JP2000008065A - Lubricating oil composition for compressor using hfc-125 as cooling medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for compressors, capable of being used for the compressors using HFC-125 as a cooling medium, having excellent sealability in the high pressure.low pressure portions of the cooling medium-compressors, and having an excellent oil-returning property in the real machines. SOLUTION: This lubricating oil composition for compressors comprises (A) 1-60 pts.wt. of a branched alkyl benzene and (B) 99-40 pts.wt. of a mineral oil, wherein the total amount of the mixture of the branched alkyl benzene A with the mineral oil B is 100 pts.wt. The mineral oil of the component B is preferably a mineral oil having a viscosity of <=50,000 mm2/s at -20 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil composition for a compressor, and more particularly to a lubricating oil composition useful for a compressor using a hydrofluorocarbon having a specific composition as a refrigerant.

[0002]

2. Description of the Related Art Due to the recent problem of protection of the ozone layer, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon), which have been conventionally used as refrigerants for refrigeration equipment, have been subject to regulation. ) Is being used as a refrigerant. As refrigerating machine oils for HFC-based refrigerants, PAG (polyalkylene glycol) and esters are used or studied as compatible types, and alkylbenzene and the like are used as so-called incompatible types in which the refrigerant and oil do not mix. For example, US Pat.
55,316, JP-A-1-198694, 1
JP-A-256594, JP-A-2599093, JP-A-2599094, JP-A-259909,
JP-A-1-274191, JP-A-2-43290,
JP-A-2-55791, JP-A-2-84491 and the like.
5602, JP-A-3-55791, and 3-
Nos. 88892, 2-128991, 2-
JP-A-128912, JP-A-3-200895, and JP-A-3-200895
JP-A-227397, JP-A-4-20597, and JP-A-4-20597
-72390, 4-218592 and 4
No. 218593. However, PAG has a disadvantage that it has high hygroscopicity and poor electrical characteristics. On the other hand, ester oil may hydrolyze due to its structure to generate an acid, and various inconveniences are expected in the refrigerator system due to the generated acid.
Further, since these oils are inferior in lubricating properties as compared with conventional mineral oil and CFC / HCFC or mineral oil, alkylbenzene and CFC / HCFC, blending of various additives has been studied.

In consideration of compatibility with refrigerants, the above-mentioned polyalkylene glycols and esters are used. On the other hand, a slightly compatible type which uses alkylbenzene and is incompatible with refrigerants in a wide range is also studied. Have been.
Japanese Patent Application Laid-Open No. Hei 8-27 describes such an HFC-based finely compatible type.
478, 8-27479, 8-489
No. 86, 8-48990 and the like. However, since the finely compatible type is hardly compatible with the refrigerant over a wide range, the viscosity is lower than the conventionally used viscosity in terms of oil return in the refrigeration system. 60% by weight or more, preferably 80% by weight or more, and most preferably 100% by weight, of which molecular weight distribution is narrow, and 0.005 to 5.0% by weight of a phosphate compound is added to this. No. If this condition is not satisfied, the refrigerating compressor may seize during a long-term operation, and is not preferable because of lack of reliability. However, there is a concern that the phosphoric acid ester may decompose at a high temperature in a sliding portion or the like and cause problems such as sludge.

[0004] Apart from the seizure of the compressor, the HFC requires a high output because the cooling capacity is low unlike the conventional CFC and HCFC. In particular, in a small-sized and high-pressure type compressor, a decrease in the sealing performance of a high-pressure portion and a low-pressure portion of a sliding portion of the compressor has become a new problem. This decrease in the sealing performance is a serious problem because it causes a decrease in the cooling efficiency of the refrigerator. In particular, when various types of compressors are considered, in the scroll type, the fixed side and the movable side (rotary side) made of aluminum alloy seal the high-pressure portion and the low-pressure portion with lubricating oil. When the sealing property is reduced, that is, when the oil film becomes thinner, the compression efficiency of the refrigerant is reduced, and the fixed side and the rotating side are partially in contact with each other, resulting in metal contact. Further, in the rotary type compressor, the tip of the vane and the rotating rotor are also in contact with each other via the oil film. If the sealing performance is reduced, gas escape occurs and the compression efficiency is reduced. This reduction in sealing performance causes cooling efficiency regardless of the scroll type or rotary type compressor, and also causes seizure.

The inventors of the present invention have conducted intensive studies on the improvement of the sealing property of the high-pressure / low-pressure section, and have found that a specific amount of alkylbenzene and mineral oil are mixed to improve the sealing property when using a refrigerant containing HFC-125. It has been found that the oil return property can be greatly improved, and the present invention has been completed.

[0006]

An object of the present invention is to provide an HF
It can be used for compressors that use C-125 as a refrigerant, and has excellent sealing properties at high and low pressure parts of the refrigerant compressor,
Another object of the present invention is to provide a lubricating oil composition for a compressor that has excellent oil return properties in an actual machine.

[0007]

The above objects of the present invention are as follows. When the mixture of A) alkylbenzene having a branched chain and B) mineral oil is 100 parts by weight, A) the alkylbenzene having a branched chain is not less than 1 part by weight and less than 60 parts by weight;
B) a lubricating oil composition for a compressor using HFC-125 as a refrigerant, wherein the lubricating oil composition comprises less than 99 parts by weight and at least 40 parts by weight of mineral oil;

[0008] 2. The lubricating oil composition for a compressor using HFC-125 as a refrigerant according to claim 1, wherein the mineral oil of component B) is a mineral oil having a viscosity at -20 ° C of 50,000 mm ² / s or less. Is achieved by each of

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the contents of the present invention will be described in detail. The branched-chain alkylbenzene of the component A) of the present invention is preferably a branched-chain alkylbenzene in view of its thermal and chemical stability, and a branched-chain alkyl group produced from a propylene polymer as a raw material of the branched chain. Is good. In particular, it is preferable that the polymer of propylene has a tetramer as a main component.
In addition, the number of alkyl groups contained in the benzene of the above-mentioned alkylbenzene is 1 to 3, and it is particularly preferable that the benzene contains a large amount of alkylbenzene (dialben) having two alkyl groups. More preferably, among the dialbenes, propylene tetramer and dialbenes having an alkyl group having less than 12 carbon atoms are the main components. When one alkylbenzene (monoalben) out of the alkylbenzenes increases, the volatility decreases and the thermal stability decreases.
When the amount of three alkylbenzenes (trialbenes) increases, the viscosity increases and the thermal stability decreases.
However, these alkylbenzenes can be used as a mixture, and particularly when the target viscosity is adjusted, it is preferable to mix various components.

The method for producing alkylbenzene, which is the component A of the refrigerating machine oil composition of the present invention, is optional, and is not limited at all, but can be generally produced by the following synthesis method. As the aromatic compound as a raw material, specifically, benzene, toluene, xylene, ethylbenzene,
Methyl ethyl benzene, diethyl benzene, and mixtures thereof can be used. Specific examples of the alkylating agent include lower monoolefins such as ethylene, propylene, butene, and isobutylene, preferably branched olefins having 6 to 40 carbon atoms obtained by polymerization of propylene, waxes, heavy oil, and petroleum oil. Fraction, polyethylene,
Carbon number 6 obtained by thermal decomposition of polypropylene etc.
40 branched olefins can be used alone or in combination. Among them, especially carbon number 6-21
Are more preferred. Known catalysts such as Friedel-Crafts type catalysts such as aluminum chloride and zinc chloride, and acidic catalysts such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid and activated clay are used as the alkylation catalyst. The alkylbenzene of the refrigerating machine oil composition of the present invention is produced by the above-mentioned production method, and is separated and used mainly for dialbenes separated by purification after production.

The mineral oil which is the component B of the present invention is, for example, a lubricating oil fraction obtained by distilling a crude oil under normal pressure and reduced pressure to remove solvent, extract solvent, hydrocrack, remove solvent. Wax, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc.
Naphthenic oils and the like can be used. The viscosity of the mineral oil as the B component is such that the viscosity at −20 ° C. is 50,000 mm ² / s or less,
It is preferably at most 10,000 mm ² / s, more preferably at most 5000 mm ² / s. When the viscosity at -20 ° C increases, the oil return property deteriorates.

In the present invention, the mixing ratio of the alkylbenzene (A) is 1 part by weight or more and less than 60 parts by weight based on 100 parts by weight of the mixture of the alkylbenzene and the mineral oil, and preferably 5 parts by weight or more of the alkylbenzene. Less than 60 parts by weight, more preferably 20 parts by weight or more and less than 60 parts by weight of alkylbenzene, and most preferably 30 parts by weight or more and less than 60 parts by weight of alkylbenzene. If this condition is not satisfied, oil taken out of the compressor during long-term operation does not return to the compressor, and so-called seizure may occur.

The refrigerating machine oil composition of the present invention contains an antioxidant, an extreme pressure agent, an antifoaming agent, and the like which are usually used as additives of the refrigerating machine oil within a range satisfying the performance of the refrigerating machine oil aimed at by the present invention. Others can be used together. Examples of antioxidants include hindered phenols, amines, and sulfur, and examples thereof include 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis (2,6-diphenyl). -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 and the like can be used. As extreme pressure agents, phosphate ester compounds, for example,
Trimethyl phosphate, Triethyl phosphate, Tributyl phosphate, Trioctyl phosphate, Tributoxyethyl phosphate, Triphenyl phosphate, Tricresyl phosphate, Trixylenyl phosphate, Cresyl diphenyl phosphate, Diphenyl orthoxenyl phosphate, Octyl diphenyl phosphate, Phenyl Isopropyl phenyl phosphate, diphenyl isopropyl phenyl phosphate, tris (isopropyl phenyl) phosphate, tris (chloroethyl) phosphate, tris dichloropropyl phosphate and the like can be used. Among them, tricresyl phosphate and tris (isopropylphenyl) phosphate are particularly preferable, and these may be used alone or in combination. As the sulfur-based compound, an inert type is better because the influence on the thermal stability is smaller. Therefore, for example, alkyl and aryl phosphorothionates can be mentioned. Among them, trioctyl phosphorothionate and triphenyl phosphorothionate are preferred. These sulfur compounds may be used alone or in combination. As the metal deactivator, for example, alizanin, chilizanine, benzotriazole, oil-soluble benzotriazole, mercaptobenzotriazole and the like can be used. As the defoaming agent, for example, dimethylpolysiloxane, metal carboxylate and the like can be used.

The refrigerant used in the refrigerator using the refrigerating machine oil of the present invention is a fluorinated alkane having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, such as pentafluoroethane (HFC-1).
25) is at least 30% by weight, preferably at least 35% by weight,
More preferably, the content is 40% by weight or more. HFC
The HFC-based refrigerant that can be mixed with −125 is not particularly limited, but specifically, for example, trifluoromethane (HFC-23), difluoromethane (HFC-3)
2), 1,1,2,2-tetrafluoroethane (HFC
-134), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), HFC such as 1,1-difluoroethane (HFC-152a) No.

In the present invention, H containing HFC-125 is used.
More specifically, HFC-125 is used as the FC refrigerant.
HFC-125 / HFC-125 / HFC-32 = 30-60% by weight / 70-40% by weight; HFC-125 / H
FC-143a = 40 to 60% by weight / 60 to 40% by weight
HFC-125 / HFC-134a / HFC
-143a = 35 to 55% by weight / 1 to 15% by weight / 40
~ 60% by weight of a mixture.

[0016]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The following evaluation tests were performed by combining the base oils shown in Table 1. As additives, di-tert-butyl-paracresol was used as an antioxidant, and tricresyl phosphate was used as an antiwear agent.

[Evaluation Test 1: Sealing Test] The sealing performance was evaluated by using a refrigerant pressurized oil film formation evaluation tester shown in FIG. This tester simulates the condition of the compressor under the refrigerant pressure, that is, the inside of the compressor of the refrigerator, and fills the container with the refrigerant and pressurizes it to affect the sealing performance under the high pressure state where the refrigerant is dissolved in the refrigerator oil It is possible to evaluate the ability to form an oil film. The sample oil is provided at the lower part of the rotating ball, and when the upper disk rotates, the steel ball also rotates and the lubricating oil in which the refrigerant is dissolved is supplied to the contact part. The test conditions were a sliding speed of 0.2 m / s, a load of 20 N, and a Hertzian pressure of the contact portion of 0.516 GPa. HFC-125 is used as the refrigerant, and the pressure is 1MPa.
And Although the evaluation of the sealing property was shown as a ratio with the combination of HFC-125 / alkylbenzene being 1, it was 2.0 or more, and preferably 2.4 or more, more preferably 2.6 or more.

In FIG. 1, 1 is a small CCD camera, 2
Denotes a steel ball, 3 denotes a load, 4 denotes a glass disk, 5 denotes a refrigerant charging port, and 6 denotes a pressure vessel.

[Evaluation Test 2: Oil Return Test] Using an experimental apparatus shown in FIG. 2, a copper pipe having a pipe length of 2 m and an inner diameter of 0.005 m was bent as shown in FIG. Is filled with 5 g of oil, the temperature of the thermostat is set to −20 ° C., HFC-125 is flowed at a flow rate of 0.001 m ³ per minute, and the amount of oil accumulated in the oil receiver is measured after 60 minutes. The oil return property was evaluated by comparison with the current product. Table 2 shows the results.
It is shown in Table 6. The oil return property was evaluated based on the return rate, and a return rate of 35% or more within a predetermined time was judged to be acceptable.
0% or more, more preferably 45% or more. This 35
%, Oil return is poor and seizure is caused.

In FIG. 2, 11 is a refrigerant tank, 12 is a copper pipe, 13 is a flow meter, 14 and 16 are pressure gauges, 15 is a thermostat, and 17 is a bearing.

[Evaluation test 3: Actual machine test] Cooling capacity 1 kW
Test oil 400 ml and HFC-125 / HFC-32 = 50% by weight / 50 using a small household room air conditioner
1000% by weight of a mixed refrigerant at a temperature of 38% by weight.
Place in a constant temperature room maintained at ℃, set the temperature of the air conditioner to 20 ℃
, Continuous operation for 1000 hours was performed, and the operability was evaluated. The results are shown in Tables 7 and 8.

[Examples: Element tests] In Examples 1-4, the mixing ratio of mineral oil A to alkylbenzene was changed.
Even if the ratio of the mineral oil is changed, the sealing property and the oil return rate increase.

Example 5 is obtained by adding an antioxidant to Example 3, Example 6 is obtained by adding an antiwear agent to Example 3, and Example 7 is obtained by adding both an antioxidant and an antiwear agent to Example 3. However, even if the additive is added, the sealing property and the oil return rate do not change.

In Examples 8 and 9, mineral oil B was added to alkylbenzene.
Are mixed at different ratios, but mineral oil B also has good sealability and oil return rate.

Examples 10 and 11 are examples in which mineral oil C is mixed with alkylbenzene at different ratios, and even mineral oil C has good sealing properties and oil return rate.

Examples 12 to 14 are examples in which mineral oil B and mineral oil C were mixed with alkylbenzene and an antioxidant and an antiwear agent were added. Even when the additives were added, the sealability and the oil return rate were good. is there.

[Comparative Example: Elemental Test] Comparative Examples 1 to 8 are examples in which 100% of mineral oil or an antioxidant and an antiwear agent were added thereto, but each component of mineral oils A, B, C and D alone However, the sealability is good, but the oil return rate is poor.

Comparative Examples 9 and 10 are examples in which an antioxidant and an anti-wear agent were added to alkylbenzene alone and alkylbenzene, but the alkylbenzene alone has a good oil return rate but has poor sealing properties.

Comparative Examples 11 to 16 are examples in which the amount of alkylbenzene is greater than the claimed range and specific mineral oils A, B and C are added thereto. Even when mineral oil and additives such as antioxidants and antiwear agents are added, the sealing properties are poor.

Comparative Examples 17 and 18 are examples in which a mineral oil D component is blended with alkylbenzene, but this combination has good sealing properties but a poor oil return rate.

[Evaluation of Actual Machine Performance] Tables 7 and 8 show examples of the actual machine performance evaluation. In Examples 1, 4, 7, 8, 11, and 14, the performance of the actual machine was good.

Comparative Example 1 is an example of a mineral oil alone, but the mineral oil alone is poor in oil return, causing seizure and inferior actual machine performance.

Comparative Example 7 is an example in which a mineral oil component outside the range of the present invention was used. It can be seen that seizure of the compressor occurred in a shorter time than in Comparative Example 1 due to poor fluidity.

In Comparative Example 10, the alkylbenzene alone was used, but this caused seizure which is considered to be due to an inferior oil film ratio.

In Comparative Example 12, a mineral oil consisting of an alkylbenzene and a specific component was blended, but it was out of the components described in the claims of the present invention, and seizure occurred.

In Comparative Examples 17 and 18, the compounding amount was within the range of the present invention, but the mineral oil component was out of the specific range, and seizure occurred.

In Comparative Example 19, the result of using R-22 was successfully completed in the actual machine test.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

[Table 4]

[0042]

[Table 5]

[0043]

[Table 6]

[0044]

[Table 7]

[0045]

[Table 8]

[0046]

According to the present invention, it can be used for a compressor using HFC-125 as a refrigerant, has excellent sealing properties at high and low pressure parts of the refrigerant compressor, and has good oil return properties in a real machine. An excellent lubricating oil composition for a compressor can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a test device used for a sealability test.

FIG. 2 is a schematic diagram of a test device used for an oil return test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small CCD camera 2 Steel ball 3 Load 4 Glass disk 5 Refrigerant charging port 6 Pressure vessel 11 Refrigerant tank 12 Copper piping 13 Flowmeter 14 Pressure gauge 15 Constant temperature chamber 16 Pressure gauge 17 Oil receiving

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C10N 40:30

Claims (2)

[Claims] When the mixture of A) a branched chain alkylbenzene and B) mineral oil is 100 parts by weight, A) the branched chain alkylbenzene is at least 1 part by weight and less than 60 parts by weight, and B) the mineral oil is 99 parts by weight. A lubricating oil composition for a compressor using HFC-125 as a refrigerant, wherein the lubricating oil composition contains less than 40 parts by weight or less by weight. 2. The mineral oil of component B) has a viscosity at -20.degree.
The lubricating oil composition for a compressor using HFC-125 as a refrigerant according to claim 1, wherein the lubricating oil composition is a mineral oil of 0000 mm ² / s or less.