Method for production of carbon fiber bundle
View Patent ↗The purpose of the present invention is to provide a method whereby deposits which have occurred on the surfaces of a fiber bundle during flameproofing treatment of a carbon fiber-precursor acrylic fiber bundle can be efficiently removed prior to carbonization treatment at high temperature. The method for production of carbon fiber bundle includes a step in which, after a carbon fiber-precursor acrylic fiber bundle has been heated and undergone flameproofing treatment, the fiber bundle is subjected to a plasma treatment involving contact with a plasma gas in gas phase, or to an ultraviolet treatment involving irradiation with ultraviolet in gas phase; and a step in which the fiber bundle having undergone the plasma treatment or the ultraviolet treatment is subjected to a carbonization treatment.
1. A method for producing a carbon fiber bundle, the method comprising:
performing a plasma treatment of bringing a fiber bundle A, which is a carbon fiber precursor acrylic fiber bundle having undergone flameproofing treatment by heating, into contact with a plasma gas in gas phase; and
performing carbonization treatment of a fiber bundle B, which has been obtained by the plasma treatment,
wherein the plasma gas is generated by introducing a mixed gas of inactive gas in a range of 97.00 volume % to 99.99 volume % and active gas in a range of 0.0100 volume % to 3.000 volume % into a plasma generation device.
2. The method for producing a carbon fiber bundle according to claim 1 , wherein the density of the fiber bundle A to be subjected to the plasma treatment is in a range of 1.30 g/cm 3 to 1.50 g/cm 3 .
3. The method for producing a carbon fiber bundle according to claim 1 , wherein the density of the fiber bundle A to be subjected to the plasma treatment is in a range of 1.50 g/cm 3 to 1.70 g/cm 3 .
4. The method for producing a carbon fiber bundle according to claim 1 , wherein the plasma gas is ejected from an ejection port and brought into contact with the fiber bundle A such that the distance d between the ejection port of the plasma gas of a plasma generation device and the fiber bundle A is in a range of 0.5 mm to 10 mm.
5. The method for producing a carbon fiber bundle according to claim 2 , wherein the fiber bundle A is made into a sheet form having a fineness per unit width in a range of 500 dtex/mm to 5000 dtex/mm, and the fiber bundle in the sheet form is brought into contact with the plasma gas.
6. The method for producing a carbon fiber bundle according to claim 3 , wherein the fiber bundle A is made into a sheet form having a fineness per unit width in a range of 500 dtex/mm to 5000 dtex/mm, and the fiber bundle in the sheet form is brought into contact with the plasma gas.
7. The method for producing a carbon fiber bundle according to claim 1 , wherein the plasma gas is ejected from each direction facing to each side of the fiber bundle in the sheet form.
8. The method for producing a carbon fiber bundle according to claim 2 , wherein the absorbance, which is measured by the measuring method below, of the fiber bundle B to be subjected to the carbonization treatment satisfies condition 1 and/or condition 2 as follows:
condition 1: absorbance at 240 nm of the wavelength is 1.5 or less;
condition 2: absorbance at 278 nm of the wavelength is 1.0 or less.
9. The method for producing a carbon fiber bundle according to claim 3 , wherein the absorbance, which is measured by the measuring method below, of the fiber bundle B to be subjected to the carbonization treatment satisfies condition 1 and/or condition 2 as follows:
condition 1: absorbance at 240 nm of the wavelength is 0.20 or less;
condition 2: absorbance at 278 nm of the wavelength is 0.15 or less.
10. The method for producing a carbon fiber according to claim 2 , wherein the total number of cavities and particles having a size of 1 μm or more which are present on the surface of filaments that are present on the surface of the fiber bundle B to be subjected to the carbonization treatment is 5 or less per 100 μm 2 area of the surface of the filaments.
11. The method for producing a carbon fiber according to claim 3 , wherein the total number of cavities and particles having a size of 1 μm or more which are present on the surface of filaments that are present on the surface of the fiber bundle B to be subjected to the carbonization treatment is 5 or less per 100 μm 2 area of the surface of the filaments.
12. The method for producing a carbon fiber according to claim 5 , wherein the total number of cavities and particles having a size of 1 μm or more which are present on the surface of filaments that are present on the surface of the fiber bundle B to be subjected to the carbonization treatment is 5 or less per 100 μm 2 area of the surface of the filaments.
13. The method for producing a carbon fiber according to claim 6 , wherein the total number of cavities and particles having a size of 1 μm or more which are present on the surface of filaments that are present on the surface of the fiber bundle B to be subjected to the carbonization treatment is 5 or less per 100 μm 2 area of the surface of the filaments.
14. A method for producing a carbon fiber bundle, the method comprising:
heating a fiber bundle of a carbon fiber precursor to perform a flame proofing treatment;
rendering the density of the fiber bundle in a range of 1.30 g/cm 3 to 1.50 g/cm 3 by the flameproofing treatment to obtain a fiber bundle C; and
subjecting the fiber bundle C to carbonization treatment;
wherein the absorbance, which is measured by the measuring method below, of the fiber bundle C to be subjected to carbonization treatment satisfies condition 1 and/or condition 2 as follows:
condition 1: absorbance at 240 nm of the wavelength is 1.5 or less;
condition 2: absorbance at 278 nm of the wavelength is 1.0 or less, and
the fiber bundle C to be subjected to the carbonization treatment is a fiber bundle that is obtained by performing ultraviolet ray treatment comprising irradiating the fiber bundle with an ultraviolet ray in a gas phase, after the flameproofing treatment.
15. A method for producing a carbon fiber bundle, the method comprising:
heating a fiber bundle of a carbon fiber precursor to perform a flame proofing treatment;
rendering the density of the fiber bundle in a range of 1.50 g/cm 3 to 1.70 g/cm 3 after the flameproofing treatment to obtain a fiber bundle C; and
subjecting the fiber bundle C to carbonization treatment;
wherein:
the total number of cavities and particles having a size of 1 μm or more which are present on the surface of filaments that are present on the surface of the fiber bundle C to be subjected to the carbonization treatment is 5 or less per 100 μm 2 area of the surface of the filaments;
the fiber bundle C to be subjected to the carbonization treatment is a fiber bundle that is obtained by performing plasma treatment comprising contacting the fiber bundle with a plasma gas in a gas phase, after the flameproofing treatment; and
the plasma gas is generated by introducing a mixed gas of inactive gas in a range of 97.00 volume % to 99.99 volume % and active gas in a range of 0.0100 volume % to 3.000 volume % into a plasma generation device.
16. The method for producing a carbon fiber bundle according to claim 14 , wherein luminous energy per unit area of the ultraviolet ray irradiated in the ultraviolet ray treatment is in a range of 3 mW/cm 2 to 10 mW/cm 2 .