Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With lubricants – or warning – stabilizing or anti-corrosion...
Reexamination Certificate
1999-08-20
2001-05-15
Einsmann, Margaret (Department: 1751)
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
With lubricants, or warning, stabilizing or anti-corrosion...
C252S067000
Reexamination Certificate
active
06231782
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerating machine oil composition, particularly relates to a refrigerating machine oil composition characterized in containing a hydrocarbon oil and an alicyclic polycarboxylic acid ester compound.
2. Related Background Art
Owing to the restriction of fluorocarbons for preventing ozone layer destruction and prevention of global warming, efforts are being made to replace chlorine-containing refrigerants such as CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) with HFC (hydrofluorocarbon), and to realize high efficiency of a refrigerating system. On the other hand, since HFC refrigerants are also the objects under the restriction for preventing global warming, the application of natural refrigerants such as carbon dioxide, ammonia, hydrocarbons have been researched.
In accordance with the efforts to substitute the above-mentioned refrigerants for the conventional refrigerants, various refrigerating machine oils have been developed. These refrigerating machine oils must satisfy a number of performance requirements including lubricity, refrigerant miscibility, heat stability/hydrolysis resistance, electric insulating ability, low hygroscopicity and the like. Therefore, the compounds contained in the refrigerating machine oils are selected to meet the required performances on the basis of the type and the use of the refrigerants. For example, refrigerating machine oils for HFC refrigerants may contain oxygen compounds such as esters, ethers and carbonates that are miscible with the refrigerant, or they may contain alkylbenzene having inferior miscibility with the refrigerant but having excellent lubricity, heat stability and hydrolysis resistance.
In order to achieve a high efficiency of a refrigerating system, the efforts have been made to lower the viscosity of the refrigerating machine oil. The ester refrigerating machine oils, such as polyol ester obtained from the reaction between an aliphatic polyhydric alcohol and a fatty acid, are disclosed in Japanese Translation Publication No. Hei 3-505602 (JP-A 3-505602) of International Publication for Patent Application and Japanese Patent Kokai (Laid-Open) Publication No. Hei 3-128991 (JP-A 3-128991). One effective means for lowering viscosity of such kinds of ester refrigerating machine oils is to select a fatty acid having a small number of carbon atoms in its alkyl group. However, in general, an ester obtained from a fatty acid with a small alkyl group would have low heat stability and hydrolysis resistance.
Japanese Patent Kokai (Laid-Open) Publication No. Hei 9-221690 (JP-A 9-221690) discloses an alicyclic polycarboxylic acid ester which is an ester refrigerating machine oil having excellent heat stability and hydrolysis resistance. However, even the ester having this structure has not sufficient heat stability and hydrolysis resistance when the viscosity thereof is lowered.
Therefore, an ester refrigerating machine oil that has both low viscosity for obtaining a high efficiency and high heat stability/hydrolysis resistance, and can also satisfy other required performances has not be developed yet.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above-mentioned technical problems. Therefore, an object of the present invention is to provide a refrigerating machine oil composition having excellent lubricity, refrigerant miscibility, heat stability/hydrolysis resistance, electric insulating ability and other performances, and can achieve a high efficiency of a refrigerating system when it is used together with an HFC refrigerant or a natural refrigerant such as carbon dioxide and hydrocarbon.
As the results of intensive researches conducted by the present inventors to achieve the above described object, it is found that an excellent refrigerating machine oil composition having the above-mentioned various performances can be obtained by blending a specific ester oil into a hydrocarbon oil.
The refrigerating machine oil composition according to the present invention comprises (A) a hydrocarbon oil and (B) an alicylic polycarboxylic acid ester compound having an alicyclic ring and at least two ester groups represented by formula (1) bonded to adjacent carbon atoms of the alicyclic ring:
—COOR
1
(1)
wherein R
1
represents a hydrocarbon group having 1-30 carbon atoms, and R
1
of each of the ester groups may be the same or different from each other.
In the refrigerating machine oil composition according to the present invention, the hydrocarbon oil is preferably at least one oil selected from a group consisting of mineral oils, olefin polymers, naphthalene compounds and alkylbenzenes; among which alkylbezenes are more preferable.
The alicylic polycarboxylic acid ester compound has preferably two ester groups represented by the formula (1).
The refrigerating machine oil composition according to the present invention preferably further comprises an epoxy compound and/or a phosphorus compound. The epoxy compound is preferably at least one compound selected from a group consisting of phenylglycidyl ether epoxy compounds, glycidyl ester epoxy compounds, alicyclic epoxy compounds and epoxidized fatty acid monoesters, among which glycidyl ester epoxy compounds and/or alicyclic epoxy compounds are more preferable.
A fluid composition for refrigerating machines according to the present invention comprises the above-described refrigerating machine oil composition according to the present invention and a chlorine-free fluorocarbon.
DESCRIPTION OF THE PREFFERRED EMBODIMENTS
The best modes for carrying out the present invention will be explained in detail hereinafter.
The component (A), i.e., the hydrocarbon oil in the refrigerating machine oil composition according to the present invention is an oil selected from a group consisting of mineral oils, olefin polymers, naphthalene compounds and alkylbenzenes; or a mixture of two or more kinds of these oils.
The mineral oil used in the present invention may be selected from paraffin mineral oils or naphthene mineral oils obtained by employing one or more suitably combined refining means such as solvent deasphalting, solvent extraction, hydrogenolysis, solvent dewaxing, catalyst dewaxing, hydrofinishing, sulfuric acid washing and clay treatment to treat lubricant oil fractions obtained from the atmospheric distillation and vacuum distillation of paraffin base crude oil, intermediate base crude oil or naphthene base crude oil.
Among the above-mentioned mineral oils, those highly refined are preferable due to their excellent heat stability. The non-aromatic unsaturated parts (unsaturation) in the highly refined mineral oils used in the present invention is preferably 10% or less. When the unsaturation exceeds 10%, it probably causes the generation of sludge and the clogging of capillaries. Therefore, the unsaturation in the present invention is more preferably not more than 5%, furthermore preferably not more than 1%, and the most preferably not more than 0.1%. The examples of the highly refined mineral oils used in the present invention include refined oils obtained by using conventional means to refine the distillate oils from the atmospheric distillation or the combination of atmospheric distillation and then vacuum distillation of paraffin base crude oil, intermediate base crude oil or naphthene base crude oil; deeply dewaxed oils obtained by further deep dewaxing after the refining; and hydrogenated oils obtained by further hydrogenation. Various refining method scan be used in this case without any specific restriction.
In general, (a) hydrogenation, (b) dewaxing (solvent dewaxing or hydrogenation dewaxing), (c) solvent extraction, (d) alkali washing or sulfuric acid washing, and (e) clay treatment can be carried out singly or in combination in a suitable order. It is also effective to divide a single treatment into several stages and carry it out repeatedly. For example, the distillate oil can be refined by (i) hydrogenation, or further alkali washi
Hirano Hiroyuki
Shimomura Yuji
Suda Satoshi
Einsmann Margaret
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Nippon Mitsubishi Oil Corp.
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