Bridged Metallocene Catalysts for High Molecular Weight Olefin Polymerization
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Solution Overview
Problem
Current metallocene compounds used for polymerizing olefins, such as propylene, face limitations in achieving high yields and producing polymers with very high molecular weights, particularly at elevated temperatures.
Innovation Solution
Development of bridged chiral bis(indenyl)metallocene compounds with specific substitutions at positions 2, 4, 5, and 6, combined with a catalyst system involving these compounds, alumoxanes, and organoaluminum compounds, to enhance polymerization efficiency and molecular weight of olefin polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional metallocene compounds are used for polymerizing olefins at elevated temperatures, then polymerization can proceed, but the yields are limited and molecular weights are not very high
Solution Approach 1:
The patent modifies the chemical structure parameters of metallocene compounds by introducing specific substituents at defined positions (2, 4, 5, 6) on the indenyl moieties. This structural parameter change creates a new class of compounds with enhanced catalytic activity and selectivity, enabling high polymerization yields and very high molecular weights even at elevated temperatures
Solution Approach 2:
The patent applies local quality by introducing specific functional groups and substituents at specific positions (2, 4, 5, 6) of the indenyl moieties. Each position has a tailored substituent that contributes specific electronic or steric effects, creating localized areas of enhanced reactivity and selectivity that collectively improve polymerization performance
2Reliability
If conventional metallocene compounds are used for polymerizing olefins, then polymerization occurs, but molecular weights are not very high
Solution Approach 1:
The patent changes the structural parameters of the metallocene compounds by introducing specific substituents at positions 2, 4, 5, and 6 on the indenyl moieties. This parameter modification creates a new class of compounds that maintain high catalytic activity while producing polymers with very high molecular weights
Solution Approach 2:
The patent creates a composite catalytic system combining the specially structured metallocene compound with alumoxane and organoaluminum compounds. This composite catalyst system synergistically enhances both polymerization yield and molecular weight, achieving performance levels not attainable with single-component catalysts
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 new metallocene compounds and catalyst system significantly improve polymerization yields and molecular weights of olefin polymers, including propylene, even at high temperatures, making them suitable for industrial applications.
Implementation Method 1
Metallocene compounds are well known in the art as catalyst components for the polymerization of olefins
Data Source
AI summary
A bridged metallocene compound of formula (I) wherein: M is a transition metal; X, is a hydrogen atom, a halogen atom, or a hydrocarbon group optionally containing heteroatoms; L is a divalent bridging group; R1 is a linear C1-C40 hydrocarbon radical optionally containing heteroatoms; T1 and T4 are a oxygen, sulfur atom or a C(R18)3 group; wherein R18, are hydrogen atoms or a C1-C40 hydrocarbon radical; T3 and T4 are C1-C40 hydrocarbon radicals; R4 is a hydrogen atom or a C1-C40 hydrocarbon radical; W is an aromatic 5 or 6 membered ring.