JP2844129B2 - Synthetic lubricant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic lubricating oil, and more particularly to a synthetic lubricating oil comprising a carbonate having a specific structure as a main component.
The present invention relates to a synthetic lubricating oil particularly useful as a refrigerator oil or the like.

[0002]

2. Description of the Related Art Conventionally, naphthenic mineral oils having a kinematic viscosity of 10 to 200 cSt at 40 ° C.
A paraffinic mineral oil, an alkylbenzene, a polyglycol-based oil, a mixture thereof, or a mixture of these various base oils with an additive is generally used.

On the other hand, CFC-11, CFC-12, and CFC-11 are CFC-11 refrigerants used in refrigerators.
5, HCFC-22 and the like are used.

[0004] Among these CFC-based refrigerants, CFC-1
CFCs in which all the hydrogens of hydrocarbons such as 1, CFC-12 and CFC-115 are replaced with halogens containing chlorine,
It is subject to regulations for destruction of the ozone layer. Therefore, hydrogen-containing Freon, especially HFC-134
a and non-chlorinated chlorofluorocarbons such as HFC152a are being used as substitutes for CFCs.
Has similar thermodynamic properties to CFC-12 conventionally used in many refrigerators such as home refrigerators, air conditioners, and car air conditioners, and is a promising alternative refrigerant.

Although refrigerating machine oils have various required performances, compatibility with refrigerants is extremely important in terms of lubrication and system efficiency of the refrigerating machine. However, refrigeration oils based on naphthenic mineral oils, paraffinic mineral oils, alkylbenzenes, and the like have almost no compatibility with non-chlorinated chlorofluorocarbons such as HFC-134a. In the refrigeration system, the oil return property, which is the most important, deteriorates, and the refrigerating efficiency decreases or the lubricity deteriorates, causing various practical problems such as seizure of the compressor. I can't stand it.

[0006] To solve this problem, the present inventors have proposed H
A polyglycol-based refrigerating machine oil, which has much higher compatibility with FC-134a than conventionally known refrigerating machine oils, has been previously developed and has already been filed (JP-A-1-256594, JP-A-1-256594). No. 274191). U.S. Pat. No. 4,755,316 discloses a polyglycol-based refrigerating machine oil compatible with HFC-134a.

The present inventors have found that an ester having a specific structure has excellent compatibility with non-chlorinated chlorofluorocarbons such as HFC-134a and has high electric insulation, and has previously filed a patent application. You are.

[0008] However, although the ester is excellent in various performances as described above, it is not always suitable for a device which is operated with high reliability over a long period of time, such as a refrigerator and a car air conditioner, because it is hydrolyzed. Therefore,
It has high compatibility with chlorine-based chlorofluorocarbons such as CFC-12 and HCFC-22 which are currently used.
There has been a desire for a refrigerating machine oil having high compatibility with non-chlorinated chlorofluorocarbons such as 4a and hydrolytic stability.

The present inventors have paid attention to the excellent various properties of the ester-based synthetic oil, and have repeatedly studied to develop a lubricating oil capable of meeting the above-mentioned requirements. The present inventors have found that they have excellent compatibility with hydrogen-containing Freon such as -134a and have excellent hydrolytic stability, and have completed the present invention.

[0010]

DISCLOSURE OF THE INVENTION The present invention is based on a carbonate having a specific structure as a main component, and comprises HFC-134a
It is an object of the present invention to provide a synthetic lubricating oil having excellent compatibility with hydrogen-containing chlorofluorocarbons and excellent hydrolytic stability.

[0011]

That is, the present invention provides a compound represented by the general formula:

[0012]

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Wherein X is an alkyl group, a cycloalkyl group, a residue of a neopentyl polyol having 5 to 30 carbon atoms and 2 to 8 hydroxyl groups,

[0014]

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A ¹ , A ² ,
A ³ , A ⁴ and A ⁵ may be the same or different,
Each represents an alkylene group having 2 to 4 carbon atoms, R ¹ and R ⁴ may be the same or different, each represents an alkyl group having 1 to 6 carbon atoms, and R ² , R ³ and R ⁵ are the same or different And an alkyl group, a cycloalkyl group or a C 5-30 and a hydroxyl group 2-8, respectively.
Represents the residue of a neopentyl-type polyol;
Is a number that satisfies a = 0 to 2, b = 0 to 2 and a + b = 2, and c and d are numbers that satisfies c = 0 to 2, d = 1 to 3 and c + d = 3, respectively; e = 1 to 3, f
= 1 to 5 each; l, m, n, j and k each represent an integer of 1 to 50].

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

The lubricating oil for refrigerators of the present invention has a general formula

[0018]

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The main component is a carbonate represented by the formula: In the above formula, X is an alkyl group (preferably having 1 to 12 carbon atoms), a cycloalkyl group (preferably having 5 to 12 carbon atoms), 5 to 30 carbon atoms, preferably 5 to 2 carbon atoms.
A residue of a neopentyl polyol having 1 and 2 to 8 hydroxyl groups, or a general formula

[0020]

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The group represented by A ¹ , A ² ,
A ³ , A ⁴ and A ⁵ may be the same or different,
Each represents an alkylene group having 2 to 4 carbon atoms, R ¹ and R ⁴ may be the same or different, each represents an alkyl group having 1 to 6 carbon atoms, and R ² , R ³ and R ⁵ are the same or different Each having an alkyl group (preferably having 1 to 12 carbon atoms), a cycloalkyl group (preferably having 5 to 12 carbon atoms), or a 5 to 30 carbon atoms, preferably 5 to 21 and 2 to 8 hydroxyl groups. The residue of a neopentyl type polyol is shown. A and b are a = 0 to 0, respectively.
2, a number satisfying b = 0-2 and a + b = 2, and c and d indicate numbers satisfying c = 0-2, d = 1-3 and c + d = 3, respectively. e = 1 to 3 and f = 1 to 5 represent an integer; l, m, n, j and k represent an integer of 1 to 50, respectively.

Preferred examples of the alkyl group represented by X, R ² , R ³ and R ⁵ include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group,
n-butyl group, iso-butyl group, sec-butyl group,
tert-butyl group, n-pentyl group, iso-pentyl group, neo-pentyl group, n-hexyl group, iso-
Hexyl group, n-heptyl group, iso-heptyl group, n
-Octyl group, iso-octyl group, n-nonyl group, i
so-nonyl group, n-decyl group, iso-decyl group, n
-Undecyl group, iso-undecyl group, n-dodecyl group, iso-dodecyl group and the like.Examples of preferred cycloalkyl groups include, specifically, cyclopentyl group, cyclohexyl group, cycloheptyl group, Examples include octyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl, methylcyclohexyl, ethylcyclohexyl, propylcyclohexyl, butylcyclohexyl, pentylcyclohexyl, hexylcyclohexyl, and the like.
Further, as the residue of the neopentyl type polyol having 5 to 30 carbon atoms and 2 to 8 hydroxyl groups, specifically, neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, trimethylolethane, Residues such as trimethylolpropane, trimethylolbutane, pentaerythritol, and dimers and trimers thereof are exemplified.
Carbon number 2 represented by A ¹ , A ² , A ³ , A ⁴ and A ⁵
Specific examples of the alkylene groups (1) to (4) include ethylene, propylene, trimethylene, butylene, tetramethylene, 1-methyltrimethylene, 2-methyltrimethylene, and 1,1-dimethylethylene. , 1,2
-Dimethylethylene group and the like. Examples of the alkyl group having 1 to 6 carbon atoms represented by R ¹ and R ⁴ include:
Specifically, a methyl group, an ethyl group, an n-propyl group, i
so-propyl group, n-butyl group, iso-butyl group,
Examples thereof include a sec-butyl group, a tert-butyl group, an n-pentyl group, an iso-pentyl group, a neo-pentyl group, an n-hexyl group, and an iso-hexyl group.

In the polyoxyalkylene moiety of the carbonate ester according to the present invention, an alkylene group having a different number of carbon atoms or a different structure may be present in one molecule. In this case, there is no particular limitation on the polymerization form of the oxyalkylene group. Alternatively, they may be random copolymerized or block copolymerized.

The method for producing the carbonate ester used in the present invention is optional. For example, neopentyl type polyols such as pentaerythritol, trimethylolethane, trimethylolpropane, trimethylolbutane, or dimer or trimer thereof, Alternatively, an alkylene oxide is added to these mixtures, and the resulting mixture is mixed with a chloroformate having 2 to 13 carbon atoms, sodium hydroxide, an alkali metal hydroxide such as potassium hydroxide, sodium methoxide,
Alkali metal alkoxides such as sodium ethoxide,
Alternatively, in the presence of an alkali such as metallic sodium,
It is obtained by reacting at 0 ° C. Alternatively, an alkylene oxide adduct of a neopentyl type polyol, a carbonic acid diester, a source of carbonic acid such as phosgene and an alcohol having 1 to 12 carbon atoms, an alkali metal hydroxide such as sodium hydroxide and potassium hydroxide, sodium methoxide, It is obtained by reacting at 80 to 150 ° C. in the presence of an alkali metal alkoxide such as sodium ethoxide or an alkali such as metal sodium.

The carbonate obtained from the above raw materials may be purified to remove by-products and unreacted products.
A small amount of by-products and unreacted products may be present even if present, as long as the excellent performance of the lubricating oil of the present invention is not impaired. In the present invention, the carbonate may be used in the form of a mixture or may be used alone. The molecular weight of the carbonate ester according to the present invention is not particularly limited, but when used as a refrigerating machine oil, those having a number average molecular weight of 200 to 3000 are preferably used from the viewpoint of further improving the sealing property of the compressor, Those having a number average molecular weight of 300 to 2,000 are more preferably used. Further, the preferred kinematic viscosity of the carbonate ester according to the present invention is 2 to 15 at 100 ° C.
0 cSt, preferably 4 to 100 cSt.

In the lubricating oil of the present invention, the above-mentioned carbonate ester may be used alone, but if necessary, other various lubricating base oils may be mixed and used. When these base oils are exemplified, as a mineral oil, for example, a lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, and catalytic dewatering. Wa,
A base oil such as a paraffinic or naphthenic oil refined by appropriately combining refining treatments such as hydrorefining, sulfuric acid washing, and clay treatment can be used. As synthetic oils, for example, poly α
-Olefin (polybutene, 1-octene oligomer,
1-decene oligomer, etc.), alkylbenzene, alkylnaphthalene, diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di 2-ethylhexyl sebacate, etc.), polyol ester (pentaerythritol 2-ethylhexa) Noate, pentaerythritol pelargonate, trimethylolpropane pelargonate, trimethylolpropane hexanoate, etc.), polyoxyalkylene glycol, polyphenyl ether, silicone oil, or a mixture of two or more thereof can be used. In this case, the carbonate according to the present invention is at least 50% by weight, preferably 7% by weight, based on the total amount of the base oil.
Desirably, it is contained in an amount of 0% by weight or more.

When the lubricating oil of the present invention is used as a refrigerating machine oil, the above carbonate may be used alone, but if necessary, another refrigerating machine oil base oil may be mixed and used. . Preferred as the base oil are polyoxyalkylene glycol, polyoxyalkylene glycol monoether, polyoxyalkylene glycol diether, polyglycol such as polyoxyalkylene glycol glycerol ether, monool, diol, monocarboxylic acid, and dicarboxylic acid. Complex esters of pentaerythritol, trimethylolpropane, or esters of neopentyl-type polyols and carboxylic acids such as dimers and trimers thereof, complex esters of neopentyl-type polyols with monocarboxylic acids and dicarboxylic acids, according to the present invention. And carbonic acid esters having a structure different from the above. These oils may be used alone or in combination of several kinds, and the mixing amount thereof is 80% by weight or less, preferably 70% by weight or less, more preferably 50% by weight or less based on the total amount of the lubricating oil.

Oils such as paraffinic and naphthenic mineral oils, poly-α-olefins, alkylbenzenes and the like may also be mixed. However, since these oils have poor compatibility with hydrogen-containing Freon refrigerants, the amount of lubrication is limited. It is desirable that the content be 30% by weight or less, preferably 20% by weight or less based on the total amount of the oil.

In order to further enhance the excellent performance of the lubricating oil of the present invention, known additives can be used if necessary. Examples of the additive include antioxidants such as phenol, amine, sulfur, zinc thiophosphate, and phenothiazine, molybdenum dithiophosphate, molybdenum dithiocarbamate, molybdenum disulfide, carbon fluoride, borate ester, and aliphatic esters. Amine,
Friction reducing agents such as higher alcohols, higher fatty acids, fatty acid esters, and fatty acid amides; extreme pressure agents such as tricresyl phosphate, triphenyl phosphate and zinc dithiophosphate; rust inhibitors such as petroleum sulfonate, alkylbenzene sulfonate, and dinonyl naphthalene sulfonate; Metal deactivators such as benzotriazole, alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates, metal detergents such as alkaline earth metal phosphonates, succinimides, succinates, benzylamines Ashless dispersants such as silicones, defoamers such as silicones, viscosity index improvers such as polymethacrylates, polyisobutylenes, and polystyrenes, pour point depressants, and the like. These can be added alone or in combination of two or more. . The content of the viscosity index improver is usually 1 to 3.
0% by weight, the content of the defoamer is usually 0.0005 to 1% by weight, and the content of the metal deactivator is usually 0.005 to 1%.
% By weight and the content of other additives are usually 0.1% each.
1 to 15% by weight (all based on the total amount of the lubricating oil).

When the lubricating oil of the present invention is used as a refrigerating machine oil, a phosphate ester, an acidic phosphate ester, and an amine salt of an acidic phosphate ester are used in order to further improve the wear resistance and the load resistance. And at least one phosphorus compound selected from the group consisting of chlorinated phosphates and phosphites. These phosphorus compounds are esters of phosphoric acid or phosphorous acid with alkanols or polyether alcohols or derivatives thereof. Specifically, examples of the phosphoric ester include tributyl phosphate, triphenyl phosphate, tricresyl phosphate, and the like. Examples of the acidic phosphate include ditetradecyl acid phosphate, dipentadecyl acid phosphate, dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, and the like. Examples of the amine salt of the acidic phosphoric acid ester include the acidic phosphoric acid ester methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Examples thereof include salts with amines such as dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine and trioctylamine. The chlorinated phosphates include tris-dichloropropyl phosphate, tris-
Chloroethyl phosphate, polyoxyalkylene bis [di (chloroalkyl)] phosphate, tris-chlorophenyl phosphate and the like can be mentioned. Examples of the phosphite include dibutyl phosphite, tributyl phosphite, dipentyl phosphite, tripentyl phosphite, dihexyl phosphite, trihexyl phosphite, diheptyl phosphite, triheptyl phosphite, dioctyl phosphite, and trioctyl phosphite. Phyte, dinonyl phosphite, trininol phosphite, didecyl phosphite, tridecyl phosphite, diundecyl phosphite, triundecyl phosphite, didodecyl phosphite, tridodecyl phosphite, diphenyl phosphite, triphenyl phosphite Phyto, dicresyl phosphite, tricresyl phosphite and the like. Also, a mixture of these can be used. When these phosphorus compounds are blended, 0.1 to 5.0% by weight, preferably 0.2 to 5.0% by weight, based on the total amount of the lubricating oil.
Desirably, the content is 2.0% by weight.

When the lubricating oil of the present invention is used as a refrigerating machine oil, a phenylglycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an epoxidized fatty acid monoester and an epoxidized vegetable oil are used to further improve the stability. And at least one epoxy compound selected from the group consisting of: Examples of the phenylglycidyl ether type epoxy compound referred to here include phenylglycidyl ether and alkylphenylglycidyl ether. The alkylphenyl glycidyl ether referred to herein is one having 1 to 3 alkyl groups having 1 to 13 carbon atoms, among which one having one alkyl group having 4 to 10 carbon atoms, for example, butylphenyl glycidyl ether, pentyl Phenylglycidyl ether, hexylphenylglycidylether, heptylphenylglycidylether, octylphenylglycidylether, nonylphenylglycidylether, and decylphenylglycidylether are preferred. Examples of the glycidyl ester type epoxy compound include phenyl glycidyl ester, alkyl glycidyl ester, and alkenyl glycidyl ester, and preferable examples include glycidyl benzoate, glycidyl acrylate, and glycidyl methacrylate.

Examples of the epoxidized fatty acid monoester include esters of an epoxidized fatty acid having 12 to 20 carbon atoms and an alcohol or phenol or alkylphenol having 1 to 8 carbon atoms. Particularly, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxystearic acid are preferably used.

As the epoxidized vegetable oil, soybean oil,
Examples include epoxy compounds of vegetable oils such as linseed oil and cottonseed oil.

Preferred among these epoxy compounds are phenylglycidyl ether type epoxy compounds and epoxidized fatty acid monoesters. Above all, a phenylglycidyl ether type epoxy compound is more preferable, and phenylglycidyl ether, butylphenylglycidyl ether and a mixture thereof are particularly preferable.

When these epoxy compounds are blended,
It is desirable that the content be 0.1 to 5.0% by weight, preferably 0.2 to 2.0% by weight based on the total amount of the lubricating oil.

Further, when the lubricating oil of the present invention is used as a refrigerating machine oil, in order to further improve its wear resistance and load resistance, a general formula is used.

[0037]

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Wherein R ⁶ and R ⁷ may be the same or different and each represents an alkyl group having 8 to 18 carbon atoms.
As the carboxylic acid, specifically, for example, octylmalonic acid, nonylmalonic acid, decylmalonic acid, undecylmalonic acid, dodecylmalonic acid, tridecylmalonic acid,
Tetradecylmalonic acid, pentadecylmalonic acid, hexadecylmalonic acid, heptadecylmalonic acid, octadecylmalonic acid, decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid , Nonadecanoic acid, eicosanoic acid, and mixtures of two or more thereof. When these carboxylic acids are blended, 0.01 to 3% by weight, preferably 0.05 to 2% by weight based on the total amount of the lubricating oil.
It is desirable that the content be contained in a proportion of weight%.

Of course, two or more of the above phosphorus compounds, epoxy compounds and carboxylic acids may be used in combination.

Further, when the lubricating oil of the present invention is used as a refrigerating machine oil, in order to further improve its performance,
If necessary, conventionally known refrigerator oil additives such as di-tert-butyl-p-cresol, phenols such as bisphenol A, phenyl-α-naphthylamine,
Antioxidants such as amines such as N, N-di (2-naphthyl) -p-phenylenediamine; antiwear agents such as zinc dithiophosphate; extreme pressure agents such as chlorinated paraffins and sulfur compounds;
Additives such as oily agents such as fatty acids, defoamers such as silicones, and metal deactivators such as benzotriazole may be used alone or in combination of several kinds. The total amount of these additives is usually based on the total amount of the lubricating oil.
It is at most 10% by weight, preferably at most 5% by weight.

In the present invention, when other refrigerating machine oils and additives are blended, the carbonate ester according to the present invention is at least 5% by weight, preferably at least 10% by weight, and more preferably at least 50% by weight, based on the total amount of the lubricating oil. It is desirable that the content is more than 70% by weight, more preferably more than 70% by weight.

When the lubricating oil containing a carbonate ester as a main component of the present invention is used as a refrigerating machine oil, the lubricating oil usually needs to have a kinematic viscosity and a pour point that are used as refrigerating machine oil. In order to prevent the solidification of the lubricating oil at the time, it is desirable that the pour point is −10 ° C. or lower, preferably −20 ° C. to −80 ° C. Further, in order to maintain the hermeticity with the compressor, the kinematic viscosity at 100 ° C. is desirably 2 cSt or more, preferably 3 cSt or more. Considering the fluidity at a low temperature and the efficiency of heat exchange in the vaporizer, 100 ° C.
Kinematic viscosity at 150 cSt or less, preferably 100 cSt
Desirably, it is not more than cSt.

As the refrigerant used when the lubricating oil of the present invention is used as a refrigerating machine oil, specifically, trifluoromethane (HFC-23), pentafluoroethane (HF
C-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1-difluoroethane (HFC-152a), Hydrogen-containing fluorocarbons such as monochlorodifluoromethane (HCFC-22), 1-chloro-1,1-difluoroethane (HCFC-142b), dichlorotrifluoroethane (HCFC-123), and monochlorotetrafluoroethane (HCFC-124); trichloro Hydrogen-free Freon such as monofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), monochlorotrifluoromethane (CFC-13), monochloropentafluoroethane (CFC-115), or a mixture of two or more thereof And the like,
From the viewpoint of environmental problems, it is preferable to use a hydrogen-containing fluorocarbon, and in particular, HFC-23, HFC-134, HFC-13
It is preferable to use a non-chlorinated chlorofluorocarbon such as 4a and HFC-152a, among which HFC-134a is preferable.

When the lubricating oil of the present invention is used as refrigerating machine oil, an air conditioner having a reciprocating or rotary compressor,
Dehumidifiers, refrigerators, freezers, refrigerated warehouses, vending machines,
It is particularly preferably used for a cooling device of a showcase, a chemical plant or the like, but it can also be preferably used for a device having a centrifugal compressor. Further, the lubricating oil of the present invention can be preferably used not only as a refrigerating machine oil, but also as an engine oil, a gear oil, a working oil, a metal working oil, and other industrial lubricating oils.

[0045]

EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these.

[0046]Examples 1-4 and Comparative Examples 1-6  The lubricating oils used in the examples and comparative examples are shown below.

Example 1

[0048]

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A refrigerating machine oil comprising an ethesyl carbonate having an average molecular weight of 1,800 represented by the formula: wherein (PO) _n represents an oxypropylene group.

Example 2

[0051]

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A refrigerating machine oil comprising an ethesyl carbonate having an average molecular weight of 1,600 represented by the formula: wherein (PO) _n represents an oxypropylene group.

Embodiment 3

[0054]

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In the formula, (PO, EO) _m is a random copolymer of oxypropylene groups and oxyethylene groups, and indicates that the weight ratio of oxypropylene groups to oxyethylene groups is 50:50. Refrigeration oil consisting of ethesulfate carbonate having an average molecular weight of 2,000.

Embodiment 4:

[0057]

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In the formula, (PO, EO) _m is a random copolymer of an oxypropylene group and an oxyethylene group, and indicates that the weight ratio of the oxypropylene group to the oxyethylene group is 50:50. Refrigerating machine oil consisting of ethsole carbonate having an average molecular weight of 2,500.

Comparative Example 1: Naphthenic mineral oil.

Comparative Example 2: Branched alkylbenzene (average molecular weight: about 480).

Comparative Example 3: Tetraester of pentaerythritol with 2-methyl-hexanoic acid and 2-ethyl-hexanoic acid.

Comparative Example 4: Polyoxypropylene glycol (average molecular weight: about 2,000).

Comparative Example 5: Polyoxypropylene glycol monomethyl ether (average molecular weight: about 1,600).

Comparative Example 6: Polyoxypropyleneoxyethylene glycol dimethyl ether (average molecular weight: about 2,
000).

In order to evaluate the performance of the base oils of the refrigerating machine oils of Examples 1 to 4 according to the present invention, the refrigerant solubility with HFC-134a, the hydrolysis stability and the Falex wear test were evaluated. For comparison, mineral oils, alkylbenzenes, ester oils and polyalkylene glycols disclosed in U.S. Pat. No. 4,755,316 disclosed in U.S. Pat. Table 1 also shows the test results of the polyoxypropylene oxyethylene glycol monomethyl ether and the polyoxypropylene oxyethylene glycol dimethyl ether (Comparative Examples 1 to 6) disclosed in JP-A-1-259095.

<Solubility with HFC-134a> Inner diameter 6 m
In a glass tube having a length of 220 mm and a length of 220 mm, 0.2 g of the sample oil of each of Examples and Comparative Examples was collected, and further cooled (HFC-13).
4a) 2.0 g was collected and a glass tube was sealed. The glass tube was placed in a low-temperature bath or a high-temperature bath at a predetermined temperature, and it was observed whether the refrigerant and the sample oil were mutually dissolved, separated or clouded.

<Hydrolysis Test> Sample oil 60 g, water 0.6
g in a 200 ml glass test tube, and put a copper plate, an iron plate and an aluminum plate (6 cm ² ) as a catalyst for promoting deterioration in a stainless steel autoclave at 175 ° C. and 168 ° C.
Degraded by heating for hours. After the test, the acid value and hydroxyl value of the sample oil were measured.

<FALEX Wear Test> ASTM D 2
According to 670, a sample oil temperature of 100 ° C., a break-in operation of 150 lb for 1 minute, and then operation under a load of 250 lb for 2 hours. After the test, the wear amount of the test journal was measured.

[0069]

[Table 1]

As shown in Examples 1 to 4 in Table 1, the lubricating oil according to the present invention was different from Comparative Examples 1 and 2 in that HFC-1
The solubility of the refrigerant in 34a is very excellent. In particular, the carbonate ester oil in the present invention has excellent refrigerant solubility as compared with the polyalkylene glycols shown in Comparative Examples 4 to 6, which are said to have excellent solubility in the HFC-134a refrigerant. Also in the wear test by Falex, it can be seen that Examples 1-4 are equal to or more than Comparative Examples 1-2 and 4-6.

Further, as shown in Comparative Example 3, ester oil has poor hydrolysis stability, and there is a problem in use due to corrosion of generated acid in a refrigerating machine system in which water is expected to enter and enter. On the other hand, in Examples 1 to 4, although there is a slight hydrolysis, a hydroxyl group is generated, but no acid is generated, so there is no problem.

[0072]

As is clear from the above description and the examples, the lubricating oil of the present invention is suitable for use in a refrigerator for hydrogen-containing Freon, and has a solubility in a refrigerant, a hydrolytic stability and an abrasion resistance. It is a lubricating oil with excellent properties, and is particularly preferably used as a refrigerator oil.

──────────────────────────────────────────────────続 き Continued on the front page (58) Investigated field (Int.Cl. ⁶ , DB name) C10M 105/48 C10M 107/34 C10N 40:30 C10M 145/26 C10M 129/84 C10M 159/12 C10M 109 / 02

Claims (5)

(57) [Claims] 1. A compound of the general formula [Wherein X is an alkyl group, a cycloalkyl group, and a carbon number of 5
To 30 and a residue of a neopentyl polyol having 2 to 8 hydroxyl groups, or a general formula: A ¹ , A ² , A ³ , A ⁴ and A ⁵ may be the same or different and each have 2 carbon atoms.
And R ¹ and R ⁴ may be the same or different, each represents an alkyl group having 1 to 6 carbon atoms, and R ² , R ³ and R ⁵ may be the same or different Represents an alkyl group, a cycloalkyl group or a residue of a neopentyl polyol having 5 to 30 carbon atoms and 2 to 8 hydroxyl groups, respectively;
２2, b = 0-2 and a + b = 2, c and d indicate c = 0 ＝ 2, d = 1 ＝ 3 and c + d = 3, respectively; e = 1１〜３3 , F = an integer of 1 to 5; l, m, n, j, and k each represent an integer of 1 to 50]. 2. The synthetic lubricating oil according to claim 1, which is used as a refrigerating machine oil. 3. The synthetic lubricating oil according to claim 1, wherein said carbonate ester is used as a base oil. (I) said ester, and (II) polyglycol selected from polyoxyalkylene glycol, polyoxyalkylene glycol monoether, polyoxyalkylene glycol diether, polyoxyalkylene glycol glycerol ether, and monool, Complex esters of diols, monocarboxylic acids and dicarboxylic acids, pentaerythritol, trimethylolpropane, or 2-3 of these
Esters of neopentyl-type polyols such as monomers and carboxylic acids, complex esters of neopentyl-type polyols with monocarboxylic and dicarboxylic acids, (I)
The synthetic lubricating oil according to claim 1 or 2, wherein the base oil is a mixed oil with at least one oil selected from the group consisting of esters selected from carbonate esters having a structure different from that of the above. 5. The amount of the oil of (II) is 80 to the total amount of the lubricating oil.
The synthetic lubricating oil according to claim 4, which is not more than weight%.