Compositions – Electrolytes for electrical devices
Patent
1989-09-08
1992-04-28
Willis, Jr., Prince
Compositions
Electrolytes for electrical devices
C10M12910
Patent
active
051086344
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
This invention relates to a lubricating oil composition, more specifically to a lubricating oil composition which has excellent high temperature stability and also excellent low temperature characteristics, and is suitable as a refrigerator oil, a heat pump oil, etc.
Background Art
In recent years, the tendency of increasing high efficiency, miniaturization and weight reduction have rapidly progressed in refrigerators, and the reciprocating system in compressors has changed to the rotary system. Further, there is a tendency that the temperature of exhaust gas is rising due to loading of an inverter or recovery of exhaust heat by a heat pump. Therefore, it is strongly required of a refrigerator oil, etc. to have high temperature stability.
Heretofore, in order to provide such high temperature stability, it has been carried out to blend a stabilizer such as 2,6-di-t-buthyl-p-cresol, etc. into a base oil. However, the above stabilizer precipitates at the low temperature portion in the refrigerator system such as a swelling valve, a capillary tube, etc. whereby it causes problems of clogging circuit of the refrigerator system or inhibiting coolant flow. Thus, a phenomenon preventing normal operation of the refrigerator has been caused.
Accordingly, the present inventor has intensively studied to solve the problems of the above conventional refrigerator oil, etc., and to develop a lubricating oil with excellent high temperature stability and at the same time have improved low temperature characteristics.
As a result, it has been found that the above object can be accomplished by blending an alkyl group-substituted phenol compound having a melting point of 20.degree. C. or lower and a base oil of a lubricating oil which is highly purified and has a specific characteristic with a specific ratio. The present invention has completed based on such a finding.
An object of the present invention is to provide a lubricating oil composition with excellent high temperature stability and low temperature characteristics.
Also, another object of the present invention is to provide a lubricating oil composition used as a stable refrigerator oil, etc., under a Flon coolant atmosphere.
DISCLOSURE OF INVENTION
That is, the present invention is to provide a lubricating oil composition which comprises, as main components, (A) 100 parts by weight of a base oil having a kinematic viscosity at 40.degree. C. of 5 to 500 cSt, a pour point of -30.degree. C. or lower and a viscosity index of 70 or more, and (B) 0.01 to 5 parts by weight of an alkyl group-substituted phenol compound having a melting point of 20.degree. C. or lower.
The lubricating oil composition of the present invention comprises the above components (A) and (B) as the main components, and the base oil of Component (A) has a kinematic viscosity at 40.degree. C. of 5 to 500 cSt, preferably 10 to 300 cSt. In the material having the kinematic viscosity at 40.degree. C. of less than 5 cSt, wear-resistance and extreme pressure properties are lowered. On the other hand, if it exceeds 500 cSt, undesirably increasing power loss results due to high viscosity. Also, the pour point of the base oil should be -30.degree. C. or lower, preferably -35.degree. C. or lower. There are no specific limits regarding the cloud point, but preferably--20.degree. C. or lower, most preferably -30.degree. C. or lower. If the pour point exceeds -30.degree. C., precipitates are generated at low temperature, and as the result, there is a fear that it will clog a swelling valve, etc. of the refrigerator system when used as a refrigerator oil, etc. This phenomenon is likely to result when the cloud point exceeds -20.degree. C., and therefore it is most preferred that the pour point is -30.degree. C. or lower and the cloud point is -20.degree. C. or lower.
Further, the base oil shall have a viscosity index of 70 or more, particularly preferably 75 or more. If the viscosity index is less than 70, the sealing property at high temperature is lowered and wear-resistance is als
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Idemitsu Kosan Company Limited
Johnson Jerry D.
Willis Jr. Prince
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