Methods of saturating nonwoven fabrics with liquid and the making of electret thereof
AssigneeUniversity of Tennessee Research Foundation
InventorPeter Ping-yi Tsai
Life of this patent
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Abstract
A method of preparing an electret by saturating a nonwoven fabric with a liquid, such as water, and removing the liquid via suction to generate charges by friction between the fabric fibers and the liquid is described. The saturating can be carried out, for example, by impinging the bottom side of the fabric with a jet or jets of water while the fabric is being pulled under a solid roller. Excess water can also be applied during a water quenching step of a meltblowing or spunbonding process. An apparatus for preparing an electret according to the presently disclosed methods is also described.
Claims14
A method of making an electret, the method comprising:
- (a) providing a sheet comprising a nonwoven web of thermoplastic fibers;
- (b) passing the sheet under a roller wherein the top surface of the sheet is in contact with the roller while simultaneously impinging the bottom surface of the sheet with one or more jets of water, thereby saturating the sheet with water to provide a saturated sheet;
- and
- (c) removing the water from the saturated sheet via suction to provide a charge, thereby providing an electret.
An apparatus for preparing an electret, said apparatus comprising:
- (i) one or more nozzles and a solid roller, wherein the one or more nozzles are positioned beneath the solid roller and are configured to direct one or more jets of water upward to the solid roller;
- (ii) a vacuum chamber comprising a vacuum port and an opening;
- and
- (iii) a series of rollers configured to transfer a fabric sheet from a first location above the one or more nozzles and under the solid roller to a second location above the opening of the vacuum chamber.
Dependencies are inferred from the claim text.