JPH05117681A - Refrigerator oil - Google Patents

Abstract

PURPOSE:To obtain a refrigerator oil excellent in stability against oxidation and heat by adding a specified amount of a specified polymer as a viscosity index improver to a naphthenic mineral oil, a paraffinic mineral oil, an alkylbenzene synthetic oil or the like. CONSTITUTION:The title oil is prepared by adding 3-12wt.%, based on the base oil, ethylene/alpha-olefin copolymer of an average molecular weight of 2600-3400, represented by the formula (wherein x=a+b; R is alkyl; and a and b are integers), as a viscosity index improver to a naphthenic mineral oil, a paraffinic mineral oil, an alkylbenzene synthetic oil or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to refrigerating machine oil used in refrigeration compressors.

[0002]

2. Description of the Related Art As a refrigerating compressor, a rotary type is becoming mainstream instead of a reciprocating type because of its small size, light weight and low noise. For this reason, oils having excellent VI (viscosity index) characteristics in addition to characteristics such as heat resistance and lubricity are desired as oils to be used, but conventionally naphthenic mineral oils, alkylbenzene synthetic oils, etc. which have been commonly used Is not a satisfactory state in terms of VI characteristics.

[0003]

The conventional refrigerating machine oil described above has the following problems to be solved.

That is, since the conventional refrigerating machine oil has a large change in viscosity with respect to temperature, there is a problem that it becomes highly viscous at low temperatures and causes an increase in load on the compressor. On the other hand, when the temperature is high, the viscosity is excessively lowered, and the gas sealability, lubricity, etc. of the sliding portion of the compressor become insufficient, and there is a problem in that the efficiency, reliability, etc. of the compressor are concerned.

In order to solve the above problems, the present invention provides a high VI.
It is an object of the present invention to provide a refrigerating machine oil having characteristics and excellent heat stability.

[0006]

The present invention is intended to provide a refrigerating machine oil described in (1) and (2) below as a means for solving the above problems. (1) An ethylene-α-olefin copolymer having an average molecular weight of 2600 to 3400 represented by the following chemical formula as a VI (viscosity index) improver in naphthenic mineral oil, paraffinic mineral oil, alkylbenzene synthetic oil, etc.
Refrigerating machine oil characterized by being added at a ratio of 12 wt%.

[0007]

[Chemical 2]

(2) Hydrochloric acid scavenger (epoxy compound), antioxidant (2,6 di-tert-butyl)
-Phenol), extreme pressure agent (tricresyl phosphate), antifoaming agent (silicon oil), etc. are added in a proportion of 0.1 to 10 wt% with respect to the base oil. Refrigerating machine oil according to (1) above.

[0009]

Since the present invention is constructed as described above, it has the following actions. (1) In the structure of (1) above, ethylene having an average molecular weight of 2600 to 3400 as a VI improver is added to a base oil such as naphthene-based mineral oil, paraffin-based mineral oil and alkylbenzene-based synthetic oil, which has excellent lubricity and heat resistance. Since the α-olefin copolymer is added in a proportion of 3 to 12 wt%, preferably 7 to 8 wt%, VI and thermal stability are improved.

That is, the ethylene-α-olefin copolymer having an average molecular weight of 2600 to 3400 is excellent in VI improving performance as compared with the conventionally known additives such as polybutene and polyacryl methacrylate. In addition, the present inventors have conducted experiments to find that they also have excellent properties in terms of oxidation / heat stability, shear stability, compatibility with mineral oil / synthetic oil, and the like. Then, by adding the additive to the above-mentioned base oil, as described later in Examples,
Stable lubricity with small change in viscosity due to temperature change,
The gas sealability can be exhibited. (2) In the configuration of (2) above, in addition to the configuration of (1) above, a hydrochloric acid scavenger, an antioxidant, an extreme pressure agent, an antifoaming agent, etc. are used as additives, so that the above (1) In addition to the above action, various properties such as anti-oxidation property, pressure resistance and the like are improved.

[0011]

EXAMPLE An example of the present invention will be described with reference to Tables 1 to 3.

[0012] Table 1 is a comparison table of the viscosity characteristics of the refrigerating machine oil of this example and the conventional refrigerating machine oil, and Table 2 is a comparison table of the hue change by the autoclave test, which was also carried out as a part of the oxidation / thermal stability improving effect test. Table 3 is also a comparison table of changes in total acid value. In each table, the example product indicates the refrigerating machine oil of the present example, and the conventional product indicates the conventional refrigerating machine oil.

In this example, a naphthenic mineral oil equivalent to ISOVG56 was selected as the base oil, and an ethylene-α-olefin copolymer having an average molecular weight of 2600 to 3400 was added as a VI improver at a ratio of 7 to 8 wt% with respect to the base oil. The effect of improving the VI and the oxidation / thermal stability of the refrigerating machine oil of this example in the case of being tested was examined in comparison with the conventional product. The results are shown in Table 1. As is clear from Table 1, the conventional product has VI ≈
At 0.8, there is a large change in viscosity with temperature, and it cannot be said that the state is satisfactory. On the other hand, the VI value of the product of this example is 14
A value of 1 is obtained, and a remarkable VI improving effect is recognized. Next, Tables 2 and 3 show the results of examining the effect of improving the oxidation and thermal stability.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

From Tables 2 and 3, it can be seen that the refrigerating machine oil of this example also has a remarkable improvement effect in terms of oxidation and thermal stability as compared with the conventional refrigerating machine oil.

That is, since the refrigerating machine oil of this embodiment has a small change in viscosity with respect to temperature, the increase in viscosity is small even at low temperatures, and the load resistance of the sliding portion of the compressor is small. On the other hand, in the high temperature range, the degree of decrease in viscosity is small, so the oil viscosity is sufficiently retained and the gas sealability and lubricity of the sliding parts of the compressor can be satisfied, contributing to improved efficiency and reliability of the compressor. To do.

As described above, according to this example, the naphthenic mineral oil as the base oil has an average molecular weight of 2600 as a VI improver.
~ 3400 ethylene-α-olefin copolymer is added to the base oil at a ratio of 7 to 8 wt% to obtain a refrigerating machine oil, so that a refrigerating machine oil having excellent VI value, oxidation and thermal stability is obtained. There is an advantage in that the refrigerator, more specifically, the gas sealability and lubricity of the sliding portion of the compressor are enhanced to contribute to the improvement of the efficiency and reliability of the refrigerator.

[0020]

Since the present invention is constructed as described above, it has the following effects.

That is, according to the present invention, a naphthene-based mineral oil, a paraffin-based mineral oil, an alkylbenzene-based synthetic oil and the like are used as bases, on which a VI improver having an average molecular weight of 2600 to
The 3400 ethylene-α olefin copolymer is added and mixed at a ratio of 3 to 12 wt% with respect to the base oil to form a refrigerating machine oil, so that the VI value and the oxidation and thermal stability are not adversely affected without adversely affecting other properties. A significantly higher refrigerating machine oil is obtained.

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Claims (2)

[Claims] 1. An average molecular weight of 2600 to 34 represented by the following chemical formula as a VI (viscosity index) improver in naphthenic mineral oil, paraffinic mineral oil, alkylbenzene synthetic oil and the like.
A refrigerating machine oil comprising the ethylene-α-olefin copolymer of 00 added to the base oil in a proportion of 3 to 12 wt%. [Chemical 1] 2. A hydrochloric acid scavenger (epoxy compound), an antioxidant (2,6 di-tert-Butyl-Phen)
ol), an extreme pressure agent (tricresyl phosphate), an antifoaming agent (silicon oil) and the like at a ratio of 0.1 to 10 wt% with respect to the base oil. Refrigerating machine oil according to item 1.