Abstract: A filtration medium is disclosed for use in air filters used in heating, ventilating and air conditioning systems. The medium contains at least one nanofiber layer of fibers having diameters less than 1 ?m and at least one carrier layer, each nanofiber layer having a basis weight of at least about 2.5 g/m2, and up to about 25 g/m2. The medium has sufficient stiffness to be formed into a pleated configuration.

Abstract: The present invention is directed to a method for preparing a nanofiber web by feeding a polymer solution, which has at least one polymer dissolved in at least one flammable solvent to a spinning nozzle, discharging the polymer solution from the spinning nozzle into a blowing gas or gas mixture that will not support combustion, wherein the blowing gas exits a jet at a lower end of the spinning nozzle, to form polymer nanofibers and collecting the polymer nanofibers on a collector under the spinning nozzle, wherein an applied high voltage differential is maintained between the spinneret and the collector.

Abstract: Filtration media are disclosed for use in high efficiency air filters for filtering particulate matter in air. The media make use of at least one layer of fibers having a diameter less than 1000 nanometers sandwiched between two scrim layers to achieve high efficiency particulate air (HEPA) filtration performance at relatively low pressure drops.