High efficiency synthetic filter medium
Assignee3M Innovative Properties Company
InventorsTien Wu, Richard Kinderman, Seyed Angadjivand
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Abstract
A high efficiency filtration medium comprised of a nonwoven filter web of electret charged fibers of a nonconductive thermoplastic resin having a resistivity greater than 10.sup.14 ohm-cm, preferably polypropylene. The nonwoven filter web has a basis weight (BW) of less than 60 grams/m.sup.2, an effective fiber diameter (EFD) of less than 5 microns and a penetration (PEN) of less than 0.03%, wherein the ratio); BW/(EFD.PEN) is greater than 200. The invention filter medium can be easily used in applications requiring HEPA performance at relatively low pressure drops.
Claims28
A high efficiency filtration medium comprising nonwoven filter web of electret charged fibers of a nonconductive thermoplastic resin, having a resistivity greater than 10.sup.14 ohm-cm, which nonwoven filter web has a basis weight (BW) of less than 60 grams/m.sup.2, an effective fiber diameter (EFD) of less than about 5 microns and a DOP penetration (PEN) of less than 0.03%, wherein the ratio;
- BW/(EFD.PEN)
- is greater than 200.
Dependencies are inferred from the claim text.