Ethylene Copolymer Viscosity Modifier Agglomeration Control
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Solution Overview
Problem
Ethylene copolymers with low ethylene content and low molecular weight are difficult to produce and handle due to agglomeration issues, while those with high ethylene content have unacceptably low service temperatures and melting points, making them challenging for use as viscosity modifiers in lubricating oils.
Innovation Solution
A metallocene catalyst system is used to produce ethylene copolymers with specific molecular weight and melting point ranges, reducing agglomeration and improving low-temperature properties without compromising handling or melting point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low ethylene content EP copolymer is used as viscosity modifier for waxy base stock oils, then excellent low temperature properties and good thickening efficiency are achieved, but the copolymer is difficult to produce and handle due to agglomeration and cold flow issues
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene content within 40-55 wt.% range and molecular weight below 100,000 g/mol to achieve the optimal balance between low temperature properties and handling characteristics, transforming the copolymer from difficult-to-handle to processable while maintaining performance
Solution Approach 2:
The patent applies local quality by creating a specific molecular weight distribution with weight-average molecular weight below 100,000 g/mol, which provides different properties at different molecular levels - lower molecular weight portions prevent agglomeration while maintaining thickening efficiency
2Strength
If high ethylene content EP copolymer is used, then outstanding low temperature impact strength and flexibility are achieved, but the service temperature is unacceptably low due to low melting point
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene content within 40-55 wt.% range, avoiding both extremely low and extremely high ethylene content, to achieve the optimal balance between low temperature impact strength and service temperature, ensuring the copolymer maintains adequate melting point while preserving flexibility
3Reliability
If low molecular weight EP copolymer is used, then shear stability standards are met for motor oil formulations, but the copolymer has propensity to agglomerate and stick to finishing equipment
Solution Approach 1:
The patent applies parameter changes by setting the weight-average molecular weight below 100,000 g/mol, which is low enough to meet shear stability requirements but combined with specific ethylene content control to prevent excessive agglomeration, achieving both shear stability and reduced agglomeration
Solution Approach 2:
The patent converts the potential harm of low molecular weight (agglomeration tendency) into a benefit by carefully selecting the ethylene content range of 40-55 wt.%, which modifies the copolymer structure to reduce intermolecular interactions that cause agglomeration, thereby transforming a disadvantage into an acceptable property
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 solution enables the production of ethylene copolymers with improved crystallinity, reduced agglomeration, and enhanced melting points, addressing handling and performance issues in both low and high ethylene content ranges for use as viscosity modifiers.
Implementation Method 1
A metallocene catalyst system is used to produce ethylene copolymers with specific molecular weight and melting point ranges
Data Source
AI summary
Provided herein are ethylene copolymers, methods for making such copolymers, and compositions made from such copolymers. The ethylene copolymers have 70 wt. % to 85 wt. % of units derived from ethylene and at least 12 wt. % of units derived from at least one α-olefin having 3 to 20 carbon atoms. The copolymers preferably further have a weight-average molecular weight (Mw) ranging from about 50,000 to about 200,000 g/mol, melting point of at least 100° C., ratio of Mw/Mn of about 1.5 to about 3.5, a content of group 4 metals of no more than 25 ppm, and a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least 3. Such copolymers may be particularly useful as viscosity modifiers for lubricating oil compositions.