| 摘要 |
PROBLEM TO BE SOLVED: To provide a mixed ester used for a refrigerating machine oil and the like that has excellent compatibility with a difluoromethane refrigerant while ensuring excellent low-temperature characteristics and a viscosity range required of a refrigerating machine oil.SOLUTION: The mixed ester comprises a pentaerythritol, a pentanoic acid, 2-methyl butyrate, and 3,5,5-trimethyl hexanoic acid. It is characterized in that (1) a degree X of variation as a value showing a distribution of 15 kinds of tetraester of pentaerythritol constituting the mixed ester in the range of 1.0 to 2.5; (2) an average ClogP value of 15 kinds of tetraester of pentaerythritol constituting the mixed ester is in the range of 9.0 to 13.0; and (3) when the mixed ester and difluoromethane is mixed in a weight ratio of the mixed ester to the difluoromethane (the mixed ester:the difluoromethane) of 90:10, a two-layer separation temperature at the low temperature side is in the range of -10 to -60°C. |
