Method for preparing ultra-drawing carbon fiber, carbon fiber and application

Abstract

The application discloses a preparation method of super-drawing carbon fibers, the carbon fibers and application, and relates to the technical field of inorganic materials. The method comprises the following steps: preparing a spinning solution with 10-40wt% of polyacrylonitrile; adding 2,4,6-triaminopyrimidine and barbituric acid into the spinning solution, and the total amount of the two accounts for 1-20wt% of the polyacrylonitrile, to obtain a spinning stock solution; after dry spraying and preforming the spinning stock solution, the spinning stock solution is put into a coagulation bath solution at 0-10 DEG C, and low-temperature coagulation bath treatment is carried out at a drawing ratio of 1-10, to obtain nascent fibers; the nascent fibers are made into original fibers, and the original fibers are made into carbon fibers through pre-oxidation and carbonization processes. The addition of the supramolecular gel promoter enables the spinning stock solution to be quickly gelled in the coagulation bath, and then high-drawing can be applied to the nascent fibers. The carbon fibers prepared through the super-drawing gel spinning technology have perfect graphite structures, good orientation and reduced defects, and the fiber strength is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic materials, in particular to a super-drawing carbon fiber preparation method and carbon fiber. BACKGROUND

[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission by the patent applicant that this information constitutes prior art.

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

[0004] In recent years, gel spinning technology has gradually attracted attention due to its unique advantages. Gel spinning technology dissolves the polymer in a suitable solvent to form a spinning dope, and then a low-temperature coagulation bath causes the spinning dope to gel to form a gel fiber. The fiber in the gelled state can withstand a higher draw ratio, thereby producing a uniform structure and excellent performance of the raw yarn.

[0005] More efficient fiber drawing technology is still a technical problem that researchers are constantly researching. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a super-drawing carbon fiber preparation method and carbon fiber. By adding a supramolecular gel promoter to the polyacrylonitrile spinning dope, the spinning dope is rapidly gelled in the coagulation bath, and then the super-drawing of the polyacrylonitrile spinning stream in the coagulation bath is realized, and finally the carbon fiber with good orientation and few defects is obtained.

[0007] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0008] The present application provides a super-drawing carbon fiber preparation method in the first aspect, comprising the following steps:

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

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

[0011] S3, after the dry spraying preforming of the spinning solution, the nascent fiber is prepared by entering the coagulation bath solution at 0-10℃ and performing low-temperature coagulation bath treatment with a draw ratio of 1-10;

[0012] S4, the nascent fiber is made into a raw silk, and the raw silk is made into a carbon fiber through a pre-oxidation and carbonization process.

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

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

[0015] Optionally, the addition amount of the end-capping agent is 1-50wt% 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, dimethyl formamide or dimethyl acetamide, 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 component in the spinning solution.

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

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

[0020] Optionally, in S4, the pre-oxidation is performed in an air medium, and the pre-oxidation temperature is 150-350℃.

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

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

[0023] In a third aspect, the above carbon fiber is applied in the fields of aerospace or transportation.

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

[0025] 1.The present application develops a new type of super-draft gel spinning technology for spinning carbon fibers, which can make the spinning dope gel quickly in the coagulation bath through the addition of supramolecular gel promoter, and then high-draft can be applied to the nascent fiber, which effectively improves the drafting effect, so that the molecular chain orientation of the nascent fiber is obviously improved, and defects such as cracks and holes are reduced. The carbon fibers prepared by the super-draft gel spinning technology have perfect graphite structure, good orientation and reduced defects, and the fiber strength is improved, which can be widely used in aerospace, transportation and other fields as reinforcing materials.

[0026] 2.In the preparation method of the present application, due to the super-draft characteristics of the gel spinning process, the draft ratio of 1-10 can be realized, which can be applied to higher spinning speed, so that the spinning production efficiency is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application, the schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0028] The mutual distance or size is exaggerated to show the position of each part in the drawing, and the schematic diagram is only used for illustration.

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

[0030] Figure 2 is a real photo of the polyacrylonitrile precursor in Example 1.

[0031] Figure 3 is a micrograph in Example 3, (A) is a micrograph of polyacrylonitrile precursor, and (B) is a micrograph of carbon fiber.

[0032] Figure 4 is a micrograph in Comparative Example 1, (A) is a micrograph of polyacrylonitrile precursor, and (B) is a micrograph of carbon fiber. DETAILED DESCRIPTION

[0033] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0034] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0035] The application will be further described below with reference to the accompanying drawings and examples.

[0036] A method for preparing an ultra-drawing carbon fiber, comprising the following steps:

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

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

[0039] S3, after dry spraying preforming the spinning stock solution, entering a coagulation bath solution at 0-10℃, and performing low-temperature coagulation bath treatment at a drawing ratio of 1-10, to obtain a nascent fiber;

[0040] S4, preparing a precursor fiber from the nascent fiber, and preparing a carbon fiber from the precursor fiber through pre-oxidation and carbonization processes.

[0041] In the above method, polyacrylonitrile is used as a precursor to prepare a spinning stock solution after dissolution. The spinning stock solution can be quickly gelled in the coagulation bath due to the addition of the supramolecular gel promoter precursor, and thus effective ultra-drawing of the nascent fiber in the coagulation bath can be realized. The nascent fiber is obtained through processes such as washing, drawing, oiling, drying and densification, and steam drawing, and the precursor fiber is then prepared into a carbon fiber through pre-oxidation and carbonization processes. The graphite structure of the carbon fiber prepared in this way has good orientation and fewer defects.

[0042] 2,4,6-triaminopyrimidine, CAS No. 1004-38-2.

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

[0044] 2,4,6-triaminopyrimidine and barbituric acid are used as small molecule precursors of the supramolecular gel promoter and are added to the spinning solution. They can be in-situ self-assembled to synthesize a supramolecular gel promoter in the spinning stock solution, can make the polyacrylonitrile spinning stream quickly gel in the low-temperature coagulation bath, and thus can realize effective ultra-drawing of the nascent fiber in the coagulation bath.

[0045] The draw ratio is the ratio of the winding speed of the as-spun fiber to the fluid extrusion speed of the spinning dope, the greater the draw ratio, the faster the spinning speed and the thinner the spinning diameter; if the draw 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, dimethyl formamide or dimethyl acetamide, which is a commonly used spinning solvent.

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

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

[0049] Optionally, in S3, the spinning dope is subjected to defoaming and filtering treatment, and then dry-jet preforming is performed.

[0050] Optionally, in S3, the solute in the coagulation bath solution is one of dimethyl sulfoxide, dimethyl formamide or dimethyl acetamide, 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 5-95%.

[0053] Optionally, in S3, after the low-temperature coagulation bath, a wet spinning process is performed to further remove the solvent inside the gelled spinning dope, and an as-spun fiber is prepared.

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

[0055] Optionally, in S4, the as-spun fiber is prepared into a precursor fiber through the processes of washing, drawing, oiling, drying densification and steam drawing.

[0056] Optionally, in S4, the pre-oxidation is performed in an air medium, and the pre-oxidation temperature is 150-350℃.

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

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

[0059] Use of the above-mentioned carbon fiber in the field of aerospace or transportation.

[0060] Example 1

[0061] An ultra-draft carbon fiber, the preparation method comprising the following steps:

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

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

[0064] S3, taking a dimethyl sulfoxide / water solution with a mass concentration of 25wt% as a coagulation bath solution, and after the spinning stock solution is subjected to conventional defoaming and filtering treatment, the spinning stock solution is dry sprayed for preforming (as shown in the photo of the dry spraying section in the spinning process Figure 1 ), and then enters the coagulation bath solution at 5℃, and a coagulation bath draft ratio is 5, to prepare a nascent fiber;

[0065] S4, gradually preparing a polyacrylonitrile precursor yarn (as shown in the photo of the polyacrylonitrile precursor yarn Figure 2 ) from the nascent fiber through processes such as water washing, drafting, oiling, drying densification, and steam drafting, and pre-oxidizing the precursor yarn in an air atmosphere at 280℃, and then carbonizing the precursor yarn in a vacuum at 1400℃ to prepare a carbon fiber, and the fiber strength of the obtained carbon fiber is about 5.5GPa.

[0066] Example 2

[0067] An ultra-draft carbon fiber, the preparation method comprising the following steps:

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

[0069] S2, adding small molecule precursors of supramolecular gel promoters including 2,4,6-triaminopyrimidine and barbituric acid to the spinning solution, the mass ratio of 2,4,6-triaminopyrimidine and barbituric acid being 1:1, and the total amount accounting for 8wt% of polyacrylonitrile, to obtain a spinning stock solution;

[0070] S3, taking a dimethyl sulfoxide / water solution with a mass concentration of 28wt% as a coagulation bath solution, and after the spinning stock solution is subjected to conventional defoaming and filtering treatment, the spinning stock solution is dry sprayed for preforming, and then enters the coagulation bath solution at 5℃, and a coagulation bath draft ratio is 6, to prepare a nascent fiber;

[0071] S4, the as-spun fiber is gradually made into a precursor fiber through water washing, drawing, oiling, drying densification, steam drawing and other processes, the precursor fiber is pre-oxidized at 280℃ in an air atmosphere, and then carbonized at 1400℃ in an inert atmosphere to make a carbon fiber, and the fiber strength of the obtained carbon fiber is about 5.7 GPa.

[0072] Among them, the difference from example 1 is that: in S1, the polyacrylonitrile concentration in the spinning solution is different, which is 21wt%; in S2, the adding amount of the small molecule precursor of the supramolecular gel promoter is different, the total amount is 8wt% of polyacrylonitrile; in S3, the concentration of coagulation bath is different, which is 28wt%; in S3, the drawing ratio of coagulation bath is different, which is 6.

[0073] Example 3

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

[0075] S1, preparing a spinning solution with dimethyl sulfoxide as the solvent and polyacrylonitrile at 19wt%;

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

[0077] S3, using a dimethyl sulfoxide / water solution with a mass concentration of 30wt% as a coagulation bath solution, the spinning stock solution is dried and sprayed after conventional defoaming and filtering treatment, then enters the coagulation bath solution at 5℃, the drawing ratio of the coagulation bath is 7, to obtain an as-spun fiber;

[0078] S4, the as-spun fiber is gradually made into a precursor fiber through water washing, drawing, oiling, drying densification, steam drawing and other processes, the precursor fiber is pre-oxidized at 280℃ in an air atmosphere, and then carbonized at 1400℃ in an inert atmosphere to make a carbon fiber, and the fiber strength of the obtained carbon fiber is about 5.9 GPa.

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

[0080] Example 4

[0081] An ultra-drawing carbon fiber, a preparation method comprising the following steps:

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

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

[0084] S3, using a dimethyl sulfoxide / water solution with a mass concentration of 32wt% as a coagulation bath solution, after the spinning stock solution is subjected to conventional defoaming and filtering treatment, the spinning stock solution is dry sprayed and pre-formed, then enters the coagulation bath solution at 5℃, the coagulation bath drawing ratio is 8, to obtain a nascent fiber;

[0085] S4, the nascent fiber is gradually made into a precursor fiber through processes such as washing, drawing, oiling, drying densification and steam drawing, the precursor fiber is pre-oxidized at 280℃ in an air atmosphere, and then carbonized at 1400℃ in an inert atmosphere to obtain a carbon fiber, the fiber strength is about 6.1GPa.

[0086] 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 the small molecule precursors of the supramolecular gel promoters is different, the total amount is 16wt% of polyacrylonitrile, and m-phenylenediamine accounting for 30% of the total amount of the precursors is added as an end-capping agent; in S3, the concentration of the coagulation bath is different, which is 32wt%; in S3, the coagulation bath drawing ratio is different, which is 8.

[0087] Comparative example 1

[0088] An ultra-drawing carbon fiber, a preparation method comprising the following steps:

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

[0090] S2, using a dimethyl sulfoxide / water solution with a mass concentration of 25wt% as a coagulation bath solution, after the spinning stock solution is subjected to conventional defoaming and filtering treatment, the spinning stock solution is dry sprayed and pre-formed, then enters the coagulation bath solution at 5℃, the coagulation bath drawing ratio is 4, to obtain a nascent fiber;

[0091] S3. The nascent fibers are gradually processed into precursor fibers through processes such as washing, stretching, oiling, drying and densification, and steam stretching. The precursor fibers are pre-oxidized in air at 280°C, and then carbonized in an inert atmosphere at 1400°C to produce carbon fibers. The resulting fibers have a strength of approximately 5.0 GPa.

[0092] The difference from Example 1 is that no supramolecular gelation promoter is added to the small molecule precursor, and no end-capping agent is added. The draw ratio in the preparation process is 4. This draw ratio is the maximum draw ratio that can be achieved in the process. If this draw ratio is exceeded, the fiber quality will begin to decline and internal defect structures will appear.

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

[0094] Microscopic observations were performed on the polyacrylonitrile precursor and carbon fibers in Example 3 and Comparative Example 1, respectively: The polyacrylonitrile precursor in Example 3 is shown in the image below. Figure 3 As shown in (A), carbon fiber products are as follows: Figure 3 As shown in (B) of Comparative Example 1, the polyacrylonitrile precursor fiber is as follows: Figure 4 As shown in (A), carbon fiber products are as follows Figure 4 As shown in (B) in the diagram.

[0095] It can be seen that, due to the adoption of the technical solution of the present invention, Example 3 can use a larger draw ratio in the preparation process, thus enabling the stable preparation of polyacrylonitrile precursor fibers with a smaller diameter than those in Comparative Example 1 while ensuring quality. Consequently, the diameter of the prepared carbon fibers is also finer than that of Comparative Example 1. Although the surface quality of the fibers in Example 3 and Comparative Example 1 is similar, the carbon fibers obtained in Example 3 have a finer diameter. Therefore, products woven or prepared using the fibers of Example 3 as raw materials have higher strength and can be used as reinforcing materials in aerospace, transportation, and other fields.

[0096] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing super-drawn carbon fibers, characterized in that, Includes the following steps: S1. Prepare a spinning solution with 10~40 wt% polyacrylonitrile; S2. Add 2,4,6-triaminopyrimidine and barbituric acid to the spinning solution, with a mass ratio of 2,4,6-triaminopyrimidine to barbituric acid of 1:(0.5~1.5), and the total amount of the two is 1~20wt% of polyacrylonitrile, to obtain the spinning solution. S3. After the spinning solution is pre-formed by dry spraying, it is placed in a coagulation bath solution at 0~10℃ and subjected to low-temperature coagulation bath treatment with a draw ratio of 1~10 to obtain nascent fibers. S4. The nascent fibers are made into precursor fibers, and the precursor fibers are made into carbon fibers through pre-oxidation and carbonization processes.

2. The method for preparing super-drawn 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-drawn carbon fiber according to claim 1, characterized in that, In S2, a capping agent is added to the spinning solution. The capping agent includes one or more of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine.

4. The method for preparing super-drawn carbon fiber according to claim 3, characterized in that, The amount of capping agent added is 1 to 50 wt% of the total amount of 2,4,6-triaminopyrimidine and barbituric acid.

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 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.

6. The method for preparing super-drawn carbon fiber according to claim 5, characterized in that, The mass fraction of the solute in the coagulation bath solution is 5-95%.

7. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that, In S3, the solute in the coagulation bath solution has the same composition as the solvent in the spinning solution.

8. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that, The spinning solution is deaerated and filtered, and then dry-sprayed for preforming.

9. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that, In S4, nascent fibers are processed into raw yarn through washing, stretching, oiling, drying and densification, and steam stretching processes.

10. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that, In S4, pre-oxidation is carried out in air medium at a temperature of 150-350℃.

11. The method for preparing super-drawn carbon fiber according to claim 1, characterized in that, In S4, carbonization is carried out in an inert atmosphere or vacuum environment, and the carbonization temperature is 1000~1600℃.

12. A carbon fiber prepared by the method for preparing super-drawn carbon fiber according to any one of claims 1-11.

13. An application of the carbon fiber of claim 12 in the aerospace or transportation field.

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