JP2785185B2 - Refrigeration oil composition for car air conditioners - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigerating machine oil composition for a car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant.

[0002]

2. Description of the Related Art Various types of refrigerators have been used in the past. Among them, so-called vapor compression refrigerators that use a refrigerant are classified into a reciprocating type, a centrifugal type, and a rotary type due to the structure of the compressor. Classified. Among them, a refrigerator with a rotary (rotary) compressor has such features that it has a large refrigerating capacity even in a small size, can exhibit excellent performance even in a high rotation range, and can operate smoothly and quietly. Therefore, it is widely used in home refrigerators, air conditioners, car air conditioners (automobile air conditioners), and the like.

[0003] The refrigerating machine oil used for these is 4
Naphthenic mineral oils, paraffinic mineral oils, alkylbenzenes, polyglycol-based oils, kinematic viscosities at 0 ° C. of 5 to 200 cSt, and mixtures of these or various base oils with additives are generally used.

[0004] On the other hand, typical refrigerants for compression refrigerators include trichloromonofluoromethane (CFC 11), dichlorodifluoromethane (CFC 12), monochlorodifluoromethane (CFC 22) and trichlorotrifluoroethane (CFC 113). Halogen-based refrigerants, hydrocarbon-based refrigerants typified by propane, and inorganic gas-based refrigerants typified by ammonia, carbon dioxide and the like are widely used.

Among them, halogen-based refrigerants are widely used in refrigerators for home refrigerators, air conditioners or car air conditioners because they are chemically stable, have low toxicity, are nonflammable, and have ideal thermodynamic characteristics. Have been.

However, among these, perhalogenocarbons, that is, chlorofluorocarbons in which all the hydrogens of hydrocarbons are replaced by halogens, are hardly decomposable and have high stability. It does not decompose, reaches the ozone layer 25 to 30 km above the ground, encounters strong ultraviolet rays from the sun, is decomposed and emits chlorine atoms, reacts with ozone, and reduces the ozone concentration in the ozone layer. This ozone layer absorbs harmful ultraviolet rays from the sun and protects creatures on the surface, and international treaties on the production and consumption of chlorofluorocarbon are under way to prevent the destruction of the ozone layer by chlorofluorocarbons. .

[0007] Under these circumstances, the United States Environmental Protection Agency (EPA) has proposed 1,1-dichloro-2,2,2.
-Trifluoroethane (CFC-123), 1-chloro-1,2,2,2-tetrafluoroethane (CFC-1
24), 1,2-dichloro-2,2-difluoroethane (CFC-132b), 1-chloro-2,2,2-trifluoroethane (CFC-133a), 1,1,1,2
-Tetrafluoroethane (FC-134a) and 1,
1-dichloro-1-fluoroethane (CFC-141
b) are proposed as alternative refrigerants.

[0008] Of these compounds, 1,1,1,2-
Tetrafluoroethane has similar thermodynamic properties to dichlorodifluoromethane (Freon 12), which has been conventionally used in refrigerators such as home refrigerators, air conditioners and car air conditioners, so that it is used as a refrigerant. ,
If 1,2-tetrafluoroethane (FC-134a) is used, it should be possible to obtain the same performance as before without largely changing the design of those refrigerator systems.

However, for this purpose, the refrigerating machine oil filled in the compressor enters the condenser and the evaporator together with the discharge gas, so that it is sufficiently dissolved in the recirculating refrigerant and circulated in the cycle to be cooled. It is indispensable that the oil return property is good.

That is, it is not uncommon for the temperature to reach -20 to -30 ° C. from the expansion valve or the capillary tube, which is the coldest part in the refrigeration cycle, to the evaporator. Those which do not cause two-layer separation with the refrigerant at low temperatures are preferred.

Since it is not unusual for a compressor, a receiver, and a condenser to reach a high temperature, it is preferable that the refrigerating machine oil not cause two-layer separation from the refrigerant in the high temperature region in addition to the low temperature region. .

Conventionally, as a refrigerating machine oil, a naphthenic mineral oil, a paraffinic mineral oil, an alkylbenzene, a mixture thereof, or a mixture of these various base oils with additives has been generally used. These conventional refrigerating machine oils are described, for example, in Japanese Patent Publication No. 40-11940, Japanese Patent Publication No. 49-4107, Japanese Patent Publication No. 49-13483, Japanese Patent Publication No. 49-13829, and Japanese Patent Publication No. 49-19.
No. 084, JP-B-52-39509, JP-B-52-43722, JP-B-53-17602, JP-A-46-4532, JP-A-48-606.
JP-A-49-47498, JP-A-51-47498
22971, JP-A-52-28503, JP-A-52-54707, JP-A-53-88007
No., etc. However, these conventional refrigerating machine oils are dichlorodifluoromethane (CFC 1).
Since there is almost no compatibility with 1,1,1,2-tetrafluoroethane (FC-134a) which is an alternative refrigerant of 2), when used in combination with 1,1,1,2-tetrafluoroethane, Two-layer separation occurs at normal temperature, and the most important oil return property in the refrigeration system is deteriorated, resulting in reduced refrigeration efficiency or poor lubricity, causing various practical problems such as seizure of the compressor I do not endure. Polyglycols are also known as refrigerating machine oils having a high viscosity index, for example, JP-B-57-42119,
JP-B-61-52880, JP-A-57-5179
No. 5 publication. However, the polyglycol oils specifically disclosed in these prior arts still have insufficient compatibility with 1,1,1,2-tetrafluoroethane, and therefore have the same problems as described above, and cannot be used practically.

[0013]

SUMMARY OF THE INVENTION The present inventors have set forth 1,1,
As a result of repeated studies to develop a refrigerating machine oil composition for a compression type car air conditioner using 1,2-tetrafluoroethane as a refrigerant, when polyglycol oil having a limited structure and properties is used as a base oil, The present inventors have found that a refrigerating machine oil composition having excellent performance that cannot be obtained with other base oils can be obtained, and have completed the present invention.

The present invention is suitable for use in a compression type car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant, and does not separate from the refrigerant at low and high temperatures, and further has lubricity, sealability and stability. It is an object of the present invention to provide a refrigerating machine oil composition for a car air conditioner having good properties.

[0015]

According to the present invention, there is provided a compound of the general formula

Embedded image [Wherein, R ₁ represents an alkyl group having 1 to 18 carbon atoms;
Represents an integer of 5 to 70, R ₂ represents an alkylene group having 2 to 4 carbon atoms, and a ratio of (the number of —OR ₂ — groups in which R ₂ is an ethylene group) / a in one molecule ( Hereinafter referred to as α)
Is 0 to 0.8], the pour point is -10 ° C or less, and the kinematic viscosity at 100 ° C is 5 to (30 + 100).
α) cSt and number average molecular weight is 300 or more and 2000
A polyoxyalkylene glycol monoether having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 1.00 to 1.20 is used as a base oil. The present invention provides a refrigerator oil composition for a car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant.

Hereinafter, the contents of the present invention will be described in more detail. The base oil of the refrigerating machine oil composition of the present invention has the general formula (I):

Embedded image Is a polyoxyalkylene glycol monoether. In the formula, R ₁ represents a linear or branched alkyl group having 1 to 18 carbon atoms, and a represents an integer of 5 to 70, respectively. R ₂ represents an alkylene group having 2 to 4 carbon atoms. Specific examples of R ₁ include, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl Group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like,
Among them, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group,
Octadecyl groups are more preferred.

As R ₂ , specifically, for example,

Embedded image And the like. Among them, an ethylene group, a propylene group, a butylene group, and a tetramethylene group are more preferable.

Further, in the polyoxyalkylene glycol monoether of the present invention, an alkylene group having a different number of carbon atoms may be present in one molecule, that is, an oxyalkylene group having a different number of carbon atoms is randomly or block copolymerized. However, the ratio (α) of (the number of —OR ₂ — groups in which R ₂ is an ethylene group) / a in one molecule needs to be 0 to 0.8. If the value of α exceeds 0.8, the refrigerating machine oil becomes solid at room temperature or its pour point becomes undesirably high.

The polyoxyalkylene glycol monoether of the present invention has a pour point of -10 ° C or lower, preferably -20 to -50 ° C, and a kinematic viscosity at 100 ° C of 5 to (30 + 100α) cSt, preferably It must be in the range of 8 to (30 + 100α) cSt. If the pour point exceeds −10 ° C., the refrigerating machine oil may be solidified in the refrigerating system at a low temperature, which is not preferable. When the kinematic viscosity at 100 ° C. is less than 5 cSt, the compressor cannot maintain the hermeticity. On the other hand, when the kinematic viscosity exceeds (30 + 100α) cSt, the refrigerant 1,1,1,2-tetrafluoroethylene is used. The solubility in ethane is deteriorated, and the two layers are separated at a low temperature, which is not preferable.

The polyoxyalkylene glycol monoether in the present invention has a number average molecular weight of 300 or more from the viewpoint of further improving the sealing performance of the compressor and increasing the temperature of the two-layer separation from the refrigerant at high temperatures. , Less than 2000, preferably 500 or more and 1500 or less.

Further, the polyoxyalkylene glycol monoether in the present invention includes a ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
Is required to be 1.00 to 1.20 from the viewpoint of further increasing the two-layer separation temperature with the refrigerant under a high temperature.

In order to further enhance the performance of the refrigerator oil composition for a car air conditioner of the present invention, if necessary, a conventionally known refrigerator oil additive such as phenol such as di-tert-butyl-p-cresol. System, phenyl-
α-naphthylamine, N, N′-di (2-naphthyl)-
amine-based antioxidants such as p-phenylenediamine,
Load-bearing additives such as zinc dithiophosphate, chlorinated paraffin, fatty acids, sulfur, etc., silicone-based defoamers, metal deactivators such as benzotriazole, glycidyl methacrylate, phosphite-based hydrogen chloride scavengers And the like can be used alone or in combination of several kinds.

The refrigerating machine oil composition for a car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant of the present invention is particularly preferably used for a car air conditioner having a rotary (rotary) compressor. However, it can be preferably used for other car air conditioners having a reciprocating or centrifugal compressor.

[0024]

The contents of the present invention will be described more specifically with reference to examples and comparative examples. Examples 1 to 9 and Comparative Examples 1 to 13 Tables 1 and 2 show properties of the base oil of the refrigerating machine oil used in Examples and Comparative Examples.

Refrigerated base oil according to the present invention (Examples 1 to 9)
In order to measure the low-temperature separability between water and the refrigerant, Examples 1 to 9 were added to 1,1,1,2-tetrafluoroethane as the refrigerant.
Of base oil is mixed with 10, 20, 30, 40, 50 and 70 parts by weight, and the mixed solution is gradually cooled from room temperature to a temperature at which the mixed solution becomes cloudy or separates into two layers. That is, the two-layer separation temperature on the low temperature side was determined. In the case where cloudiness or two-layer separation had already occurred at room temperature, the temperature was gradually increased to obtain a temperature at which the cloudiness or two-layer separation was eliminated, and this was taken as the low-temperature side two-layer separation temperature. The results are shown in Tables 3 and 4.

The frozen base oil according to the present invention (Examples 1 to 3)
9) In order to measure the high-temperature separability between the refrigerant and the refrigerant, a mixture was prepared by mixing 3, 10 and 30 parts by weight of the base oils of Examples 1 to 9 with the same refrigerant as described above, and the obtained mixture was The temperature was gradually increased from room temperature, and the temperature at which the mixture became turbid or separated into two layers, that is, the two-layer separation temperature on the high temperature side was also determined. In the case where cloudiness or two-layer separation had already occurred at room temperature, the temperature was gradually reduced to obtain a temperature at which no cloudiness or two-layer separation occurred, and this was taken as the high-temperature side two-layer separation temperature. The results are shown in Tables 3 and 4. For comparison, the low-temperature two-layer separation temperature of the base oils of Comparative Examples 1 to 13 which were outside the scope of the present invention was determined in the same manner as in Examples 1 to 9. The results are also shown in Tables 3 and 4.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

As is clear from the results of the two-layer separation temperatures in Tables 3 and 4, the refrigerating base oils of Examples 1 to 9 according to the present invention were composed of 1,1,1,2-tetrafluoroethane and 2
It shows very good compatibility even at a low temperature of about 0 to -30 ° C. Also, it shows very good compatibility with the above refrigerant not only at a low temperature but also at a high temperature of about 60 to 80 ° C. On the other hand, even in the case of the mineral oils, alkylbenzenes and polyglycol oils of Comparative Examples 9 to 11, Comparative Example 12 was used.
In the case of a diether such as described above, and even a monoether as in Comparative Example 13 having a viscosity other than the range of the present invention, the refrigerant and the refrigerant are subjected to two-layer separation at a low temperature, particularly in Comparative Examples 9 to 12, even at room temperature. It will wake up and cannot be put to practical use. In addition, even in the concentrations of Comparative Examples 1 to 8 in which the average molecular weight or Mw / Mn is out of the range of the present invention,
The two-layer temperature on the high temperature side is inferior to Examples 1 to 9.

[0032]

As described above, the composition of the present invention is suitable for use in a car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant. It is a refrigerating machine oil composition for a car air conditioner which has good lubricity, sealability and stability without being separated.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI C10N 40:30 (58) Investigated field (Int.Cl. ⁶ , DB name) C10M 107/34 C10M 105/18 C10N 20:00 C10N 20:02 C10N 20:04 C10N 40:30

Claims (1)

(57) [Claims] 1. A compound of the general formula [Wherein, R ₁ represents an alkyl group having 1 to 18 carbon atoms;
Represents an integer of 5 to 70, R ₂ represents an alkylene group having 2 to 4 carbon atoms, and a ratio of (the number of —OR ₂ — groups in which R ₂ is an ethylene group) / a in one molecule ( Hereinafter referred to as α)
Is 0 to 0.8], the pour point is -10 ° C or less, and the kinematic viscosity at 100 ° C is 5 to (30 + 100).
α) cSt and number average molecular weight is 300 or more and 2000
A polyoxyalkylene glycol monoether having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 1.00 to 1.20 is used as a base oil. A refrigerating machine oil composition for a car air conditioner using 1,1,1,2-tetrafluoroethane as a refrigerant.