Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With lubricants – or warning – stabilizing or anti-corrosion...
Reexamination Certificate
1999-01-20
2001-04-24
Medley, Margaret (Department: 1744)
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
With lubricants, or warning, stabilizing or anti-corrosion...
C508S304000, C508S438000, C508S440000
Reexamination Certificate
active
06221274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerating machine oil and a fluid composition for operating a refrigerating machine, more specifically a lubricant composition for a refrigerating machine employing a HFC-type refrigerant which contains at least one of HFC-32, HFC-125 and HFC-134a and using an ester having a specific structure alone or as a mixture of various types.
2. Discussion of Background
In recent years, by the problem of the depletion of ozone layer, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) conventionally used as refrigerants for refrigerating machines, have been prohibited by regulations, and HFC (hydrofluorocarbon) has been used as a refrigerant instead of them. As a refrigerating machine oil for the HFC refrigerant, PAG (polyalkylene glycol), esters and the like which are compatible with HFC, have been studied or employed. For example, PAG is disclosed in U.S. Pat. No. 4,755,316, JP-A-1-198694, JP-A-1-256594, JP-A-1-259093, JP-A-1-259094, JP-A-1-259095, JP-A-1-274191, JP-A-2-43290, JP-A-2-55791 and JP-A-2-84491. The esters are disclosed in Japanese PCT publication No. 3-505602, JP-A-3-55791, JP-A-3-88892, JP-A-2-128991, JP-A-2-128992, JP-A-3-200895, JP-A-3-227397, JP-A-4-20597, JP-A-4-72390, JP-A-4-218592 and JP-A-4-218593. However, PAG has drawbacks of a high moisture adsorption and poor electrical insulating properties. On the other hand, ester oils may undergo hydrolysis and form an acid due to its structure, and the formed acid will be expected to cause various inconveniences in the refrigerating machine system. Further, these oils tend to be inferior in the lubricating properties to a conventional system of a mineral oil and CFC/HCFC or a conventional system of a mineral oil, an alkylbenzene and CFC/HCFC, whereby it has been studied to incorporate various additives thereto. The refrigerating machine oil is susceptible to the high temperature and high pressure atmosphere in a refrigerating compressor, or stains due to e.g. thermal decomposition of the refrigerating machine oil tend to attach within the compressor. These drawbacks bring about new problems. Under such circumstances, the present inventors have made extensive studies to improve the cleanness in the compressor, and as a result, found that the cleanness of various types of compressors can be improved by incorporating specific additives in specific amounts. They have accomplished the present invention based on the discovery.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a refrigerating machine oil employing at least one of HFC-32, HFC-125 and HFC-134a as a refrigerant, by which the anti-corrosion properties and the cleanness in the compressor are excellent, the cleanness can be maintained particularly within the compressor over a long period of time, and a high reliability can be obtained.
The present invention provides a lubricant composition for a refrigerating machine employing a HFC type refrigerant containing at least one selected from the group consisting of HFC-32, HFC-125 and HFC-134a, which comprises a base oil of an ester formed from a dihydric or higher polyol as an alcohol and a monobasic aliphatic acid, alone or as a mixture thereof; and additives of, based on the total amount, 1) not less than 0.01 vol % and less than 1.0 vol % of a phosphate, 2) from 0.01 to 1.0 vol % of at least one of an alkylphosphorothionate and an arylphosphorothionate and 3) from 0.01 to 1.0 vol % of an epoxy compound.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be described in further detail.
In the present invention, as an ester for the base oil of the refrigerating machine oil composition, any synthetic esters composed of a dihydric or higher alcohol and a monobasic aliphatic acid may be used. The alcohol is preferably a neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol, more preferably trimethylolpropane and pentaerythritol. As the monobasic aliphatic acid, propionic acid, isopropionic acid, butanoic acid, isobutanoic acid, pentanoic acid, isopentanoic acid, hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, isooctanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, undecanoic acid and lauric acid may be mentioned. These monobasic aliphatic acids may be used alone or as a mixture of two or more of them for esterification reaction. Further, the blend ratio thereof may be changed optionally depending upon the refrigerating machines to be used. However, it should be mentioned that these are used for the base oil and the addition thereof does not contribute to the improvement of the cleanness of the compressor. The cleanness of the compression can be improved by adding 1) a phosphate, 2) at least one of an arylphosphorothionate and an alkylphosphorothionate and 3) an epoxy compound to the base oil. Here, as the phosphate of the component 1), tributylphosphate, trihexylphosphate, trioctylphosphate, trinonylphosphate, tridecylphosphate, trioleylphosphate, triphenylphosphate, tricresylphosphate, phenyl-diisopropylphenylphosphate and tris(isopropylphenyl)phosphate may, for example, be mentioned. Particularly preferred are phenyl-diisopropylphenylphosphate, tris(isopropylphenyl)phosphate and tricresylphosphate. As the arylphosphorothionate and alkylphosphorothionate of the component 2), trihexylphosphorothionate, triphenylphosphorothionate tris(methylphenyl)phosphorothionate and tris(isobutylphenyl)phosphorothionate may, for example, be mentioned. Among them, triphenylphosphorothionate is particularly preferred. Further, as the epoxy compound, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 1,2-epoxyheptadecane and 1,2-epoxyoctadecane, and as an alicyclic epoxy compound, vinylcyclohexene dioxide and 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane, may, for example, be mentioned. These may be used alone or as a mixture thereof without any problem. However, it is particularly preferred to use 1,2-epoxydecane, vinylcyclohexene dioxide and l-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane alone or in combination.
The above three additives are preferably incorporated in such ratio that 1):2):3)=not less than 0.1 vol % and less than 1.0 vol %:0.1 to 1.0 vol %:0.01 to 0.5 vol %, more preferably 1):2):3)=0.1 to 0.7 vol %:0.1 to 0.7 vol %:0.1 to 0.5 vol %, based on the total amount.
For the refrigerating machine oil composition of the present invention, conventional additives such as an antioxidant, a metal deactivator or a defoaming agent may be used within such a range that the cleanness intended in the present invention can be improved.
As the antioxidant, for example, ones of a hindered phenol type, an amine type or a sulfur type, such as, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis(2,6-di-butylphenol), 2,2′-thiobis(4-methyl-6-t-butylphenol), p,p′-dioctyldiphenylamine, 3,7-dioctylphenothiazine, phenyl-&agr;-naphthylamine and an alkyldisulfide may, for example, be mentioned.
As the metal deactivator, alizarin, quinizarin and benzotriazole may, for example, be used.
As the defoaming agent, dimethylpolysiloxane and carbonic acid metal salts may, for example, be used. These additives may be incorporated alone or as a mixture of two or more of them. The amounts of the additives i.e. the antioxidant, metal deactivator and defoaming agent are usually not more than 10 vol %, preferably not more than 5 vol % based on the total amount.
Hereinafter, the refrigerant used for the refrigerating machine employing the refrigerating machine oil of the present invention will be described. First, when the HFC type refrigerant is HFC-32, the refrigerant used for the refrigerating machine employing the refrigerating machine oil of the present invention is HFC-32 alone, or ones having a C
1-3
, preferably C
1-2
alkanefluoride blended
Akahori Yasushi
Izawa Takeshi
Magome Tomohiro
Masuda Noboru
Muraki Masayoshi
Medley Margaret
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toomer Cephia D.
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