Refrigerating machine oil and method for producing same

Abstract

The present invention provides a refrigeration oil containing a lubricating base oil and at least one selected from the group consisting of an amine salt of a phosphonic acid and an amine salt of a phosphonic acid monoester, and a method for producing the same.

Description

[Technical Field]

[0001] The present invention relates to a refrigerating machine oil and a method for producing the same. [Background technology]

[0002] Refrigeration machines such as refrigerators, car air conditioners, room air conditioners, and vending machines are equipped with compressors for circulating refrigerants through a refrigeration cycle. The compressors are filled with refrigeration oil to lubricate sliding members. Refrigeration oils generally contain base oils and additives that are blended according to desired properties.

[0003] For example, known additives for improving the wear resistance of refrigerating machine oils include anti-wear agents such as phosphorus-based anti-wear agents and sulfur-based anti-wear agents. Patent Document 1 discloses a refrigerating machine oil containing a phosphorus-based additive consisting of a phosphate triester and / or a phosphite triester. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-266423 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the investigations of the present inventors, it has been found that in the case of refrigerating machine oils using the above-mentioned phosphorus-based additives, even if they initially exhibit excellent wear resistance, the wear resistance may deteriorate after long-term storage.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a refrigeration oil capable of maintaining excellent wear resistance for a long period of time, and a method for producing the same. [Means for solving the problem]

[0007] In order to solve the above problems, the present inventors first investigated the effect of adding a phosphonic acid diester to a refrigerating machine oil on improving wear resistance. As a result, they found that a portion of the phosphonic acid diester is converted to phosphonic acid or a phosphonic acid monoester, and that the resulting phosphonic acid and phosphonic acid monoester contribute to improving wear resistance. However, they found that phosphonic acid and phosphonic acid monoester are chemically unstable compounds, and that even if these compounds are used as they are, wear resistance cannot be maintained for a long period of time.

[0008] Therefore, the present inventors have conducted further studies based on the above findings, and as a result have found that by having a phosphonic acid or a phosphonic acid monoester present in a refrigerating machine oil in the form of an amine salt, it is possible to impart excellent wear resistance to the refrigerating machine oil and to maintain the wear resistance for a long period of time, thereby completing the present invention.

[0009] That is, the present invention provides a refrigeration oil containing a lubricating base oil and at least one selected from the group consisting of an amine salt of a phosphonic acid and an amine salt of a phosphonic acid monoester.

[0010] The present invention also provides a method for producing a refrigerating machine oil, the method comprising the step of adding at least one selected from the group consisting of an amine salt of a phosphonic acid and an amine salt of a phosphonic acid monoester to a lubricating base oil or an oil composition containing the lubricating base oil.

[0011] The present invention further provides a method for producing a refrigerator oil, which comprises a step of adding a phosphonic acid diester and an amine compound to a lubricant base oil or an oil composition containing the lubricant base oil. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a refrigerating machine oil capable of maintaining excellent anti-wear properties for a long period of time, and a method for producing such a refrigerating machine oil. [Brief explanation of the drawings]

[0013] [Figure 1] 31P-NMR chart showing phosphonic acid and phosphonic acid monoester before conversion to amine salt. [Figure 2] 3 is a 31P-NMR chart showing that an amine salt of a phosphonic acid and a phosphonic acid monoester is produced by adding an amine compound. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail.

[0015] The refrigerating machine oil according to this embodiment contains a lubricating base oil and at least one selected from the group consisting of an amine salt of a phosphonic acid and an amine salt of a phosphonic acid monoester (hereinafter, sometimes referred to as the "amine salt according to this embodiment").

[0016] Such a refrigeration oil can maintain its wear resistance for a long period of time. The inventors of the present invention speculate as follows about the reason why such an effect is achieved. That is, first, since the phosphonic acid or phosphonic acid monoester exists in the form of an amine salt during storage of the refrigerating machine oil, it is believed that these components can be stably maintained in the refrigerating machine oil. Then, during use of the refrigerating machine oil, a part or all of the amine compound is released from the amine salt to form the phosphonic acid or phosphonic acid monoester, which is believed to effectively exert the effect of improving the wear resistance of these components.

[0017] Phosphonic acid is a compound represented by the following formula (1): The amine salt of phosphonic acid may be an amine salt formed by at least one hydroxyl group in the compound represented by the following formula (1) and an amine compound. Phosphonic acid may exist as its tautomer, trihydroxy phosphorous acid.

[0018] [ka]

[0019] The phosphonic acid monoester may be, for example, at least one compound represented by the following formula (2): The amine salt of the phosphonic acid monoester may be an amine salt formed by at least one hydroxyl group in the compound represented by the following formula (2) and an amine compound: The phosphonic acid monoester is also called a monohydrocarbyl hydrogen phosphite, and may exist as a dihydroxy-type phosphorous acid monoester, which is its tautomer.

[0020] [ka] [In formula (2), R represents a hydrocarbon group (hydrocarbyl group)]

[0021] The hydrocarbon group represented by R is preferably a hydrocarbon group having 1 to 20 carbon atoms. Examples of this hydrocarbon group include an alkyl group, an alkenyl group, an (alkyl)cycloalkyl group, and an (alkyl)aryl group. Among these, R is preferably an alkyl group or alkenyl group having 2 to 18 carbon atoms, or an (alkyl)aryl group having 6 to 10 carbon atoms, and more preferably an alkyl group or alkenyl group having 2 to 18 carbon atoms. Furthermore, the alkyl group and alkenyl group may be linear or branched.

[0022] Examples of such phosphonic acid monoesters include monooctyl hydrogen phosphite, mono(2-ethylhexyl) hydrogen phosphite, monolauryl hydrogen phosphite, monooleyl hydrogen phosphite, monoethyl hydrogen phosphite, monophenyl hydrogen phosphite, etc. Among these, from the viewpoint of abrasion resistance, at least one selected from the group consisting of monooctyl hydrogen phosphite, mono(2-ethylhexyl) hydrogen phosphite, monolauryl hydrogen phosphite, and monooleyl hydrogen phosphite is preferred.

[0023] The amine compound is not particularly limited as long as it is a compound having an amino group in the molecule, and examples thereof include alkyl or alkenylamines having one or two alkyl or alkenyl groups having 1 to 20 carbon atoms, alkanolamines having an alkanol group such as ethanol or propanol, or derivatives thereof, and polyamines having an alkylene group having 2 to 4 carbon atoms, or derivatives thereof. Examples of alkyl or alkenylamines include di(2-ethylhexyl)amine, oleylamine, and 2-ethylhexylamine, with di(2-ethylhexyl)amine being particularly preferred. Examples of alkanolamines include mono-, di-, or tri-diethanolamine, mono-, di-, or tri-(iso)propanolamine, and mono-, di-, or tri-(iso)butanolamine. Among these, the mono- or dialkanolamine may be, for example, one having an alkyl or alkenyl group having 1 to 20 carbon atoms, such as 2-ethylhexyldiethanolamine, dodecyldi(iso)propanolamine, lauryldiethanolamine, or oleyldiethanolamine. Furthermore, examples of polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenehexamine, and derivatives thereof. Among these, the polyamine derivative may be a reaction product of the polyamine with a fatty acid having 1 to 40 carbon atoms, such as oleic acid or stearic acid, or a dibasic acid, such as oxalic acid, maleic acid, succinic acid, or alkyl or alkenyl succinic acid.

[0024] The content of the amine salt in this embodiment is preferably 0.0001 to 1 mass %, more preferably 0.001 to 0.5 mass %, and even more preferably 0.001 to 0.1 mass %, based on the total amount of the refrigerating machine oil.

[0025] The method for producing a refrigerating machine oil according to the present embodiment includes, for example, adding at least one selected from the group consisting of an amine salt of a phosphonic acid and an amine salt of a phosphonic acid monoester to a lubricating base oil or an oil composition containing the lubricating base oil. In this production method, the amine salt according to the present embodiment may be an amine salt obtained by reacting a phosphonic acid or a phosphonic acid monoester with an amine compound, a phosphonic acid diester partially converted to a phosphonic acid or a phosphonic acid monoester, or an amine salt obtained by reacting a phosphonic acid or a phosphonic acid monoester present as an impurity in a phosphonic acid diester with an amine compound. When partially converting a phosphonic acid diester to a phosphonic acid or a phosphonic acid monoester, a solvent such as kerosene, mineral oil, n-hexane, toluene, light solvents, benzene, xylene, alcohols, ethers, or esters may be used. Furthermore, in this case, the amine salt according to the present embodiment may be added alone or together with a phosphonic acid diester.

[0026] Another method for producing a refrigerating machine oil according to the present embodiment includes a step of adding a phosphonic acid diester and an amine compound to a lubricating base oil or an oil composition containing the lubricating base oil. In this production method, the amine salt according to the present embodiment can be produced by reacting a phosphonic acid or phosphonic acid monoester, which is a partial conversion of the phosphonic acid diester, or a phosphonic acid or phosphonic acid monoester, which is present as an impurity in the phosphonic acid diester due to the degree of purification, with the amine compound in the lubricating base oil or the oil composition containing the lubricating base oil.

[0027] In this specification, an oil composition containing a lubricating base oil refers to a composition containing the lubricating base oil and other additives described below. In this case, the content of the lubricating base oil in the oil composition may be 50% by mass or more, 70% by mass or more, or 90% by mass or more, based on the total amount of the oil composition.

[0028] The phosphonic acid diester may be, for example, a compound represented by the following formula (3): Phosphonic acid diester is also called dihydrocarbyl hydrogen phosphite, and may exist as its tautomer, a monohydroxy type phosphite diester.

[0029] [ka] [In formula (3), R′ and R″ may be the same or different and each represents a hydrocarbon group (hydrocarbyl group)]

[0030] The hydrocarbon group represented by R' and R'' is preferably a hydrocarbon group having 1 to 20 carbon atoms. Examples of this hydrocarbon group include an alkyl group, an alkenyl group, an (alkyl)cycloalkyl group, a phenyl group, and an (alkyl)aryl group such as a cresyl group. Among these, R is preferably an alkyl group or alkenyl group having 2 to 18 carbon atoms or an (alkyl)aryl group having 6 to 10 carbon atoms, more preferably an alkyl group or alkenyl group having 2 to 18 carbon atoms. The alkyl group or alkenyl group may be linear or branched.

[0031] Examples of such phosphonic acid diesters include dioctyl hydrogen phosphite, di(2-ethylhexyl) hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diethyl hydrogen phosphite, diphenyl hydrogen phosphite, etc. Among these, from the viewpoint of abrasion resistance, at least one selected from the group consisting of dioctyl hydrogen phosphite, di(2-ethylhexyl) hydrogen phosphite, dilauryl hydrogen phosphite, and dioleyl hydrogen phosphite is preferred.

[0032] The mixing ratio of the phosphonic acid diester and the amine compound may be appropriately set, for example, taking into consideration the balance between the acid value of the phosphonic acid diester and the base value of the amine compound. The mixing ratio of the phosphonic acid diester and the amine compound (phosphonic acid diester / amine compound) may be, for example, 1 / 5 to 10 / 1, 2 / 3 to 5 / 1, or 1 / 1 to 4 / 1, in terms of molar ratio. Furthermore, in the case of a mixture containing phosphonic acid diesters, some of which have been converted to phosphonic acid or phosphonic acid monoesters by hydrolysis or the like, the content of the amine compound is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, of the total amount of the mixture and the amine compound.

[0033] In the refrigeration oil and its manufacturing method according to the present embodiment, hydrocarbon oils, oxygen-containing oils, etc. can be used as the lubricating base oil. Examples of hydrocarbon oils include mineral hydrocarbon oils and synthetic hydrocarbon oils. Examples of oxygen-containing oils include esters, ethers, carbonates, ketones, silicones, and polysiloxanes.

[0034] Mineral hydrocarbon oils can be obtained by refining lubricating oil fractions obtained by atmospheric distillation and vacuum distillation of paraffinic, naphthenic, or other crude oils using methods such as solvent deasphalting, solvent refining, hydrorefining, hydrocracking, solvent dewaxing, hydrodewaxing, clay treatment, sulfuric acid washing, etc. These refining methods may be used alone or in combination of two or more.

[0035] Examples of synthetic hydrocarbon oils include alkylbenzene, alkylnaphthalene, polyα-olefin (PAO), polybutene, and ethylene-α-olefin copolymer.

[0036] As the alkylbenzene, the following alkylbenzene (A) and / or alkylbenzene (B) can be used. Alkylbenzene (A): an alkylbenzene having 1 to 4 alkyl groups each having 1 to 19 carbon atoms, and the total number of carbon atoms in the alkyl groups being 9 to 19 (preferably an alkylbenzene having 1 to 4 alkyl groups each having 1 to 15 carbon atoms, and the total number of carbon atoms in the alkyl groups being 9 to 15). Alkylbenzene (B): an alkylbenzene having 1 to 4 alkyl groups each having 1 to 40 carbon atoms, and the total number of carbon atoms in the alkyl groups being 20 to 40 (preferably, an alkylbenzene having 1 to 4 alkyl groups each having 1 to 30 carbon atoms, and the total number of carbon atoms in the alkyl groups being 20 to 30).

[0037] Specific examples of the alkyl group having 1 to 19 carbon atoms contained in the alkylbenzene (A) include methyl, ethyl, propyl (including all isomers, the same applies hereinafter), butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and hexocyl. These alkyl groups may be linear or branched, with branched groups being preferred from the standpoints of stability, viscosity characteristics, and the like. In particular, from the standpoint of availability, branched alkyl groups derived from olefin oligomers such as propylene, butene, and isobutylene are more preferred.

[0038] The number of alkyl groups in the alkylbenzene (A) is 1 to 4, and from the viewpoints of stability and availability, it is preferably 1 or 2 (that is, monoalkylbenzene, dialkylbenzene, or a mixture thereof).

[0039] The alkylbenzene (A) may contain only alkylbenzene of a single structure, or may contain a mixture of alkylbenzenes having different structures, as long as the alkylbenzene satisfies the condition that it has 1 to 4 alkyl groups each having 1 to 19 carbon atoms and the total number of carbon atoms in the alkyl groups is 9 to 19.

[0040] Specific examples of the alkyl group having 1 to 40 carbon atoms contained in the alkylbenzene (B) include a methyl group, an ethyl group, a propyl group (including all isomers, the same applies hereinafter), a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group, and a henicosyl group. Examples of the alkyl group include a silyl group, a docosyl group, a tricosyl group, a tetracosyl group, a pentacosyl group, a hexacosyl group, a heptatriacontyl group, an octacosyl group, a nonacosyl group, a triacontyl group, a hentriacontyl group, a dotriacontyl group, a tritriacontyl group, a tetratriacontyl group, a pentatriacontyl group, a hexatriacontyl group, a heptatriacontyl group, an octatriacontyl group, a nonatriacontyl group, and a tetracontyl group. These alkyl groups may be linear or branched, and branched groups are preferred in terms of stability, viscosity characteristics, etc. In particular, branched alkyl groups derived from olefin oligomers such as propylene, butene, and isobutylene are more preferred in terms of availability.

[0041] The number of alkyl groups in the alkylbenzene (B) is 1 to 4, and from the viewpoints of stability and availability, it is preferably 1 or 2 (that is, monoalkylbenzene, dialkylbenzene, or a mixture thereof).

[0042] The alkylbenzene (B) may contain only alkylbenzene of a single structure, or may contain a mixture of alkylbenzenes having different structures, as long as the alkylbenzene satisfies the condition that it has 1 to 4 alkyl groups each having 1 to 40 carbon atoms and the total number of carbon atoms in the alkyl groups is 20 to 40.

[0043] Polyα-olefins (PAOs) are compounds obtained by polymerizing linear olefin molecules having 6 to 18 carbon atoms and a double bond at only one end, followed by hydrogenation. Polyα-olefins may be isoparaffins having a molecular weight distribution centered on trimers or tetramers of α-decene having 10 carbon atoms or α-dodecene having 12 carbon atoms.

[0044] Examples of the ester include aromatic esters, dibasic acid esters, polyol esters, complex esters, carbonate esters, and mixtures thereof. The ester is preferably a polyol ester or a complex ester.

[0045] Polyol esters are esters of polyhydric alcohols and fatty acids. Saturated fatty acids are preferably used as the fatty acids. The number of carbon atoms in the fatty acids is preferably 4 to 20, more preferably 4 to 18, and even more preferably 4 to 9. Polyol esters may be partial esters in which some of the hydroxyl groups of the polyhydric alcohol remain unesterified, or complete esters in which all hydroxyl groups are esterified, or mixtures of partial and complete esters. The hydroxyl value of the polyol ester is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and even more preferably 3 mgKOH / g or less.

[0046] Of the fatty acids constituting the polyol ester, the proportion of fatty acids having 4 to 20 carbon atoms is preferably 20 to 100 mol %, more preferably 50 to 100 mol %, even more preferably 70 to 100 mol %, and particularly preferably 90 to 100 mol %.

[0047] Specific examples of fatty acids having 4 to 20 carbon atoms include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, and icosanoic acid. These fatty acids may be linear or branched. More specifically, fatty acids having branches at the α- and / or β-positions are preferred, and 2-methylpropanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and 2-ethylhexadecanoic acid are more preferred, with 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid being even more preferred.

[0048] The fatty acid may contain a fatty acid other than a fatty acid having 4 to 20 carbon atoms. The fatty acid other than a fatty acid having 4 to 20 carbon atoms may be, for example, a fatty acid having 21 to 24 carbon atoms. Specific examples include heneicosanoic acid, docosanoic acid, tricosanoic acid, and tetracosanoic acid. These fatty acids may be linear or branched.

[0049] As the polyhydric alcohol constituting the polyol ester, a polyhydric alcohol having 2 to 6 hydroxyl groups is preferably used. The number of carbon atoms in the polyhydric alcohol is preferably 4 to 12, more preferably 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 preferred because of its particularly excellent compatibility with refrigerants and hydrolysis stability.

[0050] The complex ester is an ester synthesized, for example, by the following method (a) or (b). (a) A method in which the molar ratio of polyhydric alcohol to polybasic acid is adjusted to synthesize an ester intermediate in which some of the carboxyl groups of the polybasic acid remain unesterified, and then the remaining carboxyl groups are esterified with a monohydric alcohol. (b) A method in which the molar ratio of polyhydric alcohol to polybasic acid is adjusted to synthesize an ester intermediate in which some of the hydroxyl groups of the polyhydric alcohol remain unesterified, and then the remaining hydroxyl groups are esterified with a monobasic fatty acid.

[0051] The complex ester obtained by the above method (a) does not (is unlikely to) produce a relatively strong acid even when hydrolyzed during use as a refrigerating machine oil, and therefore tends to be more stable than the complex ester obtained by the above method (b). As the complex ester in this embodiment, the complex ester obtained by the above method (a), which is more stable, is preferred.

[0052] The complex ester is preferably an ester synthesized from 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 at least one selected from monohydric alcohols having 4 to 18 carbon atoms and monovalent fatty acids having 2 to 12 carbon atoms.

[0053] Examples of polyhydric alcohols having 2 to 4 hydroxyl groups include neopentyl glycol, trimethylolpropane, pentaerythritol, etc. As the polyhydric alcohols having 2 to 4 hydroxyl groups, neopentyl glycol and trimethylolpropane are preferred from the viewpoint of ensuring a suitable viscosity and obtaining good low-temperature properties when the complex ester is used as a base oil, and neopentyl glycol is more preferred from the viewpoint of being able to adjust the viscosity over a wide range.

[0054] From the viewpoint of excellent lubricity, it is preferable that the polyhydric alcohol constituting the complex ester further contains, in addition to a polyhydric alcohol having 2 to 4 hydroxyl groups, a dihydric alcohol having 2 to 10 carbon atoms other than neopentyl glycol. 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, 3-methyl-1,5-pentanediol, and 2,2-diethyl-1,3-pentanediol. Of these, butanediol is preferred from the viewpoint of excellent lubricating base oil properties. Examples of butanediols include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol. Of these, 1,3-butanediol and 1,4-butanediol are more preferred from the viewpoint of obtaining good properties. The amount of the dihydric 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, and even more preferably 0.4 mol or less, per mol of the polyhydric alcohol having 2 to 4 hydroxyl groups.

[0055] Examples of polybasic acids having 6 to 12 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and trimellitic acid. Among these, adipic acid and sebacic acid are preferred, and adipic acid is more preferred, from the viewpoints 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, and even more preferably 0.6 mol to 2.5 mol, per mol of the polyhydric alcohol having 2 to 4 hydroxyl groups.

[0056] Examples of monohydric alcohols having 4 to 18 carbon atoms include aliphatic alcohols such as butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, dodecanol, and oleyl alcohol. These monohydric alcohols may be linear or branched. From the viewpoint of a balance of properties, 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. Among these, 2-ethylhexanol and 3,5,5-trimethylhexanol are more preferred from the viewpoint of improving the low-temperature properties of the synthesized complex ester.

[0057] Examples of monovalent fatty acids having 2 to 12 carbon atoms include ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and dodecanoic acid. These monovalent fatty acids may be linear or branched. The monovalent fatty acids having 2 to 12 carbon atoms are preferably monovalent fatty acids having 8 to 10 carbon atoms, and among these, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are more preferred from the viewpoint of low-temperature properties.

[0058] Examples of the ether include polyvinyl ether, polyalkylene glycol, polyphenyl ether, perfluoroether, and mixtures thereof. As the ether, polyvinyl ether or polyalkylene glycol is preferred, and polyvinyl ether is more preferred.

[0059] The polyvinyl ether has a structural unit represented by the following formula (4).

[0060] [ka] [In formula (4), R 1 , R 2 and R 3 may be the same or different and each represents a hydrogen atom or a hydrocarbon group; R 4 represents a divalent hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group, and R5 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.]

[0061] R 1 , R 2 and R 3 The number of carbon atoms in the hydrocarbon group represented by R is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, and is preferably 8 or less, more preferably 7 or less, and even more preferably 6 or less. 1 , R 2 and R 3 Preferably, at least one of R is a hydrogen atom, 1 , R 2 and R 3 It is more preferable that all of are hydrogen atoms.

[0062] R 4 The number of carbon atoms in the divalent hydrocarbon group and ether-bonded oxygen-containing hydrocarbon group represented by R is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, and is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. 4 The divalent ether-bonded oxygen-containing hydrocarbon group represented by the formula (I) may be, for example, a hydrocarbon group having oxygen atoms in the side chain that form an ether bond.

[0063] R 5 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. Among these, an alkyl group is preferred, and an alkyl group having 1 to 5 carbon atoms is more preferred.

[0064] m is preferably 0 or more, more preferably 1 or more, and even more preferably 2 or more, and is preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less. The average value of m in all structural units constituting the polyvinyl ether is preferably 0 to 10.

[0065] The polyvinyl ether may be a homopolymer composed of one structural unit selected from those represented by formula (4), a copolymer composed of two or more structural units selected from those represented by formula (4), or a copolymer composed of the structural unit represented by formula (4) and other structural units. When the polyvinyl ether is a copolymer, the lubricity, insulating properties, moisture absorption, etc. of the refrigerating machine oil can be further improved while satisfying compatibility with the refrigerant. In this case, by appropriately selecting the type of raw material monomer, the type of initiator, the ratio of structural units in the copolymer, etc., it is possible to achieve the desired properties of the refrigerating machine oil. The copolymer may be either a block copolymer or a random copolymer.

[0066] When the polyvinyl ether is a copolymer, the copolymer is represented by the above formula (4) and R 5 is a structural unit (4-1) represented by the above formula (4) and R 5 and a structural unit (4-2) in which R is an alkyl group having 3 to 20 carbon atoms, preferably 3 to 10, and more preferably 3 to 8 carbon atoms. 5 An ethyl group is particularly preferred as R 5 An isobutyl group is particularly preferred. When the polyvinyl ether is a copolymer having the structural units (4-1) and (4-2) described above, the molar ratio of the structural units (4-1) to (4-2) is preferably 5:95 to 95:5, 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, compatibility with refrigerants can be further improved, and hygroscopicity tends to be reduced.

[0067] The polyvinyl ether may be composed only of the structural unit represented by the above formula (4), or may be a copolymer further having a structural unit represented by the following formula (5). In this case, the copolymer may be either a block copolymer or a random copolymer.

[0068] [ka] [In formula (5), R 6 ~R 9 may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.]

[0069] Polyvinyl ether can be produced by copolymerizing a vinyl ether monomer corresponding to the structural unit represented by formula (4) or a vinyl ether monomer corresponding to the structural unit represented by formula (4) with a hydrocarbon monomer having an olefinic double bond corresponding to the structural unit represented by formula (5). As the vinyl ether monomer corresponding to the structural unit represented by formula (4), a monomer represented by the following formula (6) is suitable.

[0070] [ka] [In formula (6), R 1 , R 2 , R 3 , R 4 , R 5 and m are R in formula (4), respectively. 1 , R 2 , R 3 , R 4 , R 5 and m have the same definition.]

[0071] The polyvinyl ether preferably has the following terminal structure (A) or (B).

[0072] (A) A structure in which one end is represented by formula (7) or (8) and the other end is represented by formula (9) or (10).

[0073] [ka] [In formula (7), R 11 , R 21 and R 31may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms; R 41 represents a divalent hydrocarbon group having 1 to 10 carbon atoms or a divalent ether-bonded oxygen-containing hydrocarbon group, and R 51 represents a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in formula (4). When m is 2 or more, multiple R 41 may be the same or different.]

[0074] [ka] [In formula (8), 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.

[0075] [ka] [In formula (9), 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; R 42 represents a divalent hydrocarbon group having 1 to 10 carbon atoms or a divalent ether-bonded oxygen-containing hydrocarbon group, and R 52 represents a hydrocarbon group having 1 to 20 carbon atoms, and m has the same definition as m in formula (4). When m is 2 or more, multiple R 41 may be the same or different.]

[0076] [ka] [In formula (10), 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.

[0077] (B) A structure in which one end is represented by the above formula (7) or (8) and the other end is represented by the following formula (11).

[0078] [ka] [In formula (11), 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.]

[0079] Among these polyvinyl ethers, the following polyvinyl ethers (a), (b), (c), (d) and (e) are particularly suitable as base oils. (a) One end has a structure represented by formula (7) or (8), and the other end has a structure represented by formula (9) or (10), and R 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, R 5 is a hydrocarbon group having 1 to 20 carbon atoms. (b) A compound having only a structural unit represented by formula (4), one end of which is represented by formula (7) and the other end of which is represented by formula (9), wherein R 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, R 5 is a hydrocarbon group having 1 to 20 carbon atoms. (c) One end has a structure represented by formula (7) or (8), and the other end has a structure represented by formula (11), and R 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, R 5 is a hydrocarbon group having 1 to 20 carbon atoms. (d) A compound having only a structural unit represented by formula (4), one end of which is represented by formula (8) and the other end of which is represented by formula (11), and R 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, R 5 is a hydrocarbon group having 1 to 20 carbon atoms. (e) Any of the above (a), (b), (c), and (d), wherein R in formula (4) 5 is a hydrocarbon group having 1 to 3 carbon atoms and 5 and a structural unit which is a hydrocarbon group having 3 to 20 carbon atoms.

[0080] 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. The peroxide value of the polyvinyl ether is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, and even more preferably 1.0 meq / kg or less. 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. The hydroxyl value of the polyvinyl ether is preferably 10 mg KOH / g or less, more preferably 5 mg KOH / g or less, and even more preferably 3 mg KOH / g or less.

[0081] The unsaturation degree, peroxide value, and carbonyl value in the present invention are values ​​measured according to the Standard Method for Analysis of Fats, Oils, and Related Materials established by the Japan Oil Chemists' Society. Specifically, the unsaturation degree in the present invention refers to the value (meq / g) obtained by reacting a sample with Whiss's solution (ICl-acetic acid solution), leaving it in the dark, reducing excess ICl to iodine, titrating the iodine with sodium thiosulfate to calculate the iodine value, and converting this iodine value to a vinyl equivalent. The peroxide value in the present invention refers to the value (meq / kg) obtained by adding potassium iodide to a sample, titrating the resulting free iodine with sodium thiosulfate, and converting this free iodine to milliequivalents per 1 kg of sample. The carbonyl value in the present invention refers to a value (ppm by weight) obtained by reacting a sample with 2,4-dinitrophenylhydrazine to generate a color-developing quinoid ion, measuring the absorbance of the sample at 480 nm, and converting the value into the carbonyl amount based on a calibration curve previously obtained using cinnamaldehyde as a standard substance. The hydroxyl value in the present invention refers to a hydroxyl value measured in accordance with JIS K0070:1992.

[0082] Examples of polyalkylene glycols include polyethylene glycol, polypropylene glycol, polybutylene glycol, etc. Polyalkylene glycols have oxyethylene, oxypropylene, oxybutylene, etc. as structural units. Polyalkylene glycols having these structural units can be obtained by ring-opening polymerization using ethylene oxide, propylene oxide, and butylene oxide, which are monomers, as raw materials.

[0083] An example of the polyalkylene glycol is a compound represented by the following formula (12).

[0084] R α -[(OR β ) f -OR γ ] g (12) [In formula (12), 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 Rβ represents an alkylene group having 2 to 4 carbon atoms, and 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 an integer of 1 to 8.]

[0085] R α , R γ The alkyl group represented by the formula (I) may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, and more preferably 1 to 6. When the number of carbon atoms in the alkyl group is 10 or less, compatibility with the refrigerant tends to be maintained well.

[0086] R α , R γ The alkyl group portion of the acyl group represented by the formula (I) may be linear, branched, or cyclic. The number of carbon atoms in the acyl group is preferably 2 to 10, and more preferably 2 to 6. When the number of carbon atoms in the acyl group is 10 or less, compatibility with the refrigerant is maintained, and there is little risk of phase separation occurring.

[0087] R α , R γ When both groups represented by R are alkyl groups or acyl groups, α , R γ When g is 2 or more, multiple R α , R γ The groups represented by may be the same or different.

[0088] R α When the group represented by the formula: is a residue of a compound having 2 to 8 hydroxyl groups, the compound may be linear or cyclic.

[0089] R α , R γ From the viewpoint of excellent compatibility, at least one of R is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group. From the viewpoint of excellent thermal and chemical stability, α and R γand R are preferably alkyl groups, more preferably alkyl groups having 1 to 4 carbon atoms, and even more preferably methyl groups. From the viewpoints of ease of production and cost, α and R γ Preferably, one of R is an alkyl group (more preferably an alkyl group having 1 to 4 carbon atoms) and the other is a hydrogen atom, and more preferably, one is a methyl group and the other is a hydrogen atom. From the viewpoint of excellent lubricity and sludge solubility, α and R γ It is preferred that both of these are hydrogen atoms.

[0090] R β 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. β Examples of the oxyalkylene group of the repeating unit represented by the formula (OR) include an oxyethylene group, an oxypropylene group, and an oxybutylene group. β ) f The oxyalkylene group represented by the formula (I) may be composed of one kind of oxyalkylene group, or may be composed of two or more kinds of oxyalkylene groups.

[0091] Among the polyalkylene glycols represented by formula (12), copolymers containing oxyethylene groups (EO) and oxypropylene groups (PO) are preferred from the viewpoints of compatibility with refrigerants and excellent viscosity-temperature characteristics. In this case, from the viewpoints of excellent seizure load and viscosity-temperature characteristics, the ratio of oxyethylene groups to the total of oxyethylene groups and oxypropylene groups (EO / (PO+EO)) is preferably 0.1 to 0.8, and more preferably 0.3 to 0.6. From the viewpoints of excellent hygroscopicity and thermal / oxidative stability, EO / (PO+EO) is preferably 0 to 0.5, more preferably 0 to 0.2, and most preferably 0 (i.e., propylene oxide homopolymer).

[0092] f is an oxyalkylene group OR βrepresents the number of repetitions (degree of polymerization) of the formula (II) and is an integer of 1 to 80. g is an integer of 1 to 8. For example, R α When R is an alkyl or acyl group, g is 1. α When is a residue of a compound having 2 to 8 hydroxyl groups, g is the number of hydroxyl groups that the compound has.

[0093] In the polyalkylene glycol represented by formula (12), the average value of the product of f and g (f×g) is preferably 6 to 80, from the viewpoint of satisfying the required performance as a refrigerating machine oil in a well-balanced manner.

[0094] The number-average molecular weight of the polyalkylene glycol represented by formula (12) is preferably 500 or more, more preferably 600 or more, and preferably 3000 or less, more preferably 2000 or less, and even more preferably 1500 or less. f and g are preferably numbers such that the number-average molecular weight of the polyalkylene glycol satisfies the above conditions. If the number-average molecular weight of the polyalkylene glycol is 500 or more, the lubrication properties in the presence of a refrigerant are sufficient. If the number-average molecular weight is 3000 or less, the composition range in which the polyalkylene glycol exhibits compatibility with the refrigerant is wide even under low-temperature conditions, and poor lubrication of the refrigerant compressor and inhibition of heat exchange in the evaporator are less likely to occur.

[0095] The hydroxyl value of the polyalkylene glycol is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and most preferably 10 mgKOH / g or less.

[0096] Polyalkylene glycols can be synthesized by known methods ("Alkylene Oxide Polymers", Mitsuta Shibata et al., Kaibundo, published November 20, 1990). For example, alcohols (R α OH;R α is R in equation (12) αThe polyalkylene glycol represented by formula (12) is obtained by addition-polymerizing one or more predetermined alkylene oxides to a carboxylic acid ester (having the same definition as above) and then etherifying or esterifying the terminal hydroxyl groups. When two or more alkylene oxides are used in the above production process, the obtained polyalkylene glycol may be either a random copolymer or a block copolymer, but a block copolymer is preferred in terms of a tendency toward better oxidation stability and lubricity, and a random copolymer is preferred in terms of a tendency toward better low-temperature fluidity.

[0097] The degree of unsaturation of the polyalkylene glycol is preferably 0.04 meq / g or less, more preferably 0.03 meq / g or less, and most 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, and most 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, and most preferably 20 ppm by weight or less.

[0098] The kinematic viscosity of the lubricating base oil at 40°C is preferably 3mm 2 / s or more, preferably 4 mm 2 / s or more, more preferably 5 mm 2 The kinematic viscosity of the lubricating base oil at 40°C is preferably 1000 mm 2 / s or less, preferably 500 mm 2 / s or less, more preferably 400 mm 2 The kinematic viscosity of the lubricating base oil at 100°C is preferably 1 mm / s or less. 2 / s or more, preferably 2 mm 2 The kinematic viscosity of the lubricating base oil at 100°C is preferably 100mm / s or more. 2 / s or less, preferably 50 mm 2The kinematic viscosity in the present invention means a kinematic viscosity measured in accordance with JIS K2283:2000.

[0099] The content of the lubricating base oil may be 50 mass % or more, 60 mass % or more, 70 mass % or more, 80 mass % or more, or 90 mass % or more based on the total amount of the refrigerating machine oil.

[0100] The refrigerating machine oil may further contain other additives in addition to the amine salt of this embodiment. Examples of other additives include acid scavengers, antioxidants, extreme pressure agents, oiliness agents, antifoaming agents, metal deactivators, viscosity index improvers, pour point depressants, detergent-dispersants, and anti-wear agents other than phosphonic acid and phosphonic acid monoesters. The content of each of these additives may be preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the refrigerating machine oil. In the method for producing the refrigerating machine oil of this embodiment, these additives may be added to the lubricating base oil before or after blending the amine salt of this embodiment, or the phosphonic acid diester and amine compound of this embodiment, or may be blended simultaneously.

[0101] Examples of the acid scavenger include epoxy compounds (epoxy acid scavengers). Examples of the epoxy compounds include glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, oxirane compounds, alkyloxirane compounds, alicyclic epoxy compounds, epoxidized fatty acid monoesters, and epoxidized vegetable oils. These epoxy compounds can be used alone or in combination of two or more.

[0102] As the glycidyl ether type epoxy compound, for example, an aryl glycidyl ether type epoxy compound or an alkyl glycidyl ether type epoxy compound represented by the following formula (13) can be used.

[0103] [ka] [In formula (13), R a represents an aryl group or an alkyl group having 5 to 18 carbon atoms.]

[0104] Preferred glycidyl ether epoxy compounds represented by formula (13) include n-butylphenyl glycidyl ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, 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, and 2-ethylhexyl glycidyl ether.

[0105] R a When the alkyl group represented by R has 5 or more carbon atoms, the stability of the epoxy compound is ensured, and it is possible to prevent decomposition before reacting with moisture, fatty acids, or oxidative degradation products, and to prevent self-polymerization, in which epoxy compounds polymerize with each other, making it easier to achieve the desired function. a When the number of carbon atoms in the alkyl group represented by the formula (I) is 18 or less, the solubility in the refrigerant is maintained good, and it is possible to make it less likely that the refrigerant will precipitate in the refrigeration device and cause problems such as poor cooling.

[0106] As the glycidyl ether type epoxy compound, in addition to the epoxy compound represented by formula (13), neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, polyalkylene glycol diglycidyl ether, and the like can also be used.

[0107] As the glycidyl ester type epoxy compound, for example, one represented by the following formula (14) can be used.

[0108] [ka] [In formula (14), R b represents an aryl group, an alkyl group having 5 to 18 carbon atoms, or an alkenyl group.]

[0109] The glycidyl ester type epoxy compound represented by formula (14) is preferably glycidyl benzoate, glycidyl neodecanoate, glycidyl-2,2-dimethyloctanoate, glycidyl acrylate, or glycidyl methacrylate.

[0110] R b When the alkyl group represented by R has 5 or more carbon atoms, the stability of the epoxy compound is ensured, and it is possible to prevent decomposition before reacting with moisture, fatty acids, or oxidative degradation products, and to prevent self-polymerization, in which epoxy compounds polymerize with each other, making it easier to achieve the desired function. b When the number of carbon atoms in the alkyl or alkenyl group represented by the formula (I) is 18 or less, the solubility in the refrigerant is maintained good, and it is possible to make it difficult for the compound to precipitate in the refrigerator and cause problems such as poor cooling.

[0111] The alicyclic epoxy compound is a compound represented by the following general formula (15) having a partial structure in which the carbon atoms constituting the epoxy group directly constitute an alicyclic ring.

[0112] [ka]

[0113] Preferred examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)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, and 4-epoxyethyl-1,2-epoxycyclohexane.

[0114] Examples of the allyloxirane compound include 1,2-epoxystyrene and alkyl-1,2-epoxystyrene.

[0115] Examples of alkyloxirane compounds include 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, and 1,2-epoxyicosane.

[0116] Examples of epoxidized fatty acid monoesters include esters of epoxidized fatty acids having 12 to 20 carbon atoms with alcohols, phenols, or alkylphenols having 1 to 8 carbon atoms. Preferred epoxidized fatty acid monoesters include butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl, and butylphenyl esters of epoxy stearic acid.

[0117] Examples of epoxidized vegetable oils include epoxy compounds of vegetable oils such as soybean oil, linseed oil, and cottonseed oil.

[0118] The epoxy compound is preferably at least one selected from a glycidyl ester type epoxy compound and a glycidyl ether type epoxy compound, and from the viewpoint of excellent compatibility with resin materials (e.g., nylon) used in components inside the refrigerator, at least one selected from the glycidyl ester type epoxy compound is preferred.

[0119] The antioxidant may be, for example, a phenolic antioxidant such as di-tert.butyl-p-cresol.

[0120] Examples of the anti-wear agent include phosphorus-based anti-wear agents, such as alkyl hydrogen phosphites, phosphoric acid esters such as triphenyl phosphate (TPP) and tricresyl phosphate (TCP), and thiophosphates such as triphenyl phosphorothionate (TPPT).

[0121] The kinematic viscosity of the refrigerating oil at 40°C is preferably 3mm 2 / s or more, preferably 4 mm 2 / s or more, more preferably 5 mm 2 The kinematic viscosity of the refrigerating machine oil at 40°C is preferably 500 mm 2 / s or less, preferably 400 mm 2 / s or less, more preferably 300 mm 2 The kinematic viscosity of the refrigerating machine oil at 100°C is preferably 1 mm / s or less. 2 / s or more, preferably 2 mm 2 The kinematic viscosity of the refrigerating machine oil at 100°C is preferably 100mm / s or more. 2 / s or less, preferably 50 mm 2 / s or less.

[0122] The pour point of the refrigerating machine oil may be preferably not more than −10° C., more preferably not more than −20° C. The pour point in the present invention means the pour point measured in accordance with JIS K2269:1987.

[0123] The volume resistivity of the refrigerating machine oil is preferably 1.0 x 10 9 Ω·m or more, preferably 1.0×10 10 Ω·m or more, more preferably 1.0×10 11 The volume resistivity in the present invention means the volume resistivity at 25° C. measured in accordance with JIS C2101:1999.

[0124] The water content of the refrigerating machine oil may be preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less, based on the total amount of the refrigerating machine oil. The water content in the present invention means the water content measured in accordance with JIS K2275.

[0125] The acid value of the refrigerating machine oil may be preferably 1.0 mgKOH / g or less, more preferably 0.1 mgKOH / g or less. The acid value in the present invention means the acid value measured in accordance with JIS K2501:2003.

[0126] The ash content of the refrigerating machine oil may be preferably 100 ppm or less, more preferably 50 ppm or less. The ash content in the present invention means the ash content measured in accordance with JIS K2272:1998.

[0127] The refrigerating machine oil according to the present embodiment is usually present in a refrigerator as a working fluid composition for a refrigerating machine mixed with a refrigerant. That is, the refrigerating machine oil according to the present embodiment is used together with a refrigerant, and the working fluid composition for a refrigerating machine according to the present embodiment contains the refrigerating machine oil according to the present embodiment and the refrigerant.

[0128] Examples of such refrigerants include saturated fluorohydrocarbon refrigerants, unsaturated fluorohydrocarbon refrigerants, hydrocarbon refrigerants, fluorine-containing ether refrigerants such as perfluoroethers, bis(trifluoromethyl)sulfide refrigerants, trifluoroiodomethane refrigerants, and natural refrigerants such as ammonia and carbon dioxide, as well as mixed refrigerants of two or more selected from these refrigerants.

[0129] The saturated fluorohydrocarbon refrigerant is preferably a saturated fluorohydrocarbon refrigerant having 1 to 3 carbon atoms, more preferably 1 to 2. Specific examples 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), and 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), 1,1,1,3,3-pentafluoropropane (R245fa), and 1,1,1,3,3-pentafluorobutane (R365mfc), or a mixture of two or more thereof.

[0130] The saturated fluorohydrocarbon refrigerant is appropriately selected from the above depending on the application and required performance, and examples thereof include R32 alone; R23 alone; R134a alone; R125 alone; a mixture of R134a / R32 = 60 to 80 mass% / 40 to 20 mass%; a mixture of R32 / R125 = 40 to 70 mass% / 60 to 30 mass%; and a mixture of R125 / R143a = 40 to 60 mass% / 60 to 30 mass%. Preferred examples include a mixture of 0 to 40% by mass; a mixture of R134a / R32 / R125=60% by mass / 30% by mass / 10% by mass; a mixture of R134a / R32 / R125=40 to 70% by mass / 15 to 35% by mass / 5 to 40% by mass; and a mixture of R125 / R134a / R143a=35 to 55% by mass / 1 to 15% by mass / 40 to 60% by mass. More specifically, a mixture of R134a / R32=70 / 30 mass%; a mixture of R32 / R125=60 / 40 mass%; a mixture of R32 / R125=50 / 50 mass% (R410A); a mixture of R32 / R125=45 / 55 mass% (R410B); a mixture of R125 / R143a=50 / 50 mass% (R507C); A mixture of R32 / R125 / R134a=30 / 10 / 60 mass% (R407C); a mixture of R32 / R125 / R134a=23 / 25 / 52 mass% (R407E); a mixture of R125 / R134a / R143a=44 / 4 / 52 mass% (R404A), etc. can be used.

[0131] The unsaturated fluorohydrocarbon (HFO) refrigerant is preferably a fluoropropene, more preferably a fluoropropene having 3 to 5 fluorine atoms. Specifically, the unsaturated fluorohydrocarbon refrigerant is preferably one or a mixture of two or more of 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and 3,3,3-trifluoropropene (HFO-1243zf). From the viewpoint of refrigerant properties, one or more selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf are preferred.

[0132] The hydrocarbon refrigerant is preferably a hydrocarbon having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2 to 4 carbon atoms. Specific examples of hydrocarbons include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane, normal pentane, and mixtures of two or more of these. Among these, those that are gaseous at 25°C and 1 atmospheric pressure are preferably used, and propane, normal butane, isobutane, 2-methylbutane, and mixtures of these are preferred.

[0133] The content of the refrigerating machine oil in the working fluid composition for a refrigerating machine may be preferably 1 to 500 parts by mass, more preferably 2 to 400 parts by mass, per 100 parts by mass of the refrigerant.

[0134] The refrigerating machine oil and working fluid composition for a refrigerating machine according to the present embodiment are suitably used in refrigeration machines such as air conditioners having reciprocating or rotary hermetic compressors, refrigerators, open or hermetic car air conditioners, dehumidifiers, water heaters, freezers, refrigerated and freezer warehouses, vending machines, showcases, and chemical plants, as well as refrigeration machines having centrifugal compressors. [Example]

[0135] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0136] Refrigerating machine oils were prepared by blending the base oils shown below with the various additives shown below to obtain the compositions (mass % based on the total amount of refrigerating machine oil) shown in Table 1. The refrigerating machine oils were prepared by adding the base oils to the additive mixtures obtained by mixing the various additives described above.

[0137] (base oil) A1: A mixed base oil of the following (a1) and (a2) (mixing ratio (mass ratio): (a1) / (a2)=70 / 30) (a1) Polyol ester of pentaerythritol and a mixed fatty acid of 2-methylpropanoic acid / 3,5,5-trimethylhexanoic acid (mixing ratio (mass ratio): 60 / 40) (kinematic viscosity at 40°C: 46 mm 2 / s, 100℃ kinematic viscosity: 6.3mm 2 / s) (a2) A complex ester (kinematic viscosity at 40°C: 146 mmHg) obtained by reacting an ester intermediate obtained by reacting neopentyl glycol (1 mol) and 1,4-butanediol (0.2 mol) with adipic acid (1.5 mol) and further reacting the ester intermediate with 3,5,5-trimethylhexanol (1.1 mol), and removing the remaining unreacted material by distillation. 2 / s, viscosity index: 140)

[0138] (phosphonic acid diester) B1: Dilauryl hydrogen phosphite B2: Di(2-ethylhexyl) hydrogen phosphite B3: Dioleyl Hydrogen Phosphite

[0139] (amine compounds) C1: Di(2-ethylhexyl)amine C2: Oleylamine

[0140] (Other additives) Additive package containing phenolic antioxidant, phosphorus antiwear agent, and epoxy acid scavenger

[0141] In Example 1, phosphonic acid diester B1, amine compound C1, and other additives were added to base oil A1, and the mixture was mixed at 60°C for 60 minutes to obtain a refrigerating machine oil. NMR analysis confirmed that an amine salt of phosphonic acid and / or an amine salt of phosphonic acid monoester was formed in the refrigerating machine oil. 31 The P-NMR charts are shown in Figures 1 and 2.

[0142] Figure 1 shows the results of measurements taken after adding phosphonic acid diester B1 to a solvent (heavy benzene). 31 2 is a P-NMR chart showing the presence of a phosphonic acid diester, a phosphonic acid monoester, and a phosphonic acid. Furthermore, as shown in FIG. 2, it was presumed that the amine compound C1 produced the phosphonic acid monoester and an amine salt of the phosphonic acid. Similarly, for the refrigerating machine oil of Example 1, 31 The peaks of these amine salts were confirmed on the P-NMR chart.

[0143] The wear resistance of each of the refrigerating machine oils of Examples 1 to 5 and Comparative Examples 1 to 3 was evaluated in the following manner on the day of preparation of the refrigerating machine oil and after 7 days had passed in a thermostatic bath at 60°C from the day of preparation. The results are shown in Table 1. Note that for the refrigerating machine oil of Comparative Example 2, no wear resistance effect was obtained on the day of preparation, so the wear resistance after 7 days was not evaluated.

[0144] (Evaluation of abrasion resistance) A friction test device was installed inside a sealed container, with a vane (SKH-51) as the upper test piece and a disk (SNCM220 HRC50) as the lower test piece. 600 g of each refrigeration oil was introduced into the friction test area, and after evacuating the system, 100 g of R32 refrigerant was introduced and heated. After the temperature inside the sealed container was raised to 110°C, a wear test was conducted at a load of 1000 N and a rotation speed of 750 rpm, and the wear amounts of the vane and disk were measured after 60 minutes of testing. The smaller the wear amount, the better the wear resistance.

[0145] [Table 1]

Claims

1. A method for producing a refrigerating machine oil, comprising the step of adding a phosphonic acid diester, at least one member selected from the group consisting of a phosphonic acid and a phosphonic acid monoester, and an amine compound to a lubricating base oil or an oil composition containing the lubricating base oil.

2. The method for producing a refrigerating machine oil according to claim 1 , further comprising adding an acid scavenger in the step.

Images