Polytetrafluoroethylene (PTFE), commonly known as "the plastic king", is a high polymer derived from the polymerization of tetrafluoroethylene monomer. It is a white wax-like, semi-transparent material with excellent heat resistance and cold resistance, and can be used for a long time at -180 to 260°C. This material has the characteristics of acid and alkali resistance, and resistance to various organic solvents, and is almost insoluble in all solvents.
PTFE composite fabric, also known as "breathable fabric" or "the second skin of human beings", has successfully solved the longstanding problem of being unable to achieve both waterproofness and air permeability. This high-tech product that combines waterproofness, air permeability, wind resistance, and warmth not only increases the comfort of wearing, but also undoubtedly enhances the product level and added value. Currently, due to structural deficiencies, this composite fabric is mainly used in product fabrics, but it has also been successfully used in thermal clothing and other fields.
microporous membrane has the following characteristics:
The hydrostatic pressure resistance of microporous membrane can reach about 20,000 mm of water column (that is, only when the pressure is greater than 20 meters of water column can it penetrate). The waterproof degree of general waterproof nylon is only 1000-2000 mm, which can only withstand light rain. The slightly better polytetrafluoroethylene membrane can withstand heavy rain of 5000mm, and the U.S. military standard is only 7000mm.
The pore size of the micro-pores in the microporous membrane is 1/1000-1/20000 of the diameter of water droplets. At the same time, the PTFE surface energy is low and naturally hydrophobic, so that even the smallest raindrops cannot pass through the micropores of the film. The pore diameter of the film is about 0.2μm, the diameter of drizzle is 400μm, the diameter of heavy rain is about 3000μm, and the diameter of torrential rain is over 6000μm.
The micro-pores are stacked and nested. When the wind touches the surface of the film and encounters resistance, it will change direction or bounce back, making it difficult for air to penetrate. Therefore, the external airflow cannot come into contact with the human body, effectively preventing air convection. Tests have shown that in winds of 25m/s, the warm-keeping effect of laminated fabrics is 30%-40% higher than that of traditional down jackets, making them highly sought-after by PTFE membrane suppliers.
The microporous membrane has a mesh-like, multi-layered micro-porous structure. Human sweat belongs to gas, and gas molecules are very small and can pass through the micropores to the outside world. Therefore, it has super strong air permeability. The moisture permeability of general waterproof and breathable fabrics is only 2000-3000g/㎡24hr (that is, 85-125g of water vapor can pass through every hour per square meter). The moisture permeability measured by the film micropores is more than 32 liters per day, which is more than ten times that of commonly used fabrics. The pore diameter of the microporous membrane is about 0.2μm, the diameter of water vapor molecules is 0.0004μm, and the pore diameter is hundreds of times larger than that of water vapor molecules. At the same time, there is a temperature difference inside and outside the film and a concentration difference driving factor, so that sweat vapor can easily pass through the micropores, and the vapor can be discharged out of the body, keeping the body dry and comfortable.