Metallocene Catalyst for Polymer Density and Melt Index Control
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Solution Overview
Problem
Current methods for adjusting polymer properties, such as melt index and density, are limited by the catalysts used, particularly as they often result in increased comonomer consumption and hydrogen generation, making it difficult to achieve desired polymer properties like constant density and lower melt indexes efficiently.
Innovation Solution
The use of a metallocene complex represented by Formula I, where each n-Pr is n-propyl and each X is independently CH3, Cl, Br, or F, which is activated and used to produce polymers with predetermined densities and melt indexes by reducing hydrogen and comonomer concentrations, thereby reducing comonomer consumption and achieving polymers with constant density and lower melt indexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional catalysts are used to adjust polymer properties, then polymer production is achieved, but comonomer consumption increases and hydrogen generation occurs, making it difficult to achieve constant density and lower melt indexes
Solution Approach 1:
The patent changes the chemical structure parameters of the metallocene catalyst by substituting specific groups (n-propyl, methyl, chloro, bromo, or fluoro) at defined positions on the cyclopentadienyl rings. This structural parameter change enables the catalyst to achieve constant density polymers with lower comonomer consumption while producing lower melt indexes, resolving the contradiction between density control precision and comonomer consumption.
2Manufacturing precision
If conventional catalysts are used to adjust polymer properties, then polymer production is achieved, but hydrogen generation occurs, making it difficult to achieve lower melt indexes efficiently
Solution Approach 1:
The patent modifies the catalyst's chemical parameters by introducing specific substituents (n-propyl, methyl, chloro, bromo, or fluoro groups) at predetermined positions on the metallocene structure. This parameter change enables the catalyst to produce polymers with lower melt indexes without generating hydrogen, thereby resolving the contradiction between melt index control and hydrogen generation.
3Productivity
If conventional metallocene complexes are used, then polymerization occurs, but the catalyst generates hydrogen during polymerization, preventing achievement of lower melt indexes
Solution Approach 1:
The patent changes the chemical composition parameters of the metallocene catalyst by substituting hydrogen atoms with n-propyl, methyl, chloro, bromo, or fluoro groups at specific positions. This parameter modification eliminates hydrogen generation during polymerization while maintaining productivity, allowing efficient production of polymers with lower melt indexes.
Solution Approach 2:
The patent converts the potential harm of hydrogen generation into a benefit by designing a catalyst structure where the substituents (n-propyl, methyl, chloro, bromo, or fluoro groups) prevent hydrogen evolution. This transforms the harmful effect into a beneficial feature, enabling the catalyst to simultaneously maintain high productivity and produce polymers with lower melt indexes without hydrogen generation.
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
This approach allows for the production of polymers with constant density and lower melt indexes while reducing comonomer consumption, which is economically advantageous and not achievable with other metallocene complexes that generate hydrogen during polymerization.
Implementation Method 1
activating a metallocene complex represented by Formula I to provide an activated metallocene complex; contacting a monomer and a comonomer with the activated metallocene complex to produce a first polymer
Data Source
AI summary
Embodiments of the present disclosure are directed towards methods of adjusting melt index and/or density utilizing a metallocene complex represented by Formula (I): wherein each n-Pr is n-propyl, and each X is independently CH3, CI, Br, or F.