Electret filter media containing filtration enhancing additives
AssigneeMinnesota Mining and Manufacturing Company
InventorsAlan D. Rousseau, Marvin E. Jones, Seyed A. Angadjivand
Life of this patent
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Abstract
Electret filter media comprising a fibrous web of a blend of a thermoplastic resin and at least one compound or oligomer that enhances the web's electret properties.
Claims30
Electret filter media that comprises a fibrous web that contains fibers that comprise a thermoplastic resin and at least one compound or oligomer, which compound or oligomer is
- (a) a short-chain tetrafluoroethylene telomer, ##STR25## wherein R.sub.f is a perfluorinated moiety that may contain one or more catenary ether oxygen atoms, Q is a linking group selected from alkylene groups having 1 or 2 carbon atoms, sulfonamido groups or combinations thereof, R is an alkyl group, R.sup.1 is a perfluoroalkyl group, R.sup.2 is an alkyl group that may be straight chain or branched, and n is a number of from 2 to 40,
- the web having sufficient electric charge to exhibit improved filtration efficiency over a web having no compound or oligomer.
Electret filter media that comprises a fibrous web that includes a blend that comprises a thermoplastic non-conductive polymer and at least one compound or oligomer which compound or oligomer is
- (a) a short-chain tetrafluoroethylene telomer, ##STR26## wherein R.sub.f is a perfluorinated moiety having 3 to 20 carbon atoms and which may contain one or more catenary ether oxygen atoms, Q is a linking group selected from alkylene groups having 1 or 2 carbon atoms, sulfonamido groups, or combinations thereof, R is an alkyl group having 1 to 4 carbon atoms, R.sup.1 is a perfluoroalkyl group having 1 to 4 carbon atoms, R.sup.2 is an alkyl group that may be straight chain or branched and that has 4 to 10 carbon atoms, and n is a number of from 2 to 40,
- the web having sufficient charge to exhibit improved filtration efficiency over a web having no compound or oligomer, the charge being imparted to the web at least by contacting the web with water at a pressure sufficient to impart the charge.
A fibrous electret filter media that comprises fibers formed from a blend that comprises a nonconductive thermoplastic resin and an additive that is:
- (a) a thermally stable organic compound or oligomer that contains at least one perfluorinated moiety;
- (b) a thermally stable organic triazine compound or oligomer, which compound or oligomer contains at least one nitrogen atom in addition to those in the triazine group;
- or
- (c) a combination thereof;
- the electret charge being imparted to the fibrous electret material by contacting the fibers with water at a pressure sufficient to impart the electric charge.
Dependencies are inferred from the claim text.