METHOD OF PRODUCING ELECTRET FINE FIBROUS FILTER MEDIUM FOR RESPIRATORS Russian patent published in 2003 - IPC

FIELD: development of polymer fine fibrous filter media featuring stable electret effect. SUBSTANCE: invention is based on method of aerodynamic spraying of polymer melt and provides for use of initial fiber-forming material in the form of granulated polypropylene with index of melt fluiding of 25-35 g/10 min, use of spinneret, combination of spinning and electrification of fibers in one in one process cycle and supply of material for rolling mechanisms. Fibers at stage of hot melt entrained by compressed air flow at pressure of 1.5-3 atm are subjected to electrification in corona discharge at voltage of 5-12 kV/cm that facilitates imparting of stable electret charge to material. Produced filter medium possesses high activity relative to filtered medium (effective surface density of electret charge is 15-20 nC/sq.cm) that enhances its working properties and provides conditions for highly effective filtration of air media by mechanism of volumetric catching and electrostatic attraction. EFFECT: higher productivity of process. 4 dwg, 2 tbl