PTFE/PFSA Composite Membrane for Low Flow Resistance Filtration

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Solution Overview

Problem

Current PTFE membranes are inadequate for filtering hot sulfuric peroxide mixtures and metal-containing fluids due to high flow resistance and limited metal scavenging efficiency, particularly in applications requiring low dewetting characteristics.

Innovation Solution

A porous membrane is developed by blending PTFE with perfluorosulfonic acid (PFSA) additive, which is cross-linked or non-cross-linked, and processed to achieve a critical wetting surface tension of 30-40 dynes/cm, allowing effective filtration of sulfuric peroxide mixtures and metal-containing fluids with low flow resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PTFE membranes are used for filtering sulfuric peroxide mixture and metal-containing fluids, then chemical resistance and filtration capability are improved, but flow resistance increases and metal scavenging efficiency is limited

Engineering Contradiction:
Improvefiltration capabilityVSAvoidflow resistance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent combines PTFE with PFSA (perfluorosulfonic acid) to create a composite membrane material. The PTFE provides chemical resistance and filtration capability, while the PFSA component introduces metal scavenging functionality and modifies surface properties to reduce flow resistance, thereby resolving the contradiction between filtration performance and flow efficiency

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the surface tension parameter of the membrane by incorporating PFSA additive, achieving a critical wetting surface tension of 30-40 dynes/cm. This parameter change improves wetting characteristics and reduces flow resistance while maintaining the filtration capability provided by the PTFE matrix

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If PTFE membranes are used for metal-containing fluid filtration, then chemical stability is improved, but metal scavenging efficiency deteriorates

Engineering Contradiction:
Improvechemical stabilityVSAvoidmetal scavenging efficiency
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent creates a composite system where PTFE provides chemical stability and inertness, while PFSA (particularly when cross-linked) provides metal scavenging functionality through its sulfonic acid groups. This composite approach allows both chemical stability and metal removal efficiency to coexist

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different functional properties to different aspects of the membrane: the bulk PTFE matrix provides chemical stability and structural integrity, while the PFSA component localized within the membrane provides metal scavenging capability, creating local quality differentiation that resolves the contradiction

Inventive Principle:
Principle #3Local quality

3Reliability

If membrane surface tension is reduced to improve wetting characteristics, then non-dewetting properties are improved, but flow resistance may increase

Engineering Contradiction:
Improvenon-dewetting propertiesVSAvoidflow resistance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent optimizes the surface tension parameter to a specific range (30-40 dynes/cm critical wetting surface tension) that balances wetting characteristics and flow resistance. This precise parameter control ensures non-dewetting properties while maintaining acceptable flow characteristics

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 PTFE/PFSA membrane achieves high metal scavenging efficiency and low flow resistance, maintaining non-dewetting properties, suitable for a wide range of filtration applications including pharmaceutical, medical, and industrial uses, while being easily integrated into existing manufacturing processes.

Implementation Method 1

passing the fluid through a porous membrane comprising PTFE blended with perfluorosulfonic acid (PFSA) additive, and removes particles from the fluid

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

a porous membrane which is formed from a porous polyperfluorocarbon membrane substrate having its surface modified with a perfluorocarbon polymer composition comprising, e.g., Nafion

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 3

perfluorosulfonic acid (PFSA) additive

Methodology Applied
Scientific EffectIon exchange: Ion Exchange

Implementation Method 4

the membrane has a CWST of about 30 dynes/cm (about 30 x 10^-5 N/m), wherein the CWST is a critical wetting surface tension

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP3130390B1PTFE/PFSA additive blended membrane
Publication Date: 2021.03.24 PALL CORP

AI summary

A porous membrane comprising PTFE blended with PFSA is disclosed.