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US 4,178,157 AGranted
Method for manufacturing a filter of electrically charged electret fiber material and electret filters obtained according to said method
AssigneeN. V. Verto
InventorsJan van Turnhout, Johannes C. Rieke
Life of this patent
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Abstract
A method for forming a filter of electrically charged electret fiber material, consisting of a high molecular weight, nonpolar polymeric substance, comprising drawing, charging, and fibrillating a foil of said high molecular weight substance. The fibrillated foil is wound and then crimping is effected.
Claims6
A method for manufacturing a filter of electrically charged electret fiber material, consisting of a high-molecular weight, non-polar polymeric substance, comprising the steps of:
- continuously supplying a foil of said substance, drawing, charging and fibrillating of the foil and the processing of the thus obtained filter material into a filter, selecting the foil and/or the type of drawing to manufacture spontaneously crimpable fiber material, winding said material in uncrimped condition to a fibrous package and subsequently effecting crimping to interlock the fibers of said fibrous package.
Dependencies are inferred from the claim text.