US Patent 10017709 Multiple function dispersant viscosity index improver

The present invention provides a multiple function dispersant viscosity index improver, a method of making the multiple function dispersant viscosity index improver, and a lubricating oil comprising the multiple function dispersant viscosity index improver. The multiple function dispersant viscosity index improver comprises two different functional groups, each directly grafted to a polymer backbone having graftable sites. The first functional group comprises the reaction product of an acylating agent and a first amine, the first amine comprising an aromatic primary amine, and the second functional group comprises the reaction product of an acylating agent and a second amine, the second amine comprising an aliphatic primary amine. The first functional group provides the dispersant viscosity index improver with soot handling performance attributes and the second functional group provides the dispersant viscosity index improver with sludge and varnish control performance attributes.