APPLICATION OF COMPLEX POLYESTERS AS VISCOSITY INDEX IMPROVEMENT FOR HYDRAULIC FLUIDS DESIGNED FOR AIRCRAFT Russian patent published in 2021 - IPC C10M169/04 C10M111/04 C10M111/02 C10N40/08 C10N30/08 C10N30/02 C08L67/02 C08K3/32 

FIELD: aircraft hydraulic fluid.

SUBSTANCE: invention relates to a hydraulic fluid for an aircraft. The liquid contains from 0.5 to 20 wt.% of complex polyester and not less than 50 wt.% of the base component - an ester of phosphoric acid in terms of the weight of the hydraulic fluid. The complex polyester contains, in terms of the total number of repeating units, from 30 to 50 mol.% of the repeating units of formula , from 25 to 50 mol.% of recurring units of the formula , in which R¹ is a С₁-С₆-alkyl group, R² is a hydrogen atom, or a С₁-С₆-alkyl group, and R¹ and R² together may form a cycloalkane structure. The base component mainly consists of one or more compounds, each of which is described by the formula , in which R³, R⁴ and R⁵ are all independently selected from С₁-С₆-alkyl groups.

EFFECT: hydraulic fluid offers extended service life, improved fire resistance and low toxicity.

17 cl, 6 tbl, 10 ex