Polyethylene Powder for Microporous Membranes
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Solution Overview
Problem
Existing methods for producing polyethylene powders for microporous membranes and fibers fail to improve productivity, resistance to end breakage, dimensional stability, and acid resistance.
Innovation Solution
A polyethylene powder with specific amounts of aluminum hydroxide and magnesium, having a viscosity-average molecular weight of 100,000 or higher, is developed, which is produced by polymerizing ethylene in the presence of a catalyst and deactivating it using a catalyst deactivator, such as water sprayed in the form of steam, to achieve improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-molecular-weight polyethylene is used as raw material for microporous membranes and fibers, then mechanical strength and chemical stability are improved, but melt viscosity increases making injection molding difficult
Solution Approach 1:
The patent changes the processing method from injection molding to dissolution processing, and adjusts the molecular weight parameter to an ultra-high range (10^6-10^8) to achieve both high strength and processability through solvent dissolution
2Ease of manufacture
If polyethylene is dissolved in solvents for continuous processing, then processability is improved, but foreign matter (polyethylene gels) may form reducing productivity and quality
Solution Approach 1:
The patent changes the dissolution temperature parameter to above the melting point of polyethylene, ensuring complete dissolution and preventing gel formation, thereby maintaining both continuous processing capability and product quality
Solution Approach 2:
The patent uses a mixed solvent system comprising a first solvent and a second solvent with different properties to achieve complete dissolution of ultra-high molecular weight polyethylene while preventing foreign matter formation during continuous processing
3Reliability
If existing methods are used to reduce foreign matter in microporous membranes, then quality is improved, but productivity of continuous processing and resistance to end breakage are not improved
Solution Approach 1:
The patent changes multiple parameters simultaneously: temperature (above melting point), molecular weight (ultra-high range), and solvent composition (mixed solvent system) to achieve complete dissolution that prevents foreign matter formation while maintaining high productivity
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 polyethylene powder enhances the resistance to end breakage, dimensional stability, and acid resistance of fibers and microporous membranes, while maintaining high productivity in continuous processing.
Implementation Method 1
deactivating it using a catalyst deactivator, such as water sprayed in the form of steam
Data Source
AI summary
It is intended to provide a polyethylene powder which can offer a fiber excellent in resistance to end breakage, dimensional stability, and acid resistance and/or a microporous membrane excellent in dimensional stability and acid resistance, and a microporous membrane and a fiber which are obtained by forming the polyethylene powder. The present invention provides a polyethylene powder comprising: 0.5 ppm or higher and 3,000 ppm or lower of aluminum hydroxide having an average particle size smaller than 50 μm; and 0.5 ppm or higher and 12 ppm or lower of a magnesium element, wherein the polyethylene has a viscosity-average molecular weight of 100,000 or larger.