Metallocene Catalyst System for High Isotacticity Polypropylene
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Solution Overview
Problem
Conventional methods for producing polypropylene using Ziegler-Natta catalysts face limitations in achieving high flow rates and isotacticity, leading to decreased physical properties and increased volatile organic compounds (TVOC) when compensating for processability by mixing or cracking polymers with different flow rates.
Innovation Solution
A method involving the polymerization of olefin monomers using a supported catalyst system comprising a transition metal compound, a specific cocatalyst, and a Lewis base cocatalyst supported on a carrier, which achieves high stereoregularity and hydrogen reactivity, resulting in olefin polymers with excellent isotacticity, processability, and reduced TVOC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional Ziegler-Natta catalyst is used to produce polypropylene, then excellent strength and stretchability are achieved, but high flow rate and isotacticity cannot be simultaneously obtained
Solution Approach 1:
The patent modifies the catalyst system parameters by introducing a specific metallocene catalyst with defined chemical structure (Formula 1) and combining it with specific cocatalysts (Formulas 2 and 3) in controlled ratios. This parameter change enables simultaneous achievement of high isotacticity (95% or more) and high flow rate, resolving the contradiction between strength and manufacturability
Solution Approach 2:
The patent creates a composite catalyst system comprising multiple components: metallocene catalyst (Formula 1), first cocatalyst (Formula 2), and second cocatalyst (Formula 3). This composite catalyst structure synergistically combines the functions of each component to achieve both high stereoregularity and high flow rate properties in the resulting polypropylene
2Ease of operation
If excess hydrogen is supplied to increase flow rate, then processability is improved, but physical properties such as strength decrease
Solution Approach 1:
The patent changes the fundamental parameter of catalyst activity through the metallocene catalyst system, which inherently provides high flow rate without requiring excess hydrogen. This eliminates the need to trade off strength for processability, as both high strength and high processability are achieved simultaneously through the catalyst design
3Ease of operation
If polymers with different flow rates are mixed to compensate processability, then flow rate is adjusted, but total volatile organic compounds (TVOC) increase and physical properties decrease
Solution Approach 1:
The patent changes the production approach from post-processing mixing to in-situ controlled polymerization using the metallocene catalyst system. This single-catalyst system produces polypropylene with consistent high flow rate and high isotacticity directly, eliminating the need for mixing different polymers and thereby preventing TVOC generation and property degradation
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 method produces olefin polymers with high tensile and flexural strength, improved processability, and low TVOC, making them suitable for long fiber-reinforced resins with enhanced mechanical properties.
Implementation Method 1
polymerizing olefin monomers in the presence of a supported catalyst in which a transition metal compound represented by the following Chemical Formula 1, a cocatalyst represented by the following Chemical Formula 2, and a cocatalyst represented by the following Chemical Formula 3 are supported on a carrier
Data Source
AI summary
The present invention provides a method for preparing an olefin polymer which can exhibit excellent isotacticity in a high yield and thus is suitable for use in reinforcing a long fiber, and a long fiber comprising an olefin polymer produced according to the above preparation method.