High-bulk-density single-walled carbon nanotube powder and preparation method thereof
By incomplete drying and crushing treatment of single-wall carbon nanotube block wet material, the problem of low bulk density is solved, the density is improved and the crushing loss and pollution is reduced, and efficient single-wall carbon nanotube powder preparation is achieved.
Patent Information
- Application Number
- CN202310745842.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-21
- Publication Date
- 2024-12-24
AI Technical Summary
The low bulk density of single-wall carbon nanotubes leads to powder dissipation pollution, transportation difficulties and electrical conductivity. The existing extrusion granulation methods introduce metal impurities and increase equipment costs.
Incompletely dry bulk wet material is used for crushing and re-drying. Metal impurities are removed by acid washing and humidity are controlled to increase the bulk density, avoiding losses and impurities introduction during the crushing process.
The bulk density of single-wall carbon nanotubes is improved, the energy consumption and cost of crushing is reduced, the powder pollution and transportation costs are reduced, and the conductivity is maintained.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of single-walled carbon nanotubes, and more specifically, to a single-walled carbon nanotube powder with high packing density and a preparation method thereof. Background Art
[0002] Carbon nanotubes (CNTs), tubular nano-scale graphite crystals, are seamless nano-scale tubes formed by curling single or multi-layer graphite sheets around a central axis at a certain spiral angle, forming a cylindrical surface with a hexagonal plane. Since carbon nanotube powder has a low bulk density, a large amount of powder will float in the environment during use, which will not only pollute the environment, but may also cause circuit short circuits and electrical failures, and may also cause damage to the human respiratory tract. In addition, the low bulk density of carbon nanotubes will also increase the difficulty of transporting carbon nanotube powder, such as increasing transportation costs.
[0003] For the above reasons, in the prior art, multi-walled carbon nanotube powder is generally subjected to extrusion granulation treatment to increase the packing density of carbon nanotubes. In conventional granulation methods, it can be divided into dry granulation and wet granulation. However, the granulation process requires the addition of granulation-related equipment, and the granulation process will also introduce metal impurities or foreign matter; at the same time, the granulated material will also increase the difficulty of dispersing carbon nanotubes during the use process such as preparing slurry, which will affect the use of carbon nanotubes. For single-walled carbon nanotubes, their packing density is very low (<0.01g / cm 3 ), the material formed after extrusion granulation will cause great difficulties in the dispersion process and affect the conductivity of single-walled carbon nanotubes. Summary of the invention
[0004] In order to improve the packing density and yield, the present application provides a high packing density single-walled carbon nanotube powder and a preparation method thereof.
[0005] In a first aspect, the present application provides a single-walled carbon nanotube powder with a high bulk density, which adopts the following technical scheme: a single-walled carbon nanotube powder with a high bulk density, wherein the single-walled carbon nanotube primary powder is acid-washed to obtain a single-walled carbon nanotube block wet material, the single-walled carbon nanotube block wet material is incompletely dried to obtain an incompletely dried single-walled carbon nanotube block wet material, the incompletely dried single-walled carbon nanotube block wet material is crushed and re-dried to obtain the single-walled carbon nanotube powder, wherein the bulk density of the single-walled carbon nanotube powder is 0.1 to 0.5 g / cm 3 .
[0006] The above technical solution is to use incompletely dried block wet materials for crushing, which solves the problem that single-walled carbon nanotubes in a dried state are difficult to crush and easy to be lost during the crushing process, and at the same time improves the packing density of single-walled carbon nanotubes.
[0007] Wherein, the humidity of the incompletely dried single-walled carbon nanotube block wet material is calculated according to Formula 1; Formula 1: Wherein, M1 is the mass of the single-walled carbon nanotube bulk wet material after acid washing, M2 is the mass of the single-walled carbon nanotube bulk wet material after incomplete drying, and m is the mass of the single-walled carbon nanotube after re-drying.
[0008] Preferably, the humidity of the incompletely dried single-walled carbon nanotube block wet material is not greater than 1, more preferably 10%-90%, further preferably 15-90%, further preferably 40-90%.
[0009] Preferably, the drying time in the incomplete drying is 1 to 6 hours, preferably 1 to 3 hours.
[0010] Preferably, the pulverizing time is 0.1 to 8 minutes, preferably 3 to 5 minutes; too long a pulverizing time results in incomplete drying of the single-walled carbon nanotube wet material, resulting in large agglomerations.
[0011] In a second aspect, the present application provides a method for preparing single-walled carbon nanotube powder with high packing density, using the following technical solution: A method for preparing single-walled carbon nanotube powder with high stacking density comprises the following steps: (1) Acid washing: acid washing and filtering the single-walled carbon nanotube primary powder to obtain a single-walled carbon nanotube bulk wet material; (2) Incomplete drying: Incompletely drying the single-walled carbon nanotube bulk wet material to obtain an incompletely dried single-walled carbon nanotube bulk wet material; (3) crushing: crushing the incompletely dried single-walled carbon nanotube block wet material to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after pulverization is fully dried to obtain single-walled carbon nanotube powder with high bulk density.
[0012] The filtration in the acid washing in step (1) can be suction filtration or pressure filtration, so as to press the single-walled carbon nanotubes into a block of wet material, thereby better controlling the morphology of the single-walled carbon nanotubes and facilitating subsequent crushing.
[0013] In addition, the acid washing in step (1) can remove metal impurities in the preparation process of the single-walled carbon nanotubes and improve the purity, especially the metal impurity iron. The iron content after acid washing is less than 8000 ppm.
[0014] Preferably, the acid used in the pickling in step (1) is one or a mixture of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid or dilute hydrofluoric acid.
[0015] The incomplete drying state in step (2) can be understood as the state of incomplete drying of the single-walled carbon nanotube block wet material after acid washing and purification. The purpose is to control the humidity of the incompletely dried single-walled carbon nanotube block wet material, so as to facilitate the problem of difficult pulverization and loss of single-walled carbon nanotubes during subsequent pulverization. This step plays a key role in the high bulk density of carbon nanotube materials formed after pulverization and drying.
[0016] Preferably, the drying temperature in the incomplete drying in step (2) is 50°C to 110°C, preferably 50 to 90°C.
[0017] Preferably, the pulverizing equipment in the step (3) is a small grinder, an ultrafine grinder or a combination of one or more of a multifunctional grinder.
[0018] Preferably, the weight loss rate of the single-walled carbon nanotube powder at 100-300° C. is 0.5-8.0%.
[0019] In summary, this application has the following beneficial effects: 1. The present application crushes the wet block of single-walled carbon nanotubes by incomplete drying, which not only reduces the energy consumption of the crushing equipment and saves costs; it also reduces the loss of single-walled carbon nanotubes during the crushing process, improves the yield, and avoids the pollution to the environment and even damage to the human body caused by the dispersion of powder during the crushing process.
[0020] 2. The present application adopts the method of crushing the incompletely dried single-walled carbon nanotube block wet material and then drying it, thereby increasing the packing density of the single-walled carbon nanotube powder in a completely dry state and reducing the transportation cost of the powder.
[0021] 3. In this application, there is no need to introduce specific granulation equipment, thus avoiding the possibility of introducing other metal impurities. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 The process flow chart of single-walled carbon nanotube preparation is shown below; Figure 2 Comparison of the physical volumes of high bulk density single-walled carbon nanotubes (left) and conventional crushed single-walled carbon nanotubes (right) at the same mass (2g); Figure 3 This is a photo of the wet single-walled carbon nanotube material that is not completely dried after the crushing time is too long (10 minutes); Figure 4 This is the TG test result of single-walled carbon nanotube powder in air atmosphere. DETAILED DESCRIPTION
[0023] Embodiment 1: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 50°C drying oven and dry it for 3 h before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into an ultrafine grinder and grind it for 5 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, a single-walled carbon nanotube powder material with a high bulk density is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0024] Embodiment 2: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 70°C drying oven and dry it for 2 h before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into an ultrafine grinder and grind it for 4 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, a single-walled carbon nanotube powder material with a high bulk density is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0025] Embodiment 3: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 90°C drying oven and dry it for 1 hour before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into an ultrafine grinder and grind it for 3 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, a single-walled carbon nanotube powder material with a high bulk density is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0026] Embodiment 4: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 70°C drying oven and dry it for 2.5 hours before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into an ultrafine grinder and grind it for 5 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, a single-walled carbon nanotube powder material with a high bulk density is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0027] Embodiment 5: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a drying oven at 80°C and dry it for 3 hours before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into an ultrafine grinder and grind it for 4 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, a single-walled carbon nanotube powder material with a high bulk density is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0028] Comparative Example 1: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Complete drying: Place the wet SWNT block material in a 90°C drying oven and dry it for 10 h before taking it out to obtain a completely dried SWNT material. Record the mass m. (3) Crushing: The completely dried single-walled carbon nanotube material is placed in an ultrafine grinder and crushed for 6 minutes to obtain a completely dried single-walled carbon nanotube powder material after crushing and perform a bulk density test; Comparative Example 2: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 90°C drying oven and dry it for 1 hour before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into a multifunctional crusher and crush it for 10 minutes to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, the single-walled carbon nanotube powder material is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0029] Observe the state of the wet material after grinding. The material agglomerates obviously due to the long grinding time.
[0030] Comparative Example 3: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a 90°C drying oven and dry it for 5 min before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the incompletely dried single-walled carbon nanotube block wet material into a multifunctional crusher for crushing. Since the incompletely dried single-walled carbon nanotube block wet material will precipitate water when slightly squeezed, it is actually impossible to crush it; (4) Re-drying: The incompletely dried single-walled carbon nanotube block wet material after crushing is placed in a blast drying oven, and the single-walled carbon nanotube powder material is obtained after being fully dried. The mass m is recorded and the bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0031] When the humidity of the incompletely dried single-walled carbon nanotube block wet material is higher than 90%, the material contains obvious water, and water will precipitate out with a slight squeeze. The material cannot be crushed and then dried, and the packing density cannot be effectively improved after the material is completely dried.
[0032] Comparative Example 4: (1) Acid washing: The single-walled carbon nanotube powder is acid washed with dilute sulfuric acid and then filtered to obtain a single-walled carbon nanotube block wet material, and the mass M1 is recorded; (2) Incomplete drying: Place the wet SWNT block material in a drying oven at 90°C and dry for 3 hours before taking it out to obtain the incompletely dried SWNT block material. Record the mass M2. (3) Crushing: Put the wet block of incompletely dried single-walled carbon nanotubes into a multifunctional crusher and crush for 3 minutes; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after crushing is placed in a blast drying oven, and after being fully dried, the single-walled carbon nanotube powder material is obtained, and the mass m is recorded and a bulk density test is performed; According to the formula: The humidity of the incompletely dried single-walled carbon nanotube bulk wet material was calculated.
[0033] The TG purity test was performed on the above-mentioned Examples 1-5 and Comparative Examples 1-4. The test conditions were to detect the purity of the carbon nanotubes at 800° C. in an air atmosphere, as shown in Table 1.
[0034] The test results are shown in Table 1: Table 1 As shown in Table 1, the embodiments show that under different temperature and drying time conditions, different humidity levels of incompletely dried single-walled carbon nanotube block wet materials are obtained. After the wet materials at different humidity are crushed and re-dried, single-walled carbon nanotube powders with different bulk densities are obtained.
[0035] By comparing Example 3 with Comparative Examples 1 and 4, it can be seen that the acid-washed single-walled carbon nanotube block wet material in Comparative Example 1 does not undergo an incomplete drying step but is directly dried, and the resulting bulk density is greatly reduced from 0.47 g / cm 3 Reduced to 0.01g / cm 3 Although the comparative example 4 was incompletely dried, the humidity of the incompletely dried single-walled carbon nanotube block wet material was less than 10%, and the bulk density was only 0.014 g / cm 3 This shows that the packing density of single-walled carbon nanotubes can only be improved by not completely drying them and keeping them within a certain humidity range before crushing.
[0036] By comparing Example 3 with Comparative Example 2, it can be seen that when the crushing time exceeds 8 minutes, the long crushing time will lead to agglomeration of incompletely dried single-walled carbon nanotube block wet materials, resulting in the inability to test the bulk density and fail to solve the technical problems described in this application.
[0037] By comparing Example 3 with Comparative Example 3, it can be seen that if the humidity of the incompletely dried single-walled carbon nanotube block wet material is greater than 90%, the material cannot be crushed.
[0038] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A single-walled carbon nanotube powder with high bulk density, characterized in that: The single-walled carbon nanotube primary powder is acid-washed to obtain a single-walled carbon nanotube block wet material, the single-walled carbon nanotube block wet material is incompletely dried to obtain an incompletely dried single-walled carbon nanotube block wet material, the incompletely dried single-walled carbon nanotube block wet material is crushed and dried again to obtain the single-walled carbon nanotube powder, and the bulk density of the single-walled carbon nanotube powder is 0.1-0.5 g / cm 3 .
2. The high bulk density single-walled carbon nanotube powder according to claim 1, characterized in that: The humidity of the incompletely dried single-walled carbon nanotube block wet material is calculated according to Formula 1: Formula 1: Wherein, M1 is the mass of the single-walled carbon nanotube bulk wet material after acid washing, M2 is the mass of the single-walled carbon nanotube bulk wet material after incomplete drying, and m is the mass of the single-walled carbon nanotube after re-drying.
3. The high bulk density single-walled carbon nanotube powder according to claim 2, characterized in that: The humidity of the incompletely dried single-walled carbon nanotube block wet material is not greater than 1.
4. The high bulk density single-walled carbon nanotube powder according to claim 3, characterized in that: The humidity of the incompletely dried single-walled carbon nanotube block wet material is 10%-90%.
5. The high bulk density single-walled carbon nanotube powder according to claim 1, characterized in that: The drying time in the incomplete drying is 1 to 6 hours.
6. The high bulk density single-walled carbon nanotube powder according to claim 1, characterized in that: The crushing time is 0.1-8min.
7. The method for preparing single-walled carbon nanotube powder with high bulk density according to claim 1, characterized in that: The steps include: (1) Acid washing: acid washing and filtering the single-walled carbon nanotube primary powder to obtain a single-walled carbon nanotube bulk wet material; (2) Incomplete drying: Incompletely drying the single-walled carbon nanotube bulk wet material to obtain an incompletely dried single-walled carbon nanotube bulk wet material; (3) crushing: crushing the incompletely dried single-walled carbon nanotube block wet material to obtain a crushed incompletely dried single-walled carbon nanotube wet material; (4) Re-drying: The incompletely dried single-walled carbon nanotube wet material after pulverization is fully dried to obtain single-walled carbon nanotube powder with high bulk density.
8. The method for preparing single-walled carbon nanotube powder with high bulk density according to claim 7, characterized in that: The acid used in the pickling in step (1) is one or a mixture of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid or dilute hydrofluoric acid.
9. The method for preparing single-walled carbon nanotube powder with high bulk density according to claim 7, characterized in that: The drying temperature in the incomplete drying of step (2) is 50-110°C.
10. The method for preparing single-walled carbon nanotube powder with high bulk density according to claim 7, characterized in that: The weight loss rate of the single-walled carbon nanotube powder at 100-300° C. is 0.5-8.0%.