Simply put, in the production process of melt-blown cloth, certain treatment is carried out to make it become a electret, that is, a dielectric material with long-term charge storage function, with electrostatic charge effect. The treated melt-blown cloth fiber will be charged, forming a large number of electrodes between charged fibers. On the basis of mechanical barrier, the electrostatic adsorption effect is increased. It can not only attract charged particles in the environment like a magnet, but also polarize some uncharged particles, and then absorb some small particle size pollutants. Even nano-scale viruses can be electrostatic adsorbed or charge-repulsive, and the process does not increase the resistance to filtration.
In the specific electret treatment of melt-blown cloth, corona charging method is a widely used method, which uses a uniform electric field to cause local breakdown of air corona discharge to generate ion beam bombardment of the dielectric, and make the ion charge deposited in the dielectric, and the material with charge. In order to increase the comprehensive filtering effect of the melt-blast cloth and maintain charge for a long time, a certain amount of electret masterbatch will be added to the masterbatch for modification during the melt-blast process. In this way, in the process of producing injected charge in melt-blast, the charge will be dispersed in the microfiber porous structure of the melt-blast cloth along with the electret masterbatch to improve the electret efficiency and increase the filtering effect. Of course, in addition to corona charging method and thermal polarization method, triboelectric method and other processing technology.