Refrigerating machine oil composition for use with HCFC and HFC refrigerants

摘要

A refrigerating machine oil composition for vapor compression type refrigerating machines is disclosed which can be used with either of HCFC refrigerants and HFC refrigerants. The inventive machine oil composition comprises a polyol ester (ester compound) as a base oil. Furthermore, the base oil contains from 1.0 to less than 5.0% by weight of a phosphate, from 0.1 to 2.0% by weight of an alkyl phosphorothionate and/or an aryl phosphorothionate, and from 0.05 to 2.0% by weight of an epoxy compound. The composition is free from sludge formation and insufficient lubricity, which are drawbacks of the polyol ester, due to the synergistic effect of these additives. On the other hand, the inventive composition provides the desirable properties of a polyol ester base oil, namely, good compatibility with refrigerants, high electrical insulating properties, and low hygroscopicity.