The greater the resistance of the melt blown cloth, the better? Don't be fooled.
The filtration performance of meltblown cloth is not achieved by resistance. The greater the resistance of the meltblown cloth, the better the filtering effect is without any basis.
On the contrary, the resistance of masks produced by melt blown cloth is required by standards, because too much resistance will cause breathing difficulties, so a good melt blown cloth has low resistance and high filtration efficiency.
The filtering mechanism of medical masks is Brownian diffusion, retention, inertial collision, gravity sedimentation and electrostatic adsorption. The first four are all physical factors, which are the natural characteristics of the non-woven fabric produced by the meltblown method. The filterability is about 35%; this does not meet the requirements of medical masks. We need to electret the material to make the fiber Be charged and use static electricity to capture the aerosol where the new coronavirus is located.
The electret treatment electrostatic adsorption is to capture 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), and the inspiratory resistance of civilian masks is less than 135 Pascals (Pa).
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