Carbon fiber manufacturing method and carbon fiber

1. A carbon fiber manufacturing method comprising:

a surface treatment step of ejecting an ozone solution in which ozone is dissolved in solvent from a fluid ejecting port toward a carbon fiber bundle and causing the ozone solution to pass between single fibers of the carbon fiber bundle so as to contact surfaces of the single fibers so that the surfaces of carbon fibers are treated by the ozone solution,

wherein:

the carbon fiber bundle comprises 10000 to 60000 single fibers, and

the ozone solution is ejected at an ejection speed set to 0.20 m/second to 2.0 m/second in a direction intersecting the transportation direction of the transported carbon fiber bundle from the fluid ejecting port.

2. The carbon fiber manufacturing method according to claim 1 ,

wherein a tension of the carbon fiber bundle measured when the ozone solution contacts surfaces of single fibers is 0.3 kgf to 1.8 kgf for twelve thousand single fibers.

3. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein the carbon fiber bundle is held inside the ozone solution for 0.1 seconds to 60 seconds.

4. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein, an ejection amount of the ozone solution per unit time is set to forty times to three hundred times with respect to a mass of the carbon fiber bundle passing above the fluid ejecting port or below the fluid ejecting port per unit time.

5. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein the number of times of ejecting the ozone solution from the fluid ejecting port toward the carbon fiber bundle so as to contact the surfaces of the single fibers is set to one to four times.

6. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein the fluid ejecting port has a rectangular shape, the length direction of the fluid ejecting port is the width direction of the carbon fiber bundle, and a length of the fluid ejecting port in the length direction is equal to or larger than a width of the carbon fiber bundle.

7. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein a collision plate is installed at a position facing the fluid ejecting port by interposing the carbon fiber bundle transported above a liquid level of an ozone treatment tank storing the ozone solution, and the ozone solution ejected from the fluid ejecting port is caused to pass between the single fibers of the carbon fiber bundle so as to collide with the collision plate.

8. The carbon fiber manufacturing method according to claim 7 ,

wherein the surface treatment is performed on the carbon fiber bundle of which the permeation resistance measured based on JIS P 8117:2009 is 100 seconds to 700 seconds and which is transported above the liquid level of the ozone treatment tank storing the ozone solution.

9. The carbon fiber manufacturing method according to claim 7 ,

wherein the surface treatment is performed on the carbon fiber bundle of which the moisture content is 40% or less and which is transported above the liquid level of the ozone treatment tank storing the ozone solution.

10. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein the surface treatment is performed on the carbon fiber bundle transported inside the ozone solution.

11. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein an ozone concentration of the ozone solution is 10 mg/L to 120 mg/L.

12. The carbon fiber manufacturing method according to claim 1 or 2 ,

wherein a carbon fiber is obtained of which a current value (ipa value) per unit area measured by a cyclic voltammetry method is 0.10 μA/cm 2 or more.