CN119305094A

CN119305094A - A carbon nanotube film and its continuous preparation method and continuous production system

Info

Publication number: CN119305094A
Application number: CN202411833064.XA
Authority: CN
Inventors: 孙晚红; 张�林; 陈勇; 宋飞虎; 张鹏飞; 刘恩星
Original assignee: Jiangsu New Vision Advanced Functional Fiber Innovation Center Co ltd
Current assignee: Jiangsu New Vision Advanced Functional Fiber Innovation Center Co ltd
Priority date: 2024-12-13
Filing date: 2024-12-13
Publication date: 2025-01-14

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 form a carbon nanotube wet film continuously; 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

Carbon nanotube film, continuous preparation method thereof and continuous production system

Technical Field

The invention relates to the technical field of carbon nanotube film preparation, in particular to a carbon nanotube film, a continuous preparation method and a continuous production system thereof.

Background

In the environment of rapid development of electronic science and technology today, market demands for flexible, wearable and foldable electronic devices are rapidly growing, and basic materials for developing flexible electronic products are receiving a great deal of attention. The carbon nano tube is an ideal stress sensing material with excellent electric conduction, heat conduction and mechanical properties, when the film prepared from the carbon nano tube is strained, the resistance of the film is changed, and the contact state between the carbon nano tubes in the film is also changed, so that the film is suitable for manufacturing the resistance type pressure sensor.

At present, the main preparation methods of the carbon nanotube film are divided into a dry method and a wet method, wherein the dry method comprises a film drawing method, an LB film method, a CVD method and the like, and the wet method comprises a coating method, an electrophoresis method, a vacuum suction filtration method and the like. However, the carbon nanotube film prepared by the dry method has low defect content, perfect structure and excellent performance, but has complicated process and high cost, and cannot meet the market demand. When the film is prepared by a wet method, the carbon nano tube film obtained by a coating method has loose structure and low strength, the electrophoresis method has higher requirement on the uniformity of dispersion of the carbon nano tubes in the electrolyte, the vacuum suction filtration method is simple and easy to operate, the production efficiency is high, the utilization rate of raw materials is high, and the prepared film is uniform.

However, when the carbon nanotube film is prepared by vacuum filtration, the carbon nanotube slurry is difficult to form and retain on a forming net, the strength of the nano wet film is low, so that the carbon nanotube film is difficult to continuously produce in large quantities, and the existing devices adopt support substrates to carry the carbon nanotube wet film in the production process, and the support substrates are limited in size and easy to damage, so that the production cost and the mass production difficulty are increased, and the carbon nanotube film cannot be continuously produced in large quantities.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a carbon nanotube film, a continuous preparation method thereof and a continuous production system thereof, so as to solve the problem that the carbon nanotube film is difficult to realize continuous mass production due to the difficulty in forming and retaining carbon nanotube materials on a filter screen and the low strength of a wet carbon nanotube film when the carbon nanotube film is prepared by vacuum filtration in the prior art.

On one hand, the embodiment of the invention provides a continuous preparation method of a carbon nanotube film, which comprises the steps of S1, preparing carbon nanotube slurry, S2, continuously spreading the carbon nanotube slurry on a circulating endless forming net, carrying out vacuum suction filtration on the carbon nanotube slurry to continuously form a carbon nanotube wet film, S3, transferring the carbon nanotube wet film to the circulating endless drying net, S4, drying the carbon nanotube wet film, and rolling the dried carbon nanotube film to obtain a continuous coiled carbon nanotube flexible film.

Further, the carbon nanotube slurry comprises, in mass percent, 40% -60% of carbon nanotubes, 10% -20% of dispersing agents, 10% -20% of resins, 10% -20% of flocculating agents and 3% -6% of defoaming agents, except for solvents.

Further, the resin adopts water-soluble resin emulsion, and the resin emulsion comprises at least one of water-soluble polyurethane emulsion, acrylic emulsion and styrene-butadiene emulsion.

Further, the flocculant comprises at least one of ferrous sulfate, magnesium sulfate, aluminum potassium sulfate dodecahydrate, polyaluminum chloride and ferric trichloride.

Further, in step S3, the wet carbon nanotube film is transferred to the endless drying net which moves circularly 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 wet carbon nanotube film from the endless forming net to the endless drying net by suction.

In step S3, when the endless forming net drives the carbon nanotube wet film to move to a position where the carbon nanotube wet film is intersected with the endless top net, the carbon nanotube wet film is sucked through the first top net vacuumizing assembly, and the carbon nanotube wet film is transferred from the endless forming net to the endless top net.

In step S3, when the first top net vacuumizing assembly sucks the carbon nano tube wet film, the carbon nano tube wet film is vibrated and blown by the vibration device and the first blowing device respectively, and the carbon nano tube wet film is assisted to be transferred to the endless top net under the vibration and blowing actions.

In step S3, when the endless top net drives the carbon nanotube wet film to move to a position where the endless top net interfaces with the endless drying net, the carbon nanotube wet film is pumped through the first drying and vacuumizing assembly so as to transfer the carbon nanotube wet film from the endless top net to the endless drying net.

In step S2, the carbon nano tube sizing agent is continuously paved on the endless forming net in a circulating movement mode through the sizing system.

On the other hand, the embodiment of the invention provides a carbon nanotube film, which is prepared by adopting the continuous preparation method in the embodiment, wherein the thickness of the carbon nanotube film is 30-500 mu m, and the surface density of the carbon nanotube film is 20-200 g/m ².

On the other hand, the embodiment of the invention also provides a continuous production system for realizing the continuous preparation method of the carbon nanotube film, which comprises a grinding pulping system, a pulp distribution system, a vacuum forming system, a top net transfer system, a drying system and a winding device, wherein the grinding pulping system is used for preparing carbon nanotube pulp, the pulp distribution system is connected with the grinding pulping system and is positioned above the vacuum forming system and is connected with the vacuum forming system for tiling the carbon nanotube pulp on the vacuum forming system, the vacuum forming system is used for filtering moisture in the carbon nanotube pulp to obtain the 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 suction effect, the drying system is used for drying the carbon nanotube wet film to obtain the carbon nanotube film, and the winding device is connected with the drying system and is used for winding the dried carbon nanotube film.

The continuous preparation method and the production system of the carbon nanotube film can at least realize one of the following beneficial effects:

1. when the carbon nano tube film is produced by adopting the vacuum suction filtration method, the continuous carbon nano tube wet film is directly supported by the endless forming net which moves circularly, the carbon nano tube wet film is directly transferred to the endless drying net and dried, the prepared carbon nano tube film can be rolled into a roll, the continuous preparation of the carbon nano tube film is realized, the auxiliary production of a supporting substrate is not required, and the production quantity of the carbon nano tube film is not limited by the size of the supporting substrate. In addition, the resin and the flocculating agent are added into the carbon nanotube slurry, so that the forming retention of the carbon nanotube material on the endless forming net is facilitated, the strength and the self-supporting property of the carbon nanotube film are improved, the continuous film forming of the carbon nanotube slurry on the endless forming net is further ensured, and the large-scale industrial production of the carbon nanotube flexible film is realized in a large quantity, continuously, at low cost and high efficiency.

2. The invention adopts the forming net and the drying net to bear and process the carbon nano tube films with different dryness, thereby prolonging the service life of each net and reducing the production cost.

3. According to the invention, the components such as the carbon nano tube, the resin, the flocculating agent and the like are in a proper range by optimizing the formula of the carbon nano tube slurry, so that the specific good conductivity of the prepared carbon nano tube film can be ensured while the deposition rate of the carbon nano tube material on a forming net and the strength of the carbon nano tube film are improved.

4. According to the invention, the carbon nanotube wet film is transferred from the endless forming net to the endless drying net by utilizing the top net transfer system through the suction effect, so that the carbon nanotube wet film is easy to separate from the forming net and transfer, and the continuous preparation of the carbon nanotube film is facilitated.

5. The carbon nanotube film prepared by the invention has adjustable thickness and surface density, has excellent electric conduction, heat conduction, flexibility and other performances, and can be widely applied as a material for preparing flexible sensors, supercapacitors, heating materials and other electronic devices.

In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to designate like parts throughout the drawings;

FIG. 1 is a schematic flow chart of a continuous preparation method of a carbon nanotube film according to some embodiments of the present invention;

FIG. 2 is a schematic diagram of a continuous production system for carbon nanotube films according to some embodiments of the present invention;

FIG. 3 is a schematic view of the structure of a headbox in a continuous production system according to some embodiments of the invention;

fig. 4 is a physical diagram of a carbon nanotube film prepared in example 1 of the present invention.

Reference numerals illustrate:

10-grinding pulping system, 21-high-level box, 22-head 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-driving roller, 32-forming vacuumizing component, 33-vibrating device, 34-first blowing device, 40-top net transferring system, 41-endless top net, 42-top net vacuumizing component, 43-second blowing device, 50-wet squeezing roller, 60-drying system, 61-endless drying net, 62-drying vacuumizing component, 63-drying device, 64-dry squeezing roller, 70-rolling device and 1-carbon nano tube film.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments of the present invention will be described hereinafter with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In the interest of clarity and conciseness, not all features of an actual implementation are described in this specification.

It should be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only the device structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details not greatly related to the present invention are omitted.

An embodiment of the present invention provides a continuous preparation method of a carbon nanotube film, as shown in fig. 1, comprising the steps of:

And S1, preparing carbon nano tube slurry, wherein the carbon nano tube slurry comprises carbon nano tubes, a dispersing agent, resin, a flocculating agent and a defoaming agent.

And S2, spreading the carbon nano tube slurry on a circulating endless forming net, and carrying out vacuum suction filtration on the carbon nano tube slurry to continuously form the carbon nano tube wet film.

And step S3, transferring the carbon nano tube wet film to an endless drying net.

And S4, drying the carbon nanotube wet film, and rolling the dried carbon nanotube film to obtain the continuously rolled carbon nanotube flexible film.

The embodiment of the invention directly supports the continuous carbon nanotube wet film through the endless forming net which circularly moves, realizes the continuous preparation of the carbon nanotube film, does not need to consume a supporting substrate for auxiliary production, has the advantages of no limitation of the size of the supporting substrate on the production capacity of the carbon nanotube film, and is beneficial to continuous and large-scale production of the carbon nanotube film, and has simple operation, low cost and high efficiency.

In addition, the carbon nano tube films with different dryness are borne by the endless forming net and the endless drying net, so that the service lives of the nets are prolonged, and the production cost is reduced. In the present invention, the endless forming wire means a forming wire connected to both ends in the longitudinal direction, and the endless drying wire means a drying wire connected to both ends in the longitudinal direction.

The invention is beneficial to the forming retention of the carbon nanotube material on the endless forming net by adding the resin and the flocculating agent into the carbon nanotube slurry, improves the strength and the self-supporting property of the carbon nanotube film, and further ensures the continuous film forming of the carbon nanotube slurry on the endless forming net.

In some embodiments, the carbon nanotube slurry comprises, in mass percent, 40% -60% carbon nanotubes, 10% -20% dispersant, 10% -20% resin, 10% -20% flocculant, 3% -6% defoamer, and the sum of the components is 100%. The concentration of the carbon nano tube in the carbon nano tube slurry is controlled to be 0.1-10%.

The flocculant can cooperate with the resin emulsion to improve the forming retention of the carbon nanotube slurry on a forming net and improve the strength of the carbon nanotube film. According to the embodiment of the invention, the content of the carbon nano tube, the resin emulsion and the flocculant is controlled, so that the obtained carbon nano tube film has excellent conductivity and strength.

In some embodiments, the content of the resin and the flocculant is 1:0.9-1.1, preferably 1:1, so that the resin emulsion and the flocculant react to form a combined structure of carbon nano tube particle-brooming emulsion, which is beneficial to the forming and retaining of the carbon nano tube slurry on a forming net and improves the strength of the carbon nano tube film.

Wherein the carbon nanotubes are single-walled carbon nanotubes or multi-walled carbon nanotubes. The diameter of the single-wall carbon nano tube is 0.4-2 nm, the length is 1-500 mu m, the diameter is preferably 0.4-2 nm, the length is 20-200 mu m, the diameter of the multi-wall carbon nano tube is 2-100 nm, the length is 1-500 mu m, the diameter is preferably 2-20 nm, and the length is 20-200 mu m.

In some embodiments, the dispersant is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, anionic polyacrylamide, polyethylene oxide, polyvinylpyrrolidone, carboxylated nanocellulose. The carbon nanotubes are difficult to disperse due to the existence of Van der Waals force, and the dispersing agent is added in the embodiment of the invention, so that the carbon nanotubes are dispersed under the actions of grinding, ultrasonic and the like, and the conductivity of the carbon nanotubes is fully exerted.

In some embodiments, the defoamer is at least one of an organosilicon defoamer and a polyether defoamer, which can effectively reduce foam generated by the dispersant in the stirring process.

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 comprises at least one of water-soluble polyurethane emulsion, acrylic emulsion and butylbenzene emulsion.

In some embodiments, the flocculant comprises at least one of ferrous sulfate, magnesium sulfate, aluminum potassium sulfate dodecahydrate, polyaluminum chloride, ferric trichloride.

In step S1, when preparing the carbon nanotube slurry, firstly, mixing the carbon nanotubes with a dispersing agent in water, and grinding or ultrasonic dispersing the mixture in the carbon nanotube dispersion, and adding a defoaming agent to eliminate foam, thereby obtaining the carbon nanotube dispersion.

Then, the resin emulsion is added into the carbon nanotube dispersion liquid, and the mixture is mixed and stirred, and then the flocculant is added, and the mixture is stirred and mixed. The flocculant is utilized to destroy the emulsion particle structure, so that a combined structure of carbon nano tube particles and brooming emulsion is formed, the carbon nano tube slurry is beneficial to forming and retaining on a forming net, and the strength of the formed carbon nano tube film is improved.

In some embodiments, in step S1, a grinding and pulping system may be used to prepare the carbon nanotube slurry, and the grinding and dispersing are performed on the carbon nanotube slurry by using the grinding and pulping system to obtain the uniformly dispersed carbon nanotube slurry.

In some embodiments, a pulp distribution system is arranged above the endless forming wire, and the outlet of the pulp distribution system is lapped on the endless forming wire. In step S2, the carbon nanotube slurry may be continuously laid on the endless forming wire that moves in a circulating manner by the slurry distribution system, so that the carbon nanotube slurry is continuously formed into a film, and the risk of being unable to continuously form a film can be reduced compared with the slurry spraying method.

In some embodiments, the distribution system includes a headbox that can provide a stable, uniform cross-directional pulp flow distribution for an endless forming wire.

In some embodiments, as shown in fig. 3, the headbox 22 may be an open-top headbox with an inlet 221 disposed at the bottom of the headbox, an outlet 222 disposed on the side of the headbox 22, and a first water baffle 223 and a second water baffle 224 disposed inside the headbox 22, the first water baffle 223 and the second water baffle 224 being disposed sequentially on the side of the outlet 222 of the headbox 22 along the outlet direction of the carbon nanotube slurry, forming the outlet 222 with the bottom of the headbox 22.

In step S2, the carbon nanotube slurry may be continuously delivered from the bottom inlet 221 of the headbox 22 into the cavity of the headbox 22, so that the carbon nanotube slurry flows through the lower outlets of the first water baffle 223 and the second water baffle 224 in sequence to the endless forming wire, which is moving circularly, to provide continuous, stable and uniform transverse slurry flow for the endless forming wire.

In some embodiments, the top of the first water baffle 223 and the second water baffle 224 are respectively provided with a regulating valve 225, and before the slurry distribution starts in step S2, the distance between the first water baffle 223 or the second water baffle 224 and the bottom can be regulated by rotating the regulating valve 225, so as to prepare carbon nanotube wet films with different thicknesses.

In some embodiments, a plurality of forming vacuum assemblies are disposed along the direction of movement of the endless forming wire, the forming vacuum assemblies being located on a side of the endless forming wire remote from the wet film of carbon nanotubes. In step S2, the carbon nanotube slurry laid on the endless forming net may be vacuum filtered by the forming vacuum assembly, so as to form a continuous carbon nanotube wet film.

In some embodiments, when the carbon nanotube slurry is vacuum-filtered and formed in step S2, the vacuum degree of the plurality of forming vacuum-pumping components is controlled to be-0.08 to-0.04 MPa so as to pump out part of the water in the carbon nanotube slurry.

The embodiment of the invention controls the forming vacuumizing assembly under a proper vacuum degree, can slowly suck away the moisture in the carbon nano tube slurry to prepare the carbon nano tube wet film, if the vacuum degree is too small, the obtained carbon nano tube wet film has larger moisture and larger thickness, and the rolling effect is affected, and if the vacuum degree is too large, on one hand, the resin component in the carbon nano tube slurry is sucked away, so that the strength of the prepared carbon nano tube film is reduced, and on the other hand, the carbon nano tube wet film is clung to a forming net, and cannot be completely transferred to the top net.

In some embodiments, after the carbon nanotube slurry is formed by vacuum filtration, the formed carbon nanotube wet film may be rolled by a wet press roll to accelerate dehydration of the carbon nanotube wet film and reduce the film thickness.

In some embodiments, the roll spacing of the wet press rolls can be controlled to be 50-90% of the thickness of the carbon nanotube wet film, so that the carbon nanotube wet film can be effectively rolled and dehydrated, abrasion of the carbon nanotube wet film caused by rolling is reduced, and the thickness of the carbon nanotube film is prevented from being too thin.

In some embodiments, in step S3, the wet carbon nanotube film may be transferred to the endless drying wire by a top wire transfer system disposed between the endless forming wire and the endless drying wire, the top wire transfer system transferring the wet carbon nanotube film from the endless forming wire to the endless drying wire by suction. Compared with the transfer of the carbon nano tube film by the pressing roller, the invention transfers the carbon nano tube wet film by the suction effect, so that the carbon nano tube wet film is more easily separated from the endless forming net and is attached to the target net.

Specifically, as shown in FIG. 2, a top web transfer system 40 is disposed between the endless forming wire 31 and the endless drying wire 61. In some embodiments, top web transfer system 40 includes an endless top web 41, with different locations of endless top web 41 interfacing with an endless forming web 31 and an endless drying web 61, respectively.

In step S3, transferring the wet carbon nanotube film includes transferring the wet carbon nanotube film to the endless top net 41 by suction when the endless forming net 31 drives the wet carbon nanotube film to move to the position where it interfaces with the endless top net 41, and transferring the wet carbon nanotube film to the endless drying net 61 by suction when the endless top net 41 drives the wet carbon nanotube film to move to the position where it interfaces with the endless drying net 61. The invention uses the endless top net 41 as a bridge, and can smoothly transfer the carbon nano tube wet film from the endless forming net to the unconnected endless drying net.

In some embodiments, as shown in fig. 2, the top mesh transfer system 40 includes a first top mesh evacuation assembly 42, the first top mesh evacuation assembly 42 being disposed on a side of the endless top mesh 41 remote from the wet carbon nanotube film.

In step S3, when the endless forming wire 31 drives the carbon nanotube wet film to move to the position interfacing with the endless top wire 41, the first top wire vacuum pumping assembly 42 pumps the carbon nanotube wet film, and the carbon nanotube wet film is transferred from the endless forming wire 31 to the endless top wire 41.

In some embodiments, the vacuum level of the first top net vacuum assembly 42 may be controlled to be-0.2 to-0.8 MPa. The embodiment of the invention controls the first top net vacuumizing assembly 42 under a proper vacuum degree, so that the wet film of the carbon nano tube can be sucked and transferred to the endless top net 41, and the situation that the wet film clings to the top net and cannot be transferred to the drying net due to the excessive vacuum degree is avoided.

In some embodiments, the top web transfer system further comprises a second top web evacuation assembly located downstream of the first top web evacuation assembly. After the carbon nanotube wet film is transferred to the endless top net 41, vacuum filtration and dehydration can be continuously performed on the carbon nanotube wet film through the second top net vacuum pumping assembly. Preferably, in the production process, the vacuum degree of the second top net vacuumizing assembly can be controlled to be-0.1 to-0.4 MPa.

In some embodiments, as shown in fig. 2, a vibration device 33 and two sets of first blowing devices 34 are sequentially provided along the moving direction of the endless forming wire 31.

In step S3, when the first top net vacuum pumping assembly 42 pumps the wet carbon nanotube film, the wet carbon nanotube film may be further vibrated and blown by the vibration device 33 and the first blowing device 34, respectively, so as to be transferred to the endless top net 41 under the vibration and blowing actions. The invention simultaneously shakes, blows and sucks the carbon nano tube wet film, so that the carbon nano tube film is easy to separate from the endless forming net and is transferred and attached to the endless top net, the transfer effect is good, and the operation is simple and convenient.

In some embodiments, when the vibration device 33 is used to assist in transferring the wet carbon nanotube film, the vibration pressure of the vibration device 33 in the vacuum forming system 30 is controlled to be 0.1-0.4 mpa, so as to assist in transferring the wet carbon nanotube film to the top net. If the vibration pressure is too large, the wet carbon nanotube film is crushed, and if the vibration pressure is too small, the aim of assisting the wet carbon nanotube film to separate from the forming net cannot be achieved.

In some embodiments, when the first blowing devices 34 are used to assist in transferring the wet carbon nanotube film, the blowing pressures of the two sets of first blowing devices 34 sequentially arranged along the moving direction of the endless forming wire 31 may be controlled to be 0.1-0.2 mpa and 0.08-0.16 mpa. If the blowing pressure is too high, the wet carbon nanotube film is blown, and if the blowing pressure is too low, the auxiliary transfer purpose cannot be achieved.

In some embodiments, as shown in fig. 2, the side of the endless drying wire 61 remote from the wet carbon nanotube film is provided with a first dry vacuum assembly 62.

In step S3, when the endless top net 41 drives the carbon nanotube wet film to move to the position interfacing with the endless drying net 61, the carbon nanotube wet film is pumped by the first drying and evacuating assembly 62 to transfer the carbon nanotube wet film from the endless top net 41 to the endless drying net 61.

In some embodiments, the vacuum level of the first dry vacuum assembly 62 may be controlled to-0.4 to-1 MPa. The embodiment of the present invention controls the first drying and vacuumizing assembly 62 under a proper vacuum degree, so as to avoid that the vacuum degree is too small to be transferred smoothly, and simultaneously avoid that the wet film is damaged or clings to the drying net to be separated later.

In some embodiments, a second dry vacuum assembly is also provided downstream of the first dry vacuum assembly. After the wet carbon nanotube film is transferred to the endless drying net 61, the carbon nanotube film may be continuously subjected to suction filtration and dehydration through the second drying and vacuum pumping assembly. In some embodiments, the vacuum level of the second dry vacuum assembly can be controlled to be-0.2 to-0.8 MPa.

In some embodiments, as shown in fig. 2, the top web transfer system 40 further comprises a second air blower 43, the second air blower 43 being located at a position corresponding to the endless drying web 61. When the first dry vacuuming module 62 sucks the wet carbon nanotube film, the carbon nanotube film may be further blown by the second blowing device 43 to assist in transferring the carbon nanotube film to the endless drying net 61.

In some embodiments, the blowing pressure of the second blowing device can be controlled to be 0.2-0.4 mpa, so that the wet carbon nanotube film is prevented from being blown out due to the overlarge blowing pressure, and the aim of assisting in transferring cannot be achieved due to the overlarge blowing pressure.

In some embodiments, two drying devices are provided along the direction of movement of the endless drying wire. In step S4, the carbon nanotube wet film may be dried by a drying device.

In some embodiments, the drying temperatures of two drying devices sequentially arranged along the moving direction of the endless drying wire may be controlled to be 80-100 ℃ and 90-150 ℃ respectively. And after the primary drying is performed at a lower drying temperature by using the first drying device, the carbon nano tube film is dried at a higher drying temperature by using the second drying device, so that the carbon nano tube film is completely dried.

In some embodiments, the wet carbon nanotube film may also be rolled by a dry press roll to reduce the thickness of the wet carbon nanotube film before it is completely dried. Specifically, the wet carbon nanotube film may be rolled after the first drying, so that the film thickness is reduced.

In some embodiments, the roll gap of the dry press roll may be controlled to be 50-90% of the thickness of the wet carbon nanotube film, and the thickness of the final carbon nanotube film may be controlled by controlling the roll gap of the dry press roll.

In some embodiments, in the continuous production process of the carbon nanotube film, the speed of the endless forming wire is controlled to be 0.5-10 m/min, the speed of the endless top wire is controlled to be 0.6-11 m/min, the speed of the endless drying wire is controlled to be 0.7-12 m/min, the speeds of the endless forming wire, the endless top wire and the endless drying wire are basically consistent or gradually become larger, and the speed difference is controlled to be 0.05-0.5 m/min.

In the continuous production process, as the wet carbon nanotube film is dehydrated and even stretched after drying, the embodiment of the invention controls the speed of each system to be v _{Drying net}≥v_{Top net}≥v_{Forming net} and the speed is not very different. If the overall speed is too high, firstly the dehydration effect of the wet carbon nanotube film is weakened, secondly the blowing force of the blowing device applied in unit time is insufficient during transfer, the transfer is likely to be unsuccessful, and finally the wet carbon nanotube film cannot be completely dried due to the excessive speed during drying. If the speed of the vehicle is too small, the production efficiency can be greatly influenced, the energy consumption is wasted, and the time that the carbon nano tube film is subjected to vibration during transferring is prolonged, so that the carbon nano tube film is shattered. Thus, embodiments of the present invention control the vehicle speed of each network within a suitable range.

In some embodiments, the thickness of the resulting carbon nanotube film can be adjusted by adjusting the ratio of the components in the carbon nanotube slurry, the concentration of the slurry, the distance of the water deflector from the bottom in the headbox, the speed of the respective wire, the gap of the press roll.

In some embodiments, the areal density of the produced carbon nanotube film can be adjusted by adjusting the ratio of the components in the carbon nanotube slurry, the concentration of the slurry, the distance of the water baffle from the bottom in the headbox, and the speed of the respective webs.

The embodiment of the invention also provides a carbon nano tube film which can be prepared by adopting the continuous preparation method of the embodiment, wherein the thickness of the carbon nano tube film is 30-500 mu m, and the surface density of the carbon nano tube film is 20-200 g/m ². Preferably, the carbon nanotube film has a thickness of 30-150 μm and an areal density of 30-80 g/m ².

The thickness and the surface density of the carbon nanotube film prepared by the invention are adjustable, and the carbon nanotube film has excellent electric conduction, heat conduction, flexibility and other performances, and can be widely applied as a material for preparing electronic devices such as flexible sensors, supercapacitors, heating materials and the like.

The embodiment of the invention also provides a continuous production system of the carbon nano tube film, which comprises a grinding pulping system 10, a pulp distribution system, a vacuum forming system 30, a top net transfer system 40, a drying system 60 and a winding device 70, as shown in fig. 2. The grinding pulping system 10 is used for preparing carbon nanotube slurry, the slurry distribution system is connected with the grinding pulping system 10, is positioned above the vacuum forming system 30 and is connected with the vacuum forming system 30, and is used for tiling the carbon nanotube slurry on the vacuum forming system 30. The vacuum forming system 30 is used for filtering moisture in the carbon nanotube slurry to obtain a wet carbon nanotube film, and the top net transfer system 40 is disposed between the vacuum forming system 30 and the drying system 60 and is configured to transfer the wet carbon nanotube film from the vacuum forming system 30 to the drying system 60 by suction. The drying system 60 is used for drying the wet carbon nanotube film to obtain a carbon nanotube film, and the winding device 70 is used for winding the dried carbon nanotube film.

According to the continuous production system provided by the invention, the carbon nano tube is molded through the grinding pulping system, the pulp distribution system and the vacuum molding system which are sequentially connected, and then the carbon nano tube wet film is transferred from the vacuum molding net to the drying system through the suction effect by adopting the top net transfer system, so that the carbon nano tube wet film is easily separated from the molding net and is transferred to the drying net for drying, and the continuous preparation of the carbon nano tube film is facilitated.

In some embodiments, as shown in fig. 2, the slurry distribution system includes a headbox 21 and a headbox 22, where the headbox 21 is configured to temporarily store the carbon nanotube slurry, its inlet is connected to the polishing slurry system 10, its outlet is connected to the inlet of the headbox 22, the outlet of the headbox 22 is connected to the vacuum forming system 30, and the headbox 22 is configured to homogenize and rectify the carbon nanotube slurry and tile it on the forming wire of the vacuum forming system 30.

In contrast to the existing continuous production systems which adopt a process that a headbox is lapped on an endless forming net to enable the carbon nanotube slurry to be continuously paved on the forming net, the continuous film forming of the carbon nanotube slurry can be achieved, and the risk of discontinuous film forming of the carbon nanotube slurry is reduced.

As shown in fig. 2, the head box 21 is located above the whole production system, a transfer pump is connected between the grinding and pulping system 10 and the head box 21, the carbon nanotube slurry is pumped into the head box 21 by the transfer pump, and the carbon nanotube slurry in the head box 21 flows into the head box 22 by gravity.

In some embodiments, as shown in fig. 3, the head box 22 is an open top head box, an inlet 221 thereof is provided at a bottom of the head box, an outlet 222 is provided at a side of the head box 22, and a first water baffle 223 and a second water baffle 224 are provided inside the head box 22, the first water baffle 223 and the second water baffle 224 being sequentially arranged at one side of the outlet 222 of the head box 22 along an outlet direction of the carbon nanotube slurry, and the outlet 222 being formed between the bottom of the head box 22. The carbon nanotube slurry flows into the cavity of the head box 22 from the bottom inlet 221 of the head box 22, and then flows through the lower outlets of the first water baffle 223 and the second water baffle 224 in sequence to flow into the vacuum forming system 30. By providing the first splash plate 223 and the second splash plate 224, a stable, uniform cross-slurry flow distribution can be provided to the vacuum forming system 30.

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

In some embodiments, the top of the first water baffle 223 and the second water baffle 224 are respectively provided with a regulating valve 225, and the height of the first water baffle 223 or the second water baffle 224 can be regulated by rotating the regulating valve 225, so as to obtain carbon nano tube wet films with different thicknesses.

As shown in FIG. 2, in some embodiments, the vacuum forming system 30 includes an endless forming wire 31, a multi-set forming vacuum assembly 32. The endless forming net 31 is capable of moving circularly, and the slurry distribution system is used for spreading the carbon nanotube slurry on the endless forming net 31. The multi-group forming vacuum-pumping assemblies 32 are sequentially arranged on one side of the endless forming net 31 far 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 for driving the carbon nanotube wet film to sequentially pass through the multi-group forming vacuum-pumping assemblies 32. The forming vacuum-pumping assembly 32 is used for vacuum-pumping and filtering the carbon nanotube slurry, and pumping out part of water in the carbon nanotube slurry to form the carbon nanotube slurry into a carbon nanotube wet film. Preferably, the molded vacuum extractor assembly is at least 4 sets.

Specifically, the endless forming wire 31 is supported and moved by a plurality of driving rollers 311, for example, as shown in fig. 2,4 driving rollers support the endless forming wire 31 and move it along a rectangular path in a circulating manner.

In some embodiments, the headbox 22 is disposed above the endless forming wire 31, and the outlet 222 of the headbox 22 is overlapped on the endless forming wire 31, and the moving direction of the endless forming wire 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 head box 22 onto the endless forming wire 31, the carbon nanotube slurry is spread on the endless forming wire 31 under the movement of the endless forming wire 31, so that a continuous wet film of carbon nanotubes is obtained.

Further, at least a portion of the plurality of forming vacuum-pumping assemblies 32 is disposed at a position corresponding to the headbox 22, and the forming vacuum-pumping assemblies 32 vacuum-pump-filter the carbon nanotube slurry, thereby filtering the moisture in the carbon nanotube slurry and forming the carbon nanotube wet film.

As shown in fig. 2, in some embodiments, vacuum forming system 30 is disposed in juxtaposition with drying system 60, top web transfer system 40 is disposed above vacuum forming system 30 and drying system 60 and interfaces with vacuum forming system 30 and drying system 60, respectively, and top web transfer system 40 serves as a bridge for transferring wet carbon nanotube film from endless forming web 31 to drying system 60 by suction.

In some embodiments, as shown in fig. 2, the top web transfer system 40 includes an endless top web 41, a plurality of sets of top web vacuum assemblies 42. The endless top net 41 is capable of moving circularly, and the plurality of groups of top net vacuum pumping assemblies 42 are sequentially arranged on one 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 for bearing the carbon nanotube wet film and driving the carbon nanotube wet film to sequentially pass through the plurality of groups of top net vacuum pumping assemblies 42. At least a portion of the plurality of top mesh vacuum pumping assemblies 42 are disposed at a position corresponding to the endless forming mesh 31 of the vacuum forming system 30 and downstream of the plurality of top mesh vacuum pumping assemblies 32, and the plurality of top mesh vacuum pumping assemblies 42 are at least used for pumping and transferring the wet carbon nanotube film on the endless forming mesh 31 to the endless top mesh 41.

Specifically, the endless top net 41 is supported and moved by a plurality of driving rollers, for example, as shown in fig. 2, which support the endless top net 41 and move it along a rectangular path in a circulating manner. Part of the endless top net 41 interfaces with one side of the endless forming net 31 and part interfaces with the drying system, so that the wet film of carbon nanotubes can be transferred from the endless forming net 31 to the drying system 60 through the endless top net 41.

In the embodiment of the present invention, the movement direction of the endless top net 41 is opposite to that of the endless forming net 31, so that the movement direction of the part where the endless top net 41 and the endless forming net intersect is the same, to facilitate the transfer of the wet film of the carbon nanotubes from the endless forming net 31 to the endless top net 41. For example, the endless forming wire 31 moves in a clockwise direction and the endless top wire 41 moves in a counterclockwise direction.

In some embodiments, as shown in FIG. 2, the vacuum forming system 30 further includes a first blower 34, a vibration device 33. The multi-group forming vacuum-pumping assembly 32, the vibration device 33 and the first blowing device 34 are sequentially arranged on one side of the endless forming net 31 far 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 for driving the carbon nanotube wet film to sequentially pass through the forming vacuum-pumping assembly 32, the vibration device 33 and the first blowing device 34. The first blowing device 34 and the vibration device 33 are disposed at positions corresponding to the top net transfer system 40, and are used for blowing and vibrating the wet carbon nanotube film, respectively, so as to transfer the wet carbon nanotube film to the top net transfer system 40 in an auxiliary manner.

Specifically, the vibration device 33 and the first blowing device 34 in the vacuum forming system 30 are disposed at positions corresponding to the endless top net 41, the top net vacuum pumping assembly 42 in the top net transfer system 40 is disposed at positions corresponding to the endless forming net 31, and at least one set of top net vacuum pumping assemblies 42 corresponds to the vibration device 33 and/or the first blowing device 34, so that the wet carbon nanotube film can be transferred to the endless top net 41 under the actions of vibration, blowing and suction.

When the carbon nano tube wet film on the endless forming net 31 moves to pass through the vibration device 33 and the first blowing device 34 in sequence, the carbon nano tube wet film gradually breaks away from the endless forming net 31 under the vibration of the vibration device 33 and the blowing action of the first blowing device 34, and simultaneously, the carbon nano tube wet film is adsorbed and transferred to the endless top net 41 under the suction action of the top net vacuumizing assembly 42.

Preferably, the vibration means 33 are at least one group and the first blowing means 34 are at least two groups. The wet carbon nanotube film is continuously blown by the two sets of first blowing devices 34, so that the auxiliary transfer effect is improved. The distance between the two groups of first blowing devices 34 is set to be 8-12 cm, if the distance is too large, the wet carbon nanotube film cannot be continuously blown to reduce the transfer effect, and the first blowing devices 34 occupy a certain space, so that the minimum distance is 8cm.

In some embodiments, the top mesh transfer system 40 includes at least two sets of top mesh vacuum pumping assemblies 42, a first top mesh vacuum pumping assembly and a second top mesh vacuum pumping assembly, wherein the first top mesh vacuum pumping assembly is disposed at a position corresponding to the vibration device 33 and/or the first blowing device 34 for adsorbing the wet carbon nanotube film to the endless top mesh 41, and the second top mesh vacuum pumping assembly is disposed downstream of the first top mesh vacuum pumping assembly for further dehydrating the wet carbon nanotube film after transferring the wet carbon nanotube film to the endless top mesh 41, thereby improving the dehydration effect.

In some embodiments, as shown in fig. 2, the continuous production system further includes a wet press roll 50, the wet press roll 50 being disposed between the vacuum forming system 30 and the top net transfer system 40 for rolling the wet carbon nanotube film to accelerate dehydration of the wet carbon nanotube film.

Specifically, a pair of wet press rolls 50 are respectively disposed on one side of the endless forming wire 31 and the endless top wire 41 away from the wet carbon nanotube film, so that the endless forming wire 31 and the endless top wire 41 can move through the roll gap of the wet press rolls 50, thereby rolling the wet carbon nanotube film on the endless forming wire 31, accelerating the dehydration of the wet carbon nanotube film, and reducing the thickness of the wet carbon nanotube film.

In some embodiments, the roll gap of the wet pressing roll 50 is 50-90% of the thickness of the wet carbon nanotube film, so that the wet carbon nanotube film can be effectively rolled and dehydrated, abrasion of the wet carbon nanotube film caused by rolling is reduced, and the thickness of the wet carbon nanotube film is prevented from being too thin.

As shown in fig. 2, a portion of the plurality of forming vacuum assemblies 32 is disposed at a position corresponding to the headbox 22 and another portion is disposed at a position corresponding to the endless top wire 41 downstream of the wet press roll 50, such that the carbon nanotube slurry is subjected to vacuum filtration forming by the partial forming vacuum assemblies 32 and then further dewatered by the wet press roll 50 and the other partial forming vacuum assemblies 32 in sequence.

In some embodiments, as shown in FIG. 2, the drying system 60 includes an endless drying wire 61, multiple sets of drying vacuum assemblies 62, and multiple drying devices 63. The endless drying net 61 is capable of circularly moving, the plurality of groups of drying vacuum-pumping assemblies 62 and the plurality of drying devices 63 are sequentially arranged along the moving direction of the endless drying net 61, and the endless drying net 61 is used for carrying the carbon nanotube wet film and driving the carbon nanotube wet film to sequentially pass through the plurality of groups of drying vacuum-pumping assemblies 62 and the plurality of drying devices 63 so as to dry the carbon nanotube wet film to form the carbon nanotube film.

At least a portion of the multiple sets of drying vacuum-pumping assemblies 62 are disposed at a position corresponding to the top mesh transfer system 40 for adsorbing and moving the wet carbon nanotube film to the endless drying mesh 61. The drying device is used for drying the wet carbon nanotube film to obtain the carbon nanotube film 1.

Specifically, the endless drying wire 61 is supported and moved by a plurality of driving rollers, for example, as shown in fig. 2, which support the endless drying wire 61 and move it in a circulating manner. A portion of the endless top net 41 interfaces with one side of the endless forming net 31 and a portion interfaces with the endless drying net 61, 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.

In the embodiment of the present invention, the movement direction of the endless drying wire 61 and the endless top wire 41 is opposite to the movement direction of the endless forming wire 31, so that the movement direction of the portion of the endless top wire 41 that interfaces with the endless drying wire 61 is the same, thereby facilitating the transfer of the wet film of carbon nanotubes from the endless top wire 41 to the endless drying wire 61. For example, the endless drying wire 61 moves in a clockwise direction and the endless top wire 41 moves in a counter-clockwise direction.

In some embodiments, as shown in fig. 2, the top web transfer system 40 further includes a second blower device 43. The multiple groups of top net vacuumizing assemblies 42 and the second blowing devices 43 are sequentially arranged on one side, far away from the carbon nanotube wet film, of the endless top net 41 along the moving direction of the endless top net 41, and the endless top net 41 is used for driving the carbon nanotube wet film to sequentially pass through the top net vacuumizing assemblies 42 and the second blowing devices 43. The second air blowing device 43 is disposed at a position downstream of the plurality of sets of top net vacuum pumping assemblies 42 and corresponding to the drying system 60, and the second air blowing device 43 is used for blowing the wet carbon nanotube film to assist in transferring the wet carbon nanotube film to the drying system 60 for drying.

Specifically, the second blowing device 43 in the top mesh transfer system 40 is disposed at a position corresponding to the endless drying mesh 61, and the drying vacuum-pumping assembly 62 in the drying system 60 is disposed at a position corresponding to the endless top mesh 41, so that the wet film of carbon nanotubes can be transferred from the endless top mesh 41 to the endless drying mesh 61 under the action of blowing and suction. Preferably, the second blowing devices 43 are at least two groups.

When the wet carbon nanotube film on the endless top net 41 moves to the junction of the endless top net 41 and the endless drying net 61, the wet carbon nanotube film gradually breaks away from the endless top net 41 and is adsorbed to the endless drying net 61 under the air-blowing auxiliary effect of the second air-blowing device 43 in the top net transfer system 40 under the suction effect of the drying and vacuumizing assembly 62, so that the transfer of the wet carbon nanotube film is realized.

Furthermore, in some embodiments, the drying system 60 includes at least two sets of drying and evacuating assemblies 62, a first drying and evacuating assembly and a second drying and evacuating assembly, wherein the first drying and evacuating assembly is disposed at a position corresponding to the second blowing device 43 for adsorbing and moving the wet carbon nanotube film to the endless drying net 61, and the second drying and evacuating assembly is disposed downstream of the first drying and evacuating assembly for further dehydrating the wet carbon nanotube film.

As shown in fig. 2, a plurality of drying devices 63 are sequentially arranged along the moving direction of the endless drying wire 61 for drying the wet film of carbon nanotubes. Preferably, the drying means 63 is a drying cylinder, for example a yankee drying cylinder. In the embodiment of the invention, the drying cylinder is used as the drying device 63, and the wet carbon nanotube film is dried by steam heating, so that the production cost is reduced.

In some embodiments, the number of the drying devices 63 is at least 2, and the plurality of drying devices 63 are respectively disposed on two sides of the endless drying net 61, wherein at least one drying device 63 is disposed on the inner side of the endless drying net 61 for primarily drying the wet carbon nanotube film, and at least one drying device 63 is disposed on the outer side of the endless drying net 61 so as to be in direct contact with the wet carbon nanotube film, thereby improving the drying effect on the wet carbon nanotube film.

Preferably, the drying device 63 is cylindrical, and the endless drying net 61 moves around a part of the outer surface of the drying device 63, so that the wet carbon nanotube film moves past at least half of the outer surface of the drying device 63, improving the drying effect on the wet carbon nanotube film.

In some embodiments, the drying system 60 further includes a pair of dry press rolls 64, where the pair of dry press rolls 64 are disposed on two sides of the endless drying net 61, respectively, and between the plurality of drying devices 63, for rolling the carbon nanotube film to reduce the thickness of the carbon nanotube film. The wet carbon nanotube film is dried and reduced in thickness by passing through a drying device 63, a dry pressing roller 64, and another part of the drying device 63 in this order, to obtain a carbon nanotube film 1, and the carbon nanotube film 1 is wound by a winding device 70.

In some embodiments, the roll gap of the dry press roll 64 is 50-90% of the thickness of the wet carbon nanotube film, and the thickness of the carbon nanotube film can be controlled by controlling the roll gap.

In some embodiments, the endless forming wire 31, the endless top wire 41, and the endless drying wire 61 may be one of a copper wire, a stainless steel wire, and a single/multi-layer polyester wire, and the materials of the endless forming wire 31, the endless top wire 41, and the endless drying wire 61 may be the same or different.

In some embodiments, the endless forming wire 31, the endless top wire 41 and the endless drying wire 61 may be 30-400 mesh, preferably, the endless forming wire 31 is 200-400 mesh, the endless top wire 41 is 100-250 mesh, and the endless drying wire 61 is 30-150 mesh. The mesh number affects the deposition rate of the carbon nanotube slurry and the dehydration speed, and if the mesh number is too small, some of the carbon nanotube slurry is leaked, and if the mesh number is too large, dehydration is difficult.

The continuous production system of the invention adopts the forming net, the top net and the drying net to bear and treat the carbon nano tube films with different dryness, thereby prolonging the service life of each net and reducing the production cost.

The carbon nanotube film of the present invention, and the continuous production method and continuous production system thereof are further described below by way of specific examples.

Example 1

The continuous preparation method of the carbon nanotube film of the embodiment comprises the following steps:

s1, preparing carbon nano tube slurry:

The carbon nano tube slurry comprises, by mass, 50% of carbon nano tubes, 20% of a dispersing agent, 12% of a resin, 12% of a flocculating agent and 6% of a defoaming agent except solvent water. The carbon nanotube is a multi-wall carbon nanotube with the diameter of 7-15nm and the length of 30-50 mu m, the dispersing agent is sodium dodecyl sulfate, the resin adopts aqueous polyurethane emulsion with the resin content of 50%, the addition amount of the emulsion is 2 times that of a flocculating agent, the flocculating agent is aluminum potassium sulfate dodecahydrate, and the defoaming agent is an organosilicon defoaming agent. The concentration of carbon nanotubes in the slurry was 0.4%.

Mixing the carbon nano tube and the dispersing agent in water, grinding and dispersing, and then adding the defoaming agent to obtain the carbon nano tube dispersion liquid. Adding aqueous polyurethane emulsion into the carbon nano tube dispersion liquid, mixing and stirring, adding flocculant, mixing and stirring to obtain carbon nano tube slurry.

S2, preparing the carbon nano tube slurry into a carbon nano tube wet film:

Spreading the carbon nanotube slurry on an endless forming net through a slurry distribution system, and carrying out vacuum suction filtration on the carbon nanotube slurry through an 8-component vacuum suction assembly to form the carbon nanotube wet film, wherein the vacuum degree of the 8-component vacuum suction assembly is-0.04 MPa.

The carbon nanotube wet film was rolled by wet press rolls having a roll spacing of 2mm.

S3, transferring a carbon nano tube wet film:

When the endless forming net drives the carbon nano tube wet film to move to the position where the carbon nano tube wet film is intersected with the endless top net, the carbon nano tube wet film is pumped, blown and vibrated by the first top net vacuumizing assembly, the vibration device and 2 groups of first blowing devices so as to transfer the carbon nano tube film to the endless top net. Wherein the vacuum degree of the first top net vacuumizing component is-0.8 MPa, the blowing pressure of the 2 groups of first blowing devices is 0.1MPa and 0.08MPa in sequence, and the vibration pressure of the vibration device is 0.2MPa.

And after the carbon nanotube film is transferred to the endless top net, continuously removing water by using a second top net vacuumizing assembly, wherein the vacuum degree of the second top net vacuumizing assembly is-0.4 MPa.

When the endless top net drives the carbon nanotube wet film to move to the position where the carbon nanotube wet film is intersected with the endless drying net, the carbon nanotube wet film is sucked through the first drying vacuumizing assembly, and meanwhile, the carbon nanotube wet film is blown through the second blowing device, so that the carbon nanotube wet film is transferred to the endless drying net. Wherein the vacuum degree of the first drying and vacuumizing component is-0.8 MPa, and the pressure of the second blowing device is 0.3MPa.

And after the carbon nanotube film is transferred to the endless drying net, continuously removing water from the carbon nanotube film through a second drying vacuumizing assembly, wherein the vacuum degree of the second drying vacuumizing assembly is-0.4 MPa.

S4, drying the wet carbon nanotube film:

The method comprises the steps of performing primary drying on a carbon nano tube wet film by a first drying device, wherein the drying temperature is 100 ℃, rolling the carbon nano tube wet film by a dry pressing roller, the roller spacing of the dry pressing roller is 0.15mm, drying the carbon nano tube wet film by a second drying device, and rolling the obtained carbon nano tube film.

In the whole continuous production process of the carbon nano tube film, the speed of the endless forming net is controlled to be 3m/min, the speed of the endless top net is controlled to be 3m/min, and the speed of the endless drying net is controlled to be 3.1m/min.

The carbon nanotube film prepared according to the above procedure, as shown in FIG. 4, has a thickness of 180. Mu.m, an areal density of 50g/m ², and a sheet resistance of 1.5. OMEGA/sq.

Example 2

s1, preparing carbon nano tube slurry:

The carbon nano tube slurry comprises 40% of carbon nano tubes, 17% of dispersing agent, 20% of resin, 20% of flocculating agent and 3% of defoaming agent except solvent water by mass percent. The carbon nano tube is the same as that of the embodiment 1, the dispersing agent is sodium dodecyl sulfate, the resin adopts aqueous acrylic emulsion with the resin content of 50 percent, the adding amount of the aqueous acrylic emulsion is the same as that of the carbon nano tube, the flocculating agent is ferrous sulfate, and the defoaming agent is an organosilicon defoaming agent. The concentration of carbon nanotubes in the slurry was 0.1%.

S2, preparing the carbon nano tube slurry into a carbon nano tube wet film:

Spreading the carbon nanotube slurry on an endless forming net through a slurry distribution system, and carrying out vacuum suction filtration on the carbon nanotube slurry through an 8-component vacuum suction assembly to form the carbon nanotube wet film, wherein the vacuum degree of the 8-component vacuum suction assembly is-0.08 MPa.

The carbon nanotube wet film was rolled by a wet press roll having a roll spacing of 3.2mm.

S3, transferring a carbon nano tube wet film:

When the endless forming net drives the carbon nano tube wet film to move to the position where the carbon nano tube wet film is intersected with the endless top net, the carbon nano tube wet film is pumped, blown and vibrated by the first top net vacuumizing assembly, the vibration device and 2 groups of first blowing devices so as to transfer the carbon nano tube film to the endless top net. Wherein the vacuum degree of the first top net vacuumizing component is-0.8 MPa, the blowing pressure of the 2 groups of first blowing devices is 0.2MPa and 0.16MPa in sequence, and the vibration pressure of the vibration device is 0.4MPa.

And after the carbon nanotube film is transferred to the endless top net, continuously removing water by utilizing a second top net vacuumizing assembly, wherein the vacuum degree of the second top net vacuumizing assembly is-0.3 MPa.

When the endless top net drives the carbon nanotube wet film to move to the position where the carbon nanotube wet film is intersected with the endless drying net, the carbon nanotube wet film is sucked through the first drying vacuumizing assembly, and meanwhile, the carbon nanotube wet film is blown through the second blowing device, so that the carbon nanotube wet film is transferred to the endless drying net. Wherein the vacuum degree of the first drying and vacuumizing assembly is-1 MPa, and the pressure of the second blowing device is 0.4MPa.

And after the carbon nanotube film is transferred to the endless drying net, continuously removing water from the carbon nanotube film through a second drying vacuumizing assembly, wherein the vacuum degree of the second drying vacuumizing assembly is-0.8 MPa.

S4, drying the wet carbon nanotube film:

the method comprises the steps of performing primary drying on a carbon nano tube wet film by a first drying device, wherein the drying temperature is 100 ℃, rolling the carbon nano tube wet film by a dry pressing roller, the roller spacing of the dry pressing roller is 2.8mm, drying the carbon nano tube wet film by a second drying device, and rolling the obtained carbon nano tube film.

In the whole continuous production process of the carbon nano tube film, the speed of the endless forming net is controlled to be 0.5m/min, the speed of the endless top net is controlled to be 0.6m/min, and the speed of the endless drying net is controlled to be 0.7m/min.

The carbon nanotube film prepared according to the above steps has a thickness of 230 μm, an areal density of 64g/m ², and a sheet resistance of 0.9 Ω/sq.

Example 3

s1, preparing carbon nano tube slurry:

The carbon nano tube slurry comprises, by mass, 60% of carbon nano tubes, 15% of dispersing agents, 10% of resins, 10% of flocculating agents and 5% of defoaming agents except solvent water. The carbon nano tube is the same as that in the embodiment 1, the dispersing agent is sodium dodecyl sulfate, the resin is aqueous styrene-butadiene emulsion with the resin content of 50 percent, the flocculating agent is aluminum dodecyl chloride, and the defoaming agent is an organosilicon defoaming agent. The concentration of carbon nanotubes in the slurry was 10%.

S2, preparing the carbon nano tube slurry into a carbon nano tube wet film:

The carbon nanotube wet film was rolled by a wet press roll, the roll spacing of which was 0.8mm.

S3, transferring a carbon nano tube wet film:

When the endless forming net drives the carbon nano tube wet film to move to the position where the carbon nano tube wet film is intersected with the endless top net, the carbon nano tube wet film is pumped, blown and vibrated by the first top net vacuumizing assembly, the vibration device and 2 groups of first blowing devices so as to transfer the carbon nano tube film to the endless top net. The vacuum degree of the first top net vacuumizing assembly is-0.2 MPa, the blowing pressure of the 2 groups of first blowing devices is 0.1MPa and 0.09MPa in sequence, and the vibration pressure of the vibration device is 0.2MPa.

And after the carbon nanotube film is transferred to the endless top net, continuously removing water by using a second top net vacuumizing assembly, wherein the vacuum degree of the second top net vacuumizing assembly is-0.1 MPa.

When the endless top net drives the carbon nanotube wet film to move to the position where the carbon nanotube wet film is intersected with the endless drying net, the carbon nanotube wet film is sucked through the first drying vacuumizing assembly, and meanwhile, the carbon nanotube wet film is blown through the second blowing device, so that the carbon nanotube wet film is transferred to the endless drying net. Wherein the vacuum degree of the first drying and vacuumizing assembly is-0.4 MPa, and the pressure of the second blowing device is 0.2MPa.

And after the carbon nanotube film is transferred to the endless drying net, continuously removing water from the carbon nanotube film through a second drying vacuumizing assembly, wherein the vacuum degree of the second drying vacuumizing assembly is-0.2 MPa.

S4, drying the wet carbon nanotube film:

The method comprises the steps of performing primary drying on a carbon nano tube wet film by a first drying device, wherein the drying temperature is 80 ℃, rolling the carbon nano tube wet film by a dry pressing roller, wherein the roller spacing of the dry pressing roller is 0.5mm, performing drying on the carbon nano tube wet film by a second drying device, and performing rolling on the obtained carbon nano tube film.

In the whole continuous production process of the carbon nano tube film, the speed of the endless forming net is controlled to be 10m/min, the speed of the endless top net is controlled to be 11m/min, and the speed of the endless drying net is controlled to be 12m/min.

The carbon nanotube film prepared according to the above steps has a thickness of 50 μm, an areal density of 20g/m ², and a sheet resistance of 6.5 Ω/sq.

Example 4

The difference between this example and example 1 is that the mass percentages of the components in the carbon nanotube slurry, excluding the solvent, are:

45% of carbon nano tube, 20% of dispersing agent, 15% of resin, 15% of flocculating agent and 5% of defoaming agent.

Example 5

The difference between this example and example 1 is that the mass percentages of the resin and the flocculant in the carbon nanotube slurry of this comparative example are 21% and the mass percentages of the carbon nanotubes are 32%.

Example 6

The difference between this example and example 1 is that the mass percentages of the resin and the flocculant in the carbon nanotube slurry of this comparative example are 6% and the mass percentage of the carbon nanotubes is 62%.

Comparative example 1

The present comparative example is different from example 1 in that no resin was added to the carbon nanotube paste of the present comparative example. The carbon nano tube slurry comprises the following components in percentage by mass:

60% of carbon nano tube, 20% of dispersing agent, 14% of flocculating agent and 6% of defoaming agent.

In this comparative example, the retention of the carbon nanotube slurry on the forming wire is reduced due to the absence of the resin, and a small amount of the slurry passes through the forming wire due to the too small particle size during suction filtration.

Comparative example 2

The comparative example is different from example 1 in that no flocculant was added to the carbon nanotube slurry of the comparative example. The carbon nano tube slurry comprises the following components in percentage by mass:

60% of carbon nano tube, 20% of dispersing agent, 14% of resin and 6% of defoaming agent.

In the comparative example, the resin is not demulsified because no flocculant is added, the resin and the carbon nano tube do not form a brooming shape, the retention rate of the sizing agent in a forming net is reduced, and a small amount of sizing agent passes through the forming net during suction filtration.

Comparative example 3

The comparative example differs from example 1 in that the first top web vacuum assembly had a vacuum of-0.1 MPa. In this comparative example, the first top web vacuum assembly was too low in vacuum when transferring the wet carbon nanotube film, and the wet carbon nanotube film was not successfully transferred to the endless top web.

Comparative example 4

The present comparative example is different from example 1 in that the blowing pressure of the first blowing device was 0.3MPa and the pressure of the vibration device was 0.5MPa. The blowing pressure and the vibration device pressure are too large, so that the wet film of the carbon nano tube is locally damaged.

The specific components of the carbon nanotube slurries of the respective examples and comparative examples are shown in table 1.

TABLE 1 content of ingredients (mass%) in carbon nanotube slurry excluding solvent

The properties of the carbon nanotube film of each example, such as thickness, areal density, sheet resistance, etc., are shown in table 2.

TABLE 2 thickness, areal Density and sheet resistance of carbon nanotube films

As can be seen from 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 areal density of the produced carbon nanotube film increases, and the sheet resistance decreases, i.e., the conductivity increases.

According to example 1 and comparative examples 1 to 2, since no resin or flocculant is added in comparative examples 1 and 2, a small amount of slurry passes through the forming wire during suction filtration, so that the thickness and the areal density of the finally produced carbon nanotube film are reduced, waste of the carbon nanotube slurry is caused, and the sheet resistance is increased.

Example 7

The embodiment provides a continuous production system of a carbon nano tube film, the structural schematic diagram of which is shown in fig. 1, and the continuous production system of the carbon nano tube provided by the invention sequentially comprises a grinding pulping system 10, a pulp distribution system, a vacuum forming system 30, a top net transfer system 40, a drying system 60 and a winding device 70.

Wherein, the grinding pulping system 10 is connected with a pulp distribution system, the pulp distribution system consists of a high-level box 21 and an open type pulp flow box 22, the inlet of the high-level box 21 is connected with the grinding pulping system 10 and is positioned above the whole production system, and the outlet is connected with the pulp flow box 22. A first water baffle 223 and a second water baffle 224 are arranged in the head box 22, the distance between the first water baffle 223 and the bottom is 4cm, and the distance between the second water baffle 224 and the bottom is 3mm.

Connected to the headbox 22 is a vacuum forming system 30, the vacuum forming system 30 comprising an endless forming wire 31, an 8-component vacuum suction assembly 32, 2 first blowers 34 and 1 shaker 33. The distance between the 2 first blowing devices was 10cm.

The top web transfer system 40 includes an endless top web 41, a 2-set top web vacuum assembly 42, and 1 second blower 43.

Between the vacuum forming system 30 and the top web transfer system 40, 1 set of wet press rolls 50 were installed, and the roll spacing of the wet press rolls 50 was 2mm.

The drying system 60 comprises an endless drying wire 61, 2 sets of drying vacuum-pumping assemblies 62, 2 drying devices 63 and 1 set of dry press rolls 64, the drying devices 63 being yankee cylinders, the roll spacing of the dry press rolls 64 being 0.15mm.

The endless forming wire 31 is a 300 mesh stainless steel wire, the endless top wire 41 is a 100 mesh polyester wire, and the endless drying wire 61 is a 50 mesh polyester wire.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. A continuous production method of a carbon nanotube film, comprising:

step S1, preparing carbon nano tube slurry, wherein the carbon nano tube slurry comprises carbon nano tubes, a dispersing agent, resin, a flocculating agent, a defoaming agent and water;

Step S2, continuously spreading the carbon nano tube slurry on a circulating endless forming net, and carrying out vacuum suction filtration on the carbon nano tube slurry to continuously form the carbon nano tube slurry to obtain a carbon nano tube wet film;

Step S3, transferring the carbon nano tube wet film to an endless drying net which moves circularly;

2. The method according to claim 1, wherein the carbon nanotube slurry comprises, in mass percent, 40% -60% of carbon nanotubes, 10% -20% of a dispersing agent, 10% -20% of a resin, 10% -20% of a flocculating agent, and 3% -6% of a defoaming agent, in addition to the solvent.

3. The method of claim 2, wherein the resin is a water-soluble resin emulsion, and the resin emulsion comprises at least one of a water-soluble polyurethane emulsion, an acrylic emulsion, and a styrene-butadiene emulsion;

And/or the flocculant comprises at least one of ferrous sulfate, magnesium sulfate, aluminum potassium sulfate dodecahydrate, polyaluminum chloride and ferric trichloride.

4. A method according to any one of claims 1-3, characterized in that in step S3 the wet film of carbon nanotubes is transferred by a top screen transfer system to a endless drying screen which is moved in circulation;

The top net transfer system is arranged between the endless forming net and the endless drying net, and transfers the carbon nano tube wet film from the endless forming net to the endless drying net through suction effect.

5. The method of claim 4, wherein the top web transfer system comprises a cyclically movable endless top web and a first top web evacuation assembly;

In step S3, when the endless forming net drives the carbon nanotube wet film to move to a position where the carbon nanotube wet film interfaces with the endless top net, the carbon nanotube wet film is pumped through the first top net vacuum pumping assembly, and the carbon nanotube wet film is transferred from the endless forming net to the endless top net.

6. The method according to claim 5, wherein a vibration device and two sets of first blowing devices are provided in sequence along the moving direction of the endless forming wire;

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, and the carbon nanotube wet film is assisted to be transferred to the endless top net under the vibration and blowing actions.

7. The method of claim 5, wherein a side of the endless drying wire remote from the wet carbon nanotube film is provided with a first dry vacuum assembly;

in step S3, when the endless top net drives the carbon nanotube wet film to move to a position where the carbon nanotube wet film interfaces with the endless drying net, the carbon nanotube wet film is pumped through the first drying and vacuumizing assembly, so as to transfer the carbon nanotube wet film from the endless top net to the endless drying net.

8. A method according to any one of claims 1-3, characterized in that a pulp distribution system is arranged above the endless forming wire, the outlet of which pulp distribution system is lapped on the endless forming wire;

In step S2, the carbon nanotube slurry is continuously laid on the endless forming net in a circulating manner by a slurry distribution system.

9. A carbon nanotube film, characterized in that it is prepared by the continuous preparation method according to any one of claims 1 to 8, the thickness of the carbon nanotube film is 30 to 500 μm, and the areal density of the carbon nanotube film is 20 to 200 g/m ².

10. A continuous production system of a carbon nanotube film, which is used for realizing the continuous preparation method according to any one of claims 1 to 8, and comprises a grinding pulping system, a pulp distribution system, a vacuum forming system, a top net transfer system, a drying system and a winding device;

The grinding pulping system is used for preparing carbon nano tube slurry;

The slurry distribution system is connected with the grinding and pulping system, is positioned above the vacuum forming system and is connected with the vacuum forming system, and is used for flatly paving the carbon nano tube slurry on the vacuum forming system;

The vacuum forming system is used for filtering the moisture in the carbon nano tube slurry to obtain a carbon nano tube 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 nano tube wet film from the vacuum forming system to the drying system through suction;

the drying system is used for drying the carbon nanotube wet film to obtain a carbon nanotube film;

The winding device is connected with the drying system and is used for winding the dried carbon nanotube film.