Carbon nanotube conductive master batch, and preparation method and application thereof

Abstract

This invention provides a carbon nanotube conductive masterbatch, its preparation method, and its application. The preparation method includes the following steps: (1) mixing carbon nanotubes, a dispersant, and a first solvent to obtain a carbon nanotube dispersion; mixing thermoplastic polyurethane with a second solvent to obtain a resin solution; (2) mixing the carbon nanotube dispersion and the resin solution obtained in step (1) to obtain a paste; and (3) extruding the paste obtained in step (2) to obtain the carbon nanotube conductive masterbatch. In this invention, the carbon nanotube conductive masterbatch obtained by the preparation method not only achieves good carbon nanotube dispersion but also reduces the amount of carbon nanotubes added. Under the premise of achieving the same conductivity, the carbon nanotube conductive masterbatch obtained by this invention requires less content, reducing costs. It also avoids the influence of carbon nanotubes on mechanical properties, has good versatility, and is suitable for various plastic systems.

Description

Technical Field

[0001] This invention belongs to the field of carbon nanotube material technology, specifically relating to a carbon nanotube conductive masterbatch, its preparation method, and its application. Background Technology

[0002] Carbon nanotubes, also known as buckytubes, are one-dimensional quantum materials with a unique structure, consisting of several to dozens of layers of coaxial cylindrical tubes composed of hexagonally arranged carbon atoms. Carbon nanotubes exhibit good stability and excellent electrical conductivity, making them suitable as permanent conductive agents and widely used in conductive polymer materials and conductive coatings. However, due to their high potential energy, carbon nanotubes are prone to aggregation and extremely difficult to disperse. Particularly in high-viscosity polymer melts, simple mechanical mixing is insufficient to achieve uniform dispersion of carbon nanotubes, resulting in a significantly higher actual carbon nanotube content than theoretically required to achieve the desired surface resistivity. Furthermore, carbon nanotubes easily form large agglomerates in plastic melts, severely impacting the mechanical properties of composite materials.

[0003] Currently, there are three main methods for preparing carbon nanotube polymer conductive masterbatches. The first is to directly add carbon nanotubes to polymer materials and then melt-mix them using a twin-screw extruder or internal mixer to prepare the conductive masterbatch. The second is to first mix carbon nanotubes evenly with lubricants such as low-melting-point waxes or white oils, and then melt-mix them with polymers to prepare the conductive masterbatch. The third is to use liquid solvents to help disperse the carbon nanotubes before mixing them with polymers and other raw materials to prepare the conductive masterbatch.

[0004] For example, CN101870802A discloses a solid-phase dispersion method for obtaining conductive masterbatch by high-speed mixing of polymers, carbon nanotubes, coupling agents, and dispersants followed by twin-screw extrusion granulation. However, high-speed mixing generates a large amount of dust. Furthermore, due to the high melt viscosity of the polymer material during twin-screw extrusion, the dispersion effect of carbon nanotubes is limited, inevitably leading to a higher amount of carbon nanotubes required to achieve the same level of antistatic properties.

[0005] CN111363220A discloses a method of uniformly mixing carbon nanotubes and polymer powder with a mixture of low-viscosity white oil and wax, removing the white oil, and then extruding and granulating to obtain conductive masterbatch. Although the mixed solution of white oil and wax has a low viscosity and is easier to disperse carbon nanotubes than polymer melt, simple mechanical mixing, with the addition of a solid polymer phase during the mixing process, is still not conducive to the effective dispersion of carbon nanotubes.

[0006] CN104844820A discloses a method of first dispersing a small-molecule lubricant and carbon nanotubes separately in an organic solvent, mixing them evenly, and then removing the solvent to obtain a composite conductive masterbatch of lubricant and carbon nanotubes, which can be subsequently used in polymers. However, by dispersing the carbon nanotubes before use in the polymer, the carbon nanotubes are transformed from a dispersed state in the solvent into a compressed particle aggregate state. Therefore, when used in the polymer, the dispersion effect of the carbon nanotubes in the polymer is also generally poor.

[0007] The common drawbacks of existing technologies are that traditional methods for preparing carbon nanotube conductive masterbatches often suffer from problems such as difficulty in dispersing carbon nanotubes and dust pollution. Furthermore, due to issues with the compatibility and temperature resistance of the conductive masterbatch carrier polymer with different types of plastic polymers, conductive masterbatches used for only one type of plastic polymer often require the development of conductive masterbatches with the same type of substrate, resulting in poor versatility for traditional carbon nanotube conductive masterbatches.

[0008] Therefore, developing a method for preparing a carbon nanotube conductive masterbatch with good dispersibility in polymers, low agglomeration, and good versatility is an urgent problem to be solved in this field. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a carbon nanotube conductive masterbatch, its preparation method, and its applications. The preparation method of the carbon nanotube conductive masterbatch solves the problems of carbon nanotubes not being effectively dispersed in polymers, resulting in a large amount of carbon nanotubes required to achieve the same antistatic level, and the deterioration of material mechanical properties due to the easy formation of agglomerates by carbon nanotubes. Furthermore, traditional methods produce carbon nanotube conductive masterbatches with poor versatility and generate dust pollution during production.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a carbon nanotube conductive masterbatch, the method comprising the following steps:

[0012] (1) The carbon nanotubes, dispersant and first solvent are mixed for the first time to obtain a carbon nanotube dispersion; the thermoplastic polyurethane and second solvent are mixed for the second time to obtain a resin solution; (2) The carbon nanotube dispersion and resin solution obtained in step (1) are mixed for the third time to obtain a paste; (3) The paste obtained in step (2) is extruded to obtain the carbon nanotube conductive masterbatch.

[0013] In this invention, carbon nanotubes are first pre-dispersed in a solvent, and the degree of dispersion is controlled to fully open up the aggregates, which is beneficial for obtaining well-dispersed carbon nanotubes and thus improving the dispersibility of carbon nanotubes in the polymer. Secondly, thermoplastic polyurethane is mixed with a solvent and then mixed with the carbon nanotube dispersion for homogeneous liquid-phase mixing and dispersion, which can fully retain the dispersion state of the carbon nanotube dispersion and further improve the dispersibility of carbon nanotubes. Thirdly, the resulting paste is directly extruded, allowing the carbon nanotubes to be better dispersed in the polymer, avoiding uneven dispersion or reducing the formation of aggregates. By employing… The carbon nanotube conductive masterbatch obtained by the specific preparation method not only achieves good carbon nanotube dispersion but also reduces the amount of carbon nanotubes added. Under the premise of achieving the same conductivity, the carbon nanotube conductive masterbatch obtained by this invention requires less carbon nanotubes, thus reducing costs. It also avoids the impact of high carbon nanotube content on the mechanical properties of finished plastic products. In addition, this invention uses thermoplastic polyurethane as the masterbatch carrier, which makes the masterbatch versatile and applicable to different plastic systems. It has good compatibility with various plastics (such as polyethylene, polypropylene, general-purpose polystyrene, polycarbonate, polyamide, etc.) and good high and low temperature resistance.

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

[0015] Preferably, the dispersant in step (1) includes an oil-soluble dispersant.

[0016] Preferably, the mass of the dispersant in step (1) is 5-60% of the mass of the carbon nanotubes, for example, it can be 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, etc.; more preferably, it is 15-30%.

[0017] Preferably, the first solvent in step (1) comprises N-methylpyrrolidone (NMP).

[0018] In this invention, N-methylpyrrolidone is used as a dispersion medium, which enables carbon nanotubes to be better dispersed in the dispersion medium, facilitates the opening of carbon nanotube aggregates, and NMP can also be recycled.

[0019] Preferably, the mass concentration of the carbon nanotube dispersion in step (1) is 8-20%, for example, it can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0020] Preferably, the temperature of the first mixing in step (1) is 60 to 80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, etc.

[0021] Preferably, the first mixing in step (1) is carried out in a grinding apparatus.

[0022] In this invention, the grinding equipment includes, but is not limited to, a sand mill.

[0023] Preferably, the D50 of the carbon nanotube dispersion in step (1) is 0.5–2.5 μm, for example, it can be 0.5 μm, 0.52 μm, 0.54 μm, 0.56 μm, 0.58 μm, 0.6 μm, 0.62 μm, 0.64 μm, 0.66 μm, 0.68 μm, 0.7 μm, 0.72 μm, 0.74 μm, 0.76 μm, 0.78 μm, 0.8 μm, or 0.82 μm. , 0.84μm, 0.86μm, 0.88μm, 0.9μm, 0.92μm, 0.94μm, 0.96μm, 0.98μm, 1.0μm, 1.1μm, 1.2μm, 1. 3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2.0μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, etc.

[0024] Preferably, in step (1), the second solvent comprises N-methylpyrrolidone.

[0025] Preferably, the mass concentration of the resin solution in step (1) is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0026] Preferably, the temperature of the second mixing in step (1) is 60 to 80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, etc.

[0027] Preferably, the temperature of the third mixing in step (2) is 60 to 80°C, for example, it can be 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, etc.

[0028] Preferably, the first mixture, the second mixture, and the third mixture are at the same temperature.

[0029] In this invention, the first, second, and third mixing processes are carried out at the same temperature, which can better preserve the dispersion state of carbon nanotubes, achieve homogeneous mixing and dispersion, and improve the dispersibility of carbon nanotubes.

[0030] Preferably, after the third mixing in step (2), the process further includes a step of cooling to room temperature.

[0031] Preferably, the extrusion temperature in step (3) is room temperature.

[0032] Preferably, step (3) further includes granulation and / or drying steps after extrusion.

[0033] In this invention, the particles obtained by granulation can be dried in an oven with a condensation recovery device to obtain carbon nanotube conductive masterbatch, and NMP can be recycled and reused.

[0034] Preferably, by mass percentage, the carbon nanotube conductive masterbatch comprises 10-30% carbon nanotubes (e.g., 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 22%, 24%, 26%, 28%, 30%, etc.) and 2-6% dispersant (e.g., 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%). 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6%, etc.) and 64-88% thermoplastic polyurethane (e.g., 64%, 65%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, etc.).

[0035] In this invention, if the content of the dispersant is too low, the dispersion effect is poor; if the content is too high, the cost is high and it affects the use of carbon nanotube conductive masterbatch.

[0036] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0037] (1) Add multi-walled carbon nanotubes, dispersant and N-methylpyrrolidone to a grinding device and mix and disperse them at a temperature of 60-80℃ until the D50 of the obtained carbon nanotube dispersion is 0.5-2.5μm; mix thermoplastic polyurethane and N-methylpyrrolidone at a temperature of 60-80℃ to obtain a resin solution.

[0038] (2) The carbon nanotube dispersion and resin solution obtained in step (1) are mixed evenly at a temperature of 60-80℃, and then cooled to room temperature to obtain a paste.

[0039] (3) The paste obtained in step (2) is extruded at room temperature, granulated and dried to obtain the carbon nanotube conductive masterbatch.

[0040] In a second aspect, the present invention provides a carbon nanotube conductive masterbatch, which is prepared by the preparation method described in the first aspect.

[0041] Thirdly, the present invention provides a conductive composite material, the conductive composite material comprising the carbon nanotube conductive masterbatch described in the second aspect.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The method for preparing carbon nanotube conductive masterbatch provided by this invention employs specific process steps: carbon nanotubes and thermoplastic polyurethane are pre-dispersed separately, and the resulting solutions are mixed uniformly under certain conditions to obtain a paste. The paste is then directly extruded. The resulting carbon nanotube conductive masterbatch not only exhibits good carbon nanotube dispersibility but also reduces the amount of carbon nanotubes required. To achieve the same conductivity, the carbon nanotube conductive masterbatch obtained by this invention requires less carbon nanotube content, thus reducing costs. It also avoids the negative impact of high carbon nanotube content on the mechanical properties of finished plastic products. Furthermore, it has good versatility and can be used in different plastic systems. Attached Figure Description

[0045] Figure 1 The appearance of the black paste obtained by step (2) of the preparation method provided in Example 1 of the present invention.

[0046] Figure 2 The image shows the appearance of the carbon nanotube conductive masterbatch obtained by the preparation method provided in Example 1 of this invention. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0048] All materials used in this invention are commercially available or prepared using conventional methods. Unless otherwise specified, the materials used in this invention are as follows:

[0049] Multi-walled carbon nanotubes: Initial carbon nanotube powder produced by Jiangsu Tiannai Technology Co., Ltd., with a purity >90.0%, a tube diameter of 10 nm, and a bulk density of 0.08 g / cm³. 3 Its BET specific surface area is 265m². 2 / g.

[0050] Thermoplastic polyurethane: Covestro TPU 2792A.

[0051] Oil-soluble dispersant: Highly saturated nitrile rubber ZN35053.

[0052] In this invention, D50 can be tested using a Malvern 3000 laser particle size analyzer, with Particle Refractive Index: 1.800, Particle Absorption Index: 1.000, and Dispersant Refractive Index: 1.470.

[0053] Example 1

[0054] This embodiment provides a method for preparing carbon nanotube conductive masterbatch, specifically including the following steps:

[0055] (1) 1 kg of multi-walled carbon nanotubes, 0.2 kg of oil-soluble dispersant (20% of the mass of multi-walled carbon nanotubes) and 8.8 kg of N-methylpyrrolidone were added to a sand mill and mixed and dispersed at 60°C until the D50 of the carbon nanotube dispersion was 0.5 μm; 3.8 kg of thermoplastic polyurethane and 15.2 kg of N-methylpyrrolidone were mixed at 60°C to obtain a resin solution (mass concentration of 20%).

[0056] (2) Mix 10 kg of the carbon nanotube dispersion obtained in step (1) and 19 kg of the resin solution at 60°C for 5 min, then cool to room temperature to obtain a black paste; the appearance of the black paste is shown in the figure below. Figure 1 As shown;

[0057] (3) The black paste obtained in step (2) is extruded at room temperature and granulated to obtain particles of uniform size with an average length of 5 mm; then the obtained particles are dried at 150°C to obtain the carbon nanotube conductive masterbatch; by mass percentage, the carbon nanotube conductive masterbatch comprises 20% multi-walled carbon nanotubes, 4% oil-soluble dispersant and 76% thermoplastic polyurethane. The appearance of the carbon nanotube conductive masterbatch is shown in the figure below. Figure 2 As shown.

[0058] Example 2

[0059] This embodiment provides a method for preparing carbon nanotube conductive masterbatch, specifically including the following steps:

[0060] (1) 1 kg of multi-walled carbon nanotubes, 0.25 kg of oil-soluble dispersant (25% of the mass of multi-walled carbon nanotubes) and 8.75 kg of N-methylpyrrolidone were added to a sand mill and mixed and dispersed at 70°C until the D50 of the carbon nanotube dispersion was 1.0 μm; 3.75 kg of thermoplastic polyurethane and 21.25 kg of N-methylpyrrolidone were mixed at 70°C to obtain a resin solution (mass concentration of 15%).

[0061] (2) Mix 10 kg of carbon nanotube dispersion obtained in step (1) and 25 kg of resin solution at 70 °C for 5 min, and then cool to room temperature to obtain a black paste.

[0062] (3) The black paste obtained in step (2) is extruded at room temperature and granulated to obtain particles with uniform size and an average length of 5 mm; then the obtained particles are dried at 150°C to obtain the carbon nanotube conductive masterbatch; by mass percentage, the carbon nanotube conductive masterbatch includes 20% multi-walled carbon nanotubes, 5% oil-soluble dispersant and 75% thermoplastic polyurethane.

[0063] Example 3

[0064] This embodiment provides a method for preparing carbon nanotube conductive masterbatch, specifically including the following steps:

[0065] (1) 1 kg of multi-walled carbon nanotubes, 0.2 kg of oil-soluble dispersant (20% of the mass of multi-walled carbon nanotubes) and 8.8 kg of N-methylpyrrolidone were added to a sand mill and mixed and dispersed at 80°C until the D50 of the carbon nanotube dispersion was 2.0 μm; 8.8 kg of thermoplastic polyurethane and 35.2 kg of N-methylpyrrolidone were mixed at 80°C to obtain a resin solution (mass concentration of 20%).

[0066] (2) Mix 10 kg of carbon nanotube dispersion obtained in step (1) and 44 kg of resin solution at 80 °C for 5 min, and then cool to room temperature to obtain a black paste.

[0067] (3) The black paste obtained in step (2) is extruded at room temperature and granulated to obtain particles with uniform size and an average length of 5 mm; then the obtained particles are dried at 150°C to obtain the carbon nanotube conductive masterbatch; by mass percentage, the carbon nanotube conductive masterbatch includes 10% multi-walled carbon nanotubes, 2% oil-soluble dispersant and 88% thermoplastic polyurethane.

[0068] Example 4

[0069] This embodiment provides a method for preparing carbon nanotube conductive masterbatch, specifically including the following steps:

[0070] (1) Add 3 kg of multi-walled carbon nanotubes, 0.6 kg of oil-soluble dispersant (20% of the mass of multi-walled carbon nanotubes) and 26.4 kg of N-methylpyrrolidone to a sand mill and mix and disperse at 60°C until the D50 of the carbon nanotube dispersion is 2.5 μm; mix 6.4 kg of thermoplastic polyurethane and 57.6 kg of N-methylpyrrolidone at 60°C to obtain a resin solution (mass concentration of 10%).

[0071] (2) Mix 30 kg of carbon nanotube dispersion obtained in step (1) and 64 kg of resin solution at 60 °C for 5 min, and then cool to room temperature to obtain a black paste.

[0072] (3) The black paste obtained in step (2) is extruded at room temperature and granulated to obtain particles with uniform size and an average length of 5 mm; then the obtained particles are dried at 150°C to obtain the carbon nanotube conductive masterbatch; by mass percentage, the carbon nanotube conductive masterbatch includes 30% multi-walled carbon nanotubes, 6% oil-soluble dispersant and 64% thermoplastic polyurethane.

[0073] Example 5

[0074] This embodiment provides a method for preparing a carbon nanotube conductive masterbatch. The only difference between this method and Example 2 is that the D50 of the carbon nanotube dispersion in step (1) is 0.2 μm. All other steps and parameters are the same as in Example 2.

[0075] Example 6

[0076] This embodiment provides a method for preparing carbon nanotube conductive masterbatch. The only difference between this method and Example 2 is that the D50 of the carbon nanotube dispersion in step (1) is 3 μm. All other steps and parameters are the same as in Example 2.

[0077] Example 7

[0078] This embodiment provides a method for preparing a carbon nanotube conductive masterbatch. The only difference between this method and Example 2 is that the mass percentage of oil-soluble dispersant in the carbon nanotube conductive masterbatch is 1.04%, and the mass of oil-soluble dispersant in the carbon nanotube dispersion in step (1) is 0.05 kg, and the mass of NMP is 8.95 kg. All other steps and parameters are the same as in Example 2.

[0079] Example 8

[0080] This embodiment provides a method for preparing a carbon nanotube conductive masterbatch. The only difference between this method and Example 2 is that the mass percentage of oil-soluble dispersant in the carbon nanotube conductive masterbatch is 7.8%, and the mass of oil-soluble dispersant in the carbon nanotube dispersion in step (1) is 0.4 kg, and the mass of NMP is 8.6 kg. All other steps and parameters are the same as in Example 2.

[0081] Comparative Example 1

[0082] This comparative example provides a method for preparing carbon nanotube conductive masterbatch, specifically including the following steps: adding an oil-soluble dispersant and thermoplastic polyurethane to a mixer and mixing for 3 minutes at 190°C and 70 rpm; then adding multi-walled carbon nanotubes and continuing to mix for 15 minutes to obtain a rubber compound; then adding the rubber compound to a twin-screw extruder and extruding at 190–220°C to granulate, thereby obtaining the carbon nanotube conductive masterbatch; by mass percentage, the carbon nanotube conductive masterbatch comprises 20% multi-walled carbon nanotubes, 5% oil-soluble dispersant, and 75% thermoplastic polyurethane.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing a carbon nanotube conductive masterbatch. The preparation method includes: mixing 3.75 kg of thermoplastic polyurethane and 21.25 kg of N-methylpyrrolidone at a temperature of 70°C to obtain a resin solution; then adding 1 kg of multi-walled carbon nanotubes and 0.25 kg of oil-soluble dispersant to the solution and mixing evenly for 5 min; cooling to room temperature to obtain a black paste; and then proceeding to step (3) of the obtained black paste, with the process parameters of step (3) being the same as in Example 2.

[0085] Performance testing

[0086] The carbon nanotube conductive masterbatches obtained by the preparation methods provided in Examples 1-8 and Comparative Examples 1-2 were mixed with different plastics at low speed for 5 minutes in a high-speed mixing pot, and then extruded and granulated by a twin-screw blending extruder to obtain conductive composite materials; the conductive composite material particles were injection molded and the surface resistance of the samples was tested.

[0087] The different plastics used are polyethylene (PE), polypropylene (PP), general-purpose polystyrene (GPPS), polycarbonate (PC), and polyamide 66 (PA66). The extruder temperature settings are: PE 100~140℃, PP 120~175℃, GPPS 150~190℃, PC 230~260℃, and PA66 230~270℃.

[0088] The surface resistance was tested according to the ESD STM 11.11-2021 standard.

[0089] The types of plastics, actual carbon nanotube content (wt%), and specific test results in the conductive composite materials of carbon nanotube conductive masterbatches obtained by the preparation methods provided in Examples 1-8 and Comparative Examples 1 and 2 are shown in Table 1.

[0090] Table 1

[0091]

[0092] As shown in Table 1, the carbon nanotube conductive masterbatch obtained by the preparation method provided by the present invention has carbon nanotubes that are easier to disperse; it achieves a comparable level of conductivity. The amount of carbon nanotubes required to add the conductive masterbatch prepared by the method provided by the present invention is 1.5-4% less than that required for masterbatch prepared by traditional methods; the economic benefits are significant; and the conductive masterbatch prepared by the method provided by the present invention has lower surface resistance and better conductivity.

[0093] The applicant declares that the above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a carbon nanotube conductive master batch, characterized by, The preparation method comprises the following steps: (1) mixing carbon nanotubes, a dispersant and a first solvent to obtain a carbon nanotube dispersion; mixing thermoplastic polyurethane and a second solvent to obtain a resin solution; (2) mixing the carbon nanotube dispersion and the resin solution obtained in step (1) to obtain a paste; (3) extruding the paste obtained in step (2) to obtain the carbon nanotube conductive master batch.

2. The production method according to claim 1, characterized by, The carbon nanotubes in step (1) comprise multi-walled carbon nanotubes; Preferably, the dispersant in step (1) comprises an oil-soluble dispersant; Preferably, the mass of the dispersant in step (1) is 5-60% of the mass of the carbon nanotubes, and further preferably 15-30%.

3. The production method according to claim 1 or 2, characterized by, The first solvent in step (1) comprises N-methyl pyrrolidone; Preferably, the mass concentration of the carbon nanotube dispersion in step (1) is 8-20%; Preferably, the temperature of the first mixing in step (1) is 60-80°C; Preferably, the first mixing in step (1) is performed in a grinding device; Preferably, the D50 of the carbon nanotube dispersion in step (1) is 0.5-2.5 μm.

4. The process according to any one of claims 1 to 3, characterized in that, The second solvent in step (1) comprises N-methyl pyrrolidone; Preferably, the mass concentration of the resin solution in step (1) is 10-20%; Preferably, the temperature of the second mixing in step (1) is 60-80°C.

5. The process according to any one of claims 1 to 4, characterized in that, The temperature of the third mixing in step (2) is 60-80°C; Preferably, the temperatures of the first mixing, the second mixing and the third mixing are the same.

6. The method of any one of claims 1 to 5, wherein the method further comprises, After the third mixing in step (2), the temperature is further reduced to room temperature.

7. The process according to any one of claims 1 to 6, characterized in that, The temperature of the extrusion in step (3) is room temperature; Preferably, after the extrusion in step (3), the paste is further subjected to granulation and / or drying; Preferably, the carbon nanotube conductive master batch comprises 10-30% carbon nanotubes, 2-6% dispersant and 64-88% thermoplastic polyurethane by mass percentage.

8. The process according to any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: (1) adding multi-walled carbon nanotubes, a dispersant and N-methyl pyrrolidone to a grinding device and mixing and dispersing at a temperature of 60-80°C until the D50 of the obtained carbon nanotube dispersion is 0.5-2.5 μm; mixing thermoplastic polyurethane and N-methyl pyrrolidone at a temperature of 60-80°C to obtain a resin solution; (2) mixing the carbon nanotube dispersion and the resin solution obtained in step (1) uniformly at a temperature of 60-80°C, and then reducing the temperature to room temperature to obtain a paste; (3) extruding the paste obtained in step (2) at room temperature, granulating and drying to obtain the carbon nanotube conductive master batch.

9. A carbon nanotube conductive master batch, characterized by, The carbon nanotube conductive master batch is prepared by the preparation method of any one of claims 1-8.

10. An electrically conductive composite material, characterized by The conductive composite material comprises the carbon nanotube conductive master batch of claim 9.

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