Porous carbon electrode substrate and its production method and carbon fiber paper

Abstract

The present invention provides carbon fiber paper consisting of an organic high-molecular compound as a binder and carbon fibers, characterized in that the carbon fibers contain thin fibers with an average diameter smaller than 5 μm and an average fiber length of 3 to 10 mm; a porous carbon electrode substrate for a fuel cell having a thickness of 0.05 to 0.5 mm and a bulk density of 0.3 to 0.8 g/cm 3 , also having a bending strength of 10 MPa or higher and a deflection of 1.5 mm or more at the time of bending, measured by a three-point bending test in conditions of using a sample width of 1 cm, a strain rate of 10 mm/min, and a distance between supporting points of 2 cm; and a method of producing a porous carbon electrode substrate for a fuel cell by impregnating the carbon fiber paper with a thermosetting resin, curing the thermosetting resin by heating and pressing treatment, and then carbonizing the paper. The electrode substrate of the present invention is excellent in flexibility and bending strength and able to be rolled on a roll and thus has high productivity, and the carbon fiber paper of the present invention is suitable for producing the electrode substrate.

1 - 11 . (canceled)  
   
   
       12 . A method of producing a porous carbon electrode substrate for a fuel cell by impregnating carbon fiber paper consisting of an organic high-molecular compound as a binder and carbon fibers with an average diameter smaller than 5 μm and an average fiber length of 3 to 10 mm with a thermosetting resin; curing the thermosetting resin by heating and pressing treatment; and then carbonizing the paper.  
   
   
       13 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that said carbon fiber paper is the carbon fiber paper as claimed in claim  5 .  
   
   
       14 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that said heating and pressing treatment is carried out continuously in a whole length of the carbon fiber paper.  
   
   
       15 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that prior to said heating and pressing treatment, the carbon fiber paper impregnated with the thermosetting resin is pre-heated.  
   
   
       16 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that said heating and pressing treatment is carried out using a continuous type hot press machine equipped with a pair of endless belts.  
   
   
       17 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that said heating and pressing treatment is carried out using a continuous type hot roll press machine.  
   
   
       18 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that at the time of said heating and pressing treatment, the pressure application is carried out at a line pressure of 1.5×10 4  to 1×10 5  N/m.  
   
   
       19 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that said carbonization is carried out continuously in the whole length of the carbon fiber paper.  
   
   
       20 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that the electrode substrate obtained by said carbonization is rolled around a roll with the outer diameter of 50 cm or smaller.  
   
   
       21 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 12 , characterized in that a conductive substance is added to said thermosetting resin.  
   
   
       22 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that said heating and pressing treatment is carried out continuously in a whole length of the carbon fiber paper.  
   
   
       23 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that prior to said heating and pressing treatment, the carbon fiber paper impregnated with the thermosetting resin is pre-heated.  
   
   
       24 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that said heating and pressing treatment is carried out using a continuous type hot press machine equipped with a pair of endless belts.  
   
   
       25 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that said heating and pressing treatment is carried out using a continuous type hot roll press machine.  
   
   
       26 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13  characterized in that at the time of said heating and pressing treatment, the pressure application is carried out at a line pressure of 1.5×10 4  to 1×10 5  N/m.  
   
   
       27 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that said carbonization is carried out continuously in the whole length of the carbon fiber paper.  
   
   
       28 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that the electrode substrate obtained by said carbonization is rolled around a roll with the outer diameter of 50 cm or smaller.  
   
   
       29 . The method of producing a porous carbon electrode substrate for a fuel cell as claimed in  claim 13 , characterized in that a conductive substance is added to said thermosetting resin.