| abstract |
Hydraulic fluids consist of (1) 95-99.9 wt. per cent of either a siloxane of general formula <FORM:1097279/C4-C5/1> where R is a hydrocarbon or halohydrocarbon radical free from aliphatic unsaturation, n is 1.8-3 and m is at least 2 or a polyester selected from esters of C5+ alkanoic acids and polyhydric alcohols containing at least two methylol radicals bonded to a quaternary carbon atom and esters of tertiary alkyl carbinols and dicarboxylic acids, (2) 0.05-3 wt. per cent of an amine antioxidant and (3) 0.05-3 wt. per cent of a compound of formula <FORM:1097279/C4-C5/2> or a compound of formula (Q3SiO)3SiH where Q is a C1-C6 alkyl or aryl radical, at least one Q being aryl, x is 0, 1, 2, 3 or 4 and R1 is C1-C3 alkyl, C1-C3 alkoxy, phenyl, tolyl, naphthyl, vinyl or a <FORM:1097279/C4-C5/3> radical, the ratio of (2) to (3) being from 1:2 to 2:1. Amines specified are phenyl-alpha and beta-naphthylamine, phenothiazine, N-ethyl-1-naphthylamine, 1-naphthylamine and dioctyldiphenylamine.ALSO:Hydraulic fluids consist of (1) 95-99.9 weight per cent of a siloxane of general formula <FORM:1097279/C3/1> where R is a hydrocarbon or halohydrocarbon radical free fro aliphatic unsaturation, n is 1.8-3 and m is at least 2; (2) 0.05-3 weight per cent of an amine antioxidant; and (3) 0.05-3 weight per cent of a compound of formula <FORM:1097279/C3/2> or a compound of formula (Q3SiO)3SiH where A is a C1-C6 alkyl or aryl radical, at least one Q being aryl, x is 0, 1, 2, 3 or 4 and R1 is C1-C3 alkyl, C1-C3 alkoxy, phenyl, tolyl, naphthyl, vinyl or a <FORM:1097279/C3/3> radical, the ratio of (2) to (3) being from 1:2 to 2:1. Amines specified are phenyl-alpha and beta - naphethylamine, phenothiazine, Nethyl - 1 - naphthylamine, 1 - naphthylamine and dioctyldiphenylamine. |