Method for manufacturing an electret filter medium
AssigneeMinnesota Mining and Manufacturing Company
InventorsPetrus T. A. Klaase, Jan van Turnhout
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Abstract
The present invention relates to a continuous method for manufacturing an electret filter medium from dielectric material having an open or porous structure, said method comprising the steps of continuously feeding a web of dielectric material with a substantially closed dielectric foil adjacent to at least one major face thereof into a corona discharge device, reducing the thickness of the web of dielectric material and charging the web of reduced thickness dielectric material by means of a corona discharge and to apparatus for carrying out said method.
Claims21
A method for manufacturing an electret filter medium from a dielectric material with an open or porous structure, comprising the steps of:
- continuously feeding a web of said dielectric material with a substantially closed non-fibrous dielectric foil adjacent to at least one major face thereof into a corona discharge device;
- reducing the thickness of said web of dielectric material to achieve upon charging a web of superior filtration efficiency;
- and
- charging said web of reduced thickness dielectric material by means of a corona discharge.
Dependencies are inferred from the claim text.