Polyolefin Microporous Membrane for Liquid Filter Substrate
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Solution Overview
Problem
Current liquid filters face a trade-off between collection efficiency for fine particles less than 10 nm and liquid permeability, with long-term use often resulting in decreased permeability due to changes in the porous structure of polyolefin microporous membranes.
Innovation Solution
A polyolefin microporous membrane with specific properties, including a water permeation efficiency of 0.10 to 0.50 ml/min·cm², a bubble point of 0.50 MPa to 0.80 MPa, heat shrinkage of 15% or more, and tensile elongation of 55% to 200%, is developed to maintain excellent collection efficiency and stable liquid permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the porous structure is refined to improve collection efficiency for fine particles less than 10 nm, then collection efficiency is improved, but liquid permeability decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the bubble point (0.50-0.80 MPa) and water permeation efficiency (0.10-0.50 ml/min·cm²) of the polyolefin microporous membrane. By adjusting these physical parameters within specific ranges, the membrane achieves both fine particle collection efficiency and adequate liquid permeability, resolving the trade-off between filtration precision and flow rate
Solution Approach 2:
The patent uses composite material structure by combining polyolefin base material with specific pore structure characteristics. The microporous membrane integrates multiple functional characteristics: fine pore size for particle collection, controlled porosity for permeability, and specific mechanical properties for structural stability, achieving multi-performance optimization
2Reliability
If pressure is repeatedly applied to the polyolefin microporous membrane during long-term use, then filtration function is maintained, but the porous structure changes causing gradual decrease in liquid permeability
Solution Approach 1:
The patent addresses structural stability by controlling the mechanical parameters of the microporous membrane, specifically tensile elongation (55-200%) and heat shrinkage (≥15%). These parameter controls ensure the membrane can withstand repeated pressure cycles during long-term use without significant structural degradation, maintaining both filtration function and permeability stability
Solution Approach 2:
The patent applies beforehand cushioning by designing the membrane with adequate mechanical buffer capacity. The controlled tensile elongation and elastic properties provide a cushioning effect that absorbs stress from repeated pressure application, preventing cumulative damage to the porous structure and maintaining long-term performance
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 solution enables a substrate for liquid filters that efficiently collects fine particles while maintaining high liquid permeability over long-term use, balancing collection efficiency and permeability.
Implementation Method 1
A liquid chemical prepared at high level is filtered through a dense filter immediately before application onto a wafer to remove particles that would greatly affect the pattern formation or yield
Implementation Method 2
the polyolefin microporous membrane having a water permeation efficiency of 0.10 to 0.50 ml/min·cm2
Implementation Method 3
A phase separation method is a technique that forms pores utilizing the phase separation phenomenon of a polymer solution
Data Source
AI summary
A substrate for a liquid filter, which includes a polyolefin microporous membrane, the polyolefin microporous membrane having a water permeation efficiency of 0.10 to 0.50 ml/min·cm2, the polyolefin microporous membrane having a bubble point of 0.50 MPa or more and 0.80 MPa or less.