Method of making electrets through vapor condensation
Assignee3M Innovative Properties Company
InventorsThomas I. Insley, Randall L. Knoll
Life of this patent
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Abstract
A method of making an electret includes condensing vapor from the atmosphere of a controlled environment onto a dielectric article and then drying the article to remove the condensate. The dielectric article may be a nonconductive polymeric material, and the condensate may include a polar liquid. The method is particularly useful for forming an electret from a porous material such as a nonwoven fibrous web. The method can enable individual fibers in the web to exhibit at least quasi-permanent electrical charge.
Claims25
A method of making an electret comprising:
- altering at least one property of a controlled environment so as to cause the vapor of the atmosphere of the controlled environment to condense on a dielectric article having a resistivity of greater than 1014 ohms-cm, said property being selected from the group consisting of volume, pressure or temperature of the controlled environment;
- and
- drying the article.
A method of making an electret, which method comprises:
- placing a dielectric article in a liquid of a controlled environment;
- condensing vapor from the atmosphere of the controlled environment onto the dielectric article to form a condensate thereon;
- decreasing the pressure on the atmosphere of the controlled environment such that at least a portion of the liquid evaporates into the atmosphere;
- and then
- drying the article.
A method of making an electret, which method comprises:
- altering a first property of a controlled environment comprising atmosphere and liquid such that at least a portion of the liquid evaporates into the atmosphere to form vapor;
- altering a second property of the environment such that the vapor condenses on the surface of a dielectric article;
- and then
- drying the article.
A method of making an electret, which method comprises:
- condensing vapor from the atmosphere of a controlled environment onto a dielectric article to form a condensate thereon, said condensing comprising increasing the pressure on the atmosphere of the controlled environment such that the vapor condenses on the article;
- and then
- drying the article.
A method of making an electret, which method comprises:
- condensing vapor from the atmosphere of a controlled environment onto a dielectric article by an adiabatic expansion to form a condensate on the dielectric article;
- and then
- drying the article.
A method of making an electret, which method comprises:
- altering the volume of a controlled environment that comprises atmosphere and liquid such that at least a portion of the liquid evaporates into the atmosphere to form vapor;
- altering the volume of the environment such that the vapor condenses on the surface of a dielectric article;
- and then
- drying the article.
A method of mating an electret comprising:
- altering a first property of a controlled environment of a chamber such that at least a portion of a liquid in the controlled environment evaporates into the atmosphere;
- altering at least one second property of the controlled environment so as to cause vapor of the atmosphere of the controlled environment to condense on a dielectric article having a resistivity of greater than 1014 ohms-cm, said dielectric article being disposed in said controlled environment;
- and
- drying the article to remove the condensate, wherein the electret exhibits a persistent electric charge.
Dependencies are inferred from the claim text.