl ether is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, still more preferably 1.0 meq / kg or less. The carbonyl value of polyvinyl ether is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, still more preferably 20 ppm by weight or less. The hydroxyl value of polyvinyl ether is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, still more preferably 3 mgKOH / g or less.

The degree of unsaturation, the peroxide value, and the carbonyl value in the present invention are values measured by the standard fat analysis test method established by the Japan Oil Chemists' Society, respectively. That is, the degree of unsaturatedness in the present invention is determined by reacting a sample with a whistle solution (ICl-acetic acid solution) and leaving it in a dark place, then reducing excess ICl to iodine and titrating the iodine content with sodium thiosulfate. Iodine value is calculated, and this iodine value is converted to vinyl equivalent (meq / g). The peroxide value in the present invention is a value (meq / kg) obtained by adding potassium iodide to a sample, titrating the generated free iodine with sodium thiosulfate, and converting this free iodine into milliequivalents with respect to 1 kg of the sample. Say. The carbonyl value in the present invention is a calibration curve obtained by allowing 2,4-dinitrophenylhydrazine to act on a sample to generate a chromogenic quinoid ion, measuring the absorbance of this sample at 480 nm, and obtaining cinnamaldehyde as a standard substance in advance. It means a value (weight ppm) converted into the amount of carbonyl based on. The hydroxyl value in the present invention means the hydroxyl value measured in accordance with JIS K0070: 1992.

Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol and the like. The polyalkylene glycol has oxyethylene, oxypropylene, oxybutylene and the like as structural units. Polyalkylene glycols having these structural units can be obtained by ring-opening polymerization using the monomers ethylene oxide, propylene oxide, and butylene oxide as raw materials, respectively.

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

The alkyl group represented by R ^α and R ^γ may be linear, branched or cyclic. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms. When the number of carbon atoms of the alkyl group is 10 or less, the refrigerating machine oil tends to have excellent compatibility with the refrigerant.

The alkyl group portion of the acyl group represented by R ^α and R ^γ may be linear, branched or cyclic. The acyl group has preferably 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms. When the number of carbon atoms of the acyl group is 10 or less, the refrigerating machine oil has excellent compatibility with the refrigerant, and phase separation tends to be difficult to occur.

When the groups represented by R ^α and R ^γ are both alkyl groups or both are acyl groups, the groups represented by R ^α and R ^γ may be the same or different. 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 cyclic be a chain.

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 further preferably a methyl group from the viewpoint of excellent compatibility. From the viewpoint of excellent thermal and chemical stability, both R ^α and R ^γ are preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably a methyl group. 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 a hydrogen atom, which is more preferable. One is a methyl group and the other is a hydrogen atom. From the viewpoint of excellent lubricity and sludge solubility, both R ^α and R ^γ are preferably hydrogen atoms.

R ^beta represents an alkylene group having 2 to 4 carbon atoms, examples of such alkylene groups include ethylene, propylene, butylene, and the like. ^Examples of the repeating unit oxyalkylene group represented by OR ^β include an oxyethylene group, an oxypropylene group and an oxybutylene group. The oxyalkylene group represented by (OR ^β ) _f may be composed of one kind of oxyalkylene group or two or more kinds of oxyalkylene group.

The polyalkylene glycol represented by the formula (9) is preferably a copolymer containing an oxyethylene group (EO) and an oxypropylene group (PO) from the viewpoint of excellent compatibility with the refrigerant and viscosity-temperature characteristics. Is. In this case, the ratio of the oxyethylene group (EO / (PO + EO)) to the total of the oxyethylene group and the oxypropylene group is preferably 0.1 to 0.8 from the viewpoint of excellent baking load and viscosity-temperature characteristics. , More preferably 0.3 to 0.6. From the viewpoint of excellent hygroscopicity and thermal / oxidative stability, EO / (PO + EO) is preferably 0 to 0.5, more preferably 0 to 0.2, and even more preferably 0 (that is, a propylene oxide homopolymer). Is.

f represents the number of repetitions (degree of polymerization) of the oxyalkylene group OR ^β , and is an integer of 1 to 80. g is an integer of 1-8. For example, if R ^α is an alkyl group or an acyl group, g is 1. When R ^α is a residue of a compound having 2 to 8 hydroxyl groups, g is the number of hydroxyl groups of the compound.

In the polyalkylene glycol represented by the formula (9), the average value of the product (f × g) of f and g is preferably 6 to 80 from the viewpoint of satisfying the required performance as a refrigerating machine oil in a well-balanced manner.

The weight average molecular weight of the polyalkylene glycol is preferably 500 or more, more preferably 600 or more, and preferably 3000 or less, more preferably 2000 or less, still more preferably 1500 or less. When the weight average molecular weight of the polyalkylene glycol is 500 or more, the refrigerating machine oil is excellent in lubricity in the presence of a refrigerant. When the weight average molecular weight is 3000 or less, the refrigerating machine oil has a wide composition range showing compatibility with the refrigerant under low temperature conditions, and it is possible to suppress poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator.

The number average molecular weight of the polyalkylene glycol is preferably 500 or more, more preferably 600 or more, and preferably 3000 or less, more preferably 2000 or less, still more preferably 1500 or less. When the number average molecular weight of the polyalkylene glycol is 500 or more, the refrigerating machine oil is excellent in lubricity in the presence of a refrigerant. When the number average molecular weight is 3000 or less, the refrigerating machine oil has a wide composition range showing compatibility with the refrigerant under low temperature conditions, and it is possible to suppress poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator.

The weight average molecular weight and the number average molecular weight of the polyalkylene glycol mean the weight average molecular weight and the number average molecular weight (polypropylene glycol (standard sample) conversion value) obtained by GPC analysis, respectively. The weight average molecular weight and the number average molecular weight can be measured, for example, as follows.

Chloroform is used as a solvent and diluted to prepare a solution having a polyalkylene glycol concentration of 1% by mass. The solution is analyzed using a GPC apparatus (Waters Alliance 2695). A column with a solvent flow rate of 1 ml / min and an analyzable molecular weight of 100 to 10000 is used, and the analysis is carried out using a refractive index detector. The relationship between the column retention time and the molecular weight is determined using a polyalkylene glycol standard having a clear molecular weight, a calibration curve is prepared separately, and the molecular weight of the sample is determined from the obtained retention time.

The hydroxyl value of the polyalkylene glycol is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less, still more preferably 30 mgKOH / g or less, and most preferably 10 mgKOH / g or less.

Polyalkylene glycols can be synthesized using known methods ("alkylene oxide polymer", Mita Shibata et al., Kaibundo, published on November 20, 1990). For example, an alcohol ^(R α OH; R α formula (9) R ^alpha and represent the same definition in) etherified or esterified into by addition polymerization of one or more predetermined alkylene oxide, further terminal hydroxyl groups By doing so, the polyalkylene glycol represented by the formula (9) can be obtained. When two or more kinds of alkylene oxides are used in the above production process, the obtained polyalkylene glycol may be either a random copolymer or a block copolymer, but tends to be more excellent in oxidative stability and lubricity. From the point of view, it is preferably a block copolymer, and from the point of view that it tends to be more excellent in low-temperature fluidity, it is preferably a random copolymer.

The degree of unsaturation of the polyalkylene glycol is preferably 0.04 meq / g or less, more preferably 0.03 meq / g or less, still more preferably 0.02 meq / g or less. The peroxide value is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, still more preferably 1.0 meq / kg or less. The carbonyl value is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, still more preferably 20 ppm by weight or less.

The lubricating oil base oil is preferably at least one selected from oxygen-containing oils, more preferably at least one selected from esters and ethers, and even more preferably esters.

The kinematic viscosity of the lubricating oil base oil at 40 ° C. is preferably 3 mm ² / s or more, more preferably 4 mm ² / s or more, and further preferably 5 mm ² / s or more. The kinematic viscosity of the lubricating oil base oil at 40 ° C. is preferably 1000 mm ² / s or less, more preferably 500 mm ² / s or less, and further preferably 400 mm ² / s or less. The kinematic viscosity of the lubricating oil base oil at 100 ° C. is preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. The kinematic viscosity of the lubricating oil base oil at 100 ° C. is preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less. The kinematic viscosity in the present invention means the kinematic viscosity measured according to JIS K2283: 2000.

The content of the lubricating oil base oil 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 refrigerating machine oil.

The refrigerating machine oil contains a compound represented by the following formula (A). Therefore, this refrigerating machine oil is superior in terms of seizure resistance (particularly the effect of improving seizure resistance per unit phosphorus amount) as compared with the case where a conventional phosphorus-based additive such as tricresyl phosphate is contained. ..

In the formula (A), R ¹ and R ² each independently represent a monovalent hydrocarbon group, which may be an alkyl group or an aryl group, and is excellent in seizure resistance in the presence of a refrigerant. It is preferably an alkyl group. The alkyl group may be linear or branched. The monovalent hydrocarbon group represented by R ¹ and R ² or the alkyl group or aryl group has 2 to 18, 2 to 16, 2 to 14, 2 to 12, 2 to 10 or 2 to 8 carbon atoms. It may be there.

R ³ represents a divalent hydrocarbon group, which may be, for example, a linear or branched alkylene group. The number of carbon atoms of the divalent hydrocarbon group or alkylene group represented by R ³ may be 1 to ⁴ , 1 to ³ , 1 to 2 or 1.

X represents a polar group containing ⁴ -COOR groups. R ⁴ represents a hydrogen atom or a monovalent hydrocarbon group. The monovalent hydrocarbon group represented by R ⁴ may be, for example, a linear or branched alkyl group. The number of carbon atoms of the monovalent hydrocarbon group represented by R ⁴ may be 1～12,1～8 or 1-2.

The polar group containing ⁴ -COOR groups represented by X is preferably a polar group containing a -COOH group. The polar group containing ⁴ −COOR groups is represented by, for example, −COOH group, −COOR group, −CH (COOH) CH ₂ COOH group, −CH (COOR) CH ₂ COOH group, and the following formula (X-1). It may be a group represented by the following formula (X-2). R in the -COOR group represents a monovalent hydrocarbon group. The hydrocarbon group may be, for example, a linear or branched alkyl group. The hydrocarbon group may have 1 to 12, 1 to 8 or 1 to 2 carbon atoms.

The content of the compound represented by the formula (A) may be 0.01% by mass or more, 0.02% by mass or more, or 0.05% by mass or more based on the total amount of refrigerating machine oil, and is 1.0% by mass. Hereinafter, it may be 0.5% by mass or less or 0.2% by mass or less. The content of the compound represented by the formula (A) is 0.01 to 1.0% by mass, 0.01 to 0.5% by mass, 0.01 to 0.2% by mass, based on the total amount of refrigerating machine oil. 0.02 to 1.0% by mass, 0.02 to 0.5% by mass, 0.02 to 0.2% by mass, 0.05 to 1.0% by mass, 0.05 to 0.5% by mass or It may be 0.05 to 0.2% by mass.

The refrigerating machine oil may further contain additives other than the compound represented by the formula (A). Additives other than the compound represented by the formula (A) include, for example, an acid trapping agent, an antioxidant, an extreme pressure agent, an oily agent, a defoaming agent, a metal inactivating agent, an abrasion resistant agent, and an viscosity index improving agent. Examples include agents, pour point depressants, and detergent dispersants. The content of these additives may be 10% by mass or less or 5% by mass or less based on the total amount of refrigerating machine oil.

The phosphorus content in the refrigerating machine oil may be 20 mass ppm or more, 50 mass ppm or more or 80 mass ppm or more, and 1000 mass ppm or less, 500 mass ppm or less or 200 mass ppm or less based on the total amount of refrigerating machine oil. It may be there. The phosphorus content in the refrigerating machine oil is 20 to 1000 mass ppm, 20 to 500 mass ppm, 20 to 200 mass ppm, 50 to 1000 mass ppm, 50 to 500 mass ppm, 50 to 200 mass based on the total amount of the refrigerating machine oil. It may be ppm, 80-1000 mass ppm, 80-500 mass ppm or 80-200 mass ppm. The "phosphorus content" means the content measured by the ICP elemental analysis method.

The kinematic viscosity of the refrigerating machine oil at 40 ° C. is preferably 3 mm ² / s or more, more preferably 4 mm ² / s or more, and further preferably 5 mm ² / s or more. The kinematic viscosity of the refrigerating machine oil at 40 ° C. is preferably 500 mm ² / s or less, more preferably 400 mm ² / s or less, and further preferably 300 mm ² / s or less.

The kinematic viscosity of the refrigerating machine oil at 100 ° C. is preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. The kinematic viscosity of the refrigerating machine oil at 100 ° C. is preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less.

The pour point of the refrigerating machine oil is preferably −10 ° C. or lower, more preferably −20 ° C. or lower. The pour point in the present invention means a pour point measured according to JIS K2269-1987.

The volume resistivity of the refrigerating machine oil is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and further preferably 1.0 × 10 ¹¹ Ω · m or more. .. The volume resistivity in the present invention means the volume resistivity at 25 ° C. measured according to JIS C2101: 1999.

The water content of the refrigerating machine oil is preferably 200 ppm or less, more preferably 100 ppm or less, still more preferably 50 ppm or less, based on the total amount of refrigerating machine oil.

The acid value of the refrigerating machine oil is preferably 1.0 mgKOH / g or less, more preferably 0.1 mgKOH / g or less. The acid value in the present invention means an acid value measured according to JIS K2501: 2003.

The ash content of the refrigerating machine oil is preferably 100 ppm or less, more preferably 50 ppm or less. The ash content in the present invention means the ash content measured according to JIS K2272: 1998.

The refrigerating machine oil according to the present embodiment usually exists in a refrigerating machine in the state of a working fluid composition for a refrigerating machine mixed with a refrigerant. That is, the working fluid composition for a refrigerator according to the present embodiment contains the above-mentioned refrigerating machine oil and a refrigerant. The content of the refrigerating machine oil in the working fluid composition for a refrigerating machine 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.

Examples of the refrigerant include saturated fluorinated hydrocarbon refrigerants, unsaturated fluorinated hydrocarbon refrigerants, hydrocarbon refrigerants, fluorine-containing ether-based refrigerants such as perfluoroethers, bis (trifluoromethyl) sulfide refrigerants, and methane trifluoride. Examples thereof include a refrigerant and a natural refrigerant such as ammonia and carbon dioxide.

The saturated fluorinated hydrocarbon refrigerant is preferably a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms. Specific examples of the saturated fluorinated hydrocarbon refrigerant include difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,2,2-tetrafluoroethane (R134), 1, 1,1,2-Tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1-difluoroethane (R152a), fluoroethane (R161), 1,1,1,2,3 , 3,3-Heptafluoropropane (R227ea), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1,3,3,3-hexafluoropropane (R236fa), Included are 1,1,1,3,3-pentafluoropropane (R245fa), and 1,1,1,3,3-pentafluorobutane (R365mfc), or mixtures of two or more thereof.

The saturated fluorinated hydrocarbon refrigerant is appropriately selected from the above according to the application and required performance. The saturated fluorinated hydrocarbon refrigerant is, for example, R32 alone; R23 alone; R134a alone; R125 alone; a mixture of R134a / R32 = 60 to 80% by mass / 40 to 20% by mass; R32 / R125 = 40 to 70% by mass / 60. ~ 30% by mass mixture; R125 / R143a = 40-60% by mass / 60-40% by mass mixture; R134a / R32 / R125 = 60% by mass / 30% by mass / 10% by mass mixture; R134a / R32 / R125 = 40 to 70% by mass / 15 to 35% by mass / 5 to 40% by mass; R125 / R134a / R143a = 35 to 55% by mass / 1 to 15% by mass / 40 to 60% by mass. More specifically, the saturated fluorinated hydrocarbon refrigerant is a mixture of R134a / R32 = 70/30% by mass; a mixture of R32 / R125 = 60/40% by mass; a mixture of R32 / R125 = 50/50% by mass ( R410A); R32 / R125 = 45/55% by mass mixture (R410B); R125 / R143a = 50/50% by mass mixture (R507C); R32 / R125 / R134a = 30/10/60% by mass mixture; R32 / R125 / R134a = 23/25/52 mass% mixture (R407C); R32 / R125 / R134a = 25/15/60 mass% mixture (R407E); R125 / R134a / R143a = 44/4/52 mass% (R404A) and the like.

The unsaturated fluorinated hydrocarbon (HFO) refrigerant is preferably an unsaturated fluorinated hydrocarbon having 2 to 3 carbon atoms, more preferably a fluoropropene, and even more preferably a fluoropropene having 3 to 5 fluorine numbers. The unsaturated fluorinated hydrocarbon refrigerant is preferably 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 2, One of 3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and 3,3,3-trifluoropropene (HFO-1243zf). It is one kind or a mixture of two or more kinds. From the viewpoint of the physical properties of the refrigerant, the unsaturated fluorocarbon refrigerant is preferably one or more selected from HFO-1225ye, HFO-1234ze and HFO-1234yf. The unsaturated fluorinated hydrocarbon refrigerant may be fluoroethylene, preferably 1,1,2,3-trifluoroethylene.

The hydrocarbon refrigerant is preferably a hydrocarbon having 1 to 5 carbon atoms, and more preferably a hydrocarbon having 2 to 4 carbon atoms. Specific examples of the hydrocarbon include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane, normal pentane, or two or more of them. Can be mentioned. Among these, the hydrocarbon refrigerant is preferably a gaseous hydrocarbon refrigerant at 25 ° C. and 1 atm, and more preferably propane, normal butane, isobutane, 2-methylbutane or a mixture thereof.

The refrigerator oil and the working fluid composition for a refrigerator according to the present embodiment are an air conditioner having a reciprocating or rotary sealed compressor, a refrigerator, an open or closed car air conditioner, a dehumidifier, a water heater, and a freezer. , Refrigerator / refrigerator warehouse, vending machine, showcase, refrigerator such as chemical plant, refrigerator with centrifugal compressor, etc.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to Examples.

In Examples and Comparative Examples, refrigerating machine oil having the composition shown in Table 1 (mass% based on the total amount of refrigerating machine oil) was prepared using the base oils and additives shown below.

ａ１：トリクレジルホスフェート (Base oil)
Base oil: Polyol ester of pentaerythritol and mixed fatty acid (mass ratio: 35/65) of 2-methylpropanoic acid / 3,5,5-trimethylcaproic acid (kinematic viscosity at 40 ° C.: 67. 2 mm ² / s, viscosity index: 84)
(Additive)
A1: Compound represented by the following formula (A-1)

a1: Tricresyl phosphate

The seizure resistance of each of the refrigerating machine oils of Examples and Comparative Examples was evaluated by the procedure shown below. The results are shown in Table 1.

(Seizure resistance)
A FALEX Pin / Vee-Block test was performed. Under the conditions of rotation speed: 290 rpm, temperature: 52 ± 8 ° C., oil amount: 120 mL, and air atmosphere, a break-in operation was performed for 5 minutes under a load of 300 lbf, and then the load was applied and seizure occurred. The load at that time was defined as the seizure load. An ASTM standard piece was used as the test piece.

Claims (2)

A refrigerating machine oil containing a lubricating oil base oil and a compound represented by the following formula (A).

[In the formula (A), R ¹ and R ² each independently represent a monovalent hydrocarbon group having 2 to 18 carbon atoms , R ³ represents a divalent hydrocarbon group having 1 to 4 carbon atoms , and X. Represents a -COOH group or a -COOR group . R represents a monovalent hydrocarbon group. ] A working fluid composition for a refrigerator containing the refrigerating machine oil according to claim 1 and a refrigerant.