JPH1036874A - Refrigeration oil composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] As a lubricating oil exclusively for a compressor using an HFC-based refrigerant, the lubricating oil has thermal and chemical stability, abrasion resistance, load resistance, and HFC.
It has excellent compatibility with system-based refrigerants, and it can be used for a long period of time by suppressing the generation of sludge due to the deterioration of cyclic ketals and cyclic acetals. Another object of the present invention is to provide a refrigerating machine oil that can sufficiently cope with the problem. A cyclic ketal obtained from at least one kind of polyhydric alcohol having an even number of valence of 4 to 10 and at least one kind of ketal or acetal which is a specific carbonyl compound or a reactive derivative thereof. Alternatively, a cyclic acetal is used as a base oil, and a. 0.5 to 15.0% by mass of a phosphate ester, b. 0.1 to 5.0% by weight of an alkyl phosphorothionate and / or an aryl phosphorothionate, and c. A refrigerating machine oil composition for a compressor using a hydrofluorocarbon as a refrigerant and containing an epoxy compound in an amount of 0.05 to 3.0% by mass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a refrigerating machine oil composition used for a compressor using hydrofluorocarbon (HFC) as a refrigerant.

More specifically, it is a lubricating oil composition which uses a specific cyclic ketal or cyclic acetal as a base oil, suppresses the formation of sludge, and has no lack of lubricity, and is used under the most severe lubricating conditions among compressors. The present invention relates to a refrigerating machine oil composition which can also be used for a rotary compressor to be used.

[0003]

[Prior art]

1. General required performance of refrigerating machine oil The main types of refrigerating machine compressors include reciprocating type, scroll type and rotary type. Among them, rotary compressors are used under the most severe lubrication conditions.

[0004] Regardless of the type of compressor, the most important general properties required for refrigerating machine oil are abrasion resistance, load bearing capacity, thermal and chemical stability, low-temperature fluidity, compatibility with the refrigerant used. It is. The refrigerating machine oil has a role of preventing wear and cooling of a sliding portion of the compressor, sealing high and low pressure portions in a refrigerant gas compression process, and removing wear powder and foreign matter. For this reason,
The performance of refrigerating machine oil is not only excellent in abrasion resistance and load-bearing ability, but also high in thermal and chemical stability in coexistence with equipment such as used refrigerant, electric insulating material and metal.
Equipment that does not affect equipment is required. Further, a part of the refrigerating machine oil is mixed into the compressed refrigerant gas, circulates in the refrigerating system together with the refrigerant, and flows into the evaporator via a capillary tube or an expansion valve. In order to improve the oil return from the evaporator to the compressor, and to refuel the sliding parts of the compressor when restarting at low temperature, the low-temperature fluidity and high compatibility with the used refrigerant are refrigerated. Required for machine oil.

[0005] 2. Relationship between Refrigerant Used and Refrigerator Oil As a refrigerant used in a compressor of a refrigerator, a chlorofluorocarbon (CFC) -based refrigerant and a hydrochlorofluorocarbon (HCFC) -based refrigerant have been conventionally used alone or in combination. Since all of these refrigerants have low polarity, they have good compatibility with non-polar hydrocarbon oils (mineral oil, alkylbenzene, poly-α-olefin, etc.).
These refrigerants are chlorine-containing refrigerants having a chlorine atom in the molecule. The chlorine atoms react with the sliding material on the sliding surface of the compressor to generate a chloride serving as a lubricant. In addition, hydrocarbon-based oils have good lubricity.

For this reason, chlorofluorocarbon (CF)
C) based refrigerants and hydrochlorofluorocarbon (HCF)
C) Refrigerators that use system refrigerants include antioxidants and anti-wear agents in base oils that contain hydrocarbon oils such as naphthenic mineral oil, paraffinic mineral oil, alkylbenzene, and poly-α-olefins alone or mixed appropriately. Refrigeration oil containing a small amount of an additive, a corrosion inhibitor or the like is generally used.

[0007] Incidentally, phosphate esters have low solubility in hydrocarbon-based oils and exhibit a wear-preventing effect at low concentrations. For this reason, the phosphate ester is usually used in an amount of 1% by mass or less based on the hydrocarbon base oil.

Since the theory that the ozone layer in the stratosphere is destroyed by chlorine-containing refrigerants has been published, CFC-based refrigerants and HCFCs have been internationally used to protect the global environment.
Regulations on the production of system refrigerants are being planned, and alternatives that do not have chlorine atoms in the molecule are being studied. For example, HCFC
As an alternative to -22 (R-22), HFC-134
a, HFC-143a, HFC-125, HFC-32
It is expected that an HFC-based refrigerant mixed with such a hydrofluorocarbon (HFC) -based refrigerant will be used. But,
HFC-based refrigerants have higher polarity than CFC-based refrigerants and HCFC-based refrigerants, and therefore have poor compatibility with hydrocarbon-based oils. Further, the HFC-based refrigerant does not have a chlorine atom in the molecule, and thus has a low anti-wear property. Therefore, it is difficult for a conventional lubricating oil technology for a refrigerator using a CFC-based refrigerant or an HCFC-based refrigerant to cope with a refrigerator using a new refrigerant, an HFC-based refrigerant. For this reason, there is a strong demand for the development of refrigerating machine oil suitable for HFC-based refrigerants.

3. Conventional technology of refrigerating machine oil for HFC-based refrigerants Lubricating oils for refrigerating machines using HFC-based refrigerants include polyether-based synthetic oils and ester-based synthetic oils.
Oxygen-containing synthetic oils compatible with HFC-based refrigerants have been studied. The stability of polyether synthetic oils is concerned because the ether bond in the molecule is thermally weak. Ester-based synthetic oils have characteristics such as better electrical insulation, better compatibility with refrigerants at high temperatures, and lower hygroscopicity than polyether-based synthetic oils. However, there is a concern that the ester, when containing water, undergoes hydrolysis to generate a carboxylic acid, and the generated carboxylic acid corrodes the metal and causes abrasion.

As a substance having a structure in which a carboxylic acid is not generated by hydrolysis or the like, a cyclic ketal or a cyclic acetal is known. Conventional applications of cyclic ketals and cyclic acetals include organic solvents, solvents such as inks and paints,
Additives or gelling agents, polymer raw materials, and dehydrating agents for refrigerator oil are known. Japanese Patent Application Laid-Open No. 4-3 / 1993 discloses a method of using a cyclic ketal or a cyclic acetal as a working fluid for a refrigerator.
20498 and JP-A-6-57243.

In the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-320498, 1
It is disclosed that a ketal or acetal obtained from a polyhydric alcohol or a dihydric alcohol and a ketone or an aldehyde is used by blending with an ester or a polyalkylene glycol-based synthetic lubricating oil. Acetals and ketals have the disadvantages of low molecular weight, low boiling point and low flash point. JP-A-6-57243 discloses esters of glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and carbonate derivatives containing a ketal or acetal group in the molecule. However, there is a drawback that two or more ether bonds are contained in the molecule, and the improvement of electric insulation is not sufficient. Conventional cyclic ketals and cyclic acetals have problems in melting point, stability, gelation, viscosity, etc., and also have the disadvantage of causing a specific viscosity decrease in compressors that become hot, so they are used for refrigeration oils. Was not suitable.

Incidentally, WO 96/06839 (International Publication Date: March 7, 1996) discloses a synthetic lubricating oil having a specific structure as a base oil, such as a cyclic ketal or a cyclic acetal, and the use of this synthetic lubricating oil. Refrigerator working fluid compositions are disclosed. The cyclic ketal or cyclic acetal disclosed in WO 96/06839 makes use of the feature of the cyclic ketal or cyclic acetal that a carboxylic acid is not generated by hydrolysis or the like, and furthermore,
It has excellent electrical insulation and compatibility with HFC-based refrigerants at high temperatures.

[0013]

The cyclic ketal and the cyclic acetal are chemically active as compared with hydrocarbon-based oils, and thus cause sludge formation in a high-temperature compressor. Further, since the HFC-based refrigerant has no chlorine atom in the molecule, lubricating properties are insufficient in a compressor having severe lubrication conditions. In particular, since rotary compressors are used under more severe lubrication conditions than reciprocating compressors and scroll compressors, higher wear resistance and higher thermal and chemical stability are required. Among the rotary compressors, the compact and high-output rotary compressors equipped with an inverter system have the most severe lubrication conditions, so the refrigerating machine oil used for them has even higher wear resistance and thermal and chemical stability. Is required.

An object of the present invention is to provide a lubricating oil exclusively for a compressor using an HFC-based refrigerant, which has excellent performance in thermal and chemical stability, abrasion resistance, load-bearing capacity, and compatibility with the HFC-based refrigerant. In addition to providing refrigerating machine oil that can be used for a long period of time by suppressing the generation of sludge due to the deterioration of cyclic ketals and cyclic acetals, and that can sufficiently cope with rotary compressors of any capacity and output is there.

[0015]

Means for Solving the Problems The present inventors have proposed the above W
O 96/06839, using specific cyclic ketals and cyclic acetals as base oils, and in order to solve sludge formation and lack of lubricity, additives compatible with these are selected from various types of additives. I searched. As a result of repeated experiments and studies, a combination of additives compatible with the above-mentioned cyclic ketals and acetals and an optimum blending ratio thereof have been found, and the present invention capable of responding to a rotary compressor with severe lubrication conditions has been completed. succeeded in.

The present invention is a refrigerating machine oil composition for a compressor using hydrofluorocarbon as a refrigerant. The hydrofluorocarbon may be used alone or in a mixed refrigerant in which these are mixed.

The constitution of the present invention is as follows. At least one kind of polyhydric alcohol having an even number of valence of from 1.4 to 10 and at least one kind of ketal or acetal which is a carbonyl compound represented by the following general formula (1) or a reactive derivative thereof. The cyclic ketal or cyclic acetal obtained from the above is used as a base oil, and a. 0.5 to 15.0% by mass of a phosphate ester, b. 0.1 to 5.0% by weight of alkylphosphorothionate and / or arylphosphorothionate, and c. An epoxy compound is blended in an amount of 0.05 to 3.0% by mass.

[0018]

Embedded image

(Wherein R ¹ is a hydrogen atom or a group having 1 to 1 carbon atoms)
It represents 18 linear or branched alkyl groups or cyclic saturated hydrocarbons. R ² represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon. Alternatively, R ¹ and R ² together with the carbon atom to which they are attached form a saturated hydrocarbon ring, having 2 to 3 carbon atoms
6 represents an alkylene group. )

2. The base oil includes at least one kind of polyhydric alcohol having an even number of valences of 4 to 8 and a carbonyl compound represented by the following general formula (2) or a ketal or acetal which is a reactive derivative thereof. It is preferable to contain a cyclic ketal or a cyclic acetal obtained from at least one kind.

[0021]

Embedded image

(Wherein, R ³ is a hydrogen atom or a C 1 -C 1)
It represents 12 linear or branched alkyl groups or cyclic saturated hydrocarbons. R ⁴ represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cyclic saturated hydrocarbon. Alternatively, R ³ and R ⁴ together with the carbon atom to which they are attached form a saturated hydrocarbon ring, having 2 to 13 carbon atoms
Represents an alkylene group. The total carbon number of R ³ and R ⁴ is 1 to
Thirteen. )

3. The base oil preferably contains a cyclic ketal or a cyclic acetal represented by the following general formula (3) or (4).

[0024]

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(In each of the above formulas, R ⁵ represents a hydrogen atom, and in this case, R ⁶ represents a branched alkyl group having 3 carbon atoms or a linear or branched alkyl group having 4 to 21 carbon atoms. , R ⁵ represents a linear or branched alkyl group having 1 to 21 carbon atoms, in which case R ⁶ represents a linear or branched alkyl group having 2 to 21 carbon atoms.)

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

1. Base oil In the present invention, the following cyclic ketal or cyclic acetal is used as the base oil. a. From at least one kind of polyhydric alcohol having an even number of valences of not less than 4 and not more than 10 and at least one kind of ketal or acetal which is a carbonyl compound represented by the following general formula (1) or a reactive derivative thereof. The resulting cyclic ketal or cyclic acetal.

[0027]

Embedded image

(Wherein R ¹ is a hydrogen atom or a group having 1 to 1 carbon atoms)
It represents 18 linear or branched alkyl groups or cyclic saturated hydrocarbons. R ² represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon. Alternatively, R ¹ and R ² together with the carbon atom to which they are attached form a saturated hydrocarbon ring, having 2 to 3 carbon atoms
6 represents an alkylene group. If the valency of the polyhydric alcohol is more than 10, the resulting cyclic ketal or cyclic acetal will have too high a viscosity. On the other hand, if the valency of the polyhydric alcohol is less than 4, the boiling point and the flash point are undesirably low. If the valence of the polyhydric alcohol is odd, unreacted hydroxyl groups remain, increasing the viscosity and deteriorating the compatibility with the HFC-based refrigerant, which is not preferable.

The ketone or aldehyde represented by the general formula (1) has 2 to 37 carbon atoms. If the number of carbon atoms exceeds 37, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, which is not preferable. .

When the number of carbon atoms of R ¹ or R ² exceeds 18, or when the number of carbon atoms of the alkylene group which forms a saturated hydrocarbon ring together with the carbon atom to which R ¹ and R ² are bonded is, When it exceeds 36, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, which is not preferable.

The above-mentioned polyhydric alcohol has a valency of 4, and 6
Valence and octavalent are preferred. The cyclic ketal or cyclic acetal in this case is as follows.

B. From one or more polyhydric alcohols having an even number of valences of 4 to 8 and at least one of a carbonyl compound represented by the following general formula (2) or a ketal or acetal which is a reactive derivative thereof. The resulting cyclic ketal or cyclic acetal.

[0033]

Embedded image

(Wherein R ³ is a hydrogen atom or a group having 1 to 1 carbon atoms)
It represents 12 linear or branched alkyl groups or cyclic saturated hydrocarbons. R ⁴ represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cyclic saturated hydrocarbon. Alternatively, R ³ and R ⁴ together with the carbon atom to which they are attached form a saturated hydrocarbon ring, having 2 to 13 carbon atoms
Represents an alkylene group. The total carbon number of R ³ and R ⁴ is 1 to
Thirteen. )

The above b. The polyhydric alcohol is more preferably tetravalent or hexavalent in view of viscosity, boiling point and flash point.

The ketone or aldehyde represented by the above general formula (2) has 2 to 25 carbon atoms. If the number of carbon atoms exceeds 25, the compatibility of the obtained cyclic ketal or cyclic acetal with the HFC-based refrigerant is reduced. May drop. R ³
Alternatively, when R ⁴ has more than 12 carbon atoms, or when R ³ and R
^{When the} number of carbon atoms of the alkylene group which forms a saturated hydrocarbon ring together with the carbon atom bonded to these is more than 13, the compatibility of the obtained cyclic ketal or cyclic acetal with the HFC-based refrigerant is poor. May drop.

The above a. Or b. Are those having 4 to 25 carbon atoms. If the number of carbon atoms exceeds 25, the viscosity of the obtained cyclic ketal or cyclic acetal becomes too high, which is not preferable. On the other hand, if the number of carbon atoms is smaller than 4, the boiling point and the flash point are undesirably low.

The above a. Or b. Is a saturated aliphatic alcohol. Having an unsaturated bond is not preferred because thermal stability is deteriorated.

The above a. Or b. The polyhydric alcohol is preferably one having no ether bond in the molecule or one having one ether bond from the viewpoint of having good electric insulating properties. When it has two or more ether bonds, the electrical insulation is deteriorated.

Further, from the viewpoint of enhancing the electrical insulation, a cyclic ketal or cyclic acetal having no ether bond in the molecule, a cyclic ketal or cyclic acetal having one ether bond has a 1,3-dioxolane structure and And / or a 1,3-dioxane structure, for example, those represented by the following general formula.

[0041]

Embedded image

[0042]

Embedded image

(In each of the above formulas (5) to (10), R
³ represents a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or a cyclic saturated hydrocarbon. R ⁴ is
It represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cyclic saturated hydrocarbon. Alternatively, R ³ and R ⁴ represent an alkylene group having 2 to 13 carbon atoms which forms a saturated hydrocarbon ring together with the carbon atom to which they are bonded. The total carbon number of R ³ and R ⁴ is 1 to 13. Note that a. And b. As a reactive derivative of the carbonyl compound of formula (I), a carbonyl compound (ketone, aldehyde) represented by the above general formula (1) or (2) is
And ketals and acetal synthesized from lower alcohols of No. 6 with an acid catalyst.

C. A cyclic ketal or a cyclic acetal represented by the following general formula (3) or (4).

[0045]

Embedded image

(In each of the above formulas (3) and (4), R ⁵ represents a hydrogen atom. In this case, R ⁶ is a branched alkyl group having 3 carbon atoms, or a linear or branched alkyl group having 4 to 21 carbon atoms. R ⁵ represents a linear or branched alkyl group having 1 to 21 carbon atoms, in which case R ⁶ represents a linear or branched alkyl group having 2 to 21 carbon atoms. .)

The cyclic ketal or cyclic acetal represented by the general formula (3) or (4) is a compound including the cyclic ketal or cyclic acetal represented by the general formula (5) or (6).

In the above general formula (3) or (4), R
⁵ is a hydrogen atom and R ⁶ is a branched alkyl group having 3 carbon atoms or a linear or branched alkyl group having 4 to 12 carbon atoms, or R ⁵ is a linear or branched alkyl group having 1 to 12 carbon atoms and R ⁶ is preferably a linear or branched alkyl group having 2 to 12 carbon atoms.

In the above general formula (3) or (4),
⁵ is a hydrogen atom and R ⁶ is a branched alkyl group having 3 carbon atoms or a branched alkyl group having 3 to 12 carbon atoms, or R ⁵ is a linear or branched alkyl group having 1 to 12 carbon atoms, and R ⁶ is a carbon atom. More preferably, it is a linear or branched alkyl group having the number of 2 to 12.

The cyclic ketal or cyclic acetal represented by the above general formulas (2) to (10) is usually obtained as a mixture of all or part of the cyclic ketal or cyclic acetal represented by each general formula.

The cyclic ketal or cyclic acetal used in the present invention generally has a viscosity of 5 to 150 mm2 / s (40
° C), acid value 1 mgKOH / g or less, moisture 500
ppm or less can be used. Distilled, filtered, treated with an adsorbent and a dehydrating agent to remove impurities, contaminants, and moisture that affect thermal stability, having a viscosity of 5 to 150 mm2 / s (4
0 ° C), acid value 0.01 mgKOH / g or less, moisture 100
ppm or less is preferred.

The chlorine-containing refrigerant (CFC refrigerant, HC
Naphthenic mineral oil, paraffinic mineral oil, alkylbenzene, poly-α-olefin, and the like used in FC refrigerants) have poor compatibility with HFC refrigerants and cannot be used as the base oil of the refrigerator oil composition of the present invention. .

2. Additives (1) Phosphoric acid ester Examples of the phosphoric acid ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, and cresyl. Examples include diphenyl phosphate, diphenyl orthoxenyl phosphate, octyl diphenyl phosphate, phenyl isopropyl phenyl phosphate, diphenyl isopropyl phenyl phosphate, tris (isopropyl phenyl) phosphate, tris (chloroethyl) phosphate, and tris dichloro propyl phosphate.

Among them, tricresyl phosphate, phenylisopropylphenyl phosphate, diphenylisopropylphenyl phosphate, and tris (isopropylphenyl) phosphate are particularly preferable.

Phosphoric esters are extremely compatible with the cyclic ketals or cyclic acetals used as the base oil of the present invention. In addition, when used in combination with the following alkylphosphorothionates or arylphosphorothionates, there is an effect that the wear resistance is improved due to a synergistic effect as compared with the case where they are used alone.

The mixing ratio of the phosphate ester is 0.5 to 1 with respect to the cyclic ketal or cyclic acetal base oil.
It is 5.0% by mass. 0.5 mass% or more and less than 5.0 mass% are preferable. When the mixing ratio of the phosphoric acid ester is less than 0.1% by mass, the combined use with the alkylphosphorothionate or the arylphosphorothionate has no effect, and the abrasion resistance is not sufficient. When the mixing ratio is more than 15.0% by mass,
The effect corresponding to the increase is not obtained, and the wear resistance is reduced.

When the mixing ratio of the phosphate ester is 0.5
Those having a mass percentage of less than 5.0 mass% are most suitable for a small, high-output rotary compressor used under the most severe lubrication conditions. Those with a mixing ratio of phosphate ester of 5.0% by mass or more and 15.0% by mass or less are most suitable for other rotary compressors having mild lubricating conditions as compared with small, high-output rotary compressors. Since the base oil is expensive, the more the proportion of the phosphate ester, the cheaper and more economical.

(2) Alkyl phosphorothionate, aryl phosphorothionate Examples of the alkyl phosphorothionate include trimethyl phosphorothionate, triethyl phosphorothionate, tributyl phosphorothionate, and trioctyl phosphorothionate. And tridecylphosphorothionate, trilaurylphosphorothionate.

The aryl phosphorothionates include:
An example is triphenylphosphorothionate.

The alkyl phosphorothionates and aryl phosphorothionates may be used alone or in combination.

The alkylphosphorothionates and arylphosphorothionates are extremely compatible with the cyclic ketal or cyclic acetal used as the base oil of the present invention. In addition, when used in combination with the above-mentioned phosphate ester, there is an effect that the wear resistance is improved due to a synergistic effect as compared with the case where the phosphate ester is used alone.

The mixing ratio of the alkyl phosphorothionate and / or the aryl phosphorothionate is 0.1 to 0.1 with respect to the cyclic ketal or the cyclic acetal base oil.
It is 5.0% by mass. If the compounding ratio is less than 0.1% by mass, the abrasion resistance is not improved, and if the compounding ratio is more than 5.0% by mass, the effect corresponding to the added amount cannot be obtained.

(3) Epoxy compound Examples of the epoxy compound include phenyl glycidyl ether, alkylphenyl glycidyl ether,
2-epoxyalkanes and vinylcyclohexene dioxide can be used. These may be used alone or in combination. Among them, 1,2-epoxyalkane,
Vinyl cyclohexene dioxide is preferred.

Examples of the alkyl phenyl glycidyl ether include butyl phenyl glycidyl ether, pentyl phenyl glycidyl ether, hexyl phenyl glycidyl ether, heptyl phenyl glycidyl ether, octyl phenyl glycidyl ether, nonyl phenyl glycidyl ether, and decyl phenyl glycidyl ether.

Examples of the 1,2-epoxyalkane include 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxyhdecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane,
Examples thereof include 1,2-epoxyheptadecane and 1,2-epoxyoctadecane.

The epoxy compound has good compatibility with the cyclic ketal or cyclic acetal used as the base oil of the present invention.
This has the effect of suppressing sludge formation due to the deterioration of the cyclic ketal or cyclic acetal.

The mixing ratio of the epoxy compound is from 0.05 to 3% based on the cyclic ketal or cyclic acetal base oil.
0% by mass. If the compounding ratio is less than 0.05% by mass,
In addition to the insufficient effect of suppressing cyclic ketal or cyclic acetal deterioration, it also has a negative effect on thermal and chemical stability.
When the compounding ratio exceeds 3.0% by mass, the solubility in the refrigerant, the cyclic ketal or the cyclic acetal becomes poor, and the generation of sludge resulting from the increase in the added amount is affected.

(4) Other Additives The refrigerating machine oil composition of the present invention contains an antioxidant which is generally used as a refrigerating machine oil additive within a range satisfying the performance of the refrigerating machine oil aimed at by the present invention. Metal deactivators, defoamers, and others can be used in combination.

Examples of the antioxidant include hindered phenol-based, amine-based and sulfur-based antioxidants, for example, 2,6-
Di-t-butyl-4-methylphenol, 4,4′-methylenebis (2,6-di-t-butylphenol),
2,2'-thiobis (4-methyl-6-t-butylphenol), trimethyldihydroquinone, p, p'-dioctyldiphenylamine, 3,7-dioctylphenothiazine, alkylphenothiazine-1-carboxylate, phenyl-2-naphthylamine , 2,6-di-t
-Butyl-2-dimethyl-p-cresol, 5-ethyl-10,10'diphenylphenazaline, alkyl disulfide can be used.

As the metal deactivator, for example, alizanin, chilizanine, benzotriazole, oil-soluble benzotriazole, mercaptobenzotriazole can be used.

As the antifoaming agent, for example, dimethylpolysiloxane and metal carboxylate can be used.

[0072]

EXAMPLES Examples and comparative examples of the present invention will be described below. The present invention is not limited to the embodiments. The compositions, test methods and test results of the base oils and additives used in Examples and Comparative Examples are as follows.

1. Composition (1) Examples 1-20, Comparative Examples 1-17 a. Base oil A mixture of cyclic ketals represented by the above general formulas (5) and (6) ("KAOLUBE700" manufactured by Kao Corporation) having a total acid value of 0.01 mgKOH / g or less and a water content of 100 ppm or less was used.

B. Additives As the phosphate ester, tricresyl phosphate was used. As the aryl phosphorothionate, triphenyl phosphorothionate was used. As the alkyl phosphorothionate, trioctyl phosphorothionate was used. As the epoxy compound, vinylcyclohexene dioxide was used.

(2) Comparative Example 18 a. ABA-H (hard type alkylbenzene manufactured by Mitsubishi Chemical Corporation) was used as the base oil alkylbenzene. In addition, alkylbenzene is generally used as a base oil of refrigerating machine oil of a refrigerator using HCFC-22 refrigerant.

B. Additives As the phosphate ester, tricresyl phosphate was used. The compounding ratio of the additives in the base oil is as shown in Tables 1, 2, 3, and 4.

2. Test method (1) Wear test (lubricity test) In a HFC-134a refrigerant atmosphere, a steel ring and a steel block material were used as test materials by a Falex test (ASTM D2714), and the wear amount of the steel block surface after the test was performed. Was measured. The test conditions were: test temperature 100 ° C, test time 1
Time, ambient gas pressure is 600 kPa. In addition, the test result was shown by the relative value when this was set to 1.0 with reference to the abrasion loss of Comparative Example 18 (HCFC-22 as a refrigerant, and alkylbenzene as a base oil). In the case of a rotary compressor, the wear ratio 1.0 is a wear depth 15 at the vane tip.
It corresponds to about μm. If the wear ratio is large, the sealing performance of the high and low pressure parts of the compressor will be poor, and the cooling efficiency will decrease.
It also causes sludge to be generated due to abrasion powder in the vane portion. Incidentally, a change in the wear ratio of 0.1 corresponds to a wear depth of the vane portion of about 1.5 μm.

(2) Thermal and Chemical Stability Test In a HFC-134a refrigerant atmosphere, a thermal and chemical stability test was conducted by a shield tube test method. Shielded tube test method is as follows.
c, Fe, Cu, Al wire sealed and heated, 175 ° C
This is a method in which the test oil is held for 14 days to check for discoloration or sludge formation of the test oil. Note that Comparative Example 18
Performed under a -22 refrigerant atmosphere. The discoloration of the test oil was evaluated by observing the degree of discoloration of the test oil after completion of the test, and was evaluated as ○ when no discoloration was observed, Δ when slightly discolored, and X when significantly discolored.

3. Test results The test results are shown in Tables 1, 2, 3 and 4. In addition, the test result of Comparative Example 18 is a measure of whether or not the rotary compressor can be used.

[0080]

[Table 1]

[0081]

[Table 2]

[0082]

[Table 3]

[0083]

[Table 4]

(1) Examples 1 to 20 In each of the examples, the anti-wear property is better than that of Comparative Example 18 (composition of the prior art using HCFC-22 refrigerant, wherein the base oil is alkylbenzene). It also has good thermal and chemical stability and does not produce sludge, which is a problem with cyclic ketals or cyclic acetals. For this reason, the embodiment can be sufficiently used for not only reciprocating type or scroll type compressors but also rotary compressors having the most severe lubrication conditions.
In particular, Examples 1-4, 9-12, 17, and 18 (the mixing ratio of the phosphate ester is 0.5% by mass or more and 5.0% by mass or more)
Less than) has a wear ratio of 0.6 to 0.7, and is optimal for a small, high-output rotary compressor used under extremely harsh lubrication conditions.

(2) Comparative Example 1 In Comparative Example 1, only the cyclic ketal was used, and no additive was added. However, the anti-wear property and the thermal and chemical stability were inferior to any of the examples, and sludge was formed. I do. The aforementioned WO 96
In the case where the cyclic ketal or the cyclic acetal disclosed in US Pat. No./06839 is used for a refrigerator using an HFC-based refrigerant, in particular, a refrigerator oil for a rotary compressor, the wear resistance and the thermal and chemical stability are improved. Appropriate additives must be selected to suppress sludge formation due to ketals or cyclic acetals.

(3) Comparative Examples 2 and 3 Comparative Example 2 (the additive was 3.0% by mass of a phosphoric ester, 0.5% by mass of an epoxy compound, and no arylphosphorothionate was added). The agent is 0.4% by mass of aryl phosphorothionate, 0.5% by mass of epoxy compound
And no phosphoric acid ester added) had poorer antiwear properties than any of Examples and Comparative Example 18. From this, in order to sufficiently cope with a rotary compressor under severe lubrication conditions, as shown in the examples, three types of additives, such as a phosphoric ester, an alkylphosphorothionate or an arylphosphorothionate, and an epoxy compound, were used. It is understood that the composition in which is blended is the best.

(4) Comparative Example 4 Comparative Example 4 (0.4% by mass of phosphoric acid ester) is inferior to Example 1 (0.5% by mass of phosphoric acid ester) in antiwear properties.

(5) Comparative Example 5 Comparative Example 5 (16.0% by mass of phosphoric acid ester) was more wear-resistant and thermally and chemically stable than Example 8 (15.0% by mass of phosphoric acid ester). Poor properties and sludge is formed.

From the above, it can be seen that the compounding ratio of the phosphate ester is in the range of 0.5 to 15.0% by mass.

(6) Comparative Example 6 Comparative Example 6 (0.05% by mass of aryl phosphorothionate) is inferior to Example 9 (0.1% by mass of aryl phosphorothionate) in antiwear properties. .

(7) Comparative Example 7 Comparative Example 7 (6.0% by weight of arylphosphorothionate) was more resistant to abrasion and heat than Example 10 (5.0% by weight of arylphosphorothionate). -Poor chemical stability and sludge formation.

From the above, it is understood that the compounding ratio of the arylphosphorothionate is in the range of 0.1 to 5.0% by mass.

(8) Comparative Example 8 Comparative Example 8 (0.04% by mass of epoxy compound) was more heat and heat than Example 11 (0.05% by mass of epoxy compound).
Poor chemical stability and sludge formation.

(9) Comparative Example 9 In Comparative Example 9 (4.0% by mass of epoxy compound), sludge is formed. On the other hand, in Example 12 (3.0% by mass of the epoxy compound), no sludge was generated.

From the above, it can be seen that the compounding ratio of the epoxy compound is in the range of 0.05 to 3.0% by mass.

(10) Comparative Examples 10 to 17 In Comparative Examples 10 to 15, two kinds of the phosphoric acid ester, the arylphosphorothionate and the epoxy compound were used in the respective proportions of the respective constituents of the present invention. This is a test result when the value is out of the upper limit or the lower limit. Comparative Example 16,
17 shows the test results when all of the phosphoric acid ester, the arylphosphorothionate and the epoxy compound deviated from the upper limit or lower limit of the respective mixing ratios as constituent elements of the present invention. Even when Comparative Examples 10 to 17 are compared with each of the examples, in order to correspond to a rotary compressor, the mixing ratio of each additive to the cyclic ketal or the cyclic acetal base oil is within the range specified in the present invention. It turns out to be optimal.

It should be noted that, instead of the triphenylphosphorothionates (arylphosphorothionates) of Examples 1, 2, 4, 5, and 7 to 20, triphenylphosphorothionate and trioctylphosphorothionate ( Alkyl phosphorothioate) in the same composition as in Examples 1, 2, 4, 5, and 7 to 20 except that a mixture of 1: 1 was used. As a result of the test, the same effects as in Examples 1, 2, 4, 5, and 7 to 20 were obtained.

[0098]

The present invention is a refrigerating machine oil composition for a compressor using an HFC-based refrigerant which is currently being developed worldwide as a substitute for the HCFC-based refrigerant. In the present invention, a specific cyclic ketal or cyclic acetal which is an ether compound is used as a base oil. In order to suppress the lack of lubricity of the cyclic ketal or the cyclic acetal and the generation of sludge due to the cyclic ketal or the cyclic acetal, a phosphoric acid ester as an additive compatible with the cyclic ketal or the cyclic acetal is selected from among a large number of additives. , Alkylphosphorothionate or arylphosphorothionate and an epoxy compound, and further, the optimum blending ratio is determined.

When the phosphoric acid ester is used in combination with the alkyl phosphorothionate and / or the aryl phosphorothionate, the lubricating properties are extremely improved due to the synergistic effect. In particular, when the mixing ratio of the phosphoric acid ester is 0.5% by mass or more and less than 5.0% by mass, the effect of further improving the abrasion resistance is exhibited.

The present invention makes use of the advantages of the above-described cyclic ketal or cyclic acetal, such as electrical insulation, compatibility with HFC-based refrigerants, and low moisture absorption, while utilizing phosphate esters, alkylphosphorothionates, and / or the like. Alternatively, the incorporation of the arylphosphorothionate and the epoxy compound in the optimal ratios respectively solved the lack of lubricity of the cyclic ketal or cyclic acetal used as the base oil and the generation of sludge.

The present invention exhibits excellent wear resistance, thermal and chemical stability, and suppresses the generation of sludge. Therefore, the present invention can sufficiently cope with a high-output rotary compressor having the most severe lubrication conditions.

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C10M 137: 10) C10N 30:04 30:06 30:08 40:30

Claims (3)

[Claims] 1. A method according to claim 1, wherein one or more polyhydric alcohols having an even number of valences of 4 or more and 10 or less are combined with a carbonyl compound represented by the following general formula (1) or a ketal or acetal which is a reactive derivative thereof. A cyclic ketal or a cyclic acetal obtained from at least one of the above is used as a base oil, and a. 0.5 to 15.0% by mass of a phosphate ester, b. 0.1 to 5.0% by weight of alkylphosphorothionate and / or arylphosphorothionate, and c. A refrigerating machine oil composition for a compressor using a hydrofluorocarbon as a refrigerant and containing an epoxy compound in an amount of 0.05 to 3.0% by mass. Embedded image (Wherein, R ¹ is a hydrogen atom or a straight chain having 1 to 18 carbon atoms,
It represents a branched alkyl group or a cyclic saturated hydrocarbon. R ² represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cyclic saturated hydrocarbon. Alternatively, R
¹ and R ² represent an alkylene group having 2 to 36 carbon atoms which forms a saturated hydrocarbon ring together with the carbon atom to which they are bonded. ) 2. The base oil comprises one or more polyhydric alcohols having an even valence of 4 to 8 and a carbonyl compound represented by the following general formula (2) or a reactive derivative thereof. The refrigerating machine oil composition according to claim 1, comprising a cyclic ketal or a cyclic acetal obtained from at least one kind of a ketal or an acetal. Embedded image (Wherein, R ³ is a hydrogen atom or a straight chain having 1 to 12 carbon atoms;
It represents a branched alkyl group or a cyclic saturated hydrocarbon. R ⁴ is a linear or branched alkyl group having 1 to 12 carbon atoms,
Alternatively, it represents a cyclic saturated hydrocarbon. Alternatively, R ³ and R ⁴ represent an alkylene group having 2 to 13 carbon atoms which forms a saturated hydrocarbon ring together with the carbon atom to which they are bonded. The total carbon number of R ³ and R ⁴ is 1 to 13. ) 3. The refrigerating machine oil composition according to claim 1, wherein the base oil contains a cyclic ketal or a cyclic acetal represented by the following general formula (3) or (4). Embedded image (In the above formulas, R ⁵ represents a hydrogen atom, in which case R ⁶
Represents a branched alkyl group having 3 carbon atoms or a linear or branched alkyl group having 4 to 21 carbon atoms. Alternatively, R ⁵
Represents a linear or branched alkyl group having 1 to 21 carbon atoms, in which case R ⁶ represents a linear or branched alkyl group having 2 to 21 carbon atoms. )