# US 11,305,997 B2 · Multi-walled carbon nanotube, multi-walled carbon nanotube aggregation, and method for producing the multiwalled carbon nanotube

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- Number: US 11,305,997 B2
- Document ID: US11305997B2
- Status: Granted
- Kind: B2
- Application number: 16/850,737
- Filed: 2020-04-16
- Published: 2020-10-29
- Granted: 2022-04-19
- Earliest claimed: 2019-04-26
- Assignees: Tpr Co., Ltd.
- Applicants: Tpr Co., Ltd.
- Inventors: Toshiaki Shimizu; Shinpei Teshima; Yasuhiko Okamura; Yusuke Kawaguchi; Kazuki Otomo; Yuta Koguchi; Katsuhito Suzuki; Yoshio Bando
- Web page: https://patentgrep.com/patent/US11305997B2

## CPC

- C01B 32/158: Carbon nanotubes
- C01B 32/162: characterised by catalysts
- C01B 2202/06: Multi-walled nanotubes
- C01B 2202/30: Purity
- C01B 2202/34: Length
- C01B 2202/36: Diameter
- C01P 2004/04: obtained by TEM, STEM, STM or AFM
- C01P 2004/133: Multiwall nanotubes
- C01P 2004/30: extending in three dimensions
- C01P 2004/50: Agglomerated particles
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Applicability to a composite material with high purity and high strength, and a material requiring high conductivity or high thermal conductivity is enhanced. The present invention relates to a multi-walled carbon nanotube having two or more tubes of a graphene sheet where carbon atoms are arranged in a hexagonal honeycomb form, coaxially, wherein a diameter of an outermost wall based on observation of an image by a transmission electron microscope is 3 nm or more and 15 nm or less, and a length based on observation of an image of a scanning electron microscope is 1.0 mm or more, an aggregate of multi-walled carbon nanotubes and a method for preparing the multi-walled carbon nanotube.

## Claims

### Claim 1

A multi-walled carbon nanotube having two or more tubes of a graphene sheet where carbon atoms are arranged in a hexagonal honeycomb form, coaxially,
wherein a diameter of an outermost wall is 3 nm or more and 15 nm or less, and a length is 1.0 mm or more, and
wherein a wave where an average period based on observation of an image by a scanning electron microscope is 0.5 μm or more and 2.0 μm or less is formed in a lengthwise direction.

### Claim 2 (depends on 1)

The multi-walled carbon nanotube of claim 1, wherein the diameter of the outermost wall is determined based on observation of an image by a transmission electron microscope, and the length is determined based on observation of an image of a scanning electron microscope.

### Claim 3

A multi-walled carbon nanotube aggregate that is an aggregate of multi-walled carbon nanotubes each having two or more tubes of a graphene sheet where carbon atoms are arranged in a hexagonal honeycomb form, coaxially,
wherein an average diameter of outermost walls is 6 nm or more and 12 nm or less, and an average length is 1.4 mm or more, and
wherein in a lengthwise direction of multi-walled carbon nanotubes in the multi-walled carbon nanotube aggregate, waves where average periods based on observation of an image by a scanning electron microscope are 0.5 μm or more and 2.0 μm or less are formed.

### Claim 4 (depends on 3)

The multi-walled carbon nanotube aggregate of claim 3, wherein a metal content is 250 ppm or less by weight.

### Claim 5 (depends on 3)

The multi-walled carbon nanotube aggregate of claim 3, wherein a metal content is 250 ppm or less by weight.

### Claim 6 (depends on 3)

The multi-walled carbon nanotube of claim 3, wherein the average diameter of the outermost walls is determined based on observation of an image by a transmission electron microscope, and the average length is determined based on observation of an image of a scanning electron microscope.