Polyolefin Microporous Membrane for Liquid Filter

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Solution Overview

Problem

Existing liquid filters face a trade-off between collection efficiency for particles of 50 nm to 100 nm and liquid permeability, with long-term use leading to unstable water permeability and potential pore blockage, and no solution has been proposed to achieve both excellent collection efficiency and stable permeability simultaneously.

Innovation Solution

A polyolefin microporous membrane with specific properties, including a water permeation efficiency of 1.21 to 2.90 ml/min·cm2, a bubble point of 0.40 MPa to 0.65 MPa, compressibility less than 15%, heat shrinkage of 20% or more, thickness of 7 to 16 μm, pore-blocking temperature above 140°C, and porosity of 50 to 60%, is used as a substrate for the liquid filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a polyolefin microporous membrane with high collection efficiency for particles of 50 nm to 100 nm is used, then the liquid permeability decreases

Engineering Contradiction:
Improvecollection efficiencyVSAvoidliquid permeability
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the water permeation efficiency (1.21 to 2.90 ml/min·cm2), bubble point (0.40 MPa to 0.65 MPa), compressibility (less than 15%), heat shrinkage (20% or more), thickness (7 to 16 μm), pore-blocking temperature (above 140°C), and porosity (50 to 60%) of the polyolefin microporous membrane. These parameter adjustments enable the membrane to achieve both high collection efficiency for particles of 50 nm to 100 nm and adequate liquid permeability, resolving the trade-off between filtration performance and flow rate.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If the polyolefin microporous membrane is used for long-term filtration, then the liquid permeability becomes unstable due to pore blockage

Engineering Contradiction:
Improvefiltration performanceVSAvoidliquid permeability stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by selecting a polyolefin microporous membrane with compressibility of less than 15% and pore-blocking temperature above 140°C. These properties provide structural stability and resistance to deformation under pressure, preventing pore blockage and maintaining stable liquid permeability during long-term filtration operations.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent maintains reliable liquid permeability by controlling key parameters: water permeation efficiency (1.21 to 2.90 ml/min·cm2), bubble point (0.40 MPa to 0.65 MPa), compressibility (less than 15%), and pore-blocking temperature (above 140°C). These parameter specifications ensure the membrane structure remains stable under filtration conditions, preventing performance degradation over time.

Inventive Principle:
Principle #35Parameter changes

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 provides a liquid filter with excellent collection efficiency and stable liquid permeability for long-term use, maintaining high filtration performance and preventing pore blockage.

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

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 2

the water permeation efficiency of the polyolefin microporous membrane is 1.21 to 2.90 ml/min·cm2

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentUS11338252B2Substrate for liquid filter
Publication Date: 2022.05.24 TEIJIN LTD

AI summary

A substrate for a liquid filter, which includes a polyolefin microporous membrane, the polyolefin microporous membrane having a water permeation efficiency of 1.21 to 2.90 ml/min·cm2, the polyolefin microporous membrane having a bubble point of 0.40 MPa to 0.65 MPa, the polyolefin microporous membrane having a compressibility of less than 15%.