Micron is a magical unit. The diameter of an oxygen molecule is 0.346 nanometers, and oxygen can pass through smoothly. The diameter of a new coronavirus is about 100 nanometers, which is 0.1 micrometers, which is smaller than PM2.5 (particulate matter below 2.5 micrometers). At this time, the meltblown non woven fabric Like a net, passing through this layer of cloth is a piece of cake for a 0.1 micron virus.
The non-electret meltblown cloth virus can easily pass through, and the filtering effect is very limited, and it can only filter the air droplets.
The electret treatment electrostatic adsorption is to achieve the capture of the new coronavirus droplets (aerosols) through the Coulomb force of the charged fibers. The principle is to make the surface of the filter material more open, the ability to capture particles can be grabbed, and the charge density increases, and the adsorption and polarization effects of particles are stronger. Therefore, the meltblown non woven filter material of the filter layer must be passed through extreme treatment can achieve 95% filterability without changing the respiratory resistance to effectively prevent viruses. Masks must achieve the barrier effect while ensuring comfortable ventilation. The inhalation resistance of medical masks generally does not exceed 343.2 Pascals (Pa ), the inhalation resistance of civilian masks is less than 135 Pascal Pa). Electret treatment can greatly improve the filtration efficiency without changing the breathing resistance, and the higher the electret voltage, the higher the material filtration efficiency. Generally, the electret voltage is required to be 30Kv-60kv.