A carbon nanotube film and its continuous preparation method and continuous production system

Abstract

The present invention relates to a carbon nanotube film and a continuous preparation method and a continuous production system thereof, belonging to the technical field of carbon nanotube film preparation. The continuous preparation method comprises: preparing carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, dispersant, resin, flocculant, defoamer and water; continuously spreading the carbon nanotube slurry on a circulating endless forming net, and vacuum filtering the carbon nanotube slurry to continuously form a carbon nanotube wet film; transferring the carbon nanotube wet film to a circulating endless drying net; drying the carbon nanotube wet film, and rolling up the dried carbon nanotube film to obtain a continuously rolled carbon nanotube flexible film. The present invention adds resin and flocculant to the carbon nanotube slurry, which is conducive to the formation and retention of the carbon nanotube slurry on the forming net, improves the strength and self-support of the carbon nanotube film, and is conducive to the continuous batch production of the carbon nanotube film.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon nanotube film preparation, and in particular to a carbon nanotube film and a continuous preparation method and a continuous production system thereof. Background Art

[0002] In today's environment of rapid development of electronic science and technology, the market demand for flexible, wearable and foldable electronic devices is growing rapidly, and the basic materials used to develop flexible electronic products have received extensive attention. Among them, carbon nanotubes are an ideal stress sensing material with excellent electrical, thermal and mechanical properties. When a film made of carbon nanotubes is subjected to strain, its resistance will change, and the contact state between the carbon nanotubes inside the film will also change accordingly. Therefore, this film is suitable for the manufacture of resistive pressure sensors.

[0003] At present, the main preparation methods of carbon nanotube films are divided into dry method and wet method. The dry method includes: film extraction method, LB film method, CVD method, etc., and the wet method includes: coating method, electrophoresis method, vacuum filtration method, etc. However, the carbon nanotube film prepared by the dry method has low defect content, perfect structure, and excellent performance, but the process is cumbersome and the cost is high, which cannot meet the market demand. When preparing the film by the wet method, the carbon nanotube film obtained by the coating method has a loose structure and low strength; the electrophoresis method has high requirements for the uniformity of the dispersion of carbon nanotubes in the electrolyte; the vacuum filtration method is simple and easy to operate, with high production efficiency, high raw material utilization, and uniform film.

[0004] However, when the vacuum filtration method is used to prepare carbon nanotube membranes, the carbon nanotube slurry is difficult to be formed and retained on the forming net, and the strength of the nano wet film is low, which makes it difficult to continuously and mass-produce the carbon nanotube membranes. Some existing equipment uses a supporting substrate to transport the carbon nanotube wet film during the production process, but the supporting substrate is limited in size and easily damaged, which increases the production cost and the difficulty of mass production, resulting in the inability to achieve large-scale and continuous production of carbon nanotube membranes. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a carbon nanotube membrane and a continuous preparation method and a continuous production system thereof, so as to solve the problems in the prior art that when the carbon nanotube membrane is prepared by vacuum filtration method, the carbon nanotube material is difficult to be formed and retained on the filter net, and the carbon nanotube wet film has low strength, resulting in difficulty in achieving continuous large-scale production of the carbon nanotube membrane.

[0006] On the one hand, an embodiment of the present invention provides a continuous preparation method of a carbon nanotube film, which includes: step S1, preparing a carbon nanotube slurry; wherein the carbon nanotube slurry includes: carbon nanotubes, a dispersant, a resin, a flocculant, a defoaming agent and water; step S2, continuously spreading the carbon nanotube slurry on a circulating endless forming net, and vacuum filtering the carbon nanotube slurry to continuously form a carbon nanotube wet film; step S3, transferring the carbon nanotube wet film to a circulating endless drying net; step S4, drying the carbon nanotube wet film, and rolling up the dried carbon nanotube film to obtain a continuously rolled carbon nanotube flexible film.

[0007] Furthermore, in terms of mass percentage, in addition to the solvent, the carbon nanotube slurry includes: 40% to 60% carbon nanotubes, 10% to 20% dispersant, 10% to 20% resin, 10% to 20% flocculant, and 3% to 6% defoaming agent.

[0008] Furthermore, the resin adopts a water-soluble resin emulsion, and the resin emulsion includes at least one of a water-soluble polyurethane emulsion, an acrylic emulsion, and a styrene-butadiene emulsion.

[0009] Furthermore, the flocculant includes at least one of ferrous sulfate, magnesium sulfate, potassium aluminum sulfate dodecahydrate, polyaluminum chloride, and ferric chloride.

[0010] Furthermore, in step S3, the carbon nanotube wet film is transferred to a circulating endless drying net by a top net transfer system; the top net transfer system is arranged between the endless forming net and the endless drying net, and the top net transfer system transfers the carbon nanotube wet film from the endless forming net to the endless drying net by suction.

[0011] Furthermore, the top mesh transfer system includes a cyclically movable endless top mesh and a first top mesh vacuum assembly; in step S3, when the endless forming mesh drives the carbon nanotube wet film to move to a position intersecting with the endless top mesh, the carbon nanotube wet film is sucked by the first top mesh vacuum assembly to transfer the carbon nanotube wet film from the endless forming mesh to the endless top mesh.

[0012] Furthermore, a vibration device and two groups of first blowing devices are sequentially arranged along the moving direction of the endless forming net; in step S3, when the first top net vacuum assembly sucks the carbon nanotube wet film, the carbon nanotube wet film is vibrated and blown respectively by the vibration device and the first blowing device, and the carbon nanotube wet film is assisted to be transferred to the endless top net under the action of vibration and blowing.

[0013] Furthermore, a first drying vacuum assembly is provided on the side of the endless drying net away from the carbon nanotube wet film; in step S3, when the endless top net drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net, the carbon nanotube wet film is sucked by the first drying vacuum assembly to transfer the carbon nanotube wet film from the endless top net to the endless drying net.

[0014] Furthermore, a slurry spreading system is arranged above the endless forming net, and an outlet of the slurry spreading system is overlapped on the endless forming net; in step S2, the carbon nanotube slurry is continuously spread on the circulating endless forming net through the slurry spreading system.

[0015] On the other hand, an embodiment of the present invention provides a carbon nanotube film, which is prepared by the continuous preparation method in the above embodiment, the thickness of the carbon nanotube film is 30-500 μm, and the surface density of the carbon nanotube film is 20-200 g / m 2 .

[0016] On the other hand, an embodiment of the present invention also provides a continuous production system for carbon nanotube film, which is used to implement the continuous preparation method of the above embodiment, and includes: a grinding and pulping system, a slurry spreading system, a vacuum forming system, a top mesh transfer system, a drying system and a winding device; the grinding and pulping system is used to prepare carbon nanotube slurry; the slurry spreading system is connected to the grinding and pulping system, the slurry spreading system is located above the vacuum forming system and is connected to the vacuum forming system, and is used to spread the carbon nanotube slurry on the vacuum forming system; the vacuum forming system is used to filter the moisture in the carbon nanotube slurry to obtain a carbon nanotube wet film; the top mesh transfer system is arranged between the vacuum forming system and the drying system, and is arranged to transfer the carbon nanotube wet film from the vacuum forming system to the drying system through suction; the drying system is used to dry the carbon nanotube wet film to obtain a carbon nanotube film; the winding device is connected to the drying system, and is used to wind up the dried carbon nanotube film.

[0017] The continuous preparation method and production system of the carbon nanotube film according to the embodiment of the present invention can achieve at least one of the following beneficial effects:

[0018] 1. When the present invention adopts the vacuum filtration method to produce carbon nanotube film, the continuous carbon nanotube wet film is directly supported by the endless forming net that moves in a circular motion. The carbon nanotube wet film is directly transferred to the endless drying net and dried. The prepared carbon nanotube film can be rolled into a roll to achieve the continuous preparation of the carbon nanotube film; and there is no need to consume the supporting substrate to assist the production, and the production volume of the carbon nanotube film is not limited by the size of the supporting substrate. In addition, the present invention adds resin and flocculant to the carbon nanotube slurry, which is conducive to the formation and retention of the carbon nanotube material on the endless forming net, improves the strength and self-support of the carbon nanotube film, and further ensures the continuous film formation of the carbon nanotube slurry on the endless forming net, thereby realizing the large-scale industrial production of carbon nanotube flexible films in large quantities, continuously, at low cost and with high efficiency.

[0019] 2. The present invention uses a forming net and a drying net to carry and process carbon nanotube films of different dryness, thereby increasing the life of each net and reducing production costs.

[0020] 3. The present invention optimizes the formula of carbon nanotube slurry so that the carbon nanotubes, resin, flocculant and other ingredients are within a suitable range. While improving the deposition rate of the carbon nanotube material on the forming net and the strength of the carbon nanotube film, it can ensure that the prepared carbon nanotube film has good electrical conductivity.

[0021] 4. The present invention utilizes the top net transfer system to transfer the carbon nanotube wet film from the endless forming net to the endless drying net through suction, so that the carbon nanotube wet film can be easily separated from the forming net and transferred, which is beneficial to the continuous preparation of the carbon nanotube film.

[0022] 5. The thickness and surface density of the carbon nanotube film prepared by the present invention are adjustable, and it has excellent electrical conductivity, thermal conductivity, flexibility and other properties. It can be widely used as a material for preparing electronic devices such as flexible sensors, supercapacitors, and heating materials.

[0023] 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 description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components;

[0025] Figure 1 A schematic diagram of a process for continuously preparing a carbon nanotube film according to some embodiments of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a carbon nanotube film continuous production system according to some embodiments of the present invention;

[0027] Figure 3 A schematic diagram of the structure of a headbox in a continuous production system in some embodiments of the present invention;

[0028] Figure 4 This is a physical picture of the carbon nanotube film prepared in Example 1 of the present invention.

[0029] Description of reference numerals:

[0030] 10-grinding pulping system; 21-high-level box; 22-heading box; 221-inlet; 222-outlet; 223-first water baffle; 224-second water baffle; 225-regulating valve; 30-vacuum forming system; 31-endless forming net; 311-transmission roller; 32-forming vacuum assembly; 33-vibration device; 34-first blowing device; 40-top net transfer system; 41-endless top net; 42-top net vacuum assembly; 43-second blowing device; 50-wet pressing roller; 60-drying system; 61-endless drying net; 62-drying vacuum assembly; 63-drying device; 64-dry pressing roller; 70-winding device; 1-carbon nanotube film. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification.

[0032] It is also necessary to explain here that, in order to avoid obscuring the present invention due to unnecessary details, only the device structure and / or processing steps closely related to the solution according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0033] The embodiment of the present invention provides a continuous preparation method of a carbon nanotube film, such as Figure 1 As shown, the method comprises the following steps:

[0034] Step S1, preparing carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, a dispersant, a resin, a flocculant and a defoaming agent.

[0035] Step S2, spreading the carbon nanotube slurry on the endless forming net that moves in a circular motion, and performing vacuum filtration on the carbon nanotube slurry to form a carbon nanotube wet film continuously.

[0036] Step S3, transferring the carbon nanotube wet film to an endless drying net.

[0037] Step S4, drying the carbon nanotube wet film, and rolling up the dried carbon nanotube film to obtain a continuously rolled carbon nanotube flexible film.

[0038] The embodiments of the present invention directly support continuous carbon nanotube wet film through a circulating and endless forming net, thereby realizing continuous preparation of carbon nanotube film; and there is no need to consume supporting substrates to assist production, and the production volume of carbon nanotube film is not limited by the size of the supporting substrate, which is conducive to continuous and large-scale production of carbon nanotube film, and has simple operation, low cost and high efficiency.

[0039] In addition, the present invention uses an endless forming net and an endless drying net to carry carbon nanotube films of different dryness, thereby increasing the life of each net and helping to reduce production costs. It should be noted that the endless forming net in the present invention refers to a forming net with two ends connected along the length direction; the endless drying net refers to a drying net with two ends connected along the length direction.

[0040] The present invention adds resin and flocculant to the carbon nanotube slurry, which is beneficial to the formation and retention of carbon nanotube materials on the endless forming net, improves the strength and self-support of the carbon nanotube film, and further ensures the continuous film formation of the carbon nanotube slurry on the endless forming net.

[0041] In some embodiments, in addition to the solvent, the carbon nanotube slurry includes, by mass percentage, 40% to 60% carbon nanotubes, 10% to 20% dispersant, 10% to 20% resin, 10% to 20% flocculant, and 3% to 6% defoamer, and the sum of each component is 100%. The concentration of carbon nanotubes in the carbon nanotube slurry is controlled at 0.1 to 10%.

[0042] The more carbon nanotubes there are, the stronger the conductivity of the carbon nanotube film is; the flocculant can work synergistically with the resin emulsion to improve the retention of the carbon nanotube slurry on the forming net and increase the strength of the carbon nanotube film. The embodiments of the present invention can ensure that the obtained carbon nanotube film has excellent conductivity and strength by controlling the content of carbon nanotubes, resin emulsion and flocculant.

[0043] In some embodiments, the content of resin and flocculant is 1:0.9~1.1, preferably 1:1, so that the resin emulsion reacts with the flocculant to form a combined structure of "carbon nanotube particles-blenderized emulsion", which is beneficial to the formation and retention of the carbon nanotube slurry on the forming net and improves the strength of the carbon nanotube film.

[0044] The carbon nanotubes are single-walled carbon nanotubes or multi-walled carbon nanotubes. The single-walled carbon nanotubes have a diameter of 0.4-2 nm and a length of 1-500 μm, preferably a diameter of 0.4-2 nm and a length of 20-200 μm; the multi-walled carbon nanotubes have a diameter of 2-100 nm and a length of 1-500 μm, preferably a diameter of 2-20 nm and a length of 20-200 μm.

[0045] In some embodiments, the dispersant is at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, anionic polyacrylamide, polyethylene oxide, polyvinyl pyrrolidone, and carboxylated nanocellulose. Carbon nanotubes are difficult to disperse due to the presence of van der Waals forces. In the embodiments of the present invention, the above dispersant is added to disperse the carbon nanotubes under the action of grinding, ultrasound, etc., so as to give full play to the conductive properties of the carbon nanotubes.

[0046] In some embodiments, the defoaming agent is at least one of a silicone defoaming agent and a polyether defoaming agent, which can effectively reduce the foam generated by the dispersant during the stirring process.

[0047] In some embodiments, the resin is a water-soluble resin emulsion, and the content of the resin in the resin emulsion is 45-55%. The resin emulsion includes at least one of a water-soluble polyurethane emulsion, an acrylic emulsion, and a styrene-butadiene emulsion.

[0048] In some embodiments, the flocculant includes at least one of ferrous sulfate, magnesium sulfate, potassium aluminum sulfate dodecahydrate, polyaluminum chloride, and ferric chloride.

[0049] In step S1, when preparing carbon nanotube slurry, firstly, carbon nanotubes and dispersant are mixed in water, and then ground or ultrasonically dispersed, and a defoaming agent is added to the carbon nanotube dispersion to eliminate foam, thereby obtaining a carbon nanotube dispersion.

[0050] Then, add the resin emulsion to the carbon nanotube dispersion and mix and stir, then add the flocculant and stir and mix. The flocculant is used to destroy the emulsion particle structure to form a combined structure of "carbon nanotube particles-fluffed emulsion", which is conducive to the formation and retention of the carbon nanotube slurry on the forming net and improves the strength of the formed carbon nanotube film.

[0051] In some embodiments, in step S1 , a grinding and pulping system may be used to prepare carbon nanotube slurry, and the carbon nanotube slurry is ground and dispersed by the grinding and pulping system to obtain a uniformly dispersed carbon nanotube slurry.

[0052] In some embodiments, a slurry spreading system is arranged above the endless forming net, and the outlet of the slurry spreading system is overlapped on the endless forming net. In step S2, the carbon nanotube slurry can be continuously spread on the endless forming net that moves in a circular motion by the slurry spreading system, so as to form a film continuously, which can reduce the risk of not being able to form a film continuously compared with the spraying method.

[0053] In some embodiments, the stock distribution system includes a headbox, which can provide a stable and uniform transverse stock flow distribution for the endless forming wire.

[0054] In some embodiments, Figure 3 As shown, the headbox 22 can be a top-open headbox, whose inlet 221 is arranged at the bottom of the headbox, and the outlet 222 is arranged on the side of the headbox 22, and the interior of the headbox 22 is provided with a first water baffle 223 and a second water baffle 224, and the first water baffle 223 and the second water baffle 224 are sequentially arranged on one side of the outlet 222 of the headbox 22 along the outlet direction of the carbon nanotube slurry, and the outlet 222 is formed between the headbox 22 and the bottom.

[0055] In step S2, the carbon nanotube slurry can be continuously transported from the bottom inlet 221 of the slurry box 22 to the cavity of the slurry box 22, so that it flows through the lower outlets of the first water baffle 223 and the second water baffle 224 in turn and flows onto the circulating endless forming net, providing the endless forming net with a continuous, stable and uniform lateral slurry flow.

[0056] In some embodiments, regulating valves 225 are respectively provided on the top of the first water baffle 223 and the second water baffle 224. Before starting to spread the slurry in step S2, the distance between the first water baffle 223 or the second water baffle 224 and the bottom can be adjusted by rotating the regulating valve 225 to prepare carbon nanotube wet films of different thicknesses.

[0057] In some embodiments, a plurality of forming vacuum assemblies are arranged along the moving direction of the endless forming net, and the forming vacuum assemblies are located on the side of the endless forming net away from the carbon nanotube wet film. In step S2, the carbon nanotube slurry spread on the endless forming net can be vacuum filtered by the forming vacuum assemblies to form a continuous carbon nanotube wet film.

[0058] In some embodiments, when vacuum filtering is performed on the carbon nanotube slurry in step S2, the vacuum degree of the plurality of vacuum forming components is controlled to be -0.08 to -0.04 MPa to extract part of the water in the carbon nanotube slurry.

[0059] The embodiments of the present invention control the forming vacuum assembly at an appropriate vacuum degree, which can slowly extract the moisture in the carbon nanotube slurry to prepare a carbon nanotube wet film; if the vacuum degree is too small, the obtained carbon nanotube wet film will have a larger moisture content and a thicker thickness, affecting the rolling effect; if the vacuum degree is too large, on the one hand, the resin component in the carbon nanotube slurry will be extracted, thereby reducing the strength of the prepared carbon nanotube film; on the other hand, the carbon nanotube wet film will be closely attached to the forming net, resulting in its inability to be completely transferred to the top net.

[0060] In some embodiments, after the carbon nanotube slurry is formed by vacuum filtration, the formed carbon nanotube wet film can be rolled by a wet pressing roller to accelerate the dehydration of the carbon nanotube wet film and reduce the film thickness.

[0061] In some embodiments, the roller spacing of the wet pressing rollers can be controlled to be 50-90% of the thickness of the carbon nanotube wet film, which can effectively roll and dehydrate the carbon nanotube wet film, reduce the wear of the carbon nanotube wet film caused by rolling, and avoid the carbon nanotube film from being too thin.

[0062] In some embodiments, in step S3, the carbon nanotube wet film can be transferred to a circulating endless drying net by a top net transfer system; wherein the top net transfer system is arranged between the endless forming net and the endless drying net, and the top net transfer system transfers the carbon nanotube wet film from the endless forming net to the endless drying net by suction. Compared with transferring the carbon nanotube film by a pressing roller, the present invention transfers the carbon nanotube wet film by suction, which makes it easier for the carbon nanotube wet film to separate from the endless forming net and adhere to the target net.

[0063] Specifically, Figure 2 As shown, the top wire transfer system 40 is disposed between the endless forming wire 31 and the endless drying wire 61. In some embodiments, the top wire transfer system 40 includes an endless top wire 41, and different positions of the endless top wire 41 intersect with the endless forming wire 31 and the endless drying wire 61 respectively.

[0064] In step S3, the carbon nanotube wet film is transferred, which includes: when the endless forming net 31 drives the carbon nanotube wet film to move to the position where it intersects with the endless top net 41, the carbon nanotube wet film is transferred to the endless top net 41 by suction; when the endless top net 41 drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net 61, the carbon nanotube film is transferred to the endless drying net 61 by suction. The present invention uses the endless top net 41 as a bridge to smoothly transfer the carbon nanotube wet film from the endless forming net to the unconnected endless drying net.

[0065] In some embodiments, Figure 2 As shown, the top web transfer system 40 includes a first top web vacuuming component 42, and the first top web vacuuming component 42 is disposed on a side of the endless top web 41 away from the carbon nanotube wet film.

[0066] In step S3 , when the endless forming web 31 drives the carbon nanotube wet film to move to the position intersecting with the endless top web 41 , the carbon nanotube wet film is sucked by the first top web vacuum assembly 42 to transfer the carbon nanotube wet film from the endless forming web 31 to the endless top web 41 .

[0067] In some embodiments, the vacuum degree of the first top net vacuum pumping assembly 42 can be controlled to be -0.2~-0.8MPa. The embodiment of the present invention controls the first top net vacuum pumping assembly 42 at a suitable vacuum degree, and can transfer the carbon nanotube wet film to the endless top net 41 by suction, and avoid excessive vacuum, which causes the wet film to cling to the top net and cannot be transferred to the drying net.

[0068] In some embodiments, the top net transfer system further includes a second top net vacuum pumping assembly, which is located downstream of the first top net vacuum pumping assembly. After the carbon nanotube wet film is transferred to the endless top net 41, the carbon nanotube wet film can be further vacuum filtered and dehydrated by the second top net vacuum pumping assembly. Preferably, during the production process, the vacuum degree of the second top net vacuum pumping assembly can be controlled to be -0.1~-0.4MPa.

[0069] In some embodiments, Figure 2 As shown, a vibration device 33 and two groups of first blowing devices 34 are sequentially arranged along the moving direction of the endless forming net 31.

[0070] In step S3, when the first top net vacuuming component 42 sucks the carbon nanotube wet film, the carbon nanotube wet film can also be vibrated and blown by the vibration device 33 and the first blowing device 34, respectively, and the carbon nanotube wet film is assisted to be transferred to the endless top net 41 under the action of vibration and blowing. The present invention simultaneously vibrates, blows and sucks the carbon nanotube wet film, so that the carbon nanotube film is easily separated from the endless forming net and transferred and attached to the endless top net, with a good transfer effect and simple and convenient operation.

[0071] In some embodiments, when the vibration device 33 is used to assist in transferring the carbon nanotube wet film, the vibration pressure of the vibration device 33 in the vacuum forming system 30 is controlled to be 0.1-0.4 MPa to assist in transferring the carbon nanotube wet film to the top net. If the vibration pressure is too high, the carbon nanotube wet film will be shattered; if the vibration pressure is too low, the purpose of assisting the carbon nanotube wet film to separate from the forming net cannot be achieved.

[0072] In some embodiments, when the first blowing device 34 is used to assist in the transfer of the carbon nanotube wet film, the blowing pressures of the two groups of first blowing devices 34 arranged in sequence along the moving direction of the endless forming web 31 can be controlled to be 0.1-0.2 Mpa and 0.08-0.16 Mpa, respectively. If the blowing pressure is too high, the carbon nanotube wet film will be blown apart, and if the pressure is too low, the purpose of assisting the transfer cannot be achieved.

[0073] In some embodiments, Figure 2 As shown, a first drying vacuum assembly 62 is disposed on the side of the endless drying web 61 away from the carbon nanotube wet film.

[0074] In step S3 , when the endless top web 41 drives the carbon nanotube wet film to move to the position where it intersects with the endless drying web 61 , the carbon nanotube wet film is sucked by the first drying vacuum assembly 62 to transfer the carbon nanotube wet film from the endless top web 41 to the endless drying web 61 .

[0075] In some embodiments, the vacuum degree of the first drying vacuum assembly 62 can be controlled to be -0.4~-1MPa. In the embodiment of the present invention, the first drying vacuum assembly 62 is controlled at an appropriate vacuum degree to avoid the vacuum being too low and thus failing to transfer smoothly, and to avoid the vacuum being too high and thus causing the wet film to break or cling to the drying net and failing to separate in the subsequent process.

[0076] In some embodiments, a second drying vacuum assembly is further provided downstream of the first drying vacuum assembly. After the wet carbon nanotube film is transferred to the endless drying net 61, the carbon nanotube film can be further filtered and dehydrated by the second drying vacuum assembly. In some embodiments, the vacuum degree of the second drying vacuum assembly can be controlled to be -0.2 to -0.8 MPa.

[0077] In some embodiments, Figure 2 As shown, the top web transfer system 40 further includes a second blowing device 43, which is located at a position corresponding to the endless drying web 61. When the first drying vacuum assembly 62 is sucking the carbon nanotube wet film, the second blowing device 43 can also be used to blow air on the carbon nanotube film to assist in transferring the carbon nanotube film to the endless drying web 61.

[0078] In some embodiments, the blowing pressure of the second blowing device can be controlled to be 0.2-0.4 Mpa to avoid excessive blowing pressure, which may cause the carbon nanotube wet film to be broken; and to avoid too low pressure, which may fail to assist transfer.

[0079] In some embodiments, two drying devices are arranged along the moving direction of the endless drying web. In step S4, the carbon nanotube wet film may be dried by the drying devices.

[0080] In some embodiments, the drying temperatures of two drying devices arranged in sequence along the moving direction of the endless drying web can be controlled to be 80-100° C. and 90-150° C., respectively. After the first drying device performs preliminary drying at a lower drying temperature, the second drying device performs drying at a higher drying temperature to ensure that the carbon nanotube film is completely dried.

[0081] In some embodiments, before the carbon nanotube wet film is completely dried, the carbon nanotube wet film can be rolled by a dry pressing roller to reduce the thickness of the carbon nanotube film. Specifically, the carbon nanotube wet film can be rolled after the carbon nanotube wet film is initially dried to reduce the film thickness.

[0082] In some embodiments, the roller gap of the dry press roller can be controlled to be 50-90% of the thickness of the carbon nanotube wet film, and the thickness of the final carbon nanotube film can be controlled by controlling the roller gap of the dry press roller.

[0083] In some embodiments, during the continuous production of carbon nanotube film, the speed of the endless forming web is controlled to be 0.5~10 m / min, the speed of the endless top web is controlled to be 0.6~11 m / min, and the speed of the endless drying web is controlled to be 0.7~12 m / min, and the speeds of the endless forming web, the endless top web, and the endless drying web are basically the same or gradually increase, and the speed difference is 0.05~0.5 m / min.

[0084] In the continuous production process, since the carbon nanotube wet film is stretched after being dehydrated step by step or even dried, the embodiment of the present invention controls the speed of each system to be v 干燥网 ≥v 顶网 ≥v 成型网 , and the difference is not big. If the overall vehicle speed is too high, firstly, the dehydration effect of the carbon nanotube wet film will be weakened; secondly, during the transfer, the blowing force of the blowing device per unit time is insufficient, which may easily lead to unsuccessful transfer; finally, during drying, the carbon nanotube wet film cannot be completely dried if the vehicle speed is too high. If the vehicle speed is too low, it will greatly affect the production efficiency and cause energy waste. Secondly, during the transfer, the carbon nanotube film will be vibrated for a longer time, which will cause the carbon nanotube film to be broken. Therefore, the embodiment of the present invention controls the vehicle speed of each network within an appropriate range.

[0085] In some embodiments, the thickness of the obtained carbon nanotube film can be adjusted by regulating the ratio of each component in the carbon nanotube slurry, the concentration of the slurry, the distance between the water baffle and the bottom of the headbox, the speed of each mesh, and the gap between the pressing rollers.

[0086] In some embodiments, the surface density of the prepared carbon nanotube film can be adjusted by regulating the ratio of each component in the carbon nanotube slurry, the concentration of the slurry, the distance between the water baffle and the bottom of the headbox, and the speed of each net.

[0087] The embodiment of the present invention further provides a carbon nanotube film, which can be prepared by the continuous preparation method of the above embodiment, the thickness of the carbon nanotube film is 30-500 μm, and the surface density of the carbon nanotube film is 20-200 g / m 2 Preferably, the thickness of the carbon nanotube film is 30-150 μm, and the surface density is 30-80 g / m 2 .

[0088] The thickness and surface density of the carbon nanotube film prepared by the present invention are adjustable, and it has excellent electrical conductivity, thermal conductivity, flexibility and other properties, and can be widely used as a material for preparing electronic devices such as flexible sensors, supercapacitors, and heating materials.

[0089] The embodiment of the present invention also provides a continuous production system of carbon nanotube film, such as Figure 2 As shown, it includes: a grinding pulping system 10, a pulp spreading system, a vacuum forming system 30, a top net transfer system 40, a drying system 60 and a winding device 70. The grinding pulping system 10 is used to prepare carbon nanotube slurry, the pulp spreading system is connected to the grinding pulping system 10, the pulp spreading system is located above the vacuum forming system 30 and connected to the vacuum forming system 30, and is used to spread the carbon nanotube slurry on the vacuum forming system 30. The vacuum forming system 30 is used to filter the moisture in the carbon nanotube slurry to obtain a carbon nanotube wet film, the top net transfer system 40 is arranged between the vacuum forming system 30 and the drying system 60, and is arranged to transfer the carbon nanotube wet film from the vacuum forming system 30 to the drying system 60 by suction. The drying system 60 is used to dry the carbon nanotube wet film to obtain a carbon nanotube film, and the winding device 70 is used to wind up the dried carbon nanotube film.

[0090] The continuous production system provided by the present invention forms carbon nanotubes through a grinding and pulping system, a pulping system, and a vacuum forming system that are connected in sequence, and then a top net transfer system is used to transfer the carbon nanotube wet film from the vacuum forming net to a drying system through suction, so that the carbon nanotube wet film can be easily separated from the forming net and transferred to the drying net for drying, which is beneficial to the continuous preparation of carbon nanotube films.

[0091] In some embodiments, Figure 2 As shown, the slurry distribution system includes a high-level box 21 and a flow box 22. The high-level box 21 is used to temporarily store the carbon nanotube slurry. Its inlet is connected to the grinding and pulping system 10, and its outlet is connected to the inlet of the flow box 22. The outlet of the flow box 22 is connected to the vacuum forming system 30. The flow box 22 is used to homogenize and rectify the carbon nanotube slurry and spread it flat on the forming net of the vacuum forming system 30.

[0092] Some existing production equipment uses a spraying method to apply carbon nanotube slurry, which poses a risk of not being able to form a film continuously. In contrast, the continuous production system of the present invention uses a process of overlapping an endless forming net with a flow box, so that the carbon nanotube slurry is continuously spread on the forming net, thereby achieving continuous film formation of the carbon nanotube slurry and reducing the risk of discontinuous film formation of the carbon nanotube slurry.

[0093] like Figure 2As shown, the high-level box 21 is located above the entire production system, and a transmission pump is connected between the grinding and pulping system 10 and the high-level box 21. The carbon nanotube slurry is pumped into the high-level box 21 through the transmission pump, and the carbon nanotube slurry in the high-level box 21 flows into the slurry box 22 by gravity.

[0094] In some embodiments, Figure 3 As shown, the headbox 22 is a top-open headbox, whose inlet 221 is arranged at the bottom of the headbox, and the outlet 222 is arranged at the side of the headbox 22, and the first water baffle 223 and the second water baffle 224 are arranged inside the headbox 22, and the first water baffle 223 and the second water baffle 224 are sequentially arranged on one side of the outlet 222 of the headbox 22 along the outlet direction of the carbon nanotube slurry, and the outlet 222 is formed between the first water baffle 223 and the second water baffle 224 and the bottom of the headbox 22. The carbon nanotube slurry flows into the cavity of the headbox 22 from the inlet 221 at the bottom of the headbox 22, and then flows through the lower outlets of the first water baffle 223 and the second water baffle 224 in sequence and flows into the vacuum forming system 30. By arranging the first water baffle 223 and the second water baffle 224, a stable and uniform lateral slurry flow distribution can be provided for the vacuum forming system 30.

[0095] In some embodiments, the distance between the first water baffle 223 and the bottom of the headbox 22 is 2-6 cm, and the distance between the second water baffle 223 and the bottom of the headbox 22 is 1-20 mm, which is used to control the thickness of the carbon nanotube wet film.

[0096] In some embodiments, a regulating valve 225 is disposed on the top of the first water baffle plate 223 and the second water baffle plate 224 , respectively. The height of the first water baffle plate 223 or the second water baffle plate 224 can be adjusted by rotating the regulating valve 225 to obtain carbon nanotube wet films of different thicknesses.

[0097] like Figure 2 As shown, in some embodiments, the vacuum forming system 30 includes: an endless forming net 31, and multiple forming vacuum pumping components 32. The endless forming net 31 can move cyclically, and the slurry spreading system is used to spread the carbon nanotube slurry on the endless forming net 31. The multiple forming vacuum pumping components 32 are sequentially arranged on the side of the endless forming net 31 away from the carbon nanotube wet film along the moving direction of the endless forming net 31, and the endless forming net 31 is used to drive the carbon nanotube wet film to pass through the multiple forming vacuum pumping components 32 in sequence. The forming vacuum pumping components 32 are used to vacuum filter the carbon nanotube slurry, extract part of the water in the carbon nanotube slurry, and form the carbon nanotube slurry to obtain the carbon nanotube wet film. Preferably, there are at least 4 forming vacuum pumping components.

[0098] Specifically, the endless forming net 31 is supported and driven to move by a plurality of transmission rollers 311, for example, Figure 2As shown, four transmission rollers support the endless forming mesh 31 and drive it to move cyclically along a rectangular path.

[0099] In some embodiments, the headbox 22 is disposed above the endless forming net 31, and the outlet 222 of the headbox 22 overlaps the endless forming net 31, and the moving direction of the endless forming net 31 is the same as the flow direction of the carbon nanotube slurry at the outlet of the headbox 22. When the carbon nanotube slurry flows from the headbox 22 to the endless forming net 31, the carbon nanotube slurry is flattened on the endless forming net 31 under the movement of the endless forming net 31, so as to obtain a continuous carbon nanotube wet film.

[0100] Furthermore, at least a portion of the plurality of forming vacuum assemblies 32 are disposed at positions corresponding to the headbox 22 , and the forming vacuum assemblies 32 perform vacuum filtration on the carbon nanotube slurry, thereby filtering out moisture in the carbon nanotube slurry to form a carbon nanotube wet film.

[0101] like Figure 2 As shown, in some embodiments, the vacuum forming system 30 and the drying system 60 are arranged in parallel, and the top web transfer system 40 is arranged above the vacuum forming system 30 and the drying system 60, and intersects with the vacuum forming system 30 and the drying system 60 respectively. The top web transfer system 40 serves as a bridge for transferring the carbon nanotube wet film, and transfers the carbon nanotube film on the endless forming web 31 to the drying system 60 through suction.

[0102] In some embodiments, Figure 2 As shown, the top mesh transfer system 40 includes an endless top mesh 41 and multiple groups of top mesh vacuum assemblies 42. The endless top mesh 41 can move cyclically, and the multiple groups of top mesh vacuum assemblies 42 are sequentially arranged on the side of the endless top mesh 41 away from the carbon nanotube wet film along the moving direction of the endless top mesh 41. The endless top mesh 41 is used to carry the carbon nanotube wet film and drive the carbon nanotube wet film to pass through the multiple groups of top mesh vacuum assemblies 42 in sequence. Among them, at least a part of the multiple groups of top mesh vacuum assemblies 42 are arranged at a position corresponding to the endless forming mesh 31 of the vacuum forming system 30, and are located downstream of the multiple groups of forming vacuum assemblies 32. The multiple groups of top mesh vacuum assemblies 42 are at least used to transfer the carbon nanotube wet film on the endless forming mesh 31 to the endless top mesh 41 by suction.

[0103] Specifically, the endless top net 41 is supported and driven to move by a plurality of transmission rollers, for example, Figure 2 As shown, a plurality of transmission rollers support the endless top web 41 and drive it to move cyclically along a rectangular path. Part of the endless top web 41 intersects with one side of the endless forming web 31, and part of the endless top web 41 intersects with the drying system, so that the carbon nanotube wet film can be transferred from the endless forming web 31 to the drying system 60 through the endless top web 41.

[0104] In the embodiment of the present invention, the endless top web 41 moves in the opposite direction to the endless forming web 31, so that the portion where the endless top web 41 and the endless forming web intersect moves in the same direction, so as to facilitate the transfer of the carbon nanotube wet film from the endless forming web 31 to the endless top web 41. For example, the endless forming web 31 moves in a clockwise direction, and the endless top web 41 moves in a counterclockwise direction.

[0105] In some embodiments, Figure 2 As shown, the vacuum forming system 30 further includes: a first blowing device 34 and a vibration device 33. Multiple sets of forming vacuum pumping components 32, vibration devices 33, and first blowing devices 34 are sequentially arranged on the side of the endless forming net 31 away from the carbon nanotube wet film along the moving direction of the endless forming net 31. The endless forming net 31 is used to drive the carbon nanotube wet film to pass through the forming vacuum pumping components 32, vibration devices 33, and first blowing devices 34 in sequence. Among them, the first blowing device 34 and the vibration device 33 are arranged at positions corresponding to the top net transfer system 40, and are respectively used to blow and vibrate the carbon nanotube wet film to assist in transferring the carbon nanotube wet film to the top net transfer system 40.

[0106] Specifically, the vibration device 33 and the first blowing device 34 in the vacuum forming system 30 are arranged at positions corresponding to the endless top net 41, and the top net vacuuming component 42 in the top net transfer system 40 is arranged at a position corresponding to the endless forming net 31, and at least one group of top net vacuuming components 42 corresponds to the position of the vibration device 33 and / or the first blowing device 34, so that the carbon nanotube wet film can be transferred to the endless top net 41 under the action of vibration, blowing and suction.

[0107] When the carbon nanotube wet film on the endless forming net 31 moves through the vibration device 33 and the first blowing device 34 in sequence, the carbon nanotube wet film gradually separates from the endless forming net 31 under the vibration of the vibration device 33 and the blowing of the first blowing device 34; at the same time, the carbon nanotube wet film is adsorbed and transferred to the endless top net 41 under the suction action of the top net vacuum assembly 42.

[0108] Preferably, there is at least one group of vibration devices 33 and at least two groups of first blowing devices 34. The carbon nanotube wet film is continuously blown by two groups of first blowing devices 34 to improve the auxiliary transfer effect. The spacing between the two groups of first blowing devices 34 is set to 8-12 cm; if the spacing is too large, the carbon nanotube wet film cannot be continuously blown, resulting in reduced transfer effect; and because the first blowing devices 34 need to occupy a certain space, the minimum spacing between them is 8 cm.

[0109] In some embodiments, the top mesh transfer system 40 includes at least two groups of top mesh vacuuming components 42, namely a first top mesh vacuuming component and a second top mesh vacuuming component. The first top mesh vacuuming component is arranged at a position corresponding to the vibration device 33 and / or the first blowing device 34, and is used to adsorb the carbon nanotube wet film to the endless top mesh 41; the second top mesh vacuuming component is arranged downstream of the first top mesh vacuuming component. After the carbon nanotube wet film is transferred to the endless top mesh 41, the second top mesh vacuuming component is used to further dehydrate the carbon nanotube wet film to improve the dehydration effect.

[0110] In some embodiments, Figure 2 As shown, the continuous production system further includes a wet pressing roller 50, which is disposed between the vacuum forming system 30 and the top web transfer system 40 and is used to roll the carbon nanotube wet film to accelerate the dehydration of the carbon nanotube wet film.

[0111] Specifically, a pair of wet pressing rollers 50 are respectively arranged on the side of the endless forming web 31 and the endless top web 41 away from the carbon nanotube wet film, so that the endless forming web 31 and the endless top web 41 can move through the roller gap of the wet pressing rollers 50, thereby rolling the carbon nanotube wet film on the endless forming web 31, accelerating the dehydration of the carbon nanotube wet film, and reducing the thickness of the carbon nanotube wet film.

[0112] In some embodiments, the roller gap of the wet pressing roller 50 is 50-90% of the thickness of the carbon nanotube wet film, which can effectively roll and dehydrate the carbon nanotube wet film and reduce the wear of the carbon nanotube wet film caused by rolling, thereby preventing the carbon nanotube film from being too thin.

[0113] like Figure 2 As shown, a portion of the multiple forming vacuum assemblies 32 is located at a position corresponding to the flow box 22, and another portion is arranged downstream of the wet pressing roller 50 and at a position corresponding to the endless top net 41, so that the carbon nanotube slurry is vacuum filtered and formed by a portion of the forming vacuum assemblies 32, and then passes through the wet pressing roller 50 and another portion of the forming vacuum assemblies 32 in sequence for further dehydration.

[0114] In some embodiments, Figure 2 As shown, the drying system 60 includes: an endless drying net 61, multiple sets of drying vacuum components 62, and multiple drying devices 63. The endless drying net 61 can move cyclically, and the multiple sets of drying vacuum components 62 and the multiple drying devices 63 are arranged in sequence along the moving direction of the endless drying net 61; the endless drying net 61 is used to carry the carbon nanotube wet film and drive the carbon nanotube wet film to pass through the multiple sets of drying vacuum components 62 and the multiple drying devices 63 in sequence, so that the carbon nanotube wet film is dried to form a carbon nanotube film.

[0115] At least a portion of the plurality of drying vacuum assemblies 62 is disposed at a position corresponding to the top web transfer system 40, and is used to absorb and move the carbon nanotube wet film to the endless drying web 61. The drying device is used to dry the carbon nanotube wet film to obtain the carbon nanotube film 1.

[0116] Specifically, the endless drying net 61 is supported and driven to move by a plurality of transmission rollers, for example, Figure 2 As shown, a plurality of transmission rollers support the endless drying net 61 and drive it to move in a circular motion. Part of the endless top net 41 intersects with one side of the endless forming net 31, and part of the endless drying net 61 intersects, so that the carbon nanotube wet film can be transferred from the endless forming net 31 to the endless drying net 61 through the endless top net 41.

[0117] In the embodiment of the present invention, the endless drying net 61 moves in the opposite direction to the endless top net 41 and in the same direction as the endless forming net 31, so that the portion where the endless top net 41 and the endless drying net 61 intersect moves in the same direction, thereby facilitating the transfer of the carbon nanotube wet film from the endless top net 41 to the endless drying net 61. For example, the endless drying net 61 moves in a clockwise direction, and the endless top net 41 moves in a counterclockwise direction.

[0118] In some embodiments, Figure 2 As shown, the top net transfer system 40 also includes a second blowing device 43. Multiple groups of top net vacuuming components 42 and second blowing devices 43 are sequentially arranged on the side of the endless top net 41 away from the carbon nanotube wet film along the moving direction of the endless top net 41, and the endless top net 41 is used to drive the carbon nanotube wet film to pass through the top net vacuuming components 42 and the second blowing device 43 in sequence. The second blowing device 43 is arranged downstream of the multiple groups of top net vacuuming components 42 and at a position corresponding to the drying system 60, and the second blowing device 43 is used to blow air on the carbon nanotube wet film to assist in transferring the carbon nanotube wet film to the drying system 60 for drying.

[0119] Specifically, the second blowing device 43 in the top net transfer system 40 is arranged at a position corresponding to the endless drying net 61, and the drying vacuum assembly 62 in the drying system 60 is arranged at a position corresponding to the endless top net 41, so that the carbon nanotube wet film can be transferred from the endless top net 41 to the endless drying net 61 under the action of blowing and suction. Preferably, the second blowing device 43 is at least two groups.

[0120] When the carbon nanotube wet film on the endless top net 41 moves to the junction of the endless top net 41 and the endless drying net 61, the carbon nanotube wet film is gradually separated from the endless top net 41 and adsorbed to the endless drying net 61 under the suction action of the drying vacuum assembly 62 and the auxiliary blowing action of the second blowing device 43 in the top net transfer system 40, thereby realizing the transfer of the carbon nanotube wet film.

[0121] In addition, in some embodiments, the drying system 60 includes at least two groups of drying vacuum components 62, namely a first drying vacuum component and a second drying vacuum component. The first drying vacuum component is arranged at a position corresponding to the second blowing device 43, and is used to adsorb and move the carbon nanotube wet film to the endless drying net 61; the second drying vacuum component is arranged downstream of the first drying vacuum component, and is used to further dehydrate the carbon nanotube wet film.

[0122] like Figure 2 As shown, a plurality of drying devices 63 are arranged in sequence along the moving direction of the endless drying net 61, and are used to dry the carbon nanotube wet film. Preferably, the drying device 63 is a drying cylinder, for example, a Yankee drying cylinder. The embodiment of the present invention uses a drying cylinder as the drying device 63, and dries the carbon nanotube wet film by steam heating, thereby reducing production costs.

[0123] In some embodiments, there are at least two drying devices 63, and the multiple drying devices 63 are respectively arranged on both sides of the endless drying net 61, wherein at least one drying device 63 is located on the inner side of the endless drying net 61, and is used to perform preliminary drying of the carbon nanotube wet film; at least one drying device 63 is located on the outer side of the endless drying net 61, so that it can be in direct contact with the carbon nanotube wet film, thereby improving the drying effect of the carbon nanotube wet film.

[0124] Preferably, the drying device 63 is cylindrical, and the endless drying net 61 moves around part of the outer surface of the drying device 63, so that the carbon nanotube wet film moves through at least half of the outer surface of the drying device 63, thereby improving the drying effect of the carbon nanotube wet film.

[0125] In some embodiments, the drying system 60 further includes a dry pressing roller 64, a pair of dry pressing rollers 64 are respectively arranged on both sides of the endless drying net 61, and are located between the plurality of drying devices 63, for rolling the carbon nanotube film to reduce the thickness of the carbon nanotube film. The carbon nanotube wet film passes through the drying device 63, the dry pressing roller 64, and another part of the drying device 63 in sequence to be dried and reduce the thickness to obtain the carbon nanotube film 1, and the carbon nanotube film 1 is rolled up by the winding device 70.

[0126] In some embodiments, the roller gap of the dry pressing roller 64 is 50-90% of the thickness of the carbon nanotube wet film. The thickness of the carbon nanotube film can be controlled by controlling the roller gap.

[0127] In some embodiments, the endless forming net 31, the endless top net 41, and the endless drying net 61 can be one of a copper net, a stainless steel net, and a single-layer / multi-layer polyester net. The materials of the endless forming net 31, the endless top net 41, and the endless drying net 61 can be the same or different.

[0128] In some embodiments, the endless forming net 31, the endless top net 41, and the endless drying net 61 may be 30-400 meshes; preferably, the endless forming net 31 is 200-400 meshes, the endless top net 41 is 100-250 meshes, and the endless drying net 61 is 30-150 meshes. The mesh number of the net will affect the deposition rate and dehydration speed of the carbon nanotube slurry. If the mesh number is too small, some carbon nanotube slurry will leak out, and if the mesh number is too large, dehydration will be difficult.

[0129] The continuous production system of the present invention adopts a forming net, a top net and a drying net to carry and process carbon nanotube films of different dryness, thereby increasing the life of each net and reducing the production cost.

[0130] The carbon nanotube film and the continuous preparation method and continuous production system of the present invention are further described below through specific examples.

[0131] Example 1

[0132] The continuous preparation method of the carbon nanotube film of this embodiment includes:

[0133] S1, preparing carbon nanotube slurry:

[0134] In terms of mass percentage, in addition to solvent water, the carbon nanotube slurry includes: 50% carbon nanotubes, 20% dispersant, 12% resin, 12% flocculant, and 6% defoamer. Among them, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 7-15nm and a length of 30-50μm; the dispersant is sodium dodecyl sulfate; the resin uses an aqueous polyurethane emulsion with a resin content of 50%, and the amount of the emulsion added is twice that of the flocculant; the flocculant is potassium aluminum sulfate dodecahydrate; the defoamer is an organic silicon defoamer. The concentration of carbon nanotubes in the slurry is 0.4%.

[0135] The carbon nanotubes and the dispersant are mixed in water, ground and dispersed, and then a defoamer is added to obtain a carbon nanotube dispersion. A waterborne polyurethane emulsion is added to the carbon nanotube dispersion and mixed and stirred, and then a flocculant is added and mixed and stirred to obtain a carbon nanotube slurry.

[0136] S2, preparing the carbon nanotube slurry into a carbon nanotube wet film:

[0137] The carbon nanotube slurry is spread on the endless forming net through the slurry spreading system, and the carbon nanotube slurry is vacuum filtered through the 8-group forming vacuum pumping assembly to form a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping assembly is -0.04MPa.

[0138] The carbon nanotube wet film was pressed by a wet press roll, and the roll gap between the wet press rolls was 2 mm.

[0139] S3, transfer of carbon nanotube wet film:

[0140] When the endless forming net drives the carbon nanotube wet film to move to the position where it intersects with the endless top net, the carbon nanotube wet film is sucked, blown and vibrated by the first top net vacuuming component, the vibration device, and the two sets of first blowing devices to transfer the carbon nanotube film to the endless top net. Among them, the vacuum degree of the first top net vacuuming component is -0.8MPa; the blowing pressures of the two sets of first blowing devices are 0.1MPa and 0.08MPa respectively; and the vibration pressure of the vibration device is 0.2MPa.

[0141] After the carbon nanotube film is transferred to the endless top net, the second top net vacuum pumping component is used to continue to remove moisture from the film, and the vacuum degree of the second top net vacuum pumping component is -0.4 MPa.

[0142] When the endless top net drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net, the carbon nanotube wet film is sucked by the first drying vacuum pumping component, and the second blowing device blows air to transfer the carbon nanotube wet film to the endless drying net. The vacuum degree of the first drying vacuum pumping component is -0.8MPa; the pressure of the second blowing device is 0.3MPa.

[0143] After the carbon nanotube film is transferred to the endless drying net, moisture is further removed from the film through the second drying vacuum pumping component, and the vacuum degree of the second drying vacuum pumping component is -0.4 MPa.

[0144] S4, drying the carbon nanotube wet film:

[0145] The carbon nanotube wet film is initially dried by the first drying device at a drying temperature of 100°C; the carbon nanotube wet film is rolled by a dry pressing roller with a roller spacing of 0.15mm; the carbon nanotube wet film is dried by the second drying device at a drying temperature of 120°C; the obtained carbon nanotube film is rolled up.

[0146] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web was controlled to be 3 m / min, the speed of the endless top web was controlled to be 3 m / min, and the speed of the endless drying web was controlled to be 3.1 m / min.

[0147] The carbon nanotube film prepared according to the above steps is as follows Figure 4 As shown, its thickness is 180μm and its surface density is 50g / m 2 , the square resistance is 1.5Ω / sq.

[0148] Example 2

[0149] The continuous preparation method of the carbon nanotube film of this embodiment includes:

[0150] S1, preparing carbon nanotube slurry:

[0151] In terms of mass percentage, in addition to the solvent water, the carbon nanotube slurry includes: 40% carbon nanotubes, 17% dispersant, 20% resin, 20% flocculant, and 3% defoamer. Among them, the carbon nanotubes are the same as those in Example 1, the dispersant is sodium dodecyl sulfate; the resin is a water-based acrylic emulsion with a resin content of 50%, and the addition amount is the same as the mass of the carbon nanotubes; the flocculant is ferrous sulfate; and the defoamer is an organosilicon defoamer. The concentration of the carbon nanotubes in the slurry is 0.1%.

[0152] The carbon nanotubes and the dispersant are mixed in water, ground and dispersed, and then a defoamer is added to obtain a carbon nanotube dispersion. A waterborne polyurethane emulsion is added to the carbon nanotube dispersion and mixed and stirred, and then a flocculant is added and mixed and stirred to obtain a carbon nanotube slurry.

[0153] S2, preparing the carbon nanotube slurry into a carbon nanotube wet film:

[0154] The carbon nanotube slurry is spread on the endless forming net through the slurry spreading system, and the carbon nanotube slurry is vacuum filtered through the 8-group forming vacuum pumping assembly to form a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping assembly is -0.08MPa.

[0155] The carbon nanotube wet film was pressed by a wet press roll, and the roll gap between the wet press rolls was 3.2 mm.

[0156] S3, transfer of carbon nanotube wet film:

[0157] When the endless forming net drives the carbon nanotube wet film to move to the position where it intersects with the endless top net, the carbon nanotube wet film is sucked, blown and vibrated by the first top net vacuuming component, the vibration device, and the two sets of first blowing devices to transfer the carbon nanotube film to the endless top net. Among them, the vacuum degree of the first top net vacuuming component is -0.8MPa; the blowing pressures of the two sets of first blowing devices are 0.2MPa and 0.16MPa respectively; and the vibration pressure of the vibration device is 0.4MPa.

[0158] After the carbon nanotube film is transferred to the endless top net, the second top net vacuum pumping assembly is used to continue to remove moisture from the film, and the vacuum degree of the second top net vacuum pumping assembly is -0.3 MPa.

[0159] When the endless top net drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net, the carbon nanotube wet film is sucked by the first drying vacuum pumping component, and the second blowing device blows air to transfer the carbon nanotube wet film to the endless drying net. The vacuum degree of the first drying vacuum pumping component is -1MPa; the pressure of the second blowing device is 0.4MPa.

[0160] After the carbon nanotube film is transferred to the endless drying net, moisture is further removed from the film through the second drying vacuum pumping component, and the vacuum degree of the second drying vacuum pumping component is -0.8 MPa.

[0161] S4, drying the carbon nanotube wet film:

[0162] The carbon nanotube wet film is initially dried by the first drying device at a drying temperature of 100°C; the carbon nanotube wet film is rolled by a dry pressing roller with a roller spacing of 2.8mm; the carbon nanotube wet film is dried by the second drying device at a drying temperature of 150°C; the obtained carbon nanotube film is rolled up.

[0163] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web was controlled to be 0.5 m / min, the speed of the endless top web was controlled to be 0.6 m / min, and the speed of the endless drying web was controlled to be 0.7 m / min.

[0164] The carbon nanotube film prepared according to the above steps has a thickness of 230 μm and a surface density of 64 g / m 2 , the square resistance is 0.9Ω / sq.

[0165] Example 3

[0166] The continuous preparation method of the carbon nanotube film of this embodiment includes:

[0167] S1, preparing carbon nanotube slurry:

[0168] In terms of mass percentage, in addition to the solvent water, the carbon nanotube slurry includes: 60% carbon nanotubes, 15% dispersant, 10% resin, 10% flocculant, and 5% defoamer. The carbon nanotubes are the same as those in Example 1, the dispersant is sodium dodecyl sulfate; the resin is an aqueous styrene butadiene emulsion with a resin content of 50%; the flocculant is polyaluminum chloride dodecahydrate; and the defoamer is an organosilicon defoamer. The concentration of the carbon nanotubes in the slurry is 10%.

[0169] The carbon nanotubes and the dispersant are mixed in water, ground and dispersed, and then a defoamer is added to obtain a carbon nanotube dispersion. A waterborne polyurethane emulsion is added to the carbon nanotube dispersion and mixed and stirred, and then a flocculant is added and mixed and stirred to obtain a carbon nanotube slurry.

[0170] S2, preparing the carbon nanotube slurry into a carbon nanotube wet film:

[0171] The carbon nanotube slurry is spread on the endless forming net through the slurry spreading system, and the carbon nanotube slurry is vacuum filtered through the 8-group forming vacuum pumping assembly to form a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping assembly is -0.04MPa.

[0172] The carbon nanotube wet film was pressed by a wet press roll, and the roll gap between the wet press rolls was 0.8 mm.

[0173] S3, transfer of carbon nanotube wet film:

[0174] When the endless forming net drives the carbon nanotube wet film to move to the position where it intersects with the endless top net, the carbon nanotube wet film is sucked, blown and vibrated by the first top net vacuuming component, the vibration device, and the two sets of first blowing devices to transfer the carbon nanotube film to the endless top net. Among them, the vacuum degree of the first top net vacuuming component is -0.2MPa; the blowing pressures of the two sets of first blowing devices are 0.1MPa and 0.09MPa respectively; and the vibration pressure of the vibration device is 0.2MPa.

[0175] After the carbon nanotube film is transferred to the endless top net, the second top net vacuum pumping component is used to continue to remove moisture from it, and the vacuum degree of the second top net vacuum pumping component is -0.1 MPa.

[0176] When the endless top net drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net, the carbon nanotube wet film is sucked by the first drying vacuum pumping component, and the second blowing device blows air to transfer the carbon nanotube wet film to the endless drying net. The vacuum degree of the first drying vacuum pumping component is -0.4MPa; the pressure of the second blowing device is 0.2MPa.

[0177] After the carbon nanotube film is transferred to the endless drying net, moisture is further removed from the film through the second drying vacuum pumping component, and the vacuum degree of the second drying vacuum pumping component is -0.2 MPa.

[0178] S4, drying the carbon nanotube wet film:

[0179] The carbon nanotube wet film is initially dried by the first drying device at a drying temperature of 80°C; the carbon nanotube wet film is rolled by a dry pressing roller with a roller spacing of 0.5mm; the carbon nanotube wet film is dried by the second drying device at a drying temperature of 90°C; the obtained carbon nanotube film is rolled up.

[0180] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web is controlled to be 10 m / min, the speed of the endless top web is controlled to be 11 m / min, and the speed of the endless drying web is controlled to be 12 m / min.

[0181] The carbon nanotube film prepared according to the above steps has a thickness of 50 μm and a surface density of 20 g / m 2 , the square resistance is 6.5Ω / sq.

[0182] Example 4

[0183] The difference between this embodiment and embodiment 1 is that, except for the solvent, the mass percentages of the components in the carbon nanotube slurry are:

[0184] Carbon nanotubes 45%, dispersant 20%, resin 15%, flocculant 15%, defoaming agent 5%.

[0185] Example 5

[0186] The difference between this example and Example 1 is that the mass percentage of the resin and the flocculant in the carbon nanotube slurry of this comparative example is 21% each, and the mass percentage of the carbon nanotubes is 32%.

[0187] Example 6

[0188] The difference between this example and Example 1 is that the mass percentage of the resin and the flocculant in the carbon nanotube slurry of this comparative example is 6%, and the mass percentage of the carbon nanotubes is 62%.

[0189] Comparative Example 1

[0190] The difference between this comparative example and Example 1 is that no resin is added to the carbon nanotube slurry of this comparative example. The mass percentage of each component in the carbon nanotube slurry is:

[0191] Carbon nanotubes 60%, dispersant 20%, flocculant 14%, defoamer 6%.

[0192] In this comparative example, since no resin was added, the retention rate of the carbon nanotube slurry on the forming net was reduced, and a small amount of the slurry passed through the forming net during filtration due to the small particle size.

[0193] Comparative Example 2

[0194] The difference between this comparative example and Example 1 is that no flocculant is added to the carbon nanotube slurry of this comparative example. The mass percentage of each component in the carbon nanotube slurry is:

[0195] Carbon nanotubes 60%, dispersant 20%, resin 14%, defoamer 6%.

[0196] In this comparative example, since no flocculant was added, the resin was not demulsified, the resin and the carbon nanotubes did not form a broom shape, the retention rate of the slurry on the forming net was reduced, and a small amount of slurry passed through the forming net during filtration.

[0197] Comparative Example 3

[0198] The difference between this comparative example and Example 1 is that the vacuum degree of the first top net vacuum pumping assembly is -0.1 MPa. In this comparative example, the vacuum degree of the first top net vacuum pumping assembly is too low when transferring the carbon nanotube wet film, and the carbon nanotube wet film is not successfully transferred to the endless top net.

[0199] Comparative Example 4

[0200] The difference between this comparative example and Example 1 is that the blowing pressure of the first blowing device is 0.3 MPa, and the pressure of the vibration device is 0.5 MPa. The blowing pressure and the pressure of the vibration device are too large, resulting in partial damage to the carbon nanotube wet film.

[0201] The specific ingredients of the carbon nanotube slurry of each embodiment and comparative example are shown in Table 1.

[0202] Table 1 Content of each component in carbon nanotube slurry except solvent (mass percentage %)

[0203]

[0204] The thickness, surface density, square resistance and other properties of the carbon nanotube film of each embodiment are shown in Table 2.

[0205] Table 2 Thickness, surface density and sheet resistance of carbon nanotube films

[0206]

[0207] According to Examples 1, 5 and 6, as the carbon nanotube content in the carbon nanotube slurry increases and the resin and flocculant content decreases, the thickness and surface density of the prepared carbon nanotube film increase, and the square resistance decreases, that is, the conductivity increases.

[0208] According to Example 1 and Comparative Examples 1-2, since no resin or flocculant was added in Comparative Examples 1 and 2, a small amount of slurry passed through the forming net during filtration, resulting in reduced thickness and surface density of the carbon nanotube film finally obtained, resulting in waste of carbon nanotube slurry and increased square resistance.

[0209] Example 7

[0210] This embodiment provides a carbon nanotube film continuous production system, and its structural schematic diagram is as follows: Figure 1 As shown; the carbon nanotube continuous production system provided by the present invention comprises a grinding and pulping system 10, a pulping system, a vacuum forming system 30, a top net transfer system 40, a drying system 60 and a winding device 70 in sequence.

[0211] The grinding pulping system 10 is connected to the pulping system, which is composed of a high-level box 21 and an open headbox 22. The entrance of the high-level box 21 is connected to the grinding pulping system 10 and is located above the entire production system, and the outlet is connected to the headbox 22. The headbox 22 is provided with a first water baffle 223 and a second water baffle 224, the distance between the first water baffle 223 and the bottom is 4 cm, and the distance between the second water baffle 224 and the bottom is 3 mm.

[0212] The vacuum forming system 30 is connected to the headbox 22, and includes an endless forming net 31, 8 forming vacuum assemblies 32, 2 first blowing devices 34 and 1 vibration device 33. The distance between the 2 first blowing devices is 10 cm.

[0213] The top net transfer system 40 includes an endless top net 41 , two groups of top net vacuuming components 42 , and a second blowing device 43 .

[0214] A set of wet pressing rollers 50 is installed between the vacuum forming system 30 and the top wire transfer system 40, and the roller spacing of the wet pressing rollers 50 is 2 mm.

[0215] The drying system 60 includes an endless drying net 61, two sets of drying vacuum components 62, two drying devices 63 and a set of dry pressing rollers 64. The drying device 63 is a Yankee dryer, and the roller spacing of the dry pressing rollers 64 is 0.15 mm.

[0216] The endless forming net 31 is a 300-mesh stainless steel net, the endless top net 41 is a 100-mesh polyester net, and the endless drying net 61 is a 50-mesh polyester net.

[0217] 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 continuously preparing a carbon nanotube film, characterized in that: include: Step S1, preparing carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, dispersant, resin, flocculant, defoamer and water; in terms of mass percentage, excluding the solvent, the carbon nanotube slurry comprises: 40% to 60% carbon nanotubes, 10% to 20% dispersant, 10% to 20% resin, 10% to 20% flocculant, and 3% to 6% defoamer; Step S2, continuously spreading the carbon nanotube slurry on a circulating endless forming net, and vacuum filtering the carbon nanotube slurry to continuously form a carbon nanotube wet film; Step S3, transferring the carbon nanotube wet film to a circulating endless drying net; Step S4, drying the carbon nanotube wet film, and rolling up the dried carbon nanotube film to obtain a continuously rolled carbon nanotube flexible film; In step S3, the carbon nanotube wet film is transferred to the circulated endless drying net by a top net transfer system; the top net transfer system is arranged between the endless forming net and the endless drying net, and the top net transfer system transfers the carbon nanotube wet film from the endless forming net to the endless drying net by suction; The top net transfer system includes a cyclically movable endless top net and a first top net vacuuming component; in step S3, when the endless forming net drives the carbon nanotube wet film to move to a position intersecting with the endless top net, the carbon nanotube wet film is sucked by the first top net vacuuming component to transfer the carbon nanotube wet film from the endless forming net to the endless top net; A vibration device and two groups of first blowing devices are sequentially arranged along the moving direction of the endless forming net; in step S3, when the first top net vacuum pumping assembly sucks the carbon nanotube wet film, the carbon nanotube wet film is vibrated and blown by the vibration device and the first blowing device respectively, and the carbon nanotube wet film is assisted to be transferred to the endless top net under the action of vibration and blowing; When the vibration device and the first blowing device are used to assist in transferring the carbon nanotube wet film, the vibration pressure of the vibration device is controlled to be 0.1~0.4MPa, and the blowing pressures of the two groups of the first blowing devices arranged sequentially along the moving direction of the endless forming network are controlled to be 0.1~0.2Mpa and 0.08~0.16Mpa respectively.

2. The method according to claim 1, characterized in that The resin adopts a water-soluble resin emulsion, and the resin emulsion includes at least one of a water-soluble polyurethane emulsion, an acrylic emulsion, and a styrene-butadiene emulsion; And / or, the flocculant includes at least one of ferrous sulfate, magnesium sulfate, potassium aluminum sulfate dodecahydrate, polyaluminium chloride and ferric chloride.

3. The method according to claim 1, characterized in that A first drying vacuum assembly is disposed on a side of the endless drying net away from the carbon nanotube wet film; In step S3, when the endless top net drives the carbon nanotube wet film to move to the position where it intersects with the endless drying net, the carbon nanotube wet film is sucked by the first drying vacuum assembly to transfer the carbon nanotube wet film from the endless top net to the endless drying net.

4. The method according to any one of claims 1 to 3, characterized in that: A pulp distribution system is arranged above the endless forming net, and an outlet of the pulp distribution system is overlapped on the endless forming net; In step S2, the carbon nanotube slurry is continuously spread on the endless forming net that is circulated by a slurry spreading system.

5. A carbon nanotube film, characterized in that: The carbon nanotube film is prepared by the continuous preparation method according to any one of claims 1 to 4, wherein the thickness of the carbon nanotube film is 30 to 500 μm, and the surface density of the carbon nanotube film is 20 to 200 g / m 2 .

6. A continuous production system for carbon nanotube films, characterized in that: Used to implement the continuous preparation method according to any one of claims 1 to 4, comprising: a grinding pulping system, a pulp spreading system, a vacuum forming system, a top net transfer system, a drying system and a winding device; The grinding and slurrying system is used to prepare carbon nanotube slurry; The slurry spreading system is connected to the grinding and slurry making system. The slurry spreading system is located above the vacuum forming system and connected to the vacuum forming system, and is used to spread the carbon nanotube slurry on the vacuum forming system. The vacuum forming system is used to filter the water in the carbon nanotube slurry to obtain a carbon nanotube wet film; The top web transfer system is disposed between the vacuum forming system and the drying system, and is configured to transfer the carbon nanotube wet film from the vacuum forming system to the drying system by suction; The drying system is used to dry the carbon nanotube wet film to obtain a carbon nanotube film; The winding device is connected to the drying system and is used for winding the dried carbon nanotube film.

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