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Assignee3M Innovative Properties Company
InventorsSeth M. Kirk, Marvin E. Jones, Steven J. Pachuta, Andrew W. Chen, William P. Klinzing, Patrick J. Sager
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A method of making a fluorinated fibrous web, which method includes providing a nonwoven web 22 that contains polymeric fibers, creating a plasma that contains fluorine atoms at a first location 14, and contacting the nonwoven web with products from the plasma at a second location 26 remote from the first location 14. The method avoids exposure of the web to the plasma and hence expands the manufacturing processing window. Webs so fluorinated have a different C3F4H+ to C2F5+ ratio when compared to locally fluorinated webs having similar levels of surface fluorination. The remote fluorinated webs can be subsequently charged electrically to provide a good performing electret filter 40 suitable for use in an air purifying respirator 30. Webs fluorinated in accordance with this invention also may exhibit good performance even after being “aged” at high temperatures.
A spun-bond fibrous filtration web comprising bicomponent, fluorinated electret fibers with first and second thermoplastic organic nonconductive polymer components arranged concentrically therein in a sheath-core configuration, wherein the first and second polymer components are chosen from polypropylene and poly-4-methyl-pentene, and wherein the bicomponent, fluorinated electret fibers are hydrocharged, plasma-fluorinated fibers that comprise fluorine atoms on the surfaces of the fibers so as to exhibit greater than 40 atomic % fluorine.
Dependencies are inferred from the claim text.