Preparation method of super-drafted carbon fiber, carbon fiber and application

Abstract

The invention discloses a preparation method of super-drafted carbon fibers, carbon fibers and application, and relates to the technical field of inorganic materials. The method comprises the following steps: preparing a spinning solution containing 10-40wt% of polyacrylonitrile; 2, 4, 6-triaminopyrimidine and barbituric acid are added into the spinning solution, the total amount of 2, 4, 6-triaminopyrimidine and barbituric acid accounts for 1-20 wt% of polyacrylonitrile, and a spinning solution is obtained; carrying out dry spray preforming on the spinning stock solution, then putting the spinning stock solution into a coagulating bath solution at 0-10 DEG C, and carrying out low-temperature coagulating bath treatment at a draw ratio of 1-10 to prepare nascent fibers; and preparing the nascent fiber into a precursor, and preparing the precursor into the carbon fiber through pre-oxidation and carbonization processes. By adding the supramolecular gel accelerator, the spinning stock solution can be rapidly gelated in a coagulating bath, and then high-multiple drafting can be applied to nascent fibers. The internal graphite structure of the carbon fiber prepared by the super-drafting gel spinning technology is perfect, the orientation is good, the defects are reduced, and the fiber strength is improved.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic materials, and in particular to a method for preparing super-drawn carbon fiber and the carbon fiber. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] With the rapid development of modern industry, the demand for high-performance materials is growing. In this context, carbon fiber materials have been increasingly widely used in aerospace, automobile manufacturing, sports equipment and other fields due to their low density, high strength and modulus, high electrical conductivity and high thermal conductivity. However, traditional carbon fiber production technology has many limitations, such as high production costs and complex processes, which seriously restrict the large-scale application and further development of carbon fiber materials. The production of carbon fiber mainly uses polyacrylonitrile as a precursor, and the final carbon fiber product is made through dry / wet / dry-wet spinning, pre-oxidation, carbonization and other processes. In production, the drafting process of the spinning process is the key link that affects the final carbon fiber performance. However, traditional drafting technology has problems such as limited drafting multiples, uneven fiber structure, and low production efficiency.

[0004] In recent years, gel spinning technology has gradually attracted attention due to its unique advantages. Gel spinning technology dissolves the polymer in an appropriate solvent to form a spinning solution, and then uses a low-temperature coagulation bath to cause the spinning solution to gel to form gel fibers. In the gel state, the fiber can withstand a higher draft multiple, which makes the produced raw fiber uniform in structure and excellent in performance.

[0005] More efficient fiber drawing technology remains a technical challenge that researchers are constantly exploring. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing super-stretched carbon fiber and carbon fiber, by adding a supramolecular gel promoter to the polyacrylonitrile spinning solution to promote the rapid gelation of the spinning solution in a coagulation bath, and then achieve super-stretching of the polyacrylonitrile spinning fine flow in the coagulation bath, and finally obtain a carbon fiber with good orientation and few defects.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] The first aspect of the present invention provides a method for preparing super-drawn carbon fiber, comprising the following steps:

[0009] S1, preparing a spinning solution containing 10-40 wt% polyacrylonitrile;

[0010] S2, adding 2,4,6-triaminopyrimidine and barbituric acid to the spinning solution, wherein the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:(0.5-2), and the total amount of the two accounts for 1-20wt% of the polyacrylonitrile, to obtain a spinning solution;

[0011] S3, after preforming by dry spraying the spinning solution, entering the coagulation bath solution at 0-10°C, and performing low-temperature coagulation bath treatment at a draft ratio of 1-10 to obtain primary fibers;

[0012] S4. The primary fibers are made into raw fibers, and the raw fibers are made into carbon fibers through pre-oxidation and carbonization processes.

[0013] Optionally, in S1, the solvent of the spinning solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide.

[0014] Optionally, in S2, a capping agent is added to the spinning solution, and the capping agent includes one or more of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine.

[0015] Optionally, the amount of the capping agent added is 1 to 50 wt % of the total amount of 2,4,6-triaminopyrimidine and barbituric acid.

[0016] Optionally, in S3, the solute in the coagulation bath solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide, and the solvent in the coagulation bath solution is one or more of water, methanol, ethanol and diethylene glycol.

[0017] Optionally, in S3, the solute in the coagulation bath solution is consistent with the solvent composition in the spinning solution.

[0018] Optionally, in S3, the mass fraction of the solute in the coagulation bath solution is 5 to 95%.

[0019] Optionally, in S3, the draft ratio is 5-8.

[0020] Optionally, in S4, pre-oxidation is performed in an air medium at a pre-oxidation temperature of 150-350°C.

[0021] Optionally, in S4, carbonization is performed in an inert atmosphere or a vacuum environment, and the carbonization temperature is 1000-1600°C.

[0022] In a second aspect, a carbon fiber prepared by the above-mentioned super-stretched carbon fiber preparation method.

[0023] Thirdly, the above-mentioned carbon fiber is used in the fields of aerospace or transportation.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The present invention develops a new type of super-drawn gel spinning technology for spinning carbon fiber. The addition of supramolecular gel accelerator allows the spinning solution to gel quickly in the coagulation bath, and then a high multiple of drafting can be applied to the primary fiber, which effectively improves the drafting effect, significantly improves the orientation of the molecular chain in the primary fiber, and reduces defects such as cracks and holes. The carbon fiber prepared by the super-drawn gel spinning technology has a perfect internal graphite structure, good orientation, reduced defects, and improved fiber strength. It can be widely used in aerospace, transportation and other fields as a reinforcing material.

[0026] 2. In the preparation method of the present invention, due to the super-stretching characteristics of the gel spinning process, a stretching multiple of 1-10 times can be achieved, which can be applied to a higher spinning speed, thereby significantly improving the spinning production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0028] In order to show the positions of various parts, the distances or sizes between them are exaggerated in the figure, and the schematic diagram is for illustration only.

[0029] Figure 1 This is a photo of the dry spray section of the gel spinning process in Example 1.

[0030] Figure 2 This is a physical picture of the polyacrylonitrile precursor in Example 1.

[0031] Figure 3 These are microscopic photographs in Example 3, (A) is a microscopic photograph of polyacrylonitrile precursor, and (B) is a microscopic photograph of carbon fiber.

[0032] Figure 4 These are the microscopic photographs in Comparative Example 1, (A) is a microscopic photograph of polyacrylonitrile precursor, and (B) is a microscopic photograph of carbon fiber. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0036] A method for preparing super-drawn carbon fiber comprises the following steps:

[0037] S1, preparing a spinning solution containing 10-40 wt% polyacrylonitrile;

[0038] S2, adding 2,4,6-triaminopyrimidine and barbituric acid to the spinning solution, wherein the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:(0.5-2), and the total amount of the two accounts for 1-20wt% of the polyacrylonitrile, to obtain a spinning solution;

[0039] S3, after preforming by dry spraying the spinning solution, entering the coagulation bath solution at 0-10°C, and performing low-temperature coagulation bath treatment at a draft ratio of 1-10 to obtain primary fibers;

[0040] S4. The primary fibers are made into raw fibers, and the raw fibers are made into carbon fibers through pre-oxidation and carbonization processes.

[0041] In the above method, polyacrylonitrile is used as a precursor and dissolved to prepare a spinning solution. Since the spinning solution is added with a precursor of a supramolecular gel promoter, it can quickly gel in a coagulation bath, thereby achieving effective super-multiple drawing of the primary fiber in the coagulation bath. The primary fiber is subjected to processes such as washing, drawing, oiling, drying and densification, and steam drawing to obtain polyacrylonitrile precursor, which is then pre-oxidized and carbonized to form carbon fiber. The carbon fiber prepared in this way has a good graphite structure orientation and fewer defects.

[0042] 2,4,6-Triaminopyrimidine, CAS number is 1004-38-2.

[0043] Barbituric acid, also known as malonyl urea, 2,4,6-pyrimidinetrione.

[0044] 2,4,6-Triaminopyrimidine and barbituric acid are used together as small molecule precursors of supramolecular gel promoters. When added to the spinning solution, they can self-assemble and synthesize supramolecular gel promoters in situ in the spinning solution, which can make the polyacrylonitrile spinning stream quickly gel in a low-temperature coagulation bath, thereby achieving effective super-multiple stretching of the primary fibers in the coagulation bath.

[0045] The draft ratio is the ratio of the winding speed of the nascent fiber to the fluid extrusion speed of the spinning solution. The larger the draft ratio, the faster the spinning speed and the finer the spinning diameter. If the draft ratio is too large, greater than the material's own limit, continuous spinning cannot be achieved.

[0046] Optionally, in S1, the solvent of the spinning solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide, which are commonly used spinning solvents.

[0047] Optionally, in S2, a capping agent is added to the spinning solution, and the capping agent includes one or more of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine. The capping agent is introduced to adjust the structure and effect of the supramolecular gel accelerator.

[0048] Optionally, the amount of the capping agent added is 1 to 50 wt % of the total amount of 2,4,6-triaminopyrimidine and barbituric acid.

[0049] Optionally, in S3, the spinning solution is subjected to degassing and filtering treatments, and then dry-sprayed for preforming.

[0050] Optionally, in S3, the solute in the coagulation bath solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide, and the solvent in the coagulation bath solution is one or more of water, methanol, ethanol and diethylene glycol.

[0051] Optionally, in S3, the solute in the coagulation bath solution is consistent with the solvent composition in the spinning solution.

[0052] Optionally, in S3, the mass fraction of the solute in the coagulation bath solution is 5 to 95%.

[0053] Optionally, in S3, a wet spinning process is performed after the low-temperature coagulation bath to further remove the solvent in the gelled spinning solution to obtain primary fibers.

[0054] Optionally, in S3, the draft ratio is 5-8.

[0055] Optionally, in S4, the spun fibers are made into raw fibers through washing, drawing, oiling, drying and densification, and steam drawing processes.

[0056] Optionally, in S4, pre-oxidation is performed in an air medium at a pre-oxidation temperature of 150-350°C.

[0057] Optionally, in S4, carbonization is performed in an inert atmosphere or a vacuum environment, and the carbonization temperature is 1000-1600°C.

[0058] A carbon fiber prepared by the above-mentioned super-drawn carbon fiber preparation method.

[0059] An application of the carbon fiber in the field of aerospace or transportation.

[0060] Example 1

[0061] A super-drawn carbon fiber, the preparation method comprising the following steps:

[0062] S1, using dimethyl sulfoxide as solvent, preparing a spinning solution containing 23 wt% polyacrylonitrile;

[0063] S2, adding a small molecule precursor of a supramolecular gel accelerator to a spinning solution, including 2,4,6-triaminopyrimidine and barbituric acid, wherein the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:1, and the two precursors account for 2wt% of polyacrylonitrile respectively, and the total amount accounts for 4wt% of polyacrylonitrile, to obtain a spinning solution;

[0064] S3, using a 25wt% dimethyl sulfoxide / water solution as a coagulation bath solution, the spinning solution is subjected to conventional degassing and filtration treatments, and then dry-sprayed to preform the spinning solution (the photo of the dry-spraying section of the spinning process is shown in FIG. Figure 1 As shown), then enter into a coagulation bath solution at 5°C, the coagulation bath draft ratio is 5, and the nascent fiber is obtained;

[0065] S4, the primary fiber is gradually made into polyacrylonitrile precursor through processes such as washing, drawing, oiling, drying and densification, and steam drawing (the actual picture of polyacrylonitrile precursor is as shown in the figure). Figure 2 As shown in the figure, the raw silk is pre-oxidized at 280°C in an air atmosphere, and then made into carbon fiber by a carbonization process at 1400°C in a vacuum. The obtained fiber has a strength of about 5.5GPa.

[0066] Example 2

[0067] A super-drawn carbon fiber, the preparation method comprising the following steps:

[0068] S1, using dimethyl sulfoxide as solvent, preparing a spinning solution containing 21 wt% polyacrylonitrile;

[0069] S2, adding a small molecule precursor of a supramolecular gel accelerator to a spinning solution, including 2,4,6-triaminopyrimidine and barbituric acid, wherein the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:1, and the total amount accounts for 8wt% of polyacrylonitrile, to obtain a spinning solution;

[0070] S3, using a dimethyl sulfoxide / water solution with a mass concentration of 28wt% as a coagulation bath solution, the spinning solution is subjected to conventional degassing and filtration treatments, and then the spinning solution is dry-sprayed for preforming, and then enters the coagulation bath solution at 5°C, and the coagulation bath draft ratio is 6, to obtain primary fibers;

[0071] S4. The spun fibers are gradually made into raw fibers through processes such as washing, drawing, oiling, drying and densification, and steam drawing. The raw fibers are pre-oxidized at 280°C in an air atmosphere, and then carbonized at 1400°C in an inert atmosphere to make carbon fibers. The strength of the obtained fibers is about 5.7 GPa.

[0072] Among them, the differences from Example 1 are: in S1, the concentration of polyacrylonitrile in the spinning solution is different, which is 21wt%; in S2, the added amount of the small molecule precursor of the supramolecular gel accelerator is different, and the total amount is 8wt% of polyacrylonitrile; in S3, the coagulation bath concentration is different, which is 28wt%; in S3, the coagulation bath draw ratio is different, which is 6.

[0073] Example 3

[0074] A super-drawn carbon fiber, the preparation method comprising the following steps:

[0075] S1, using dimethyl sulfoxide as solvent, preparing a spinning solution containing 19 wt% polyacrylonitrile;

[0076] S2, adding a small molecule precursor of a supramolecular gel accelerator to a spinning solution, including 2,4,6-triaminopyrimidine and barbituric acid, the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:1.5, the total amount accounts for 12wt% of polyacrylonitrile, and m-phenylenediamine is added as a capping agent, the amount of the capping agent added accounts for 20wt% of the total amount of the two small molecule precursors, to obtain a spinning solution;

[0077] S3, using a 30wt% dimethyl sulfoxide / water solution as a coagulation bath solution, the spinning solution is subjected to conventional degassing and filtration treatments, and then the spinning solution is dry-sprayed for preforming, and then placed in a coagulation bath solution at 5°C, with a coagulation bath draft ratio of 7, to obtain primary fibers;

[0078] S4. The spun fibers are gradually made into raw fibers through processes such as washing, drawing, oiling, drying and densification, and steam drawing. The raw fibers are pre-oxidized at 280°C in an air atmosphere, and then carbonized at 1400°C in an inert atmosphere to make carbon fibers. The strength of the obtained fibers is about 5.9 GPa.

[0079] Among them, the difference from Example 1 is that: in S1, the concentration of polyacrylonitrile in the spinning solution is different, which is 19wt%; in S2, the amount of small molecule precursor of the supramolecular gel accelerator added is different, the total amount is 12wt% of polyacrylonitrile, and m-phenylenediamine accounting for 20% of the total amount of the precursor is added as a capping agent; in S3, the coagulation bath concentration is different, which is 30wt%; in S3, the coagulation bath draw ratio is different, which is 7.

[0080] Example 4

[0081] A super-drawn carbon fiber, the preparation method comprising the following steps:

[0082] S1, using dimethyl sulfoxide as solvent, preparing a spinning solution containing 17 wt% polyacrylonitrile;

[0083] S2, adding a small molecule precursor of a supramolecular gel accelerator to a spinning solution, including 2,4,6-triaminopyrimidine and barbituric acid, the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1:2, the two precursors account for 8wt% of polyacrylonitrile respectively, and the total amount accounts for 16wt% of polyacrylonitrile, and m-phenylenediamine is added as a capping agent, the amount of the capping agent added accounts for 30wt% of the total amount of the two small molecule precursors, to obtain a spinning solution;

[0084] S3, using a 32wt% dimethyl sulfoxide / water solution as a coagulation bath solution, the spinning solution is subjected to conventional degassing and filtration treatments, and then the spinning solution is dry-sprayed for preforming, and then placed in a coagulation bath solution at 5°C, with a coagulation bath draft ratio of 8, to obtain primary fibers;

[0085] S4. The spun fibers are gradually made into raw fibers through processes such as washing, drawing, oiling, drying and densification, and steam drawing. The raw fibers are pre-oxidized at 280°C in an air atmosphere, and then carbonized at 1400°C in an inert atmosphere to make carbon fibers. The strength of the obtained fibers is about 6.1 GPa.

[0086] Among them, the difference from Example 1 is that: in S1, the concentration of polyacrylonitrile in the spinning solution is different, which is 17wt%; in S2, the amount of small molecule precursor of the supramolecular gel accelerator added is different, the total amount is 16wt% of polyacrylonitrile, and m-phenylenediamine accounting for 30% of the total amount of the precursor is added as a capping agent; in S3, the coagulation bath concentration is different, which is 32wt%; in S3, the coagulation bath draw ratio is different, which is 8.

[0087] Comparative Example 1

[0088] A super-drawn carbon fiber, the preparation method comprising the following steps:

[0089] S1, using dimethyl sulfoxide as solvent, preparing a spinning solution containing 23 wt% polyacrylonitrile;

[0090] S2, using a 25wt% dimethyl sulfoxide / water solution as a coagulation bath solution, the spinning solution is subjected to conventional degassing and filtration treatments, and then the spinning solution is dry-sprayed for preforming, and then placed in a coagulation bath solution at 5°C, with a coagulation bath draft ratio of 4, to obtain primary fibers;

[0091] S3. The spun fibers are gradually made into raw fibers through processes such as washing, drawing, oiling, drying and densification, and steam drawing. The raw fibers are pre-oxidized at 280°C in an air atmosphere, and then carbonized at 1400°C in an inert atmosphere to make carbon fibers. The strength of the obtained fibers is about 5.0 GPa.

[0092] The difference from Example 1 is that no small molecule precursor of the supramolecular gel promoter is added, and no capping agent is added. The draft ratio in the preparation process is 4. The draft ratio here is the maximum draft ratio that can be achieved in the process. If the draft ratio is exceeded, the fiber quality begins to decline and defective structures appear inside.

[0093] The material parameters and properties of each embodiment and comparative example are summarized in Table 1.

[0094] The polyacrylonitrile precursor and carbon fiber in Example 3 and Comparative Example 1 were observed microscopically: Figure 3 As shown in (A), carbon fiber products such as Figure 3 As shown in (B), the polyacrylonitrile precursor in Comparative Example 1 is as follows Figure 4 As shown in (A), carbon fiber products such as Figure 4 As shown in (B) in .

[0095] It can be seen that: Example 3, due to the adoption of the technical solution of the present invention, can use a larger draft ratio in the preparation process, so that it can stably prepare polyacrylonitrile precursor with a finer diameter than that of Comparative Example 1 while ensuring quality, so that the diameter of the prepared carbon fiber is also finer than that of Comparative Example 1. Although the surface quality of the fibers of Example 3 and Comparative Example 1 is similar, since the diameter of the prepared carbon fiber of Example 3 is finer, the strength of the product woven or prepared using the fiber of Example 3 as raw material is higher, and can be used as a reinforcing material in the fields of aerospace, transportation, etc.

[0096] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing super-drawn carbon fiber, characterized in that: The following steps are involved: S1, preparing a spinning solution containing 10-40 wt% polyacrylonitrile; S2, adding 2,4,6-triaminopyrimidine and barbituric acid to the spinning solution, the mass ratio of 2,4,6-triaminopyrimidine to barbituric acid is 1: (0.5-2), and the total amount of the two accounts for 1-20wt% of the polyacrylonitrile to obtain a spinning solution; S3, after preforming by dry spraying the spinning solution, entering the coagulation bath solution at 0-10°C, and performing low-temperature coagulation bath treatment at a draft ratio of 1-10 to obtain primary fibers; S4. The primary fibers are made into raw fibers, and the raw fibers are made into carbon fibers through pre-oxidation and carbonization processes.

2. The method for preparing super-stretched carbon fiber according to claim 1, characterized in that: In S1, the solvent of the spinning solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide.

3. The method for preparing super-stretched carbon fiber according to claim 1, characterized in that: In S2, a capping agent is added to the spinning solution, wherein the capping agent includes one or more of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine; Optionally, the amount of the capping agent added is 1 to 50 wt % of the total amount of 2,4,6-triaminopyrimidine and barbituric acid.

4. The method for preparing super-stretched carbon fiber according to claim 1, characterized in that: In S3, the solute in the coagulation bath solution is one of dimethyl sulfoxide, dimethylformamide or dimethylacetamide, and the solvent in the coagulation bath solution is one or more of water, methanol, ethanol and diethylene glycol; Optionally, in S3, the mass fraction of the solute in the coagulation bath solution is 5 to 95%.

5. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that: In S3, the solute in the coagulation bath solution is consistent with the solvent composition in the spinning solution; Optionally, the spinning solution is deaerated and filtered before dry-spraying for preforming.

6. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that: In S4, the raw fiber is made into raw yarn through the steps of washing, drawing, oiling, drying and densification, and steam drawing.

7. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that: In S4, pre-oxidation is carried out in an air medium at a pre-oxidation temperature of 150-350°C; Optionally, in S4, carbonization is performed in an inert atmosphere or a vacuum environment, and the carbonization temperature is 1000-1600°C.

8. The method for preparing super-stretched carbon fiber according to any one of claims 1 to 7, characterized in that: In S3, the draft ratio is 5-8.

9. A carbon fiber prepared according to the method for preparing super-stretched carbon fiber according to any one of claims 1 to 8.

10. Use of the carbon fiber according to claim 9 in the field of aerospace or transportation.

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