A method for continuously preparing high-conductivity carbon nanotube fiber tows by uniformly propelling a high-quality liquid crystal solution with air pressure

Abstract

The present application relates to the controllable preparation technical field of carbon nanotube fiber bundle, in particular to a method for continuously preparing high-conductivity carbon nanotube fiber bundle by uniformly pushing high-quality liquid crystal solution with air pressure. The high-quality carbon nanotube liquid crystal spinning solution is used as raw material, and is placed in a charging kettle. The liquid crystal spinning solution is pressed into a ketone coagulation bath through a multi-hole spinneret by uniform air pressure generated by an air compressor, and then the high-conductivity carbon nanotube fiber bundle is continuously prepared through a winding device. The present application breaks through the technical bottleneck of the current continuous spinning of high-performance carbon nanotube fiber bundle, and realizes the continuous preparation of high-orientation-degree and high-conductivity carbon nanotube fiber bundle.

Description

Technical Field

[0001] This invention relates to the field of controllable preparation technology of carbon nanotube fiber bundles, specifically a method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform gas pressure. Background Technology

[0002] Carbon nanotubes possess excellent electrical, thermal, and mechanical properties, with a theoretical electrical conductivity as high as 10⁻⁶. 8 S·m -1 Thermal conductivity 3000 W·m -1 ·K -1 With tensile strength reaching 100 GPa, macroscopic carbon nanotube fibers are considered ideal next-generation conductive fiber materials, with promising applications in flexible sensors, high-performance cables, artificial muscles, and many other fields. However, carbon nanotube fibers have not yet achieved large-scale application, mainly due to their low yield and micron-level size, which cannot meet application requirements in most cases. Therefore, improving carbon nanotube fiber spinning technology, increasing yield, and preparing high-performance carbon nanotube fiber bundles are key to achieving their large-scale application.

[0003] Currently, the main methods for preparing carbon nanotube fibers are divided into dry spinning and wet spinning. Dry spinning can be further divided into array spinning and direct spinning via chemical vapor deposition with floating catalyst. Array spinning involves first growing a vertical array of super-aligned carbon nanotubes on a substrate, then pulling the carbon nanotubes out from one end of the array. Under the action of van der Waals forces between the tubes, the carbon nanotubes connect end to end to form a continuous fiber (Reference 1: Jiang K, Li Q, Fan S. Nature, 2002 (6909)). Direct spinning via chemical vapor deposition with floating catalyst involves directly pulling out the carbon nanotubes generated in the high-temperature reaction zone and spinning them into continuous carbon nanotube fibers (Reference 2: Zhu, HWScience, 2002, 296 (5569): 884-886). Wet spinning involves mixing pretreated carbon nanotubes with chlorosulfonic acid in a specific ratio to form a homogeneous liquid crystal spinning solution, which is then extruded into a coagulation bath to form carbon nanotube fibers (Reference 3: Vigolo B, Penicaud A, Coulon C, Sauder C., Pailler R., Journet C, Bernier B, Poulin B. Science. 2000, 290(5495), 1331-1334). Compared to dry spinning, wet-spun fibers exhibit a more compact arrangement of carbon nanotubes and stronger inter-tube interactions, making them suitable for producing high-performance fibers. Furthermore, wet spinning draws upon the spinning technology of chemical fibers in industrial production, possessing a more complete technological system. Therefore, wet spinning has significant advantages in the industrialization of carbon nanotube fibers.

[0004] However, current literature reports on wet spinning techniques for preparing carbon nanotube fibers are all monofilament techniques, with fiber diameters around 20 micrometers. These small-diameter single carbon nanotube fibers limit their practical applications, thus necessitating the development of a method for continuously preparing carbon nanotube fiber bundles. Currently, there are no reported techniques for continuously preparing carbon nanotube fiber bundles, primarily because simultaneously preparing fiber bundles with high orientation, good continuity, and no fiber sticking is extremely challenging.

[0005] In summary, in order to realize the practical application of carbon nanotube fibers, it is urgent to develop a method for the continuous preparation of carbon nanotube fiber bundles with high electrical conductivity. Summary of the Invention

[0006] The purpose of this invention is to provide a method for the continuous preparation of high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under air pressure. This method overcomes the technical bottleneck of continuous preparation of carbon nanotube fiber bundles by utilizing the stable, adjustable, and uniform propulsion power provided by an air compressor, combined with the high viscosity of a high-quality, high aspect ratio carbon nanotube liquid crystal spinning solution, to achieve continuous preparation of high-conductivity carbon nanotube fiber bundles.

[0007] The technical solution of this invention is:

[0008] A method for continuously preparing high-conductivity carbon nanotube fiber bundles using a high-quality liquid crystal spinning solution propelled by uniform air pressure involves using a high-quality carbon nanotube liquid crystal spinning solution as raw material. The solution is placed in a loading vessel, and uniform air pressure generated by an air compressor forces the solution through a porous spinneret into an acetone coagulation bath. The high-conductivity carbon nanotube fiber bundles are then continuously prepared using a winding device. The high-quality carbon nanotube liquid crystal spinning solution has a viscosity ≥3000 cp, a carbon nanotube aspect ratio ≥15000, and a Raman spectrum of I0.05. G / I D The ratio is ≥80.

[0009] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure includes an air compressor, a loading vessel, a porous spinneret, a coagulation bath, and a winding device. The specific structure is as follows: the top of the sealed loading vessel is connected to the air compressor through a pipeline, the bottom of the loading vessel is connected to the porous spinneret through a pipeline, the porous spinneret is placed in the coagulation bath below the loading vessel, and one end of the winding device is set in the coagulation bath and corresponds to the spinning direction of the porous spinneret.

[0010] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure uses a compressor to force the high-quality carbon nanotube liquid crystal spinning solution out of the loading vessel. This method is beneficial for efficiently utilizing the volume of the loading vessel and continuously preparing high-conductivity carbon nanotube fiber bundles, while reducing the residual carbon nanotube liquid crystal spinning solution in the wet spinning system. The compressor pressure is between 20 and 200 MPa.

[0011] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure has an adjustable number of holes and inner diameter of the porous spinneret, with the number of holes ranging from 5 to 50 and the inner diameter of the holes ranging from 80 to 120 μm.

[0012] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure has an adjustable winding speed. By adjusting this speed and the air compressor pressure, a stretching effect is generated on the fiber, which helps to orient the carbon nanotubes in the fiber.

[0013] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure, wherein the number of high-conductivity carbon nanotube fiber bundles is 5 to 50, the diameter of a single fiber is 10 to 25 μm, the bundle diameter is 50 to 400 μm, and the length is not limited.

[0014] The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform gas pressure, and the Raman spectrum of the high-conductivity carbon nanotube fiber bundles I. G / I D It has a ratio ≥70, electrical conductivity up to 10 MS / m, and tensile strength up to 4 GPa.

[0015] The design concept of this invention is:

[0016] This invention utilizes the high viscosity and easy molding characteristics of high-quality, high aspect ratio carbon nanotube liquid crystal spinning solution. An air compressor provides uniform and stable propulsion pressure on a porous spinning plate, and the high-quality carbon nanotube liquid crystal spinning solution in the loading vessel is uniformly extruded into an acetone coagulation bath through the porous spinneret. The high-viscosity, oriented liquid crystal spinning solution is further oriented and compacted under the extrusion and shearing action of the spinneret orifice. The multiple fibers extruded from the spinneret undergo double diffusion and solidification in the coagulation bath. The solidified multiple fibers are simultaneously stretched in the same direction by the winding device, and they are stranded together to form carbon nanotube fiber bundles before exiting the liquid. Finally, the high-conductivity carbon nanotube fiber bundles are collected by the winding device.

[0017] The advantages and beneficial effects of this invention are:

[0018] 1. This invention utilizes an air compressor to provide uniform and stable propulsion pressure, combined with the high viscosity characteristics of a high-quality, high aspect ratio carbon nanotube liquid crystal solution, to break through the bottleneck of continuous preparation technology for high-performance carbon nanotube fiber bundles, and realizes the continuous preparation of carbon nanotube fiber bundles with high orientation and high conductivity.

[0019] 2. This invention introduces an air compressor as the power source for extruding the single-walled carbon nanotube liquid crystal spinning solution from the feeding vessel, and its pressure is continuously adjustable; and compared with the traditional piston feeding method, it is not limited by the size of the feeding vessel, which is conducive to increasing the size of the feeding vessel, thereby realizing the continuous preparation of carbon nanotube fiber bundles; at the same time, due to the permeability of gas, it is beneficial to reduce the residue of spinning solution in the wet spinning system and improve the utilization rate of materials.

[0020] 3. This invention can prepare high-quality Raman spectra (the intensity ratio of the G peak to the D peak in the spectrum is I). G / I D Carbon nanotube fiber bundles with a conductivity value ≥70 have achieved the highest performance of a single filament (10 MS / m).

[0021] 4. The method for preparing high-conductivity carbon nanotube fiber bundles developed in this invention can be applied to continuous production and is easy to scale up. It is expected to have important applications in high-performance cables, flexible sensors, aerospace and other fields. Attached Figure Description

[0022] Figure 1 A schematic diagram of an apparatus for the continuous preparation of high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure. In the diagram, 1-support, 2-feeding vessel, 3-air compressor, 4-porous spinneret, 5-coagulation bath, 6-winding device.

[0023] Figure 2 The image shows the Raman spectrum of the carbon nanotube liquid crystal spinning solution prepared in Example 1. In the figure, the horizontal axis represents the Raman shift (cm). -1 The vertical axis Intensity represents the relative intensity (au).

[0024] Figure 3 An optical photograph of the carbon nanotube fiber bundles prepared in Example 1.

[0025] Figure 4 The image shown is a scanning electron microscope (SEM) image of the carbon nanotube fiber bundles prepared in Example 1, with a scale bar of 50 μm.

[0026] Figure 5 The image shown is a scanning electron microscope (SEM) image of the carbon nanotube fiber bundles prepared in Example 1, with a scale bar of 100 μm. Detailed Implementation

[0027] like Figure 1 As shown, the apparatus for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under air pressure according to the present invention mainly includes a support 1, a loading vessel 2, an air compressor 3, a porous spinneret 4, a coagulation bath 5, and a winding device 6. The specific structure is as follows: The loading vessel 2 is mounted on the support 1. The top of the sealed loading vessel 2 is connected to the air compressor 3 via a pipeline, and the bottom of the loading vessel 2 is connected to the porous spinneret 4 via a pipeline. The porous spinneret 4 is placed in the coagulation bath 5 below the loading vessel 2. One end of the winding device 6 is positioned in the coagulation bath 5 and corresponds to the spinning direction of the porous spinneret 4. In use, the uniform and stable propelling air pressure provided by the air compressor 3 serves as the power source, forcing the high-quality carbon nanotube liquid crystal spinning solution in the loading vessel 2 through the porous spinneret 4 into the acetone coagulation bath 5. The fibers coagulate in the coagulation bath 5 and are collected by the winding device 6 to obtain high-conductivity fiber bundles.

[0028] In its specific implementation, this invention provides a method for the continuous preparation of high-conductivity carbon nanotube fiber bundles using a high-quality liquid crystal solution propelled by uniform air pressure (device diagram shown). Figure 1 The process includes the following steps:

[0029] (1) Carbon nanotubes with a high aspect ratio are mixed with chlorosulfonic acid in a certain proportion and then added to a high-speed mixer for stirring and dispersion to obtain a high-quality carbon nanotube liquid crystal spinning solution; preferably, the viscosity of the high-quality carbon nanotube liquid crystal spinning solution is 3000-6000 cp, the aspect ratio of the carbon nanotubes in the carbon nanotube liquid crystal spinning solution is 30000-80000, and the Raman spectrum is I G / I D The mass fraction of carbon nanotubes is 0.5–3.0 wt%, with a ratio of 80–120. 。

[0030] (2) The obtained carbon nanotube liquid crystal spinning solution is added to the loading vessel, and under the air pressure of the air compressor, the spinning solution is uniformly squeezed into the acetone coagulation bath through the porous spinneret.

[0031] (3) Under the directional stretching action of the winding machine, the fiber bundles are solidified and self-assembled in the coagulation bath to obtain carbon nanotube fiber bundles with high electrical conductivity.

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments.

[0033] Example 1

[0034] In this embodiment, a method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure includes the following steps:

[0035] (1) 630 mg of high-quality carbon nanotubes were mixed with 30 ml of chlorosulfonic acid. The mixture was then dispersed in a high-speed mixer at 3500 r / min for 10 min to obtain a carbon nanotube liquid crystal spinning solution with a mass fraction of 1.2 wt% and a viscosity of 5600 cp, a carbon nanotube aspect ratio of 75000, and a Raman I value. G / I D The ratio is 105 ( Figure 2 ).

[0036] (2) The carbon nanotube liquid crystal spinning solution prepared in step (1) is transferred to a loading vessel, and a spinneret with 10 holes and an inner diameter of 100 μm is selected. The air compressor pressure is set to 30 MPa. The carbon nanotube liquid crystal spinning solution in the loading vessel is extruded into an acetone coagulation bath through the porous spinneret. The spun yarn coagulates in the coagulation bath. The coagulated carbon nanotube fibers self-assemble and twist together and are collected by a winding device to obtain a continuous carbon nanotube fiber bundle. Figure 3 ).

[0037] The structure and properties of the prepared carbon nanotube fiber bundles were characterized, and the fiber scanning electron microscope images were obtained. Figure 4 This indicates that the diameter of the carbon nanotube fiber bundle is ~70 μm, and it is composed of multiple single fiber filaments. Figure 5 Raman spectroscopy I G / I D The ratio was 90, and the electrical conductivity of the fiber bundle was 10 MS / m, and the tensile breaking strength was 4 GPa, as measured by the four-wire method.

[0038] Example 2

[0039] In this embodiment, a method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure includes the following steps:

[0040] (1) Step (1) is the same as step (1) in Example 1, except that carbon nanotube raw material is used instead. The viscosity of the prepared carbon nanotube liquid crystal spinning solution is 4200cp, the aspect ratio of carbon nanotube is 52000, and the Raman spectrum G / D ratio is 95.

[0041] (2) Step (2) is the same as step (2) in Example 1, except that the air compressor pressure is changed to 50MPa, the number of spinneret holes is 50, and the inner diameter is 80μm.

[0042] The structure and properties of the prepared carbon nanotube fiber bundles were characterized. Scanning electron microscopy images showed that the diameter of the carbon nanotube fiber bundles was ~250 μm, and the Raman spectrum was I. G / I D The ratio was 75, and the electrical conductivity of the fiber bundle was 4.8 MS / m, and the tensile breaking strength was 2 GPa, as measured by the four-wire method.

[0043] Example 3

[0044] In this embodiment, a method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure includes the following steps:

[0045] (1) Step (1) is the same as step (1) in Example 1, except that carbon nanotube raw material is used instead. The prepared carbon nanotube liquid crystal spinning solution has a viscosity of 3000 cp, a carbon nanotube aspect ratio of 35000, and a Raman I value. G / I D The value is 85.

[0046] (2) Step (2) is the same as step (2) in Example 1, except that the air compressor pressure is changed to 80MPa, the number of spinneret holes is 20, and the inner diameter is 120μm.

[0047] The structure and properties of the prepared carbon nanotube fiber bundles were characterized. Scanning electron microscopy images showed that the diameter of the carbon nanotube fiber bundles was ~150 μm, and the Raman spectrum was I. G / I D The ratio was 72, and the electrical conductivity of the fiber bundle was 2 MS / m, and the tensile breaking strength was 1.2 GPa, as measured by the four-wire method.

[0048] Comparative Example 1:

[0049] In this comparative example, the method for preparing carbon nanotube fiber bundles using a low-mass carbon nanotube liquid crystal solution includes the following steps:

[0050] (1) Step (1) is the same as step (1) in Example 1, except that carbon nanotube raw material is used instead. The prepared carbon nanotube liquid crystal spinning solution has a viscosity of 1700 cp, a carbon nanotube aspect ratio of 8000, and a Raman I value. G / I D The value is 30.

[0051] (2) Step (2) is the same as step (2) in Example 1.

[0052] The structure and properties of the prepared carbon nanotube fiber bundles were characterized. Scanning electron microscopy images showed that the diameter of the carbon nanotube fiber bundles was ~85 μm, and Raman spectra were I0. G / I D The ratio was 22, and the electrical conductivity of the fiber bundle was 0.7 MS / m and the tensile breaking strength was 0.5 GPa, as measured by the four-wire method.

[0053] Comparative Example 2:

[0054] In this comparative example, the method for preparing carbon nanotube fiber bundles using a conventional piston feeding method includes the following steps:

[0055] (1) Step (1) is the same as step (1) in Example 1.

[0056] (2) Transfer the obtained liquid crystal spinning solution to an injection syringe, set the extrusion rate to 0.12 mL / min, and the rest is the same as step (2) in Example 1.

[0057] The structure and properties of the prepared carbon nanotube fiber bundles were characterized. Scanning electron microscopy images showed that the diameter of the carbon nanotube fiber bundles was ~70 μm, and Raman spectra were [missing information]. G / I D The ratio was 90, and the electrical conductivity of the fiber bundle was 9.8 MS / m, and the tensile breaking strength was 4 GPa, as measured by the four-wire method. However, due to the limitation of the injection syringe volume (10 mL), it is difficult to achieve continuous preparation of carbon nanotube fiber bundles.

[0058] In summary, this invention utilizes an air compressor as the power source for extruding the liquid crystal spinning solution from a porous spinneret. Combined with the high spinnability of the high-quality carbon nanotube liquid crystal spinning solution, it overcomes the bottleneck in carbon nanotube fiber bundle preparation technology, achieving continuous spinning of highly oriented, high-density carbon nanotube fiber bundles. The optimal performance reaches the highest single-filament performance reported in the current literature. The results show that the Raman spectrum of the high-conductivity carbon nanotube fiber bundles obtained by this invention... G / I D The specific gravity can reach 70 or higher, up to 90; the electrical conductivity can reach 2 MS / m or higher, up to 10 MS / m; and the tensile breaking strength can reach 1.2 GPa or higher, up to 4 GPa.

[0059] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure, characterized in that, Using high-quality carbon nanotube liquid crystal spinning solution as raw material, it is placed in a loading vessel. The liquid crystal spinning solution is pressed into an acetone coagulation bath through a porous spinneret using uniform air pressure generated by an air compressor. The air compressor pressure is 20~200MPa. Under the directional stretching action of the winding machine, the fiber bundles solidify and self-assemble in the coagulation bath. Then, high-conductivity carbon nanotube fiber bundles are continuously prepared by the winding device. High-quality carbon nanotube liquid crystal spinning solution has a viscosity ≥3000 cp, a carbon nanotube aspect ratio ≥15000, and Raman spectra I. G / I D The ratio is ≥80; the number of high-conductivity carbon nanotube fiber bundles is 5~50, the diameter of a single fiber is 10~25 μm, the bundle diameter is 50~400 μm, and the length is unlimited; Raman spectrum of high-conductivity carbon nanotube fiber bundles I G / I D It has a ratio of ≥70, an electrical conductivity of up to 10 MS / m, and a tensile strength of up to 4 GPa.

2. The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform gas pressure according to claim 1, characterized in that, The apparatus for continuously preparing high-conductivity carbon nanotube fiber bundles includes an air compressor, a loading vessel, a porous spinneret, a coagulation bath, and a winding device. The specific structure is as follows: the top of the sealed loading vessel is connected to the air compressor through a pipeline, the bottom of the loading vessel is connected to the porous spinneret through a pipeline, the porous spinneret is placed in the coagulation bath below the loading vessel, and one end of the winding device is set in the coagulation bath and corresponds to the spinning direction of the porous spinneret.

3. The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure according to claim 1, characterized in that, Using uniform pressure generated by an air compressor to expel high-quality carbon nanotube liquid crystal spinning solution from the loading vessel is beneficial for efficient utilization of the loading vessel volume and continuous preparation of high-conductivity carbon nanotube fiber bundles, while reducing residual carbon nanotube liquid crystal spinning solution in the wet spinning system.

4. The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure according to claim 1, characterized in that, The number of holes and the inner diameter of the porous spinneret are adjustable, with the number of holes ranging from 5 to 50 and the inner diameter from 80 to 120 μm.

5. The method for continuously preparing high-conductivity carbon nanotube fiber bundles by uniformly propelling a high-quality liquid crystal solution under uniform air pressure according to claim 1, characterized in that, The winding speed of the winding device is adjustable. By adjusting this speed and the air compressor pressure, a stretching effect is applied to the fiber, which helps to orient the carbon nanotubes in the fiber.

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