Production method of graphene heat dissipation film

Abstract

The invention discloses a production method of a graphene heat dissipation film, belongs to the technical field of preparation of graphene heat dissipation films, and aims to solve the problem of poor heat dissipation performance of the graphene heat dissipation film caused by low single-sheet rate and small sheet diameter of the graphene heat dissipation film in the prior art. According to the method, graphene oxide in an agglomeration state and a solvent are mixed and then sequentially subjected to mechanical shearing dispersion, high-pressure homogenization, stirring dispersion cooling and defoaming to obtain graphene oxide slurry, the defoaming graphene oxide slurry is adopted for coating and high-temperature reduction, and the graphene heat dissipation film is obtained. The method can be used for producing the graphene heat dissipation film.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene heat dissipation film preparation, and in particular relates to a production method of a graphene heat dissipation film. Background Art

[0002] Graphene has good heat dissipation performance. Graphene heat dissipation film is made of overlapping single sheets of graphene. The heat dissipation coefficient is as high as 1300W / (m·K). Its bending resistance and processing performance are better than those of current commercial artificial graphite sheets. It can be used as an excellent heat dissipation material for various electronic devices.

[0003] However, the existing graphene heat dissipation films have a low single-piece rate and a small sheet diameter, resulting in poor heat dissipation performance of the graphene heat dissipation films. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a method for producing a graphene heat dissipation film, so as to solve the problem in the prior art that the graphene heat dissipation film has a low single-piece rate and a small sheet diameter, resulting in poor heat dissipation performance of the graphene heat dissipation film.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions.

[0006] The present invention provides a method for producing a graphene heat dissipation film, comprising the following steps:

[0007] Step 1: mixing the agglomerated graphene oxide and the solvent and then performing mechanical shearing and dispersion to obtain a primary mixed graphene oxide slurry, wherein the graphene oxide in the primary mixed graphene oxide slurry is in a multi-layer stacked state;

[0008] Step 2: using a high-pressure homogenizer to perform high-pressure homogenization on the initially mixed graphene oxide slurry, so that the multi-layered graphene oxide in the initially mixed graphene oxide slurry is peeled off into a single-layer graphene oxide, and a homogeneous graphene oxide slurry is obtained;

[0009] Step 3: stirring, dispersing and cooling the homogeneous graphene oxide slurry to obtain cooled graphene oxide slurry;

[0010] Step 4: Repeat steps 2 to 3 until the viscosity of the cooled graphene oxide slurry drops to a threshold range and then proceed to step 5;

[0011] Step 5: defoaming the cooled graphene oxide slurry to obtain defoamed graphene oxide slurry;

[0012] Step 6: coating with defoamed graphene oxide slurry to obtain a graphene oxide film;

[0013] Step 7: Perform high-temperature reduction on the graphene oxide film so that the graphene oxide is reduced to graphene, thereby obtaining a graphene heat dissipation film.

[0014] Furthermore, in step 1, the solid content of the initially mixed graphene oxide slurry is 4 to 6%.

[0015] Furthermore, in step 1, the air pressure during the mechanical shearing dispersion process is -100 to -200 Pa.

[0016] Furthermore, in step 2, the shear force of the high-pressure homogenizer on the primary mixed graphene oxide slurry is greater than 100 MPa.

[0017] Furthermore, in step 3, the stirring speed is 100 to 300 rad / min.

[0018] Furthermore, the viscosity of the initially mixed graphene oxide slurry is 8000-10000 cp.

[0019] Furthermore, in step 4, step 2 to step 3 are repeated once.

[0020] Furthermore, the viscosity of the once homogenized graphene oxide slurry is 6500-7500 cp; the viscosity of the once cooled graphene oxide slurry is 5000-6000 cp.

[0021] Furthermore, the viscosity of the secondary homogenized graphene oxide slurry is 4000-4500 cp; the viscosity of the secondary cooled graphene oxide slurry is 3000-3500 cp.

[0022] Furthermore, heat dissipation film production equipment is used for production.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] The production method of the graphene heat dissipation film provided by the present invention, in the process of preparing graphene oxide slurry, the raw materials of the graphene oxide slurry (i.e., graphene oxide and solvent) are dispersed by mechanical shearing dispersion and high-pressure homogenization. On the one hand, the mechanical shearing dispersion can fully and evenly mix the raw materials, and at the same time, disperse the graphene oxide in the agglomerated state into graphene oxide in the multi-layer stacked state, realize mechanical viscosity reduction, and is suitable for the production of large-scale high-viscosity graphene oxide slurry; on the other hand, the high-pressure homogenization can further peel off the multi-layer stacked graphene oxide in the graphene oxide slurry, so that the multi-layer stacked graphene oxide is peeled off into the graphene oxide in the single-layer state, avoiding damage to the graphene oxide sheet diameter, thereby being able to improve the single-layer rate and sheet diameter of the graphene oxide in the obtained graphene oxide slurry, and then improve the single-layer rate, sheet diameter and heat dissipation performance of the graphene heat dissipation film prepared subsequently.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0027] Figure 1 A flow chart of a method for producing a graphene heat dissipation film provided in Example 1 of the present invention is provided;

[0028] Figure 2 A schematic diagram of the structure of the production equipment in the production method of the graphene heat dissipation film provided in Example 1 of the present invention is provided;

[0029] Figure 3 The present invention provides a structural schematic diagram of a second cooling chamber in the method for producing a graphene heat dissipation film provided in Example 1;

[0030] Figure 4 A schematic diagram of the structure of a delivery pipe in a method for producing a graphene heat dissipation film provided in Example 1 of the present invention is provided, wherein the thermal expansion ring is not in contact with the contact sensor;

[0031] Figure 5 A schematic structural diagram of a delivery tube in a method for producing a graphene heat dissipation film provided in Example 1 of the present invention is provided, wherein a thermal expansion ring is in contact with a contact sensor.

[0032] Reference numerals:

[0033] 1-high pressure homogenizer; 2-conveying pipe; 201-contact sensor; 202-inner pipe; 203-outer pipe; 204-thermal expansion ring; 3-dispersion chamber; 4-stirring blade; 5-shearing and dispersing blade; 6-transfer chamber; 7-slurry coating machine; 8-high temperature reduction chamber; 9-defoaming machine; 10-rotating motor; 11-cooling chamber; 12-stirring assembly; 13-high temperature inlet pipe; 14-low temperature inlet pipe; 15-low temperature outlet pipe; 16-inner tank; 17-interlayer chamber; 18-rotating blade; 19-heat exchange chamber; 20-cooling medium supply unit; 21-temperature detection unit; 22-conversion tee; 23-tee controller. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0035] Embodiment 1

[0036] This embodiment provides a method for producing a graphene heat dissipation film. Figure 1 , including the following steps:

[0037] Step 1: mixing agglomerated graphene oxide and a solvent (e.g., a mixed solvent of water and ethanol) and then performing mechanical shearing and dispersion to obtain a primary mixed graphene oxide slurry, wherein the solid content of the primary mixed graphene oxide slurry is 4-6%, and the graphene oxide in the primary mixed graphene oxide slurry is in a multi-layer stacked state;

[0038] Step 2: using a high-pressure homogenizer 1 to perform high-pressure homogenization on the initially mixed graphene oxide slurry, so that the multi-layered graphene oxide in the initially mixed graphene oxide slurry is peeled off into a single-layer graphene oxide, and a homogeneous graphene oxide slurry is obtained;

[0039] Step 3: stirring, dispersing and cooling the homogeneous graphene oxide slurry to obtain cooled graphene oxide slurry;

[0040] Step 4: Repeat steps 2 to 3 until the viscosity of the cooled graphene oxide slurry drops to a threshold range and then proceed to step 5;

[0041] Step 5: defoaming the cooled graphene oxide slurry to obtain defoamed graphene oxide slurry;

[0042] Step 6: coating with defoamed graphene oxide slurry to obtain a graphene oxide film;

[0043] Step 7: Perform high-temperature reduction on the graphene oxide film so that the graphene oxide is reduced to graphene, thereby obtaining a graphene heat dissipation film.

[0044] Compared with the prior art, the production method of the graphene heat dissipation film provided in this embodiment, in the process of preparing graphene oxide slurry, the raw materials of the graphene oxide slurry (i.e., graphene oxide and solvent) are dispersed by mechanical shearing dispersion and high-pressure homogenization. On the one hand, the mechanical shearing dispersion can fully and evenly mix the raw materials, and at the same time, disperse the agglomerated graphene oxide into multi-layered graphene oxide, achieve mechanical viscosity reduction, and is suitable for the production of large-scale high-viscosity graphene oxide slurry; on the other hand, the high-pressure homogenization can further peel off the multi-layered graphene oxide in the graphene oxide slurry, so that the multi-layered graphene oxide is peeled off into a single-layered graphene oxide, avoiding damage to the graphene oxide sheet diameter, thereby improving the monolayer rate and sheet diameter of the graphene oxide in the obtained graphene oxide slurry, and then improving the monolayer rate, sheet diameter and heat dissipation performance of the subsequent graphene heat dissipation film.

[0045] In order to improve the effect of mechanical shearing dispersion, in the above step 1, the air pressure during the mechanical shearing dispersion process is -100 to -200 Pa, that is, the mechanical shearing dispersion is carried out under a medium vacuum state.

[0046] Similarly, in order to improve the effect of high-pressure homogenization, in the above step 2, the shear force of the high-pressure homogenizer on the primary mixed graphene oxide slurry is greater than 100 MPa (for example, 110 to 150 MPa).

[0047] In order to fully stir, disperse and cool the homogeneous graphene oxide slurry, in the above step 3, the stirring speed is 100 to 300 rad / min.

[0048] In practical applications, taking high-pressure homogenization and stirring dispersion cooling as an example, the specific viscosity of the graphene oxide slurry obtained after each step in the above-mentioned method for producing the graphene heat dissipation film is as follows:

[0049] The viscosity of the initially mixed graphene oxide slurry obtained in step 1 is 8000 to 10000 cp.

[0050] The viscosity of the primary homogenized graphene oxide slurry is lower than 8000 cp (eg, 6500-7500 cp).

[0051] The viscosity of the once cooled graphene oxide slurry is lower than 6500 cp (eg, 5000-6000 cp).

[0052] The viscosity of the secondary homogenized graphene oxide slurry is lower than 5000 cp (eg, 4000-4500 cp).

[0053] The viscosity of the secondary cooled graphene oxide slurry is lower than 4000 cp (eg, 3000-3500 cp).

[0054] Accordingly, the temperature of the primary cooling of the graphene oxide slurry is 70° C. or less (eg, 55 to 70° C.).

[0055] The temperature of the secondary cooling of the graphene oxide slurry is 50° C. or less (eg, 30 to 50° C.).

[0056] Exemplarily, the above-mentioned method for producing the graphene heat dissipation film adopts a heat dissipation film production device with the following structure, see Figure 2 The production equipment includes a mechanical shearing dispersion chamber, a high-pressure homogenizer 1, a cooling chamber, a defoamer 9, a slurry coater 7 and a high-temperature reduction chamber 8 connected in sequence, wherein the number of the high-pressure homogenizer 1 and the cooling chamber is multiple, and the high-pressure homogenizer 1 and the cooling chamber are alternately arranged.

[0057] In order to achieve mechanical shear dispersion, the structure of the mechanical shear dispersion chamber, specifically, includes a dispersion chamber 3 and a stirring blade 4 and a shear dispersion blade 5 arranged in the dispersion chamber 3. The stirring blade 4 is located at the bottom of the dispersion chamber 3 and is mainly used for stirring the graphene oxide slurry. The shear dispersion blade 5 is located above the stirring blade 4 and is mainly used for dispersing the agglomerated graphene oxide into multi-layer graphene oxide. The rotation speed of the shear dispersion blade 5 is greater than the rotation speed of the stirring blade 4.

[0058] In order to ensure the continuous production of the above-mentioned production equipment, the above-mentioned production equipment also includes a transfer chamber 6, and the discharge port of the mechanical shear dispersion chamber is connected to the feed port of the high-pressure homogenizer 1 through the transfer chamber 6. In this way, the graphene oxide slurry discharged from the mechanical shear dispersion chamber will first be discharged into the transfer chamber 6 for storage, and then will flow into the high-pressure homogenizer 1 for high-pressure homogenization to reduce the processing pressure of the high-pressure homogenizer 1.

[0059] For the cooling chamber, the following two structures can be used:

[0060] One of the structures, specifically, the cooling chamber includes a cooling chamber 11, a stirring assembly 12 arranged in the cooling chamber 11, and a rotating motor 10 for driving the stirring assembly 12 to rotate. In order to effectively cool the graphene oxide slurry, a high-temperature inlet pipe 13, a low-temperature inlet pipe 14 and a low-temperature outlet pipe 15 are opened on the cooling chamber 11.

[0061] Another structure, specifically, see Figure 3 The cooling chamber includes an inner tank 16, an interlayer chamber 17 arranged on the outer wall of the inner tank 16, and a rotating blade 18 arranged in the inner tank 16. In order to effectively cool the graphene oxide slurry, a high-temperature inlet pipe 13, a low-temperature inlet pipe 14 and a low-temperature outlet pipe 15 are provided on the inner tank 16.

[0062] It should be noted that the temperature of the graphene oxide slurry of the high-temperature inlet pipe 13 , the temperature of the graphene oxide slurry of the low-temperature outlet pipe 15 , and the temperature of the graphene oxide slurry of the low-temperature inlet pipe 14 decrease in sequence.

[0063] In order to further adjust the temperature of the graphene oxide slurry discharged from the cooling chamber, the above-mentioned production equipment also includes a heat exchange chamber 19, a cooling medium supply unit 20, a temperature detection unit 21, a conversion tee 22 and a tee controller 23, the conversion tee 22 has a tee feed port, a first tee discharge port and a second tee discharge port, the high-temperature inlet pipe 13 is connected to the discharge port of the high-pressure homogenizer 1, the low-temperature outlet pipe 15 is connected to the tee feed port, the first tee discharge port is connected to the slurry feed port of the heat exchange chamber 19 The slurry discharge port of the heat exchange chamber 19 is connected to the low-temperature inlet pipe 14, the second three-way discharge port is connected to the feed port of the high-pressure homogenizer 1, the temperature detection unit 21 is arranged on the connection pipeline between the discharge port of the cooling chamber and the three-way feed port, the liquid outlet of the cooling medium supply unit 20 is connected to the medium inlet port of the heat exchange chamber 19, the medium liquid outlet of the heat exchange chamber 19 is connected to the liquid inlet port of the cooling medium supply unit 20, and the three-way controller 23 is respectively connected to the temperature detection unit 21 and the conversion tee 22.

[0064] During implementation, the temperature detection unit 21 detects the temperature data of the graphene oxide slurry in real time and transmits it to the three-way controller 23. The three-way controller 23 receives the temperature data and determines whether the temperature data is higher than the prefabricated temperature. If it is higher than the threshold temperature, it means that the temperature of the graphene oxide slurry is too high and is not suitable for subsequent high-temperature homogenization. The three-way controller 23 controls the three-way feed port to be connected with the first three-way discharge port, and the graphene oxide slurry discharged from the cooling chamber enters the heat exchange chamber 19 for further cooling. After cooling, it is discharged into the cooling chamber and mixed with the graphene oxide slurry in the cooling chamber to cool the graphene oxide slurry in the cooling chamber. If it is lower than or equal to the threshold temperature, it means that the temperature of the graphene oxide slurry is suitable and subsequent high-temperature homogenization can be performed. The three-way controller 23 controls the three-way feed port to be connected with the second three-way discharge port, and the graphene oxide slurry is discharged into the high-temperature homogenizer for subsequent high-temperature homogenization.

[0065] Exemplarily, the inner tank 16 is cylindrical in shape, and the mounting shaft of the rotary blade 18 is disposed along the axial direction of the inner tank 16 .

[0066] Taking into account the high viscosity of the graphene oxide slurry in the cooling chamber, in order to avoid precipitation and stratification of the graphene oxide slurry in the cooling chamber, the feeding direction of the high-temperature inlet pipe 13 and the feeding direction of the low-temperature inlet pipe 14 are both along the tangential direction of the inner tank 16, and the feeding directions of the two are rotated by a certain angle in a clockwise or counterclockwise direction, so that the swirl direction of the graphene oxide slurry flowing from the high-temperature inlet pipe 13 into the inner tank 16 is the same as the swirl direction of the graphene oxide slurry flowing from the low-temperature inlet pipe 14 into the inner tank 16. The swirl of the graphene oxide slurry is used to drive the rotating blades 18 to rotate, without the need for an additional driver for the rotating blades 18, thereby effectively simplifying the structure.

[0067] In this way, when the temperature data of the graphene oxide slurry is lower than or equal to the threshold temperature, no graphene oxide slurry flows into the inner tank 16 from the low-temperature inlet pipe 14, and the swirl power of the graphene oxide slurry in the inner tank 16 is only provided by the graphene oxide slurry flowing into the inner tank 16 from the high-temperature inlet pipe 13 of the tank body. The swirl speed and the rotation speed of the rotating blades 18 are low. Since the discharge flow rate of the low-temperature outlet pipe 15 remains basically unchanged, the heat exchange between the graphene oxide slurry and the interlayer cavity 17 is small. When the temperature data of the graphene oxide slurry is higher than the threshold temperature, the graphene oxide slurry will flow into the heat exchange chamber 19 for further cooling. The swirl power of the graphene oxide slurry in the inner tank 16 is only provided by the graphene oxide slurry flowing into the inner tank 16 from the high-temperature inlet pipe 13 and the graphene oxide slurry flowing into the inner tank 16 from the low-temperature inlet pipe 14. The swirl speed and the rotation speed of the rotating blade 18 are relatively high. Since the discharge flow rate of the low-temperature outlet pipe 15 remains basically unchanged, the heat exchange rate between the graphene oxide slurry and the interlayer chamber 17 is relatively large, and the graphene oxide slurry can be fully cooled.

[0068] Considering that the temperature of subsequent graphene oxide slurry coating will affect the performance of subsequent graphene oxide film and graphene heat dissipation film, in order to further cool the graphene oxide slurry discharged from the defoamer 9, the above-mentioned production equipment also includes a conveying pipe 2, a coolant supply unit and a cooling controller.

[0069] Specifically, the delivery pipe 2 includes an inner pipe 202 and an outer pipe 203 sleeved outside the inner pipe 202. There is a certain size of gap between the inner pipe 202 and the outer pipe 203, and the gap serves as a cooling chamber. The cooling chamber is connected to the cooling liquid supply unit. The outer wall of the inner pipe 202 is provided with a heat expansion ring 204, and the inner wall of the outer pipe 203 is provided with a contact sensor 201. The positions of the heat expansion ring 204 and the contact sensor 201 correspond. There is a tiny gap between the outer ring surface of the heat expansion ring 204 and the contact sensor 201. The cooling controller is connected to the contact sensor 201 and the cooling liquid supply unit. In this way, when the temperature of the graphene oxide slurry in the delivery pipe 2 does not exceed the temperature threshold, since there is a tiny gap between the outer ring surface of the heat expansion ring 204 and the contact sensor 201, the inner pipe 202 and the outer pipe 203 are isolated from air, so that the cooling chamber can form air insulation, see Figure 4 When the temperature of the graphene oxide slurry in the delivery pipe 2 exceeds the temperature threshold, the heat in the graphene oxide slurry will be transferred to the thermal expansion ring 204, so that the thickness of the thermal expansion ring 204 increases, and the outer ring surface of the thermal expansion ring 204 contacts the contact sensor 201. The contact sensor 201 sends an over-temperature signal to the cooling controller, and the cooling controller controls the coolant supply unit to pass the coolant into the cooling chamber. The cooling chamber can directly cool the graphene oxide slurry through the inner tube 202. See Figure 5 In addition, when the temperature of the graphene oxide slurry in the delivery pipe 2 exceeds the temperature threshold, the heat expansion ring 204 and the contact sensor 201 in contact with each other can also serve as a heat dissipation structure, so that the heat in the graphene oxide slurry can be diffused to the external environment, thereby further improving the cooling effect of the graphene oxide slurry.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for producing a graphene heat dissipation film, characterized in that: The steps include: Step 1: mixing graphene oxide in an agglomerated state with a solvent and then performing mechanical shearing and dispersion to obtain a primary mixed graphene oxide slurry, wherein the graphene oxide in the primary mixed graphene oxide slurry is in a multi-layer stacked state; Step 2: using a high-pressure homogenizer to perform high-pressure homogenization on the initially mixed graphene oxide slurry, so that the multi-layered graphene oxide in the initially mixed graphene oxide slurry is peeled off into a single-layer graphene oxide, and a homogeneous graphene oxide slurry is obtained; Step 3: stirring, dispersing and cooling the homogeneous graphene oxide slurry to obtain cooled graphene oxide slurry; Step 4: Repeat steps 2 to 3 until the viscosity of the cooled graphene oxide slurry drops to a threshold range and then proceed to step 5; Step 5: defoaming the cooled graphene oxide slurry to obtain defoamed graphene oxide slurry; Step 6: coating with defoamed graphene oxide slurry to obtain a graphene oxide film; Step 7: Perform high-temperature reduction on the graphene oxide film so that the graphene oxide is reduced to graphene, thereby obtaining a graphene heat dissipation film.

2. The method for producing a graphene heat dissipation film according to claim 1, characterized in that: In the step 1, the solid content of the initially mixed graphene oxide slurry is 4-6%.

3. The method for producing a graphene heat dissipation film according to claim 1, characterized in that: In the step 1, the air pressure during the mechanical shearing and dispersion process is -100 to -200 Pa.

4. The method for producing a graphene heat dissipation film according to claim 1, characterized in that: In the step 2, the shear force of the high-pressure homogenizer on the primary mixed graphene oxide slurry is greater than 100 MPa.

5. The method for producing a graphene heat dissipation film according to claim 1, characterized in that: In the step 3, the stirring speed is 100 to 300 rad / min.

6. The method for producing a graphene heat dissipation film according to claim 1, characterized in that: The viscosity of the initially mixed graphene oxide slurry is 8000-10000 cp.

7. The method for producing a graphene heat dissipation film according to any one of claims 1 to 6, characterized in that: In step 4, steps 2 to 3 are repeated once.

8. The method for producing a graphene heat dissipation film according to claim 7, characterized in that: The viscosity of the primary homogenized graphene oxide slurry is 6500-7500cp; The viscosity of the once cooled graphene oxide slurry is 5000-6000 cp.

9. The method for producing a graphene heat dissipation film according to claim 8, characterized in that: The viscosity of the secondary homogenized graphene oxide slurry is 4000-4500cp; The viscosity of the secondary cooled graphene oxide slurry is 3000-3500 cp.

10. The method for producing a graphene heat dissipation film according to claim 7, characterized in that: The heat dissipation film production equipment is used for production.

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