초록 ▼

There is provided a method for forming a nonwoven electret fiber filter 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 a

There is provided a method for forming a nonwoven electret fiber filter 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.

대표청구항 ▼

[ I claim:] [1.] A method for forming an electret nonwoven filter web comprising the steps of:a) providing at least one nonwoven filter web;b) joining the at least one filter web to a reinforcement scrim said reinforcement scrim having discrete open areas where the average cross-sectional area in th

[ I claim:] [1.] A method for forming an electret nonwoven filter web comprising the steps of:a) providing at least one nonwoven filter web;b) joining the at least one filter web to a reinforcement scrim said reinforcement scrim having discrete open areas where the average cross-sectional area in the plane of the filter of the open areas is at least 0.25 mm.sup.2 and said scrim having an overall pressure drop of less than 1.5 mm H.sub.2 O at 98.4 meters/min;c) needle punching the at least one filter web and reinforcement scrim to form a filter; andd) providing at least some of the filter fibers of the filter web with electret charges.