JP6581030B2 - Refrigeration oil - Google Patents

Description

  The present invention relates to refrigerating machine oil.

  Refrigerators such as refrigerators, car air conditioners, room air conditioners, and vending machines include a compressor for circulating the refrigerant in the refrigeration cycle. The compressor is filled with refrigerating machine oil for lubricating the sliding member. In refrigerating machine oil, from the viewpoint of improving stability, it is common to improve the refining degree of the base oil to reduce the acid value and the hydroxyl value of the base oil (for example, Patent Document 1).

JP 2012-052135 A

  By the way, from the viewpoint of improving the wear resistance of refrigeration oil, it has been studied to use a complex ester as a base oil. However, the acid value and hydroxyl value of the complex ester are not necessarily small, and the stability of the refrigerating machine oil when the complex ester is used is not always sufficient.

  Further, from the viewpoint of improving the wear resistance and the like, for example, a phosphorus-based, sulfur-based, or phosphorus-sulfur-based extreme pressure agent may be blended with the refrigerating machine oil. Among these extreme pressure agents, particularly acidic extreme pressure agents are not necessarily stable themselves because of their high activity, and as a result, they can be a factor that deteriorates refrigerating machine oil. Therefore, it is not always easy to ensure the stability of refrigerating machine oil containing such an acidic additive.

  That is, when a base oil (for example, a complex ester) having an acid value or hydroxyl value exceeding a certain level is used, or when an acidic additive is used in combination, a difficult problem to be overcome in terms of the stability of the refrigerating machine oil Can be said to exist.

  The present invention has been made in view of the circumstances as described above, and provides a refrigerating machine oil having improved stability even when, for example, a complex ester is used or an acidic additive is used. The purpose is to do.

  When the present inventors use a specific lubricating base oil and a specific two types of epoxy compounds in combination, the stability of the refrigerating machine oil is ensured even when, for example, an acidic additive is used. I found out.

  That is, the present invention relates to a lubricating base oil containing a complex ester of at least one selected from the group consisting of monohydric alcohols having 4 to 18 carbon atoms and monohydric fatty acids having 4 to 18 carbon atoms and an ester intermediate. The ester intermediate is selected from the group consisting of a polybasic acid containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and a polybasic acid having 6 to 12 carbon atoms. Lubricating oil base oil which is an ester with at least one polybasic acid, a glycidyl ester type epoxy compound represented by the following formula (A), and a glycidyl ether type epoxy compound represented by the following formula (B) And a refrigerating machine oil comprising:

［式（Ａ）中、Ｒ^ａはアリール基、アルキル基又はアルケニル基を表す。］

［式（Ｂ）中、Ｒ^ｂはアリール基又はアルキル基を表す。］

[In the formula (A), R ^a represents an aryl group, an alkyl group or an alkenyl group. ]

[In the formula (B), R ^b represents an aryl group or an alkyl group. ]

  The refrigerating machine oil may further contain an acidic phosphorus compound.

  According to the present invention, it is possible to provide a refrigerating machine oil having improved stability even when, for example, a complex ester is used or an acidic additive is used.

  The refrigerating machine oil according to the present embodiment includes a lubricating base oil, a glycidyl ester type epoxy compound represented by the following formula (A) (hereinafter also simply referred to as “glycidyl ester type epoxy compound”), and a formula (B) below. And a glycidyl ether type epoxy compound (hereinafter, also simply referred to as “glycidyl ether type epoxy compound”).

［式（Ａ）中、Ｒ^ａはアリール基、アルキル基又はアルケニル基を表す。］

［式（Ｂ）中、Ｒ^ｂはアリール基又はアルキル基を表す。］

[In the formula (A), R ^a represents an aryl group, an alkyl group or an alkenyl group. ]

[In the formula (B), R ^b represents an aryl group or an alkyl group. ]

  The lubricating base oil is a complex ester (hereinafter simply referred to as “complex ester”) of at least one selected from the group consisting of monohydric alcohols having 4 to 18 carbon atoms and monohydric fatty acids having 4 to 18 carbon atoms and an ester intermediate. "). The ester intermediate is at least one selected from the group consisting of polyhydric alcohols containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and polybasic acids having 6 to 12 carbon atoms. It is an ester with a polybasic acid containing

Complex ester is ester of the following (a-1) or (a-2), for example.
(A-1) a polyhydric alcohol containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and at least one selected from the group consisting of polybasic acids having 6 to 12 carbon atoms. An ester intermediate with a polybasic acid containing an ester intermediate having a carboxyl group;
A polyvalent compound comprising at least one selected from the group consisting of monohydric alcohols having 4 to 18 carbon atoms and at least one selected from the group consisting of ester (a-2) neopentyl glycol, trimethylolpropane and pentaerythritol. An ester intermediate of an alcohol and a polybasic acid containing at least one selected from the group consisting of polybasic acids having 6 to 12 carbon atoms, an ester intermediate having a hydroxyl group;
Esters having at least one selected from the group consisting of monovalent fatty acids having 4 to 18 carbon atoms

The complex ester is an ester synthesized by the following method (b-1) or (b-2), for example.
(B-1) a polyhydric alcohol containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and at least one selected from the group consisting of polybasic acids having 6 to 12 carbon atoms. The molar ratio of the polybasic acid to be contained is adjusted to synthesize an ester intermediate such that a part of the carboxyl group of the polybasic acid remains without being esterified, and then the remaining carboxyl group has 4 carbon atoms. (B-2) a polyhydric alcohol containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and a polybasic group having 6 to 12 carbon atoms Adjusting the molar ratio with a polybasic acid containing at least one selected from the group consisting of acids, METHOD partially synthesize the ester intermediate as remains without being esterified, then esterifying the hydroxyl groups thereof remaining in a monovalent fatty acid having 4 to 18 carbon atoms

  Since the complex ester (a-2) (complex ester obtained by the method (b-2) above) is hydrolyzed during use as a refrigerating machine oil, a relatively strong acid is produced. Compared with the complex ester (complex ester obtained by the method (b-1) above), the stability tends to be slightly inferior. From this point of view, the complex ester (a-1) (complex ester obtained by the method (b-1)), which is more excellent in terms of stability, is preferably used as the complex ester.

  The polyhydric alcohol constituting the complex ester is preferably a neopentyl glycol or trimethylol propane from the viewpoint of securing a suitable refrigerating machine viscosity and obtaining good low-temperature characteristics, from the viewpoint of wide viscosity adjustment, More preferred is neopentyl glycol.

  From the viewpoint of excellent lubricity, the polyhydric alcohol constituting the complex ester is preferably a dihydric alcohol having 2 to 10 carbon atoms other than neopentyl glycol, in addition to neopentyl glycol, trimethylolpropane or pentaerythritol. contains. Examples of the dihydric alcohol having 2 to 10 carbon atoms other than neopentyl glycol include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, 2-methyl-1,3-propanediol, and 3-methyl-1,5. -Pentanediol, 2,2-diethyl-1,3-pentanediol and the like. Of these, butanediol is preferably used from the viewpoint of excellent properties of the lubricating base oil. Examples of butanediol include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, and the like. Among these, 1,3-butanediol or 1,4-butanediol is preferably used from the viewpoint of excellent lubricating base oil characteristics. 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 with respect to 1 mol of the total amount of neopentyl glycol, trimethylolpropane and pentaerythritol. Hereinafter, it is more preferably used at 0.4 mol or less.

  Examples of the polybasic acid having 6 to 12 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and trimellitic acid. The polybasic acid is preferably adipic acid or sebacic acid, more preferably adipic acid, from the viewpoint of excellent balance of properties of the complex ester and easy availability. 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, still more preferably 0.6 mol to 1 mol of the polyhydric alcohol. Used at 2.5 moles.

  Examples of the monohydric alcohol 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. The monohydric alcohol having 4 to 18 carbon atoms is preferably a monohydric alcohol having 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms, from the viewpoint of excellent balance of properties of the complex ester. Among these, 2-ethylhexanol or 3,5,5-trimethylhexanol is preferably used from the viewpoint of excellent low temperature characteristics of the complex ester.

  The monohydric alcohol having 4 to 18 carbon atoms is preferably 0.5 mol to 4 mol, more preferably 0.8 mol to 2 mol, and still more preferably 1.0 mol, with respect to 1 mol of the carboxyl group in the ester intermediate. Used in mol to 1.5 mol. The monohydric alcohol is preferably 1.0 mol or more than 1.0 mol with respect to 1 mol of the carboxyl group in the ester intermediate from the viewpoint that the carboxyl group in the ester intermediate can be completely esterified. Used in quantity. After the reaction between the ester intermediate and the monohydric alcohol, it is preferable to distill off a part or all of the remaining unreacted monohydric alcohol.

  Examples of the monovalent fatty acid having 4 to 18 carbon atoms include 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 acid having 4 to 18 carbon atoms is preferably a monovalent fatty acid having 8 to 10 carbon atoms, and more preferably 2-ethylhexanoic acid or 3,5,5- from the viewpoint of excellent low temperature properties of the complex ester. Trimethylhexanoic acid.

  The monovalent fatty acid having 4 to 18 carbon atoms is preferably 0.5 to 4 mol, more preferably 0.8 to 2 mol, and still more preferably 1.0 mol with respect to 1 mol of the hydroxyl group in the ester intermediate. Used at ~ 1.5 moles. The monovalent fatty acid is preferably used in an amount exceeding 1.0 mol or 1.0 mol with respect to 1 mol of the hydroxyl group in the ester intermediate from the viewpoint that the hydroxyl group in the ester intermediate can be completely esterified. It is done. After the reaction between the ester intermediate and the monovalent fatty acid, it is preferable to distill off a part or all of the remaining unreacted monovalent fatty acid.

  The hydroxyl value of the complex ester is preferably 0.01 mgKOH / g or more, more preferably 5 mgKOH / g or more, and still more preferably 15 mgKOH / g or more, from the viewpoint of facilitating the effect of reducing friction. The hydroxyl value of the complex ester is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less, from the viewpoint of obtaining a refrigerating machine oil having a suitable volume resistivity. The hydroxyl value in the present invention means a hydroxyl value measured according to JIS K0070-1992.

  The number average molecular weight (Mn) of the complex ester is preferably 500 or more, more preferably 1000 or more, preferably 10,000 or less, more preferably 5000 or less, and still more preferably 3000 or less. It's okay.

  The weight average molecular weight (Mw) of the complex ester is preferably 500 or more, more preferably 1000 or more, preferably 10,000 or less, more preferably 5000 or less, and still more preferably 3000 or less. It's okay.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the complex ester is preferably 1.0 or more, more preferably 1.2 or more, still more preferably 1.5 or more. , Preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.0 or less.

  By setting the values of number average molecular weight (Mn), weight average molecular weight (Mw) and Mw / Mn within the above ranges, it is possible to increase the melt viscosity of the refrigerant, improve the wear resistance, and to achieve a desirable compatibility with the refrigerant. Can be maintained.

  The average molecular weight (Mn) and the weight average molecular weight (Mw) of the complex ester are measured, for example, by the following method. Using chloroform as a solvent, a solution is prepared by diluting to a complex ester concentration of 1% by mass. The solution is analyzed using a GPC apparatus (Waters Alliance 2695). The analysis is performed using a refractive index detector using a column having a solvent flow rate of 1 ml / min and an analyzable molecular weight of 100 to 10,000. The relationship between the column retention time and the molecular weight is determined using a polystyrene standard with a clear molecular weight, a calibration curve is separately prepared, and the molecular weight is determined from the obtained retention time.

The kinematic viscosity at 40 ° C. of the complex ester is preferably 30 mm ² / s or more, more preferably 50 mm ² / s or more, still more preferably 80 mm ² / s or more, particularly preferably 120 mm ² / s, and 180 mm ² / s. It may be the above. The kinematic viscosity at 40 ° C. of the complex ester is preferably 1000 mm ² / s or less, more preferably 500 mm ² / s or less, still more preferably 300 mm ² / s or less, and may be less than 180 mm ² / s. Kinematic viscosity at 40 ° C. Complex esters preferably 30 -1000 mM ² / s, more preferably 50 to 300 mm ² / s, more preferably 80~300mm ² / s, particularly preferably 120~180mm ² / s met well ^{Te, 30~120mm 2 / s, 50~80mm 2} / s, may be 180~500mm ² / s or 200 to 300 mm ² / s.

The kinematic viscosity at 100 ° C. of the complex ester may be preferably 3 mm ² / s or more, more preferably 5 mm ² / s or more, and still more preferably 8 mm ² / s. Kinematic viscosity at 100 ° C. Complex esters preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less, more preferably may be at 30 mm ² / s or less.

  The viscosity index of the complex ester is preferably 80 or more, more preferably 100 or more, still more preferably 120 or more, preferably 200 or less, more preferably 160 or less, and even more preferably 150 or less. The kinematic viscosity and viscosity index in the present invention mean the kinematic viscosity and viscosity index measured or calculated according to JIS K2283: 2000, respectively.

  The content of the complex ester is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably, based on the total amount of the base oil. It is 40 mass% or less, More preferably, it is 30 mass% or less. By setting the content of the complex ester in the above range, it is possible to increase the refrigerant dissolution viscosity and improve the wear resistance, and to maintain the compatibility with the refrigerant in a desirable range.

  The lubricating base oil may contain other base oils in addition to the complex ester. Other base oils include hydrocarbon oils and oxygenated oils. Examples of the hydrocarbon oil include mineral oil-based hydrocarbon oil and synthetic hydrocarbon oil. Examples of the oxygen-containing oil include esters other than complex esters, ethers, carbonates, ketones, silicones, polysiloxanes, and the like. The lubricating base oil preferably further contains an ester other than the complex ester, more preferably a polyol ester.

  The polyol ester is an ester of a polyhydric alcohol and a fatty acid. A saturated fatty acid is preferably used as the fatty acid. The carbon number of the fatty acid is preferably 4 to 20, more preferably 4 to 18, still more preferably 4 to 9, and particularly preferably 5 to 9. The polyol ester may be a partial ester in which some of the hydroxyl groups of the polyhydric alcohol are not esterified and remain as hydroxyl groups, or may be a complete ester in which all of the hydroxyl groups are esterified. It may be a mixture of an ester and a complete ester. The hydroxyl value of the polyol ester is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, still more preferably 3 mgKOH / g or less.

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

  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, and pentadecanoic acid. Hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid and icosanoic acid. These fatty acids may be linear or branched. The fatty acid is preferably a fatty acid having a branch at the α-position and / or β-position, and more preferably 2-methylpropanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2- Ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethylhexadecanoic acid and the like are more preferable, among which 2-ethylhexanoic acid and 3,5,5-trimethyl are preferred. Selected from hexanoic acid.

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

  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 of the polyhydric alcohol is preferably 4 to 12, more preferably 5 to 10. The polyhydric alcohol is preferably hindered such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, dipentaerythritol. More preferred are pentaerythritol, dipentaerythritol, or a mixed ester of pentaerythritol and dipentaerythritol because it is an alcohol and is particularly excellent in compatibility with a refrigerant and hydrolytic stability.

  The content of the polyol ester is appropriately adjusted according to the content of the complex ester, and may be, for example, 50% by mass or more, 60% by mass or more, or 70% by mass or more based on the total amount of the base oil. 99 mass% or less, 95 mass% or less, or 90 mass% or less.

Kinematic viscosity at 40 ° C. of the lubricating base oil is preferably ^{3 mm} 2 / s or more, more preferably ^{4 mm} 2 / s or more, may be even more preferably at ^{5 mm} 2 / s or more. Kinematic viscosity at 40 ° C. of the lubricating base oil is preferably 1000 mm ² / s or less, more preferably 500 mm ² / s or less, more preferably may be at 400 mm ² / s or less. The kinematic viscosity at 100 ° C. of the lubricating base oil may be preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. The kinematic viscosity at 100 ° C. of the lubricating base oil may be preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less.

  The content of the lubricating base oil is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more, based on the total amount of refrigerating machine oil.

  The glycidyl ester type epoxy compound is represented by the following formula (A). Specifically, for example, glycidyl benzoate, glycidyl stearate, glycidyl neodecanoate, glycidyl-2,2-dimethyloctanoate, glycidyl acrylate, glycidyl It may be methacrylate.

［式（Ａ）中、Ｒ^ａはアリール基、アルキル基又はアルケニル基を表す。］

[In the formula (A), R ^a represents an aryl group, an alkyl group or an alkenyl group. ]

R ^a is preferably an alkyl group, more preferably a branched alkyl group, from the viewpoint of further improving stability. From the same viewpoint, the carbon number of the alkyl group is preferably 18 or less, more preferably 15 or less, still more preferably 12 or less, and particularly preferably 10 or less. The number of carbon atoms of the alkyl group may be, for example, 5 or more from the viewpoint of the stability of the epoxy compound.

  The content of the glycidyl ester type epoxy compound is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and still more preferably 0.2% by mass based on the total amount of refrigerating machine oil from the viewpoint of improving stability. % Or more. The content of the glycidyl ester type epoxy compound is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 2.0% by mass based on the total amount of refrigerating machine oil from the viewpoint of improving lubricity. % Or less.

  The glycidyl ether type epoxy compound is represented by the following formula (B), specifically, for example, 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 It may be glycidyl ether or 2-ethylhexyl glycidyl ether.

［式（Ｂ）中、Ｒ^ｂはアリール基又はアルキル基を表す。］

[In the formula (B), R ^b represents an aryl group or an alkyl group. ]

R ^b is preferably an alkyl group, more preferably a branched alkyl group, from the viewpoint of further improving stability. From the same viewpoint, the carbon number of the alkyl group is preferably 18 or less, more preferably 14 or less, still more preferably 10 or less, and particularly preferably 8 or less. The number of carbon atoms of the alkyl group may be, for example, 5 or more from the viewpoint of the stability of the epoxy compound.

  The content of the glycidyl ether type epoxy compound is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and still more preferably 0.2% by mass based on the total amount of refrigerating machine oil from the viewpoint of improving stability. % Or more. The content of the glycidyl ether type epoxy compound is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 2.0% by mass based on the total amount of refrigerating machine oil from the viewpoint of improving lubricity. % Or less.

  The refrigerating machine oil may further contain other additives in addition to the lubricating base oil, the glycidyl ester type epoxy compound and the glycidyl ether type epoxy compound. Additives include acid scavengers other than glycidyl ester type epoxy compounds and glycidyl ether type epoxy compounds, antioxidants, extreme pressure agents, oiliness agents, antifoaming agents, metal deactivators, antiwear agents, and viscosity index improvements. Agents, pour point depressants, cleaning dispersants, friction modifiers, rust inhibitors and the like. The content of other additives may be 5% by mass or less, or 2% by mass or less, based on the total amount of refrigerating machine oil.

  The refrigerating machine oil preferably further contains an antiwear agent among other additives. Suitable antiwear agents include, for example, phosphate esters, thiophosphate esters, sulfide compounds, and zinc dialkyldithiophosphates. The phosphate ester is preferably triphenyl phosphate (TPP) or tricresyl phosphate (TCP). The thiophosphate is preferably triphenyl phosphorothioate (TPPT). As the sulfide compound, a monosulfide compound is preferably used from the viewpoint that the stability of the refrigerating machine oil is ensured and the deterioration of copper frequently used in the refrigeration equipment can be suppressed.

  The refrigerating machine oil preferably further contains an antioxidant among other additives. Antioxidants include di-tert. Examples thereof include phenolic compounds such as butyl-p-cresol and amine compounds such as alkyldiphenylamine.

  The refrigerating machine oil preferably further contains, among other additives, a friction modifier, an extreme pressure agent, a rust inhibitor, a metal deactivator, and an antifoaming agent. Examples of the friction modifier include aliphatic amines, aliphatic amides, aliphatic imides, alcohols and esters. Examples of extreme pressure agents include sulfurized olefins and sulfurized fats and oils. Examples of the rust preventive agent include esters or partial esters of alkenyl succinic acid. Examples of the metal deactivator include benzotriazole and benzotriazole derivatives. Examples of antifoaming agents include silicone compounds and polyester compounds.

  The refrigerating machine oil may further contain an additive (acid additive) having an acid value of 0.01 mg / KOH or more, 1 mg / KOH or more, 10 mg / KOH or more, 50 mg / KOH or more, or 100 mg / KOH or more. Good. The acid value of the acidic additive may be, for example, 500 mg / KOH or less, 400 mg / KOH or less, or 200 mg / KOH or less. The acid value in the present invention means an acid value measured according to JIS K2501: 2003.

  The content of the acidic additive may be, for example, 0.001% by mass or more and 0.01% by mass or more based on the total amount of the refrigerating machine oil, and may be 5% by mass or less, 2% by mass or less, or 1% by mass or less. It's okay. In the refrigerating machine oil according to this embodiment, stability is improved even when an acidic additive is contained.

  The acidic additive may be, for example, an acidic phosphorus compound (acidic phosphorus wear inhibitor), and specifically may be an acidic phosphate compound, an acidic phosphite compound, or the like. Examples of the acidic phosphate compound include acidic phosphate esters and amine salts of the acidic phosphate esters. Examples of the acidic phosphite compound include acidic phosphites and amine salts of the acidic phosphites.

  Examples of acidic phosphate esters include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate, monododecyl Acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid phosphate, dipentyl acid , Dihexyl reed Dophosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl acid, dipentadecyl acid Examples include hexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, and the like.

  The amine salt of the acidic phosphate ester may be, for example, a salt of the above acidic phosphate ester and an alkylamine having 1 to 24 carbon atoms. Alkylamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctyl Examples include amine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine and the like.

  Acid phosphites include di-n-butyl hydrogen phosphite, di-2-ethylhexyl hydrogen phosphite, didecyl hydrogen phosphite, dilauryl hydrogen phosphite, distearyl hydrogen phosphite, geo Examples include rail hydrogen phosphite and diphenyl hydrogen phosphite. The amine salt of acidic phosphite may be, for example, a salt of the above acidic phosphite and an alkylamine having 1 to 24 carbon atoms, and the alkylamine may be the above alkylamine.

Kinematic viscosity at 40 ° C. of the refrigerating machine oil is preferably ^{3 mm} 2 / s or more, more preferably ^{4 mm} 2 / s or more, may be even more preferably at ^{5 mm} 2 / s or more. Kinematic viscosity at 40 ° C. of the refrigerating machine oil is preferably 1000 mm ² / s or less, more preferably 500 mm ² / s or less, more preferably may be at 400 mm ² / s or less. The kinematic viscosity at 100 ° C. of the refrigerating machine oil may be preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more. The kinematic viscosity at 100 ° C. of the refrigerating machine oil may be preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less.

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

The volume resistivity of the refrigerating machine oil is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and further preferably 1.0 × 10 ¹¹ Ω · m or more. It's okay. In particular, when it is used for a hermetic refrigerator, it is preferable that it has high electrical insulation. The volume resistivity in the present invention means a volume resistivity at 25 ° C. measured according to JIS C2101: 1999.

  The water content of the refrigeration oil is 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 refrigeration oil. In particular, when it is used for a closed type refrigerator, it is preferable that the water content is small from the viewpoint of the influence on the thermal / chemical stability and electrical insulation of the refrigerator oil.

  The acid value (initial acid value) of the refrigerating machine oil may be, for example, 0.02 mgKOH / g or more, 0.03 mgKOH / g or more, or 0.05 mgKOH / g or more. In the refrigerating machine oil according to the present embodiment, stability is improved even when the acid value is likely to rise such that the initial acid value is in the above range. The acid value (initial acid value) of the refrigerating machine oil may be, for example, 0.2 mgKOH / g or less, or 0.1 mgKOH / g or less. The acid value (initial acid value) of the refrigerating machine oil may be less than 0.02 mg KOH / g (for example, 0.00 mg KOH / g) or 0.02 mg KOH / g or less. In this case, the refrigeration according to the present embodiment is also possible. It goes without saying that the formula for machine oil can be applied.

  The ash content of the refrigerating machine oil is preferably 100 ppm or less, more preferably 50 ppm or less, from the viewpoint of increasing the thermal and chemical stability of the refrigerating machine oil and suppressing the generation of sludge and the like. The ash content in this invention means the ash content measured based on JISK2272: 1998.

  The refrigerating machine oil according to the present embodiment is used together with a refrigerant. The working fluid composition for a refrigerator according to the present embodiment contains the refrigerator oil according to the present embodiment and a refrigerant. Such refrigerants include saturated fluorinated hydrocarbon refrigerants, unsaturated fluorinated hydrocarbon refrigerants, hydrocarbon refrigerants, fluorinated ether refrigerants such as perfluoroethers, bis (trifluoromethyl) sulfide refrigerants, and trifluoroiodinated. Examples include methane refrigerant and natural refrigerants such as ammonia and carbon dioxide.

  The saturated fluorinated hydrocarbon refrigerant is preferably a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms. Specifically, difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1-difluoroethane (R152a), fluoroethane (R161), 1,1,1,2,3,3,3-heptafluoropropane ( R227ea), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1,3,3,3-hexafluoropropane (R236fa), 1,1,1,3,3 -Pentafluoropropane (R245fa) and 1,1,1,3,3-pentafluorobutane (R365mfc), or a mixture of two or more of these Thing, and the like. Of these, difluoromethane (R32) is preferably used.

  The saturated fluorinated hydrocarbon refrigerant is appropriately selected from the above depending on the application and required performance. For example, R32 alone; R23 alone; R134a alone; R125 alone; R134a / R32 = 60 to 80% by mass / 40 R32 / R125 = 40-70 mass% / 60-30 mass% mixture; R125 / R143a = 40-60 mass% / 60-40 mass% mixture; R134a / R32 / R125 = 60 Mixture of mass% / 30 mass% / 10 mass%; R134a / R32 / R125 = 40-70 mass% / 15-35 mass% / 5-40 mass% mixture; R125 / R134a / R143a = 35-55 mass% Preferred examples include / 1-15% by mass / 40-60% by mass. More specifically, a mixture of R134a / R32 = 70/30% by mass; a mixture of R32 / R125 = 60/40% by mass; a mixture of R32 / R125 = 50/50% by mass (R410A); R32 / R125 = 45 / 55 wt% mixture (R410B); R125 / R143a = 50/50 wt% mixture (R507C); R32 / R125 / R134a = 30/10/60 wt% mixture; R32 / R125 / R134a = 23/25 / 52 mass% mixture (R407C); R32 / R125 / R134a = 25/15/60 mass% mixture (R407E); R125 / R134a / R143a = 44/4/52 mass% mixture (R404A), etc. be able to.

  The unsaturated fluorinated hydrocarbon (HFO) refrigerant is preferably a fluoropropene having 3 to 5 fluorine atoms, more preferably 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), or a mixture of two or more thereof. The unsaturated fluorinated hydrocarbon refrigerant is preferably one or more selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf from the viewpoint of refrigerant physical properties.

  The hydrocarbon refrigerant is preferably a hydrocarbon having 1 to 5 carbon atoms, specifically, methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, It may be 2-methylbutane, normal pentane or a mixture of two or more thereof. The hydrocarbon refrigerant is preferably a hydrocarbon refrigerant which is gaseous at 25 ° C. and 1 atm, more preferably propane, normal butane, isobutane, 2-methylbutane or a mixture thereof.

  Refrigerator oil is usually present in the form of a working fluid composition for a refrigerator mixed with a refrigerant in a refrigerator. The content of the refrigerating machine oil in the working fluid composition for a refrigerating machine is preferably 1 to 500 parts by mass, more preferably 2 to 400 parts by mass with respect to 100 parts by mass of the refrigerant.

  The refrigerating machine oil and the working fluid composition for the refrigerating machine according to the present embodiment include an air conditioner having a reciprocating or rotating hermetic compressor, a refrigerator, an open type or a sealed car air conditioner, a dehumidifier, a water heater, and a freezer. It is preferably used for a refrigerator having a refrigerator, a refrigerator, a vending machine, a showcase, a chemical plant, a centrifugal compressor, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to an Example.

A base oil having the composition shown in Table 1 (mass%, base oil total amount standard) was prepared using the base oil shown below.
[Base oil]
Base oil a: an ester intermediate of neopentyl glycol (1 mol), 1,4-butanediol (0.2 mol) and adipic acid (2 mol), 3,5,5-trimethylhexanol (1 mol) In the complex ester, most of the remaining unreacted product was removed by distillation (acid value <0.01 mg KOH / g, hydroxyl value 20 mg KOH / g, Mn: 1210, Mw: 2140, Mw / Mn: 1.7, 40 ° C. kinematic viscosity: 150 mm ² / s, 100 ° C. kinematic viscosity: 18.4 mm ² / s, viscosity index: 138)
Base oil b: polyol ester of pentaerythritol and 2-methylpropanoic acid / 3,5,5-trimethylhexanoic acid (molar ratio: 0.4 / 0.6) (acid value <0.01 mgKOH / g, hydroxyl value) <1 mg KOH / g, 40 ° C. kinematic viscosity: 68 mm ² / s, 100 ° C. kinematic viscosity: 8.2 mm ² / s, viscosity index: 84)
Base oil c: polyol ester of pentaerythritol and 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid (molar ratio: 0.5 / 0.5) (acid value <0.01 mgKOH / g, hydroxyl value) <1 mg KOH / g, 40 ° C. kinematic viscosity: 68 mm ² / s, 100 ° C. kinematic viscosity: 8.3 mm ² / s, viscosity index: 88)
Base oil d: polyol ester of pentaerythritol and n-pentanoic acid / 3,5,5-trimethylhexanoic acid (molar ratio: 0.4 / 0.6) (acid value <0.01 mg KOH / g, hydroxyl value < 1 mg KOH / g, 40 ° C. kinematic viscosity: 51 mm ² / s, 100 ° C. kinematic viscosity: 7.4 mm ² / s, viscosity index: 105)
Base oil e: ester intermediate of neopentyl glycol (1 mol), 1,4-butanediol (0.3 mol) and adipic acid (2.4 mol) and 3,5,5-trimethylhexanol (2. 5 mol), which is obtained by removing most of the remaining unreacted product by distillation (acid value <0.01 mg KOH / g, hydroxyl value 30 mg KOH / g, Mn: 980, Mw: 1570, Mw / Mn: 1.6,40 ° C. kinematic viscosity: 67.8mm ² / s, 100 ℃ kinematic viscosity: 10.6 mm ² / s, viscosity index: 145)
Base oil f: an ester intermediate of neopentyl glycol (1 mol), 1,4-butanediol (0.2 mol) and adipic acid (1.7 mol) and 3,5,5-trimethylhexanol (0. 8 mol) which is a complex ester obtained by removing most of the remaining unreacted product by distillation (acid value <0.01 mg KOH / g, hydroxyl value 25 mg KOH / g, Mn: 1340, Mw: 2370, Mw / Mn: 1.8, 40 ° C. kinematic viscosity: 220 mm ² / s, 100 ° C. kinematic viscosity: 24.2 mm ² / s, viscosity index: 138)

Refrigerating machine oil having the composition shown in Tables 2 to 5 (% by mass, based on the total quantity of refrigerating machine oil) was prepared using the base oils AD and the following additives.
[Additive]
A1: Glycidyl-dimethyloctanoate (the following formula (A1))
B1: 2-ethylhexyl glycidyl ether (the following formula (B1))
B2: 4-tert-butylphenylglycidyl ether (the following formula (B2))

  In addition to the above-described base oil and additives, in addition to the above base oils and additives, an amine salt of an acidic phosphate (acid value: 140 mgKOH / g) 0.05% by mass, tricresyl phosphate (acid value ≦ 0.01 mg KOH / g) 0.5% by mass and 2,6-di-tert. -0.3% by mass of butyl-p-cresol (both based on the total amount of refrigerating machine oil) was added.

  For each refrigerating machine oil, first, the acid value (pre-test acid value) was measured according to JIS K2501: 2003. Subsequently, the stability test at the time of refrigerant | coolant mixing was implemented about each refrigerator oil based on JISK2211: 2009 (autoclave test). That is, 30 g of refrigerating machine oil whose water content was adjusted to 1000 ppm was weighed in an autoclave, and the catalyst (iron, copper, aluminum wire, each outer diameter 1.6 mm × length 50 mm) and difluoromethane (R32) refrigerant 30 g. And heated at 175 ° C. for 168 hours. About each refrigerating machine oil after a test, based on JISK2501: 2003, the acid value (acid value after a test) was measured. The increase in acid value was calculated from the obtained acid value before test and acid value after test. The results are shown in Tables 2-5.

  As is clear from Tables 2 to 5, when a specific lubricating base oil and two specific types of epoxy compounds are used in combination, an excellent synergistic effect is obtained in terms of improving the stability of the refrigerating machine oil.

Claims (2)

A lubricating base oil containing a complex ester of at least one selected from the group consisting of monohydric alcohols having 4 to 18 carbon atoms and monohydric fatty acids having 4 to 18 carbon atoms and an ester intermediate, wherein the ester The intermediate contains at least one selected from the group consisting of polyhydric alcohols containing at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol, and polybasic acids having 6 to 12 carbon atoms. A lubricating base oil that is an ester with a polybasic acid;
A glycidyl ester type epoxy compound represented by the following formula (A);
A glycidyl ether type epoxy compound represented by the following formula (B);
Refrigerating machine oil containing.

[In the formula (A), R ^a represents an aryl group, an alkyl group or an alkenyl group. ]

[In the formula (B), R ^b represents an aryl group or an alkyl group. ]   The refrigerating machine oil according to claim 1, further comprising an acidic phosphorus compound.