Viscosity index improver

摘要

A viscosity index improver which contains a polymer dispersion comprising: a polyolefin having a weight average molecular weight of 10,000 to 500,000, a dispersant comprising a reaction product of an ethylenically unsaturated dicarboxylic acid added polyolefin with a carboxylic acid-reactive compound selected from the group consisting of an amine, a ketimine compound, an alcohol and an isocyanate compound and an organic liquid medium comprising a liquid phenolic derivative selected from the group consisiting of an alkyl phenol and an alkyl salicylate.