Process of making a carbon fiber nonwoven fabric

Abstract

The present invention has an object of providing the carbon fiber (or the nonwoven fabric configured of the aforementioned carbon fiber) of which the surface area, the graphitization degree, and the fiber diameter are large, high, and small, respectively, and yet of which dispersion is small. The method of producing the carbon fiber nonwoven fabric includes a dispersion liquid preparing step of preparing a dispersion liquid containing resin and pitch, an electrospinning step of producing the nonwoven fabric that is comprised of carbon fiber precursors with electrospinning from the aforementioned dispersion liquid, and a modifying step of modifying the carbon fiber precursors of the nonwoven fabric obtained in the aforementioned electrospinning step into the carbon fiber.

1 - 19 . (canceled) 
     
     
         20 . A carbon fiber: wherein said carbon fiber includes a large diameter portion and a small diameter portion;
 wherein a diameter of said large diameter portion is 20 nm to 2 μm;   wherein a diameter of said small diameter portion is 10 nm to 1 μm; and   wherein (the diameter in said large diameter portion)>(the diameter in said small diameter portion).   
     
     
         21 . The carbon fiber as claimed in  claim 20 , wherein (a maximum value of the diameter in said large diameter portion)/(a minimum value of the diameter in said small diameter portion) is 1.1 to 100. 
     
     
         22 . The carbon fiber as claimed in  claim 20 , wherein a length of said small diameter portion is longer than a minimum value of the diameter in said large diameter portion. 
     
     
         23 . The carbon fiber as claimed  claim 20 , wherein the length of said small diameter portion is shorter than the maximum value of the diameter in said large diameter portion. 
     
     
         24 . The carbon fiber as claimed in  claim 20 , wherein the length of said small diameter portion is 10 nm to 10 μm. 
     
     
         25 . The carbon fiber as claimed in  claim 20 , wherein the length of said large diameter portion is 50 nm to 10 μm. 
     
     
         26 . The carbon fiber as claimed in  claim 20 ,
 wherein said carbon fiber includes said large diameter portions in plural number, and yet said small diameter portions in plural number; and   wherein a length of said carbon fiber is 0.1 to 1000 μm.   
     
     
         27 . The carbon fiber as claimed in  claim 20 , wherein a specific surface area of said carbon fiber is 1 to 100 m 2 /g. 
     
     
         28 . The carbon fiber as claimed in  claim 20 , wherein a peak originating in a graphite structure (002) exists within a range of 25° to 30° (2θ) in an X-ray diffraction measurement of said carbon fiber, and a half width of said peak is 0.1° to 2° (2θ). 
     
     
         29 . The carbon fiber as claimed in  claim 20 , wherein ID/IG of said carbon fiber is 0.2 to 2 (ID is a peak intensity existing within 1300 cm −1  to 1400 cm −1  in Raman scattering spectra of said carbon fiber. IG is a peak intensity existing within 1580 cm −1  to 1620 cm −1  in Raman scattering spectra of said carbon fiber.). 
     
     
         30 . The carbon fiber as claimed in  claim 20 , wherein L/(S) 1/2  of said carbon fiber (S is an area of said carbon fiber in an image obtained by observing said carbon fiber with a scanning electron microscope. L is an outer length of said carbon fiber in the image obtained by observing said carbon fiber with the scanning electron microscope.) is 3.7 to 300. 
     
     
         31 - 48 . (canceled) 
     
     
         49 . A carbon fiber nonwoven fabric comprising 50 to 100% by mass of the carbon fiber of  claim 20 .