Continuous production system and continuous preparation method of carbon nanotube film

Abstract

The embodiment of the invention relates to a continuous production system and a continuous preparation method of a carbon nanotube film, and belongs to the technical field of carbon nanotube film preparation. The continuous production system comprises a grinding and pulping system, a pulp distribution system, a vacuum forming system, a top net transfer system, a drying system and a winding device. The grinding and pulping system is used for preparing carbon nanotube slurry; the pulp distribution system is connected with the grinding and pulping system, is positioned above the vacuum forming system, is connected with the vacuum forming system, and is used for spreading the carbon nanotube pulp on the vacuum forming system; the vacuum forming system is used for filtering moisture in the carbon nanotube slurry to obtain a carbon nanotube wet film; the top net transfer system is arranged between the vacuum forming system and the drying system and is used for transferring the carbon nanotube wet film from the vacuum forming system to the drying system through a suction effect; the drying system is used for drying the carbon nanotube wet film to obtain a carbon nanotube film; and the winding device is connected with the drying system and is used for winding the dried carbon nanotube film.

Description

Technical Field

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

[0004] However, when the carbon nanotube film is prepared by vacuum filtration, it is not easy for the carbon nanotube film to separate from the filter membrane or filter screen, which makes it difficult to obtain a continuous roll of carbon nanotube film. The existing continuous production equipment uses a pressing roller to separate the carbon nanotube film from the filter screen, and transfers the carbon nanotube film from the porous filter screen to the bonding substrate through the pressing roller, and then dries the carbon nanotube film. However, the use of a pressing roller to transfer the carbon nanotube film may also result in a failure in the transfer of the carbon nanotube film, or it is necessary to coat the target substrate with an adhesive to improve the bonding strength between the carbon nanotube film and the target substrate to prevent the carbon nanotube film from falling off, but the adhesive may cause contamination of the carbon nanotube film. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a continuous production system and continuous preparation method of carbon nanotube film, so as to solve the problem that the carbon nanotube film is difficult to separate from the filter screen in the prior art carbon nanotube film preparation method, resulting in difficulty in continuous preparation.

[0006] On the one hand, an embodiment of the present invention provides a continuous production system for carbon nanotube films, which includes: a grinding and pulping system, a slurry spreading system, a vacuum forming system, a top-net 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-net transfer system is arranged between the vacuum forming system and the drying system, and the top-net transfer system is arranged 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 to wind up the dried carbon nanotube film.

[0007] Furthermore, the vacuum forming system includes: an endless forming net and multiple forming vacuum components; the endless forming net can move in a circular motion, and the slurry spreading system is used to spread the carbon nanotube slurry on the endless forming net; the multiple forming vacuum components are arranged in sequence on the side of the endless forming net away from the carbon nanotube wet film along the moving direction of the endless forming net, and the endless forming net is used to drive the carbon nanotube slurry to pass through the multiple forming vacuum components in sequence; the forming vacuum component is used to vacuum filter the carbon nanotube slurry to form a carbon nanotube wet film.

[0008] Furthermore, the top mesh transfer system includes an endless top mesh and multiple groups of top mesh vacuum assemblies; the endless top mesh can move cyclically, and the multiple groups of top mesh vacuum assemblies are arranged in sequence on the side of the endless top mesh away from the carbon nanotube wet film along the moving direction of the endless top mesh; the endless top mesh 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 in sequence; a part of the endless top mesh intersects with the endless forming mesh, and at least a part of the multiple groups of top mesh vacuum assemblies are arranged at a position corresponding to the vacuum forming system, and corresponding to the downstream position of the multiple groups of forming vacuum assemblies, for sucking and transferring the formed carbon nanotube wet film to the endless top mesh.

[0009] Furthermore, the vacuum forming system also includes: a vibration device, a first blowing device; multiple sets of forming vacuum pumping components, a vibration device, and a first blowing device are arranged in sequence along the moving direction of the endless forming network on the side of the endless forming network away from the carbon nanotube wet film, and the endless forming network is used to drive the carbon nanotube wet film to pass through the vibration device and the first blowing device in sequence; the first blowing device and the vibration device are set at positions corresponding to the top network transfer system, 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 network transfer system.

[0010] Furthermore, the drying system includes: an endless drying net, multiple groups of drying vacuum components, and multiple drying devices; the endless drying net can move in a circular motion, and the multiple groups of drying vacuum components and the multiple drying devices are arranged in sequence along the moving direction of the endless drying net; the endless drying net is used to carry the carbon nanotube wet film and drive the carbon nanotube wet film to pass through the multiple groups of vacuum components and the multiple drying devices in sequence; a part of the endless drying net intersects with the endless top net of the top net transfer system, and the multiple groups of drying vacuum components are arranged at a position corresponding to the top net transfer system, and are used to suck and transfer the carbon nanotube wet film to the endless drying net; the multiple drying devices are arranged in sequence along the moving direction of the endless drying net, and are used to dry the carbon nanotube wet film.

[0011] Furthermore, the top net transfer system also includes a second blowing device; the second blowing device is arranged downstream of the multiple groups of top net vacuuming components and at a position corresponding to the drying system, and is used to blow air to the carbon nanotube wet film to assist in transferring the carbon nanotube wet film to the drying system.

[0012] Furthermore, the pulp distribution system includes: a headbox, which is arranged above the endless forming wire, and an outlet of the headbox is overlapped on the endless forming wire.

[0013] Furthermore, the continuous production system also includes: a wet pressing roller, which is arranged between the vacuum forming system and the top web transfer system and is used to roll the carbon nanotube wet film to accelerate the dehydration of the carbon nanotube wet film.

[0014] Furthermore, the drying system also includes: dry pressing rollers, which are arranged on both sides of the endless drying net and located between the multiple drying devices, and are used to roll the carbon nanotube film to reduce the thickness of the carbon nanotube film.

[0015] On the other hand, an embodiment of the present invention further provides a method for continuously preparing a carbon nanotube film, which can be implemented by using the continuous production system in the above embodiment, and the method comprises:

[0016] Prepare carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, dispersant, resin emulsion, flocculant, defoamer and water;

[0017] The carbon nanotube slurry is spread on a vacuum forming system and formed by vacuum filtration to obtain a carbon nanotube wet film;

[0018] The carbon nanotube wet film is transferred to the drying system using a top-net transfer system;

[0019] The carbon nanotube wet film is dried and rolled up to obtain a carbon nanotube film.

[0020] The continuous production system and continuous preparation method of the carbon nanotube film according to the embodiment of the present invention can achieve at least one of the following beneficial effects:

[0021] 1. The continuous production system provided by the present invention adopts a vacuum filtration method to shape the carbon nanotube slurry through a grinding pulping system, a pulping system, and a vacuum forming system 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 the drying net through suction, so that the carbon nanotube wet film can be separated from the forming net and transferred to the drying net for drying, which is beneficial to the continuous preparation of the carbon nanotube film; and, compared with the existing method of transferring the carbon nanotube wet film by a lamination roller, there is no need to apply an adhesive, thereby avoiding contamination of the carbon nanotube film.

[0022] 2. The present invention arranges a top net vacuuming component, a vibration device, and a blowing device at positions corresponding to the vacuum forming system and the top net transfer system, and realizes the separation of the carbon nanotube wet film from the forming net and the transfer from the forming net to the top net through the combined action of suction, vibration, and suction; arranges a drying vacuuming component and a blowing device at positions corresponding to the top net transfer system and the drying system, and realizes the separation of the carbon nanotube wet film from the top net and the transfer from the top net to the drying net through the combined action of suction and blowing, and the operation is simple.

[0023] 3. The continuous production system of the present invention uses 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 production costs.

[0024] 4. The continuous production system of the present invention adopts the process of overlapping the endless forming net with the headbox, so that the carbon nanotube slurry is continuously spread on the forming net, which can realize the continuous film formation of the carbon nanotube slurry and reduce the risk of discontinuous film formation of the slurry.

[0025] 5. The continuous production system of the present invention is not only suitable for the continuous production and preparation of carbon nanotube films, but can also be used for the continuous preparation of other two-dimensional nanofilms and micron-scale fiber papers, such as graphene films, carbon nanotube-nanocellulose films, carbon nanotube-graphene films, etc., thereby improving the feasibility of the industrialization of two-dimensional nanomaterials.

[0026] 6. The continuous preparation method of the present invention improves the formula of the carbon nanotube slurry and forms a combined structure of "carbon nanotube particles-flocculated emulsion" through the interaction of the resin emulsion and the flocculant, which is beneficial to the formation and retention of the carbon nanotube slurry on the forming net, improves the strength of the carbon nanotube film and the self-supporting property during the preparation process, and does not require the consumption of supporting substrates to assist in production, thereby realizing large-scale industrial production of carbon nanotube flexible films in large quantities, continuously, at low cost and with high efficiency.

[0027] 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

[0028] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 It is a schematic structural diagram of a continuous production system according to an embodiment of the present invention.

[0030] Figure 2 It is a schematic structural diagram of a headbox in a continuous production system according to an embodiment of the present invention.

[0031] Figure 3 This is a physical picture of the carbon nanotube film prepared in Example 2 of the present invention.

[0032] Description of reference numerals:

[0033] 10-grinding pulping system;

[0034] 21-high-level box; 22-heading box; 221-inlet; 222-outlet; 223-first water baffle; 224-second water baffle; 225-regulating valve;

[0035] 30-vacuum forming system; 31-endless forming net; 311-transmission roller; 32-forming vacuum pumping assembly; 33-vibration device; 34-first blowing device;

[0036] 40-top net transfer system; 41-endless top net; 42-top net vacuum assembly; 43-second blowing device;

[0037] 50 - wet press roll;

[0038] 60-drying system; 61-endless drying net; 62-drying vacuum assembly; 63-drying device; 64-dry pressing roller;

[0039] 70-reeling device;

[0040] 1-Carbon nanotube film. DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] The embodiment of the present invention provides a continuous production system of carbon nanotube film, such as Figure 1 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.

[0044] 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 uses a top net transfer system 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 separated from the forming net and transferred to the drying net for drying, which is beneficial to the continuous preparation of the carbon nanotube film; and, compared with the existing carbon nanotube wet film transfer by pressing rollers, there is no need to consider whether the interface bonding strength between the carbon nanotube film and the target substrate is sufficient to transfer the carbon nanotube film to the target substrate, and there is no need to apply an adhesive, thereby avoiding contamination of the carbon nanotube film.

[0045] In some embodiments, Figure 1 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.

[0046] like Figure 1 As 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.

[0047] In some embodiments, Figure 2 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.

[0048] 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.

[0049] 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.

[0050] Some existing production equipment uses spraying to apply carbon nanotube slurry, which has the 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.

[0051] like Figure 1As 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.

[0052] Specifically, the endless forming net 31 is supported and driven to move by a plurality of transmission rollers 311, for example, Figure 1 As shown, four transmission rollers support the endless forming mesh 31 and drive it to move cyclically along a rectangular path.

[0053] 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 spread 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.

[0054] Furthermore, at least a portion of the multiple forming vacuum assemblies 32 are arranged at a position corresponding to the slurry box 22, and the forming vacuum assemblies 32 are used to vacuum filter the carbon nanotube slurry spread on the endless forming net 31, thereby filtering the moisture in the carbon nanotube slurry to form a continuous carbon nanotube wet film.

[0055] like Figure 1 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.

[0056] In some embodiments, Figure 1As 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.

[0057] Specifically, the endless top net 41 is supported and driven to move by a plurality of transmission rollers, for example, Figure 1 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.

[0058] 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.

[0059] In some embodiments, Figure 1 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.

[0060] 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.

[0061] 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 action 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 in the top net transfer system 40.

[0062] 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 to 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.

[0063] 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.

[0064] In some embodiments, Figure 1 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.

[0065] 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.

[0066] 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.

[0067] like Figure 1 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.

[0068] In some embodiments, Figure 1 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.

[0069] 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 transfer the carbon nanotube wet film to the endless drying web 61 by suction. The drying device is used to dry the carbon nanotube wet film to obtain the carbon nanotube film 1.

[0070] Specifically, the endless drying net 61 is supported and driven to move by a plurality of transmission rollers, for example, Figure 1 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.

[0071] 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.

[0072] In some embodiments, Figure 1As 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.

[0073] 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.

[0074] 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 in the drying system 60 and the blowing assistance of the second blowing device 43 in the top net transfer system 40, thereby realizing the transfer of the carbon nanotube wet film.

[0075] 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.

[0076] like Figure 1 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.

[0077] 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.

[0078] 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.

[0079] 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 can be rolled up by the winding device 70.

[0080] In some embodiments, the roller gap of the dry press 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.

[0081] 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.

[0082] The continuous production system of the present invention respectively adopts an endless forming net, an endless top net and an endless drying net to carry and process carbon nanotube films of different dryness, thereby increasing the life of each net and reducing the production cost.

[0083] 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.

[0084] 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 (i.e. connected end to end); the endless top net refers to a top net with two ends connected along the length direction; and the endless drying net refers to a drying net with two ends connected along the length direction.

[0085] The continuous production system of the present invention is not only suitable for the continuous production and preparation of carbon nanotube films, but can also be used for the continuous preparation of other two-dimensional nanofilms and micron-scale fiber papers, such as graphene films, carbon nanotube-nanocellulose films, carbon nanotube-graphene films, etc., thereby improving the feasibility of the industrialization of two-dimensional nanomaterials.

[0086] The embodiment of the present invention further provides a method for continuously preparing a carbon nanotube film, which can be implemented using the continuous production system in the above embodiment. The continuous preparation method of the embodiment of the present invention comprises the following steps:

[0087] Step S1, preparing carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, a dispersant, a resin emulsion, a flocculant and a defoaming agent;

[0088] Step S2, spreading the carbon nanotube slurry on the vacuum forming system 30, and forming it by vacuum filtration to obtain a carbon nanotube wet film;

[0089] Step S3, using the top web transfer system 40 to transfer the carbon nanotube wet film to the drying system 60;

[0090] Step S4, drying the carbon nanotube wet film and rolling it up to obtain a carbon nanotube film.

[0091] The embodiments of the present invention improve the strength of the carbon nanotube film by adding resin emulsion and flocculant to the carbon nanotube slurry, so that the carbon nanotube film has strong self-supporting properties. When the above-mentioned continuous production system is used for continuous production, the carbon nanotube slurry can be directly formed and retained on an endless forming network without consuming a supporting layer to assist production, thereby realizing continuous and large-scale production of the carbon nanotube film with simple operation, low cost and high efficiency.

[0092] In some embodiments, in addition to the solvent water, 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 the components is 100%. The concentration of carbon nanotubes in the carbon nanotube slurry is controlled at 0.1 to 10%.

[0093] 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 increase the deposition rate of the carbon nanotube slurry on the forming net and improve 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] In some embodiments, the flocculant includes at least one of ferrous sulfate, magnesium sulfate, potassium aluminum sulfate dodecahydrate, polyaluminum chloride, and ferric chloride.

[0100] 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.

[0101] 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.

[0102] In some embodiments, when vacuum filtration is performed on the carbon nanotube slurry in step S2, the vacuum degree of the multiple molding vacuum pumping components 32 in the vacuum molding system 30 is controlled to be -0.08 to -0.04 MPa to extract part of the water in the carbon nanotube slurry. The embodiment of the present invention controls the molding vacuum pumping component 32 at a suitable vacuum degree, which can slowly extract the water 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 water content and a larger thickness, which will affect 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, so that the strength of the prepared carbon nanotube film will be reduced, and on the other hand, the carbon nanotube wet film will be closely attached to the molding net, resulting in it being unable to be completely transferred to the top net.

[0103] In some embodiments, in step S3, transferring the carbon nanotube wet film to the drying system using the top web transfer system comprises:

[0104] The carbon nanotube wet film is sucked by the top net vacuum assembly 42, and the carbon nanotube wet film is blown and vibrated by the first blowing device 34 and the vibration device 33 of the vacuum forming system 30, so that the carbon nanotube wet film is transferred to the endless top net 41 under the action of suction, vibration and blowing;

[0105] The carbon nanotube wet film is sucked by the drying vacuum assembly 62 of the drying system 61, and the carbon nanotube wet film is blown by the second blowing device 43 of the top net transfer system 40. Initially, the carbon nanotube wet film is transferred to the endless drying net 61 under the action of suction and blowing.

[0106] In some embodiments, the top net transfer system 40 includes two sets of top net vacuuming components 42, the first top net vacuuming component 42 is used to absorb and move the carbon nanotube wet film from the endless forming net 31 to the endless top net 41, and the vacuum degree of the first top net vacuuming component 42 is controlled to be -0.2 to -0.8 MPa. In the embodiment of the present invention, the first top net vacuuming component 42 is controlled at a suitable vacuum degree, so that the carbon nanotube wet film can be sucked and transferred to the top net, and the vacuum is prevented from being too large, causing the wet film to cling to the top net and unable to be transferred to the drying net.

[0107] Furthermore, the second top-net vacuum pumping assembly 42 is used to continue dehydrating the carbon nanotube wet film, and the vacuum degree of the second top-net vacuum pumping assembly 42 is controlled to be -0.1 to -0.4 MPa.

[0108] In some embodiments, when the first blowing device 34 in the vacuum forming system 30 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 are 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.

[0109] 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.

[0110] In some embodiments, the drying system 60 includes two sets of drying vacuum assemblies 62. The first drying vacuum assemblies 62 are used to absorb and move the carbon nanotube wet film from the endless top net 41 to the endless drying net 61, and the vacuum degree of the first drying vacuum assemblies 62 is controlled to be -0.4 to 1 MPa. The second drying vacuum assemblies 62 are used to continue to dehydrate the carbon nanotube wet film, and the vacuum degree of the second drying vacuum assemblies 62 is controlled to be -0.2 to -0.8 MPa.

[0111] In some embodiments, when the second blowing device in the top web transfer system 40 is used to assist in transferring the carbon nanotube wet film to the endless drying web 61, the blowing pressure of the second blowing device is controlled to be 0.2-0.4 MPa.

[0112] In some embodiments, when drying the carbon nanotube wet film in step S4, the drying temperatures of the two drying devices 63 arranged in sequence along the moving direction of the endless drying web 61 are controlled to be 80-100° C. and 90-150° C., respectively. After the first drying device 63 performs preliminary drying at a relatively low drying temperature, the dry pressing roller 64 is used to reduce the film thickness, and then the second drying device 63 is used to perform drying at a relatively high drying temperature to ensure that the carbon nanotube film is completely dried.

[0113] In some embodiments, during the continuous production of carbon nanotube film, the speed of the endless forming web 31 is controlled to be 0.5-10 m / min, the speed of the endless top web 41 is controlled to be 0.6-11 m / min, and the speed of the endless drying web 61 is controlled to be 0.7-12 m / min. The speeds of the endless forming web 31, the endless top web 41, and the endless drying web 61 are basically the same or gradually increase, and the speed difference is 0.05-0.5 m / min.

[0114] 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 drying net ≥ top net ≥ forming net, and the difference is not large. If the overall 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 speed is too high. If the speed is too low, it will greatly affect the production efficiency and cause energy waste. Secondly, the vibration time of the carbon nanotube film during the transfer will be prolonged, which may cause the carbon nanotube film to be broken. Therefore, the embodiment of the present invention controls the speed of each system within an appropriate range.

[0115] The embodiment of the present invention further provides a carbon nanotube film, which can be prepared by the continuous production system or the continuous preparation method of the above embodiment, 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 Preferably, the thickness of the carbon nanotube film is 30 to 150 μm, and the surface density is 30 to 80 g / m 2 .

[0116] The embodiments of the present invention can adjust the thickness of the prepared carbon nanotube film 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 system, and the gap between the pressing rollers; and can adjust the surface density of the prepared carbon nanotube film 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 system.

[0117] 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.

[0118] The carbon nanotube film continuous production system and continuous preparation method of the present invention are further described below through specific examples.

[0119] Example 1

[0120] 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.

[0121] Among them, the grinding and pulping system 10 is connected to the pulp distribution system, and the pulp distribution system consists of a high-level box 21 and an open flow box 22. The inlet of the high-level box 21 is connected to the grinding and pulping system 10 and is located above the entire production system. The outlet is connected to the flow box 22.

[0122] A first water baffle 223 and a second water baffle 224 are provided in the headbox 22. 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.

[0123] 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.

[0124] 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 .

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Example 2

[0129] This embodiment provides a method for continuously preparing a carbon nanotube film, which is implemented using the continuous production system of embodiment 1. The continuous preparation method includes:

[0130] (1) preparing carbon nanotube slurry;

[0131] 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 is an aqueous polyurethane emulsion with a resin content of 50%, and the addition amount is 24%, so that the resin content in the slurry is 12%; 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%.

[0132] 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.

[0133] (2) preparing a carbon nanotube film from the carbon nanotube slurry;

[0134] First, the carbon nanotube slurry is spread on the endless forming net 31 through the slurry spreading system, and is vacuum filtered and formed by the 8-group forming vacuum pumping component 32 of the vacuum forming system 30 to obtain a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping component 32 is -0.04MPa.

[0135] Next, the carbon nanotube wet film passes through the first top net vacuum assembly 42, two sets of first blowing devices 34, and the vibration device 33, and is transferred to the endless top net 41 under the action of suction, blowing and vibration.

[0136] Among them, the vacuum degree of the first top net vacuum pumping component 42 is -0.8MPa, so as to suck the carbon nanotube wet film from the endless forming net 31 to the endless top net 41; the blowing pressures of the two groups of first blowing devices 34 are 0.1MPa and 0.08MPa respectively; and the vibration pressure of the vibration device 33 is 0.2MPa.

[0137] After the carbon nanotube film is transferred to the endless top net 41, the second top net vacuum pumping assembly 42 is used to continue to remove moisture from the film. The vacuum degree of the second top net vacuum pumping assembly 42 is -0.4 MPa.

[0138] Then, the carbon nanotube wet film is transferred to the endless drying net 61 under the suction of the first drying vacuum assembly 62 and the blowing of the second blowing device 43 .

[0139] The vacuum degree of the first drying vacuum pumping assembly 62 is -0.8 MPa; the pressure of the second blowing device 43 is 0.3 MPa.

[0140] After the carbon nanotube film is transferred to the endless drying net 61, the second drying vacuum assembly 62 is used to continue to remove moisture, and the vacuum degree of the second drying vacuum assembly 62 is -0.4 MPa.

[0141] Finally, the wet carbon nanotube film is dried by two drying devices 63 to obtain a carbon nanotube film, and the carbon nanotube film is rolled up by a rolling device 70. The drying temperatures of the two drying devices are 100°C and 120°C respectively.

[0142] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web 31 in the vacuum forming system 30 is controlled to be 3 m / min, the speed of the endless top web 41 in the top web transfer system 40 is controlled to be 3 m / min, and the speed of the endless drying web 61 in the drying system 60 is controlled to be 3.1 m / min.

[0143] The carbon nanotube film prepared according to the above steps is as follows Figure 3 As shown, its thickness is 180μm and its surface density is 50g / m 2 , the square resistance is 1.5Ω / sq.

[0144] Example 3

[0145] The continuous preparation method of the carbon nanotube film of this embodiment includes:

[0146] (1) preparing carbon nanotube slurry;

[0147] In terms of mass percentage, in addition to solvent water, the carbon nanotube slurry includes: 60% carbon nanotubes, 15% dispersant, 10% resin, 10% flocculant, and 5% 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 butadiene-styrene emulsion with a resin content of 50%; the flocculant is polyaluminum chloride dodecahydrate; and the defoamer is an organic silicon defoamer. The concentration of carbon nanotubes in the slurry is 10%.

[0148] 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.

[0149] (2) preparing a carbon nanotube film from the carbon nanotube slurry;

[0150] First, the carbon nanotube slurry is spread on the endless forming net 31 by the slurry spreading system, and then vacuum-filtered and formed by the 8-group forming vacuum pumping assembly 32 of the vacuum forming system 30 to obtain a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping assembly 32 is -0.04 MPa. Then, the carbon nanotube wet film is rolled by the wet pressing roller 50, and the roller spacing of the wet pressing roller is 0.8 mm.

[0151] Next, the carbon nanotube wet film passes through the first top net vacuuming assembly 42, the two sets of first blowing devices 34, and the vibration device 33, and is transferred to the endless top net 41 under the action of suction, blowing and vibration. Among them, the vacuum degree of the first top net vacuuming assembly 42 is -0.2MPa, so as to suck and transfer the carbon nanotube wet film from the endless forming net 31 to the endless top net 41; the blowing pressures of the two sets of first blowing devices 34 are 0.1MPa and 0.09MPa respectively; and the vibration pressure of the vibration device 33 is 0.2MPa.

[0152] After the carbon nanotube film is transferred to the endless top net 41, the second top net vacuum pumping assembly 42 is used to continue to remove moisture from the film. The vacuum degree of the second top net vacuum pumping assembly 42 is -0.1 MPa.

[0153] Then, the carbon nanotube wet film is transferred to the endless drying net 61 under the suction of the first drying vacuum assembly 62 and the blowing of the second blowing device 43. The vacuum degree of the first drying vacuum assembly 62 is -0.4 MPa, and the pressure of the second blowing device 43 is 0.2 MPa.

[0154] After the carbon nanotube film is transferred to the endless drying net 61, the second drying vacuum assembly 62 is used to continue to remove moisture, and the vacuum degree of the second drying vacuum assembly 62 is -0.2 MPa.

[0155] Finally, 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 carbon nanotube film is obtained and rolled up.

[0156] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web 31 in the vacuum forming system 30 is controlled to be 10 m / min, the speed of the endless top web 41 in the top web transfer system 40 is controlled to be 11 m / min, and the speed of the endless drying web 61 in the drying system 60 is controlled to be 12 m / min.

[0157] The carbon nanotube film prepared according to the above steps is as follows Figure 3 As shown, its thickness is 50μm and its surface density is 20g / m 2 , the square resistance is 6.5Ω / sq.

[0158] Example 4

[0159] The continuous preparation method of the carbon nanotube film of this embodiment includes:

[0160] (1) preparing carbon nanotube slurry;

[0161] In terms of mass percentage, in addition to 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 multi-walled carbon nanotubes with a diameter of 7-15nm and a length of 30-50μm; 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 carbon nanotubes in the slurry is 0.1%.

[0162] 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.

[0163] (2) preparing a carbon nanotube film from the carbon nanotube slurry;

[0164] First, the carbon nanotube slurry is spread on the endless forming net 31 by the slurry spreading system, and then vacuum-filtered and formed by the 8-group forming vacuum pumping assembly 32 of the vacuum forming system 30 to obtain a carbon nanotube wet film; wherein the vacuum degree of the 8-group forming vacuum pumping assembly 32 is -0.08MPa. Then, the carbon nanotube wet film is rolled by a wet pressing roller, and the roller spacing of the wet pressing roller is 3.2mm.

[0165] Next, the carbon nanotube wet film passes through the first top net vacuuming assembly, two sets of first blowing devices 34, and the vibration device 33, and is transferred to the endless top net 41 under the action of suction, blowing and vibration. Among them, the vacuum degree of the first top net vacuuming assembly is -0.8MPa, so as to suck and transfer the carbon nanotube wet film from the endless forming net 31 to the endless top net 41; the blowing pressures of the two sets of first blowing devices 34 are 0.2MPa and 0.16MPa respectively; and the vibration pressure of the vibration device 33 is 0.4MPa.

[0166] After the carbon nanotube film is transferred to the endless top net 41, the second top net vacuum pumping assembly is used to continue to remove moisture from the film. The vacuum degree of the second top net vacuum pumping assembly is -0.3 MPa.

[0167] Then, the carbon nanotube wet film is transferred to the endless drying net 61 through the suction of the first drying vacuum assembly and the blowing of the second blowing device 43 .

[0168] The vacuum degree of the first drying vacuum pumping assembly is -1 MPa; the pressure of the second blowing device 43 is 0.4 MPa.

[0169] After the carbon nanotube film is transferred to the endless drying net 61, the second drying vacuum pumping component is used to continue to remove moisture, and the vacuum degree of the second drying vacuum pumping component is -0.8 MPa.

[0170] Finally, 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; and the obtained carbon nanotube film is rolled up.

[0171] During the entire continuous production process of the carbon nanotube film, the speed of the endless forming web 31 in the vacuum forming system 30 is controlled to be 0.5 m / min, the speed of the endless top web 41 in the top web transfer system 40 is controlled to be 0.6 m / min, and the speed of the endless drying web 61 in the drying system 60 is controlled to be 0.7 m / min.

[0172] The carbon nanotube film prepared according to the above steps is as follows Figure 3 As shown, its thickness is 230μm and its surface density is 64g / m 2 , the square resistance is 0.9Ω / sq.

[0173] Example 5

[0174] The difference between this embodiment and embodiment 2 is that, except for the solvent, the mass percentages of the components in the carbon nanotube slurry are: carbon nanotubes 45%, dispersant 20%, resin 15%, flocculant 15%, and defoamer 5%.

[0175] Example 6

[0176] The difference between this example and Example 2 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%.

[0177] Example 7

[0178] The difference between this example and Example 2 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%.

[0179] Comparative Example 1

[0180] 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:

[0181] Carbon nanotubes 60%, dispersant 20%, flocculant 14%, defoamer 6%.

[0182] 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.

[0183] Comparative Example 2

[0184] 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:

[0185] Carbon nanotubes 60%, dispersant 20%, resin 14%, defoamer 6%.

[0186] 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.

[0187] Comparative Example 3

[0188] 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 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.

[0189] Comparative Example 4

[0190] 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.

[0191] The specific ingredients of the carbon nanotube slurry of each embodiment and comparative example are shown in Table 1.

[0192] Table 1 Content of each component in carbon nanotube slurry except solvent (mass percentage %)

[0193]

[0194] The thickness, surface density, square resistance and other properties of the carbon nanotube films of various embodiments and comparative examples are shown in Table 2.

[0195] Table 2 Thickness, surface density and square resistance of carbon nanotube film

[0196]

[0197] According to Examples 2, 6 and 7, 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.

[0198] According to Example 2 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.

[0199] 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 continuous production system for carbon nanotube films, characterized in that: include: Grinding pulping system, pulp spreading system, vacuum forming system, top web transfer system, drying system and 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 the top web transfer system 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.

2. The system according to claim 1, characterized in that The vacuum forming system comprises: an endless forming net and multiple sets of forming vacuum pumping components; The endless forming net can move cyclically, and the slurry spreading system is used to spread the carbon nanotube slurry on the endless forming net; A plurality of molding vacuum pumping components are sequentially arranged on a side of the endless molding web away from the carbon nanotube wet film along the moving direction of the endless molding web, and the endless molding web is used to drive the carbon nanotube slurry to pass through the plurality of molding vacuum pumping components sequentially; The molding vacuum pumping component is used to perform vacuum filtration on the carbon nanotube slurry to mold it into a carbon nanotube wet film.

3. The system according to claim 2, characterized in that The top net transfer system includes an endless top net and multiple groups of top net vacuuming components; The endless top net can move cyclically, and the multiple groups of top net vacuuming components are sequentially arranged on a side of the endless top net away from the carbon nanotube wet film along the moving direction of the endless top net; the endless top net is used to carry the carbon nanotube wet film and drive the carbon nanotube wet film to pass through the multiple groups of top net vacuuming components sequentially; A portion of the endless top mesh intersects with the endless forming mesh, and at least a portion of the multiple groups of top mesh vacuum components are arranged at a position corresponding to the vacuum forming system and corresponding to the downstream position of the multiple groups of forming vacuum components, for sucking and transferring the formed carbon nanotube wet film to the endless top mesh.

4. The system according to claim 3, characterized in that The vacuum forming system further comprises: a vibration device and a first blowing device; the multiple forming vacuum pumping components, the vibration device and the first blowing device are sequentially arranged on a side of the endless forming web away from the carbon nanotube wet film along the moving direction of the endless forming web, and the endless forming web is used to drive the carbon nanotube wet film to pass through the vibration device and the first blowing device sequentially; The first blowing device and the vibration device are arranged at positions corresponding to the top-net transfer system, and are used to blow and vibrate the carbon nanotube wet film respectively, so as to assist in transferring the carbon nanotube wet film to the top-net transfer system.

5. The system according to claim 1, characterized in that The drying system comprises: an endless drying net, multiple groups of drying vacuum components, and multiple drying devices; The endless drying net can move cyclically, and the multiple groups of drying vacuum components and the multiple drying devices are arranged in sequence along the moving direction of the endless drying net; the endless drying net is used to carry the carbon nanotube wet film and drive the carbon nanotube wet film to pass through the multiple groups of vacuum components and the multiple drying devices in sequence; A portion of the endless drying net intersects with the endless top net of the top net transfer system, and the plurality of sets of drying vacuum assemblies are arranged at positions corresponding to the top net transfer system, and are used to transfer the carbon nanotube wet film to the endless drying net by suction; The plurality of drying devices are arranged in sequence along the moving direction of the endless drying net, and are used to dry the carbon nanotube wet film.

6. The system according to claim 3, characterized in that The top net transfer system also includes a second blowing device; The second blowing device is disposed downstream of the multiple groups of top net vacuuming components and at a position corresponding to the drying system, and is used to blow air to the carbon nanotube wet film to assist in transferring the carbon nanotube wet film to the drying system.

7. The system according to claim 2, characterized in that The slurry distribution system comprises: a headbox, which is arranged above the endless forming wire, and an outlet of the headbox is overlapped on the endless forming wire.

8. The system according to any one of claims 1 to 7, characterized in that: Also includes: A wet pressing roller is disposed between the vacuum forming system and the top web transfer system and is used for rolling the carbon nanotube wet film to accelerate the dehydration of the carbon nanotube wet film.

9. The system according to claim 5, characterized in that The drying system further comprises: dry pressing rollers, which are arranged on both sides of the endless drying net and located between the plurality of drying devices, and are used for rolling the carbon nanotube film to reduce the thickness of the carbon nanotube film.

10. A method for continuously preparing a carbon nanotube film, characterized in that: The method is implemented by the continuous production system according to any one of claims 1 to 9, and comprises: Prepare carbon nanotube slurry; wherein the carbon nanotube slurry comprises: carbon nanotubes, dispersant, resin emulsion, flocculant, defoamer and water; The carbon nanotube slurry is spread on a vacuum forming system, and is formed by vacuum filtration to obtain a carbon nanotube wet film; Transferring the carbon nanotube wet film to a drying system using a top-net transfer system; The carbon nanotube wet film is dried and rolled up to obtain a carbon nanotube film.

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