Patent ID: 7371713

Claim:
A method of making a dispersant viscosity index improver, comprising the steps of: A. providing (i) a graftable polyolefin, (ii) a reaction product of an acylating agent having at least one point of ethylenic unsaturation and an amine, wherein the amine is selected from the group consisting of primary amines and secondary amines, and wherein the reaction product is provided in an amount sufficient for a molar ratio of reaction product to polyolefin of at least about 1:1, and (iii) an initiator in an amount sufficient to graft at least about 1 mole of the reaction product per mole of the polyolefin; B. forming a polyolefin mixture comprising the polyolefin and a solvent; C. adding the reaction product to the polyolefin mixture; D. adding the initiator to the polyolefin mixture; E. heating the polyolefin mixture to at least the initiation temperature of the initiator; thereby forming a graft copolymer having a molar ratio of grafted reaction product to polyolefin of at least about 0.5:1, in which method graftable, ethylenically unsaturated, aliphatic or aromatic nitrogen- and oxygen-containing compounds in the reaction product are not recovered from the reaction product before carrying out the grafting reaction.