| 摘要 |
A dispersant viscosity index improver linear diblock copolymer or radial or star block copolymer, wherein the linear diblock copolymer and each arm of the radial or star block copolymer, respectively, has an overall number average molecular weight of 7500 to 250,000 and comprises a block of a conjugated diene having a number average molecular weight of 5000 to 200,000 and a block of a vinyl aromatic hydrocarbon having a number average molecular weight of 2500 to 100,000, the copolymer having a vinyl aromatic hydrocarbon content of 5 to 50 weight percent, wherein 5 to 10 N-vinyl imidazole functional groups per polymer chain have been grafted on to the copolymer, a process for producing and lubricating oil compositions and additive concentrates containing such dispersant viscosity index improvers. |
