Includes the adjustment, and that star polymer of the star polymer and that star polymer the lubricating constituent

摘要

The invention provides star-shaped polymers comprising a plurality of arms of a block copolymer containing a single monoalkenyl aromatic hydrocarbon block and a single conjugated diolefin block having hydrogenated conjugated diene monomer units and a poly(polyalkenyl coupling agent) nucleus, said polymer containing from 6 to 13 total arms as determined by gel permeation chromatography using monoalkenyl aromatic equivalent molecular weights, the monoalkenyl aromatic equivalent peak molecular weight of the monoalkenyl aromatic hydrocarbon polymer block being within the range from 600 to 120,000 and the peak molecular weight of the conjugated diolefin block being within the range from 8,000 to 180,000 with the proviso that the weight ratio of monoalkenyl aromatic hydrocarbon to conjugated diolefin in the polymer be within the range from 0.05:1 to 1.5:1; a process for their preparation, and lubricating oil compositions containing such polymers.