Ethylene-Propylene Copolymers Shear Stability Low Temperature
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Solution Overview
Problem
Current commercial viscosity modifiers for lubricant oils, such as ethylene-propylene copolymers, face limitations in low temperature properties and shear stability, necessitating the development of novel compositions with improved fuel economy and viscosity index performance.
Innovation Solution
The synthesis of ethylene-propylene copolymers using pyridyldiamido catalysts and a chain transfer agent, which results in polymers with specific molecular weight and ethylene content ranges, enhancing their performance as viscosity modifiers by improving thickening efficiency and shear stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ethylene-propylene copolymers are used as viscosity modifiers, then thickening efficiency is achieved, but low temperature properties and shear stability are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling polymerization conditions including catalyst type (pyridyldiamido), monomer ratios (ethylene content 30-70 wt%), comonomer selection (C3-C20 alpha-olefins), and chain transfer agents to achieve optimal molecular weight (50,000-500,000 g/mol) and comonomer distribution that simultaneously improve shear stability and low temperature properties
Solution Approach 2:
The invention creates a composite polymer structure by copolymerizing ethylene with C3-C20 alpha-olefins in specific sequences and ratios, producing a copolymer that combines the benefits of ethylene (shear stability) with the low-temperature flexibility of alpha-olefin comonomers, achieving both improved shear stability and low temperature properties
2Quantity of substance
If polymer molecular weight is increased to improve thickening efficiency, then viscosity modification performance improves, but shear stability decreases
Solution Approach 1:
The patent optimizes the molecular weight parameter to a specific range (50,000-500,000 g/mol, preferably 100,000-300,000 g/mol) achieved through controlled polymerization conditions including catalyst selection and chain transfer agent usage, which balances thickening efficiency with shear stability by preventing excessive chain entanglement while maintaining sufficient polymer chain length for effective viscosity modification
3Reliability
If ethylene content in copolymer is increased to improve shear stability, then low temperature properties deteriorate
Solution Approach 1:
The patent optimizes the ethylene content parameter to a balanced range (30-70 wt%, preferably 40-60 wt%) through controlled polymerization conditions, which provides sufficient ethylene for shear stability while incorporating enough alpha-olefin comonomer (30-70 wt%) to maintain low temperature flexibility and prevent excessive crystallinity that would harm low temperature properties
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 resulting copolymers exhibit improved low temperature properties, increased shear stability, and better compatibility with lower viscosity base oils, leading to enhanced viscometric performance across a wide temperature range.
Implementation Method 1
contacting ethylene and one or more C3 to C20 alpha-olefins with a catalyst system comprising an activator, a chain transfer agent, and a pyridyldiamido transition metal complex
Data Source
AI summary
In some embodiments, ethylene-propylene random copolymers as viscosity modifiers were synthesized with pyridyldiamido catalyst systems and a chain transfer agent. In some embodiments, the present disclosure provides for ethylene-propylene random copolymers having an ethylene content between about 45 wt % and about 55 wt %. In some embodiments, the ethylene-propylene random copolymer is used as a viscosity modifier in a lubricating composition and a fuel composition.