Refrigerator oil for carbon dioxide refrigerant, and method of using it for lubrication

Abstract

Provided is a refrigerator oil, especially that for carbon dioxide refrigerant, which comprises a base oil comprising an oxygen-containing organic compound as the essential component and having a kinematic viscosity at 100° C. of from 5 to 50 mm2/sec and a viscosity index of at least 60, and optionally contains additives of, for example, extreme pressure agent and acid scavenger. The refrigerator oil can be used in compression refrigerators with carbon dioxide refrigerant therein, concretely in refrigerating or heating-cooling equipment such as car air conditioners, refrigerators, freezers, air conditioners, heat pumps, compression refrigeration cycles equipped with oil separator and/or hot gas line, etc. This is stable and has excellent lubricity (abrasion resistance) even in a supercritical carbon dioxide atmosphere, and therefore can be used for a long period of time in the atmosphere.

Dependencies are inferred from the claim text.