# US 10,870,580 B2 · Polyimide film for graphite sheet, graphite sheet prepared by using the same and method for preparing graphite sheet

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- Number: US 10,870,580 B2
- Document ID: US10870580B2
- Status: Granted
- Kind: B2
- Application number: 16/428,839
- Filed: 2019-05-31
- Published: 2019-09-19
- Granted: 2020-12-22
- Earliest claimed: 2018-01-30
- Assignees: PI Advanced Materials Co., Ltd.
- Applicants: PI Advanced Materials Co., Ltd.
- Inventors: Dong Young Won; Kyung Su Kim; Sung Il Cho; Jeong Yeul Choi
- Web page: https://patentgrep.com/patent/US10870580B2

## CPC

- C01B 32/205: Preparation
- C08G 73/1003: {Preparatory processes}
- C08G 73/1071: {Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain}
- C08J 5/18: Manufacture of films or sheets
- C09K 5/14: Solid materials, e.g. powdery or granular
- C01P 2006/32: Thermal properties
- C08J 2379/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

The present disclosure provides a polyimide film prepared from a precursor composition containing a polyamic acid and an organic solvent and having a value of (first FWHM−second FWHM)/(first FWHM+second FWHM) which is less than 0.4, a graphite sheet prepared from the polyimide film, and a method for preparing a graphite sheet.

## Claims

### Claim 1

A polyimide film prepared from a precursor composition containing a polyamic acid and an organic solvent and having a value of the following Formula 1 less than 0.4:
(first FWHM−second FWHM)/(first FWHM+second FWHM) Formula 1
wherein, when a diffraction peak of (010) plane according to XRD analysis of the polyimide film is in the form of a single peak, the first FWHM (full width at half maximum) indicates a FWHM of the single peak; and when the diffraction peak of (010) plane is in the form of a plurality of single peaks or in the form of a plurality of single peaks overlapped with each other, the first FWHM indicates an average of individual FWHMs of the single peaks, and
when a diffraction peak of (102) plane according to XRD analysis of the polyimide film is in the form of a single peak, the second FWHM indicates a FWHM of the single peak; and when the diffraction peak of (102) plane is in the form of a plurality of single peaks or in the form of a plurality of single peaks overlapped with each other, the second FWHM indicates an average of individual FWHMs of the single peaks,
wherein the polyamic acid is contained in an amount 15 to 20% by weight based on the total weight of the precursor composition, and
a film intermediate derived from the precursor composition is stretched at least once,
wherein the film intermediate is stretched at a temperature of 20 degrees C. to 40 degrees C.

### Claim 2 (depends on 1)

The polyimide film of claim 1, wherein the film intermediate is stretched so that the polyimide film has a thickness of 20 to 125 micrometers.

### Claim 3 (depends on 1)

The polyimide film of claim 1, wherein a stretching ratio in the at least one of the machine direction and the transverse direction is +3% or more and +25% or less.

### Claim 4 (depends on 1)

The polyimide film of claim 1, wherein the polyamic acid is prepared by polymerization of dianhydride monomers and diamine monomers.

### Claim 5 (depends on 1)

The polyimide film of claim 1, wherein the first FWHM is 35 degrees or more and 80 degrees or less, and the second FWHM is 43% or more and 92% or less of the first FWHM.

### Claim 6 (depends on 1)

The polyimide film of claim 1, wherein the value of Formula 1 is 0.01 or more and 0.37 or less.

### Claim 7

A method for preparing a graphite sheet, comprising:
preparing a polyimide film having a value of the following Formula 1 less than 0.4 from a precursor composition containing a polyamic acid and an organic solvent;
carbonizing the polyimide film; and
obtaining a graphite sheet by graphitizing the carbonized polyimide film, wherein the graphite sheet has a thermal conductivity of 1400 W/mK or more:
(first FWHM−second FWHM)/(first FWHM+second FWHM) Formula 1
wherein, when a diffraction peak of (010) plane according to XRD analysis of the polyimide film is in the form of a single peak, the first FWHM (full width at half maximum) indicates a FWHM of the single peak; and when the diffraction peak of (010) plane is in the form of a plurality of single peaks or in the form of a plurality of single peaks overlapped with each other, the first FWHM indicates an average of individual FWHMs of the single peaks, and
when a diffraction peak of (102) plane according to XRD analysis of the polyimide film is in the form of a single peak, the second FWHM indicates a FWHM of the single peak; and when the diffraction peak of (102) plane is in the form of a plurality of single peaks or in the form of a plurality of single peaks overlapped with each other, the second FWHM indicates an average of individual FWHMs of the single peaks,
wherein the polyamic acid is contained in an amount 15 to 20% by weight based on the total weight of the precursor composition, and
a film intermediate derived from the precursor composition is stretched at least once,
wherein the film intermediate is stretched at a temperature of 20 degrees C. to 40 degrees C.

### Claim 8 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the film intermediate is stretched so that the polyimide film has a thickness of 20 to 125 micrometers.

### Claim 9 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the film intermediate is stretched at a stretching ratio of +3% or more and +25% or less in at least one of the machine direction and the transverse direction.

### Claim 10 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the precursor composition is prepared by mixing the polyamic acid in an amount of 15 to 20% by weight and the organic solvent in an amount of 80 to 85% by weight based on the total weight of the precursor composition.

### Claim 11 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the polyamic acid is prepared by polymerization of dianhydride monomers and diamine monomers.

### Claim 12 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the first FWHM is 35 degrees or more and 80 degrees or less, and the second FWHM is 43% or more and 92% or less of the first FWHM.

### Claim 13 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the value of Formula 1 is 0.01 or more and 0.37 or less.

### Claim 14 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the polyimide film is carbonized by heat-treating the polyimide film at a temperature of 1,000 degrees C. to 1,500 degrees C.

### Claim 15 (depends on 7)

The method for preparing a graphite sheet of claim 7, wherein the carbonized polyimide film is graphitized by heat-treating the carbonized polyimide film at a temperature of 2,500 degrees C. to 3,000 degrees C.