Hybrid Metallocene Catalyst for Long-Chain-Branched Polypropylene
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Solution Overview
Problem
Conventional polypropylene production using Ziegler-Natta catalysts results in broad molecular weight distribution and non-uniform compositional distribution, leading to issues like low impact strength and melt strength, while metallocene catalysts face challenges in introducing long chain branches for improved properties.
Innovation Solution
A hybrid supported metallocene catalyst comprising specific metallocene compounds with defined molar ratios and a support system, which includes a first metallocene compound for forming double bonds and a second metallocene compound for high polymerizability, enhancing catalytic activity and introducing long chain branches into polypropylene molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Ziegler-Natta catalyst is used for polypropylene production, then high productivity is achieved, but the polymer has broad molecular weight distribution and low impact strength
Solution Approach 1:
The catalyst system is segmented into multiple distinct metallocene catalyst components (first metallocene catalyst and second metallocene catalyst), each with specific ligand structures that provide different active site characteristics. This segmentation allows each catalyst component to contribute differently to polymer chain growth, enabling control over molecular weight distribution and introduction of long chain branches, thereby improving impact strength while maintaining productivity
Solution Approach 2:
The invention uses a composite catalyst system combining multiple metallocene catalysts with specific ligand structures (Formula 1 and Formula 2). This composite approach integrates the advantages of different catalyst components: one optimized for high activity and another for introducing long chain branches, achieving both high productivity and improved impact strength through synergistic catalysis
2Productivity
If Ziegler-Natta catalyst is used for polypropylene production, then high productivity is achieved, but the polymer has low melt strength
Solution Approach 1:
The catalyst system is segmented into multiple distinct metallocene catalyst components (first metallocene catalyst and second metallocene catalyst), each with specific ligand structures that provide different active site characteristics. This segmentation allows each catalyst component to contribute differently to polymer chain growth, enabling control over molecular weight distribution and introduction of long chain branches, thereby improving impact strength while maintaining productivity
Solution Approach 2:
The invention uses a composite catalyst system combining multiple metallocene catalysts with specific ligand structures (Formula 1 and Formula 2). This composite approach integrates the advantages of different catalyst components: one optimized for high activity and another for introducing long chain branches, achieving both high productivity and improved impact strength through synergistic catalysis
3Manufacturing precision
If conventional metallocene catalyst is used, then narrow molecular weight distribution is achieved, but long chain branches cannot be effectively introduced
Solution Approach 1:
The ligand structures are designed with specific local features: the first metallocene catalyst has ligands (Formula 1) that create active sites favorable for high polymerization activity, while the second metallocene catalyst has ligands (Formula 2) with specific substituent patterns that promote long chain branch formation. This local quality differentiation in ligand structures enables each catalyst component to perform its specific function, achieving both narrow molecular weight distribution and effective long chain branch introduction
Solution Approach 2:
The invention uses a composite catalyst system combining multiple metallocene catalysts with specific ligand structures (Formula 1 and Formula 2). This composite approach integrates the advantages of different catalyst components: one optimized for high activity and another for introducing long chain branches, achieving both high productivity and improved impact strength through synergistic catalysis
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 hybrid catalyst achieves high melt strength in polypropylene by introducing long chain branches, improving physical properties such as tacticity and molecular weight, while maintaining high catalytic activity in propylene polymerization.
Implementation Method 1
a hybrid supported metallocene catalyst which includes at least one first metallocene compound and at least one second metallocene compound
Data Source
AI summary
Disclosed is a hybrid supported metallocene catalyst exhibiting high activity in propylene polymerization and useful for preparing a polypropylene having high melt strength by introducing long chain branches into the polypropylene molecule, and to a method for preparing a polypropylene using the same.