Waterproof breathable film is a product application derived from membrane separation technology. It is a film made with a special process and has selective permeability. It can allow some gases smaller than the aperture of waterproof breathable film to pass through under its own characteristics, and cannot allow other substances such as water droplets larger than the aperture of waterproof breathable film to pass through. It is precisely because of the nature of the waterproof breathable film that some small molecules can pass, and some large molecules can not pass through the waterproof breathable film, so since the 1960s of the last century, the waterproof breathable film has been rapidly developed. At present, there are mainly PTFE, PES, PVDF, PP, PETE and other filtration membranes, due to the good chemical stability of ePTFE materials, natural hydrophobic properties and used in all walks of life.
Working principle of waterproof breathable membrane
In the state of water vapor, the diameter of water vapor molecules is only about 0.0004 microns, and the minimum diameter of water droplets is about 20 microns. The existence of polymer breathable layer containing micropores in the waterproof breathable film enables the water vapor molecules in the wall to discharge smoothly through the microporous membrane through the diffusion principle, effectively reducing the problem of condensation on the exterior wall. Because of the large diameter of liquid water or water droplets outside the wall, water molecules cannot penetrate from the water beads to the other side, which makes the breathable film waterproof.
Under normal circumstances, many devices and their applications require a relatively closed sealing environment, which cannot be affected by external dust, water, and bacteria. If the design is particularly closed, under the objective conditions of ambient temperature and latitude changes, it will lead to pressure changes inside the equipment, usually this pressure change will produce a certain concentration effect, which will destroy the sensitive parts of the equipment shell and the interior. The use of ePTFE waterproof breathable membrane can continuously balance the pressure difference of the equipment, reduce the cost of component design, and ensure the reliability of the product.
ePTFE waterproof breathable film characteristics
Waterproof: 0.1-10μm microhole, the aperture is less than 10,000 times water beads, so that water can not pass, effectively protect sensitive parts, avoid liquid erosion, improve product life.
Air permeability: the micropore diameter is 700 times greater than water vapor, waterproof at the same time, allowing air to pass smoothly, can effectively heat dissipation, prevent the inner wall of the product fog, balance the internal and external space pressure.
Dust prevention: The microporous channel forms a mesh three-dimensional structure in the film, and the uniform and dense distribution of micropores makes the dust encounter barrier, so as to achieve effective dust prevention effect, and the minimum can capture 0.1μm particles.