# US 11,078,081 B2 · Graphene film prepared with flexible polyimide and preparation method thereof

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- Number: US 11,078,081 B2
- Document ID: US11078081B2
- Status: Granted
- Kind: B2
- Application number: 16/121,227
- Filed: 2018-09-04
- Published: 2020-01-23
- Granted: 2021-08-03
- Earliest claimed: 2016-03-04
- Assignees: Shenzhen Danbond Technology Co., Ltd
- Applicants: Shenzhen Danbond Technology Co., Ltd
- Inventors: Ping Liu
- Web page: https://patentgrep.com/patent/US11078081B2

## CPC

- B32B 27/08: of synthetic resin
- C01B 32/184: Preparation
- B32B 9/007: {comprising carbon, e.g. graphite, composite carbon}
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/281: {comprising polyimides}
- B32B 37/06: characterised by the heating method
- B32B 37/10: characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
- B32B 38/004: {by physically contacting the layers, e.g. by the use of heated platens or rollers}
- B32B 2264/102: Oxide or hydroxide
- B32B 2307/20: having particular electrical or magnetic properties, e.g. piezoelectric
- B32B 2307/212: Electromagnetic interference shielding
- B32B 2307/302: Conductive
- B32B 2307/306: Resistant to heat
- B32B 2307/54: Yield strength; Tensile strength
- B32B 2307/546: Flexural strength; Flexion stiffness
- B32B 2307/706: Anisotropic
- B32B 2307/732: Dimensional properties
- B32B 2309/02: Temperature
- B32B 2313/04: Carbon
- B32B 2379/08: Polyimides
- B32B 2571/00: Protective equipment
- C01B 2204/24: Thermal properties
- C01B 2204/26: Mechanical properties
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

A preparation method of a graphene film prepared with flexible polyimide includes the following steps: S1, laminating a plurality of polyimide films; S2, performing heat treatment while pressing the laminated polyimide films for bonding, wherein the temperature of heat treatment is lower than the temperature at which a thermoplastic polyimide film begins thermal decomposition, so that the laminated polyimide films are bonded together to form a polyimide composite film; and S3, raising the temperature of the polyimide composite film to be higher than the temperature at which the polyimide film begins thermal decomposition for heat treatment and carbonization treatment, thereby obtaining a carbonized multifunctional film, and performing graphitization treatment as required. The graphene film prepared by the present invention has ultra-high thermal conductivity, excellent flexibility and bending resistance, anisotropy and good electrical boundary shielding effect and magnetic boundary shielding effect, and a good application prospect.

## Claims

### Claim 1

A preparation method of a graphene film prepared with flexible polyimide, comprising the following steps:
S1: laminating a plurality of polyimide films;
S2: performing a heat treatment while pressing the laminated polyimide films for bonding, wherein the temperature of the heat treatment is lower than the temperature at which a thermoplastic polyimide film begins thermal decomposition, so that the laminated polyimide films are bonded together to form a polyimide composite film; and
S3: raising the temperature of the polyimide composite film to be higher than the temperature at which the polyimide films begin thermal decomposition for heat treatment and carbonization treatment, thereby obtaining a carbonized multifunctional film, and subjecting the carbonized multifunctional film to a graphitization treatment,
wherein, in step S3, the polyimide composite film is placed in a heating furnace, filled with black lead powder, sealed, heated, and pressurized.

### Claim 2 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein, in step S2, the laminated polyimide films are hot-pressed for bonding using a roller hot press.

### Claim 3 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein the temperature at which the polyimide films begin thermal decomposition is about 500° C., and in step S2, the temperature is raised from 10° C. to 500° C. at a processing rate of 1 m/min and under a pressure of 50 kg/cm2.

### Claim 4 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein each of the polyimide films has a thickness of 50 μm and a glass transition temperature of 400° C., and the temperature at which the polyimide films begin thermal decomposition is about 500° C.

### Claim 5 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein, in step S3, the temperature of the polyimide composite film is raised from 500° C. to 1000° C.-1500° C. at a processing rate of 1 m/min, and the polyimide composite film is subjected to carbonization treatment under a pressure of 75 kg/cm2.

### Claim 6 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein, in step S3, the graphitization treatment includes graphitizing the carbonized multifunctional film by raising the temperature from 1500° C. to 2000° C. in a graphitization furnace at a processing rate of 0.5 m/min and under a pressure of 100 kg/cm2 to obtain a vitrified carbon film.

### Claim 7 (depends on 6)

The preparation method of graphene film prepared with flexible polyimide according to claim 6, wherein the vitrified carbon film is further heated in the graphitization furnace from 2000° C. to 2800° C., and subjected to a further graphitization treatment at a processing rate of 0.4 m/min and under a pressure of 120 kg/cm2, to obtain a graphitized multifunctional film.

### Claim 8 (depends on 7)

The preparation method of graphene film prepared with flexible polyimide according to claim 7, wherein the graphitized multifunctional film is further heated in the graphitization furnace from 2800° C. to 3200° C., and subjected to a further graphitization treatment at a processing rate of 0.4 m/min and under a pressure of 150 kg/cm2, to obtain a vitric carbon multifunctional graphene film.

### Claim 9 (depends on 1)

The preparation method of graphene film prepared with flexible polyimide according to claim 1, wherein the temperature of the polyimide composite film is raised in a non-oxidizing environment.