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US 4,375,718 AGranted
Method of making fibrous electrets
AssigneeSurgikos, Inc.
InventorsLarry C. Wadsworth, Solomon P. Hersh
Life of this patent
Estimating the term…
Abstract
A process of manufacturing an electrostatically charged filtration medium is disclosed. A web made of nonconductive thermoplastic fibers is contacted on each side with a more conductive web to form a combined web. The combined web is charged with electrically charged particles from corona charging elements on opposite sides of the web. The charging elements are operated at a voltage of from 5 to 25 kV but with opposite polarity.
Claims17
A process of making a filtration web comprising:
- joining a fibrous conductive web to each surface of a web of filtration medium,
- the web of filtration medium comprising thermoplastic fibers having a diameter of from 0.3 to 80 microns,
- charging one surface of the joined web with electrically charged particles from a pair of corona charging elements with a first corona charging element connected to a voltage of from 5 to 25 kV,
- charging the opposite surface of the joined web with electrically charged particles with a second corona charging element connected to a voltage of from 5 to 25 kV but with the opposite polarity as that of the first element.
1 more element
A process of applying a permanent electrostatic charge by corona charging to a dielectric fiber web,
- joining a contact web, which is more conductive than said dielectric fiber web, to each surface of said dielectric fiber web to form a combined web,
- moving the combined web between a first pair of corona discharge elements which are charged with a voltage of from 5 to 25 kV but with the discharge elements having opposite polarity,
- maintaining the combined web in the corona of the corona discharge elements for from 0.01 to 1 seconds to produce a permanent charge on said dielectric fiber web.
Dependencies are inferred from the claim text.