Dispersing system for graphene oxide slurry

Abstract

The invention discloses a dispersion system of graphene oxide slurry, belongs to the technical field of graphene film preparation, and aims to solve the problems of high viscosity and small sheet diameter of the graphene oxide slurry caused by preparation of the graphene oxide slurry only by mechanical stirring in the prior art. The dispersion system comprises a mechanical shearing dispersion unit, a homogenizing dispersion unit and a defoaming treatment unit which are sequentially connected, and the homogenizing dispersion unit comprises a high-pressure homogenizer and a cooling tank which are sequentially connected from the mechanical shearing dispersion unit to the defoaming treatment unit. The method can be used for dispersing the graphene oxide slurry.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene film preparation, and in particular relates to a dispersion system of graphene oxide slurry. Background Art

[0002] Graphene heat dissipation film is the material with the highest thermal conductivity at present. The main production process is as follows:

[0003] Graphene oxide is used to prepare graphene oxide slurry (i.e., an aqueous sol dispersion of graphene oxide), and a graphene oxide film is obtained through a coating process. Then, the graphene oxide film is reduced to a graphene film by a high-temperature heat treatment combined with a chemical reduction method. The solid content and viscosity of the graphene oxide slurry will directly affect the quality of the graphene film.

[0004] Existing graphene oxide slurries usually adopt a single mechanical stirring method. On the one hand, it is impossible to obtain graphene oxide slurries with low viscosity. On the other hand, during the mechanical stirring process, the graphene oxide sheets will be broken and the sheet diameter will be reduced, which will affect the thermal conductivity of the subsequent graphene film. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a dispersion system for graphene oxide slurry, so as to solve the problem that the prior art only uses mechanical stirring to prepare graphene oxide slurry, resulting in high viscosity and small flake diameter of graphene oxide slurry.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions.

[0007] The present invention provides a dispersion system for graphene oxide slurry, comprising a mechanical shearing dispersion unit, a homogenizing dispersion unit and a defoaming treatment unit which are connected in sequence, wherein the homogenizing dispersion unit comprises a high-pressure homogenizer and a cooling tank which are connected in sequence from the mechanical shearing dispersion unit to the defoaming treatment unit.

[0008] Furthermore, the number of homogenizing and dispersing units is two groups, and the high-pressure homogenizers and cooling tanks are alternately arranged.

[0009] Furthermore, the mechanical shearing and dispersing unit includes a dispersing tank and a stirring blade and a shearing and dispersing blade arranged in the dispersing tank, and the rotation speed of the shearing and dispersing blade is greater than the rotation speed of the stirring blade.

[0010] Furthermore, the stirring blade is located at the bottom of the dispersion tank; and the shearing and dispersing blade is located above the stirring blade.

[0011] Furthermore, the above-mentioned graphene oxide slurry dispersion system also includes a buffer tank, and the discharge port of the mechanical shear dispersion unit is connected to the feed port of the high-pressure homogenizer through the buffer tank.

[0012] Furthermore, the cooling tank includes a cooling cylinder, a stirring assembly arranged in the cooling cylinder, and a stirring driving assembly for driving the stirring assembly to rotate.

[0013] Furthermore, the cooling tank comprises an inner layer of the tank body, a cooling interlayer arranged on the outer wall of the inner layer of the tank body, and rotating blades arranged in the inner layer of the tank body.

[0014] Furthermore, the inner layer of the tank body is cylindrical in shape, and the mounting shaft of the rotating blade is arranged along the axial direction of the inner layer of the tank body.

[0015] Furthermore, the dispersion system of the above-mentioned graphene oxide slurry also includes a first delivery pump arranged on the pipeline connecting the mechanical shear dispersion unit and the buffer tank, a second delivery pump arranged on the pipeline connecting the buffer tank and the high-pressure homogenizer, a third delivery pump arranged on the pipeline connecting the high-pressure homogenizer and the cooling tank, and a fourth delivery pump arranged on the pipeline connecting the cooling tank and the defoaming treatment unit.

[0016] Furthermore, the first delivery pump, the second delivery pump, the third delivery pump and the fourth delivery pump are all screw pumps.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] A) The dispersion system of graphene oxide slurry provided by the present invention adopts a combination of multiple dispersion equipment (mechanical shearing dispersion unit and homogenizing dispersion unit), which can improve the monolayer rate and sheet diameter of graphene oxide in the obtained graphene oxide slurry, thereby improving the thermal conductivity of the subsequently prepared graphene film.

[0019] B) In the dispersion system of the graphene oxide slurry provided by the present invention, the mechanical shearing dispersion unit can fully and evenly mix the raw materials, and at the same time, disperse the agglomerated graphene oxide into multi-layer graphene oxide to achieve mechanical viscosity reduction, which is suitable for large-scale production of high-viscosity graphene oxide slurry.

[0020] C) In the dispersion system of the graphene oxide slurry provided by the present invention, the high-pressure homogenizer can further peel off the multi-layer graphene oxide in the graphene oxide slurry, so that the multi-layer graphene oxide is peeled off into a single-layer graphene oxide, avoiding damage to the graphene oxide sheet diameter.

[0021] D) In ​​the graphene oxide slurry dispersion system provided by the present invention, the graphene oxide slurry discharged from the mechanical shearing dispersion unit will first be discharged into a buffer tank for storage, and will then flow into a cooling tank for cooling to reduce the processing pressure of the cooling tank.

[0022] 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

[0023] 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.

[0024] Figure 1 The present invention provides a schematic structural diagram of a dispersion system of graphene oxide slurry provided in Example 1;

[0025] Figure 2 A schematic diagram of the structure of a mechanical shearing dispersion unit in a dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided;

[0026] Figure 3 A schematic diagram of a first structure of a cooling tank in a dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided;

[0027] Figure 4 A schematic diagram of the connection between a first cooling tank, a heat exchange tank, and a cooling medium tank in a dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided;

[0028] Figure 5 A schematic structural diagram of a second cooling tank in the dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided;

[0029] Figure 6 A schematic diagram of the structure of a discharge pipeline in a dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided, wherein the thermal expansion ring is not in contact with the contact sensor;

[0030] Figure 7 A schematic structural diagram of a discharge pipeline in a dispersion system of graphene oxide slurry provided in Example 1 of the present invention is provided, wherein a thermal expansion ring is in contact with a contact sensor.

[0031] Reference numerals:

[0032] 1-high pressure homogenizer; 2-discharge pipeline; 201-contact sensor; 202-inner tube; 203-outer tube; 204-thermal expansion ring; 3-dispersion tank; 4-stirring blade; 5-shearing and dispersing blade; 6-buffer tank; 7-first delivery pump; 8-second delivery pump; 9-third delivery pump; 10-fourth delivery pump; 11-cooling cylinder; 12-stirring assembly; 13-high temperature feed port; 14-low temperature feed port; 15-low temperature discharge port; 16-tank inner layer; 17-cooling interlayer; 18-rotating blade; 19-heat exchange tank; 20-cooling medium tank; 21-temperature sensor; 22-connecting tee; 23-tee controller; 24-defoaming treatment unit; 25-stirring drive assembly. DETAILED DESCRIPTION

[0033] 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.

[0034] Embodiment 1

[0035] This embodiment provides a dispersion system of graphene oxide slurry, see Figure 1 , including a mechanical shearing dispersion unit, a homogenizing dispersion unit and a defoaming treatment unit 24 (for example, a defoaming machine) connected in sequence, wherein the number of the homogenizing dispersion units is at least one group, for example, two groups, including a high-pressure homogenizer 1 and a cooling tank connected in sequence from the mechanical shearing dispersion unit to the defoaming treatment unit 24, that is, the high-pressure homogenizer 1 and the cooling tank are alternately arranged.

[0036] Compared with the prior art, the dispersion system of graphene oxide slurry provided in this embodiment adopts a combination of multiple dispersion equipment (mechanical shearing dispersion unit and homogenizing dispersion unit).

[0037] Among them, the mechanical shearing dispersion unit can fully and evenly mix the raw materials, and at the same time, disperse the agglomerated graphene oxide into multi-layer graphene oxide to achieve mechanical viscosity reduction, which is suitable for the production of large-scale high-viscosity graphene oxide slurry.

[0038] The high-pressure homogenizer 1 can further peel off the multi-layer graphene oxide in the graphene oxide slurry, so that the multi-layer graphene oxide is peeled off into a single-layer graphene oxide, avoiding damage to the graphene oxide sheet diameter, thereby improving the single-layer rate and sheet diameter of the graphene oxide in the obtained graphene oxide slurry, and then improving the thermal conductivity of the subsequently obtained graphene film.

[0039] In order to achieve mechanical shear dispersion, for the structure of the mechanical shear dispersion unit, see Figure 2It includes a dispersion tank 3 and a stirring blade 4 and a shearing dispersion blade 5 arranged in the dispersion tank 3. The stirring blade 4 is located at the bottom of the dispersion tank 3 and is mainly used for stirring the graphene oxide slurry. The shearing 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 shearing dispersion blade 5 is greater than the rotation speed of the stirring blade 4.

[0040] In practical applications, considering that the processing capacity of the mechanical shearing dispersion unit is different from that of the high-pressure homogenizer 1, the processing capacity of the mechanical shearing dispersion unit is usually greater than that of the high-pressure homogenizer 1. In order to ensure the continuous production of the above-mentioned graphene oxide slurry dispersion system, the above-mentioned graphene oxide slurry dispersion system also includes a buffer tank 6, and the discharge port of the mechanical shearing dispersion unit is connected to the feed port of the high-pressure homogenizer 1 through the buffer tank 6. In this way, the graphene oxide slurry discharged from the mechanical shearing dispersion unit will first be discharged into the buffer tank 6 for storage, and will later flow into the high-pressure homogenizer 1 for high-pressure homogenization to reduce the processing pressure of the high-pressure homogenizer 1.

[0041] It can be understood that in order to provide flow power for the graphene oxide slurry, the dispersion system of the graphene oxide slurry further includes a first delivery pump 7 provided on the pipeline connecting the mechanical shear dispersion unit and the buffer tank 6, a second delivery pump 8 provided on the pipeline connecting the buffer tank 6 and the high-pressure homogenizer 1, a third delivery pump 9 provided on the pipeline connecting the high-pressure homogenizer 1 and the cooling tank, and a fourth delivery pump 10 provided on the pipeline connecting the cooling tank and the defoaming treatment unit 24. In this way, the first delivery pump 7, the second delivery pump 8, the third delivery pump 9 and the fourth delivery pump 10 can provide flow power for the high-viscosity graphene oxide slurry, thereby ensuring the normal operation of the dispersion system of the graphene oxide slurry.

[0042] Exemplarily, the first delivery pump 7 , the second delivery pump 8 , the third delivery pump 9 and the fourth delivery pump 10 are all screw pumps.

[0043] For the cooling tank, the following two structures can be used:

[0044] One of the structures, specifically, see Figure 3 to Figure 4 The cooling tank includes a cooling cylinder 11, a stirring assembly 12 disposed in the cooling cylinder 11, and a stirring drive assembly 25 (for example, a stirring motor) for driving the stirring assembly 12 to rotate. In order to effectively cool the graphene oxide slurry, a high-temperature feed port 13, a low-temperature feed port 14 and a low-temperature discharge port 15 are provided on the cooling cylinder 11.

[0045] Another structure, specifically, see Figure 5The cooling tank includes an inner layer 16 of the tank body, a cooling interlayer 17 arranged on the outer wall of the inner layer 16 of the tank body, and a rotating blade 18 arranged in the inner layer 16 of the tank body. In order to effectively cool the graphene oxide slurry, a high-temperature feed port 13, a low-temperature feed port 14 and a low-temperature discharge port 15 are opened on the inner layer 16 of the tank body.

[0046] It should be noted that the temperature of the graphene oxide slurry at the high-temperature feed port 13 , the temperature of the graphene oxide slurry at the low-temperature discharge port 15 , and the temperature of the graphene oxide slurry at the low-temperature feed port 14 decrease in sequence.

[0047] In order to further adjust the temperature of the graphene oxide slurry discharged from the cooling tank, the above-mentioned graphene oxide slurry dispersion system also includes a heat exchange tank 19, a cooling medium tank 20, a temperature sensor 21, a connecting tee 22 and a tee controller 23, the connecting tee 22 has a tee feed port, a first tee discharge port and a second tee discharge port, the high-temperature feed port 13 is connected to the discharge port of the high-pressure homogenizer 1, the low-temperature discharge port 15 is connected to the tee feed port, the first tee discharge port is connected to the heat exchange tank 1 9, the slurry feed port of the heat exchange tank 19 is connected to the low-temperature feed port 14, the second three-way discharge port is connected to the feed port of the high-pressure homogenizer 1, the temperature sensor 21 is arranged on the connection pipeline between the discharge port of the cooling tank and the three-way feed port, the liquid outlet of the cooling medium tank 20 is connected to the medium inlet of the heat exchange tank 19, the medium liquid outlet of the heat exchange tank 19 is connected to the liquid inlet of the cooling medium tank 20, and the three-way controller 23 is respectively connected to the temperature sensor 21 and the connecting three-way 22.

[0048] During implementation, the temperature sensor 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 preset temperature.

[0049] 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 tank enters the heat exchange tank 19 for further cooling. After cooling, it is discharged into the cooling tank and mixed with the graphene oxide slurry in the cooling tank to cool the graphene oxide slurry in the cooling tank.

[0050] If it is lower than or equal to the threshold temperature, it means that the temperature of the graphene oxide slurry is appropriate and can be subsequently homogenized at high temperature. Then, 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.

[0051] Exemplarily, the inner layer 16 of the tank body is cylindrical in shape, and the mounting axis of the rotating blade 18 is arranged along the axial direction of the inner layer 16 of the tank body.

[0052] Taking into account the high viscosity of the graphene oxide slurry in the cooling tank, in order to avoid precipitation and stratification of the graphene oxide slurry in the cooling tank, the feeding direction of the high-temperature feed port 13 and the feeding direction of the low-temperature feed port 14 are both along the tangential direction of the tank body inner layer 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 into the tank body inner layer 16 from the high-temperature feed port 13 is the same as the swirl direction of the graphene oxide slurry flowing into the tank body inner layer 16 from the low-temperature feed port 14. 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.

[0053] Exemplarily, the angle between the feeding direction of the high-temperature feeding port 13 and the feeding direction of the low-temperature feeding port 14 is 30 to 60 degrees.

[0054] 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 layer 16 of the tank body from the low-temperature feed port 14, and the swirl power of the graphene oxide slurry in the inner layer 16 of the tank body is only powered by the graphene oxide slurry flowing into the inner layer 16 of the tank body from the high-temperature feed port 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 discharge port 15 remains basically unchanged, the heat exchange between the graphene oxide slurry and the cooling interlayer 17 is small.

[0055] 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 tank 19 for further cooling. The swirl power of the graphene oxide slurry in the inner layer 16 of the tank body is only provided by the graphene oxide slurry flowing into the inner layer 16 of the tank body from the high-temperature feed port 13 and the graphene oxide slurry flowing into the inner layer 16 of the tank body from the low-temperature feed port 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 discharge port 15 remains basically unchanged, the heat exchange rate between the graphene oxide slurry and the cooling interlayer 17 is relatively large, and the graphene oxide slurry can be fully cooled.

[0056] Considering that the temperature of subsequent graphene oxide slurry coating will affect the performance of subsequent graphene oxide film and graphene film, in order to further cool the graphene oxide slurry discharged from the defoaming treatment unit 24, the above-mentioned graphene oxide slurry dispersion system also includes a discharge pipeline 2, a coolant supply unit and a cooling controller.

[0057] Specifically, the above-mentioned discharge pipeline 2 includes an inner tube 202 and an outer tube 203 sleeved outside the inner tube 202. There is a certain size of gap between the inner tube 202 and the outer tube 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 tube 202 is provided with a heat expansion ring 204, and the inner wall of the outer tube 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 annular surface of the heat expansion ring 204 and the contact sensor 201, and the cooling controller is connected to the contact sensor 201 and the coolant supply unit.

[0058] Exemplarily, the thermal expansion ring 204 is made of Cu60Zn40, FeNi22Cr3, FeNi20Mn6, FeNi13Mn7 or Mn72Cr18Ni10.

[0059] In this way, when the temperature of the graphene oxide slurry in the discharge pipeline 2 does not exceed the temperature threshold, there is a small gap between the outer ring surface of the thermal expansion ring 204 and the contact sensor 201, and the inner tube 202 and the outer tube 203 are isolated by air, so that the cooling chamber can form air insulation, see Figure 6 .

[0060] When the temperature of the graphene oxide slurry in the discharge pipeline 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 layer tube 202. See Figure 7 .

[0061] In addition, when the temperature of the graphene oxide slurry in the discharge pipeline 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 conductive structure, so that the heat in the graphene oxide slurry can diffuse into the external environment, thereby further improving the cooling effect of the graphene oxide slurry.

[0062] 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 dispersion system of graphene oxide slurry, characterized in that: It comprises a mechanical shearing dispersion unit, a homogenizing dispersion unit and a defoaming treatment unit which are connected in sequence, wherein the homogenizing dispersion unit comprises a high-pressure homogenizer and a cooling tank which are connected in sequence from the mechanical shearing dispersion unit to the defoaming treatment unit.

2. The dispersion system of graphene oxide slurry according to claim 1, characterized in that: The number of the homogenizing and dispersing units is two groups, and the high-pressure homogenizers and cooling tanks are arranged alternately.

3. The dispersion system of graphene oxide slurry according to claim 1, characterized in that: The mechanical shearing and dispersing unit comprises a dispersing tank, and a stirring blade and a shearing and dispersing blade arranged in the dispersing tank. The rotation speed of the shearing and dispersing blade is greater than the rotation speed of the stirring blade.

4. The dispersion system of graphene oxide slurry according to claim 3, characterized in that: The stirring blade is located at the bottom of the dispersion tank; the shearing and dispersing blade is located above the stirring blade.

5. The dispersion system of graphene oxide slurry according to claim 1, characterized in that: It also includes a buffer tank, and the discharge port of the mechanical shearing and dispersing unit is connected to the feed port of the high-pressure homogenizer through the buffer tank.

6. The graphene oxide slurry dispersion system according to claim 1, characterized in that: The cooling tank comprises a cooling cylinder, a stirring assembly arranged in the cooling cylinder, and a stirring driving assembly for driving the stirring assembly to rotate.

7. The graphene oxide slurry dispersion system according to claim 1, characterized in that: The cooling tank comprises an inner layer of the tank body, a cooling interlayer arranged on the outer wall of the inner layer of the tank body, and rotating blades arranged in the inner layer of the tank body.

8. The graphene oxide slurry dispersion system according to claim 7, characterized in that: The inner layer of the tank body is in a cylindrical shape, and the mounting shaft of the rotating blade is arranged along the axial direction of the inner layer of the tank body.

9. The dispersion system of graphene oxide slurry according to any one of claims 1 to 8, characterized in that: It also includes a first delivery pump arranged on the pipeline connecting the mechanical shearing and dispersion unit and the buffer tank, a second delivery pump arranged on the pipeline connecting the buffer tank and the high-pressure homogenizer, a third delivery pump arranged on the pipeline connecting the high-pressure homogenizer and the cooling tank, and a fourth delivery pump arranged on the pipeline connecting the cooling tank and the defoaming treatment unit.

10. The graphene oxide slurry dispersion system according to claim 9, characterized in that: The first delivery pump, the second delivery pump, the third delivery pump and the fourth delivery pump are all screw pumps.

Images