CN114394585A

CN114394585A - Composite film, preparation method thereof and electronic equipment

Info

Publication number: CN114394585A
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: 2022-04-26
Anticipated expiration: 2041-12-31
Also published as: CN114394585B

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 stacked mode, a carbon nano tube is connected between graphene sheet layers, and the interlayer bonding force between the graphene sheet layers is 80 gf-150 gf. The composite material uses the carbon nano tube as a support body to connect the graphene, on one hand, the carbon nano tube is present between the graphene to enhance the uniformity of graphene dispersion, on the other hand, the carbon nano tube is connected with the graphene through the chemical bond of the carbon nano tube, the mutual binding force of the graphene and the carbon nano tube is enhanced, the interlayer binding force of the graphene composite film layer is improved, and a guarantee is provided for the feasibility of continuous preparation of the graphene coiled 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 of the composite film and electronic equipment.

Background

With the rapid development of the 5G electronic industry, electronic products are becoming more compact, multifunctional and high-performance, and the amount of heat generated per unit area is also rising rapidly, so that heat dissipation becomes a critical issue, and the performance and reliability of electronic products, batteries and other high-power systems are restricted. Graphene, one of the new materials that has attracted attention in the 21 st century, exhibits excellent electrical conductivity, thermal conductivity, and mechanical properties due to its unique structure, and thus, a thermally conductive and heat dissipating material developed based on graphene will be introduced as a mainstream heat dissipating material in the future.

The existing graphene heat dissipation material is mainly prepared by oriented self-assembly of graphene oxide, however, in the process of oriented self-assembly of graphene oxide, because the oxygen content of graphite oxide is high, high oxygen content functional groups are removed by heat treatment to cause more cavities in the graphene film, the graphene film has high expansion degree, and the graphene film is very easy to break, which seriously affects the product yield. In addition, the graphite oxide with high oxygen content causes the graphite oxide slurry obtained after dispersion and homogenization to have low solid content, low coating efficiency and low single-layer film thickness, and is not beneficial to batch production.

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

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

Disclosure of Invention

The composite film has low swelling degree and high interlayer bonding force, is not easy to delaminate, and can be prepared in batch.

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

In one possible embodiment in combination with the first aspect, the graphene forms at least one of a five-membered ring structure and a six-membered ring structure with a carbon element of the carbon nanotube.

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

In one possible embodiment in combination with the first aspect, the carbon nanotubes include at least one of a single wall, a double wall, and a multi wall.

In one possible embodiment in combination with the first aspect, the carbon nanotubes have a tube length of 5 μm to 50 μm.

In one possible embodiment in combination with the first aspect, the carbon nanotubes have a tube diameter of 4nm to 100 nm.

In one possible embodiment in combination with the first aspect, the carbon nanotube morphology includes at least one of a twisted type and an arrayed type.

With reference to the first aspect, in one possible embodiment, the composite film includes at least two single-layer film materials stacked together, and the single-layer film materials include graphene with carbon nanotubes connected between layers.

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

In a possible embodiment in combination with the first aspect, the composite film has a thickness of 50 μm to 300 μm.

In one possible embodiment in combination with the first aspect, the composite film has a thermal conductivity of 800W/mK to 1500/mK.

In one possible embodiment in combination with the first aspect, the composite film has a tensile strength of 60MPa to 120 MPa.

In one possible embodiment in combination with the first aspect, the composite membrane is a plane-line-plane three-dimensional structure.

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

coating slurry containing graphene oxide, graphene and functionalized carbon nanotubes to obtain a graphene oxide/functionalized graphene/carbon nanotube composite membrane, 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 nanotube composite membrane to remove oxygen-containing functional groups to obtain the composite membrane.

With reference to the second aspect, the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is prepared by the following steps: obtaining graphene oxide slurry, and performing first dispersion treatment on the graphene oxide slurry and the graphene to obtain slurry containing the graphene oxide and the 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 embodiment, the obtaining a slurry containing graphene oxide and graphene by performing the first dispersion treatment on the graphene oxide slurry and graphene specifically includes: and preparing part of the graphene oxide slurry to form a graphene oxide dispersion liquid, mixing the graphene oxide dispersion liquid with the graphene, and then adding the rest graphene oxide slurry for homogenization treatment to obtain the slurry containing the graphene oxide and the graphene.

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

In combination with the second aspect, in one possible embodiment, the carbon content of the graphene is 70% or more.

In combination with the second aspect, in one possible embodiment, the mixing of the graphene oxide dispersion and the graphene is performed under stirring conditions.

In a possible embodiment, in combination with the second aspect, the pressure of the homogenization treatment is between 500bar and 1250 bar.

In a possible embodiment, in combination with the second aspect, the temperature of the homogenization treatment is 10 ℃ to 25 ℃.

In a possible embodiment in combination with the second aspect, the number of homogenization treatments is 2 to 4.

In combination with the second aspect, in one possible embodiment, the slurry containing graphene oxide and graphene has a pH of 6 to 8.

In combination with the second aspect, in one possible embodiment, the mass ratio of the graphene oxide, the graphene and the functionalized carbon nanotubes in the slurry containing the graphene oxide, the graphene and the functionalized carbon nanotubes is 1: (0.1-1): (0.01-0.1).

In combination with the second aspect, in one possible embodiment, the functionalized carbon nanotubes include at least one of single-walled, double-walled, and multi-walled.

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

In a possible embodiment, in combination with the second aspect, the functionalized carbon nanotubes have a tube diameter of 4nm to 100 nm.

In combination with the second aspect, in a possible embodiment, the second dispersion process includes the steps of sequentially performing a stirring process and a grinding process on the slurry containing graphene oxide and graphene and the functionalized carbon nanotubes.

In combination with the second aspect, in a possible embodiment, before the coating process, a step of subjecting the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to a defoaming process is further included.

In combination with 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 2400mm to 3500 mm.

In a possible embodiment in combination with the second aspect, the temperature of the defoaming treatment is 15 ℃ to 20 ℃.

In a possible embodiment, in combination with the second aspect, the time of the defoaming treatment is 10min to 30 min.

With reference to the second aspect, in a possible embodiment, the solid content of the defoamed material is 5% to 20%.

In a possible embodiment in combination with the second aspect, the viscosity of the defoamed material is 30000cps to 70000 cps.

In combination with the second aspect, in one possible embodiment, the heat treatment includes a pretreatment, a carbonization treatment, and a graphitization treatment.

In a possible embodiment, in combination with the second aspect, the temperature of the pre-treatment is between 100 ℃ and 400 ℃.

In a possible embodiment in combination with the second aspect, the temperature increase rate of the pre-treatment is 5 ℃/min to 10 ℃/min.

In a possible embodiment, in combination with the second aspect, the time of the pretreatment is 5 to 10 hours.

In combination with the second aspect, in one possible embodiment, the carbonization treatment is performed under vacuum conditions.

In combination with the second aspect, in one possible embodiment, the temperature of the carbonization treatment is 1000 ℃ to 1500 ℃.

In a possible embodiment in combination with the second aspect, the temperature increase rate of the carbonization treatment is 5 ℃/min to 30 ℃/min.

In a possible embodiment, in combination with the second aspect, the carbonization treatment is carried out for a time of 5 to 24 hours.

In a possible embodiment, in combination with the second aspect, the graphitization treatment temperature is 2600 ℃ to 3100 ℃.

In a possible embodiment in combination with the second aspect, the rate of temperature increase of the graphitization treatment is 10 deg.C/min to 30 deg.C/min.

In combination with the second aspect, in one possible embodiment, the graphitization treatment is performed in a protective atmosphere including at least one of argon and nitrogen.

In a possible embodiment, in combination with the second aspect, the graphitization treatment time is 10 to 72 hours.

In a possible embodiment, in combination with the second aspect, the carbonization treatment and the graphitization treatment are performed in the same apparatus.

In combination with the second aspect, in a possible embodiment, after the graphene oxide/graphene/functionalized carbon nanotube composite film is subjected to a heat treatment to remove oxygen-containing functional groups, a step of performing a compaction treatment is further included.

In combination with the second aspect, in one possible embodiment, the densified substrate includes at least one of polyethylene, polyethylene terephthalate, polypropylene, and oriented polypropylene.

In a possible embodiment, in combination with the second aspect, the pressure of the compaction process is between 2MPa and 50 MPa.

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

The technical scheme of the application has at least the following beneficial effects: the utility model provides a composite membrane, regard carbon nanotube as supporter connection graphite alkene, on the one hand, carbon nanotube has strengthened the homogeneity that graphite alkene disperses between the lamella that exists in graphite alkene, on the other hand, carbon nanotube connects graphite alkene through the chemical bond of self, the mutual cohesion of graphite alkene and carbon nanotube has been strengthened, improve the interlayer cohesion between the graphene lamella and reach 80gf ~ 150gf, the inflation is low, can effectively restrain the layering of graphite alkene membrane, the composite membrane is not fragile, improve the product yield of composite membrane, provide the guarantee for the continuous preparation feasibility of graphite alkene coiled material membrane.

The composite film adopts the slurry containing the graphene oxide, the graphene and the functionalized carbon nanotube as a preparation raw material, and on one hand, the composite film can inhibit cavities and layers caused by volatilization of oxygen-containing functional groups in the graphene oxide at high temperature, so that the expansion problem of the composite film can be effectively weakened, and the preparation of the composite film with low expansion degree is realized. Moreover, the solid content of the slurry in the composite film can be effectively improved by adding the graphene and the functionalized carbon nano tube, 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 the graphene oxide, the graphene and the functionalized carbon nanotubes is coated and thermally treated, the carbon nanotubes in the slurry are loaded on graphene sheets through the action of functional groups, the graphene oxide and groups on the surfaces and edges 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 increased to 80-150 gf through a thermal 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 needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.

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

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

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

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

fig. 5 is a data diagram of interlayer peeling force of the graphene/aminated carbon nanotube composite film in example 1 obtained by referring to a test method of the peeling strength of the adhesive tape of GB2792-2014 in the present application;

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

Detailed Description

For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.

It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present 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 the examples of the present invention 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 type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

The embodiment of the application discloses a composite film, which comprises graphene which is arranged in a stacked mode, wherein carbon nanotubes are connected between sheet layers of the graphene, and the interlayer bonding force between the graphene sheet layers is 80 gf-150 gf.

In the technical scheme, the carbon nano tube is used as the support body to be connected with the graphene, on one hand, the carbon nano tube exists between the graphene, so that the dispersion uniformity of the graphene is enhanced, on the other hand, the carbon nano tube is connected with the graphene through the chemical bond of the carbon nano tube, so that the mutual binding force between the graphene and the carbon nano tube is enhanced, the interlayer binding force between graphene sheets is increased to 80 gf-150 gf, and the feasibility of continuous preparation of the graphene coiled material film is guaranteed. The composite film has large interlayer binding force between graphene layers, can effectively inhibit layering of graphene films, 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 the graphene sheets is 80gf to 150gf, and the interlayer bonding force between the graphene sheets may be 80gf, 90gf, 100gf, 110gf, 120gf, 130gf, 140gf, 150gf, or the like, but may be other values within the above range, which is not limited herein. The applicant finds that the interlayer bonding force in the range can inhibit the 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 may be formed between the graphene and the carbon nanotube, a single six-membered ring structure may also be formed, and the five-membered ring and the six-membered ring may exist simultaneously.

In some embodiments, the mass ratio of graphene to carbon nanotubes is 1: (0.01-0.1), wherein the mass ratio of the graphene to the 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., or may have other values within the above range, and is not limited herein. The mass ratio of the graphene to the carbon nanotubes is less than 1: 0.01, the carbon nano tubes are added excessively, so that the carbon nano tubes are difficult to disperse and easy to agglomerate, the prepared film material is poor in uniformity, and the agglomerated parts are easy to cause film breakage; the mass ratio of the graphene to the carbon nanotubes is more than 1: 0.1, the adding amount of the carbon nano tube is too small, so that the mechanical property of the composite membrane can not be effectively improved.

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

In some embodiments, the tube length of the carbon nanotube is 5 μm to 50 μm, and the tube length of the carbon nanotube may be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or the like, but may be other values within the above range, which is not limited herein.

In some embodiments, the diameter of the carbon nanotube is 4nm to 100nm, and the diameter of the carbon nanotube may be 4nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc., or may be other values within the above range, which is not limited herein.

In some embodiments, the morphology of the carbon nanotubes includes at least one of a wound and an array.

In some embodiments, the composite membrane includes at least two single-layer membrane materials arranged in a stack, wherein the single-layer membrane materials have carbon nanotubes connected between graphene sheets.

In some embodiments, the composite film has a surface-line-surface three-dimensional structure, and it is understood that the single-layer film material has a two-dimensional lamellar structure in which carbon nanotubes are connected between graphene sheets, and a one-dimensional linear structure in which carbon nanotubes are connected between graphene sheets, that is, the single-layer film material has a three-dimensional structure formed by surface-line-surface.

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 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, which is not limited herein. 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 50 μm, 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, etc., or may be other values within the above range, which is not limited herein.

In some embodiments, the thermal conductivity of the composite film is 800W/mK to 1500W/mK, 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., and may be other values within the above range, which is not limited herein.

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

An embodiment of the present application further provides a method for preparing a composite film, as shown in fig. 1, which is a flow chart for preparing the composite film of the present application, including the following steps:

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

And S200, carrying out heat treatment on the graphene oxide/graphene/functionalized carbon nanotube composite membrane to remove oxygen-containing functional groups to obtain the composite membrane.

In the technical scheme, the composite film adopts the slurry containing the graphene oxide, the graphene and the functionalized carbon nanotube as the preparation raw material, and on one hand, cavities and layering caused by volatilization of oxygen-containing functional groups in the graphene oxide at high temperature can be inhibited, so that the expansion problem of the composite film can be effectively weakened, and the preparation of the composite film with low expansion degree is realized. Moreover, the solid content of the slurry in the composite film can be effectively improved by adding the graphene and the functionalized carbon nano tube, 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 method comprises the steps of coating and carrying out heat treatment on slurry containing graphene oxide, graphene and functionalized carbon nanotubes, wherein the functionalized carbon nanotubes in the slurry are loaded on graphene sheets through the action of functional groups, the graphene oxide and groups on the surfaces and edges 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 and the graphene sheets is increased 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, on one hand, the functional groups of the functionalized carbon nanotubes can be uniformly dispersed between graphene oxide and graphene sheets, so that the dispersion uniformity is improved, and agglomeration is prevented; on the other hand, the chemical bond function of the functional group of the functionalized carbon nanotube can enhance the mutual binding force between the graphene and the carbon nanotube, the carbon nanotube is of a one-dimensional linear structure, the graphene is of a two-dimensional lamellar structure, the one-dimensional carbon nanotube plays a good mechanical traction role between two-dimensional graphene lamellar layers, and the binding force of the composite membrane can be improved. As shown in fig. 2, when the aminated carbon nanotube is used, the aminated carbon nanotube and the amide of the carboxyl group on the graphite oxide undergo a dehydration reaction to reduce the content of the carboxyl functional group on the graphite oxide and neutralize the acidity, which is advantageous for inhibiting the swelling delamination of the composite membrane.

The preparation method of the present application is specifically described below with reference to the following examples, which include the following steps:

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

In some embodiments, the thickness of the wet film after the coating treatment is 2400mm to 3500mm, and the thickness may be 2400mm, 2500mm, 2600mm, 2700mm, 2800mm, 2900mm, 3000mm, 3100mm, 3200mm, 3300mm, 3400mm, 3500mm, or the like, or may be other values within the above range, which is not limited herein.

In some embodiments, the wet film obtained from the coating process may need to be dried and cut in stages.

In some embodiments, the temperature for drying is 60 ℃ to 95 ℃, and the temperature for drying may be, for example, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ and 95 ℃, and may be other values within the above range, which is not limited herein.

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, or may be other values within the above range, which is not limited herein.

In some embodiments, before performing step S100, a step of subjecting the slurry containing graphene oxide, graphene and functionalized carbon nanotubes to a defoaming treatment is further included. Namely, slurry containing graphene oxide, graphene and functionalized carbon nanotubes is defoamed and then coated to form a film.

In some embodiments, the apparatus for debubbling comprises an in-line continuous centrifugal debubbling 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, or may be other values within the above range, and is not limited herein.

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

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

In some embodiments, the solid content of the material after the defoaming treatment is 5% to 20%, and the solid content may be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or the like, or may be other values within the above range, which is not limited herein. The solid content of the material after the defoaming treatment is controlled within the range, so that the thickness of the composite film is favorably improved.

In some embodiments, the viscosity of the material after the defoaming treatment is 30000cps to 70000cps, and the viscosity may be 30000cps, 40000cps, 45000cps, 50000cps, 55000cps, 60000cps, 65000cps, 70000cps, or other values within the above range, but is not limited thereto. The solid content of the material after the defoaming treatment is controlled within the range, and the composite coating process conditions are ensured.

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

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, then the rest graphene oxide slurry is added to carry out homogenization treatment on the slurry containing graphene oxide and graphene, the slurry containing graphene oxide and graphene is mixed with functionalized carbon nanotubes to carry out stirring treatment and grinding treatment, and the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is obtained.

In the preparation steps, the graphene oxide slurry is obtained firstly, then part of the graphene oxide slurry is prepared into the graphene oxide dispersion liquid, and finally, the graphene oxide is fully contacted with the graphene by dispersing the graphene in the graphene oxide dispersion liquid, so that the dispersion uniformity and stability of the graphene in the graphene oxide/graphene mixed slurry are improved. Through strong shearing, impacting, cavity and turbulent vortex effects generated by homogenizing treatment, graphene oxide sheets and graphene sheets in the graphene oxide slurry can be effectively stripped, and the dispersion uniformity of graphene in the graphene oxide/graphene mixed slurry is further improved. The solid content of the slurry containing the graphene oxide, the graphene and the functionalized carbon nano tubes can be improved by adding the graphene and the functionalized carbon nano tubes, and the subsequent coating efficiency and the thickness of a single-layer film are further improved; the graphene oxide has the advantages that the surface of the graphene oxide contains rich functional groups such as hydroxyl, epoxy, carboxyl and the like, in the application, the graphene oxide can be used as a film forming substance and also used as a dispersing adhesive, so that the full development of graphene sheet layers is facilitated, the formation of chemical bonds between transverse molecules between the sheet layers is facilitated, after stirring treatment, the graphene and the functionalized carbon nano tube form a five-membered ring structure and/or a six-membered ring structure, and the binding force between the graphene sheet layers can be enhanced. The functionalized carbon nanotube is added in the second step without homogenization treatment, so that the good length-diameter ratio of the functionalized carbon nanotube is kept, and the acting force between graphene sheet layers is better enhanced. In some embodiments, the mass of the graphene oxide in the partial graphene oxide slurry is 0.01% to 0.1% of the mass of the graphene, specifically, the mass of the 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% of the mass of the graphene, and the like, and may be other values within the above range, which is not limited herein.

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 be specifically 70%, 73%, 75%, 80%, 83%, 85%, and the like, and may be other values within the above range, which is not limited herein. It can be understood that the graphene is low-oxidation-degree graphene, so that the oxygen content in the slurry can be reduced, and the problem of high expansion of the film caused by a large amount of 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 the graphene is performed under stirring conditions. The stirring speed under the stirring conditions is 3000rpm to 5000rpm, and may be, specifically, 3000rpm, 3300rpm, 3500rpm, 3700rpm, 4000rpm, 4200rpm, 4500rpm, 4800rpm, 5000rpm, or the like, or 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 be specifically 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, or the like, or may be other values within the above range, which is not limited herein.

In some embodiments, the pressure for homogenization is 500bar to 1250bar, and the pressure for homogenization may specifically be 500bar, 600bar, 700bar, 800bar, 900bar, 1000bar, 1100bar, 1200bar, 1250bar, etc., and 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 ℃, and the temperature of the homogenization treatment is specifically 10 ℃, 12 ℃, 15 ℃, 17 ℃, 20 ℃, 22 ℃, 24 ℃, 25 ℃ or the like, and may be other values within the above range, and is not limited herein.

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

In some embodiments, the graphene oxide slurry is obtained by dispersing graphite oxide or purchasing commercially available graphene oxide slurry, and when the graphene oxide slurry is obtained by using a graphite oxide dispersion treatment, crushing a graphite oxide filter cake with a carbon content of less than 70%, and stirring and dispersing the crushed graphite oxide filter cake in deionized water.

The preparation process of the functionalized carbon nanotube is the prior art, and the product which is already commercialized 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 the graphene oxide, the graphene and the functionalized carbon nanotube 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 have other values within the above range, and is not limited herein. The control of the proportion is beneficial to improving the dispersion uniformity of the functionalized carbon nanotubes, the graphene oxide and the graphene in the slurry, and the uniform dispersion of the functionalized carbon nanotubes is beneficial to improving the interlayer binding force among graphene sheet layers and inhibiting the expansion delamination of the film. The addition amount of the functionalized carbon nanotubes in the graphene oxide slurry is too small, so that the prepared membrane material has poor binding force and the expansion and delamination of the membrane cannot be effectively inhibited; the addition amount of the functionalized carbon nanotubes in the graphene oxide slurry is too much, so that the dispersion uniformity of the slurry is poor, and the thermal conductivity of the prepared film material is low.

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

In some embodiments, the tube length of the functionalized carbon nanotube is 5 μm to 50 μm, and the tube length of the functionalized carbon nanotube may be specifically 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or the like, or may be other values within the above range, which is not limited herein.

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

In some embodiments, the morphology of the functionalized carbon nanotubes includes at least one of a wound and an array.

In some embodiments, the second dispersion process comprises a stirring process and a milling process.

In some embodiments, the apparatus for blending processes comprises a double planetary blender.

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

In some embodiments, the stirring rate of the stirring process is 3000rpm to 5000rpm, and the stirring rate is specifically 3000rpm, 3500rpm, 4000rpm, 4500rpm, 5000rpm, and the like, and may be other values within the above range, which is not limited herein.

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, or may be other values within the above range, which is not limited herein.

In some embodiments, the polishing speed is 3000rpm to 5000rpm, and the polishing speed may be, for example, 3000rpm, 3500rpm, 4000rpm, 4500rpm, 5000rpm, etc., and may be other values within the above range, which is not limited herein.

In some embodiments, the time of the polishing process 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, or may be other values within the above range, which is not limited herein.

In some embodiments, the number of times of the polishing treatment is 2 to 4, and the number of times of the polishing treatment may be, for example, 2, 3, 4, or the like, or may be other values within the above range, and is not limited herein. The purpose of multiple grinding is to fully mix and uniformly disperse the functionalized carbon nanotubes and the graphene.

In some embodiments, the pH of the graphene oxide/graphene mixed slurry is 6-8. Specifically, since the graphite oxide has a low pH and is acidic, the pH of the graphene oxide/graphene mixed slurry is adjusted to be neutral by dropping an alkali solution after the second dispersion treatment in order not to affect the subsequent operation.

And 200, carrying out heat treatment on the graphene oxide/graphene/functionalized carbon nanotube composite membrane to remove oxygen-containing functional groups to obtain the composite membrane.

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

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

In some embodiments, the temperature increase rate of the pretreatment is 5 ℃/min to 10 ℃/min, and the temperature increase rate may be, for example, 5 ℃/min, 6 ℃/min, 7 ℃/min, 8 ℃/min, 9 ℃/min, 10 ℃/min, or the like, or may be other values within the above range, which is not limited herein.

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., or may be other values within the above range, which is not limited herein.

In some embodiments, carbonization and graphitization are performed in the same equipment, and the graphene oxide/graphene/functionalized carbon nanotube composite membrane is subjected to uninterrupted carbon and graphitization treatment, 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 apparatus employed for carbonization and graphitization includes an integrated high temperature furnace.

In some embodiments, the specific steps of the carbonization and graphitization treatment are: firstly, raising the temperature to 1000-1500 ℃ under the condition of continuous vacuum to carry out carbonization treatment, and then rapidly raising the temperature to 2600-3100 ℃ in a protective atmosphere to carry out 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, or may be other values within the above range, and is not limited herein.

In some embodiments, the temperature increase rate of the carbonization treatment is 5 ℃/min to 30 ℃/min, and the temperature increase rate may be, for example, 5 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min, 30 ℃/min, or the like, or may be other values within the above range, which is not limited herein.

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

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

In some embodiments, the time for the graphitization treatment is 10h to 72h, and the time for the graphitization treatment may be 10h, 15h, 20h, 24h, 30h, 36h, 40h, 48h, 52h, 60h, 66h, 70h, 72h, or the like, and may be other values within the above range, which is not limited herein.

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

In some embodiments, the temperature increase rate of the graphitization heat treatment is 10 ℃/min to 30 ℃/min, and the temperature increase rate may be, for example, 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min, 30 ℃/min, etc., or may be other values within the above range, which is not limited herein.

In the step, the slurry containing the graphene oxide, the graphene and the functionalized carbon nanotube is pretreated in a graphite clamp after graphite paper lamination is carried out, and oxygen-containing functional groups in the slurry are removed.

In some embodiments, the resulting composite membrane may be obtained by subjecting one or more monolayer membrane materials to a compaction process after heat treatment.

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

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

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

According to the preparation method, the compounding of the graphene oxide, the graphene and the functionalized carbon nano tube is adopted, so that the oxygen content of the slurry can be reduced, the expansion of the heat-conducting composite film is effectively inhibited, the product yield of the graphene heat-conducting composite film is improved, 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, and 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 connection among graphene sheet layers, the interlayer binding force among the graphene sheet layers is effectively improved through the heat treatment step, and a foundation is laid for the subsequent production of the graphene heat-conducting film coiled material.

The embodiment of the application also provides electronic equipment, and the electronic equipment comprises the composite film prepared by the method.

The following examples are intended to illustrate the invention in more detail. The embodiments of the present invention are not limited to the following specific embodiments. The present invention can be modified and implemented as appropriate within the scope of the main claim.

Example 1

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

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

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

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

(5) And (3) compacting the single-layer film material subjected to heat treatment on the PET substrate by using a pair-roller calender, wherein the pressure of the compacting treatment is 50MPa, so that the composite film is obtained.

In the above embodiment, the addition mass ratio of the graphene oxide, the graphene and the aminated carbon nanotube in step (1) 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, which shows that: the graphene oxide/graphene/aminated carbon nanotube composite slurry prepared in the embodiment 1 of the application has the advantages that the aminated carbon nanotube and the graphene are uniformly dispersed and do not agglomerate.

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

As shown in fig. 5, a 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, which shows that: the average peel force (i.e., interlayer bonding force) of the composite film of example 1 was 110 gf.

Example 2

Different from the embodiment 1, the addition mass ratio of the graphene oxide, the graphene and the aminated carbon nanotube in the step (1) is 1: 0.02: 0.005.

in the composite film prepared by the embodiment, the graphene layers are stacked, the carbon nanotubes are connected between the graphene sheets, and the numerical values of the thickness, the tensile strength and the interlayer bonding force are shown in table 1.

Example 3

Different from the embodiment 1, the addition mass ratio of the graphene oxide, the graphene and the aminated carbon nanotube in the step (1) is 1: 1: 0.1.

in the composite film prepared by the embodiment, the graphene layers are stacked, the graphene layers are connected through the nanotube, and the numerical values of the thickness, the tensile strength and the interlayer bonding force are shown in table 1.

Example 4

Different from the embodiment 1, the addition mass ratio of the graphene oxide, the graphene and the aminated carbon nanotube in the step (1) is 1: 5: 0.2.

in the composite film prepared by the embodiment, the graphene layers are stacked, the graphene layers are connected, and the numerical values of the thickness, the tensile strength and the interlayer bonding force are shown in table 1.

Example 5

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

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 pretreatment in step (3) was not performed.

Example 8

Different from the embodiment 1, in the step (1), the graphene oxide slurry and the graphene are mixed and homogenized at high pressure to obtain a graphene oxide/graphene mixed slurry.

Example 9

In contrast to example 1, the carbonization temperature in step (4) was 950 ℃.

Example 10

In contrast to example 1, the carbonization temperature in step (4) was 1000 ℃.

Example 11

In contrast to example 1, the carbonization temperature in step (4) was 1300 ℃.

Example 12

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

Example 13

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

Example 14

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

Example 15

Unlike example 1, the temperature of the graphitization heat treatment 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 is as follows:

(1) weighing 100g of graphite oxide filter cake blocks with solid content of 70% in a double-planet stirrer material cylinder, grinding, diluting and dispersing in 2000ml of deionized water, uniformly stirring at a stirring speed of 30rmp/min, and then homogenizing at high pressure to obtain graphene oxide slurry; adding 19.31ml of ammonia water to obtain pH of 7, maintaining stirring at 30rmp/min for 1h, and then stirring and dispersing at a stirring speed of 120rmp/min and a dispersion speed of 5000rmp/min for 2h to obtain graphene oxide slurry with solid content of 5% and viscosity of 50000 cps.

(2) And (3) coating the obtained graphene oxide 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 wet film thickness is 2400mm, and the baking temperature is 90 ℃ for 8 hours to obtain the graphene oxide raw film.

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

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

(5) And (3) compacting the graphitized PET substrate by using a pair-roller calender under the pressure of 50MPa to obtain the graphene film.

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

Performance testing

1. And (3) testing the binding force method: referring to GB/T2792 film raw material double-sided application of tesa adhesive tape, one side is torn off release paper and fixed on a steel plate, the other side is stripped at 180 degrees, the stripping speed is 300mm/min, and the average value of the stable sections is taken.

2. The tensile strength test method is based on GB/T1040.1-2018, and the experiment is carried out by a microcomputer-controlled electronic universal tester.

3. The solid content of the slurry is tested by a weighing method, the upper layer, the middle layer and the lower layer of the defoamed material are respectively sampled by 6-10 g, the number of samples in each layer is 2, the obtained samples are placed in an oven to be baked for 4-6 h at 110 ℃, the weight of each sample is measured after baking, and the solid content of the material is calculated according to 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 testing of composite membranes prepared in examples and comparative examples

As can be seen from the data in Table 1: this application combines high-temperature thermal treatment process optimization through the complex formulation of oxidation graphite alkene, graphite alkene and carbon nanotube, effectively weakens because of the high swelling problem that the oxygen-containing functional group volatilizees in a large number and leads to in high-temperature thermal treatment process, realizes the preparation of low expansibility thick film product, and the complex film of this application preparation, thick liquid solid content is higher, and cohesion between the complex film rete is strong, and the individual layer membrane thickness is thicker, can improve coating process, can realize the mass production of complex film.

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

In examples 1 to 4, the addition mass ratio of graphene to functionalized carbon nanotubes is too small (example 2), which results in failure to effectively inhibit expansion and weak interlayer bonding force of the film; too large a mass ratio of graphene to functionalized carbon nanotubes (example 4) increases the dispersion difficulty, and the uniformity of the film is poor, so that the bonding force between films cannot be effectively improved.

In example 7, the pretreatment of step (3) was not performed, and the prepared composite membrane was too swollen, resulting in easy fracture 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 films had the disadvantages of incomplete removal of functional groups and low thermal conductivity of the composite films.

In examples 1 and 12 to 15, the graphitization temperature was too low (example 12), and the prepared composite membrane had the disadvantages of low graphitization degree and poor thermal conductivity. The graphitization temperature is too high (example 15), and the prepared composite membrane has the defects of too strong 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 films had a problem of high expansion and easy cracking.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Although the present application has been described with reference to preferred embodiments, it is not intended to limit the scope of the claims, and many possible variations and modifications may be made by one skilled in the art without departing from the spirit of the application.

Claims

1. The composite film is characterized by comprising graphene which is arranged in a stacked mode, wherein carbon nanotubes are connected between sheet layers of the graphene, and the interlayer bonding force between the graphene sheet layers is 80 gf-150 gf.

2. The composite film according to claim 1, characterized in that it comprises at least one of the following features (1) to (6):

(1) the graphene and the carbon element of the carbon nano tube form at least one of a five-membered ring structure and a six-membered ring structure;

(2) the mass ratio of the graphene to the carbon nanotubes is 1: (0.01 to 0.1);

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

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

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

(6) the morphology of the carbon nanotubes comprises at least one of a wound and an array.

3. The composite film according to claim 1, characterized in that it comprises at least one of the following features (1) to (6):

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

(2) the composite membrane comprises at least two single-layer membrane materials which are arranged in a stacked mode, wherein the single-layer membrane materials comprise graphene connected with carbon nano tubes in an interlayer mode, and the thickness of the single-layer membrane materials is 25-35 mu m;

(3) the thickness of the composite membrane is 50-300 μm;

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

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

(6) the composite membrane is of a surface-line-surface three-dimensional structure.

4. A preparation method of a composite film is characterized by comprising the following steps:

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

5. The preparation method according to claim 4, wherein the slurry containing graphene oxide, graphene and functionalized carbon nanotubes is prepared by: obtaining graphene oxide slurry, and performing first dispersion treatment on the graphene oxide slurry and the graphene to obtain slurry containing the graphene oxide and the 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 according to claim 5, wherein the first dispersion treatment is performed on the graphene oxide slurry and the graphene to obtain a slurry containing the graphene oxide and the graphene, and specifically comprises: preparing part of the graphene oxide slurry to form a graphene oxide dispersion liquid, mixing the graphene oxide dispersion liquid with the graphene, adding the rest graphene oxide slurry, and homogenizing to obtain the slurry containing the graphene oxide and the graphene, wherein the method comprises at least one of the following characteristics (1) to (7):

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

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

(3) mixing the graphene oxide dispersion liquid with graphene under a stirring condition;

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

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

(6) the number of the homogenization treatment is 2-4;

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

7. The production method according to claim 5, characterized by comprising at least one of the following features (1) to (6):

(1) 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 to 0.1);

(3) the functionalized carbon nanotube comprises at least one of a single wall, a double wall, and a 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) and the second dispersion treatment comprises the steps of sequentially stirring and grinding the slurry containing the graphene oxide and the graphene and the functionalized carbon nanotubes.

8. The production 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, wherein the method comprises at least one of the following features (1) to (5):

(1) 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;

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

(3) the time of the defoaming treatment is 10 min-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 production method according to claim 4, characterized in that the heat treatment includes pretreatment, carbonization treatment, and graphitization treatment, and the method includes at least one of the following features (1) to (15):

(1) the temperature of the pretreatment is 100-400 ℃;

(2) the temperature rising rate of the pretreatment is 5-10 ℃/min;

(3) the pretreatment time is 5-10 h;

(4) the carbonization treatment is carried out under the vacuum condition;

(5) the temperature of the carbonization treatment is 1000-1500 ℃;

(6) the temperature rise rate of the carbonization treatment is 5-30 ℃/min;

(7) the carbonization time is 5-24 h;

(8) the temperature of the graphitization treatment is 2600-3100 ℃;

(9) the temperature rise rate of the graphitization treatment is 10-30 ℃/min;

(10) the graphitization treatment is carried out in a protective atmosphere comprising at least one of argon and nitrogen;

(11) the graphitization treatment time is 10-72 h;

(12) the carbonization treatment and the graphitization treatment are carried out in the same equipment;

(13) after the graphene oxide/graphene/functionalized carbon nanotube composite membrane is subjected to heat treatment to remove oxygen-containing functional groups, the graphene oxide/graphene/functionalized carbon nanotube composite membrane further comprises a step of compacting treatment;

(14) after the graphene oxide/graphene/functionalized carbon nanotube composite membrane is subjected to heat treatment to remove oxygen-containing functional groups, the graphene oxide/graphene/functionalized carbon nanotube composite membrane further comprises a step of compacting treatment, wherein a substrate subjected to the compacting treatment comprises at least one of polyethylene, polyethylene terephthalate, polypropylene and oriented polypropylene;

(15) the graphene oxide/graphene/functionalized carbon nanotube composite membrane is subjected to heat treatment to remove oxygen-containing functional groups, and then the graphene oxide/graphene/functionalized carbon nanotube composite membrane further comprises a step of compacting treatment, wherein the pressure of the compacting treatment is 2 MPa-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.