To obtain a hydraulic fluid composition comprising a base oil consisting essentially of a cyclic ketal, etc., an acidic phosphorous ester, a specific amine compound and a hydrofluorocarbon, excellent in heat stability, electrical insulating properties and moisture absorption, not causing a carboxylic acid by hydrolysis.
This composition for a refrigerator hydraulic fluid comprises (A) a base oil consisting essentially of a cyclic ketal or a cyclic acetal, (B) an acidic phosphorous ester of formula (X1 is a 2-4C alkylene; (p) is 0-30; X2 is H, a 1-18C straight-chain alkyl, a 6-18C aryl, etc.; when (p) is 0, X2 is not H), (C) an amine compound of formula II (X3 to X6 are each H, a 1-18C straight- chain alkyl, a 6-18C aryl, etc.; X7 is a 2-4C alkylene; (m) is 0-4, when (m) is 0, at least one of X3, X4 and X6 is except H) and when (m) is 1 to 4, at least one X3, X4 to X6 is except H) and (D) a hydrofluorocarbon.
HAGIWARA TOSHIYA
SAKAI AKIMITSU
TOGASHI HIROYASU
KOBAYASHI YUICHIRO
