VISCOSITY INDEX IMPROVERS FOR LUBRICATING OIL COMPOSITIONS

摘要

VISCOSITY INDEX IMPROVERS FOR LUBRICATING OIL COMPOSITIONS Polymers suitable for use as a viscosity index improver for lubricating oil compositions including hydrogenated linear polymers characterized by the formula:D'-PA-D";and hydrogenated star polymerscharacterized by the formula:(D'-PA-D")„-X;wherein D' represents an "outer" block derived from diene having a number average molecular weight of from about 10,000 to about 120,000 daltons; PA represents a block derived from monoalkenylarene having a number average molecular weight of from about 10,000 to about 50,000 daltons; D" represents an inner random derivedfrom diene having a number average molecular weight of from about 5,000 to about 60,000 daltons; n represents the average number of arms per star polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms, and X represents a nucleus of a polyalkenyl coupling agent.No Figure