Conductive carbon black and preparation method thereof, shielding material and high-voltage cable

Abstract

The invention provides conductive carbon black and a preparation method thereof, a shielding material and a high-voltage cable. The preparation method comprises the following steps: mixing a structure adjusting liquid precursor with water to prepare a structure adjusting liquid; the structure adjusting liquid precursor comprises at least one of dopamine hydrochloride, tannic acid, citric acid and tartaric acid; carrying out wet granulation on the powdery conductive carbon black by adopting the structure adjusting liquid to prepare conductive carbon black wet particles; and sequentially drying, sieving and calcining the conductive carbon black wet particles to prepare the conductive carbon black. According to the preparation method, firstly, the surface of the powdery conductive carbon black is coated with the polyhydroxy polar structure adjusting liquid through wet granulation, a coating layer is formed in situ, and the situation that the conductive carbon black is gathered due to the electrostatic adsorption effect to form the conductive carbon black with the too high structural degree is prevented; and the polar coating layer is converted into a highly ordered graphite carbon coating layer through drying and calcining treatment, so that the electrical property of the conductive carbon black is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of high-voltage cables, and in particular to a conductive carbon black and a preparation method thereof, a shielding material and a high-voltage cable. Background Art

[0002] High-voltage cables are an important part of power transmission, and their semi-conductive shielding materials are an important factor in ensuring the safe operation of cables. The performance of semi-conductive shielding materials not only depends on the properties of the matrix resin itself, but also is affected by the structure and conductivity of the conductive carbon black.

[0003] Granulation is an important process in the production of conductive carbon black. Among them, the wet granulation process has the advantages of high efficiency, low environmental pollution, and high production capacity. It is the main way to granulate conductive carbon black. The traditional conductive carbon black wet granulation process is difficult to effectively adjust the microstructure and morphology of carbon black, which easily leads to problems such as high structural degree and poor conductivity of conductive carbon black, limiting its application in the field of high-voltage cables.

[0004] Therefore, it is still necessary to further improve the traditional conductive carbon black. Summary of the invention

[0005] Based on this, one or more embodiments of the present application provide a conductive carbon black with moderate structure and excellent conductive properties, a preparation method thereof, a shielding material and a high-voltage cable.

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

[0007] Mixing a structure regulating liquid precursor with water to prepare a structure regulating liquid; the structure regulating liquid precursor comprises 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 sequentially dried, sieved and calcined to obtain conductive carbon black.

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

[0010] In one embodiment, the following steps are also included: adjusting the pH value of the structure regulating solution to 7.0-9.0 using a buffer solution;

[0011] Optionally, the buffer comprises Tris-HCl.

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

[0013] (1) The injection rate of the structure regulating 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 regulating liquid is 100 g:(50 mL~120 mL).

[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 aperture of the sieve is 1mm~2mm.

[0018] In one embodiment, the calcination process is carried out under an inert atmosphere, wherein the inert atmosphere comprises N 2 and Ar, and the flow rate of the inert atmosphere is 30 mL / min~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°C to 1200°C and the time is 0.5h to 2h;

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

[0022] According to a second aspect of an embodiment of the present application, a conductive carbon black is provided, which is prepared by using the above-mentioned method for preparing conductive carbon black.

[0023] According to a third aspect of an embodiment of the present application, a shielding material is provided, comprising the above-mentioned conductive carbon black.

[0024] According to a fourth aspect of an embodiment of the present application, there is provided a high-voltage cable comprising the above-mentioned shielding material.

[0025] Compared with the traditional technology, this application has the following beneficial effects:

[0026] The preparation method of the present application firstly coats the surface of powdered conductive carbon black with a polyhydroxy polar structure regulating liquid through wet granulation to form a coating layer in situ, thereby preventing the conductive carbon black from aggregating due to electrostatic adsorption to form conductive carbon black with a too high structure, thereby making the conductive carbon black have better dispersibility; and converts the polar coating layer into a highly ordered graphite carbon coating layer through drying and calcination treatment, thereby effectively improving the electrical properties of the conductive carbon black. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0029] Figure 2 The absorption value test results of dibutyl phthalate (DBP) of the conductive carbon black in Examples 1 to 5 and Comparative Examples 1 to 2 of the present application;

[0030] Figure 3 These are the test results of the intrinsic powder resistivity of the conductive carbon black in Examples 1 to 5 of the present application and Comparative Examples 1 to 2. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present application, etc. can be purchased from the market 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 clearly and specifically defined. In this application, "at least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0034] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

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

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

[0037] The temperature parameters of the present application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

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

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

[0040] Step S20: wet granulating the powdered conductive carbon black with a structure regulating liquid to obtain conductive carbon black wet granules.

[0041] Step S30: drying, sieving and calcining the conductive carbon black wet particles in sequence to obtain conductive carbon black.

[0042] The present application uses a wet granulation process to coat a polyhydroxy polar structure regulating liquid on the surface of powdered conductive carbon black to form a coating layer in situ to prevent the conductive carbon black from aggregating to form a too-high structure due to electrostatic adsorption. The polar coating layer is then dried and calcined to form a highly ordered graphite carbon coating layer, thereby effectively improving the conductive properties of the conductive carbon black.

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

[0044] In the wet granulation process, the structure regulating liquid can form a polar coating layer on the surface of powdered conductive carbon black in situ through self-polymerization reaction under neutral or weak alkaline conditions; the polar coating layer formed on the surface of conductive carbon black can play a role of sealing and isolation, preventing excessive aggregation of the primary structure of conductive carbon black. The aggregation of conductive carbon black usually leads to excessively high structure, which will also reduce the dispersion performance of conductive carbon black in semi-conductive shielding materials after compounding with polymer matrix resin.

[0045] Conductive carbon black with high structure has a large specific surface area and has a strong adsorption capacity for polymer binders, liquid and polymer electrolytes, etc. This strong adsorption will cause carbon black particles to be closely combined with binders and other substances to form larger agglomerates, thereby increasing 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 liquid medium, reduces friction and electrostatic interaction between particles, and thus reduces secondary aggregation of particles; the network structure formed by the interaction between particles will affect the stability and overall structure of the aggregate. Therefore, in the granulation process, the structure of conductive carbon black can be regulated by coating the multi-hydroxy polar molecular layer and adjusting its thickness and properties, and conductive carbon black with excellent dispersion characteristics can be obtained.

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

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

[0050] In some specific embodiments, the method for preparing powdered conductive carbon black comprises a furnace method; alternatively, the method for preparing powdered conductive carbon black comprises 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 an example, the iodine absorption value of the powdered conductive carbon black can be, but is not limited to, specific values ​​such as 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 screen residue of the conductive carbon black includes 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 adjustment liquid precursor to water is 1g:(1000mL~3000mL). As an example, the ratio of the structure adjustment liquid precursor to water can be, but is not limited to, 1g:1000mL, 1g:1500mL, 1g:2000mL, 1g:2500mL, 1g:3000mL, and other specific ratios.

[0056] It can be understood that the ratio of the structure adjustment liquid precursor to water is 1 g:1000 mL, which means that 1000 mL of deionized water is mixed with 1 g of the structure adjustment liquid 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 regulating liquid, the thickness and properties of the polar coating layer can be further optimized, thereby regulating the structural properties of the conductive carbon black.

[0060] In some embodiments, the following step is further included: adjusting the pH value of the structure regulating solution to 7.0-9.0 using a buffer solution. As an example, the pH value of the structure regulating solution is, but is not limited to, 7.0, 7.5, 8.0, 8.5 or 9.0.

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

[0062] In some embodiments, the injection rate of the structure regulating liquid in the wet granulation step is 1000 kg / h to 9000 kg / h. As an example, the injection rate of the structure regulating 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 regulating liquid is 100 g: (50 mL to 120 mL). As an example, the ratio of powdered conductive carbon black to structure regulating liquid can be, but is not limited to, 100 g: 50 mL, 100 g: 60 mL, 100 g: 70 mL, 100 g: 80 mL, 100 g: 90 mL, 100 g: 100 mL, 100 g: 110 mL or 100 g: 120 mL.

[0064] In some embodiments, the drying temperature is 150° C. to 300° C. As an example, the drying temperature may 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, drying is performed using a rotary dryer.

[0066] It can be understood that moisture and other impurities in the wet conductive carbon black particles can be removed by drying, thereby obtaining conductive carbon black particles with a polar molecule layer coated on the surface.

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

[0068] In some embodiments, the screening is performed using a drum.

[0069] In some embodiments, the calcination process is carried out under an inert atmosphere, wherein the inert atmosphere comprises N 2 and Ar, the flow rate of the inert atmosphere is 30 mL / min~50 mL / min.

[0070] As an example, the flow rate of the inert atmosphere may 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] The polar coating layer undergoes a pyrolysis reaction under an inert atmosphere and high temperature conditions. During this process, the polar polymer coating layer undergoes a deoxidation and dehydrogenation process to generate a dense surface carbon layer. Specifically, the polar coating layer undergoes a pyrolysis and carbonization process at high temperature to form an ordered graphite structure with high electrical conductivity. This process removes impurity elements such as hydrogen and oxygen in the polar polymer layer and promotes the formation of covalent bonds between carbon atoms, thereby improving the integrity of the conductive network, reducing the resistance of current conduction between carbon black particles, and promoting the flow of electrons, thereby improving the electrical conductivity of the conductive carbon black.

[0072] In some embodiments, the calcination temperature is 900°C to 1200°C, and the time is 0.5h to 2h. As an example, the calcination temperature may be, but not limited to, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, or 1200°C; the calcination time may be, but not limited to, 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 process is 2°C / min to 20°C / min, and may be, but not limited to, specific values ​​such as 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°C / min~20°C / min.

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

[0076] The conductive carbon black is prepared by the method of the present application, which has the advantages of simple process, high efficiency and controllable structure of the conductive carbon black.

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

[0078] Compared with traditional conductive carbon black, the conductive carbon black prepared in the present application has the advantages of moderate structure and excellent conductive performance.

[0079] Some embodiments of the present application also provide a shielding material comprising the above-mentioned conductive carbon black.

[0080] It is understandable that the raw materials for preparing the shielding material also include raw materials such as polymer resins, etc. The above-mentioned conductive carbon black has good dispersion performance after being compounded with the polymer resin.

[0081] Some embodiments of the present application also provide a high-voltage cable, comprising a semi-conductive shielding layer made of the above-mentioned shielding material.

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

[0083] The present application will be further described below in conjunction with specific examples and comparative examples, but they should not be construed as limiting the scope of protection of the present application. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources, the instruments used, unless otherwise specified, can all be sourced from commercial sources, and the processes involved, unless otherwise specified, are all conventionally selected by those skilled in the art.

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

[0085] Example 1

[0086] (1) Preparation of a structure-adjusting 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 a structure-adjusting solution.

[0087] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

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

[0090] (4) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2 The temperature was raised to 1000°C at a heating rate of 10°C / min and kept at that temperature for 0.5h to prepare conductive carbon black.

[0091] Example 2

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

[0093] (1) Preparation of a structure-adjusting 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 a structure-adjusting solution.

[0094] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

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

[0097] (4) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2 The temperature was raised to 1000°C at a heating rate of 10°C / min and kept at that temperature for 0.5h to prepare conductive carbon black.

[0098] Example 3

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

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

[0101] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

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

[0104] (4) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2 The temperature was raised to 1000°C at a heating rate of 10°C / min and kept at that temperature for 0.5h 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 a structure-adjusting solution: deionized water and dopamine hydrochloride were mixed in a ratio of 2500 mL:1 g, and tris(hydroxymethyl)aminomethane hydrochloride was added to adjust the pH value to 8.5 to obtain a structure-adjusting solution.

[0108] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

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

[0111] (4) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2 The temperature was raised to 1200°C at a heating rate of 20°C / min and kept at that temperature for 0.5h to prepare conductive carbon black.

[0112] Example 5

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

[0114] (1) Preparation of a structure-adjusting 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 a structure-adjusting solution.

[0115] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

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

[0118] (4) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2 The temperature was raised to 1000°C at a heating rate of 10°C / min and kept at that temperature for 0.5h to prepare conductive carbon black.

[0119] Comparative Example 1

[0120] It is basically the same as Example 1, except that deionized water is used instead of the structure regulating liquid. The specific steps are as follows.

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

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

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

[0124] (3) Calcination treatment: N2 at a flow rate of 50 mL / min was introduced into the conductive carbon black powder. 2The temperature was raised to 1000°C at a heating rate of 10°C / min and kept at that temperature for 0.5h to prepare conductive carbon black.

[0125] Comparative Example 2

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

[0127] (1) Preparation of a structure-adjusting 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 a structure-adjusting solution.

[0128] (2) Wet granulation: Pre-place the powdered conductive carbon black into a stirring tooth granulator and inject the structure adjustment liquid to fully atomize it; the addition ratio of the powdered conductive carbon black and the structure adjustment liquid is 100g:50mL, and the injection flow rate of the structure adjustment liquid is 4000kg / h.

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

[0130] (3) Drying and sieving: The conductive carbon black wet particles are fully dried at 200°C in a rotary dryer and 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 chain branch structure aggregates (commonly known as primary structure) formed by the melting of primary particles and agglomerates (commonly known as secondary structure) formed by the van der Waals force. The combination of the primary and secondary structures of conductive carbon black is collectively referred to as the structural degree. The oil absorption value of dibutyl phthalate (DBP) refers to the volume (cm2) of DBP absorbed by 100g of conductive carbon black under specified test conditions. 3 ) number, the larger the value, the higher the structure of the conductive carbon black. In order to measure the effect of polar molecular layer coating on the structure of conductive carbon black, the oil absorption value of the conductive carbon black in each embodiment and comparative example was tested by DBP; the results are shown in Table 2 and Figure 2 shown.

[0136] Table 2

[0137]

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

[0139] Table 3

[0140]

[0141] It can be seen from Examples 1 to 5 and Comparative Example 1 that the polyhydroxy polar structure regulating liquid can effectively regulate the structure degree and resistivity of the conductive carbon black, and increasing the concentration of the structure regulating liquid can effectively reduce the structure degree of the conductive carbon black, thereby preventing the conductive carbon black from having too high a structure degree and causing dispersion problems in the matrix resin.

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

[0143] In Examples 1 to 5 of the present application, a multi-hydroxy polar structure regulating liquid is used for wet granulation, and the wet granulation is combined with drying and calcination treatment. The synergistic effect of each step makes the prepared conductive carbon black have a moderate degree of structure, which can meet the dispersion requirements of the conductive filler of the semi-conductive shielding material of the high-voltage cable. The highly ordered graphitized carbon layer formed after the calcination treatment can provide a high-quality channel for electron transmission, and meet the electrical performance requirements of the semi-conductive shielding material of the high-voltage cable for the conductive carbon black.

[0144] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing conductive carbon black, characterized in that: The steps include: Mixing a structure regulating liquid precursor with water to prepare a structure regulating liquid; the structure regulating liquid precursor comprises at least one of dopamine hydrochloride, tannic acid, citric acid and tartaric acid; The structure regulating liquid is used to wet granulate powdered conductive carbon black to obtain conductive carbon black wet granules; The conductive carbon black wet particles are dried, sieved and calcined in sequence 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 adjustment liquid precursor to water is 1g:(1000mL~3000mL).

3. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that: The method further comprises the following steps: using a buffer solution to adjust the pH value of the structure regulating solution to 7.0-9.0; Optionally, the buffer comprises Tris-HCl.

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

5. The method for preparing conductive carbon black according to any one of claims 1 to 2, characterized in that: The preparation method meets at least one of the following characteristics: (1) The drying temperature is 150℃~300℃; (2) The aperture 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 treatment 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 meets at least one of the following characteristics: (1) The calcination temperature is 900°C~1200°C 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 The conductive carbon black is prepared by the preparation method of any one of claims 1 to 7.

9. A shielding material, characterized in that: Contains the conductive carbon black according to claim 8.

10. A high voltage cable, characterized in that: Comprising the shielding material as claimed in claim 9.

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