Stretched Porous PTFE Membrane Node-Fibril Structure
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Solution Overview
Problem
Highly-air-permeable stretched porous PTFE membranes used in filter members are prone to breakage during handling and attachment to housings due to low cohesion, which limits their application in ensuring both air permeability and structural integrity.
Innovation Solution
A stretched porous PTFE membrane with a node-fibril structure, where the ratio of average node length to membrane thickness is 10% or more, enhancing cohesion and reducing breakage risk, while maintaining high air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a highly-air-permeable stretched porous PTFE membrane is used to improve air permeability and facilitate downsizing, then air permeability is improved, but the membrane is likely to suffer breakage such as cracking during handling or attachment
Solution Approach 1:
The patent applies local quality by creating a node-fibril structure where nodes (aggregates of PTFE) are distributed throughout the membrane at specific intervals. These localized dense regions act as reinforcement points that prevent crack propagation while maintaining overall porosity. The nodes are positioned to create a network that provides structural integrity without blocking air flow paths.
Solution Approach 2:
The patent creates a composite structure within the PTFE membrane by forming a node-fibril architecture. The membrane consists of two distinct phases: dense nodal regions and porous fibrillar regions. This composite-like structure combines the high strength of dense PTFE aggregates with the high permeability of porous fibrillar networks, achieving both breakage resistance and air permeability.
2Volume of moving object
If the membrane thickness is reduced to facilitate downsizing, then device size is reduced, but the membrane becomes more susceptible to breakage
Solution Approach 1:
The patent addresses the thickness-strength trade-off by transitioning from a two-dimensional thin film problem to a three-dimensional structured material. Instead of simply making the membrane thinner, the invention creates a vertically structured node-fibril architecture where nodes are distributed through the thickness. This dimensional approach allows the membrane to maintain strength through internal structural complexity rather than relying solely on thickness.
Solution Approach 2:
The patent changes the structural parameters of the membrane by controlling the size, distribution, and morphology of nodes and fibrils. By adjusting node diameter, inter-node distance, and fibril density, the membrane can achieve optimal balance between thinness and strength. The parameter optimization allows reduced thickness while maintaining cohesion through enhanced structural organization.
Data Source
AI summary
A provided stretched porous polytetrafluoroethylene membrane has a node-fibril structure including a plurality of nodes and a fibril connecting the plurality of nodes. A ratio of an average length of the plurality of nodes in a thickness direction of the stretched porous polytetrafluoroethylene membrane to a thickness of the stretched porous polytetrafluoroethylene membrane is 10% or more. The above stretched porous polytetrafluoroethylene membrane is less likely to suffer breakage. In the above stretched porous polytetrafluoroethylene membrane, assuming that there is a cuboid region having an upper surface and a lower surface respectively positioned at one membrane surface and the other membrane surface of the stretched porous polytetrafluoroethylene membrane, the number of the nodes included in the region may be 4 or less per micrometer thickness, the upper surface and the lower surface each having dimensions of 280 μm×280 μm.