Aromatic diblock copolymers for lubricant and concentrate compositions and methods thereof

Abstract

A lubricant composition comprises (A) a major amount of an oil of lubricating viscosity and (B) a minor amount of a diblock copolymer comprising a poly(monovinyl aromatic hydrocarbon) block and a hydrogenated poly(conjugated diene) block where the diblock copolymer has a weight average molecular weight of 10,000 to 50,000 and a poly(monovinyl aromatic hydrocarbon) content of 5 to 45% by weight. A concentrate composition, a method for improving viscosity performance of a lubricant composition for an internal combustion engine, and a method for lubricating an internal combustion engine comprise the diblock copolymer which is especially useful for reducing soot-induced viscosity increase in a compression-ignited internal combustion engine equipped with an exhaust gas recirculation system.

Dependencies are inferred from the claim text.