Method for producing carbon nanotube sheet and carbon nanotube sheet

• US 10,562,775 B2
• Filed: 11/20/2015
• Issued: 02/18/2020
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: Kinki University, Lintec Corporation, Lintec of America Incorporated (Lintec Corporation)
• Original Assignee: Lintec Corporation
• Inventors: Ovalle, Raquel, Tanaka, Senku, Inoue, Kanzan
• Primary Examiner(s): Miller, Daniel H
• Application Number:
  US15/527,632
• Publication Number:
  US 20170362089A1
• Time in Patent Office: 1,551 Days
• Field of Search: 428408, 423448
• CPC Class Codes: B32B 37/14 characterised by the properties of the layers
• CPC Class Codes: B32B 9/00 Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
• CPC Class Codes: B32B 9/04 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a glass layer B32B17/06; layered products with at least two ceramic layers composed mainly of ceramic B32B18/00
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2202/08 Aligned nanotubes
• CPC Class Codes: C01B 2202/22 Electronic properties
• CPC Class Codes: C01B 32/168 After-treatment
• CPC Class Codes: C01P 2006/10 Solid density
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/842 for carbon nanotubes or fullerenes
• CPC Class Codes: Y10S 977/932 for electronic or optoelectronic application

Abstract

The present invention provides a method for producing a carbon nanotube sheet that is excellent in light transmittance and conductivity, and the carbon nanotube sheet. The method includes firstly modifying of modifying a free-standing unmodified carbon nanotube sheet in which a plurality of carbon nanotubes are aligned in a predetermined direction. The firstly modifying includes performing a densification process of bringing the unmodified carbon nanotube sheet into contact with either one of or both of vapor and liquid particles of a liquid substance to produce a modified carbon nanotube sheet that contains the carbon nanotubes which are mainly aligned in a predetermined direction, and that includes a high density portion where the carbon nanotubes are assembled together and a low density portion where density of the carbon nanotubes is relatively lower than density in the high density portion.

Claims

1. A method for producing a carbon nanotube sheet, the method comprising:

firstly modifying of modifying a free-standing unmodified carbon nanotube sheet in which a plurality of carbon nanotubes are aligned in a predetermined direction, wherein the firstly modifying includes

performing a densification process of bringing the unmodified carbon nanotube sheet into contact with liquid particles of mist of a liquid substance to produce a modified carbon nanotube sheet that contains the carbon nanotubes which are mainly aligned in a predetermined direction, and that includes a high density portion where the carbon nanotubes are assembled together and a low density portion where density of the carbon nanotubes is relatively lower than density in the high density portion,

wherein at least one layer of the unmodified carbon nanotube sheet is further stacked on at least one layer of the modified carbon nanotube sheet,

wherein a first orientation direction of the carbon nanotubes of the at least one unmodified carbon nanotube sheet and a second orientation direction of the carbon nanotubes of the at least one modified carbon nanotube sheet are oriented in substantially the same direction, whereby substantially the same direction includes displacements between the first orientation direction and the second orientation direction within a range of 15°

or smaller,

wherein the liquid particles have a size of 200 μ

m or smaller, and

wherein the liquid particles are formed as either one of or both of an aerosol of the liquid substance and the liquid substance ejected by ink-jetting.

4. The method for producing a carbon nanotube sheet according to claim 1, wherein the liquid substance is an organic solvent.

5. The method for producing a carbon nanotube sheet according to claim 4, wherein the organic solvent is an alcohol compound.

6. The method for producing a carbon nanotube sheet according to claim 5, wherein the alcohol compound is at least one selected from the group consisting of methanol, ethanol, and isopropyl alcohol.

7. A carbon nanotube sheet produced by the method for producing a carbon nanotube sheet according to claim 1.

8. The carbon nanotube sheet according to claim 7, wherein the carbon nanotube sheet has a light transmittance of 70% or more.

9. The carbon nanotube sheet according to claim 7, wherein the carbon nanotube sheet has a resistance of 500 Ω

/square or less.

10. The carbon nanotube sheet according to claim 9, wherein the carbon nanotube sheet has the light transmittance of 70% or more and a resistance of 500 Ω

/square or less.

11. The method for producing a carbon nanotube sheet according to claim 1, further comprising:

secondly modifying the stacked assembly by a densification process in which the stacked assembly is brought into contact with liquid particles of the liquid substance.

12. The method for producing a carbon nanotube sheet according to claim 1, wherein the free-standing unmodified carbon nanotube sheet comprises at least two unmodified carbon nanotube sheets stacked on each other prior to the modifying.

2. A method for producing a carbon nanotube sheet, the method comprising:

firstly modifying of modifying a free-standing unmodified carbon nanotube sheet in which a plurality of carbon nanotubes are aligned in a predetermined direction, wherein the firstly modifying includes performing a densification process of bringing the unmodified carbon nanotube sheet into contact with liquid particles of mist of a liquid substance to produce a modified carbon nanotube sheet that contains the carbon nanotubes which are mainly aligned in a predetermined direction, and that includes a high density portion where the carbon nanotubes are assembled together and a low density portion where density of the carbon nanotubes is relatively lower than density in the high density portion; and

stacking at least two layers of the modified carbon nanotube sheets to prepare a stacked assembly of the carbon nanotube sheets,

wherein a first orientation direction of the carbon nanotubes of at least one modified carbon nanotube sheet and a second orientation direction of the carbon nanotubes of at least one modified carbon nanotube sheet are oriented in substantially the same direction, whereby substantially the same direction includes displacements between the first orientation direction and the second orientation direction within a range of 15°

or smaller,

wherein the liquid particles have a size of 200 μ

m or smaller, and

wherein the liquid particles are formed as either one of or both of an aerosol of the liquid substance and the liquid substance ejected by ink-jetting.

3. The method for producing a carbon nanotube sheet according to claim 2, wherein at the stacking step, the stacked assembly of the carbon nanotube sheets is prepared by stacking 2 to 25 layers of the modified carbon nanotube sheets.

13. The method for producing a carbon nanotube sheet according to claim 2, further comprising:

secondly modifying the stacked assembly by a densification process in which the stacked assembly in a free-standing state is brought into contact with liquid particles of the liquid substance.