CN116876196A - Drawing enhancement method and system for carbon nanotube fibers - Google Patents

Abstract

The invention discloses a method and system for drawing and reinforcing carbon nanotube fibers. The drafting enhancement method includes: providing carbon nanotube fibers, which are in a twisted state; performing plying treatment on the carbon nanotube fibers to obtain fiber bundles; performing protonation drafting and coagulation bath treatment on the fiber bundles to obtain Precursor fiber; remove the protonation reagent and/or coagulation bath reagent in the precursor fiber to obtain carbon nanotube reinforced fiber. The drafting enhancement method provided by the invention performs twisting and plying. After the fiber bundle is protonated and expanded by strong acid, the edge shape of each expanded fiber inside produces an adaptive effect; during the drafting process, the stress is applied more uniformly on the fiber bundle. On each fiber, the stability during the fiber drafting process is improved, thereby achieving higher drafting speed and drafting ratio, which ultimately significantly improves the mechanical strength and consistency of the reinforced fibers and brings very excellent continuous properties, which is very conducive to the application of carbon nanotube fibers.

Description

Drawing enhancement method and system for carbon nanotube fibers

Technical field

The present invention relates to the technical field of inorganic carbon materials or high-performance fibers, and in particular to a drafting reinforcement method and system for carbon nanotube fibers.

Background technique

Carbon nanotube fiber (CNTF) is a fibrous material composed of a large number of carbon nanotubes orderly assembled. Its component unit carbon nanotube itself has very excellent mechanical properties. Its tensile breaking strength and tensile modulus can respectively reach 100GPa and above 1000GPa. However, the fibrous macroscopic body of carbon nanotubes is difficult to overcome the influence of a series of factors such as structural defects during the preparation and assembly process, which ultimately makes the mechanical properties of carbon nanotube fibers far lower than the molecular-level carbon nanotubes themselves.

For example, the currently commonly used floating catalytic method produces carbon nanotube fibers with low cost and high productivity. However, the fibers produced have the characteristics of low density, poor internal structure orientation, and high impurity content, which affect the final strength of the fiber.

Subsequent drafting treatment of carbon nanotube fiber precursors is currently one of the more effective methods of fiber mechanical enhancement. By applying appropriate drafting to the fiber, the orientation and density of the internal structure of the fiber can be controlled to achieve mechanical enhancement of the carbon nanotube fiber.

Some existing technologies, such as the Chinese invention patent with publication number CN112359441A, use the heat generated by electric current to heat up and soften the polymer into a highly elastic state, and reorient and densify the carbon nanotube/polymer composite fiber through drafting.

In addition, some other existing technologies can expand the carbon nanotube fibers through the protonation of strong acid and weaken the internal inter-tube force, thereby achieving effective drafting enhancement (for example, Jaegeun Lee, st al., Nature Communications, 2019 , 10 2962, and the Chinese invention patent with publication number CN114672899A) based on strong acid assistance to achieve continuous post-processing reinforcement of fibers.

However, on the one hand, the mechanical strength of the fibers processed by the current drafting reinforcement method is still insufficient. On the other hand, the differences between the multiple reinforced fibers are very obvious and the consistency is poor, which greatly limits the carbon nanotube fiber. applications of this high-performance fiber.

Moreover, the current technical solutions often cannot achieve long continuity during fiber drafting and are prone to fiber breakage, which also greatly increases the cost of fiber preparation and reduces production efficiency.

Contents of the invention

In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a drafting reinforcement method and system for carbon nanotube fibers.

In order to achieve the foregoing invention objectives, the technical solutions adopted by the present invention include:

In a first aspect, the present invention provides a method for drawing and reinforcing carbon nanotube fibers, which includes:

Provide carbon nanotube fibers, the carbon nanotube fibers being in a twisted state;

Perform plying treatment on the carbon nanotube fibers to obtain fiber bundles;

The fiber bundle is subjected to protonation drawing and coagulation bath treatment to obtain precursor fibers;

The protonation reagent and/or coagulation bath reagent in the precursor fiber is removed to obtain carbon nanotube reinforced fiber.

In a second aspect, the present invention also provides a drafting enhancement system for carbon nanotube fibers, which includes:

The plying module is used to ply carbon nanotube fibers to obtain fiber bundles, and the carbon nanotube fibers are in a twisted state;

A drafting module, used to perform protonation drafting and coagulation bath treatment on the fiber bundle to obtain precursor fibers;

A post-processing module is used to remove protonation reagents and/or coagulation bath reagents in the precursor fiber to obtain carbon nanotube reinforced fibers.

Based on the above technical solution, compared with the existing technology, the beneficial effects of the present invention at least include:

The drafting enhancement method provided by the invention twists and plies the carbon nanotube fibers, and performs strong acid-assisted drafting on the plied fiber bundles. After the fiber bundles are protonated and expanded by strong acid, the edge shapes of each expanded fiber inside are generated. With the adaptive effect, the gaps between the plying fibers are filled, and the effective contact between fibers is increased; during the drafting process, the effective contact between fibers can transfer the drafting stress to each other, so that the stress is more uniformly applied to each fiber. on, thereby greatly improving the stability of the fiber drafting process, thereby achieving higher drafting speed and drafting ratio, ultimately significantly improving the mechanical strength and consistency of the reinforced fiber, and bringing very excellent continuity , which is very beneficial to the application of carbon nanotube fibers.

In addition, the method provided by the present invention also brings a very significant advantage in preparation efficiency. This advantage is not only an increase in the number of batch processes brought about by the simultaneous drafting of multiple fibers, but also due to the extremely high continuous brought about by sex.

The above description is only an overview of the technical solutions of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement them in accordance with the contents of the description, the following is a detailed description of the preferred embodiments of the present invention. The description of the drawings is as follows.

Description of the drawings

Figure 1 is a schematic process diagram of a draft enhancement method provided by a typical implementation case of the present invention;

Figure 2a is a test diagram showing the relationship between the mechanical properties of carbon nanotube original fibers at different first twist angles provided by a typical implementation case of the present invention;

Figure 2b is a microscopic test photo of the original carbon nanotube fiber at different first twist angles provided in a typical implementation case of the present invention;

Figure 3 is a surface electron microscope photo of the carbon nanotube reinforced fiber provided in a typical comparative example of the present invention;

Figure 4 is a surface electron microscope photo of the carbon nanotube reinforced fiber provided in a typical implementation case of the present invention;

Figure 5 is a comparative test chart of the mechanical properties and consistency of carbon nanotube-reinforced fibers provided by a typical implementation case and a comparative case of the present invention.

Detailed ways

In view of the deficiencies in the prior art, the inventor of this case was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principles will be further explained below.

Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not limited to the specific implementation disclosed below. Example limitations.

Furthermore, relative terms such as "first" and "second" are merely used to distinguish one component or method step from another with the same name and do not necessarily require or imply that such components or method steps are mutually exclusive. any such actual relationship or sequence exists between them.

Currently, the existing methods for drawing and reinforcing carbon nanotube fibers have the following shortcomings:

(1) Most of the existing enhancement methods have low processing efficiency, and the single processing length is short, about 10-20cm, making it impossible to achieve batch processing enhancement.

(2) Some continuous drafting enhancement methods have poor continuity, especially for strong acid-assisted drafting processes. Under the protonation effect of strong acid, the distance between the internal tubes of the fiber increases, the van der Waals force weakens, and the entire fiber basically loses its original mechanical strength. Although the above-mentioned protonation can achieve a higher drafting rate of carbon nanotube fibers, it also weakens the fiber's ability to resist external stress, causing the fiber to easily break during the drafting process and making it impossible to achieve more stable continuous post-processing reinforcement. .

(3) The mechanical strength of the fiber obtained by the current drafting method is still insufficient, and the fiber consistency is poor.

In view of the above shortcomings, the main purpose of the present invention is to provide an efficient post-processing enhancement method for carbon nanotube fibers. In some specific examples, the raw fibers prepared by the floating catalytic method are first twisted and processed through a subsequent drying process. The twisting state is fixed, and then the twisted raw yarns are stranded. Subsequently, through the protonation of strong acid, the twisted fibers expand to apply a higher draft rate, thereby reorienting the internal structure of the carbon nanotube fibers, and through subsequent cleaning and annealing treatments, efficient Fibers are processed continuously. When drawing in strong acid by plying fibers, due to the adaptive effect of fiber edge shape, the interfiber gaps inside the plied fibers are filled, and the effective contact between fibers increases. During the drafting process, each fiber can share part of the drafting stress, so that the drafting force is applied to each fiber more evenly. This is also the key to achieving a higher drafting rate in the present invention. In addition, after the twisted fibers are stretched by strong acid, they enter the coagulation bath to achieve deprotonation. The concentration difference causes the fibers inside the twisted fibers to shrink. Since the fibers after twisting have the characteristics of radial shrinkage, each single fiber will shrink. The filaments can be split independently of each other, ultimately achieving efficient batch post-processing enhancement of carbon nanotube fibers.

Referring to Figure 1, an embodiment of the present invention first provides a method for drawing and reinforcing carbon nanotube fibers, which includes the following steps:

Carbon nanotube fibers are provided, and the carbon nanotube fibers are in a twisted state.

The carbon nanotube fibers are plied to obtain fiber bundles.

The fiber bundle is subjected to protonation drawing and coagulation bath treatment to obtain precursor fibers.

The protonation reagent and/or coagulation bath reagent in the precursor fiber is removed to obtain carbon nanotube reinforced fiber.

As some typical application examples of the above technical solution, the wet fiber strands grown by the floating catalytic method can first be twisted, and then the twisted state of the fiber can be solidified by drying, and the twisted fibers can be plied. Finally, the chlorosulfonic acid-assisted drawing means is used to continuously draw and strengthen the twisted fibers after plying. The continuous drawing and strengthening system includes four parts: the winding end, the drafting end, the cleaning end, and the winding end. Subsequent drafting and strengthening treatment after fiber plying can greatly increase fiber processing capacity, and drafting after plying can improve continuity, thereby achieving efficient fiber post-processing reinforcement.

Among them, the carbon nanotube fiber is used as a raw material for subsequent plying, drafting and other processes. The twisted fiber can be directly purchased commercially, or it can be prepared by oneself. For example, the following carbon nanotube raw fiber can be commercially purchased and then twisted, etc. Processing, you can also prepare the original carbon nanotube fibers yourself and then twist them. That is, the preparation process exemplarily provided by the present invention can be prepared by one manufacturer, or can be dispersed and performed by multiple manufacturers to perform different steps. Even the following combined fiber bundles can also be prepared by one of the manufacturers, Then it is transferred to another producer in various forms for subsequent processing. Such processing methods all fall within the protection scope of the present invention.

In some embodiments, the carbon nanotube fibers are obtained by twisting original carbon nanotube fibers.

In some embodiments, the first twist angle of the carbon nanotube fiber may preferably be 5-35°.

In some embodiments, the diameter of the carbon nanotube fibers may preferably range from 10 to 50 μm.

A very critical point is that in the technical solution provided by the present invention, twisting and plying work together. During the protonation drafting process, the fiber will expand due to protonation. If it is not coordinated with appropriate twisting treatment, , the phenomenon of surface adhesion easily occurs between the expanded multi-strand fibers (this is an inevitable phenomenon caused by the high specific surface area, high flexibility and entanglement ability of the carbon nanotubes themselves). This aspect makes the processed multi-strand fibers Fibers are difficult to separate, limiting application scenarios; on the other hand, mutual viscosity will significantly affect the sharing of draft stress between fibers, and even cause some weaker fibers to be damaged due to adhesion, greatly affecting the strength of the fibers. Mechanical strength and consistency levels.

Combined with appropriate twisting, even if expansion occurs between multiple fibers, they can still have a certain "cohesion". That is, twisting overcomes the expansion and brings about a certain shrinkage tendency, which makes it difficult for fibers to bond. , there is a certain degree of free slip, surface damage is not easy to occur and the drafting stress can be adaptively dispersed to different fiber filaments without hindrance, thus avoiding the above problems.

Therefore, the key technical means of the present invention lies not only in plying multiple fibers, but also in the coordinated effects of twisting and plying.

In some embodiments, the carbon nanotube original fibers are produced by floating vapor deposition, but are not limited thereto. Of course, this is a very efficient and low-cost method for preparing raw fibers, and raw fibers prepared by other existing methods such as liquid phase spinning and array spinning can also be used.

In some embodiments, the carbon nanotube original fibers are in a wet state that absorbs liquid.

In some embodiments, the drafting enhancement method may further include: performing a twisting process and then a drying process to shape the twisted original carbon nanotube fibers to obtain the carbon nanotube fibers.

In some embodiments, the temperature of the drying treatment is 60-190°C and the time is 3-10 minutes.

In some embodiments, the fiber bundle has a ply number of 20-200.

In some embodiments, the protonated drafting has a drafting ratio of 15-40% and a drafting rate of 0.5-2m/min.

In some embodiments, the protonating reagent is selected from strong acid reagents.

In some embodiments, the protonating reagent includes any one of chlorosulfonic acid, methanesulfonic acid or a combination of both.

In some embodiments, the coagulation bath reagent includes any one or a combination of acetone and methylene chloride.

It should be pointed out that the main technical means of the drafting enhancement method exemplified in the present invention is to use twisting and plying to ultimately improve the mechanical strength, consistency and continuity. Specifically, how to perform protonated drafting and Coagulation bath treatment has been fully demonstrated in the prior art and does not need to be limited to the specific protonation reagents and selection of coagulation bath reagents mentioned above. Any chemical reagent that can achieve the same protonation function and coagulation function can be used.

As some typical application examples of the above technical solutions, a complete specific drafting process includes the following steps:

1) First, twist the original carbon nanotube fiber, which is a wet fiber grown by a floating catalytic method and densified by water.

2) Drying the twisted original wet carbon nanotube fiber obtained in step (1) can more effectively maintain its twisted state and fix the twist angle.

3) The twisted carbon nanotube fibers obtained in step (2) are stranded, and then the stranded fibers are continuously drafted and strengthened, which includes three stages of drafting, coagulation bath cleaning and annealing:

a. During the drafting stage, when the fibers are plied for strong acid drafting, due to the adaptive effect of the fiber edge shape, the interfiber gaps inside the plied fibers are filled, and the effective contact between fibers increases. During the drafting process, each fiber can share part of the drafting stress, so that the drafting force is applied to each fiber more evenly, which is also the key to achieving a higher drafting rate in the present invention.

b. After drafting, the plying fiber enters the coagulation bath for deprotonation cleaning. Since each fiber in the plying fiber has been twisted, it has the characteristics of radial shrinkage during the deprotonation stage. Each fiber gradually moves along the radial direction from the expanded state. Shrink, and eventually each monofilament becomes independent of the other.

c. After the above-mentioned drafting and cleaning, the plied fibers enter the annealing furnace for protective atmosphere annealing treatment to further remove the residual solution inside the fibers. After the above three-stage treatment, each fiber in the combined fiber is independent of each other and can be separated.

Some specific technical parameters regarding the above steps:

Step (1) includes: twisting the original fiber with a twist angle between 5-35°.

Step (2) includes: drying the twisted fibers at a drying temperature of 60-190°C and a drying time of 3-10 minutes.

Step (3) includes: a. plying the twisted fibers. The number of fibers after plying is 20 to 200. After plying, the fibers are drawn in strong acid (chlorosulfonic acid, methylsulfonic acid or a mixture of both), with a draw rate of 15% to 40% and a draw rate of 0.5 to 2m/min. The coagulation bath uses acetone, methylene chloride or a mixed solution of the two in any proportion; b. Perform high-temperature annealing treatment on the fiber obtained in step (3) under an argon environment, where the annealing temperature is 350-550°C and the annealing time is 4-20 minutes .

The above are some specific details about fiber drafting, and the present invention also provides further technical means. For example, in some embodiments, the fiber bundle has a second twist angle.

The second twisting angle is 2-10°.

In some embodiments, the second twist angle is less than 1/2 the first twist angle.

In the present invention, the plying can be directly parallel plying, that is, multiple bundles of fibers are combined into one bundle and used directly, or a certain second twisting angle can be applied to the plyed fiber bundles. As a further optimization solution of the above technical solution, the inventor found that applying a second twist can also produce more excellent technical effects, especially reflected in the fiber consistency after drafting.

After the second twist angle is applied, during protonation expansion, the second twist can bring a certain inward contraction force to the entire fiber bundle, inhibit the mutual separation of fiber filaments, and produce a squeezing and convergence effect, making the pulling The distribution of tensile stress becomes more uniform based on the above method, thereby improving consistency.

As for the specific twist angle setting, during drafting, due to the loosening effect of the protonated reagent, there is a certain untwisting tendency in the twisting of the filament bundle, and this trend will act on both the first twist angle and The second twisting angle. Therefore, the second twisting angle needs to be set to be significantly smaller than the first twisting angle to prevent the significant untwisting phenomenon of the first twisting angle earlier than the second twisting angle and avoid one of the single twisting angles. After the root fiber is untwisted, the shrinkage pressure brought by the second twist angle causes significant bonding between fiber filaments. Therefore, the inventor was able to propose the quantitative relationship between the above-mentioned first twist angle and the second twist angle through continuous summary and analysis.

In some embodiments, the drafting enhancement method may specifically include:

The precursor fiber is annealed to remove the protonation reagent and/or coagulation bath reagent to obtain a reinforced fiber bundle.

In some embodiments, the drafting reinforcement method may further include: splitting the reinforcing fiber bundle to obtain a plurality of mutually separated carbon nanotube reinforcing fibers.

In some embodiments, the temperature of the annealing treatment is 350-550°C and the time is 4-20 minutes.

Of course, the technical parameters of the above examples are only the inventor's best parameters based on the limited reagents currently used. If those skilled in the art replace them with other protonation reagents and/or coagulation baths, the corresponding annealing temperature and time Can be adjusted appropriately to match different reagents.

Moreover, the method of removing the above-mentioned protonation reagent and/or coagulation bath reagent is not limited to high-temperature annealing treatment. Other methods of replacing the low-boiling point solvent with a low-boiling point solvent and then drying to remove the low-boiling point solvent can also achieve the same technical effect. Any method that can achieve Any technical means for removing adsorbed reagents from fibers can be applied in the present invention.

In some embodiments, the CV value of the tensile strength of multiple fibers in the obtained carbon nanotube-reinforced fibers is less than 5%.

In some embodiments, the continuity of the obtained carbon nanotube reinforced fibers is greater than 500 m.

The most important technical effect of the present invention lies in the mechanical strength, consistency and continuity of the fiber. In addition, because the present invention processes the carbon nanotube fibers after they are stranded, the fiber processing efficiency is improved dozens of times compared to the single-filament efficiency. to hundreds of times. The core point of the present invention is to use twisted fibers for plying treatment. During the coagulation bath cleaning stage after the plying fibers are drawn, the twisted fibers have the characteristic of shrinking along their radial direction due to the deprotonation of the coagulation bath. The contact between fibers is reduced, and each fiber is independent of each other, forming detachable reinforced carbon nanotube fibers. That is to say, using twisted fibers for plying processing can not only achieve batch plying processing, but also achieve the characteristics of independent and separable fibers after processing. Moreover, the improvement in processing efficiency is not only an increase in the number of batch processes, but more importantly, it reduces the frequency of fiber breakage. There is no need to frequently pay attention to whether the fiber is broken or perform splicing operations after breakage, which also significantly saves production time. .

Corresponding to the above drafting enhancement method, a second aspect of the embodiment of the present invention also provides a drafting enhancement system for carbon nanotube fibers, which includes:

The plying module is used to ply the carbon nanotube fibers to obtain fiber bundles, and the carbon nanotube fibers are in a twisted state.

The drafting module is used to perform protonation drafting and coagulation bath treatment on the fiber bundle to obtain precursor fibers.

A post-processing module is used to remove protonation reagents and/or coagulation bath reagents in the precursor fiber to obtain carbon nanotube reinforced fibers.

In some embodiments, the drafting enhancement system may further include a twisting module for twisting original carbon nanotube fibers to obtain the carbon nanotube fibers.

The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the examples selected are only for illustrating the invention and do not limit the scope of the invention.

Example 1

This embodiment illustrates a process of drawing and enhancing carbon nanotubes, which is specifically as follows:

Step (1): Twist the original fiber with a twist angle of 10°. After twisting, the diameter of the fiber is 20 μm.

Step (2): Dry the twisted fibers at a drying temperature of 200°C and a drying time of 1 minute.

Step (3):

a. Ply the twisted fibers. The number of fibers after plying is 50.

b. After plying, the fibers are drawn in strong acid (chlorosulfonic acid) and then passed through a coagulation bath. The drawing rate is 25% and the drawing speed is 0.5m/min. Use acetone for the coagulation bath.

c. Perform high-temperature annealing treatment on the fiber obtained in step (3) under an argon atmosphere, where the annealing temperature is 350°C and the annealing time is 1 minute.

Finally, bundles of reinforcing fibers are obtained, and their continuity is almost not broken, and is only limited by the maximum length of each fiber roll. Usually, a roll of fiber during processing can reach hundreds of meters to kilometers, but it is not limited to this. , when moving from the laboratory to actual production, the use of larger equipment should result in higher fiber lengths per roll. The reinforcing fibers can be peeled off into individual fibers, and in this embodiment, the surface morphology and mechanical properties of the peeled off fibers are tested, as shown in Figures 4-5.

Comparative example 1

This comparative example illustrates a blank control process of carbon nanotube fiber drafting enhancement treatment, the details are as follows:

Steps 1-2 in Example 1 are omitted, and a single original fiber is directly dried and then drafted under the same conditions (reagents, drafting parameters, etc.).

The surface morphology of the obtained reinforced fiber is shown in Figure 3, and the mechanical property test is shown in Figure 5.

Comparing Figure 3 and Figure 4, it can be seen that the microscopic morphology of the fiber drawn after twisting and stranding is more dense than the direct drafting of the original fiber, and multiple strands are formed in it, which should be The reason for its higher mechanical strength.

As can be seen from Figure 5, in terms of results, the mechanical strength and strength consistency of the fibers obtained in Example 1 are also significantly better than those in Comparative Example 1, and statistics show that the fiber strength obtained in Example 1 is 5.5 GPa, intensity CV value is 4.5%.

Moreover, the continuity of the reinforced fibers treated in this comparative example usually ranges from 100 to 600 m, and the breakage frequency is significantly higher than that of Example 1.

Comparative example 2

This comparative example exemplifies a process of drawing and strengthening treatment of carbon nanotube fibers, which is generally similar to Example 1. The main differences are:

The original carbon nanotube fibers are not twisted, but are directly dried and then stranded, and the stranded fibers are drawn and annealed under the same conditions.

Since this comparative example lacks the step of twisting treatment, the adhesion between fibers caused by stranding is very serious, and some fibers cannot be separated from the fiber bundle.

Moreover, the mechanical strength and consistency of the fiber are also significantly worse than those in Example 1, the mechanical strength is slightly lower than that in Comparative Example 1, and the strength CV value is as high as 8%.

Also, the continuity of the reinforced fibers processed in this comparative example is usually between 200-300m.

Comparative example 3

This comparative example exemplifies a process of drawing and strengthening treatment of carbon nanotube fibers, which is generally similar to Example 1. The main differences are:

After the original carbon nanotube fibers are twisted and dried, they are not stranded. Instead, a single twisted fiber is used for drawing and annealing under the same conditions.

The mechanical strength and consistency of the obtained fiber are also significantly worse than in Example 1, and direct drafting after twisting a single fiber may cause local stress concentration inside the fiber, and this stress concentration is not bundled into multiple bundles. The fibers are dispersed, so the average mechanical strength of the obtained fiber is even significantly lower than that of Comparative Example 1 (a decrease of about 30%), and the strength CV value is as high as 15%.

Also, the continuity of the reinforcing fibers processed in this comparative example is usually between 10-50m.

Example 2

This embodiment illustrates a process of drawing and enhancing carbon nanotubes, which is generally similar to Embodiment 1. The main differences are:

After plying the fibers, a second slight twist is applied so that the fiber bundle has a second twist angle of 5°.

The strength of the fiber obtained in this example is at the same level as that in Example 1, but the consistency is better, and its strength CV value is reduced to 3.5%.

Comparative example 4

This comparative example is generally similar to Example 2, and the main differences are:

The second twist angle applied is the same as the first twist applied to the original fiber.

This comparative example is somewhat similar to Comparative Example 2. Because the degree of the second twisting is too high, the inward squeezing force of the fiber bundles is strong, resulting in a little adhesion between the fibers, which affects the consistency and strength. The CV value is significantly higher at 9.0%.

Example 3

This example shows an example of the influence of the twist angle of the original fiber on the mechanical properties, specifically as follows:

The twisting angle of the original fiber was changed. The initial mechanical properties test of the original carbon nanotubes with different twisting angles is shown in Figure 2a. The fiber morphology is shown in Figure 2b. The drawing and post-processing were carried out under the same conditions. , and test related mechanical properties.

The results show that different twisting angles have an impact on mechanical properties, but the fibers finally obtained are better than those without twisting (0°).

Example 4

This embodiment is generally similar to Embodiment 1, and the main differences are:

The annealing temperature adopts gradient temperature, that is, four temperature zones are used for annealing from the position where the fiber enters the annealing furnace. The gradient is 150℃-200℃-300℃-350℃. The mechanical strength of the fiber finally obtained was similar to that of Example 1, but the CV value was further reduced to 3%. And due to the use of gradient temperature, the static annealing state of the fiber is more relaxed, the fiber processing speed is increased (0.8m/min), and the irregular morphology of the fiber directly entering the high temperature zone for annealing is avoided.

It can be determined from this that on the basis of the above technical solution provided by the present invention, further using a gradient temperature rise method during annealing can further optimize fiber consistency.

Example 5

This embodiment is generally similar to Embodiment 1, and the main differences are:

By changing the number of plies to 20 and 200 respectively, the mechanical strength, consistency and continuity of the finally obtained fibers are basically unchanged compared to Example 1.

Based on the above embodiments and comparative examples, it can be understood that the drafting enhancement method provided by the embodiments of the present invention twists and plies the carbon nanotube fibers, and performs strong acid-assisted drafting on the fiber bundles after plying. After the fiber bundles are subjected to strong acid After protonation expansion, the edge shape of each expanded fiber inside produces an adaptive effect, the gaps between the plying fibers are filled, and the effective contact between fibers increases; during the drafting process, the effective contact between fibers can transfer pull to each other. The tensile stress is applied more uniformly to each fiber, thereby greatly improving the stability of the fiber drafting process, thereby achieving higher drafting speed and drafting ratio, and ultimately significantly improving the mechanical strength of the reinforced fiber. and consistency, and brings very excellent continuity, which is very conducive to the application of carbon nanotube fibers.

In addition, the method provided by the embodiment of the present invention also brings a very significant advantage in preparation efficiency. This advantage is not only the increase in batch processing quantity brought about by the simultaneous drafting of multiple fibers, but also due to the extremely high brought about by continuity.

It should be understood that the above embodiments are only to illustrate the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with the technology to understand the content of the present invention and implement it accordingly, and cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method for drawing and reinforcing carbon nanotube fibers, which is characterized by comprising: Provide carbon nanotube fibers, the carbon nanotube fibers being in a twisted state; Perform plying treatment on the carbon nanotube fibers to obtain fiber bundles; The fiber bundle is subjected to protonation drawing and coagulation bath treatment to obtain precursor fibers; The protonation reagent and/or coagulation bath reagent in the precursor fiber is removed to obtain carbon nanotube reinforced fiber. 2. The drafting enhancement method according to claim 1, wherein the carbon nanotube fiber is obtained by twisting the original carbon nanotube fiber; Preferably, the first twist angle of the carbon nanotube fiber is 5-35°; Preferably, the diameter of the carbon nanotube fibers is 10-50 μm. 3. The drafting enhancement method according to claim 2, characterized in that the original carbon nanotube fibers are produced by a floating vapor deposition method; Preferably, the original carbon nanotube fibers are in a wet state that absorbs liquid; Preferably, the method further includes: performing twisting treatment and then drying treatment to shape the twisted original carbon nanotube fibers to obtain the carbon nanotube fibers; Preferably, the temperature of the drying treatment is 60-190°C and the time is 3-10 minutes. 4. The drafting enhancement method according to claim 1, characterized in that the number of fiber bundles combined is 20-200. 5. The drafting enhancement method according to claim 1, characterized in that the drafting rate of the protonated drafting is 15-40%, and the drafting rate is 0.5-2m/min; Preferably, the protonating reagent is selected from strong acid reagents; Preferably, the protonating reagent includes any one or a combination of two of chlorosulfonic acid and methylsulfonic acid; Preferably, the coagulation bath reagent includes any one or a combination of acetone and methylene chloride. 6. The drafting enhancement method according to claim 1, characterized in that the fiber bundle has a second twist angle; The second twisting angle is 2-10°; Preferably, the second twist angle is less than 1/2 of the first twist angle. 7. The drafting enhancement method according to claim 1, characterized in that it specifically includes: Perform annealing treatment on the precursor fiber to remove the protonation reagent and/or coagulation bath reagent to obtain a reinforced fiber bundle; Preferably, the method further includes: splitting the reinforcing fiber bundle to obtain a plurality of mutually separated carbon nanotube reinforcing fibers. 8. The drafting enhancement method according to claim 7, characterized in that the temperature of the annealing treatment is 350-550°C and the time is 4-20 minutes. 9. The drafting reinforcement method according to claim 1, characterized in that the CV value of the tensile strength of the plurality of fibers in the obtained carbon nanotube reinforced fibers is less than 5%; Preferably, the continuity of the obtained carbon nanotube reinforced fiber is more than 500m. 10. A carbon nanotube fiber drafting reinforcement system, characterized by comprising: The plying module is used to ply carbon nanotube fibers to obtain fiber bundles, and the carbon nanotube fibers are in a twisted state; A drafting module, used to perform protonation drafting and coagulation bath treatment on the fiber bundle to obtain precursor fibers; A post-processing module for removing protonation reagents and/or coagulation bath reagents in the precursor fiber to obtain carbon nanotube reinforced fibers; Preferably, the method further includes a twisting module for twisting original carbon nanotube fibers to obtain the carbon nanotube fibers.