Polymer Composition Gel Prevention via Hydrogen Feed Control

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Solution Overview

Problem

Lubricating oils with high ethylene content copolymers tend to aggregate and form gels at low temperatures, leading to undesirable viscosity profiles in lubricating oils, which affects their performance as viscosity index improvers.

Innovation Solution

A process for producing polymer compositions with reduced or no gel formation by adjusting hydrogen feed concentrations in polymerization reaction zones, using metallocene catalysts to combine ethylene-α-olefin copolymers with varying ethylene content, resulting in a semi-crystalline and amorphous copolymer blend that maintains rheological stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If higher ethylene content copolymers are used to promote oil thickening and shear stability, then thickening efficiency and shear stability are improved, but the copolymers aggregate at low temperatures leading to gel formation and undesirable viscosity profiles

Engineering Contradiction:
Improveshear stabilityVSAvoidgel formation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The copolymer is segmented into distinct compositional regions (ethylene-rich crystalline domains and alpha-olefin-rich amorphous domains) through controlled polymerization. This segmentation allows the ethylene-rich segments to provide shear stability while the alpha-olefin-rich segments prevent aggregation at low temperatures, resolving the contradiction between shear stability and gel formation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the copolymer chain have different local compositions and properties. The ethylene-rich regions provide crystalline structure for shear stability, while the alpha-olefin-rich regions provide amorphous character for low-temperature flexibility. This local quality variation enables the polymer to simultaneously achieve shear stability and prevent gel formation

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If higher ethylene content copolymers are used to increase viscosity at operating temperatures, then thickening efficiency is improved, but low temperature viscosity performance deteriorates due to aggregation

Engineering Contradiction:
Improvethickening efficiencyVSAvoidlow temperature viscosity performance
Core Design Contradiction:
Quantity of substanceVSTemperature

Solution Approach 1:

The copolymer acts as a composite material with crystalline ethylene-rich domains dispersed in an amorphous alpha-olefin-rich matrix. The crystalline domains provide thickening efficiency at operating temperatures, while the amorphous matrix prevents aggregation and maintains low-temperature viscosity performance

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional Ziegler-Natta catalysts are used to produce copolymers, then manufacturing process is established, but the copolymers still form gels in lubricating oils at low temperatures

Engineering Contradiction:
Improvemanufacturing processVSAvoidgel formation in lubricating oils
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The polymerization parameters are changed by using metallocene catalysts instead of conventional Ziegler-Natta catalysts, and by controlling hydrogen feed concentration and monomer ratios. These parameter changes produce copolymers with controlled composition distribution that prevent gel formation in lubricating oils while maintaining manufacturability

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The process produces polymer compositions that effectively prevent gel formation, enhancing thickening efficiency and shear stability, thereby improving the viscosity index and low-temperature performance of lubricating oils.

Implementation Method 1

the use of a synthesis process that employs metallocene-based catalysts in the polymerization process

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

adjusting the concentrations of the hydrogen feed(s) in the first and/or second polymerization reaction zones

Methodology Applied
Scientific EffectChain transfer:

Implementation Method 3

VI improving components, many of which are derived from ethylene-alpha-olefin copolymers, modify the rheological behavior of a lubricant to increase viscosity

Methodology Applied
Scientific EffectRheology modification:

Data Source

PatentUS9139794B2Process for the production of polymeric compositions useful as oil modifiers
Publication Date: 2015.09.22 EXXONMOBIL CHEMICAL PATENTS INC

AI summary

Provided are processes for making polymer compositions, especially those with reduced or no gel formation in lubricating oils as identified by rheological and visual gel tests and which are useful as viscosity modifiers. The processes described herein aim to achieve this objective by adjusting the concentrations of the hydrogen feed(s) in the first and/or second polymerization reaction zones, preferably such that (a) the hydrogen feed concentration in the first polymerization reaction zone is 0.0-1.0 wt %, based on total weight of feed(s) of hydrogen, ethylene monomer, α-olefin comonomer, and solvent into the first polymerization reaction zone, and/or (b) the hydrogen feed concentration in the second polymerization reaction zone is 0.0-0.5 wt %, based on total weight of feed(s) of hydrogen, ethylene monomer, α-olefin comonomer, and solvent into the second polymerization reaction zone.