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US 2020/0318028 A1Published application
Hydraulic fluid composition
AssigneeThe Lubrizol Corporation
InventorsDaniel J. Knapton, David Cressey, Daniel C. Visger
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Abstract
A hydraulic fluid includes an oil of lubricating viscosity and at least 2 wt. % of an ester of a carboxy group-containing interpolymer comprising units derived from a vinyl aromatic monomer and units derived from a carboxylic acid monomer. The interpolymer also contains nitrogen functionality. The hydraulic fluid is at least substantially free of polyacrylates and polymethacrylates.
Claims32
A hydraulic fluid comprising:
- (a) an oil of lubricating viscosity;
- and
- (b) at least 2 wt. % of an ester of a carboxy group-containing interpolymer comprising units derived from a vinyl aromatic monomer and units derived from a carboxylic acid monomer, the interpolymer also comprising nitrogen functionality, the ester of the carboxy group-containing interpolymer having a weight average molecular weight of 20,000 to 200,000, the ester of a carboxy group-containing interpolymer including up to 0.4 wt. % nitrogen;
- and
- wherein the hydraulic fluid is at least substantially free of polyacrylates and polymethacrylates that contain, in total, at least 30 mol. % of at least one of acrylate and methacrylate units and have a weight-average molecular weight of at least 1500, such that said polyacrylates and polymethacrylates, in total, amount to no more than 0.3 wt. % of the hydraulic fluid.
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Dependencies are inferred from the claim text.