A carbon nanotube fiber online crushing device and online crushing method

Abstract

The invention discloses an online crushing device and method for carbon nanotube fibers. An atomizing nozzle sprays a graphene oxide aqueous solution into a collecting device, so that the carbon nanotube aerosol and the graphene oxide water are easily and fully contacted to form composite fibers. A heating component heats the collecting device. The composite fibers inside the collecting device evaporate along with the water in a high temperature and inert atmosphere. The graphene oxide is in situ attached to the carbon nanotube wall or the surface of the tube bundle under the capillary action. The graphene oxide is deoxidized and reduced in the heating zone, releasing a large amount of gas, and the carbon nanotube fibers are crushed into a powder state. Since the nano-sized spatial steric hindrance of graphene oxide can prevent the tube bundles of the carbon nanotube aerosol from aggregating, the van der Waals force between the carbon nanotubes is reduced, which is conducive to crushing. No metal impurities are introduced into the online crushing device and method for carbon nanotube fibers, and the microstructure of the carbon nanotubes is not damaged, thereby ensuring its excellent electrical properties, and the crushing efficiency of the carbon nanotube fibers is high and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of carbon nanotube production, and more specifically to an online pulverizing device and an online pulverizing method for carbon nanotube fibers. Background Art

[0002] Carbon nanotubes (CNTs), as a new type of one-dimensional nanomaterial, are widely used in new energy, transparent display, anti-static, semiconductors, engineering plastics and other fields due to their excellent electrical conductivity, thermal conductivity, temperature resistance, chemical resistance and mechanical properties.

[0003] At present, carbon nanotubes prepared by traditional methods such as floating catalytic method and arc method mostly exist in the form of continuous assemblies of carbon nanotubes (carbon nanotube fibers), and the disordered carbon nanotube fibers exist in the form of films, blocks, flocs, ropes, etc., making the dispersion of carbon nanotube fibers difficult. Usually, the carbon nanotube fibers need to be crushed to ensure the consistency of subsequent dispersion.

[0004] The main method for crushing carbon nanowire fibers is mechanical crushing, including blade crushing, air flow crushing and hammer crushing. Due to the characteristics of high toughness, low specific gravity, and high specific surface area, the fibers are easy to agglomerate, adhere and entangle during the crushing process, resulting in inadequate crushing or even damage to the crusher. Patent CN113611438A, on the basis of traditional mechanical crushing, first soaks the carbon nanotube fibers with a wetting liquid to obtain a weight-added structure, and then crushes them using a fiber crusher. This solves the problem of fiber adhesion to a certain extent, but at the same time, the density of the fibers after impregnation increases, and the fiber strength is greatly enhanced, which has side effects on the crushing process.

[0005] Therefore, it is urgent to develop an efficient and low-cost carbon nanotube fiber crushing device and method to facilitate the dispersion and subsequent application of carbon nanotubes. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an online carbon nanotube fiber crushing device. By using the online crushing device to crush the carbon nanotube fibers online, it is possible to avoid using mechanical blades to crush the carbon nanotube fibers and will not cause metal pollution to the product. In addition, this method does not require the carbon nanotube fibers to be collected and then subjected to secondary crushing treatment, thereby avoiding problems such as reduced crushing efficiency caused by secondary dissolution, and also avoiding problems such as high energy consumption and poor crushing effect caused by mechanical crushing, thereby greatly reducing production costs and being suitable for large-scale industrial production.

[0007] The technical solution of the present invention is to provide a carbon nanotube fiber online crushing device with the following structure, including a carbon nanotube synthesis device and a collecting device; the carbon nanotube synthesis device is provided with a carbon nanotube aerosol outlet, the collecting device is provided with an inlet, and the carbon nanotube aerosol outlet is connected to the inlet of the collecting device; an atomizing nozzle is provided at one end of the collecting device close to the carbon nanotube aerosol outlet, and the atomizing nozzle is used to spray graphene oxide aqueous solution into the collecting device; an exhaust structure is provided on the collecting device; and a heating component is provided outside the collecting device.

[0008] After adopting the above structure, the carbon nanotube fiber online crushing device of the present invention has the following advantages compared with the prior art:

[0009] When the carbon nanotube fiber online crushing device of the present invention is working, the atomizing nozzle sprays the graphene oxide aqueous solution into the collecting device, so that the carbon nanotube aerosol and the graphene oxide aqueous solution are fully contacted to form a composite fiber, and the heating component heats the collecting device to a high temperature. The composite fiber inside the collecting device evaporates with water in a high temperature and inert atmosphere, and the graphene oxide is attached to the carbon nanotube tube wall or the tube bundle surface in situ under the capillary action, and the graphene oxide is deoxidized and reduced in the collecting device. Due to the steric hindrance of the nanometer size of graphene oxide, the tube bundle of the carbon nanotube aerosol can be prevented from aggregating, and the van der Waals force between the carbon nanotubes is reduced, which is conducive to crushing. In addition, under the conditions of high temperature and inert atmosphere, the graphene oxide is reduced and a large amount of gas is released. Under the microscopic pressure of the gas, the carbon nanotube fiber is broken to form a carbon nanotube powder. The method does not introduce metal impurities, and the microscopic structure of the carbon nanotube is not damaged, thereby ensuring its excellent electrical properties. Through this device, the crushing of carbon nanotube fibers is efficient, low cost and good effect.

[0010] Preferably, the exhaust structure includes a first exhaust pipe and a second exhaust pipe, the first exhaust pipe and the second exhaust pipe are respectively arranged at the two ends of the collecting device, and the inner cavity of the first exhaust pipe and the inner cavity of the second exhaust pipe are both connected to the inner cavity of the collecting device. With this structure, the generated carbon nanotube aerosol and the graphene oxide aqueous solution sprayed from the top can be convected through the first exhaust pipe and the second exhaust pipe, and the contact is more complete; at the same time, the waste gas and water vapor in the collecting device can also be discharged.

[0011] Preferably, a first microporous partition is provided at one end of the collecting device, and the atomizing nozzle is mounted on the first microporous partition; a second microporous partition is provided at the other end of the collecting device. With this structure, microporous partitions are provided at both ends of the collecting device to prevent the product from being discharged outdoors along with the waste gas.

[0012] Further preferably, the diameters of the micropores on the first microporous partition plate and the second microporous partition plate are both 1-1000 um. After adopting this structure, the effect is better.

[0013] Further preferably, the first microporous partition plate and the second microporous partition plate are made of microporous ceramics or sand core filter plates or microporous titanium plates or foamed copper or foamed nickel.

[0014] Further preferably, a filter screen is provided in the other end of the collecting device and located on the upper side of the second microporous partition plate. With this structure, the filter screen is used to filter the cooling water, so that the carbon nanotube fibers remain on the filter screen for easy collection.

[0015] Preferably, the heating assembly includes a heater and a heat preservation layer, the heater is mounted on the outer wall of the collecting device, and the heat preservation layer is wrapped around the collecting device and the heater. With this structure, the heat preservation layer can keep the temperature low and also keep the outer wall temperature of the heating assembly below 50°C to avoid scalding the staff.

[0016] Further preferably, the side wall of the heater close to the collecting device is made of ceramic, stainless steel, graphite or silicon carbide. With this structure, the heater has a better heat conduction effect, so that the heating effect is better.

[0017] Further preferably, the heating body of the heater is resistive heating or induction heating.

[0018] Preferably, a plurality of the atomizing nozzles form the atomizing nozzle group, and one end of the collecting device is provided with one or more groups of the atomizing nozzle groups. With this structure, the spraying effect is better and the coverage area is wider.

[0019] Further preferably, the spray angle of the atomizing nozzle is 30° to 120°. After adopting this structure, the spray angle and spray height make the spray coverage area larger.

[0020] Preferably, the spray direction of the atomizing nozzle (3) is perpendicular to the outlet direction of the carbon nanotube aerosol, and the spray direction is vertically downward. With this structure, the sprayed graphene oxide aqueous solution and the carbon nanotube aerosol are mixed better.

[0021] Preferably, the spraying method of the atomizing nozzle is liquid pressurization, gas assistance or ultrasonic atomization. After adopting this structure, the spraying effect is better.

[0022] More preferably, the spraying method of the atomizing nozzle is gas-assisted, and the gas used is an inert gas, which can be argon, nitrogen, helium, etc.

[0023] Preferably, a first observation window and a second observation window are respectively provided at both ends of the side wall of the collecting device, wherein the first observation window is used to observe the atomization condition in the collecting device, and the second observation window is used to observe the product condition in the collecting device. With this structure, the atomization condition in the collecting device can be observed through the first observation window, and the product condition generated in the collecting device can be observed through the second observation window, which helps the staff understand the working condition of the device.

[0024] Another technical problem to be solved by the present invention is to provide an online crushing method for carbon nanotube fibers. This crushing method can avoid the use of mechanical blades to crush the carbon nanotube fibers, and will not cause metal pollution to the product. In addition, this method does not need to collect the carbon nanotube fibers for secondary crushing, thereby avoiding the problem that after the graphene oxide is collected into the water tank along with the carbon nanotube aerosol, the secondary dissolution causes the crushing efficiency to decrease, and also avoids the problems of high energy consumption and poor crushing effect of mechanical crushing, thereby greatly reducing the production cost and being suitable for large-scale industrial production.

[0025] The technical solution of the present invention is to provide a method for online pulverization of carbon nanotube fibers having the following steps:

[0026] S1, synthesizing carbon nanotubes by catalytic reaction in a carbon nanotube synthesis device, and transporting the carbon nanotubes to a collection device in the form of aerosol;

[0027] S2, supplying the graphene oxide aqueous solution to the atomizing nozzle on the collecting device, and spraying the graphene oxide aqueous solution into the collecting device by the atomizing nozzle, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture;

[0028] S3, heating the heating component outside the collecting device to 500-1000° C.;

[0029] S4, opening the first exhaust pipe and the second exhaust pipe respectively provided at both ends of the collecting device to adjust the pressure in the collecting device to negative pressure;

[0030] S5. Collecting the carbon nanotube and graphene powder products in the collecting device.

[0031] After adopting the above steps, the carbon nanotube fiber online crushing method of the present invention has the following advantages compared with the prior art:

[0032] The principle of the carbon nanotube fiber online crushing method of the present invention is: in the process of carbon nanotube synthesis, graphene oxide spray is used to replace traditional water mist precipitation, and graphene oxide is fully contacted with carbon nanotube aerosol to form composite fibers. As water evaporates in a high temperature and inert atmosphere, graphene oxide is in situ attached to the carbon nanotube wall or tube bundle surface under capillary action. Graphene oxide is deoxidized and reduced in a high temperature environment, releasing a large amount of gas, and the carbon nanotube fiber is crushed into a powder state. The advantages of using this method are:

[0033] (1) The technical solution of this application is the first to use graphene oxide to crush carbon nanotube fibers online. The graphene oxide microsheets are in situ adsorbed on the tube wall / tube bundle surface of the carbon nanotubes in the carbon nanotube aerosol state. The nano-sized steric hindrance can prevent the tube bundles of the carbon nanotube aerosol from aggregating, and the van der Waals force between the carbon nanotubes is reduced, which is conducive to crushing.

[0034] (2) Under high temperature and inert atmosphere conditions, graphene oxide is reduced and releases a large amount of gas. Under the microscopic pressure of the gas, the carbon nanotube fibers are broken to form carbon nanotube powder. This method does not introduce metal impurities and the microstructure of the carbon nanotubes is not destroyed, thus ensuring their excellent electrical properties.

[0035] Preferably, in step S2, the graphene oxide aqueous solution is 0.02-0.1 mg / ml, the graphene oxide sheet diameter is 10-500 nm, the C / O ratio is 1:1, and the graphene oxide aqueous solution is supplied to the atomizing nozzle at a flow rate of 2-5 kg / h. With this structure, the atomizing spraying effect of the graphene oxide aqueous solution is better.

[0036] Preferably, in step S1, carbon nanotubes are synthesized in a carbon nanotube synthesis device by a floating catalytic cracking method or an arc method catalytic reaction, and the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or oligo-walled carbon nanotubes.

[0037] Preferably, in step S2, the graphene oxide solution is prepared by Brodie method, Staudenmaier method or Hummers method, and the C / O ratio of the graphene oxide solution is 1:0.8-1.5. After adopting this structure, the surface of the graphene oxide has more hydrophilic functional groups such as carboxyl, hydroxyl, carbonyl, amino, thiol, etc., which can form hydrogen bond interactions with water molecules, thereby enhancing the dispersibility of the graphene oxide aqueous solution.

[0038] Further preferably, the graphene oxide solution is centrifuged or filtered to obtain a small-diameter graphene oxide aqueous solution, the diameter of which is 10 to 500 nm; and the concentration of the graphene oxide aqueous solution is 0.01 to 0.15 mg / mL.

[0039] Further preferably, the spray flow rate of the graphene oxide aqueous solution is 1-10 kg / h; the output of the carbon nanotube aerosol is 0.1-5 kg / h. With this structure, the mixing effect of the graphene oxide aqueous solution and the carbon nanotube aerosol is better.

[0040] Preferably, the particle size of the pulverized carbon nanotube and graphene powder products is 20-200 meshes, and the moisture content of the carbon nanotube and graphene powders is 1%-20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of the carbon nanotube fiber online crushing device of the present invention.

[0042] Figure 2 It is a schematic diagram of the distribution structure of the atomizing nozzle of the carbon nanotube fiber online pulverizing device of the present invention on the first microporous partition plate.

[0043] Figure 3 It is a schematic diagram of the principle of the online pulverization method of carbon nanotube fibers of the present invention.

[0044] Figure 4 This is a photo of the product after carbon nanotube / graphene is crushed in a preferred embodiment of the present invention.

[0045] Figure 5 This is a photo of a carbon nanotube fiber product in a comparative embodiment of the present invention.

[0046] As shown in the figure: 1. carbon nanotube synthesis device, 2. collection device, 3. atomizing nozzle, 4. first exhaust pipe, 5. second exhaust pipe, 6. first microporous partition, 7. second microporous partition, 8. heater, 9. insulation layer, 10. first observation window, 11. second observation window, 12. filter. DETAILED DESCRIPTION

[0047] In order to better understand the present application, a more detailed description of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and do not limit the scope of the present application in any way. Throughout the specification, the same figure numerals refer to the same elements.

[0048] In the drawings, the thickness, size and shape of objects have been slightly exaggerated for ease of explanation. The drawings are only examples and are not drawn strictly to scale.

[0049] It should also be understood that the terms “comprises,” “including,” “has,” and “contains,” when used in this specification, indicate the presence of the described features, integers, steps, operations, elements, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or combinations thereof.

[0050] like Figure 1 to Figure 2 As shown, the present application discloses an online carbon nanotube fiber crushing device, including a carbon nanotube synthesis device 1 and a collection device 2.

[0051] The carbon nanotube synthesis device 1 is used to synthesize carbon nanotubes. The synthesis method includes floating catalytic cracking method or arc method, but is not limited thereto; the synthesized carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, and oligo-walled carbon nanotubes. The carbon nanotube synthesis device 1 contains an inert gas. In the carbon nanotube synthesis device 1, carbon nanotubes as dispersed substances and inert gas dispersion medium form carbon nanotube aerosols, which have colloidal properties, are light in gas, and have characteristics such as Brownian motion, and do not settle due to gravity. The carbon nanotube synthesis device 1 is provided with a carbon nanotube aerosol outlet, and the collection device 2 is provided with an inlet. The carbon nanotube aerosol outlet is connected to the inlet provided in the collection device 2.

[0052] The collecting device 2 is provided with an atomizing nozzle 3 and a first exhaust pipe 4 at one end close to the carbon nanotube aerosol outlet. The atomizing nozzle 3 is used to spray the graphene oxide aqueous solution into the collecting device 2. A first microporous partition 6 is provided in one end of the collecting device 2. The atomizing nozzle 3 is installed on the first microporous partition 6, that is, the lower end of the atomizing nozzle 3 is connected to the first microporous partition 6, and the upper end of the atomizing nozzle 3 is exposed outside the upper end of the collecting device 2 for connecting with the graphene oxide aqueous solution supply device. The atomizing nozzle 3 can be one group or multiple groups. In this specific embodiment, the atomizing nozzle 3 is provided with 6 groups. The spraying method of the atomizing nozzle 3 can be one of liquid pressurization, gas-assisted and ultrasonic atomization, preferably ultrasonic atomization. If the gas-assisted spraying method is selected, the gas should use an inert gas, such as argon, nitrogen, helium, etc., but not limited thereto. The spray particle size of the atomized graphene oxide aqueous solution is less than 50um; the spray particle size is related to the contact probability and penetration rate of the graphene oxide aqueous solution and the carbon nanotube aerosol. The spray angle is 30° to 120°; the spray angle and spray height affect the spray coverage area. The spray direction of the atomizing nozzle 3 is perpendicular to the outlet direction of the carbon nanotube aerosol.

[0053] The function of the first exhaust pipe 4 is to form convection between the generated aerosol and the graphene oxide spray sprayed from the top, so that the contact is more complete, and the waste gas and water vapor in the collection system are discharged. The function of the first microporous partition 6 is to prevent the product from being discharged outdoors with the waste gas. The pore size of the micropores of the first microporous partition 6 is 1 to 1000 um. The first microporous partition 6 is made of microporous ceramics or sand core filter plates or microporous titanium plates or foamed copper or foamed nickel, but is not limited thereto.

[0054] The other end of the collecting device 2 is provided with a second exhaust pipe 5, and the other end of the collecting device 2 is provided with a second microporous partition 7. The structure and function of the second microporous partition 7 are the same as those of the first microporous partition 7. The second exhaust pipe 5 is located at the lower side of the second microporous partition. The exhaust port of the second exhaust pipe 5 is connected to the exhaust gas treatment device. The other end of the collecting device 2 is provided with a filter screen 12, and the filter screen 12 is provided on the upper side of the second microporous partition 7.

[0055] The collecting device 2 is provided with a heating component outside, and the heating component is arranged at the middle and lower end of the collecting device. The heating component includes a heater 8 and a thermal insulation layer 9, and the heater 8 is installed on the outer wall of the collecting device 2. The thermal insulation layer 9 is wrapped outside the collecting device 2 and the heater 8. The heating component is arranged at the middle and lower end of the collecting device 2, and its main purpose is to gasify the water in the carbon nanotube and graphene oxide spray, and use the large amount of gas formed in the reduction process of graphene oxide to break the carbon nanotube fiber into carbon nanotube and graphene composite powder. The heating body of the heating device is resistive heating or induction heating, but not limited to this; the material of the inner wall of the heating device is ceramic, stainless steel, graphite, silicon carbide and other materials, but not limited to this; the set temperature of the heating device is 500~1000℃. The thermal insulation layer 9 has the function of thermal insulation and heat insulation, ensuring that the outer wall temperature of the heating device is lower than 50℃.

[0056] The two ends of the side wall of the collecting device 2 are respectively provided with a first observation window 10 and a second observation window 11; the first observation window 10 is located between the second microporous partition 7 and the heating assembly, and the first observation window 10 is used to observe the atomization condition in the collecting device 2. The second observation window 11 is located between the second microporous partition and the heating assembly, and the second observation window 11 is used to observe the product condition in the collecting device 2.

[0057] like Figure 3 As shown, the present application also discloses a method for online crushing of carbon nanotube fibers, and the device used is the online crushing of carbon nanotube fibers with the above structure, and the specific embodiments are as follows: Example

[0058] This specific embodiment discloses a method for online pulverization of carbon nanotube fibers, comprising the following steps:

[0059] S1. Synthesize carbon nanotubes by catalytic reaction in the carbon nanotube synthesis device 1, and transport the carbon nanotubes in the form of aerosol to the collection device 2. The output of carbon nanotubes is 500 g / h.

[0060] S2, supplying 0.1 mg / ml graphene oxide aqueous solution (graphene oxide sheet diameter 300-500 nm, C / O ratio 1:1) to the atomizing nozzle 3 on the collecting device 2 at a flow rate of 2 kg / h, the atomizing nozzle 3 sprays the graphene oxide aqueous solution into the collecting device 2, and the graphene aqueous solution is sprayed on the surface of the carbon nanotube aerosol in the form of spray atomization, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; the atomizing nozzle 3 has a spray angle of 60° and an atomized particle size of 10-50 um;

[0061] S3. The heating component outside the collecting device 2 is heated to 800°C.

[0062] S4, open the first exhaust pipe 4 and the second exhaust pipe 5 respectively arranged at the two ends of the collecting device 2, and adjust the pressure in the collecting device 2 to a slight negative pressure.

[0063] S5, collecting the carbon nanotube and graphene powder products in the collecting device 2.

[0064] The collection method used in this specific embodiment is a water mist spray collection method. This method refers to the use of the principle of water mist settling. The water mist in the collection device will form a water film, and the water film will collect the carbon nanotubes on the surface of the water mist, and then after washing and filtering through a filter, it will form a carbon nanotube fiber. In the collection stage, the carbon source, etc., undergoes cracking, melting, precipitation, etc. to form a product in the high temperature area, which is a process from the aerosol state discharged from the outlet to the fiber state.

[0065] The detection revealed that the particle size of the carbon nanotube and graphite powder in this embodiment is 100-150 mesh, the ratio of carbon nanotube to graphene is 100:20, and the water content in the powder is 7%. Example

[0066] This specific embodiment discloses a method for online pulverization of carbon nanotube fibers, comprising the following steps:

[0067] S1. Synthesize carbon nanotubes by catalytic reaction in the carbon nanotube synthesis device 1, and transport the carbon nanotubes in the form of aerosol to the collection device 2. The output of carbon nanotubes is 1 kg / h.

[0068] S2, supplying 0.08 mg / ml of graphene oxide aqueous solution (graphene oxide sheet diameter 50-100 nm, C / O ratio 1:1) to the atomizing nozzle 3 on the collecting device 2 at a flow rate of 3 kg / h, and the atomizing nozzle 3 sprays the graphene oxide aqueous solution into the collecting device 2, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; the spray angle of the atomizing nozzle 3 is 120°, and the atomized particle size is 10-50 um;

[0069] S3. The heating component outside the collecting device 2 is heated to 1000°C.

[0070] S4, open the first exhaust pipe 4 and the second exhaust pipe 5 respectively arranged at the two ends of the collecting device 2, and adjust the pressure in the collecting device 2 to a slight negative pressure.

[0071] S5, collecting the carbon nanotube and graphene powder products in the collecting device 2.

[0072] The detection revealed that the particle size of the carbon nanotube and graphite powder in this embodiment is 80-120 mesh, the ratio of carbon nanotube to graphene is 100:12, and the water content in the powder is 12%. Example

[0073] This specific embodiment discloses a method for online pulverization of carbon nanotube fibers, comprising the following steps:

[0074] S1. Synthesize carbon nanotubes by catalytic reaction in the carbon nanotube synthesis device 1, and transport the carbon nanotubes in the form of aerosol to the collection device 2. The output of carbon nanotubes is 500 g / h.

[0075] S2, supplying 0.02 mg / ml of graphene oxide aqueous solution (graphene oxide sheet diameter 10-50 nm, C / O ratio 1:1) to the atomizing nozzle 3 on the collecting device 2 at a flow rate of 5 kg / h, the atomizing nozzle 3 sprays the graphene oxide aqueous solution into the collecting device 2, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; the spray angle of the atomizing nozzle 3 is 90°, and the atomized particle size is 10-50 um;

[0076] S3. The heating component outside the collecting device 2 is heated to 500°C.

[0077] S4, open the first exhaust pipe 4 and the second exhaust pipe 5 respectively arranged at the two ends of the collecting device 2, and adjust the pressure in the collecting device 2 to a slight negative pressure.

[0078] S5, collecting the carbon nanotube and graphene powder products in the collecting device 2.

[0079] The detection revealed that the particle size of the carbon nanotube and graphite powder in this embodiment is 40-80 mesh, the ratio of carbon nanotube to graphene is 100:10, and the water content in the powder is 18%. Example

[0080] This specific embodiment discloses a method for online pulverization of carbon nanotube fibers, comprising the following steps:

[0081] S1. Synthesize carbon nanotubes by catalytic reaction in the carbon nanotube synthesis device 1, and transport the carbon nanotubes in the form of aerosol to the collection device 2. The output of carbon nanotubes is 500 g / h.

[0082] S2, supplying 0.1 mg / ml graphene oxide aqueous solution (graphene oxide sheet diameter 100-220 nm, C / O ratio 1:1.5) to the atomizing nozzle 3 on the collecting device 2 at a flow rate of 2 kg / h, the atomizing nozzle 3 sprays the graphene oxide aqueous solution into the collecting device 2, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; the spray angle of the atomizing nozzle 3 is 60°, and the atomized particle size is 10-50 um;

[0083] S3. The heating component outside the collecting device 2 is heated to 800°C.

[0084] S4, open the first exhaust pipe 4 and the second exhaust pipe 5 respectively arranged at the two ends of the collecting device 2, and adjust the pressure in the collecting device 2 to a slight negative pressure.

[0085] S5, collecting the carbon nanotube and graphene powder products in the collecting device 2.

[0086] The detection revealed that the particle size of the carbon nanotube and graphite powder in this embodiment is 80-120 mesh, the ratio of carbon nanotube to graphene is 100:16, and the water content in the powder is 8%. Example

[0087] This specific embodiment discloses a method for online pulverization of carbon nanotube fibers, comprising the following steps:

[0088] S1. Synthesize carbon nanotubes by catalytic reaction in the carbon nanotube synthesis device 1, and transport the carbon nanotubes in the form of aerosol to the collection device 2. The output of carbon nanotubes is 500 g / h.

[0089] S2, supplying 0.1 mg / ml graphene oxide aqueous solution (graphene oxide sheet diameter 100-220 nm, C / O ratio 1:0.8) to the atomizing nozzle 3 on the collecting device 2 at a flow rate of 2 kg / h, the atomizing nozzle 3 sprays the graphene oxide aqueous solution into the collecting device 2, so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; the spray angle of the atomizing nozzle 3 is 60°, and the atomized particle size is 10-50 um;

[0090] S3. The heating component outside the collecting device 2 is heated to 800°C.

[0091] S4, open the first exhaust pipe 4 and the second exhaust pipe 5 respectively arranged at the two ends of the collecting device 2, and adjust the pressure in the collecting device 2 to a slight negative pressure.

[0092] S5, collecting the carbon nanotube and graphene powder products in the collecting device 2.

[0093] The detection revealed that the particle size of the carbon nanotube and graphite powder in this embodiment is 150-200 mesh, the ratio of carbon nanotube to graphene is 100:22, and the water content in the powder is 10%.

[0094] For comparison, the following comparative example is provided:

[0095] Comparative Example 1

[0096] The same as Example 1, except that pure water is used instead of the graphene oxide aqueous solution.

[0097] Result: The product was fibrous.

[0098] Comparative Example 2

[0099] The same as Example 1, except that a graphene oxide quantum dot aqueous solution is used (the flake diameter of the graphene oxide quantum dots is 1-5 nm, and the C / O ratio is 1:1).

[0100] Result: The product was a mixture of fibers and powder.

[0101] Comparative Example 3

[0102] The same as Example 1, except that a graphene oxide aqueous solution is used (the diameter of the graphene oxide flakes is 1-10 um, and the C / O ratio is 1:1).

[0103] Result: The product was a mixture of fibers and powder.

[0104] Comparative Example 4

[0105] The same as the embodiment 1, the difference is that the atomized droplet diameter of the atomizing nozzle 3 is 50-100 um.

[0106] Results: The particle size of the carbon nanotube / graphite powder in this comparative example is relatively coarse, ranging from 10 to 20 meshes, and the particle size is uneven.

[0107] Comparative Example 5

[0108] The same as Example 1, except that the spray angle is 30°.

[0109] Result: The product was a mixture of fibers and powder.

[0110] Comparative Example 6

[0111] The same as Example 1, except that the heating temperature is 300°C.

[0112] Results: The particle size of the carbon nanotube / graphite powder in this comparative example is relatively coarse, ranging from 10 to 20 meshes, and the particle size is uneven, with a moisture content of 42%.

[0113] Result analysis: It can be seen from the results of Examples 1 to 5 that the graphene oxide aqueous solution and its spray form can both perform online crushing of the synthesized carbon nanotube fibers within the ratio range set in the present application. It can be seen from Examples 1 to 3 that the sheet diameter of graphene oxide has a significant effect on the particle size of the dispersed composite powder. When the sheet diameter of graphene is reduced from 500nm to 10nm, the particle size of the composite powder after crushing is reduced from 120 mesh to 40 mesh. This is because the carbon nanotube aerosol quickly shrinks into carbon nanotube fibers after contacting the graphene oxide aqueous solution, and the bonding force between the tube walls is large. As the size of graphene oxide decreases, the oxygen-containing groups in the sheet are relatively reduced, and the gas generated by high-temperature deoxidation is less, resulting in a decrease in crushing force; it can be seen from Comparative Example 2 that when an aqueous solution of graphene oxide quantum dots is used, the crushing effect decreases sharply; and when the size of graphene oxide is too large (Example 3), its large-size structure is difficult to infiltrate the carbon nanotube aerosol, resulting in the separation of carbon nanotube fibers and graphene oxide, and the crushing effect is not good; compared with Example 1, the C / O atomic ratio of graphene oxide in Examples 4 and 5 is different. Under high temperature conditions, graphene oxide sheets with a high O atomic ratio have a better crushing effect on carbon nanotube fibers.

[0114] From Comparative Example 1, it can be seen that after replacing the graphene oxide aqueous solution with pure water, the product formed is a fibrous structure; from Comparative Examples 4 and 5, it can be seen that the spray angle and the particle size distribution of the spray also have a significant impact on the crushing effect. If the spray angle is too small or the spray particle size is too large, the carbon nanotube aerosol will not contact the spray sufficiently, resulting in uneven breakage, and some products will still exist in a fibrous state. From Example 6, it can be seen that the heating temperature is too low, the graphene oxide is not fully reduced, the crushing effect is poor, and the water cannot be fully volatilized, and the moisture content of the product is too high.

[0115] In summary, the online pulverization method of carbon nanotube fibers in the present application has the following advantages:

[0116] 1. In the product collection stage of carbon nanotube synthesis, a certain size of graphene oxide aqueous solution spray is used to replace the traditional pure water spray. In the carbon nanotube aerosol state, the carbon nanotube wall microscopically adsorbs the graphene oxide sheet. By controlling the particle size and spray amount of the spray, the carbon nanotube aerosol is precipitated to form carbon nanotubes and graphene oxide spray;

[0117] The carbon nanotubes and graphene oxide spray enter the collecting device, wherein a heating device is arranged at the lower end, and annealing is carried out in an inert atmosphere. A large amount of gas is released during the annealing of the graphene oxide, and the formed carbon nanotube macro-fiber structure is destroyed to form a carbon nanotube and graphene composite powder. The composite powder enters the tail end of the collecting device for collection, and the exhaust gas is discharged from the second exhaust pipe.

[0118] The present application is the first to utilize the gas released during the reduction process of graphene oxide microsheets to break up carbon nanotube fibers. The breaking principle is as follows: 1) the graphene oxide microsheets are in situ adsorbed on the tube wall or tube bundle surface of the carbon nanotubes in the carbon nanotube aerosol state, and their nano-sized spatial steric hindrance can prevent the tube bundles of the carbon nanotube aerosol from aggregating; 2) under high temperature and inert atmosphere conditions, the graphene oxide is reduced and releases a large amount of gas. Under the action of the microscopic pressure of the gas, the carbon nanotube fibers are broken to form carbon nanotube powder. This method does not introduce metal impurities, and the microscopic structure of the carbon nanotubes is not damaged, thereby ensuring its excellent electrical properties.

[0119] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the principles and spirit of the present application are included in the protection scope of the present application.

Claims

1. A carbon nanotube fiber online crushing device, characterized in that: The invention comprises a carbon nanotube synthesis device (1) and a collection device (2); the carbon nanotube synthesis device (1) is provided with a carbon nanotube aerosol outlet, the collection device (2) is provided with an inlet, and the carbon nanotube aerosol outlet is connected to the inlet of the collection device (2); an atomizing nozzle (3) is provided at one end of the collection device (2) close to the carbon nanotube aerosol outlet, and the atomizing nozzle (3) is used to spray a graphene oxide aqueous solution into the collection device (2); an exhaust structure is provided on the collection device (2), a heating component is provided outside the collection device (2), and the collection device (2) is filled with an inert gas; The heating assembly comprises a heater (8) and a heat-insulating layer (9); the heater (8) is mounted on the outer wall of the collecting device (2); and the heat-insulating layer (9) is wrapped around the collecting device (2) and the heater (8); and the spray angle of the atomizing nozzle (3) is greater than 30° and less than or equal to 120°.

2. The carbon nanotube fiber online crushing device according to claim 1, characterized in that: The exhaust structure comprises a first exhaust pipe (4) and a second exhaust pipe (5), wherein the first exhaust pipe (4) and the second exhaust pipe (5) are respectively arranged at two ends of the collecting device (2), and the inner cavity of the first exhaust pipe (4) and the inner cavity of the second exhaust pipe (5) are both connected to the inner cavity of the collecting device (2).

3. The carbon nanotube fiber online crushing device according to claim 1, characterized in that: A first microporous partition (6) is provided at one end of the collecting device (2), and the atomizing nozzle (3) is mounted on the first microporous partition (6); a second microporous partition (7) is provided at the other end of the collecting device (2).

4. The carbon nanotube fiber online pulverizing device according to claim 3, characterized in that: The pore diameters of the micropores on the first microporous partition plate (6) and the second microporous partition plate (7) are both 1 to 1000 um.

5. The carbon nanotube fiber online crushing device according to claim 3, characterized in that: The first microporous partition plate (6) and the second microporous partition plate (7) are made of microporous ceramics or sand core filter plates or microporous titanium plates or foamed copper or foamed nickel.

6. The carbon nanotube fiber online pulverizing device according to claim 3, characterized in that: A filter screen is provided in the other end of the collecting device and located on the upper side of the second microporous partition.

7. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: The side wall of the heater (8) close to the collecting device (2) is made of ceramic, stainless steel, graphite or silicon carbide.

8. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: The heating element of the heater (8) is resistive heating or induction heating.

9. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: The plurality of atomizing nozzles (3) form the atomizing nozzle group, and one end of the collecting device (2) is provided with one or more groups of the atomizing nozzle groups.

10. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: The spray direction of the atomizing nozzle (3) is perpendicular to the outlet direction of the carbon nanotube aerosol, and the spray direction is vertically downward.

11. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: The spraying method of the atomizing nozzle (3) is a liquid pressurization method, a gas-assisted method, or an ultrasonic atomization method.

12. The carbon nanotube fiber online pulverizing device according to claim 11, characterized in that: The spraying method of the atomizing nozzle (3) is a gas-assisted method, and the gas used is an inert gas.

13. The carbon nanotube fiber online pulverizing device according to claim 1, characterized in that: A first observation window (10) and a second observation window (11) are respectively provided at both ends of the side wall of the collecting device (2); the first observation window (10) is used to observe the atomization condition in the collecting device (2), and the second observation window (11) is used to observe the product condition in the collecting device (2).

14. A method for online pulverization of carbon nanotube fibers, characterized in that: The carbon nanotube fibers are crushed using a carbon nanotube fiber online crushing device, the carbon nanotube fiber online crushing device comprising a carbon nanotube synthesis device (1) and a collecting device (2); the carbon nanotube synthesis device (1) is provided with a carbon nanotube aerosol outlet, the collecting device (2) is provided with an inlet, the carbon nanotube aerosol outlet is connected to the inlet of the collecting device (2); an atomizing nozzle (3) is provided at one end of the collecting device (2) close to the carbon nanotube aerosol outlet, the atomizing nozzle (3) is used to spray a graphene oxide aqueous solution into the collecting device (2); an exhaust structure is provided on the collecting device (2), a heating component is provided outside the collecting device (2), and the collecting device (2) is filled with an inert gas; The carbon nanotube fiber online pulverization method comprises the following steps: S1, synthesizing carbon nanotubes by catalytic reaction in a carbon nanotube synthesis device (1), and transporting the carbon nanotubes in the form of aerosol to a collection device (2); S2, supplying the graphene oxide aqueous solution to the atomizing nozzle (3) on the collecting device (2), and spraying the graphene oxide aqueous solution into the collecting device (2), so that the graphene oxide aqueous solution and the carbon nanotube aerosol form a mixture; S3, heating the heating component outside the collecting device (2) to 500-1000°C; S4, opening the first exhaust pipe (4) and the second exhaust pipe (5) respectively provided at the two ends of the collecting device (2), and adjusting the pressure in the collecting device (2) to a negative pressure; S5. Collecting the carbon nanotube and graphene powder products in the collecting device (2).

15. The method for online pulverizing carbon nanotube fibers according to claim 14, characterized in that: In step S2, the graphene oxide aqueous solution is 0.02-0.1 mg / ml, the graphene oxide flake diameter is 10-500 nm, the C / O ratio is 1:1, and the graphene oxide aqueous solution is supplied to the atomizing nozzle (3) at a flow rate of 2-5 kg / h.

16. The method for online pulverizing carbon nanotube fibers according to claim 14, characterized in that: In step S1, carbon nanotubes are synthesized in a carbon nanotube synthesis device (1) by a floating catalytic cracking method or an arc method catalytic reaction, wherein the carbon nanotubes are single-walled carbon nanotubes, double-walled carbon nanotubes, or oligo-walled carbon nanotubes.

17. The method for online pulverizing carbon nanotube fibers according to claim 14, characterized in that: In step S2, the graphene oxide solution is prepared by a Brodie method, a Staudenmaier method or a Hummers method, and the C / O ratio of the graphene oxide solution is 1:0.8-1.

5.

18. The method for online pulverizing of carbon nanotube fibers according to claim 17, characterized in that: The graphene oxide solution is centrifuged or filtered to obtain a small-diameter graphene oxide aqueous solution, the diameter of which is 10-500 nm; the concentration of the graphene oxide aqueous solution is 0.01-0.15 mg / mL.

19. The method for online pulverizing carbon nanotube fibers according to claim 17, characterized in that: The spray flow rate of the graphene oxide aqueous solution is 1-10 kg / h; the output of the carbon nanotube aerosol is 0.1-5 kg / h.

20. The method for online pulverizing carbon nanotube fibers according to claim 14, characterized in that: The particle size of the crushed carbon nanotube and graphene powder products is 20-200 meshes, and the moisture content of the carbon nanotube and graphene powder is 1%-20%.

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