Graphene oxide film, and production equipment and production method of graphene oxide film

Abstract

The invention discloses a graphene oxide film, and production equipment and a production method of the graphene oxide film. The equipment comprises a coating part, a cutting part, a drying part and a winding part. The coating part is used for coating the base material with the graphene oxide slurry; the cutting part is used for cutting the base material; the drying part comprises a drying oven, a cantilever stand column is arranged in the drying oven, a free piece capable of moving up and down is arranged on the cantilever stand column, and a storage frame of a storage layer extending transversely is fixedly arranged on the free piece; a rail in the same direction as the extending direction of the material storage layer is arranged in the drying oven, and a movable drying oven tractor is arranged on the rail and used for dragging the base material and placing the base material on the material storage layer. According to the equipment, by improving the structure of the storage rack, parallel operation of coating and drying is achieved, the problem that a traditional tunnel type drying oven stops and waits due to long drying time under the low-temperature condition is solved, the production efficiency is improved, and the cost is reduced. Meanwhile, the invention also provides a method for preparing the graphene oxide film by using the equipment and the graphene oxide film prepared by the method.

Description

Technical Field

[0001] This application relates to the field of new materials, and specifically to the field of graphene production equipment. Background Art

[0002] In the prior art, one of the ways to mass-produce graphene oxide membranes is continuous coating and drying. The drying method is multi-section oven tunnel heating and drying, and the heating method is hot air circulation heating. The heating temperature curve is divided into a preheating section and a constant temperature drying section. The temperature in the preheating section is 50 - 70°C, and the temperature in the constant temperature section is 70 - 130°C; the heating air speed is relatively high. Under high temperature and high air speed, the water evaporation rate is relatively fast, which easily causes phenomena such as cracking and curling of the film surface, and the thermal conductivity of the finally prepared graphene thermal conductive film is not good. Moreover, for the coating machine in the prior art to prepare a graphene oxide membrane dried under a lower temperature condition (≤40°C), after coating, it is necessary to wait for the wet graphene oxide film in the oven channel to dry completely before it can be wound up, and then continue to coat the graphene oxide film in the next channel and repeat the steps of drying and winding. It is impossible to achieve continuous coating, and the long waiting time for drying will increase the coating cost.

[0003] The content in the background art part is only the technology known to the inventor and does not of course represent the prior art in this field. Summary of the Invention

[0004] In view of the above problems, in the first aspect of this application, a production device for graphene oxide membranes is provided, including a coating section, a cutting section, a drying section, and a winding section. The substrate sequentially passes through the coating section, the cutting section, and the drying section and is wound up in the winding section. Among them,

[0005] The coating section is used to coat graphene oxide slurry on the substrate;

[0006] The drying section includes at least one oven. The oven is provided with an oven heater for drying the substrate coated with graphene oxide slurry; inside the oven, there is a cantilever column, and a free part that can move up and down is provided on the cantilever column. A storage rack including at least two layers of horizontally extending storage layers is fixedly arranged on the free part;

[0007] Inside the oven, there is a track in the same direction as the extension direction of the storage layer. On the track, there is a movable oven tractor for pulling the substrate coated with graphene oxide slurry and placing it in the storage layer;

[0008] The cutting section is arranged at the substrate inlet of the oven and is used to cut the substrate coated with graphene oxide slurry.

[0009] Further, the cantilever column includes a driving motor, a hydraulic pump, and a hydraulic cylinder;

[0010] The driving motor is in transmission connection with the hydraulic pump, the hydraulic pump is connected to the hydraulic cylinder through an oil pipeline, the free part is specifically a plunger, and the plunger is arranged in the hydraulic cylinder;

[0011] When the driving motor starts, the hydraulic pump injects hydraulic oil into the hydraulic cylinder, pushing the plunger upward to lift the storage rack;

[0012] When the driving motor stops, the storage rack presses the plunger to move downward under the action of its own weight, causing the hydraulic oil in the hydraulic cylinder to return to the hydraulic pump through the return pipeline.

[0013] Further, at least one support column is arranged inside the oven, a movable part that can move up and down is arranged on the support column, and the storage rack is fixedly connected to the movable part.

[0014] Further, an air inlet and an air outlet are arranged on the oven, and the oven heater is communicated with the inside of the oven at the air inlet and the air outlet respectively;

[0015] An exhaust hole is arranged at the top of the oven box body, which is used to discharge the moisture generated during the drying process of the graphene oxide wet film.

[0016] Further, the oven tractor adopts a sports car structure, and the sports car structure is divided into wheels, a transmission shaft, a braking device, a motor, and a tractor; the wheels are located on the transmission shaft, and the braking device is located inside the wheels.

[0017] Further, a feeding part is further included, and the feeding part includes a base material roller and a unwinding mechanism, and the unwinding mechanism is used to provide power for the transmission of the base material on the base material roller;

[0018] A connecting part is arranged between the feeding part and the coating part, and the connecting part is used to connect the material heads of the base materials to each other when replacing a new base material roller.

[0019] Further, the coating part includes a coating roller, a material tank, a scraper, and a gap measuring probe. The coating base material is tensioned and connected to the coating roller. The scraper is arranged adjacent to the coating roller. The scraper is on the side of the coating base material away from the coating roller, and a coating gap is formed between the scraper and the coating side of the coating base material. The material tank has a feed inlet and a discharge outlet, and the discharge outlet is correspondingly arranged with the coating side of the coating base material. An extrusion die head is arranged at the feed inlet, and the extrusion die head can extrude the graphene oxide slurry into the material tank to obtain a slurry with a flat liquid surface. The slurry in the material tank is coated on the coating base material through the action of the scraper under the pressure of its own weight to form a graphene oxide wet film with a uniform thickness;

[0020] The gap measuring probe is arranged adjacent to the coating roller and is used to measure the thickness of the graphene oxide wet film.

[0021] The second aspect of the present application provides a production method of a production device for graphene oxide membranes. The method includes: after the substrate is coated by the coating part, it enters the drying part through the cutting part. The oven tractor pulls the coated substrate and places it on the storage layer, and then the cutting part cuts the substrate; the free part on the cantilever column moves, thereby driving the storage layer to move, exposing the storage layer without the substrate placed on it. At the same time, the oven tractor returns to the cutting part to pull the head of the previously cut substrate material and re-cover the storage layer without the substrate placed on it. When the graphene oxide wet film is dried, it is wound up in the winding part, and the above process is cycled to achieve the continuous production of graphene oxide membranes.

[0022] Further, during the drying process of the graphene oxide wet film, the drying temperature is 20 - 60 °C, the drying wind speed is 1 - 10 m / s, the drying time is 0.2 - 60 h, and the coating thickness of graphene oxide is 5 - 500 μm.

[0023] The third aspect of the present application provides a graphene oxide membrane prepared by the above-mentioned production device and production method of graphene oxide membranes. It is characterized in that the grammage of the graphene oxide membrane is 30 - 300 g / cm 2 , preferably 90 - 150 g / cm 2 ;

[0024] And / or, the surface roughness Ra of the graphene oxide membrane is 0.5 - 5.0 μm; preferably 2.0 - 3.0 μm.

[0025] The principle of the present application is as follows:

[0026] By improving the structure of the storage rack in the present application, during the coating process, the coating roller works intermittently. After the substrate coated with graphene oxide material enters the drying part and covers the storage layer, the cutting part cuts the substrate, and at the same time, the coating roller pauses working. The storage layer moves up / down under the action of the motor. At the same time, the oven tractor returns to the cutting part to pull the head of the previously cut substrate material, and the coating part continues to work to re-cover the next layer of the storage rack. After completion, the cutting knife of the cutting part cuts the substrate, the storage rack moves one more layer, and the oven tractor returns to the cutting part to pull the material head for the next round of coating. Repeating this way can coat each layer of the storage layer with graphene oxide material film. At the same time, the graphene oxide membrane is dried in the drying part. After one layer is dried, it is peeled off and wound up. Repeating this way can carry out the large-scale production of graphene oxide membranes. The device for preparing graphene oxide membranes in the present application is suitable for low-temperature drying of graphene oxide. Since the drying temperature is reduced and the drying time of the graphene oxide membrane is increased, the device in the present application can make coating and drying proceed simultaneously, improving the coating efficiency of graphene oxide membranes and the low-temperature drying efficiency; reducing the cost of low-temperature drying of graphene oxide membranes.

[0027] Graphene oxide is a nanomaterial with a two-dimensional structure, and there are many oxygen-containing functional groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH) on its surface. Wrinkling is a common phenomenon in two-dimensional materials. Since the thickness of graphene oxide is atomic-level and its out-of-plane stiffness is low, it will show a wrinkled state when subjected to intermolecular or interfacial interactions. Since the rest of the graphene oxide slurry is water except for graphene oxide, graphene oxide is easily affected during the drying process of water, resulting in some changes.

[0028] When the graphene oxide dispersion is dried rapidly, the surface tension of the liquid increases rapidly, thereby generating a large capillary force on the graphene oxide nanosheets, which causes the graphene oxide film sheets to wrinkle and the distance between the sheets will also increase. The graphene thermal conductive film is prepared by thermally reducing and removing functional groups from the graphene oxide film, so the wrinkling phenomenon will be retained, which enhances the phonon scattering effect during the heat transfer process of the graphene thermal conductive film and reduces the heat transfer performance. Slow drying, on the other hand, greatly reduces the capillary force during the assembly process of graphene oxide nanosheets, making the interlayer stacking and assembly between the sheets more orderly, providing a good path for planar heat conduction, and the graphene thermal conductive film prepared by its thermal reduction has better thermal conductivity. The equipment of the present application is suitable for low-temperature drying of graphene oxide, and the graphene thermal conductive film further prepared has a higher thermal diffusion coefficient.

[0029] The technical effects obtained by the above technical solutions of the present application are as follows:

[0030] Through the synergistic effect of the multi-level storage rack driven by the cantilever column and the oven tractor, the present application realizes the parallel operation of coating and drying. When the coating roller works intermittently, the coated substrate is cut and the layer position is automatically adjusted by the storage rack, and the next layer can be coated continuously without waiting for a single layer to be completely dried. This design solves the problem of downtime waiting caused by long drying time under low temperature (≤40°C) conditions in traditional tunnel ovens, and the production efficiency is greatly improved.

[0031] The tension controller and gap measurement probe equipped in the coating section are linked by a cylinder and a motor to adjust the distance between the scraper and the coating roller in real time to ensure the uniformity of the wet film thickness. Combined with the double-sided exhaust design of the breathable substrate, the risk of film surface cracking is reduced, and the coating success rate under low-temperature drying conditions is further guaranteed.

[0032] The combined process of low-temperature drying and low-speed wind speed slows down the capillary force during the water evaporation process, enables the graphene oxide sheets to be stacked orderly, and reduces the roughness of the graphene oxide film. The graphene oxide film prepared by the technical solution of the present application, after thermal reduction, the obtained graphene thermal conductive film has a higher thermal diffusion coefficient, lower surface roughness, and reduced risk of die-cut delamination. Description of the Drawings

[0033] The accompanying drawings are used to provide a further understanding of the present application and form a part of the description. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation to the present application. In the accompanying drawings:

[0034] Figure 1 It is a schematic structural view of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0035] Figure 2 It is a front view of the drying part of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0036] Figure 3 It is a top view of the drying part of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0037] Figure 4 It is a schematic structural view of the coating part of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0038] Figure 5 It is a schematic structural view of the cutting part of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0039] Figure 6 It is a left view of the drying part of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0040] Figure 7 It is a schematic structural view of the oven tractor of the production equipment of the graphene oxide film provided by some embodiments of the present application;

[0041] Figure 8 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 2000x in Example 2;

[0042] Figure 9 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 5000x in Example 2;

[0043] Figure 10 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 20000x in Example 2;

[0044] Figure 11 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 2000x in Comparative Example 1;

[0045] Figure 12 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 5000x in Comparative Example 1;

[0046] Figure 13 It is a SEM cross-sectional view of the graphene oxide film at a magnification of 20000x in Comparative Example 1;

[0047] Figure 14 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 2000x in Example 2;

[0048] Figure 15 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 5000x in Example 2;

[0049] Figure 16 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 10000x in Example 2;

[0050] Figure 17 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 2000x in Comparative Example 1;

[0051] Figure 18 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 5000x in Comparative Example 1;

[0052] Figure 19 It is the SEM cross-sectional view of the graphene thermal conductive film at a magnification of 10000x in Comparative Example 1.

[0053] Reference numerals:

[0054] 1, Substrate;

[0055] 100, Unwinding section; 110, Substrate roller; 120, Unwinding mechanism;

[0056] 200, Connection section;

[0057] 300, Coating section; 310, Coating roller; 320, Material tank; 321, Feed inlet; 322, Discharge outlet; 323, Extrusion die head; 330, Doctor blade; 340, Gap measurement probe; 350, Swing arm; 360, Cylinder; 370, Tension controller;

[0058] 400, Cutting section; 410, Cutting knife; 420, Cutting knife roller;

[0059] 500, Drying section; 510, Oven; 511, Oven heater; 512, Cantilever column; 512-1, Free part; 512-2, Driving motor; 512-3, Hydraulic pump; 512-4, Hydraulic cylinder; 513, Storage rack; 513-1, Storage layer; 514, Track; 515, Oven tractor; 515-1, Wheel; 515-2, Transmission shaft; 515-3, Braking device; 515-4, Towing part; 516, Support column; 516-1, Moving part; 517, Air inlet; 518, Air outlet; 519, Exhaust hole;

[0060] 600, Rewinding section; Detailed implementation manners

[0061] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0062] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present application will have the meanings commonly understood by those of ordinary skill in the art. In addition, unless the context requires otherwise, singular terms shall include plural forms and plural terms shall include singular forms. More specifically, as used in this specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" include plural referents. In the present application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms (such as "including" and "containing") is not restrictive. In addition, the ranges provided in the specification and the appended claims include the endpoints and all values therebetween. The preferred embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present application and are not intended to limit the present application.

[0063] See Figures 1 to 7 , the production equipment for graphene oxide membranes provided by the first aspect of the present application includes a coating section 300, a cutting section 400, a drying section 500, and a winding section 600 arranged in sequence. The substrate 1 enters from the coating section 300 and completes the processes of coating, drying, and winding in sequence.

[0064] The coating section 300 evenly coats the graphene oxide slurry on the surface of the substrate through the cooperation of a doctor blade and a coating roller; the cutting section 400 is arranged at the substrate inlet of the drying section 500 and is used for cutting the coated substrate; the drying section 500 is internally provided with an oven having a multi-layer storage structure, and continuous drying is achieved through dynamic traction and layer position adjustment; the finally dried graphene oxide membrane is wound by the winding section 600.

[0065] Refer to Figure 2 , the drying section 500 includes at least one oven 510. An oven heater 511 is provided outside the oven 510 for drying the substrate coated with the graphene oxide slurry; a cantilever column 512 is vertically provided at the bottom inside the oven 510, and a free member 512-1 that can move up and down is provided at the top of the cantilever column 512. A storage rack 513 is fixed to the free member 512-1 and includes at least two horizontally extending storage layers 513-1. Each storage layer 513-1 is arranged in parallel and the extending direction is the same as the length direction of the oven 510.

[0066] Inside the oven 510, there is a track 514 extending in the same direction as the storage layer 513-1. On the track 514, a movable oven tractor 515 is configured. The oven tractor 515 uses a mechanical clamping mechanism to pull the cut substrate 1 from the entrance to the target storage layer. When a certain storage layer is filled with the substrate, the cutting unit 400 cuts the coated substrate. The free part 512-1 of the cantilever column 512 drives the entire storage rack 513 to rise or fall, exposing another empty storage layer. At the same time, the oven tractor 515 returns to the cutting unit 400 for a new round of pulling, forming a cyclic operation of "pulling - cutting - layer position adjustment", thereby realizing the parallel operation of coating and drying.

[0067] After the dried graphene oxide film is peeled off, it is wound by the winding unit 600. Its peeling and winding processes and related equipment involved are conventional technologies in this field, and this application will not describe them in detail.

[0068] In some embodiments, the length of the oven 510 is set to 50 - 150 m, preferably 100 m. The set length of the oven 510 can match the substrate transmission rate and the drying cycle, ensuring the uniformity of the internal heat field distribution of the oven.

[0069] In some embodiments, refer to Figure 3 , the number of ovens 510 can be adjusted according to actual production needs.

[0070] In some embodiments, the number of layers of the storage rack 513 is 5 - 50 layers, preferably 20 layers. When the number of layers is too small, the layer position switching frequency of the storage rack 513 increases, and it is necessary to wait frequently for the drying of a single layer to complete, resulting in an extended coating interruption time. When the number of layers is too large, the dried graphene oxide film cannot be wound in time, resulting in a decrease in the utilization rate of the internal space of the oven.

[0071] In some embodiments, refer to Figure 1 , the graphene oxide film production equipment is further configured with a feeding unit 100 and a connecting unit 200 to realize the continuous supply and seamless connection of the substrate. Specifically, the feeding unit 100 includes a substrate roller 110 and an unwinding mechanism 120. Among them, the substrate roller 110 is used to carry the substrate 1, and the unwinding mechanism 120 drives the transmission shaft through a servo motor to provide power for the transmission of the substrate 1. The structure of the feeding unit 100 is a conventional technology in this field, and this application will not describe it in detail.

[0072] There is a connecting unit 200 between the feeding unit 100 and the coating unit 300. Its core function is to realize the automatic connection of the new and old substrates when replacing the substrate roller 110, and the connection method is stitching or tape bonding. The structure and connection method of the connecting unit 200 also belong to conventional technologies in this field, and this application will not describe them in detail.

[0073] In some embodiments, the substrate 1 is a breathable or non-breathable substrate, preferably a breathable polypropylene textile material. During the drying process of the wet film, the breathable substrate can exhaust air on both sides, making the drying process more uniform and improving the film-forming quality.

[0074] In some embodiments, referring to Figure 4 , the coating unit 300 includes a collaborative structure of a coating roller 310, a material tank 320, a doctor blade 330, and a gap measurement probe 340, which is used to achieve precise coating of the graphene oxide slurry.

[0075] Specifically, the substrate 1 is tensioned on the surface of the coating roller 310 and is transmitted forward as the roller body rotates. The material tank 320 receives the graphene oxide slurry through the feed port 321. The extrusion die head 323 configured at the feed port 321 injects the slurry into the interior of the material tank 320 at a constant pressure to ensure a flat liquid surface. The slurry flows out from the discharge port 322 under its own weight and uniformly covers the coating side surface of the substrate 1.

[0076] The doctor blade 330 is fixed on the side of the substrate 1 away from the coating roller 310, forming a coating gap with the coating side of the substrate 1. Through the scraping action of the doctor blade 330 on the excess slurry, a graphene oxide wet film with a uniform thickness is formed, and then the graphene oxide wet film is transferred to the subsequent process steps through the guide roller.

[0077] The gap measurement probe 340 is installed on the side of the coating roller 310 to monitor the wet film thickness in real time and feed the data back to the control system. For example, when the probe detects that the film thickness deviation exceeds ±5 μm, the cylinder and motor linkage mechanism (such as a stepper motor) dynamically adjusts the height of the doctor blade 330 to correct the coating gap and ensure thickness uniformity.

[0078] In some embodiments, the adjustment mechanism of the doctor blade 330 of the coating unit 300 adopts a linkage design of a swing arm 350 and a cylinder 360 to achieve precise control of the coating gap. Specifically, the doctor blade 330 is fixed to the end of the swing arm 350 through bolts. The middle of the swing arm 350 is connected to the equipment frame through a hinge shaft, forming a lever structure; the other end of the swing arm 350 is rigidly connected to the piston rod of the cylinder 360. When the cylinder 360 receives the control signal from the control system, its piston rod expands and contracts in the vertical direction, driving the swing arm 350 to rotate around the hinge shaft, thereby driving the doctor blade 330 to move in an arc relative to the coating roller 310 to achieve dynamic adjustment of the coating gap. For example, when the cylinder 360 is inflated and pressurized, the piston rod extends and pushes the swing arm 350 to rotate counterclockwise, and the doctor blade 330 presses down to reduce the gap; when the cylinder 360 exhausts and relieves pressure, the piston rod retracts and pulls the swing arm 350 to rotate clockwise, and the doctor blade 330 lifts to increase the gap.

[0079] In some embodiments, the coating unit 300 is further configured with a tension controller 370 for precisely controlling the transmission tension of the substrate 1 on the coating roller 310 to ensure uniform coating of the graphene oxide wet film. Specifically, the tension controller 370 monitors the tension value of the substrate 1 in real time through a tension sensor and forms a closed-loop feedback system with the servo motor of the unwinding mechanism 120 and the driving unit of the coating roller 310. After the substrate 1 is output from the feeding unit 100, it enters the surface of the coating roller 310 through the guide roller group. At this time, the tension controller 370 dynamically adjusts the output torque of the unwinding mechanism 120 and the rotation speed of the coating roller 310 according to the preset tension range to achieve tension control, preventing the film surface from breaking or being damaged due to excessive tension, or uneven distribution of the wet film and affecting the thickness due to too small tension.

[0080] The above control system and control actions can be implemented by commonly used technical means in the field of control, and the present application will not elaborate on this.

[0081] In some embodiments, the coating gap is 500 - 5000 μm, preferably 2900 μm. If the thickness is too thick, the moisture escape channel is blocked, the drying is slow, and the appearance is likely to be defective. If the thickness is too low, the equipment accuracy is insufficient, and the film thickness is likely to be uneven.

[0082] In some embodiments, referring to Figure 5 , the cutting unit 400 includes a cutting knife 410 and a cutting knife roller 420. The handle end of the cutting knife 410 is fixed, and the blade end is vertically downward. The cutting knife roller 420 is arranged below the cutting knife 410, and the substrate passes through the middle of the cutting knife 410 and the cutting knife roller 420. The cutting knife roller 420 adopts a cam structure, and there are protrusions on the roller body. When the cutting knife roller 420 rotates to a certain extent, the protrusions on the cutting knife roller 420 squeeze the substrate to contact the cutting knife 410 for cutting. The rotation speed of the cutting knife roller can be adjusted according to the actual scenario requirements to achieve fixed-length cutting.

[0083] In some embodiments, referring to Figure 2 , the cantilever column 512 includes a driving motor 512-2, a hydraulic pump 512-3, a hydraulic cylinder 512-4, and a plunger 512-1, and realizes the vertical lifting of the storage rack 513 through the cooperation of the mechanical and hydraulic systems. Specifically, the output shaft of the driving motor 512-2 is rigidly connected to the input shaft of the hydraulic pump 512-3 through a coupling to form a mechanical transmission link; the hydraulic pump 512-3 is connected to the oil inlet of the hydraulic cylinder 512-4 through a high-pressure oil pipeline. There is a plunger 512-1 as a free part inside the hydraulic cylinder 512-4, and the top of the plunger 512-1 is fixedly connected to the bottom of the storage rack 513 through a flange.

[0084] When the drive motor 512-2 starts, the hydraulic pump 512-3 injects hydraulic oil into the lower chamber of the hydraulic cylinder 512-4 through the oil inlet pipeline, pushing the plunger 512-1 to move upward along the inner wall of the cylinder body, thereby lifting the storage rack 513 to the target height; when the drive motor 512-2 stops, the hydraulic pump 512-3 terminates the oil supply, and the storage rack 513 presses the plunger 512-1 to move downward under its own gravity. At this time, the hydraulic oil in the lower chamber of the hydraulic cylinder 512-4 returns to the oil storage chamber of the hydraulic pump 512-3 through the return pipeline, forming a closed cycle of the hydraulic system.

[0085] In some embodiments, the inside of the oven 510 is configured with a combined structure of support columns 516 and moving members 516-1 to improve the load-bearing stability of the storage rack 513. Specifically, the support columns 516 are vertically fixed inside the oven 510, and their surfaces are provided with slide rails or guide grooves; the moving members 516-1 are matched with the slide rails of the support columns 516 through sliders or rollers to form a connecting mechanism that can slide up and down along the axial direction of the columns. The storage rack 513 is rigidly connected to the moving member 516-1 by bolts or welding, so that the lifting action of the storage rack 513 is synchronized with the displacement of the moving member 516-1.

[0086] The number of support columns 516 can be adjusted according to the size of the storage rack 513. For example, when the length of the storage rack 513 is relatively long, two support columns 516 are symmetrically arranged inside the oven 510, respectively located at both ends of the storage rack 513 or on both sides of the middle cantilever column 512. The top of the support column 516 is fixed to the top wall of the oven 510, and the bottom is connected to the bottom plate of the oven 510 to form a stable support frame. The moving members 516-1 on different support columns 516 should be on the same horizontal line to ensure that the storage rack 513 remains horizontal when switching between multi-level storage layers.

[0087] In some embodiments, refer to Figure 6 , the oven 510 of the drying section 500 is configured with an integrated hot air circulation and moisture discharge system for efficient drying of the graphene oxide wet film. Specifically, the side walls of the oven 510 are respectively provided with an air inlet 517 and an air outlet 518, which are connected to the oven heater 511 through pipelines to form a closed loop. The hot air generated by the heating unit (such as a gas combustion chamber) of the oven heater 511 is injected into the inside of the oven 510 through the air inlet 517, evenly distributed along the extending direction of the storage layer of the storage rack 513, and performs heat exchange on the coated substrate; the airflow carrying moisture after heat exchange returns to the oven heater 511 through the air outlet 518 and re-enters the cycle after being heated. A plurality of exhaust holes 519 are arranged at intervals along the length direction of the top of the oven 510, and the exhaust holes 519 are connected to an external moisture discharge device through independent pipelines for directionally discharging the moisture generated during the drying process to prevent moisture from accumulating in the oven.

[0088] In some embodiments, referring to Figure 7 , the oven tractor 515 adopts a trolley - type moving structure, and realizes the precise traction of the base material through the synergistic action of the mechanical transmission and the braking system. Specifically, a transmission shaft 515 - 2 is provided at the bottom of the frame of the oven tractor 515. Both ends of the transmission shaft 515 - 2 are fixed through bearing seats, and are connected with the wheels 515 - 1 through key grooves to form a rigid transmission link; the power input end of the transmission shaft 515 - 2 is connected with the output shaft of a driving motor (not labeled) through a coupling, and the motor controls the rotation speed of the transmission shaft through a frequency converter. The traction member 515 - 4 is fixed on the mounting seat at the front end of the frame, and a mechanical clamping mechanism (such as a traction clip, a traction hook, a traction belt and other connecting devices) is provided at its end for clamping the head of the base material after cutting. The braking device 515 - 3 is integrated at the inner hub of the wheel 515 - 1, and realizes the rapid braking and positioning locking of the oven tractor 515 on the track through the contact friction between the brake pads and the hub.

[0089] The trolley structure of the oven tractor 515 makes a linear reciprocating motion along the track 514 arranged inside the oven. The track 514 is fixed to the oven body through bolts, and its extending direction is parallel to the storage layer. A guiding flange is provided on the surface of the track 514, and the wheel rim of the wheel 515 - 1 cooperates with the guiding flange to prevent lateral deviation during the traction process. The clamping / releasing action of the traction member 515 - 4 is driven by a cylinder, a servo motor or other appropriate means, and those skilled in the art can adjust according to the actual situation. When the oven tractor 515 moves to the cutting part, the clamping mechanism automatically opens and clamps the base material, and then the tractor moves along the track to the target storage layer to complete the laying of the base material.

[0090] The method for producing graphene oxide film provided in the second aspect of the present application realizes continuous production based on the synergistic linkage of each component of the equipment. The specific steps are as follows:

[0091] Step 1: Base material feeding and coating

[0092] The base material 1 is output from the base material roller 110 of the feeding part 100, and the unwinding mechanism 120 drives the base material to be uniformly transmitted through the connecting part 200 to the coating part 300 by a servo motor;

[0093] The coating roller 310 drives the base material 1 through the material tank 320, and the graphene oxide slurry is uniformly coated on the surface of the base material through the extrusion die head 323, and the doctor blade 330 levels the graphene oxide slurry on the surface of the base material;

[0094] The gap measurement probe 340 monitors the wet film thickness in real time and controls the lifting of the swing arm 350 of the doctor blade 330.

[0095] Step 2: Traction and laying

[0096] The coated substrate enters the drying section 500 through the cutting section 400 and is pulled by the oven tractor 515 to cover the storage layer 513-1.

[0097] Step 3: Cutting

[0098] The cutting motor of the cutting section 400 is started after the substrate 1 covers one layer of the storage layer 513-1, and drives the cutting knife to cut the substrate 1.

[0099] Step 4: Switching of the storage rack layer

[0100] When the cutting is completed, the hydraulic drive system of the cantilever column 512 is started, and the hydraulic cylinder 512-4 pushes the plunger 512-1 to lift and lower, driving the overall movement of the storage rack 513;

[0101] After the unfilled storage layer is exposed, the oven tractor 515 returns to the cutting section 400 to pull the next section of the substrate, forming a continuous laying cycle.

[0102] Step 5: Low-temperature drying and moisture discharge

[0103] The oven heater 511 injects low-temperature hot air into the oven 510 through the air inlet 517, and the moisture is discharged through the top exhaust hole 519;

[0104] The substrate is slowly dried at a low temperature on the multi-layer structure of the storage rack 513, and the graphene oxide sheets are stacked in an orderly manner.

[0105] Step 6: Finished product winding After the dried graphene oxide film is peeled off, the winding tension is adjusted by the tension controller of the winding section 600, and it is smoothly wound through the transmission roller group.

[0106] In some embodiments, during the drying process of the graphene oxide wet film, the drying temperature is 20-60 °C, such as 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, preferably 40 °C. If the temperature is too high, the drying speed is relatively fast, which is not conducive to the assembly of the GO film, and the thermal diffusion coefficient of the prepared graphene thermal conductive film is relatively low; if the temperature is too low, the coating drying cost is relatively high.

[0107] The drying wind speed is 1-10 m / s, such as 1 m / s, 2 m / s, 3 m / s, 4 m / s, 5 m / s, 6 m / s, 7 m / s, 8 m / s, 9 m / s, 10 m / s, preferably 5 m / s. If the wind speed is too high, the drying speed is relatively fast, which is not conducive to the assembly of the GO film, and the thermal diffusion coefficient of the prepared graphene thermal conductive film is relatively low; if the wind speed is too low, the coating drying cost is relatively high.

[0108] The thickness of the graphene oxide film after coating and drying is 5-500 μm, such as 5 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, preferably 150 μm.

[0109] The drying time is 0.2-60 h, such as 0.2 h, 1.0 h, 10 h, 20 h, 30 h, 40 h, 50 h, 60 h, preferably 4 h, at which the film has a moderate dryness and humidity.

[0110] The third aspect of the present application provides a graphene oxide film prepared by the production equipment and production method of the above-mentioned graphene oxide film. The grammage of the graphene oxide film is 30-300 g / cm 2 , such as 30 g / cm 2 , 100 g / cm 2 , 150 g / cm 2 , 200 g / cm 2 , 250 g / cm 2 , 300 g / cm2, preferably 90-150 g / cm 2 .

[0111] In the present application, the grammage is the surface density, which is the weight per unit area, and the unit is g / cm 2 .

[0112] The surface roughness Ra of the graphene oxide film is 0.5-5.0 μm; for example, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, etc., preferably 2.0-3.0 μm. The lower the surface roughness of the graphene oxide film, the smaller the surface roughness of the prepared graphene thermal conductivity film, and the less likely it is to delaminate during die cutting.

[0113] In some embodiments, the graphene oxide film obtained by the above embodiments of the present application can be heat-treated to prepare a graphene thermal conductivity film with a higher thermal conductivity and a lower roughness. The heat treatment process is to reduce the graphene oxide film to a graphene film at a high temperature. The heat treatment methods for reducing the graphene oxide film to a graphene film in the prior art are all applicable to the present application.

[0114] The following lists a specific heat treatment method:

[0115] The heat treatment method described in this application needs to be carried out in a vacuum or an inert atmosphere, aiming to prevent oxidizing gases in the air, such as oxygen, from re-oxidizing the already reduced graphene, thereby hindering the progress of the reduction reaction. The inert atmosphere is achieved by introducing an inert gas; the inert gas is a gas that does not react with graphene oxide and graphene, preferably one or at least a combination of 2 or more selected from nitrogen, helium, neon, argon, krypton, xenon, and radon. The combination examples include a combination of nitrogen and argon, a combination of helium and argon, a combination of neon / argon / helium, etc. Further preferably, it is nitrogen and / or argon, and most preferably nitrogen with a purity of 99.999% and / or argon with a purity of 99.99%.

[0116] Preferably, the gas flow rate of the introduced inert gas is 50 - 150 cm 3 / min. For example, 50 cm 3 / min, 60 cm 3 / min, 70 cm 3 / min, 80 cm 3 / min, 90 cm 3 / min, 100 cm 3 / min, 110 cm 3 / min, 120 cm 3 / min, 130 cm 3 / min, 140 cm 3 / min, 150 cm 3 / min, etc. Preferably, it is 100 cm 3 / min. The realization of the inert atmosphere is a technique well-known to those skilled in the art. For example, the reaction vessel can be evacuated to a high vacuum degree at one time first, and then an inert gas is introduced; or the reaction vessel can be evacuated first, and then an inert gas is introduced, and the above steps are repeated until the oxidizing gases in the reaction vessel are completely exhausted.

[0117] The thickness of the graphene thermal conductive film is 10 - 500 μm. For example, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, etc. Preferably, it is 30 - 50 μm; if the thickness is too low, it is easy to be damaged during the production and manufacturing process, and if the thickness is too high, multiple sheets need to be stacked and burned during heat treatment, and it is easy to delaminate during die-cutting.

[0118] The density of the graphene thermal conductive film is 1.8 - 2.2 g / cm 3 , for example, 1.8 g / cm 3 , 1.9 g / cm 3 , 2.0 g / cm 3 , 2.1 g / cm 3 , 2.2 g / cm3 etc., preferably 2.05 - 2.15 g / cm 3 ; If the density is too low, the thermal conductivity is relatively low;

[0119] The thermal diffusivity of the graphene thermal conductive film is 800 - 1200 mm 2 / s, for example, 800 mm 2 / s, 900 mm 2 / s, 1000 mm 2 / s, 1100 mm 2 / s, 1200 mm 2 / s, etc., preferably 850 - 950 mm 2 / s; The higher the thermal diffusivity, the better the thermal conductivity;

[0120] The surface roughness of the graphene thermal conductive film is 0.2 - 1.0 μm, for example, 0.2 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm, 1.0 μm, etc., preferably 0.5 μm; The lower the roughness, the better. If the roughness is too high, the appearance is poor, and it is not conducive to subsequent die-cutting processing.

[0121] The method for detecting roughness refers to the standard ISO 5287 - 1997.

[0122] The detection of thermal diffusivity refers to the standard ASTM E 1561.

[0123] The following are specific examples:

[0124] Example 1:

[0125] 1) Coat the graphene oxide slurry with a solid content of 5% and a viscosity of 10000 mPa·s on a substrate; The coating substrate is a polyester breathable material; The thickness of the graphene oxide slurry is 2.5 mm;

[0126] 2) Use the equipment in this application for coating, drying and winding of graphene oxide. The length of the coater is 100 m, and the number of storage layers is 20 layers; The drying temperature is 30 °C, the wind speed is 10 m / s, and the drying time is 12 h;

[0127] 3) The thickness of the prepared graphene oxide film is 100 μm, and the density is 1.5 g / cm 3 , and the surface roughness is 2.0 μm;

[0128] 5) Use the graphene oxide film in 3) to prepare a graphene thermal conductive film. The thickness of the graphene thermal conductive film is 50 μm, the density is 2.0 g / cm 3 , the thermal diffusivity is 900 mm 2 / s, and the surface roughness is 0.5 μm;

[0129] Example 2:

[0130] 1) Coat the graphene oxide slurry with a solid content of 8% and a viscosity of 26000 mPa·s on a substrate; the coating substrate is a polypropylene breathable material; the thickness of the graphene oxide slurry is 1.5 mm;

[0131] 2) Use the equipment in this application for coating, drying and winding of graphene oxide. The length of the coater is 100 m, and the number of storage layers is 20 layers; the drying temperature is 50 °C, the wind speed is 5 m / s, and the drying time is 5 h;

[0132] 3) The thickness of the prepared graphene oxide film is 100 μm, and the density is 1.5 g / cm 3 , and the surface roughness is 3.0 μm;

[0133] 5) Use the graphene oxide film in 3) to prepare a graphene thermal conductive film. The thickness of the graphene thermal conductive film is 50 μm, and the density is 2.0 g / cm 3 , and the thermal diffusivity is 900 mm 2 / s, and the surface roughness is 1.0 μm;

[0134] The cross-sectional SEM image of the graphene oxide film prepared in this example is shown in Figures 8 - 10 , and it can be seen that the graphene oxide film is assembled in an orderly manner, the layers are very tightly combined, and the wrinkles are small. The cross-sectional SEM image of the graphene film is shown in Figures 14 - 17 , and it can be seen that the graphene thermal conductive film is assembled in an orderly manner, the layers are very tightly combined, and the wrinkles are small.

[0135] Example 3:

[0136] 1) Coat the graphene oxide slurry with a solid content of 10% and a viscosity of 50000 mPa·s on a substrate; the coating substrate is an airtight PET film; the thickness of the graphene oxide slurry is 0.8 mm;

[0137] 2) Use the equipment in this application for coating, drying and winding of graphene oxide. The length of the coater is 100 m, and the number of storage layers is 20 layers; the drying temperature is 50 °C, the wind speed is 2 m / s, and the drying time is 1 h;

[0138] 3) The thickness of the prepared graphene oxide film is 60 μm, and the density is 1.8 g / cm 3 , and the surface roughness is 1.0 μm;

[0139] 5) Use the graphene oxide film in 3) to prepare a graphene thermal conductive film. The thickness of the graphene thermal conductive film is 25 μm, and the density is 2.0 g / cm 3 , and the thermal diffusivity is 1000 mm 2 / s, and the surface roughness is 0.5 μm.

[0140] Comparative Example 1:

[0141] 1) Coat the graphene oxide slurry with a solid content of 8% and a viscosity of 26000 mPa·s on a substrate; the coated substrate is a polypropylene breathable material; the thickness of the graphene oxide slurry is 1.5 mm;

[0142] 2) The coater is a traditional continuously coatable coater with a length of 100 m; the drying temperature is 100 °C, the wind speed is 20 m / s, and the drying time is 30 min;

[0143] 3) The thickness of the prepared graphene oxide film is 100 μm, and the density is 1.5 g / cm 3 , and the surface roughness is 10.0 μm;

[0144] 5) Use the graphene oxide film in 3) to prepare a graphene thermal conductive film. The thickness of the graphene thermal conductive film is 50 μm, and the density is 2.0 g / cm 3 , and the thermal diffusivity is 750 mm 2 / s, and the surface roughness is 3.0 μm.

[0145] The cross-sectional SEM image of the graphene oxide film prepared in this comparative example is shown in Figures 11 - 13 , and it can be clearly seen that the wrinkles of the graphene oxide film layers are very obvious. The cross-sectional SEM image of the graphene film is shown in Figures 17 - 19 , and it can be clearly seen that the wrinkles of the graphene thermal conductive film layers are very obvious.

[0146] It can be seen from the examples and comparative examples that in the examples, the surface roughness of the graphene oxide film dried at low temperature is reduced, the interlayer bonding is tight, the wrinkles of the graphene oxide layers are less, and the interlayer spacing is lower. In the examples of the present application, the graphene film prepared from the graphene oxide film has a higher thermal diffusivity and a lower surface roughness.

[0147] Finally, it should be noted that the above are only the preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Production equipment for graphene oxide membranes, characterized in that, It includes a coating section, a cutting section, a drying section and a winding section. The substrate passes through the coating section, the cutting section and the drying section in sequence and is wound in the winding section. The coating unit is used to coat the graphene oxide slurry on the substrate; The drying section comprises at least one oven, the oven is provided with an oven heater for drying the substrate coated with graphene oxide slurry; a cantilever column is provided inside the oven, a free part movable up and down is provided on the cantilever column, and a storage rack comprising at least two transversely extending storage layers is fixedly arranged on the free part; A track is provided inside the oven in the same direction as the extension direction of the storage layer, and a movable oven tractor is provided on the track for traction of the substrate coated with graphene oxide slurry to place it in the storage layer; The cutting part is arranged at the substrate entrance of the oven and is used for cutting the substrate coated with graphene oxide slurry.

2. The production equipment of the graphene oxide film according to claim 1, characterized in that, The cantilever column includes a driving motor, a hydraulic pump and a hydraulic cylinder; The driving motor is in driving connection with the hydraulic pump, the hydraulic pump is connected to the hydraulic cylinder through an oil pipeline, the free member is specifically a plunger, and the plunger is arranged in the hydraulic cylinder; When the drive motor is started, the hydraulic pump injects hydraulic oil into the hydraulic cylinder, pushing the plunger upward to lift the storage rack; When the drive motor stops, the storage rack presses the plunger downward under the action of its own weight, causing the hydraulic oil in the hydraulic cylinder to return to the hydraulic pump through the return pipeline.

3. The production equipment of the graphene oxide film according to claim 1, characterized in that, At least one supporting column is arranged inside the oven, a moving part which can move up and down is arranged on the supporting column, and the material storage rack is fixedly connected to the moving part.

4. The production equipment of the graphene oxide film according to claim 1, characterized in that, The oven is provided with an air inlet and an air outlet, and the oven heater is connected to the interior of the oven at the air inlet and the air outlet respectively; An exhaust hole is provided on the top of the oven body for exhausting moisture generated during the drying process of the graphene oxide wet film.

5. The production equipment of the graphene oxide film according to claim 1, characterized in that, The oven tractor adopts a sports car structure, which is divided into wheels, a transmission shaft, a brake device, a motor, and a tractor; the wheels are located on the transmission shaft, and the brake device is located inside the wheels.

6. The production equipment of the graphene oxide film according to claim 1, characterized in that, It also includes a material unloading section, the material unloading section includes a substrate roller and an unwinding mechanism, and the unwinding mechanism is used to provide power for the transmission of the substrate on the substrate roller; A connecting portion is provided between the material discharge portion and the coating portion, and the material connection portion is used to connect the material heads of the substrate to each other when a new substrate roller is replaced.

7. The production equipment of the graphene oxide film according to claim 1, characterized in that, The coating part comprises a coating roller, a material trough, a scraper and a gap measuring probe, the coating roller is tensionedly connected with the coating substrate, the scraper is arranged adjacent to the coating roller, the scraper is located on the side of the coating substrate away from the coating roller, and a coating gap is formed between the scraper and the coating side of the coating substrate, the material trough has a feed inlet and a discharge outlet, the discharge outlet is arranged corresponding to the coating side of the coating substrate, an extrusion die is arranged at the feed inlet, the extrusion die can extrude the graphene oxide slurry into the material trough to obtain a slurry with a flat liquid surface, and the slurry in the material trough is coated on the coating substrate by the action of the scraper under the pressure of its own weight to form a graphene oxide wet film with uniform thickness; The gap measurement probe is arranged adjacent to the coating roller and is used to measure the thickness of the graphene oxide wet film.

8. A production method using the production equipment for the graphene oxide film according to any one of claims 1-7, characterized in that, It includes: After the substrate is coated by the coating part, it enters the drying part through the cutting part. The oven tractor pulls the coated substrate and places it on the storage layer. Then the cutting part cuts the substrate; the free part on the cantilever column moves, which drives the storage layer to move, exposing the storage layer without the substrate placed on it. At the same time, the oven tractor returns to the cutting part to pull the base material head of the previously cut substrate and re-paves the storage layer without the substrate placed on it. When the graphene oxide wet film is dried, it is wound up in the winding part, and the above process is cycled to realize the continuous production of the graphene oxide film.

9. The production method according to claim 8, characterized in that, During the drying process of the graphene oxide wet film, the drying temperature is 20 - 60 °C, the drying wind speed is 1 - 10 m / s, the drying time is 0.2 - 60 h, and the thickness of the graphene oxide coating is 5 - 500 μm.

10. A graphene oxide membrane prepared by the production equipment of the graphene oxide membrane according to any one of claims 1-7, characterized in that, The grammage of the graphene oxide membrane is 30-300 g / cm 2 , preferably 90-150 g / cm 2 ; And / or, the surface roughness Ra of the graphene oxide film is 0.5 - 5.0 μm; preferably 2.0 - 3.0 μm.

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