Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic oxygen compound
Reexamination Certificate
2000-11-13
2003-12-02
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic oxygen compound
C252S067000, C252S068000, C508S485000
Reexamination Certificate
active
06656891
ABSTRACT:
This application is a 371 of PCT/SP99/02449 filed May 12, 1999.
TECHNICAL FIELD
The present invention relates to a refrigerating machine oil composition. More specifically, it relates to a refrigerating machine oil composition having good properties that a capillary tube is hardly clogged and so forth when a hydrofluorocarbon type, a fluorocarbon type, a hydrocarbon type, an ether type, a carbon dioxide type or an ammonia type, preferably a hydrofluorocarbon type which can be a substitute for a chlorofluocarbon type refrigerant problematic due to the environmental pollution is used as a refrigerant.
BACKGROUND OF THE INVENTION
Generally, a compression-type refrigerating machine comprises at least a compressor, a condenser, an expansion mechanism (expansion valve and the like), an evaporator and further a drier, having a structure that a mixed liquid of a refrigerant and lubricating oil is circulated in this closed system. As a refrigerant of a compression-type refrigerating machine, especially, an air-conditioner, chlorodifluoromethane (hereinafter referred to as R22) or a mixture of chlorodifluoromethane and chloropentafluoroethane at a weight ratio of 48.8:51.2 (hereinafter referred to as R502) has been of ten used so far. Further, as lubricating oil, various mineral oils or synthetic oils that meet the above-described requirements have been used. However, since there is a fear that R22 and R502 might cause the environmental pollution such as the depletion of the ozonosphere present in the stratosphere or the like, they are being strictly regulated worldwide. For this reason, hydrofluorocarbons typified by 1,1,1,2-tetrafluoroethane, difluoromethane, pentafluoroethane and 1,1,1-trifluoroethane (hereinafter referred to as R134a, R32, R125 and R143a respectively) have attracted much interest as new refrigerants, and are replacing the same. Since there is no fear that these hydrofluorocarbons, especially R134a, R32, R125 and R143a might deplete the ozonosphere, they are preferable as a refrigerant for a compression-type refrigerating machine. Nevertheless, it is problematic when the hydrofluorocarbons are used singly. For example, in “Energy-Resources”, vol. 16, No. 5, p. 474, it is reported that (1) when R134a is applied to an air-conditioner as a substitute for R22, an operating pressure is low, and an ability is decreased by approximately 40% and an efficiency by approximately 5% as compared with R22, (2) in comparison with R22, R32 is good in efficiency, but an operating pressure is high and a slight combustibility is shown , (3) R125 is incombustible, but a critical pressure is low and an efficiency is decreased, and so forth. Further, R143a is, like R32, problematic in a combustibility.
It is preferable that the refrigerant for the compression-type refrigerating machine can be used without changing the existing refrigerating machine. However, in view of the foregoing problems, a refrigerant containing the above-described hydrofluorocarbon has to be actually used. That is, in order to substitute existing refrigerants R22 and R502, it is advisable that combustible R32 and R143a are used from the aspect of the efficiency and the former is mixed with R125 and R134a for imparting an incombustibility to the entire refrigerant. In The International Symposium on R22 & R502 Alternative Refrigerants, 1994, p. 166, it is indicated that an R32/R134a mixture is combustible with the R32 content of 56% by weight or more. It is said that a refrigerant containing 45% by weight or more of an incombustible hydrofluorocarbon such as R125, R134a or the like is preferable from the aspect of the incombustibility, which cannot absolutely be defined though in view of the refrigerant composition.
Meanwhile, since a refrigerant is used under various conditions within a refrigerating system, it is undesirable that compositions of hydrofluorocarbons to be mixed vary greatly in respective positions of the refrigerating system. A refrigerant takes both gaseous and liquid forms in the refrigerating system. Accordingly, when boiling points of hydrofluorocarbons to be mixed are quite different, there is a possibility that compositions of mixing refrigerants vary greatly in respective positions of the refrigerating system for the foregoing reason.
The boiling points of R32, R143a, R125 and R134a are −51.7° C., −47.4° C., −48.5° C. and −26.3° C. respectively. When R134a is used in a hydrofluorocarbon-containing refrigerant system, care must be taken in this respect. Accordingly, in a refrigerant containing R125, its content is between 20 and 80% by weight, especially preferably between 40 and 70% by weight. When the content is less than 20% by weight, a large amount of a refrigerant having quite a different boiling point, such as R134a or the like, is further required to impart an incombustibility, which is undesirable in view of the foregoing reason. Further, when the content of R125 exceeds 80% by weight, an efficiency is decreased. Thus, it is unwanted.
In view of these points, as a substitute for the existing R22 refrigerant, a mixture of R32, R125 and R134a at a weight ratio of 23:25:52 (hereinafter referred to as R407C), a mixture thereof at a weight ratio of 25:15:60, a mixture of R32 and R125 at a weight ratio of 50:50 (hereinafter referred to as R410A), and a mixture of R32 and R125 at a weight ratio of 45:55 (hereinafter referred to as R410B) are preferable. Meanwhile, as a substitute for the R502 refrigerant, a mixture of R125, R143a and R134a at a weight ratio of 44:52:4 (hereinafter referred to as R404A) and a mixture of R125 and R143a at a weight ratio of 50:50 (hereinafter referred to as R507) are preferable.
This hydrofluorocarbon refrigerant is different from ordinary refrigerants in qualities. As refrigerating machine oil used in combination with this, a product obtained by using, for example, a polyalkylene glycol, a polyol ester, a polyvinyl ether or the like having a specific structure as base oil and adding thereto additives such as an antioxidant, an extreme pressure agent, a defoamer and the like is known to be useful.
On the other hand, in a refrigerating machine, an expansion valve called a capillary tube is provided in a refrigerating cycle. Since this capillary tube is a narrow tube having a diameter of approximately 0.7 mm, it tends to clog. The clogging phenomenon of the capillary tube is the most serious factor to determine the life of the refrigerating cycle. However, owing to the use of the additives, sludges were accumulated, and these caused the clogging of the capillary tube. Accordingly, the development of additives for dissolving materials that clog the capillary has been expected, and the advent of a refrigerating oil composition containing the same has been in demand.
DISCLOSURE OF THE INVENTION
The invention has been made from these aspects, and it aims to provide a refrigerating machine oil composition by which a capillary tube is hardly clogged when a hydrofluorocarbon type, a hydrocarbon type, an ether type, a carbon dioxide type or an ammonia type, preferably a hydrofluorocarbon type which can be a substitute for a chlorofluocarbon type refrigerant problematic due to the environmental pollution is used as a refrigerant.
The present inventors have assiduously conducted investigations, and have consequently found that the aim of the invention can effectively be achieved by mixing base oil containing oxygen-containing synthetic oil such as a polyvinyl ether or a polyol ester with a specific polyalkylene glycol alkyl ether or alkylbenzene. This has led to the completion of the invention.
That is, the gist of the invention is as follows.
First Invention
(1) A refrigerating machine oil composition characterized in that a base oil containing at least one oxygen-containing synthetic oil selected from the group consisting a polyvinyl ether and a polyol ester is mixed with 1 to 20% by weight, based on the total amount of the composition, of a polyalkylene glycol alkyl ether having a number average molecular weight of 500 to 3,000, as represented by
Sakanoue Shuichi
Takagi Minoru
Takesue Masahiko
Howard Jacqueline V.
Idemitsu Kosan Co. Ltd.
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