| 摘要 |
<p>A mixed ester prepared from pentaerythritol, pentanoic acid, 2-methylbutyric acid and 3,5,5-trimethylhexanoic acid, characterized in that: (1) the dispersion degree (X), which indicates the distribution of 15 pentaerythritol tetraesters that constitute the mixed ester, is 1.0 to 2.5; (2) the average ClogP value of 15 pentaerythritol tetraesters that constitute the mixed ester is 9.0 to 13.0; and (3) a mixture obtained by mixing the mixed ester with a difluoromethane refrigerant at a (mixed ester/refrigerant) weight ratio of 90:10 exhibits a lower-temperature-side separation temperature of -10 to -60°C, said separation temperature being a temperature at which the mixture is separated into two layers. The mixed ester exhibits excellent compatibility with a difluoromethane refrigerant while ensuring excellent low-temperature characteristics and a viscosity range necessary for refrigerating machine oils, thus being useful as a refrigerating machine oil or the like.</p> |
