Polymeric additives for fuels and lubricants

Claim 1

A process for preparing a lubricating oil concentrate of a viscosity index improver having sludge dispersing properties and a number average molecular weight in the range of about 10,000 to 250,000; comprising dissolving from 5 to 30 weight percent of ethylene copolymer comprising 30 to 80 wt. % ethylene and 20 to 70 wt. % C 3 to C 18 alpha-olefin in a mineral lubricating oil as solvent, maintaining said resulting copolymer-oil solution at a temperature of from about 100° C. to about 250° C. and under an inert atmosphere while admixing an ethylenically-unsaturated dicarboxylic acid material selected from the group consisting of maleic anhydride, maleic anhydride derivatives, maleic acid and fumaric acid, and a free-radical initiator having a boiling point in excess of about 100° C. into said solution, wherein the weight ratio of said dicarboxylic acid material to said initiator is about 1:1 to 30:1, and maintaining said temperature and inert atmosphere for about 0.1 to 12 hours to graft said acid material onto said ethylene copolymer and said solvent, without substantial molecular weight breakdown of said ethylene copolymer, and thereafter reacting carboxy groups of said grafted polymer with a polyfunctional material selected from the group consisting of polyamines having 3 to 20 carbon atoms and 2 to 12 nitrogen atoms, C 2 to C 30 polyols having 2 to 10 hydroxyl radicals, and C 2 to C 30 hydroxy amines having 1 to 6 hydroxy groups and 1 to 10 nitrogen atoms, to thereby form said lubricating oil concentrate.