Chromium Metallocene Catalyst for Olefin Polymerization
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Solution Overview
Problem
There is a need for new and improved catalyst systems for the polymerization of olefins that can achieve specific polymer properties such as impact resistance without compromising processability.
Innovation Solution
A catalyst system comprising a chromium metallocene catalyst compound represented by Formula I, an activator, and an optional support, where the catalyst compound is used to polymerize olefins, with the formula including a bridging group, phosphorus, and specific hydrocarbyl and heteroatom groups, and the process involves contacting the catalyst compound with an activator and monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chromium oxide or chromocene catalysts are used for olefin polymerization, then polymer production is achieved, but the resulting polymers lack specific properties such as impact resistance while maintaining processability
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the chromium catalyst through specific ligand coordination (phosphorus-containing ligands with defined R groups) and oxidation state control (Cr(III) vs Cr(II)). These parameter changes in catalyst structure enable precise control over polymer microstructure, achieving both impact resistance and processability in the resulting polyethylene
Solution Approach 2:
The patent implements local quality by creating catalysts with specific localized structural features - particularly the phosphorus-containing ligands with various R groups (hydrocarbyl, heteroatom, substituted groups) coordinated to the chromium center. This localized structural modification at the catalyst active site produces polymers with specific local microstructural characteristics that confer both impact resistance and processability
2Reliability
If new chromium metallocene catalyst compounds with specific structures are used, then polymers with enhanced impact resistance are produced, but catalyst system complexity increases
Solution Approach 1:
The patent applies composite materials by creating chromium catalysts that combine multiple ligand types - cyclopentadienyl or indenyl ligands combined with phosphorus-containing ligands (PR2, P(R)NR'2, or P(R)OP(R'')R'''). This composite ligand structure around the chromium center produces polymers with enhanced impact resistance while the modular nature of the composite catalyst allows systematic variation to optimize performance
Solution Approach 2:
The patent implements segmentation by dividing the catalyst structure into distinct functional segments: the chromium metal center, the cyclopentadienyl/indenyl ligand framework, and the phosphorus-containing ligand with variable R groups. This segmented structure allows independent optimization of each component's contribution to polymer properties, achieving impact resistance through specific phosphorus ligand configurations
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 system effectively produces polymers with enhanced impact resistance while maintaining processability, achieving specific polymer properties through the use of the chromium metallocene catalyst compound and activator in the polymerization process.
Implementation Method 1
a catalyst system comprising activator, optional support, catalyst compound represented by Formula I and a process to polymerize olefins
Data Source
AI summary
This invention relates to a catalyst system comprising a half sandwich chromocene compound featuring a tethered P-donor, with an activator and optional supportation on silica which produces ethylene homopolymer or copolymer.