High-thermal-conductivity radiation heat dissipation graphite film and preparation method thereof

Abstract

The application discloses a high-thermal-conductivity radiation heat dissipation graphite film and a preparation method thereof. The high-thermal-conductivity radiation heat dissipation graphite film is prepared by using a modified polyamide acid solution, a nitric acid solution and graphene oxide as raw materials, high-temperature imidization, preparation of a composite film, high-temperature carbonization and graphitization of the composite film, functionalization of the composite graphite film, immersion of the functionalized graphite film in an ethyl acrylate and potassium persulfate composite liquid, and high-temperature treatment. In the high-temperature carbonization process, N elements in the composite film produce nitrogen gas, so that the prepared composite graphite film contains small holes on the surface. Ethyl acrylate enters the holes and forms polyacrylate with double bonds on the functionalized graphite film in the holes and on the surface, thereby increasing the mechanical properties of the graphite film. In the high-temperature carbonization process, a structure of carbon particles coating silver can be formed, and the thermal conductivity and mechanical properties of the graphite film are further improved.

Description

Technical Field

[0001] This invention relates to the field of graphite film preparation technology, specifically to a high thermal conductivity radiation-dissipating graphite film and its preparation method. Background Technology

[0002] With the rapid development of 5G technology, electronic devices such as smartphones, tablets, and laptops are becoming increasingly lightweight, compact, and efficient. During their high-frequency, high-speed operation, they generate and accumulate significant amounts of heat. If this heat cannot be dissipated in time, it will severely impact the operational stability and lifespan of electronic components. Therefore, appropriate thermal solutions and specific heat dissipation materials are essential, especially lightweight materials with high thermal conductivity. Traditional metal heat dissipation materials, due to their high density, high coefficient of thermal expansion, and low thermal conductivity, are struggling to meet increasingly stringent heat dissipation requirements. Graphite, with its lightweight, high thermal conductivity, and ease of processing, has become the preferred heat dissipation material. However, current graphite films exhibit low interfacial thermal conductivity and insufficient mechanical properties, making them prone to breakage and affecting normal operation. Summary of the Invention

[0003] The purpose of this invention is to provide a high thermal conductivity radiation heat dissipation graphite film and its preparation method, which solves the problems of low thermal conductivity and poor mechanical properties of graphite films at present.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing a high thermal conductivity, radiation-dissipating graphite film includes the following steps:

[0006] Step A1: Mix modified polyamic acid solution, silver nitrate aqueous solution and graphene oxide, and sonicate at a frequency of 20-30kHz and a temperature of 40-50℃ for 30-40 minutes. Then coat the mixture onto a substrate and heat-treat at a temperature of 160-170℃ for 3-4 hours. Next, heat the mixture to 280-300℃ and heat-treat for 2-3 hours. Finally, remove the mixture from the substrate to obtain a composite film.

[0007] Step A2: Place the composite film in a high-temperature carbonization furnace. Under the conditions of 600-650℃ and argon to hydrogen volume ratio of 95:5, hold for 30-40 minutes. Then, under the condition of heating rate of 2℃ / min, heat to 1000℃ and hold for 1-1.5 hours. Then, heat to 1200℃ and hold for 1-1.5 hours to obtain a carbonized film. Place the carbonized film in a high-temperature graphitization furnace. Under the conditions of heating rate of 5℃ and argon atmosphere, heat to 2300℃ and hold for 1-1.5 hours. Then, heat to 2600℃ and hold for 1-1.5 hours to obtain a composite graphite film.

[0008] Step A3: Immerse the composite graphite film in dilute sulfuric acid and sonicate it for 2-3 hours at a frequency of 30-40kHz and a temperature of 40-50℃. Remove and dry the film, then place it in DMF, add KH550, and sonicate it for 3-5 minutes at a temperature of 60-70℃. Add deionized water and sonicate for 10-15 minutes. Add 4-vinylbenzaldehyde and sonicate for 1-1.5 hours to obtain a functionalized graphite film. Mix ethyl acrylate and potassium persulfate evenly, immerse the functionalized graphite film in the mixture for 30-40 minutes, remove it until no more liquid drips, and keep it at a temperature of 60-70℃ for 2-3 hours to obtain a high thermal conductivity radiation heat dissipation graphite film.

[0009] Furthermore, the ratio of the modified polyamic acid solution, silver nitrate aqueous solution, and graphene oxide used in step A1 is 20 mL: 10 mL: 3 g, and the mass fraction of the silver nitrate aqueous solution is 1%.

[0010] Furthermore, the mass fraction of the dilute sulfuric acid mentioned in step A3 is 60%, the amount of KH550 added is 1% of the volume of DMF, the amount of deionized water added is 2% of the volume of DMF, the molar ratio of 4-vinylbenzaldehyde and KH550 is 1:1, and the amount of potassium persulfate is 5‰ of the mass of ethyl acrylate.

[0011] Furthermore, the modified polyamic acid solution is prepared by the following steps:

[0012] Step B1: Mix 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, triethylamine and DMF, and react for 3-5 hours at a speed of 200-300 r / min and a temperature of 25-30℃ to obtain intermediate 1. Mix zinc powder, acetic acid, deionized water and DMF, and stir and add intermediate 1 at a speed of 150-200 r / min and a temperature of 80-85℃, and react for 1-1.5 hours. Adjust the pH to alkaline to obtain the modified monomer.

[0013] Step B2: The modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic acid dianhydride and DMF are mixed and reacted at a speed of 1200-1500 r / min and a temperature of 20-25℃ for 4-6 h to obtain a polyamic acid solution. 2,6-dibromo-4-pyridinemethanol, itaconic acid, p-toluenesulfonic acid and toluene are mixed evenly and reacted at a speed of 200-300 r / min and a temperature of 115-120℃ for 3-5 h to obtain intermediate 2.

[0014] Step B3: Mix intermediate 2, benzimidazole, copper powder, potassium carbonate, potassium hydroxide and DMF evenly, and react for 40-45 h at a speed of 120-150 r / min and a temperature of 155-160℃ to obtain the functional monomer. Mix polyamic acid solution, acrylonitrile, functional monomer, potassium persulfate and isopropanol, and react for 3-5 h at a speed of 200-300 r / min and a temperature of 60-70℃ to obtain the modified polyamic acid solution.

[0015] Furthermore, the molar ratio of 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, and triethylamine in step B1 is 1:2:2.1, and the ratio of zinc powder, acetic acid, deionized water, DMF, and intermediate 1 is 2.5g:2g:20mL:50mL:2g.

[0016] Furthermore, in step B2, the ratio of the modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic dianhydride, and DMF is 1 mol:3 mol:4 mol:1 L, the molar ratio of 2,6-dibromo-4-pyridinemethanol and itaconic acid is 1:1, and the amount of p-toluenesulfonic acid is 1% of the mass of itaconic acid.

[0017] Furthermore, in step B3, the molar ratio of intermediate 2, benzimidazole, copper powder, potassium carbonate, and potassium hydroxide is 5:11:5:5:5; the ratio of polyamic acid solution, acrylonitrile, and functional monomer is 1L:100g:15g; the amount of potassium persulfate is 0.5% of the total mass of acrylonitrile and functional monomer; and the amount of isopropanol is 1% of the total mass of acrylonitrile and functional monomer.

[0018] The beneficial effects of this invention are as follows: This invention discloses a high thermal conductivity radiation-dissipating graphite film made by ultrasonically mixing modified polyamic acid solution, nitric acid solution and graphene oxide as raw materials, coating it on a substrate, removing DMF from the polyamic acid at high temperature, and then imidizing it at high temperature to obtain a composite film. The composite film is then carbonized at high temperature and further graphitized to obtain a composite graphite film. The composite graphite film is then immersed in dilute sulfuric acid to make it contain active hydroxyl groups. The composite graphite film is then treated with KH550 to graft amino groups onto the surface. 4-vinylbenzaldehyde is then added, causing the aldehyde groups on 4-vinylbenzaldehyde to react with the amino groups on the surface to form imino groups, thus obtaining a functionalized graphite film. The functionalized graphite film is then immersed in a composite solution of ethyl acrylate and potassium persulfate. Under high temperature conditions, the double bonds remaining on the surface of the functionalized graphite film will polymerize with the double bonds on the ethyl acrylate to obtain a high thermal conductivity radiation-dissipating graphite film.

[0019] The modified polyamic acid solution was reacted with 4,4'-dibromo-2,2'-dinitrobiphenyl and allyl alcohol as raw materials, causing the bromine atom on 4,4'-dibromo-2,2'-dinitrobiphenyl to react with the hydroxyl group on allyl alcohol to obtain intermediate 1. Intermediate 1 was reduced with zinc powder, causing the nitro group on intermediate 1 to be converted to an amino group, to obtain the modified monomer. The modified monomer, 4,4'-diaminodiphenyl ether and benzophenone tetracarboxylic acid dianhydride were reacted to form polyamic acid. 2,6-dibromo-4-pyridinemethanol and itaconic acid were reacted, causing the hydroxyl group on 2,6-dibromo-4-pyridinemethanol to esterify with the carboxyl group on itaconic acid to obtain intermediate 2. Intermediate 2 was reacted with benzimidazole, causing the bromine atom site on intermediate 2 to react with the secondary amine on benzimidazole. The polyamic acid solution, acrylonitrile and functional monomer were reacted to form polyacrylonitrile molecular chains on the side chains of the polyamic acid molecule, finally obtaining the modified polyamic acid solution.

[0020] During the high-temperature carbonization process, nitrogen gas is generated from nitrogen in the composite film, resulting in tiny pores on the surface of the prepared composite graphite film. When the functionalized graphite film is immersed in a composite solution of ethyl acrylate and potassium persulfate, ethyl acrylate enters the pores and forms polyacrylate with the double bonds on the functionalized graphite film in the pores and on the surface, thereby increasing the mechanical properties of the graphite film. At the same time, the sidewalls of the pores can form stable thermal conductivity pathways, thus ensuring the thermal conductivity of the graphite film. Furthermore, the modified polyacrylic acid has a comb-like molecular chain, which can form a structure of carbon particles coated with silver during the high-temperature carbonization process, further improving the thermal conductivity and mechanical properties of the graphite film. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: A method for preparing a high thermal conductivity, radiation-dissipating graphite film, specifically including the following steps:

[0023] Step A1: Mix the modified polyamic acid solution, silver nitrate aqueous solution and graphene oxide, and sonicate at a frequency of 20kHz and a temperature of 40℃ for 30 minutes. Then coat the mixture onto a substrate, heat it at 160℃ for 3 hours, then heat it to 280℃ and heat it for 2 hours. Finally, remove the mixture from the substrate to obtain the composite film.

[0024] Step A2: Place the composite film in a high-temperature carbonization furnace. Under the conditions of 600℃ and argon to hydrogen volume ratio of 95:5, hold for 30 min. Then, under the conditions of heating rate of 2℃ / min, heat to 1000℃ and hold for 1 h. Then, heat to 1200℃ and hold for 1 h to obtain a carbonized film. Place the carbonized film in a high-temperature graphitization furnace. Under the conditions of heating rate of 5℃ and argon atmosphere, heat to 2300℃ and hold for 1 h. Then, heat to 2600℃ and hold for 1 h to obtain a composite graphite film.

[0025] Step A3: Immerse the composite graphite film in dilute sulfuric acid and sonicate it for 2 hours at a frequency of 30 kHz and a temperature of 40 ℃. Remove and dry the film, then place it in DMF, add KH550, and sonicate it for 3 minutes at a temperature of 60 ℃. Add deionized water and sonicate for 10 minutes. Add 4-vinylbenzaldehyde and sonicate for 1 hour to obtain a functionalized graphite film. Mix ethyl acrylate and potassium persulfate evenly, immerse the functionalized graphite film in the mixture, and immerse it for 30 minutes. Remove the film until no more liquid drips, and keep it at a temperature of 60 ℃ for 2 hours to obtain a high thermal conductivity radiation heat dissipation graphite film.

[0026] The ratio of the modified polyamic acid solution, silver nitrate aqueous solution, and graphene oxide used in step A1 is 20 mL: 10 mL: 3 g, and the mass fraction of the silver nitrate aqueous solution is 1%.

[0027] The mass fraction of the dilute sulfuric acid mentioned in step A3 is 60%, the amount of KH550 added is 1% of the volume of DMF, the amount of deionized water added is 2% of the volume of DMF, the molar ratio of 4-vinylbenzaldehyde and KH550 is 1:1, and the amount of potassium persulfate is 5‰ of the mass of ethyl acrylate.

[0028] The modified polyamic acid solution is prepared by the following steps:

[0029] Step B1: 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, triethylamine and DMF were mixed and reacted for 3 hours at a speed of 200 r / min and a temperature of 25°C to obtain intermediate 1. Zinc powder, acetic acid, deionized water and DMF were mixed and stirred at a speed of 150 r / min and a temperature of 80°C, and intermediate 1 was added. The reaction was carried out for 1 hour, and the pH was adjusted to alkaline to obtain the modified monomer.

[0030] Step B2: The modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic acid dianhydride and DMF are mixed and reacted for 4 h at a speed of 1200 r / min and a temperature of 20 °C to obtain a polyamic acid solution. 2,6-dibromo-4-pyridinemethanol, itaconic acid, p-toluenesulfonic acid and toluene are mixed evenly and reacted for 3 h at a speed of 200 r / min and a temperature of 115 °C to obtain intermediate 2.

[0031] Step B3: Mix intermediate 2, benzimidazole, copper powder, potassium carbonate, potassium hydroxide and DMF evenly, and react for 40 h at a speed of 120 r / min and a temperature of 155℃ to obtain the functional monomer. Mix polyamic acid solution, acrylonitrile, functional monomer, potassium persulfate and isopropanol, and react for 3 h at a speed of 200 r / min and a temperature of 60℃ to obtain the modified polyamic acid solution.

[0032] The molar ratio of 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol and triethylamine in step B1 is 1:2:2.1, and the ratio of zinc powder, acetic acid, deionized water, DMF and intermediate 1 is 2.5g:2g:20mL:50mL:2g.

[0033] The ratio of the modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic dianhydride and DMF in step B2 is 1 mol:3 mol:4 mol:1 L, the molar ratio of 2,6-dibromo-4-pyridinemethanol and itaconic acid is 1:1, and the amount of p-toluenesulfonic acid is 1% of the mass of itaconic acid.

[0034] The molar ratio of intermediate 2, benzimidazole, copper powder, potassium carbonate and potassium hydroxide mentioned in step B3 is 5:11:5:5:5. The ratio of polyamic acid solution, acrylonitrile and functional monomer is 1L:100g:15g. The amount of potassium persulfate is 0.5% of the total mass of acrylonitrile and functional monomer. The amount of isopropanol is 1% of the total mass of acrylonitrile and functional monomer.

[0035] Example 2: A method for preparing a high thermal conductivity, radiation-dissipating graphite film, specifically including the following steps:

[0036] Step A1: The modified polyamic acid solution, silver nitrate aqueous solution and graphene oxide are mixed and ultrasonically treated for 35 min at a frequency of 25 kHz and a temperature of 45 ℃. The mixture is then coated onto a substrate and kept at a temperature of 165 ℃ for 3.5 h. After that, the temperature is raised to 290 ℃ and kept at a temperature of 2.5 h. The mixture is then removed from the substrate to obtain the composite film.

[0037] Step A2: The composite film is placed in a high-temperature carbonization furnace. Under the conditions of 630℃ and argon to hydrogen volume ratio of 95:5, it is kept at this temperature for 35 minutes. Then, under the condition of a heating rate of 2℃ / min, the temperature is raised to 1000℃ and kept at this temperature for 1.3 hours. The temperature is then raised to 1200℃ and kept at this temperature for 1.3 hours to obtain a carbonized film. The carbonized film is then placed in a high-temperature graphitization furnace. Under the conditions of a heating rate of 5℃ and argon atmosphere, the temperature is raised to 2300℃ and kept at this temperature for 1.3 hours. The temperature is then raised to 2600℃ and kept at this temperature for 1.3 hours to obtain a composite graphite film.

[0038] Step A3: Immerse the composite graphite film in dilute sulfuric acid and sonicate it at 35 kHz and 45 ℃ for 2.5 h. Remove and dry it, then place it in DMF, add KH550, and sonicate it at 65 ℃ for 4 min. Add deionized water and sonicate it for 13 min. Add 4-vinylbenzaldehyde and sonicate it for 1.3 h to obtain a functionalized graphite film. Mix ethyl acrylate and potassium persulfate evenly, immerse the functionalized graphite film in the mixture, and immerse it for 35 min. Remove it until no more liquid drips, and keep it at 65 ℃ for 2 h to obtain a high thermal conductivity radiation heat dissipation graphite film.

[0039] The ratio of the modified polyamic acid solution, silver nitrate aqueous solution, and graphene oxide used in step A1 is 20 mL: 10 mL: 3 g, and the mass fraction of the silver nitrate aqueous solution is 1%.

[0040] The mass fraction of the dilute sulfuric acid mentioned in step A3 is 60%, the amount of KH550 added is 1% of the volume of DMF, the amount of deionized water added is 2% of the volume of DMF, the molar ratio of 4-vinylbenzaldehyde and KH550 is 1:1, and the amount of potassium persulfate is 5‰ of the mass of ethyl acrylate.

[0041] The modified polyamic acid solution is prepared by the following steps:

[0042] Step B1: 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, triethylamine and DMF were mixed and reacted at 200 r / min and 30°C for 4 h to obtain intermediate 1. Zinc powder, acetic acid, deionized water and DMF were mixed and stirred at 150 r / min and 85°C, and intermediate 1 was added. The reaction was carried out for 1.3 h, and the pH was adjusted to alkaline to obtain the modified monomer.

[0043] Step B2: The modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic acid dianhydride and DMF are mixed and reacted for 5 h at a speed of 1200 r / min and a temperature of 25 °C to obtain a polyamic acid solution. 2,6-dibromo-4-pyridinemethanol, itaconic acid, p-toluenesulfonic acid and toluene are mixed evenly and reacted for 4 h at a speed of 200 r / min and a temperature of 120 °C to obtain intermediate 2.

[0044] Step B3: Mix intermediate 2, benzimidazole, copper powder, potassium carbonate, potassium hydroxide and DMF evenly, and react for 40 h at a speed of 120 r / min and a temperature of 160 °C to obtain the functional monomer. Mix polyamic acid solution, acrylonitrile, functional monomer, potassium persulfate and isopropanol, and react for 4 h at a speed of 200 r / min and a temperature of 65 °C to obtain the modified polyamic acid solution.

[0045] The molar ratio of 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol and triethylamine in step B1 is 1:2:2.1, and the ratio of zinc powder, acetic acid, deionized water, DMF and intermediate 1 is 2.5g:2g:20mL:50mL:2g.

[0046] The ratio of the modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic dianhydride and DMF in step B2 is 1 mol:3 mol:4 mol:1 L, the molar ratio of 2,6-dibromo-4-pyridinemethanol and itaconic acid is 1:1, and the amount of p-toluenesulfonic acid is 1% of the mass of itaconic acid.

[0047] The molar ratio of intermediate 2, benzimidazole, copper powder, potassium carbonate and potassium hydroxide mentioned in step B3 is 5:11:5:5:5. The ratio of polyamic acid solution, acrylonitrile and functional monomer is 1L:100g:15g. The amount of potassium persulfate is 0.5% of the total mass of acrylonitrile and functional monomer. The amount of isopropanol is 1% of the total mass of acrylonitrile and functional monomer.

[0048] Example 3: A method for preparing a high thermal conductivity, radiation-dissipating graphite film, specifically including the following steps:

[0049] Step A1: Mix modified polyamic acid solution, silver nitrate aqueous solution and graphene oxide, sonicate at 30 kHz and 50 ℃ for 40 min, coat onto substrate, heat at 170 ℃ for 4 h, heat to 300 ℃ for 3 h, remove from substrate to obtain composite film.

[0050] Step A2: Place the composite film in a high-temperature carbonization furnace. Under the conditions of 650℃ and argon to hydrogen volume ratio of 95:5, hold for 40 min. Then, at a heating rate of 2℃ / min, heat to 1000℃ and hold for 1.5 h. Then, heat to 1200℃ and hold for 1.5 h to obtain a carbonized film. Place the carbonized film in a high-temperature graphitization furnace. Under the conditions of 5℃ heating rate and argon atmosphere, heat to 2300℃ and hold for 1.5 h. Then, heat to 2600℃ and hold for 1.5 h to obtain a composite graphite film.

[0051] Step A3: Immerse the composite graphite film in dilute sulfuric acid and sonicate it for 3 hours at a frequency of 40 kHz and a temperature of 50 ℃. Remove and dry the film, then place it in DMF, add KH550, and sonicate it for 5 minutes at a temperature of 70 ℃. Add deionized water and sonicate for 15 minutes. Add 4-vinylbenzaldehyde and sonicate for 1.5 hours to obtain a functionalized graphite film. Mix ethyl acrylate and potassium persulfate evenly, immerse the functionalized graphite film in the mixture, and immerse it for 40 minutes. Remove the film until no more liquid drips, and keep it at a temperature of 70 ℃ for 3 hours to obtain a high thermal conductivity radiation heat dissipation graphite film.

[0052] The ratio of the modified polyamic acid solution, silver nitrate aqueous solution, and graphene oxide used in step A1 is 20 mL: 10 mL: 3 g, and the mass fraction of the silver nitrate aqueous solution is 1%.

[0053] The mass fraction of the dilute sulfuric acid mentioned in step A3 is 60%, the amount of KH550 added is 1% of the volume of DMF, the amount of deionized water added is 2% of the volume of DMF, the molar ratio of 4-vinylbenzaldehyde and KH550 is 1:1, and the amount of potassium persulfate is 5‰ of the mass of ethyl acrylate.

[0054] The modified polyamic acid solution is prepared by the following steps:

[0055] Step B1: 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, triethylamine and DMF were mixed and reacted at 300 r / min and 30°C for 5 h to obtain intermediate 1. Zinc powder, acetic acid, deionized water and DMF were mixed and stirred at 200 r / min and 85°C, and intermediate 1 was added. The reaction was carried out for 1.5 h, and the pH was adjusted to alkaline to obtain the modified monomer.

[0056] Step B2: The modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic acid dianhydride and DMF are mixed and reacted for 6 h at a speed of 1500 r / min and a temperature of 25 °C to obtain a polyamic acid solution. 2,6-dibromo-4-pyridinemethanol, itaconic acid, p-toluenesulfonic acid and toluene are mixed evenly and reacted for 5 h at a speed of 300 r / min and a temperature of 120 °C to obtain intermediate 2.

[0057] Step B3: Mix intermediate 2, benzimidazole, copper powder, potassium carbonate, potassium hydroxide and DMF evenly, and react for 45 h at a speed of 150 r / min and a temperature of 160 °C to obtain the functional monomer. Mix polyamic acid solution, acrylonitrile, functional monomer, potassium persulfate and isopropanol, and react for 5 h at a speed of 300 r / min and a temperature of 70 °C to obtain the modified polyamic acid solution.

[0058] The molar ratio of 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol and triethylamine in step B1 is 1:2:2.1, and the ratio of zinc powder, acetic acid, deionized water, DMF and intermediate 1 is 2.5g:2g:20mL:50mL:2g.

[0059] The ratio of the modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic dianhydride and DMF in step B2 is 1 mol:3 mol:4 mol:1 L, the molar ratio of 2,6-dibromo-4-pyridinemethanol and itaconic acid is 1:1, and the amount of p-toluenesulfonic acid is 1% of the mass of itaconic acid.

[0060] The molar ratio of intermediate 2, benzimidazole, copper powder, potassium carbonate and potassium hydroxide mentioned in step B3 is 5:11:5:5:5. The ratio of polyamic acid solution, acrylonitrile and functional monomer is 1L:100g:15g. The amount of potassium persulfate is 0.5% of the total mass of acrylonitrile and functional monomer. The amount of isopropanol is 1% of the total mass of acrylonitrile and functional monomer.

[0061] Comparative Example 1: This comparative example does not include silver nitrate aqueous solution, but the other steps are the same as in Example 1.

[0062] Comparative Example 2: Compared with Example 1, this comparative example uses a functionalized graphite film instead of a high thermal conductivity radiation-dissipating graphite film, while the other steps are the same.

[0063] Comparative Example 3: Compared with Example 1, this comparative example uses a polyamic acid solution instead of a modified polyamic acid solution, while the other steps are the same.

[0064] The graphite films prepared in Examples 1-3 and Comparative Examples 1-3 were tested for in-plane thermal conductivity and interlayer thermal conductivity according to GB / T22588-2008. Type 5 specimens were prepared according to GB / T1040.3-2006, with a tensile rate of 50 mm / min. The test results are shown in Table 1 below.

[0065] Table 1

[0066]

[0067] As shown in the table above, this application has excellent thermal conductivity and high mechanical strength.

[0068] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity, radiation-dissipating graphite film, characterized in that: Specifically, the steps include the following: Step A1: After mixing and ultrasonically treating the modified polyamic acid solution, silver nitrate aqueous solution and graphene oxide, the mixture is coated onto a substrate. After heat treatment at 160-170℃ for 3-4 hours, the temperature is raised to 280-300℃ and heat treatment is carried out for 2-3 hours. The mixture is then removed from the substrate to obtain a composite film. Step A2: Place the composite film in a high-temperature carbonization furnace and carbonize it at high temperature to obtain a carbonized film. Place the carbonized film in a high-temperature graphitization furnace and keep it at high temperature to obtain a composite graphite film. Step A3: After immersing the composite graphite film in dilute sulfuric acid and ultrasonically treating it, remove and dry it, then place it in DMF, add KH550, ultrasonically treat it, add deionized water, ultrasonically treat it, add 4-vinylbenzaldehyde, ultrasonically treat it to obtain a functionalized graphite film. Mix ethyl acrylate and potassium persulfate evenly, immerse the functionalized graphite film in it, immerse it until no liquid drips, and keep it at a temperature of 60-70℃ for 2-3 hours to obtain a high thermal conductivity radiation heat dissipation graphite film.

2. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 1, characterized in that: The ratio of the modified polyamic acid solution, silver nitrate aqueous solution, and graphene oxide used in step A1 is 20 mL: 10 mL: 3 g, and the mass fraction of the silver nitrate aqueous solution is 1%.

3. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 1, characterized in that: The mass fraction of the dilute sulfuric acid mentioned in step A3 is 60%, the amount of KH550 added is 1% of the volume of DMF, the amount of deionized water added is 2% of the volume of DMF, and the molar ratio of 4-vinylbenzaldehyde to KH550 is 1:

1.

4. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 1, characterized in that: The modified polyamic acid solution is prepared by the following steps: Step B1: 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol, triethylamine and DMF are mixed and reacted to obtain intermediate 1. Zinc powder, acetic acid, deionized water and DMF are mixed and stirred and added to intermediate 1 to carry out the reaction. The pH is adjusted to alkaline to obtain the modified monomer. Step B2: The modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic acid dianhydride and DMF are mixed and reacted to prepare a polyamic acid solution. 2,6-dibromo-4-pyridinemethanol, itaconic acid, p-toluenesulfonic acid and toluene are mixed and reacted to prepare intermediate 2. Step B3: Mix intermediate 2, benzimidazole, copper powder, potassium carbonate, potassium hydroxide and DMF to prepare a functional monomer. Mix polyamic acid solution, acrylonitrile, functional monomer, potassium persulfate and isopropanol and react to prepare a modified polyamic acid solution.

5. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 4, characterized in that: The molar ratio of 4,4'-dibromo-2,2'-dinitrobiphenyl, allyl alcohol and triethylamine in step B1 is 1:2:2.1, and the ratio of zinc powder, acetic acid, deionized water, DMF and intermediate 1 is 2.5g:2g:20mL:50mL:2g.

6. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 4, characterized in that: The ratio of the modified monomer, 4,4'-diaminodiphenyl ether, benzophenone tetracarboxylic dianhydride and DMF in step B2 is 1 mol:3 mol:4 mol:1 L, and the molar ratio of 2,6-dibromo-4-pyridinemethanol and itaconic acid is 1:

1.

7. The method for preparing a high thermal conductivity, radiation-dissipating graphite film according to claim 4, characterized in that: The molar ratio of intermediate 2, benzimidazole, copper powder, potassium carbonate and potassium hydroxide mentioned in step B3 is 5:11:5:5:5, and the ratio of polyamic acid solution, acrylonitrile and functional monomer is 1L:100g:15g.

8. A high thermal conductivity, radiation-dissipating graphite film, characterized in that: Prepared according to any one of the preparation methods described in claims 1-7.

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