Filtration principle of meltblown cloth. The main material of melt-blown nonwoven fabric is polypropylene, which is an ultra-fine electrostatic fiber cloth that can capture dust. When the droplets containing pneumonia virus are close to the melt-blown nonwoven fabric, they will be electrostatically adsorbed on the surface of the nonwoven fabric and cannot penetrate. This is the principle that this material isolates germs. After dust is captured by superfine electrostatic fiber, it is difficult to separate it by cleaning, and washing will also destroy the electrostatic dust collection ability. So this mask can only be used once.
Melt-blown nonwovens need to add a trace substance called electret, which is easy to carry static electricity. Non-woven fabrics can be charged for a long time by corona discharge of electrostatic electret equipment.
Fixed electrode treatment. Electret is a kind of dielectric material with long-term charge storage function, which has the advantages of high efficiency, low flow resistance, antibacterial and energy saving. On the basis of ensuring the physical collision barrier effect of conventional filter materials, the electrostatic adsorption effect is increased. Electret treatment makes the fibers of filter material charged, and a large number of electrodes are formed between charged fibers in combination with the dense characteristics of melt-blown superfine fiber materials. Charged fibers can not only attract most charged particles in the environment like magnets, but also polarize some uncharged particles, thus adsorbing some pollutants with smaller particle size, and even nano-scale substances such as viruses can be electrostatically adsorbed or blocked by charge repulsion.