Stretched Porous PTFE Membrane Balancing Airflow and Handling Strength
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Solution Overview
Problem
Highly-air-permeable stretched porous PTFE membranes are prone to breakage during handling or placement due to uneven peel cohesion in different directions, compromising their structural integrity.
Innovation Solution
A stretched porous PTFE membrane with an air permeability of 4 cm3/(sec·cm2) or more and a total cohesion of 1.9 (N/20 mm)2 or more, achieved by biaxial stretching and sintering, ensuring balanced peel cohesion in both in-plane directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a highly-air-permeable stretched porous PTFE membrane is used, then air permeability is improved, but the membrane is likely to suffer breakage during handling or placement
Solution Approach 1:
The invention changes the physical parameters of the PTFE membrane by controlling the stretching process to achieve specific air permeability (4 cm³/(sec·cm²) or more) and peel cohesion (1.9 (N/20 mm)² or more) values, resolving the contradiction between permeability and breakage resistance
Solution Approach 2:
The invention creates uniform local quality throughout the membrane by ensuring consistent peel cohesion in both machine direction and transverse direction, preventing weak spots that would cause breakage during handling
2Reliability
If the peel cohesion in machine direction and transverse direction is made uniform, then handling reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention initially creates asymmetric stretching conditions during manufacturing (different stretching ratios or speeds in machine direction versus transverse direction) to achieve the desired air permeability, then uses controlled biaxial stretching to balance the peel cohesion uniformly in both directions
Solution Approach 2:
The invention employs dynamic control of the stretching process, adjusting stretching ratios and temperatures during manufacturing to achieve both high air permeability and uniform peel cohesion, managing the complexity through process optimization
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 membrane maintains high air permeability while significantly reducing the likelihood of breakage during handling or placement, making it suitable for filter members.
Implementation Method 1
having an air permeability of 4 cm3/(sec·cm2) or more, as expressed in terms of Frazier air permeability, in a thickness direction
Implementation Method 2
preventing a foreign matter from passing therethrough in the thickness direction
Data Source
AI summary
A provided stretched porous polytetrafluoroethylene membrane has an air permeability of 4 cm3/(sec·cm2) or more, as expressed in terms of Frazier air permeability, in a thickness direction, and has a total cohesion of 1.9 (N/20 mm)2 or more, the total cohesion being expressed by a product of a peel cohesion in a first in-plane direction and a peel cohesion in a second in-plane direction perpendicular to the first direction. The above stretched porous membrane is highly air-permeable and, for example, when included in a filter member, being less likely to suffer breakage at the time of handling the member or placing the member on a housing or the like.