Modified conductive carbon black and preparation method thereof, semiconductive shielding material and ultrahigh-voltage cable

Abstract

The invention relates to modified conductive carbon black and a preparation method thereof, a semiconductive shielding material and an ultrahigh-voltage cable. According to the preparation method of the modified conductive carbon black, the polyethyleneimine solution is subjected to protonation treatment, so that the active dispersion liquid can keep excellent modification capability under the condition of lower polyethyleneimine concentration. Then, the conductive carbon black is soaked in the active dispersion liquid, and the modified conductive carbon black with a polyethyleneimine protection layer on the surface is obtained by means of the electrostatic adsorption effect of the polyethyleneimine groups and the surfaces of conductive carbon black particles, so that the dispersity of the modified conductive carbon black is improved. On the basis, the mass concentration of the polyethyleneimine in the active dispersion liquid is regulated and controlled, so that the coating degree of the polyethyleneimine on the conductive carbon black is moderate, and the modified conductive carbon black is ensured to have good electrical properties.

Description

Technical Field

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

[0002] The structure of a power cable includes a metallic conductor core, insulation layer, semi-conductive shielding layer, and sheath. The primary function of the semi-conductive shielding layer is to fill air gaps within the cable, creating a smooth and uniform interface. This in turn uniformizes the electric field strength across the core surface and reduces tip discharge. Therefore, the surface finish of the semi-conductive shielding layer significantly impacts the voltage rating and service life of the power cable.

[0003] However, the conductive fillers in the semi-conductive shielding layer often agglomerate, resulting in uneven structure of the shielding layer and reduced surface smoothness, which in turn causes uneven electric field distribution, increases the risk of tip discharge and partial discharge, and even destroys the insulation structure of the cable, significantly degrading the electrical performance of the semi-conductive shielding layer and reducing the cable's withstand voltage strength and operational stability. Summary of the Invention

[0004] Based on this, it is necessary to provide a modified conductive carbon black that is not easy to agglomerate in a polymer matrix and has excellent electrical properties, a preparation method thereof, a semiconductive shielding material, and an ultra-high voltage cable.

[0005] In a first aspect of the present application, a method for preparing modified conductive carbon black is provided.

[0006] A method for preparing modified conductive carbon black comprises the following steps:

[0007] Protonating the polyethyleneimine solution to obtain an active dispersion;

[0008] impregnating conductive carbon black with the active dispersion, and performing solid-liquid separation to obtain modified conductive carbon black;

[0009] The mass percentage of polyethyleneimine in the polyethyleneimine solution relative to the active dispersion is 0.01% to 0.2%.

[0010] In some embodiments, the immersion temperature is 60°C to 90°C; and / or

[0011] The immersion time is 5 h to 12 h.

[0012] In some embodiments, the protonation step comprises:

[0013] The protonated treatment solution with a pH value of 4 to 6 is mixed with the polyethyleneimine solution.

[0014] In some embodiments, the pH value of the active dispersion is 5-7.

[0015] In a second aspect of the present application, a modified conductive carbon black is provided.

[0016] A modified conductive carbon black is prepared by adopting the above-mentioned preparation method of the modified conductive carbon black.

[0017] In a third aspect of the present application, a semiconductive shielding material is provided.

[0018] A semi-conductive shielding material, comprising the following raw materials, measured by weight:

[0019] 60~65 parts of base resin

[0020] 30~38 parts of modified conductive carbon black,

[0021] 1~2 parts of processing aid; and

[0022] 0.9 to 1 part of cross-linking agent;

[0023] Wherein, the modified conductive carbon black includes the modified conductive carbon black mentioned above.

[0024] In some embodiments, the processing aid is a lubricant and an antioxidant; and / or

[0025] The cross-linking agent includes one or more of di-tert-butylperoxyisopropylbenzene, diisopropylbenzene peroxide and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0026] In a fourth aspect of the present application, a method for preparing the above-mentioned semiconductive shielding material is provided.

[0027] A method for preparing the above-mentioned semiconductive shielding material comprises the following steps:

[0028] mixing the modified conductive carbon black and the processing aid to form a first mixture;

[0029] mixing the base resin and the first mixture to form a second mixture;

[0030] The cross-linking agent and the second mixture are mixed, and heated for cross-linking to obtain the semiconductive shielding material.

[0031] In some embodiments, one or more of the following conditions are met:

[0032] (1) After forming the second mixture, the method further includes the steps of melting, extruding, granulating and drying the second mixture;

[0033] (2) The cross-linking agent is a ground cross-linking agent;

[0034] (3) The cross-linking temperature is 40°C to 80°C, and the cross-linking time is 8h to 12h.

[0035] In a fifth aspect of the present application, an ultra-high voltage cable is provided.

[0036] An ultra-high voltage cable comprises a conductor, an insulating layer and a semi-conductive shielding layer; the conductor is located on the inner side of the insulating layer, and the semi-conductive shielding layer is located on at least one surface of the insulating layer; the semi-conductive shielding layer is made of the above-mentioned semi-conductive shielding material or the semi-conductive shielding material prepared by the above-mentioned preparation method.

[0037] In the preparation method of the modified conductive carbon black of the present application, by protonating the polyethyleneimine solution, the active dispersion is able to exhibit excellent modification capabilities at relatively low polyethyleneimine concentrations. The conductive carbon black is then impregnated with the active dispersion, and by virtue of the electrostatic adsorption between the polyethyleneimine group and the surface of the conductive carbon black particles, a modified conductive carbon black having a polyethyleneimine protective layer on the surface is obtained, thereby effectively improving the dispersibility of the modified conductive carbon black. In addition, by regulating the mass concentration of the polyethyleneimine solution, it is helpful to achieve a moderate degree of polyethyleneimine coating on the conductive carbon black, thereby obtaining a modified conductive carbon black with good electrical properties.

[0038] The surface of the modified conductive carbon black in this application features a steric structure formed by interwoven polyethyleneimine molecular chains, and the surface charges repel each other, effectively reducing aggregation of the modified conductive carbon black. Furthermore, the polyethyleneimine molecular chains exhibit good compatibility with the polymer matrix, helping to improve the compatibility of the modified conductive carbon black with the polymer matrix. These two mechanisms contribute to the excellent dispersibility of the modified conductive carbon black in the matrix resin, dispersing stress and providing a more uniform conductive path, resulting in semi-conductive shielding materials with superior mechanical and electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0040] Figure 1 This is an enlarged image of the surface of the semiconductive shielding layer made of the semiconductive shielding material in Example 1 of the present application.

[0041] Figure 2This is an enlarged image of the surface of the semiconductive shielding layer made of the semiconductive shielding material in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0042] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0043] In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined. In this application, "at least one" means more than one, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] 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 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 a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0046] 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 further 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.

[0047] In this application, “above” or “below” includes the number itself. For example, “1 below” includes 1.

[0048] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0049] In the semi-conductive shielding layer of power cables, the agglomeration of conductive fillers can lead to an uneven structure and reduced surface finish, resulting in uneven electric field distribution and an increased risk of tip and partial discharge. In recent years, as cable operating voltage levels have gradually increased, these interfacial weaknesses have been further amplified by the ultra-high voltage operating environment. This not only accelerates the aging of the cable insulation and shortens the cable's service life, but can also cause insulation breakdown failures, leading to power transmission interruptions or even more serious safety incidents.

[0050] Based on this, the first aspect of the present application provides a method for preparing modified conductive carbon black that is not easy to agglomerate in a polymer matrix and has excellent electrical properties.

[0051] The preparation method of modified conductive carbon black comprises the following steps:

[0052] Protonating the polyethyleneimine solution to obtain an active dispersion;

[0053] The conductive carbon black is impregnated with an active dispersion, and the solid-liquid separation is performed to obtain a modified conductive carbon black;

[0054] The mass percentage of polyethyleneimine in the polyethyleneimine solution relative to the active dispersion is 0.01% to 0.2%.

[0055] In the preparation method of the modified conductive carbon black described above, a highly active active dispersion can be obtained by protonating the polyethyleneimine solution. Then, by impregnating the conductive carbon black with the active dispersion, the polyethyleneimine component is prompted to form an electrostatic charge protection layer on the surface of the conductive carbon black particles, and the polyethyleneimine molecular chains on the surface are interwoven to form a steric hindrance structure, thereby effectively reducing the agglomeration of the conductive carbon black. Furthermore, the polyethyleneimine molecular chains have good compatibility with the polymer matrix, which helps to improve the compatibility of the modified conductive carbon black with the polymer matrix. Under the action of the above two mechanisms, the modified conductive carbon black has excellent dispersibility in the matrix resin, which helps to provide a more developed conductive path and disperse stress, thereby providing the semi-conductive shielding material with better electrical and mechanical properties.

[0056] Alternatively, the mass percentage of polyethyleneimine in the polyethyleneimine solution relative to the active dispersion can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, or other values within the range of 0.01% to 0.2%. Maintaining the mass concentration of the polyethyleneimine component in the active dispersion within the above range can achieve better dispersibility of the modified conductive carbon black while reducing the impact of the polyethyleneimine component on the electrical properties of the conductive carbon black.

[0057] In some embodiments, the protonation step comprises:

[0058] The protonated treatment solution with a pH value of 4 to 6 is mixed with the polyethyleneimine solution.

[0059] In some embodiments, the temperature of the protonation treatment is 40° C. to 80° C. Alternatively, the temperature of the protonation treatment may be 40° C., 50° C., 60° C., 70° C., 80° C., or other temperatures within the range of 40° C. to 80° C.

[0060] In some embodiments, the protonation treatment time is 10 min to 50 min. Alternatively, the protonation treatment time can be 10 min, 20 min, 30 min, 40 min, 50 min or other time within the range of 10 min to 50 min.

[0061] In some embodiments, the protonation treatment solution used in the protonation treatment includes one or more of hydrochloric acid, nitric acid, and sulfuric acid.

[0062] In some embodiments, the pH value of the protonated treatment solution is 4 to 6. Alternatively, the pH value of the protonated treatment solution may be 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6, or other values within the range of 4 to 6. Maintaining the pH value of the protonated treatment solution within the above range can obtain an active dispersion with higher activity and reduce the self-aggregation of polyethyleneimine in polyethyleneimine.

[0063] In some embodiments, the solvent of the polyethyleneimine solution includes water.

[0064] In some embodiments, the mass concentration of polyethyleneimine in the polyethyleneimine solution is 0.05% to 5%. Alternatively, the mass concentration of polyethyleneimine can be 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or other values within the range of 0.05% to 5%.

[0065] In some embodiments, the solid-liquid separation step includes filtration and drying, wherein the drying temperature is 100° C. to 140° C. and the drying time is 8 h to 12 h.

[0066] In some embodiments, the immersion temperature is 60° C. to 90° C. Alternatively, the immersion temperature may be 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., or other temperatures within the range of 60° C. to 90° C.

[0067] In some embodiments, the impregnation time is 5 h to 12 h. Alternatively, the impregnation time can be 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h or other time within the range of 5 h to 12 h.

[0068] In some embodiments, the step of impregnating the conductive carbon black with the active dispersion comprises:

[0069] Disperse the conductive carbon black in the active dispersion and continue stirring at 60℃~90℃ for 5h~12h to allow the active dispersant to fully impregnate the conductive carbon black.

[0070] In some embodiments, the pH value of the active dispersion is 5 to 7. Alternatively, the pH value of the active dispersion can be 5, 5.5, 6, 6.5, 6.9, or any value within the range of 5 to 7. Maintaining the pH value of the active dispersion within the above range can result in a higher degree of protonation of the active dispersion, thereby exhibiting higher activity. Simultaneously, it can also reduce polymerization between polyethyleneimines, improving the modification effect of subsequent impregnation with conductive carbon black. Furthermore, it can make the impregnation process of the conductive carbon black easier to control, allowing for uniform growth of the coating layer.

[0071] In some embodiments, the conductive carbon black includes acetylene black.

[0072] In some embodiments, the polyethyleneimine is a branched polyethyleneimine with an average molecular weight of 4000 to 6000. Branched polyethyleneimine has a more complex branched structure, which makes the molecule more flexible and has a steric hindrance effect, thereby helping to improve the dispersibility and mechanical properties of the modified conductive carbon black.

[0073] In some embodiments, the mass ratio of conductive carbon black to polyethyleneimine is 100:(0.1-4).

[0074] In a second aspect of the present application, a modified conductive carbon black is provided, which is prepared using the above-mentioned method for preparing the modified conductive carbon black.

[0075] In some embodiments, the modified conductive carbon black includes conductive carbon black and a polyethyleneimine layer disposed on at least a portion of the surface of the conductive carbon black. The polyethyleneimine and the conductive carbon black are tightly adsorbed together through interactions such as hydrogen bonding. Even under ultra-high voltage (>500K), the modified conductive carbon black maintains excellent dispersion within the polymer matrix, maintaining a stable structure and resisting separation.

[0076] In a third aspect of the present application, a semiconductive shielding material is provided.

[0077] The semi-conductive shielding material is prepared from raw materials comprising, by weight, 60-65 parts base resin, 30-38 parts modified conductive carbon black, 1-2 parts processing aid, and 0.9-1 part cross-linking agent. The modified conductive carbon black includes the aforementioned modified conductive carbon black. Maintaining this raw material ratio helps produce a semi-conductive shielding material with excellent electrical and mechanical properties and surface finish.

[0078] Optionally, in the raw materials for preparing the semiconductive shielding material, the mass fraction of the matrix resin may be 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts or other fractions within the range of 60 parts to 65 parts.

[0079] Optionally, in the raw materials for preparing the semiconductive shielding material, the mass fraction of the modified conductive carbon black can be 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts or other parts within the range of 30 parts to 38 parts.

[0080] In some embodiments, the base resin includes one or more of ethylene ethyl acrylate and ethylene butyl acrylate.

[0081] Optionally, in the raw materials for preparing the semiconductive shielding material, the mass fraction of the processing aid can be 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts or other parts within the range of 1 part to 2 parts.

[0082] In some embodiments, the processing aid is a lubricant and an antioxidant. Optionally, the lubricant includes one or more of zinc stearate and paraffin. Optionally, the antioxidant includes one or more of antioxidant 1010 and antioxidant 300.

[0083] Optionally, in the raw materials for preparing the semiconductive shielding material, the mass fraction of the crosslinking agent can be 0.9 part, 0.91 part, 0.92 part, 0.93 part, 0.94 part, 0.95 part, 0.96 part, 0.97 part, 0.98 part, 0.99 part, 1 part or other parts within the range of 0.9 part to 1 part.

[0084] In some embodiments, the crosslinking agent includes one or more of di-tert-butylperoxyisopropylbenzene, diisopropylbenzene peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0085] In a fourth aspect of the present application, a method for preparing the above-mentioned semiconductive shielding material is provided.

[0086] The method for preparing the semiconductive shielding material comprises the following steps:

[0087] mixing modified conductive carbon black and a processing aid to form a first mixture;

[0088] mixing a base resin and the first mixture to form a second mixture;

[0089] The cross-linking agent and the second mixture are mixed, and heated for cross-linking to obtain a semiconductive shielding material.

[0090] In some embodiments, a mixer is used to mix the modified conductive carbon black and the processing aid. The mixer has a rotation speed of 70 rpm to 150 rpm and a stirring time of 30 min to 60 min.

[0091] In some embodiments, the first mixture is dried at a temperature of 60° C. to 100° C. for a drying time of 3 h to 8 h.

[0092] In some embodiments, after forming the second mixture, the process further comprises the steps of melting, extruding, granulating and drying the second mixture.

[0093] In some embodiments, the step of mixing the base resin and the first mixture includes:

[0094] The base resin is melted, and the melted base resin is melt-blended with the second mixture to obtain a second mixture, and the second mixture is extruded, granulated and dried; wherein the extrusion temperature is 140° C. to 170° C.

[0095] In some embodiments, the crosslinking agent is ground prior to mixing the crosslinking agent with the second mixture.

[0096] In some embodiments, the cross-linking is performed at a temperature of 40° C. to 80° C. for a time of 8 h to 12 h.

[0097] In a fifth aspect of the present application, an ultra-high voltage cable is provided.

[0098] An ultra-high voltage cable comprises a conductor, an insulation layer, and a semiconductive shielding layer; the conductor is located inside the insulation layer, and the semiconductive shielding layer is located on at least one surface of the insulation layer. The semiconductive shielding layer is made of the aforementioned semiconductive shielding material or a semiconductive shielding material prepared by the aforementioned preparation method.

[0099] The present application is further described in detail below with reference to specific embodiments.

[0100] In the following specific examples and comparative examples, the raw materials used, unless otherwise specified, are all commercially available products; the instruments used, unless otherwise specified, are all commercially available products; and the processes used, unless otherwise specified, are all routinely selected by those skilled in the art.

[0101] Example 1

[0102] This embodiment provides a modified conductive carbon black and a semi-conductive shielding material. Figure 1 , Figure 1 This is an enlarged view of the surface of the semiconductive shielding layer made of the semiconductive shielding material in this embodiment.

[0103] The preparation method of modified conductive carbon black is as follows:

[0104] 1 g of 0.01 mol / L nitric acid solution was dropwise added to 200 g of deionized water and ultrasonically dispersed for 20 minutes to obtain a protonated solution. 100 g of a 0.1 wt% aqueous polyethyleneimine solution was slowly added dropwise and ultrasonically dispersed for 30 minutes to obtain an active dispersion. 34 g of conductive carbon black was gradually dispersed in the active dispersion, stirred at 70 rpm for 30 minutes at 80°C, and immersed for 8 hours. The liquid was filtered off and the mixture was dried at 120°C for 8 hours to obtain a modified conductive carbon black. The polyethyleneimine was a branched polyethyleneimine with an average molecular weight of 5000, and the conductive carbon black was acetylene black.

[0105] The raw materials for preparing the semi-conductive shielding material are as follows:

[0106] 63.5 parts of base resin;

[0107] 34 parts of modified conductive carbon black;

[0108] 1.5 parts of processing aid; and

[0109] 1 part cross-linking agent.

[0110] The matrix resin is ethylene-butyl acrylate; the modified conductive carbon black is the modified conductive carbon black prepared in this embodiment; the crosslinking agent is di-tert-butyl peroxyisopropylbenzene; and the processing aid is composed of 1 part of zinc stearate and 0.5 parts of antioxidant 300.

[0111] The preparation method of the semi-conductive shielding material is as follows:

[0112] The modified conductive carbon black and the processing aid were mixed thoroughly in a high-speed mixer (rotation speed 100 rpm, time 45 min), and dried (dried at 80° C. for 5 h) to obtain a first mixture.

[0113] The base resin was melted in a torque rheometer (rotation speed 80 rpm, 5 min) and melt-blended with the second mixture (rotation speed 120 rpm, 15 min) to obtain a second mixture, which was then extruded (160° C.), pelletized, and dried (dried at 80° C. for 5 h).

[0114] The second mixture was mixed with a cross-linking agent and placed at 60° C. for 10 hours to obtain a semiconductive shielding material.

[0115] Example 2

[0116] The only difference between this embodiment and embodiment 1 is that when preparing the active dispersion, 100 g of a 0.075 wt % polyethyleneimine aqueous solution is slowly added dropwise.

[0117] Example 3

[0118] This embodiment provides a modified conductive carbon black and a semi-conductive shielding material.

[0119] This embodiment is substantially the same as embodiment 1, except that: when preparing the active dispersion, 100 g of a 0.2 wt % aqueous solution of polyethyleneimine is slowly added dropwise.

[0120] Comparative Example 1

[0121] This comparative example provides a semi-conductive shielding material. Figure 2 , Figure 2 It is an enlarged view of the surface of the semiconductive shielding layer made of the semiconductive shielding material in this comparative example.

[0122] This comparative example is basically the same as Example 1, except that: modified conductive carbon black is not used in the raw materials for preparing the semi-conductive shielding material, and the conductive carbon black and processing aid are fully mixed in a high-speed mixer.

[0123] Comparative Example 2

[0124] This comparative example provides a modified conductive carbon black and a semiconductive shielding material.

[0125] This comparative example is basically the same as Example 1, except that: when preparing the active dispersion, 100 g of a 1 wt % polyethyleneimine aqueous solution was slowly added dropwise.

[0126] Comparative Example 3

[0127] This comparative example provides a modified conductive carbon black and a semiconductive shielding material.

[0128] This comparative example is basically the same as Example 1, except that: when preparing the active dispersion, no nitric acid is added and no protonation treatment is performed.

[0129] Test Case

[0130] The semiconductive shielding materials obtained in the examples and comparative examples were placed in a flat vulcanizer for hot pressing for 15 minutes and cold pressing for 6 minutes to produce a cable semiconductive shielding layer. The electrical and mechanical properties of the cable semiconductive shielding layer were measured. A strip-shaped semiconductive shielding layer was produced by a single-screw extruder. The surface smoothness of the strip material was observed using an optical microscope. Five different test areas (1 cm 2 ), and counted the number of defects (protrusions or depressions) with a two-dimensional size exceeding 50µm. The results of various performance tests are shown in Table 1.

[0131] Table 1

[0132]

[0133] Comparison of the examples with the comparative examples demonstrates that the semiconductive shielding materials incorporating the modified conductive carbon black of this application exhibit superior mechanical and electrical properties, as well as surface finish. This demonstrates that the modified conductive carbon black prepared using the method for preparing the modified conductive carbon black of this application can achieve excellent dispersion within the polymer matrix and form a more developed conductive pathway.

[0134] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0135] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present invention should be based on the appended claims, and the specification may be used to interpret the content of the claims.

Claims

1. A method for preparing modified conductive carbon black, characterized in that: The following steps are involved: Protonating the polyethyleneimine solution to obtain an active dispersion; impregnating conductive carbon black with the active dispersion, and performing solid-liquid separation to obtain modified conductive carbon black; The mass percentage of polyethyleneimine in the polyethyleneimine solution relative to the active dispersion is 0.01% to 0.2%.

2. The method for preparing modified conductive carbon black according to claim 1, wherein The immersion temperature is 60°C to 90°C; and / or The immersion time is 5 h to 12 h.

3. The method for preparing modified conductive carbon black according to claim 1, wherein The protonation step comprises: The protonated treatment solution with a pH value of 4 to 6 is mixed with the polyethyleneimine solution.

4. The method for preparing the modified conductive carbon black according to any one of claims 1 to 3, wherein: The pH value of the active dispersion is 5-7.

5. A modified conductive carbon black, characterized in that: The conductive carbon black is prepared by the modification method of any one of claims 1 to 4.

6. A semi-conductive shielding material, characterized in that: The semi-conductive shielding material comprises the following raw materials in parts by mass: 60~65 parts of base resin 30~40 parts of modified conductive carbon black, 1~2 parts of processing aid; and 0.9 to 1 part of cross-linking agent; Wherein, the modified conductive carbon black includes the modified conductive carbon black according to claim 5.

7. The semiconductive shielding material according to claim 6, characterized in that The processing aids include one or more of lubricants and antioxidants; and / or The cross-linking agent includes one or more of di-tert-butylperoxyisopropylbenzene, diisopropylbenzene peroxide and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; and / or The base resin includes one or more of ethylene-ethyl acrylate and ethylene-butyl acrylate.

8. A method for preparing the semiconductive shielding material according to claim 6 or 7, characterized in that: The following steps are involved: mixing the modified conductive carbon black and the processing aid to form a first mixture; mixing the base resin and the first mixture to form a second mixture; The cross-linking agent and the second mixture are mixed, and heated for cross-linking to obtain the semiconductive shielding material.

9. The method for preparing a semiconductive shielding material according to claim 8, characterized in that: The preparation method of the semiconductive shielding material meets one or more of the following conditions: (1) After forming the second mixture, the method further includes the steps of melting, extruding, granulating and drying the second mixture; (2) The cross-linking agent is a ground cross-linking agent; (3) The cross-linking temperature is 40°C to 80°C, and the cross-linking time is 8h to 12h.

10. An ultra-high voltage cable, characterized in that: It comprises a conductor, an insulating layer and a semiconductive shielding layer; the conductor is located on the inner side of the insulating layer, and the semiconductive shielding layer is located on at least one surface of the insulating layer; the semiconductive shielding layer is made of the semiconductive shielding material according to any one of claims 6 to 7 or the semiconductive shielding material prepared by the preparation method according to any one of claims 8 to 9.

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