REFRIGERATOR OIL AND HYDRAULIC FLUID COMPOSITION FOR REFRIGERATOR

摘要

PROBLEM TO BE SOLVED: To provide a refrigerator oil attaining all of excellent refrigerant compatibility, lubricity and low temperature fluidity at a high level when using with difluoromethane refrigerant; and a hydraulic fluid composition for refrigerator using the same.SOLUTION: The refrigerator oil is an ester of pentaerythritol and fatty acid and contains ≥10 mass% ester in which the ratio by mol of a 6C branched fatty acid and 3,5,5-trimethyl hexanoic acid in the fatty acid is 20:80-80:20 and the ratio of total of the 6C branched fatty acid and 3,5,5-trimethyl hexanoic acid occupying in the fatty acid is ≥20 mol% on the basis of total quantity of the refrigerator oil and is used with the difluoromethane refrigerant. The hydraulic fluid composition for refrigerator contains the refrigerator oil and the difluoromethane refrigerant.