Flame retardant hydraulic oil.

摘要

Disclosed herein is a flame retardant hydraulic oil excellent in the flame retardancy, heat stability and oxidative stability, unaccompanied by the dangers of pinhole fire and giving rise to no environmental contamination. This flame retardant hydraulic oil contain a hydraulic base oil comprising as the essential component a synthetic ester, which is a product formed by reacting (A) at least one polyol selected from the group consisting of neopentyl glycol, 2,2-dimethyl-3-hydroxypropyl-2', 2'-dimethyl-3'-hydroxypropionate, glycerin and trimethylolpropane with (B) a carboxylic acid comprising 15 to 85% by mole of oleic acid based on the total carboxylic acid and 15 to 85% by mole of isostearic acid based on the total carboxylic acid or a carboxylic acid obtained by incorporating into said carboxylic acid 85% by mole or less of monocarboxylic acid having 6 to 22 carbon atoms (excluding oleic acids and isostearic acids) based on the total carboxylic acid. Said synthetic ester has a kinematic viscosity of 40 to 80cSt at 40 DEG C and a flash point of 290 DEG C or higher.