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US 5,401,427 AGranted
Viscosity index improver
AssigneeExxon Chemical Patents Inc.
InventorsDavid Y. Chung, Mark J. Struglinski
Life of this patent
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Abstract
Degraded molecular weight copolymers of ethylene alpha-olefin are provided. The ethylene alpha-olefin copolymers, before degradation, are characterized by having a narrow molecular weight distribution and are comprised of intramolecularly heterogeneous and intermolecularly homogeneous copolymer chains. The degraded copolymers are useful as viscosity index improvers for oils.
Claims35
A grafted degraded ethylene-.alpha.-olefin copolymer comprising reaction product of:
- (i) molecular weight 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 chains 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 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 ethylene-alpha-olefin copolymer grafted with
- (ii) unsaturated carboxylic acid material.
Dependencies are inferred from the claim text.