Polymeric viscosity index additive and oil composition comprising the same
AssigneeShell Oil Company
InventorsRobert B. Rhodes, Arthur R. Bean
Life of this patent
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Abstract
A star-shaped polymer useful as a polymeric VI improver comprising at least one arm which is a block copolymer containing a cunjugated diolefin block and a monoalkenyl aromatic hydrocarbon block and a plurality of arms which are either a homopolymer of a conjugated diolefin or a copolymer of two or more conjugated diolefin or a copolymer of two or more conjugated diolefins. Oil compositions comprising star-shaped VI improvers of this type exhibit relativelylow HTHSR viscosities, and hence, improved fuel efficients when used in automotive applications. Oil compositions comprising star-shaped VI improvers of this type also exhibit improved low temperature pumpability.
Claims27
A lubricating oil composition comprising a lubricating oil and a selectively hydrogenated star-shaped polymer comprising at least one arm of a block copolymer containing a single monoalkenyl aromatic hydrocarbon block and a single block having conjugated diene monomer units and a plurality of arms of a conjugated diene homopolymer or copolymer and a poly(polyalkenyl coupling agent) nucleus, said polymer containing from about 6 to about 13 total arms as determined by gel permeation chromatography on a styrene scale and one block copolymer arm, on average, for from about 1 to about 10 conjugated diolefin homopolymer or copolymer arms, the molecular weight of the monoalkenyl aromatic hydrocarbon block being from about 0.65 to about 7.5 times the molecular weight of the conjugated diene block in said block copolymer and the molecular weight of the conjugated diene block of the block copolymer being from about 0.8 to about 1.2 times the molecular weight of the conjugated diene homopolymer or copolymer blocks.
A lubricating oil composition comprising a lubricating oil and a selectively hydrogenated star-shaped polymer comprising at least one arm of a block copolymer containing a single monoalkenyl aromatic hydrocarbon block and a single block having conjugated diene monomer units and a plurality of arms of a conjugated diene homopolymer or copolymer and a poly(polyalkenyl coupling agent) nucleus, said polymer containing from about 6 to about 13 total arms as determined by (GPC) on a styrene scale and one block copolymer arm, on average, for from about 1 to about 10 conjugated diolefin homopolymer or copolymer arms, the molecular weight of the monoalkenyl aromatic hydrocarbon block being from about 0.7 to about 5.0 times the molecular weight of the conjugated diene block in said block copolymer and the molecular weight of the conjugated diene block of the block copolymer being from about 0.8 to about 1.2 times the weight average molecular weight of the conjugated diene homopolymer or copolymer blocks.
A lubricating oil composition comprising a lubricating oil and a selectively hydrogenated star-shaped polymer comprising at least one arm of a block copolymer containing a single monoalkenyl aromatic hydrocarbon block and a single block having conjugated diene monomer units and a plurality of arms of a conjugated diene homopolymer or copolymer and a poly(polyalkenyl coupling agent) nucleus, said polymer containing from about 7 to about 9 total arms as determined by (GPC) on a styrene scale and one block copolymer arm, on average, for from about 1 to about 10 conjugated diolefin homopolymer or copolymer arms, the molecular weight of the monoalkenyl aromatic hydrocarbon block being from about 0.8 to about 2.5 times the molecular weight of the conjugated diene block in said block copolymer and the molecular weight of the conjugated diene block of the block copolymer being from about 0.8 to about 1.2 times the molecular weight of the conjugated diene homopolymer or copolymer blocks.
Dependencies are inferred from the claim text.