JPH0670237B2 - Refrigerator oil - Google Patents

Description

TECHNICAL FIELD The present invention relates to refrigerating machine oil, more specifically, it does not decompose CFCs in the presence of CFCs (hereinafter referred to as CFC stability).
The present invention relates to a refrigerating machine oil that does not corrode metals such as iron, copper and aluminum and has excellent stability itself.

[Conventional technology]

In recent years, CFCs have been used in a wide range of fields such as the freezing and refrigerating industries, cooling accompanying the advancement of various industrial equipment, and effective use of waste energy. Specific examples thereof include refrigerators, air conditioners, cooling of insulating oil such as transformers and rectifiers, and freon turbines. In the equipment using these freons, there are problems such as corrosion of the metal part of the equipment and deterioration of the oil due to hydrogen chloride generated by the reaction between oil and freon or thermal decomposition of freon.

Conventionally, synthetic oils such as naphthene-based mineral oils, alkylbenzene-based oils, and polyether-based oils have been used as refrigerating machine oils, but they cannot be said to have sufficient freon stability. Therefore, it has been attempted to add glycidyl ethers such as phenyl glycidyl ether, epoxidized fatty acid esters, and epoxidized vegetable oils as hydrogen chloride scavengers (Japanese Patent Publication No. 57-42119 and Japanese Patent Publication No. 60-19352). , JP-A-57-177097
No. 59-102990, 59-117590 and 60-130696). Attempts have also been made to add acrylic acid glycidyl ester and the like (JP-A-59-911).
No. 98). However, it is not preferable to use some of these epoxy compounds because they have a strong skin irritancy.

In recent years, as the efficiency of refrigerating machines has increased, thermal stability of refrigerating machine oil has come to be emphasized, and polyhydric alcohol esters have come to be used as refrigerating machine oil. Ester-based oils have a great advantage in lubricity and stability at high temperatures as compared with naphthene-based mineral oils and alkylbenzene-based oils. However, ester-based oils are used at higher temperatures than naphthene-based mineral oils and alkylbenzene-based oils, so even ester-based oils that are superior in stability at high temperatures do not have sufficient CFC stability and corrode the metal parts of equipment. It has become difficult to control. In order to solve this point, it has been attempted to use an additive (Japanese Patent Laid-Open No. 55-55).
-155093 and JP-A-58-15592), the solubility of the additive in the ester-based oil is insufficient, and the thermal stability of the additive is inferior to the ester-based oil. Is not producing a satisfactory effect. That is, it is difficult to sufficiently suppress the corrosion of the metal part even if an epoxy compound which has been conventionally used as an additive is added to the ester oil.

[Problems to be solved by the invention]

The properties required for refrigerating machine oils used in refrigerating machines which must be operated for a long time under severe conditions include not only lubricity but also stability at high temperatures and freon stability.

The object of the present invention is to provide a refrigerating machine oil capable of stabilizing CFCs even under severe conditions and suppressing the corrosion of the metal part of the apparatus by using a novel additive excellent in compatibility with the base oil. , What is offered.

[Means for solving problems]

The present inventors have conducted extensive studies on additives for improving freon stability of ester-based frozen oils and suppressing metal corrosion of equipment, and as a result, have found that glycidyl esters of fatty acids are effective and have completed the present invention. Ivy.

That is, the present invention relates to a polyhydric alcohol ester or a mixture of a polyhydric alcohol ester and a mineral oil or a synthetic oil, and a straight chain or side chain saturated fatty acid having 8 to 18 carbon atoms or glycidyl straight chain unsaturated fatty acid having 14 to 18 carbon atoms. 0.
It is a refrigerating machine oil that is characterized by adding 05 to 10% by weight.

Examples of the polyhydric alcohol ester in the present invention include esters of polyhydric alcohol and monocarboxylic acid (Japanese Patent Laid-Open No. 56-1
33421), an ester composed of a polyhydric alcohol and a dicarboxylic acid or a monocarboxylic acid (JP-A-59-164393).
and so on. The polyhydric alcohol in these esters is preferably neopentyl polyol such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol.

The mineral oil or synthetic oil that can be used together with the polyhydric alcohol ester is a naphthene-based or paraffin-based mineral oil or a polyether-based, alkylbenzene-based, or polyolefin-based synthetic oil generally used as a lubricating oil.

The fatty acid constituting the fatty acid glycidyl ester used in the present invention is a linear or side chain saturated fatty acid having 8 to 18 carbon atoms or a linear unsaturated fatty acid having 14 to 18 carbon atoms. Glycidyl esters of fatty acids having a smaller number of carbon atoms are not preferable because they have insufficient solubility in ester base oils and may have skin irritation in some cases. A glycidyl ester of a fatty acid having a carbon number larger than the above is not preferred because it may cause clouding at low temperature when dissolved in an ester base oil. Specific examples of these fatty acids include caprylic acid, 2-ethylhexane, nonanoic acid, isononanoic acid, 2,2-dimethylnonanoic acid, capric acid, 3-methyldecanoic acid, lauric acid, myristic acid, isostearic acid, tetradecene. Acid, palmitooleic acid, oleic acid, linoleic acid and the like can be mentioned.

The addition amount of the fatty acid glycidyl ester in the present invention is 0.05 to 10% by weight, preferably 0.2
~ 4% by weight. If it is less than 0.05% by weight, the desired effect cannot be obtained, and if it is more than 10% by weight, it may become cloudy at low temperature, which is not preferable.

The fatty acid glycidyl ester of the present invention can be used together with other additives such as antioxidants and antiwear agents.

The refrigerating machine oil of the present invention can be widely used for all refrigerating machines utilizing CFCs.

[Action]

In the present invention, the reason why the fatty acid glycidyl ester stabilizes the system in the presence of freon is considered to be that the epoxy group in the molecule traps hydrogen chloride produced by the decomposition of freon. The reason why the fatty acid glycidyl ester of the present invention is particularly effective for polyhydric alcohol esters is not clear, but one reason is that these compounds have similar chemical structures and excellent compatibility. it is conceivable that.

〔The invention's effect〕

The refrigerating machine oil comprising the polyhydric alcohol ester oil of the present invention and the fatty acid glycidyl ester is a refrigerating machine oil having not only excellent lubricity and thermal stability but also improved freon stability. Therefore, by using the refrigerating machine oil of the present invention, it is possible to operate the refrigerator under severe conditions for a long time without any problem.

〔Example〕

 The present invention will be described with reference to examples.

Table 1 shows ester oils, mineral oils, and alkylbenzenes used in Examples and Comparative Examples.

The fatty acid glycidyl ester and other epoxy compounds used in Examples and Comparative Examples are shown in Table 2.

Refrigerating machine oils were prepared by adding the additives of Table 2 to the base oils of Table 1 or mixtures thereof, and the obtained refrigerating machine oils were evaluated by the shield tube test.

Sealed tube test: Put 0.6 ml of refrigerating machine oil, copper rod (2 x 50 mm), steel rod (2 x 50 mm) and aluminum foil (2 x 30 mm) into a glass tube (inner diameter 6 mm, wall thickness 2 mm), then- Put Freon-22 (chlorodifluoromethane) in a cooling bath at 60 ° C, seal the tube, and
After conducting a heating test at 0 ° C. for 5 days, changes in the hue of the sample, the amount of hydrogen chloride present, the presence or absence of the copper plating phenomenon, the corrosion state of the copper rod and the corrosion state of the steel rod were measured.

Moreover, the property of each refrigerating machine oil at −20 ° C. was observed.

The compositions tested and the results obtained are summarized in Table 3. The symbols used in each test in Table 3 are as follows.

The change in hue represents the difference between the hue [1 (light color, best) to 10 (dark color, worst) in 10 steps] before and after the heating test,
The smaller the number, the better.

The smaller the amount of hydrogen chloride present, the better.

○: Less than 25 ppm △: 25 to 100 ppm ×: Exceeds 100 ppm The copper plating phenomenon is the degree of plating of the steel bar, and the one that is not recognized is good.

⊚: Not observed ◯: Very slight Δ: Mild ×: Large Corrosion of copper and steel is better as it is smaller.

◯: Almost not observed Δ: Mild corrosion ×: Severe corrosion The properties of the refrigerating machine oil at −20 ° C. are good for a transparent liquid.

○: Transparent liquid ×: Cloudy liquid As is clear from the results shown in Table 3, the refrigerating machine oils of the present invention were all different from the comparative ones in color change, amount of hydrogen chloride, copper plating phenomenon, copper corrosion, steel corrosion and It can be seen that it has excellent properties in all properties at low temperatures and has extremely good Freon stability.

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Claims (1)

[Claims] 1. A linear or side chain saturated fatty acid having 8 to 18 carbon atoms or 14 to 12 carbon atoms in a polyhydric alcohol ester or a mixture of a polyhydric alcohol ester and mineral oil or synthetic oil.
Glycidyl ester of 18 straight chain unsaturated fatty acids 0.05 to 10
Refrigerating machine oil characterized by being added by weight%.