Low defect nanotube application solutions and fabrics and methods for making same

• US 9,650,732 B2
• Filed: 04/30/2014
• Issued: 05/16/2017
• Est. Priority Date: 05/01/2013
• Status: Active Grant

• Current Assignee: Jason M. Tommey, Sally Smith, ZEON Corporation
• Original Assignee: Nantero Incorporated
• Inventors: Bengtson, Thomas R., Kocab, J. Thomas, Smith, Billy, Roberts, David A., Hosic, Sanjin, Sen, Rahul, Sites, Peter
• Primary Examiner(s): Jolley, Kirsten
• Application Number:
  US14/265,602
• Publication Number:
  US 20140329430A1
• Time in Patent Office: 1,112 Days
• CPC Class Codes: B01D 19/0005 with one or more auxiliary substances
• CPC Class Codes: B01D 19/0031 by filtration
• CPC Class Codes: B01D 19/0036 Flash degasification the other groups take precedence
• CPC Class Codes: B01D 19/0057 the centrifugal movement being caused by a vortex, e.g. using a cyclone, or by a tangential inlet
• CPC Class Codes: B01D 19/0078 by vibration
• CPC Class Codes: B05C 13/02 for particular articles
• CPC Class Codes: B05C 19/06 Storage, supply or control of the application of particulate material; Recovery of excess particulate material
• CPC Class Codes: B05C 9/10 the auxiliary operation being performed before the application B05C9/14 takes precedence
• CPC Class Codes: B05D 1/005 Spin coating
• CPC Class Codes: B05D 3/002 Pretreatement
• CPC Class Codes: B05D 3/12 by mechanical means
• CPC Class Codes: B05D 7/24 for applying particular liquids or other fluent materials
• CPC Class Codes: D04H 1/4242 Carbon fibres
• CPC Class Codes: D04H 1/732 by fluid current, e.g. air-lay
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: Y10S 977/845 Purification or separation of fullerenes or nanotubes
• CPC Class Codes: Y10S 977/892 Liquid phase deposition
• CPC Class Codes: Y10T 442/60 Nonwoven fabric [i.e., nonwoven strand or fiber material]

Abstract

The present disclosure provides methods for removing defects nanotube application solutions and providing low defect, highly uniform nanotube fabrics. In one aspect, a degassing process is performed on a suspension of nanotubes to remove air bubbles present in the solution. In another aspect, a continuous flow centrifugation (CFC) process is used to remove small scale defects from the solution. In another aspect, a depth filter is used to remove large scale defects from the solution. According to the present disclosure, these three methods can be used alone or combined to realize a low defect nanotube application solutions and fabrics.

Claims

1. A method for forming a low defect, uniform nanotube fabric comprising:

contacting a plurality of nanotubes with a liquid medium to obtain a mixture;

purifying said mixture to obtain a purified nanotube solution;

degassing said purified nanotube solution;

performing at least one additional defect reduction processing step on said purified nanotube solution; and

depositing said purified nanotube solution over a material layer to form a nanotube fabric layer

wherein said step of degassing is performed immediately prior to said at least one additional defect reduction processing step; and

wherein said purified nanotube solution remains in a degassed state during said at least one additional defect reduction step.

2. The method of claim 1 wherein said at least one additional defect reduction processing step includes at least one of a degassing process, a continuous flow centrifugation process, a batch centrifugation process, and a depth filter.

3. The method of claim 1 wherein at least one of said at least one defect reduction processing step is repeated at least once.

4. The method of claim 1 wherein said step of degassing prevents the formation of nanotube clumps during the steps of performing, and depositing.

5. The method of claim 1 wherein said one additional defect reduction processing step removes small scale defects from said purified nanotube solution.

6. The method of claim 5 wherein small scale defects are elements within said purified nanotube solution on the order of 100 nanometers to on the order of 300 nanometers.

7. The method of claim 1 wherein said one additional defect reduction step removes large scale defects from said purified nanotube solution.

8. The method of claim 7 wherein large scale defects are elements within said nanotube application solution greater than 2 microns.

9. The method of claim 7 wherein large scale defects are elements within said nanotube application solution greater than 10 microns.

10. The method of claim 7 wherein large scale defects are elements within said nanotube application solution greater than 20 microns.

11. The method of claim 1 wherein said nanotube fabric layer is uniform and substantially free of defects.

12. The method of claim 1 wherein said nanotube fabric layer is substantially free of defects having a diameter of greater than about 2 microns.

13. The method of claim 1 wherein said nanotube fabric layer is substantially free of defects having a diameter of greater than about 10 microns.

14. The method of claim 1 wherein said nanotube fabric layer is substantially free of defects having a diameter of greater than about 20 microns.

15. The method of claim 1 wherein said step of purifying comprises at least one of an acid oxidation process, a cross-flow filtration process, an ion exchange process, and a centrifugation process.

16. The method of claim 15 wherein at least one of said acid oxidation process, said cross-flow filtration process, said ion exchange process, and said centrifugation process is repeated at least once.

17. The method of claim 1 wherein said nanotubes comprise conductive nanotubes.

18. The method of claim 1 wherein said nanotubes comprise semiconductive nanotubes.

19. The method of claim 1 wherein said nanotubes comprise single-walled carbon nanotubes.

20. The method of claim 1 wherein said nanotubes comprise multi-walled carbon nanotubes.

21. The method of claim 1 wherein said purified nanotube solution comprises nanotubes at a concentration of greater than 100 mg/L.

22. The method of claim 1 wherein said purified nanotube solution comprises nanotubes at a concentration of greater than 1000 mg/L.

23. The method of claim 1 wherein said liquid medium is water.