Process for lubricating a refrigerator containing sliding parts made of an engineering plastic material

Abstract

A process to lubricate a refrigerator preferably having a sliding portion which is made of an engineering plastic material, or provided thereon with an organic coating film or an inorganic coating film is provided. The process includes contacting sliding parts of the refrigerator with a refrigerating machine oil composition having a base oil containing a polyvinyl ether and / or a polyoxyalkylene glycol derivative as a main component and having a kinematic viscosity of 1 to 8 mm2 / s as measured at 40° C. The refrigerating machine oil composition has a low viscosity, an improved energy saving performance, a good sealability and an excellent compatibility with a refrigerant and, therefore, the process can be suitably used in various refrigerating application fields, in particular, in closed-system refrigerators.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation application of prior U.S. patent application Ser. No. 11 / 913,108, filed Oct. 30, 2007, the disclosure of which is incorporated herein by reference in its entirety. The parent application is the national stage of PCT / JP06 / 316864, filed Aug. 28, 2006, the disclosure of which is incorporated herein by reference in its entirety. The parent application claims priority to Japanese Application No. 2005 252642 filed Aug. 31, 2005, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to refrigerating machine oil compositions, and more particularly to refrigerating machine oil compositions having a low viscosity, an improved energy saving performance, a good sealability and an excellent compatibility with a refrigerant which are suitably used in various refrigerating application fields, in particula...

AI Technical Summary

Benefits of technology

[0028]In accordance with the present invention, there is provided a refrigerating machine oil composition having a low viscosity, an improved energy saving performance, a good sealability and an excellent compatibility with a refrigerant which is suitably used in various refrigerating application fields, in particular, closed-system refrigerators.

Problems solved by technology

If the mixed liquid undergoes the phase separation during operation of the refrigerators, the life or operation efficiency of these apparatuses tends to be considerably adversely affected.

For example, if the mixed liquid suffers from phase separation into the refrigerant and the lubricant in the compressor, poor lubrication occurs at a movable part thereof, resulting in defects such as seizing and, therefore, remarkably shortened life of the apparatuses.

Whereas, if the phase separation occurs in the evaporator, a heat exchange efficiency of the apparatuses tends to be deteriorated owing to a high-viscous lubricant being present therein

However, these compounds contain chlorine causing environmental problems.

However, HFC has been reported to have adverse influence on global warming.

Although a necessary viscosity of the lubricant varies depending upon kinds of the compressor and use conditions thereof, the lubricant before mixing with the refrigerant preferably has a viscosity (kinematic viscosity) of 10 to 200 mm2 / s as measured at 40° C. It has been conventionally reported that if the viscosity of the lubricant is lower than the above specified range, a thickness of an oil film formed tends to be reduced, resulting in poor lubrication, whereas if the viscosity of the lubricant is higher than the above specified range, a heat exchange efficiency of the refrigerators tends to be lowered.

The refrigerators using a refrigerating machine oil having such a high viscosity tend to inevitably suffer from a large energy consumption.

However, when the viscosity of the refrigerating machine oil is further reduced, there tends to arise such a problem that a sealability and a lubricating property thereof are deteriorated.

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