STAR POLYMER VISCOSITY INDEX IMPROVER FOR OIL LUBRICATING COMPOSITIONS

摘要

The present invention provides star polymers, useful as viscosity index improvers in oil compositions, having triblock copolymer arms of hydrogenated polyisoprene and polystyrene wherein the polystyrene is placed near the core of the star polymer to provide excellent low temperature performance and finishability as a polymer crumb; a process for their preparation; and lubricating oil compositions and lubricating oil concentrates containing them.