JP2020158786A - Anti-wear additive, refrigerating machine oil and hydraulic fluid composition for refrigerating machine - Google Patents

Abstract

To provide a refrigerating machine oil containing an anti-wear additive capable of improving the wear resistance of a sliding member.SOLUTION: There is provided a refrigerating machine oil comprising: a base oil only consisting of at least one selected from the group consisting of a polyol ester comprising at least one polyhydric alcohol selected from the group consisting of neopentyl glycol and the like and a fatty acid having 4 to 20 carbon atoms, and a complex ester; and an anti-wear additive that is at least one selected from the group consisting of a silicone oil that is dimethylpolysiloxane, a modified silicone oil with the end of the main chain of dimethylpolysiloxane modified with polyalkylene glycol, and a fluorinated silicone oil with side chains of dimethylpolysiloxane modified to fluoropolyether groups, wherein the content of the base oil is 95 mass% or more based on the total amount of the refrigerating machine oil, and the content of the anti-wear additive is 0.1 mass ppm or more and 500 mass ppm or less based on the total amount of the refrigerating machine oil.SELECTED DRAWING: None

Description

The present invention relates to wear resistant additives, refrigerating machine oils and working fluid compositions for refrigerating machines.

Refrigerators such as refrigerators, car air conditioners, room air conditioners, and vending machines are equipped with a compressor for circulating the refrigerant in the refrigeration cycle. Then, the compressor is filled with refrigerating machine oil for lubricating the sliding member. In general, refrigerating machine oils contain base oils and additives that are formulated according to the desired properties. As the additive, for example, a sulfur-based abrasion inhibitor, a phosphorus-based abrasion inhibitor, an alcohol-based abrasion inhibitor, and a polyhydric alcohol partial ester-based abrasion added to improve the abrasion resistance of sliding members in a refrigerator. Inhibitors, polyhydric alcohol partial ether-based anti-wear agents, etc. are known (see Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 3-243697 Japanese Unexamined Patent Publication No. 2001-200285 Japanese Unexamined Patent Publication No. 2011-178990

An object of the present invention is to provide a wear-resistant additive capable of improving the wear resistance of a sliding member, and a refrigerator oil and a refrigerator working fluid composition containing the same.

The present invention provides an abrasion resistant additive containing at least one selected from the group consisting of silicone oil, modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and fluorinated silicone oil.

The present invention also provides a refrigerating machine oil containing a base oil and the above-mentioned wear-resistant additive.

The content of the wear-resistant additive is preferably 0.1 mass ppm or more and 500 mass ppm or less based on the total amount of refrigerating machine oil.

The base oil preferably contains an ester of a fatty acid and an alcohol containing a polyhydric alcohol.

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

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

According to the present invention, it is possible to provide a wear-resistant additive capable of improving the wear resistance of a sliding member, and a refrigerator oil and a refrigerator working fluid composition containing the same.

The wear-resistant additive according to the present embodiment is at least one selected from the group consisting of silicone oil, modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and fluorinated silicone oil (hereinafter, "" Also referred to as "predetermined silicone oil").

That is, a composition containing at least one selected from the group consisting of silicone oil, modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and fluorinated silicone oil is suitable as an abrasion resistant additive. Used for. Further, a composition containing at least one selected from the group consisting of silicone oil, modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and fluorinated silicone oil is produced as an abrasion resistant additive. Is preferably used for.

Examples of the silicone oil include dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane. Among these, dimethylpolysiloxane is particularly preferable because it is highly versatile and easily available.

As the modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, the end of the main chain of dimethylpolysiloxane is modified with polypropylene glycol, and the end of the main chain of dimethylpolysiloxane is modified with polyethylene glycol. A modified modified silicone oil is exemplified.

Examples of the fluorinated silicone oil include fluorinated silicone oil in which the side chain of dimethylpolysiloxane is modified to a fluoroalkyl group, and fluorinated silicone oil in which the side chain of dimethylpolysiloxane is modified to a fluoropolyether group.

The kinematic viscosity of the predetermined silicone oil is not particularly limited. The kinematic viscosity of the predetermined silicone oil at 25 ° C. is preferably 50 mm ² / s or more, more preferably 100 mm ² / s or more, still more preferably 300 mm ² / s or more, from the viewpoint of excellent wear resistance. There also is preferably 100,000 mm ² / s or less, more preferably 40000 mm ² / s, more preferably not more than 10000 mm ² / s.

The kinematic viscosity of the predetermined silicone oil at 25 ° C. is preferably 100 mm ² because, as another aspect, the abrasion resistance effect per addition amount is high, and the dispersibility in the lubricating oil and the storage stability for a long period of time are excellent. / s or higher, more preferably 500 mm ² / s or more, more preferably 5000 mm ² / s or more, particularly preferably 20000 mm ² / s or more, and preferably 100,000 mm ² / s or less, more preferably 80000Mm ² / s Below, it is more preferably 60,000 mm ² / s or less.

The wear-resistant additive may consist of a predetermined silicone oil, or may further contain other components in addition to the predetermined silicone oil.

The wear-resistant additive according to the present embodiment is preferably used for lubricating oils that require improved wear resistance, and is particularly preferably used for refrigerating machine oils.

The refrigerating machine oil according to the present embodiment contains at least one selected from the group consisting of a base oil, a silicone oil, a modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and a fluorinated silicone oil. Contains an abrasion resistant additive. The refrigerating machine oil according to the present embodiment includes an embodiment containing a base oil and an abrasion resistant additive according to the present embodiment.

As the base oil, hydrocarbon oil, oxygen-containing oil and the like can be used. Examples of the hydrocarbon oil include mineral oil-based hydrocarbon oils and synthetic hydrocarbon oils. Examples of oxygen-containing oils include esters, polyvinyl ethers, polyalkylene glycols, carbonates, ketones, polyphenyl ethers, silicones, polysiloxanes, and perfluoro ethers. The base oil preferably contains an oxygen-containing oil, and more preferably contains an ester.

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

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

Examples of the ester include aromatic esters, dibasic acid esters, polyol esters, complex esters, carbonic acid esters, and mixtures thereof. As the ester, an ester (polypoly ester, complex ester) of a fatty acid and an alcohol containing a polyhydric alcohol is preferable from the viewpoint of more effectively exerting the wear resistance of the abrasion resistant agent according to the present embodiment. Is more preferable.

The content of the base oil is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, based on the total amount of the refrigerating machine oil base oil. The ester content of the fatty acid and the alcohol containing the polyhydric alcohol is preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, based on the total amount of refrigerating machine oil. The content of the complex ester is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more based on the total amount of refrigerating machine oil.

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

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

Specific examples of the fatty acid having 4 to 20 carbon atoms include linear or branched butanoic acid, linear or branched pentadecanoic acid, linear or branched hexanoic acid, and linear or branched. Linear heptanic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched Linear or branched dodecanoic acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched Examples include linear or branched octadecanoic acid, linear or branched nonadecanic acid, and linear or branched valeric acid. More specifically, fatty acids having a branch at the α-position and / or β-position are preferable, and 2-methylpropanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-Methylbutanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethylhexadecanoic acid and the like are more preferable, and 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are further preferable. preferable.

The fatty acid may contain a fatty acid other than the fatty acid having 4 to 20 carbon atoms. As the fatty acid other than the fatty acid having 4 to 20 carbon atoms, for example, a fatty acid having 21 to 24 carbon atoms may be contained. Specific examples thereof include linear or branched henic acid, linear or branched docosanoic acid, linear or branched tricosanoic acid, linear or branched tetracosanoic acid, and the like.

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

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

The complex ester obtained by the method (b) above is slightly inferior in stability to the complex ester obtained by the method (a) above because a relatively strong acid is produced when hydrolyzed when used as a refrigerating machine oil. There is a tendency. As the complex ester in the present embodiment, the complex ester obtained by the method (a) above, which has higher stability, is preferable.

As the complex ester, at least one selected from polyhydric alcohols having 2 to 4 hydroxyl groups, at least one selected from polybasic acids having 6 to 12 carbon atoms, and monovalents having 4 to 18 carbon atoms. It is preferably an ester synthesized from at least one selected from alcohols and monovalent fatty acids having 2 to 12 carbon atoms.

Examples of the polyhydric alcohol having 2 to 4 hydroxyl groups include neopentyl glycol, trimethylolpropane, pentaerythritol and the like. As polyhydric alcohols having 2 to 4 hydroxyl groups, neopentyl glycol and trimethylol propane are selected from the viewpoint of ensuring a suitable viscosity when a complex ester is used as a base oil and obtaining good low temperature characteristics. Neopentyl glycol is preferable, and neopentyl glycol is more preferable from the viewpoint of being able to adjust the viscosity widely.

From the viewpoint of further improving lubricity, the polyhydric alcohol constituting the complex ester has 2 to 10 carbon atoms other than neopentyl glycol in addition to the polyhydric alcohol having 2 to 4 hydroxyl groups. It is preferable to further contain the dihydric alcohol of. Dihydric alcohols having 2 to 10 carbon atoms other than neopentyl glycol include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, 2-methyl-1,3-propanediol, and 3-methyl-1,5. -Pentanediol, 2,2-diethyl-1,3-pentanediol and the like can be mentioned, and butanediol having a well-balanced characteristics of the synthesized base oil is preferable. Examples of butanediol include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 2,3-butanediol, but 1,3-butanediol can be obtained from the viewpoint of obtaining good characteristics. Butanediol and 1,4-butanediol are more preferable. The divalent alcohol having 2 to 10 carbon atoms other than neopentyl glycol is preferably 1.2 mol or less, preferably 0.8 mol or less, with respect to 1 mol of the polyhydric alcohol having 2 to 4 hydroxyl groups. It is more preferable that the amount is 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. Among these, adipic acid and sebacic acid are preferable, and adipic acid is more preferable, from the viewpoint of excellent balance of characteristics of the synthesized ester and easy availability. The polybasic acid having 6 to 12 carbon atoms is preferably 0.4 mol to 4 mol, preferably 0.5 mol to 3 mol, with respect to 1 mol of the polyhydric alcohol having 2 to 4 hydroxyl groups. It is more preferably present, and more preferably 0.6 mol to 2.5 mol.

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

Examples of monovalent fatty acids having 2 to 12 carbon atoms include linear or branched heptanoic acid, linear or branched propanoic acid, linear or branched butyric acid, linear or branched pentanoic acid, and linear or branched hexane. Examples include acids, linear or branched heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched dodecanoic acid and the like. The monovalent fatty acid having 2 to 12 carbon atoms is preferably a monovalent fatty acid having 8 to 10 carbon atoms, and among these, 2-ethylhexanoic acid and 3,5,5-trimethyl are more preferable from the viewpoint of low temperature characteristics. Hexanoic acid.

The content of the wear-resistant additive is preferably 0.1 mass ppm or more, more preferably 1 mass ppm or more, still more preferably 3 mass ppm or more, based on the total amount of refrigerating machine oil, from the viewpoint of improving lubricity in a refrigerant atmosphere. It is ppm or more, particularly preferably 5 mass ppm or more. The content of the wear-resistant additive is preferably 500 mass ppm or less, more preferably 100 mass ppm or less, still more preferably 50 mass ppm or less, based on the total amount of refrigerating machine oil, from the viewpoint of precipitation in a refrigerant atmosphere. .. A wear-resistant additive containing a predetermined silicone oil exhibits excellent wear resistance with a smaller content than conventional wear-resistant additives (for example, anti-wear agents described in Patent Documents 1 to 3).

The refrigerating machine oil may further contain other additives in addition to the wear-resistant additive according to the present embodiment. Examples of other additives include antioxidants, friction modifiers, wear inhibitors other than the wear resistant additives according to the present embodiment, extreme pressure agents, rust inhibitors, metal inactivating agents and the like.

The kinematic viscosity of the refrigerating machine oil at 40 ° C. is preferably 3 mm ² / s or more, more preferably 4 mm ² / s or more, further preferably 5 mm ² / s or more, and preferably 1000 mm ² / s or less, more preferably. Can be 500 mm ² / s or less, more preferably 400 mm ² / s or less. The kinematic viscosity of the refrigerating machine oil at 100 ° C. is preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more, and preferably 100 mm ² / s or less, more preferably 50 mm ² / s or less. Can be done.

The pour point of the refrigerating machine oil can be preferably −10 ° C. or lower, more preferably −20 ° C. or lower.

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. be able to. In particular, when used for a closed-type refrigerator, it is preferable to have high electrical insulation. The volume resistivity in the present invention means a value at 25 ° C. measured according to JIS C2101: 1999 “Electrical Insulation Oil Test Method”.

The water content of the refrigerating machine oil can be preferably 200 ppm or less, more preferably 100 ppm or less, still more preferably 50 ppm or less based on the total amount of the refrigerating machine oil. In particular, when used for a closed-type refrigerator, it is preferable that the water content is low from the viewpoint of affecting the thermal / chemical stability and electrical insulation of the refrigerator oil.

The acid value of the refrigerating machine oil can be preferably 1.0 mgKOH / g or less, more preferably 0.1 mgKOH / g or less, from the viewpoint of preventing corrosion to the metal used in the refrigerator or piping. The acid value in the present invention means an acid value measured in accordance with JIS K2501: 2003 "Petroleum products and lubricating oil-neutralization value test method".

The ash content of the refrigerating machine oil can be preferably 100 ppm or less, more preferably 50 ppm or less, from the viewpoint of enhancing the thermochemical stability of the refrigerating machine oil and suppressing the generation of sludge and the like. The ash content in the present invention means the ash content measured in accordance with JIS K2272: 1998 "Crude oil and petroleum products-ash content and sulfate ash content test method".

The working fluid composition for a refrigerator according to the present embodiment is selected from the group consisting of a base oil, a silicone oil, a modified silicone oil in which the end of the main chain of the silicone oil is modified with polyalkylene glycol, and a fluorinated silicone oil. It contains refrigerating machine oil containing at least one wear additive and a refrigerant. The working fluid composition for a refrigerator according to the present embodiment includes an embodiment containing the refrigerating machine oil according to the present embodiment and a refrigerant.

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

Examples of the saturated fluorinated hydrocarbon refrigerant include saturated fluorinated hydrocarbons 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 (R134a) 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 mixtures of two or more thereof.

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. ~ 20% by weight mixture; R32 / R125 = 40 ~ 70% by weight / 60 ~ 30% by weight mixture; R125 / R143a = 40-60% by weight / 60-40% by weight mixture; R134a / R32 / R125 = 60 Mixture of% by mass / 30% by mass / 10% by mass; mixture of R134a / R32 / R125 = 40 to 70% by mass / 15 to 35% by mass / 5 to 40% by mass; R125 / R134a / R143a = 35 to 55% by mass A mixture of / 1 to 15% by mass / 40 to 60% by mass is a preferable example. 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% by mass mixture (R410B); R125 / R143a = 50/50% by mass mixture (R507C); R32 / R125 / R134a = 30/10/60% by mass mixture; R32 / R125 / R134a = 23/25 / 52% by mass mixture (R407C); R32 / R125 / R134a = 25/15/60% by mass mixture (R407E); R125 / R134a / R143a = 44/4/52% by mass mixture (R404A) and the like are used. be able to.

As the unsaturated fluorinated hydrocarbon (HFO) refrigerant, fluoropropene having a fluorine number of 3 to 5 is preferable, and 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. It is preferably one or a mixture of two or more of 3-trifluoropropene (HFO-1243zf). From the viewpoint of the physical properties of the refrigerant, one or more selected from HFO-1225ye, HFO-1234ze and HFO-1234yf are preferable.

As the hydrocarbon refrigerant, hydrocarbons having 1 to 5 carbon atoms are preferable, and specifically, for example, methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, and the like. Examples include 2-methylbutane, normalpentane or a mixture of two or more thereof. Among these, those having a gas at 25 ° C. and 1 atm are preferably used, and propane, normal butane, isobutane, 2-methylbutane or a mixture thereof is preferable.

The refrigerating machine oil according to the present embodiment usually exists in a refrigerating machine in the form of a working fluid composition for a refrigerating machine mixed with a refrigerant. The content of the refrigerating machine oil in the working fluid composition for a refrigerating machine according to the present embodiment is not particularly limited, but is preferably 1 part by mass or more, more preferably 2 parts by mass or more, based on 100 parts by mass of the refrigerant. Further, it is preferably 500 parts by mass or less, more preferably 400 parts by mass or less.

The refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment include an air conditioner having a reciprocating or rotary sealed compressor, a refrigerator, an open or closed car air conditioner, a dehumidifier, a water heater, and a freezer. , Refrigerator / refrigerator, vending machines, showcases, cooling devices for chemical plants, etc., those with centrifugal compressors, etc. are preferably used.

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

As the base oil, esters (A-1) to (A-5) produced by the procedure shown below were used.
[Manufacturing of ester (A-1)]
Neopentyl glycol, 1,4-butanediol and adipic acid are reacted at neopentyl glycol / 1,4-butanediol / adipic acid = 1 / 0.3 / 2.4 (molar ratio) to form an ester intermediate. Got Further, 3,5,5-trimethylhexanol is further reacted with this ester intermediate at neopentyl glycol / 3,5,5-trimethylhexanol = 1 / 2.5 (molar ratio) without using a catalyst or a solvent. Then, the remaining unreacted material was removed by distillation. Then, in the final step, an adsorption treatment (white clay treatment) was carried out to remove a trace amount of impurities to obtain an ester (kinematic viscosity at 40 ° C., 67.8 mm ² / s, viscosity index 145, pour point −50 ° C.).

[Manufacturing of ester (A-2)]
Trimethylolpropane and adipic acid were reacted at trimethylolpropane / adipic acid = 1 / 2.4 (molar ratio) to obtain an ester intermediate. This ester intermediate was further reacted with 2-ethylhexanol so that trimethylolpropane / 2-ethylhexanol = 1 / 1.9 (molar ratio), and the remaining unreacted material was removed by distillation. Then, in the final step, an adsorption treatment (white clay treatment) was carried out to remove a trace amount of impurities to obtain an ester (kinematic viscosity at 40 ° C., 68.8 mm ² / s, viscosity index 120, pour point −55 ° C.).

[Example 3: Production of ester (A-3)]
Neopentyl glycol and adipic acid were reacted at neopentyl glycol / adipic acid = 1 / 0.8 (molar ratio) to obtain an ester intermediate. This ester intermediate was further reacted with 3,5,5-trimethylhexanoic acid so that neopentyl glycol / 3,5,5-trimethylhexanoic acid = 1 / 0.5 (molar ratio), and the residue remained. The unreacted material was removed by distillation. Then, in the final step, an adsorption treatment (white clay treatment) was carried out to remove a trace amount of impurities to obtain an ester (kinematic viscosity 71.5 mm ² / s, viscosity index 114, pour point −55 ° C.).

[Example 4: Production of ester (A-4)]
Neopentyl glycol, 1,4-butanediol and adipic acid are reacted with neopentyl glycol / 1,4-butanediol / adipic acid = 1 / 0.1 / 1.2 (molar ratio) to form an ester intermediate. Got Further, 3,5,5-trimethylhexanol was further reacted with this ester intermediate at neopentyl glycol / 3,5,5-trimethylhexanol = 1 / 0.3 (molar ratio) without using a catalyst or a solvent. Then, the remaining unreacted material was removed by distillation. Then, in the final step, an adsorption treatment (white clay treatment) was carried out to remove a trace amount of impurities to obtain an ester (kinematic viscosity at 40 ° C., 275.9 mm ² / s, viscosity index 117, pour point −35 ° C.).

[Example 5: Production of ester (A-5)]
Neopentyl glycol and adipic acid were reacted at neopentyl glycol / adipic acid = 1 / 0.8 (molar ratio) to obtain an ester intermediate. Further 3,5,5-trimethylhexanoic acid is added to this ester intermediate at neopentyl glycol / 3,5,5-trimethylhexanoic acid = 1 / 0.3 (molar ratio) without using a catalyst or solvent. And the remaining unreacted material was removed by distillation. Then, in the final step, an adsorption treatment (white clay treatment) was carried out to remove a trace amount of impurities to obtain an ester (kinematic viscosity at 40 ° C., 300 mm ² / s, viscosity index 114, pour point −35 ° C.).

In addition, the following esters (b-1) to (b-5) were used as the base oil.
(B-1) Pentaerythritol mixed with 2-methylpropanoic acid and 3,5,5-trimethylhexanoic acid (2-methylpropanoic acid: 3,5,5-trimethylhexanoic acid = 1: 1 (mass ratio) )) Ester with mixed acid (kinematic viscosity at 40 ° C. 69.4 mm ² / s, viscosity index 95, flow point −45 ° C.)
(B-2) Dipentaerythritol and a mixed acid of normal butanoic acid and 3,5,5-trimethylhexanoic acid (normal butanoic acid: 3,5,5-trimethylhexanoic acid = 7: 3 (mass ratio)) Ester with mixed acid (kinematic viscosity at 40 ° C. 68.1 mm ² / s, viscosity index 90, flow point −45 ° C.)
(B-3) Ester of trimethylolpropane and oleic acid (kinematic viscosity at 40 ° C. 50.3 mm ² / s, viscosity index 176)
(B-4) Ester of pentaerythritol, pentanoic acid and 3,5,5-trimethylhexanoic acid (kinematic viscosity at 40 ° C. 31.4 mm ² / s, viscosity index 118, pour point <-55 ° C.)
(B-5) Ester of pentaerythritol, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid (kinematic viscosity at 40 ° C. 68.3 mm ² / s, viscosity index 87, pour point −45 ° C.)

The kinematic viscosity and viscosity index of the esters (A-1) to (A-5) and (b-1) to (b-5) were measured according to JIS K2283: 2000. The pour point was measured according to JIS K2269: 1987. Further, the esters (b-1) to (b-5) were also subjected to an adsorption treatment (white clay treatment) in the final step of production to remove trace impurities.

The following additives 1 to 4 were used as abrasion resistant additives. Incidentally, the kinematic viscosity at 25 ° C. of additives 1 to 4 were in the ranges of 100mm ² / s~50000mm ² / s.
Additive 1: Dimethylpolysiloxane (kinematic viscosity at 25 ° C: 30,000 mm ² / s)
Additive 2: Modified silicone oil additive in which the end of the main chain of dimethylpolysiloxane is modified with polyalkylene glycol 3: Modified silicone oil additive in which the end of the main chain of dimethylpolysiloxane is modified with ester 4: Dimethylpolysiloxane Fluorinated silicone oil with side chains modified to fluoropolyether groups

The above base oil and additives were blended in the blending ratios shown in Tables 1 to 6 to prepare a test oil. The following wear resistance tests were performed on each test oil. The results are shown in Tables 1-6. Incidentally, kinematic viscosity of 100 mm ² / ^s at 25 ℃, 1000mm 2 / s, for even dimethylpolysiloxane 50,000 mm ² / s, at ranges of content 1 to 50 mass ppm (sample oil total amount), additives The same result as when 1 is used can be obtained.

(Abrasion resistance test)
Refrigerant pressure fluctuation wear resistance test is performed using a high-pressure atmospheric friction tester (rotary sliding method of rotating vane material and fixed disc material) manufactured by Shinko Koki Co., Ltd., which can create a refrigerant atmosphere similar to that of an actual compressor. It was. The test conditions were one of the following wear resistance tests-(1) to (6) for each type of evaluation refrigerant.
Abrasion resistance test- (1): R134a is used as the refrigerant, and the pressure inside the test container is 1.6 MPa.
Abrasion resistance test- (2): R410A is used as the refrigerant, and the pressure inside the test container is 1.6 MPa.
Abrasion resistance test- (3): R32 is used as the refrigerant, and the pressure inside the test container is 1.6 MPa.
Abrasion resistance test- (4): HFO-1234yf was used as the refrigerant, and the pressure inside the test container was 1.6 MPa.
Abrasion resistance test- (5): n-hexane (20% by volume is mixed with refrigerating machine oil. Hydrocarbon refrigerants such as R290 are used as a substitute due to safety concerns), and the pressure inside the test vessel is Pressure slightly higher than normal pressure.
Abrasion resistance test- (6): CO ₂ is used as the refrigerant, and the pressure inside the test container is 1.6 MPa.

Abrasion resistance test-For all of (1) to (6), the amount of oil was 600 ml, the test temperature was 100 ° C., the rotation speed was 650 rpm, the load was 70 kgf, and the pressure inside the test vessel was 100 L / min 30 minutes after the start of the test. It was decided to lower the pressure to atmospheric pressure and continue the test for another 30 minutes in that state. It is also common that SKH-51 was used as the vane material and FC250 was used as the disc material. Since the amount of wear of the disc material is extremely small, the wear resistance was evaluated based on the wear depth of the vane material. The results are shown in Tables 1-6.

Claims (8)

At least one polyvalent selected from the group consisting of neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol and dipentaerythritol. A polyol ester consisting of an alcohol and a fatty acid having 4 to 20 carbon atoms, and a base oil consisting of at least one selected from the group consisting of a complex ester.
From the group consisting of silicone oil which is dimethylpolysiloxane, modified silicone oil in which the end of the main chain of dimethylpolysiloxane is modified with polyalkylene glycol, and fluorinated silicone oil in which the side chain of dimethylpolysiloxane is modified to a fluoropolyether group. Containing at least one selected anti-wear additive,
The content of the base oil is 95% by mass or more based on the total amount of refrigerating machine oil, and
A refrigerating machine oil having a content of the wear-resistant additive of 0.1 mass ppm or more and 500 mass ppm or less based on the total amount of the refrigerating machine oil. The refrigerating machine oil according to claim 1, which is used together with a refrigerant containing difluoromethane. The refrigerating machine oil according to claim 1 or 2, which is used together with a refrigerant containing an unsaturated fluorinated hydrocarbon refrigerant. The refrigerating machine oil according to any one of claims 1 to 3, wherein the base oil contains the polyol ester. The base oil has at least one selected from polyhydric alcohols having 2 to 4 hydroxyl groups, at least one selected from polybasic acids having 6 to 12 carbon atoms, and 4 carbon atoms as the complex ester. The refrigerating machine oil according to any one of claims 1 to 4, which contains a complex ester synthesized from at least one selected from a monohydric alcohol to 18 and a monohydric fatty acid having 2 to 12 carbon atoms. A working fluid composition for a refrigerator containing the refrigerating machine oil according to any one of claims 1 to 5 and a refrigerant. The working fluid composition for a refrigerator according to claim 6, wherein the refrigerant contains difluoromethane. The working fluid composition for a refrigerator according to claim 6 or 7, wherein the refrigerant contains an unsaturated fluorinated hydrocarbon refrigerant.