Carbon-fiber-precursor fiber bundle, carbon fiber bundle, and uses thereof

Patent metadata

Field	Value
Publication number	US-9920456-B2
Application number	US-201113879278-A
Country	US
Kind code	B2
Filing date	Oct 13, 2011
Priority date	Oct 13, 2010
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

A carbon-fiber-precursor acryl fiber bundle, including a polyacrylonitrile-based copolymer that contains from 95 to 99 mol % of an acrylonitrile unit and from 1 to 5 mol % of a hydroxyalkyl (meth)acrylate unit, where the fiber bundle has a single-fiber fineness of from 1.5 dtex to 5.0 dtex and a roundness of from 0.75 to 0.9 in a cross-section shape perpendicular to a fiber axis of the single fiber; the roundness being determined with equation (1): roundness=4πS/L 2 , where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

First claim

The invention claimed is:

1. A carbon-fiber-precursor acryl fiber bundle, comprising:
a polyacrylonitrile-based copolymer comprising from 95 to 99 mol % of an acrylonitrile unit and from 1 to 5 mol % of a hydroxyalkyl (meth)acrylate unit,
wherein the fiber bundle has a single-fiber fineness of from 1.5 dtex to 3.0 dtex and a roundness of 0.9 or less in a cross-section shape perpendicular to a fiber axis of the single fiber,
wherein the roundness is a value determined using equation (1): roundness=4πS/L 2 , wherein S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image, and
wherein when a constant velocity temperature rising exothermic curve is from 30° C. to 450° C. measured at a temperature rising rate of 10° C./minute in air flow at 100 ml/minute at 30° C. and 0.10 MPa using a heat flux type differential scanning calorimeter;
a heat quantity Ja obtained by integrating an exothermic velocity from 230° C. to 260° C. of the constant velocity temperature rising exothermic curve is from 100 kJ/kg to 250 kJ/kg; and
a heat quantity Jb obtained by integrating an exothermic velocity from 260° C. to 290° C. is from 550 kJ/kg to 1050 kJ/kg.

2. The fiber bundle according to claim 1 , wherein the roundness is from 0.8 to 0.9.

3. The fiber bundle according to claim 1 , wherein a melting point under heat and humidity of the polyacrylonitrile-based copolymer is from 160 to 175° C.

4. The fiber bundle according to claim 1 wherein a water contact angle is from 40° to 70°.

5. The fiber bundle according to claim 4 , wherein an oxidation depth De is from 4.0 μm to 6.0 μm in the polyacrylonitrile-based copolymer, and the oxidation depth De is obtained by a method comprising:
dissolving the polyacrylonitrile-based copolymer at a concentration of 25% by mass in dimethylformamide to prepare a copolymer solution;
applying the copolymer solution onto a glass plate;
drying the glass plate on which the copolymer solution was applied in air at 120° C. for 6 hours to evaporate dimethylformamide and make a film having a constant thickness in the range of from 20 μm to 40 μm;
flame-proof treating by treating the obtained film with heat in air at 240° C. for 60 minutes and further in air at 250° C. for 60 minutes to obtain a flame-proofed film;
embedding the flame-proofed film in a resin followed by polishing to obtain a polished flame-proofed film;
observing a cross-section perpendicular to a surface of the polished flame-proofed film at a magnification of 1500 using a fluorescence microscope; and
observing an oxidation progressing part as a relatively dark layer and observing an oxidation non-progressing part as a relatively light layer in the cross-section, thus a distance from the surface of the polished flame-proofed film to a boundary between the dark layer and the light layer is measured at least at 5 points on one cross-section, the same measurement is further repeated on three cross-sections, and their arithmetic average is used as the oxidation depth De (μm).

6. The fiber bundle according to claim 1 , wherein the heat quantity Ja is from 100 kJ/kg to 160 kJ/kg.

7. The fiber bundle according to claim 1 , wherein a calorific value per unit mass at 215 to 300° C. obtained by a measurement using a heat flux type differential scanning calorimeter is 3200 kJ/kg or more wherein a temperature rising rate in the measurement using the heat flux type differential scanning calorimeter is 2° C./minute and an atmosphere is air and
wherein a half-value width of solid 1 H-NMR spectra at a measurement temperature of 160° C. is from 10.0 kHz to 14.5 kHz.

8. The fiber bundle according to claim 7 , wherein the calorific value at 215 to 300° C. is 3300 kJ/kg or more.

9. The fiber bundle according to claim 7 , wherein the half-value width is from 10.0 kHz to 13.5 kHz.

10. A method for flame-proof treatment, comprising treating the carbon-fiber-precursor acryl fiber bundle according to any one of claims 1 , 4 , 7 , 8 , or 9 under an oxidation atmosphere at temperature of from 220° C. to 300° C. for from 30 minutes to 90 minutes or less to obtain a flame-proofed fiber bundle having a fiber density of from 1.35 g/cm 3 to 1.43 g/cm 3 .

11. A method of producing a carbon fiber bundle having a diameter Di of 8 μm or more and a roundness of a shape of 0.90 or less in a cross-section perpendicular to a fiber axis of a single fiber, the method comprising:
flame-proof treating the carbon-fiber-precursor acryl fiber bundle according to any one of claims 1 , 4 , 7 , 8 , or 9 under an oxidation atmosphere at temperature of from 220° C. to 300° C. for from 30 minutes to 90 minutes to obtain a flame-proofed fiber bundle having a fiber density of from 1.35 g/cm 3 to 1.43 g/cm 3 ; and
further carbonizing the flame-proofed fiber bundle at temperature of from 800° C. to 2000° C. in an inert gas,
wherein the diameter Di is as measured by:
preparing a sample, wherein a carbon fiber bundle cut into a length of 5 cm is embedded in an epoxy resin, wherein epomount base: epomount curing agent=100:9 by mass ratio, and cut into a length of 2 cm to expose a cross-sectional surface, to which a mirror surface treatment is given;
performing an etching treatment to the cross-sectional surface of the sample with a Plasma Etching Apparatus JP-170 manufactured by JEOL Ltd. under an atmosphere of Ar/O 2 =75/25, a plasma output power of 50 W, a vacuum degree of about 120 Pa, and a treatment time period of 5 minutes;
observing under SEM, wherein the cross-sectional surface of the samples obtained by the preparing and the performing is observed using SEM PHILIPS FEI-XL20, and five photographs of 5 or more fiber cross-sections on an image are taken randomly; and
measuring a diameter of a single fiber cross-section in a carbon fiber bundle, wherein for each sample, 20 single fiber cross-sections from the 5 SEM photographs, wherein 3 or more single fiber cross-sections from one photograph, are randomly selected, a contour of the fiber cross-section is traced using an image analysis software Image-ProPLUS, manufactured by Nippon Roper K.K., a major axis d, which is a maximum feret diameter of the cross-section, is measured, and a mean value of the major axes of all single fiber cross-sections selected is the diameter Di of the single fiber in the carbon fiber bundle.

Assignees

• Shinmen Yuusuke
• Hirota Norifumi
• Nii Takeshi
• Mitsubishi Chem Corp

Inventors

• Shinmen Yuusuke
• Hirota Norifumi
• Nii Takeshi

Classifications

• Y10T442/3089

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• Y10T428/298

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• Y10T428/26

  Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension · CPC title

• D01D5/096

  Humidity control, or oiling, of filaments, threads or the like, leaving the spinnerettes · CPC title

• C08J5/042

  with carbon fibres · CPC title