Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With lubricants – or warning – stabilizing or anti-corrosion...
Reexamination Certificate
1997-10-03
2001-03-27
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
06207071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a refrigerator oil and a fluid composition for a refrigerator, and in particular to a refrigerator oil and a fluid composition containing said oil for use in a refrigerator, the refrigerator oil comprising an alkyl benzene having a specific feature and being suited for use with an HFC refrigerant containing 1,1,1,2-tetrafluoroethane (HFC-134a) and/or pentafluoroethane (HFC-125).
2. Prior Art
Due to the recent problems as to the destruction of the ozone layer, the use of CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) which have been conventionally used as a refrigerant for a refrigerator is now restricted under a regulation. Therefore, as a replacement of these materials, HFC (hydrofluorocarbon) has been increasingly employed as a refrigerant.
Under the circumstances, PAG (polyalkyleneglycol) and esters which are compatible with HFC have been studied or used as an oil for a refrigerator using an HFC refrigerant. For example, the use of PAG is proposed in U.S. Pat. No. 4,755.316; Japanese Patent Unexamined Publications No. Hei 1-198694, No. Hei 1-256594, No. Hei 1-259093, No. Hei 1-259094, No. Hei 1-259095, No. Hei 1-274191, No. Hei 2-43290, No. Hei 2-55791 and No. Hei 2-84491. The use of esters is proposed in PCT. Publication No. Hei 3-505602; Japanese Patent Unexamined Publications No. Hei 3-88892, No. Hei 2-128991, No. Hei 3-128992, No. Hei 3-200895, No. Hei 3-227397, No. Hei 4-20597, No. Hei 4-72390, No. Hei 4-218592 and No. Hei 4-249593.
However, PAG is rather high in hygroscopicity and poor in electric characteristics (volume resistivity). On the other hand, ester-based oils are readily hydrolyzed to generate an acid thus possibly giving rise to various problems. Moreover, these oils are accompanied with a serious problem that they are inferior in lubricity as compared with a mineral oil/CFC or a mineral oil/HCFC.
On the other hand, Japanese Patent Unexamined Publications No. Hei 5-157379 describes a refrigerating system for an HFC-134a refrigerant wherein there is used a refrigerator oil which is incompatible with a refrigerant. As an example of such an oil, an alkylbenzene is disclosed therein. However, it has been found that if an ordinary alkylbenzene is to be used as a refrigerator oil for HFC-134a and/or HFC-125, some specific means is required to be taken on the side of the system, and that if an ordinary alkylbenzene is used as a refrigerator oil for HFC-134a and/or HFC-125 without taking such specific means, the seizure of a refrigerating compressor used may possibly be caused after a long period of its operation.
The present inventors took notice of an alkylbenzene which is free from hydrolysis and hygroscopicity and made an extensive study to finally find out that if an alkylbenzene having a specific property is used as a refrigerator oil for HFC-134a and/or HFC-125, the seizure of the refrigerating compressor can be avoided, thus indicating an excellent lubricity of the alkylbenzene, and that the alkylbenzene is capable of maintaining a high reliability for a long period of time. This invention has thus been accomplished in one aspect.
It has further been found out by the present inventors that when a phosphoric ester compound is added in a specific ratio to the above alkylbenzene having a specific property and the resulting mixture is used as a refrigerator oil in a refrigerator, the wear resistance and load resistance of the refrigerator can be improved. This invention has thus been accomplished in another aspect.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a refrigerator oil to be used with an HFC refrigerant containing HFC-134a and/or HFC-125, which enables a refrigerating compressor to be prevented from its seizure, is excellent in lubricity and retains high reliability for a long period of time.
Another object of the present invention is to provide a fluid composition for use in a refrigerator, which comprises the above refrigerator oil and an HFC refrigerant containing HFC-134a and/or HFC-125.
In a first aspect of this invention, there is provided a refrigerator oil for use with an HFC refrigerant containing HFC-134a and/or HFC-125, which comprises an alkylbenzene oil containing 60% by weight or more of alkylbenzenes having a molecular weight of 200 to 350.
In a second aspect of this invention, there is provided an oil composition for use with an HFC refrigerant containing HFC-134a and/or HFC-125, which comprises, as a base oil, an alkylbenzene oil containing 60% by weight or more of alkylbenzenes having a molecular weight of 200 to 350, and 0.01 to 5.0% by weight (based on the total amount of the oil composition) of a phosphoric ester compound.
In a third aspect of this invention, there is provided a fluid composition for use in a refrigerator which comprises;
[I] an HFC refrigerant containing HFC-134a and/or HFC-125; and
[II] a refrigerator oil comprising an alkylbenzene oil containing 60% by weight or more of alkylbenzenes having a molecular weight of 200 to 350.
In a further aspect of this invention, there is provided a fluid composition for use in a refrigerator which comprises;
[I] an HFC refrigerant containing HFC-134a and/or HFC-125; and
[II] an alkylbenzene oil containing 60% by weight or more of alkylbenzenes having a molecular weight of 200 to 350 as a base oil, which base oil is mixed with 0.01 to 5.0% by weight (based on the total amount of the oil composition) of a phosphoric ester compound.
This invention will be further explained in detail with reference to the following preferred embodiments.
The refrigerator oil proposed by this invention comprises an alkylbenzene oil containing at least 60% by weight of alkylbenzenes having a molecular weight of 200 to 350.
To be more specific, it is required for the alkylbenzene oil to contain at least 60% by weight, preferably at least 65% by weight, more preferably at least 70% by weight, still more preferably at least 80% by weight, most preferably 100% by weight of alkylbenzenes having a molecular weight of 200 to 350. If there is employed an alkylbenzene oil containing less than lower limit of alkylbenzenes having a molecular weight of 200 to 350, the seizure of a refrigerating compressor used may possibly be caused after a long period of operation, thus undesirably affecting the reliability of the refrigerator oil.
Further, in view of improving the property for preventing the generation of seizure of refrigerating compressor during a long period of operation, the alkylbenzene oil may desirably be selected from those containing 30% by weight or more, more preferably 35% by weight or more, most preferably 40% by weight or more of alkylbenzenes having a molecular weight of 200 to 300.
As for the alkylbenzene oil constituting a refrigerator oil of this invention, there is no restriction with respect to the molecular structure of the component alkylbenzenes as far as the molecular weight thereof falls within the range of from 200 to 350. However, in view of improving a long-term reliability of a refrigerating system, it is preferable to select an alkylbenzene (A) having 1 to 4 alkyl groups, each group containing 1 to 19 carbon atoms and the total amount of carbon atoms in the alkyl groups being 9 to 19, and more preferably to select an alkylbenzene having 1 to 4 alkyl groups, each group containing 1 to 15 carbon atoms and the total amount of carbon atoms in the alkyl groups being 9 to 15.
Examples of alkyl group containing 1 to 19 carbon atoms are methyl, ethyl, propyl (including all isomers), butyl (including all isomers), pentyl (including all isomers), hexyl (including all isomers), heptyl (including all isomers), octyl (including all isomers), nonyl (including all isomers), decyl (including all isomers), undecyl (including all isomers), dodecyl (including all isomers), tridecyl (including all isomers), tetradecyl (including all isomers), pentadecyl (including all isomers), hexadecyl (including all isomers), heptadecyl (including all i
Sasaki Umekichi
Suda Satoshi
Takigawa Katsuya
Einsmann Margaret
Morrison Law Firm
Nippon Mitsubishi Oil Corporation
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