The invention relates to a multilayer
electret nanofiber filtering material and a preparation method thereof. The invention adopted the technical scheme is as follows: through an electric-field stepped increasing / reducing technology, utilizing a combined needle head for electrostatic
spinning to realize deposition of
spinning polymer solution on a receiving substrate to obtain
nanofiber, carrying out slight dissolving treatment on the surface of a
nanofiber layer by a certain release rate by adopting a
recovery solvent steam, wherein the nanofiber layer is uniformly filled with
electret materials and the
diameter of the nanofiber layer is distributed in a stepped-increasing or stepped-reducing manner along the direction vertical to the breadth. According to the multilayer
electret nano-
fiber filtering material, the electret charge stability is extremely high, the surface electrostatic potential is 250-7000V, simultaneously the filtering performance is excellent, the filtering efficiency for 0.03-10 microns
particulates is more than 99.997%, the resistance pressure drop is less than or equal to 39Pa, the service life is long, and the development and application prospect in the aspect of filtering materials for
air purifiers, window gauzes, masks and filtering papers and the like are wide.