Homopolypropylene Pellet Metallocene Catalyst Narrow Molecular Weight Distribution
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Solution Overview
Problem
There is a need for a homopolypropylene resin pellet that is environment-friendly, has excellent workability, and enables the preparation of fine denier fiber, as existing resins face limitations in achieving these properties simultaneously.
Innovation Solution
A homopolypropylene resin pellet is developed using a metallocene catalyst with high hydrogen reactivity, exhibiting a melt index greater than 500 g/10min, a melting point of 155°C or more, and a narrow molecular weight distribution of 2.0 to 2.4, which allows for the preparation of fine denier fibers without the use of decomposition accelerators, and is extruded at a controlled pellet die temperature of 150 to 190°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Ziegler-Natta catalyst with multi active sites is used to produce highly flowable homopolypropylene, then flowability is improved, but molecular weight distribution becomes greater than 3, limiting fine denier preparation
Solution Approach 1:
The patent changes the catalyst system from Ziegler-Natta to metallocene catalyst, which fundamentally alters the polymerization mechanism to achieve narrow molecular weight distribution (2.0-2.4) while maintaining high flowability (MI > 500 g/10min). This parameter change in catalyst type resolves the contradiction between flowability and molecular weight distribution control.
2Ease of operation
If peroxide-based decomposition accelerator is used during extrusion to achieve high flowability, then flowability is improved, but fine powders are generated, worsening workability
Solution Approach 1:
The patent removes the peroxide-based decomposition accelerator from the extrusion process entirely. By using metallocene catalyst-produced homopolypropylene with inherently narrow molecular weight distribution, the resin achieves high flowability without requiring decomposition accelerators, thus eliminating fine powder generation and improving workability.
3Manufacturing precision
If conventional homopolypropylene is used to increase fine denier, then filter efficiency is improved, but workability deteriorates due to fine powder generation
Solution Approach 1:
The patent changes the molecular weight distribution parameter to 2.0-2.4 through metallocene catalyst usage, enabling fine denier fiber preparation while preventing fine powder generation during processing. This specific parameter range achieves the dual benefit of improved filter efficiency and maintained workability.
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 resulting resin exhibits high flowability, excellent fiber processability, and reduced generation of fine particles, making it suitable for applications requiring high filter efficiency, such as filters or masks, while maintaining environmental friendliness.
Implementation Method 1
polymerizing propylene monomers in the presence of a catalyst composition comprising a transition metal compound of the following Chemical Formula 1, to prepare homopolypropylene
Implementation Method 2
molecular weight distribution of the homopolypropylene resin pellet is 2.0 to 2.4, weight average molecular weight of the homopolypropylene resin pellet is 60,000g/mol or less, and number average molecular weight of the homopolypropylene resin pellet is 16,000 to 25,000g/mol, wherein the weight average molecular weight and the number average molecular weight are measured using gel permeation chromatography (GPC)
Data Source
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AI summary
The present invention provides a polypropylene resin pellet that is environment friendly, has excellent workability, and enables preparation of fine denier fiber, and a method for preparing the same.