Bridged Hafnium Metallocene Catalysts for Olefin Polymerization
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Solution Overview
Problem
Current olefin polymerization catalyst systems lack the ability to produce polymers with high melting point, high molecular weights, and specific comonomer incorporation while maintaining vinyl chain ends and molecular weight, particularly 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 positions and a cyclic bridging group, used in combination with a non-coordinating anion activator for olefin polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional metallocene catalysts are used for olefin polymerization, then polymerization activity is achieved, but the ability to produce polymers with high melting point and high molecular weight is limited
Solution Approach 1:
The patent applies local quality by specifically substituting the indenyl ligands at the 4-position with alkyl or cycloalkyl groups while leaving other positions unchanged. This localized modification at specific positions of the ligand structure enables the catalyst to produce polymers with high melting points and high molecular weights, resolving the contradiction between achieving specific polymer properties and maintaining catalyst versatility.
Solution Approach 2:
The patent employs parameter changes by modifying the chemical structure of the indenyl ligands through substitution at the 4-position with various alkyl (C1-C10) or cycloalkyl groups. This structural parameter change in the catalyst directly influences the polymerization outcome, enabling the production of polymers with high melting points and high molecular weights that were not achievable with conventional catalysts.
2Manufacturing precision
If conventional metallocene catalysts are used, then polymerization occurs, but specific comonomer incorporation with maintained vinyl chain ends is difficult to achieve
Solution Approach 1:
The patent applies local quality by making specific substitutions at the 4-position of the indenyl ligands while keeping the rest of the catalyst structure relatively simple. This localized modification enables precise control over comonomer incorporation and vinyl chain end maintenance without requiring complex overall catalyst architecture, thus resolving the contradiction between manufacturing precision and device complexity.
3Manufacturing precision
If conventional catalyst systems are used, then polymerization activity is achieved, but increasing vinyl unsaturations at chain ends while maintaining molecular weight is limited
Solution Approach 1:
The patent employs parameter changes by substituting the indenyl ligands at the 4-position with alkyl or cycloalkyl groups, which modifies the steric and electronic parameters of the catalyst active site. This parameter change enables the catalyst to increase vinyl unsaturations at chain ends while simultaneously maintaining high molecular weight, resolving the contradiction between these two previously conflicting objectives.
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 solution enhances polymer properties by achieving high melting points, molecular weights, and comonomer incorporation, while maintaining or increasing vinyl chain ends and molecular weight, thereby improving the polymerization process.
Implementation Method 1
novel bridged hafnium transition metal metallocene catalyst compounds... for olefin polymerization
Data Source
Figure 1
AI summary
This invention relates to novel bridged a hafnium transition metal metallocene catalyst compounds having two indenyl ligands substituted at the 4 positions with a C1 to C10 alkyl, where the 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.