Heat conduction sheet, method of manufacturing heat conduction sheet, and heat dissipating device

1. A heat conduction sheet, comprising:

at least one kind of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles and rod-like particles;

a polymer (B) having an isobutylene structure, the polymer (B) comprising at least one of a copolymer of isobutene and styrene in which a content ratio of the isobutylene structure in the copolymer of isobutene and styrene is from 60% by mass to 95% by mass, a copolymer of isobutene and ethylene in which a content ratio of the isobutylene structure in the copolymer of isobutene and ethylene is from 60% by mass to 95% by mass, and a homopolymer of isobutene;

an ethylene-propylene copolymer (C); and

an ethylene octene elastomer (D),

wherein a content ratio of the polymer (B) in the heat conduction sheet is from 10% by volume to 40% by volume, and

wherein, in a case of scale-like particles, a plane direction of the particle is oriented in a thickness direction of the heat conduction sheet, and in a case of ellipsoidal particles or rod-like particles, a long axis direction of the particle is oriented in the thickness direction of the heat conduction sheet.

2. The heat conduction sheet according to claim 1 , wherein the graphite particle (A) includes a scale-like particle that comprises an expanded graphite particle.

3. The heat conduction sheet according to claim 1 , further comprising an alicyclic hydrocarbon resin (E).

4. The heat conduction sheet according to claim 1 , further comprising an antioxidant.

5. The heat conduction sheet according to claim 1 , wherein a content ratio of the graphite particle (A) is from 15% by volume to 50% by volume.

6. A method of manufacturing the heat conduction sheet according to claim 1 , comprising:

preparing a composition comprising: at least one kind of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles and rod-like particles; a polymer (B) having an isobutylene structure; an ethylene-propylene copolymer (C); and an ethylene octene elastomer (D);

forming the composition into a sheet;

producing a layered body by stacking a plurality of the sheets, folding one of the sheets, or rolling one of the sheets; and

slicing a side end face of the layered body.

7. A heat dissipating device, comprising the heat conducting sheet according to claim 1 interposed between a heat generating body and a heat dissipating body.

8. The heat conduction sheet according to claim 1 , wherein a content ratio of the polymer (B) in the heat conduction sheet is from 20% by volume to 30% by volume.

9. A heat conduction sheet, comprising:

at least one kind of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles and rod-like particles; and

a resin component having a storage elastic modulus G′ at 150° C. of 8 Pas or more including a polymer (B) having an isobutylene structure, the polymer (B) comprising at least one of a copolymer of isobutene and styrene in which a content ratio of the isobutylene structure in the copolymer of isobutene and styrene is from 60% by mass to 95% by mass, a copolymer of isobutene and ethylene in which a content ratio of the isobutylene structure in the copolymer of isobutene and ethylene is from 60% by mass to 95% by mass, and a homopolymer of isobutene,

wherein a content ratio of the polymer (B) in the heat conduction sheet is from 10% by volume to 40% by volume, and

wherein, in a case of scale-like particles, a plane direction of the particle is oriented in a thickness direction of the heat conduction sheet, and in a case of ellipsoidal particles or rod-like particles, a long axis direction of the particle is oriented in the thickness direction of the heat conduction sheet.

10. The heat conduction sheet according to claim 9 , wherein a content ratio of the polymer (B) in the heat conduction sheet is from 20% by volume to 30% by volume.

11. The heat conduction sheet according to claim 9 , wherein the graphite particle (A) includes a scale-like particle that comprises an expanded graphite particle.

12. The heat conduction sheet according to claim 9 , wherein a content ratio of the graphite particle (A) is from 15% by volume to 50% by volume.

13. A heat dissipating device, comprising the heat conducting sheet according to claim 9 interposed between a heat generating body and a heat dissipating body.

14. A heat conduction sheet, comprising:

at least one kind of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles and rod-like particles; and

a resin component including a polymer (B) having an isobutylene structure, the polymer (B) comprising at least one of a copolymer of isobutene and styrene in which a content ratio of the isobutylene structure in the copolymer of isobutene and styrene is from 60% by mass to 95% by mass, a copolymer of isobutene and ethylene in which a content ratio of the isobutylene structure in the copolymer of isobutene and ethylene is from 60% by mass to 95% by mass, and a homopolymer of isobutene, wherein:

one of the following (1) to (3) is satisfied,

(1) compression set (%) after treatment at 150° C. is 4% or less,

(2) an arithmetic mean roughness of a surface of the sheet is 2.1 μm or less,

(3) a porosity of the sheet is 10% or less,

wherein a content ratio of the polymer (B) in the heat conduction sheet is from 10% by volume to 40% by volume, and

in a case of scale-like particles, a plane direction of the particle is oriented in a thickness direction of the heat conduction sheet, and in a case of ellipsoidal particles or rod-like particles, a long axis direction of the particle is oriented in the thickness direction of the heat conduction sheet.

15. The heat conduction sheet according to claim 14 , wherein a content ratio of the polymer (B) in the heat conduction sheet is from 20% by volume to 30% by volume.

16. The heat conduction sheet according to claim 14 , wherein the graphite particle (A) includes a scale-like particle that comprises an expanded graphite particle.

17. The heat conduction sheet according to claim 14 , wherein a content ratio of the graphite particle (A) is from 15% by volume to 50% by volume.

18. A heat dissipating device, comprising the heat conducting sheet according to claim 14 interposed between a heat generating body and a heat dissipating body.