Cyclic Cationic Activator for High Melting Point Polypropylene
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Solution Overview
Problem
Current olefin polymerization catalyst systems face challenges in achieving high melting point and molecular weight polymers while maintaining polymer properties, particularly in propylene polymerization, where increased conversion often results in decreased molecular weight and specific polymer properties.
Innovation Solution
A catalyst system comprising a transition metal compound and a non-coordinating anion activator with a specific cyclic cation structure, which activates the transition metal compound to maintain or increase weight average molecular weight during polymerization, resulting in polymers with high melting points and improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If increased propylene conversion is achieved in polymerization, then productivity is improved, but molecular weight decreases
Solution Approach 1:
The patent applies parameter changes by modifying the activator structure from conventional types to cyclic cationic structures with specific ring sizes (3-10 membered non-aromatic rings). This structural parameter change in the activator enables the catalyst system to maintain high molecular weight even at high propylene conversion levels, resolving the trade-off between productivity and molecular weight
2Manufacturing precision
If high melting point polymers are produced, then polymer quality is improved, but catalyst system complexity increases
Solution Approach 1:
The patent achieves high melting point polymers by changing the chemical parameter of the activator to a cyclic cationic structure with specific ring configurations. This parameter change in the activator structure directly influences polymer crystallinity and melting point while maintaining reasonable catalyst system complexity through the use of well-defined cyclic structures
Solution Approach 2:
The patent employs a composite catalyst system combining transition metal compounds with cyclic cationic activators and non-coordinating anions. This composite approach enables control over polymer melting point through the synergistic interaction of different components, achieving high melting point polymers without excessive complexity in any single component
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 achieves polymers with high melting points and molecular weights, along with improved properties such as pellet stability, impact resistance, and heat seal properties, while maintaining or increasing molecular weight with increasing monomer conversion.
Implementation Method 1
a catalyst system comprising a transition metal compound and an activator... activates the transition metal compound
Data Source
AI summary
Provided are catalyst systems, processes for polymerizing one or more olefins, polymers resulting therefrom, and articles prepared from such polymers. The processes comprise contacting under polymerization conditions one or more olefin monomers, preferably propylene, with a catalyst system comprising a transition metal compound and an activator of the formula (1) or (2) as described herein. The polymer compositions described herein exhibit advantageously narrow composition distributions and high melting points in comparison to conventional polymers having the same comonomer content. The polymers described herein exhibit improved properties, e.g., pellet stability, impact properties, heat seal properties, and structural integrity in film and fabricated parts applications.