A hydrophilic carbon fiber spinning solution and its airflow spinning method
By introducing liquid melamine phosphate to prepare hydrophilic carbon spinning solution, and employing airflow spinning and high-temperature carbonization processes, the problem of poor performance of hydrophilic carbon fiber materials in traditional methods was solved, and efficient and low-cost preparation of hydrophilic carbon nanofibers was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2026-04-03
AI Technical Summary
Hydrophilic carbon fiber materials prepared by traditional methods are difficult to meet the industry requirements in fields such as catalysis, energy and water treatment, and the surface treatment technology is not effective.
Hydrophilic carbon spinning solution was prepared by introducing liquid melamine phosphate, and carbon nanofibers with excellent hydrophilicity without surface treatment were prepared by using airflow spinning method combined with high-temperature carbonization process.
The efficient preparation of hydrophilic carbon nanofibers has been achieved. The fiber structure is dense and the surface maintains good hydrophilicity, making it suitable for large-scale production at low cost.
Smart Images
Figure CN119507069B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon fiber preparation technology, and in particular relates to a hydrophilic carbon fiber spinning solution and its airflow spinning method. Background Technology
[0002] Carbon fiber, due to its high modulus, high tensile strength, corrosion resistance, good acid and alkali resistance, and excellent mechanical properties, has been widely used in many fields such as aerospace, automotive manufacturing, and sporting goods. However, the strong hydrophobic properties of traditional carbon nanofibers limit their practical effectiveness and efficiency in many potential applications. The large-scale preparation of hydrophilic carbon fibers is of great value. As filter and electrode materials, hydrophilic carbon fibers exhibit excellent adsorption capacity and conductivity. This unique hydrophilic property significantly enhances the application value of materials in water treatment, energy storage, and biomedicine. Furthermore, hydrophilic carbon fibers can significantly improve interfacial bonding in composite materials, thereby enhancing the overall mechanical properties of the materials.
[0003] Most methods for preparing hydrophilic carbon fibers involve plasma modification, plasma treatment, surface coating, and high-temperature treatment. The main principle is to use modifying materials to modify the surface of non-hydrophilic carbon fibers. However, most of the above modification techniques are applicable to carbon fiber surface treatment and adopt a two-step strategy of spinning and post-treatment. However, the prepared carbon fiber materials have poor hydrophilicity. With the development of fields such as catalysis, energy, and water treatment, hydrophilic carbon fiber materials prepared by traditional surface treatment techniques can no longer meet the industry's needs, which greatly limits the development of carbon fiber materials. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hydrophilic carbon fiber spinning solution and its air-jet spinning method. The hydrophilic carbon nanofibers prepared by introducing liquid melamine phosphate to prepare the spinning solution and then performing blowing and high-temperature carbonization do not require surface treatment and can still maintain excellent hydrophilicity.
[0005] This invention is achieved through the following technical solution:
[0006] The first aspect of this invention provides a hydrophilic carbon fiber spinning solution, which is prepared by adding a precursor spinning material to N,N-dimethylformamide (DMF), followed by modification with liquid melamine phosphate. The mass ratio of the precursor spinning material, liquid melamine phosphate, and N,N-dimethylformamide is 10–20:3–6:90–110. The liquid melamine phosphate is prepared by modifying a phosphate additive in liquid melamine resin and stirring magnetically for 2 hours to obtain a homogeneous mixture. The mass ratio of the liquid melamine resin to the phosphate additive is 1:3–6.
[0007] Furthermore, the precursor spinning raw material is one or two of polyacrylonitrile and lignin.
[0008] A second aspect of the present invention provides an air-jet spinning method for the above-mentioned hydrophilic carbon fiber spinning solution, comprising the following steps:
[0009] (1) The hydrophilic carbon fiber spinning solution is transferred into an injection pump and solution blow spinning is performed to obtain precursor fiber cotton.
[0010] (2) After drying the precursor fiber cotton, it is carbonized at 400-800℃ in a nitrogen environment to obtain hydrophilic carbon nanofibers.
[0011] Furthermore, during the solution-blown spinning process, the spinning parameters are set as follows: spinning air pressure is 0.2-0.4 MPa, spinning flow rate is stable at 10-30 mL / h, and spinning distance is 30 cm.
[0012] Furthermore, the drying process specifically involves placing the precursor fibers in a drying oven at 50–60°C for 10–20 hours. The main purpose of this process is to remove residual solvents and moisture from the fibers to ensure structural stability and consistent performance. Prolonged drying effectively reduces the moisture content of the fibers, preventing fiber deformation, performance degradation, or other adverse effects caused by residual moisture during subsequent processing.
[0013] Furthermore, the dried precursor fiber cotton is placed in a muffle furnace for pre-oxidation at 220–260°C, followed by carbonization. The purpose of pre-oxidation is that in air, the fiber surface reacts with oxygen to form oxygen-containing functional groups (such as carboxyl, alcohol, and aldehyde groups). The formation of these functional groups helps improve the structural stability of the fiber during subsequent carbonization and reduces volume shrinkage and fiber breakage during high-temperature carbonization, significantly enhancing the mechanical properties of carbon nanofibers.
[0014] Furthermore, the carbonization heating rate is 4–8 °C / min, and the carbonization time is 0.5–2 h. The main purpose of this high-temperature treatment step is to perform carbonization or sintering to obtain carbon nanofibers with good hydrophilic properties. Carbonization temperatures below 400 °C result in low carbonization levels, leading to poor mechanical properties of the prepared hydrophilic carbon nanofibers. Temperatures above 800 °C increase graphitization and decrease hydrophilicity. Carbonization between 400 and 800 °C ensures that the carbon nanofibers possess good hydrophilicity.
[0015] The third aspect of the present invention provides a method for preparing hydrophilic carbon nanofibers, wherein the above-mentioned hydrophilic carbon fiber spinning solution is transferred into an injection pump and subjected to solution blow spinning to obtain precursor fiber cotton. After drying the precursor fiber cotton, it is pre-oxidized at 220-260°C and then carbonized at 400-800°C in a nitrogen environment to obtain hydrophilic carbon nanofibers.
[0016] A fourth aspect of the present invention provides a hydrophilic carbon nanofiber prepared by the method described above.
[0017] This application proposes a DMF-soluble liquid melamine phosphate ester prepared using liquid melamine resin as the matrix and adding phosphoric acid as a modifying agent. Compared with commercial melamine materials, this effectively avoids the problem of increased spinning solution viscosity caused by the addition of common nano-melamine powder to the solution, which makes the spinning process difficult. The liquid melamine phosphate ester of this application exhibits better solubility in DMF solvent, effectively reducing the viscosity of the spinning solution. Specifically, when the liquid melamine phosphate ester is introduced into PAN / DMF precursor spinning solutions and lignin / PAN / DMF precursor spinning solutions, the formaldehyde groups in the melamine phosphate ester combine with the side chains of phosphoric acid to form hydrophilic groups. The formation of this hydrophilic group not only improves the stability of the spinning solution but also significantly enhances spinning efficiency and fiber quality. By using solution-blown spinning technology combined with a carbonization process at 400–800℃, large-scale and efficient preparation of hydrophilic carbon nanofibers can be achieved. Melamine phosphate itself can be carbonized to form carbon fiber materials. During the calcination process, it synergistically enhances the density of hydrophilic carbon nanofibers with polyacrylonitrile and lignin, thereby improving their hydrophilic properties.
[0018] The advantages and positive effects of this invention are:
[0019] (1) The present invention effectively reduces the viscosity of the spinning solution and improves its stability by introducing a spinning solution prepared by liquid melamine phosphate, thereby improving spinning efficiency and fiber quality.
[0020] (2) The airflow spinning method of the present invention prepares hydrophilic carbon nanofibers with a dense structure by solution spray spinning and carbonization of the spinning solution. The fiber surface can maintain excellent hydrophilicity without treatment, which has extremely high application value.
[0021] (3) The preparation method of the hydrophilic carbon fiber of the present invention is simple, low in cost, and can be mass-produced. Attached Figure Description
[0022] Figure 1 SEM image of the carbon nanofibers prepared in Example 1;
[0023] Figure 2 A macroscopic photograph of the carbon nanofibers prepared in Example 1;
[0024] Figure 3 SEM image of the carbon nanofibers prepared in Example 2;
[0025] Figure 4 Macroscopic photograph of the carbon nanofibers prepared in Example 2;
[0026] Figure 5 The diagram shows the water absorption process of the carbon nanofibers prepared in Example 1 (water stained with a fluorescent agent);
[0027] Figure 6 The diagram shows the water absorption process of the carbon nanofibers prepared in Example 2 (water stained with a fluorescent agent);
[0028] Figure 7 SEM image of the carbon nanofibers prepared in Comparative Example 1.
[0029] Figure 8 Hydrophobic diagram of PAN-based carbon nanofibers prepared in Comparative Example 1;
[0030] Figure 9 SEM image of the carbon nanofibers prepared for Comparative Example 2;
[0031] Figure 10 SEM image of the carbon nanofibers prepared in Comparative Example 3.
[0032] Figure 11 The water contact angle of PAN / melamine hydrophilic carbon nanofibers prepared with liquid melamine phosphate in Example 1 after carbonization at 800 degrees Celsius for 1 hour in a nitrogen atmosphere;
[0033] Figure 12 Example 3 shows the water contact angle of PAN / melamine hydrophilic carbon nanofibers prepared from liquid melamine phosphate after carbonization at 400 degrees Celsius for 1 hour in a nitrogen atmosphere;
[0034] Figure 13The water contact angle of PAN / melamine hydrophilic carbon nanofibers prepared with liquid melamine phosphate in Comparative Example 3 after carbonization at 1200 degrees Celsius for 1 hour in a nitrogen atmosphere.
[0035] Figure 14 Example 2 shows the water contact angle of lignin / PAN / melamine hydrophilic carbon nanofibers prepared with liquid melamine phosphate after carbonization at 800 degrees Celsius for 1 hour in a nitrogen atmosphere.
[0036] Figure 15 Example 4 shows the water contact angle of lignin / PAN / melamine hydrophilic carbon nanofibers prepared with liquid melamine phosphate after carbonization at 400 degrees Celsius for 1 hour in a nitrogen atmosphere.
[0037] Figure 16 The water contact angle of lignin / PAN / melamine hydrophilic carbon nanofibers prepared with liquid melamine phosphate in Comparative Example 4 after carbonization at 1200 degrees Celsius for 1 hour in a nitrogen atmosphere. Detailed Implementation
[0038] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.
[0039] Example 1
[0040] An air-jet spinning method for a hydrophilic carbon fiber spinning solution includes the following steps:
[0041] (1) Preparation of liquid melamine phosphate: 10g of liquid melamine resin and 50g of modified phosphate were mixed with magnetic stirring for 2h to prepare a uniformly mixed liquid melamine phosphate.
[0042] (2) Weigh 10g of polyacrylonitrile, 5g of liquid melamine phosphate, and 100g of NN-dimethylformamide. Stir with a magnetic stirrer for 2 hours and mix evenly to prepare a hydrophilic carbon fiber spinning solution with good spinning viscosity.
[0043] (3) The hydrophilic carbon fiber spinning solution was transferred into an injection pump, and the precursor fiber cotton was prepared by solution jet spinning. The spinning parameters were set as follows: spinning air pressure was 0.2 MPa, spinning rate was 10 mL / h, and spinning distance was 30 cm.
[0044] (4) The prepared precursor fiber cotton was dried and then placed in a tube furnace for carbonization at 800℃ under nitrogen atmosphere. The heating rate of carbonization was 5℃ / min and the holding time was 1h, finally obtaining carbon nanofibers with good hydrophilic properties.
[0045] SEM image of the carbon nanofibers prepared in Example 1 is shown below. Figure 1 As shown, macroscopic photos are as follows Figure 2 As shown, the water absorption process is as follows Figure 5 As shown.
[0046] Example 2
[0047] The difference from Example 1 is that step (2) is: weigh 15g of lignin, 5g of polyacrylonitrile, 5g of liquid melamine phosphate, 100g of NN-dimethylformamide, stir with a magnetic stirrer for 2 hours, and mix evenly to prepare a hydrophilic carbon fiber spinning solution with good spinning viscosity.
[0048] SEM image of the carbon nanofibers prepared in Example 2 is shown below. Figure 3 As shown, macroscopic photos are as follows Figure 4 As shown, the water absorption process is as follows Figure 6 As shown.
[0049] Example 3
[0050] The only difference from Example 1 is that the carbonization temperature is 400°C.
[0051] Example 4
[0052] The only difference from Example 2 is that the carbonization temperature is 400°C.
[0053] Comparative Example 1
[0054] The difference from Example 1 is that step (1) is omitted and liquid melamine phosphate is not added in step (2).
[0055] SEM image of PAN-based carbon nanofibers prepared in Comparative Example 1 is shown below. Figure 7 As shown, the hydrophobic diagram is as follows Figure 8 As shown.
[0056] Comparative Example 2
[0057] The difference from Example 1 is in steps (1) and (2):
[0058] (1) Weigh 10g of powdered melamine and 50g of DMF, and stir with a magnetic stirrer for 2h to prepare a uniformly mixed melamine solution.
[0059] (2) Weigh 10g of polyacrylonitrile, 5g of melamine solution, and 100g of N,N-dimethylformamide. Stir with a magnetic stirrer for 2 hours and mix evenly to prepare a hydrophilic carbon fiber spinning solution.
[0060] SEM images of the carbon nanofibers prepared in Comparative Example 2 are shown below. Figure 9 As shown.
[0061] Comparative Example 3
[0062] The difference from Example 2 is in steps (1) and (2).
[0063] (1) Weigh 10g of powdered melamine and 50g of DMF, and stir with a magnetic stirrer for 2h to prepare a uniformly mixed melamine solution.
[0064] (2) Weigh 15g of lignin, 5g of polyacrylonitrile, 5g of melamine solution, and 100g of N,N-dimethylformamide. Stir with a magnetic stirrer for 2 hours and mix evenly to prepare a hydrophilic carbon fiber spinning solution.
[0065] SEM images of the carbon nanofibers prepared in Comparative Example 3 are shown below. Figure 10 As shown.
[0066] Comparative Example 3
[0067] The only difference from Example 1 is that the carbonization temperature is 1200°C.
[0068] Comparative Example 4
[0069] The only difference from Example 2 is that the carbonization temperature is 1200°C.
[0070] Performance and Testing
[0071] The carbon nanofibers prepared in Examples 1, 2, and Comparative Examples 1-3 were subjected to electron microscopy. The SEM image of the carbon nanofibers prepared in Example 1 is shown below. Figure 1 As shown; SEM image of the carbon nanofibers prepared in Example 2 is shown. Figure 3 As shown; SEM image of the carbon nanofibers prepared in Comparative Example 1 is shown. Figure 7 As shown; SEM image of the carbon nanofibers prepared in Comparative Example 2 is shown. Figure 9 As shown; SEM image of the carbon nanofibers prepared in Comparative Example 3 is shown. Figure 10 As shown; comparison Figure 1 and Figure 9 , Figure 3 and Figure 10 As can be seen, the carbon nanofibers prepared by introducing liquid melamine phosphate into PAN / DMF precursor spinning solution and lignin / PAN / DMF precursor spinning solution have smooth surfaces and uniform diameter distribution. In contrast, carbon nanofibers prepared using powdered melamine powder exhibit internal agglomeration and uneven diameter distribution. Figure 7 The carbon nanofibers prepared without the addition of liquid melamine phosphate have a sparse internal structure. This indicates that the introduction of liquid melamine phosphate in this application, during the calcination process, synergistically enhances the density of hydrophilic carbon nanofibers with polyacrylonitrile and lignin, thereby increasing the internal density of carbon nanofibers, reducing internal agglomeration, and thus improving hydrophilic properties.
[0072] Water contact testing was performed using an OCA15EC contact angle analyzer (Data-physics, Germany). Water droplets of the same size were dropped onto the fiber surface, and the angle formed by the water droplets and the diffusion rate were observed. Examples 1, 3, and Comparative Example 3 used PAN / melamine hydrophilic carbon nanofibers prepared from liquid melamine phosphate, such as… Figure 11-13 As shown, the hydrophilicity of fibers is characterized by the diffusion rate of water droplets on the fiber felt surface. Water droplets on the surface of PAN / melamine hydrophilic carbon nanofibers prepared by carbonization at 400°C for 1 hour in a nitrogen atmosphere are completely absorbed within 11 ms, while water droplets on the surface of fibers carbonized at 800°C are completely diffused within 63 ms. However, the degree of graphitization of fibers obtained after carbonization at 1200°C increases, hydrophilicity decreases, and surface moisture is not completely diffused for 71 s.
[0073] The water contact angle of lignin / PAN / melamine hydrophilic carbon nanofibers prepared from liquid melamine phosphate in Examples 2, 4, and Comparative Example 4 was tested. Figures 14-16 As shown, carbon nanofibers prepared at 400℃ and 800℃ exhibit good hydrophilicity at their contact angles, but this hydrophilicity decreases as the temperature rises to 1200℃ due to increased graphitization. Figure 14-16 As shown, the hydrophilicity of fibers is characterized by the diffusion rate of water droplets on the fiber felt surface. Water droplets on the surface of lignin / PAN / melamine hydrophilic carbon nanofibers prepared from liquid melamine phosphate and carbonized at 400°C for 1 hour in a nitrogen atmosphere were completely absorbed within 16 ms, while water droplets on the surface of fibers carbonized at 800°C were completely diffused within 82 ms. However, the degree of graphitization of fibers obtained after carbonization at 1200°C increased, resulting in decreased hydrophilicity; the water on the fiber surface did not completely diffuse until 71 s later.
[0074] Water absorption tests were conducted on Examples 1 and 2, such as... Figure 5 , Figure 6 As shown, water was stained with a fluorescent agent and then absorbed. It can be seen that the fiber, after hydrophilic modification with liquid melamine phosphate, exhibits significantly enhanced hydrophilicity, enabling rapid anti-gravity water transport. Water droplets were placed on the PAN-based carbon nanofibers prepared in Comparative Example 1, as shown... Figure 8 As shown, the carbon nanofibers prepared without liquid melamine phosphate have high hydrophobicity and absorb almost no water. This also indicates that adding liquid melamine phosphate can improve the water absorption of carbon nanofibers.
[0075] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept, and these all fall within the protection scope of the present invention.
Claims
1. A hydrophilic carbon fiber spinning solution, characterized in that, The hydrophilic carbon fiber spinning solution is prepared by adding precursor spinning raw materials to N,N-dimethylformamide, followed by modification with liquid melamine phosphate. The mass ratio of precursor spinning raw materials, liquid melamine phosphate, and N,N-dimethylformamide is 10~20:3~6:90~110. The liquid melamine phosphate is prepared by adding phosphoric acid, a modifying agent, to liquid melamine resin and stirring magnetically for 2 hours to obtain a homogeneous mixture. The mass ratio of liquid melamine resin to phosphoric acid is 1:3~6. The air-jet spinning method for the hydrophilic carbon fiber spinning solution includes the following steps: (1) The hydrophilic carbon fiber spinning solution is transferred into an injection pump and solution blow spinning is performed to obtain precursor fiber cotton. (2) After drying the precursor fiber cotton, it is placed in a muffle furnace for pre-oxidation at 220~260℃, and then carbonized at 400~800℃ in a nitrogen environment to obtain hydrophilic carbon nanofibers. Liquid melamine phosphate is introduced, which, in the calcination process, works synergistically with polyacrylonitrile and lignin to enhance the internal density of carbon nanofibers, reduce internal fiber aggregation, and improve hydrophilicity.
2. The hydrophilic carbon fiber spinning solution according to claim 1, characterized in that, The precursor spinning raw material is one or two of polyacrylonitrile and lignin.
3. The hydrophilic carbon fiber spinning solution according to claim 1, characterized in that, During the solution-blown spinning process, the spinning parameters are set as follows: spinning air pressure is 0.2-0.4 MPa, spinning flow rate is stable at 10-30 mL / h, and spinning distance is 30 cm.
4. The hydrophilic carbon fiber spinning solution according to claim 1, characterized in that, The drying process specifically involves placing the precursor fibers in a drying oven at 50-60°C for 10-20 hours.
5. The hydrophilic carbon fiber spinning solution according to claim 1, characterized in that, The carbonization heating rate is 4~8℃ / min, and the carbonization time is 0.5~2h.
6. A method for preparing hydrophilic carbon nanofibers, characterized in that, The hydrophilic carbon fiber spinning solution described in any one of claims 1 to 5 is transferred into an injection pump and subjected to solution blow spinning to obtain precursor fiber cotton. After drying the precursor fiber cotton, it is pre-oxidized at 220 to 260°C and then carbonized at 400 to 800°C in a nitrogen environment to obtain hydrophilic carbon nanofibers.
7. A hydrophilic carbon nanofiber prepared according to the method of claim 6.