阅读说明：本技术 一种石墨烯导热厚膜的制备方法 (Preparation method of graphene heat-conducting thick film ) 是由 金闯 李炜罡 于 2021-10-08 设计创作，主要内容包括：本发明公开了一种石墨烯导热厚膜的制备方法,包括以下步骤：采用热喷涂法将氧化石墨烯分散液喷涂于基膜上；干燥,形成氧化石墨烯层与基膜层的复合膜；对氧化石墨烯层进行还原；对复合膜进行碳化和石墨化；将碳化和石墨化的复合膜压制成石墨烯导热厚膜。本发明通过氧化石墨烯膜和由PI(聚酰亚胺)制备的人工石墨层进行复合,并一起进行热处理,解决了现有厚膜分层的问题,可制备出较厚的高导热的石墨烯复合膜,厚度可达300微米,且不分层不掉粉,耐弯折性能高。(The invention discloses a preparation method of a graphene heat-conducting thick film, which comprises the following steps: spraying the graphene oxide dispersion liquid on a base film by adopting a thermal spraying method; drying to form a composite film of the graphene oxide layer and the base film layer; reducing the graphene oxide layer; carbonizing and graphitizing the composite film; and pressing the carbonized and graphitized composite film into the graphene heat-conducting thick film. According to the invention, the graphene oxide film and the artificial graphite layer prepared from PI (polyimide) are compounded and are subjected to heat treatment together, so that the problem of layering of the conventional thick film is solved, and the thick high-thermal-conductivity graphene composite film can be prepared, has the thickness of 300 microns, does not delaminate, does not fall powder, and has high bending resistance.)

1. A preparation method of a graphene heat-conducting thick film is characterized by comprising the following steps:

spraying the graphene oxide dispersion liquid on a base film by adopting a thermal spraying method;

drying to form a composite film of the graphene oxide layer and the base film layer;

reducing the graphene oxide layer;

carbonizing and graphitizing the composite film;

and pressing the carbonized and graphitized composite film into the graphene heat-conducting thick film.

2. The method for preparing the graphene thermal conductive thick film according to claim 1, wherein the graphene oxide dispersion is prepared by mixing graphene oxide with N-methylpyrrolidone, dispersing and filtering.

3. The preparation method of the graphene thermal conductive thick film according to claim 2, wherein the mass ratio of the graphene oxide to the N-methylpyrrolidone is 1: 8-10.

4. The preparation method of the graphene thermal conductive thick film according to claim 2, wherein the rotation speed of the dispersion is 2000-2200 r/min, and the aperture of the filter screen for filtration is 500-600 meshes.

5. The preparation method of the graphene thermal conductive thick film according to claim 1, wherein the thickness of the base film is 90-100 μm, and the thickness of the dried composite film is 250-260 μm.

6. The method for preparing the graphene thermal conductive thick film according to claim 1, wherein the graphene oxide layer is reduced by thermal reduction or a reducing agent is added before spraying.

7. The preparation method of the graphene thermal conductive thick film according to claim 6, wherein the thermal reduction method comprises spraying a HI solution with a concentration of 10% on the surface of the graphene oxide layer, and then drying at a temperature of 65-70 ℃ for 10-12 h.

8. The method of claim 1, wherein the carbonization temperature is less than 1000 ℃ and the graphitization temperature is less than 3000 ℃.

9. The method for preparing the graphene thermal conductive thick film according to claim 1, wherein the pressing to form the graphene thermal conductive thick film is to flat press or roll the composite film on a release film or a protective film, and then to strip the composite film.

Technical Field

The invention belongs to the technical field of graphene heat-conducting films, and particularly relates to a preparation method of a graphene heat-conducting thick film.

Background

With the rapid development of modern microelectronic technology, electronic devices (such as notebook computers, mobile phones, tablet computers, notebook computers and the like) become increasingly ultra-thin and portable, the internal power density of the electronic devices is obviously improved due to the structure, and heat generated in operation is not easy to discharge and is easy to accumulate quickly to form high temperature. On the other hand, high temperatures can reduce the performance, reliability, and service life of electronic devices. Therefore, the current electronic industry puts higher and higher requirements on heat dissipation materials serving as core components of a thermal control system, and an efficient heat-conducting and light material is urgently needed to rapidly transfer heat out and ensure normal operation of electronic equipment. In addition, plasma-facing materials for solid rocket engine throat liners and nuclear fusion reactors are required to have high-efficiency heat-conducting properties.

Graphene is a novel two-dimensional carbon material formed by hexagonal close packing of carbon atoms in a plane. Graphene, the thinnest substance known in the world at present, has received worldwide attention due to its unique and excellent physicochemical properties since its discovery in 2004, and graphene thermal conductive films also have the advantages of excellent mechanical properties, low density, small thermal expansion coefficient and the like, and are considered to be a highly efficient thermal conductive material with great development potential.

The current industrialized heat conduction materials are mainly metal materials (such as copper and aluminum), natural graphite, artificial graphite films and graphene heat conduction films, the metal materials are generally pressed into products with different thicknesses, and the products are called copper foils or aluminum foils and are characterized by high density, hard surfaces and difficult contact with heat dissipation interfaces. And the heat conductivity coefficient is low and can only reach 200-400 w.m/k. The natural graphite heat-conducting film has the advantages of low price, wide application, capability of being made into materials with various thicknesses, low heat conductivity coefficient, poor physical properties and easiness in wrinkling and powder falling. The raw material of the artificial graphite heat-conducting film is a polyimide film, and the artificial graphite heat-conducting film has the advantages of high heat-conducting coefficient which can reach 1000-1800 w.m/k, environmental pollution in the manufacturing process, low application range and thickness of a common product which is less than 50 microns.

With the popularization of the 5G technology and the proposal of the heat flux concept, the thickness of the heat conduction material becomes a key index. The thickness of the graphene heat conduction film gradually increases from 40 micrometers to 200 micrometers, and the graphene heat conduction film continuously increases to 300-500 micrometers. However, with the increase of the thickness of the product, the difficulty of the back-end process is more and more increased, for example, delamination and powder falling are easily generated, and the bending resistance of the product is remarkably reduced, which troubles the development of the graphene heat-conducting film. In response to this problem, we developed a new process for graphene thermal conductive films.

Disclosure of Invention

The invention aims to overcome the defects, and provides a preparation method of a graphene heat-conducting thick film, which can be used for preparing a thicker graphene composite film with high heat conductivity, and the graphene heat-conducting thick film is a continuous coiled material and is convenient to use.

In order to realize the purpose, the invention is realized by the following technical scheme:

a preparation method of a graphene heat-conducting thick film comprises the following steps:

spraying the graphene oxide dispersion liquid on a base film by adopting a thermal spraying method;

drying to form a composite film of the graphene oxide layer and the base film layer;

reducing the graphene oxide layer;

carbonizing and graphitizing the composite film;

and pressing the carbonized and graphitized composite film into the graphene heat-conducting thick film.

Preferably, the graphene oxide dispersion liquid is prepared by mixing graphene oxide and N-methyl pyrrolidone, dispersing and filtering, and the dispersion liquid is favorable for film formation and does not reduce the performance of a final product.

Preferably, the mass ratio of the graphene oxide to the N-methyl pyrrolidone is 1: 8-10.

Preferably, the rotating speed of the dispersion is 2000-2200 r/min, and the aperture of the filtering screen is 500-600 meshes.

Preferably, the base film can be a polyimide film, the thickness of the base film is 90-100 mu m, and the thickness of the dried composite film is 250-260 mu m.

Preferably, the graphene oxide layer is reduced by thermal reduction or by adding a reducing agent, such as an aqueous solution of VC, before spraying.

Preferably, the thermal reduction method comprises the steps of spraying a small amount of HI solution with the concentration of 10% on the surface of the graphene oxide layer, and then preserving heat for 10-12 hours at the temperature of 65-70 ℃ for drying.

Preferably, the carbonization temperature is less than 1000 ℃, and the graphitization temperature is less than 3000 ℃ so as to ensure that graphite crystals are formed.

Preferably, the pressing process for the graphene heat-conducting thick film is to flatly press or roll the composite film on the release film or the protective film, and then strip the composite film.

The thickness of the graphene heat-conducting thick film prepared by the method is usually 100-200 mu m, and thicker heat-conducting thick films can be pressed, and the thickness can reach 300 mu m at most.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the graphene oxide film and the artificial graphite layer prepared from PI (polyimide) are compounded, and compared with the traditional thermal spraying process in which the graphene oxide film is sprayed on the bottom film and the back surface of the graphene oxide film is separated from the bottom film, the graphene oxide film and the bottom film are subjected to thermal treatment together, so that the problem of thick film layering is solved, a thicker graphene composite film with high thermal conductivity can be prepared, the thickness can reach 300 micrometers, no layering and no powder falling occur, and the bending resistance is high.

Detailed Description

Preferred embodiments of the present invention will be described in more detail with reference to specific examples.

Example 1

A preparation method of a graphene heat-conducting thick film comprises the following steps:

(1) dispersing 10 kg of graphene oxide dry powder in 90 kg of N-methyl pyrrolidone, treating for 4 hours in a high-speed dispersion machine at 2000r/min, and screening by using a 500-mesh screen;

(2) spraying a graphene oxide aqueous solution on a polyimide film with the thickness of 100 microns by adopting a thermal spraying method, wherein the length of the polyimide film is 100 meters, drying the polyimide film to form a composite film of a graphene oxide layer and a base film layer, and the total thickness of the graphene oxide layer and the base film layer is 250 microns after drying;

(3) spraying a small amount of 10% HI solution on the surface of the graphene oxide, drying in an oven at the temperature of 65 ℃, and preserving heat for 12 hours;

(4) carbonizing and graphitizing, wherein the highest carbonizing temperature is 1000 ℃, and the highest graphitizing temperature is 3000 ℃;

(5) the graphene heat-conducting thick film is obtained through a roller press, the thickness of the graphene heat-conducting thick film is 200 micrometers, the heat conductivity coefficient of the graphene heat-conducting thick film is 1400W/M.K, and the 180-degree bending resistance times exceed 1 ten thousand times.

Example 2

A preparation method of a graphene heat-conducting thick film comprises the following steps:

(1) dispersing 10 kg of graphene oxide dry powder in 80 kg of N-methyl pyrrolidone, treating for 4 hours in a high-speed dispersion machine at 2000r/min, and screening by using a 500-mesh screen;

(2) spraying a graphene oxide aqueous solution on a polyimide film with the thickness of 100 microns by adopting a thermal spraying method, wherein the length of the polyimide film is 100 meters, drying the polyimide film to form a composite film of a graphene oxide layer and a base film layer, and the total thickness of the graphene oxide layer and the base film layer is 250 microns after drying;

(3) spraying a small amount of 10% HI solution on the surface of the graphene oxide, drying in an oven at the temperature of 65 ℃, and preserving heat for 12 hours;

(4) carbonizing and graphitizing, wherein the highest carbonizing temperature is 1000 ℃, and the highest graphitizing temperature is 3000 ℃;

(5) the graphene heat-conducting thick film is obtained through a roller press, the thickness of the graphene heat-conducting thick film is 180 micrometers, the heat conductivity coefficient of the graphene heat-conducting thick film is 1400W/M.K, and the 180-degree bending resistance times exceed 1 ten thousand times.

Example 3

A preparation method of a graphene heat-conducting thick film comprises the following steps:

(1) dispersing 10 kg of graphene oxide dry powder in 100 kg of N-methyl pyrrolidone, treating for 4 hours in a high-speed dispersion machine at 2200r/min, and screening by a 500-mesh screen;

(2) spraying a graphene oxide aqueous solution on a polyimide film with the thickness of 100 microns by adopting a thermal spraying method, wherein the length of the polyimide film is 100 meters, drying the polyimide film to form a composite film of a graphene oxide layer and a base film layer, and the total thickness of the graphene oxide layer and the base film layer is 250 microns after drying;

(3) spraying a small amount of 10% HI solution on the surface of the graphene oxide, drying in an oven at the temperature of 65 ℃, and preserving heat for 12 hours;

(4) carbonizing and graphitizing, wherein the highest carbonizing temperature is 1000 ℃, and the highest graphitizing temperature is 3000 ℃;

(5) the graphene heat-conducting thick film is obtained through a roller press, the thickness of the graphene heat-conducting thick film is 300 microns, the heat conductivity coefficient of the graphene heat-conducting thick film is 1400W/M.K, and the 180-degree bending resistance times exceed 1 ten thousand times.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and technical principles of the described embodiments, and such modifications and variations should also be considered as within the scope of the present invention.