Carbon fiber composite material, method of producing the same, insulating article, electronic part, and logging tool

Abstract

A carbon fiber composite material comprising 100 parts by mass of an elastomer, and 20 to 100 parts by mass of carbon nanofibers that have been oxidized and reduced in number of branch points. The carbon fiber composite material has a dynamic modulus of elasticity (E′) at 200° C. and 10 Hz of 10 to 1000 MPa, and a volume resistivity of 10 6 to 10 18 ohms·cm.

What is claimed is: 
     
         1 . A carbon fiber composite material comprising 100 parts by mass of an elastomer, and 20 to 100 parts by mass of carbon nanofibers that have been oxidized and reduced in number of branch points, the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 200° C. and 10 Hz of 10 to 1000 MPa, and a volume resistivity of 10 6  to 10 18  ohms·cm. 
     
     
         2 . The carbon fiber composite material according to  claim 1 , wherein the carbon nanofibers are reduced in number of branch points by a mechanical process before the carbon nanofibers are mixed into the elastomer. 
     
     
         3 . The carbon fiber composite material according to  claim 2 , wherein the mechanical process is implemented by a compression process. 
     
     
         4 . The carbon fiber composite material according to  claim 3 , wherein the elastomer is a fluoroelastomer, the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 200° C. and 10 Hz of 15 to 300 MPa, and a volume resistivity of 10 11  to 10 18  ohms·cm. 
     
     
         5 . The carbon fiber composite material according to  claim 3 , wherein the elastomer is an ethylene-propylene rubber, the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 200° C. and 10 Hz of 10 to 200 MPa, and a volume resistivity of 10 7  to 10 18  ohms·cm. 
     
     
         6 . The carbon fiber composite material according to  claim 2 , wherein the mechanical process is implemented by a grinding process. 
     
     
         7 . The carbon fiber composite material according to  claim 6 , wherein the elastomer is an ethylene-propylene rubber, the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 200° C. and 10 Hz of 10 to 200 MPa, and a volume resistivity of 10 8  to 10 18  ohms·cm. 
     
     
         8 . The carbon fiber composite material according to  claim 1 , wherein the carbon nanofibers have a maximum fiber length of less than 20 μm. 
     
     
         9 . An insulating article that is used for oilfield applications, the insulating article comprising the carbon fiber composite material according to  claim 1 . 
     
     
         10 . An electronic part comprising the insulating article according to  claim 9 . 
     
     
         11 . A logging tool comprising a housing, and the electronic part according to  claim 10  that is disposed in the housing.