# US 11,897,770 B2 · Method for producing densified carbon nanotube fiber

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- Number: US 11,897,770 B2
- Document ID: US11897770B2
- Status: Granted
- Kind: B2
- Application number: 17/101,198
- Filed: 2020-11-23
- Published: 2021-10-21
- Granted: 2024-02-13
- Earliest claimed: 2020-04-17
- Assignees: Korea Institute of Science and Technology
- Applicants: Korea Institute of Science and Technology
- Inventors: Hyeon Su Jeong; Seung Min Kim; Sook Young Moon; Dong Myeong Lee
- Web page: https://patentgrep.com/patent/US11897770B2

## CPC

- C01B 32/168: After-treatment
- D01D 5/0046: {the fibre formed by coagulation, i.e. wet electro-spinning}
- D01D 5/06: Wet spinning methods {(D01D5/0046 takes precedence)}
- D01F 9/12: Carbon filaments; Apparatus specially adapted for the manufacture thereof
- C01P 2004/03: obtained by SEM
- C01P 2006/10: Solid density
- D01F 11/10: of carbon
- D06M 7/00: {Treating fibres, threads, yarns, fabrics, or fibrous goods made of other substances with subsequent freeing of the treated goods from the treating medium, e.g. swelling, e.g. polyolefins (D06M10/00 takes precedence; treating fibres or filaments made of glass, mineral -, or slag wool C03C; carbon fibres D01F11/10)}
- D06M 2101/40: Fibres of carbon
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- D06M: TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS

## Abstract

Disclosed is a method for mass-producing densified carbon nanotube fiber. The method includes preparing carbon nanotube fiber, swelling the carbon nanotube fiber by applying an acid solution thereto, and stretching the carbon nanotube fiber, coagulating the stretched carbon nanotube fiber so as to remove the acid solution present therein, and drying the coagulated carbon nanotube fiber.

## Claims

### Claim 1

A method for producing densified carbon nanotube fiber, the method comprising:
preparing carbon nanotube fiber;
swelling the carbon nanotube fiber by applying an acid solution thereto, and stretching the carbon nanotube fiber;
coagulating the stretched carbon nanotube fiber so as to remove the acid solution present therein; and
drying the coagulated carbon nanotube fiber;
wherein in the preparing the carbon nanotube fiber, carbon nanotube fiber having a linear density equal to or greater than 5 tex is prepared, and
in the swelling and stretching the carbon nanotube fiber, the carbon nanotube fiber is stretched to a stretching ratio greater than 80% but less than or equal to 200%.

### Claim 2 (depends on 1)

The method of claim 1, wherein, in the preparing the carbon nanotube fiber, as-spun carbon nanotube fiber is prepared by a direct spinning method.

### Claim 3 (depends on 1)

The method of claim 1, wherein, in the swelling and stretching the carbon nanotube fiber, the carbon nanotube fiber is immersed in the acid solution.

### Claim 4 (depends on 1)

The method of claim 1, wherein the acid solution is one selected from the group consisting of chlorosulfuric acid (HSO3Cl), fluorosulfuric acid (HSO3F), trifluoroacetic acid (CF3COOH), trifluoromethanesulfonic acid (CF3SO3H), fluoroantimonic acid (H2FSbF6), carborane acid, and combinations thereof.

### Claim 5 (depends on 1)

The method of claim 1, wherein, in the swelling and stretching the carbon nanotube fiber, the carbon nanotube fiber is immersed in the acid solution for 1 minute or longer.

### Claim 6 (depends on 1)

The method of claim 1, wherein, in the swelling and stretching the carbon nanotube fiber, the carbon nanotube fiber is stretched to a stretching ratio greater than 100% but less than or equal to 200%.

### Claim 7 (depends on 1)

The method of claim 1, wherein, in the coagulating the stretched carbon nanotube fiber, the stretched carbon nanotube fiber is coagulated by applying a coagulation solution, selected from the group consisting of diethyl ether, fuming sulfuric acid (oleum) and a combination thereof, to the stretched carbon nanotube fiber.

### Claim 8 (depends on 7)

The method of claim 7, wherein the coagulation solution comprises 50% by weight to 85% by weight of diethyl ether and 15% by weight to 50% by weight of oleum.

### Claim 9 (depends on 1)

The method of claim 1, wherein, in the drying the coagulated carbon nanotube fiber, the coagulated carbon nanotube fiber is dried while applying tension thereto.