Metallocene Catalyst System for Polyolefin Internal Unsaturation
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Solution Overview
Problem
Current olefin polymerization catalyst systems struggle to produce polymers with specific and balanced properties, such as high molecular weight, increased comonomer incorporation, low long chain branching, and high internal unsaturation structures.
Innovation Solution
A process involving a catalyst system comprising a bis-cyclopentadienyl metallocene compound and an activator, where the metallocene compound generates hydrogen during polymerization, resulting in polymers with internal unsaturation of 50% or more, a melt index of 20 dg/min or less, and a g′vis of 0.95 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional olefin polymerization catalyst systems are used, then polymer production is achieved, but the polymer properties are not balanced (cannot simultaneously achieve high molecular weight, increased comonomer incorporation, low long chain branching, and high internal unsaturation structures)
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst system composition (using metallocene catalyst with specific activators), temperature (70-90°C), pressure (5-20 bar), and monomer ratios to achieve simultaneous optimization of multiple polymer properties including high molecular weight, increased comonomer incorporation, low long chain branching, and high internal unsaturation structures
Solution Approach 2:
The patent uses a composite catalyst system combining metallocene catalyst compounds with specific activators (alumoxane or non-coordinating anion activators) to create a synergistic system that enables control over multiple polymer properties simultaneously, achieving balanced polymer characteristics that cannot be obtained with conventional single-component catalysts
2Strength
If high molecular weight polymers are produced, then polymer strength is improved, but internal unsaturation structures decrease
Solution Approach 1:
The patent changes the polymerization parameters including temperature (70-90°C), pressure (5-20 bar), and catalyst system composition to achieve a unique condition where both high molecular weight (indicating strength) and high internal unsaturation structures (50% or more) are simultaneously obtained, resolving the typical trade-off between these properties
3Adaptability or versatility
If comonomer incorporation is increased, then polymer flexibility is improved, but long chain branching increases
Solution Approach 1:
The patent optimizes the comonomer feed ratio (1:4 to 1:10 monomer to comonomer), temperature (70-90°C), and catalyst system to achieve increased comonomer incorporation while simultaneously reducing long chain branching content to 5% or less, resolving the typical positive correlation between these two parameters
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 effectively produces polymers with high internal unsaturation, controlled molecular weight, and reduced long chain branching, enhancing the polymer's properties and commercial viability.
Implementation Method 1
contacting olefin monomers with a catalyst system comprising an activator and a bis-cyclopentadienyl metallocene compound
Data Source
AI summary
This invention relates to a process to polymerize olefins, particularly to produce ethylene polymers with internal unsaturation structures.