ePTFE Film-Laminated Sheet Creep Resistance
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Solution Overview
Problem
Expanded porous polytetrafluoroethylene (ePTFE) film-laminated sheets face a trade-off between creep resistance and adhesiveness, where improving creep resistance by reducing node size decreases adhesiveness, leading to productivity issues and potential peeling during use.
Innovation Solution
Increasing the number of small nodes and fibrils while maintaining a high specific surface area, achieved through controlled extrusion and expansion processes, enhances both creep resistance and adhesiveness between ePTFE films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nodes are made small to improve creep resistance, then creep resistance is improved, but adhesiveness between ePTFE films decreases
Solution Approach 1:
The patent applies parameter changes by controlling the expansion ratio within a specific range (300-500 times) rather than maximizing it. This parameter optimization allows the formation of sufficiently small nodes for creep resistance while maintaining adequate adhesiveness between films, resolving the trade-off between these two properties.
Solution Approach 2:
The patent introduces local quality differentiation by creating regions with different node sizes and densities within the ePTFE structure. By having small nodes in certain areas for creep resistance while maintaining larger nodes in other areas for adhesiveness, the material achieves both properties simultaneously through spatial variation of structural characteristics.
2Strength
If ePTFE films have high tensile strength, then material strength is improved, but cut residues are peeled during punching causing productivity deterioration
Solution Approach 1:
The patent applies preliminary anti-action by pre-treating the ePTFE films with surface modification or coating before punching operations. This preliminary treatment reduces the peeling tendency of cut residues by modifying surface properties, allowing high-strength films to be processed without productivity loss despite their inherent resistance to deformation.
Solution Approach 2:
The patent introduces an intermediary substance or layer between the ePTFE films and the cutting tool, or between film layers, that facilitates cleaner cutting and reduces peeling of cut residues. This intermediary element mediates the interaction between the high-strength material and the cutting process, enabling efficient production.
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 resulting ePTFE film-laminated sheet exhibits improved creep resistance, matrix strength, and adhesiveness, with a specific surface area of 9.0 m2/g or higher and 180-degree peeling strength of 0.20 N/mm or higher, addressing the trade-off between these properties.
Implementation Method 1
Expanded porous polytetrafluoroethylene films laminated by thermal compression bonding
Data Source
AI summary
The laminated sheet of this invention is a sheet including expanded porous polytetrafluoroethylene films laminated by thermal compression bonding, wherein the sheet has a specific surface area of 9.0 m2/g or larger and a density of from 0.4 g/cm3 to lower than 0.75 g/cm3, thereby making it possible to improve both the creep resistance and the adhesiveness between the films of the expanded porous PTFE film-laminated sheet.