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AssigneeExxon Research & Engineering Co.
InventorsJohn B. Gardiner, James Zielinski, Robert L. Elliott, Stanley J. Brois
Estimating the term…
Oil-soluble, derivatized ethylene copolymers derived from about 2 to 98 wt. % ethylene, and one or more C.sub.3 to C.sub.28 alpha-olefins, e.g. propylene, which are grafted, preferably solution-grafted under an inert atmosphere and at elevated temperatures and in the presence of a high-temperature decomposable free-radical initiator, with an ethylenically-unsaturated dicarboxylic acid material and thereafter reacted with a polyamine having at least two primary amine groups, e.g. an alkylene polyamine such as diethylene triamine, to form carboxyl-grafted polymeric imide, usually maleimide, derivatives are reacted with an anhydride of a C.sub.1 -C.sub.30 hydrocarbyl substituted acid, preferably acetic anhydride, to yield an oil-soluble stable amide of said polyamine whereby oil solutions of said amide derivative are characterized by minimal viscosity change over an extended period of time. Useful number average molecular weight (M.sub.n) of said copolymers range from about 700 to 500,000; however, if the molecular weight is from 10,000 to 500,000 then these copolymers are also useful as multifunctional viscosity index improvers.
A lubricating oil composition comprising a major amount of a lubricating oil having dissolved therein at least a viscosity index improving amount of an oil-soluble ethylene polymeric viscosity index improver having dispersancy properties and containing in the range of from about 0.001 to 8 wt. % of nitrogen, which improver has been formed by:
A process for improving the viscosity stability of an oil additive concentrate consisting essentially of a hydrocarbon solvent and from 0.1 to 50 wt. %, based on the total weight of said concentrate, of an imidated grafted ethylene/C.sub.3 -C.sub.28 .alpha.-olefin copolymeric viscosity index improver having a molecular weight (M.sub.n) of 700 to 500,000 and a M.sub.w /M.sub.n ratio of less than 7, said viscosity index improver having dispersancy properties and being formed by grafting maleic anhydride onto an ethylene copolymer comprising about 30 to 80 wt. % ethylene and about 20 to 70 wt. % of said C.sub.3 -C.sub.28 .alpha.-olefin, followed by reaction of said maleic anhydride moieties with a polyamine of 2 to 60 carbon atoms and 2 to 12 nitrogen atoms and having at least two primary amine groups, wherein at least some of said primary amine groups remain unreacted, said process comprising the step of reacting said concentrate with a hydrocarbyl substituted acid anhydride having from about 2 to 30 carbons by adding said acid anhydride in an amount to provide an excess of at least about 5% based on the primary amino concentration in said concentrate and maintaining said concentrate at a temperature ranging from about 50.degree. to about 250.degree. C. and for a period of 0.25 to 8 hours and thereafter removing all unreacted anhydride and byproducts of said reaction while maintaining said concentrate under an inert and water-free environment.
Dependencies are inferred from the claim text.