Stretch Composite Fabric ePTFE Film Lamination
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Solution Overview
Problem
Existing composite fabrics made from expanded porous polytetrafluoroethylene (ePTFE) films struggle to achieve a balance between stretch property and strength without corrugating the film, leading to issues with delamination and compromised moisture permeability when using sintered ePTFE, and the methods to enhance stretch property often require the use of elastomer resins which can increase thickness and reduce permeability.
Innovation Solution
A stretch composite fabric is created by laminating a sintered ePTFE film with a stretch cloth, where the laminate is stretched and then shrunk to increase the area without corrugating the film, utilizing the shrinking force of the cloth or heat to achieve the desired properties, eliminating the need for elastomer resin impregnation and maintaining a flat state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintered ePTFE film is used to ensure strength, then cohesive strength is improved, but stretch property deteriorates
Solution Approach 1:
The patent applies heat treatment to the sintered ePTFE film to change its physical parameters. By heating the film to a specific temperature range (200-300°C) and holding it, the crystalline structure and molecular arrangement of the PTFE are modified, which simultaneously improves cohesive strength and enables stretch recovery properties without requiring elastomer resins.
2Strength
If stretch resin is applied to surfaces to prevent delamination, then cohesive strength is improved, but thickness increases and moisture permeability decreases
Solution Approach 1:
The patent removes the elastomer resin layer from the composite fabric structure entirely. Instead of applying stretch resin to the surfaces of the ePTFE film, the invention uses heat treatment of the sintered ePTFE film itself to achieve both delamination prevention and stretch recovery, thereby eliminating the thickness increase and moisture permeability reduction that would result from adding resin layers.
3Adaptability or versatility
If ePTFE film is stretched to increase area, then stretch property is improved, but necking occurs and width decreases
Solution Approach 1:
The patent applies heat treatment to the sintered ePTFE film before lamination to pre-establish the stretch recovery capability. By heating the film in advance to modify its molecular structure and enable elastic recovery, the film can subsequently be stretched during lamination without permanent necking or width reduction, as the heat-treated structure allows for reversible deformation.
4Adaptability or versatility
If stretch cloth is laminated to ePTFE film to provide stretch, then stretch property is improved, but delamination occurs due to low cohesive strength
Solution Approach 1:
The patent changes the temperature parameter of the sintered ePTFE film through heat treatment (heating to 200-300°C and holding) to simultaneously achieve two objectives: (1) improve the cohesive strength of the ePTFE film to prevent delamination from the stretch cloth, and (2) enable the film to provide stretch recovery itself, reducing dependence on the stretch cloth while still maintaining the laminate structure.
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 method enhances the strength and stretch property of the ePTFE film significantly while maintaining a flat, aesthetically pleasing surface and improving moisture permeability, with a tensile stress at 10% elongation of 1.8 N/15 mm or less and an elongation recovery of 70% or more, without the drawbacks of delamination or increased thickness.
Implementation Method 1
heating the sintered ePTFE film to a temperature of 200°C to 300°C
Implementation Method 2
the laminate is stretched and shrunk by removing the stretching force or by heat
Data Source
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AI summary
A stretch composite fabric comprises a sintered expanded porous polytetrafluoroethylene film and a stretch cloth laminated to each other while maintaining a flat state. The stretch composite fabric has a tensile stress at 10% elongation, as measured in at least one direction, of 1.8 N/15 mm or less. When a 5 cm-width test piece of the stretch composite fabric is stretched in a length direction under a load of 300 g and then released from the stress, an elongation recovery R of the stretch composite fabric, which is given by the following equation, is preferably 70% or more. R = (L2-L3) / (L2-L1) x 100 (In the equation, L1, L2, and L3 represent the lengths of the composite fabric before the load is applied, when the load is applied, and after the load is removed, respectively.)