Hybrid Supported Metallocene Catalyst for High-Melt-Strength Polypropylene
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Solution Overview
Problem
Existing polypropylene production methods using Ziegler-Natta catalysts result in high volatile organic compounds (VOCs) and struggle to achieve high melt strength, while metallocene catalysts lack the ability to introduce long chain branches (LCB) effectively, leading to polypropylenes with low impact strength and melt strength.
Innovation Solution
A hybrid supported metallocene catalyst comprising specific first and second metallocene compounds, supported on a carrier with hydroxyl and siloxane groups, enhances catalytic activity and introduces LCBs into polypropylene molecules, improving melt strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Ziegler-Natta catalyst is used for polypropylene production, then high catalytic activity is achieved, but high volatile organic compounds (VOCs) are generated
Solution Approach 1:
The patent uses a composite catalyst system combining metallocene compounds with specific ligand structures (Formula 1 and Formula 2) supported on a carrier material. This composite structure achieves high catalytic activity while reducing VOC generation by eliminating the need for traditional Ziegler-Natta catalyst components that produce high levels of volatile organic compounds.
2Manufacturing precision
If conventional metallocene catalyst is used for polypropylene production, then single active site characteristics are achieved, but long chain branches (LCB) cannot be introduced effectively
Solution Approach 1:
The patent introduces specific ligand structures (Formula 1 with R5-R7 groups and Formula 2 with R11-R18 groups) that create local active sites with different functionalities on the metallocene catalyst. These localized structural variations enable the catalyst to perform both precise comonomer incorporation and effective long chain branch introduction, resolving the contradiction between uniformity and melt strength.
3Strength
If polypropylene with high melt strength is produced through post-modification, then melt strength is improved, but additional processing steps are required
Solution Approach 1:
The patent incorporates the capability to introduce long chain branches directly into the polypropylene molecule during the polymerization process itself, rather than requiring subsequent post-modification steps. The metallocene catalyst with specific ligand structures performs this function preliminarily, eliminating the need for additional irradiation or grafting processes and simplifying the overall production流程.
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 catalytic activity and produces polypropylene with improved melt strength by incorporating LCBs, addressing the limitations of existing catalysts in reducing VOCs and enhancing physical properties.
Implementation Method 1
hybrid supported metallocene catalyst comprising specific first and second metallocene compounds, supported on a carrier with hydroxyl and siloxane groups, enhances catalytic activity and introduces LCBs into polypropylene molecules
Data Source
AI summary
Provided are a hybrid supported metallocene catalyst comprising one or more first metallocene compounds selected from compounds represented by the following Chemical Formula 1; one or more second metallocene compounds selected from compounds represented by the following Chemical Formula 2, and showing high activity in propylene polymerization and being usefully applied to the preparation of a polypropylene having high melt strength by introducing long chain branches into the polypropylene molecule, and a method of preparing a polypropylene using the samewherein all the variables are described herein.