Refrigeration oil composition and composition for refrigeration machine

Abstract

To provide a refrigeration oil composition which is excellent in wear resistance, seizure resistance, and heat stability.SOLUTION: A refrigeration oil composition includes: a base oil (A); and a phosphonic ester (B) represented by the following general formula (1) (where R1 and R2 each independently represent a 1-8C hydrocarbon group and R3 represents a 9-40C hydrocarbon group optionally having a hydroxyl group as a substituent).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a refrigerator oil composition and a composition for a refrigerator. [Background technology]

[0002] A refrigerator, for example, a compression type refrigerator, is generally composed of at least a compressor, a condenser, an expansion mechanism (such as an expansion valve), an evaporator, etc., and has a structure in which a mixture of a refrigerant and a refrigerating machine oil (hereinafter also referred to as a "composition for a refrigerator") circulates within a sealed system. As refrigerants for compression-type refrigerators, fluorocarbon compounds that have a low environmental impact are being used in place of the hydrochlorofluorocarbons (HCFCs) that were widely used in the past. As fluorocarbon compounds, saturated fluorocarbon compounds (hydro-fluoro-carbons; hereinafter also referred to as "HFCs") such as 1,1,1,2-tetrafluoroethane (R134a), difluoromethane (R32), and a mixture of difluoromethane and pentafluoroethane (R410A) are widely used. In addition, the use of unsaturated fluorohydrocarbon compounds (Hydro-Fluoro-Olefins; hereinafter also referred to as "HFOs"), which have a low global warming potential, such as 1,3,3,3-tetrafluoropropene (R1234ze) and 2,3,3,3-tetrafluoropropene (R1234yf), is also being considered.

[0003] In order to improve the lubricating performance of refrigeration oils, various additives are blended into the refrigeration oils. Among them, tricresyl phosphate (hereinafter also referred to as "TCP") has been used as an additive to improve wear resistance and seizure resistance. For example, Patent Documents 1 and 2 disclose refrigeration oils containing a phosphonic acid ester as a phosphorus-based extreme pressure agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 021533 [Patent Document 2] International Publication No. 2020 / 171135 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is an increasing demand for refrigeration oils with improved wear resistance, and there is a demand for additives that can improve wear resistance and seizure resistance more than TCP and the phosphonic acid esters specifically described in the above-mentioned patent documents.

[0006] The present inventors have also found that when a lubricating oil composition containing TCP is used as a refrigeration oil, the acid value of the lubricating oil composition increases at high temperatures. This problem is particularly noticeable when unsaturated fluorohydrocarbon compounds (Hydro-Fluoro-Olefin; hereinafter also referred to as "HFO"), which have low global warming potential, such as 1,3,3,3-tetrafluoropropene (R1234ze) and 2,3,3,3-tetrafluoropropene (R1234yf), are used as refrigerants, and improvement is desired.

[0007] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a refrigerating machine oil composition which is excellent in wear resistance, seizure resistance and thermal stability. [Means for solving the problem]

[0008] As a result of intensive research, the present inventors have found that a refrigeration oil composition containing a base oil and a specific phosphonic acid ester can solve the above problems, and have completed the present invention. The present invention has been completed based on this finding. That is, according to each embodiment of the present invention, the following [1] to

[10] are provided. [1] A refrigerator oil composition comprising a base oil (A) and a phosphonic acid ester (B) represented by the following general formula (1): [ka] (In the formula, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R 3 represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent. [2] The refrigerating oil composition according to the above [1], wherein the content of the phosphonate ester (B) is 200 to 4,000 mass ppm in terms of phosphorus atoms based on the total amount of the refrigerating oil composition. [3] In the general formula (1), R 1 and R 2 represents an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms, R 3 represents a hydrocarbon group having 12 to 30 carbon atoms. [4] In the general formula (1), R 3 represents a linear or branched alkyl or alkenyl group having 14 to 24 carbon atoms, or a group represented by the following general formula (2): [ka] (In the formula, L 1 represents a single bond, -CH- or -CHCH-; R 4 and R 5 each independently represents a hydrocarbon group having 2 to 10 carbon atoms. [5] The refrigerating machine oil composition according to any one of the above [1] to [4], wherein the base oil (A) comprises one or more selected from the group consisting of polyalkylene glycols (PAGs), polyvinyl ethers (PVEs), polyol esters (POEs) and mineral oils. [6] The refrigerator oil composition according to any one of the above [1] to [5], further comprising an antioxidant (C). [7] The refrigerator oil composition according to any one of the above [1] to [6], further comprising an acid scavenger (D). [8] The refrigerating machine oil composition according to any one of the above [1] to [7], further comprising one or more selected from the group consisting of an oiliness improver, a copper deactivator, a rust inhibitor, an antifoaming agent, and a viscosity index improver. [9] A composition for a refrigerator comprising the refrigerator oil composition according to any one of the above [1] to [8] and a refrigerant.

[10] The composition for a refrigerator according to the above [9], wherein the refrigerant comprises at least one selected from the group consisting of unsaturated fluorohydrocarbon refrigerants, saturated fluorohydrocarbon refrigerants, hydrocarbon refrigerants, carbon dioxide and ammonia.

[11] The composition for a refrigerator according to the above

[10] , wherein the refrigerant comprises an unsaturated fluorohydrocarbon compound.

[12] A method for producing a refrigerating oil composition, comprising the step of mixing a base oil (A) with a phosphonic acid ester (B) represented by the following general formula (1): [ka] (In the formula, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R 3 represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent. Effect of the Invention

[0009] According to the present invention, it is possible to provide a refrigerating machine oil composition which is excellent in wear resistance, seizure resistance and thermal stability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this specification, the lower limit and upper limit described in stages for a preferred numerical range (e.g., range of content, etc.) can be combined independently. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60." Similarly, in this specification, the numerical values ​​of "greater than or equal to," "less than or equal to," "less than," and "greater than" in the description of a numerical range can be arbitrarily combined.

[0011] In this specification, unless otherwise specified, the term "hydrocarbon group" refers to a group composed only of carbon atoms and hydrogen atoms. The term "hydrocarbon group" also includes "aliphatic groups" composed of straight or branched chains, "alicyclic groups" having one or more saturated or unsaturated carbon rings that do not have aromaticity, and "aromatic groups" having one or more aromatic rings that exhibit aromaticity, such as a benzene ring.

[0012] In the present specification, the term "number of ring carbon atoms" refers to the number of carbon atoms among the atoms constituting the ring itself of a compound having a structure in which atoms are bonded in a ring. When the ring is substituted with a substituent, the carbon atoms contained in the substituent are not included in the number of ring carbon atoms. The number of ring atoms refers to the number of atoms constituting the ring itself in a compound having a structure in which atoms are bonded in a ring, and does not include atoms not constituting the ring (e.g., hydrogen atoms terminating bonds of atoms constituting the ring) and atoms contained in the substituent when the ring is substituted with a substituent. In this specification, the "number of carbon atoms a to b" in the expression "a substituted or unsubstituted X group having a carbon number of a to b" represents the number of carbon atoms when the X group is unsubstituted, and does not include the number of carbon atoms of the substituent when the X group is substituted.

[0013] [Refrigerating machine oil composition] The refrigerating machine oil composition of the present embodiment contains a base oil (A) and a phosphonic acid ester (B) represented by the following general formula (1).

[0014] [ka] (In the formula, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R 3 represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent. The present inventors have investigated additives capable of improving the anti-wear properties of refrigeration oils, and as a result, have found that R 1 and R 2 R 3 It has been found that a refrigerating oil composition containing a phosphonic acid ester having a group with a relatively large number of carbon atoms as the phosphonate exhibits excellent wear resistance and seizure resistance as well as good thermal stability. On the other hand, R 3 When a phosphonic acid ester having a group having 8 or less carbon atoms was used as the aryl group, sufficient effects of improving the wear resistance and seizure resistance could not be obtained. From the above, the present inventors have found that the phosphonic acid ester (B) represented by the above general formula (1) has the effect of improving the wear resistance, seizure resistance and thermal stability of a composition for a refrigerator.

[0015] In the refrigerating machine oil composition of the present embodiment, the total content of component (A) and component (B) is preferably 80 to 100 mass%, more preferably 85 to 100 mass%, even more preferably 90 to 100 mass%, and still more preferably 95 to 100 mass%, based on the total amount (100 mass%) of the refrigerating machine oil composition.

[0016] Hereinafter, each component contained in the refrigerator oil composition of the present embodiment will be described.

[0017] <Base oil (A)> The refrigerating machine oil composition of the present embodiment contains a base oil (A). In the refrigerating machine oil composition of the present embodiment, the content of the base oil (A) is, based on the total amount (100 mass%) of the refrigerating machine oil composition, preferably 85.0 mass% or more, more preferably 90.0 mass% or more, even more preferably 95.0 mass% or more, and is preferably 99.7 mass% or less, more preferably 99.3 mass% or less, even more preferably 99.0 mass% or less, and these lower and upper limits may be arbitrarily combined, and specifically, is preferably 85.0 to 99.7 mass%, more preferably 90.0 to 99.3 mass%, even more preferably 95.0 to 99.0 mass%.

[0018] The base oil (A) can be, for example, one or more oils selected from the group consisting of synthetic oils and mineral oils. As the base oil (A), from the viewpoint of improving the thermal stability of the refrigerating machine oil composition, it is preferable to include one or more base oils selected from the group consisting of polyalkylene glycols (hereinafter also referred to as "PAG"), polyvinyl ethers (hereinafter also referred to as "PVE"), polyol esters (hereinafter also referred to as "POE") and mineral oils (hereinafter also referred to as "base oil (A1)"). From the viewpoint of improving compatibility with the refrigerant, improving hydrolysis resistance, and improving the thermal stability of the refrigerating machine oil composition, it is more preferable to include one or more base oils selected from the group consisting of PVE and PAG (hereinafter also referred to as "base oil (A2)"). From the viewpoint of improving compatibility with the refrigerant, improving hydrolysis resistance, and further improving the thermal stability of the refrigerating machine oil composition, it is even more preferable to include PAG (hereinafter also referred to as "base oil (A3)"). PVE, PAG, POE and mineral oil will be explained in detail below.

[0019] (Polyvinyl ethers (PVE)) The PVE may be any polymer having one or more structural units derived from vinyl ether. When the base oil (A) contains a PVE, the PVE may be used alone or in combination of two or more kinds. From the viewpoint of compatibility with the refrigerant, the PVE is preferably a polymer having one or more structural units derived from vinyl ether and having an alkyl group having 1 to 4 carbon atoms in the side chain. From the viewpoint of further improving compatibility with the refrigerant, the alkyl group is preferably a methyl group or an ethyl group, and more preferably a methyl group.

[0020] The PVE is preferably a polymer (A-1) having one or more structural units represented by the following general formula (A-1).

[0021] [ka]

[0022] In formula (A-1), R 1a , R 2a and R 3a R each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. 4a R represents a divalent hydrocarbon group having 2 to 10 carbon atoms. 5a represents a hydrocarbon group having 1 to 10 carbon atoms; r represents OR 4a The number of repeating units of the formula (A-1) is 0 to 10, preferably 0 to 5, more preferably 0 to 3, and even more preferably 0. 4a If multiple exists, multiple OR 4a may be the same or different.

[0023] R 1a , R 2a and R 3aExamples of the hydrocarbon group having 1 to 8 carbon atoms represented by the formula (I) include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, and various octyl groups; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, and various dimethylcyclohexyl groups; aryl groups such as phenyl group, various methylphenyl groups, various ethylphenyl groups, and various dimethylphenyl groups; and arylalkyl groups such as benzyl group, various phenylethyl groups, and various methylbenzyl groups. Here, "various types" refers to "linear, branched or cyclic" hydrocarbon groups, and for example, "various butyl groups" refers to various butyl groups such as "n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, cyclobutyl group, etc. In addition, for groups having a cyclic structure, this includes positional isomers such as ortho-, meta- and para-isomers, and the same applies hereinafter.

[0024] R 1a , R 2a and R 3a The hydrocarbon group represented by the following formula (1) preferably has 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. R 1a , R 2a and R 3a are each independently preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0025] R 4aExamples of the divalent hydrocarbon group having 2 to 10 carbon atoms represented by the formula (I) include divalent aliphatic groups such as ethylene group, 1,2-propylene group, 1,3-propylene group, various butylene groups, various pentylene groups, various hexylene groups, various heptylene groups, various octylene groups, various nonylene groups, and various decylene groups; divalent alicyclic groups such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane; divalent aromatic groups such as various phenylene groups, various methylphenylene groups, various ethylphenylene groups, various dimethylphenylene groups, and various naphthylenes; divalent alkyl aromatic groups having monovalent bonding sites at the alkyl moiety and aromatic moiety of alkyl aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and divalent alkyl aromatic groups having a bonding site at the alkyl moiety of polyalkyl aromatic hydrocarbons such as xylene and diethylbenzene. R 4a The hydrocarbon group represented by the following formula (1) preferably has 2 to 6 carbon atoms, and more preferably 2 to 4 carbon atoms. R 4a is preferably a divalent aliphatic group having 2 to 10 carbon atoms, and more preferably a divalent aliphatic group having 2 to 4 carbon atoms.

[0026] R 5a Examples of the hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, and various dimethylcyclohexyl groups; aryl groups such as phenyl group, various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl groups, various propylphenyl groups, various trimethylphenyl groups, various butylphenyl groups, and various naphthyl groups; and arylalkyl groups such as benzyl group, various phenylethyl groups, various methylbenzyl groups, various phenylpropyl groups, and various phenylbutyl groups. R 5aThe hydrocarbon group represented by the following formula (1) preferably has 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms. R 5a From the viewpoint of further improving compatibility with the refrigerant, the alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, further preferably a methyl group or an ethyl group, and still further preferably a methyl group.

[0027] The number of units (degree of polymerization) of the structural unit represented by the above general formula (A-1) is appropriately selected according to the kinematic viscosity required for the base oil (A). The polymer having the structural unit represented by the general formula (A-1) may be a homopolymer having only one type of the structural unit, or a copolymer having two or more types of the structural unit. When the polymer is a copolymer, the form of the copolymer is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer. Furthermore, the PVE may contain a polyalkylene glycol structure in its structure, but it is preferable that it does not contain a polyalkylene glycol structure.

[0028] At the terminal portion of the polymer (A-1), a monovalent group derived from a saturated hydrocarbon, ether, alcohol, ketone, amide, nitrile, etc., may be introduced. Among these, it is preferable that one terminal portion of the polymer (A-1) is a group represented by the following general formula (A-1-i).

[0029] [ka]

[0030] In formula (A-1-i), * indicates the bonding position to the carbon atom in the structural unit represented by general formula (A-1) above. In formula (A-1-i), R 6a , R 7a and R 8a each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R 6a , R 7a and R 8a As the hydrocarbon group having 1 to 8 carbon atoms represented by the formula (A-1), 1a , R 2a and R 3a Examples of the hydrocarbon group having 1 to 8 carbon atoms represented by the following formula include the same as those listed above.

[0031] In the above formula (A-1-i), R 9a represents a divalent hydrocarbon group having 2 to 10 carbon atoms, preferably a divalent hydrocarbon group having 2 to 6 carbon atoms, and more preferably a divalent aliphatic group having 2 to 4 carbon atoms. In the above formula (A-1-i), r1 is OR 9a The number of repeating units of the formula (A-1-i) is an integer of 0 to 10, preferably an integer of 0 to 5, more preferably an integer of 0 to 3, and even more preferably 0. 9a If multiple exists, multiple OR 9a may be the same or different. R 9a As the divalent hydrocarbon group having 2 to 10 carbon atoms represented by the formula (A-1), 4a Examples of the divalent hydrocarbon group having 2 to 10 carbon atoms and represented by the following formula include the same as those listed above.

[0032] In formula (A-1-i), R 10a represents a hydrocarbon group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 8 carbon atoms. In addition, R 10a As the alkyl group, when r1 in the above general formula (A-1-i) is 0, it is preferably an alkyl group having 1 to 6 carbon atoms, and when r1 is 1 or more, it is preferably an alkyl group having 1 to 4 carbon atoms. R 10a As the hydrocarbon group having 1 to 10 carbon atoms represented by the formula (A-1), 5a Examples of the hydrocarbon group having 1 to 10 carbon atoms and represented by the following formula include the same as those listed above.

[0033] In addition, when one end moiety of the polymer (A-1) is a group represented by the above general formula (A-1-i), the other end moiety is preferably any one of a group represented by the above general formula (A-1-i), a group represented by the following general formula (A-1-ii), a group represented by the following general formula (A-1-iii), and a group having an olefinically unsaturated bond.

[0034] [ka]

[0035] In formulas (A-1-ii) and (A-1-iii), R 6a , R 7a , R 8a , R 9a , R 10a and r1 are the same as those in the general formula (A-1-i) above. In addition, in the formula (A-1-ii), R 11a , R 12a and r2 are each R in the above general formula (A-1-i). 9a , R 10a and the same as the provisions for r1.

[0036] (Polyalkylene glycols (PAG)) The PAG is preferably a polymer (A-2) represented by the following general formula (A-2). R 13a -[(OR 14a ) m -OR 15a ] n (A-2) When the base oil (A) contains a PAG, the PAG may be used alone or in combination of two or more kinds.

[0037] In the above general formula (A-2), R 13a represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, a divalent to hexavalent hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 10 ring atoms; R 14a represents an alkylene group having 2 to 4 carbon atoms, R15a represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 10 ring atoms. Examples of the substituent that the heterocyclic group may have include an alkyl group having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 3); a cycloalkyl group having 3 to 10 ring carbon atoms (preferably 3 to 8, more preferably 5 or 6); an aryl group having 6 to 18 ring carbon atoms (preferably 6 to 12); a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom); a cyano group; a nitro group; a hydroxy group; and an amino group. These substituents may be further substituted with any of the above-mentioned substituents.

[0038] n is an integer of 1 to 6, preferably an integer of 1 to 3, and more preferably 1. In addition, n is R in the above general formula (A-2). 13a For example, R 13a When R is an alkyl group or an acyl group, n is 1, and R 13a is a hydrocarbon group or a heterocyclic group which is di-, tri-, tetra-, penta- or hexavalent, then n is 2, 3, 4, 5 or 6, respectively. m is OR 14a The number of repeating units is 1 or more, and preferably m×n is a number from 6 to 80. The value of m is determined based on the kinematic viscosity of the base oil (A) at 100° C. of 2 to 50 mm 2 / s, and there is no particular limitation as long as the kinematic viscosity is adjusted to fall within the specified range. In addition, multiple R 14a may be the same or different. When n is 2 or more, multiple R 15a may be the same as or different from each other.

[0039] R 13a and R 15aExamples of the monovalent hydrocarbon group represented by the formula (1) include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups; cycloalkyl groups such as cyclopentyl, cyclohexyl, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, and various dimethylcyclohexyl groups; aryl groups such as phenyl, various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl groups, various propylphenyl groups, various trimethylphenyl groups, various butylphenyl groups, and various naphthyl groups; arylalkyl groups such as benzyl, various phenylethyl groups, various methylbenzyl groups, various phenylpropyl groups, and various phenylbutyl groups; and the like. The alkyl groups may be either linear or branched. R 13a and R 15a From the viewpoint of compatibility with the refrigerant, the monovalent hydrocarbon group represented by the following formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms.

[0040] R 13a and R 15a The hydrocarbon group portion of the acyl group having 2 to 10 carbon atoms represented by the following formula (I) may be linear, branched or cyclic. The alkyl group portion may be any of the above-mentioned R 13a and R 15a Among the hydrocarbon groups represented by the following formula, those having 1 to 9 carbon atoms can be mentioned. R 13a and R 15a The number of carbon atoms in the acyl group represented by the following formula is preferably 2 to 8, and more preferably 2 to 6, from the viewpoint of compatibility with the refrigerant.

[0041] R 13a The divalent to hexavalent hydrocarbon group represented by the above formula (I) is 13aand residues in which hydroxyl groups have been removed from polyhydric alcohols such as trimethylolpropane, glycerin, pentaerythritol, sorbitol, 1,2,3-trihydroxycyclohexane, and 1,3,5-trihydroxycyclohexane. R 13a The number of carbon atoms in the divalent to hexavalent acyl group represented by the following formula is preferably 2 to 10, and more preferably 2 to 6, from the viewpoint of compatibility with the refrigerant.

[0042] R 13a and R 15a The heterocyclic group represented by the following formula (I) is preferably an oxygen atom-containing heterocyclic group or a sulfur atom-containing heterocyclic group. The heterocyclic group may be a saturated ring or an unsaturated ring. Examples of the oxygen atom-containing heterocyclic group include oxygen atom-containing saturated heterocycles such as ethylene oxide, 1,3-propylene oxide, tetrahydrofuran, tetrahydropyran, and hexamethylene oxide; and residues in which 1 to 6 hydrogen atoms have been removed from oxygen atom-containing unsaturated heterocycles such as acetylene oxide, furan, pyran, oxycycloheptatriene, isobenzofuran, and isochromene. Examples of the sulfur atom-containing heterocyclic group include residues in which 1 to 6 hydrogen atoms have been removed from sulfur atom-containing saturated heterocycles such as ethylene sulfide, trimethylene sulfide, tetrahydrothiophene, tetrahydrothiopyran, and hexamethylene sulfide, and sulfur atom-containing unsaturated heterocycles such as acetylene sulfide, thiophene, thiapyran, and thiotripyridene.

[0043] R 13a and R 15a The heterocyclic group represented by the formula (A-1) may have a substituent, and the substituent may be bonded to the oxygen atom in the formula (A-2). As the substituent, as described above, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 3 carbon atoms is more preferable. The heterocyclic group preferably has 3 to 10 ring atoms, and more preferably 3 to 6 ring atoms, from the viewpoint of compatibility with the refrigerant.

[0044] R 14a Examples of the alkylene group represented by the formula (I) include alkylene groups having two carbon atoms, such as a dimethylene group (-CH2CH2-) and an ethylene group (-CH(CH3)-); alkylene groups having three carbon atoms, such as a trimethylene group (-CH2CH2CH2-), a propylene group (-CH(CH3)CH2-), a propylidene group (-CHCH2CH3-), and an isopropylidene group (-C(CH3)2-); and alkylene groups having four carbon atoms, such as a tetramethylene group (-CH2CH2CH2CH2-), a 1-methyltrimethylene group (-CH(CH3)CH2CH2-), a 2-methyltrimethylene group (-CH2CH(CH3)CH2-), and a butylene group (-C(CH3)2CH2-). Among these, R 14a As the alkyl group, a propylene group (-CH(CH3)CH2-) is preferable.

[0045] In the polymer (A-2) represented by the above general formula (A-2), the content of the oxypropylene unit (-OCH(CH3)CH2-) is 14a ) is preferably 50 mol % or more, more preferably 65 mol % or more, and even more preferably 80 mol % or more, based on the total amount (100 mol %) of the copolymers.

[0046] Among the polymers (A-2) represented by the above general formula (A-2), at least one selected from the group consisting of polyoxypropylene glycol dimethyl ether represented by the following general formula (A-2-i), polyoxyethylene polyoxypropylene glycol dimethyl ether represented by the following general formula (A-2-ii), polyoxypropylene glycol monobutyl ether represented by the following general formula (A-2-iii), and polyoxypropylene glycol diacetate are preferred.

[0047] [ka] (In formula (A-2-i), m1 represents a number of 1 or more, and preferably a number of 6 to 80.)

[0048] [ka] (In formula (A-2-ii), m2 and m3 each independently represent a number of 1 or more, and preferably a number such that the value of m2+m3 is 6 to 80.)

[0049] [ka] (In formula (A-2-iii), m4 represents a number of 1 or more, and preferably a number of 6 to 80.)

[0050] Incidentally, m1 in the above general formula (A-2-i), m2 and m3 in the above general formula (A-2-ii), and m4 in the above general formula (A-2-iii) may be appropriately selected according to the kinematic viscosity required for the base oil (A).

[0051] (Polyol esters (POE)) Examples of POE include esters of diols or polyols and fatty acids. When POE is contained in the base oil (A), one type of POE may be used alone, or two or more types may be used in combination. The POE is preferably an ester of a diol or a polyol having 3 to 20 hydroxyl groups and a fatty acid having 3 to 20 carbon atoms.

[0052] Examples of diols include ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0053] Examples of polyols include polyhydric alcohols such as trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, di-(pentaerythritol), tri-(pentaerythritol), glycerin, polyglycerin (a dimer to 20-mer of glycerin), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensates, adonitol, arabitol, xylitol, and mannitol; sugars such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose, gentianose, and melenitose; and partially etherified products thereof, methyl glucoside (glycoside), and the like. Among these, preferred are hindered alcohols such as neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, di-(pentaerythritol), tri-(pentaerythritol), etc. The term "hindered alcohol" refers to an alcohol having a quaternary carbon atom bonded to four carbon atoms.

[0054] From the viewpoint of lubricating performance, the carbon number of the fatty acid is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and still more preferably 8 or more, and from the viewpoint of compatibility with the refrigerant, the carbon number is preferably 20 or less, more preferably 16 or less, even more preferably 12 or less, and still more preferably 10 or less. The carbon number of the fatty acid includes the carbon atom of the carboxy group (-COOH) contained in the fatty acid. The fatty acid may be either a linear or branched fatty acid, but from the viewpoint of lubrication performance, linear fatty acids are preferred, and from the viewpoint of hydrolysis stability, branched fatty acids are preferred. Furthermore, the fatty acid may be either a saturated or unsaturated fatty acid.

[0055] Examples of fatty acids include straight-chain or branched-chain fatty acids such as isobutyric acid, propionic acid, 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, icosanoic acid, and oleic acid, as well as so-called neo acids in which the α carbon atom is quaternary. More specifically, isobutyric acid, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), pelargonic acid (n-nonanoic acid), capric acid (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and the like are preferred.

[0056] The POE may be a partial ester in which some of the hydroxyl groups of the polyol remain unesterified, or a complete ester in which all of the hydroxyl groups are esterified. The POE may be a mixture of a partial ester and a complete ester, but is preferably a complete ester.

[0057] As POE, from the viewpoint of superior hydrolytic stability, esters of hindered alcohols such as neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, di-(pentaerythritol), and tri-(pentaerythritol) are preferred, esters of neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, and pentaerythritol are more preferred, and from the viewpoint of particularly superior compatibility with the refrigerant and hydrolytic stability, esters of pentaerythritol are even more preferred.

[0058] Specific examples of preferred POE include diesters of neopentyl glycol and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; triesters of trimethylolethane and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; triesters of trimethylolpropane and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; triesters of trimethylolbutane and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; triesters of trimethylolbutane and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid; tetraesters of pentaerythritol and one or more fatty acids selected from the group consisting of isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid.

[0059] The ester of two or more fatty acids may be a mixture of two or more esters of one fatty acid and a polyol. Among POEs, esters of two or more mixed fatty acids and polyols are preferred from the viewpoints of improving low-temperature properties and compatibility with refrigerants.

[0060] (Mineral Oil) Examples of mineral oils include oils obtained by distilling paraffinic, intermediate, or naphthenic crude oils at atmospheric pressure, or by vacuum distilling the atmospheric residual oil obtained by atmospheric distillation of crude oil, and then refining the lubricating oil fraction by subjecting it to one or more of the following treatments: solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc.; and oils produced by isomerizing mineral oil wax. When the base oil (A) contains a mineral oil, the mineral oil may be used alone or in combination of two or more kinds.

[0061] In the refrigerating machine oil composition of the present embodiment, the main component of the base oil (A) is preferably the above-mentioned base oil (A1), more preferably the above-mentioned base oil (A2), and even more preferably the above-mentioned base oil (A3). Note that in this specification, the "main component" means the component having the highest content. The content of base oil (A1), base oil (A2) or base oil (A3) in base oil (A) is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%, based on the total amount (100 mass%) of base oil (A). In particular, the content of base oil (A3) in base oil (A) is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, still more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%.

[0062] The base oil (A) may further contain other base oils in addition to the base oil (A1), the base oil (A2) or the base oil (A3). Other base oils include synthetic oils such as polyesters, polycarbonates, hydrogenated α-olefin oligomers, alicyclic hydrocarbon compounds, alkylated aromatic hydrocarbon compounds, poly(oxy)alkylene glycols or copolymers of their monoethers with polyvinyl ethers (ECPs), which do not fall under the above-mentioned PVE, PAG, and POE. In addition, the term "copolymer (ECP) of poly(oxy)alkylene glycol or its monoether and polyvinyl ether" refers to a copolymer having a structural unit derived from poly(oxy)alkylene glycol or its monoether and a structural unit derived from polyvinyl ether, and the term "poly(oxy)alkylene glycol" refers to both polyalkylene glycol and polyoxyalkylene glycol.

[0063] The kinematic viscosity of the base oil (A) at 40°C is preferably 5 to 120 mm 2 / s, more preferably 10 to 110 mm 2 / s, more preferably 30 to 100 mm 2 When the 40° C. kinematic viscosity of the base oil (A) is within the above range, the wear resistance is improved. In this specification, the 40° C. kinematic viscosity is a value measured using a glass capillary viscometer in accordance with JIS K 2283:2000.

[0064] <Phosphonic acid ester (B)> The refrigerator oil composition of the present embodiment contains a phosphonic acid ester (B) represented by the following general formula (1).

[0065] [ka] (In the formula, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R 3 represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent.

[0066] The phosphonate ester (B) represented by the above general formula (1) is a phosphonate having an R bonded to an oxygen atom. 1 and R 2 is a relatively small group that serves to adsorb to the metal surface, while R is oriented toward the inside of the oil film. 3 It is believed that the relatively bulky group R imparts good wear resistance. 1 , R 2 and R3 However, it is presumed that the thermal stability of the refrigerating machine oil composition is not impaired by the fact that any of these is a hydrocarbon group which may have a hydroxyl group as a substituent.

[0067] In the above general formula (1), R 1 and R 2 Examples of the hydrocarbon group having 1 to 8 carbon atoms represented by the formula (I) include an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, a cycloalkyl group having 6 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 8 carbon atoms, and an aryl group having 6 to 8 carbon atoms. Among these, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms is preferred, an alkyl group having 1 to 4 carbon atoms is more preferred, and a methyl group or an ethyl group is particularly preferred.

[0068] Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various hexyl groups, etc. The alkyl group may be either linear or branched. Examples of the cycloalkyl group having 6 to 8 carbon atoms include a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the alkylcycloalkyl group having 6 to 8 carbon atoms include various methylcyclohexyl groups, various ethylcyclohexyl groups, and various dimethylcyclohexyl groups.

[0069] The aryl group having 6 to 8 carbon atoms includes a substituted or unsubstituted phenyl group, and specific examples thereof include a phenyl group, various methylphenyl groups, and various dimethylphenyl groups.

[0070] In the above general formula (1), R 3Examples of the hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent represented by the formula (I) include a substituted or unsubstituted alkyl group having 9 to 40 carbon atoms, a substituted or unsubstituted alkenyl group having 9 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 9 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 9 to 40 carbon atoms, a substituted or unsubstituted alkylcycloalkyl group having 9 to 40 carbon atoms, and a substituted or unsubstituted aryl group having 9 to 40 carbon atoms. Among these, a substituted or unsubstituted alkyl group having 9 to 40 carbon atoms and a substituted or unsubstituted aryl group having 9 to 40 carbon atoms are preferred. The substituent that the various hydrocarbon groups may have is a hydroxyl group.

[0071] Examples of the substituted or unsubstituted alkyl group having 9 to 40 carbon atoms include various alkyl groups such as nonyl groups, various decyl groups, etc. The alkyl group may be either linear or branched.

[0072] Examples of the substituted or unsubstituted aryl group having 9 to 40 carbon atoms include a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, and among these, a substituted or unsubstituted phenyl group is preferred.

[0073] In view of the above, R in the general formula (1) 1 and R 2 are preferably each independently an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms. On the other hand, R in the general formula (1) 3 is preferably a hydrocarbon group having 12 to 30 carbon atoms which may have a hydroxyl group as a substituent, and more specifically, is more preferably a linear or branched alkyl or alkenyl group having 14 to 24 carbon atoms, or a group represented by the following general formula (2).

[0074] [ka] (In the formula, L 1 represents a single bond, -CH- or -CHCH-; R4 and R 5 each independently represents a hydrocarbon group having 2 to 10 carbon atoms.

[0075] Above R 3 is a group represented by the above general formula (2), R adjacent to the hydroxyl group 4 and R 5 From the viewpoint of thermal stability, it is preferable that R is a group having a certain degree of bulkiness. 4 and R 5 As the alkyl group, a hydrocarbon group having 3 to 8 carbon atoms is more preferable.

[0076] In the above general formula (2), R 4 or R 5 Examples of the hydrocarbon group having 2 to 10 carbon atoms represented by the formula (I) include an alkyl group having 2 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, an alkylcycloalkyl group having 6 to 10 carbon atoms, and an aryl group having 6 to 10 carbon atoms. Among these, a substituted or unsubstituted alkyl group having 2 to 10 carbon atoms is preferred, an alkyl group having 3 to 6 carbon atoms is more preferred, and a t-butyl group is particularly preferred.

[0077] Examples of the alkyl group having 2 to 10 carbon atoms include alkyl groups such as ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups; and cycloalkyl groups such as cyclopentyl group, cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, and various dimethylcyclohexyl groups. The alkyl groups may be either linear or branched. The alkyl group preferably has 2 to 10 carbon atoms, and more preferably 3 to 8 carbon atoms.

[0078] Examples of the substituted or unsubstituted aryl group having 6 to 10 carbon atoms include a substituted or unsubstituted phenyl group, naphthyl group, and the like.

[0079] In the refrigerator oil composition of this embodiment, the content of component (B) is, in terms of phosphorus atoms derived from component (B), based on the total amount of the refrigerator oil composition, from the viewpoint of improving wear resistance, preferably 200 ppm by mass or more, more preferably 300 ppm by mass or more, even more preferably 400 ppm by mass or more, particularly preferably 500 ppm by mass or more, and preferably 3,000 ppm by mass or less, more preferably 2,400 ppm by mass or less, even more preferably 2,000 ppm by mass or less, particularly preferably 1,500 ppm by mass or less, and these upper and lower limits may be arbitrarily combined, specifically, preferably 200 to 3,000 ppm by mass, more preferably 300 to 2,400 ppm by mass, even more preferably 400 to 2,000 ppm by mass, particularly preferably 500 to 1,500 ppm by mass. Component (B) used in the refrigerating machine oil composition of this embodiment has a hydrocarbon group which may have a hydroxyl group as a substituent, and therefore has excellent thermal stability, and therefore its content can be relatively large.

[0080] <Additives> The refrigerator oil composition of the present embodiment may further contain additives. From the viewpoint of improving the stability of the refrigerating machine oil composition, the additive preferably contains one or more selected from the group consisting of antioxidants, oiliness improvers, oxygen scavengers, acid scavengers, copper deactivators, rust inhibitors, antifoaming agents and viscosity index improvers, and more preferably contains at least an antioxidant. The refrigerating machine oil composition of the present embodiment may also contain an extreme pressure agent other than component (B). These additives may be used alone or in combination of two or more. The total content of these additives is preferably 0 to 10 mass %, more preferably 0.01 to 8.0 mass %, and even more preferably 0.1 to 5.0 mass %, based on the total amount (100 mass %) of the refrigerator oil composition.

[0081] (Antioxidants) The antioxidant is preferably one or more selected from the group consisting of phenol-based antioxidants and amine-based antioxidants. Examples of the phenol-based antioxidant include 2,6-di-tert-butyl-4-methylphenol (DBPC), 2,6-di-tert-butyl-4-ethylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). Examples of the amine-based antioxidant include phenyl-α-naphthylamine and N,N'-diphenyl-p-phenylenediamine. Among these, 2,6-di-tert-butyl-4-methylphenol (DBPC) is more preferable. From the viewpoints of stability and antioxidant performance, the content of the antioxidant is preferably 0.01 to 5.0 mass%, more preferably 0.05 to 3.0 mass%, and even more preferably 0.10 to 1.50 mass%, based on the total amount (100 mass%) of the refrigerating machine oil composition.

[0082] (Oil improver) Examples of oiliness improvers include aliphatic saturated or unsaturated monocarboxylic acids such as stearic acid and oleic acid; polymerized fatty acids such as dimer acid and hydrogenated dimer acid; hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid; aliphatic saturated or unsaturated monoalcohols such as lauryl alcohol and oleyl alcohol; aliphatic saturated or unsaturated monoamines such as stearylamine and oleylamine; aliphatic saturated or unsaturated monocarboxylic acid amides such as lauric acid amide and oleic acid amide; partial esters of polyhydric alcohols such as glycerin and sorbitol with aliphatic saturated or unsaturated monocarboxylic acids; and the like.

[0083] (Oxygen Scavenger) Examples of oxygen scavengers include aliphatic unsaturated compounds and terpenes having a double bond. The aliphatic unsaturated compound is preferably an unsaturated hydrocarbon, specifically, olefins, polyenes such as dienes and trienes, etc. As the olefin, from the viewpoint of reactivity with oxygen, α-olefins such as 1-tetradecene, 1-hexadecene, 1-octadecene, etc. are preferable. Other aliphatic unsaturated compounds than those mentioned above include those having the molecular formula C, which is selected from the viewpoint of reactivity with oxygen. 20 H 30 Unsaturated aliphatic alcohols having conjugated double bonds, such as vitamin A represented by O ((2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-1-yl)nona-2,4,6,8-tetraen-1-ol), are preferred. As the terpene having a double bond, a terpene-based hydrocarbon having a double bond is preferable. From the viewpoint of reactivity with oxygen, α-farnesene (C 15 H 24 : 3,7,11-trimethyldodeca-1,3,6,10-tetraene) and β-farnesene (C 15 H 24 :7,11-dimethyl-3-methylidene-dodeca-1,6,10-triene) is more preferred.

[0084] (Acid Scavenger) Examples of the acid scavenger include epoxy compounds such as phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil. In particular, at least one selected from glycidyl esters, glycidyl ethers, and α-olefin oxides is preferably used as the acid scavenger. Examples of glycidyl ethers include glycidyl ethers derived from linear, branched or cyclic saturated or unsaturated aliphatic mono- or polyhydric alcohols having a carbon number of usually 3 to 30, preferably 4 to 24, and more preferably 6 to 16, or aromatic compounds containing one or more hydroxyl groups. In the case of aliphatic polyhydric alcohols or aromatic compounds containing two or more hydroxyl groups, it is preferable that all of the hydroxyl groups are glycidyl etherified from the viewpoint of suppressing an increase in the hydroxyl value for the stability of the refrigerating machine oil composition. Among these, it is particularly preferable to use glycidyl ethers derived from linear, branched or cyclic saturated aliphatic monoalcohols having a carbon number of 6 to 16. Examples of such glycidyl ethers include 2-ethylethyl glycidyl ether, isononyl glycidyl ether, caprinoyl glycidyl ether, lauryl glycidyl ether, and myristyl glycidyl ether. On the other hand, the α-olefin oxide used generally has 4 to 50 carbon atoms, preferably 4 to 24 carbon atoms, and more preferably 6 to 16 carbon atoms. The acid scavenger may be used alone or in combination of two or more kinds. The content of the acid scavenger is preferably 0.01 to 5.0 mass %, more preferably 0.05 to 3.0 mass %, and further preferably 0.10 to 2.0 mass %, based on the total amount (100 mass %) of the refrigerating machine oil composition.

[0085] (copper deactivator) The copper deactivator may, for example, be N-[N,N'-dialkyl (alkyl group having 3 to 12 carbon atoms) aminomethyl]triazole.

[0086] (rust inhibitor) Examples of the rust inhibitor include metal sulfonates, aliphatic amines, organic phosphites, organic phosphates, organic sulfonic acid metal salts, organic phosphate metal salts, alkenyl succinates, and polyhydric alcohol esters.

[0087] (Antifoaming agent) The antifoaming agent includes silicone-based antifoaming agents such as silicone oil and fluorinated silicone oil.

[0088] (Viscosity index improver) Viscosity index improvers include polymethacrylates, polyisobutylenes, ethylene-propylene copolymers, hydrogenated styrene-diene copolymers, and the like.

[0089] (Extreme pressure agents other than component (B)) Examples of the extreme pressure agent other than component (B) include phosphorus-based extreme pressure agents other than component (B), metal salts of carboxylic acids, and sulfur-based extreme pressure agents. Examples of phosphorus-based extreme pressure agents other than component (B) include phosphate esters, acid phosphate esters, phosphites, acid phosphites, and amine salts thereof. Specific examples include tricresyl phosphate (TCP), triphenyl phosphate, tri(nonylphenyl)phosphite, dioleylhydrogen phosphite, and 2-ethylhexyldiphenyl phosphite. Examples of the metal salt of a carboxylic acid include metal salts of a carboxylic acid having 3 to 60 carbon atoms (preferably 3 to 30 carbon atoms). Among these, one or more selected from the group consisting of metal salts of fatty acids having 12 to 30 carbon atoms and dicarboxylic acids having 3 to 30 carbon atoms are preferred. As the metal constituting the metal salt, alkali metals and alkaline earth metals are preferred, and alkali metals are more preferred. Examples of the sulfur-based extreme pressure agents include sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes, and dialkylthiodipropionates. In the refrigerating machine oil composition of the present embodiment, since component (B) exerts an effect as an extreme pressure agent, the refrigerating machine oil composition may not contain any extreme pressure agent other than component (B). When the refrigerant oil composition of the present embodiment contains an extreme pressure agent other than component (B), the content thereof is, from the viewpoints of lubricity and stability, preferably 1 mass % or less, more preferably 0.5 mass % or less, and even more preferably 0.1 mass % or less, based on the total amount (100 mass %) of the refrigerant oil composition. Furthermore, from the viewpoint of improving corrosion resistance, the content of the dithiophosphate ester in the refrigerating machine oil composition of this embodiment is preferably 1 mass % or less, more preferably 0.5 mass % or less, even more preferably 0.1 mass % or less, based on the total amount (100 mass %) of the refrigerating machine oil composition, and it is most preferable that the refrigerating machine oil composition is not contained.

[0090] <Uses of refrigerating machine oil composition> More specifically, the refrigeration oil composition of the present embodiment is used in a refrigerator having a refrigeration cycle essentially consisting of a compressor, a condenser, an expansion mechanism (such as an expansion valve) and an evaporator, or a compressor, a condenser, an expansion mechanism, a dryer and an evaporator. The refrigeration oil composition of the present embodiment is preferably used, for example, to lubricate sliding parts provided in a compressor or the like. Therefore, the present invention also provides a lubrication method in which the refrigerating machine oil composition of the present embodiment is used for lubricating parts inside a refrigerator. The refrigerating machine oil composition of the present embodiment can be used, for example, in air conditioners, refrigerators, vending machines, showcases, refrigeration systems, hot water supply systems, or heating systems. Examples of air conditioners include car air conditioners such as open-type car air conditioners and electric car air conditioners; gas heat pump (GHP) air conditioners; and the like.

[0091] [Composition for refrigerators] The refrigeration composition of the present embodiment is a refrigeration composition containing the refrigeration oil composition of the present embodiment and a refrigerant.

[0092] <Refrigerant> The refrigerant may be a fluorohydrocarbon refrigerant such as an unsaturated fluorohydrocarbon compound or a saturated fluorohydrocarbon compound; or a natural refrigerant such as a hydrocarbon refrigerant, carbon dioxide, or ammonia. These may be used alone or in combination of two or more. Among these, the refrigerant is preferably one containing one or more selected from the group consisting of an unsaturated fluorohydrocarbon compound, a saturated fluorohydrocarbon compound, a hydrocarbon, carbon dioxide, and ammonia, and more preferably one containing an unsaturated fluorohydrocarbon compound. Each refrigerant will be described below.

[0093] <Unsaturated fluorohydrocarbon compounds> Unsaturated fluorocarbon compounds have low thermal stability at high temperatures, and therefore when used as refrigerants, they have the drawback of generating acidic substances such as hydrogen fluoride (HF) and easily increasing their acid value, but by using the refrigeration oil composition of this embodiment, the drawback of unsaturated fluorocarbon compounds that their acid value easily increases can be eliminated, and the stability of refrigeration systems using unsaturated fluorocarbon compounds as refrigerants can be ensured. In addition, the refrigeration oil composition of this embodiment exhibits particularly excellent wear resistance and seizure resistance when combined with a fluorocarbon refrigerant (particularly an unsaturated fluorocarbon refrigerant). Therefore, in the composition for a refrigerator of this embodiment, the refrigerant is preferably a refrigerant containing an unsaturated fluorohydrocarbon compound (HFO). The content of unsaturated fluorohydrocarbon compounds (HFOs) in the refrigerant, based on the total amount (100 mass%) of the refrigerant, is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more. It is even more preferable that the refrigerant is a refrigerant consisting only of unsaturated fluorohydrocarbon compounds (HFOs).

[0094] Examples of the unsaturated fluorinated hydrocarbon compound include those having a carbon-carbon double bond, such as fluorinated linear or branched chain olefins having 2 to 6 carbon atoms and cyclic olefins having 4 to 6 carbon atoms. More specific examples include ethylene having 1 to 3 fluorine atoms introduced, propene having 1 to 5 fluorine atoms introduced, butene having 1 to 7 fluorine atoms introduced, pentene having 1 to 9 fluorine atoms introduced, hexene having 1 to 11 fluorine atoms introduced, cyclobutene having 1 to 5 fluorine atoms introduced, cyclopentene having 1 to 7 fluorine atoms introduced, and cyclohexene having 1 to 9 fluorine atoms introduced. Among these unsaturated fluorohydrocarbon compounds, propene fluorides are preferred, propene having 3 to 5 fluorine atoms introduced is more preferred, and propene having 4 fluorine atoms introduced is even more preferred.Specifically, preferred compounds include 1,3,3,3-tetrafluoropropene (R1234ze) and 2,3,3,3-tetrafluoropropene (R1234yf). These unsaturated fluorohydrocarbon compounds may be used alone or in combination of two or more, or may be used in combination with a refrigerant other than an unsaturated fluorohydrocarbon compound. Examples of the refrigerant used in combination with a refrigerant other than an unsaturated fluorohydrocarbon compound include a mixed refrigerant of a saturated fluorohydrocarbon compound and an unsaturated fluorohydrocarbon compound. Examples of the mixed refrigerant include a mixed refrigerant of R32 and R1234yf, a mixed refrigerant of R32, R1234ze and R152a (AC5, mixing ratio is 13.23:76.20:9.96), and the like.

[0095] The saturated fluorinated hydrocarbon compound is preferably a fluoride of an alkane having 1 to 4 carbon atoms, more preferably a fluoride of an alkane having 1 to 3 carbon atoms, and even more preferably a fluoride of an alkane (methane or ethane) having 1 or 2 carbon atoms. Examples of the fluoride of methane or ethane include trifluoromethane (R23), difluoromethane (R32), 1,1-difluoroethane (R152a), 1,1,1-trifluoroethane (R143a), 1,1,2-trifluoroethane (R143), 1,1,1,2-tetrafluoroethane (R134a), 1,1,2,2-tetrafluoroethane (R134), and 1,1,1,2,2-pentafluoroethane (R125). Among these, difluoromethane and 1,1,1,2,2-pentafluoroethane are preferred. These saturated fluorohydrocarbon compounds may be used alone or in combination of two or more. Examples of the combination of two or more include a mixed refrigerant in which two or more saturated fluorohydrocarbon compounds having a carbon number of 1 to 3 are mixed, and a mixed refrigerant in which two or more saturated fluorohydrocarbon compounds having a carbon number of 1 to 2 are mixed. Examples of the mixed refrigerant include a mixture of R32 and R125 (R410A), a mixture of R125, R143a, and R134a (R404A), a mixture of R32, R125, and R134a (R407A, R407C, R407E, etc.), and a mixture of R125 and R143a (R507A).

[0096] <Natural refrigerant> The natural refrigerant may be one or more selected from the group consisting of hydrocarbon refrigerants (HC), carbon dioxide (CO2) and ammonia, and is preferably a hydrocarbon refrigerant. These refrigerants may be used alone or in combination of two or more, or may be combined with a refrigerant other than a natural refrigerant. Here, an example of a refrigerant used in combination with a refrigerant other than a natural refrigerant may be a mixed refrigerant with a saturated fluorohydrocarbon compound and / or an unsaturated fluorohydrocarbon compound. A specific example of a mixed refrigerant is a mixed refrigerant of carbon dioxide, R1234ze and R134a (AC6, blend ratio 5.15:79.02:15.41).

[0097] The hydrocarbon refrigerant is preferably a hydrocarbon having 1 to 8 carbon atoms, more preferably a hydrocarbon having 1 to 5 carbon atoms, and even more preferably a hydrocarbon having 3 to 5 carbon atoms. If the carbon number is 8 or less, the boiling point of the refrigerant is not too high, which is preferable as a refrigerant. Examples of the hydrocarbon refrigerant include methane, ethane, ethylene, propane (R290), cyclopropane, propylene, n-butane, isobutane (R600a), 2-methylbutane, n-pentane, isopentane, cyclopentane isobutane, and normal butane. The hydrocarbon refrigerant may be used alone or in combination of two or more. The hydrocarbon refrigerant may be used alone or as a mixed refrigerant mixed with a refrigerant other than the hydrocarbon refrigerant, such as a fluorohydrocarbon refrigerant such as R134a or carbon dioxide.

[0098] In the refrigerator composition of the present embodiment, the amounts of the refrigerant and the refrigerator oil composition used are preferably 1 / 99 to 90 / 10, more preferably 5 / 95 to 70 / 30, in terms of the mass ratio of the refrigerator oil composition / refrigerant. When the mass ratio of the refrigerator oil composition / refrigerant is within this range, lubricity and suitable refrigeration capacity in the refrigerator can be obtained.

[0099] The composition for a refrigerator of the present embodiment is preferably used in, for example, an air conditioner, a refrigerator, an automatic vending machine, a showcase, a refrigeration system, a hot water supply system, or a heating system. Examples of the air conditioner include car air conditioners such as an open type car air conditioner and an electric car air conditioner; a gas heat pump (GHP) air conditioner; and the like. EXAMPLES

[0100] The present invention will be described in more detail with reference to the following examples, although the present invention is not limited to the following examples.

[0101] The types of each component used in preparing the refrigerator oil compositions of the Examples and Comparative Examples are shown below. (1) Base oil 40℃ kinematic viscosity 47.0mm 2 Polyalkylene glycols (PAG) with 1000 g / s were used as base oils. The 40° C. kinematic viscosity was measured using a glass capillary viscometer in accordance with JIS K2283:2000.

[0102] (2) Component (B) Phosphonate ester 1: Dimethylstearylphosphonate (Solvay, DURAPHOS100) Phosphonic acid ester 2: Diethylstearylphosphonate (JC-390, manufactured by Johoku Chemical Industry Co., Ltd.) Phosphonate ester 3: Diethyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate (JC-356, manufactured by Johoku Chemical Industry Co., Ltd.)

[0103] (3) Comparative extreme pressure agent (component (B')) Phosphonic acid ester 1': Diethyl phenyl phosphonate (DEPP, manufactured by Johoku Chemical Industry Co., Ltd.) Phosphonate ester 2': Diethyl-4-methylbenzylphosphonate (JC-243, manufactured by Johoku Chemical Industry Co., Ltd.) TCP: Tricresyl phosphate

[0104] (4) Phenolic antioxidants DBPC: 2,6-di-t-butyl-4-methylphenol

[0105] (5) Acid Scavenger Epoxy acid scavenger: 2-ethylhexyl glycidyl ether

[0106] (6) Refrigerant ·R1234yf: 2,3,3,3-tetrafluoropropene

[0107] The structural formulae of the above components (B) and (B') are shown below. [ka]

[0108] [Examples 1 to 3 and Comparative Examples 1 to 3] Refrigerating machine oil compositions having the compositions shown in Table 1 were prepared and evaluated for wear resistance, seizure resistance and thermal stability by the methods described below. The evaluation results are shown in Table 1. The blending amounts of component (B) and component (B') in each refrigerating machine oil composition were adjusted so that the phosphorus atom content in the total amount of the composition was 840 ppm by mass.

[0109] [Phosphorus atom content] The phosphorus atom content was measured in accordance with JPI-5S-38-03.

[0110] [Falex Test] (1) The following items were prepared as pins and blocks: Pin: SAE3135 Block: AISIC1137 (2) Wear measurement The following tests were carried out using a closed Falex testing machine in accordance with ASTM D2670. A pin and a block were set in a closed Falex testing machine, and 280 g of the refrigeration oil composition to be evaluated was introduced into the test vessel. After the pressure was reduced once, the refrigerant (R1234yf) was sealed in until the pressure reached 0.3 MPaG. The machine was then operated for 60 minutes with the rotation speed set to 290 rpm, the oil temperature set to 50°C, and the load set to 1,779 N, and the wear amount (mg) of the pin and the block was measured. (3) Seizure load measurement The following tests were carried out using an open Falex testing machine in accordance with ASTM D3233. The pin and block were set, and the seizure load of the sample oil (refrigerating machine oil composition) was measured under the following conditions. Break-in load: 1112N x 1 minute Rotational speed: 290 rpm Oil temperature: Room temperature

[0111] [Thermal stability] An autoclave vessel (volume: 200 ml) was charged with Fe, Cu, and Al as catalysts, and further charged with a mixture of 20 g of the refrigerating machine oil composition obtained in each example and 20 g of a refrigerant (R1234yf), as well as 2,000 ppm by mass of moisture. After holding at 175°C for 336 hours, the acid value (mgKOH / g) was evaluated. The acid value was measured by indicator photometric titration method in accordance with JIS K2501 (see Appendix 1 of the JIS standard).

[0112] [Table 1]

[0113] As can be seen from Table 1, the refrigeration oil compositions of Examples 1 to 3 using component (B) had low wear, high seizure load, and relatively low acid value after the thermal stability test. On the other hand, the phosphonic acid ester 1′ used in Comparative Example 1 is R 3 is a phenyl group, and the phosphonic acid ester 2′ used in Comparative Example 2 is R 3was a methylbenzyl group, and none of the carbon numbers were 9 or more, and as a result, the obtained refrigerating machine oil composition had a large amount of wear and an insufficient seizure load. Furthermore, the refrigerating machine oil composition of Comparative Example 3, which used TCP, had a large amount of wear, an insufficient seizure load, and a relatively large acid value after the thermal stability test. From the above results, it is apparent that the refrigerating machine oil composition of the present embodiment is excellent in wear resistance and seizure resistance, and also in thermal stability. [Industrial Applicability]

[0114] The refrigeration oil composition of the present embodiment has excellent wear resistance, seizure resistance, and thermal stability. Therefore, it can be suitably used in, for example, car air conditioners such as open-type car air conditioners and electric car air conditioners, room air conditioners and packaged air conditioners, refrigeration systems such as gas heat pumps (GHPs), freezers, refrigerators, vending machines, and showcases, hot water systems such as water heaters and floor heating systems, and heating systems.

Claims

1. A refrigerator oil composition comprising a base oil (A) and a phosphonate ester (B) represented by the following general formula (1): 【Chemical 1】 (In the formula, R １ and R ２ each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R ３ represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent.

2. The refrigerator oil composition according to claim 1, wherein the content of the phosphonate ester (B) is 200 to 4,000 mass ppm in terms of phosphorus atoms based on the total amount of the refrigerator oil composition.

3. In the general formula (1), R １ and R ２ each independently represents an alkyl group having 1 to 4 carbon atoms or an alkenyl group having 2 to 4 carbon atoms, R ３ The refrigerator oil composition according to claim 1 or 2, wherein represents a hydrocarbon group having 12 to 30 carbon atoms which may have a hydroxyl group as a substituent.

4. In the general formula (1), R ３ represents a linear or branched alkyl or alkenyl group having 14 to 24 carbon atoms, or a group represented by the following general formula (2): 【Chemistry 2】 (In the formula, L １ is a single bond, -CH ２ - or -CH ２ CH ２ - indicates R ４ and R ５ each independently represents a hydrocarbon group having 2 to 10 carbon atoms.

5. 3. The refrigerator oil composition according to claim 1, wherein the base oil (A) comprises one or more selected from the group consisting of polyalkylene glycols (PAGs), polyvinyl ethers (PVEs), polyol esters (POEs), and mineral oils.

6. The refrigerator oil composition according to claim 1 or 2, further comprising an antioxidant (C).

7. The refrigerator oil composition according to claim 1 or 2, further comprising an acid scavenger (D).

8. The refrigerator oil composition according to claim 1 or 2, further comprising one or more selected from the group consisting of an oiliness improver, a copper deactivator, a rust inhibitor, an antifoaming agent, and a viscosity index improver.

9. A refrigerator composition comprising the refrigerator oil composition according to claim 1 or 2 and a refrigerant.

10. 10. The composition for a refrigerator according to claim 9, wherein the refrigerant comprises at least one selected from the group consisting of unsaturated fluorohydrocarbon refrigerants, saturated fluorohydrocarbon refrigerants, hydrocarbon-based refrigerants, carbon dioxide, and ammonia.

11. The refrigerator composition according to claim 10, wherein the refrigerant comprises an unsaturated fluorohydrocarbon compound.

12. A method for producing a refrigerator oil composition, comprising the step of mixing a base oil (A) with a phosphonic acid ester (B) represented by the following general formula (1): 【Chemistry 3】 (In the formula, R １ and R ２ each independently represents a hydrocarbon group having 1 to 8 carbon atoms; R ３ represents a hydrocarbon group having 9 to 40 carbon atoms which may have a hydroxyl group as a substituent.

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