Patent ID: 7622063

Claim:
A method of making a pleated filter element, which method comprises: extruding molten polymer through a melt-blowing die to form melt-blown fibers and collecting the melt-blown fibers on a moving collector to form a nonwoven filtration web, with the melt-blown fibers passing, prior to being collected on the moving collector, through a secondary quench air zone comprising opposing air streams one of which is aligned in the direction of motion of the collector and the other of which is aligned opposite the direction of motion of the collector, forming rows of spaced-apart pleats in the nonwoven filtration web; and cutting the pleated web to a desired size and shape to form a self-supporting pleated, continuous filter element comprising rows of oppositely facing pleats; wherein the volume and velocity of the opposing air streams are such that a majority of the melt-blown fibers in the pleated filter element are aligned at 90°±20° with respect to the row direction of the pleats.