| 摘要 |
A functional fluid comprising a novel base stock composition comprising between about 50% and about 70% by weight of a trialkyl phosphate in which the alkyl substituents are C3 to C8 and are bonded to the phosphate moiety via a primary carbon atom, between about 18% and about 35% by weight of a dialkyl aryl phosphate in which the alkyl substituents are C3 to C8 and are bonded to the phosphate moiety via a primary carbon atom, and from 0 to about 5% by weight of an alkyl diaryl phosphate. Preferably, the alkyl substituents are isobutyl or isopentyl. The fluid further comprises an acid scavenger, an anti-erosion additive, a viscosity index improver, and an antioxidant. A novel additive combination comprises a high molecular weight butyl/hexyl methacrylate viscosity index improver, a perfluoroalkylsulfonate anti-erosion additive, a 3,4-epoxy-cyclohexane carboxylate or a diepoxide acid scavenger, a di(alkylphenyl)amine, and a phenolic antioxidant comprising a mixture of a 2,4,6-trialkylphenol and a hindered polyphenol composition selected from the group consisting of bis(3,5-dialkyl-4-hydroxyaryl)methane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroyaryl)benzene and mixtures thereof. Preferably, the composition further comprises a 4,5dihydroimidazole derivative to enhance the stability of the fluid.
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