# US 10,766,773 B2 · Graphite sheet having excellent thermal conductivity and method for preparing the same

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- Number: US 10,766,773 B2
- Document ID: US10766773B2
- Status: Granted
- Kind: B2
- Application number: 15/858,604
- Filed: 2017-12-29
- Published: 2019-05-16
- Granted: 2020-09-08
- Earliest claimed: 2017-11-10
- Assignees: PI Advanced Materials Co., Ltd.
- Applicants: PI Advanced Materials Co., Ltd.
- Inventors: Dong Young Won; Hyun Jai Lim; Kyung Su Kim
- Web page: https://patentgrep.com/patent/US10766773B2

## CPC

- C01B 32/205: Preparation
- C07C 233/00: Carboxylic acid amides
- C01B 2204/04: Specific amount of layers or specific thickness
- C01B 2204/24: Thermal properties
- C01P 2006/32: Thermal properties
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

The present invention provides a method for preparing a high-performance graphite sheet by imidizing a polyamic acid resulting from a reaction of dianhydride monomer(s) and diamine monomer(s) to obtain a polyimide film; and carbonizing and/or graphitizing the polyimide film to obtain a high-performance graphite sheet, where the polyimide film contains 2 or more fillers having different average particle diameters, and the thermal conductivity of the graphite sheet is at least 1,400 W/m·K. Further, the present invention provides a graphite sheet obtained by the above method.

## Claims

### Claim 1

A method for preparing a high-performance graphite sheet, comprising:
providing a polyimide film containing a first filler having an average particle diameter of 2.0 μm to 2.5 μm, and a second filler having an average particle diameter of 1.0 μm to 1.6 μm; and
carbonizing and graphitizing the polyimide film to obtain the graphite sheet,
wherein the thermal conductivity of the graphite sheet is at least 1,400 W/m·K.

### Claim 2 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the fillers are sublimated during carbonizing and/or graphitizing step, forming voids in the graphite sheet.

### Claim 3 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the graphite sheet has a thickness of 15 μm to 40 μm.

### Claim 4 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the polyimide film contains more than 0% to not more than 40% of the first filler, and at least 60% to less than 100% of the second filler, based on the total of the fillers.

### Claim 5 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the polyimide film has an average roughness(Ra) of 8 nm to 30 nm.

### Claim 6 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the content of the fillers is 2000 ppm to 4000 ppm based on the weight of the polyamic acid.

### Claim 7 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the fillers are at least one selected from the group consisting of calcium carbonate, calcium phosphate dibasic, and barium sulphate.

### Claim 8 (depends on 7)

The method for preparing the high-performance graphite sheet according to claim 7, wherein the fillers are calcium phosphate dibasic and/or barium sulphate.

### Claim 9 (depends on 1)

The method for preparing the high-performance graphite sheet according to claim 1, wherein the heat treatment temperature of the graphitizing step is at least 2700° C.