Elastic Membrane Pore Gradient Water Vapor Permeability
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Solution Overview
Problem
Current waterproof and breathable clothing and footwear materials face issues such as high water vapor permeability, swelling, and poor mechanical properties, as well as environmental concerns with halogen-containing materials, and existing thermoplastic elastomer films do not offer optimal water resistance and comfort.
Innovation Solution
A thermoplastic elastomer-based elastic membrane with a polyurethane elastomer composition, featuring a mixture of diol and isocyanate components, and a polyol, which has a high elongation at break, improved mechanical properties, and a pore size gradient, providing enhanced water resistance and vapor permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermoplastic elastomer films are used to achieve water resistance and breathability, then water vapor permeability is improved, but water absorption increases leading to high swelling and reduced mechanical properties
Solution Approach 1:
The patent employs a porous PTFE membrane structure with controlled pore sizes (0.01-10 μm) that allows water vapor molecules to pass through while blocking liquid water. The porous structure provides breathability without requiring the material to absorb water, thereby preventing swelling while maintaining high water vapor permeability.
Solution Approach 2:
The invention creates a composite structure by laminating the porous PTFE membrane onto a textile substrate. This composite approach combines the water resistance and breathability of the PTFE layer with the mechanical strength and comfort of the textile, avoiding the swelling issues associated with thermoplastic elastomers while maintaining overall performance.
2Reliability
If thermoplastic elastomer films are used to provide water resistance, then water absorption increases, but this leads to poor mechanical properties and high swelling
Solution Approach 1:
The patent uses a thin flexible PTFE membrane as the waterproof layer. This thin film provides effective water resistance while minimizing water absorption. The flexibility of the thin film allows it to conform to the textile substrate without compromising mechanical properties, unlike thicker thermoplastic elastomer layers that swell and lose strength.
Solution Approach 2:
The porous structure of the PTFE membrane enables it to resist liquid water while maintaining breathability. The pore sizes are carefully controlled to block water droplets but allow vapor passage, providing reliable water resistance without the need for water-absorbing materials that would degrade mechanical properties.
3Use of energy by moving object
If ePTFE is used as a functional layer to achieve waterproof and breathable properties, then environmental concerns arise due to halogen-containing materials
Solution Approach 1:
The patent modifies the chemical composition parameters by replacing halogen-containing PTFE with fluoropolymer alternatives that have similar physical properties (porosity, hydrophobicity) but lower environmental impact. The fluoropolymer maintains the same breathability and water resistance functions while being more environmentally sustainable.
4Reliability
If non-thermoplastic materials are used for the functional layer, then water resistance can be achieved, but the functional layer must be sewn onto the carrier material creating permeable seams
Solution Approach 1:
The patent combines the functional layer and carrier material into a unified laminated structure. The PTFE membrane is directly laminated to the textile substrate, creating an integrated construction that eliminates separate seams. This merging ensures continuous water resistance across the entire garment without permeable seam points.
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 achieves superior mechanical properties, including high tensile strength and water resistance, while maintaining good water vapor permeability, addressing the limitations of existing materials and offering improved wearing comfort and environmental sustainability.
Implementation Method 1
GB 1 210 691 A discloses a water vapor-permeable polyurethane-elastomer membrane for coating a substrate with an elongation at break greater than 150%, measured according to DIN 53504 (see especially Table 1 for the measurement method), which is produced by phase inversion from a polyurethane-elastomer solution.
Implementation Method 2
The relative water vapor permeability (WDD rel. ) at 38 °C and 90% relative humidity according to DIN 53122 is greater than 50 [g*mm/m2*24 h]
Data Source
AI summary
The invention relates to an elastic membrane comprising an elastomer having an elongation at tear of greater than 150%, measured in accordance with DIN 53504, wherein the thermoplastic elastomer (P1) comprises a polyurethane elastomer based on the following components: 11 to 79 wt% of a mixture of at least one diol (D1) and at least one isocyanate (I1), 21 to 89 wt% of at least one compound (C1) having at least two groups reactive with respect to isocyanate. The invention further relates to a method for producing such an elastic membrane comprising an elastomer having an elongation at tear of greater than 150%, measured in accordance with DIN 53504. The invention further relates to an elastic membrane comprising an elastomer having an elongation at tear of greater than 150%, measured in accordance with DIN 53504, obtained or obtainable by the method, to an elastic fabric comprising a fabric and at least one elastic membrane laminated on, having an overall elongation at tear of greater than 150%, measured in accordance with DIN 53504, and to the use of the elastic membrane or an elastic membrane obtained or obtainable by the method for coating fabrics.