Conductive carbon black, method for producing the same, shielding material, and high-voltage cable

Abstract

This application provides a conductive carbon black, its preparation method, a shielding material, and a high-voltage cable. The preparation method includes the following steps: mixing a structure-modifying liquid precursor with water to obtain a structure-modifying liquid; the structure-modifying liquid precursor includes at least one of dopamine hydrochloride, tannic acid, citric acid, and tartaric acid; using the structure-modifying liquid to wet-granulate powdered conductive carbon black to obtain wet conductive carbon black particles; and sequentially drying, sieving, and calcining the wet conductive carbon black particles to obtain conductive carbon black. The preparation method of this application first coats the surface of powdered conductive carbon black with a polyhydroxy polar structure-modifying liquid through wet granulation, forming an in-situ coating layer to prevent the conductive carbon black from agglomerating due to electrostatic adsorption, resulting in conductive carbon black with excessively high structure; and then, through drying and calcination, transforms the polar coating layer into a highly ordered graphitic carbon coating layer, thereby effectively improving the electrical properties of the conductive carbon black.

Description

Technical Field

[0001] This application relates to the field of high-voltage cable technology, and in particular to a conductive carbon black and its preparation method, shielding material and high-voltage cable. Background Technology

[0002] High-voltage cables are a crucial component of power transmission, and their semi-conductive shielding materials are essential for ensuring safe operation. The performance of semi-conductive shielding materials depends not only on the properties of the matrix resin itself but also on the structure and conductivity of the conductive carbon black.

[0003] Granulation is a crucial step in the production of conductive carbon black. Wet granulation, with its advantages of high efficiency, low environmental pollution, and high production capacity, is the primary method for conductive carbon black granulation. However, traditional wet granulation processes for conductive carbon black struggle to effectively control the microstructure and morphology of the carbon black, often resulting in problems such as excessively high structural density and poor conductivity, thus limiting its application in high-voltage cables.

[0004] Therefore, traditional conductive carbon black still needs further improvement. Summary of the Invention

[0005] Based on this, one or more embodiments of this application provide a conductive carbon black with moderate structural density and excellent conductivity, a method for preparing the same, a shielding material, and a high-voltage cable.

[0006] According to a first aspect of the embodiments of this application, a method for preparing conductive carbon black is provided, comprising the following steps:

[0007] A structure-modifying liquid precursor is prepared by mixing it with water; the structure-modifying liquid precursor includes at least one of dopamine hydrochloride, tannic acid, citric acid and tartaric acid.

[0008] The structure-regulating liquid is used to wet granulate powdered conductive carbon black to obtain conductive carbon black wet particles; the conductive carbon black wet particles are then dried, sieved and calcined to obtain conductive carbon black.

[0009] In one embodiment, the ratio of the structure-regulating liquid precursor to water is 1 g:(1000 mL~3000 mL).

[0010] In one embodiment, the method further includes the step of adjusting the pH of the structure conditioning solution to 7.0-9.0 using a buffer solution;

[0011] Optionally, the buffer solution comprises tris(hydroxymethyl)aminomethane hydrochloride.

[0012] In one embodiment, the preparation method satisfies at least one of the following characteristics:

[0013] (1) The injection rate of the structure conditioning liquid in the wet granulation step is 1000 kg / h to 9000 kg / h;

[0014] (2) The ratio of the powdered conductive carbon black to the structure conditioning liquid is 100g:(50mL~120mL).

[0015] In one embodiment, the preparation method satisfies at least one of the following characteristics:

[0016] (1) The drying temperature is 150℃~300℃;

[0017] (2) The mesh size of the sieve is 1mm~2mm.

[0018] In one embodiment, the calcination process is carried out under an inert atmosphere, the inert atmosphere comprising one or more of N2 and Ar, and the flow rate of the inert atmosphere is 30 mL / min to 50 mL / min.

[0019] In one embodiment, the preparation method satisfies at least one of the following characteristics:

[0020] (1) The calcination temperature is 900℃~1200℃ and the time is 0.5h~2h;

[0021] (2) The heating rate of the calcination treatment is 2℃ / min~20℃ / min.

[0022] According to a second aspect of the embodiments of this application, a conductive carbon black is provided, which is prepared by the above-described method for preparing conductive carbon black.

[0023] According to a third aspect of the embodiments of this application, a shielding material is provided, comprising the above-described conductive carbon black.

[0024] According to a fourth aspect of the embodiments of this application, a high-voltage cable is provided, comprising the shielding material described above.

[0025] Compared with traditional technologies, this application has the following advantages:

[0026] The preparation method of this application first involves coating the surface of powdered conductive carbon black with a polyhydroxy polar structure regulating liquid through wet granulation, forming a coating layer in situ to prevent the conductive carbon black from agglomerating due to electrostatic adsorption and forming conductive carbon black with excessively high structure, thereby giving the conductive carbon black better dispersibility; and then through drying and calcination treatment, the polar coating layer is transformed into a highly ordered graphitic carbon coating layer, thereby effectively improving the electrical properties of the conductive carbon black. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram illustrating the preparation principle of conductive carbon black in one embodiment of this application;

[0029] Figure 2 The absorbance values ​​of dibutyl phthalate (DBP) in conductive carbon black in Examples 1-5 and Comparative Examples 1-2 of this application are as follows:

[0030] Figure 3 The intrinsic powder resistivity test results are for the conductive carbon black in Examples 1-5 and Comparative Examples 1-2 of this application. Detailed Implementation

[0031] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.

[0033] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In this application, "at least one" means one or more, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0034] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0035] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0036] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0037] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant temperature treatment or variations within a certain temperature range. It should be understood that the constant temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0038] Some embodiments of this application provide a method for preparing conductive carbon black, including steps S10 to S30.

[0039] Step S10: Mix the structure conditioning liquid precursor with water to obtain the structure conditioning liquid; the structure conditioning liquid precursor includes at least one of dopamine hydrochloride, tannic acid, citric acid and tartaric acid.

[0040] Step S20: The powdered conductive carbon black is wet-granulated using a structure-regulating liquid to obtain wet conductive carbon black granules.

[0041] Step S30: The wet conductive carbon black particles are successively dried, sieved and calcined to obtain conductive carbon black.

[0042] This application employs a wet granulation process to coat the surface of powdered conductive carbon black with a multi-hydroxyl polar structure regulating liquid, forming a coating layer in situ. This prevents the formation of conductive carbon black with excessively high structure due to electrostatic adsorption. Then, through drying and calcination processes, the polar coating layer is transformed into a highly ordered graphite carbon coating layer, thereby effectively improving the conductivity of the conductive carbon black.

[0043] In this application, "structure degree" refers to the morphology and complexity of carbon black particle aggregates, reflecting the way and degree of interconnection between carbon black particles.

[0044] In wet granulation processes, the structure-regulating liquid, under neutral or weakly alkaline conditions, can form a polar coating layer in situ on the surface of powdered conductive carbon black through a self-polymerization reaction. This polar coating layer acts as a seal and barrier, preventing excessive aggregation of the primary structure of the conductive carbon black. Aggregation of conductive carbon black typically leads to excessively high structure density, and when combined with a polymer matrix resin, it also reduces the dispersion performance of the conductive carbon black in semi-conductive shielding materials.

[0045] High-structure conductive carbon black has a large specific surface area and a strong adsorption capacity for polymer binders, liquids, and polymer electrolytes. This strong adsorption causes carbon black particles to bind tightly to binders and other substances, forming large agglomerates, which increases the difficulty of dispersion.

[0046] In some specific embodiments, the polar coating layer includes a dopamine hydrochloride layer, a tannic acid layer, a citric acid layer, or a tartaric acid layer.

[0047] Wet granulation improves the wettability of conductive carbon black particles through a liquid medium, reducing friction and electrostatic interactions between particles, thereby minimizing secondary aggregation. The network structure formed by interparticle interactions affects the stability and overall structure of the aggregates. Therefore, by coating the granulation process with a polyhydroxy polar molecular layer and adjusting its thickness and properties, the structure of conductive carbon black can be controlled, resulting in conductive carbon black with excellent dispersion properties.

[0048] Figure 1 This is a schematic diagram illustrating the principle of regulating the structure of conductive carbon black and improving its conductivity in some embodiments of this application.

[0049] In some specific embodiments, the raw materials for preparing powdered conductive carbon black include one or more of anthracene oil, ethylene tar, and coal tar.

[0050] In some specific embodiments, the preparation method of powdered conductive carbon black includes a furnace method; optionally, the preparation method of powdered conductive carbon black includes an oil furnace method.

[0051] In some specific embodiments, the average particle size of the powdered conductive carbon black is 36 nm to 40 nm. As an example, the average particle size of the powdered conductive carbon black can be, but is not limited to, specific values ​​such as 36 nm, 37 nm, 38 nm, 39 nm, or 40 nm. Further, the average particle size of the powdered conductive carbon black is 38 nm.

[0052] In some specific embodiments, the iodine absorption value of the powdered conductive carbon black is 65 g / kg to 75 g / kg. As examples, the iodine absorption value of the powdered conductive carbon black can be, but is not limited to, 65 g / kg, 66 g / kg, 67 g / kg, 68 g / kg, 69 g / kg, 70 g / kg, 71 g / kg, 72 g / kg, 73 g / kg, 74 g / kg, or 75 g / kg. Further, the iodine absorption value of the powdered conductive carbon black is 70 g / kg.

[0053] In some specific embodiments, the 325-mesh sieve residue of the conductive carbon black comprises 6 ppm of powder.

[0054] In some specific embodiments, the ash content of the conductive carbon black is 0.05% to 0.11%. As an example, the ash content of the conductive carbon black can be, but is not limited to, specific values ​​such as 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, or 0.11%. Further, the ash content of the conductive carbon black is 0.08%.

[0055] In some embodiments, the ratio of the structure conditioning liquid precursor to water is 1 g:(1000 mL to 3000 mL). As an example, the ratio of the structure conditioning liquid precursor to water can be, but is not limited to, specific ratios such as 1 g:1000 mL, 1 g:1500 mL, 1 g:2000 mL, 1 g:2500 mL, 1 g:3000 mL, etc.

[0056] Understandably, a ratio of 1g:1000mL for the structure conditioning fluid precursor to water means mixing 1000mL of deionized water with 1g of the structure conditioning fluid precursor.

[0057] Furthermore, the ratio of the structure-regulating liquid precursor to water is 1 g:(1000 mL~2500 mL).

[0058] Furthermore, the ratio of the structure-regulating liquid precursor to water is 1 g:(1000 mL~1800 mL).

[0059] By adjusting the concentration of the structure conditioning liquid, the thickness and properties of the polar coating layer can be further optimized, thereby controlling the structural characteristics of the conductive carbon black.

[0060] In some embodiments, the method further includes adjusting the pH of the structure conditioning solution to 7.0-9.0 using a buffer solution. As an example, the pH of the structure conditioning solution may be, but is not limited to, specific values ​​such as 7.0, 7.5, 8.0, 8.5, or 9.0.

[0061] In some specific embodiments, the buffer solution comprises tris(hydroxymethyl)aminomethane hydrochloride. It should be noted that other buffer solutions known in the art can also be used to adjust the pH of the structure-regulating solution, as long as they achieve the purpose of this application, and are not limited to the types listed herein.

[0062] In some embodiments, the injection rate of the structure conditioning liquid in the wet granulation step is 1000 kg / h to 9000 kg / h. As an example, the injection rate of the structure conditioning liquid can be, but is not limited to, specific values ​​such as 1000 kg / h, 2000 kg / h, 3000 kg / h, 4000 kg / h, 5000 kg / h, 6000 kg / h, 7000 kg / h, 8000 kg / h, or 9000 kg / h.

[0063] In some embodiments, the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:(50mL~120mL). As an example, the ratio of powdered conductive carbon black to structure conditioning liquid can be, but is not limited to, specific values ​​such as 100g:50mL, 100g:60mL, 100g:70mL, 100g:80mL, 100g:90mL, 100g:100mL, 100g:110mL, or 100g:120mL.

[0064] In some embodiments, the drying temperature is 150°C to 300°C. As an example, the drying temperature can be, but is not limited to, specific values ​​such as 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 250°C, or 300°C.

[0065] In some specific embodiments, a rotary dryer is used for drying.

[0066] It is understandable that drying can remove moisture and other impurities from the wet conductive carbon black particles, thereby obtaining conductive carbon black particles with a polar molecular layer on the surface.

[0067] In some embodiments, the mesh size of the sieve is 1mm to 2mm. As an example, the mesh size of the sieve can be, but is not limited to, specific values ​​such as 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2.0mm.

[0068] In some specific embodiments, a drum is used for sieving.

[0069] In some embodiments, the calcination process is carried out under an inert atmosphere, which includes one or more of N2 and Ar, and the flow rate of the inert atmosphere is 30 mL / min to 50 mL / min.

[0070] As an example, the flow rate of the inert atmosphere can be, but is not limited to, specific values ​​such as 30 mL / min, 35 mL / min, 40 mL / min, 45 mL / min, or 50 mL / min.

[0071] Under inert atmosphere and high temperature conditions, the polar coating layer undergoes a pyrolysis reaction. During this process, the polar polymer coating layer undergoes deoxidation and dehydrogenation, generating a dense surface carbon layer. Specifically, the polar coating layer undergoes pyrolysis and carbonization at high temperatures, forming an ordered graphite structure with high electrical conductivity. This process removes impurities such as hydrogen and oxygen from the polar polymer layer, promotes the formation of covalent bonds between carbon atoms, thereby improving the integrity of the conductive network, reducing the resistance to current conduction between carbon black particles, promoting electron flow, and ultimately increasing the conductivity of the conductive carbon black.

[0072] In some embodiments, the calcination temperature is 900℃~1200℃, and the time is 0.5h~2h. As an example, the calcination temperature can be, but is not limited to, specific values ​​such as 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, or 1200℃; the calcination time can be, but is not limited to, specific values ​​such as 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.5h, or 2h.

[0073] In some embodiments, the heating rate of the calcination treatment is 2°C / min to 20°C / min. Specific values ​​can be, but are not limited to, 2°C / min, 4°C / min, 6°C / min, 8°C / min, 10°C / min, 15°C / min, or 20°C / min.

[0074] Furthermore, the heating rate of the calcination treatment is 10℃ / min~20℃ / min.

[0075] Furthermore, the heating rate of the calcination treatment is 15℃ / min~20℃ / min.

[0076] The method described in this application for preparing conductive carbon black has the advantages of simple process, high efficiency and controllable structure of conductive carbon black.

[0077] Some embodiments of this application also provide a conductive carbon black, which is prepared using the above-described method for preparing conductive carbon black.

[0078] Compared with traditional conductive carbon black, the conductive carbon black prepared in this application has advantages such as moderate structure and excellent conductivity.

[0079] Some embodiments of this application also provide a shielding material comprising the aforementioned conductive carbon black.

[0080] Understandably, the raw materials for preparing shielding materials also include polymer resins and other raw materials. The aforementioned conductive carbon black, when combined with polymer resin, exhibits excellent dispersibility.

[0081] Some embodiments of this application also provide a high-voltage cable, including a semi-conductive shielding layer made using the shielding material described above.

[0082] In some embodiments, the high-voltage cable further includes one or more of a conductor layer, an insulation layer, a metallic shielding layer, and a sheath layer.

[0083] The present application will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present application. Unless otherwise specified, the raw materials involved in the following specific embodiments are all commercially available, the instruments used are all commercially available, and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0084] The specific parameters of the powdered conductive carbon black used in the embodiments and comparative examples of this application are as follows: it is prepared by using anthracene oil as raw material and a traditional oil furnace method; the average particle size is 38 nm, the iodine absorption value is 70 g / kg, the residue on a 325 mesh sieve is 6 ppm, and the ash content is 0.08%.

[0085] Example 1

[0086] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed in a ratio of 1000 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0087] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0088] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0089] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0090] (4) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1000℃ at a heating rate of 10℃ / min and held for 0.5 h to prepare conductive carbon black.

[0091] Example 2

[0092] It is basically the same as Example 1, except that the ratio of deionized water and dopamine hydrochloride is different in step (1). The specific steps are as follows.

[0093] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed in a ratio of 1800 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0094] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0095] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0096] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0097] (4) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1000℃ at a heating rate of 10℃ / min and held for 0.5 h to prepare conductive carbon black.

[0098] Example 3

[0099] It is basically the same as Example 1, except that the ratio of deionized water and dopamine hydrochloride is different in step (1). The specific steps are as follows.

[0100] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed at a ratio of 2500 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0101] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0102] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0103] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0104] (4) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1000℃ at a heating rate of 10℃ / min and held for 0.5 h to prepare conductive carbon black.

[0105] Example 4

[0106] It is basically the same as Example 3, except that the heating rate and calcination temperature of the calcination treatment in step (4) are different. The specific steps are as follows.

[0107] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed at a ratio of 2500 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0108] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0109] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0110] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0111] (4) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1200℃ at a heating rate of 20℃ / min and held for 0.5 h to prepare conductive carbon black.

[0112] Example 5

[0113] It is basically the same as Example 1, except that the ratio of deionized water and dopamine hydrochloride is different in step (1). The specific steps are as follows.

[0114] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed in a ratio of 3000 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0115] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0116] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0117] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0118] (4) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1000℃ at a heating rate of 10℃ / min and held for 0.5 h to prepare conductive carbon black.

[0119] Comparative Example 1

[0120] The procedure is basically the same as in Example 1, except that deionized water is used instead of the structure conditioning solution. The specific steps are as follows.

[0121] (1) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and deionized water is injected for full atomization; the ratio of powdered conductive carbon black to deionized water is 100g:50mL, and the injection flow rate of the structure conditioning liquid is 4000kg / h.

[0122] Powdered conductive carbon black and deionized water undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0123] (2) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0124] (3) Calcination treatment: N2 with a flow rate of 50 mL / min is introduced into the conductive carbon black powder, and the temperature is raised to 1000℃ at a heating rate of 10℃ / min and held for 0.5 h to prepare conductive carbon black.

[0125] Comparative Example 2

[0126] It is basically the same as Example 5, except that the calcination step is not included. The specific steps are as follows.

[0127] (1) Preparation of structure conditioning solution: Deionized water and dopamine hydrochloride were mixed in a ratio of 3000 mL: 1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain the structure conditioning solution.

[0128] (2) Wet granulation: Powdered conductive carbon black is pre-added into a stirring tooth granulator and injected with structure conditioning liquid for full atomization; the ratio of powdered conductive carbon black to structure conditioning liquid is 100g:50mL, and the injection flow rate of structure conditioning liquid is 4000kg / h.

[0129] Powdered conductive carbon black and structure conditioning liquid undergo degassing, wetting, granulation, compaction and polishing processes under the action of high-speed stirring teeth to obtain wet conductive carbon black particles.

[0130] (3) Drying and sieving: The wet conductive carbon black particles are thoroughly dried in a rotary dryer at 200°C and then sieved through a 1.2 mm drum to obtain conductive carbon black powder.

[0131] Some parameters in the above embodiments and comparative examples are shown in Table 1.

[0132] Table 1

[0133]

[0134] Performance testing

[0135] (a) Conductive carbon black is composed of aggregates of chain-branched structures formed by the melting of primary particles (commonly known as primary structure) and agglomerates formed by mutual attraction through van der Waals forces (commonly known as secondary structure). The combination of the primary and secondary structures of conductive carbon black is collectively referred to as its structure degree. The oil absorption value of dibutyl phthalate (DBP) refers to the volume (cm³) of DBP absorbed by 100g of conductive carbon black under specified test conditions. 3 The higher the value of the conductive carbon black number, the higher its structural density. To measure the effect of polar molecular layer coating on the structural density of conductive carbon black, the oil absorption value of the conductive carbon black in each example and comparative example was tested using DBP; the results are shown in Table 2 and... Figure 2 As shown.

[0136] Table 2

[0137]

[0138] (b) To test the effect of the ordered graphitized layer formed during the calcination process on the resistivity of conductive carbon black, the intrinsic powder resistivity of the conductive carbon black prepared in each example and comparative example was tested using a four-probe tester; the results are shown in Table 3 and... Figure 3 As shown.

[0139] Table 3

[0140]

[0141] As can be seen from Examples 1-5 and Comparative Example 1, the polyhydroxy polar structure regulating liquid can effectively control the structure degree and resistivity of conductive carbon black. Increasing the concentration of the structure regulating liquid can effectively reduce the structure degree of conductive carbon black and prevent the conductive carbon black from having too high a structure degree, which would cause dispersion problems in the matrix resin.

[0142] As can be seen from Examples 1-5 and Comparative Example 2, calcination treatment can significantly reduce the resistivity of conductive carbon black, and the higher the temperature, the lower the resistivity.

[0143] Examples 1-5 of this application employ a multi-hydroxyl polar structure regulating liquid for wet granulation, combined with drying and calcination. The synergistic effect of each step results in conductive carbon black with a suitable degree of structure, which meets the dispersion requirements of conductive fillers in high-voltage cable semi-conductive shielding materials. The highly ordered graphitized carbon layer formed after calcination provides a high-quality channel for electron transport, thus meeting the electrical performance requirements of conductive carbon black in high-voltage cable semi-conductive shielding materials.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing conductive carbon black, characterized in that, Includes the following steps: A structure-modifying liquid precursor is mixed with water to prepare a structure-modifying liquid; the structure-modifying liquid precursor includes at least one of dopamine hydrochloride and tannic acid. The pH of the structure conditioning solution was adjusted to 7.0-9.0 using a buffer solution; the powdered conductive carbon black was wet-granulated using the structure conditioning solution to obtain wet conductive carbon black particles; the wet conductive carbon black particles were then dried, sieved, and calcined sequentially to obtain conductive carbon black.

2. The method for preparing conductive carbon black according to claim 1, characterized in that, The ratio of the structure-regulating liquid precursor to water is 1 g:(1000 mL~3000 mL).

3. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that, The buffer solution comprises trihydroxymethylaminomethane hydrochloride.

4. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The injection rate of the structure conditioning liquid in the wet granulation step is 1000 kg / h to 9000 kg / h; (2) The ratio of the powdered conductive carbon black to the structure conditioning liquid is 100g:(50mL~120mL).

5. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The drying temperature is 150℃~300℃; (2) The mesh size of the sieve is 1mm~2mm.

6. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that, The calcination process is carried out under an inert atmosphere, wherein the inert atmosphere includes one or more of N2 and Ar, and the flow rate of the inert atmosphere is 30 mL / min to 50 mL / min.

7. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The calcination temperature is 900℃~1200℃ and the time is 0.5h~2h; (2) The heating rate of the calcination treatment is 2℃ / min~20℃ / min.

8. A conductive carbon black, characterized in that, It is prepared by the method described in any one of claims 1 to 7.

9. A shielding material, characterized in that, It includes the conductive carbon black as described in claim 8.

10. A high-voltage cable, characterized in that, Includes the shielding material as described in claim 9.

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