A refrigerating machine oil for a carbon dioxide refrigerant according to the present invention contains polyalkylene glycol represented by the following general formula (1):
R1-(OR3)n-OR2}m (1)
[where R1 represents a residue obtained by removing m hydroxyl groups from an organic compound having three to ten hydroxyl groups, R2 hydrogen, an alkylene group of one to five carbons, or an acyl group of one to five carbons, R3 an alkylene group of two to four carbons, m an integer of 3 to 10, and n such an integer that a number average molecular weight of the polyalkylene glycol (1) becomes 500 to 3000],
wherein a kinematic viscosity at 100°C of the polyalkylene glycol is 5-20 mm2/s.
根据本发明,一种用于
二氧化碳制冷剂的冷冻机油含有由以下通式(1)表示的聚亚烷基二醇:
R1-(OR3)n-OR2}m (1)
[其中 R1 代表从具有三至十个羟基的有机化合物中除去 m 个羟基而得到的残余物,R2 代表氢、一至五个碳原子的亚烷基或一至五个碳原子的酰基,R3 代表二至四个碳原子的亚烷基,m 代表 3 至 10 的整数,n 代表使聚亚烷基二醇(1)的平均分子量变为 500 至 3000 的整数]、
其中聚亚烷基二醇在 100°C 时的运动粘度为 5-20 mm2/s。