Method of making a fibrous electret web using a nonaqueous polar liquid

Abstract

A method of charging fibrous webs with nonaqueous polar liquids. A web 20 that contains nonconductive fibers is wetted with a nonaqueous polar liquid 14. The web 20 is then substantially dried 22 to provide a fibrous electret web. The fibrous electret web can be used as a filter in a filtration face mask 40 that is adapted to cover the nose and mouth of the wearer. The present method has the advantage over known charging methods in that the nonaqueous liquid requires less energy for drying than is required for aqueous liquids. Additionally, many filter webs can be directly wetted with nonaqueous liquids, which cannot be easily wetted with aqueous liquids.

Dependencies are inferred from the claim text.