Carbon fiber composite material and method of producing the same, formed product of carbon fiber composite and method of producing the same, carbon fiber-metal composite material and method of producing the same, and formed product of carbon fiber-metal composite and method of producing the same

1. A method of producing a carbon nanofiber composite material, comprising:

mixing an elastomer which includes an unsaturated bond or a group having affinity to carbon nanofibers with metal particles; and

mixing the carbon nanofibers into the elastomer including the metal particles and uniformly dispersing the carbon nanofibers by a shear force at 0 to 50° C. by a method selected from the group consisting of an open-roll method with a roll distance of 0.5 mm or less, a closed kneading method, and a multi-screw extruding kneading method,

wherein the composite material is in an uncrosslinked form and the composite material has a first spin-spin relaxation time (T 2 n) of 100 to 3,000 μsec, a second spin-spin relaxation time (T 2 nn) of 1,000 to 10,000 μsec or without the second spin-spin relaxation time, and a fraction (fnn) of components having the second spin-spin relaxation time is less than 0.2, as measured at 150° C. by Hahn-echo method using a pulsed NMR technique with 1 H as an observing nucleus.

2. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein the metal particles have an average particle diameter greater than an average diameter of the carbon nanofibers, and

wherein the amount of the metal particles is 10 to 3,000 parts by weight for 100 parts by weight of the elastomer.

3. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein the metal particles have an average particle diameter greater than an average diameter of the carbon nanofibers.

4. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein the metal particles are aluminum particles or aluminum alloy particles.

5. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein at least one of a main chain, a side chain and a terminal chain of the elastomer includes at least one of a double bond, a triple bond, α-hydrogen, a carbonyl group, a carboxyl group, a hydroxyl group, an amino group, a nitrile group, a ketone group, an amide group, an epoxy group, an ester group, a vinyl group, a halogen group, a urethane group, a biuret group, an allophanate group and a urea group.

6. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein a network component of the elastomer in an uncrosslinked form has a spin-spin relaxation time (T 2 n) measured at 30° C. by a Hahn-echo method using pulsed nuclear magnetic resonance (NMR) technique of 100 to 3,000 μsec.

7. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein a network component of the elastomer in a crosslinked form has a spin-spin relaxation time (T 2 n) measured at 30° C. by a Hahn-echo method using pulsed nuclear magnetic resonance (NMR) technique of 100 to 2,000 μsec.

8. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein the carbon nanofibers have an average diameter of 0.5 to 500 nm.

9. The method of producing a carbon nanofiber composite material as defined in claim 1 , wherein the step of dispersing the carbon nanofibers is conducted by the open-roll method with two rolls having a surface velocity ratio of 1.05 to 3.00.

10. A method of producing a formed product of carbon nanofiber composite, comprising:

obtaining a carbon nanofiber composite material by the method as defined in claim 1 and forming the carbon nanofiber composite material into a desired shape.

11. A method of producing a carbon nanofiber-metal composite material, comprising:

obtaining a formed product of carbon nanofiber composite by the method as defined in claim 10 ; mixing the formed product of carbon nanofiber composite into a molten metal; and

casting the mixture in a die having a desired shape.

12. The method of producing a carbon nanofiber-metal composite material as defined in claim 11 , wherein the molten metal is the same metal as the metal particles.

13. A method of producing a formed product of carbon nanofiber-metal composite, comprising:

obtaining a formed product of carbon nanofiber composite by the method as defined in claim 10 ; and permeating a molten metal into the formed product of carbon nanofiber composite to replace the elastomer with the molten metal.

14. The method of producing a formed product of carbon nanofiber -metal composite as defined in claim 13 , wherein the molten metal is the same metal as the metal particles.

15. A method of producing a formed product of carbon nanofiber-metal composite, comprising:

obtaining a formed product of carbon nanofiber composite by the method as defined in claim 10 ; disposing a metal ingot above the formed product of carbon nanofiber composite;

heating the metal ingot to melt into a molten metal and heating the formed product of the carbon nanofiber composite to vaporize the elastomer in the formed product of carbon nanofiber composite; and

permeating the molten metal into the formed product of carbon nanofiber composite to replace the elastomer with the molten metal.

16. The method of producing a formed product of carbon nanofiber -metal composite as defined in claim 15 , wherein the molten metal is the same metal as the metal particles.

17. A method of producing a carbon nanofiber-metal composite material, comprising:

obtaining a formed product of carbon nanofiber composite by the method as defined in claim 10 ; and powder-forming the formed product of carbon nanofiber composite.

18. A method of producing a formed product of carbon nanofiber composite, comprising:

obtaining a carbon nanofiber composite material by the method as defined in claim 1 ; and crosslinking the carbon nanofiber composite material.

19. A method of producing a formed product of carbon nanofiber composite, comprising:

obtaining a carbon nanofiber composite material by the method as defined in claim 1 ; and crosslinking and forming the carbon nanofiber composite material in a mold having a desired shape.

20. A method of producing a carbon nanofiber-metal composite material, comprising:

obtaining a carbon nanofiber composite material by the method as defined in claim 1 ; mixing the carbon nanofiber composite material into a molten metal; and

casting the mixture in a die having a desired shape.

21. The method of producing a carbon nanofiber-metal composite material as defined in claim 20 , wherein the molten metal is the same metal as the metal particles.

22. A method of producing a carbon nanofiber-metal composite material, comprising:

obtaining a carbon nanofiber composite material by the method as defined in claim 1 ; and powder-forming the carbon nanofiber composite material.