Thermoplastic bidirectional high-thermal-conductivity composite material and preparation method thereof

Abstract

The invention discloses a thermoplastic bidirectional high-thermal-conductivity composite material and a preparation method thereof, and the thermoplastic bidirectional high-thermal-conductivity composite material is prepared by finely regulating and controlling a preparation process, introducing thermoplastic resin and nano thermal-conductivity filler particles into pores / gaps of filler for pre-filling, and then further performing banburying mixing and hot-pressing treatment. Due to the fact that the nanometer heat conduction filler particles and the thermoplastic resin are filled between the three-dimensional filler layers to play a supporting role, more out-of-plane heat transmission paths can be constructed, the out-of-plane heat conduction coefficient is remarkably improved, and meanwhile due to the good in-plane heat conduction coefficient under the hot-pressing condition, the heat conduction performance of the composite material is improved. Finally, the thermoplastic heat-conducting composite material disclosed by the invention has bidirectional high heat-conducting property.

Description

Technical Field

[0001] The present invention relates to a thermoplastic thermal conductive composite material, and specifically to a high-efficiency heat dissipation material applied to high-power electronic devices and a preparation method thereof. Background Art

[0002] As electronic devices develop towards high integration, miniaturization, and high power density, a large amount of heat is generated from components. If the heat is not dissipated in time, the problem of heat accumulation will become increasingly prominent; this may seriously affect the service life and thermal stability of the equipment, and even cause a fire, resulting in irreparable losses. Therefore, the development of efficient heat dissipation materials for high-power electronic devices has received more and more attention.

[0003] At present, polymer-based materials are increasingly gaining widespread attention in the field of thermal management due to their advantages such as light weight, easy processing and corrosion resistance. The inherent low thermal conductivity of thermoplastic polymers (0.1-0.2 W / m·K) severely limits their application in the field of thermal management. In order to improve the thermal conductivity of thermoplastic polymer materials, filling with high thermal conductivity fillers is one of the effective methods, including metals, metal oxides, inorganic compounds and carbon-based fillers. In the structural design of the material, using high thermal conductivity fillers and the overlap between the constructed micro three-dimensional fillers to construct a continuous three-dimensional thermal conductive network in the composite material is an effective method to greatly improve the thermal conductivity of the material. However, in the preparation process, the direct mixing method has limited improvement in thermal conductivity because it is not easy for fillers to overlap to form a continuous network. The hot pressing process is considered to be an effective method for preparing dense heat transfer networks and well-oriented high thermal conductivity composite materials because the application of external force is more conducive to the dense overlap between fillers to form a connected heat transfer network. For example, Chinese patent CN117625139A uses a specific directional freezing device to ensure the high consistency of the orientation of the expanded graphite inside the paraffin after directional freezing, and then uses hot pressing to further densify, regulate the anisotropic distribution of thermal conductivity, and significantly improve the unidirectional heat transfer rate. The final composite material has a maximum in-plane thermal conductivity of 8.1 W / m·K and an out-of-plane thermal conductivity of 3.4 W / m·K. Chinese patent CN 118325335A mixes polyol-polysiloxane prepolymer, nanosilver-modified expanded graphite and curing agent, and then performs hot pressing vulcanization to obtain a composite material with an in-plane thermal conductivity of 23.4 W / m·K and an out-of-plane thermal conductivity of 8.1 W / m·K.

[0004] However, under hot pressing conditions, most of the fillers are arranged perpendicular to the hot pressing direction with the external force, making the heat transfer efficiency of the composite material in the in-plane direction higher, while the out-of-plane heat transfer capacity is very limited. At the same time, the resin encapsulated in the micron and nano pores / gaps of the filler has a low thermal conductivity, which limits the effective transfer of heat to the out-of-plane direction, resulting in limited improvement in the out-of-plane thermal conductivity (<10 W / m·K).

[0005] In addition, usually, nanoparticles are small in size and can be easily embedded in the micron and nano pores / gaps of the three-dimensional structure to support the three-dimensional structure of the composite material and increase the number of heat transfer paths. However, in terms of preparation technology, the direct mixing of the two fillers cannot ensure that the particles are introduced into the three-dimensional structure due to the lack of driving force; at the same time, thermoplastic resins are mostly solid particles, which are also difficult to embed into the pores of the three-dimensional structure; the solution mixing method will shrink the inherent three-dimensional structure of the filler during the solvent evaporation process, and requires a large amount of solvent, resulting in an increase in preparation costs; direct ball milling / mixing mixing will destroy the three-dimensional structure of the material during the mixing process due to its violent impact and friction, resulting in limited improvement in out-of-plane thermal conductivity.

[0006] Therefore, how to adopt a simpler, more efficient and cleaner preparation process to introduce high thermal conductivity particles into the three-dimensional thermal conductive network micro-regions without destroying the constructed three-dimensional structure, construct more heat transfer paths, and achieve out-of-plane and in-plane bidirectional high thermal conductivity of composite materials has become an urgent problem to be solved. Summary of the invention

[0007] In view of this, the present disclosure provides a thermoplastic bidirectional high thermal conductivity composite material and a preparation method thereof, which solves the problem that the thermal conductivity of the current thermoplastic thermal conductive composite material in the out-of-plane direction needs to be improved.

[0008] The invention idea of ​​the thermoplastic bidirectional high thermal conductivity composite material of the present invention is as follows: First, in a vacuum melting state, nano thermal conductive fillers and molten thermoplastic resins are slowly adsorbed into the micron and nano pores / gaps of the three-dimensional network-constructed fillers through micro-adsorption by capillary force for pre-filling, thereby effectively supporting the pores / gaps; second, the pre-filled molten mixture is placed in an internal mixer for internal mixing, and a composite state with more complete mixing, adsorption and dispersion is obtained after the internal mixing; third, the composite material after internal mixing is placed in a hot pressing mold, and a hot pressing process is further used to perform dense overlap between fillers to form a connected heat transfer network, thereby obtaining a dense heat transfer network and an excellently oriented high thermal conductivity composite material; through the coordinated regulation of the above three aspects, since the micron and nano pores / gaps of the three-dimensional network-constructed fillers are filled with nano thermal conductive fillers and thermoplastic resins for support, the subsequent internal mixing and hot pressing processes can be prevented from damaging the heat transfer path, so that the high thermal conductivity channel in the out-of-plane direction of the thermoplastic high thermal conductivity composite material can be maximized and the filler network can be densified, and finally out-of-plane and in-plane bidirectional high thermal conductivity can be obtained.

[0009] To achieve the above-mentioned object of the invention, in a first aspect, the method for preparing the thermoplastic bidirectional high thermal conductivity composite material disclosed in the present invention comprises: After subjecting the mixture of the three-dimensional network structure filler, the thermoplastic resin and the nano thermal conductive filler to vacuum heating and melting treatment, the molten mixture is subjected to banburying treatment. After the banburying treatment is completed, the banburying product is subjected to hot pressing treatment to obtain the thermoplastic high thermal conductive composite material.

[0010] In the present disclosure and possible embodiments, the mass ratio of the three-dimensional network construction filler to the nano thermal conductive filler is 1:4 to 4:1; The three-dimensional network construction filler and the nano thermal conductive filler account for 10-90wt% of the total mass of the thermal conductive composite material.

[0011] In the present disclosure and possible embodiments, the three-dimensional network construction filler includes graphite, carbon felt, carbon fiber, boron nitride, graphene and carbon nanotubes.

[0012] In the present disclosure and possible embodiments, the graphite is expanded graphite; The thermoplastic resin includes polyvinylidene fluoride, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyimide and polyetheretherketone.

[0013] In the present disclosure and possible embodiments, the nano thermal conductive filler includes nano aluminum oxide, nano silicon carbide, nano diamond, nano boron nitride, nano silver, nano copper and nano silicon nitride.

[0014] In the present disclosure and possible embodiments, the temperature of the vacuum heating melting treatment is 80-280° C., the time is 2-6 h, and the vacuum degree is -0.1 MPa.

[0015] In the present disclosure and possible embodiments, the mixing temperature of the internal mixer used in the internal mixing treatment is 80-280° C., and the internal mixing time is 10-60 min.

[0016] In the present disclosure and possible embodiments, the hot pressing conditions of the hot pressing treatment are: preheating at a temperature of 80-280°C for 10-60 min, then maintaining the pressure at a pressure of 5-30 MPa for 1-3 h, cooling to room temperature after the pressure maintenance, and demolding to obtain the thermoplastic high thermal conductivity composite material.

[0017] In a second aspect, the thermoplastic bidirectional high thermal conductivity composite material is prepared by any method described in the first aspect.

[0018] The present invention has the beneficial effects: The thermoplastic bidirectional high thermal conductivity composite material disclosed in the present invention is prepared by introducing thermoplastic resin and nano thermal conductive filler particles into the pores / gaps of the filler for pre-filling through finely controlled preparation process, and then further mixing and hot pressing. In the structure of the composite material, since the nano thermal conductive filler particles and thermoplastic resin are filled in the three-dimensional filler layers to play a supporting role, more out-of-plane heat transfer paths can be constructed, thereby significantly improving the out-of-plane thermal conductivity. At the same time, due to the good in-plane thermal conductivity under hot pressing conditions, the bidirectional high thermal conductivity performance of the thermoplastic thermal conductive composite material disclosed in the present invention is finally achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which: FIG1A is a cross-sectional view of the thermoplastic bidirectional high thermal conductivity composite material of Example 1; Figure 1B It is an enlarged cross-section view; Figure 2A This is the SEM image of the mixture obtained by direct mechanical mixing in Comparative Example 1; Figure 2B This is the SEM image of the mixture after melt micro-adsorption in Comparative Example 1; Figure 3 It is a diagram of the heat conduction mechanism using two-dimensional graphite and three-dimensional expanded graphite; Figure 4 It is a diagram of the heat conduction mechanism with and without the use of nano thermal conductive filler particles. DETAILED DESCRIPTION

[0020] The present disclosure is described below based on specific embodiments, but it is worth noting that the present disclosure is not limited to these specific embodiments. In the detailed description of the present disclosure below, some specific details are described in detail. However, for the parts that are not described in detail, those skilled in the art can also fully understand the present disclosure.

[0021] At the same time, unless the context clearly requires otherwise, the words "include", "comprises" and similar words throughout the specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0022] Although the hot pressing process is considered to be an effective method for preparing dense heat transfer networks and excellent orientation thermal conductive composite materials because the application of external force is more conducive to the dense overlap between fillers to form a connected heat transfer network, under the conditions of hot pressing and mixing, the fillers will be quickly squeezed into dense sheets, thereby limiting the entry of nano-thermal conductive filler particles and resin into the micron and nano-pores / gaps of the fillers. Most of the fillers are arranged perpendicular to the pressure direction with the external force, making the thermal conductive composite material have a high heat transfer efficiency in the in-plane direction, while the out-of-plane heat transfer capacity is very limited.

[0023] Obviously, if traditional mechanical and physical mixing is adopted, the resin particles and nano-thermal conductive filler particles cannot enter the micro-voids inside the three-dimensional filler particles. The present invention adjusts the vacuum degree and uses capillary force to micro-adsorb thermoplastic resin and nano-thermal conductive filler particles into the micron and nano-pores / gaps of the filler to provide partial or full support for the microstructure, further adopts banburying treatment to strengthen adsorption, mixing and dispersion, and uses hot pressing process to perform dense overlap between fillers to form a connected heat transfer network, thereby obtaining a dense heat transfer network and an excellent oriented high thermal conductivity composite material; through the coordinated regulation of the above three aspects, because the micron and nano-pores / gaps of the filler constructed in the three-dimensional network are filled with nano-thermal conductive fillers and thermoplastic resin for support, it can prevent the subsequent banburying and hot pressing processes from damaging the heat transfer path, so the high thermal conductivity channel in the out-of-plane direction of the thermoplastic high thermal conductivity composite material can be maximized and the filler network can be densified, and finally the out-of-plane and in-plane bidirectional high thermal conductivity can be obtained.

[0024] To this end, in each embodiment of the present disclosure, the preparation method of the thermoplastic bidirectional high thermal conductivity composite material is as follows: After subjecting the mixture of the three-dimensional network construction filler, the thermoplastic resin and the nano thermal conductive filler to vacuum heating and melting treatment, the molten mixture is subjected to banburying treatment. After the banburying treatment is completed, the banburying material is subjected to hot pressing treatment to obtain the thermoplastic high thermal conductive composite material.

[0025] In a specific embodiment, the mass ratio of the three-dimensional network construction filler to the nano thermal conductive filler is 1:4-4:1; the three-dimensional network construction filler and the nano thermal conductive filler account for 10-90wt% of the total mass of the thermal conductive composite material.

[0026] In a specific embodiment, the three-dimensional network construction filler includes graphite, carbon felt, carbon fiber, boron nitride, graphene and carbon nanotubes, wherein the graphite is preferably expanded graphite.

[0027] In a specific embodiment, the thermoplastic resin includes polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), polyimide (PI) and polyetheretherketone (PEEK).

[0028] In a specific embodiment, the nano thermal conductive filler includes nano aluminum oxide, nano silicon carbide, nano diamond, nano boron nitride, nano silver, nano copper and nano silicon nitride.

[0029] In a specific embodiment, the temperature of the vacuum heating melting treatment is 80-280° C., the time is 2-6 h, and the vacuum degree is -0.1 MPa.

[0030] In a specific embodiment, the mixing temperature of the internal mixer used in the internal mixing treatment is 80-280° C., and the internal mixing time is 10-60 min.

[0031] In a specific embodiment, the hot pressing conditions of the hot pressing treatment are: preheating at a temperature of 80-280°C for 10-60 minutes, then maintaining the pressure at a pressure of 5-30 MPa for 1-3 hours, cooling to room temperature after the pressure maintenance, and demolding to obtain the thermoplastic high thermal conductivity composite material.

[0032] Unless otherwise specified, the materials used in the embodiments of the present disclosure can be purchased or prepared by conventional methods with reference to relevant literature.

[0033] The following are specific embodiments of the present disclosure and corresponding comparative examples. Example 1

[0034] The method of the present invention is used to prepare a thermoplastic high thermal conductivity composite material, which is specifically as follows: (1) Add a certain amount of silane coupling agent modified nano M-Al2O3, expanded graphite, and polyvinylidene fluoride (PVDF) into a beaker, where the modified nano alumina M-Al2O3 and expanded graphite account for 10 wt% and 40 wt% respectively, and PVDF accounts for 50 wt%. After mixing the three components, place them in a vacuum oven at 180°C with a vacuum degree of -0.1 MPa, melt for 2 h, cool them down, and take them out; (2) adding the vacuum melted mixture of step (1) into an internal mixer for further mixing, wherein the operating temperature of the internal mixer is 190° C., the rotation speed is 40 rpm, and the internal mixing time is 15 min; (3) The product after the banburying in step (2) was placed in a hot pressing mold for hot pressing at a temperature of 190° C., preheated for 30 min, a pressure of 7.5 MPa, and a holding time of 1.5 h. After cooling to room temperature, the product was demolded and polished to obtain the thermoplastic bidirectional high thermal conductivity composite material of Example 1.

[0035] The cross-sectional view of the thermoplastic bidirectional high thermal conductivity composite material of Example 1 is as follows Figure 1A and Figure 1B As shown, it can be seen from the SEM image that the internal pores of the composite material prepared by the vacuum heating melting-mixing-hot pressing process are fully filled with nano-thermal conductive filler particles, which play a role in supporting the pores and constructing more out-of-plane heat transfer paths.

[0036] Comparative Example 1 Comparative Example 1 is different in that the vacuum heating melting process is not used, but the silane coupling agent modified nano M-Al2O3, expanded graphite and PVDF are directly mechanically mixed, and after mechanical mixing, internal mixer mixing and hot pressing are continued to obtain the thermoplastic thermal conductive composite material of this comparative example 1.

[0037] The SEM image of the mixture obtained by direct mechanical mixing of the silane coupling agent modified nano M-Al2O3, expanded graphite and PVDF in this comparative example 1 is as follows: Figure 2A As shown, in addition, the SEM image of the mixture obtained by vacuum melting micro-adsorption of the same silane coupling agent modified nano M-Al2O3, expanded graphite and PVDF is as follows Figure 2B As shown, through Figure 2A Figure 2B It can be seen from the comparison that direct mechanical mixing cannot fill the resin particles into the pores, resulting in many resin particles on the surface of the expanded graphite. After melt micro-adsorption, the molten resin enters the pores of the expanded graphite, and there are no resin particles on the surface.

[0038] Comparative Example 2 The same preparation process as in Example 1 is used, except that the expanded graphite is replaced with a two-dimensional graphite filler.

[0039] Comparative Example 3 The same preparation process as in Example 1 is adopted, except that nano M-Al2O3 which is not modified by a silane coupling agent is filled.

[0040] Comparative Example 4 The same preparation process as in Example 1 was used, except that the nano M-Al2O3 modified by the silane coupling agent was not added. Example 2

[0041] Thermoplastic high thermal conductivity composite material is prepared according to the method of the present invention: (1) Add a certain amount of nano-silicon carbide SiC, expanded graphite and polyvinylidene fluoride resin PVDF into a beaker, where nano-silicon carbide SiC and expanded graphite account for 10 wt% and 40 wt% respectively, and PVDF accounts for 50 wt%. After mixing the three components, place them in a vacuum oven at 180℃ with a vacuum degree of -0.1 MPa for 3 hours of melt micro-adsorption, then cool and take them out; (2) adding the molten micro-adsorption mixture of step (1) into an internal mixer for further mixing, wherein the operating temperature of the internal mixer is 190° C., the rotation speed is 40 rpm, and the internal mixing time is 20 min; (3) The kneaded product of step (2) is placed in a hot pressing mold, preheated at 190°C for 30 min, hot pressed at a pressure of 7.5 MPa, and held for 2 h. After cooling to room temperature, the mold is removed to obtain the thermoplastic bidirectional high thermal conductivity composite material of Example 2.

[0042] Comparative Example 5 The same raw materials and contents as those in Example 2 are used, and after vacuum melting, micro-adsorption and banburying, the thermoplastic thermal conductive composite material of Comparative Example 5 is directly obtained without hot pressing.

[0043] Table 1 In-plane and out-of-plane thermal conductivity values ​​of comparative examples and examples As shown in Table 1, compared with Comparative Examples 1-4, the in-plane and out-of-plane thermal conductivity of the composite material of Example 1 are significantly improved, indicating that the filling support of the nano thermal conductive particles plays a positive role in constructing more out-of-plane heat transfer paths.

[0044] Specifically, due to direct mechanical mixing in Comparative Example 1, the thermoplastic resin particles cannot be well embedded in the pores of the three-dimensional structure of the expanded graphite ( Figure 2A As shown), air exists between the pores, which increases the thermal resistance; and because the pores are not pre-filled, the three-dimensional structure of the expanded graphite is easily squeezed into a two-dimensional structure during the banburying process, which is not conducive to building a three-dimensional thermal conductive network. The resin and nanoparticles are also difficult to be completely adsorbed into the pores during the banburying process, and cannot play a role in supporting the three-dimensional structure and building a dense heat transfer path. Therefore, the thermal conductivity of the comparative example 1 is greatly reduced compared with the thermal conductivity of the composite material prepared in Example 1.

[0045] Comparative Example 2 Since the two-dimensional graphite is used, it is not conducive to the adsorption of nanoparticles and thermoplastic resins during the preparation process, and the two-dimensional filler is not conducive to the construction of a continuous overlap to form a three-dimensional thermal conductive network in the composite material. Therefore, the thermal conductivity of the prepared composite material is much lower than that of the three-dimensional filler. The specific thermal conductivity mechanism is as follows Figure 3 shown.

[0046] Comparative Example 3 uses unmodified nanoparticles, which results in poor interface compatibility between the resin filler and a slight decrease in thermal conductivity.

[0047] Comparative Example 4 does not use nanoparticles to support the micro three-dimensional structure constructed by expanded graphite, and cannot construct more heat transfer paths, resulting in a significant decrease in the out-of-plane thermal conductivity. The specific thermal conduction mechanism is as follows Figure 4 shown.

[0048] Since the composite material in Comparative Example 5 is not prepared by hot pressing, a dense three-dimensional thermal conductive network cannot be formed inside the material, resulting in a thermal conductivity coefficient much lower than that of Example 2 using hot pressing process; Example 3

[0049] Thermoplastic bidirectional high thermal conductivity composite material is prepared according to the method of the present invention: (1) Add a certain amount of nanodiamond, expanded graphite and polyvinylidene fluoride resin PVDF into a beaker, where nanodiamond and expanded graphite account for 15 wt% and 35 wt% respectively, and PVDF accounts for 50 wt%. After mixing the three components, place them in a vacuum oven at 180℃ with a vacuum degree of -0.1 MPa for 3 h of melt micro-adsorption, then cool and take them out; (2) adding the vacuum melt micro-adsorption mixture of step (1) into an internal mixer for further mixing, wherein the operating temperature of the internal mixer is 190° C., the rotation speed is 40 rpm, and the internal mixing time is 10 min; (3) The mixed product after the mixing in step (2) is placed in a hot pressing mold, preheated at a temperature of 190° C. for 40 min, a hot pressing pressure of 10 MPa, and a holding time of 1.5 h. After cooling to room temperature, demolding is performed to obtain a thermoplastic bidirectional high thermal conductivity composite material of Example 3. Example 4

[0050] Thermoplastic high thermal conductivity composite material is prepared according to the method of the present invention: (1) Add a certain amount of nano-alumina, graphite and polyethylene resin into a beaker, where nano-alumina and graphite account for 20 wt% and 50 wt% respectively, and polyethylene resin accounts for 30 wt%. After mixing the three components, place them in a vacuum oven at 150℃ with a vacuum degree of -0.1 MPa for 3 h of melt micro-adsorption, then cool and take them out; (2) adding the vacuum melt micro-adsorption mixture of step (1) into an internal mixer for further mixing, wherein the operating temperature of the internal mixer is 150° C., the rotation speed is 40 rpm, and the internal mixing time is 20 min; (3) The mixed product after the mixing in step (2) is placed in a hot pressing mold, preheated at a temperature of 150° C. for 40 min, a hot pressing pressure of 15 MPa, and a holding time of 2 h. After cooling to room temperature, the mold is demolded to obtain the thermoplastic bidirectional high thermal conductivity composite material of this embodiment 4. Example 5

[0051] Thermoplastic high thermal conductivity composite material is prepared according to the method of the present invention: (1) Add a certain amount of nano-silicon carbide, graphene and polypropylene resin into a beaker, where nano-silicon carbide and graphene account for 20 wt% and 50 wt% respectively, and polypropylene resin accounts for 30 wt%. After mixing the three components, place them in a vacuum oven at 180℃ with a vacuum degree of -0.1 MPa, melt micro-adsorb for 3 hours, then cool and take them out; (2) adding the molten micro-adsorbed mixture in step (1) into an internal mixer for further mixing, wherein the operating temperature of the internal mixer is 200° C., the speed is 40 rpm, and the mixing time is 10 min; (3) The mixed product after the mixing in step (2) is placed in a hot pressing mold, preheated at a temperature of 200° C. for 35 min, a hot pressing pressure of 10 MPa, and a holding time of 1 h. After cooling to room temperature, the mold is demolded to obtain the thermoplastic bidirectional high thermal conductivity composite material of this embodiment 5.

[0052] The in-plane and out-of-plane thermal conductivity values ​​of Examples 3-5 are shown in Table 2: Table 2 In-plane and out-of-plane thermal conductivity values ​​of Examples 3-5 The above-described embodiments are only embodiments of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the present disclosure. It should be noted that, for a person of ordinary skill in the art, without departing from the concept of the present disclosure, several variations, equivalent substitutions, improvements, etc. may be made, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the attached claims.

Claims

1. A method for preparing the thermoplastic bidirectional high thermal conductivity composite material, characterized in that: include: After subjecting the mixture of the three-dimensional network structure filler, the thermoplastic resin and the nano thermal conductive filler to vacuum heating and melting treatment, the molten mixture is subjected to banburying treatment. After the banburying treatment is completed, the banburying product is subjected to hot pressing treatment to obtain the thermoplastic high thermal conductive composite material.

2. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 1, characterized in that: The mass ratio of the three-dimensional network construction filler to the nano thermal conductive filler is 1:4 to 4:1; The three-dimensional network construction filler and the nano thermal conductive filler account for 10-90wt% of the total mass of the thermal conductive composite material.

3. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 1 or 2, characterized in that: The three-dimensional network construction filler includes graphite, carbon felt, carbon fiber, boron nitride, graphene and carbon nanotubes.

4. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 3, characterized in that: The graphite is expanded graphite; The thermoplastic resin includes polyvinylidene fluoride, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polyimide and polyetheretherketone.

5. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 4, characterized in that: The nano thermal conductive filler includes nano aluminum oxide, nano silicon carbide, nano diamond, nano boron nitride, nano silver, nano copper and nano silicon nitride.

6. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 5, characterized in that: The temperature of the vacuum heating melting treatment is 80-280° C., the time is 2-6 h, and the vacuum degree is -0.1 MPa.

7. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 6, characterized in that: The mixing temperature of the internal mixer used in the internal mixing treatment is 80-280° C., and the internal mixing time is 10-60 min.

8. The method for preparing the thermoplastic bidirectional high thermal conductivity composite material according to claim 7, characterized in that: The hot pressing conditions of the hot pressing treatment are: preheating at a temperature of 80-280°C for 10-60 min, then maintaining the pressure at a pressure of 5-30 MPa for 1-3 h, cooling to room temperature after the pressure maintenance, and demolding to obtain the thermoplastic high thermal conductivity composite material.

9. A thermoplastic bidirectional high thermal conductivity composite material, characterized in that: The composite material is: The method is prepared by any one of claims 1 to 8.

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