Highly oriented ultrathin extended carbon nanotube bundle, preparation method and application thereof

Abstract

The present invention discloses a highly oriented ultrathin widened bundle of carbon nanotubes, its preparation method and application. The preparation method comprises: providing a plurality of original carbon nanotube fibers; performing mechanical pre-widening; contacting the pre-widened bundle with a liquid expansion medium for expansion widening treatment; performing de-expansion treatment to remove part of the liquid expansion medium; cleaning and heat treating the de-expanded bundle to obtain a highly oriented ultrathin widened bundle of carbon nanotubes. The present invention utilizes a combination of mechanical widening and expansion widening, and utilizes the filling, lubrication, bonding and tension adjustment effects of high molecular polymers to avoid the problems of dispersion, cracking and shrinkage during the expansion and widening process. A secondary removal method is adopted when removing the liquid expansion medium to avoid significant shrinkage of the widened bundle. Finally, through thorough cleaning and heat treatment to finalize the shape, an ultrathin, highly oriented and uniform highly oriented ultrathin widened bundle of carbon nanotubes is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-carbon materials, and in particular to a highly oriented ultra-thin and widened carbon nanotube bundle, a preparation method and application thereof. Background Art

[0002] Carbon nanotubes, also known as buckytubes, are a unique one-dimensional quantum material with radial dimensions measured in nanometers and axial dimensions measured in micrometers. Both ends of the tube are essentially sealed. Carbon nanotubes are primarily composed of coaxial circular tubes with several to dozens of layers of carbon atoms arranged in a hexagonal pattern.

[0003] Due to the excellent mechanical strength, high electrical conductivity and high thermal conductivity of carbon nanotubes, a lot of research and development work has been done in the field. In particular, the compounding of carbon nanotubes with polymers such as resins to produce components has become a new breakthrough in the fields of aerospace, electronics, and automobiles.

[0004] Some existing technologies attempt to composite single carbon nanotubes or carbon nanotube films with resins. However, due to the small gaps between the carbon nanotubes, it is difficult to fully composite them and the high strength characteristics of the carbon nanotubes cannot be brought into play. Subsequently, some technical solutions proposed the technical idea of ​​fusing multiple carbon nanotubes to obtain fused bundles for application. After fusion, the multiple carbon nanotubes are entangled and combined with each other to form an overall combined force, which has made progress in mechanical properties and ease of processing.

[0005] However, the above technical solutions can only obtain fibrous materials with a certain diameter or strip materials with a certain thickness. The larger cross-sectional macroscopic size limits the contact area of ​​the carbon nanotube bundles in the composite material, resulting in unsatisfactory physical properties. In the field of materials science, people often hope that the substrate used for composites is as thin as possible. For example, when the thickness of hand-torn steel is thin to a certain extent, the physical properties of the components made therefrom will change significantly compared to thicker homogeneous components.

[0006] Therefore, how to obtain a highly oriented carbon nanotube bundle with ultra-thin properties is a topic that is very worthy of research. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention aims to provide a highly oriented, ultra-thin, and widened carbon nanotube bundle, a preparation method, and applications thereof.

[0008] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0009] In a first aspect, the present invention provides a method for preparing a highly oriented ultrathin extended carbon nanotube bundle, comprising:

[0010] Providing a plurality of stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles;

[0011] Mechanically pre-expanding the original carbon nanotube fibers to form pre-expanded bundles;

[0012] The pre-expanded bundle is brought into contact with a liquid expansion medium for expansion and expansion to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening process, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and the expanded fiber bundle is subjected to tension in an axial direction and elongated;

[0013] contacting the expanded and widened cluster with a deswelling liquid to perform a deswelling treatment to remove a portion of the liquid expansion medium, thereby obtaining a deswelled cluster;

[0014] The de-expanded cluster is cleaned and heat-treated to obtain a highly oriented ultra-thin expanded cluster of carbon nanotubes.

[0015] In a second aspect, the present invention further provides a device for preparing a highly oriented ultrathin extended carbon nanotube bundle, which is used to implement the above-mentioned preparation method, and comprises:

[0016] A pay-off device for providing a plurality of parallel stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles;

[0017] A pre-expansion device, used for mechanically pre-expanding the original carbon nanotube fibers to form a pre-expanded bundle;

[0018] an expansion and widening device for contacting the pre-widened bundle with a liquid expansion medium to perform an expansion and widening treatment to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening treatment, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and causes the expanded fiber bundle to be subjected to tension in an axial direction and to be elongated;

[0019] a de-expansion device for contacting the expanded and widened cluster with a de-expansion liquid to perform a de-expansion treatment, so as to remove part of the liquid expansion medium and obtain a de-expansion cluster;

[0020] a cleaning device for cleaning the de-expanded cluster;

[0021] a heat treatment device for heat-treating the cleaned and de-expanded bundle to obtain a highly oriented ultra-thin and widened carbon nanotube bundle;

[0022] And, a collecting device is used to collect the highly oriented ultra-thin and widened carbon nanotube bundles.

[0023] In the third aspect, the present invention also provides a highly oriented ultrathin widened carbon nanotube bundle obtained by the above-mentioned preparation method, wherein the highly oriented ultrathin widened carbon nanotube bundle is a bundle with a flat axial cross-section formed by combining multiple carbon nanotube bundles, and the carbon nanotube bundles are filled with polymers. The thickness of the highly oriented ultrathin widened carbon nanotube bundle is 500nm-10μm.

[0024] In a fourth aspect, the present invention further provides a further application of the above technical solution, namely, a carbon nanotube composite component, which is formed by at least stacking and combining the above-mentioned highly oriented ultrathin extended carbon nanotube bundles along the thickness direction.

[0025] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least:

[0026] The preparation method provided by the present invention utilizes a combination of preliminary mechanical pre-widening and secondary expansion and widening under the action of protonation expansion to achieve the preparation of highly oriented ultrathin widened bundles of carbon nanotubes. During the expansion and widening process, the filling, lubrication, bonding and tension adjustment effects of the high molecular polymer are utilized to avoid the problems of dispersion, cracking and shrinkage during the expansion and widening process. In addition, a secondary removal method is adopted when removing the liquid expansion medium to avoid the one-time removal of a large amount of liquid expansion medium and the obvious shrinkage of the bundle after widening. Finally, through thorough cleaning and heat treatment to shape, ultrathin, highly oriented and uniform highly oriented ultrathin widened bundles of carbon nanotubes are obtained. The highly oriented ultrathin widened bundles of carbon nanotubes perform excellently in the application of preparing composite materials.

[0027] The above description is only an overview of the technical solution of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of this application and implement them according to the contents of the specification, the following is an explanation of the preferred embodiments of the present invention with detailed drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a schematic diagram of the plan view of the structure of an apparatus for preparing highly oriented ultrathin and widened carbon nanotube bundles provided in a typical embodiment of the present invention;

[0029] Figure 2 This is a schematic top view of the structure of an apparatus for preparing highly oriented ultrathin and widened carbon nanotube bundles provided in a typical embodiment of the present invention;

[0030] Figure 3 This is a macroscopic morphology photograph of a highly oriented ultrathin and widened carbon nanotube bundle provided by a typical embodiment of the present invention;

[0031] Figure 4 This is an electron microscope photograph of a highly oriented ultrathin extended carbon nanotube bundle provided by another typical embodiment of the present invention;

[0032] Figure 5 This is a low-magnification electron microscope photograph of the cross-section and surface morphology of a highly oriented ultrathin extended carbon nanotube bundle provided in another typical embodiment of the present invention;

[0033] Figure 6 This is a high-magnification surface morphology electron microscope photograph of a highly oriented ultrathin extended carbon nanotube bundle provided in another typical embodiment of the present invention;

[0034] Figure 7 This is a mechanical properties test diagram of a highly oriented ultrathin extended carbon nanotube bundle provided by another typical embodiment of the present invention.

[0035] Description of reference numerals:

[0036] 1. Pay-off device; 2. Pre-widening device; 3. Active traction assembly; 4. Lower yarn spreading rod; 5. Upper yarn spreading rod; 6. Expansion widening device; 7. De-expansion device; 8. Cleaning device; 9. Environmental sealing assembly; 10. Heat treatment device; 11. Take-up device. DETAILED DESCRIPTION

[0037] There is no relevant research on ultra-thin stretching of carbon nanotube fibers in the current existing technology. As carbon materials, the stretching methods of carbon fibers include: hot stick method, mechanical stretching, ultrasonic stretching, air jet stretching, etc., but they are not suitable for the stretching preparation of carbon nanotubes. The current problems include: (1) The mechanical properties of carbon nanotube precursors directly prepared by the floating catalytic method are weak, and the existing carbon fiber stretching technology cannot be directly used for continuous stretching, and the stretching efficiency is low; (2) The structural controllability is poor, and the fiber cannot be stretched to ultra-thin thickness; (3) The tension during the stretching process is too high to destroy the carbon tube structure in the fiber, and the fiber loses its mechanical properties after stretching. performance; (4) The existing widening equipment cannot fuse the fibers after widening and they remain in a scattered state, which makes it impossible to achieve cross-scale performance transfer from macro to micro, resulting in poor overall performance; (5) Although the existing technology uses chlorosulfonic acid protonation expansion technology to achieve the fusion of multiple carbon nanotube fibers and the preparation of fiber bundles, the fiber cross-section is multi-dimensionally circular, elliptical or ribbon-shaped, which makes it difficult to achieve ultra-thinness. Once ultra-thin widening is achieved, the problem of interface interaction between tubes in the ultra-thinning process must be solved. Otherwise, due to the action of interfacial tension during the preparation process, it is easy to cause scattered fibers, cracks, wrinkles, shrinkage or stacking, resulting in failure of ultra-thin widening.

[0038] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0040] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component or method step from another with the same name, but do not necessarily require or imply any actual relationship or order between these components or method steps.

[0041] The present invention provides a method for preparing a highly oriented ultrathin extended carbon nanotube bundle, which comprises the following steps:

[0042] Providing a plurality of stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles;

[0043] Mechanically pre-expanding the original carbon nanotube fibers to form pre-expanded bundles;

[0044] The pre-expanded bundle is brought into contact with a liquid expansion medium for expansion and expansion to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening process, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and the expanded fiber bundle is subjected to tension in an axial direction and elongated;

[0045] contacting the expanded and widened cluster with a deswelling liquid to perform a deswelling treatment to remove a portion of the liquid expansion medium, thereby obtaining a deswelled cluster;

[0046] The de-expanded bundles are cleaned and heat-treated to obtain highly oriented ultra-thin and widened bundles of carbon nanotubes (hereinafter referred to as "bunches" or "ultra-thin bundles").

[0047] In order to achieve the above-mentioned objectives, the key technical points of the present invention are reflected in multiple aspects. The first is the combination of two widening methods. Through mechanical pre-widening, multiple strands of original carbon nanotube fibers are first spread relatively in the plane direction to avoid concentrated stacking, which provides a precondition for the subsequent expansion and widening to obtain a thin and uniform material; the second is to add a certain amount of polymer to the liquid expansion medium. The properties and appropriate concentration of the polymer itself can effectively regulate the interaction force and surface tension between the carbon nanotube bundles, as well as the viscosity of the liquid expansion medium, and can also prevent the liquid expansion medium from being removed from the expansion body too quickly during the de-expansion process. Under the action of multiple aspects, it can assist The spreading and shaping of the carbon nanotube bundles in the planar direction also play a connecting role to prevent dispersion or dissociation after spreading, which is very critical for forming a thin and uniform cross-sectional state. In addition, in the present invention, the method of removing the liquid expansion medium does not adopt a direct removal method at one time. Instead, a deswelling liquid with relatively mild dissolving properties is first used to remove a portion of the liquid expansion medium, and then a cleaning liquid is used to completely remove the liquid expansion medium, avoiding the shrinkage, wrinkling, stacking and other problems caused by the one-time removal of the liquid expansion medium. Ultimately, with the systematic coordination of various technical means, uniform, ultra-thin and highly oriented carbon nanotube highly oriented ultra-thin and widened bundles are successfully prepared.

[0048] From the perspective of mechanism, in the preparation method of the present invention, ultra-thin widening is achieved under the comprehensive effects of a series of factors, including the expansion force under super acid, the yarn spreading force, the stretching force, and the polymer viscosity force during the protonation expansion process; the yarn spreading force, the solvent evaporation interface shrinkage force, the in-plane and thickness direction shrinkage force, the stretching force, and the polymer anchoring force during the coagulation bath shrinkage process.

[0049] The team to which the inventor of the present invention belongs has proposed some technical solutions for protonation treatment, such as the Chinese invention patent "Carbon nanotube bundles, preparation methods and applications thereof" with publication number CN116905215 A, which proposes a technical idea of ​​using protonating agents such as chlorosulfonic acid as expansion media to achieve expansion and fusion of multiple fibers. However, in this technical idea, no attempt was made to obtain ultra-thin widened materials. Although the obtained material was roller-shaped, it was still a strip material with a considerable thickness and did not reach the ultra-thin state required by the present invention. In terms of technical means, it did not specifically set up secondary widening, polymer-assisted widening and secondary removal of expansion medium for the purpose of ultra-thin widening. Therefore, it is impossible to obtain the ultra-thin material provided by the present invention.

[0050] Regarding the specific technical details of the more critical process, in some embodiments, the liquid expansion medium includes any one of chlorosulfonic acid, methanesulfonic acid, and fuming sulfuric acid, or a combination of two or more thereof.

[0051] In some embodiments, the polymer includes any one or a combination of two or more of polyvinyl alcohol, polyacrylic acid, polystyrene, polyphenylene ether, phenolic resin, polyamide, and polyetheretherketone.

[0052] In some embodiments, the mass fraction of the polymer in the liquid expansion medium is 0.01-1%, typically 0.1-1%. Furthermore, the polymer is typically commercially available, with a molecular weight range of, but not limited to, 20,000-150,000. Due to the relatively low concentration of the polymer, the molecular weight of the polymer does not significantly affect the liquid viscosity. The molecular weight range can be appropriately expanded to achieve similar effects.

[0053] In order to improve the effect of the polymer, the present invention also proposes a more preferred method, that is, by constructing active groups on the surface of carbon nanotubes to improve the binding of the polymer to the surface of carbon nanotubes, thereby improving the effect of the polymer. Therefore, in some embodiments, the preparation method may further include the following steps:

[0054] Before the expansion and widening treatment is performed, the original carbon nanotube fibers are subjected to a pre-oxidation treatment so as to form oxygen-containing functional groups on the surface of the carbon nanotube bundles.

[0055] Specifically in some embodiments, the pre-oxidation treatment is performed by immersion oxidation, and the oxidant includes any one of concentrated sulfuric acid, concentrated nitric acid, and hydrogen peroxide, or a combination of any two compatible ones.

[0056] As for other process steps, in some embodiments, the mechanical pre-widening is performed by rolling and widening with a spreading roller, and the plurality of original carbon nanotube fibers in the pre-widened bundle are arranged in a row side by side.

[0057] In some embodiments, the expansion and widening treatment is carried out using multiple yarn spreading rods immersed in the liquid expansion medium, the expanded fiber bundle is wrapped around the yarn spreading rods and is subjected to pressure, the wrapping curvature diameter is 1-100 mm, the wrap angle of the expanded fiber bundle is 30-130°, and the drawing ratio is 1:(1.1-1.2).

[0058] In some embodiments, the deswelling treatment is performed by immersing in a deswelling liquid, wherein the deswelling liquid includes any one of chloroform, carbon tetrachloride, and nitrobenzene, or a combination of two or more thereof.

[0059] In some embodiments, the cleaning treatment is performed by immersing in a cleaning solution, wherein the cleaning solution includes any one of acetone, ethanol, N-methylpyrrolidone, and water, or a combination of two or more thereof.

[0060] In some embodiments, the heat treatment temperature is 100-550°C.

[0061] In some embodiments, during the de-expansion treatment, the cleaning treatment, and the heat treatment, a drafting roller is used to draw and simultaneously shape the spread state of the bundle.

[0062] Furthermore, in order to prevent moisture and oxygen in the air from adversely affecting the widening process, in some embodiments, the expansion and widening process, the de-expansion process, and the cleaning process are all performed in a protective atmosphere.

[0063] A second aspect of an embodiment of the present invention further provides an apparatus for preparing a highly oriented ultrathin extended carbon nanotube bundle, for implementing the preparation method provided in any of the above embodiments, comprising: sequentially arranging along a process direction (typically a linear direction, but not limited thereto):

[0064] A pay-off device for providing a plurality of parallel stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles;

[0065] A pre-expansion device, used for mechanically pre-expanding the original carbon nanotube fibers to form a pre-expanded bundle;

[0066] an expansion and widening device for contacting the pre-widened bundle with a liquid expansion medium (also referred to as an expansion liquid, or a protonating agent, etc. in some embodiments) to perform an expansion and widening treatment to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening treatment, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and causes the expanded fiber bundle to be subjected to tension in an axial direction and to elongate;

[0067] a de-expansion device for contacting the expanded and widened cluster with a de-expansion liquid to perform a de-expansion treatment, thereby removing a portion of the liquid expansion medium to obtain a de-expansion cluster;

[0068] a cleaning device for cleaning the de-expanded cluster;

[0069] a heat treatment device for heat-treating the cleaned and de-expanded bundle to obtain a highly oriented ultra-thin and widened carbon nanotube bundle;

[0070] And, a collecting device is used to collect the highly oriented ultra-thin and widened carbon nanotube bundles.

[0071] The third aspect of an embodiment of the present invention also provides a highly oriented ultrathin widened bundle of carbon nanotubes obtained by the above-mentioned preparation method, wherein the highly oriented ultrathin widened bundle of carbon nanotubes is a bundle with a flat axial cross-section formed by combining multiple carbon nanotube bundles, and the carbon nanotube bundles are filled with polymers. The thickness of the highly oriented ultrathin widened bundle of carbon nanotubes is 500nm-10μm.

[0072] As some typical application examples of the above-mentioned technical solutions, specific embodiments of the present invention disclose a highly oriented, ultrathin, and widened carbon nanotube fiber, as well as a preparation method and equipment thereof. The preparation method comprises: pre-oxidizing the carbon nanotube fiber tow, performing preliminary widening in a pre-widening device, then uniformly compounding, thinning the tow in an expansion solution with a yarn spreading rod, fusing the tow, and drawing and orienting the fiber, thereby thinning the fiber while improving its mechanical properties. Then, under continuous support, the fiber is subjected to a de-swelling solution, a cleaning solution, and a high-temperature heat treatment annealing process, in which the residual protonated solution in the fiber is gradually removed in stages to achieve densification and shaping, ultimately converting the fiber into a highly oriented, ultrathin, and widened carbon nanotube ribbon.

[0073] The pre-oxidation treatment involves immersing the carbon nanotube fiber bundle in an oxidant to graft functional groups onto the carbon nanotube surface, increasing the bonding strength between the carbon nanotubes and the resin, thereby improving the mechanical properties of the fiber. The swelling solution consists of a small amount of polymer dissolved in a protonated solvent. The loose structure of the carbon nanotubes after swelling in the protonated solvent is utilized to achieve uniform bonding between the carbon nanotubes and the resin. The polymer can fill the spaces between the tubes, reducing the inter-tube porosity, improving axial slippage, and increasing the density of the fiber orientation. It can also effectively improve the radial composite strength (adhesion) of the carbon nanotube interface, greatly reducing the occurrence of loose fibers (cracks) between the fiber bundles during fiber widening and structural densification and shrinkage, thereby improving the fiber's integration and mechanical properties. It also plays a shaping role in subsequent processes, preventing shrinkage, wrinkling, or stacking. The staged deswelling agent avoids the same shrinkage, wrinkling, or stacking problems caused by removing too much swelling medium at one time. The high-temperature annealing removes the temporarily retained protonated solvent while cross-linking or curing the polymer on the carbon nanotube surface, improving the mechanical properties.

[0074] At the same time, the present invention also provides corresponding preparation equipment, such as Figure 1 and 2 As shown, it includes: a pay-off device 1, a pre-widening device 2, an active traction component 3, a lower yarn spreading rod 4, an upper yarn spreading rod 5, an expansion widening device 6, a de-expansion device 7, a cleaning device 8, an environmental sealing component 9, a heat treatment device 10, a take-up device 11, etc. The shape and size of the lower yarn spreading rod 4 and the upper yarn spreading rod 5 are controlled to adjust the wrap angle and the surrounding diameter of the carbon nanotube fiber bundle, thereby forming tension in different directions, and the yarn spreading between multiple carbon nanotube fibers in the bundle is realized in the pre-yarn spreading stage, and the yarn spreading between multiple carbon nanotubes in the fiber is realized in the carbon nanotube protonation expansion stage, and finally the nano-scale ultra-thin extreme widening and stretching orientation enhancement mechanical properties of the fiber are achieved; the upper and lower traction rollers (belonging to the active traction component 3) closely connected in the de-expansion device 7, the cleaning device 8, and the heat treatment device 10 are used to prevent the fiber from curling and curling in the direction perpendicular to the fiber surface due to the support force during the solvent exchange and solvent volatilization densification process, and maintain a thin surface state on a macro scale. At the same time, the traction shaft reduces the friction between the fiber and the roller during the removal of the protonated reagent; the dry inert gas atmosphere provided by the environmental sealing component 9 reduces the moisture in the environment during the ultra-thin widening process, thereby reducing the surface defects of the fiber.

[0075] In a more specific example, the structure of the device is composed of:

[0076] Pay-off device 1: The pay-off end of the component can be one or more, and the pay-off rate of all single yarns is controlled to be V1, and the pay-off rate range is 0.01-100 m / h; Pre-widening device 2: Performs primary widening on the yarn bundle to increase the widening efficiency of the yarn bundle. The shape of the pre-widening yarn shaft can be cylindrical or polygonal, the widening surface can be flat or convex, and the rotating shaft can actively feed the wire, passively feed the wire, or not feed the wire; Active traction component 3: Actively pulls the yarn bundle to ensure that the force at each position of the yarn bundle is uniform during the entire processing process and reduce the friction between the yarn bundle and the traction roller; Lower yarn spreading rod 4: Introduces the yarn bundle into the solution tank. The shape of the lower yarn spreading rod 4 can be cylindrical or polygonal, the widening surface can be flat or convex, the rotating shaft can actively feed the wire, passively feed the wire, or not feed the wire, and the lower traction equivalent circle diameter range is 1-100 mm, typically 10-50 mm. Upper spreading rod 5: Applying a force perpendicular to the traction axis within the solution to the filaments, further widening the tow. The vertical distance and spacing between upper and lower spreading rods 4 and 5 are controllable, allowing for an adjustable wrap angle of 0°-180° (greater than 0°), with a typical wrap angle range of 30°-130°. Expansion and widening device 6: Expands and uniformly composites the tow fibers within the solution, providing a foundation for further widening and stretching. The expansion tank can be made of one or more materials, such as quartz, polytetrafluoroethylene, or other materials coated with quartz or polytetrafluoroethylene. The solute in the modified expansion solution can be one or more resins soluble in chlorosulfonic acid, such as polyvinyl alcohol, polyacrylic acid, polystyrene, polyphenylene oxide, phenolic resin, polyamide, and polyetheretherketone. The solvent can be one or more of chlorosulfonic acid, methanesulfonic acid, and fuming sulfuric acid. De-expansion device 7 eliminates the expansion effect of the tow within the expansion tank. The de-expansion tank can be made of one or more materials such as quartz, polytetrafluoroethylene, or other materials coated with quartz or polytetrafluoroethylene. The de-expansion solution can be one or more solvents that are miscible but non-reactive with chlorosulfonic acid, such as chloroform, carbon tetrachloride, and nitrobenzene. However, it cannot be a liquid medium with high affinity and reactivity with chlorosulfonic acid or other expansion media in the subsequent cleaning tank to prevent curling caused by removing too much of the expansion media at once. Cleaning device 8 further removes residual expansion solution and de-expansion solution from the tow. The de-expansion tank can be made of one or more materials such as quartz, polytetrafluoroethylene, or other materials coated with quartz or polytetrafluoroethylene. The deswelling solution can be one or more of acetone, ethanol, N-methylpyrrolidone, and water. Environmental sealing assembly 9 provides a water-free environment for the entire experimental process. The sealing device is made of any material that does not react with the vapors of the expansion solution, deswelling solution, and cleaning solution, such as quartz or polytetrafluoroethylene.A dry inert gas, such as one or more of nitrogen and argon, is continuously introduced into the sealing device; a heat treatment device 10 completely removes the liquid residue in the stretched filament bundle and cross-links the resin on the surface of the carbon nanotubes in the filament bundle to obtain a high-performance ultra-thin stretched fiber with stable structure, and the annealing temperature range is 100-550°C; a take-up device 11: a stretched filament bundle collection end, collects the obtained stretched filament bundle, and provides a drawing force during the treatment process, and the collection speed V2 ranges from 0.01-100 m / h, wherein V1 is less than V2 (the specific ratio is set according to the drawing ratio), so that the carbon nanotube fiber is stretched after protonation expansion to achieve high orientation.

[0077] The thickness of the obtained highly oriented ultra-thin extended carbon nanotube bundles is generally less than 5 μm (may exceed this range depending on the process conditions), the tensile strength is generally greater than 6 GPa, and the electrical conductivity is generally greater than 1.5 MS.m -1 , thermal conductivity is generally greater than 250 Wm -1 .K -1 .

[0078] The present invention controls the shape and size of the yarn-unwinding rollers through the modification and uniform compounding of a small amount of polymer between tubes, and the upper and lower traction rollers tightly connected in the cleaning tank and annealing assembly greatly realize the ultra-thin extreme widening of the carbon nanotube fibers, and the process is stable throughout the entire process. This method can continuously and synchronously realize the expansion compounding, stretching orientation, ultra-thin widening, tow fusion, densification and cross-linking of the carbon nanotube fibers, which is conducive to the large-scale preparation of multifunctional carbon nanotube fibers. The prepared highly oriented carbon nanotube fibers have the advantages of uniform thickness, breaking through the thickness limit of carbon fibers, excellent mechanical, electrical, thermal and other properties, continuous preparation and adjustable thickness.

[0079] The specific advantages are:

[0080] (1) Pretreatment with a modifier improves the bonding strength between carbon nanotubes and resins. Of course, in some implementation schemes, when the selected resin and carbon nanotubes themselves have certain affinity properties, pre-oxidation modification is also allowed, depending on the specific circumstances; (2) A small amount of resin or other polymer is added to the liquid expansion medium, and the carbon nanotubes in the carbon nanotube fiber bundle are expanded and rearranged to achieve uniform compounding of carbon nanotubes and polymers. At the same time, the addition of polymers is mainly to change the inter-tube interaction, interface properties and viscosity characteristics, etc., which is a key condition for achieving ultra-thin widening. Its concentration needs to be controlled in a relatively thin range, which is obviously different from the commonly used concentration range of traditional carbon nanotube-polymer swelling composites; (3) After the modified bundles are pre-spun, de-expanded and cleaned, they are uniformly compounded, ultra-thinly widened, highly oriented, fused and densified in an annealing device and then collected. The treatment process is continuous and highly controllable; (4) The entire treatment process is carried out in a dry inert gas environment to avoid water vapor and other factors affecting the bundle structure. (5) Through the adjustment of the processing technology, the thinnest nanometer-scale stretched fibers can be obtained, and usually bundles of several micrometers in thickness can be easily obtained, which far exceeds the thickness limit of carbon fiber and previous carbon nanotube bundle materials; (6) After ultra-thin stretching, the carbon nanotube bundles are highly oriented and fused to form a thin layer of ribbon-like carbon nanotube fiber structure. After further rearrangement and optimization, the fiber has excellent mechanical, electrical and thermal properties, and the homogeneity and bonding properties when used to prepare composite materials are very excellent, which is significantly stronger than other carbon nanotube materials with thicker radial dimensions (such as carbon fibers, carbon nanotube fibers, carbon nanotube films, carbon nanotube narrow strips, etc. with larger cross-sectional dimensions, which often require pre-impregnation winding or pre-impregnation lamination when resin composites are carried out. The fiber phase and the resin phase are macroscopically separated and cannot produce a combination close to homogenization. For ultra-thin materials, they will produce an extremely large contact area when used in the preparation of composite materials. The cross-section after bonding produces a similar homogeneous effect, and the mechanical strength, thermal conductivity and electrical conductivity will be significantly improved).

[0081] In addition, as an application of the above technical solution, the fourth aspect of the embodiment of the present invention also provides a carbon nanotube composite component, which is formed by stacking and combining the highly oriented ultra-thin widened carbon nanotube bundles provided by at least the above embodiment along the thickness direction.

[0082] The technical solution of the present invention is further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0083] Example 1

[0084] A roll of carbon nanotube fiber tow was soaked in a modifier for 24 hours to graft oxygen-containing functional groups on the surface of the carbon nanotubes to increase the bonding strength between the carbon nanotubes and the resin. The modifier was hydrogen peroxide. The carbon nanotube fiber tow was taken out and treated in a vacuum oven at 150°C for 1 hour to remove the modifier.

[0085] In a fume hood, a small amount of polyvinyl alcohol was dissolved in chlorosulfonic acid to prepare a modified swelling solution with a polyvinyl alcohol content of 0.5%.

[0086] The environmental sealing device is opened, and a roll of pre-treated carbon nanotube fiber tow is fixed on the pay-off device. The tow end passes through the pre-spinning assembly, active traction assembly, expansion tank, de-expansion tank, cleaning tank, and annealing device, and is then fixed on the empty reel of the collection device.

[0087] Select the shape and size of the pre-spreading yarn, upper and lower yarn spreading rods, and traction shaft according to the following parameters, and adjust them to the desired position so that the fiber wrapping meets the set wrap angle;

[0088] After adding acetone cleaning solution, carbon tetrachloride deswelling solution and modified swelling solution into the solution tank, the environmental sealing device is closed;

[0089] Dry inert gas is introduced from the top of the environmental seal and exhausted from the outlets at both ends. The gas needs to be introduced for a period of time (5 minutes in this example) to completely expel the moist air within the seal. The gas flow rate is 5 SLM to ensure that there is no significant moisture in the environment.

[0090] Open the annealing furnace and heat it to the target temperature of 300°C;

[0091] Set the traction speed of the pay-off device, collecting device and all active traction wheels according to the following parameters;

[0092] At the same time, the unwinding device, the collecting device and all active traction device switches are turned on to carry out the widening process of the carbon nanotube fiber bundle.

[0093] Specifically, this embodiment uses 100 strands of carbon nanotube fiber bundles. During pre-widening, the parameters are adjusted so that the 100 strands of fibers are basically close to being arranged in a row. The yarn spreading rod, the upper and lower yarn spreading rods, and the traction shaft are all cylindrical plane shafts with a diameter of 50 mm. The yarn spreading rod is guided by active traction and adjusted to the expected position so that the wrap angle is 130°, the collection speed is 60 m / h, and V2:V1=1.1:1 (that is, the collection speed of the collection device is 60 m / h, the pay-off speed of the pay-off device is 54.55 m / h, the active traction speed before entering the expansion solution is equal to the pay-off speed, and the active traction speed after entering the expansion solution is equal to the collection speed). After widening, the width of the fiber bundle is 3 mm, the bundle thickness is 10 μm, and the finished product is shown in the photo. Figure 3 shown.

[0094] Example 2

[0095] This example is generally similar to Example 1, differing primarily in parameters. 100 carbon nanotube fiber tows are used (the number of tows can be varied, depending on the specific width requirements, typically between 5 and 500, but not limited thereto). The polymer is polyetheretherketone (PEEK), added at a 1% concentration. The cleaning fluid is ethanol, and the deswelling fluid is nitrobenzene. The yarn spreading rod is a cylindrical flat shaft with a diameter of 30 mm. Active pulling is used, with a wrap angle of 110°. The collection speed is 50 m / h, and the V2:V1 ratio is 1.1:1. After spreading, the fiber tow has a thickness of 8 μm and a width of 3.75 mm.

[0096] Example 3

[0097] This example is generally similar to Example 1, differing primarily in parameters. 100 carbon nanotube fiber strands were used. The polymer was polyamide, with an additive amount of 0.1%. Water was the cleaning fluid, and chloroform was the deswelling fluid. The spreading rod was a cylindrical flat shaft with a diameter of 30 mm. The spreading rod employed active pulling, a wrap angle of 60°, a collection speed of 40 m / h, and a V2:V1 ratio of 1.16:1. After spreading, the fiber strands had a thickness of 2 μm and a width of 15 mm.

[0098] Example 4

[0099] This example is substantially the same as Example 1, with the main difference being some parameters. 100 strands of carbon nanotube fiber tow were used, the spreading rod was a convex plate with a thickness of 1 cm, the spreading rod employed a non-active rotational traction method, the wrap angle was 30°, the collection speed was 10 m / h, and V2:V1 = 1.2:1. The stretched fiber tow had a thickness of 500 nm and a width of 60 mm, and its cross-sectional morphology was as follows: Figure 4 As shown, it can be seen that its thickness has reached the level of hundreds of nanometers, and in such an ultra-thin state, its cross-sectional thickness is very uniform, and the distribution of carbon nanotubes is also very uniform. Figure 4 The cross-sectional morphology shown in the figure is magnified at a high magnification, or as shown in the figure Figure 5 The low-magnification cross-section shown in the figure shows no unevenness such as particles, agglomerates, cracks, or depressions. Figure 6 From the surface morphology of the bundle shown, it can be seen that the carbon nanotubes are clearly oriented along the axial direction, and except for some burr areas on the surface, the distribution of the carbon nanotubes is very dense.

[0100] The mechanical properties of the ultra-thin stretched cluster were tested, and the tensile curve was as follows: Figure 7As shown, it can reach a level of 6.6GPa, which is a relatively high-strength fiber bundle material; however, the mechanical properties of the bundle provided by the present invention are not only reflected in the strength of a single bundle itself, but also in the composite strength after compounding, which is related to the composite performance under ultra-thin size shown above. For details, please refer to the control experiment below.

[0101] Application Examples

[0102] This application example uses the composite material of the ultrathin carbon nanotube bundles provided in Example 4 to prepare the laminated body by adopting a bundle-resin layer-bundle cyclic lamination method. The resin layer material is bismaleimide resin to obtain a multilayer composite material.

[0103] The mechanical strength of the multilayer composite material was measured, and its tensile strength was 6 GPa, which was only slightly lower than that of a single ultra-thin carbon nanotube bundle.

[0104] As a comparison, this application example also provides a high-strength carbon nanotube fiber (also with a strength of approximately 6.6 GPa) used in previous research and development processes, which was pre-impregnated and wound with the same resin. The two had the same mass ratio and the same hot pressing conditions. The strength of the final composite material was 5 GPa, which showed a significant decrease.

[0105] Analysis shows that after the carbon nanotube fiber is widened to an ultra-thin state, it has a larger specific surface area, and the probability of resin penetrating into the narrow carbon nanotube band increases, increasing the interface composite strength between the resin and the fiber. At the same time, its surface density is small, its weight is light, and its weight-to-weight ratio is high. Compared with traditional carbon fiber composite materials, the resin content of the prepared composite material can be lower, and the composite material with the same composite ratio has higher strength and higher mechanical retention rate.

[0106] In addition, a high-strength narrow-band bundle provided in previous research was also used (specific reference is made to the previous research of the present invention: the high-strength narrow-band bundle prepared by the method shown in Example 1 of the Chinese invention patent "Carbon Nanotube Bundles, Preparation Methods and Applications thereof" with publication number CN116905215 A, and samples with higher mechanical strength were selected from multiple batches, with a tensile strength of approximately 6 GPa). The thickness of the narrow-band bundle is greater than 50 μm. Under the same conditions, a composite material is prepared with a strength of 4.8 GPa, which is significantly lower than the strength of the carbon nanotube bundle itself.

[0107] Comparative Example 1

[0108] This comparative example is substantially the same as Example 4, except that:

[0109] The pre-widening process is eliminated, and the 100 strands of fiber bundled together are directly introduced into the expansion and widening device.

[0110] Finally, due to the lack of pre-widening, multiple strands of fibers are physically stacked, and ultra-thin bundles cannot be obtained by relying solely on expansion and widening. The obtained product is similar to the plastic multiple strands of fused fibers or strips in the previous inventions.

[0111] Comparative Example 2

[0112] This comparative example is substantially the same as Example 4, except that:

[0113] No polymer was added to the liquid expansion medium.

[0114] Finally, during the de-expansion process, the expanded body shrank significantly, resulting in a significant increase in the thickness of the product. At the same time, in the expansion and widening device, the expanded body was also very easy to bifurcate and detach, making it impossible to prepare ultra-thin bundles. Obviously, the bonding, interface modification and viscosity control of the polymer are very critical in the preparation of ultra-thin bundles.

[0115] Comparative Example 3

[0116] This comparative example is substantially the same as Example 4, except that:

[0117] Multiple tests were conducted with the addition ratio of polymer being 3%, 5%, and 10%.

[0118] It was found that in the expansion and widening device, the expansion body was obviously unable to fully spread in the width direction and encountered obvious widening resistance. The higher the polymer ratio, the more obvious this problem was, and ultimately only relatively thick narrow strips could be obtained.

[0119] The main function of the polymer is to regulate the interfacial force, provide cohesive force and viscosity, and solve problems such as widening and dispersion during the shrinkage process of the coagulation bath. However, its content should be controlled within a low range, otherwise it will easily lead to the inability to widen to an ultra-thin state.

[0120] Comparative Example 4

[0121] This comparative example is substantially the same as Example 4, except that:

[0122] The de-expansion process is eliminated, and the expanded body directly enters the cleaning device after coming out of the expansion and widening device.

[0123] Finally, due to the rapid adsorption and removal rate of the liquid expansion medium by the cleaning liquid, the expansion body loses its expansion effect before it is shaped. Therefore, a very obvious shrinkage and stacking phenomenon will occur in the cleaning device, and ultimately an ultra-thin cluster cannot be obtained.

[0124] This shows that the removal of the liquid expansion medium is divided into two removal processes, inducing the fibers to gradually shrink and expand, achieving a slow and steady-state shrinkage process, and avoiding the excessive removal of the liquid expansion medium, which is crucial for achieving an ultra-thin and dense network structure.

[0125] Based on the above embodiments and comparative examples, it can be clearly seen that:

[0126] (1) The embodiments of the present invention provide a solution for preparing ultra-thin bundles, which can continuously and synchronously achieve the effects of high orientation, ultra-thin widening, bundle fusion, densification, and cross-linking of carbon nanotube fibers, which is conducive to the large-scale preparation of multifunctional carbon nanotube bundles. The thickness is uniform, breaking through the thickness limit of carbon fiber, and has excellent mechanical, electrical, and thermal properties. It can be prepared continuously and the thickness is adjustable.

[0127] (2) The embodiments of the present invention modify the carbon nanotube fiber bundle and the expansion solution respectively, and achieve uniform compounding of the resin when the carbon nanotube fibers are in a loose state of expansion, thereby improving the uniformity and integrity of the ultra-thin extreme widening of the carbon nanotube fiber bundle;

[0128] (3) The embodiments of the present invention provide yarn spreading rods of different shapes and sizes, which form different wrap angles on the carbon nanotube tow to generate different tensions in the perpendicular fiber direction, realize preliminary yarn spreading between multiple fibers in the tow in the pre-yarn spreading part, and utilize the plasticity of the loose structure of the expanded carbon nanotube fibers in the expansion tank to realize yarn spreading between multiple carbon nanotubes in the carbon nanotube fibers. Multi-stage yarn spreading can achieve ultra-thin extreme widening of the carbon nanotube fiber tow;

[0129] (4) The embodiment of the present invention introduces adjacent continuous active stretching components during the de-expansion, cleaning and annealing steps, while avoiding the removal of a large amount of liquid expansion medium at one time, thereby reducing the shrinkage of the thin-layered carbon nanotube fibers on the vertical fiber surface during the densification process such as solvent exchange and solvent volatilization, maintaining the thickness and width of the carbon nanotube fibers in the expansion tank, and improving the uniformity of the ultra-thin widened carbon nanotube fibers.

[0130] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A method for preparing a highly oriented ultrathin extended carbon nanotube bundle, characterized in that: include: Providing a plurality of stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles; Mechanically pre-expanding the original carbon nanotube fibers to form pre-expanded bundles; The pre-expanded bundle is brought into contact with a liquid expansion medium for expansion and expansion to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening process, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and the expanded fiber bundle is subjected to tension in an axial direction and elongated; contacting the expanded and widened cluster with a deswelling liquid to perform a deswelling treatment to remove a portion of the liquid expansion medium, thereby obtaining a deswelled cluster; The de-expanded cluster is cleaned and heat-treated to obtain a highly oriented ultra-thin expanded cluster of carbon nanotubes.

2. The preparation method according to claim 1, characterized in that The liquid expansion medium includes any one of chlorosulfonic acid, methanesulfonic acid, and fuming sulfuric acid, or a combination of two or more thereof; And / or, the polymer includes any one or a combination of two or more of polyvinyl alcohol, polyacrylic acid, polystyrene, polyphenylene ether, phenolic resin, polyamide, and polyetheretherketone; And / or, the mass fraction of the polymer in the liquid expansion medium is 0.01-1%.

3. The preparation method according to claim 1, characterized in that Also includes: Before the expansion and widening treatment is performed, the original carbon nanotube fibers are subjected to a pre-oxidation treatment so as to form oxygen-containing functional groups on the surface of the carbon nanotube bundles.

4. The preparation method according to claim 3, characterized in that The pre-oxidation treatment is carried out by immersion oxidation, and the oxidant includes any one of concentrated sulfuric acid, concentrated nitric acid, and hydrogen peroxide, or a combination of any two compatible ones.

5. The preparation method according to claim 1, characterized in that The mechanical pre-widening is performed by rolling and widening with a spreading roller, and the plurality of original carbon nanotube fibers in the pre-widened bundle are arranged in a row and in parallel.

6. The preparation method according to claim 1, characterized in that The expansion and widening treatment is carried out using multiple yarn spreading rods immersed in the liquid expansion medium. The expanded fiber bundle is wrapped around the yarn spreading rods and is subjected to pressure. The wrapping curvature diameter is 1-100 mm, the wrapping angle of the expanded fiber bundle is 30-130°, and the drafting ratio is 1:(1.1-1.2).

7. The preparation method according to claim 1, characterized in that The deswelling treatment is carried out by immersing in a deswelling liquid, wherein the deswelling liquid includes any one of chloroform, carbon tetrachloride, and nitrobenzene, or a combination of two or more thereof; And / or, the cleaning treatment is performed by immersing in a cleaning solution, wherein the cleaning solution comprises any one of acetone, ethanol, N-methylpyrrolidone, and water, or a combination of two or more thereof; And / or, the temperature of the heat treatment is 100-550°C; And / or, the expansion and widening process, the de-expansion process and the cleaning process are all carried out in a protective atmosphere; And / or, during the de-expansion treatment, the cleaning treatment and the heat treatment, a drafting roller is used to draw and simultaneously shape the spread state of the cluster.

8. A device for preparing highly oriented ultrathin and widened carbon nanotube bundles, for implementing the preparation method according to any one of claims 1 to 7, characterized in that: Including the following arranged in sequence along the process direction: A pay-off device for providing a plurality of parallel stranded original carbon nanotube fibers, wherein the original carbon nanotube fibers contain a plurality of carbon nanotube bundles; A pre-expansion device, used for mechanically pre-expanding the original carbon nanotube fibers to form a pre-expanded bundle; an expansion and widening device for contacting the pre-widened bundle with a liquid expansion medium to perform an expansion and widening treatment to form an expanded and widened bundle; a polymer is dissolved in the liquid expansion medium, and during the expansion and widening treatment, the plurality of carbon nanotube bundles repel and expand each other, the polymer enters between the plurality of carbon nanotube bundles and adheres to the surfaces of the carbon nanotube bundles, and simultaneously causes the expanded fiber bundle composed of the plurality of carbon nanotube bundles to be subjected to pressure in a first radial direction and to spread and widen in a second radial direction, the first radial direction and the second radial direction intersecting, and causes the expanded fiber bundle to be subjected to tension in an axial direction and to be elongated; a de-expansion device for contacting the expanded and widened cluster with a de-expansion liquid to perform a de-expansion treatment, thereby removing a portion of the liquid expansion medium to obtain a de-expansion cluster; a cleaning device for cleaning the de-expanded cluster; a heat treatment device for heat-treating the cleaned and de-expanded bundle to obtain a highly oriented ultra-thin and widened carbon nanotube bundle; And, a collecting device is used to collect the highly oriented ultra-thin and widened carbon nanotube bundles.

9. The highly oriented ultrathin extended carbon nanotube bundle prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The highly oriented ultrathin and widened carbon nanotube bundle is a bundle with a flat axial cross section formed by combining multiple carbon nanotube bundles. Polymer is filled between the carbon nanotube bundles. The thickness of the highly oriented ultrathin and widened carbon nanotube bundle is 500nm-10μm.

10. A carbon nanotube composite component, characterized in that: The carbon nanotube composite component is formed by stacking and combining at least the highly oriented ultrathin extended carbon nanotube bundles according to claim 9 along the thickness direction.

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