JP2617369B2 - Synthetic lubricant - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a synthetic lubricating oil, and more particularly to a synthetic lubricating oil containing carbonate ester as a main component and particularly useful as a refrigerator oil and the like.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, as refrigeration oil, kinematic viscosity at 40 ° C.
A naphthenic mineral oil, a paraffinic mineral oil, an alkylbenzene, a polyglycol-based oil, a mixture thereof, or a mixture of these various base oils with an additive of 10 to 200 cSt are generally used.

On the other hand, CFC-based refrigerants used in refrigerators include CF
C-11, CFC-12, CFC-115, HCFC-22 and the like are used.

Among these CFC-based refrigerants, CFC-11, CFC-12, CF
CFCs in which all the hydrogens of hydrocarbons such as C-115 are replaced by halogens containing chlorine are subject to regulation because they lead to ozone depletion. Therefore, hydrogen-containing Freon,
In particular, non-chlorinated chlorofluorocarbon such as HFC-134a and HFC-152a is CF
C is being used as a replacement, but in particular, HFC-134a
Has similar thermodynamic properties to CFC-12, which has been 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 a refrigerant 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, etc. have little 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.

In order to solve this problem, the present inventors have previously developed and have already filed a polyglycol-based refrigerating machine oil having compatibility with HFC-134a which is significantly better than conventionally known refrigerating machine oils. (JP-A-1-256594, JP-A-274191, etc.). Also, U.S. Pat.No. 4,755,316 includes HFC-134a
Polyglycol-based refrigerating machine oils that are compatible with are disclosed.

On the other hand, refrigerating machine oil used for compressors such as home refrigerators requires high electrical insulation. Among the known refrigerating machine oils, those having the highest electrical insulation properties are alkylbenzenes and mineral oils. However, as described above, alkylbenzenes and mineral oils have almost no compatibility with non-chlorinated chlorofluorocarbons such as HFC-134a. In addition, polyglycol-based oils having excellent compatibility with HFC-134a have a problem of poor electrical insulation.

The present inventors have found that an ester having a specific structure is HFC-1
It has been found that it has excellent compatibility with non-chlorinated chlorofluorocarbons such as 34a and has high electrical insulation properties, and has previously filed a patent application.

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, HFC-134a
It has been desired to develop a refrigerating machine oil having high compatibility with hydrogen-containing chlorofluorocarbons, electrical insulation and hydrolysis stability.

Further, conventionally, ester-based synthetic oils are known as synthetic oils having excellent heat resistance. However, since they are hydrolyzed as described above, the emergence of ester-based synthetic oils having excellent hydrolysis stability is in great demand. It had been.

The present inventors have paid attention to the excellent various performances of the ester-based synthetic oil, and as a result of repeated studies to develop a lubricating oil capable of meeting the above requirements, a carbonate having a specific structure was found to be HFC-134a or the like. Excellent compatibility with hydrogen-containing Freon,
The present inventors have found that they have high electrical insulation properties and also have excellent hydrolysis stability, and have completed the present invention.

The present invention contains a carbonate having a specific structure as a main component. An object of the present invention is to provide a synthetic lubricating oil having excellent compatibility with hydrogen-containing chlorofluorocarbons such as HFC-134a, high electrical insulation, and further excellent hydrolysis stability.

[Means for Solving the Problems] That is, the present invention provides an alcohol component comprising: (A) a monohydric alcohol, (B) a dihydric alcohol, and (C) neopentyl having 5 to 7 carbon atoms and 3 to 4 hydroxyl groups. An object of the present invention is to provide a synthetic lubricating oil characterized in that the main component is a type polyol or a carbonate ester which is a dimer or trimer.

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

The lubricating oil of the present invention comprises (A) a monohydric alcohol, (B) a dihydric alcohol, and (C) a carbon number of 5
And a neopentyl polyol having 3 to 4 hydroxyl groups,
Alternatively, it is characterized in that the dimer-trimer carbonate is a main component.

(A) As the monohydric alcohol, those having 1 to 15 carbon atoms are preferably used, and specifically, for example, methanol,
Ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol,
Those having a linear or branched alkyl group such as tridecanol, tetradecanol, and pentadecanol are exemplified. More preferred alcohols have 1 to 9 carbon atoms.

As the dihydric alcohol (B), those having 2 to 12 carbon atoms are preferably used. Specifically, for example, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2 -Butanediol, 2-
Methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, -Methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, Examples thereof include 11-undecanediol and 1,12-dodecanediol. More preferred dihydric alcohols have 2 to 9 carbon atoms.

(C) Neopentyl type polyol having 5 to 7 carbon atoms and 3 to 4 hydroxyl groups, or the dimer or trimer, specifically, for example, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol or These dimers and trimers are exemplified. Among them, particularly preferred are trimethylolpropane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, di- (pentaerythritol), tri- (pentaerythritol) and the like.

The carbonate ester as a main component of the lubricating oil of the present invention has a structure derived from the above-mentioned alcohol (A) component, (B) component and (C) component. In other words, not only those synthesized using carbonic acid and the components (A), (B), and (C) as raw materials, but also carbonates having the above-described structure may be obtained as a result.

The method for producing the carbonic acid ester used in the present invention is optional. sodium,
It is obtained by reacting at 80 to 200 ° C. in the presence of an alkali such as sodium hydroxide and sodium methoxide. In this case, carbonates having various structures, molecular weights and viscosities can be obtained by changing the molar ratio of the source of the carbonic acid moiety and the alcohol. ~ 100 mol, preferably 1-20
Mole, (A) component 1 to 20 mole, preferably 1 to 10 mole,
The reaction is preferably carried out in a proportion of 1 to 100 mol, preferably 1 to 20 mol, of the component (B).

The carbonate obtained from the raw material as described above may be purified to remove by-products and unreacted products, but a small amount of by-products and unreacted products are excellent performance of the lubricating oil of the present invention. There is no problem even if it exists, as long as it 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, from the viewpoint of further improving the sealing property of the compressor, the number average molecular weight is 200.
~ 3000 are preferably used and the number average molecular weight is 300
~ 2000 are more preferably used. Further, the preferred kinematic viscosity of the carbonate ester according to the present invention is 2 to 150 cSt, preferably 4 to 100 cSt at 100 ° C.

As an example of the structure of the carbonate of the present invention, when the component (C) is trimethylolpropane, [Wherein, R represents an alkyl group having 1 to 15 carbon atoms, R 'represents an alkylene group having 2 to 12 carbon atoms, and x represents an integer of 0 to 12].

In the lubricating oil of the present invention, the above-mentioned carbonate ester may be used alone, but if necessary, various other 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. A paraffinic or naphthenic base oil refined by appropriately combining refining treatments such as wax, hydrorefining, sulfuric acid washing, and clay treatment can be used. Examples of the synthetic oil include 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-3-ethylhexyl sebacate, etc.), polyol esters (trimethylolpropane caprylate, trimethylolpropaneperargonate, pentaerythritol 2-ethylhexanoate,
Pentaerythritol pelargonate), polyoxyalkylene glycol, polyphenyl ether, silicone oil, perfluoroalkyl ether, or a mixture of two or more thereof. In this case, it is desirable that the carbonate ester according to the present invention is contained in an amount of 50% by weight or more, preferably 70% by weight or more based on the total amount of the base oil.

When the lubricating oil of the present invention is used as a refrigerating machine oil, the above-mentioned carbonate ester may be used alone, but if necessary, another refrigerating machine oil base oil may be mixed and used. Preferred examples of the base oil include the following.

In the general formula R ₁ OR _{3 a} OR ₂ [wherein, R ₁ and R ₂ represents hydrogen or an alkyl group having 1 to 18 carbon atoms, R ₃ represents an alkylene group having 2 to 4 carbon atoms,
a represents an integer of 5 to 70.] A polyoxyalkylene glycol or an ether thereof.

General formula [Wherein, R _{4 to} R ₆ represent hydrogen or an alkyl group having 1 to 18 carbon atoms, and R _{7 to} R ₉ represent an alkylene group having 2 to 4 carbon atoms;
b to d each represent an integer of 5 to 7]. Polyoxyalkylene glycol glycerol ether represented by the formula:

General formula Wherein X ₁ is -OR ₁₂ or X ₂ is a group represented by Or Wherein each of R ₁₀ and R ₁₆ is an alkylene group having 1 to 8 carbon atoms, and R ₁₁ and R ₁₃ are each a group having 2 to 16 carbon atoms.
R ₁₂ and R ₁₇ each represent an alkyl group having 1 to ₁₅ carbon atoms; R ₁₄ and R ₁₅ each represent an alkyl group having 1 to 14 carbon atoms; e and f are each 0 or 1; 0
Represents an integer of up to 30], an ester represented by the general formula [Wherein X ₃ is a methyl group, an ethyl group, a propyl group and a general formula Wherein R _{18 to} R ₂₁ are linear alkyl groups having 3 to 11 carbon atoms, branched alkyl groups having 3 to 15 carbon atoms, and 6 And the proportion of linear alkyl groups is 60% or less based on all alkyl groups, and h is an integer of 1 to 3].

General formula [Wherein X ₄ and X ₅ may be the same or different and each represents a methyl group, an ethyl group, a propyl group and a general formula Represents any group selected from the group consisting of groups represented by the following, wherein R _{22 to} R ₂₆ are an alkyl group having 3 to 15 carbon atoms, and R ₂₇ is a divalent hydrocarbon group having 1 to 8 carbon atoms. And i is 1-5
And a polyol dicarboxylic acid ester represented by the formula:

General formula Wherein R ₂₈ and R ₂₉ may be the same or different,
An alkyl group having 1 to 15 carbon atoms or 2 to 12 carbon atoms, respectively
Wherein R ₃₀ represents an alkylene group having 2 to 12 carbon atoms, and j represents an integer of 0 to 30].

General formula [Wherein X ₆ is a hydrogen atom or a general formula Wherein R _{31 to} R ₃₃ may be the same or different and each have an alkyl group having 1 to 12 carbon atoms,
Represents a cycloalkyl group of up to 12 or a neopentyl-type polyol residue having 5 to 30 carbon atoms and 3 to 8 hydroxyl groups,
₃₄ is an alkyl group having 1 to 6 carbon atoms, k is 1 or 2, l is 0 or 1, and k + 1 = 2, and m is 0 to 30 (m = 0 In this case, at least one of R ₃₁ and R ₃₂ represents a neopentyl-type polyol residue), and n represents an integer of 1 to 3, respectively. ] The carbonate represented by these.

Among these, carbonate esters are particularly preferred as the mixed oil of the lubricating oil of the present invention.

These oils may be used alone or in combination of several kinds. Oils such as paraffinic and naphthenic mineral oils, poly-α-olefins, and alkylbenzenes may be mixed, but in this case, the compatibility with the non-chlorinated fluorocarbon solvent is reduced.

The blending amount of these base oils is not particularly limited as long as the excellent performance of the lubricating oil of the present invention as a refrigerator oil is not impaired, but usually less than 50% by weight based on the total amount of the lubricating oil, Preferably, it is blended so as to be 30% by weight or less.

In order to further enhance the excellent performance of the lubricating oil of the present invention, known additives can be used as needed. Examples of the additive include antioxidants such as phenol-based, amine-based, sulfur-based, zinc thiophosphate-based, phenothiazine-based, molybdenum dithiophosphate, molybdenum dithiocarbamate, molybdenum disulfide, carbon fluoride, borate ester, and aliphatic ester. Friction reducing agents such as amines, 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 Agents, metal deactivators such as benzotriazole, metal-based detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates, alkaline earth metal phosphonates, succinimides, Ashless dispersants such as citrate esters and benzylamine; defoamers such as silicone; viscosity index improvers such as polymethacrylate, polyisobutylene and polystyrene; pour point depressants; and the like, alone or in combination of two or more. Can be added.
The content of the viscosity index improver is usually 1 to 30% by weight, the content of the defoamer is usually 0.0005 to 1% by weight, the content of the metal deactivator is usually 0.005 to 1% by weight, The content of each additive is usually 0.1 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, in order to further improve its abrasion resistance and load resistance, phosphate ester, acidic phosphate ester, amine salt of acidic phosphate ester, chlorinated At least one phosphorus compound selected from the group consisting of phosphate esters and phosphite esters can be blended. 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, Dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine,
Salts with amines such as tripentylamine, trihexylamine, triheptylamine, trioctylamine and the like can be mentioned. Examples of the chlorinated phosphate include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, polyoxyalkylene bis [di (chloroalkyl)] phosphate, and tris-chlorophenyl phosphate. As phosphites,
Dibutyl phosphite, tributyl phosphite, dipentyl phosphite, tripentyl phosphite, dihexyl phosphite, trihexyl phosphite, diheptyl phosphite, triheptyl phosphite, dioctyl phosphite, trioctyl phosphite, dinonyl phosphite, Didecyl phosphite, diundecyl phosphite, triundecyl phosphite, didodecyl phosphite, tridodecyl phosphite, diphenyl phosphite, triphenyl phosphite, dicresyl phosphite, tricresyl phosphite, and the like. Also, a mixture of these can be used. When compounding these phosphorus compounds, 0.1 to
It is desirable that the content is 5.0% by weight, preferably 0.2 to 2.0% by weight.

When the lubricating oil of the present invention is used as a refrigerating machine oil, in order to further improve its stability, a group consisting of a phenylglycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an epoxidized fatty acid monoester and an epoxidized vegetable oil. At least one type of epoxy compound selected from the following can be blended. Examples of the phenylglycidyl ether type epoxy compound referred to here include phenylglycidyl ether and alkylphenylglycidyl ether. The alkylphenyl glycidyl ether referred to here has 1 to 1 carbon atoms.
Those having 1 to 3 alkyl groups of 13 and, among them, those having 1 alkyl group of 4 to 10 carbon atoms, such as butylphenylglycidyl ether, pentylphenylglycidylether, hexylphenylglycidylether, heptylphenylglycidylether, Octylphenyl glycidyl ether, nonylphenyl glycidyl ether and decylphenyl glycidyl ether 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.

Epoxidized vegetable oils include soybean oil, linseed oil,
Examples include epoxy compounds of vegetable oils such as 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 they be contained at a ratio of 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, the general formulas R ₃₅ -CH (COOH) ₂ and / or R ₃₆ -CH _2- COOH wherein R ₃₅ and R ₃₆ may be the same or different,
Each represents an alkyl group having 8 to 18 carbon atoms]. Specific examples of the carboxylic acid include octylmalonic acid, nonylmalonic acid, decylmalonic acid, undecylmalonic acid, dodecylmalonic acid, tridecylmalonic acid, tetradecylmalonic acid, pentadecylmalonic acid, and 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 of these And the like.
When these carboxylic acids are blended, it is desirable that they be contained in a proportion of 0.01 to 3% by weight, preferably 0.05 to 2% by weight, based on the total amount of the lubricating oil.

Further, needless to say, 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, conventionally known refrigerating machine oil additives such as di-tert-butyl-p-cresol, bisphenol A, etc. Phenol, phenyl-α-naphthylamine, N, N-di (2-
Amine antioxidants such as naphthyl) -p-phenylenediamine; antiwear agents such as zinc dithiophosphate; extreme pressure agents such as chlorinated paraffins and sulfur compounds; oily agents such as fatty acids;
Additives such as silicone-based antifoaming agents and metal deactivators such as benzotriazole may be used alone or in combination of several kinds. The total amount of these additives is usually 10% by weight or less, preferably 5% by weight or less based on the total amount of the lubricating oil.

In the present invention, when other refrigerating machine oils or additives are blended, the carbonate ester according to the present invention is preferably contained in an amount of more than 50% by weight, preferably 70% by weight or more, based on the total amount of the lubricating oil. .

When the lubricating oil containing the carbonate ester of the present invention as a main component is used as a refrigerating machine oil, the lubricating oil may have a kinematic viscosity and a pour point that are generally used as the refrigerating machine oil. Pour point of -10 to prevent solidification of oil
C. or lower, preferably -20.degree. C. to -80.degree. In order to maintain the sealing performance with the compressor, the kinematic viscosity at 100 ° C is preferably 2 cSt or more, and more preferably 3 cSt or more.In consideration of the fluidity at low temperature and the efficiency of heat exchange in the vaporizer, the kinematic viscosity at 100 ° C is considered. Is desirably 150 cSt or less, preferably 100 cSt or less.

As the refrigerant used when the lubricating oil of the present invention is used as a refrigerating machine oil, specifically, 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoro Ethane (HFC-134a), 1,1-difluoroethane (HFC-152
a), hydrogen-containing Freon such as trifluoromethane (HFC-23), monochlorodifluoromethane (HCFC-22), 1-chloro-1,1-difluoroethane (HCFC-142b), trichloromonofluoromethane (CFC-11), Dichlorodifluoromethane (CFC-12), Monochlorotrifluoromethane (CFC-13), Monochloropentafluoromethane (CFC
-115), etc., or a mixture of two or more of these, and the like. From the viewpoint of environmental issues, it is preferable to use a hydrogen-containing Freon, and particularly preferable to use HFC-134a. The lubricating oil of the present invention has much better compatibility with hydrogen-containing chlorofluorocarbons, especially non-chlorinated fluorocarbons, than conventionally known lubricating oils.

Further, the lubricating oil of the present invention is an excellent lubricating oil having not only high compatibility with non-chlorinated chlorofluorocarbons and high electric insulation but also high lubricity and low hygroscopicity.

When the lubricating oil of the present invention is used as refrigerating machine oil, cooling of an air conditioner having a reciprocating or rotary compressor, a dehumidifier, a refrigerator, a freezer, a freezing and refrigerated warehouse, a vending machine, a showcase, a chemical plant, etc. Although it is particularly preferably used for an apparatus or the like, 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.

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 thereto.

Examples 1 to 4 and Comparative Examples 1 to 5 Lubricating oils used in Examples and Comparative Examples are shown below.

Example 1: 10 mol of diethyl carbonate, 4 mol of 2-methyl-1-pentanol, 3 mol of neopentyl glycol and 1 mol of trimethylolpropane were placed in a reaction vessel, and subjected to transesterification at 120 ° C. for 4 hours using sodium metal as a catalyst. . Ethanol produced by transesterification was removed by distillation, treated with dilute hydrochloric acid, washed with water, and then a low molecular weight component in the product was distilled off to obtain a sample oil.

Example 2: diethyl carbonate 10 mol, 2,2,4-trimethyl-1-
4 mol of pentanol, 3 mol of 3-methylpentanediol and 1 mol of trimethylolpropane were placed in a reaction vessel, and transesterification was carried out at 120 ° C. for 4 hours using sodium metal as a catalyst. Ethanol produced by transesterification was removed by distillation, treated with dilute hydrochloric acid, washed with water, and then a low molecular weight component in the product was distilled off to obtain a sample oil.

Example 3: 10 mol of diethyl carbonate, 2 mol of 2-methyl-1-pentanol, 2 mol of 3-methylpentanediol, 2 mol of neopentyl glycol and 1 mol of pentaerythritol
Into a reaction vessel, and using sodium metal as a catalyst, 120 ° C
For 4 hours. Ethanol produced by transesterification was removed by distillation, treated with dilute hydrochloric acid, washed with water, and then a low molecular weight component in the product was distilled off to obtain a sample oil.

Example 4: diethyl carbonate 10 mol, 2,2,4-trimethyl-1-
4 mol of pentanol, 4 mol of propylene glycol and 1 mol of pentaerythritol were placed in a reaction vessel, and transesterified at 120 ° C. for 4 hours using sodium metal as a catalyst. Ethanol produced by transesterification was removed by distillation, treated with dilute hydrochloric acid, washed with water, and then a low molecular weight component in the product was distilled off to obtain a sample oil.

Comparative Example 1: Naphthenic mineral oil.

Comparative Example 2: Branched-chain alkylbenzene (average molecular weight of about 30
0).

Comparative Example 3: Pentaerythritol and tetraester of 2-methyl-hexanoic acid and 2,4-dimethylheptanoic acid.

Comparative Example 4: Complex ester of 3-methyl-1,5-pentanediol, adipic acid and 3,5,5-trimethylhexanoic acid (average molecular weight: about 500).

Comparative Example 5: Polyoxypropylene glycol (average molecular weight: about 900).

In order to evaluate the performance of the base oils of the lubricating oils of Examples 1 to 4 according to the present invention, the solubility with HFC-134a, the hydrolyzability, the insulating properties, the Falex wear test and the hygroscopicity were evaluated. For comparison, Table 1 also shows the test results of mineral oil, alkylbenzene, ester oil and polyalkylene glycol (Comparative Examples 1 to 5) conventionally used for lubricating oils.

<Solubility with HFC-134a> In a glass tube having an inner diameter of 6 mm and a length of 220 mm, 0.2 g of the sample oil of each of the examples and the comparative examples was collected, and the refrigerant (HFC-134a) 2.0 was further added.
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> 60 g of sample oil and 0.6 g of water were placed in a 200 ml glass test tube, and a copper plate, iron plate and aluminum plate (6c
m ² ) in a stainless steel autoclave at 175 ° C, 1
Degraded by heating for 68 hours.

 After the test, the acid value and hydroxyl value of the sample oil were measured.

<Insulation Characteristics> The volume resistivity of the sample oil was measured according to JIS C 2101. The test was performed at 25 ° C.

<FALEX abrasion test> According to ASTM D 2670, a sample oil temperature of 100 ° C and a break-in operation of 150 lb were performed for 1 minute, followed by operation under a load of 250 lb for 2 hours. After the test, the wear amount of the test journal was measured.

<Hygroscopicity> 30 g of the sample oil was placed in a 300 ml beaker, allowed to stand in a thermo-hygrostat kept at 30 ° C. and 60% humidity for 7 days, and the water content was measured by the Karl Fischer method.

As shown in Examples 1 to 4 in Table 1, the lubricating oil according to the present invention has much better refrigerant solubility in HFC-134a than Comparative Examples 1 and 2.

As shown in Comparative Examples 3 and 4, ester oil is excellent in refrigerant solubility and electrical insulation, but has poor hydrolyzability.
Refrigerator systems in which water is expected to enter and enter water have a problem in use due to corrosion of generated acids. On the other hand, Examples 1-4
Is slightly hydrolyzed to form a hydroxyl group, but does not generate any acid, so there is no problem.

Examples 1 to 4 are not inferior to mineral oil and alkylbenzene in terms of insulating properties, are almost equivalent to ester oil, and are superior to alkylene glycol oil of Comparative Example 5.

Also, in the wear test by Falex, it can be seen that Examples 1 to 4 are equal to or more than Comparative Examples 1 to 5.

Regarding the hygroscopicity of water, the lubricating oils of Examples 1 to 4
Compared with Comparative Examples 1 and 2, it is almost equivalent to the ester oils of Comparative Examples 3 and 4, and is significantly superior to the alkylene glycol of Comparative Example 5.

[Effects of the Invention] As is clear from the above description and Examples, the lubricating oil of the present invention is suitable for use in a refrigerator for hydrogen-containing Freon, has excellent electrical insulation properties, and has excellent wear resistance. It is a lubricating oil having excellent non-hygroscopicity, and is particularly preferably used as a refrigerator oil.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C10M 105: 38 137: 04 129: 18 129: 66 129: 40 129: 42) C10N 30:06 40 : 30 (72) Inventor Tatsuyuki Ishikawa 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Pref. Japan Petroleum Corporation Central Research Laboratory (56) References JP-A-4-63893 (JP, A) JP-A-4-18490 (JP, A) JP-A-3-149295 (JP, A) JP-A-48-37568 (JP, A)

Claims (10)

(57) [Claims] An alcohol component comprising: (A) a monohydric alcohol, (B) a dihydric alcohol, and (C) a neopentyl polyol having 5 to 7 carbon atoms and 3 to 4 hydroxyl groups, or a dimer or trimer thereof. A synthetic lubricating oil characterized by comprising a carbonate ester as a main component. 2. The component (c) comprises trimethylolpropane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, di- (pentaerythritol), and tri- (pentaerythritol). The synthetic lubricating oil according to claim 1, which is one or a mixture of two or more selected from the group. 3. The synthetic lubricating oil according to claim 1, which is used as a refrigerating machine oil. 4. The synthetic lubricating oil according to claim 3, wherein the Freon refrigerant used is a hydrogen-containing Freon. 5. The synthetic lubricating oil according to claim 3, wherein the carbonic acid ester according to claim 1 is used as a base oil. 6. carbonate according to claim 1, as well as in the general formula R ₁ OR _{3 a} OR ₂ [wherein, R ₁ and R ₂ represents hydrogen or an alkyl group having 1 to 18 carbon atoms, R ₃ is Represents an alkylene group having 2 to 4 carbon atoms,
a represents an integer of 5 to 70], a polyoxyalkylene glycol or an ether thereof, [Wherein, R _{4 to} R ₆ represent hydrogen or an alkyl group having 1 to 18 carbon atoms, and R _{7 to} R ₉ represent an alkylene group having 2 to 4 carbon atoms;
b to d each represent an integer of 5 to 7], a polyoxyalkylene glycol glycerol ether represented by the following general formula: Wherein X ₁ is -OR ₁₂ or X ₂ is a group represented by Or Wherein each of R ₁₀ and R ₁₆ is an alkylene group having 1 to 8 carbon atoms, and R ₁₁ and R ₁₃ are each a group having 2 to 16 carbon atoms.
R ₁₂ and R ₁₇ each represent an alkyl group having 1 to ₁₅ carbon atoms; R ₁₄ and R ₁₅ each represent an alkyl group having 1 to 14 carbon atoms; e and f are each 0 or 1; 0
Represents an integer of up to 30], an ester represented by the general formula [Wherein X ₃ is a methyl group, an ethyl group, a propyl group and a general formula Wherein R _{18 to} R ₂₁ are linear alkyl groups having 3 to 11 carbon atoms, branched alkyl groups having 3 to 15 carbon atoms, and 6 Represents a group selected from cycloalkyl groups of from 1 to 12, wherein the proportion of linear alkyl groups is 60% or less based on all alkyl groups, and h represents an integer of 1 to 3]. [Wherein X ₄ and X ₅ may be the same or different and each represents a methyl group, an ethyl group, a propyl group and a general formula Represents any group selected from the group consisting of groups represented by the following formulas, wherein R _{22 to} R ₂₆ represent an alkyl group having 3 to 15 carbon atoms, and R ₂₇ represents a divalent hydrocarbon group having 1 to 8 carbon atoms. And i represents an integer of 1 to 5], a polyol dicarboxylic acid ester represented by the following general formula: Wherein R ₂₈ and R ₂₉ may be the same or different,
An alkyl group having 1 to 15 carbon atoms or 2 to 12 carbon atoms, respectively
Wherein R ₃₀ represents an alkylene group having 2 to 12 carbon atoms, j represents an integer of 0 to 30], and a carbonate represented by the following general formula: [Wherein X ₆ is a hydrogen atom or a general formula Wherein R _{31 to} R ₃₃ may be the same or different and each have an alkyl group having 1 to 12 carbon atoms,
Represents a cycloalkyl group of up to 12 or a neopentyl-type polyol residue having 5 to 30 carbon atoms and 3 to 8 hydroxyl groups,
₃₄ is an alkyl group having 1 to 6 carbon atoms, k is 1 or 2, l is 0 or 1, and k + 1 = 2, and m is 0 to 30 (m = 0 In this case, at least one of R ₃₁ and R ₃₂ represents a neopentyl-type polyol residue), and n represents an integer of 1 to 3, respectively.] A carbonate represented by the following formula: The refrigerating machine oil according to claim 3 or 4, wherein a base oil is a mixed oil of the oil. 7. The refrigerating machine oil according to claim 6, wherein the carbonate ester according to claim 1 is blended in an amount exceeding 50% by weight based on the total amount of the refrigerating machine oil. 8. At least one phosphorus compound selected from the group consisting of phosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorinated phosphate esters and phosphite esters, based on the total amount of the refrigerator oil. The refrigerating machine oil according to any one of claims 3 to 7, comprising 0.1 to 5.0% by weight as an essential component. 9. 0.1 to 5.0% by weight of at least one epoxy compound selected from the group consisting of a phenylglycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an epoxidized fatty acid monoester and an epoxidized vegetable oil, based on the total amount of the refrigerator oil. The refrigerating machine oil according to any one of claims 3 to 8, comprising as an essential component. 10. The method according to claim 10, wherein the total amount of the refrigerating machine oil is represented by a general formula: R ₃₅ —CH (COOH) ₂ and / or R ₃₆ —CH ₂ —COOH, wherein R ₃₅ and R ₃₆ may be the same or different;
The refrigerating machine oil according to any one of claims 3 to 9, which comprises, as an essential component, a carboxylic acid represented by the following formula: