| abstract |
A first refrigerator oil of the invention has a sodium and/or potassium concentration of 0.1 ppm or less, a low hydrolyzability and excellent insulation performance, and hence is useful as a composition for a refrigerator equipped with an enclosed compressor. A second refrigerator oil of the invention comprises mainly a carboxylic acid ester of pentaerythritol, wherein the carboxylic acid comprises a mixture of 3,5,5-trimethylhexanoic acid with a C₆-C₈ linear or branched fatty acid and the content of the trimethylhexanoic acid exceeds 50 mole % but does not exceed 90 mole %. This oil has a high viscosity and high electrical insulation properties required of refrigerator oils for large air-conditioning equipment and a household air conditioner, does not crystallize at low temperature, and is excellent in handleability. |