Electrostatic fibrous filter web
AssigneeMinnesota Mining and Manufacturing Company
InventorThomas E. Haskett
Life of this patent
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Abstract
There is provided a nonwoven electret fiber filter formed with a nonwoven web of electret fibers needle-punched to an open scrim support. The scrim support material has individual discrete open areas with an average cross-sectional area as viewed from the plane of the filter media of at least 0.25 mm.sup.2, preferably 1.0 mm.sup.2, and a pressure drop across the scrim support, without the filter web, of less than 1.5 mm H.sub.2 O measured at 98.4 meters/min gaseous face velocity. The resulting filter has enhanced lifetimes, a low pressure drop and high filtration efficiencies.
Claims20
An electret fiber nonwoven filter media comprising at least one nonwoven filter web comprising entangled fibers, at least some of which are electrostatically charged electret fibers, wherein the web is joined to at least one reinforcement scrim by needle-punching, said reinforcement scrim having discrete open areas where the average open area has a cross-sectional area of at least 0.25 mm.sup.2 and the reinforcement scrim has an overall pressure drop of less than 2.0 mm H.sub.2 O at 98.4 meters/min, wherein said open areas extend from one face to the opposite face of the scrim in a non-tortuous path.
Dependencies are inferred from the claim text.