Multifunctional viscosity index improver derived from polyamine containing one primary amine group and at least one tertiary amine group and degraded ethylene copolymer

Abstract

A multifunctional viscosity index improver for lubricating oils comprising reaction product of: (i) (a) degraded ethylene-alpha-olefin copolymer obtained by degrading undegraded copolymer of ethylene and at least one other alpha-olefin monomer, said undegraded copolymer comprising intramolecularly heterogeneous copolymer chain containing at least one crystallizable segment of methylene units and at least one low crystallinity ethylene-alpha-olefin copolymer segment, wherein said at least one crystallizable segment comprises at least about 10 weight percent of said copolymer chain and contains at least about 57 weight percent of said copolymer chain and contains at least about 57 weight percent ethylene, wherein said low crystallinity segment contains not greater than about 53 weight percent ethylene, and wherein said copolymer has a molecular weight distribution characterized by at least one of a ratio of M.sub.w /M.sub.n of less than 2 and a ratio of M.sub.z /M.sub.w of less than 1.8 and wherein at least two portions of an individual intramolecularly heterogeneous chain, each portion comprising at least 5 weight percent of said chain, differ in composition from one another by at least 7 weight percent ethylene; said degraded copolymer grafted with (b) ethylenically monounsaturated carboxylic acid material having 1 to 2 carboxylic acid groups or anhydride group to form grafted degraded ethylene copolymer; and (ii) at least one polyamine containing one primary amino group and at least one tertiary amino group.

Dependencies are inferred from the claim text.