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LUBRICANT COMPOSITIONS COMPRISING ETHYLENE PROPYLENE COPOLYMERS AND METHODS FOR MAKING THEM

IP.com Disclosure Number: IPCOM000242102D
Publication Date: 2015-Jun-18

Publishing Venue

The IP.com Prior Art Database

Related People

ExxonMobil Chemical Company: OWNER

Abstract

Described herein are ethylene propylene copolymers (“EP copolymers”) useful as rheology modifiers. The EP copolymer may be a blocky EP copolymers that has semicrystalline ethylene sequences and amorphous or low crystallinity propylene sequences. The polymers may be prepared using metallocene-based catalyst systems and preferably without the use of a chain shuttling agent. The polymers have higher melting temperatures than previously known random copolymers or block copolymers prepared with chain shuttling agents.

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LUBRICANT COMPOSITIONS COMPRISING ETHYLENE PROPYLENE

COPOLYMERS AND METHODS FOR MAKING THEM

ABSTRACT
[0001]Described herein are ethylene propylene copolymers ("EP copolymers") useful as rheology modifiers. The EP copolymer may be a blocky EP copolymers that has semicrystalline ethylene sequences and amorphous or low crystallinity propylene sequences. The polymers may be prepared using metallocene-based catalyst systems and preferably without the use of a chain shuttling agent. The polymers have higher melting temperatures than previously known random copolymers or block copolymers prepared with chain shuttling agents.

RELATED PUBLICATIONS
[0002]This publication is related to U.S. Patent Application Publication No. 2013/0281340 and PCT Patent Application Publication No. WO 2013/158253, the disclosures of which are incorporated herein by reference.

BACKGROUND
[0003]Lubrication fluids are applied between moving surfaces to reduce friction, thereby improving efficiency and reducing wear. Lubrication fluids also often function to dissipate the heat generated by moving surfaces.

[0004]One type of lubrication fluid is a petroleum-based lubrication oil used for internal combustion engines. Lubrication oils contain additives that help the lubrication oil exhibit a certain viscosity at a given temperature. In general, the viscosity of lubrication oils and fluids is inversely dependent upon temperature. When the temperature of a lubrication fluid is increased, the viscosity generally decreases, and when the temperature is decreased, the viscosity generally increases. For internal combustion engines, for example, it is desirable to have a lower viscosity at low temperatures to facilitate engine starting during cold weather, and a higher viscosity at higher ambient temperatures when lubrication properties typically decline.

[0005]Additives for lubrication fluids and oils include rheology modifiers, such as viscosity index (VI) improvers. VI improvers, many of which are derived from ethylene-alpha-olefin copolymers, modify the rheological behavior of a lubricant to increase viscosity and promote a more constant viscosity over the range of temperatures at which the lubricant is used. Higher ethylene content copolymers efficiently promote oil thickening and shear stability. However, higher ethylene content copolymers also tend to flocculate or aggregate in oil formulations leading to very viscous and potentially solid formulations. Flocculation

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typically happens at ambient or subambient conditions of controlled and quiescent cooling. This deleterious property of otherwise advantageous higher ethylene content viscosity improvers is measured by low temperature solution rheology. Various remedies have been proposed for these higher ethylene content copolymer formulations to overcome or mitigate the propensity towards the formation of high viscosity flocculated materials.

[0006]One proposed solution is the use of blends of amorp...