Remote fluorination of fibrous filter webs

Patent metadata

Field	Value
Publication number	US-10464001-B2
Application number	US-201615357889-A
Country	US
Kind code	B2
Filing date	Nov 21, 2016
Priority date	Apr 3, 2009
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

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 C 3 F 4 H + to C 2 F 5 + 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.

First claim

What is claimed is:

1. An electret article that comprises:
a nonwoven web that comprises melt-blown fibers that contain polypropylene and that have fluorine atoms on the surfaces of the melt-blown fibers in the web such that the electret article has (a) an atomic % fluorine greater than 40%, (b) a ToF-SIMS C 3 F 4 H + to C 2 F 5 + ratio that is greater than 0.3 and that is above a Remote Fluorination Threshold RFT1 line for the atomic % fluorine, (c) a fluorosaturation ratio in a range of about 270 to about 413, and (d) does not contain heteroatoms.

2. The electret article of claim 1 , wherein the polypropylene melt-blown fibers are microfibers that have an effective fiber diameter of 1 to 10 μm and that have a volume resistivity of 10 14 ohm-cm or greater, and wherein the article exhibits a QF of at least about 2 and a Q 9 of 1.5/mm H 2 O.

3. The electret article of claim 2 , wherein the ToF-SIMS C 3 F 4 H + to C 2 F 5 + ratio is above an RFT2 line.

4. The electret article of claim 2 , wherein the ToF-SIMS C 3 F 4 H + to C 2 F 5 + ratio is above an RFT3 line.

5. A filter that comprises the electret article of claim 1 .

6. A respirator that comprises the filter of claim 5 .

7. The electret article of claim 1 , wherein the article exhibits a Q 9 of at least 1.6/mm H 2 O.

8. The electret article of claim 1 , wherein the article exhibits a Q 9 of at least 1.8/mm H 2 O.

9. The electret article of claim 1 , wherein the article has an atomic % fluorine of greater than 42%.

10. The electret article of claim 1 , wherein the article has an atomic % fluorine of greater than 45%.

11. The electret article of claim 1 having a ToF-SIMS C 3 F 4 H + to C 2 F 5 + ratio of at least about 0.4.

12. The electret article of claim 1 having a basis weight of 20 to 150 g/m 2 , a solidity of 3 to 10%, and a thickness of 0.5 to 2 mm.

13. The electret article of claim 1 , wherein the article has a fluorosaturation ratio of 332 or greater.

14. The electret article of claim 1 , wherein the article has a fluorosaturation ratio of 372 or greater.

Assignees

• 3M Innovative Properties Co

Inventors

• Kirk Seth M
• Jones Marvin E
• Pachuta Steven J
• Chen Andrew W
• Klinzing William P
• Sager Patrick J

Classifications

• B03C7/006

  Charging without electricity supply, e.g. by tribo-electricity or pyroelectricity · CPC title

• B01D2239/0627

  Spun-bonded · CPC title

• B01D2239/025

  comprising nanofibres · CPC title

• D06M2200/00

  Functionality of the treatment composition and/or properties imparted to the textile material · CPC title

• B03C3/64

  synthetic resins · CPC title