Cyclopropyl Metallocene Catalysts for Olefin Polymerization
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Solution Overview
Problem
There is a need for new and improved catalyst systems for olefin polymerization to achieve specific polymer properties such as high melting point, high molecular weights, increased conversion, or altered comonomer distribution without compromising polymer quality.
Innovation Solution
Development of novel group 3, 4, or 5 transition metal metallocene catalyst compounds with cyclopropyl-substituted arenyl ligands, specifically cyclopropyl-substituted indenyl ligands, used in conjunction with activators for olefin polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metallocene catalysts are used for olefin polymerization, then basic polymer properties are achieved, but polymer quality and specific properties such as melting point and molecular weight cannot be optimized
Solution Approach 1:
The patent applies local quality by introducing cyclopropyl substituents at specific positions (2-position or 4-position) on the indenyl ligand structure. This localized substitution modifies the electronic and steric properties of the catalyst active site, enabling control over polymer properties such as melting point and molecular weight while maintaining catalyst functionality. The cyclopropyl group at a specific location creates distinct polymer characteristics without altering the entire catalyst structure.
Solution Approach 2:
The patent employs parameter changes by varying the substitution pattern (2-cyclopropyl vs 4-cyclopropyl), the metal center (Zr, Hf, Ti), and the combination with different activators to optimize polymer properties. These parameter modifications allow tuning of catalyst activity, polymer molecular weight, and melting point, achieving enhanced polymer quality and specific property control.
2Reliability
If new catalyst systems are developed to achieve specific polymer properties, then polymer quality and properties are improved, but catalyst complexity increases
Solution Approach 1:
The patent creates composite catalyst systems by combining cyclopropyl-substituted indenyl ligands with group 4 transition metals (Zr, Hf, Ti) and coordinating activators. This composite structure integrates multiple functional components - the cyclopropyl-indenyl provides structural framework and electronic properties, the transition metal provides catalytic activity, and the activator enables catalyst formation. The synergistic combination achieves enhanced polymer properties while maintaining reasonable catalyst complexity through rational design.
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 catalyst systems enable the production of polymers with enhanced properties by effectively controlling polymerization processes, improving melting points and molecular weights while maintaining polymer quality.
Implementation Method 1
Catalysts for olefin polymerization are often based on metallocenes as catalyst precursors, which are activated either with an alumoxane or with an activator containing a non-coordinating anion
Data Source
AI summary
This invention relates to a novel group 2, 3 or 4 transition metal metallocene catalyst compound having at least one arenyl ligand substituted with: 1) a cyclopropyl group and, optionally, 2) at at least one other group, such as a hydrocarbyl, a heteroatom or a heteroatom containing group.