Group 4 Metallocene Catalysts for High Comonomer Polyolefins
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Solution Overview
Problem
There is a need for polyolefin copolymers with high comonomer content and high molecular weight, as well as bimodal molecular weight distribution polyolefin compositions that combine the mechanical properties of high molecular weight fractions with improved processing properties, which existing methods struggle to achieve efficiently and cost-effectively.
Innovation Solution
The use of catalyst compounds represented by specific formulas, comprising group 4 metals and bridged or unbridged metallocene catalysts, to produce polyolefin compositions with high comonomer content and bimodal molecular weight distribution, enhancing catalyst productivity and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional Ziegler-Natta or metallocene catalysts are used, then polyolefin copolymers can be produced, but achieving high comonomer content and high molecular weight simultaneously is difficult
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing group 4 metal catalysts with specific ligand structures (Formula I and Formula II) and using non-coordinating anion activators. This parameter change enables the catalyst to accommodate both high comonomer incorporation and high molecular weight polymer production, resolving the trade-off between these two properties.
Solution Approach 2:
The patent creates a composite catalyst system combining group 4 metal centers with specific organic ligands (cyclopentadienyl, indenyl, fluorenyl) and non-coordinating anion activators. This composite structure provides unique catalytic properties that enable simultaneous achievement of high comonomer content and high molecular weight, which neither conventional Ziegler-Natta nor standard metallocene catalysts can achieve alone.
2Strength
If methods to produce bimodal molecular weight distribution polyolefins are used, then mechanical properties improve, but processing efficiency and cost-effectiveness deteriorate
Solution Approach 1:
The patent merges the functions of producing different molecular weight fractions into a single catalyst system. The group 4 metal catalyst with specific ligand structure can simultaneously produce high molecular weight and low molecular weight polyolefin fractions with bimodal distribution in one reactor, eliminating the need for separate processes or multiple catalysts, thereby improving processing efficiency while maintaining mechanical properties.
Solution Approach 2:
The catalyst system exhibits multi-functionality by being capable of producing polyolefins with bimodal molecular weight distribution, high comonomer content, and high molecular weight all through a single catalytic system. This universal catalyst replaces multiple specialized catalysts or processes, improving overall processing efficiency and cost-effectiveness.
3Quantity of substance
If existing catalyst systems are used to produce high comonomer content copolymers, then comonomer incorporation increases, but molecular weight and mechanical properties suffer
Solution Approach 1:
The patent changes the catalytic parameters by using group 4 metal catalysts (Ti, Zr, Hf) with specific ligand structures and non-coordinating anion activators. This parameter change allows the catalyst to maintain high activity even when incorporating high comonomer content, preventing the typical drop in molecular weight and mechanical properties that occurs with conventional catalysts.
Solution Approach 2:
The patent employs a catalyst system that maintains high productivity and activity throughout the polymerization process even with high comonomer content. The catalyst resists deactivation and maintains its ability to produce high molecular weight chains, effectively replacing catalysts that would otherwise become inactive or produce low molecular weight material under high comonomer conditions.
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 results in polyolefin compositions with improved mechanical properties and processing efficiency, achieving high comonomer content and density split, thereby addressing the limitations of existing methods in producing such materials.
Implementation Method 1
a catalyst compound, and catalyst systems comprising such catalyst compounds and uses thereof
Data Source
AI summary
Disclosed herein is a catalyst compound represented by Formula (I) or Formula (II):M is a group 4 metal. Each of R1, R2, R3, R4, R5, R6, R7, R8, and R9 is independently hydrogen, or a C1-C50 substituted or unsubstituted hydrocarbyl, halocarbyl, silylcarbyl, alkoxyl, siloxyl, or one or more of R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 are joined to form cyclic a saturated or unsaturated ring. Each X is independently a halide or C1-C50 substituted or unsubstituted hydrocarbyl, hydride, amide, alkoxide, sulfide, phosphide, halide, or a combination thereof, or two Xs are joined together to form a metallocycle ring, or two Xs are joined to form a chelating ligand, a diene ligand, or an alkylidene. Also disclosed is a method for using the catalyst compound in a catalyst system to produce polyolefin polymers.