JPH0324197A - Refrigerator oil composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigerating machine oil assembly that is thermally and chemically stable and has extremely good lubricity.

(Prior technology) Refrigerating machine oil is introduced into refrigeration compressors such as air conditioners, car air conditioners, and freezers, and is used to lubricate and seal the sliding parts of the compressors.
Used for cooling. In recent years, there has been a trend toward higher performance, smaller size, and lighter weight compressors. Therefore, as the speed of rotating parts increases, refrigerating machine oils are increasingly required to have load resistance and wear resistance, as well as thermal stability due to high temperatures.

Various additives are used in general lubricating oils, but refrigeration oil is unique in that it is used in a refrigerant atmosphere. Therefore, refrigerating machine oil additives must not inhibit the stability of oil in such a refrigerant atmosphere and must have excellent low-temperature properties. Many of the additives used in general lubricating oils are
Additives that can be applied to refrigeration oil are limited because they have a negative effect on stability in a refrigerant atmosphere. Currently, only phosphate ester-based extreme pressure agents such as triphenyl phosphate and tricresyl phosphate are mainly used as mineral oil-based refrigerating machine oil additives. (Problem to be solved by the invention) However, such phosphoric acid ester-based extreme pressure agents improve the lubricity on sliding surfaces of iron-based materials, but are not necessarily effective on aluminum-based materials. .

Particularly in the case of car air conditioner compressors, aluminum-based materials are increasingly being used to reduce their weight, and there is a need for refrigeration oil that suppresses the wear of aluminum-based materials. Furthermore, in line with the recent movement to regulate fluorocarbons, in the case of car air conditioners, Freon R-134a (1.1,
1. 2-tetrafluoroethane), but this Freon R-134a has almost no compatibility with oil, and polyether, a fluorocarbon oil, is a useful candidate as a refrigerating machine oil for Freon R-134a. It is listed as. Compared to conventional mineral oil, this polyether has a thinner oil film even under the same pressure, and also has a thinner oil film than conventional mineral oil.
- Since 134a) does not contain chlorine, it cannot be expected that the refrigerant will be effective in suppressing wear. Therefore, the object of the present invention is to improve the resistance even in refrigeration compressors using aluminum as the sliding material by adding a wear resistance improver suitable for the refrigerating machine oil base material, which is mainly made of oil. The object of the present invention is to provide a refrigerating machine oil with good abrasion resistance and thermal stability.

(Means for Solving the Problems) As a result of intensive study on additives for improving the lubricity of synthetic refrigerating machine oil, the present inventors found that they have excellent low-temperature properties without impeding stability, and that A compound with extremely good wear resistance for ξ materials has been discovered, and the present invention has been completed.

That is, the present invention provides the following general formula (1
), XI (wherein, R is a hydrocarbon group having 5 to 17 carbon atoms, XI is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, x2 and X3 are a hydrogen atom or a hydroxyl group, and both groups are the same) or different groups, but the total number of carbon atoms in the formula is 8 to 20
This relates to a refrigerating machine oil compound containing the compound represented by The surface of aluminum, which has no oxide film due to friction, becomes considerably active and its wear resistance decreases.As a result of various studies, we found that the compound represented by general formula (1) can significantly improve wear resistance. I found it. The compound represented by the general formula (1) has high thermal stability and oxidation stability when added to a refrigerating machine oil base material,
It does not impede the low-temperature properties of the base material.

From this, the present invention is a refrigerating oil mixture containing a compound represented by the general formula (1) for improving the lubricity of the refrigerating machine oil base material against aluminum ξ-based materials.

The refrigerating machine oil base material according to the present invention has a pour point of -20°C or less, and has other low-temperature properties and thermal stability selected from a certain group of polyethers, alkylbenes, and esters that can be used as a refrigerating machine oil. The base material is a mixture of one type or two or more types of Hekai oil. Examples of polyethers include alkyl ethers of polyoxypropylene, alkyl ethers of polyoxyethylene propylene glycol, and terminal esters thereof, and examples of esters include monoesters, diesters, polyol esters, and complex esters. Can be mentioned. Examples of the alkylbenzene include hard alkylbenzenes having a branched alkyl group and soft alkylbenzenes having a linear alkyl group. Particularly when polyether, which has poor lubricity on sliding surfaces of aluminum-based materials, is used as a base material, the addition of the compound represented by general formula (1) is effective. This is due to the following reasons. That is, the Alξ-based material is not only soft, but also becomes chemically unstable when its oxide film is removed. Compounds that easily adsorb to unstable aluminum-based materials and form a dense adsorption film are effective in improving the lubricity of refrigerating machine oil.

Therefore, it is desirable that the additive does not participate much in redox, has a coordination-type molecular structure that is a relatively Lewis base, and has few substituents that cause steric hindrance near the functional group. In addition, polyethers have many ether bonds (-0-
) and several hydroxyl groups (-OH), the compound represented by general formula (1) has good solubility in these, does not separate from the base oil at low temperatures, and has low-temperature characteristics such as clouding point and There is almost no increase in the flock point, etc. For this purpose, it is easier to adsorb onto the sliding material when the molecular weight is not too large and there are fewer substituents that cause steric hindrance near the α-position of the alkyl group. Furthermore, the general formula (1
) was found to have the effect of further improving the low electrical insulation properties of polyether when it is used as a base material. Improving electrical insulation is extremely beneficial for refrigerators with built-in motors, such as refrigerator compressors.

In addition, 0.0% of the compound represented by the general formula (1) is added to the refrigerating machine oil.
It is preferable to add within the range of 1 to 20.0% by weight. If the amount of the compound added is too small, it will not be effective in suppressing the wear of iron or aluminum, as shown in the examples below, and if it is too large, the degree of effect will decrease relative to the ratio of the amount added, and furthermore, it will not be economical. It is also undesirable.

Since the sliding parts of compressors are often made of iron-aluminum materials, the refrigerating machine oil composition of the present invention may contain phosphate esters (for example, tricresyl phosphate, triphenyl phosphate, etc.) or chlorinated paraffin ( chlorine content of 20 to 80% by weight) can be added in an amount of 0.01 to 10.0% by weight. At this time, if the base material is synthetic oil, the stability of the refrigeration oil formulation system will not be affected.
It has been found that lubricity can be significantly improved.

The compound represented by the above general formula (1) can be used not only for oil but also for mineral oil; however, when used for mineral oil, it may have an adverse effect on the thermal stability of refrigeration oil depending on the conditions of use. There is. Therefore, in the present invention, it is preferable to use synthetic oils that do not cause such problems. Further, in the refrigerating machine oil composition of the present invention, additives commonly used in refrigerating machine oil such as antifoaming agents, antioxidants, and hydrochloric acid scavengers are not prohibited from being used in combination.

(Example) Next, the present invention will be specifically explained using examples.

Various performances of refrigerating machine oil to which a predetermined amount of the compound shown in general (1) above was added were evaluated. The following compounds were used.

2-Ethyl-1,3- Hexanediol (manufactured by Kyowa Yuka ■) (hereinafter referred to as alcohol 1) 2-Ethylhexanol (manufactured by Kyowa Yuka ■) (hereinafter referred to as alcohol 2) Lauryl alcohol (calcol 208: manufactured by Kao ■) (hereinafter referred to as alcohol 3) ) Decanol (Calcol IOH: manufactured by Kao ■)
The performance evaluation of the phosphoric acid ester (TCP: manufactured by Daihachi Chemical ■) and paraffin chloride [chlorine content 60%] (Shiobara 60: manufactured by Toyo Soda Kogyo ■) was conducted using the Phalenx test (ASTM D-267).
0), a thermal stability test using a shield tube, and a volume resistivity test (JI
This was done by examining the electrical insulation properties using SC2101). Furthermore, the two-phase separation temperature of the refrigerant and oil was also investigated, since if the refrigerant and oil undergo two-phase separation, the oil taken out from the refrigerant compressor will not return to the compressor, causing seizure.

The Farex test (ASTM D-2670) is a test in which a cylindrical rotating shaft with a diameter of approximately 6 mA is sandwiched between two V-blocks from the left and right sides, and a load is applied linearly to this.
This is a test in which the wear weight of the rotating shaft and V block is measured at a constant oil temperature, rotation speed, applied load, and test time while blowing refrigerant gas at 70II1/allin into the sample. In addition, the thermal stability test is a tempered glass tube called a shield tube with a length of 200 m, an inner diameter of 6IIll1, and a thickness of 21IIIL, in which steel, copper, and aluminum metal wires, as well as refrigerant Freon gas (low-temperature liquid) and sample oil are respectively applied. This is a test in which 1 g is sealed and heated in a constant temperature bath at 175°C, and the degree of coloration (ASTM color) of the contents is recorded at regular intervals to observe changes over time.

Two-phase separation temperature measurement involves sealing the refrigerant Freon gas and the sample oil in a glass tube at a weight ratio of 8:2, and slowly cooling this with an acetone solution of dry ice at a rate of 1°C/win. The temperature at which phase separation occurs was determined.

1-8 1-3 Falex abrasion test conducted on the oil types shown in Table 1 below using additive-free polyether (viscosity at 100°C: 11 cSt) as the refrigerating machine oil base material, heat resistance using a shield tube The results of the stability test, volume resistivity test, and two-phase separation temperature measurement are also listed in Table 1.

Note that Freon R-134a was used here as the refrigerant.

Furthermore, the block used in the Farex wear resistance test was made of aluminum-based material, and the rotating shaft was made of iron-based material.

From Table 1, by adding the compound shown in general formula (1),
It was found that the amount of wear on aluminum-based materials was reduced, and that it compensated for the weaknesses of additives such as phosphate esters and chlorinated paraffin. In addition, high thermal stability was maintained even with the addition of the compound represented by general formula (1), and there was no problem with the flocking point.

Therefore, even if the compound represented by general formula (1) is added to polyether-based refrigeration oil, the desired improvement in wear resistance can be achieved without impeding the excellent properties of polyethers. It was confirmed that

9~l6, 4~6 Additive-free alkylbenzene (100"
The results of the same evaluation tests as in Example 1 except for the volume resistivity test are shown in Table 2 below using C (viscosity: 5 cSt). The refrigerant fluorocarbon gas used here was R-22.

From Table 2, the compound shown in general formula (1) increases its lubricity, shows a synergistic effect with other additives, and can improve the wear resistance without reducing the properties of the refrigeration oil base material. It was confirmed.

〔Effect of the invention〕

From the above, it has become clear that the following effects are produced.

The compound shown in general (1) above has the effect of suppressing wear of highly active metals such as aluminum as a wear resistance improver. Moreover, it does not adversely affect the thermal stability or low-temperature properties of the refrigeration oil base material. Currently, due to regulations on fluorocarbons, there is a very high possibility that the alternative refrigerant for the fluorocarbon gas R-12, which is a refrigerant for refrigerators, will be fluorocarbon R-134a. In particular, the compound represented by formula (1) is indispensable as an additive to improve the lubricity of new refrigeration oils that are compatible with R-1348, and refrigeration oils containing this compound also meet various performance requirements. You can expect it to be fulfilled.

Claims (1)

[Claims] 1. For a base material mixed with one or more synthetic oils selected from the group consisting of polyethers, alkylbenzenes, and esters, the following general formula (1), , chemical formulas, tables, etc.▼(1) (In the formula, R is a hydrocarbon group having 5 to 17 carbon atoms, X^1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X^
2 and X^3 are a hydrogen atom or a hydroxyl group, and both groups are the same or different groups, but in the formula, the total number of carbon atoms is 8
A refrigerating machine oil composition containing a compound represented by: 2. 0.1 to 2 of the compound represented by the above general formula (1)
The refrigerating machine oil composition according to claim 1, containing 0.0% by weight. 3. The refrigerating machine oil composition according to claim 1 or 2, wherein 0.01 to 10.0% by weight of phosphoric acid ester and/or chlorinated paraffin (chlorine content 20 to 80% by weight) is added.