Patent ID: 6858297

Claim:
A method of making a fibrous filtration web, which method comprises: a) melt-blowing a fiber-forming thermoplastic material through an array of nozzles in the presence of a primary fluid stream to form a plurality of filaments that are attenuated into fibers and directed towards a porous collection surface having a direction of motion; b) impinging at least one secondary fluid stream upon the filaments or fibers to oscillate the fibers generally in and against the direction of motion; and c) collecting the fibers on the porous collection surface to form a nonwoven meltblown web wherein the secondary fluid stream causes the fibers to oscillate sufficiently so that a majority of the collected fibers are aligned within ±20° of the direction of motion, and wherein in a web that has not been heat treated, fibers having lengths of about 1 to about 10 cm can be teased from the web.