Crushing method and crushing device for carbon nanotubes and application of crushing device

Abstract

The invention provides a carbon nanotube crushing method and device and application of the carbon nanotube crushing method and device, and the carbon nanotube crushing method comprises the following steps: (1) performing opening treatment on a carbon nanotube to obtain an opened carbon nanotube; (2) carrying out extrusion treatment on the opened carbon nanotubes to obtain semi-finished carbon nanotubes; and (3) cutting and crushing the semi-finished carbon nano tube to obtain the crushed carbon nano tube. According to the crushing method disclosed by the invention, the carbon nano tube can be continuously crushed, the agglomeration and winding phenomena in a conventional crushing method can be avoided, the phenomenon of low crushing efficiency caused by the problems of material blockage and the like can be avoided, the crushing method can be used for industrial production, and the obtained carbon nano tube can be directly used for preparing conductive slurry.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon nanotube production, and relates to a carbon nanotube pulverizing method, a pulverizing device and applications thereof. Background Art

[0002] Carbon nanotubes have excellent electronic, mechanical, and mechanical properties. At the same time, changes in the atomic scale of carbon nanotubes can lead to changes in their properties. The resulting diversity of carbon nanotube properties makes them potentially applicable in fields such as lithium-ion batteries. A very small amount of carbon nanotubes can significantly improve the performance of materials such as lithium-ion batteries. The main methods for preparing carbon nanotubes include arc discharge, laser ablation, and chemical vapor deposition. The carbon nanotubes produced by these methods are mostly in the form of strips, ribbons, and clumps, which are difficult to be directly used in the preparation of conductive slurries. Therefore, the carbon nanotubes need to be crushed to the required particle size. However, although carbon nanotubes appear soft, they are actually very hard and tough, and it is very difficult to crush them to a certain particle size.

[0003] At present, the main methods for crushing carbon nanotubes are dry crushing such as blade crushing, turbine crushing, air flow crushing, etc.; and wet crushing. Since carbon nanotubes are in the form of fiber bundles, with high flexibility and low bulk density (less than 0.01g / cm3), they are easily agglomerated, entangled, and twisted during the dry crushing process, causing the crushing to be suspended and need to be cleaned before continuing, which is a cycle, wasting manpower, material resources and time, and more seriously damaging the crusher. In the wet crushing process, carbon nanotubes are mixed with solvents such as water and crushed. They can only be used to prepare conductive slurry after drying, which has high energy consumption. In addition, when solvents such as water are added to the crusher, the solvents slowly penetrate into the bearings of the crusher, which will cause short circuits if used for a long time.

[0004] CN118270771A discloses an online carbon nanotube fiber crushing device, which utilizes the gas released during the reduction process of graphene oxide microsheets to crush the carbon nanotube fibers, thereby avoiding the use of mechanical blades to crush the carbon nanotube fibers.

[0005] CN113611438A discloses a method for crushing carbon nanotube fiber bundles and conductive slurry, which uses a wetting liquid to wet the carbon nanotube fiber bundle until the wetting saturation of the carbon nanotube fiber bundle is 50-100% to obtain a weighted structure, and then crushes the weighted structure to obtain carbon nanotube powder.

[0006] The above scheme requires the introduction of additional substances such as wetting agents or graphene, which greatly limits the application scope of carbon nanotube fibers. Therefore, it is necessary to develop an efficient and continuous carbon nanotube pulverization process that does not introduce other additional substances such as wetting agents or graphene, and does not require a drying process, and can be directly used in the preparation of conductive slurries and other aspects. Summary of the invention

[0007] The purpose of the present invention is to provide a carbon nanotube crushing method, a crushing device and their application. The crushing method of the present invention enables carbon nanotubes to be crushed continuously, avoids the agglomeration and entanglement phenomenon in conventional crushing methods, avoids the phenomenon of low crushing efficiency caused by problems such as material jamming, and can be used for industrial production. The obtained carbon nanotubes can be directly used to prepare conductive slurry.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for pulverizing carbon nanotubes, the pulverizing method comprising the following steps:

[0010] (1) performing an opening treatment on the carbon nanotubes to obtain opened carbon nanotubes;

[0011] (2) extruding the opened carbon nanotubes to obtain semi-finished carbon nanotubes;

[0012] (3) Cutting and crushing the semi-finished carbon nanotubes to obtain crushed carbon nanotubes.

[0013] The present invention performs preliminary crushing of carbon nanotubes through loosening treatment, which can prevent the occurrence of entanglement, twisting and jamming during the subsequent crushing process. After that, the loosened carbon nanotubes are squeezed, which greatly improves the bulk density of the carbon nanotubes, facilitates the feeding and unloading of subsequent crushing, and solves the problem that it is difficult and inefficient to directly crush and unload carbon nanotubes with lower bulk density. Finally, cutting-type crushing can further prevent the entanglement and twisting of carbon nanotubes during the crushing process, and through the multiple strong cutting and shearing actions between the rotating knife and the cutting edge, carbon nanotube powder that can be directly used to prepare conductive slurry can be obtained.

[0014] Preferably, the carbon nanotubes in step (1) include single-walled carbon nanotubes.

[0015] Preferably, the morphology of the carbon nanotubes in step (1) includes any one of strip-shaped, ribbon-shaped or cluster-shaped, or a combination of at least two of them. Typical but non-limiting combinations include a combination of strip-shaped and ribbon-shaped, a combination of strip-shaped and cluster-shaped, or a combination of ribbon-shaped and cluster-shaped, etc.

[0016] Preferably, the bulk density of the carbon nanotubes in step (1) is 0.004 g / cm 3 ~0.01g / cm 3 , for example: 0.004g / cm 3 , 0.005g / cm 3 , 0.006g / cm 3 , 0.007g / cm 3 , 0.008g / cm 3, 0.009g / cm 3 or 0.01g / cm 3 The present invention is not limited to the numerical values ​​listed, and other numerical values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the rotation speed of the opening treatment in step (1) is 500rpm to 3000rpm, for example: 500rpm, 800rpm, 1000rpm, 2000rpm or 3000rpm, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the time for the opening treatment in step (1) is 3 min to 10 min, for example: 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the length of the loosened carbon nanotubes in step (1) is 0.05 mm to 50 mm, for example, 0.05 mm, 0.1 mm, 2 mm, 5 mm, 10 mm or 50 mm.

[0020] The operating steps of the extrusion treatment described in the present invention are to put the loosened carbon nanotubes into the feed port of the extruder, and the carbon nanotubes are pushed forward by the high-intensity rotation of the screw. The rotation of the screw generates a shear force to crush the carbon nanotubes, and the rotation of the screw generates a driving force to make the broken carbon nanotubes move forward continuously, and then the crushed carbon nanotubes are discharged from the discharge port.

[0021] Preferably, the screw rotation frequency of the extrusion treatment in step (2) is 20 Hz to 30 Hz, for example, 20 Hz, 22 Hz, 25 Hz, 28 Hz or 30 Hz, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the extrusion treatment time in step (2) is 3 min to 10 min, for example, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the bulk density of the semi-finished carbon nanotubes in step (2) is 0.1 g / cm 3 ~0.3g / cm 3 , for example: 0.1g / cm 3 , 0.15g / cm 3 , 0.2g / cm 3 , 0.25g / cm 3or 0.3g / cm 3 wait.

[0024] The operation flow of the cutting and crushing treatment in step (3) of the present invention is that the carbon nanotubes enter the grinding chamber through the sample inlet, are crushed for a certain period of time under the multiple cutting actions between the rotating knife and the cutting edge, and then enter the collecting device through the action of airflow.

[0025] Preferably, the rotation speed of the cutting and crushing process in step (3) is 500rpm to 3000rpm, for example: 500rpm, 800rpm, 1000rpm, 2000rpm or 3000rpm, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the time for the cutting and crushing treatment in step (3) is 3 min to 10 min, for example: 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the length of the crushed carbon nanotubes in step (3) is 0.05 mm to 20 mm, for example, 0.05 mm, 0.1 mm, 1 mm, 5 mm, 10 mm or 20 mm, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the bulk density of the crushed carbon nanotubes in step (3) is 0.02 g / cm 3 ~0.06g / cm 3 , for example: 0.02g / cm 3 , 0.03g / cm 3 , 0.04g / cm 3 , 0.05g / cm 3 or 0.06g / cm 3 The present invention is not limited to the numerical values ​​listed, and other numerical values ​​not listed within the numerical range are also applicable.

[0029] In a second aspect, the present invention provides a pulverizing device used in the pulverizing method as described in the first aspect, wherein the pulverizing device comprises an opener, a twin-screw extruder and a cutting pulverizer which are sequentially connected through a carbon nanotube transmission pipeline.

[0030] Preferably, the internal materials of the opener, the twin-screw extruder and the cutting mill independently include any one of stainless steel, carbon steel or tungsten steel or a combination of at least two thereof.

[0031] Preferably, the opener comprises a licker-in opener.

[0032] Preferably, needle teeth are arranged on the licker-in roller of the licker-in roller opener.

[0033] The licker-in roller of the licker-in type opener of the present invention is provided with hundreds of needle teeth, and the carbon nanotubes are opened due to being grabbed and torn by the needle teeth.

[0034] Preferably, a multi-tooth rotary cutter is arranged inside the cutting pulverizer.

[0035] Preferably, the multi-tooth rotary cutter comprises a 24-tooth stainless steel rotary cutter.

[0036] The rotary cutter of the cutting pulverizer of the present invention adopts a 24-tooth stainless steel rotary cutter, which is specifically arranged as a 4-tooth large rotary cutter in the front view and 4 groups in the side view, each group containing 6-tooth small rotary cutters, and the small rotary cutters are staggered in sequence.

[0037] In a third aspect, the present invention provides a conductive paste, wherein the conductive paste comprises pulverized carbon nanotubes obtained by the pulverization method according to the first aspect.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The carbon nanotube pulverization method of the present invention adopts a continuous pulverization process of sequentially performing an opening treatment, an extrusion treatment and a cutting type pulverization, and the efficiency of pulverizing the carbon nanotubes is high and the effect is good. The obtained pulverized carbon nanotubes can be directly used to prepare a conductive paste, which can solve the problem of large particle size and uneven particle size of the carbon nanotube conductive paste.

[0040] (2) The carbon nanotube pulverization method of the present invention can significantly increase the bulk density of carbon nanotubes. Through extrusion treatment, the bulk density of single-walled carbon nanotubes can be increased from 0.006 g / cm 3 Increase to 0.19g / cm 3 The increase can reach 31.7 times. After being crushed by a cutting mill, the bulk density of the single-walled carbon nanotube powder is 0.02g / cm 3 ~0.06g / cm 3 Compared with the bulk density of the initial single-walled carbon nanotubes, it has increased by 3.3 to 10 times. The length after crushing can reach within 50 mm or even within 5 mm, and the crushing effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a particle size distribution diagram of the conductive paste made from the crushed carbon nanotubes obtained in Example 1.

[0042] Figure 2 This is the particle size distribution diagram of the conductive paste made from the crushed carbon nanotubes obtained in Example 8.

[0043] Figure 3This is a morphology picture of the initial single-walled carbon nanotube used in Example 1.

[0044] Figure 4 This is a morphology picture of the opened carbon nanotubes obtained in Example 1.

[0045] Figure 5 This is a morphology picture of the semi-finished carbon nanotubes obtained in Example 1.

[0046] Figure 6 This is a morphology picture of the crushed carbon nanotubes obtained in Example 1. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0048] The pulverizing device used in the embodiment of the present invention includes an opener, a twin-screw extruder and a cutting type pulverizer connected in sequence through a carbon nanotube transmission pipeline. The internal materials of the opener, the twin-screw extruder and the cutting type pulverizer are all stainless steel. The opener is a licker-in type opener, and the licker-in type opener has hundreds of needle teeth on its licker-in roller. The interior of the cutting type pulverizer is provided with 24-tooth stainless steel rotary cutters, and the specific arrangement is that the front view is a 4-tooth large rotary cutter, and the side view is 4 groups, each group contains 6-tooth small rotary cutters, and the small rotary cutters are arranged in a staggered manner in sequence.

[0049] Example 1

[0050] This embodiment provides a method for pulverizing carbon nanotubes. The particle size distribution of the conductive paste made of carbon nanotubes obtained by the pulverizing method is as follows: Figure 1 As shown, the pulverizing method specifically comprises the following steps:

[0051] (1) The bulk density is 0.006 g / cm 3 The initial single-walled carbon nanotubes have a flocculent morphology. The morphology of the initial single-walled carbon nanotubes is shown in FIG. Figure 3 The initial single-walled carbon nanotubes were opened for 5 minutes using an opening machine at a rotation speed of 600 rpm to obtain opened carbon nanotubes. The morphology of the opened carbon nanotubes is shown in FIG. Figure 4 As shown;

[0052] (2) Using a twin-screw extruder at a rotation frequency of 25 Hz to extrude the opened carbon nanotubes for 5 minutes to obtain semi-finished carbon nanotubes. The morphology of the semi-finished carbon nanotubes is shown in FIG. Figure 5 As shown;

[0053] (3) Using a cutting mill to cut and crush the semi-finished carbon nanotubes at a rotation speed of 500 rpm for 3 minutes to obtain crushed carbon nanotubes. The morphology of the crushed carbon nanotubes is as shown in FIG. Figure 6 shown.

[0054] Example 2

[0055] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0056] (1) The bulk density is 0.006 g / cm 3 , the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0057] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0058] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 500 rpm for 10 min to obtain crushed carbon nanotubes.

[0059] Example 3

[0060] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0061] (1) The bulk density is 0.006 g / cm 3 , the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0062] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0063] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 1000 rpm for 10 min to obtain crushed carbon nanotubes.

[0064] Example 4

[0065] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0066] (1) The bulk density is 0.006 g / cm 3, the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0067] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0068] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 2000 rpm for 10 min to obtain crushed carbon nanotubes.

[0069] Example 5

[0070] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0071] (1) The bulk density is 0.006 g / cm 3 , the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0072] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0073] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 3000 rpm for 3 min to obtain crushed carbon nanotubes.

[0074] Example 6

[0075] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0076] (1) The bulk density is 0.006 g / cm 3 , the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0077] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0078] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 3000 rpm for 5 min to obtain crushed carbon nanotubes.

[0079] Example 7

[0080] This embodiment provides a method for crushing carbon nanotubes, and the crushing method specifically includes the following steps:

[0081] (1) The bulk density is 0.006 g / cm 3 , the initial single-walled carbon nanotubes with flocculent morphology are opened by using an opening machine at a rotation speed of 600 rpm for 5 minutes to obtain opened carbon nanotubes;

[0082] (2) using a twin-screw extruder to extrude the opened carbon nanotubes at a rotation frequency of 25 Hz for 5 minutes to obtain semi-finished carbon nanotubes;

[0083] (3) The semi-finished carbon nanotubes were cut and crushed by a cutting mill at a rotation speed of 3000 rpm for 10 min to obtain crushed carbon nanotubes.

[0084] Example 8

[0085] The only difference between this embodiment and embodiment 1 is that the time for the cutting and crushing process is 2 minutes, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0086] Example 9

[0087] The only difference between this embodiment and embodiment 1 is that the time for the cutting and crushing process is 20 minutes, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0088] Example 10

[0089] The only difference between this embodiment and embodiment 1 is that the rotation speed of the cutting and crushing process is 400 rpm, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0090] Embodiment 11

[0091] The only difference between this embodiment and embodiment 1 is that the rotation speed of the cutting and crushing process is 3500 rpm, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0092] Comparative Example 1

[0093] The only difference between this comparative example and Example 1 is that no extrusion treatment is performed, and other conditions and parameters are exactly the same as those in Example 1.

[0094] Comparative Example 2

[0095] The only difference between this comparative example and Example 1 is that no opening treatment is performed, and other conditions and parameters are exactly the same as those in Example 1.

[0096] Comparative Example 3

[0097] The only difference between this comparative example and Example 1 is that no cutting and crushing process is performed, and other conditions and parameters are exactly the same as those in Example 1.

[0098] Performance Testing:

[0099] During the pulverization process of the carbon nanotubes, the bulk density of the single-walled carbon nanotubes was obtained in each step, wherein the bulk density calculation formula is the weight of the single-walled carbon nanotube m / the volume of the single-walled carbon nanotube v; the length of the single-walled carbon nanotubes was tested using an optical microscope, and " / " indicates that the pulverization process was interrupted and the test was not performed or could not be performed. The test results are shown in Table 1:

[0100] Table 1

[0101]

[0102] As can be seen from Table 1, from Examples 1-11, the carbon nanotube crushing method of the present invention can greatly increase the bulk density of carbon nanotubes. Through extrusion treatment, the bulk density of single-walled carbon nanotubes can be increased from 0.006 g / cm 3 Increase to 0.19g / cm 3 The increase can reach 31.7 times. After being crushed by a cutting mill, the bulk density of the single-walled carbon nanotube powder is 0.02g / cm 3 ~0.06g / cm 3 Compared with the bulk density of the initial single-walled carbon nanotubes, it has increased by 3.3 to 10 times. The length after crushing can reach within 50 mm or even within 5 mm, and the crushing effect is better.

[0103] By comparing Example 1 with Examples 8-9, it can be seen that in the crushing process of the carbon nanotubes described in the present invention, the time of the cutting and crushing treatment will affect the effect of obtaining the carbon nanotubes. The effect of obtaining the carbon nanotubes is better when the cutting and crushing treatment time is controlled within 3min to 10min. If the cutting and crushing treatment time is too short, the length of the carbon nanotubes after crushing will be too large. If the cutting and crushing treatment time is too long, the length range of the carbon nanotube powder remains unchanged, the bulk density remains unchanged, but the energy consumption increases.

[0104] By comparing Example 1 with Examples 10-11, it can be seen that in the crushing process of the carbon nanotubes described in the present invention, the rotation speed of the cutting and crushing treatment will affect the effect of obtaining the carbon nanotubes. The effect of obtaining the carbon nanotubes is better when the rotation speed of the cutting and crushing treatment is controlled at 500rpm~3000rpm. If the rotation speed of the cutting and crushing treatment is too small, the maximum length of the carbon nanotubes is 50mm, and the crushing effect cannot be achieved, and it cannot be directly used to prepare conductive slurry. If the rotation speed of the cutting and crushing treatment is too large, the length range of the carbon nanotube powder remains unchanged, the bulk density remains unchanged, but the energy consumption increases.

[0105] From the comparison between Example 1 and Comparative Example 1, it can be seen that the bulk density of the single-walled carbon nanotubes after being crushed by the opener is very low, only 0.005 g / cm 3 The material is not extruded through a twin-screw extruder to increase the bulk density, which results in the material being difficult to discharge after entering the cutting mill because it is very light.

[0106] From the comparison between Example 1 and Comparative Example 2, it can be seen that the single-walled carbon nanotubes are not crushed by the opener and are directly extruded by the twin-screw extruder. Because the material is in agglomerated blocks, entanglement, twisting and jamming of the material occur during the extrusion process, and continuous production cannot be achieved. The present invention can break up the initial single-walled carbon nanotube material through the opening process, making it fluffy, so that the material can be extruded and fed uniformly to the downstream twin-screw extruder.

[0107] From the comparison between Example 1 and Comparative Example 3, it can be seen that the single-walled carbon nanotubes are crushed by an opener and extruded by a twin-screw extruder, but not crushed by a cutting pulverizer. The single-walled carbon nanotubes are in agglomerates and cannot be directly used to prepare conductive slurry.

[0108] Application Example 1

[0109] 2 g of the single-walled carbon nanotube powder prepared in Example 1, 3 g of carboxymethyl cellulose and 495 g of N-methylpyrrolidone were prepared into a conductive slurry using an ultrasonic disperser. The particle size distribution of the conductive slurry was tested using a Malvern laser particle size analyzer. The test results are shown in Tables 2 and Figure 1 .

[0110] Application Example 2

[0111] 2 g of the single-walled carbon nanotube powder prepared in Example 8, 3 g of carboxymethyl cellulose and 495 g of N-methylpyrrolidone were prepared into a conductive slurry using an ultrasonic disperser. The particle size distribution of the conductive slurry was tested using a Malvern laser particle size analyzer. The test results are shown in Tables 2 and Figure 2 .

[0112] Table 2

[0113]

[0114] From Table 2 and Figure 1-2 By comparison, it can be seen that the particle size distribution diagram of the conductive paste of Application Example 1 has only one peak, the average particle size D50 is 0.052μm, D90 is 0.08μm, the particle size span is small, and the distribution is uniform. The distribution diagram of the conductive paste of Application Example 2 has 4 peaks, the average particle size D50 is 0.115μm, D90 is 40.369μm, the particle size span is large, and the distribution is uneven. Therefore, it is shown that the single-walled carbon nanotube crushing process of Example 1 can achieve the purpose of uniform crushing, and its crushing effect is significantly better than the crushing effect of Example 8 with a shorter crushing time.

[0115] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for pulverizing carbon nanotubes, characterized in that: The comminution method comprises the following steps: (1) performing an opening treatment on the carbon nanotubes to obtain opened carbon nanotubes; (2) extruding the opened carbon nanotubes to obtain semi-finished carbon nanotubes; (3) Cutting and crushing the semi-finished carbon nanotubes to obtain crushed carbon nanotubes.

2. The pulverizing method according to claim 1, characterized in that The carbon nanotubes in step (1) include single-walled carbon nanotubes; Preferably, the morphology of the carbon nanotubes in step (1) includes any one of strip-shaped, band-shaped or cluster-shaped, or a combination of at least two of them; Preferably, the bulk density of the carbon nanotubes in step (1) is 0.004 g / cm 3 ~0.01g / cm 3 .

3. The pulverizing method according to claim 1 or 2, characterized in that: The rotation speed of the opening treatment in step (1) is 500 rpm to 3000 rpm; Preferably, the time for the opening treatment in step (1) is 3 min to 10 min; Preferably, the length of the loosened carbon nanotubes in step (1) is 0.05 mm to 50 mm.

4. The pulverizing method according to any one of claims 1 to 3, characterized in that: The screw rotation frequency of the extrusion process in step (2) is 20 Hz to 30 Hz; Preferably, the extrusion treatment time in step (2) is 3 min to 10 min; Preferably, the bulk density of the semi-finished carbon nanotubes in step (2) is 0.1 g / cm 3 ~0.3g / cm 3 .

5. The pulverizing method according to any one of claims 1 to 4, characterized in that: The speed of the cutting and crushing process in step (3) is 500 rpm to 3000 rpm; Preferably, the cutting and crushing process in step (3) takes 3 to 10 minutes; Preferably, the length of the crushed carbon nanotubes in step (3) is 0.05 mm to 20 mm; Preferably, the bulk density of the crushed carbon nanotubes in step (3) is 0.02 g / cm 3 ~0.06g / cm 3 .

6. A pulverizing device used in the pulverizing method according to any one of claims 1 to 5, characterized in that: The pulverizing device comprises an opener, a twin-screw extruder and a cutting pulverizer which are sequentially connected through a carbon nanotube transmission pipeline.

7. The pulverizing device according to claim 6, characterized in that: The internal materials of the opener, the twin-screw extruder and the cutting pulverizer independently include any one of stainless steel, carbon steel or tungsten steel or a combination of at least two thereof.

8. The pulverizing device according to claim 6 or 7, characterized in that: The opener comprises a licker-in type opener; Preferably, needle teeth are arranged on the licker-in roller of the licker-in roller opener.

9. The pulverizing device according to any one of claims 6 to 8, characterized in that: A multi-tooth rotary cutter is arranged inside the cutting pulverizer; Preferably, the multi-tooth rotary cutter comprises a 24-tooth stainless steel rotary cutter.

10. A conductive paste, characterized in that: The conductive paste comprises pulverized carbon nanotubes obtained by the pulverization method according to any one of claims 1 to 5.

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