JP2553262B2 - Refrigerator oil - Google Patents

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 must be equipped with an oil recovery facility, and if its function is not sufficient, the oil will be taken out into the refrigeration cycle, causing a shortage of oil in the compressor. As a result, poor lubrication occurs in the sliding portion, causing seizure and the like, which significantly shortens the life of the device. On the other hand, low temperature oil in the evaporator leaves high-viscosity oil, which lowers the efficiency of heat exchange. 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 not be used in the future, and the regulated subject is chlorodifluoromethane (R-22)
It is also in motion. 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 The inventors of the present invention have conducted extensive studies to develop a refrigerating machine oil having excellent compatibility with ammonia, lubricity and stability in an ammonia atmosphere, and as a result, have been found It has been found that a compound containing an ether compound as a main component can achieve the above object, and has completed the present invention.

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

Embedded image (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. Further, m _{1 to} m ₁₀ and n _{1 to} n ₁₀ are integers having an average molecular weight of more than 300 and not more than 1800, and n _{1 to} n ₁₀ are 0 or integers not exceeding the corresponding m _{1 to} m _10. The present 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, a compound represented by the following formula: RO (AO) _x H (AO represents an oxyalkylene group) is widely used as the polyether compound, 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 give a solid acid amide compound. Therefore, the above (I) according to the present invention
R and R _{1 to} R ₁₀ in the formulas (V) to (V) must not be hydrogen atoms. In addition, the sum of the carbon numbers excluding the carbon atoms of the oxypropylene group and the oxyethylene group in one molecule of the polyether compound of the above 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 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 average molecular weight is adjusted by the degree of polymerization of oxyethylene and oxypropylene in the formula.

In the present invention, oxybutylene or more,
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 to increase the oxyethylene content more than 5: 5 (molar ratio), low temperature characteristics such as pour point deteriorate and finally solidify at room temperature, which is not preferable. .

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 formulas (I) to (V).

The refrigerating machine oil of the present invention includes various additives conventionally used in refrigerating machine lubricating oils, such as load-bearing additives such as tricresyl phosphate, antioxidants such as amine and phenol, and benzo. Metal deactivators such as triazole, antifoaming agents such as silicones, oily agents such as carboxylic acids,
A rust preventive such as alkenyl succinic acid can be added in a necessary amount as 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 these examples, average molecular weight, kinematic viscosity, compatibility with ammonia, Falex baking load,
The results of total acid value 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 Branched chain refrigeration 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 performed from room temperature at a rate of 1 ° C. per minute, and the temperature at which two-layer separation occurred 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 filled with 3 m of 1.6 mmφ iron wire as a catalyst, and add N
Pressurized with H ₃ to 0.6 kg / cm ² G, and with N ₂ 5.7 kg / cm
Pressurized to cm ² G. After that, heat to 150 ° C,
It was kept at the same temperature for 7 days. After that, NH ₃ was removed from the sample oil under reduced pressure, and then the total acid value and 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 applying a wide range of refrigerators for ammonia, the function can be sufficiently exerted.

Claims (1)

(57) [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, which comprises, as a main component, one or more polyether compounds selected from the polyether compounds represented by