A graphite film based on a high thermal conductivity and high carbon residue aromatic heterocyclic polymer and its preparation method

Abstract

This invention relates to the field of thermally conductive graphite materials technology, specifically disclosing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film and its preparation method. The invention provides a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film, wherein the graphite film is prepared by first obtaining a dry base film using polyarylene oxadiazole as a polymer-based precursor, and then obtaining it through carbonization and graphitization treatments. The polyarylene oxadiazole is prepared by a segmented multi-step polymerization reaction using naphthalenedicarboxylic acid, hydrazine salt, terephthalic acid, and isophthalic acid as raw materials. The resulting graphite film exhibits significantly improved carbon residue and thermal conductivity compared to general organic precursors.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive graphite materials technology, specifically to a high thermal conductivity, high carbon residue, aromatic heterocyclic polymer-based graphite film and its preparation method. Background Technology

[0002] As electronic products become increasingly integrated, complex, miniaturized, and computationally intensive, power dissipation also increases dramatically. Sustained high temperatures can lead to a gradual deterioration in the performance and reliability of electronic products, making heat dissipation a pressing issue. High thermal conductivity graphite film, as a novel two-dimensional material for heat dissipation, is considered one of the most promising high-efficiency thermal management composite material reinforcements due to its excellent thermal shock resistance, low resistivity, high modulus, corrosion resistance, and especially its high thermal conductivity, low coefficient of thermal expansion, and low density. It is a crucial material for overcoming the heat dissipation challenge in electronic devices during the 5G era.

[0003] The current methods for preparing graphite films include: expanded graphite calendering, which is simple, inexpensive, and does not require high temperature and pressure, and can be mass-produced, but the resulting graphite films have low strength, many defects, and low thermal conductivity; reduction of graphite oxide, which has problems such as complex process, low yield, and poor performance of the obtained graphite films; and CVD method, which is costly and not conducive to large-scale industrial production.

[0004] In recent years, graphitization of polymer-based organic precursors has attracted widespread attention as a novel method for preparing graphite films. Its advantages lie in the low cost of the organic precursors and the high performance of the resulting films, such as polyimide (PI) and polyarylene diazole (POD). For example, patent application number 202410127138.1 discloses a graphite film prepared from an azo compound-doped modified polyarylene diazole precursor, which improves the thermal conductivity of the POD precursor. Meanwhile, patent application number 202310817704.7 addresses the issue of partial powder shedding in graphite films by selecting appropriate monomers. However, improvements are still needed in aspects such as residual carbon value and thermal conductivity. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a high thermal conductivity and high residual carbon aromatic heterocyclic polymer-based graphite film and its preparation method. A dry base film is prepared by using polyarylene oxadiazole as a fused-ring aromatic heterocyclic polymer-based precursor, and then a graphite film is obtained through carbonization and graphitization treatments. The resulting graphite film exhibits significantly improved residual carbon value and thermal conductivity compared to general organic precursors.

[0006] The technical solution of the present invention:

[0007] The first technical problem to be solved by the present invention is to provide a graphite film based on a high thermal conductivity and high carbon residue of aromatic heterocyclic polymers. The graphite film is prepared by first obtaining a dry base film by using polyarylene oxadiazole as a fused-ring aromatic heterocyclic polymer precursor, and then obtaining it through carbonization and graphitization treatment.

[0008] The polyarylene oxadiazole is prepared by a multi-step polymerization reaction using naphthalenecarboxylic acid, hydrazine salt, terephthalic acid, and isophthalic acid as raw materials: first, naphthalenecarboxylic acid and hydrazine salt are subjected to a polycondensation reaction in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid at 70-90 °C; then, terephthalic acid and isophthalic acid are added, dissolved, and the resulting mixture is reacted at 100-120 °C for 2-3 h; then, it is reacted at 120-160 °C for 3-5 h; finally, benzoic acid is added to terminate the reaction.

[0009] Furthermore, the density of the high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film is 1.99-2.11 g / m³. 3 The thickness is 40±5.

[0010] Furthermore, the molar ratio of naphthaleneacetic acid to the total molar ratio of terephthalic acid and isophthalic acid is 0.01-0.08:1; the molar ratio of hydrazine salt to the total molar ratio of naphthaleneacetic acid, terephthalic acid and isophthalic acid is 1.02-1.15:1; and the molar ratio of terephthalic acid to isophthalic acid is 7:2-4.

[0011] Furthermore, the molar ratio of naphthalic acid to the total molar ratio of terephthalic acid and isophthalic acid is 0.04:1.

[0012] Furthermore, the molar ratio of terephthalic acid to isophthalic acid is 7:3.

[0013] Further, specifically, polyarylene oxadiazole is prepared by the following method: naphthalic acid and hydrazine salt are subjected to a polycondensation reaction in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid at 70-90 °C for 0.5-2 h, then terephthalic acid and isophthalic acid are added, and the reaction is carried out at 70-900 °C for 0.5-2 h to obtain a mixed solution; the mixed solution is further reacted at 100-120 °C for 2-3 h, then reacted at 120-160 °C for 3-5 h, benzoic acid is added to terminate the reaction, and the mixture is degassed under vacuum for 0.5-1 h to obtain polyarylene oxadiazole.

[0014] Furthermore, the decomposition temperature of polyarylexadiazole is 450-500 ℃.

[0015] Furthermore, naphthalenedicarboxylic acid is 2,6-naphthalenedicarboxylic acid.

[0016] Furthermore, the hydrazine salt is hydrazine sulfate.

[0017] The key to the preparation of polyarylene oxadiazole in this invention lies in the use of a segmented, multi-step polymerization method to control the hydrazideation reaction and obtain more and more uniform fused cyclic structures: First, naphthalene dicarboxylic acid is reacted with hydrazine salt to form a prepolymer structure, avoiding the situation where naphthalene dicarboxylic acid, as a minority of added monomers, has reduced effective collisions with hydrazine salt, thus preventing its reaction with sulfuric acid and subsequent polymerization failure. Then, terephthalic acid and isophthalic acid are added and kept at a constant temperature for thorough mixing, avoiding uneven molecular weight distribution caused by vigorous polymerization. Finally, the reaction is further carried out at a low temperature, and the effective prepolymerization deepens the degree of hydrazideation, which is beneficial for the subsequent aromatic heterocyclization reaction.

[0018] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned high thermal conductivity and high carbon residue aromatic heterocyclic polymer-based graphite film, comprising the following steps: preparing a dry base film from polyarylene oxadiazole, and then obtaining a high thermal conductivity and high carbon residue aromatic heterocyclic polymer-based graphite film through carbonization and graphitization treatment.

[0019] Furthermore, the preparation method of high thermal conductivity and high carbon residue aromatic heterocyclic polymer-based graphite film specifically includes the following steps:

[0020] (1) First, a polyarylene oxadiazole stock solution is prepared, then the polyarylene oxadiazole stock solution is extruded to form a wet film, and then the wet film is used to prepare a dry base film.

[0021] The polyarylene oxadiazole stock solution was prepared by the following method: Naphthalene dicarboxylic acid and hydrazine salt were subjected to a polycondensation reaction at 70-90 °C for 0.5-2 h in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid. Then, terephthalic acid and isophthalic acid were added, and the solution was dissolved and reacted at 70-90 °C for 0.5-2 h to obtain a mixed solution. The mixed solution was further reacted at 100-120 °C for 2-3 h, followed by a reaction at 120-160 °C for 3-5 h. Benzoic acid was added to terminate the reaction, and the solution was degassed under vacuum for 0.5-1 h to obtain the polyarylene oxadiazole stock solution.

[0022] (2) The dry base film is subjected to carbonization and graphitization to obtain a high thermal conductivity and high residual carbon aromatic heterocyclic polymer-based graphite film.

[0023] Further, in step (1), the molar addition of naphthalenecarboxylic acid is: the total molar addition of terephthalic acid and isophthalic acid = 0.01-0.08:1; the molar addition of hydrazine salt is: the total molar addition of naphthalenecarboxylic acid, terephthalic acid and isophthalic acid = 1.02-1.15:1; the molar ratio of terephthalic acid and isophthalic acid is 7:2-4.

[0024] Furthermore, in step (1), the naphthalene carboxylic acid is 2,6-naphthalene carboxylic acid.

[0025] Furthermore, the hydrazine salt is hydrazine sulfate;

[0026] Further, in step (1), the polyarylexadiazole stock solution is extruded at 60-90 ℃ to form a wet film in a 40-60 vt% sulfuric acid coagulation bath, and then annealed at 50-80 ℃ for 10-60 min to obtain a dry base film.

[0027] Further, in step (2), the carbonization process is as follows: under the protection of inert gas, the dry base film is heated from room temperature to 400-500 ℃ at a heating rate of 2-5 ℃ / min and held for 0.5-2 h. Then the heating rate is reduced to 0.5-2 ℃ / min and the temperature is increased to 500-600 ℃ and held for 0.5-2 h. Then the heating rate is increased to 2-5 ℃ / min and the temperature is increased to 1200-1500 ℃ and held for 0.5-5 h.

[0028] Further, in step (2), the graphitization process is as follows: heat to 2200-2300 ℃ at a heating rate of 3-10 ℃ / min, hold for 0.5-2 h, then reduce the heating rate to 0.5-2 ℃ / min and heat to 2400-2500 ℃, hold for 0.5-2 h; then increase the heating rate to 3-10 ℃ / min and heat to 2600-3000 ℃ and hold for 0.5-2 h, and then cool naturally to room temperature.

[0029] The present invention has the following beneficial effects:

[0030] This invention employs a segmented, multi-step polymerization method to completely polymerize the introduced third monomer, naphthalenedicarboxylic acid, and achieves successful film formation. The resulting graphite film exhibits significantly improved thermal conductivity, reaching 1800 W / (mK), a 24.4% increase compared to graphite films prepared using a precursor without naphthalenedicarboxylic acid. The highest residual mass fraction after thermal weight loss at 800 °C is 53.5%, representing an improvement of up to 7.8% compared to the precursor without naphthalenedicarboxylic acid. After graphitization at 3000 °C, the residual mass fraction of the precursor with naphthalenedicarboxylic acid is 40.1%, representing an improvement of up to 9.4% compared to the precursor without naphthalenedicarboxylic acid. Attached Figure Description

[0031] Figure 1 The infrared spectrum of the product obtained in Example 1;

[0032] Figure 2 The thermal conductivity and thermal diffusivity of the products obtained in Comparative Example 1, Comparative Example 5, and Examples 1-4 are shown.

[0033] Figure 3 The thermogravimetric curves of the products obtained in Comparative Example 1, Comparative Example 5, and Examples 1-4 at 800°C;

[0034] Figure 4This is a schematic diagram showing the change in mass percentage of the products obtained in Example 1 and Comparative Example 1 from room temperature (25°C) to graphitization (3000°C). Detailed Implementation

[0035] This invention proposes a method for preparing a graphite film based on a high thermal conductivity and high carbon residue aromatic heterocyclic polymer. The method employs a segmented, multi-step polymerization process to polymerize naphthalic acid (as a third monomer) into a poly(aryloxadiazole) stock solution containing terephthalic acid and isophthalic acid. The stock solution is then extruded, coated, and gradient-solidified before drying to obtain a dry base film. This dry base film is then carbonized and graphitized. Finally, it is rolled and statically pressed to obtain the graphite film.

[0036] The preparation method specifically includes the following steps:

[0037] (1) First, a polyarylene oxadiazole stock solution is prepared, then the polyarylene oxadiazole stock solution is extruded to form a wet film, and then the wet film is used to prepare a dry base film.

[0038] The polyaryl oxadiazole stock solution was prepared by the following method: Naphthalenedicarboxylic acid and hydrazine salt were subjected to a polycondensation reaction at 70-90 °C for 0.5-2 h in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid. Then, terephthalic acid and isophthalic acid were added, and the solution was dissolved and reacted at 70-90 °C for 0.5-2 h to obtain a mixed solution. The mixed solution was further reacted at 100-120 °C for 2-3 h, followed by a reaction at 120-160 °C for 3-5 h. Benzoic acid was added to terminate the reaction, and the solution was degassed under vacuum for 0.5-1 h. h, to obtain polyaryloxadiazole stock solution; the molar addition of naphthalenecarboxylic acid: the total molar addition of terephthalic acid and isophthalic acid = 0.01-0.08:1; the molar addition of hydrazine salt: the total molar addition of naphthalenecarboxylic acid, terephthalic acid and isophthalic acid = 1.02-1.15:1; the molar ratio of terephthalic acid and isophthalic acid is 7:2-4;

[0039] (2) The dry base film is subjected to carbonization and graphitization treatment, and then rolled and statically pressed at 15-20 MPa for 5-30 min to obtain a high thermal conductivity and high residual carbon aromatic heterocyclic polymer-based graphite film.

[0040] The carbonization process is as follows: Under inert gas protection, the dry base film is heated from room temperature to 400-500 ℃ at a heating rate of 2-5 ℃ / min and held for 0.5-2 h. Then, the heating rate is reduced to 0.5-2 ℃ / min and the temperature is increased to 500-600 ℃ and held for 0.5-2 h. The heating rate is then increased to 2-5 ℃ / min and the temperature is increased to 1200-1500 ℃ and held for 0.5-5 h.

[0041] The graphitization process is as follows: heat to 2200-2300 ℃ at a heating rate of 3-10 ℃ / min, hold for 0.5-2 h, then reduce the heating rate to 0.5-2 ℃ / min and heat to 2400-2500 ℃, hold for 0.5-2 h; then increase the heating rate to 3-10 ℃ / min and heat to 2600-3000 ℃ and hold for 0.5-2 h, then allow to cool naturally to room temperature.

[0042] In this invention, naphthalene dicarboxylic acid, as a polycyclic aromatic hydrocarbon, provides a good graphite microcrystal growth framework for the POD precursor during carbonization and graphitization, reducing the generation of defects, improving the conjugated structure, and greatly enhancing thermal conductivity. At the same time, due to the reduction of defects and the increase of the conjugated structure, the residual mass of thermal weight loss is further improved, which has good economic benefits for production.

[0043] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0044] Example 1

[0045] A high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film is prepared by the following steps:

[0046] (1) Synthesis of the stock solution: 4% (specifically, a molar ratio of (naphthalic acid) / (terephthalic acid + isophthalic acid)) (1.03 g) of 2,6-naphthalic acid and 17.05 g of hydrazine sulfate (N2H4·H2SO4) were subjected to a polycondensation reaction at 80 °C for 1 h in a mixed solution of 55 mL of fuming sulfuric acid and 75 mL of concentrated sulfuric acid. Then, terephthalic acid (13.3 g) and isophthalic acid (5.7 g) with a molar ratio of 7:3 were added, and the solution was dissolved and reacted at 80 °C for 1 h to obtain a mixed solution. The mixed solution was reacted at 100 °C for 2 h, and then reacted at 120 °C for 3 h. 1.45 g of benzoic acid was added to terminate the reaction, and the solution was degassed under vacuum for 0.5 h to obtain the polyarylene oxadiazole stock solution.

[0047] (2) Preparation of dry base film: The polyarylene oxadiazole stock solution was extruded at 80 °C into a 50 vt% sulfuric acid coagulation bath (concentrated sulfuric acid → water) to form a wet film, and then annealed at 60 °C for 40 min to obtain a dry base film;

[0048] (3) Carbonization treatment: Under the protection of inert gas, the dry base film was heated from room temperature to 400 ℃ at a heating rate of 2.5 ℃ / min and held for 0.5 h. Then the heating rate was reduced to 1 ℃ / min and the temperature was increased to 600 ℃ and held for 0.5 h. Then the heating rate was increased to 2.5 ℃ / min and the temperature was increased to 1400 ℃ and held for 0.5 h.

[0049] (4) Graphitization treatment: The carbon film was heated to 2200 ℃ at a heating rate of 5 ℃ / min and held for 0.5 h. Then the heating rate was reduced to 1 ℃ / min and heated to 2500 ℃ and held for 0.5 h. Then the heating rate was increased to 5 ℃ / min and heated to 3000 ℃ and held for 1 h. Then it was naturally cooled to room temperature.

[0050] (5) Post-processing: After the graphite film is rolled, it is statically pressed at 20 MPa for 30 min to obtain a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film. Its infrared spectrum is shown in the figure. Figure 1 As shown.

[0051] Example 2

[0052] Example 2 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 2% (0.52 g) of 2,6-naphthalenedicarboxylic acid.

[0053] Example 3

[0054] Example 3 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 6% (1.55 g) of 2,6-naphthalenedicarboxylic acid.

[0055] Example 4

[0056] Example 4 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 8% (2.06 g) of 2,6-naphthalenedicarboxylic acid.

[0057] Comparative Example 1

[0058] The preparation method of Comparative Example 1 is the same as that of Example 1, except that 2,6-naphthalenedicarboxylic acid is not added in the synthesis of the original solution in step (1); the specific steps of step (1) are as follows:

[0059] Terephthalic acid (13.3 g), isophthalic acid (5.7 g), and 17.05 g hydrazine sulfate in a molar ratio of 7:3 were dissolved in a mixed solution of 55 mL fuming sulfuric acid and 75 mL concentrated sulfuric acid at 80 °C and subjected to a polycondensation reaction for 1 h to obtain a mixed solution. The mixed solution was further reacted at 100 °C for 2 h, followed by a reaction at 120 °C for 3 h. The reaction was terminated by adding 1.45 g benzoic acid and degassing under vacuum for 0.5 h to obtain a polyarylene oxadiazole stock solution.

[0060] Comparative Example 2

[0061] Comparative Example 2 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 4% (1.15 g) of 4,4'-biphenyldicarboxylic acid.

[0062] Comparative Example 3

[0063] A graphite film, the preparation method of which includes the following steps:

[0064] (1) 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid, 17.05 g of hydrazine sulfate, 13.3 g of terephthalic acid and 5.7 g of isophthalic acid in a molar ratio of 7:3 were subjected to a polycondensation reaction at 80 °C for 0.5 h in a mixed solution of 55 mL of fuming sulfuric acid and 75 mL of concentrated sulfuric acid to obtain a mixed solution; the mixed solution was further reacted at 120 °C for 3 h, 1.45 g of benzoic acid was added to terminate the reaction, and the solution was degassed under vacuum for 0.5 h to obtain polyarylene oxadiazole stock solution;

[0065] (2) The poly(aryloxadiazole) stock solution was extruded at 80 °C into a 50 vt% sulfuric acid coagulation bath (concentrated sulfuric acid → water) to form a wet film. At this time, it was found that the wet film was not completely transparent and obvious phase separation occurred. The wet film was annealed at 60 °C for 40 min, but a dry base film could not be obtained. The film underwent severe shrinkage and breakage.

[0066] Comparative Example 4

[0067] Comparative Example 4 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 4% (1.03 g) of 1,4-naphthalenedicarboxylic acid.

[0068] Comparative Example 5

[0069] Comparative Example 5 was prepared in the same way as Example 1, except that 4% (1.03 g) of 2,6-naphthalenedicarboxylic acid in Example 1 was replaced with 10% (2.58 g) of 2,6-naphthalenedicarboxylic acid.

[0070] Test example

[0071] The thermal diffusivity of the products obtained in Examples 1-4 and Comparative Examples 1-5 was tested using a Netzsch LFA467 analyzer. The test temperature was set at room temperature (25 °C), and the test sample was a circular disc with a diameter of 2.5 cm. Using a Netzsch TG209F1 thermal analyzer (Germany), the membrane was cut into pieces, and 5-10 mg was taken for heat resistance testing in an N2 environment. The heating rate was 5 °C / min, and the test temperature range was 45-800 °C. The test results are shown below. Figure 2 and Figure 3 As shown in Table 1. The products obtained from Comparative Example 2 and Comparative Example 4 were also subjected to the same tests. The results are shown in Table 1.

[0072] in, Figure 2 and Figure 3 In the comparison, 0%, 2%, 4%, 6%, 8% and 10% correspond to Comparative Example 1, Example 2, Example 1, Example 3, Example 4 and Comparative Example 5, respectively.

[0073] Table 1 Performance statistics of products from each embodiment and comparative example

[0074] Serial Number Thermal conductivity (W / (mK)) <![CDATA[Density (g / cm 3 ).]]> Thickness (μm) Example 1 1800 2.11 40±5 Example 2 1590 2.08 40±5 Example 3 1650 2.07 40±5 Example 4 1570 2.02 40±5 Comparative Example 1 1447 1.99 40±5 Comparative Example 2 1366 1.96 40±5 Comparative Example 3 — — — Comparative Example 4 1190 1.92 40±5 Comparative Example 5 1335 1.99 40±5

[0075] The results above show that the thermal conductivity of the product obtained in Example 1 reaches 1800 W / (mK), and the weight loss at 800℃ is 9.4% higher than that of the sample without 2,6-naphthalenedicarboxylic acid (Comparative Example 1), reaching 53.5%. The thermal conductivity of the product obtained in Example 2 is 1590 W / (mK), and the weight loss at 800℃ is 49.6%. The thermal conductivity of the product obtained in Example 3 is 1650 W / (mK), and the weight loss at 800℃ is 50.2%. The thermal conductivity of the product obtained in Example 4 is 1570 W / (mK), and the weight loss at 800℃ is 47.7%. The thermal conductivity of the product obtained in Comparative Example 1 is only 1447 W / (mK), lower than the 1800 W / (mK) of Example 1 of this invention, and the weight loss at 800℃ is 45.7%. The thermal conductivity of the product obtained in Comparative Example 2 was 1366 W / (mK); the thermal conductivity of the product obtained in Comparative Example 4 was 1190 W / (mK), which was much lower than the 1800 W / (mK) of Example 1 of the present invention; the thermal conductivity of the product obtained in Comparative Example 5 was 1335 W / (mK), and the thermal weight loss at 800 °C was 46.9%.

[0076] Meanwhile, the mass percentage change of the products obtained in Example 1 and Comparative Example 1 from room temperature (25°C) to graphitization (3000°C) was obtained, and the results are as follows: Figure 4 As shown. Among them, Figure 4 In the figures, 4% and 0% correspond to Example 1 and Comparative Example 1, respectively.

[0077] Depend on Figure 4It can be seen that the residual carbon values ​​of the samples at 800 ℃, 1400 ℃, 2500 ℃ and 3000 ℃ were compared. It can be found that after graphitization, the residual carbon of the sample with 4% naphthalene carboxylic acid added increased by 9.4% compared with the sample without naphthalene carboxylic acid.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a graphite film based on a high thermal conductivity and high carbon residue aromatic heterocyclic polymer, characterized in that, The preparation method is as follows: a dry base film is first prepared by using polyarylene oxadiazole as a polymer-based precursor, and then the graphite film is prepared by carbonization and graphitization. The polyarylene diazole is prepared by a multi-step polymerization reaction using naphthalenedicarboxylic acid, hydrazine salt, terephthalic acid, and isophthalic acid as raw materials. First, naphthalenedicarboxylic acid and hydrazine salt undergo a condensation reaction in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid at 70-90 °C. Then, terephthalic acid and isophthalic acid are added, dissolved, and the resulting mixture is reacted at 100-120 °C for 2-3 h. The reaction is then carried out at 120-160 °C for 3-5 h. Finally, benzoic acid is added to terminate the reaction. The molar ratio of naphthalenedicarboxylic acid to the total molar ratio of terephthalic acid and isophthalic acid is 0.01-0.08:1; the molar ratio of hydrazine salt to the total molar ratio of naphthalenedicarboxylic acid, terephthalic acid, and isophthalic acid is 1.02-1.15:1; the molar ratio of terephthalic acid to isophthalic acid is 7:2-4; and the naphthalenedicarboxylic acid is 2,6-naphthalenedicarboxylic acid.

2. The method for preparing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film as described in claim 1, characterized in that, The decomposition temperature of the polyarylene oxadiazole is 450-500 ℃; Alternatively, the hydrazine salt is hydrazine sulfate.

3. The method for preparing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film as described in claim 1, characterized in that, The preparation method includes the following steps: (1) First, a polyarylene oxadiazole stock solution is prepared, then the polyarylene oxadiazole stock solution is extruded to form a wet film, and then the wet film is used to prepare a dry base film. The polyarylene oxadiazole stock solution is prepared by the following method: Naphthalene dicarboxylic acid and hydrazine salt are subjected to a polycondensation reaction in a mixed solution of fuming sulfuric acid and concentrated sulfuric acid at 70-90 °C for 0.5-2 h. Then, terephthalic acid and isophthalic acid are added, and the solution is dissolved and reacted at 70-90 °C for 0.5-2 h to obtain a mixed solution. The mixed solution is further reacted at 100-120 °C for 2-3 h, followed by a reaction at 120-160 °C for 3-5 h. Benzoic acid is added to terminate the reaction, and the solution is degassed under vacuum for 0.5-1 h to obtain the polyarylene oxadiazole stock solution. (2) The dry base film is subjected to carbonization and graphitization to obtain a high thermal conductivity and high residual carbon aromatic heterocyclic polymer-based graphite film.

4. The method for preparing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film as described in claim 3, characterized in that, In step (1), the polyarylexadiazole stock solution is extruded at 60-90 ℃ to form a wet film in a 40-60 vt% sulfuric acid coagulation bath, and then annealed at 50-80 ℃ for 10-60 min to obtain a dry base film.

5. The method for preparing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film as described in claim 3, characterized in that, In step (2), the carbonization process is as follows: under the protection of inert gas, the dry base film is heated from room temperature to 400-500 ℃ at a heating rate of 2-5 ℃ / min and held for 0.5-2 h. Then the heating rate is reduced to 0.5-2 ℃ / min and the temperature is increased to 500-600 ℃ and held for 0.5-2 h. Then the heating rate is increased to 2-5 ℃ / min and the temperature is increased to 1200-1500 ℃ and held for 0.5-5 h.

6. The method for preparing a high thermal conductivity, high carbon residue aromatic heterocyclic polymer-based graphite film as described in claim 3, characterized in that, In step (2), the graphitization process is as follows: heat to 2200-2300 ℃ at a heating rate of 3-10 ℃ / min, hold for 0.5-2 h, then reduce the heating rate to 0.5-2 ℃ / min and heat to 2400-2500 ℃, hold for 0.5-2 h; then increase the heating rate to 3-10 ℃ / min and heat to 2600-3000 ℃ and hold for 0.5-2 h, and then cool naturally to room temperature.

7. A graphite film based on a high thermal conductivity and high carbon residue aromatic heterocyclic polymer, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

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