JPH059483A - Refrigerator oil - Google Patents

Abstract

PURPOSE:To provide a refrigerator oil which is used in a refrigerator using ammonia as the refrigerant and is excellent in the compatibility with ammonia as well as in lubricity and the stability in an ammoniac atmosphere by using a specific polyether compd. as the main component. CONSTITUTION:At least one polyether compd. selected from the group consisting of compds. of formulas I to V (wherein R and R1 to R10 are each independently 1-8C alkyl; the number of carbon atoms per molecule excluding those in oxypropylene and oxyethylene groups is 10 or lower; and each of m1 to m10 and n1 to n10 is such an integer that the average mol.wt. of each compd. is 300-1800 provided that each of n1 to n10 is 0 or an integer not higher than the corresponding m1 to m10, which may be a random copolymer or a block copolymer, is used as the main component of a refrigerator oil. If necessary, a load- bearing additive, an antioxidant, a metal deactivator, an antifoaming agent, an oiliness improver, an anticorrosive agent, etc., are added to the oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine oil for ammonia refrigerant, which contains a polyether compound as a main component, which has good compatibility with ammonia and excellent lubricity.

[Prior Art]

Conventionally, ammonia has been mainly used as a refrigerant in industrial refrigerators, and mineral oils have been used as such refrigerator oils. However, since ammonia is incompatible with mineral oil-based oils, the compressor requires an oil recovery facility, and if its function is not sufficient, the oil is taken out into the refrigeration cycle, causing a shortage of oil in the compressor. As a result, poor lubrication occurs in the sliding part, causing seizure and the like, which significantly shortens the life of the device. On the other hand, because of the low temperature in the evaporator, highly viscous oil is left behind and the efficiency of heat exchange decreases. For this reason, refrigerators that use ammonia are relatively large,
It was limited to industrial refrigerators that can be regularly maintained.

On the other hand, recently, in order to protect the ozone layer, dichlorodifluoromethane (R-1) which is a CFC containing chlorine.
2) etc. are regulated and will be prohibited in the future, and the regulated subject is chlorodifluoromethane (R-22)
There is a movement to spread to other places. As development of alternatives to these CFC refrigerants progresses, ammonia is being reviewed as an alternative refrigerant.

[Problems to be Solved by the Invention]

As described above, when ammonia is used as a refrigerant, the biggest problem is compatibility with oil. If this point is solved, ammonia becomes a closed refrigeration cycle with almost no maintenance like a CFC refrigerant. Can also be used. Therefore, an object of the present invention is to provide a refrigerating machine oil having good compatibility with ammonia, excellent lubricity, and stability in an ammonia atmosphere in order to meet such a demand.

[0005]

Means for Solving the Problems As a result of intensive investigations by the present inventors to develop a refrigerating machine oil excellent in compatibility with ammonia, lubricity, and stability in an ammonia atmosphere, a poly- The inventors have found that those containing an ether compound as a main component can achieve the above object, and have completed the present invention.

That is, the present invention has the following general formula:

[Chemical 2] (In the above general formulas (I) to (V), R and R _{1 to} R
₁₀ represents an alkyl group having 1 to 8 carbon atoms, which may be the same or different. The sum of carbon numbers excluding the carbon atoms of the oxypropylene group and the oxyethylene group in one molecule is 10 or less. In addition, m _{1 to} m ₁₀ and n _{1 to} n ₁₀ are integers having an average molecular weight of more than 300 and 1800 or less, and n _{1 to} n ₁₀ are 0 or integers not exceeding the corresponding m _{1 to} m _10. The invention relates to a refrigerating machine oil for an ammonia refrigerant, which comprises, as a main component, one or two or more polyether compounds selected from the polyether compounds represented by

The above (I) to be used in the present invention
R and R _{1 to} R ₁₀ of the polyether compound of the formula (V) are
As described above, it represents an alkyl group having 1 to 8 carbon atoms, which may be the same or different. However, generally, as the polyether compound, a compound represented by the following formula: RO (AO) _x H (AO represents an oxyalkylene group) is widely used, and such a compound having a hydroxyl group at the terminal is deteriorated. It becomes an acid in the process of.
This acid reacts with ammonia to eventually form a solid acid amide compound. Therefore, the above (I) according to the present invention
In formula (V), R and R _{1 to} R ₁₀ must not be hydrogen atoms. In addition, the sum of the numbers of carbon atoms excluding the carbon atoms of the oxypropylene group and the oxyethylene group in one molecule of the polyether compound of the formulas (I) to (V) is 10 or less. From the point of compatibility with ammonia, the smaller the carbon number, the better,
As the alkyl group, an alkyl group having 1 to 4 carbon atoms is more preferable, and if the alkyl group has more than 8 carbon atoms, it will not be compatible with ammonia and cannot be used.

The above (I) to be used in the present invention
The reason why the average molecular weights of the compounds of the formula (V) are both limited to more than 300 and 1800 or less is as follows.
That is, when the average molecular weight is 300 or less, the kinematic viscosity at 100 ° C. is 2 cSt or less, which cannot maintain sufficient lubricity, while when the average molecular weight exceeds 1800, it becomes incompatible with ammonia. Out.

The adjustment of the average molecular weight is made by the degree of polymerization of oxyethylene and oxypropylene in the formula.

In the present invention, oxybutylene or higher,
That is, an oxyalkylene-containing polyether compound having 4 or more carbon atoms cannot be used because it becomes incompatible with ammonia. Further, the polyether compound containing only oxyethylene has a high pour point and cannot be used alone. On the other hand, a polyether compound containing only oxypropylene can be used, and preferably,
A polyether compound of a copolymer of oxyethylene and oxypropylene. Further, when the ratio of oxyethylene and oxypropylene changes in a direction in which the amount of oxyethylene becomes larger than 5: 5 (molar ratio), the low temperature characteristics such as pour point deteriorate and finally solidify at room temperature. ..

The compound of formulas (I) to (V) may be polymerized in the form of random copolymerization or block copolymerization. Further, such polyether compounds may be used alone or in combination of two or more kinds. Furthermore,
Two or more kinds may be appropriately selected and used from the compounds of the above formulas (I) to (V).

The refrigerating machine oil of the present invention includes various additives conventionally used in refrigerating machine lubricating oils, for example, load-bearing additives such as tricresyl phosphate, antioxidants such as aminophenol, and benzotriazole. Metal deactivators, such as
Defoaming agents such as silicones, oiliness agents such as carboxylic acids, rust preventives such as alkenyl succinic acid, and the like can be added in desired amounts, if desired.

[0013]

EXAMPLES Next, the present invention will be specifically described by way of examples. Examples 1-5, Comparative Examples 1-5 Structure or type of polyether compound which is the main component of the refrigerating machine oil used in this example, average molecular weight, kinematic viscosity, compatibility with ammonia, Falex baking load,
The results of total oxidation and color before and after the cylinder test are shown in Table 1 below.

[0014]

[Table 1]

In Table 1, the physical properties of the naphthene mineral oil type refrigerating machine oil of Comparative Example 1 and the branched chain alkylbenzene of Comparative Example 2 are as follows.
It is as follows. Naphthenic mineral oil type Branched chain Refrigerating machine oil Alkylbenzene Density 0.888 0.870 Kinematic viscosity (cSt at 100 °) 4.96 4.35 Flash point (° C) 180 178

The outline of various test methods in Table 1 is as follows. After 5 ml of a sample oil compatible with ammonia and 1 ml of ammonia were sealed in a glass tube, cooling was carried out from room temperature at a rate of 1 ° C./min, and the temperature at which two layers were separated was measured. In order to evaluate the lubricity of Falex seizure load oil, ASTM D-3233
The Falex seizure load was measured according to -73. Cylinder test The following test was conducted to evaluate the stability of oil in an ammonia atmosphere. First, put 50 g of sample oil into a 300 ml cylinder charged with 3 m of 1.6 mmφ iron wire as a catalyst, and add N
Pressurized to 0.6 kg / cm ² G with H ₃ and 5.7 kg / with N _2.
Pressurized to cm ² G. Then, heat to 150 ° C,
It was kept at the same temperature for 7 days. Then, after removing NH ₃ from the sample oil under reduced pressure, the total acid value and the hue of the sample oil were measured, and the appearance was visually observed.

[0017]

As described above, since the refrigerating machine oil of the present invention contains a specific polyether compound as a main component, the refrigerating machine oil has excellent compatibility with ammonia and good lubricity and stability. However, when a wide range of refrigerators for ammonia are applied, their functions can be fully exerted.

Claims (1)

Claims: 1. The following general formula: (In the above general formulas (I) to (V), R and R _{1 to} R
₁₀ represents an alkyl group having 1 to 8 carbon atoms, which may be the same or different. The sum of carbon numbers excluding the carbon atoms of the oxypropylene group and the oxyethylene group in one molecule is 10 or less. In addition, m _{1 to} m ₁₀ and n _{1 to} n ₁₀ are integers having an average molecular weight of more than 300 and 1800 or less, and n _{1 to} n ₁₀ are 0 or integers not exceeding the corresponding m _{1 to} m _10. A refrigerating machine oil for an ammonia refrigerant containing, as a main component, one or two or more polyether compounds selected from the polyether compounds represented by