Method for producing flake graphite, and flake graphite

Patent metadata

Field	Value
Publication number	US-10167198-B2
Application number	US-201314374835-A
Country	US
Kind code	B2
Filing date	Feb 12, 2013
Priority date	Feb 14, 2012
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

There is provided a method for producing relatively easily handleable exfoliated graphite by exfoliating graphite without complicated steps, and exfoliated graphite obtained by the method. A method for producing exfoliated graphite, comprising steps of preparing a composition which comprises graphite or primary exfoliated graphite and a polymer and in which the polymer is fixed to the graphite or primary exfoliated graphite; and pyrolyzing the polymer contained in the composition to exfoliate the graphite or primary exfoliated graphite and remove the polymer by pyrolysis.

First claim

The invention claimed is:

1. A method for producing exfoliated graphite, comprising steps of:
preparing a composition which comprises graphite or primary exfoliated graphite and a polymer and in which the polymer is fixed to the graphite or primary exfoliated graphite; and
pyrolyzing the polymer contained in the composition to exfoliate the graphite or primary exfoliated graphite and remove the polymer by burning the polymer off such that it disappears through pyrolysis of the polymer,
wherein in the step of preparing the composition, the polymer is grafted on the graphite or primary exfoliated graphite in the composition in which the polymer is fixed to the graphite or primary exfoliated graphite.

2. The method for producing exfoliated graphite according to claim 1 , wherein the step of preparing the composition comprises:
a step of preparing a mixture comprising the graphite or primary exfoliated graphite and a radical polymerizable monomer, and
a step of polymerizing the radical polymerizable monomer contained in the mixture to form a polymer in which the radical polymerizable monomer is polymerized in the mixture and graft the polymer on the graphite or primary exfoliated graphite.

3. The method for producing exfoliated graphite according to claim 2 , wherein in the step of preparing the mixture, the mixture further comprises a pyrolyzable foaming agent.

4. The method for producing exfoliated graphite according to claim 3 , wherein in the step of forming the polymer and grafting the polymer on the graphite or primary exfoliated graphite, the pyrolyzable foaming agent contained in the mixture is pyrolyzed.

5. The method for producing exfoliated graphite according to claim 2 , wherein the step of forming the polymer and grafting the polymer on the graphite or primary exfoliated graphite is performed by heating the mixture to polymerize the radical polymerizable monomer contained in the mixture.

6. The method for producing exfoliated graphite according to claim 1 , wherein in the step of preparing the composition, the polymer is heated to a temperature in a temperature range of 50° C. or higher and 400° C. or lower in the presence of the graphite or primary exfoliated graphite to graft the polymer on the graphite.

7. The method for producing exfoliated graphite according to claim 1 , wherein in the step of preparing the composition, the composition further comprises a pyrolyzable foaming agent.

8. The method for producing exfoliated graphite according to claim 7 , wherein in the step of pyrolyzing the polymer to exfoliate the graphite or primary exfoliated graphite, the pyrolyzable foaming agent contained in the composition is pyrolyzed.

9. The method for producing exfoliated graphite according to claim 1 , wherein in the step of preparing the composition, the composition in which the polymer is fixed to the graphite or primary exfoliated graphite, comprising graphite or primary exfoliated graphite and a first polymer, the first polymer being adsorbed on the graphite or primary exfoliated graphite, is prepared, and
in the step of exfoliating the graphite or primary exfoliated graphite, a heating step of heating the composition to a temperature equal to or higher than a pyrolysis temperature of the first polymer to pyrolyze the first polymer to obtain exfoliated graphite is performed.

10. The method for producing exfoliated graphite according to claim 9 , wherein the first polymer is at least one polymer selected from the group consisting of polyvinyl acetate, polybutyral, and polypropylene glycol.

11. The method for producing exfoliated graphite according to claim 10 , wherein in the step of preparing the composition, the composition further comprises a pyrolyzable foaming agent.

12. The method for producing exfoliated graphite according to claim 10 , wherein the exfoliated graphite obtained by the method for producing exfoliated graphite according to claim 9 is used as the primary exfoliated graphite.

13. The method for producing exfoliated graphite according to claim 12 , wherein
a step of adsorbing the first polymer on the primary exfoliated graphite using as the primary exfoliated graphite the exfoliated graphite obtained by the method for producing exfoliated graphite according to claim 12 , to prepare the composition, and
a heating step of heating the provided composition to a temperature equal to or higher than the pyrolysis temperature of the first polymer to pyrolyze the first polymer to obtain exfoliated graphite, are further repeated.

14. The method for producing exfoliated graphite according to claim 9 , further comprising:
a step of preparing a mixture comprising the obtained exfoliated graphite and a radical polymerizable monomer after the heating step;
a step of polymerizing the radical polymerizable monomer contained in the mixture to form a second polymer in Which the radical polymerizable monomer is polymerized in the mixture and graft the second polymer on the exfoliated graphite; and
a second heating step of heating the mixture to a temperature at which the second polymer is pyrolyzed or higher to pyrolyze the second polymer to further exfoliate the exfoliated graphite.

15. The method for producing exfoliated graphite according to claim 9 , wherein the step of preparing the composition comprises:
a step of preparing a mixture comprising graphite and a radical polymerizable monomer,
a step of polymerizing the radical polymerizable monomer contained in the mixture to form a second polymer in which the radical polymerizable monomer is polymerized in the mixture and graft the second polymer on the graphite,
a third heating step of heating the mixture to a temperature equal to or higher than a pyrolysis temperature of the second polymer to pyrolyze the second polymer, and
a step of mixing primary exfoliated graphite obtained in the third heating step and the first polymer to obtain the composition.

16. The method for producing exfoliated graphite according to claim 3 , wherein the pyrolyzable foaming agent is at least one heat foaming agent selected from the group consisting of compounds having structures represented by the following formula (1) to formula (4)

17. The method for producing exfoliated graphite according to claim 3 , wherein in the step of exfoliating the graphite or primary exfoliated graphite, the pyrolyzable foaming agent contained in the mixture is pyrolyzed.

18. The method for producing exfoliated graphite according to claim 2 , wherein the radical polymerizable monomer is styrene or glycidyl methacrylate.

19. Exfoliated graphite obtained by a method for producing exfoliated graphite comprising the steps of:
preparing a composition which comprises graphite or primary exfoliated graphite and a polymer and in which the polymer is fixed to the graphite or primary exfoliated graphite between layers of the graphite or primary exfoliated graphite at an edge portion of the graphite or primary exfoliated graphite; and
pyrolyzing the polymer contained in the composition to exfoliate the edge portion of the graphite or primary exfoliated graphite and remove the polymer by burning the polymer off such that it disappears through pyrolysis of the polymer,
wherein in the step of preparing the composition, the polymer is grafted on the graphite or primary exfoliated graphite in the composition in which the polymer is fixed to the graphite or primary exfoliated graphite,
wherein a central portion of

Assignees

• Sekisui Chemical Co Ltd

Inventors

• Nozato Shoji
• Nakasuga Akira
• Yoshitani Hiroshi

Classifications

• C01B31/0423 Primary

  Chemistry & Metallurgy · mapped topic

• C01B32/225 Primary

  Expansion; Exfoliation · CPC title