Graphite paper with high heat dissipation and preparation method and application thereof

Abstract

The application belongs to the field of graphite materials, and specifically discloses a graphite paper with high heat dissipation efficiency and a preparation method and application thereof. The graphite paper is prepared from the following raw materials in parts by weight: modified graphite powder 100 parts, carbon black 10-20 parts, talcum powder 5-10 parts, carboxymethyl cellulose 5-10 parts, binder 3-8 parts, nano metal heat-conducting material 2-4 parts, and anti-wear agent 2-3 parts. The modified graphite powder is processed through the following modification steps: 1) crushing flake graphite and passing it through a 200-500 mesh sieve to obtain flake graphite powder; 2) adding 2-4% of multilayer graphene, 1-2% of molybdenum disulfide, 0.5-1% of silicon nitride and 0.2-0.4% of potassium dichromate in the final mass fraction to the flake graphite powder to obtain powder A, and then putting the powder A into an organic solvent for ultrasonic treatment; and 3) filtering the mixed solution after ultrasonic treatment, collecting the solid, and vacuum drying at 300-400 DEG C until the water content is lower than 5% to obtain the modified graphite powder. The graphite paper has good mechanical properties, high heat-conducting capacity, and a safe, simple and pollution-free preparation process.

Description

Technical Field

[0001] This invention belongs to the field of graphite materials, and specifically discloses a high-efficiency heat dissipation graphite paper, its preparation method and application. Background Technology

[0002] With the accelerated upgrading of electronic products and the increasing demand for heat dissipation management in miniaturized, highly integrated, and high-performance electronic devices, a new heat dissipation technology for electronic products has been introduced: a new solution using graphite materials. This novel natural graphite solution utilizes the high heat dissipation efficiency, small footprint, and light weight of graphite paper. It conducts heat uniformly in two directions, eliminating "hot spots" and shielding heat sources and components while improving the performance of consumer electronics. Existing graphite paper is mainly prepared by reacting graphite with strong acid to denature it, followed by calendering. For example, CN201410253642.2 discloses a method for preparing graphite paper. After acid treatment, graphite flakes are processed into graphite worms. After desulfurization, some of the raw materials enter the graphite wire preparation device 4. Under the action of a high-pressure power pump, graphite wires are continuously sprayed out at the nozzle. These graphite wires are sprayed onto graphite paper and / or rolls 7. In coordination with the movement of graphite paper and rolls, a series of oblique or mesh-like graphite wires are formed on graphite paper and rolls. Graphite paper of the corresponding thickness is further prepared by rolling. CN201810158894.5 discloses thermally conductive graphite paper and its preparation method, which includes the following steps: mixing flake graphite with sulfuric acid solution to obtain a first mixture; adding potassium dichromate powder to the first mixture to obtain a second mixture; washing the second mixture with water to obtain a pre-product; placing the pre-product in a chamber, first evacuating the chamber, then introducing an inert gas into the chamber, and performing a high-temperature expansion treatment to obtain expanded graphite material; and performing at least one rolling process on the expanded graphite material to obtain thermally conductive graphite paper. The above-mentioned graphite paper preparation process all require the use of strong oxidizing materials such as strong acids, resulting in poor safety and environmental friendliness during the preparation process. To address the aforementioned shortcomings, CN201310628887.4 discloses a method for preparing high thermal conductivity graphite paper. The method involves first preparing a nickel catalyst layer on a graphite sheet with a thickness of 0.2–1 mm using a magnetron sputtering system, with the nickel film thickness ranging from 10 to 500 nm. The prepared nickel catalyst layer is then subjected to high-temperature annealing to form nickel single-crystal particles with a diameter of 0.5–15 μm. Next, graphene is prepared on the graphite sheet coated with the nickel catalyst layer using chemical vapor deposition. The graphite sheet coated with the graphene film is then immersed in a catalyst solution of ferric nitrate, ferric chloride, or ferric acetate aqueous solution for 10 min–2 h. After drying at 120 °C, it is placed in a chemical vapor deposition system to grow carbon nanotubes. Finally, a hydraulic press is used to press the graphite paper to obtain the high thermal conductivity graphite paper. Although the aforementioned patents avoid using strong acids to modify graphite, the preparation process requires the use of magnetron sputtering systems and chemical vapor deposition, which necessitates surface treatment of the graphite. This process is time-consuming, has high equipment costs, and results in low yields, making it unsuitable for large-scale application. Summary of the Invention

[0003] To address the aforementioned issues, this invention discloses a high-efficiency heat dissipation graphite paper, its preparation method, and its application. It utilizes ultrasonically modified novel graphite powder as the main raw material, combined with common raw materials such as carbon black, talc, and carboxymethyl cellulose, thus avoiding strong acid contamination. The resulting graphite paper exhibits excellent mechanical properties, strong thermal conductivity, high preparation efficiency, and low cost.

[0004] The present invention adopts the following technical solution:

[0005] A high-efficiency heat-dissipating graphite paper is made from the following raw materials in parts by weight:

[0006]

[0007] The modified graphite powder is processed through the following modification steps:

[0008] 1) After crushing the flake graphite, pass it through a 200-500 mesh sieve to obtain flake graphite powder;

[0009] 2) Add 2-4% of multilayer graphene, 1-2% of molybdenum disulfide, 0.5-1% of silicon nitride, and 0.2-0.4% of potassium dichromate to the above-mentioned flake graphite powder, mix them evenly, and then place them in an organic solvent for ultrasonic treatment.

[0010] 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 300-400℃ until the moisture content is less than 5% to obtain modified graphite powder.

[0011] Furthermore, in the aforementioned high-efficiency heat dissipation graphite paper, the binder is coal tar pitch.

[0012] Furthermore, in the aforementioned high-efficiency heat dissipation graphite paper, the anti-wear agent is antimony dibutyldithiocarbamate.

[0013] Furthermore, in the aforementioned high-efficiency heat dissipation graphite paper, the nano-metal thermal conductive material is one or more of nickel powder, aluminum powder, or copper powder, with an average diameter between 200-500 nm.

[0014] Furthermore, in the above-mentioned high-efficiency heat dissipation graphite paper, the organic solvent in step 2) is anhydrous ethanol.

[0015] Furthermore, in the aforementioned high-efficiency heat dissipation graphite paper, the mass ratio of powder A to organic solvent is 1:20-30.

[0016] Furthermore, in the ultrasonic treatment of the aforementioned high-efficiency heat dissipation graphite paper, the power is 500-1500W, the frequency is 19.5-20.5KHz, the processing volume is 500-1500mL, the single ultrasonic time is 3-10s, the single interval time is 2-4s, the number of cycles is 100-300, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

[0017] The present invention also discloses a method for preparing the above-mentioned high-efficiency heat dissipation graphite paper, including the following steps: S1. Grinding: After uniformly mixing modified graphite powder, carbon black, talc powder and carboxymethyl cellulose, the mixture is ground and passed through a 100-200 mesh sieve to obtain mixture A;

[0018] S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B;

[0019] S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material;

[0020] S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 800-900℃, the sintering holding and pressurizing time is 25-40min, and the sintering pressure is 15-30MPa.

[0021] S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering.

[0022] S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2100-2500 N·cm-2 to obtain a high-efficiency heat-dissipating graphite paper with a thickness of 0.05-0.5 mm.

[0023] Furthermore, in the above-mentioned method for preparing high-efficiency heat-dissipating graphite paper, the expansion process parameters in step S3 are as follows: the graphite is heated and expanded in an expansion furnace at a temperature of 850-900℃ through a hydrocyclone for 10-20 minutes, and the expanded graphite is then extracted from the expansion furnace and placed into a silo.

[0024] On the other hand, the present invention also discloses the application of the above-mentioned high-efficiency heat dissipation graphite paper in heat dissipation in electronic products.

[0025] Compared with the prior art, the present invention has the following outstanding advantages:

[0026] This invention adds carbon black, talc, and carboxymethyl cellulose to modified graphite powder, significantly improving the strength and toughness of graphite paper. Compared to before the addition, the mechanical properties are improved by more than 80%. Simultaneously, this invention improves the modification of graphite powder, eliminating the need for strong acid denaturation or vapor deposition treatment. Only ultrasonic treatment and the addition of 2-4% multilayer graphene, 1-2% molybdenum disulfide, 0.5-1% silicon nitride, and 0.2-0.4% potassium dichromate by mass fraction are required to achieve the same or better thermal conductivity as strong acid denaturation. This reduces environmental pollution, improves the working environment, increases production efficiency, and has low preparation costs, making it easy to promote and produce. Attached Figure Description

[0027] Figure 1 A comparison of the thermal conductivity of graphite paper at 300℃;

[0028] Figure 2 A comparison of the thermal conductivity of graphite paper at 500℃;

[0029] Figure 3 A comparison of the thermal conductivity of graphite paper at 1000℃;

[0030] Figure 4 Comparative test of tensile strength properties of graphite paper. Detailed Implementation

[0031] 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.

[0032] The main raw materials for this invention are sourced from:

[0033] Flake graphite: Purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., item number 100033, high-purity flake graphite 50 mesh, purity 99.5wt%.

[0034] Multilayer graphene: purchased from Shanghai Fuqi Industry & Trade Co., Ltd., item number FQ-31.

[0035] Carbon black: Purchased from Tianjin Huarun Chemical Technology Co., Ltd., N990 high-purity carbon black.

[0036] Coal tar pitch: Purchased from Hebei Guangjinyuan New Energy Technology Co., Ltd., medium-temperature coal tar pitch.

[0037] Example 1

[0038] A high-efficiency heat-dissipating graphite paper, characterized in that it is made from the following raw materials in parts by weight:

[0039]

[0040] The modified graphite powder is processed through the following modification steps:

[0041] 1) After crushing the flake graphite, pass it through a 200-mesh sieve to obtain flake graphite powder;

[0042] 2) Add 2% multilayer graphene, 1% molybdenum disulfide, 0.5% silicon nitride, and 0.2% potassium dichromate to the above-mentioned flake graphite powder and mix them evenly to form powder A, which is then placed in an organic solvent for ultrasonic treatment.

[0043] 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 300℃ until the moisture content is less than 5% to obtain modified graphite powder.

[0044] The binder is coal tar pitch.

[0045] The anti-wear agent is antimony dibutyldithiocarbamate.

[0046] The nano-metal thermal conductive material is nickel powder with an average diameter between 200-500 nm.

[0047] The organic solvent in step 2) is anhydrous ethanol.

[0048] The mass ratio of powder A to organic solvent is 1:20.

[0049] In the ultrasonic treatment: the power is 500W, the frequency is 19.5-20.5KHz, the treatment volume is 500mL; the single ultrasonic time is 3s, the single interval time is 2s, the number of cycles is 100, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

[0050] The method for preparing the above-mentioned high-efficiency heat dissipation graphite paper is characterized by comprising the following steps:

[0051] S1. Grinding: After uniformly mixing modified graphite powder, carbon black, talc powder and carboxymethyl cellulose, grind the mixture and collect it through a 100-mesh sieve to obtain mixture A;

[0052] S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B;

[0053] S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material;

[0054] S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 800℃, the sintering holding and pressurization time is 25min, and the sintering pressure is 15MPa.

[0055] S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering.

[0056] S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2100 N·cm-2 to obtain a high-efficiency heat-dissipating graphite paper with a thickness of 0.2 mm.

[0057] In step S3, the expansion process parameters are as follows: the graphite is heated and expanded in an expansion furnace at 850°C through a hydrocyclone for 20 minutes, and then the expanded graphite is extracted from the expansion furnace and sent to the silo.

[0058] Example 2

[0059] A high-efficiency heat-dissipating graphite paper, characterized in that it is made from the following raw materials in parts by weight:

[0060]

[0061] The modified graphite powder is processed through the following modification steps:

[0062] 1) After crushing the flake graphite, pass it through a 400-mesh sieve to obtain flake graphite powder;

[0063] 2) Add 3% multilayer graphene, 1.5% molybdenum disulfide, 0.75% silicon nitride, and 0.3% potassium dichromate to the above-mentioned flake graphite powder and mix them evenly to form powder A, which is then placed in an organic solvent for ultrasonic treatment.

[0064] 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 350℃ until the moisture content is less than 5% to obtain modified graphite powder.

[0065] The binder is coal tar pitch.

[0066] The anti-wear agent is antimony dibutyldithiocarbamate.

[0067] The nano-metal thermal conductive material is aluminum powder with an average diameter between 200-500 nm.

[0068] The organic solvent in step 2) is anhydrous ethanol.

[0069] The mass ratio of powder A to organic solvent is 1:25.

[0070] In the ultrasonic treatment: the power is 1000W, the frequency is 19.5-20.5KHz, the treatment volume is 1000mL; the single ultrasonic time is 5s, the single interval time is 3s, the number of cycles is 200, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

[0071] The method for preparing the above-mentioned high-efficiency heat dissipation graphite paper is characterized by comprising the following steps:

[0072] S1. Grinding: After uniformly mixing modified graphite powder, carbon black, talc powder and carboxymethyl cellulose, grind the mixture and collect it through a 100-200 mesh sieve to obtain mixture A;

[0073] S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B;

[0074] S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material;

[0075] S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 850℃, the sintering holding and pressurization time is 30min, and the sintering pressure is 25MPa.

[0076] S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering.

[0077] S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2300 N·cm-2 to obtain a high thermal conductivity graphite paper with a thickness of 0.1 mm.

[0078] In step S3, the expansion process parameters are as follows: the graphite is heated and expanded in an expansion furnace at a temperature of 875°C through a hydrocyclone for 15 minutes, and then the expanded graphite is extracted from the expansion furnace and sent to the silo.

[0079] Example 3

[0080] A high-efficiency heat-dissipating graphite paper, characterized in that it is made from the following raw materials in parts by weight:

[0081]

[0082] The modified graphite powder is processed through the following modification steps:

[0083] 1) After crushing the flake graphite, pass it through a 200-500 mesh sieve to obtain flake graphite powder;

[0084] 2) Add 4% multilayer graphene, 2% molybdenum disulfide, 1% silicon nitride, and 0.4% potassium dichromate to the above-mentioned flake graphite powder and mix them evenly to form powder A, which is then placed in an organic solvent for ultrasonic treatment.

[0085] 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 400℃ until the moisture content is less than 5% to obtain modified graphite powder.

[0086] The binder is coal tar pitch.

[0087] The anti-wear agent is antimony dibutyldithiocarbamate.

[0088] The nano-metal thermal conductive material is copper powder with an average diameter between 200-500 nm.

[0089] The organic solvent in step 2) is anhydrous ethanol.

[0090] The mass ratio of powder A to organic solvent is 1:30.

[0091] In the ultrasonic treatment: the power is 1500W, the frequency is 19.5-20.5KHz, the treatment volume is 1500mL; the single ultrasonic time is 10s, the single interval time is 4s, the number of cycles is 300, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

[0092] The method for preparing the above-mentioned high-efficiency heat dissipation graphite paper is characterized by comprising the following steps:

[0093] S1. Grinding: After uniformly mixing modified graphite powder, carbon black, talc powder and carboxymethyl cellulose, grind the mixture and collect it through a 100-200 mesh sieve to obtain mixture A;

[0094] S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B;

[0095] S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material;

[0096] S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 900℃, the sintering holding and pressurization time is 25min, and the sintering pressure is 30MPa.

[0097] S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering.

[0098] S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2500 N·cm-2 to obtain a high thermal conductivity graphite paper with a thickness of 0.1 mm.

[0099] In step S3, the expansion process parameters are as follows: the graphite is heated and expanded in an expansion furnace at a temperature of 900°C through a hydrocyclone for 20 minutes, and then the expanded graphite is extracted from the expansion furnace and placed into a silo.

[0100] Comparative Example 1

[0101] The graphite powder used in Comparative Example 1 was flake graphite, which was not modified, and the rest was the same as in Example 2.

[0102] A high-efficiency heat-dissipating graphite paper is made from the following raw materials in parts by weight:

[0103]

[0104] The binder is coal tar pitch.

[0105] The anti-wear agent is antimony dibutyldithiocarbamate.

[0106] The nano-metal thermal conductive material is aluminum powder with an average diameter between 200-500 nm.

[0107] The organic solvent in step 2) is anhydrous ethanol.

[0108] The mass ratio of powder A to organic solvent is 1:25.

[0109] In the ultrasonic treatment: the power is 1000W, the frequency is 19.5-20.5KHz, the treatment volume is 1000mL; the single ultrasonic time is 5s, the single interval time is 3s, the number of cycles is 200, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

[0110] The method for preparing the above-mentioned high-efficiency heat dissipation graphite paper is characterized by comprising the following steps:

[0111] S1. Grinding: After uniformly mixing graphite powder, carbon black, talc powder and carboxymethyl cellulose, grind the mixture and collect it through a 100-200 mesh sieve to obtain mixture A;

[0112] S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B;

[0113] S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material;

[0114] S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 850℃, the sintering holding and pressurization time is 30min, and the sintering pressure is 25MPa.

[0115] S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering.

[0116] S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2300 N·cm-2 to obtain a high thermal conductivity graphite paper with a thickness of 0.1 mm.

[0117] In step S3, the expansion process parameters are as follows: the graphite is heated and expanded in an expansion furnace at a temperature of 875°C through a hydrocyclone for 15 minutes, and then the expanded graphite is extracted from the expansion furnace and sent to the silo.

[0118] Comparative Example 2

[0119] The modification process of Comparative Example 2 is different from that of Example 2. It does not contain multilayer graphene, but all other processes are the same.

[0120] The modified graphite powder is processed through the following modification steps:

[0121] 1) After crushing the flake graphite, pass it through a 200-500 mesh sieve to obtain flake graphite powder;

[0122] 2) Add 1-2% molybdenum disulfide, 0.5-1% silicon nitride, and 0.2-0.4% potassium dichromate to the above-mentioned flake graphite powder and mix them evenly to form powder A. Place the powder in an organic solvent for ultrasonic treatment.

[0123] 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 300-400℃ until the moisture content is less than 5% to obtain modified graphite powder.

[0124] Comparative Example 3

[0125] The modification process of Comparative Example 3 is different from that of Example 2. It does not contain molybdenum disulfide, but all other processes are the same.

[0126] Comparative Example 4

[0127] The modification process of Comparative Example 4 is different from that of Example 2. It does not contain silicon nitride, but all other processes are the same.

[0128] Comparative Example 5

[0129] The modification process of Comparative Example 5 is different from that of Example 2. It does not contain potassium dichromate, but all other processes are the same.

[0130] Test Example 1

[0131] The thermal conductivity of the graphite paper in Examples 1-3 and Comparative Examples 1-5 was measured.

[0132] Test method: The thermal conductivity of the above test objects was tested at 300℃, 500℃ and 1000℃ using a thermal conductivity meter. The thermal conductivity is the surface thermal conductivity.

[0133] Experimental subjects: Examples 1-3 and Comparative Examples 1-5.

[0134] The test results are shown in Table 1 and Figure 1-3 As shown:

[0135] Table 1 Thermal conductivity test of graphite paper

[0136]

[0137] 1) Based on the comparison of thermal conductivity of Examples 1-3 and Comparative Example 1 in the table above, the graphite paper of Examples 1-3 all have significant thermal conductivity in high-temperature environments, with an improvement of more than 50% compared to Comparative Example 1. Modifying graphite can greatly improve the thermal conductivity of graphite paper. Compared with graphite paper prepared by strong acid modification in the prior art, its thermal conductivity is not inferior, and may even be increased.

[0138] 2) Based on the comparison of thermal conductivity of Example 2 and Comparative Examples 2-4 in the table above, adding multilayer graphene, molybdenum disulfide, silicon nitride and potassium dichromate alone can only slightly improve the thermal conductivity of graphite paper, while adding the above raw materials at the same time can significantly improve the thermal conductivity of graphite paper.

[0139] Comparative Example 6

[0140] In Comparative Example 6, no carbon black was added, and the rest was the same as in Example 2.

[0141] Comparative Example 7

[0142] In Comparative Example 7, no talc was added, and the rest was the same as in Example 2.

[0143] Comparative Example 8

[0144] In Comparative Example 7, carboxymethyl cellulose was not added, and the rest was the same as in Example 2.

[0145] Comparative Example 9

[0146] In Comparative Example 8, carbon black, talc, and carboxymethyl cellulose were not added; otherwise, the process was the same as in Example 2.

[0147] Test Example 2

[0148] The mechanical properties of the graphite papers prepared in Example 2 and Comparative Examples 6-9 were compared. The tensile properties of the graphite papers during stretching were tested to characterize their strength and toughness. Tensile strength was tested using a universal testing machine, and the unit is megapascal (MPa). The results are shown in Table 2 and... Figure 4 .

[0149] Table 2 Tensile strength test of graphite paper

[0150] Tensile strength (MPa) Example 2 4.47 Comparative Example 6 3.32 Comparative Example 7 3.44 Comparative Example 8 3.52 Comparative Example 9 2.63

[0151] As shown in Table 2, Example 2, due to the simultaneous addition of carbon black, talc, and carboxymethyl cellulose, exhibited a tensile strength increase of over 80% compared to Comparative Example 9, which did not contain these raw materials. The test data from Example 2 and Comparative Examples 6-8 show that adding any of these raw materials alone could not achieve 75% of the tensile strength of Example 2. Therefore, it is evident that the simultaneous addition of carbon black, talc, and carboxymethyl cellulose, combined with modified graphite, can significantly improve the tensile strength of the graphite paper in this invention.

[0152] As can be seen from the above embodiments, the present invention significantly improves the strength and toughness of graphite paper by adding raw materials such as carbon black, talc, and carboxymethyl cellulose to modified graphite powder. Compared with before the addition, the mechanical properties are improved by more than 80%. At the same time, the present invention improves the modification of graphite powder. It eliminates the need for strong acid denaturation or vapor deposition treatment of graphite. Only ultrasonic treatment and the addition of 2-4% multilayer graphene, 1-2% molybdenum disulfide, 0.5-1% silicon nitride, and 0.2-0.4% potassium dichromate by mass fraction can achieve the same or better thermal conductivity as strong acid denaturation, reduce environmental pollution, improve the working environment, increase production efficiency, and have low preparation cost, making it easy to promote and produce.

[0153] The above are merely a few preferred embodiments of the present invention, described in a relatively specific and detailed manner, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A high-efficiency heat-dissipating graphite paper, characterized in that, Made from the following parts by weight of raw materials: 100 parts of modified graphite powder 10-20 parts carbon black 5-10 parts talcum powder 5-10 parts carboxymethyl cellulose 3-8 parts adhesive 2-4 parts of nano-metal thermal conductive material 2-3 parts of anti-wear agent The modified graphite powder is processed through the following modification steps: 1) After crushing the flake graphite, pass it through a 200-500 mesh sieve to obtain crushed flake graphite powder; 2) Add 2-4% multilayer graphene, 1-2% molybdenum disulfide, 0.5-1% silicon nitride, and 0.2-0.4% potassium dichromate to the pulverized flake graphite powder and mix them evenly to form powder A. Place it in an organic solvent for ultrasonic treatment. 3) After ultrasonic treatment, the mixed solution is filtered, the solids are collected, and vacuum dried at 300-400℃ until the moisture content is less than 5% to obtain modified graphite powder.

2. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, The binder is coal tar pitch.

3. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, The anti-wear agent is antimony dibutyldithiocarbamate.

4. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, The nano-metal thermal conductive material is one or more of nickel powder, aluminum powder or copper powder, with an average diameter between 200-500 nm.

5. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, The organic solvent in step 2) is anhydrous ethanol.

6. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, The mass ratio of powder A to organic solvent is 1:20-30.

7. The high-efficiency heat dissipation graphite paper according to claim 1, characterized in that, In the ultrasonic treatment: power 500-1500W, frequency 19.5-20.5KHz, treatment volume 500-1500mL; single ultrasonic time 3-10s, single interval time 2-4s, number of cycles 100-300 times, and magnetic stirring is performed simultaneously during the ultrasonic treatment.

8. The method for preparing high-efficiency heat-dissipating graphite paper according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Grinding: After uniformly mixing modified graphite powder, carbon black, talc powder and carboxymethyl cellulose, grind the mixture and collect it through a 100-200 mesh sieve to obtain mixture A; S2. Mixing: Add the binder, nano-metal thermal conductive material and anti-wear agent to mixture A, and stir further to obtain mixture B; S3. Expansion: Mixture B is fed into a graphite expansion furnace for expansion to obtain a molded material; S4. Sintering: The molding material obtained in step S3 is sintered under argon gas. The sintering temperature is 800-900℃, the sintering holding and pressurizing time is 25-40min, and the sintering pressure is 15-30MPa. S5. Second sintering: The first sintered product obtained in step S4 is subjected to a second sintering process using spark plasma sintering. The maximum sintering temperature is 2000℃. Graphite paper material is obtained after the second sintering. S6. Pressing: The graphite paper material is pressed using a hydraulic press at a pressure of 2100–2500 N•cm. -2 This yields graphite paper with a thickness of 0.05-0.5 mm that provides high-efficiency heat dissipation.

9. The method for preparing high-efficiency heat-dissipating graphite paper according to claim 8, characterized in that, In step S3, the expansion process parameters are as follows: the graphite is heated and expanded in an expansion furnace at a temperature of 850-900℃ through a hydrocyclone for 10-20 minutes, and the expanded graphite is then extracted from the expansion furnace and placed into a silo.

10. The application of the high-efficiency heat dissipation graphite paper as described in any one of claims 1-7 in heat dissipation in electronic products.

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