Continuous carbon nanotube ribbons from chemical vapor deposition systems

Abstract

The invention provides a carbon nanotube ribbon, a system for continuously producing the carbon nanotube ribbon and a method for producing the carbon nanotube ribbon by applying the system.

Description

[0001] Cross-referencing of related patents

[0002] This application claims priority to U.S. Patent Application No. 63 / 528,498, filed July 24, 2023, which is incorporated herein by reference. Technical Field

[0003] This invention relates generally to carbon nanotube strips, and more specifically to systems and methods for the continuous production of carbon nanotube strips using chemical vapor deposition systems and strip forming systems. Background Technology

[0004] Current methods for producing carbon nanotubes are labor-intensive and costly. Typically, this method includes: 1) preparing initial carbon nanotube sheets 4 feet wide by 8 feet long in a chemical vapor deposition system; 2) collecting the initial carbon nanotube sheets and testing them to determine their suitability for use as carbon nanotube tapes; 3) post-processing the initial carbon nanotube sheets using a condensation chemistry method; 4) cutting the post-processed sheets into 4-inch wide by 8-foot long pieces; 5) joining the 4-inch wide by 8-foot long pieces together using a hot melt adhesive bonding process; 6) winding the joined sheets into 4-inch wide by 1000-2000-meter long reels; 7) running the reels through a cutting operation to obtain the desired bandwidth, such as 5 / 16 inch to 1 inch; 8) optionally joining the reels together to produce longer finished width reels of 3000-4000 meters; and 9) detecting the tape strength, width, thickness, and seam thickness of each finished roll by continuously running the tape reels through tension-sensing rollers, digital non-contact width sensors, and digital or manual thickness measurement equipment. The finished product is then prepared on a roll for transport.

[0005] Ideally, a new method should be provided for the continuous production of carbon nanotube strips that is more efficient and less costly than current methods. This invention provides such a method that eliminates several of the aforementioned steps while still producing carbon nanotube strips with the desired width and length suitable for the aerospace, commercial wire and cable industries. Summary of the Invention

[0006] The present invention generally provides a system for the continuous production of carbon nanotube strips, the system comprising: (a) a chemical vapor deposition system operable for forming carbon nanotube material; and (b) a strip forming system comprising: (i) a housing having an inlet coupled to an outlet of the chemical vapor deposition system, (ii) an air knife assembly located near the inlet and operable for receiving carbon nanotube material, and (iii) a vacuum transport system operable for extracting carbon nanotube material from the air knife assembly and forming carbon nanotube strips. Attached Figure Description

[0007] Figure 1 A schematic diagram of a system for the continuous production of carbon nanotube strips according to an embodiment of the present invention is described, the system typically including a chemical vapor deposition system coupled to a strip forming system;

[0008] Figure 2A This is a schematic diagram of a floating catalyst chemical vapor deposition system for producing carbon nanotube materials that can be used to form carbon nanotube bands according to an embodiment of the present invention;

[0009] Figure 2B It is used for Figure 2A A schematic description of the injector device of the system shown.

[0010] Figure 2C A schematic diagram of a floating catalyst chemical vapor deposition system for producing carbon nanotube materials using a plasma generator, related to an embodiment of the present invention, is described;

[0011] Figure 2D Described applicable Figure 2C A schematic diagram of the system's plasma generator;

[0012] Figure 3 A schematic side view of a belt forming system according to one embodiment of the present invention is described;

[0013] Figure 4 for Figure 3 The front view of the belt forming the system;

[0014] Figure 5 yes Figure 3 A perspective view of a tape-forming system that receives a carbon nanotube sheath produced in a chemical vapor deposition system;

[0015] Figure 6A This is a perspective view of a vacuum conveying system according to one embodiment of the present invention;

[0016] Figure 6B It is a perspective view of a platform combined with the transmission and guiding mechanisms of a vacuum conveying system;

[0017] Figure 6C It is a top view of a platform that is in fluid communication with the vacuum source of the vacuum delivery system;

[0018] Figure 6D This is a top view of a portion of the conveyor belt located on a platform of a vacuum conveying system;

[0019] Figure 6E It is a perspective view of a continuous conveyor belt in a vacuum conveyor system;

[0020] Figure 6F This is a perspective view of the transmission mechanism of the vacuum conveying system;

[0021] Figure 6G This is a perspective view of the guiding mechanism of the vacuum conveying system;

[0022] Figure 7A (In situ) and 7B (non-in situ) are respectively Figure 3 A front view of the belt forming system's collection system and the finished belt product; and

[0023] Figure 8 Is with Figure 3 A perspective view of the airlocks coupled to the system. Detailed Implementation

[0024] This invention generally relates to carbon nanotube strips and systems and methods for the continuous production of carbon nanotube strips. (Reference) Figure 1 In one embodiment, carbon nanotube strips are produced by a method typically comprising the following steps: First, carbon nanotube material is produced in a chemical vapor deposition system 1000. Then, the carbon nanotube material is introduced into a strip forming system 1100, which is configured to operate to form carbon nanotube strips. The strip forming system 1100 is coupled to the chemical vapor deposition system 1000, particularly to a synthesis chamber 1001 of the chemical vapor deposition system 1000. The synthesis chamber 1001 typically includes an inlet end 1001a to which reactive gases are supplied, a hot zone 1002 to which elongated carbon nanotubes are synthesized, and an outlet end 1001b from which reaction products (i.e., elongated carbon nanotubes (i.e., carbon nanotube material)) and waste gases exit. In some embodiments, the synthesis chamber 1001 may include a quartz tube 1003 extending through the hot zone 1002. Although in Figure 1 The general description is provided, but it should be understood that other configuration options can be used in the design of synthesis chamber 1001.

[0025] In some embodiments, the belt forming system 1100 includes a housing 1105. For example... Figure 1 As shown, the housing 1105 can maintain substantial airtightness to minimize the release of potentially harmful aerosol particles from the synthesis chamber 1001 into the environment and to prevent oxygen from entering the system 1100 and reaching the synthesis chamber 1001. In particular, the presence of oxygen within the synthesis chamber 1001 may affect the integrity of the carbon nanotubes and impair their production.

[0026] The housing 1105 of the band-forming system 1100 also includes an inlet 1105a for substantially hermetically airtight connection to the outlet end 1001b of the synthesis chamber 1001. In some embodiments, as the carbon nanotubes exit the synthesis chamber 1001, the nanotubes entangle, bundle, and otherwise coalesce to form an extended network of interconnected and branching bundles, forming a hollow carbon nanotube sheath 1200 (i.e., the carbon nanotube material is a carbon nanotube sheath) shaped like a wind vane bag billowing in a breeze. An air knife assembly 1300 located near the inlet 1105a is operable to guide and control the width of the carbon nanotube sheath 1200 exiting the synthesis chamber 1001. The carbon nanotube sheath 1200 is extracted onto a continuous transport surface of a vacuum transport system 1400 located below the air knife assembly 1300. The extracted sheath 1200 forms a film or band 1250 on the continuous transport surface (see...). Figure 7B ), and is conveyed to a collection system located within housing 1105, such as receiving a reel to wind it into a roll, or conveyed from housing 1105 to environmental conditions (e.g., Figure 8 As shown), it is used to roll up on a receiving reel or to transport to other equipment for further processing.

[0027] A surprising advantage of the system and method of this invention is that the width of the carbon nanotube sheath leaving the synthesis chamber can be controlled via the air knife assembly, and the sheath does not adhere to the elements of the tape-forming system. While the width of the carbon nanotube sheath can be controlled by operating the air knife assembly, the carbon nanotube sheath leaving the chemical vapor deposition system is filled with hydrogen and must be degassed. The air knife assembly works in conjunction with a vacuum delivery system to extract the width-controlled carbon nanotube sheath onto a continuous conveyor belt to produce carbon nanotube tapes. The width and thickness of the carbon nanotube tapes can be controlled by: the production rate of the carbon nanotube material in the chemical vapor deposition system; the operation of the air knife assembly; the speed of the conveyor belt; and the rate at which the carbon nanotube sheath is vacuum-extracted from the air knife assembly. In some embodiments, the production rate of the carbon nanotube material can be about 5-50 g / h, the conveyor belt speed can be about 10-100 ft / min, and the vacuum extraction rate of the carbon nanotube sheath can be about 20-60 Hz. The width of the carbon nanotube tapes produced according to this invention can be about 5 / 16-3 inches (e.g., ...). Figure 7A and 7B (As shown, it has substantially straight edges). In other embodiments, the density of carbon nanotube strips produced according to the method of the present invention can be about 1-10 g / m. 2 .

[0028] As discussed above, the carbon nanotube strips of the present invention are formed from carbon nanotube materials. According to one embodiment, the carbon nanotube material comprises entangled carbon nanotubes having the following specific characteristics: (i) a diameter of about 10-100 nm, or about 12-90 nm, or about 15-80 nm, or about 17-60 nm, or about 20-50 nm, or about 25-30 nm; (ii) a length of about 0.1-10 mm, or about 0.2-9 mm, or about 0.3-8 mm, or about 0.44-7 mm, or about 5-6 mm; and (iii) a density of about 0.3-1.9 g / cm³. 3 Or approximately 0.35-1.8 g / cm³ 3 Or approximately 0.5-1.7 g / cm³ 3 or approximately 0.1-1 g / cm³ 3 Or approximately 0.3-1.1 g / cm³ 3 (iv) An aspect ratio of at least about 250,000, or at least about 350,000, or at least about 500,000, or at least about 600,000; (v) A fracture strain of about 1.8-7%, or about 2-6.5%, or about 3-5%; and (vi) A surface area of ​​about 100-300 m². 2 / g, or approximately 125-275 m 2 / g, or approximately 150-250 m 2 / g, or approximately 175-225 m 2 / g. In other embodiments, in addition to the features described above, the entangled carbon nanotubes may also have the following characteristics: a tensile strength of about 0.2-3.2 GPa, or about 0.3-3 GPa, or about 0.3-2.8 GPa, and / or a specific strength of about 1800-2900 kN. M / kg, or approximately 2000-2700 kN M / kg, or approximately 2200-2600 kN M / kg.

[0029] Currently, there are various methods and variations thereof that can be used to form nanotubes in this invention. These methods include: (1) chemical vapor deposition, a commonly used method that can be carried out under near-normal or high pressure conditions and at temperatures above about 400°C; (2) electric arc discharge, a high-temperature method that can generate highly perfect nanotubes; and (3) laser ablation.

[0030] As discussed above, suitable carbon nanotubes can be grown using chemical vapor deposition (CVD) or similar gas-phase pyrolysis processes known in the industry. The growth temperature for CVD can be in a relatively low range, for example, approximately 400–1350 °C. In some embodiments, carbon nanotubes, including single-walled carbon nanotubes (SWNTs) or multi-walled carbon nanotubes (MWNTs), can be grown by exposing nanoscale catalyst particles to a carbon-containing reactive gas (i.e., a gaseous carbon source). Specifically, nanoscale catalyst particles can be introduced into the carbon-containing reactive gas by adding existing particles or by in-situ synthesis of particles from organometallic precursors or even non-metallic catalysts. While both SWNTs and MWNTs can be grown, SWNTs may be chosen in certain situations due to their relatively high growth rate and the potential to form rope-like structures, which offer advantages in terms of handling, thermal conductivity, electronic properties, and strength.

[0031] The carbon nanotubes used in this invention can be described as unmodified, pristine, unpurified, or purified. The terms "unmodified" and / or "pristine" and / or "unpurified" describe carbon nanotubes that have not been treated or have undergone only minimal treatment since chemical synthesis. These types of carbon nanotubes are primarily, but not limited to, materials obtained directly by synthetic methods. The term "purified" carbon nanotubes are primarily defined as carbon nanotubes that have undergone chemical and / or thermal and / or physical treatments to improve their properties. Examples of such treatments include, but are not limited to, acid treatment to remove catalysts or amorphous carbon and thermal annealing to eliminate amorphous carbon and / or reduce the number of carbon defect sites. Additionally, carbon nanotubes can be subjected to media milling to break up carbon nanotube aggregates, thereby promoting the dispersion and processing of carbon nanotubes. Various methods and means of purifying carbon nanotubes are well known to those skilled in the art and described in the literature, and materials prepared by these techniques can be used in this invention.

[0032] It should be noted that although carbon-synthesized nanotubes are mentioned throughout this application, other compounds, such as boron nitride, MoS2, or combinations thereof, can also be used in the synthesis of nanotubes according to the present invention.

[0033] In one embodiment, the present invention employs a floating catalyst chemical vapor deposition (“CVD”) system and method to produce carbon nanotubes. Because the growth temperature of the floating catalyst CVD method can be relatively low, for example about 400-1400°C, carbon nanotubes, including single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), or both, can be generated. While both SWNTs and MWNTs can be grown, SWNTs are preferred in certain situations due to their higher growth rate and the potential to form rope-like structures, which can provide advantages in terms of operability, safety, and strength.

[0034] Figure 2AOne embodiment of the invention is provided, which describes a substantially horizontal CVD system 20 capable of producing carbon nanotubes. The CVD system 20 includes a housing 21 (i.e., a furnace) having opposing ends 211 and 212 and a channel 213 extending between the ends 211 and 212. A tube 22 (i.e., a reactor) may be located within the channel 213 of the housing 21, having a proximal end and a distal end, within which elongated, untangled carbon nanotube filaments can be generated. The tube 22 is filled with a preheated dense-phase gas, such as, but not limited to, argon, sulfur hexafluoride (SF6), carbon monoxide, or mixtures thereof. These dense phase gases are preheated to a temperature of at least about 100°C, or at least about 200°C, or at least about 300°C, or at least about 400°C, or at least about 500°C, or at least about 600°C, or at least about 700°C, or at least about 800°C, or at least about 900°C, or at least about 1000°C, so that their density is higher than the density of the inlet CVD gas (i.e., the fluid mixture) injected from end 222 (or the lower end of tube 22). The concentration of the dense phase gas in tube 22 may be at least about 10 mol%, or at least about 20 mol%, or at least about 30 mol%, or at least about 40 mol%, or at least about 50 mol%, or at least about 60 mol%, or at least about 70 mol%, or at least about 80 mol%, or at least about 90 mol%, or at least about 99.9 mol%. When the feed fluid mixture is injected, the heat of the preheated dense phase gas in pipe 22 is transferred to the incoming light fluid mixture feedstock through conduction / convection and radiation from the wall of pipe 22.

[0035] The ends 221 and 222 of tube 22 can be positioned such that they extend from the ends 211 and 212 of housing 21, respectively. Housing 21 may include heating elements or other mechanisms (such as a tank furnace) to generate a temperature of approximately 1000-1500°C, which is necessary for the growth of carbon nanotubes within tube 22. Since the heating elements or other mechanisms must maintain the temperature environment within tube 22 within a specified range during the synthesis of elongated, untangled carbon nanotube filaments, although not shown, system 20 may include thermocouples on the exterior of tube 22 to monitor the temperature environment within tube 22. The maintenance of the temperature range (e.g., approximately 1100-1400°C) within tube 22 can be optimized by applying thermal insulation structure 223. Figure 2C The insulation structure 223 shown can be made of, for example, zirconia ceramic fibers (such as zirconia-stabilized boron nitride). Other insulation materials can also be used.

[0036] Because the housing 21 and tube 22 must withstand changes in temperature and gas reactivity, they can be made of a robust, essentially corrosion-resistant, and essentially airtight material. The housing 21 and tube 22 can be made of quartz or ceramic materials such as Macor® machinable glass-ceramics to provide enhanced shock absorption. Of course, other materials can also be used, as long as the housing 21 and tube 22 maintain their airtightness and corrosion resistance. Furthermore, although illustrated as cylindrical, the housing 21 and tube 22 can have cross-sections of any geometry.

[0037] The CVD system 20 is coupled at its distal end to a tape-forming system 23. The tape-forming system 23 is in fluid communication with end 221 of the tube 22, enabling it to receive carbon nanotube material generated within the tube 22. At the opposite end 222 of the tube 22, the CVD system 20 may include an ejector device 24 (i.e., an atomizer) in fluid communication with the tube 22. The ejector 24 may be designed to receive a fluid mixture from a reservoir 25 containing the components necessary for growing nanotube filaments within the tube 22. The ejector 24 may also be designed to vaporize or fluidize the mixture (i.e., generate microdroplets) before guiding the mixture into the tube 22 for the generation and growth of carbon nanotubes. In some embodiments, multiple filaments may be produced by an array of ejectors (not shown), such as a spinneret similar to those commonly used in gel spinning.

[0038] In one embodiment, the fluid mixture entering at end 222 may include, but is not limited to: (a) a metal catalyst precursor from which metal catalyst particles can be generated for subsequent growth of nanotubes thereon; (b) a modulator compound for controlling the particle size distribution of the metal catalyst particles generated from the metal catalyst precursor, thereby modulating the diameter of the nanotubes; and (c) a carbon source for depositing carbon atoms on the metal catalyst particles to grow elongated, untangled nanotubes.

[0039] Examples of metal catalyst precursors from which metal catalyst particles can be generated include ferrocene materials (such as iron or iron alloys), nickel, cobalt, their oxides or alloys (or compounds with other metals or ceramics). Additionally, metal catalyst particles can also be made from metal oxides, such as Fe3O4, Fe2O4, or FeO, similar oxides of cobalt or nickel, or combinations thereof.

[0040] Examples of conditioning compounds that can be used in the fluid mixtures of the present invention include thiophene, H2S, other sulfur-containing compounds, or combinations thereof.

[0041] Examples of carbon sources that can be used in the fluid mixtures of this invention include, but are not limited to, ethanol, methyl formate, propanol, acetic acid, hexane, methanol, or mixtures of methanol and ethanol. Other liquid carbon sources, including C2H2, CH3, and CH4, may also be used.

[0042] The following is for reference. Figure 2B The ejector 24 is described in detail. The ejector 24 includes a generally tubular chamber 241 that defines a channel 242 along which a vaporized fluid mixture can be generated and introduced into the reactor tube 22. To vaporize or fluidize the mixture, the ejector 24 may include an atomizing tube 26, designed to achieve a Venturi effect, thereby generating small droplets from the fluid mixture drawn from the reservoir 25. It should be understood that the vaporization or fluidization of the fluid mixture primarily occurs as the fluid exits through the distal end 261 of the atomizing tube 26. The size of the generated droplets can range from nanometers to micrometers. To guide the vaporized fluid mixture along the atomizing tube 26 into the reactor tube 22, a volume of gas such as H2, He, or any other inert gas can be applied to propel or drive the vaporized fluid into the reactor tube 22.

[0043] Although the illustration is based on a tubular shape, it should be understood that the injector 24 can be designed in any geometry, as long as the injector can accommodate the atomizing tube 26 and provide a path for introducing the gasified fluid mixture into the reactor tube 22.

[0044] Additionally, it should be noted that injector 24 may be designed to allow the individual components of the fluid mixture to be introduced into injector 24 individually, rather than being provided as part of the mixed fluid. In this embodiment, each component may be individually vaporized through an atomizing tube similar to tube 26 and introduced into injector 24, where they are allowed to mix and subsequently guided along injector 24 in a similar manner as described above.

[0045] Since the ejector 24 is located within part of the reactor tube 22 and furnace 21, the heat generated within the tube 22 and furnace 21 may negatively affect the temperature environment within the ejector 24. To insulate the ejector 24 from the heat within the reactor tube 22 and furnace 21, a heat insulation package 27 can be provided around the ejector 24. Specifically, the heat insulation package 27 is used to maintain the temperature environment along the length of the ejector 24.

[0046] With the presence of the heat insulation pack 27, the temperature environment within the injector 24 can be lower than the range of reactions necessary to affect the growth of carbon nanotubes. For this purpose, the injector 24 may also include a heating zone A located downstream of the atomizing tube 26, thereby providing a temperature range sufficient for the formation of metal catalyst particles from the metal catalyst precursor. The heating zone A may include a first heater 28 located downstream of the distal end 261 of the atomizing tube 26. The heater 28 can be provided to maintain a temperature range, for example, that is necessary for the decomposition of the metal catalyst precursor for its constituent atoms. p1 At this point, the constituent atoms can then aggregate into metal catalyst particles, and nanostructures can subsequently be grown on these metal catalyst particles. To maintain T p1The temperature range at which the metal catalyst precursor is decomposed is at the level required, and in one embodiment, it can be at T p1 Heater 28 is located slightly downstream. In the embodiment using ferrocene as a precursor, when T p1 When the temperature can be maintained at about 200-300℃, it can produce constituent atoms (i.e., iron particles) with a size of basically nanometers.

[0047] Heating zone A may also include a second heater 29 located downstream of the first heater 28 and within the furnace 21. The heater 29 may be provided to maintain a temperature range, for example, at the Tc required for the decomposition of the regulator compound to its constituent atoms. p2 In the presence of metal catalyst particle clusters, these atoms can interact with the clusters to control the particle size distribution of the metal catalyst particles and thus the diameter of the resulting nanostructures. In embodiments where thiophene is used as a modifier compound, sulfur can be released during thiophene decomposition and interact with the metal catalyst particle clusters. In one embodiment, heater 29 can be designed to maintain a temperature of T. p2 The temperature range is approximately 700-950°C, and this range is maintained slightly downstream of heater 29.

[0048] According to an implementation plan, T p2 It can be located at a distance of T p1 At the required distance. Since multiple parameters may be at play, T p1 To T p2 The distance between them should be such that the metal catalyst precursor decomposes at T. p1 To T p2 The flow of the fluid mixture can optimize the amount of decomposition of the regulator compound, thereby optimizing the particle size distribution of the metal catalyst particles.

[0049] It should be understood that, in addition to the specific temperature range generated within the injector 24 by the first heater 28 and the second heater 29, the temperature at the distal end 261 of the atomizing tube 26 also needs to be maintained within a specific range in the injector 24 to prevent condensation or uneven flow of the vaporized fluid mixture as it exits through the distal end 261 of the atomizing tube 26. In one embodiment, the temperature at the distal end 261 may need to be maintained at approximately 100-250°C. For example, if the temperature is below the range shown, condensation of the fluid mixture may occur along the wall of the injector 26. Accordingly, the fluid mixture guided from the injector 26 into the reaction tube 22 may differ significantly from the mixture drawn from the reservoir 25. For example, if the temperature is above the range shown, boiling of the fluid mixture may occur at the distal end 261, resulting in fluid splashing and uneven flow upon entering the injector 24.

[0050] Since the injector 24 may need to maintain a temperature gradient along its length, whether to reduce condensation at the distal end 261 of the atomizing tube 26 or to achieve a temperature gradient at T... p1 Maintaining the temperature necessary for the decomposition of the metal catalyst precursor, or at T p2 The insulation pack 27 maintains the temperature necessary for the decomposition of the regulator compound. In addition to shielding the reactor tube 22 and furnace 21 from heat, it also maintains the required temperature gradient at various key locations along the injector 24.

[0051] In one embodiment, the insulation pack 27 may be made of quartz or a similar material, or of a porous ceramic material, such as zirconia ceramic fibers (e.g., zirconia-stabilized boron nitride). Other insulation materials may also be used.

[0052] Continue to refer to Figure 2B System 20 may include at least one inlet 291 through which a carrier gas can be introduced into reactor tube 22. Introducing a carrier gas into tube 22 can assist the fluid mixture in flowing along tube 22 after exiting ejector 24. Additionally, since it may be desirable to reduce turbulence or eddies associated with the fluid mixture exiting ejector 24, the carrier gas can be allowed to flow along the outer surface of reactor tube 22 and ejector 24. In one embodiment, the carrier gas can be allowed to flow at a velocity substantially similar to that of the fluid mixture exiting ejector 24, thereby maintaining a substantially laminar flow of the fluid mixture. By maintaining a substantially laminar flow, the growth and strength of the resulting nanotubes can be optimized. In one embodiment, the carrier gas can be H2, He, or any other inert gas.

[0053] To further reduce turbulence or eddies as the fluid mixture exits the ejector 24, the insulation package 27 may have a basic conical design near the distal end of the ejector 24. Alternatively or additionally, an extension (not shown) may be provided near the distal end of the ejector 24, thereby extending the flow of the fluid mixture significantly away from the center of the ejector 24 radially as it exits the distal end. The presence of this extension reduces the flow velocity of the fluid mixture and allows the flow to remain essentially laminar.

[0054] It should be understood that ejector 24 can be designed so that when the fluid mixture moves along ejector 24, at T p1 Decomposition of metal catalyst precursors and in T p2 The decomposition regulator compound is present. However, the carbon source required for nanostructure growth is not decomposed and its chemical properties remain essentially unchanged as the fluid mixture moves along the injector 24.

[0055] However, as shown in Figure 2-2A, since the distal end of the injector 24 extends into the interior of the furnace 21, it is close to a significantly higher temperature range inside the furnace 21 and therefore close to the reactor tube 22. This allows the carbon source to be immediately exposed to the temperature range required for its decomposition as it leaves the distal end of the injector 24, for subsequent nanotube growth. In one embodiment, the temperature at the interface 242 between the distal end of the injector and the furnace 21 can be approximately 1000-1250°C.

[0056] refer to Figure 2C A plasma generator 230 can be positioned near the distal end of the ejector 24. In this way, the fluid mixture passes through the plasma flame 232 of the plasma generator 230 before entering the reactor tube 22. In one embodiment, seals or fluid seals can be provided near the connection between the plasma generator 230 and the ejector 24, and near the connection between the plasma generator 230 and the reactor tube 22, to prevent gas and particles in the fluid mixture from escaping from the system 20. In one embodiment, the plasma generator 230 can be axially or linearly aligned with the tubular chamber 241 of the ejector 24 to provide an efficient flow path for the fluid mixture from the ejector 24 through the plasma generator 230. In one embodiment, the plasma generator 230 is aligned with the ejector 24 such that the fluid mixture passes substantially through the central region of the plasma generator 230. In some embodiments, this may result in the fluid mixture passing through the central region of the plasma flame 232, where the temperature distribution may be more uniform than in the outer region of the plasma flame 230. The plasma generator 230 can also be axially or linearly aligned with the reactor tube 22.

[0057] In one embodiment, plasma generator 230 provides concentrated energy in the form of a plasma flame 232, raising the temperature of the fluid mixture to a level above the temperature range of ejector 24. In one embodiment, plasma generator 230 can raise the temperature of the fluid mixture to a level sufficient to decompose the carbon source to its constituent atoms to activate nanostructure growth. In one embodiment, plasma generator 230 can operate at approximately 1200-1700°C. Since the temperature of the plasma flame 232 is much higher than the temperature inside ejector 24, the heat generated by the plasma flame 232 may negatively affect the temperature environment inside ejector 24. Therefore, a heat shield 260 can be provided between the region of plasma generator 230 that generates the plasma flame 232 and ejector 24 to maintain the temperature environment along the length of ejector 24. In one embodiment, heat shield 260 can be made of a porous ceramic material such as zirconia ceramic fibers (e.g., zirconia-stabilized boron nitride). Of course, other heat-insulating materials can also be used.

[0058] Because the plasma generator 230 can provide concentrated energy to the fluid mixture, it triggers faster decomposition of the carbon source. In one embodiment, a shorter reactor tube 22, furnace 21, or both can be used, but still produce nanotubes of sufficient length. Of course, the length of the reactor tube 22, furnace 21, or both can be configured to be similar to or longer than in a system without a plasma generator, as needed. In one embodiment, the application of the plasma generator 230 in the method can enable the production of longer carbon nanotubes.

[0059] It should also be noted that in some embodiments, the ejector 24 and plasma generator 230 can be used with minimal or no additional heat in the reaction tube 22. It should also be noted that multiple plasma generators can be used in system 20 to create the desired temperature gradient over the travel distance of the fluid mixture.

[0060] Figure 2D One embodiment of a plasma generator 230 is described. In one embodiment, the plasma generator 230 may be a direct current (DC) generator. The plasma generator 230 may include an anode 252 and a cathode 254, both of which may be cooled by conducting heat from the electrodes 252, 254 via water or other cooling fluids or other materials that can act as heat sinks. In one embodiment, the electrodes 252, 254 may be highly diffusive metal electrodes, such as those typically made of copper or silver. A plasma gas may flow around the anode 252 and cathode 254 and may be ionized by an electric arc 256 induced between the anode 252 and cathode 254 to form a plasma flame 232. Suitable plasma gases may be reactive or non-reactive and may include, but are not limited to, argon, oxygen, nitrogen, helium, hydrogen, or other gases. In one embodiment, the plasma generator 230 may include one or more Helmholtz coils 258 or other devices that generate a magnetic field for rotating the electric arc 256. In this embodiment, the anode 252 and cathode 254 may be provided in a ring shape, thereby facilitating the rotation of the electric arc 256. Although Figure 2D A suitable implementation scheme for a plasma generator is described, but other designs and types of plasma generators (such as radio frequency, alternating current and other discharge plasma generators) can also be used.

[0061] In one embodiment, a Helmholtz coil 258 can be used to generate an electromagnetic or electrostatic field for in-situ alignment of nanotubes downstream of a plasma generator 230 within the reactor chamber 22. Alternatively or additionally, the electromagnetic field generated by the plasma generator 230 can be used to deflect the carbon nanotubes toward the axial direction of the reaction tube 22 by generating torque on the carbon nanotubes, thereby stacking the carbon nanotubes in that axial direction. In one embodiment, the plasma generator 230 can also be designed to push or aggregate the carbon nanotube cloud into a smaller radial volume as the cloud travels through the reaction tube 22. In one embodiment, the particles on which the carbon nanotubes are grown can be charged by a particle charging device, enabling the particles to respond to electrostatic forces.

[0062] When multiple plasma generators 230 are used, the field strength and position of the plasma generators can be optimized to align the carbon nanotubes. Alternatively or additionally, the generators can be linearly aligned with each other, and each downstream subsequent plasma generator can be configured to generate a stronger electrostatic field, thereby forcing or condensing the carbon nanotube cloud into a smaller radial volume while moving the carbon nanotubes in a manner substantially axially aligned with the reaction tube 22. In some embodiments, subsequent plasma generators can also be applied to control the acceleration or deceleration of the flow, causing the nanotubes to radially condense into a filamentary structure. This method of condensing the carbon nanotube flow forces the carbon nanotubes to be packed more closely, thereby enhancing the contact between adjacent nanotubes. The contact between adjacent carbon nanotubes can be further enhanced by non-covalent interactions between the carbon nanotubes (such as London dispersion forces or van der Waals forces).

[0063] During operation, multiple processes may occur in the region between the atomizing tube 26 of system 20 and the main furnace 21. For example, initially, a fluid mixture of a metal catalyst precursor, a modifier compound, and a carbon source may be introduced from the storage tank 25 into the injector 24 through the atomizing tube 26. An inert gas such as H2 or He may be applied to assist in guiding the fluid mixture along the atomizing tube 26. As the fluid mixture moves along and exits the atomizing tube 26, the tube 26 can induce a Venturi effect, causing the mixture to vaporize (i.e., droplets are generated from the liquid mixture). To reduce any condensation or boiling that occurs as the fluid mixture exits the atomizing tube 26, this region within the injector 24 may be maintained in a temperature range of approximately 100-250°C.

[0064] In one embodiment, an additive for a carbon source may be included in the fluid mixture to optimize growth conditions and enhance the strength of the carbon nanotube material prepared from the resulting carbon nanotubes. Examples of additives include, but are not limited to, C. 60 C 70 C 72 C 84 and C 100 .

[0065] The vaporized fluid mixture can then travel along the injector 24 to the first heater 28, where the temperature can be maintained at T. p1 Maintaining a temperature of approximately 200-300°C, the metal catalyst precursor within the fluid mixture can decompose, releasing its constituent atoms. In one embodiment, the decomposition temperature of the metal catalyst precursor may depend on the carrier gas (e.g., ...). (Or He), or possibly depending on the presence of other substances. Subsequently, the constituent atoms can aggregate into metal catalyst particles with a characteristic particle size distribution. This particle size distribution of the metal catalyst particles is usually formed gradually during their migration into the furnace 21 via the injector 24.

[0066] Subsequently, the fluid mixture continues downward along the injector 24 to the second heater 29. In one embodiment, the second heater 29 can be located at T p2 The temperature is maintained at approximately 700-950°C, where the regulator compound decomposes into its constituent atoms. These constituent atoms then react with the metal catalyst particle clusters to achieve a specific particle size distribution. Specifically, the constituent atoms of the regulator compound can inhibit the growth of the metal catalyst particles and / or suppress their evaporation. In one embodiment, both the constituent atoms of the regulator compound and H2 in the injector 24 can interact with the metal catalyst particle clusters to influence their particle size distribution.

[0067] It should be understood that as the fluid mixture travels along the entire length of the ejector 24, the carbon source within the fluid mixture can maintain its chemical properties or not decompose within the ejector 24.

[0068] Once the regulated metal catalyst particles have moved past the second heater 29, they can cross the interface 242 between the distal end 241 of the injector 24 and the furnace 21, and enter the main body of the reactor tube 12 filled with preheated dense phase gas. After leaving the injector 24, the regulated metal catalyst particles and the carbon source are in a carrier gas such as... It can maintain a basically laminar flow state in the presence of He. In the presence of a carrier gas, the regulated metal catalyst particles may be diluted by the volume of the carrier gas.

[0069] Furthermore, when entering the main body of reactor tube 22, the temperature range within reactor tube 22 can be maintained at a level sufficient to decompose the carbon source into its constituent carbon atoms, and the presence of carbon atoms can activate the growth of nanotubes. In one embodiment, the temperature can be approximately 1000-1250°C. Typically, the growth process occurs when carbon atoms themselves are substantially ordered attached to the metal catalyst particles to form nanotubes (such as carbon nanotubes).

[0070] In one embodiment, the fluid mixture from ejector 24 may pass through plasma generator 230 before entering reactor tube 22.

[0071] As described above, when heat enters the main body of reactor tube 22, it is transferred from the dense phase gas to the light fluid mixture via conduction / convection and radiation from the wall of reactor tube 22, thereby generating elongated, untangled nanotubes. Furthermore, the flow of the fluid mixture within the main body of reactor tube 22 results in very little or no contact between nanotubes and the wall of reactor tube 22.

[0072] Nanotube growth may end when the metal catalyst particles become deactivated, the concentration of constituent carbon atoms near the metal catalyst particles decreases to a relatively low value, or the temperature decreases as the mixture moves out of the temperature range within reactor tube 22 and remains in a region sufficient for growth.

[0073] Figure 3 An exemplary tape forming system 23 of the present invention is illustrated. The described tape forming system 23 is merely one example of a tape forming system 23 that can be suitably incorporated into the principles of the present invention. In practice, various alternative designs and structures of the tape forming system 23 can be employed without departing from the scope of the invention. In one embodiment, the tape forming system 23 is coupled to a distal end of a CVD system 20 and typically includes a substantially hermetically sealed housing 31 and an inlet 33 for a substantially hermetically sealed connection to the outlet end 221 of a reactor tube 22.

[0074] The following is for reference. Figure 3-6G The strip forming system 23 further includes: an air knife assembly 35 located near the outlet end 221 of the reactor tube 22, operable to guide and control the width of the carbon nanotube sheath 50 as it leaves the reactor tube 22; and a vacuum conveying assembly 36 located below the air knife assembly 35, operable to extract the carbon nanotube sheath 50 from the air knife assembly 35 onto a conveying surface or conveyor belt 37 to form a carbon nanotube strip or film 60, and to convey the carbon nanotube strip 60 away from the air knife assembly 35. In another embodiment, the strip forming system 23 further includes a collecting assembly 38 located at the distal end of the air knife assembly 35, operable to collect the carbon nanotube strip 60 by the vacuum conveying assembly 36.

[0075] The air knife assembly 35 includes a first air guide component 40a supported by a vacuum delivery assembly 36. A mounting bracket 42 for the air guide component is fixed to the discharge delivery assembly 36 and supports the first air guide component 40a. An air supply line 44a extends from the first air guide component 40a and communicates with a pressurized air source 41.

[0076] The air knife assembly 35 also includes a second air guide component 40b. The second air guide component is located on the opposite side of the first air guide component 40a and is supported by the vacuum delivery assembly 36. An air guide component mounting bracket 42 is fixed to the vacuum delivery assembly 36 and supports the second air guide component 40b. The second air guide component 40b is substantially the same as the first air guide component 40a and also includes an air supply line 44b extending from the second air guide component 40b and communicating with a pressurized air source 41. In one embodiment, the bracket 42 of at least one of the air guide components 40a and 40b may be adjustable, so that the positions of the air guide components 40a and 40b can be adjusted relative to the delivery surface 37 of the vacuum delivery assembly 36. For example, the air guide components 40a and 40b can be adjusted so that their lower end spacing (“C”) is approximately 0.25–3.5 inches.

[0077] Although the specific structure, construction, and operation of the gas guiding components may differ, gas guiding components 40a and 40b are generally configured to provide a substantially continuous, high-concentration flow of gas thin layer sufficient to control the width of the carbon nanotube sheath. Since gas guiding component 40b is identical to gas guiding component 40a, only gas guiding component 40a will be further described below (these descriptions also apply to gas guiding component 40b).

[0078] The air-guiding component 40a includes a contraction section 45 having an outer wall 46 and a breathable inner wall 47 spaced apart from the outer wall 46. The outer wall 46 may be made of an impermeable metal such as stainless steel, carbon steel (with or without coating), aluminum, or other impermeable materials.

[0079] The breathable inner wall 47 can be made of a porous plate, such as a porous graphite plate, a porous metal plate, a porous stainless steel plate, a porous aluminum plate, a porous brass plate, a porous ceramic plate, a porous resin plate, or a porous composite plate, such as a composite plate of carbon, KEVLAR aramid, and boron. In some embodiments, the breathable inner wall 47 may comprise two or more layers of the same or different of the above-mentioned materials. In a particular embodiment, the breathable inner wall 47 comprises a porous graphite plate. As discussed further below, the carbon nanotube sheath 50 is fluidized and / or suspended above the porous surface of the breathable inner wall, enabling the carbon nanotube sheath 50 to pass through the inner wall with extremely low friction in a manner similar to an air hockey puck surface without adhering to the wall.

[0080] Alternatively, instead of using a perforated plate, the permeable inner wall 47 can be, for example, a screen or mesh material. In another alternative, the permeable inner wall 47 can be a fluidizing plate, which is formed by processing (e.g., machining, drilling, water jetting, laser cutting) to create multiple holes, grooves, channels, and / or jet holes or channels running through the fluidizing plate. The holes, grooves, channels, and / or jet holes can be in specific patterns (e.g., matrix, radial, star-shaped, concentric circles). Furthermore, the construction of the holes, grooves, channels, and / or jet holes can be customized (e.g., different sizes, different profiles, different cross-sectional shapes, tapers, specific surface roughness, and / or surface treatments of the holes, grooves, channels, and / or jet holes or outer surfaces) to produce various fluidization effects.

[0081] Various methods can be used to secure the breathable inner wall 47 to the inner surface of the contraction section 45. For example, one or more connecting structures can be provided on the inner surface of the contraction section 45, and the breathable inner wall 47 can be connected to said structures by welding, bolting, or other known connection methods.

[0082] As shown in the figure, the air knife assembly 35 has a vertical axis "L" parallel to the normal vector "N". Figure 4 As shown, the contraction section 45 has a horizontal inclination angle α, which is relative to the horizontal plane perpendicular to the vertical axis L and the vector N. Therefore, as the horizontal inclination angle α formed with the horizontal plane increases, the steepness of the inclination of the outer wall 46 also increases.

[0083] Figure 4 The vertical tilt angle β relative to a vertical vector N parallel to the longitudinal axis L is also given, which can be measured between the inclined outer wall 46 of the contraction section 45 and the normal (or vertical) vector N of the air knife assembly 35. The vertical tilt angle β is equal to 90°. Subtract the horizontal tilt angle α. In the example described, when the value of the tilt angle β is close to zero degrees (0°), When the contraction section 45 is in the contraction phase, the inclined outer wall 46 becomes steeper.

[0084] Although other tilt angles are also considered, according to one implementation scheme, the typical range of the horizontal tilt angle α can be approximately 25-65 degrees. or about 40-50 or about 45 Similarly, while other angles are also considered, in another implementation, the typical range of the vertical tilt angle β can be approximately 20-60 degrees. Or approximately 30-55 or about 45 .

[0085] exist Figure 4In the illustrated belt-forming system, the breathable inner wall 47 conforms to the inclination of the outer wall 46. Therefore, the outer wall 46 and the breathable inner wall 47 can have the same inclination angles α and β. However, the invention also considers the possibility that the breathable inner wall 47 does not conform to the inclination of the outer wall 46. Regardless of whether the breathable inner wall 47 conforms to the inclination of the outer wall, the breathable inner wall 47 can be oriented within the range of inclination angles α and β as described above. Therefore, although other angles are also considered, in one embodiment, the breathable inner wall 47 has a horizontal inclination angle α of approximately 25-65 degrees. or about 40-50 or about 45 Downward orientation. Similarly, although other angles are also considered, the breathable inner wall 47 has an inclination angle β of approximately 20-60 degrees. Or approximately 30-55 or about 45 Downward orientation.

[0086] As discussed above, the air knife assembly 35 includes a converging section 45 having an outer wall 46 and a permeable inner wall 47 spaced apart from the outer wall. The air knife assembly 35 also includes air supply lines 44A and 44B, which communicate with the air supply source 41 and the space between the outer wall section 46 and the inner wall section 47. The flow rate in the air supply lines can be controlled by a valve V.

[0087] Therefore, the air knife assembly 35 includes a permeable inner wall 47 on the contraction section 45 but spaced apart from the inner surface of the contraction section 45, thereby forming a space between the permeable inner wall 47 and the inclined outer wall 46 of the contraction section 45. Gas from air supply lines 44A and B communicating with the air supply source 41 is injected into the space between the permeable inner wall 47 and the inclined outer wall 46 of the contraction section 45 and passes through the permeable inner wall 47. This forms a gas layer between the permeable inner wall 47 and the carbon nanotube sheath, causing the carbon nanotube sheath in the air knife assembly 35 to fluidize above the permeable inner wall 47. This enhances the flow of the carbon nanotube sheath within it, so that the carbon nanotube sheath is guided with sufficient fluidity within the contraction section 45 without adhering to the air guiding components.

[0088] The gas supply system, including the gas supply device and pipeline, may also include pipes, pressure regulating equipment, a main pipe, valves, nozzles (e.g., adjustable nozzles), connectors (e.g., pipe fittings), etc., for guiding or delivering air or other suitable gases (such as argon, hydrogen, or any pressurized gas) to the gas delivery component 40a. Gas can be supplied / injected into the space between the outer wall 46 and the permeable inner wall 47 at a controlled pressure and flow rate. Valve V can assist in controlling the gas flow rate.

[0089] The tape-forming system 23 also includes a vacuum delivery assembly 36. The vacuum delivery assembly 36 can be operated to deliver the carbon nanotube sheath 50 (see [link to documentation]). Figure 5The carbon nanotubes are drawn from the air knife assembly 35 onto the conveyor surface, thereby forming a carbon nanotube belt, and then conveyed away from the air knife assembly 35. In some embodiments, the conveyor belt can be controlled by a simple drive, wherein the drive speed is controlled by a motor.

[0090] Figure 6A An embodiment of a vacuum delivery assembly 36 applicable in this invention is described. As shown, the vacuum delivery assembly 36 includes a vacuum source 602. The vacuum source 602 can be in fluid communication with a platform 604. Therefore, the vacuum source 602 can be configured to extract air from the platform 604. The platform 604 has a first platform end 662 and a second platform end 664 opposite to the first platform end 662, with a length extending along the MD direction defined between them. Additionally, the platform 604 has a width extending along the transverse direction CD. Figure 6B As shown, platform 604 may include one or more channels 626 that extend in the MD direction and are located on platform surface 606. (Continue to reference) Figure 6A The conveyor belt 608 may be adjacent to the platform surface 606. The conveyor belt 608 has a length extending in the direction MD and a width extending in the transverse direction CD. Additionally, the conveyor belt 608 may include a first surface 610, a second surface 612 opposite to the first surface 610, a first edge 636, and a second edge 638 opposite to the first edge 636. The second surface 612 of the conveyor belt 608 may face the platform surface 606, and the first surface 610 may be exposed to the carbon nanotube sheath. The conveyor belt 608 may also include one or more holes 614 disposed between the first edge 636 and the second edge 638. Furthermore, each hole 614 defined by the conveyor belt 608 may be aligned with at least one channel 626 on the platform 604. Therefore, air can be extracted through the holes 614, then enter the platform 604 via the channel 626, and exit to the vacuum source 602.

[0091] The conveyor belt 608 may also include a first row of teeth and a second row of teeth disposed on a second surface 612 of the conveyor belt 608. In one embodiment, the first row of teeth and the second row of teeth connected to the conveyor belt 608 may be used to drive the conveyor belt via a transmission mechanism 615. The transmission mechanism 615 may be adjacent to the first platform end 662 and configured to mesh with and drive the conveyor belt. More specifically, the first row of teeth may mesh with a first gear element 616, and the second row of teeth may mesh with a second gear element 618. The first gear element 616 and the second gear element 618 may be located on a shaft member 620 driven by a drive mechanism 622 (such as a rotary motor). Thus, when the shaft member 620 rotates, the first gear element 616 and the second gear element 618 rotate about the longitudinal axis 624 of the shaft member 620. The rotation of the first gear element 616 and the second gear element 618 may drive the conveyor belt 608 to move along the platform surface 606 in the MD direction.

[0092] like Figure 6A As shown, a guide mechanism 646 can be positioned opposite and adjacent to the second platform end 664 of the transmission mechanism 615. The guide mechanism 646 can be configured to guide the conveyor belt 608 during operation of the vacuum conveying system 36. For example, in a vacuum conveying system comprising a continuous loop conveyor belt, it is necessary to guide the conveyor belt back onto the platform surface during operation. The guide mechanism 646 may include a shaft 666 rotatable about a longitudinal axis 668. The shaft 666 can be used to support the conveyor belt 608. In an alternative embodiment not shown, it is believed that a drive mechanism 622 can also operatively engage with the shaft 666, thereby driving the drive mechanism 622 to rotate the shaft 666 about the longitudinal axis 668. Rotation of the shaft 666 can cause the conveyor belt 608 to move along the MD direction.

[0093] refer to Figure 6B and 6C As described above, a vacuum source 602 can be connected to a platform 604, thereby drawing air from the platform 604 to the vacuum source 602. The platform 604 has a platform length DL extending in the MD direction and a platform width DW extending in the lateral direction CD. A platform surface 606 can define one or more channels 626. Channels 626 can extend through the platform surface 606, such that each channel 626 is in fluid communication with the vacuum source 602. Each channel 626 can have a specific size and shape. The size and shape of each channel 626 can be the same as or different from the size and shape of the other channels 626. However, the size and shape of the channel 626 should be sufficient to provide the required suction force, either alone or in combination with the conveyor belt 608. In one example implementation, such as... Figure 6C As shown, channel 626 can be an elongated elliptical shape. Additionally, channel 626 can be located on platform surface 606, so that the holes 614 in conveyor belt 608, when located on platform surface 606, are subjected to a substantially constant vacuum. Platform 604 can be made of any material having sufficient strength to withstand the loads of the conveyor belt and the items being transported, and sufficient structural rigidity to withstand one or more channels 626 that may extend through platform surface 606. For example, platform 604 can be constructed of steel, aluminum, ceramic, phenolic board, and / or polymer elements, including but not limited to UHMW polymers, Teflon, phenolic polymers, and / or Dellin (polyoxymethylene). Platform surface 606 can also be anodized, electroplated, vapor-deposited coated, polymer-coated, or ceramic-coated to reduce the coefficient of friction and decrease wear.

[0094] like Figure 6DAs shown, the conveyor belt 608 may extend along at least a portion of the platform surface 606. More specifically, the conveyor belt 608 may be located on the platform surface 606 such that the entire width BW of the conveyor belt is supported by the platform surface 606. In other words, in one embodiment, the conveyor bandwidth BW may be less than or equal to the platform bandwidth DW. The conveyor belt 608 may include a first edge 636 and a second edge 638 opposite to the first edge 636. Additionally, the conveyor belt may include one or more holes 614 located within the first edge 636 and the second edge 638. In one embodiment, the one or more holes 614 may be arranged in a row. Furthermore, the conveyor belt 608 may be located on the platform surface 606 such that each row of holes 214 is in fluid communication with one or more channels 626 on the platform surface 606. If the conveyor belt 608 is properly aligned to allow the holes 614 to be in fluid communication with the channels 626, the holes 614 can be designed to have a smaller cross-section. In other words, if the manufacturer knows that the hole 614 on the conveyor belt 608 will not be misaligned with the channel 626, the manufacturer can design the hole 614 to have a smaller cross-section and / or make its cross-section match the cross-section of the channel, thus achieving stronger suction with lower energy consumption.

[0095] Alternatively, if it is known that the holes 614 on the conveyor belt 608 may become misaligned (also known as off-center) during processing, then the holes 614 need to be designed with a larger cross-section so that at least some portions of the holes can still maintain fluid communication with the channels 626 when the conveyor belt becomes misaligned. Designing larger holes 614 allows for the acquisition and / or maintenance of the required suction on the carbon nanotube strips. The vacuum source 602 needs to draw more air through the holes 614 to maintain the required suction on the carbon nanotube strips. Therefore, reducing the off-center of the conveyor belt 608 allows for a smaller CD size for the channels 626 and a smaller CD size for the holes 614 on the conveyor belt 608, given the CD width of the holes 614, which can increase the strength of the conveyor belt 608. It is important that the conveyor belt 608 maintains its orientation along the CD direction so that one or more holes 614 remain substantially aligned with one or more channels 626.

[0096] One or more holes 614 can be arranged in any number of structures on the conveyor belt 608. The size of one or more holes 614 can be determined based on the configuration of the channel 626 and the suction capacity of the vacuum source 602 to generate the desired suction on the carbon nanotube strips. The shape of each hole 614 can be determined to maximize the ability to control the carbon nanotube strips. For example, in one embodiment, such as... Figure 6EAs shown, the aperture 614 can be circular. In an alternative embodiment (not shown), the aperture can be an elongated ellipse to maximize the cross-sectional area of ​​the aperture 614 in fluid communication with the carbon nanotube strips within a given CD width of the channel 626. Furthermore, the layout design of one or more apertures 614 should take into account the layout of the channel 626 on the platform surface 606 and / or the dimensions of the carbon nanotube strips to be processed. The apertures 614 should be arranged on the conveyor belt 608 such that one or more apertures 614 remain in fluid contact with the channel 626 when the conveyor belt 608 covers the platform surface 606. Fluid contact means that a vacuum source can draw air into the platform 604 through the aperture 614 and the adjacent channel 626.

[0097] like Figure 6E As shown, the conveyor belt 608 can be configured to form a continuous loop. To form a continuous loop, the conveyor belt 608 may include a seam 628. The seam 628 may be located at the junction of the two ends of the conveyor belt. The seam 628 should be strong enough to withstand the stresses applied to the conveyor belt 608 during manufacturing. Because the conveyor belt has a continuous loop structure, during the manufacturing process of the carbon nanotube belt, the second surface 612 of the conveyor belt may remain engaged with the drive mechanism 615 and the guide mechanism 646. Therefore, the second surface 612 of the conveyor belt 608 may be connected to one or more rows of teeth to interact with the drive mechanism 615 and the guide mechanism 646.

[0098] As mentioned above, such as Figure 6F As shown, the conveyor belt 608 can be driven along the MD direction by the track mechanism 615. The conveyor belt 608 may include a first row of teeth and a second row of teeth, which the transmission mechanism 615 can use to move the conveyor belt. The first row of teeth can mesh with a first gear element 616, and the second row of teeth can mesh with a second gear element 618. The surface profile of the first gear element 616 can match the first row of teeth, and the surface profile of the second gear element 618 can match the second row of teeth. Therefore, when the shaft member 620 rotates, the first gear element 616 and the second gear element 618 rotate about the longitudinal axis 624 of the shaft member 620. When the first gear element 616 and the second gear element 618 rotate, they mesh with a portion of the first and second rows of teeth, respectively, causing the conveyor belt 608 to move along the platform surface 606 in the MD direction. "Meshing" means that the gear teeth of the gear elements are interconnected with each row of teeth, enabling the gear teeth to apply force to each row of teeth to drive the conveyor belt to move.

[0099] like Figure 6FAs shown, the transmission mechanism 615 may include a shaft member 620 having a first end 648 and a second end 650 opposite to the first end 648, and a shaft length 652 extending in a transverse CD direction. The shaft member 620 is rotatable about a longitudinal axis 624. The shaft member 620 may be connected to a roll 644 located between the first end 648 and the second end 650 of the shaft member 620. The roll 644 meshes with the shaft member, so that when the shaft member rotates, the roll also rotates about the longitudinal axis 624. The roll 644 has an outer surface 654 with an outer periphery and may be configured to support a conveyor belt 608 when it moves. Additionally, the roll 644 includes a first roll end 656 and a second roll end 658 opposite to the first roll end. The first roll end 656 may be adjacent to a first gear element 616. Similarly, the second roll end 658 may be adjacent to a second gear element 618. More specifically, the second gear element 618 can be detachably connected to the second roll end 658. For example, the second gear element 618 can be helically connected to the second roll end 658. In addition, at least one of the roll 644 and the second gear element 618 can be fixedly connected to the shaft member 620, so that when the shaft member rotates, the roll 644 and the second gear element 618 can also rotate about the longitudinal axis 624.

[0100] like Figure 6F As shown, the first gear element 616 may be adjacent to the first roll end 656 and the first end of the shaft member 648. The first gear element 616 may slidably engage with the shaft member 620, allowing the first gear element 616 to move along the shaft length 652. In other words, the first gear element 616 may be movably connected to the first end 648 of the shaft member 620, thereby allowing the second gear element to move along the length 652 of the shaft member 620 in the transverse CD direction. Therefore, the first gear element 616 may slide along the surface of the shaft member 620 in the transverse CD direction. The transverse movement of the first gear element 616 may be limited, thereby allowing a stop (not shown) to be provided between the first gear element 616 and the first end 648 of the shaft member 620. In addition, the splines located on the first gear element 616 and the shaft member 620 interact, allowing the first gear element 616 to rotate about the longitudinal axis 624 of the shaft member 620 when the shaft member 620 rotates. It is believed that the configuration of the first gear element 616 can also be used for the second gear element 618, so that the second gear element 618 can slide engage with the shaft element. By causing at least one of the first gear element 616 and the second gear element 618 to slide engage with the shaft member 624, the conveyor belt 608 can move in the lateral direction CD. This lateral movement can alleviate the lateral forces acting on the conveyor belt 608, thereby extending the conveyor belt's life and improving production efficiency.

[0101] As mentioned above, Figure 6AAs shown, the guide mechanism 646 may be opposite to the transmission mechanism 615 and adjacent to the second platform end 664. The guide mechanism 646 may include a shaft 666 rotatable about a longitudinal axis 668, such as... Figure 6G As shown in detail. A shaft 666 can be constructed to interact with the second surface 612 of the conveyor belt 608 during operation of the vacuum conveying system 36, and to guide and / or drive the conveyor belt 608. The shaft 666 includes an outer surface 670 having a periphery, and a shaft length 676 extending between a first shaft end 672 and a second shaft end 674 opposite to the first shaft end 672. For example, in one embodiment, the shaft 666 may include an outer surface 670 having a uniform periphery extending along the shaft length 676 from the first shaft end 672 to the second shaft end 674 (not shown). In another alternative embodiment, the shaft 666 may include an outer surface 670 having a periphery that varies along the shaft length 676.

[0102] It is believed that conveyor belt 608 can be driven forward by shaft member 622 and / or shaft 666. More specifically, drive mechanism 622 can be operatively connected to at least one of shaft member 620 and shaft 666. For example, in one embodiment, drive mechanism 622 can be operatively connected to shaft member 620, thereby forcing shaft member 622 to rotate about longitudinal axis 624, thereby driving conveyor belt 608 forward. In an alternative embodiment, drive mechanism 622 can be operatively connected to shaft 666, thereby driving shaft 666 to rotate about longitudinal axis 668, thereby driving conveyor belt 608 forward.

[0103] The carbon nanotube sheath can be extracted to form a carbon nanotube band and transported away from the air knife assembly using the following steps. For example... Figure 5 and Figure 6AThe conveying assembly 36 shown is located below the air knife assembly 35. The vacuum conveying assembly 36 may include a platform 604 and a conveyor belt 608. The platform may include a channel 626. The conveyor belt 608 may include a first surface 610, a second surface 612 opposite to the first surface, and a row of holes 614. The second surface 612 of the conveyor belt 608 may face the platform 604. Air can be extracted through the channel 626 using a vacuum source 602. Air extraction through the row of holes 614 and the channel 626 can generate suction on the carbon nanotube sheath 50 within the air guiding component of the air knife assembly 35, thereby drawing the carbon nanotube sheath 50 onto the first surface 610 of the conveyor belt 608 to form a carbon nanotube strip 60 (see Figure 7). The carbon nanotube strip 60 is pressed onto the first surface 610 of the conveyor belt 608. The conveyor belt 608 may advance along the MD direction. To assist the forward movement of the conveyor belt 608 and / or maintain its alignment, the inclined teeth of the first gear element 616 can mesh with a first row of inclined teeth connected to the second surface 612 of the conveyor belt 608, and the inclined teeth of the second gear element 618 can mesh with a second row of inclined teeth connected to the second surface 612 of the conveyor belt 608. At least one of the first gear element 616 and the second gear element 618 can be connected to a shaft member 620. The shaft member can rotate about a longitudinal axis, and the first and second gear elements can rotate with the shaft member. The rows of holes 614 can be aligned with the channel 626 by moving the conveyor belt 608 in the transverse direction CD. In addition, the conveyor belt 608 can be guided in the MD direction by supporting the second surface 612 of the conveyor belt 608 with a shaft 666.

[0104] According to one implementation scheme, the belt forming system 23 may also include a collection component. (See reference) Figure 3 7. The collecting assembly 38 includes a winding device 62 spaced from the air knife assembly 35 and located at the end of the vacuum delivery assembly 36. The winding device 62 collects carbon nanotube strips 60 from the vacuum delivery assembly 36 onto at least one reel 63. The winding device 62 includes a pair of towers 64 for supporting the reels 63. The reels 63 can be removed from the towers 64.

[0105] The following is for reference. Figure 8In an alternative embodiment, the strip forming mechanism 23 may be coupled to an airlock 72. An "airlock" refers to any housing or chamber equipped with two opening / closing mechanisms, such as a physical barrier like a cap or gas barrier, which is substantially airtight in its closed state. Therefore, the airlock 72 is equipped with a first or internal opening / closing mechanism 73 located between the strip forming mechanism 23 and the airlock 72. The airlock 72 is also equipped with a second or external opening / closing mechanism 74, such as a physical barrier like a cap or gas barrier, for separating the airlock 72 from the external environment 75 of the strip forming mechanism 23. Although only one airlock is given, two or more airlocks may also be used. The airlock can be operated to form an effective barrier that prevents gas (i.e., hydrogen) from escaping from the strip forming mechanism 23 during the introduction and extraction of the carbon nanotube strip 60 from the chamber. Thus, the airlock allows the continuous delivery mechanism 76 carrying the carbon nanotube strip 60 to enter and exit the chamber while preventing hydrogen from escaping from the chamber. The airlock 72 also includes an outlet 77 for removing a gaseous vapor / air mixture from the chamber, the mixture originating from carbon nanotube strips 60 that have not been completely dehydrogenated, and / or from gas exchange between the strip forming mechanism 23 and the airlock 72 when the first opening / closing mechanism located between the airlock and the strip forming mechanism is opened. The degassed carbon nanotube strips 76 exiting the airlock can then be conveyed via a conveying mechanism to a collection system similar to that described above, or to other equipment or systems for post-processing.

[0106] According to another embodiment, a system for the continuous production of carbon nanotube strips is provided, which generally includes: (i) a horizontally oriented chemical vapor deposition system as described herein; and (ii) a strip forming system coupled to the horizontally oriented chemical vapor deposition system as described herein.

[0107] Therefore, in one embodiment, the chemical vapor deposition includes: (a) a reactor having a proximal end, an upper distal end, and an internal cavity configured to contain a dense phase gas; (b) an ejector located at the proximal end of the reactor and configured to push a fluid mixture into the reactor, the fluid mixture comprising: a metal catalyst precursor from which metal catalyst particles can be generated for subsequent growth of elongated untangled carbon nanotubes thereon, a modifier compound for controlling the particle size distribution of the metal catalyst particles generated from the metal catalyst precursor, and a carbon source for depositing carbon atoms on the metal catalyst particles to grow elongated untangled carbon nanotubes; and (c) a furnace surrounding the reactor, configured to heat the reactor to a temperature sufficient to generate metal catalyst particles from the metal catalyst precursor and carbon atoms from the carbon source. Thus, the chemical vapor deposition system can be operated to produce carbon nanotube sheaths from elongated untangled carbon nanotubes.

[0108] The strip-forming system includes: (a) a housing having an inlet for substantially hermetically sealed connection to the reactor outlet of a chemical vapor deposition system; (b) an air knife assembly including opposing guide mechanisms operable for controlling the width of the carbon nanotube sheath; and (c) a vacuum delivery system operable for extracting the carbon nanotube sheath from the air knife assembly to a delivery surface to form a carbon nanotube strip and for delivering the carbon nanotubes away from the air knife assembly. In some embodiments, the strip-forming system further includes a collection system for collecting the carbon nanotube strip from the delivery surface of the vacuum delivery assembly.

[0109] In an alternative implementation, the system further includes an airlock coupled to the outlet of the vacuum conveying system, operable to degas the carbon nanotube strip and convey it into the atmosphere for collection on the reel described above or in a device for post-processing.

[0110] In yet another embodiment, a method for the continuous production of carbon nanotube strips is provided, the method generally comprising the steps of: (i) producing carbon nanotube material in a horizontally oriented chemical vapor deposition system as described herein; and (ii) introducing the carbon nanotube material into a strip forming system coupled herein to the chemical vapor deposition system, the strip forming system being operable for producing carbon nanotube strips.

[0111] While various embodiments of making and applying the invention have been described in detail above, it should be understood that the invention provides many implementable inventive concepts that can be realized in many specific situations. The specific embodiments discussed herein merely describe particular ways of making and applying the invention and do not limit the scope of the invention.

Claims

1. A system for continuous production of carbon nanotube strips, comprising: (a) A chemical vapor deposition system operable for forming carbon nanotube materials; and (b) A strip forming system comprising: (i) a housing having an inlet coupled to an outlet of a chemical vapor deposition system; (ii) an air knife assembly located near the inlet and operable to receive carbon nanotube material; and (iii) a vacuum delivery system operable to extract carbon nanotube material from the air knife assembly and form carbon nanotube strips.

2. The system of claim 1, wherein the air knife assembly includes opposing air guiding components operable for controlling the width of the carbon nanotube material.

3. The system of claim 2, wherein the carbon nanotube material is a carbon nanotube sheath.

4. The system of claim 1, wherein the vacuum delivery system includes a vacuum source in fluid communication with the continuous delivery surface.

5. The system of claim 1 further includes a collection system for collecting carbon nanotube strips.

6. The system of claim 5, wherein the collection system is located inside the housing of the belt forming system.

7. The system of claim 5, wherein the collection system is located outside the housing of the belt forming system.

8. The system of claim 7 further includes an airlock located between the belt forming system and the collection system.

9. The system of claim 1, wherein the chemical vapor deposition system is a floating catalyst chemical vapor deposition system.

10. A method for continuous production of carbon nanotube strips, comprising: (a) Fabrication of elongated carbon nanotubes in a chemical vapor deposition system, the chemical vapor deposition system comprising a synthesis chamber having an inlet end providing reactant gases, a hot zone for synthesizing elongated carbon nanotubes from the reactant gases, and an outlet end from which the elongated carbon nanotubes exit. (b) Introducing untangled carbon nanotubes into a tape forming system, wherein the tape forming system comprises: a housing having an inlet connected to the outlet of the synthesis chamber; an air knife assembly near the inlet of the tape forming system for providing a continuous gas flow layer to prevent untangled elongated carbon nanotubes from adhering to the inlet and the air knife assembly; and a vacuum delivery system located below the air knife assembly for providing a vacuum to degas and extract the untangled elongated carbon nanotubes and form carbon nanotube tapes.

11. The method of claim 10, wherein the untangled elongated carbon nanotubes leaving the synthesis chamber entangle, bundle, and otherwise aggregate to form an extended network of interconnected and branched bundles, thereby forming a hollow carbon nanotube sheath.

12. The method of claim 10, wherein the air knife assembly guides and controls the width of the carbon nanotube sheath.

13. The method of claim 12, wherein the vacuum delivery system extracts a carbon nanotube sheath onto a delivery surface to form a carbon nanotube strip.

14. The method of claim 13, wherein the vacuum transport system transports the carbon nanotube strip on the transport surface away from the air knife assembly.

15. The method of claim 14, wherein the carbon nanotube strip is delivered to the collection system and wound onto a reel.

16. The method of claim 14, wherein the carbon nanotube strip is conveyed to the airlock and further degassed to form a degassed carbon nanotube strip.

17. The method of claim 16, wherein the degassed carbon nanotube strip is conveyed to a collection system and wound onto a reel.

18. Carbon nanotube strips produced by the method according to claim 10.

19. The carbon nanotube strip of claim 18, wherein the carbon nanotube strip has a width of about 5 / 16-3 inches and a length greater than 650 feet.

20. The carbon nanotube strip of claim 19, wherein the carbon nanotube strip has substantially straight edges. [Add weights related to using variable belt speed and vacuum extraction to control density.] [Add descriptions and claims regarding CBC injectors and furnace tube dimensions to vary density in the 1-100 gram range.]

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