JP2930963B2 - Lubricating oil composition for CFC refrigerant - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a lubricating oil composition for a CFC refrigerant, and more specifically, a refrigerator or the like which uses a CFC-based lubricant as a refrigerant, particularly a hydrogen-containing CFC compound as a refrigerant. The present invention relates to a lubricating oil composition useful as a lubricating oil composition.

[Problems to be Solved by the Related Art and the Invention] Generally, the performance required for refrigerating machine oil is (1) good compatibility with refrigerant, and (2) good stability in contact with the refrigerant. And (3) good lubricity (seizure resistance and wear resistance).

Currently, refrigerating machine oils include trichloromonofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-11).
Freon compounds containing no hydrogen, such as 12), are mainly used as refrigerants. However, when released into the atmosphere, most of these fluorocarbon compounds reach the stratosphere without being decomposed, and their use is being regulated internationally because they destroy the ozone layer. For this reason, it is conceivable to use a hydrogen-containing CFC compound that is relatively easily decomposed in the future as a refrigerant. In this case, the two-layer separation temperature between the refrigerant and the lubricating oil, particularly a mineral oil-based lubricating oil, is high. The problem arises that the layers are easily separated. Alkylbenzene which has been conventionally used as a refrigerating machine oil also has problems that lubricity, especially seizure resistance, is insufficient, and that oil consumption due to evaporation is large.

To solve such a problem, Japanese Patent Application Laid-Open No. 60-123577
Various proposals have been made in Japanese Unexamined Patent Application Publications No. 58-103594 and No. 58-103594. However, these have a problem that, depending on the refrigerant used, lubricity (particularly wear resistance), compatibility with the refrigerant, or thermal stability are insufficient.

The present inventors have intensively studied to solve the above problems and to develop a lubricating oil suitable as a lubricant for a system using a hydrogen-containing chlorofluorocarbon compound as a refrigerant.

[Means for solving the problem]

As a result, they have found that a mixture of a high viscosity alkylbenzene having a kinematic viscosity at 40 ° C. of 50 cSt or more and a specific mineral oil polyglycol can solve the above-mentioned problem. The present invention has been completed based on such findings.

That is, the present invention provides (A) a kinematic viscosity at 40 ° C of 50 to
2 to 20% by weight of a high-viscosity alkylbenzene having 300 cSt and a total carbon number of alkyl groups of 20 or more, (B) a kinematic viscosity at 40 ° C of 5 to 600 cSt, a pour point of -15 ° C or less, and a nitrogen content of 2 to 15% by weight of a mineral oil of 100 ppm or less and (C)
An object of the present invention is to provide a lubricating oil composition for chlorofluorocarbon refrigerant, which is blended in a proportion of 96 to 65% by weight of polyglycol.

Here, the alkylbenzene, which is the component (A) of the composition of the present invention, has a higher viscosity than the alkylbenzene conventionally used in refrigerator oils and the like, and usually has a kinematic viscosity at 40 ° C. of 50 cSt or more, preferably It is 60 to 300 cSt, more preferably 70 to 250 cSt. Here, if the kinematic viscosity is less than 50 cSt, the oil consumption by evaporation is large,
In addition, various inconveniences such as poor sealing properties are caused, and seizure resistance is insufficient, and lubricity is insufficient.

There are various types of such high-viscosity alkylbenzenes, and the total number of carbon atoms of the alkyl group (when there are a plurality of alkyl groups, the total number of carbon atoms of each alkyl group)
Alkylbenzenes having 20 or more (monoalkylbenzene, dialkylbenzene, trialkylbenzene, etc.), preferably those having a total carbon number of 20 or more and having two or more alkyl groups (dialkylbenzene, etc.) are suitably used. Incidentally, this high-viscosity alkylbenzene, even if the kinematic viscosity is within the above range, even one kind alone,
Alternatively, a mixture of two or more types may be used.

The mineral oil as the component (B) of the composition of the present invention has a temperature of 40 ° C.
Has a kinematic viscosity of 5 to 600 cSt, preferably 8 to 400 cSt. When the kinematic viscosity is less than 5 cSt, disadvantages such as a large loss of oil due to evaporation and a decrease in sealing performance occur. This mineral oil has a pour point of -15 ° C or less,
Preferably it is -20 ° C or lower, more preferably -30 ° C. If the pour point exceeds −15 ° C., the low-temperature performance is reduced, and the lubricant is unsatisfactory as a lubricant for a refrigerator or the like, which is an object of the present invention. In addition, this mineral oil has a nitrogen content
100 ppm or less, preferably 50 ppm or less, more preferably 3 ppm
It is 0 ppm or less. When the nitrogen content exceeds 100 ppm, there arises a problem that heat resistance is lowered and discoloration is easily caused. The mineral oil as the component (B) may be any one having a kinematic viscosity, a pour point and a nitrogen content within the above-mentioned ranges. In addition, the sulfur content is 1% by weight or less, especially 0.7%.
% By weight or less is preferred.

There are various types of such mineral oils. Specifically, paraffin-based crude oil, intermediate-based crude oil or naphthenic-based crude oil is distilled under normal pressure, or the residual oil of normal pressure distillation is distilled under reduced pressure. The obtained distillate oil or refined oil obtained by refining the same according to a conventional method, such as solvent refined oil, hydrogenated refined oil, and dewaxed oil, can be used.

Furthermore, the kinematic viscosity of the polyglycol that is the component (C) of the composition of the present invention is not particularly limited, and is generally 40 ° C.
The kinematic viscosity at 10 to 1000 cSt is used.

In the lubricating oil composition of the present invention, the mixing ratio of the components (A), (B) and (C) is not particularly limited,
Preferably, (A) 2 to 20% by weight of a high viscosity alkylbenzene, (B) 2 to 15% by weight of a mineral oil and (C) polyglycol
96 to 65% by weight, more preferably (A) 3 to 15% by weight of a high viscosity alkylbenzene, and (B) 3 to 10% by weight of mineral oil.
% And (C) 94 to 75% by weight of polyglycol.

The lubricating oil composition of the present invention comprises the above-mentioned components (A), (B) and (C) as main components. If necessary, an antiwear agent, a chlorine scavenger, an antioxidant, a metal It is also effective to mix appropriate amounts of a deactivator, an antifoaming agent and the like.

The lubricating oil composition of the present invention can be used as a lubricant for refrigerators, coolers, heat pumps and the like using a hydrogen-containing Freon refrigerant as well as trichloromonofluoromethane (Freon-11) and dichlorodifluoromethane (Freon-12). Although effective, the refrigerant containing hydrogen as a refrigerant is 1,1-dichloro-2,2,2-trifluoroethane (Freon-123); 1,1,1,2-tetrafluoroethane (Freon). -134a); 1-chloro-1,1-difluoroethane (CFC-142b); 1,1-difluoroethane (CFC-152a); trifluoromethane (CFC-23) or monochlorodifluoromethane (CFC-22); It is particularly effective for these refrigerants.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 8 and Comparative Examples 1 to 9 Lubricating oils or lubricating oil compositions were prepared using the mineral oils, alkylbenzenes and polyglycols shown in Table 1 and used as sample oils to evaluate the performance according to the following method. Was done. The results are shown in Table 1.

Two-layer separation temperature The sample oil and Freon refrigerant were mixed at a ratio of 2: 8 (weight), and the temperature at which the two layers were separated was measured. ×: 10 ° C or higher, ○: 10 to 0
° C and ◎ indicate 0 ° C or less.

Shield tube test A 2: 1 (weight) mixture of sample oil and chlorofluorocarbon refrigerant was
Enclosed in a glass tube with copper and aluminum catalysts,
After heating at 175 ° C. for 720 hours, its appearance and the presence or absence of precipitates were measured.

Abrasion Resistance Test In accordance with ASTMD 2670, evaluation was carried out under the conditions of a blow rate of 10 / hour using a refrigerant of Freon-22 for 1 hour under a load of 150 pounds.

Seizure resistance test Evaluated by seizure load (lb) according to ASTM D 3233.

* 1 Alkylbenzene (total carbon number of the alkyl group is 19 or less): alkylbenzene (total carbon number of the alkyl group is 20 or more) = 30: 70 (weight ratio) (kinematic viscosity at 40 ° C. 56 cSt) * 2 Alkylbenzene (total carbon number of the alkyl group) (Number 19 or less): alkylbenzene (total carbon number of alkyl group 20 or more) = 10: 90 (weight ratio) (kinematic viscosity at 40 ° C. 90 cSt) * 3 alkylbenzene (total number of carbon atoms of alkyl group 19 or less): alkylbenzene (alkyl group) = 20: 10 (weight ratio) (Kinematic viscosity at 40 ℃ 14cSt) * 4 Naphthenic mineral oil Kinematic viscosity at 40 ℃ 9cSt, Nitrogen content 10p
pm, sulfur content 0.5 wt%, pour point -35 ° C * 5 Naphthenic mineral oil 40 ° C kinematic viscosity 32 cSt, nitrogen content 10
ppm, sulfur content 0.35% by weight, pour point -30 ℃ * 6 Naphthenic mineral oil 40 ℃ kinematic viscosity 94cSt, nitrogen content 15
0 ppm, sulfur content 2.5% by weight, pour point -15 ° C * 7 Polyoxypropylene glycol monobutyl ether, kinematic viscosity 32 cSt at molecular weight 700, 40 ° C * 8 Polyoxypropylene glycol monobutyl ether, kinematic viscosity 56 cSt at molecular weight 1000, 40 ° C [ Effect of the Invention As described above, the lubricating oil composition of the present invention includes not only ordinary Freon compounds but also Freon-123, Freon-134a, Freon-142b, Freon-152a, Freon-23, Freon-22, etc. The bilayer separation temperature is lower than the hydrogen-containing Freon compound,
It also has high seizure resistance, low oil consumption due to evaporation, and good stability.

Therefore, the lubricating oil composition of the present invention provides a refrigerator, a cooler,
It is effectively used as a lubricant for heat pumps and the like.

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Claims (1)

(57) [Claims] (A) A kinematic viscosity at 40 ° C. of 50 to 300 cSt.
2 to 20% by weight of a high-viscosity alkylbenzene having an alkyl group having a total carbon number of 20 or more, (B) a kinematic viscosity at 40 ° C of 5 to 600 cSt, a pour point of -15 ° C or less, and a nitrogen content of 100 ppm A lubricating oil composition for CFC refrigerants, which is blended at a ratio of 2 to 15% by weight of mineral oil and (C) 96 to 65% by weight of polyglycol as follows.