JPH0913063A - Lubricating oil composition - Google Patents

Abstract

PURPOSE: To provide a lubricating oil composition which is free from the hydrolytic generation of a carboxylic acid, improved in thermal stability, electrical insulating properties, and economic efficiency, and reduced in hygroscopicity by incorporating an ester and a specific cyclic ketal or acetal and regulating the kinematic viscosity at 100 deg.C to a specific value. CONSTITUTION: A cyclic ketal or acetal (A) obtained from at least one polyhydric alcohol whose valence is an even number of 4 to 10 and at least one ketal or acetal of a carbonyl compound (derivative) represented by the formula (wherein R<1> is H, a 1-8C alkyl, or a 2-36C alkylene and R<2> is a 1-18C alkyl or a 2-36C alkylene) is mixed with an ester (F) between an alcohol selected from among a 2-50C di- to decahydric alcohol (B) or a 1-50C monohydric alcohol (C) and a 2-50C monocarboxylic acid (derivative) (D), that between the ingredient (C) and a 2-50C di- to decacarboxylic acid (derivative) (E), that obtained from the ingredients (B), (D) and (E) or that obtained from the ingredients (B), (C) and (E), in an (F)/(A) weight ratio of 10/99 to 99/1. Thus, a composition having a kinematic viscosity at 100 deg.C of 0.1-100mm<2> /s and having excellent compatibility with hydrofluorocarbons is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lubricating oil composition containing an ester compound having a kinematic viscosity at 100 ° C. of 0.1 to 100 mm ² / s and a cyclic ketal or cyclic acetal having a specific structure. Further, the present invention relates to a refrigerator working fluid composition using this lubricating oil composition.

[0002]

2. Description of the Related Art In recent years, the performance required for lubricating oil has become more severe as the demand for extension of the oil refreshing period and energy saving, and the high performance and miniaturization of mechanical devices. In particular, there is a strong demand for lubricating oils having excellent thermal stability and oxidation stability.
In addition, destruction of the ozone layer by carbon dioxide, carbon dioxide,
Global warming due to methane gas, acid rain and deforestation due to sulfur dioxide and NOx in exhaust gas, soil and lake pollution due to leakage of chemical substances, and other problems of global environmental pollution have been highlighted. That correspondence is required.

In order to meet the demand for improvement in thermal stability and oxidation stability, ethers such as polyalkylene glycols and esters such as aliphatic diesters and hindered esters have been developed, and engine oil, hydraulic oil, grease base oil, gear Used for oil, rolling oil, precision machine oil, etc.

However, ethers such as polyalkylene glycols have the drawbacks of high hygroscopicity and insolubility of conventionally used additives, because they have too high a polarity as compared with conventionally used mineral oils. ing. As an ether whose polarity is not so high as compared with this polyalkylene glycol, there is one synthesized from an alkyl halide and a polyol described in Japanese Patent Publication No. 1-29240, but a slight amount of halogen remains in the produced ether. , The thermal stability and the oxidative stability may be deteriorated.

Further, the ester also has a problem that it produces a carboxylic acid by hydrolysis and corrodes a metal, and has an advantage of lowering a friction coefficient due to its excellent adsorptivity to a metal. It has the drawback of inhibiting the effects of extreme pressure agents.

[0006] Therefore, there is a demand for a synthetic lubricating oil which is not so high in polarity, is excellent in thermal stability and oxidative stability, does not generate carboxylic acid due to hydrolysis, etc., and has low hygroscopicity.

On the other hand, the use of dichlorodifluoromethane (CFC12), which is used in refrigerators and car coolers for the protection of the ozone layer, is restricted from the viewpoint of the global environment.
It was decided that the use would be banned by the end of five years. Further, subsequently, the use of chlorodifluoromethane (HCFC22) used for room air conditioners and the like is about to be regulated. Therefore, as an alternative to CFC12 and HCFC22, hydrofluorocarbons that do not destroy the ozone layer, such as 1,1,1,2-tetrafluoroethane (H
FC134a), difluoromethane (HFC32) and pentafluoroethane (HFC125) have been developed.

However, hydrofluorocarbon is CF
Since the polarity is higher than that of C12 or HCFC22, if a lubricating oil such as naphthene-based mineral oil, poly α-olefin, or alkylbenzene that has been generally used as a refrigerating machine oil is used, the phase of these lubricating oil and hydrofluorocarbon is Poor solubility, causing two-layer separation at low temperature.
When two-layer separation occurs, oil return deteriorates, a thick oil film adheres to the vicinity of the condenser or evaporator as a heat exchanger to hinder heat transfer, and also causes serious defects such as poor lubrication and foaming at startup. Cause of. Therefore, the conventional refrigerating machine oil cannot be used as a refrigerating machine oil under these new refrigerant atmospheres. Therefore, there is a need for a lubricating oil that has good compatibility with hydrofluorocarbons.

Also, regarding the lubricity, CFC12 and HC
In FC22, there was an effect that it partially decomposed to generate hydrogen chloride, and this hydrogen chloride reacted with the friction surface to form a chloride film and improve the lubricity. However, since such effects cannot be expected for hydrofluorocarbons that do not contain chlorine atoms, refrigerating machine oils used with hydrofluorocarbons are required to have lubricating oils with even better lubricity than conventional ones.

Further, the refrigerating machine oil used together with hydrofluorocarbon must have good thermal stability in the presence of hydrofluorocarbon.

In addition to this, in compression type refrigerators such as electric refrigerators and room air conditioners, there are organic materials used for motors such as insulating materials and enameled wires, so that a working fluid consisting of hydrofluorocarbon and refrigerator oil is used. It is necessary that they do not adversely affect these organic materials and that they also have good electrical insulation.

Hydrofluorocarbons such as 1,1,1,
As a refrigerating machine oil that can be used with 2-tetrafluoroethane (HFC134a), US Pat. No. 4,755,316
(Japanese Patent Publication No. 2-502385) and Japanese Unexamined Patent Publication No.
-14894 (European Patent No. 377,122),
JP-A-2-182780 (WO90 / 05172)
No.) and the like, polyalkylene glycol compounds are disclosed.

Since the polyalkylene glycol-based compound has a higher polarity than the naphthene-based mineral oil, the compatibility with HFC134a at low temperature is certainly good. However,
As described in U.S. Pat. No. 4,755,316, the polyalkylene glycol-based compound has a problem that two-phase separation occurs when the temperature rises. Further, the polyalkylene glycol compound has some other problems. One is that it has poor electrical insulation. This is a very big problem and cannot be used in refrigerators for electric refrigerators and refrigerators for air conditioners in which the motor is built in the compressor. These compounds have been suggested for use in such car-free air conditioning applications. Another problem is that it is highly hygroscopic. Due to the water content in the polyalkylene glycol compound, the PET film or the like, which is an organic material, is hydrolyzed. By reducing the number of ether bonds per unit weight, electrical insulation can be improved and hygroscopicity can be reduced, but compatibility with hydrofluorocarbon becomes poor. Thus, an ether compound such as polyalkylene glycol cannot achieve both compatibility with hydrofluorocarbon, electrical insulation and hygroscopicity.

Ester-based compounds and carbonate-based compounds have been developed in order to improve the problems of polyalkylene glycol-based compounds such as electric insulation and hygroscopicity. For example, 1,1,1,2-tetrafluoroethane (HFC13
As a refrigerating machine oil that can be used together with 4a), a mixed oil of a polyalkylene glycol compound and an ester oil is disclosed in US Pat. No. 4,851,144 (JP-A-2-276894) and JP-A-2-158693.
Japanese Patent Publication No. 3-505602 (WO90 / 12849)
), JP-A-3-128991, JP-A-3-12
Ester oils are disclosed in JP-A-8992, JP-A-3-88892 and JP-A-3-179091. JP-A-2-132178, JP-A-3-149
295 and European Patent 421,298 disclose carbonate oils.

Ester-based compounds and carbonate-based compounds have excellent compatibility with hydrofluorocarbons and also have excellent thermal stability in the presence of hydrofluorocarbons. Compared with polyalkylene glycol-based compounds, it has extremely excellent electric insulation and also has considerably low hygroscopicity.
However, compared with CFC12-mineral oil system, which is a conventional working fluid, both hydrofluorocarbon-ester oil system and hydrofluorocarbon-carbonate oil system have higher polarities of both freon and oil, and are likely to contain water.
Therefore, there is a problem that the ester hydrolyzes to generate a carboxylic acid, and the generated carboxylic acid corrodes a metal to cause abrasion. In addition, the carbonate oil causes hydrolysis, produces non-condensable carbon dioxide, and causes a problem that the refrigerating capacity is lowered.

Particularly in a room air conditioner, the refrigerant is exclusively filled in the field, so it is almost impossible to prevent the mixture of water unlike the case of a refrigerator which is filled in a factory. -Carbonate oil system is concerned about the reliability of room air conditioners.

Further, as a polyether compound having improved electrical insulation of polyalkylene glycol, WO93 /
Japanese Patent No. 24435 discloses a polyvinyl ether compound. This polyvinyl ether-based compound is obtained by polymerizing a vinyl ether-based monomer and hydrogenating it, and it is disclosed that this compound has good compatibility with hydrofluorocarbon and also has good electrical insulation. . However, since polyvinyl ether compounds are synthesized by the polymerization method and the products have different molecular weights, some high molecular weight compounds may cause clogging of the capillary tube, and compatibility with hydrofluorocarbons. May worsen. In addition, it is difficult to say that the post-treatment method is complicated and the unstable vinyl ether-based monomer is used as a raw material, and that the yield is not necessarily high. In particular, those having a low degree of polymerization (polymerization degree of around 6) have a drawback that the yield is low. In addition, vinyl ether-based monomers are difficult to obtain depending on the structure,
It is expensive.

On the other hand, examples in which a cyclic ketal or a cyclic acetal is used as a working fluid of a refrigerator are described in JP-A-4-320498 and JP-A-6-57243.
The former is a ketal or acetal obtained from a monohydric alcohol or a dihydric alcohol and a ketone or an aldehyde, and it is stated that the ketal or acetal is blended with an ester or polyalkylene glycol-based synthetic lubricating oil, and the latter is an intramolecular compound. It is a derivative of ester or carbonate of glycerin, trimethylolethane, trimethylolpropane, pentaerythritol containing a ketal or acetal group. The former acetals and ketals have the drawbacks of low molecular weight, low boiling point and flash point, and also low viscosity. Therefore,
When mixed with an ester or an ether such as polyalkylene glycol, there is a drawback that the viscosity and the flash point are remarkably lowered. Further, the latter acetal and ketal have a drawback that they are expensive because they undergo two or more reaction steps in the production, and some have a drawback that they are difficult to obtain with high purity. Further, the latter acetals and ketals specifically disclosed include the problem that two or more ether bonds are contained in the molecule and the improvement of electrical insulation is not sufficient.

As described above, the hydrofluorocarbon-polyalkylene glycol type developed up to now has a problem in hygroscopicity and electric insulation, and the hydrofluorocarbon-ester type and the hydrofluorocarbon-carbonate type have problems in hydrolysis resistance. , All systems are conventional CFC
Compared to the 12-mineral oil type, it tends to contain water, causes deterioration of thermal stability, deterioration of organic materials, corrosion and wear of metals, and is not satisfactory as a working fluid for a refrigerator. Further, since the polyvinyl ether compound has a high molecular weight compound in part because it has a molecular weight distribution, it has a drawback that the compatibility is lowered, and there is a drawback that the raw material species are limited and the cost becomes high. In addition, the ketals and acetals that have been reported so far have the drawbacks of low molecular weight and high price.

Therefore, an object of the present invention is to provide an inexpensive synthetic lubricating oil which is excellent in thermal stability and oxidative stability, does not generate carboxylic acid due to hydrolysis, has low hygroscopicity, Another object of the present invention is to provide an inexpensive refrigerator working fluid composition that has excellent compatibility with hydrofluorocarbons, electrical insulation, hygroscopicity, etc., does not generate carboxylic acid due to hydrolysis, etc.

[0021]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a composition containing a cyclic ketal or a cyclic acetal compound having a specific structure and an ester compound, Excellent compatibility with hydrofluorocarbons, excellent electrical insulation, excellent lubricity and heat resistance, excellent hygroscopicity, and the production of carboxylic acid from ester is significantly suppressed by the coexistence of ketal and acetal. It was discovered that the composition could be an extremely excellent lubricating oil composition, and further research was conducted to complete the present invention.

That is, the gist of the present invention is as follows: (1) The kinematic viscosity at 100 ° C. is 0.1 to 100 mm.
A lubricating oil composition comprising an ester compound of ² / s and a cyclic ketal or a cyclic acetal, (2) the cyclic ketal or the cyclic acetal has an even valence of 4 to 10 1 of polyhydric alcohol
More than one species, and general formula (I)

[0023]

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(Wherein R ¹ represents a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms, and R ² represents a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms. Or R ¹ and R ² together represent an alkylene group having 2 to 36 carbon atoms) or one or more of a ketal or acetal which is a reactive derivative thereof. The lubricating oil composition according to (1) above, which is obtained, (3) wherein the cyclic ketal or cyclic acetal is at least one polyhydric alcohol having an even valence of 4 to 8 and a general formula ( II)

[0025]

[Chemical 6]

(In the formula, R ³ is a hydrogen atom or a carbon number of 1 to
12 straight-chain, branched, or cyclic alkyl groups are shown,
R ⁴ represents a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ together represent an alkylene group having 2 to 13 carbon atoms. The total carbon number of R ³ and R ⁴ is 1 to 13. ) A lubricating oil composition according to the above (1), which is obtained from one or more of a carbonyl compound represented by the formula (1) or a reactive derivative thereof, a ketal or an acetal, (4) the polyhydric alcohol has an ether bond. The lubricating oil composition according to the above (2) or (3), which has no ether or one ether bond, (5) the cyclic ketal or cyclic acetal has a 1,3-dioxolane structure and / or 1 The lubricating oil composition according to any one of (1) to (4), which contains a 1,3-dioxane structure, (6) the cyclic ketal or cyclic acetal is a tetravalent or hexavalent saturated aliphatic group having 4 to 20 carbon atoms. One of an alcohol and a carbonyl compound represented by the general formula (II) or a ketal or acetal which is a reactive derivative thereof.
(4) or (5), which is obtained from one or more species
(7) The cyclic ketal or cyclic acetal has the formula (III) or (IV)

[0027]

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(In the formula, R ³ represents a hydrogen atom or a carbon number of 1 to 1.
12 straight-chain, branched, or cyclic alkyl groups are shown,
R ⁴ represents a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ together represent an alkylene group having 2 to 13 carbon atoms. The total carbon number of R ³ and R ⁴ is 1 to 13. (8) The lubricating oil composition according to the above (1), wherein the cyclic ketal or cyclic acetal has the formula (V) or (VI)

[0029]

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(In the formula, R ³ is a hydrogen atom or a carbon number of 1 to
12 straight-chain, branched, or cyclic alkyl groups are shown,
R ⁴ represents a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ together represent an alkylene group having 2 to 13 carbon atoms. The total carbon number of R ³ and R ⁴ is 1 to 13. (1) The lubricating oil composition according to (1) above, wherein the mixing ratio of the ester compound and the cyclic ketal or cyclic acetal in the lubricating oil composition is an ester compound / cyclic ketal, cyclic acetal = 10. / 90-99 /
The lubricating oil composition according to any one of (1) to (8), which is 1 (weight ratio), (10) the ester compound is A) a C2 to C2 to C2 to C10 polyhydric alcohol or carbon number. An ester obtained from a monohydric alcohol having 1 to 50 and a monohydric carboxylic acid having 2 to 50 carbon atoms or a derivative thereof, B) a monohydric alcohol having 1 to 50 carbon atoms, and 2 to 5 carbon atoms
An ester obtained from a 0 to 2 to 10 valent polycarboxylic acid or a derivative thereof, C) a 2 to 10 valent polyalcohol having 2 to 50 carbon atoms,
A monovalent carboxylic acid having 2 to 50 carbon atoms or a derivative thereof,
And an ester obtained from a C2 to C2 to C10 polyvalent carboxylic acid or derivative thereof, and D) C2 to C2 to C10 polyhydric alcohol and C1 to C1 A polyhydric alcohol and 2 to 50 carbon atoms
2. A lubricating oil composition according to any one of (1) to (9) above, which is selected from the group consisting of an ester obtained from a divalent to 10-valent polycarboxylic acid or a derivative thereof. (11) The ester compound is A ′) a C 2-10 divalent to polyvalent aliphatic polyhydric alcohol or a C 1-10 saturated aliphatic monohydric alcohol, and a C 2-9 straight chain or An ester obtained from a branched chain saturated aliphatic monovalent carboxylic acid or a derivative thereof, B ′) a saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms, and a divalent saturated hexavalent aliphatic group having 2 to 10 carbon atoms An ester obtained from a polycarboxylic acid or a derivative thereof, C ′) a C 2 to C 2-6 aliphatic polyhydric alcohol, and a C 2-9 linear or branched saturated aliphatic 1
Carboxylic acid or its derivative, and carbon number 2 to 1
0, an ester obtained from a linear or branched saturated aliphatic divalent carboxylic acid or a derivative thereof, and D ′) a linear or branched saturated aliphatic dihydric alcohol having 2 to 10 carbon atoms and the number of carbon atoms 1 to 10 linear or branched saturated aliphatic monohydric alcohols, and esters obtained from C 2 to C 2-6 saturated aliphatic polyvalent carboxylic acids or derivatives thereof, selected from the group consisting of: (1) A lubricating oil composition according to any one of (1) to (9), (12) A refrigerating machine oil containing the lubricating oil composition according to (11) above, and a refrigeration containing hydrofluorocarbon. Machine working fluid composition, and (13) Hydrofluorocarbon and refrigerating machine oil,
Hydrofluorocarbon / Refrigerator oil = 50/1 to 1 /
The refrigerator working fluid composition according to the above (12), which is contained at 20 (weight ratio).

The present invention will be described in detail below. 1. Regarding the cyclic ketal and cyclic acetal, the polyhydric alcohol relating to the cyclic ketal or the cyclic acetal used in the present invention is a polyhydric alcohol having an even valence of 4 to 10 and is preferably tetravalent, hexavalent or octavalent. And more preferably tetravalent or hexavalent. In the present specification, the polyhydric alcohol relating to the cyclic ketal or the cyclic acetal refers to the polyhydric alcohol when the cyclic ketal or the cyclic acetal is formed from the polyhydric alcohol and a carbonyl compound or the like. If it has a valence of more than 10, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, and the viscosity of the obtained lubricating oil composition becomes too high. If it is less than tetravalent, the molecular weight will be too low, and the boiling point and flash point of the resulting lubricating oil composition will be too low, which is not preferable. If the valence of the polyhydric alcohol is odd, unreacted hydroxyl groups will always remain and the viscosity will increase, which is not preferable. When used as a refrigerator working fluid,
If the hydroxyl group remains, the compatibility with the hydrofluorocarbon deteriorates, which is not preferable. By making the unreacted hydroxyl group into an ether structure by an alkylation reaction, the viscosity and compatibility with hydrofluorocarbon can be improved, but this is not preferable because the number of reaction steps in production increases.
In addition, this makes it difficult to obtain a highly pure product.

Specifically, erythritol, diglycerin, arabinose, ribose, sorbitol, mannitol, galactitol, iditol, talitol, allitol, 4,7-dioxadecane-1,2,9,10-tetraol, 5-methyl -4,7-Dioxadecane-1,2,9,10-tetraol, 4,7,10- Trioxatridecane-1,2,12,13-tetraol, 1,6-dimethoxyhexane-2,3 Polyhydric alcohols such as 1,4,5-tetraol and 3,4-diethoxyhexane-1,2,5,6-tetraol, pentaerythritol, ditrimethylolethane, ditrimethylolpropane, dipentaerythritol, tripenta Erythritol, 2,9-diethyl-2,9-dihydroxymethyl-4,7-dioxadecane
-1,10-diol, 2,12-diethyl-2,12-dihydroxymethyl-5,8-dimethyl-4,7,10-trioxatridecane-1,13
-A hindered alcohol such as a diol.

Of these, 4,7-dioxadecane-1,2,9,10-
Tetraol, 5-methyl-4,7-dioxadecane-1,2,9,1
0-tetraol, 4,7,10-trioxatridecane-1,2,1
2,13-Tetraol, 1,6-dimethoxyhexane-2,3,4,5
-Tetraol, 3,4-diethoxyhexane-1,2,5,6-tetraol, 2,9-diethyl-2,9-dihydroxymethyl-
4,7-Dioxadecane-1,10-diol, 2,12-diethyl-
Polyhydric alcohols with two or more ether bonds, such as 2,12-dihydroxymethyl-5,8-dimethyl-4,7,10-trioxatridecane-1,13-diol, are easy to obtain industrially. Rather, it requires several steps to manufacture, which is expensive and is not preferable.

The polyhydric alcohol relating to the cyclic ketal or cyclic acetal used in the present invention has 4 to 2 carbon atoms.
5 and preferably 4 to 20. If the carbon number exceeds 25, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, and the viscosity of the obtained lubricating oil composition becomes too high. If the carbon number is less than 4, the molecular weight becomes too low, and the resulting lubricating oil composition has low boiling point and flash point, which is not preferable.

The polyhydric alcohol relating to the cyclic ketal or cyclic acetal used in the present invention is a saturated aliphatic alcohol. An unsaturated bond is not preferable because the resulting lubricating oil composition has poor thermal stability.

The polyhydric alcohol relating to the cyclic ketal or cyclic acetal used in the present invention is most preferably one having no ether bond in the molecule from the viewpoint of having a good electric insulating property. Moreover, even if it has an ether bond, one is preferable. If two or more are present, the electrical insulation will be poor, so it is not preferable when the lubricating oil composition of the present invention is used as an electrical insulating oil, a working fluid for a refrigerator, or the like.
Specific examples of the polyhydric alcohol having no ether bond in the molecule include erythritol, sorbitol, mannitol, galactitol, iditol, talitol, allitol, pentaerythritol, etc., and specific examples of the polyhydric alcohol having one ether bond. Examples include diglycerin, ditrimethylolpropane, ditrimethylolethane and the like.

When the lubricating oil composition of the present invention is used as a working fluid for a refrigerator, the valency of the polyhydric alcohol related to the cyclic ketal or cyclic acetal is preferably 4, 6, or 8. It is preferably tetravalent or hexavalent. If the valence of the polyhydric alcohol related to the cyclic ketal or cyclic acetal is higher than 8, the viscosity will be too high for a refrigerating machine oil, the viscosity of the resulting lubricating oil composition will be too high, and the compatibility with hydrofluorocarbons will be high. Is not preferable because it becomes worse. Further, if the valence of the polyhydric alcohol relating to the cyclic ketal or the cyclic acetal is less than tetravalent, the molecular weight becomes too low, and the boiling point and the flash point of the obtained lubricating oil composition become low, which is not preferable.

The polyhydric alcohol having a cyclic ketal or cyclic acetal preferably has 4 to 20 carbon atoms, more preferably 4 to 15 carbon atoms, and particularly preferably 4 to 1 carbon atoms.
0. If the polyhydric alcohol related to the cyclic ketal or cyclic acetal has more than 20 carbon atoms, the resulting lubricating oil composition has poor compatibility with hydrofluorocarbons, which is not preferable. If the number of carbon atoms of the polyhydric alcohol relating to the cyclic ketal or cyclic acetal is less than 4, the molecular weight becomes too low, and the boiling point and flash point of the resulting lubricating oil composition become low, which is not preferable. Further, when an alcohol having a high symmetry such as pentaerythritol is used, the melting point of the obtained cyclic ketal or cyclic acetal becomes high, so that the obtained lubricating oil composition has a high melting point and is used as a refrigerator working fluid. Is not preferable.

The carbonyl compound relating to the cyclic ketal or cyclic acetal used in the present invention is a ketone or aldehyde represented by the general formula (I). The ketone or aldehyde represented by the general formula (I) has 2 to 3 carbon atoms.
7, preferably 2 to 25 carbon atoms, and more preferably 2 to 17 carbon atoms. If the carbon number exceeds 37, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, and the viscosity of the obtained lubricating oil composition becomes too high, which is not preferable.

R ¹ represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, preferably a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms. And more preferably a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 8 carbon atoms. R ² represents a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms, preferably 1 to 1 carbon atoms
12 straight-chain, branched, or cyclic alkyl groups are shown,
More preferably, it represents a linear, branched, or cyclic alkyl group having 1 to 8 carbon atoms. Alternatively, R ¹ and R ² together represent an alkylene group having 2 to 36 carbon atoms, preferably 2 to 24 carbon atoms, more preferably 2 to 16 carbon atoms. Also, R ¹
And R ² may be the same or different.

When the carbon number of R ¹ or R ² exceeds 18, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, and the viscosity of the obtained lubricating oil composition becomes too high, which is not preferable. If the alkylene group formed by R ¹ and R ² together has more than 36 carbon atoms, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, and the viscosity of the obtained lubricating oil composition becomes too high. Therefore, it is not preferable.

Specifically, as the ketone in which R ¹ and R ² are alkyl groups, acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl isopropyl ketone, methyl butyl ketone, ethyl propyl ketone, methyl-sec-butyl ketone, Methyl isobutyl ketone, ethyl isopropyl ketone, methyl tert-butyl ketone, methyl amyl ketone, ethyl butyl ketone, diisopropyl ketone, methyl isoamyl ketone, dipropyl ketone, isopropyl propyl ketone, methyl neopentyl ketone, ethyl tert-butyl ketone, methyl hexyl Ketone, ethylpentylketone, 6-methyl-2-heptanone, 4-methyl-3-heptanone, 2-methyl-3-heptanone, 5-methyl-3-heptanone, methylcyclohexylketone, methylheptylketone, ethi Lehexyl ketone, dibutyl ketone, diisobutyl ketone, methyl octyl ketone, methyl nonyl ketone, dipentyl ketone,
Methyl decyl ketone, methyl undecyl ketone, dihexyl ketone, 5- (2 ', 2', 5'-trimethylcyclohexyl) -2-pentanone, 6,10-dimethyl-2-undecane, methyl tridecyl ketone, diheptyl ketone , Methyl tetradecyl ketone, dioctyl ketone, methyl pentadecyl ketone, diisooctyl ketone, methyl hexadecyl ketone, 6,10,14-trimethyl-2-pentadecane, dinonyl ketone, methylheptadecyl ketone, methyl octadecyl ketone, didecyl ketone, etc. can give.

Further, as the ketone in which R ¹ and R ² are combined to form an alkylene group, cyclopropanone, cyclobutanone, cyclopentanone, cyclohexanone,
2-methylcyclopentanone, 3-methylcyclopentanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, cycloheptanone,
2,4-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, cyclooctanone, 3-ethylcyclohexanone, 4-ethylcyclohexanone, 3,5,5-trimethylcyclohexanone, 2-tert-butylcyclohexanone, 4-te
Examples include rt-butylcyclohexanone, 2-isopropyl-4-methylcyclohexanone, cyclodecanone and cyclododecanone.

As the aldehyde in which R ¹ is a hydrogen atom, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, isovaleraldehyde, 2-methylbutyraldehyde, caproaldehyde, 2-methylpentanal, 3-methylpentanal, 4-methylpentanal, 2-ethylbutanal, 2,3-dimethylbutanal, 3,3-dimethylbutanal, cyclopentylacetaldehyde, heptanal, 2-methylhexanal, 3-methylhexanal, 4 -
Methylhexanal, 5-methylhexanal, 2-ethylpentanal, cyclohexylaldehyde, octanal, 2-methylheptanal, 2-ethylhexanal, 2-
Propyl pentanal, 2,2,4-trimethyl pentanal, nonyl aldehyde, 3,5,5-trimethyl hexanal, decyl aldehyde, isodecyl aldehyde, 3,7-dimethyl octanal, 2-isopropyl-5-methyl hexanal, Undecanal, dodecanal, tridecyl aldehyde, isotridecyl aldehyde, hexadecanal, isooctadecanal, octadecanal, 2-methyloctadecanal and the like can be mentioned.

When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, a ketone or an aldehyde represented by the general formula (II) in the general formula (I) is preferable. The ketone or aldehyde represented by the general formula (II) has 2 to 14 carbon atoms, preferably 2 to 11 carbon atoms, and more preferably 2 to 6 carbon atoms. When the number of carbon atoms exceeds 14, compatibility of the resulting lubricating oil composition with hydrofluorocarbon is deteriorated, which is not preferable.

R ³ represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, preferably a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. And more preferably a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms. R ⁴ represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms
Is a linear, branched or cyclic alkyl group, more preferably a linear, branched or cyclic alkyl group having 1 to 5 carbon atoms. Alternatively, R ³ and R ⁴ together represent an alkylene group having 2 to 13 carbon atoms, preferably an alkylene group having 4 to 10 carbon atoms, and more preferably an alkylene group having 4 to 5 carbon atoms. The total carbon number of R ³ and R ⁴ is 1 to 13, preferably 1 to 10, and more preferably 1 to 5.

When the carbon number of R ³ or R ⁴ exceeds 12, the compatibility of the resulting lubricating oil composition with hydrofluorocarbon is deteriorated, which is not preferable. In addition, the number of carbon atoms of the alkylene group formed by R ³ and R ^{4 taken} together is 1
When it exceeds 3, compatibility of the resulting lubricating oil composition with hydrofluorocarbon deteriorates, which is not preferable. Further, if the total carbon number of R ³ and R ⁴ exceeds 13, the compatibility of the resulting lubricating oil composition with hydrofluorocarbon is deteriorated, which is not preferable.

From the compatibility of the resulting lubricating oil composition with hydrofluorocarbon, the alkyl groups of R ³ and R ⁴ preferably have a branched or cyclic structure rather than a linear structure, and R
It is preferred that ³ and R ⁴ do not form together rather than form an alkylene group.

The ketones represented by the general formulas (I) and (II) used in the lubricating oil composition of the present invention are high temperature decarboxylation dimerization reaction of fatty acids, catalytic oxidation reaction of olefins (Wacker method) and secondary reaction. It can be easily obtained by oxidation of alcohol, dehydrogenation or oxidation of cycloalkane. In the case of the Wacker method, the obtained ketone can be separated and purified into a single product by precision distillation.

The aldehydes represented by the general formulas (I) and (II) used in the lubricating oil composition of the present invention include, for example, dehydrogenation reaction of fatty alcohol, hydroformylation reaction of olefin (oxo method), and fatty acid chloride. It can be easily obtained by direct reduction of Rosemund or direct fatty acid. In the case of the oxo method, a linear product and a branched product are produced, but they can be separated and purified into a single product by precision distillation.

The reactive derivative of the carbonyl compound used in the synthesis of the cyclic ketal or cyclic acetal of the present invention is easily synthesized from the above-mentioned ketone, aldehyde and lower alcohol having 1 to 6 carbon atoms by an acid catalyst. There are ketals and acetals. Carbon number 1-6
Specific examples of lower alcohols include, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, amyl alcohol, isoamyl alcohol, neopentyl alcohol, 1-methylbutanol, 1,1-dimethyl. Propanol, 1-ethylpropanol, hexanol,
Examples thereof include isohexanol, 2-ethylbutanol, 1-methylamyl alcohol, 1,3-dimethylbutanol and 1-ethylbutanol.

The cyclic ketal and cyclic acetal used in the lubricating oil composition of the present invention can be obtained as follows. The reaction between the polyhydric alcohol and the ketone is a ketalization reaction, and this reaction uses an acid catalyst such as paratoluenesulfonic acid, methanesulfonic acid, or sulfuric acid as a catalyst in an amount of 0.05 to 10 mol% with respect to the polyhydric alcohol, Preferably it is 0.1-7.0 mol%, More preferably, it is 0.5-5.0.
Performed using mol%. This reaction is carried out without solvent or in an inert solvent such as xylene, toluene, benzene, octane, isooctane, heptane, hexane, cyclohexane, pentane, ligroin, petroleum ether, etc., or in a mixed solution thereof, at the boiling point of the ketone to be used. It depends 4
At a temperature of 0 to 160 ° C, preferably 60 to 100 ° C,
It is preferable to carry out while removing the produced water. In some cases, it is effective to carry out the reaction under reduced pressure. If the temperature is lower than this, the reaction does not proceed, and if the temperature is higher than this, coloring is severe and side reactions occur, which is not preferable. Further, under a nitrogen flow condition, either under a nitrogen atmosphere or under a dry air atmosphere may be used. The reaction time may vary depending on various conditions, but is usually preferably 5 to 200 hours. The obtained cyclic ketal is neutralized, then subjected to pretreatment such as filtration and washing, and then treated with clay, crystallization,
It can be purified by an operation such as distillation.

The reaction between the polyhydric alcohol and the aldehyde is an acetalization reaction, and this reaction uses an acid catalyst such as p-toluenesulfonic acid, methanesulfonic acid or sulfuric acid as a catalyst with respect to the polyhydric alcohol of 0.01. ˜5.0 mol%, preferably 0.05 to 3.0 mol%, more preferably 0.1 to 2.0 mol%. This reaction is carried out without solvent or in an inert solvent such as xylene, toluene, benzene, octane, isooctane, heptane, hexane, cyclohexane, pentane, ligroin, petroleum ether, etc., or in a mixed solvent thereof to the boiling point of the aldehyde used. 20 to 130 ° C., preferably 4
It is preferable to carry out at a temperature of 0 to 100 ° C. while removing the produced water. In some cases, it is also effective to carry out the reaction under reduced pressure. If the temperature is lower than this, the reaction will not proceed,
If it is too high, coloring is severe and side reactions occur, which is not preferable. Also,
Under a nitrogen flow condition, either a nitrogen atmosphere or a dry air atmosphere may be used. The reaction time may vary depending on various conditions, but is usually preferably 1 to 30 hours. The obtained cyclic acetal is neutralized and then subjected to pretreatments such as filtration and washing,
Then, it can be purified by operations such as clay treatment, crystallization and distillation.

The reaction between the polyhydric alcohol and the ketal, which is a reactive derivative of the ketone, is a transketal reaction, and this reaction uses an acid catalyst such as paratoluenesulfonic acid, methanesulfonic acid or sulfuric acid as a catalyst. 0.05 to 10 mol% with respect to alcohol, preferably 0.1 to
The amount is 7.0 mol%, and more preferably 0.5 to 5.0 mol%. This reaction is solvent-free, or xylene, toluene, benzene, octane, isooctane, heptane,
In an inert solvent such as hexane, cyclohexane, pentane, ligroin or petroleum ether, or in a mixed solvent thereof, depending on the boiling points of the ketal used and the lower alcohol produced, 40 to 160 ° C, preferably 60 to 160 ° C.
It is preferable to carry out at a temperature of 130 ° C. while removing the produced lower alcohol. In some cases, it is also effective to carry out the reaction under reduced pressure. If the temperature is lower than this, the reaction does not proceed, and if the temperature is higher than this, coloring is severe and side reactions occur, which is not preferable. Further, under a nitrogen flow condition, either under a nitrogen atmosphere or under a dry air atmosphere may be used. The reaction time may vary depending on various conditions, but is usually preferably 5 to 200 hours. The obtained cyclic ketal can be purified by neutralization, pretreatment such as filtration and washing, and then operations such as clay treatment, crystallization and distillation.

The reaction between the polyhydric alcohol and acetal, which is a reactive derivative of aldehyde, is a transacetal reaction, and this reaction uses an acid catalyst such as paratoluenesulfonic acid, methanesulfonic acid, or sulfuric acid as a polyhydric alcohol. 0.01 to 5.0 mol%, preferably 0.05 to 3.0 mol%, more preferably 0.1 to 2.
It is carried out using 0 mol%. This reaction is solvent-free, or xylene, toluene, benzene, octane, isooctane,
In an inert solvent such as heptane, hexane, cyclohexane, pentane, ligroin and petroleum ether, or in a mixed solvent thereof, depending on the boiling point of the aldehyde used, the temperature is 20 to 150 ° C, preferably 50 to 130 ° C. Then, it is preferable to carry out while removing the lower alcohol produced. In some cases, it is also effective to carry out the reaction under reduced pressure. If the temperature is lower than this, the reaction does not proceed, and if the temperature is higher than this, coloring is severe and side reactions occur, which is not preferable. Further, under a nitrogen flow condition, either under a nitrogen atmosphere or under a dry air atmosphere may be used. The reaction time may vary depending on various conditions,
Usually, 1 to 30 hours is preferable. The obtained cyclic acetal can be purified by neutralization, pretreatment such as filtration and washing, and subsequent operations such as clay treatment, crystallization and distillation.

The ratio of a ketone or a ketal which is a reactive derivative of a ketone to be reacted with a polyhydric alcohol, or an aldehyde or an acetal (hereinafter abbreviated as a carbonyl compound) which is a reactive derivative of an aldehyde is based on 1 mol of the polyhydric alcohol. The carbonyl compound is A / 2 mol (A is the valence of the polyhydric alcohol). In order to accelerate the reaction rate, it is also effective to carry out the reaction by using an excess of carbonyl compound over A / 2 mol and recover the excess carbonyl compound after the reaction is completed.

The cyclic ketal or cyclic acetal used in the lubricating oil composition of the present invention is a reaction of at least one polyhydric alcohol with at least one ketone or a ketal which is a reactive derivative of a ketone, or an aldehyde or an aldehyde. It can be obtained by reacting with an acetal which is a sex derivative. Further, the cyclic ketal or cyclic acetal obtained here can be mixed and used. For example, a cyclic ketal obtained from 1 mol of sorbitol and 3 mol of methyl ethyl ketone (viscosity at 40 ° C. 63.1).
mm ² / s), a cyclic ketal obtained from 1 mol of diglycerin and 2 mol of methyl ethyl ketone (viscosity at 40 ° C. 7.6)
9 mm ² / s) can be synthesized individually and mixed to adjust the desired viscosity. As a concrete example,
The lubricating oil of VG22 can be obtained by mixing 1 mol of cyclic ketal obtained from 1 mol of sorbitol and 3 mol of methyl ethyl ketone and 1 mol of cyclic ketal obtained from 1 mol of diglycerin and 2 mol of methyl ethyl ketone. Alternatively, 1 mol of sorbitol, 1 mol of diglycerin and 5 mol of methyl ethyl ketone can be reacted to obtain the above mixture. Also, by reacting 1 mol of sorbitol with 2 kinds of ketones or aldehydes, for example, 2 mol of 3,5,5-trimethylhexanal and 1 mol of methyl ethyl ketone,
It is also possible to obtain the cyclic ketal or cyclic acetal used in the lubricating oil composition of the present invention.

Further, it is preferable that the amount of unreacted hydroxyl groups present in the obtained cyclic ketal or cyclic acetal is small, and such unreacted hydroxyl groups are on average 20 with respect to the number of hydroxyl groups of the polyhydric alcohol as the raw material. % Or less, preferably 10% or less, more preferably 5% or less, particularly preferably 3% or less. If more than 20% of unreacted hydroxyl groups remain, the viscosity becomes too high, and the boiling point and the flash point become too low, which is not preferable.

When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, it is preferable that the amount of unreacted hydroxyl groups in the cyclic ketal or cyclic acetal is as small as possible.
% Or less, preferably 5% or less, more preferably 3% or less, particularly preferably 2% or less, most preferably 1% or less. If more than 10% of unreacted hydroxyl groups remain, the compatibility with hydrofluorocarbons and the electrical insulation are poor, which is not preferable. Further, when the lubricating oil composition of the present invention is used as an electric insulating oil or a base oil of a working fluid of a refrigerator, a polyhydric alcohol related to a cyclic ketal or a cyclic acetal has a structure having no ether bond, It becomes high and is preferable. Therefore, it is better to use a cyclic ketal or a cyclic acetal obtained from a hexavalent alcohol such as sorbitol, mannitol, galactitol, iditol, talitol, and allitol, or a polyhydric alcohol such as erythritol, and an ether such as diglycerin or ditrimethylolpropane. It is more preferable to use a cyclic ketal or a cyclic acetal obtained from an alcohol having one bond.

When the lubricating oil composition of the present invention is used as an electric insulating oil or a base oil for a working fluid of a refrigerator, the cyclic ketal or cyclic acetal used is a 1,3-dioxolane structure and / or a 1,3-dioxane structure. It is preferable to include the above because it has high electric insulation. Among these, those containing a 1,3-dioxolane structure are particularly preferable. Therefore, erythritol, diglycerin, sorbitol, mannitol,
It is preferable to use an alcohol having a hydroxyl group at an adjacent position such as galactitol, iditol, talitol, and allitol.

When a hexahydric alcohol such as sorbitol, mannitol, galactitol, iditol, talitol or allitol is used, the cyclic ketal or cyclic acetal represented by the formula (III) (formula IIIa and formula IIIb) can be obtained. Formula III with three 1,3-dioxolane structures
A is preferable because it has higher electric insulation. Also,
When erythritol is used, formula (IV) (formula IVa and formula
The cyclic ketal or cyclic acetal shown in IVb) is obtained, but the formula IVa having two 1,3-dioxolane structures is
It is preferable because the electric insulating property is improved. Hexahydric alcohols such as sorbitol, mannitol, galactitol, iditol, taritol, and allitol, and erythritol can be reacted with ketones or ketals to give formula IIIa,
The cyclic ketal of the formula IVa is likely to be formed, and the cyclic acetal of the formula IIIb or the formula IVb is easily produced when reacted with an aldehyde or an acetal. Therefore, it is preferable to react these alcohols with ketones or ketals.

When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, even if the valency of the polyhydric alcohol relating to the cyclic ketal or cyclic acetal is an even number, the hexavalent one represented by the formula (III) is used. Cyclic ketals or acetals of alcohols, or cyclic ketals or acetals obtained from tetrahydric alcohols such as erythritol, diglycerin, and ditrimethylolpropane shown in formulas (IV) to (VI) have compatibility with hydrofluorocarbons and electrical conductivity. It is particularly preferable in that various physical properties such as insulating property, melting point and viscosity are balanced. Even with the same tetrahydric alcohol, the formula (V
The cyclic ketals obtained from pentaerythritol having good symmetry represented by IIa) or (VIIb) are both solid at room temperature, which is not preferable. Among the compounds represented by formulas (III) to (VI), the compound having a 1,3-dioxolane structure (III
The compounds shown in a), (IIIb), (IVa), and (V) are preferable, and among them, especially, have only a 1,3-dioxolane structure.
(IIIa), (IVa) and (V), and among them, the polyhydric alcohol moiety has no ether bond (III
The compounds shown in a) and (IVa) are preferable.

The melting point of the cyclic ketal or cyclic acetal used in the lubricating oil composition of the present invention is preferably 10 ° C or lower, more preferably -10 ° C or lower, and particularly preferably-
It is 30 ° C or lower. The cyclic ketal or cyclic acetal having a melting point of more than 10 ° C. such as (VIIa) or (VIIb) is mixed with another cyclic ketal, cyclic acetal or ester compound used in the present invention having a low melting point, or other lubricating oil. , Can be used by limiting the addition amount.

[0064]

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The cyclic ketal or cyclic acetal used in the lubricating oil composition of the present invention has a viscosity of 1 mm ² / s at 100 ° C.
It is preferably 100 mm ² / s or less, more preferably 1 mm ² / s or more and 50 mm ² / s or less, and particularly preferably 1 m.
It is not less than m ² / s and not more than 30 mm ² / s.

When the cyclic ketal or cyclic acetal used in the lubricating oil composition of the present invention is used as the base oil of the working fluid of the refrigerator, it is desirable that the two-phase separation temperature from the hydrofluorocarbon is low and 10 ° C. or lower. , Preferably 0 ° C. or lower, more preferably −10 ° C. or lower, particularly preferably −30 ° C. or lower. However, even if a cyclic ketal or cyclic acetal having a two-layer separation temperature from hydrofluorocarbon of more than 10 ° C. is mixed with another cyclic ketal, cyclic acetal, ester compound or other hydrofluorocarbon of lubricating oil. When the separation temperature is low and the lubricating oil composition has a temperature of 10 ° C. or lower, the two-layer separation temperature with hydrofluorocarbon is 10
Even cyclic ketals or cyclic acetals having a temperature above 0 ° C can be used in the refrigerator working fluid composition.

2. Regarding Ester Compound (1) Aspect of Ester Compound The ester compound used in the present invention is an ester compound having a kinematic viscosity at 100 ° C. of 0.1 to 100 mm ² / s. Examples of the ester compound used in the present invention include the following four types of ester A to ester D.

(I) Ester A The first type of ester used in the present invention includes: , An ester obtained from a monovalent carboxylic acid having 2 to 50 carbon atoms or a derivative thereof.

The polyhydric alcohol relating to the ester compound described in A) used in the present invention is a polyhydric alcohol having 2 to 10 carbon atoms and 2 to 50 carbon atoms. The carbon number of these polyhydric alcohols is 2 to 50, preferably 2 to
30, more preferably 2 to 10, particularly preferably 2
7 When the number of carbon atoms is more than 50, the viscosity of the ester compound becomes high and the viscosity of the obtained lubricating oil composition also becomes high, which is not preferable. The valency of these polyhydric alcohols is 2 to 10 and preferably 2 to 6. When the valence of the polyhydric alcohol is higher than 10, the viscosity becomes too high and the viscosity of the resulting lubricating oil composition becomes high, which is not preferable.

Specific examples of the polyhydric alcohol include neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 2-isopropyl-2-methyl-1,3-propanediol, 2, 2-diethyl-1,3-propanediol, 2-
Hindered alcohols such as n-butyl-2-ethyl-1,3-propanediol, trimethylolethane, trimethylolpropane, ditrimethylolpropane, trimethylolnonane, pentaerythritol, dipentaerythritol, tripentaerythritol and polypentaerythritol , Or ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol,
1,3-butanediol, 1,4-butanediol, 2-methyl-
1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol,
1,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 3,3-dimethyl-1,2-butanediol, 1, 7-heptanediol, 2-ethyl-1,3-hexanediol, 1,
2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, glycerin , Diglycerin, polyglycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, mannitol, galactitol, inditol, talitol and allitol. And other polyhydric alcohols.

These polyhydric alcohols are preferably saturated polyhydric alcohols having no unsaturated bond in their structure from the viewpoint of the thermal stability of the lubricating oil composition, and the viscosity index of the resulting lubricating oil composition is From the viewpoint, an aliphatic polyhydric alcohol is preferable. In particular, hindered alcohols that do not contain β hydrogen in the alcohol structure are particularly excellent in view of the heat deterioration mechanism of the ester.

In particular, when a lubricating oil composition obtained by using these polyhydric alcohols and containing an ester compound described in A) and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator, thermal stability is improved. Also, from the viewpoint of compatibility with hydrofluorocarbons, the polyhydric alcohol is preferably a divalent to hexavalent aliphatic polyhydric alcohol having 2 to 10 carbon atoms, and is particularly a hindered alcohol from the viewpoint of thermal stability of the ester compound. Is preferred. Specific examples include neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol and dipentaerythritol.

The monohydric alcohol relating to the ester compound described in A) used in the present invention has 1 to 50 carbon atoms, preferably 1 to 36, more preferably 1 to 22, Especially preferably, it is 1-12.
When the carbon number of these monohydric alcohols exceeds 50, the viscosity of the obtained ester becomes high, and the viscosity of the obtained lubricating oil composition becomes high, which is not preferable.

These monohydric alcohols are specifically methanol, ethanol, propanol, isopropanol,
Cyclopropanol, 1-butanol, 2-butanol, 2-
Methyl-1-propanol, 2-methyl-2-propanol,
3-butene-1-ol, 3-butene-2-ol, 2-butene-1
-Ol, cyclobutanol, cyclopropanemethanol, 2-methyl-2-propen-1-ol, 2-butyn-1-ol, 3-butyn-1-ol, 3-butyn-2-ol, 2-methyl- 1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-pentanol, 2-pentanol, 3- Pentanol, cyclobutanemethanol, cyclopentanol, 2-methyl-3-buten-1-ol, 2-methyl-3-buten-2-ol, 3-methyl-2-buten-1-ol, 3-methyl- 3-butene-1-ol, α-methylcyclopropanemethanol, 1-methylcyclopropanemethanol, 2-methylcyclopropanemethanol, 1-pentene-3
-All, 2-penten-1-ol, 3-pentene-2-ol, 4-pentene-1-ol, 4-pentene-2-ol, 2-
Methyl-3-butyn-2-ol, 1,4-pentadiene-3-ol, 1-pentyn-3-ol, 2-pentyn-1-ol,
3-pentyn-1-ol, 4-pentyn-1-ol, 4-pentyn-2-ol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl- 2-butanol,
2-ethyl-1-butanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 2-
Methyl-2-pentanol, 2-methyl-3-pentanol,
3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, cyclohexanol, cyclopentane Methanol, 1-hexen-3-ol, 2-hexen-1-ol, 3-hexen-1-ol, 4-
Hexen-1-ol, 5-hexen-1-ol, 1-methylcyclopentanol, 2-methylcyclopentanol, 3-
Methylcyclopentanol, 3-methyl-1-pentene-3-
All, 4-methyl-3-penten-1-ol, 2-cyclohexene-1-ol, 1,5-hexadiene-3-ol, 2,4-
Hexadiene-1-ol, 3-hexyn-1-ol, 5-hexyn-1-ol, 3-methyl-1-pentyn-3-ol,
3-methyl-2-penten-4-yn-1-ol, phenol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl-3-
Pentanol, 2,4-Dimethyl-3-pentanol, 4,4-Dimethyl-2-pentanol, 3-Ethyl-3-pentanol,
1-heptanol, 2-heptanol, 3-heptanol, 2-
Methyl-2-hexanol, 2-methyl-3-hexanol,
5-methyl-2-hexanol, cycloheptanol, cyclohexylmethanol, 1-methylcyclohexanol,
2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclohexanol, 3-cyclohexene
-1-Methanol, 1,6-heptadien-4-ol, 3-methyl-2-cyclohexen-1-ol, norborneol, 1-
Ethynylcyclopentanol, 5-norbornen-2-ol, benzyl alcohol, cresol, 2-ethyl-1-hexanol, 4-methyl-3-heptanol, 6-methyl-2-
Heptanol, 1-octanol, 2-octanol, 3-octanol, 2-propyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, cycloheptanemethanol,
1-cyclohexylethanol, 2-cyclohexylethanol, cyclooctanol, 3-cyclopentyl-1-propanol, 2,3-dimethylcyclohexanol, 2,6-dimethylcyclohexanol, 3,5-dimethylcyclohexanol, 2-ethylcyclohexanol , 4-ethylcyclohexanol, 6-methyl-5-hepten-2-ol, 1-octen-3-ol, 3,5-dimethyl-1-hexyne-3-ol, 6-methyl-3-cyclohexene-1 -Methanol, 2-norbornanemethanol, 1-octyne-3-ol, 1-ethynyl-1-cyclohexanol, 5-norbornene-2-methanol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5 -Dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylpheno Le, 2-methylbenzyl alcohol, 3-methyl benzyl alcohol, 4-methylbenzyl alcohol, phenethyl alcohol, 2,6-dimethyl-4-heptanol,
3-Ethyl-2,2-dimethyl-3-pentanol, 1-nonanol, 2-nonanol, 3,5,5-trimethyl-1-hexanol, 3-cyclohexyl-1-propanol, 3-nonene-1-
Oar, 2,4-dimethyl-2,6-heptadiene-1-ol,
3-methyl-2-norbornanemethanol, 3-nonin-1-ol, 3,5,5-trimethyl-2-cyclohexen-1-ol, 2,4-dimethylbenzyl alcohol, 2,5-dimethylbenzyl alcohol, 3 , 4-dimethylbenzyl alcohol,
3,5-dimethylbenzyl alcohol, 4-ethylbenzyl alcohol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methylphenethyl alcohol, 3-methylphenethyl alcohol, 4-
Methylphenethyl alcohol, 1-phenyl-1-propanol, 1-phenyl-2-propanol, 2-phenyl-1-propanol, 2-phenyl-2-propanol, 3-phenyl
-1-propanol, 3-propylphenol, 4-propylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,4,6-trimethylphenol, 3,4,
5-trimethylphenol, 2-allylphenol, cinnamyl alcohol, 1-indanol, 2-propenylphenol, 1-phenyl-2-propyn-1-ol, decanol,
2-decanol, 4-decanol, 3,7-dimethyl-1-octanol, 3,7-dimethyl-3-octanol, 2-tert-butylcyclohexanol, citronellol, 4-cyclohexyl-1-butanol, 9-decene- 1-ol, menthol, 3,3,5,5-tetramethylcyclohexane, decahydro
-1-Naphthol, 2-butylphenol, ethylphenethyl alcohol, 4-isopropylbenzyl alcohol, 4-
Isipropyl-3-methylphenol, 2-methyl-1-phenyl-1-propanol, 1-phenyl-1-butanol, 2-
Allyl-6-methylphenol, cyclopropylbenzyl alcohol, 1-phenyl-1-cyclopropanemethanol, 2-phenyl-3-butyn-2-ol, 1-naphthol,
2-naphthol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol,
Nonadecanol, icosanol, docosanol, triacontanol, tetracontanol, pentacontanol and the like.

These monohydric alcohols are preferably saturated alcohols from the viewpoint of thermal stability of the lubricating oil composition. Also, in terms of the viscosity index of the obtained lubricating oil composition,
Desirably it is an aliphatic alcohol.

In particular, when a lubricating oil composition containing an ester compound described in A) obtained by using these monohydric alcohols and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator, a monohydric alcohol is used. Is preferably a saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms. From the viewpoint of compatibility with hydrofluorocarbons, branched chain alcohols are preferable to straight chain alcohols.

Specifically, isopropanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl- 1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 2-pentanol,
3-pentanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol,
2-Ethyl-1-butanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pent Tanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-
Pentanol, 2,2-Dimethyl-3-pentanol, 2,3-Dimethyl-3-pentanol, 2,4-Dimethyl-3-pentanol, 4,4-Dimethyl-2-pentanol, 3-Ethyl -3-Pentanol, 2-heptanol, 3-heptanol, 2-methyl
-2-hexanol, 2-methyl-3-hexanol, 5-methyl-2-hexanol, 2-ethyl-1-hexanol, 4-methyl-3-heptanol, 6-methyl-2-heptanol, 2-
Octanol, 3-octanol, 2-propyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, 2,6-dimethyl-4-heptanol, 3-ethyl-2,2-dimethyl-3- Pentanol, 2-nonanol, 3,5,5-trimethyl-1-hexanol and the like can be mentioned. Further, these monohydric alcohols may be used alone or in combination.

The monovalent carboxylic acid relating to the ester compound or its derivative described in A) used in the present invention has 2 to 50 carbon atoms, preferably 2 to 36, and more preferably. 2 to 22, particularly preferably 2 to 12. When the carbon number exceeds 50, the viscosity of the ester compound becomes high, and the viscosity of the obtained lubricating oil composition becomes high, which is not preferable. Further, if the carbon number is less than 2, corrosiveness to metal increases, which is not preferable.

Specific examples of these monovalent carboxylic acids or derivatives thereof include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, 2-methylbutyric acid, caproic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2-
Ethyl butyric acid, tert-butylacetic acid, cyclopentanecarboxylic acid, enanthic acid, 2,2-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4- Methylhexanoic acid, 5-methylhexanoic acid, cyclohexanecarboxylic acid, cyclopentyl acetic acid, caprylic acid, 2-ethylhexanoic acid, 3,5-dimethylhexanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 3- Methylheptanoic acid, 4-methylheptanoic acid,
2-propylpentanoic acid, 3,4-dimethylhexanoic acid, cyclohexylacetic acid, 3-cyclopentylpropionic acid, pelargonic acid, 2,2-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2,4,4-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid,
Decanoic acid, 2,2-dimethyloctanoic acid, 2,4-dimethyloctanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, peptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid, tria Contanoic acid, tetracontanoic acid, pentaconsanic acid, benzoic acid, diphenyl-4-carboxylic acid, methylbenzoic acid, naphthalenecarboxylic acid, phenylacetic acid, phenoxyacetic acid, tert-butylbenzoic acid, o-benzoylbenzoic acid, 1,4 -Dihydro-2-methylbenzoic acid, 4-vinylbenzoic acid, cinnamic acid, 2,3-dimethylbenzoic acid, 4-ethylbenzoic acid, 2-phenyl-1-cyclopropanecarboxylic acid, 2-
Methoxyvinylbenzoic acid, 1-naphthylacetic acid, 1-naphthoxyacetic acid, 1-phenyl-1-cyclopentanecarboxylic acid, 2-
Ethyl-2-phenylbutanoic acid, 3-methyl-2-phenylvaleric acid, 4-pentylbenzoic acid, 6-phenylhexanoic acid, 4-pentyloxybenzoic acid, 2-phenoxybenzoic acid, 2-ethoxy-1-naphthalene Carboxylic acid, 4-hexylbenzoic acid, 4-isobutyl-α-methylphenylacetic acid, 9-
Anthracenecarboxylic acid, 9-fluorene acetic acid, 2,2-diphenylpropionic acid, 4-undecyloxybenzoic acid, 4-
Dodecyloxybenzoic acid, abietic acid or their methyl esters, ethyl esters, acid anhydrides and the like can be mentioned.

These monovalent carboxylic acids are preferably saturated monovalent carboxylic acids having no unsaturated bond in their structure from the viewpoint of thermal stability of the lubricating oil composition. From the viewpoint of the viscosity index of the resulting lubricating oil composition, aliphatic monovalent carboxylic acid is preferable.

In particular, when a lubricating oil composition containing an ester compound described in A) obtained by using these monovalent carboxylic acids or derivatives thereof and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid for a refrigerator. The monovalent carboxylic acid is preferably a linear or branched saturated aliphatic monovalent carboxylic acid having 2 to 9 carbon atoms, and more preferably a saturated aliphatic monovalent carboxylic acid having 5 to 9 carbon atoms. Considering the structure of the monovalent carboxylic acid from the viewpoint of lubricity, a straight chain acid is preferable to a branched chain acid. Considering the structure of the monovalent carboxylic acid from the viewpoint of compatibility with hydrofluorocarbon, a branched chain acid is preferable to a straight chain acid.

Specific examples of the saturated aliphatic carboxylic acid having 2 to 9 carbon atoms include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, 2-methylbutyric acid, caproic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid,
2-ethylbutyric acid, tert-butylacetic acid, enanthic acid, 2,2-dimethylpentanoic acid, 2,2-diethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2-methylhexanoic acid, 3-methyl Hexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, caprylic acid, 2-ethylhexanoic acid, 3,5-
Dimethylhexanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 2-propylpentanoic acid, 3,4-dimethylhexanoic acid,
Pelargonic acid, 2,2-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2, Examples include 4,4-tetramethylpentanoic acid and 2,2-diisopropylpropionic acid.

Among the above carboxylic acids, valeric acid, isovaleric acid, 2-methylbutyric acid, caproic acid, enanthic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, caprylic acid, 2- Ethylhexanoic acid, pelargonic acid, 3,5,5-trimethylhexanoic acid and the like are preferable. Further, these monovalent carboxylic acids may be used alone or in combination.

(Ii) Ester B The second type of ester used in the present invention is B) a monohydric alcohol having 1 to 50 carbon atoms and 2 to 5 carbon atoms.
It is an ester obtained from a 2- to 10-valent polycarboxylic acid of 0 or a derivative thereof.

The monohydric alcohol relating to the ester compound described in B) used in the present invention is the same as the monohydric alcohol described in A). These monohydric alcohols are preferably saturated alcohols from the viewpoint of the thermal stability of the lubricating oil composition. Further, from the viewpoint of the viscosity index of the obtained lubricating oil composition, an aliphatic alcohol is desirable.

Particularly when a lubricating oil composition containing the ester compound described in B) obtained by using these monohydric alcohols and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator, a monohydric alcohol is used. Is preferably a saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms. From the viewpoint of compatibility with hydrofluorocarbons, branched chain alcohols are preferable to straight chain alcohols.

The polyvalent carboxylic acid relating to the ester compound or its derivative described in B) used in the present invention has 2 to 50 carbon atoms, and preferably 2
-22, more preferably 2-10. Carbon number 5
If it exceeds 0, the viscosity of the ester compound becomes high, and the viscosity of the obtained lubricating oil composition becomes high, which is not preferable. Moreover, the valence of these polyvalent carboxylic acids is from 2 to 10,
The valence is preferably 2 to 8, and more preferably 2 to 6. When the valence of the polyvalent carboxylic acid exceeds 10, the viscosity of the ester compound increases and the viscosity of the resulting lubricating oil composition increases, which is not preferable.

Specific examples of these polyvalent carboxylic acids or their derivatives include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid and maleic acid. , Fumaric acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecane Dicarboxylic acid, 1,15-hexadecanedicarboxylic acid, 1,20-icosanedicarboxylic acid, 1,30-triacontanedicarboxylic acid, 1,40-tetracontanedicarboxylic acid, 1,50-pentacontanedicarboxylic acid, dimethylmalonic acid , 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid,
3,3-dimethyl glutaric acid, trimethyl adipic acid, 2,2-
Dimethyl adipic acid, 7-ethyl-1,14-tetradecanedicarboxylic acid, 8-ethyl-1,18-octadecanedicarboxylic acid,
7,8-Diphenyl-1,16-hexadecanedicarboxylic acid, 1,3-
Cyclohexanedicarboxylic acid, α-carboxy-o-toluic acid, 4-carboxyphenoxyacetic acid, 2-methoxyisophthalic acid, benzylmalonic acid, 2-carboxybenzenepropanoic acid, 1,4-phenylenediacetic acid, phenylsuccinic acid,
1,2-phenylenedioxydiacetic acid, 1,1-cyclohexanediacetic acid, cyclohexylsuccinic acid, 2,2,5,5-tetramethylhexanedicarboxylic acid, 3-phenylglutaric acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid,
Dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 1,4-phenylenediacrylic acid, 5-tert-butylisophthalic acid, 1,4-phenylenedipropionic acid and 4,4-biphenyldicarboxylic acid, 1, 3,5-cyclohexanetricarboxylic acid, 1,3,
5-trimethyl-1,3,5-cyclohexanetricarboxylic acid,
Trivalent carboxylic acids such as trimellitic acid and citric acid, tetravalent carboxylic acids such as pyromellitic acid and dipivaloyl-D-tetracarboxylic acid, 6 such as 1,7,8,9,10,16-hexadecanehexacarboxylic acid Carboxylic acids and their methyl esters,
Examples thereof include ethyl ester and acid anhydride.

These polyvalent carboxylic acids are preferably saturated polycarboxylic acids from the viewpoint of the thermal stability of the lubricating oil composition, and further, from the viewpoint of the viscosity index of the resulting lubricating oil composition, aliphatic polycarboxylic acids are preferred. It is preferably a carboxylic acid.

In particular, when a lubricating oil composition containing the ester compound described in B) and a cyclic ketal or a cyclic acetal obtained by using these polyvalent carboxylic acids or their derivatives is used as a base oil for a working fluid of a refrigerator. The polycarboxylic acid is preferably a saturated aliphatic polycarboxylic acid having 2 to 6 carbon atoms and having 2 to 10 carbon atoms. Specific examples of the saturated aliphatic polycarboxylic acid include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid and 2,3-dimethyl. Examples include succinic acid, 3,3-dimethylglutaric acid, trimethyladipic acid, 2,2-dimethyladipic acid, phthalic acid, trimellitic acid and pyromellitic acid. Further, these polyvalent carboxylic acids may be used alone or in combination.

(Iii) Ester C As the third type of ester used in the present invention, C) a polyhydric alcohol having 2 to 10 carbon atoms and having 2 to 50 carbon atoms,
A monovalent carboxylic acid having 2 to 50 carbon atoms or a derivative thereof,
And an ester obtained from a C2 to C2 to C10 polyvalent carboxylic acid or a derivative thereof.

As described in C) used in the present invention,
The polyhydric alcohol related to the ester compound is the same as the polyhydric alcohol described in A).

These polyhydric alcohols are preferably saturated polyhydric alcohols having no unsaturated bond in their structure from the viewpoint of thermal stability of the lubricating oil composition, and the viscosity index of the resulting lubricating oil composition is From the viewpoint, an aliphatic polyhydric alcohol is preferable. In particular, hindered alcohols that do not contain β hydrogen in the alcohol structure are particularly excellent in view of the heat deterioration mechanism of the ester.

In particular, when a lubricating oil composition obtained by using these polyhydric alcohols and containing the ester compound described in C) and a cyclic ketal or a cyclic acetal is used as a base oil for a working fluid of a refrigerator, thermal stability is improved. Also, from the viewpoint of compatibility with hydrofluorocarbons, the polyhydric alcohol is preferably a divalent to hexavalent aliphatic polyhydric alcohol having 2 to 10 carbon atoms, and is particularly a hindered alcohol from the viewpoint of thermal stability of the ester compound. Is preferred. Specific examples include neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol and dipentaerythritol.

As described in C) used in the present invention,
The monovalent carboxylic acid or its derivative relating to the ester compound is the same as the monovalent carboxylic acid or its derivative described in A).

These monovalent carboxylic acids are preferably saturated monovalent carboxylic acids having no unsaturated bond in their structure from the viewpoint of thermal stability of the lubricating oil composition. From the viewpoint of the viscosity index of the resulting lubricating oil composition, aliphatic monovalent carboxylic acid is preferable.

In particular, when a lubricating oil composition containing an ester compound described in C) obtained by using these monovalent carboxylic acids or derivatives thereof and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator. The monovalent carboxylic acid is preferably a linear or branched saturated aliphatic monovalent carboxylic acid having 2 to 9 carbon atoms, and more preferably a saturated aliphatic monovalent carboxylic acid having 5 to 9 carbon atoms. Considering the structure of the monovalent carboxylic acid from the viewpoint of lubricity, a straight chain acid is preferable to a branched chain acid. Considering the structure of the monovalent carboxylic acid from the viewpoint of compatibility with hydrofluorocarbon, a branched chain acid is preferable to a straight chain acid.

Examples of the saturated aliphatic carboxylic acid having 2 to 9 carbon atoms are the same as those mentioned in the section of the ester A.

Among the above-mentioned carboxylic acids, valeric acid, isovaleric acid, 2-methylbutyric acid, caproic acid, enanthic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, caprylic acid, 2- Ethylhexanoic acid, pelargonic acid, 3,5,5-trimethylhexanoic acid and the like are preferable. Further, these monovalent carboxylic acids may be used alone or in combination.

As described in C) used in the present invention,
The polycarboxylic acid or its derivative used for the ester compound is the same as the polycarboxylic acid or its derivative described in B).

These polyvalent carboxylic acids are preferably saturated polycarboxylic acids from the viewpoint of the thermal stability of the lubricating oil composition, and are aliphatic from the viewpoint of the viscosity index of the resulting lubricating oil composition. It is preferably a polycarboxylic acid.

In particular, when a lubricating oil composition containing an ester compound described in C) obtained by using these polyvalent carboxylic acids or derivatives thereof and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid for a refrigerator. The polycarboxylic acid is preferably a linear or branched saturated aliphatic dicarboxylic acid having 2 to 10 carbon atoms. Specific examples of the saturated aliphatic dicarboxylic acid include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid,
Examples include 2,3-dimethylsuccinic acid, 3,3-dimethylglutaric acid, trimethyladipic acid, and 2,2-dimethyladipic acid.
Further, these polyvalent carboxylic acids may be used alone or in combination. As the carboxylic acid component of the ester compound described in C), both the above-mentioned monovalent carboxylic acid and polyvalent carboxylic acid are used.

(Iv) Ester D The fourth type of ester used in the present invention is as follows: , Carbon number 2-50
Is an ester obtained from a divalent to 10-valent polycarboxylic acid or a derivative thereof.

As described in D) used in the present invention,
The polyhydric alcohol related to the ester compound is the same as the polyhydric alcohol described in A).

These polyhydric alcohols are preferably saturated polyhydric alcohols having no unsaturated bond in their structure from the viewpoint of the thermal stability of the lubricating oil composition, and the viscosity index of the resulting lubricating oil composition is From the viewpoint, an aliphatic polyhydric alcohol is preferable. In particular, hindered alcohols that do not contain β hydrogen in the alcohol structure are particularly excellent in view of the heat deterioration mechanism of the ester.

In particular, when a lubricating oil composition containing the ester compound described in D) obtained by using these polyhydric alcohols and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator, thermal stability is improved. Further, from the viewpoint of compatibility with hydrofluorocarbon, the polyhydric alcohol is preferably a linear or branched saturated aliphatic dihydric alcohol having 2 to 10 carbon atoms, and particularly, from the viewpoint of heat stability of the ester compound, it is a hindered alcohol. Preferably there is. Specifically, neopentyl glycol, 2-ethyl-2-
Methyl-1,3-propanediol, 2-isopropyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-
2-ethyl-1,3-propanediol and the like can be mentioned.

As described in D) used in the present invention,
The monohydric alcohol used for the ester compound is the same as the monohydric alcohol described in A).

These monohydric alcohols are preferably saturated alcohols from the viewpoint of the thermal stability of the lubricating oil composition. Further, from the viewpoint of the viscosity index of the obtained lubricating oil composition, an aliphatic alcohol is desirable.

In particular, when a lubricating oil composition containing an ester compound described in D) obtained by using these monohydric alcohols and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid of a refrigerator, a monohydric alcohol is used. Is preferably a linear or branched saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms. From the viewpoint of compatibility with hydrofluorocarbons, branched chain alcohols are preferable to straight chain alcohols. Specifically, ester A
Are the same as those listed in the section.

As described in D) used in the present invention,
The polycarboxylic acid used for the ester compound is the same as the polycarboxylic acid described in B).

These polyvalent carboxylic acids are preferably saturated polyvalent carboxylic acids from the viewpoint of the thermal stability of the lubricating oil composition, and from the viewpoint of the viscosity index of the resulting lubricating oil composition, they are aliphatic. It is preferably a polycarboxylic acid.

In particular, when a lubricating oil composition containing an ester compound described in D) obtained by using these polyvalent carboxylic acids or derivatives thereof and a cyclic ketal or a cyclic acetal is used as a base oil of a working fluid for a refrigerator. The polycarboxylic acid is preferably a saturated aliphatic polycarboxylic acid having 2 to 6 carbon atoms and having 2 to 10 carbon atoms. Specific examples of the saturated aliphatic polycarboxylic acid include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethylmalonic acid, 2,2-dimethylsuccinic acid and 2,3-dimethyl. Examples thereof include succinic acid, 3,3-dimethylglutaric acid, trimethyladipic acid, 2,2-dimethyladipic acid, phthalic acid, trimellitic acid and pyromellitic acid. Further, these polyvalent carboxylic acids may be used alone or in combination. As the alcohol component of the ester compound described in D), both the polyhydric alcohol and the monohydric alcohol as described above are used.

The ester compound used in the lubricating oil composition of the present invention can be obtained by a conventional esterification reaction, and further purified by a general purification step such as deoxidation, water washing and adsorption treatment after the esterification reaction. can do.

A) used in the lubricating oil composition of the present invention
As the ester compound described in D), a preferred ester compound may be selected depending on the use of the lubricating oil composition. In particular, when the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, the following ester compounds are preferable because of their excellent compatibility with hydrofluorocarbons. A ′) a C 2-10 divalent to C 6 aliphatic polyhydric alcohol or a C 1-10 saturated aliphatic monohydric alcohol, and a C 2-9 linear or branched saturated aliphatic 1 An ester obtained from a divalent carboxylic acid or a derivative thereof, B ') a saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms, and a divalent to 6-valent saturated aliphatic polycarboxylic acid having 2 to 10 carbon atoms or a derivative thereof And C ′) a C 2 to C 2-10 divalent aliphatic polyhydric alcohol, and a C 2 to C 9 linear or branched saturated aliphatic 1
Carboxylic acid or its derivative, and carbon number 2 to 1
0, an ester obtained from a linear or branched saturated aliphatic divalent carboxylic acid or a derivative thereof, and D ′) a linear or branched saturated aliphatic dihydric alcohol having 2 to 10 carbon atoms and the number of carbon atoms An ester obtained from a linear or branched saturated aliphatic monohydric alcohol having 1 to 10 and a divalent saturated hexavalent polycarboxylic acid having 2 to 6 carbon atoms or a derivative thereof.

Further, among A ') to D'), the ester compound described in A ') is particularly preferable in consideration of the balance of required performances such as compatibility with hydrofluorocarbon, thermal stability, lubricity, and electrical insulation. . Among the ester compounds described in A '), especially as a polyhydric alcohol, 2 having 2 to 10 carbon atoms.
Particularly preferred is a hindered ester using a hexavalent hindered alcohol and a saturated aliphatic monovalent carboxylic acid having 5 to 9 carbon atoms as the monovalent carboxylic acid. As the saturated aliphatic polyhydric alcohol, neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol and the like are preferable, and as the saturated aliphatic monovalent carboxylic acid, valeric acid, isovaleric acid, 2-methyl Butyric acid, caproic acid, enanthic acid, 2-
Ethylpentanoic acid, 2-methylhexanoic acid, caprylic acid,
2-Ethylhexanoic acid, pelargonic acid, 3,5,5-trimethylhexanoic acid and the like are preferable.

Particularly preferred specific examples of the ester described in A ') are 3,5,5-trimethylhexanoic acid ester of neopentyl glycol, 2-ethylhexanoic acid ester of neopentyl glycol, and 3,5 of trimethylolpropane. ,
5-trimethylhexanoic acid ester, trimethylolpropane 2-methylhexanoic acid / 2-ethylpentanoic acid / 3,5,
5-trimethylhexanoic acid mixed fatty acid ester, trimethylolpropane 2-ethylhexanoic acid ester, trimethylolpropane 2-methylhexanoic acid / 2-ethylpentanoic acid mixed fatty acid ester, pentaerythritol valeric acid / isovaleric acid / 3, 5,5-trimethylhexanoic acid mixed fatty acid ester, pentaerythritol enanthate / 3,5,5-trimethylhexanoic acid mixed fatty acid ester, pentaerythritol 2-ethylhexanoic acid / 3,5,
5-Trimethylhexanoic acid mixed fatty acid ester, pentaerythritol 2-methylhexanoic acid / 2-ethylpentanoic acid / 2-ethylhexanoic acid mixed fatty acid ester, pentaerythritol caprylic acid / 3,5,5-trimethylhexanoic acid mixed fatty acid Examples include esters.

(2) Physicochemical Properties of Ester Compound (i) Kinematic Viscosity The ester compound used in the present invention has a kinematic viscosity at 100 ° C. of 0.1 to 100 mm ² / s, preferably 0.
5 to 50 mm ² / s, more preferably 1 to 30 mm ²
/ S is an ester compound. When the kinematic viscosity at 100 ° C. exceeds 100 mm ² / s, the viscosity of the lubricating oil composition becomes too high, which is not preferable. The kinematic viscosity at 40 ° C. is preferably 1 to 1000 mm ² / s. The same applies when the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator.

(Ii) Iodine Value The iodine value (Img / 100g) of the ester compound used in the lubricating oil composition of the present invention is 10 or less, preferably 5 or less, more preferably 3 or less, particularly preferably 1 or less. . If the iodine value exceeds 10, the thermal oxidation stability of the resulting lubricating oil composition may be significantly impaired. When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, the ester compound used has an iodine value of 5 or less, preferably 3 or less, more preferably 1 or less, and particularly preferably 0.5 or less. When the iodine value exceeds 5, the thermo-oxidative stability of the working fluid of the refrigerator using the lubricating oil composition of the present invention as a base oil may be significantly impaired.

(Iii) Acid Value The acid value (mgKOH / g) of the ester compound used in the lubricating oil composition of the present invention is 5 or less, preferably 1 or less, more preferably 0.5 or less, and particularly preferably 0.1. It is 1 or less. When the acid value exceeds 5, it not only promotes hydrolysis of the lubricating oil composition, but also impairs thermal oxidation stability of the lubricating oil composition itself, and also corrodes metallic materials, lowers the flash point, and wear resistance. It is not preferable because it causes deterioration of the electric field, an offensive odor, a decrease in electric insulation, and the like. When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, the acid value (mgKOH / g) of the ester compound used is 1 or less, preferably 0.1.
Or less, more preferably 0.05 or less, and particularly preferably 0.03 or less. If the acid value exceeds 1, it is not preferable because it causes corrosion of the metal material, deterioration of wear resistance, deterioration of thermal oxidation stability, deterioration of electric insulation, and the like.

(Iv) Hydroxyl Value The hydroxyl value (mgKOH / g) of the ester compound used in the lubricating oil composition of the present invention is 0.1 or more and 50 or less, preferably 0.1 or more and 20 or less, more preferably 0.1. It is 3 or more and 10 or less, and particularly preferably 0.5 or more and 5 or less.
When the hydroxyl value exceeds 50, it is not preferable because the obtained lubricating oil composition causes a decrease in the flash point and a decrease in the electric insulation. If it is less than 0.1, the lubricity deteriorates, which is not preferable. When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, the ester compound used has a hydroxyl value (mgKOH / g) of 0.1 or more and 20 or less, preferably 0.3 or more and 10 or less, It is preferably 0.5 or more and 5 or less. A hydroxyl value of more than 20 is not preferable because it causes a decrease in compatibility with hydrofluorocarbons, a decrease in electrical insulation and the like. If less than 0.1,
Lubricity deteriorates, which is not preferable.

(V) Melting point The melting point of the ester compound used in the lubricating oil composition of the present invention is preferably 10 ° C or lower, more preferably -10 ° C or lower, and particularly preferably -30 ° C or lower. An ester compound having a melting point of higher than 10 ° C., such as an ester of pentaerythritol and 3,5,5-trimethylhexanoic acid, is a cyclic ketal or a cyclic acetal used in the present invention having a low melting point,
It can be used in a lubricating oil composition by mixing with an ester compound and limiting the amount added. When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, the melting point of the ester compound used is 10 ° C or lower, preferably -10 ° C or lower, more preferably -30 ° C or lower, and particularly preferably- Four
0 ° C. or less.

(Vi) Two-Phase Separation Temperature When the lubricating oil composition of the present invention is used as a base oil of a working fluid of a refrigerator, it is desirable that the two-phase separation temperature of the ester compound used and hydrofluorocarbon is low.
℃ or less, preferably 0 ℃ or less, more preferably -10
C. or lower, particularly preferably -30.degree. C. or lower. But,
Even when an ester compound having a two-layer separation temperature from hydrofluorocarbon of more than 10 ° C. is mixed with the ester compound of the present invention, a cyclic ketal or a cyclic acetal, the two-layer separation temperature from the hydrofluorocarbon is lowered to give a composition. When the temperature is 10 ° C or lower, it can be used in a refrigerator working fluid composition.

The mixing ratio of the ester compound and the cyclic ketal or cyclic acetal in the lubricating oil composition of the present invention is as follows: ester compound / cyclic ketal or cyclic acetal = 10/9
0 to 99/1 weight ratio, preferably 10/90 to 9
5/5 weight ratio, more preferably 20/80 to 90/1
0, particularly preferably 35/65 to 90/10 weight ratio. If the amount of the cyclic ketal or cyclic acetal contained is less than 1% by weight, the effect of improving lubricity and the effect of preventing hydrolysis of the ester compound cannot be sufficiently exhibited. Further, when the content of the ester compound is less than 10% by weight, the viscosity index of the lubricating oil composition is significantly deteriorated.

3. Lubricating oil composition and working fluid set for refrigerator
About the composition The lubricating oil composition of the present invention is obtained by mixing the ester compound as described above with a cyclic ketal or a cyclic acetal. The lubricating oil composition obtained has a kinematic viscosity at 100 ° C of 1 mm ² / s or more. It is preferably 100 mm ² / s or less, more preferably 1 mm ² / s or more and 50 mm ² / s or less, and particularly preferably 1 mm ² / s or more and 30 mm ² / s or less. 40 ℃
Kinematic viscosity at the, 1 mm ² / s or more 1000 mm ² /
s or less, more preferably 1 mm ² / s or more and 5
00 mm ² / s or less, particularly preferably 5 mm ² / s or more and 200 mm ² / s or less.

The iodine value (Ig / 100g) of the lubricating oil composition of the present invention is 10 or less, preferably 5 or less,
It is more preferably 3 or less, and particularly preferably 1 or less.
If the iodine value exceeds 10, the thermal oxidation stability of the lubricating oil composition may be significantly impaired. The acid value (mgKOH / g) of the lubricating oil composition of the present invention is 5 or less, preferably 1 or less, more preferably 0.5 or less, and particularly preferably 0.1 or less. When the acid value exceeds 5, it not only promotes hydrolysis of the lubricating oil composition, but also impairs thermal oxidation stability of the lubricating oil composition itself, and also corrodes metallic materials, lowers the flash point, and wear resistance. It is not preferable because it causes deterioration of the electric field, an offensive odor, a decrease in electric insulation, and the like. The hydroxyl value (mgKOH / g) of the lubricating oil composition of the present invention is 0.1 or more and 5
0 or less, preferably 0.1 or more and 20 or less, more preferably 0.3 or more and 10 or less, particularly preferably 0.5 or more and 5
It is as follows. A hydroxyl value of more than 50 is not preferable because it causes a decrease in flash point and a decrease in electric insulation of the resulting lubricating oil composition. Also, if it is less than 0.1, the lubricity deteriorates, which is not preferable. The melting point of the lubricating oil composition of the present invention is preferably 10 ° C or lower, more preferably -1.
It is 0 ° C. or lower, particularly preferably −30 ° C. or lower.

When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, it is desirable that the two-phase separation temperature from hydrofluorocarbon is low, 10 ° C. or lower, preferably 0 ° C. or lower, and more preferably It is -10 ° C or lower, particularly preferably -30 ° C or lower.

The lubricating oil composition of the present invention can also be used as a mixture with other lubricating oils. Other lubricating oils include mineral oils, hydrocarbon-based synthetic oils such as polybutene, poly-α-olefins and alkylbenzenes, polyalkylene glycols, polyphenyl ethers, carbonates, phosphates, silicate esters, silicone oils, perfluoropolyethers, etc. Synthetic lubricating oil, rapeseed oil, soybean oil, safflower oil,
Corn oil, palm oil, palm oil, palm kernel oil, linseed oil,
Examples include natural oils such as cottonseed oil, tung oil, castor oil, and tallow fatty acid ester. Specific examples are “New edition Physical Chemistry of Lubrication” (Koshobo) and “Basics and Applications of Lubricating Oil” (Corona)
And so on.

When the lubricating oil composition of the present invention is mixed with another lubricating oil, the mixing ratio of the lubricating oil composition of the present invention in the mixed lubricating oil is 10% by weight or more, preferably 30% by weight or more, Particularly preferably, it is contained in an amount of 50% by weight or more, and the mixed lubricating oil contains 0.1% of cyclic ketal or cyclic acetal.
It is desirable that the content is not less than wt%, particularly preferably not less than 10 wt%.

The content of the lubricating oil composition of the present invention is 10
If it is less than the weight%, the effect of improving the lubricity cannot be sufficiently exhibited. If the amount of cyclic ketal or cyclic acetal contained is less than 0.1% by weight, the effect of improving lubricity and the effect of preventing hydrolysis of the ester compound cannot be sufficiently exhibited. When the lubricating oil composition of the present invention is used as a base oil of a working fluid of a refrigerator, the other lubricating oil to be mixed is preferably one having excellent compatibility with hydrofluorocarbon, polyalkylene glycol, perfluoropolyether. , Carbonate, perfluoroester and the like are preferable. However, when the compatibility with the hydrofluorocarbon of the lubricating oil composition of the present invention is sufficiently excellent,
For example, the two-phase separation temperature is -30 ° C or lower, preferably -5.
When the temperature is 0 ° C. or lower, it may be mixed with a lubricating oil having poor compatibility with hydrofluorocarbon, such as alkylbenzene or mineral oil, within a range where the two-phase separation temperature does not exceed 10 ° C.

The lubricating oil composition of the present invention contains, if necessary, antioxidants, extreme pressure agents, oiliness improvers, defoamers, detergent dispersants, viscosity index improvers, rust preventives, etc. Lubricating oil additives such as demulsifiers can also be added. For example, those usable as antioxidants are 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4,
Phenolic antioxidants such as 4'-methylenebis (2,6-di-tert-butylphenol), p, p-dioctylphenylamine, monooctyldiphenylamine, phenothiazine, 3,7-dioctylphenothiazine, phenyl-1-naphthylamine Amine-based antioxidants such as phenyl-2-naphthylamine and alkylphenyl-2-naphthylamine,
Examples thereof include sulfur-based antioxidants such as alkyl disulfide, thiodipropionic acid ester and benzothiazole, zinc dialkyldithiophosphate, zinc diaryldithiophosphate and the like. The amount added is 0.05 to 2.0% by weight based on the lubricating oil containing the lubricating oil composition of the present invention.

As the extreme pressure agent and oiliness improver, for example, zinc compounds such as zinc dialkyldithiophosphate and zinc diaryldithiophosphate, thiodipropionate, dialkyl sulfide, dibenzyl sulfide, dialkyl polysulfide, alkyl can be used. Sulfur compounds such as mercaptan, dibenzothiophene and 2,2'-dithiobis (benzothiazole), phosphorus compounds such as triaryl phosphate, triaryl phosphite, trialkyl phosphite and trialkyl phosphate, chlorine such as chlorinated paraffin Compound, molybdenum dithiocarbamate, molybdenum dithiophosphate,
Examples thereof include molybdenum compounds such as molybdenum disulfide, perfluoroalkyl polyethers, ethylene trifluoride chloride polymers, fluorine compounds such as fluorinated graphite, silicon compounds such as fatty acid-modified silicone, and graphite. The amount added is 0.0 with respect to the lubricating oil containing the lubricating oil composition of the present invention.
5 to 10% by weight.

As the defoaming agent, silicone oil such as dimethylpolysiloxane and organosilicates such as diethyl silicate are used. The amount added is 0.0005 to 5 with respect to the lubricating oil containing the lubricating oil composition of the present invention.
1% by weight.

The detergents and dispersants used are sulfonates, phenates, salicylates, phosphonates, polybutenyl succinimides, polybutenyl succinates and the like. The amount added is 0.05 to 10% by weight based on the lubricating oil containing the lubricating oil composition of the present invention.

When the lubricating oil composition of the present invention is used as a base oil for a working fluid of a refrigerator, benzotriazole or its derivative for protecting a metal surface is added as an additive, and lubricity is improved. It is effective to add triaryl phosphate or triaryl phosphite, or to add a phenolic compound having a radical trapping ability for improving thermal stability and a metal deactivator having a chelating ability.

The triaryl phosphate and triaryl phosphite used in the present invention have 18 to 18 carbon atoms.
70, more preferably 18 to 50 carbon atoms. Specifically, it is described in JP-A-5-209171, column 12, lines 26-41. Among them, particularly preferred is triphenyl phosphate,
Tricresyl phosphate, trixylenyl phosphate, tris (2,4-di-tert-butylphenyl) phosphate, triphenyl phosphite, tricresyl phosphite, trixylenyl phosphite, tris (2,4 -Di-tert-butylphenyl) phosphite. The amount of triaryl phosphate and / or triaryl phosphite added is 0.1 to 5.0% by weight, and preferably 0.5 to 2.%, based on the lubricating oil containing the lubricating oil composition of the present invention. It is 0% by weight.

The amount of benzotriazole or its derivative used in the present invention is 0.001 to 0.1% by weight, preferably 0.003 to 0.1% by weight based on the lubricating oil containing the lubricating oil composition of the present invention. It is 0.03% by weight. The benzotriazole and benzotriazole derivative used in the present invention have 6 to 50 carbon atoms, preferably 6 to 30 carbon atoms. Specifically, Japanese Patent Laid-Open No. 5-2
09171, column 13, lines 9 to 29. Among them, benzotriazole and 5-methyl-1H-benzotriazole are particularly preferable.

The addition amount of the metal deactivator used in the present invention is 0.0 based on the lubricating oil containing the lubricating oil composition of the present invention.
01 to 2.0% by weight, preferably 0.003 to
0.5% by weight. The metal deactivator used in the present invention preferably has a chelating ability and has a carbon number of 5 to 50.
And preferably 5 to 20. Specifically, it is described in JP-A-5-209171, column 13, line 38 to column 14, line 8. Among them, particularly preferred are N, N'-disalicylidene-1,2-diaminoethane, N, N'-disalicylidene-1,2-diaminopropane, acetylacetone, acetoacetate, alizarin, quinizarin and the like.

The amount of the phenolic compound having a radical trapping ability used in the present invention is 0.05 to 2.0% by weight, preferably 0, based on the lubricating oil containing the lubricating oil composition of the present invention. 0.05 to 0.5% by weight. The phenolic compound used in the present invention has 6 to 100 carbon atoms, preferably 10 to 80 carbon atoms.
belongs to. Specifically, it is described in JP-A-5-209171, column 12, line 32 to column 13, line 18. Among them, particularly preferable are 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4'-Butylidene bis (3-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-ter
t-butylphenol), 2,2'-methylenebis (4-methyl)
-6-tert-butylphenol), 4,4'-isopropylidenebisphenol, 2,4-dimethyl-6-tert-butylphenol, tetrakis [methylene-3- (3,5-di-tert-butyl-4)
-Hydroxyphenyl) propionate] methane, 1,1,
3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-
Di-tert-butyl-4-hydroxybenzyl) benzene, 2,
6-di-tert-butyl-4-ethylphenol, 2,6-bis (2 '
-Hydroxy-3'-tert-butyl-5'-methylbenzyl) -4
-Methylphenol, bis [2- (2-hydroxy-5-methyl-3-tert-butylbenzyl) -4-methyl-6-tert-butylphenyl] terephthalate, triethyleneglycol-
Bis [3- (3,5-di-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol
-Bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the like.

Further, an additive such as an organic tin compound or a boron compound which stabilizes the chlorofluorocarbon refrigerant may be added. The amount added is 0.0 with respect to the lubricating oil containing the lubricating oil composition of the present invention.
01 to 10% by weight.

Since the lubricating oil composition of the present invention has excellent compatibility with hydrofluorocarbons and excellent electric insulation, it can be used as a working fluid for a refrigerator as a mixture with hydrofluorocarbons. Further, since it has excellent electric insulation properties, it can be used as electric insulating oil, transformer oil, and the like. Further, since the composition has a ring structure, it can be used as a traction oil. Further, since it has excellent lubricity and heat resistance, it can be used as engine oil, turbine oil, gear oil, hydraulic oil, bearing oil, metal working oil, compressor oil, grease base oil and the like. Further, since it has excellent lubricity, it can be used as an additive for low-sulfur gas oil.
When the lubricating oil composition of the present invention is used as a refrigerator working fluid,
When the lubricating oil composition of the present invention is mixed with another lubricating oil, the mixing ratio of the lubricating oil composition of the present invention in the mixed lubricating oil is 10% by weight or more, preferably 30% by weight or more, and particularly preferably. 50% by weight or more, and 0.1% by weight or more of cyclic ketal or cyclic acetal in the mixed lubricating oil,
It is particularly preferable that the content is 10% by weight or more.

When the lubricating oil composition of the present invention is used in a refrigerator working fluid, the ratio of hydrofluorocarbon in the refrigerator working fluid composition of the present invention to the refrigerating machine oil containing the lubricating oil composition of the present invention is usually Hydrofluorocarbon / refrigerating machine oil = 50/1 to 1/20 (weight ratio), preferably 10
It is / 1-1 / 5 (weight ratio). When the hydrofluorocarbon / refrigerating machine oil ratio is higher than 50/1, the viscosity of the hydrofluorocarbon / refrigerating machine oil mixed solution becomes low, and the lubricity may deteriorate, which is not preferable. If the ratio of hydrofluorocarbon is lower than hydrofluorocarbon / refrigerating machine oil = 1/20, the refrigerating capacity may be insufficient, which is not preferable.

The hydrofluorocarbons used in the present invention include difluoromethane (HFC32), 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC143a) and 1,1,1,2-tetrafluorocarbon. Ethane (HFC134a), 1,1,2,2-Tetrafluoroethane (HFC134), Pentafluoroethane (HFC12)
5) etc., and particularly 1,1,1,2-tetrafluoroethane, difluoromethane, pentafluoroethane, and 1,1,1-trifluoroethane are preferable. These hydrofluorocarbons may be used alone, or two or more kinds of hydrofluorocarbons may be mixed and used.

[0143]

EXAMPLES The production examples and examples of the present invention will be described below, but the present invention is not limited thereto.

Production Example 1 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. D-
Sorbitol 336.8 g (1.85 mol), methyl ethyl ketone 800.0 g (11.1 mol), paratoluene sulfonic acid monohydrate 17.6 g (0.092 mo)
1) and 200 ml of hexane were charged into the flask. The reaction was carried out at 69 to 79 ° C under a nitrogen atmosphere at atmospheric pressure for 8 hours while distilling off water. After completion of the reaction, the mixture was cooled to 60 ° C., 19.6 g of sodium carbonate (0.185 mol, twice equivalent of paratoluenesulfonic acid) was added for neutralization, and 6
Stirred at 0 ° C. for 30 minutes. Add 200g of water, 60 ℃
After stirring for 30 minutes, the mixture was allowed to stand and separated into layers. After removing the lower layer, the solution was washed with 200 g of saturated saline, and hexane and excess methyl ethyl ketone were removed under reduced pressure using a rotary evaporator. Further, it was distilled under reduced pressure to obtain cyclic ketal A1 (hydroxyl value 12.9 mgKOH / g, gas chromatography purity 97.3%). Then, a part of the cyclic ketal A1 was further purified by column chromatography to give a cyclic ketal A2 (hydroxyl value 4.6 mg KO).
H / g, gas chromatography purity 99.1%) was obtained.

Production Example 2 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a calcium chloride tube, and a dehydration tube equipped with a condenser. D
-Sorbitol 450.0 g (2.47 mol), isobutyraldehyde 588.0 g (8.15 mol), paratoluenesulfonic acid monohydrate 4.7 g (0.025 m)
ol) and petroleum ether 400 having a boiling point of 30 to 60 ° C.
ml was charged to the flask. The reaction was performed for 15 hours while distilling off water at 40 to 65 ° C. under atmospheric pressure in a dry air atmosphere. After completion of the reaction, the mixture was cooled to 60 ° C., 5.24 g of sodium carbonate (0.049 mol, 2 times equivalent of paratoluenesulfonic acid) was added to neutralize, and the mixture was stirred at 60 ° C. for 30 minutes. Add 100 g of water and stir at 60 ° C. for 30 minutes,
The solution was allowed to stand and separated into layers. After removing the lower layer, saturated saline solution 100
Wash with g and remove petroleum ether and excess isobutyraldehyde under reduced pressure using a rotary evaporator. Further, it was distilled under reduced pressure to give cyclic acetal B (hydroxyl value 6.0 mgKOH / g, gas chromatography purity 9
9.0%) was obtained.

Production Example 3 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube with a condenser. Diglycerin 166.0 g (1.00 mol), methyl ethyl ketone 288.0 g (4.00 mol), paratoluenesulfonic acid monohydrate 3.8 g (0.020 mol),
And 100 ml of hexane were taken into the flask. The reaction was carried out under a nitrogen atmosphere at atmospheric pressure at 66 to 81 ° C. for 15 hours, and water was distilled off. After completion of the reaction, the mixture was cooled to 60 ° C., sodium carbonate 4.24 g (0.040 mol, twice the equivalent of paratoluenesulfonic acid) was added for neutralization, and the mixture was stirred at 60 ° C. for 30 minutes. 100 g of water was added, and the mixture was stirred at 60 ° C. for 30 minutes and allowed to stand to separate layers. After removing the lower layer, the mixture was washed with 100 g of water, and hexane and excess methyl ethyl ketone were removed under reduced pressure using a rotary evaporator. Further, the lower boiling point was removed by vacuum distillation. To 223.0 g of the obtained crude ketal, 0.6 g of activated alumina was added, and 5
Stirred at 0 ° C. for 30 minutes. After filtration, cyclic ketal C (hydroxyl value 15.7 mg KOH / g) was obtained.

Production Example 4 A 2-liter four-necked flask was equipped with a stirrer, a thermometer, a calcium chloride tube, and a dehydration tube equipped with a condenser. D
-Sorbitol 170.8 g (0.937 mol),
3,5,5-Trimethylhexanal 400.0 g
(2.81 mol), 1.78 g (0.0094 mol) of paratoluenesulfonic acid monohydrate, and hexane 40.
0 ml was taken in the flask. The reaction was carried out at 79 to 81 ° C. under atmospheric pressure in a dry air atmosphere for 8 hours, and water was distilled off. After the reaction was completed, the mixture was cooled to 70 ° C. and sodium carbonate was 1.99 g.
(0.019 mol, twice the equivalent of paratoluene sulfonic acid) was added for neutralization, and the mixture was stirred at 70 ° C. for 30 minutes. Water 1
00 g was added, the mixture was stirred at 60 ° C. for 30 minutes, and allowed to stand to separate layers. After removing the lower layer, the solution was washed with 100 g of a saturated saline solution, hexane was removed under reduced pressure using a rotary evaporator, and low-boiling components were further removed by reduced pressure distillation. 500.9 g of the obtained crude acetal was mixed with 5 parts of hexane.
After adding 00 ml and filtering through activated clay, hexane was removed under reduced pressure using a rotary evaporator to give a cyclic acetal D (hydroxyl value 27.2 mg KO).
H / g) was obtained.

Production Example 5 A 1-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. Diglycerin 166.0 g (1.00 mol), 3,5,5
-Trimethylhexanal 289.7 g (2.04 mo
l), 1.90 g of paratoluenesulfonic acid monohydrate
(0.010 mol) and 150 ml of hexane were taken in the flask. 8 at 75-92 ℃ under normal pressure under nitrogen stream
The reaction was carried out for a time, and the water was distilled off. After completion of the reaction, the mixture was cooled to 60 ° C. and 2.12 g of sodium carbonate (0.020 mo
1, 2 times equivalent of paratoluenesulfonic acid) was added to neutralize, and the mixture was stirred at 60 ° C. for 30 minutes. Add 100g of water,
The mixture was stirred at 60 ° C. for 30 minutes and allowed to stand to separate layers. After removing the lower layer, the solution was washed with 100 g of a saturated saline solution, hexane was removed under reduced pressure using a rotary evaporator, and low-boiling components were further removed by reduced pressure distillation. 1.2 g of activated alumina was added to 405.5 g of the obtained crude acetal, and 5
Stirred at 0 ° C. for 30 minutes. After filtration, cyclic acetal E (hydroxyl value 23.1 mgKOH / g) was obtained.

Production Example 6 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. 136 g (1.00 mol) of pentaerythritol, 230.5 g (1.77 mol) of 2-methylhexanoic acid, 2-
Ethyl pentanoic acid 94.1 g (0.72 mol), 2-
216.4 g (1.50 mol) of ethylhexanoic acid was charged into the flask. 250 ° C under normal pressure under nitrogen stream
After the reaction was carried out for 2 hours, the reaction was carried out under reduced pressure at 19.95 kPa for 6 hours. Then, the unreacted monocarboxylic acid was distilled under reduced pressure to obtain an ester compound F (acid value 0.01 mgKOH
/ G, and the hydroxyl value was 3.9 mgKOH / g).

Production Example 7 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. 136 g (1.00 mol) of pentaerythritol, 352.6 g (2.45 mol) of 2-ethylhexanoic acid, 3,
5,5-Trimethylhexanoic acid 245.0 g (1.55
mol) was charged to the flask. After performing the reaction at 250 ° C. for 2 hours under a nitrogen stream at atmospheric pressure, the reduced pressure reaction was performed at 19.95 kPa for 6 hours. Then, the unreacted monocarboxylic acid was distilled under reduced pressure to give an ester compound G (acid value 0.01 m
gKOH / g, hydroxyl value 4.2 mgKOH / g) was obtained.

Production Example 8 A 3 liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. Neopentyl glycol 104 g (1.00 mol), 2-
288.0 g (2.00 mol) of ethylhexanoic acid was charged into the flask. 250 ° C under normal pressure under nitrogen stream
After the reaction was carried out for 2 hours, the reaction was carried out under reduced pressure at 19.95 kPa for 6 hours. Then, the unreacted monocarboxylic acid was distilled under reduced pressure to obtain the ester compound H (acid value 0.01 mgKOH
/ G, hydroxyl value 3.5 mgKOH / g) was obtained.

Production Example 9 A 3-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydration tube equipped with a condenser. The flask was charged with 136 g (1.00 mol) of pentaerythritol and 568.0 g (4.00 mol) of 2-ethylhexanoic acid. The reaction was carried out at 250 ° C. for 2 hours under a nitrogen stream at atmospheric pressure, and then the reaction was performed under reduced pressure at 19.95 kPa for 6 hours. Then, the unreacted monocarboxylic acid was distilled under reduced pressure to give an ester compound I (acid value 0.01 mgKOH /
g, hydroxyl value 2.9 mg KOH / g) was obtained.

The cyclic ketals, cyclic acetals, and ester compounds obtained in Production Examples have kinematic viscosities (JIS K-2283) and pour points (JIS K-22 at 40 ° C. and 100 ° C.).
69) is shown in Table 1.

[0154]

[Table 1]

Example 1 Acid value and hydroxyl value of the inventive products 1 to 24 and comparative products 1 to 6 obtained by using the cyclic ketals, cyclic acetals and ester compounds used in the inventive products obtained in the production examples ( JIS
K-2501), kinematic viscosity at 40 ° C and 100 ° C (JI
SK-2283), pour point (JIS K-2269)
Was measured. The results are shown in Tables 2 and 3. As is clear from comparison between the product 4 of the present invention in Table 2 and the comparative product 6 in Table 3, it was confirmed that the ketal obtained from the monohydric alcohol and the ketone was 5
It is understood that the comparative product 6 in which 0% is mixed has a remarkable decrease in viscosity as compared with the inventive product 4.

[0156]

[Table 2]

[0157]

[Table 3]

Example 2 For the products 2 and 4 of the present invention and the comparative products 7 and 8 shown in Table 2,
The viscosity index (JIS K-2283) was examined. Table 4 shows the results. Further, the viscosity indexes of the products 8 and 9 of the present invention and the comparative products 8 and 9 shown in Table 2 were examined. Table 5 shows the results. Further, the viscosity indexes of the present invention products 10 and 11 and the comparative products 10 and 11 shown in Table 2 were examined. Table 6 shows the results. Further, the products 21 and 22 of the present invention shown in Table 3
The viscosity index of Comparative Products 12 and 13 was examined. Table 7 shows the results. As is clear from Tables 4 to 7, the product of the present invention has an improved viscosity index as compared with the comparative product. That is, the viscosity index is improved by incorporating the ester in an amount of 10% by weight or more.

[0159]

[Table 4]

[0160]

[Table 5]

[0161]

[Table 6]

[0162]

[Table 7]

Example 3 Inventive products 1 to 24 shown in Tables 2 and 3 and comparative products 2 to 5
Was examined for electrical insulation. The volume resistivity at 25 ° C was measured based on JIS C-2101. The results are shown in Tables 8 and 9. As is clear from Tables 8 and 9, the products of the present invention had a high volume resistivity, and all had good electrical insulation properties as compared with Comparative Examples 2 to 5.

[0164]

[Table 8]

[0165]

[Table 9]

Example 4 Inventive products 3, 7, 8 and comparative product 2 shown in Tables 2 and 3
The hygroscopicity of (polyalkylene glycol) was examined. Into a glass tube with an inner diameter of 18 mm and an internal volume of 10 ml, take 2 g of oil adjusted to a water concentration of 50 ppm or less in advance, and
The sample was placed in a constant temperature bath at 80 ° C. and 80% humidity. After leaving for a certain period of time, the water concentration of the oil is determined by the Karl Fischer method (JIS K-22
75). Table 10 shows the results. As is clear from Table 10, the product of the present invention had a significantly lower hygroscopicity than the polyalkylene glycol.

[0167]

[Table 10]

Example 5 The flash points of the products 3 to 5 of the present invention and the comparative product 6 shown in Tables 2 and 3 were measured. That is, regarding the invention products 3 to 5 and the comparative product 6, the tag closed flash point measuring device (JIS
K-2265) was used to measure the flash point. Table 11 shows the results. As is clear from Table 11, the products 3 to 5 of the present invention have higher flash points than the comparative product 6 which is a composition of a ketal and an ester obtained from a monohydric alcohol and a ketone.

[0169]

[Table 11]

Example 6 The compatibility of the present invention products 1 to 16 shown in Tables 2 and 3 and the comparative product 1 with hydrofluorocarbon as a refrigerant was examined. The product of the present invention (lubricating oil composition) 1 shown in Table 2
16 and 1,1,1,2-tetrafluoroethane (HFC134
The product of the present invention which is a composition with a) or a mixed refrigerant of 1,1,1,2-tetrafluoroethane, difluoromethane (HFC32) and pentafluoroethane (HFC125) (refrigerator working fluid composition) 25) to 45, and Table 3
The two-phase separation temperature at low temperature was measured for the comparative products 1 and HFC134a or the comparative products 14 and 15 each of which was a composition of a mixed refrigerant of HFC134a, HFC32, and HFC125 shown in FIG. The two-phase separation temperature was measured with the oil concentration in the refrigerator working fluid composition being 10, 20, 30, 40 and 50% by volume. The results are shown in Tables 12 and 13. The product of the present invention has excellent solubility in each refrigerant as compared with the comparative product. As can be seen by comparing the products of the present invention 25 and 27 and 30 and 32, the lower the hydroxyl value, the better the solubility with the hydrofluorocarbon.

[0171]

[Table 12]

[0172]

[Table 13]

Example 7 With respect to the products of the present invention (refrigerator working fluid compositions) 25 to 45 shown in Tables 12 and 13, a shield tube test was conducted under the following conditions to examine thermal stability. That is, the water concentration is 10 ppm or less and the acid value is 0.03 in advance.
10 g of lubricating oil adjusted to (mgKOH / g) or less and 5 g of hydrofluorocarbon were placed in a glass tube, and iron, copper, and aluminum were added as a catalyst to seal the tube. 175
After testing at 14 ° C for 14 days, the appearance of the composition of hydrofluorocarbon and oil and the presence or absence of deposits were observed, the sealed tube was opened to remove the hydrofluorocarbon, and the acid value of the oil was examined. The results are shown in Tables 14 and 15. As is clear from Tables 14 and 15, all the products of the present invention had a good appearance, no precipitate, no increase in acid value, and good thermal stability.

[0174]

[Table 14]

[0175]

[Table 15]

Example 8 The product of the present invention (refrigerator working fluid composition) 25 to 45 shown in Tables 12 and 13 and a composition of cyclic ketal or cyclic acetal and ester (refrigerator working fluid composition) Compositions) 46-48, and comparative products 3-5 shown in Table 3.
Comparative products 16 to 18, which are a composition of and 1,1,1,2-tetrafluoroethane, were subjected to a shield tube test under the following conditions in order to examine the thermal stability in the presence of water. That is, the lubricating oil 10 having a water concentration adjusted to 3000 ppm and an acid value adjusted to 0.03 (mgKOH / g) or less in advance.
g and 5 g of hydrofluorocarbon were placed in a glass tube, and iron, copper, and aluminum were added as a catalyst, and the tube was sealed. After testing at 175 ° C. for 28 days, the appearance of the hydrofluorocarbon and oil composition and the presence or absence of deposits were observed,
After opening the sealed tube and removing the hydrofluorocarbon,
The acid number of the oil was investigated. The results are shown in Tables 16 and 17. As is clear from Tables 16 and 17, the products of the present invention have better appearance than the comparative products, no precipitates, little increase in acid value, and thermal stability in the presence of water. It was good. By incorporating 5% by weight or more of the cyclic ketal, the thermal stability in the presence of water is remarkably improved.

[0177]

[Table 16]

[0178]

[Table 17]

Example 9 The wear resistance of the products 31, 36 and 37 of the present invention shown in Table 16 and the comparative products 16 to 18 shown in Table 17 were set to Falex.
It was examined using a test. Warm 100 ml of oil to 80 ° C,
1,1,1,2-Tetrafluoroethane (HFC134a) was blown in at 10 liters per hour and operated for 4 hours under a load of 150 (lb), and the amount of wear of the V-block and the pin after the operation was examined. The results are shown in Table 18. As is clear from Table 18,
The products of the present invention had less wear than the comparative products and were excellent in wear resistance.

[0180]

[Table 18]

Example 10 Products of the present invention (refrigerator working fluid composition) 25 to 45 shown in Tables 12 and 13 and comparative products 2 to 5 and 1 shown in Table 3
Comparative product 1 which is a composition with 1,1,2-tetrafluoroethane
Regarding 6 to 19, the influence on the organic material when water was mixed was examined. That is, take 10 g of oil and 5 g of hydrofluorocarbon in a glass tube, and add water to the oil in an amount of 500 ppm.
In addition, a PET film (trade name: Lumirror X-10 (manufactured by Toray)) was added and the tube was sealed. After testing at 130 ° C. for 7 days, the sealed tube was opened, the hydrofluorocarbon was removed, and then the acid value of the oil and the tensile strength of the PET film were measured. The results are shown in Tables 19 and 20. The tensile strength is shown as a relative value with 1.00 before the test. As is clear from Table 19 and Table 20, the products 25 to 45 of the present invention are
There is no increase in acid value compared to the comparative products 16 to 19, and PE
No decrease in tensile strength of the T film was observed.

[0182]

[Table 19]

[0183]

[Table 20]

[0184]

EFFECT OF THE INVENTION The present invention provides a lubricating oil composition which is excellent in thermal stability and electric insulation, does not generate carboxylic acid due to hydrolysis, has low hygroscopicity, and is inexpensive. Also,
By blending such a lubricating oil composition with hydrofluorocarbon, it is possible to provide an inexpensive refrigerator working fluid composition having excellent compatibility, excellent electric insulation, excellent hygroscopicity, no generation of carboxylic acid due to hydrolysis, and low cost. be able to.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication C10M 105: 32) C10N 30:08 40:16 40:30 (72) Inventor Yuichiro Kobayashi Minato, Wakayama City 1334 Kao Research Institute

Claims (13)

[Claims] 1. A kinematic viscosity at 100 ° C. of 0.1 to 10
A lubricating oil composition comprising an ester compound of 0 mm ² / s and a cyclic ketal or a cyclic acetal. 2. A cyclic ketal or a cyclic acetal, and one or more polyhydric alcohols having an even valence of 4 or more and 10 or less, and a general formula (I): (In the formula, R ¹ represents a hydrogen atom or a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms, and R ² represents a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms. Alternatively, R ¹ and R ² together form 2 carbon atoms.
~ 36 alkylene groups are shown. The lubricating oil composition according to claim 1, which is obtained from at least one of a carbonyl compound represented by the formula (1) or a reactive derivative thereof, a ketal or an acetal. 3. A cyclic ketal or a cyclic acetal, and one or more polyhydric alcohols having an even valence of 4 or more and 8 or less and a general formula (II): (In the formula, R ³ is a hydrogen atom or a straight chain having 1 to 12 carbon atoms,
A branched or cyclic alkyl group is shown, and R ⁴ is a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ are taken together and have 2 to 1 carbon atoms.
3 represents an alkylene group. The total carbon number of R ³ and R ⁴ is 1
~ 13. 1) a carbonyl compound or a reactive derivative thereof, ketal or acetal
The lubricating oil composition according to claim 1, which is obtained from one or more species. 4. The lubricating oil composition according to claim 2 or 3, wherein the polyhydric alcohol has no ether bond or has one ether bond. 5. The cyclic ketal or cyclic acetal is
The lubricating oil composition according to any one of claims 1 to 4, which comprises a 1,3-dioxolane structure and / or a 1,3-dioxane structure. 6. A ketal or a cyclic ketal or a cyclic acetal which is a tetravalent or hexavalent saturated aliphatic alcohol having 4 to 20 carbon atoms and a carbonyl compound represented by the general formula (II) or a reactive derivative thereof. It is obtained from one or more kinds of acetals.
The lubricating oil composition described. 7. The cyclic ketal or cyclic acetal is represented by the formula (III) or (IV): (In the formula, R ³ is a hydrogen atom or a straight chain having 1 to 12 carbon atoms,
A branched or cyclic alkyl group is shown, and R ⁴ is a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ are taken together and have 2 to 1 carbon atoms.
3 represents an alkylene group. The total carbon number of R ³ and R ⁴ is 1
~ 13. ) The lubricating oil composition according to claim 1, which is represented by 8. The cyclic ketal or cyclic acetal is represented by the formula (V) or (VI): (In the formula, R ³ is a hydrogen atom or a straight chain having 1 to 12 carbon atoms,
A branched or cyclic alkyl group is shown, and R ⁴ is a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms. Alternatively, R ³ and R ⁴ are taken together and have 2 to 1 carbon atoms.
3 represents an alkylene group. The total carbon number of R ³ and R ⁴ is 1
~ 13. ) The lubricating oil composition according to claim 1, which is represented by 9. The mixing ratio of the ester compound and the cyclic ketal or cyclic acetal in the lubricating oil composition is such that the ester compound / cyclic ketal, cyclic acetal = 10/90 to.
It is 99/1 (weight ratio), The lubricating oil composition of any one of Claims 1-8. 10. The ester compound comprises: A) a C2 to C2 to C10 polyhydric alcohol or a C1 to C50 monohydric alcohol, and a C2 to C50 carboxylic acid or derivative thereof. B) a monohydric alcohol having 1 to 50 carbon atoms and 2 to 5 carbon atoms
An ester obtained from a 0 to 2 to 10 valent polycarboxylic acid or a derivative thereof, C) a 2 to 10 valent polyalcohol having 2 to 50 carbon atoms,
A monovalent carboxylic acid having 2 to 50 carbon atoms or a derivative thereof,
And an ester obtained from a C2 to C2 to C10 polyvalent carboxylic acid or derivative thereof, and D) C2 to C2 to C10 polyhydric alcohol and C1 to C1 A polyhydric alcohol and 2 to 50 carbon atoms
10. A lubricating oil composition according to any one of claims 1 to 9, wherein the lubricating oil composition is selected from the group consisting of an ester obtained from a divalent to 10-valent polycarboxylic acid or a derivative thereof. . 11. An ester compound comprising A ′) a C 2-10 divalent to polyvalent aliphatic polyhydric alcohol or a C 1-10 saturated aliphatic monohydric alcohol, and a C 2-9 straight chain. Obtained from a chain or branched saturated aliphatic monovalent carboxylic acid or a derivative thereof, B ′) a saturated aliphatic monohydric alcohol having 1 to 10 carbon atoms and a saturated divalent to hexavalent carbon atom having 2 to 10 carbon atoms Ester obtained from aliphatic polycarboxylic acid or its derivative, C ') C2-C2-6-valent aliphatic polyhydric alcohol, and C2-C9 straight-chain or branched-chain saturated fat Tribe 1
Carboxylic acid or its derivative, and carbon number 2 to 1
0, an ester obtained from a linear or branched saturated aliphatic divalent carboxylic acid or a derivative thereof, and D ′) a linear or branched saturated aliphatic dihydric alcohol having 2 to 10 carbon atoms and the number of carbon atoms 1 to 10 linear or branched saturated aliphatic monohydric alcohols, and esters obtained from C 2 to C 2-6 saturated aliphatic polyvalent carboxylic acids or derivatives thereof, selected from the group consisting of: The lubricating oil composition according to any one of claims 1 to 9, wherein the lubricating oil composition comprises: 12. A refrigerator working fluid composition containing hydrofluorocarbon and a refrigerating machine oil containing the lubricating oil composition according to claim 11. 13. Hydrofluorocarbon and refrigerating machine oil, wherein hydrofluorocarbon / refrigerating machine oil = 50/1.
The working fluid composition for a refrigerator according to claim 12, wherein the working fluid composition is contained in an amount of ˜1 / 20 (weight ratio).