| abstract |
A diester represented by the formula wherein A represents a cyclohexane, cyclohexene or benzene ring, X is H or methyl, Rx and Ry are the same or different and each is C3-C18 branched-chain alkyl, C1-C18 straight-chain alkyl, C2-C18 straight-chain alkenyl or C3-C10 cycloalkyl, provided that when A is a benzene ring, Rx and Ry are different from each other and -COORx and -COORy are attached to two adjacent carbon atoms of the benzene ring, and having the following properties: (1) a total acid number of 0.05 mgKOH/g or less, (2) a sulfated ash content of 10 ppm or less, (3) a sulfur content of 20 ppm or less, (4) a phosphorus content of 20 ppm or less, (5) a peroxide value of 1.0 meq/kg or less, (6) a carbonyl value of 10 or less, (7) a volume resistivity of 1x10<SP>11</SP> Ω.cm or more, (8) a hydroxyl value of 3 mgKOH/g or less, and (9) a water content of 100 ppm or less, a process for preparing the same and a refrigerator lubricating oil comprising the diester. |