CN114394585B

CN114394585B - Composite film, preparation method thereof and electronic equipment

Info

Publication number: CN114394585B
Application number: CN202111662048.5A
Authority: CN
Inventors: 王乾龙; 张艳; 章登科; 陈德权; 廖祥; 林锦盛
Original assignee: Shenzhen Shen Rui Graphene Technology Co ltd
Current assignee: Shenzhen Shen Rui Graphene Technology Co ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2023-08-04
Anticipated expiration: 2041-12-31
Also published as: CN114394585A

Abstract

The application relates to a composite film, a preparation method thereof and electronic equipment, wherein the composite film comprises graphene which is arranged in a laminated mode, carbon nanotubes are connected between graphene sheets, and interlayer bonding force between the graphene sheets is 80 gf-150 gf. According to the composite material, the carbon nanotubes are used as the supporting bodies to connect the grapheme, on one hand, the uniformity of graphene dispersion is enhanced due to the fact that the carbon nanotubes exist among the grapheme, on the other hand, the carbon nanotubes are connected with the grapheme through chemical bonds of the carbon nanotubes, the mutual binding force of the grapheme and the carbon nanotubes is enhanced, the interlayer binding force of a grapheme composite film layer is improved, and guarantee is provided for continuous preparation feasibility of a grapheme coiled material film.

Description

Composite film, preparation method thereof and electronic equipment

Technical Field

The application belongs to the field of graphene heat dissipation materials, and particularly relates to a composite film, a preparation method thereof and electronic equipment.

Background

With the rapid development of the 5G electronic industry, the electronic products are miniaturized, multifunctional and high-performance, and meanwhile, the heat generated in unit area is also rapidly increased, so that the heat dissipation becomes a critical problem, and the performance and reliability of the electronic products, batteries and other high-power systems are restricted. Graphene is one of new materials attracting attention in the 21 st century, and has excellent electric conduction, heat conduction and mechanical properties due to its unique structure, so that a heat conduction and heat dissipation material developed based on graphene is or will be introduced as a mainstream heat dissipation material in the future.

In the existing graphene heat dissipation material, the graphene is mainly used for preparing a film material through directional self-assembly of graphene oxide, however, in the directional self-assembly film forming process of the graphene oxide, as the oxygen content of the graphene oxide is high, high oxygen content functional groups are removed by heat treatment to generate more holes in the film, so that the expansion degree of the graphene film is high, the film is extremely easy to break, and the product yield is seriously affected. In addition, the high-oxygen-content graphite oxide leads to lower solid content of the graphite oxide slurry obtained after dispersion and homogenization, and the coating efficiency and the single-layer film thickness are lower, so that the mass production is not facilitated.

The graphene heat dissipation film material can also be prepared by compounding the carbon material, however, the additives such as a dispersing agent, a binder, a plasticizer, an organic solvent and the like are often introduced into the compounded carbon material, and the use of the additives is not suitable for the existing graphene composite film batch preparation process.

Therefore, development of a graphene composite heat conducting film with low expansion is urgently needed.

Disclosure of Invention

The purpose of the application is to provide a composite film, a preparation method thereof and electronic equipment, wherein the composite film has low expansion degree, high interlayer binding force and difficult layering, and can realize batch preparation.

In a first aspect, an embodiment of the present application provides a composite film, where the composite film includes graphene that is stacked, carbon nanotubes are connected between graphene sheets, and an interlayer bonding force between the graphene sheets is 80 gf-150 gf.

With reference to the first aspect, in a possible embodiment, the graphene and the carbon element of the carbon nanotube form at least one of a five-membered ring structure and a six-membered ring structure.

With reference to the first aspect, in a possible implementation manner, the mass ratio of the graphene to the carbon nanotubes is 1: (0.01-0.1).

With reference to the first aspect, in a possible embodiment, the carbon nanotubes include at least one of single wall, double wall, and multi wall.

With reference to the first aspect, in a possible implementation manner, the tube length of the carbon nanotube is 5 μm to 50 μm.

With reference to the first aspect, in a possible implementation manner, the tube diameter of the carbon nanotube is 4nm to 100nm.

With reference to the first aspect, in a possible implementation manner, the morphology of the carbon nanotube includes at least one of a winding type and an array type.

With reference to the first aspect, in a possible implementation manner, the composite film includes at least two single-layer film materials disposed in a stacked manner, where the single-layer film materials include graphene with carbon nanotubes connected between layers.

With reference to the first aspect, in a possible implementation manner, the composite film includes at least two single-layer film materials that are stacked, where the single-layer film material includes graphene with carbon nanotubes connected between layers, and the thickness of the single-layer film material is 25 μm to 35 μm.

With reference to the first aspect, in a possible embodiment, the thickness of the composite film is 50 μm to 300 μm.

With reference to the first aspect, in a possible implementation manner, the thermal conductivity of the composite film is 800W/mK to 1500/mK.

With reference to the first aspect, in a possible embodiment, the tensile strength of the composite film is 60MPa to 120MPa.

With reference to the first aspect, in a possible embodiment, the composite film is a surface-line-surface three-dimensional structure.

In a second aspect, embodiments of the present application provide a method for preparing a composite film, including the steps of:

coating the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to obtain a graphene oxide/functionalized graphene/carbon nanotube composite film, wherein the functionalized carbon nanotubes comprise at least one of hydroxylated carbon nanotubes, aminated carbon nanotubes and epoxidized carbon nanotubes;

And performing heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups to obtain the composite film.

With reference to the second aspect, the preparation process of the slurry containing graphene oxide, graphene and functionalized carbon nanotubes comprises the following steps: obtaining graphene oxide slurry, and performing first dispersion treatment on the graphene oxide slurry and the graphene to obtain a slurry containing graphene oxide and graphene; and carrying out second dispersion treatment on the slurry containing the graphene oxide and the graphene and the functionalized carbon nano tube to obtain the slurry containing the graphene oxide, the graphene and the functionalized carbon nano tube.

With reference to the second aspect, in a possible implementation manner, performing a first dispersion treatment on the graphene oxide slurry and the graphene to obtain a slurry containing graphene oxide and graphene specifically includes: and preparing a part of the graphene oxide slurry to form graphene oxide dispersion liquid, mixing the graphene oxide dispersion liquid with the graphene, and adding the rest of the graphene oxide slurry to perform homogenization treatment to obtain the slurry containing the graphene oxide and the graphene.

With reference to the second aspect, in a possible embodiment, the mass of graphene oxide in the partial graphene oxide slurry is 0.01% to 0.1% of the mass of graphene.

With reference to the second aspect, in a possible embodiment, the carbon content of the graphene is 70% or more.

With reference to the second aspect, in one possible embodiment, the mixing of the graphene oxide dispersion with graphene is performed under stirring conditions.

With reference to the second aspect, in a possible embodiment, the pressure of the homogenizing treatment is 500bar to 1250bar.

With reference to the second aspect, in a possible embodiment, the temperature of the homogenizing treatment is 10 ℃ to 25 ℃.

With reference to the second aspect, in a possible implementation, the number of homogenizing treatments is 2 to 4.

With reference to the second aspect, in a possible embodiment, the pH of the slurry containing graphene oxide and graphene is 6 to 8.

With reference to the second aspect, in a possible embodiment, the mass ratio of graphene oxide, graphene and functionalized carbon nanotubes in the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is 1: (0.1-1): (0.01-0.1).

With reference to the second aspect, in a possible embodiment, the functionalized carbon nanotube includes at least one of single wall, double wall, and multi wall.

With reference to the second aspect, in a possible embodiment, the functionalized carbon nanotubes have a tube length of 5 μm to 50 μm.

With reference to the second aspect, in a possible embodiment, the tube diameter of the functionalized carbon nanotube is 4nm to 100nm.

With reference to the second aspect, in a possible embodiment, the second dispersion treatment includes a step of sequentially performing a stirring treatment and a grinding treatment on the slurry containing graphene oxide and graphene and the functionalized carbon nanotubes.

With reference to the second aspect, in a possible embodiment, the method further includes a step of defoaming the slurry containing graphene oxide, graphene and functionalized carbon nanotubes before the step of coating the slurry containing graphene oxide, graphene and functionalized carbon nanotubes.

With reference to the second aspect, in a possible embodiment, the thickness of the wet film of the graphene oxide/graphene/functionalized carbon nanotube composite film obtained by the coating treatment is 2400 mm-3500 mm.

With reference to the second aspect, in a possible embodiment, the temperature of the defoaming treatment is 15 ℃ to 20 ℃.

With reference to the second aspect, in a possible implementation manner, the time of the defoaming treatment is 10min to 30min.

With reference to the second aspect, in a possible embodiment, the solids content of the material after the defoaming treatment is 5% to 20%.

With reference to the second aspect, in a possible embodiment, the viscosity of the defoamed material is 30000cps to 70000cps.

With reference to the second aspect, in a possible embodiment, the heat treatment includes a pretreatment, a carbonization treatment, and a graphitization treatment.

With reference to the second aspect, in a possible embodiment, the temperature of the pretreatment is 100 ℃ to 400 ℃.

With reference to the second aspect, in a possible embodiment, the temperature rising rate of the pretreatment is 5 ℃/min to 10 ℃/min.

With reference to the second aspect, in a possible embodiment, the pretreatment time is 5h to 10h.

With reference to the second aspect, in a possible embodiment, the carbonization treatment is performed under vacuum conditions.

With reference to the second aspect, in a possible embodiment, the carbonization treatment is performed at a temperature of 1000 ℃ to 1500 ℃.

With reference to the second aspect, in a possible embodiment, the temperature rise rate of the carbonization treatment is 5 ℃/min to 30 ℃/min.

With reference to the second aspect, in a possible embodiment, the carbonization treatment takes 5 to 24 hours.

With reference to the second aspect, in a possible embodiment, the graphitization treatment is performed at a temperature of 2600 ℃ to 3100 ℃.

With reference to the second aspect, in a possible embodiment, the temperature rising rate of the graphitization treatment is 10 ℃/min to 30 ℃/min.

With reference to the second aspect, in a possible embodiment, the graphitization treatment is performed in a protective atmosphere comprising at least one of argon and nitrogen.

With reference to the second aspect, in a possible embodiment, the graphitization treatment takes 10 to 72 hours.

With reference to the second aspect, in a possible embodiment, the carbonization treatment and the graphitization treatment are performed in the same apparatus.

With reference to the second aspect, in a possible embodiment, the step of performing a compaction treatment further includes performing a heat treatment on the graphene oxide/graphene/functionalized carbon nanotube composite film to remove oxygen-containing functional groups.

With reference to the second aspect, in one possible embodiment, the densified substrate includes at least one of polyethylene, polyethylene terephthalate, polypropylene, and oriented polypropylene.

With reference to the second aspect, in a possible embodiment, the compacting treatment is performed at a pressure of 2MPa to 50MPa.

In a third aspect, embodiments of the present application provide an electronic device, where the electronic device includes the composite film according to the first aspect or the composite film manufactured by the manufacturing method according to the second aspect.

The technical scheme of the application has the following beneficial effects: according to the composite film, the carbon nanotubes are used as a supporting body to connect graphene, on one hand, the uniformity of graphene dispersion is enhanced due to the fact that the carbon nanotubes exist between the sheets of the graphene, on the other hand, the carbon nanotubes are connected with the graphene through chemical bonds of the carbon nanotubes, the mutual binding force of the graphene and the carbon nanotubes is enhanced, the interlayer binding force between the sheets of the graphene is improved to 80 gf-150 gf, the expansion is low, layering of the graphene film can be effectively inhibited, the composite film is not fragile, the product yield of the composite film is improved, and guarantee is provided for continuous preparation feasibility of the graphene coiled material film.

According to the composite membrane, the slurry containing graphene oxide, graphene and the functionalized carbon nano tube is used as a preparation raw material, on one hand, holes and layering caused by volatilization of oxygen-containing functional groups in the graphene oxide at a high temperature can be restrained, so that the expansion problem of the composite membrane can be effectively weakened, and the preparation of the composite membrane with low expansion degree is realized. In addition, the addition of graphene and the functionalized carbon nanotubes can effectively improve the solid content of the slurry in the composite film, further improve the thickness of the composite film, improve the coating efficiency of the slurry and be beneficial to batch production. On the other hand, the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is coated and heat-treated, the carbon nanotubes in the slurry are loaded on graphene sheets through the action of functional groups and graphene oxide and the surface and edge groups of the graphene through the action of chemical bonds, the graphene sheets are self-assembled into a layered structure through coating treatment, and the interlayer bonding force between the graphene sheets is improved to 80 gf-150 gf through a heat treatment process. The preparation of the composite film does not add other dispersing agents, surfactants and binders, does not introduce impurity atoms, and has good slurry uniformity.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic illustration of a first process for preparing a composite membrane of the present application;

FIG. 2 is a diagram of a reaction mechanism of an aminated carbon nanotube and graphene oxide according to the present application;

FIG. 3 is an AFM image of a slurry containing graphene oxide, graphene and functionalized carbon nanotubes obtained in example 1 of the present application;

FIG. 4 is an SEM image of a graphene/aminated carbon nanotube composite film obtained in example 1 of the present application;

FIG. 5 is a graph of interlayer peel force data of a graphene/carbon nanotube composite film of example 1 obtained by referring to the test method of the peel strength of the adhesive tape of GB 2792-2014;

fig. 6 is a graph showing the mechanical properties of the graphene/aminated carbon nanotube composite film obtained in example 1 of the present application compared with the graphene film obtained in comparative example 1.

Detailed Description

For a better understanding of the technical solution of the present invention, the following detailed description of the embodiments of the present invention refers to the accompanying drawings.

It should be understood that the described embodiments are merely some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

The embodiment of the application discloses a composite film, the composite film includes the graphene of range upon range of setting, is connected with the carbon nanotube between the lamellar of graphene, and the interlaminar cohesion between the graphene lamellar is 80gf ~ 150gf.

In the technical scheme, the graphene is connected by taking the carbon nanotubes as the supporting body, so that on one hand, the uniformity of graphene dispersion is enhanced due to the fact that the carbon nanotubes exist among the graphene, on the other hand, the carbon nanotubes are connected with the graphene through chemical bonds of the carbon nanotubes, the mutual binding force of the graphene and the carbon nanotubes is enhanced, the interlayer binding force between graphene sheets is improved to 80 gf-150 gf, and the guarantee is provided for the continuous preparation feasibility of the graphene coiled material film. The composite film has larger interlayer binding force between graphene layers, can effectively inhibit layering of the graphene film, is not fragile, improves the product yield of the composite film, and can be used for preparing graphene heat-conducting film coiled materials.

In some embodiments, the interlayer bonding force between graphene sheets is 80gf to 150gf, and the interlayer bonding force between graphene sheets may be specifically 80gf, 90gf, 100gf, 110gf, 120gf, 130gf, 140gf, 150gf, or the like, but may be other values within the above range, and is not limited thereto. The applicant found that the interlayer bonding force in the above range can inhibit delamination of the composite film and improve the product yield of the composite film.

In some embodiments, the graphene and the carbon element of the carbon nanotube form at least one of a five-membered ring structure and a six-membered ring structure, and it can be understood that the graphene and the carbon nanotube are connected through the five-membered ring and/or the six-membered ring structure, specifically, a single five-membered ring structure can be formed between the graphene and the carbon nanotube, a single six-membered ring structure can also be formed, and the five-membered ring and the six-membered ring can also exist at the same time.

In some embodiments, the mass ratio of graphene to carbon nanotubes is 1: (0.01-0.1), the mass ratio of graphene to carbon nano tube is 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09 and 1:0.1, etc., but may be any other value within the above range, and is not limited thereto. The mass ratio of graphene to carbon nanotubes is less than 1:0.01, excessive carbon nano tubes are added, so that the carbon nano tubes are difficult to disperse and easy to agglomerate, the uniformity of the prepared film material is poor, and film rupture is easy to occur at the agglomeration position; the mass ratio of graphene to carbon nanotubes is greater than 1:0.1, the addition amount of the carbon nano tube is too small, so that the mechanical property of the composite film cannot be effectively improved.

In some embodiments, the carbon nanotubes comprise at least one of single wall, double wall, and multi wall.

In some embodiments, the tube length of the carbon nanotubes is 5 μm to 50 μm, and the tube length of the carbon nanotubes may specifically be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc., but may of course be other values within the above range, and is not limited thereto.

In some embodiments, the tube diameter of the carbon nanotubes is 4nm to 100nm, and the tube diameter of the carbon nanotubes may specifically be 4nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc., but may also be other values within the above range, and is not limited thereto.

In some embodiments, the morphology of the carbon nanotubes includes at least one of a wrap-around type and an array type.

In some embodiments, the composite film comprises at least two single-layer film materials arranged in a stacked manner, wherein carbon nanotubes are connected between graphene sheets in the single-layer film materials.

In some embodiments, the composite film has a surface-line-surface three-dimensional structure, and it can be understood that carbon nanotubes are connected between graphene sheets in the single-layer film material, the graphene has a two-dimensional sheet structure, the carbon nanotubes have a one-dimensional linear structure, that is, the single-layer film material has a three-dimensional structure formed by surface-line-surface, and the composite film also has a surface-line-surface three-dimensional structure due to the fact that the composite film comprises at least two single-layer film materials which are stacked, and the three-dimensional structure is beneficial to improving interlayer bonding force between the graphene sheets.

In some embodiments, the thickness of the single-layer film material is 25 μm to 35 μm, and the thickness of the single-layer film material may specifically be 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, or the like, but may be other values within the above range, and is not limited thereto. Preferably, the thickness of the single layer film material is 25 μm to 30 μm.

In some embodiments, the thickness of the composite film is 50 μm to 300 μm, and the thickness of the composite film may be specifically 50 μm, 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 220 μm, 250m, 280 μm, 300 μm, etc., but may be other values within the above range, and is not limited thereto.

In some embodiments, the thermal conductivity of the composite film is 800W/mK to 1500W/mK, and the thermal conductivity of the composite film may be 800W/mK, 900K, 1000W/mK, 1100W/mK, 1200W/mK, 1300W/mK, 1400W/mK, 1500W/mK, etc., but may be other values within the above range, and is not limited thereto.

In some embodiments, the tensile strength of the composite film is 60MPa to 120MPa, and the tensile strength of the composite film may specifically be 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, 110MPa, 120MPa, or the like, but may be other values within the above range, and is not limited thereto.

The embodiment of the application also provides a preparation method of the composite film, as shown in fig. 1, which is a preparation flow chart of the composite film, and comprises the following steps:

and step S100, coating the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to obtain the graphene oxide/graphene/functionalized carbon nanotube composite film, wherein the functionalized carbon nanotubes comprise at least one of hydroxylated carbon nanotubes, aminated carbon nanotubes and epoxidized carbon nanotubes.

And step 200, performing heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups to obtain the composite film.

In the technical scheme, the composite membrane adopts the slurry containing graphene oxide, graphene and the functionalized carbon nano tube as the preparation raw material, on one hand, the cavitation and layering caused by volatilization of the oxygen-containing functional group in the graphene oxide at high temperature can be inhibited, so that the expansion problem of the composite membrane can be effectively weakened, and the preparation of the composite membrane with low expansion degree is realized. In addition, the addition of graphene and the functionalized carbon nanotubes can effectively improve the solid content of the slurry in the composite film, so that the thickness of the composite film is improved, the coating efficiency of the slurry is improved, and the mass production is facilitated. On the other hand, the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is coated and heat-treated, the functionalized carbon nanotubes in the slurry are loaded on the graphene sheets through the action of functional groups and the graphene oxide and the groups on the surfaces and edges of the graphene, the graphene sheets are self-assembled into a layered structure through coating treatment, and the interlayer bonding force between the graphene sheets is improved to 80 gf-150 gf through a heat treatment process. The preparation of the composite film does not add other dispersing agents, surfactants and binders, does not introduce impurity atoms, and has good slurry uniformity.

In the technical scheme, the functional groups of the functional carbon nano tube can be uniformly dispersed between graphene oxide and graphene sheets on one hand, so that the dispersion uniformity is improved, and agglomeration is prevented; on the other hand, the chemical bond action of the functional groups of the functionalized carbon nanotubes can enhance the mutual binding force between graphene and the carbon nanotubes, the carbon nanotubes are of a one-dimensional linear structure, the graphene is of a two-dimensional lamellar structure, the one-dimensional carbon nanotubes play a good mechanical traction role between the two-dimensional graphene lamellar layers, and the binding force of the composite film can be improved. As shown in fig. 2, when the aminated carbon nanotube is used, the amide of the carboxyl group on the aminated carbon nanotube and the graphite oxide undergoes a dehydration reaction to reduce the content of the carboxyl functional group on the graphite oxide and neutralize the acidity, which is advantageous in suppressing the swelling delamination of the composite film.

The following describes the preparation method of the present application in detail with reference to examples, including the following steps:

In some embodiments, the apparatus for the coating process comprises an automated coater.

In some embodiments, the wet film after the coating treatment has a thickness of 2400mm to 3500mm, and the thickness may be 2400mm, 2500mm, 2600mm, 2700mm, 2800mm, 2900mm, 3000mm, 3100mm, 3200mm, 3300mm, 3400mm, 3500mm, or the like, although other values within the above range are also possible, and the present invention is not limited thereto.

In some embodiments, the coating process requires drying and sectioning of the wet film after it is obtained.

In some embodiments, the temperature of the drying is 60 to 95 ℃, and the temperature of the drying may be 60 to 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃ or the like, but may be other values within the above range, and the drying is not limited thereto.

In some embodiments, the drying time is 6h to 9h, and the drying temperature may be, for example, 6h, 7h, 8h, 9h, or the like, but may be other values within the above range, which is not limited thereto.

In some embodiments, before performing step S100, the method further includes a step of defoaming the slurry containing graphene oxide, graphene, and functionalized carbon nanotubes. Firstly, defoaming slurry containing graphene oxide, graphene and functionalized carbon nanotubes, and then coating to form a film.

In some embodiments, the apparatus for the defoaming treatment comprises an in-line continuous centrifugal defoaming machine.

In some embodiments, the temperature of the defoaming treatment is 15 to 20 ℃, and the temperature of the defoaming treatment may be, for example, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, or the like, but may be other values within the above range, and the present invention is not limited thereto.

In some embodiments, the time of the defoaming treatment is 10min to 30min, and the time of the defoaming treatment may be, for example, 10min, 12min, 15min, 16min, 17min, 20min, 22min, 25min, 27min, 29min, 30min, or the like, but may be other values within the above range, which is not limited thereto.

In some embodiments, the solids content and viscosity of the resulting material are tested after the de-bubbling treatment to ensure that it meets the coating process conditions.

In some embodiments, the solids content of the defoamed material is 5% to 20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and 20%, etc., but may be other values within the above range, and the solid content is not limited thereto. The solid content of the material after the defoaming treatment is controlled within the range, which is beneficial to the thickness improvement of the composite film.

In some embodiments, the viscosity of the defoamed material is 30000cps to 70000cps, and the viscosity may be 30000cps, 40000cps, 45000cps, 50000cps, 55000cps, 60000cps, 65000cps, and 70000cps, or other values within the above range, without limitation. The solid content of the material after the defoaming treatment is controlled within the range, so that the composite coating process condition is ensured.

In some embodiments, a slurry containing graphene oxide, graphene, and functionalized carbon nanotubes is prepared by:

and (3) obtaining graphene oxide slurry, and performing first dispersion treatment on the graphene oxide slurry and graphene to obtain slurry containing graphene oxide and graphene. And carrying out second dispersion treatment on the slurry containing the graphene oxide and the graphene and the functionalized carbon nano tube to obtain the slurry containing the graphene oxide, the graphene and the functionalized carbon nano tube.

Specifically, graphene oxide slurry is obtained, a part of the graphene oxide slurry is prepared to form graphene oxide dispersion liquid, the graphene oxide dispersion liquid is mixed with graphene, the rest of the graphene oxide slurry is added to carry out homogenization treatment on the slurry containing graphene oxide and graphene, and the slurry containing graphene oxide and graphene is mixed with functionalized carbon nanotubes to carry out stirring treatment and grinding treatment to obtain the slurry containing graphene oxide, graphene and functionalized carbon nanotubes.

In the preparation steps, graphene oxide slurry is obtained firstly, then a graphene oxide dispersion liquid is prepared from part of the graphene oxide slurry, and finally graphene oxide is fully contacted with graphene through dispersing graphene in the graphene oxide dispersion liquid, so that the uniformity and stability of the graphene in the graphene oxide/graphene mixed slurry are improved. Through strong shearing, impact, cavity and turbulent vortex effects generated by homogenizing treatment, graphene oxide sheets and graphene sheets in graphene oxide slurry can be effectively peeled off, and the dispersion uniformity of graphene in graphene oxide/graphene mixed slurry is further improved. The addition of graphene and the functionalized carbon nanotubes can improve the solid content of the slurry containing graphene oxide, graphene and the functionalized carbon nanotubes, and further improve the subsequent coating efficiency and the thickness of the single-layer film; the graphene oxide surface contains abundant hydroxyl, epoxy, carboxyl and other functional groups, and in the application, the graphene oxide can be used as a film forming substance and a dispersing adhesive, so that the sufficient expansion of graphene sheets is facilitated, the formation of transverse intermolecular chemical bonds between the sheets is facilitated, the graphene and the functionalized carbon nano tube form a five-membered ring structure and/or a six-membered ring structure after stirring treatment, and the binding force between the graphene sheets can be enhanced. The functionalized carbon nano tube is added in the second step without homogenizing treatment, so that the purpose is to keep the good length-diameter ratio of the functionalized carbon nano tube and better enhance the acting force between graphene sheets. In some embodiments, the mass of graphene oxide in the partial graphene oxide slurry is 0.01% -0.1% of the mass of graphene, specifically, the mass of graphene oxide in the partial graphene oxide slurry is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% and so on of the mass of graphene, but other values within the above range are of course possible, and are not limited thereto.

In some embodiments, the graphene is obtained by at least one of mechanically exfoliating graphene, liquid phase exfoliating graphene, and reducing graphene oxide.

In some embodiments, the carbon content of the graphene is 70% or more, and the carbon content of the graphene may specifically be 70%, 73%, 75%, 80%, 83%, 85%, or the like, but may be other values within the above range, which is not limited thereto. It can be understood that the graphene is graphene with low oxidation degree, so that the oxygen content in the slurry can be reduced, and the problem of high expansion of the film caused by the large volatilization of oxygen-containing functional groups in the high-temperature heat treatment process can be effectively reduced.

In some embodiments, the mixing of the graphene oxide dispersion with graphene is performed under stirring conditions. The stirring speed under the stirring conditions is 3000rpm to 5000rpm, and the stirring speed may be, specifically, 3000rpm, 3300rpm, 3500rpm, 3700rpm, 4000rpm, 4200rpm, 4500rpm, 4800rpm, 5000rpm, or the like, but may be other values within the above range, and is not limited thereto.

In some embodiments, the stirring time under the stirring condition is 15min to 60min, and the stirring time may specifically be 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, and the like, but may also be other values within the above range, which is not limited herein.

In some embodiments, the pressure of the homogenizing treatment is 500bar to 1250bar, and the pressure of the homogenizing treatment may specifically be 500bar, 600bar, 700bar, 800bar, 900bar, 1000bar, 1100bar, 1200bar, 1250bar, etc., but may also be other values within the above range, which is not limited herein.

In some embodiments, the temperature of the homogenization treatment is 10 to 25 ℃, specifically 10 ℃, 12 ℃, 15 ℃, 17 ℃, 20 ℃, 22 ℃, 24 ℃, 25 ℃ and the like, but of course, other values within the above range are also possible, and the temperature of the homogenization treatment is not limited thereto.

In some embodiments, the number of times of the homogenization treatment is 2 to 4 times, and the number of times of the homogenization treatment may be specifically 2 times, 3 times, 4 times, or the like, but may be other values within the above range, and is not limited thereto.

In some embodiments, the graphene oxide slurry is obtained by dispersing graphite oxide or purchasing graphene oxide slurry sold in the market, and when the graphene oxide slurry is obtained by adopting a graphite oxide dispersing treatment, a graphite oxide filter cake with carbon content of less than 70% is crushed, and then the crushed graphite oxide filter cake is stirred and dispersed in deionized water.

The preparation process of the functionalized carbon nano tube is the prior art, and the commercialized product can be prepared or directly purchased.

In some embodiments, the mass ratio of graphene oxide, graphene, and functionalized carbon nanotubes in the graphene oxide slurry is 1: (0.1-1): (0.01-0.1), the mass ratio of graphene oxide, graphene and functionalized carbon nanotubes in the graphene oxide slurry can be specifically 1:0.1:0.5, 1:0.2:0.01, 1:0.5:0.03, 1:0.7:0.1, 1:0.8:0.7, 1:1:0.9 and 1:0.8:1, etc., may be any other value within the above range, and is not limited thereto. Controlling the proportion is beneficial to improving the dispersion uniformity of the functionalized carbon nano tube, the graphene oxide and the graphene in the slurry, the dispersion uniformity of the functionalized carbon nano tube is beneficial to improving the interlayer binding force between graphene sheets, and the expansion delamination of the film is inhibited. The addition amount of the functionalized carbon nano tube in the graphene oxide slurry is too small, so that the prepared film material has poor binding force and can not effectively inhibit the expansion and delamination of the film; the addition amount of the functionalized carbon nano tube in the graphene oxide slurry is too much, so that the dispersion uniformity of the slurry is poor, and the thermal conductivity performance of the prepared film material is lower.

In some embodiments, the functionalized carbon nanotubes comprise at least one of single wall, double wall, and multi wall.

In some embodiments, the tube length of the functionalized carbon nanotubes is 5 μm to 50 μm, and the tube length of the functionalized carbon nanotubes may specifically be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc., but may be other values within the above range, and is not limited thereto.

In some embodiments, the tube diameter of the functionalized carbon nanotubes is 4nm to 100nm, and the tube diameter of the functionalized carbon nanotubes may specifically be 4nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc., but may also be other values within the above range, and is not limited thereto.

In some embodiments, the morphology of the functionalized carbon nanotubes includes at least one of a wrap-around type and an array type.

In some embodiments, the second dispersion treatment comprises a stirring treatment and a grinding treatment.

In some embodiments, the apparatus for the agitation process comprises a double planetary agitator.

In some embodiments, the apparatus for the grinding process comprises at least one of a sand mill and a ball mill.

In some embodiments, the stirring rate of the stirring treatment is 3000rpm to 5000rpm, specifically 3000rpm, 3500rpm, 4000rpm, 4500rpm, 5000rpm, etc., but other values within the above range are also possible, and the stirring rate is not limited thereto.

In some embodiments, the stirring time of the stirring treatment is 15min to 60min, and the stirring time may be, for example, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, or the like, but may be other values within the above range, which is not limited thereto.

In some embodiments, the polishing rate is 3000rpm to 5000rpm, and the polishing rate may be, for example, 3000rpm, 3500rpm, 4000rpm, 4500rpm, 5000rpm, or the like, but may be other values within the above range, and is not limited thereto.

In some embodiments, the polishing time is 15min to 60min, and the polishing time may be, for example, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, or the like, but may be other values within the above range, which is not limited thereto.

In some embodiments, the number of polishing treatments is 2 to 4, and the number of polishing treatments may be, for example, 2, 3, 4, etc., but may be other values within the above range, and is not limited thereto. The purpose of multiple grinding is to fully mix and disperse the functionalized carbon nano tube and the graphene uniformly.

In some embodiments, the pH of the graphene oxide/graphene mixed slurry is from 6 to 8. Specifically, since the pH of the graphene oxide is low and acidic, the pH of the graphene oxide/graphene mixed slurry is adjusted to be neutral in a manner of dropwise adding alkali liquor after the second dispersion treatment in order not to influence the subsequent operation.

And 200, performing heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups to obtain the composite film.

In some embodiments, the heat treatment includes pretreatment, carbonization and graphitization, that is, the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is sequentially subjected to pretreatment, carbonization and graphitization, and it is understood that the film material after the heat treatment is a single-layer film material, which includes graphene sheets stacked, and the graphene sheets are connected by chemical bonds C-C through the functionalized carbon nanotubes.

In some embodiments, the pretreatment temperature is 100 to 400 ℃, and the pretreatment temperature may be, for example, 100 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, or the like, but may be other values within the above range, and is not limited thereto.

In some embodiments, the temperature rising rate of the pretreatment is 5 to 10 ℃ per minute, and the temperature rising rate may be, for example, 5, 6, 7, 8, 9, and 10 ℃ per minute, but may be other values within the above range, and is not limited thereto.

In some embodiments, the pretreatment time is 5h to 10h, and the pretreatment time may be, for example, 5h, 6h, 7h, 8h, 9h, 10h, etc., but may be other values within the above range, which is not limited thereto.

In some embodiments, carbonization and graphitization are performed in the same equipment, and carbon and graphitization treatment is performed on the graphene oxide/graphene/functionalized carbon nanotube composite film continuously, so that the heat treatment time can be shortened, the energy consumption can be reduced, the occupied space of the equipment can be reduced, and the operation cost can be reduced.

In some embodiments, the equipment employed for carbonization and graphitization comprises an integrated high temperature furnace.

In some embodiments, the specific steps of the carbonization and graphitization process are: firstly, heating to 1000-1500 ℃ under continuous vacuum condition for carbonization treatment, and then rapidly heating to 2600-3100 ℃ in protective atmosphere for graphitization heat treatment.

In some embodiments, the temperature of the carbonization treatment may be, for example, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃, 1500 ℃, or the like, but may be other values within the above range, without limitation.

In some embodiments, the heating rate of the carbonization treatment is 5 to 30 ℃ per minute, and the heating rate may be, for example, 5, 10, 15, 20, 25, 30, etc., but may be other values within the above range, without limitation.

In some embodiments, the carbonization time is 5h to 24h, and the specific carbonization time may be 5h, 8h, 10h, 12h, 16h, 20h and 24h, but may be other values within the above range, which is not limited herein.

In some embodiments, the temperature of the graphitization treatment is 2600 ℃ to 3100 ℃, and the graphitization treatment temperature may be 2600 ℃, 2700 ℃, 2800 ℃, 2900 ℃, 3000 ℃, 3100 ℃ or the like, but may be other values within the above range, and is not limited thereto.

In some embodiments, the time of the graphitization treatment is 10h to 72h, and the time of the graphitization treatment may specifically be 10h, 15h, 20h, 24h, 30h, 36h, 40h, 48h, 52h, 60h, 66h, 70h, 72h, etc., but may also be other values within the above range, and is not limited thereto.

In some embodiments, the graphitizing treatment is performed in a protective atmosphere comprising at least one of argon and nitrogen.

In some embodiments, the temperature rise rate of the graphitization heat treatment is 10 to 30 ℃ per minute, and the temperature rise rate may be, for example, 10, 15, 20, 25, 30, etc., although other values within the above range are also possible, and the present invention is not limited thereto.

In this step, the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is subjected to pretreatment after the graphite paper lamination is placed in the middle of the graphite jig, and oxygen-containing functional groups in the slurry are removed, and it can be understood that the oxygen-containing functional groups in the graphene oxide and graphene can be reduced by pretreatment, so that the problem of high expansion in the subsequent high-temperature heat treatment process (carbonization and graphitization) is avoided, and the cavitation and delamination caused by volatilization of the graphene oxide functional groups at high temperature are inhibited.

In some embodiments, the resulting one or more monolayer film materials may be subjected to a compaction process after the heat treatment to produce a composite film.

In some embodiments, the compacted substrate is a polymeric substrate comprising at least one of polyethylene, polyethylene terephthalate, polypropylene, and oriented polypropylene.

In some embodiments, the apparatus for compacting comprises a twin roll calender.

In some embodiments, the compacting pressure is 2MPa to 50MPa, and the pressure may be, for example, 2MPa, 5MPa, 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, or the like, but may be other values within the above range, and is not limited thereto.

According to the preparation method, the oxygen content of the slurry can be reduced by compounding graphene oxide, graphene and the functionalized carbon nano tube, so that the expansion of the heat-conducting composite film is effectively inhibited, the product yield of the graphene heat-conducting composite film is improved, and meanwhile, the high-solid-content composite slurry is prepared by compounding the graphene oxide, the graphene and the functionalized carbon nano tube and adjusting the production process of the whole composite film, so that the improvement of the coating efficiency and the preparation of a thick film are realized; in addition, the addition of the functionalized carbon nanotubes plays a role in connecting between graphene sheets, and the interlayer binding force between the graphene sheets is effectively improved through a heat treatment step, so that a foundation is laid for the production of the follow-up graphene heat-conducting film coiled material.

The embodiment of the application also provides electronic equipment, which comprises the prepared composite film.

The following examples are provided to further illustrate embodiments of the invention. The embodiments of the present invention are not limited to the following specific embodiments. The modification can be appropriately performed within the scope of the main claim.

Example 1

(1) Weighing 300g of graphite oxide filter cake blocks with the solid content of 70% in a double planetary mixer cylinder, grinding, diluting and dispersing in 2000ml of deionized water, and uniformly stirring at the stirring speed of 30rmp/min to obtain graphene oxide slurry; taking 25g of graphene oxide slurry, adding 150g of water to obtain a graphene oxide dispersion liquid with the concentration of 1%, adding 120g of graphene (with the carbon content of 98%) into the graphene oxide dispersion liquid, uniformly stirring at the stirring speed of 2000rmp/min, adding the rest of graphene oxide slurry, and homogenizing under high pressure to obtain graphene oxide/graphene mixed slurry; then adding 12g of aminated carbon nano tube and 50ml of ammonia water into the graphene oxide/graphene slurry to obtain pH value of 7, maintaining 3000rmp/min and stirring for 1h, and grinding for 30min at 3000rmp/min to obtain the graphene oxide/graphene/aminated carbon nano tube mixed slurry with solid content of 11.4% and viscosity of 40000 cps.

(2) Coating the graphene oxide/graphene/aminated carbon nanotube composite slurry on a 300-mesh polypropylene mesh filter cloth with the thickness of 0.4mm at the coating height of 3mm and the coating speed of 0.4m/min, wherein the thickness of a wet film is 3000mm, and baking at the baking temperature of 90 ℃ for 6 hours to obtain a graphene oxide/graphene/aminated carbon nanotube raw film.

(3) Pretreating the graphene oxide/graphene/aminated carbon nanotube raw film at 100 ℃, and baking for 6 hours at a heating rate of 10 ℃/min to obtain a graphene oxide/graphene/aminated carbon nanotube pretreatment film;

(4) And (3) placing the graphene oxide/graphene/aminated carbon nanotube pretreatment film into an integrated high-temperature furnace for heat treatment, performing vacuum carbonization and reduction heat treatment at 1500 ℃, filling high-purity argon into a furnace body at a heating rate of 30 ℃/min, rapidly heating to 3100 ℃ for graphitization heat treatment to obtain a single-layer film material, and baking for 72h at a heating rate of 20 ℃/min.

(5) And (3) compacting the heat-treated single-layer film material on the PET substrate by adopting a twin-roll calender, wherein the compacting pressure is 50MPa, and thus the composite film is obtained.

In the above embodiment, in the step (1), the mass ratio of graphene oxide, graphene and aminated carbon nanotubes added is 1:1:0.05.

As shown in fig. 3, an AFM image of the graphene oxide/graphene/aminated carbon nanotube composite slurry according to example 1 of the present application is shown in fig. 3: the graphene oxide/graphene/aminated carbon nanotube composite slurry prepared in the embodiment 1 of the application is uniform in dispersion of the aminated carbon nanotubes and graphene, and is not agglomerated.

As shown in fig. 4, an SEM image of the composite film of example 1 of the present application is shown. As shown in fig. 4, the carbon nanotubes are uniformly intercalated between graphene sheets.

As shown in fig. 5, the graph of the interlayer peeling force data of the graphene/carbon nanotube composite film in example 1 of the present application is shown in fig. 5: the average peeling force (i.e., interlayer bonding force) of the composite film of example 1 was 110gf.

Example 2

Unlike example 1, the added mass ratio of graphene oxide, graphene, and aminated carbon nanotubes in step (1) was 1:0.02:0.005.

in the composite film prepared in this embodiment, graphene is stacked, carbon nanotubes are connected between graphene sheets, and the values of thickness, tensile strength and interlayer binding force are shown in table 1.

Example 3

Unlike example 1, the added mass ratio of graphene oxide, graphene, and aminated carbon nanotubes in step (1) was 1:1:0.1.

In the composite film prepared in this embodiment, graphene layers are stacked, and the sheets of graphene are connected through nanotubes, and the values of thickness, tensile strength and interlayer binding force are shown in table 1.

Example 4

Unlike example 1, the added mass ratio of graphene oxide, graphene, and aminated carbon nanotubes in step (1) was 1:5:0.2.

in the composite film prepared in this embodiment, graphene layers are stacked, and the numerical values of thickness, tensile strength and interlayer binding force of graphene layers are shown in table 1 through connection.

Example 5

Unlike example 1, the "aminated carbon nanotubes" in step (1) were replaced with "hydroxylated carbon nanotubes".

Example 6

Unlike example 1, the "aminated carbon nanotubes" in step (1) were replaced with "epoxidized carbon nanotubes".

Example 7

Unlike example 1, the step of the step (3) pretreatment was not performed.

Example 8

Unlike example 1, graphene oxide slurry and graphene were mixed in step (1) and homogenized at high pressure to obtain graphene oxide/graphene mixed slurry.

Example 9

Unlike example 1, the carbonization temperature in step (4) was 950 ℃.

Example 10

Unlike example 1, the carbonization temperature in step (4) was 1000 ℃.

Example 11

Unlike example 1, the carbonization temperature in step (4) was 1300 ℃.

Example 12

Unlike example 1, the graphitization heat treatment temperature in step (4) was 2500 ℃.

Example 13

Unlike example 1, the graphitization heat treatment temperature in step (4) was 2600 ℃.

Example 14

Unlike example 1, the graphitization heat treatment temperature in step (4) was 2800 ℃.

Example 15

Unlike example 1, the graphitization heat treatment temperature in step (4) was 3200 ℃.

Example 16

Unlike example 1, the carbon content of graphene was 90%.

Example 17

Unlike example 1, the carbon content of graphene was 80%.

Example 18

Unlike example 1, the carbon content of graphene was 63%.

Comparative example 1

The preparation method of the pure graphene film provided by the comparative example comprises the following steps:

(1) Weighing 100g of graphite oxide filter cake blocks with the solid content of 70% in a double-planetary stirrer cylinder, grinding, diluting and dispersing in 2000ml of deionized water, uniformly stirring at a stirring speed of 30rmp/min, and then homogenizing under high pressure to obtain graphene oxide slurry; 19.31ml of ammonia water is added to obtain pH 7, stirring is maintained at 30rmp/min for 1h, and then stirring and dispersing are carried out at a stirring speed of 120rmp/min and a dispersing speed of 5000rmp/min for 2h, so as to obtain graphene oxide slurry with solid content of 5% and viscosity of 50000 cps.

(2) And (3) coating the graphene oxide slurry on a 300-mesh polypropylene mesh filter cloth with the thickness of 0.4mm at a coating height of 3mm and a coating speed of 0.4m/min, wherein the thickness of a wet film is 2400mm, and baking at 90 ℃ for 8 hours to obtain a graphene oxide raw film.

(3) Pretreating the raw film at 400 ℃, and baking for 6 hours at a heating rate of 10 ℃/min to obtain a graphene oxide pretreated film;

(4) And (3) placing the obtained pretreatment film into an integrated high-temperature furnace for heat treatment, performing vacuum carbonization and reduction heat treatment at 1500 ℃, wherein the heating rate is 30 ℃/min, then filling high-purity argon into a furnace body, rapidly heating to 3100 ℃ for graphitization heat treatment, and baking for 72h at the heating rate of 20 ℃/min.

(5) And (3) compacting the graphitized graphene film on a PET substrate by adopting a twin-roll calender under the pressure of 50MPa to obtain the graphene film.

In the composite film prepared in this comparative example, the values of thickness, tensile strength and interlayer bonding force are shown in Table 1.

Performance testing

1. And (3) testing a binding force method: and (3) tearing off release paper to fix on a steel plate while peeling at 180 degrees with reference to a GB/T2792 film raw material double-sided tesa adhesive tape, and taking an average value of a stable section.

2. The tensile strength test method is based on GB/T1040.1-2018, and experiments are carried out by controlling an electronic universal tester through a microcomputer.

3. The solid content of the slurry is tested by adopting a weighing method, 6-10 g of the upper, middle and lower layers of the defoamed material are respectively sampled, the sampling number of each layer is 2, the obtained samples are placed in an oven for baking at 110 ℃ for 4-6 h, the weight of each sample is measured after baking, and the solid content of the material is calculated through the mass difference before and after baking.

4. The viscosity of the slurry was measured using a viscometer. The test data are shown in Table 1.

TABLE 1 Performance test of composite films prepared in examples and comparative examples

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As can be seen from the data in table 1: according to the preparation method, the graphene oxide, the graphene and the carbon nano tube are compounded, the high-temperature heat treatment process is optimized, the problem of high expansion caused by the fact that oxygen-containing functional groups volatilize in a large amount in the high-temperature heat treatment process is effectively solved, the preparation of a low-expansion thick film product is achieved, the prepared composite film is high in solid content of slurry, strong in binding force between the film layers of the composite film, and thick in single-layer film thickness, the coating process can be improved, and batch production of the composite film can be achieved.

As shown in fig. 6, which is a graph comparing mechanical properties of the composite film prepared in example 1 and comparative example 1, comparative example 1 directly adopts graphite oxide as a raw material to prepare a composite heat-conducting film, and its tensile strength is significantly smaller than that of the film material prepared in example 1, specifically, the tensile strength of the composite film of example 1 is 100MPa, which is approximately 5 times that of the pure graphene film of comparative example 1, which indicates that the composite film of the present application has strong bonding force and can be used as a material of graphene coiled film.

In examples 1 to 4, the ratio of the added mass of graphene to functionalized carbon nanotubes was too small (example 2), resulting in an inability to effectively suppress expansion and a weak interlayer bonding force of the film; the addition mass ratio of graphene to functionalized carbon nanotubes is too large (example 4), which results in increased dispersion difficulty and poor film uniformity, resulting in ineffective enhancement of the bonding force between the film layers.

In example 7, the composite membrane prepared without the pretreatment of step (3) swells too much, resulting in easy breakage and breakage of the composite membrane.

In example 8, the graphene oxide slurry was directly mixed with graphene without dispersion, and the prepared composite film had poor dispersion uniformity and low film performance.

In examples 1 and 9 to 11, the carbonization temperature was too low (example 9), and the prepared composite film had disadvantages of incomplete removal of functional groups and low thermal conductivity of the composite film.

In examples 1 and 12 to 15, the graphitization temperature was too low (example 12), and the prepared composite film had the disadvantages of low graphitization degree and poor thermal conductivity. The graphitization temperature is too high (example 15), and the prepared composite film has the defects of too high rigidity and high energy consumption in the preparation process.

In examples 1 and 16 to 18, the carbon content of graphene was too low (example 18), and the prepared composite film had a problem of high expansion and easy breakage.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

While the preferred embodiment has been described, it is not intended to limit the scope of the claims, and any person skilled in the art can make several possible variations and modifications without departing from the spirit of the invention, so the scope of the invention shall be defined by the claims.

Claims

1. The composite film is characterized by comprising graphene which is arranged in a laminated mode, carbon nanotubes are connected between graphene sheets, the graphene and carbon elements of the carbon nanotubes form at least one of a five-membered ring structure and a six-membered ring structure, and interlayer bonding force between the graphene sheets is 80 gf-150 gf.

2. The composite membrane of claim 1, wherein the composite membrane comprises at least one of the following features (1) - (5):

(1) The mass ratio of the graphene to the carbon nano tube is 1: (0.01-0.1);

(2) The carbon nanotubes include at least one of single wall, double wall, and multi wall;

(3) The length of the carbon nano tube is 5-50 mu m;

(4) The pipe diameter of the carbon nano-tube is 4 nm-100 nm;

(5) The morphology of the carbon nanotubes includes at least one of a wrap-around type and an array type.

3. The composite membrane of claim 1, wherein the composite membrane comprises at least one of the following features (1) - (6):

(1) The composite film comprises at least two single-layer film materials which are arranged in a laminated mode, wherein the single-layer film materials comprise graphene with carbon nano tubes connected between layers;

(2) The composite film comprises at least two single-layer film materials which are arranged in a laminated way, wherein the single-layer film materials comprise graphene with carbon nano tubes connected between layers, and the thickness of the single-layer film materials is 25-35 mu m;

(3) The thickness of the composite film is 50-300 mu m;

(4) The heat conductivity coefficient of the composite film is 800W/mK-1500/mK;

(5) The tensile strength of the composite film is 60-120 MPa;

(6) The composite film has a surface-line-surface three-dimensional structure.

4. A method for preparing a composite membrane, comprising the steps of:

coating the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to obtain a graphene oxide/graphene/functionalized carbon nanotube composite film, wherein the functionalized carbon nanotubes comprise at least one of hydroxylated carbon nanotubes, aminated carbon nanotubes and epoxidized carbon nanotubes;

and carrying out heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups to obtain the composite film, wherein the heat treatment comprises graphitization treatment, and the temperature of the graphitization treatment is 2600-3100 ℃.

5. The preparation method according to claim 4, wherein the preparation process of the slurry containing graphene oxide, graphene and functionalized carbon nanotubes comprises the following steps: obtaining graphene oxide slurry, and performing first dispersion treatment on the graphene oxide slurry and the graphene to obtain slurry containing graphene oxide and graphene; and carrying out second dispersion treatment on the slurry containing the graphene oxide and the graphene and the functionalized carbon nano tube to obtain the slurry containing the graphene oxide, the graphene and the functionalized carbon nano tube.

6. The preparation method of claim 5, wherein the first dispersion treatment is performed on the graphene oxide slurry and the graphene to obtain a slurry containing graphene oxide and graphene, and specifically comprises the following steps: preparing a part of graphene oxide slurry to form graphene oxide dispersion liquid, mixing the graphene oxide dispersion liquid with the graphene, adding the rest of the graphene oxide slurry, and carrying out homogenization treatment to obtain the slurry containing the graphene oxide and the graphene, wherein the method comprises at least one of the following characteristics (1) - (7):

(1) The mass of graphene oxide in the partial graphene oxide slurry is 0.01% -0.1% of the mass of graphene;

(2) The carbon content of the graphene is more than or equal to 70%;

(3) The graphene oxide dispersion liquid and graphene are mixed under stirring conditions;

(4) The pressure of the homogenizing treatment is 500 bar-1250 bar;

(5) The temperature of the homogenizing treatment is 10-25 ℃;

(6) The times of the homogenizing treatment are 2 to 4 times;

(7) The pH of the slurry containing graphene oxide and graphene is 6-8.

7. The method according to claim 5, characterized in that the method comprises at least one of the following features (1) to (6):

(1) The mass ratio of graphene oxide to the functionalized carbon nanotubes in the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is 1: (0.1-1): (0.01-0.1);

(3) The functionalized carbon nanotubes comprise at least one of single wall, double wall, and multi wall;

(4) The tube length of the functionalized carbon nano tube is 5-50 mu m;

(5) The pipe diameter of the functionalized carbon nano-tube is 4 nm-100 nm;

(6) The second dispersion treatment comprises the steps of stirring treatment and grinding treatment on the slurry containing graphene oxide and graphene and the functionalized carbon nano tube in sequence.

8. The method according to claim 4, further comprising a step of subjecting the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to a defoaming treatment before subjecting the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to a coating treatment, the method comprising at least one of the following features (1) to (5):

(1) The thickness of the wet film of the graphene oxide/graphene/functionalized carbon nano tube composite film obtained by the coating treatment is 2400-3500 mm;

(2) The temperature of the defoaming treatment is 15-20 ℃;

(3) The time of the defoaming treatment is 10-30 min;

(4) The solid content of the material after the defoaming treatment is 5% -20%;

(5) The viscosity of the material after the defoaming treatment is 30000 cps-70000 cps.

9. The method according to claim 4, wherein the method comprises at least one of the following features (1) to (14):

(1) The heat treatment also comprises pretreatment, wherein the temperature of the pretreatment is 100-400 ℃;

(2) The heat treatment further comprises pretreatment, wherein the heating rate of the pretreatment is 5 ℃/min-10 ℃/min;

(3) The heat treatment further comprises pretreatment, wherein the pretreatment time is 5-10 h;

(4) The heat treatment further comprises carbonization treatment, wherein the carbonization treatment is carried out under vacuum condition;

(5) The heat treatment also comprises carbonization treatment, wherein the temperature of the carbonization treatment is 1000-1500 ℃;

(6) The heat treatment also comprises carbonization treatment, wherein the heating rate of the carbonization treatment is 5 ℃/min-30 ℃/min;

(7) The heat treatment further comprises carbonization treatment, wherein the time of the carbonization treatment is 5-24 hours;

(8) The heating rate of the graphitization treatment is 10-30 ℃/min;

(9) The graphitization treatment is performed in a protective atmosphere comprising at least one of argon and nitrogen;

(10) The graphitization treatment time is 10-72 hours;

(11) The carbonization treatment and the graphitization treatment are performed in the same equipment;

(12) The step of compacting the graphene oxide/graphene/functionalized carbon nanotube composite film after the graphene oxide/graphene/functionalized carbon nanotube composite film is subjected to heat treatment to remove oxygen-containing functional groups;

(13) The method comprises the steps of carrying out heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups, and then carrying out compaction treatment, wherein the compacted substrate comprises at least one of polyethylene, polyethylene terephthalate, polypropylene and oriented polypropylene;

(14) The method comprises the steps of carrying out heat treatment on the graphene oxide/graphene/functionalized carbon nano tube composite film to remove oxygen-containing functional groups, and then carrying out compaction treatment, wherein the pressure of the compaction treatment is 2-50 MPa.

10. An electronic device comprising the composite film according to any one of claims 1 to 3 or the composite film produced by the production method according to any one of claims 4 to 9.