| 摘要 |
PROBLEM TO BE SOLVED: To obtain a machine oil composition for refrigerators that has excellent lubrication properties and high sealing properties and can be stably used for a long period of time in a compression type refrigerating cycle using a refrigerant comprising carbon dioxide as the main component. SOLUTION: In this lubrication process, (1) the machine oil for refrigerators comprises a refrigerant mainly composed of carbon dioxide and a lubricant oil composition mainly containing an ester oil, in addition, a base oil with a dynamic viscosity of 5.5-30 mm2/s at 100 deg.C, 0.005-5 wt.%, based on the base oil, of an extreme-pressure agent and/or an acid-capturing agent. This machine oil composition is used in a compression type refrigerating cycle having an oil separator and/or a hot gas line. |
