Bridged Hafnium Metallocene Catalysts for Olefin Polymerization
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Solution Overview
Problem
Current olefin polymerization catalyst systems fail to achieve specific polymer properties such as high melting point, high molecular weights, and optimal comonomer incorporation without compromising polymer properties, particularly in increasing vinyl unsaturations at chain ends.
Innovation Solution
Development of novel bridged hafnium transition metal metallocene catalyst compounds with indenyl ligands substituted at the 4 and optionally 7 positions, combined with a non-coordinating anion activator, for the polymerization of ethylene and cyclic olefins, which enhances catalyst activity and comonomer distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metallocene catalysts are used for olefin polymerization, then polymerization can be achieved, but the catalysts fail to achieve high molecular weights and optimal comonomer incorporation without compromising polymer properties
Solution Approach 1:
The patent applies local quality by introducing specific substituents at defined positions (4 and 7 positions) on the indenyl ligands of the metallocene catalyst. This localized modification of the catalyst structure enables precise control over polymerization characteristics, achieving high molecular weights and optimal comonomer incorporation while maintaining desired polymer properties such as melting point and viscosity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the substituents at the 4 and 7 positions of the indenyl ligands. By changing the chemical parameters of the catalyst structure (different substituents, their positions and types), the invention optimizes the balance between catalyst activity and polymer property control, enabling high molecular weight polymerization with controlled comonomer distribution.
2Productivity
If catalyst activity is increased to improve productivity, then polymerization rate increases, but vinyl unsaturations at chain ends increase compromising polymer properties
Solution Approach 1:
The patent applies local quality by placing specific substituents at the 4 and 7 positions of the indenyl ligands, which locally modifies the electronic and steric properties of the catalyst active site. This localized modification enables the catalyst to maintain high activity while selectively controlling the polymerization mechanism to minimize vinyl unsaturations at chain ends, thus preserving polymer property consistency.
Solution Approach 2:
The patent uses composite materials by combining the metallocene catalyst core with specifically designed substituted indenyl ligands. This composite catalyst structure integrates the high activity of the metallocene center with the property-controlling influence of the substituted ligands, achieving both high productivity and high polymer property consistency by suppressing unwanted side reactions that create vinyl unsaturations.
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 produces ethylene-cyclic-olefin copolymers with improved molecular weights, melting points, and increased vinyl unsaturations at chain ends, while maintaining or enhancing polymer properties.
Implementation Method 1
novel bridged hafnium transition metal metallocene catalyst compounds... for the polymerization of ethylene and cyclic olefins
Data Source
AI summary
This invention relates to novel bridged a hafnium transition metal metallocene catalyst compounds having two indenyl ligands substituted at the 4 position, preferably 4 and 7 positions, with a C1 to C10 alkyl, where the 2 and 3 positions are hydrogen (assuming the bridge position is counted as the one position) and the bridging atom is carbon or silicon which is incorporated into a cyclic group comprising 3, 4, 5, or 6 silicon and/or carbon atoms that make up the cyclic ring.