Carbon fiber nonwoven fabric

Abstract

A carbon fiber nonwoven fabric in which carbon fibers are sized with an aliphatic compound having a plurality of epoxy groups or a specific aromatic compound; the number average x of carbon fibers forming a carbon fiber bundle, in which the number of carbon fibers forming the carbon fiber bundle is 90 or more, is 90 to 1,000 fibers per bundle among the carbon fiber bundles in the carbon fiber nonwoven fabric; and the standard deviation σ of the number of carbon fibers forming the carbon fiber bundle is 50 to 500.

1 .- 16 . (canceled) 
     
     
         17 . A carbon fiber nonwoven fabric including carbon fibers, wherein said carbon fibers are sized with an aliphatic compound having a plurality of epoxy groups, a number average x of carbon fibers forming a carbon fiber bundle, in which a number of carbon fibers forming a carbon fiber bundle is 90 or more, is 90 to 1,000 fibers per bundle among carbon fiber bundles in said carbon fiber nonwoven fabric, and a standard deviation σ of the number of carbon fibers forming said carbon fiber bundle is 50 to 500. 
     
     
         18 . A carbon fiber nonwoven fabric including carbon fibers, wherein said carbon fibers are sized with an aromatic compound having a plurality of epoxy groups in which a number of atoms present between an epoxy group and an aromatic ring is 6 or more, a number average x of carbon fibers forming a carbon fiber bundle, in which a number of carbon fibers forming a carbon fiber bundle is 90 or more, is 90 to 1,000 fibers per bundle among carbon fiber bundles in said carbon fiber nonwoven fabric, and a standard deviation σ of the number of carbon fibers forming said carbon fiber bundle is 50 to 500. 
     
     
         19 . The carbon fiber nonwoven fabric according to  claim 17 , wherein said compound having a plurality of epoxy groups is a compound having an epoxy group at each end of the longest atomic chain. 
     
     
         20 . The carbon fiber nonwoven fabric according to  claim 19 , wherein said compound having a plurality of epoxy groups is a compound having an epoxy group only at each end of the longest atomic chain. 
     
     
         21 . The carbon fiber nonwoven fabric according to  claim 17 , wherein a number of atoms of the longest atomic chain of said aliphatic compound having a plurality of epoxy groups is 20 to 200. 
     
     
         22 . The carbon fiber nonwoven fabric according to  claim 17 , wherein said aliphatic compound having a plurality of epoxy groups is at least one compound selected from the group consisting of glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyethylene glycol diglycidyl ether group and polypropylene glycol diglycidyl ether group. 
     
     
         23 . The carbon fiber nonwoven fabric according to  claim 18 , wherein said aromatic compound having a plurality of epoxy groups in which a number of atoms present between an epoxy group and an aromatic ring is 6 or more is a compound shown in chemical formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1  is chemical formula (2): 
       
         
           
           
               
               
           
         
       
       R 2  represents an alkylene group having a carbon number of 2 to 30, R 3  is —H or —CH 3 , m and n represent an integer of 2 to 48, and m+n is 4 to 50. 
     
     
         24 . The carbon fiber nonwoven fabric according to  claim 23 , wherein said R 2  is —CH 2 CH 2 — or —CH(CH 3 ) CH 2 —. 
     
     
         25 . The carbon fiber nonwoven fabric according to  claim 18 , wherein said aromatic compound is a condensed polycyclic aromatic compound. 
     
     
         26 . The carbon fiber nonwoven fabric according to  claim 25 , wherein a skeletal structure of said condensed polycyclic aromatic compound is naphthalene, anthracene, phenanthrene or pyrene. 
     
     
         27 . A carbon fiber nonwoven fabric including carbon fibers, wherein at least one compound selected from chemical formulae (3), (4) and (5) is made to adhere to said carbon fibers at an amount of 0.1 to 5.0 wt. % relative to the weight of said carbon fibers of 100 wt. %, a number average x of carbon fibers forming a carbon fiber bundle, in which a number of carbon fibers forming a carbon fiber bundle is 90 or more, is 90 to 1,000 fibers per bundle among carbon fiber bundles in said carbon fiber nonwoven fabric, and a standard deviation σ of the number of carbon fibers forming said carbon fiber bundle is 50 to 500 
       
         
           
           
               
               
           
         
       
       wherein R 1  represents H, OH, chemical formulae (6) or (7), R 2  represents H or OH, m and n represent an integer of 1 to 49, and m+n is in a range of 10 to 50 
       
         
           
           
               
               
           
         
       
     
     
         28 . The carbon fiber nonwoven fabric according to  claim 17 , wherein said standard deviation σ of the number of carbon fibers forming said carbon fiber bundle is 50 to 350. 
     
     
         29 . The carbon fiber nonwoven fabric according to  claim 17 , wherein a proportion of said carbon fiber bundles relative to the total weight of carbon fibers is 5 to 80 wt. %. 
     
     
         30 . The carbon fiber nonwoven fabric according to  claim 17 , wherein said carbon fiber nonwoven fabric is formed from a carbon fiber bundle whose drape value (cm)/single fiber flexural stiffness (Pa·cm 4 ) at 25° C. is 1.4×10 3  to 4.0×10 3  (cm/(Pa·cm 4 )). 
     
     
         31 . The carbon fiber nonwoven fabric according to  claim 17 , wherein a single fiber flexural stiffness of carbon fibers forming said carbon fiber nonwoven fabric is 1.0×10 −11  to 2.8×10 −11  (Pa·cm 4 ). 
     
     
         32 . The carbon fiber nonwoven fabric according to  claim 17 , wherein a fiber length Ln of carbon fibers forming said carbon fiber nonwoven fabric is 3 to 50 mm. 
     
     
         33 . The carbon fiber nonwoven fabric according to  claim 18 , wherein said compound having a plurality of epoxy groups is a compound having an epoxy group at each end of the longest atomic chain. 
     
     
         34 . The carbon fiber nonwoven fabric according to  claim 19 , wherein a number of atoms of the longest atomic chain of said aliphatic compound having a plurality of epoxy groups is 20 to 200. 
     
     
         35 . The carbon fiber nonwoven fabric according to  claim 19 , wherein said aliphatic compound having a plurality of epoxy groups is at least one compound selected from the group consisting of glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyethylene glycol diglycidyl ether group and polypropylene glycol diglycidyl ether group.