Cable shielding layer material, preparation method thereof and high-voltage direct-current cable

Abstract

The invention relates to the technical field of cable materials, in particular to a cable shielding layer material, a preparation method thereof and a high-voltage direct-current cable. The cable shielding layer material comprises the following components in parts by weight: 100 parts of matrix resin, 5-20 parts of a conductive material, 0.1-2 parts of a carbon black modifier, 0.1-2 parts of a space charge inhibitor and 0.1-1 part of a processing aid, the matrix resin comprises polypropylene and an elastomer in a weight ratio of (3-7): (3-7); the conductive material comprises carbon black. The cable shielding layer material has good electrical performance, is resistant to high-temperature deformation, has the non-crosslinking characteristic and is convenient to recycle.

Description

Technical Field

[0001] The present application relates to the technical field of cable materials, and in particular to a cable shielding layer material and a preparation method thereof, and a high-voltage direct current cable. Background Art

[0002] Cable shielding material is an important material used in cable manufacturing. It is usually located between the conductor and the insulation layer (inner shielding layer), and between the insulation layer and the sheath (outer shielding layer). Its main function is to prevent external electromagnetic interference, improve the transmission efficiency of the cable, and play a role in uniform electric field distribution, suppressing excessive local field strength, and preventing local discharge in the cable, thereby ensuring the quality and stability of signal transmission.

[0003] Cable shielding materials can be divided into metal materials and non-metal materials. Metal materials can be aluminum, copper, silver, silver-plated copper, alloys, etc. These materials are widely used in cable shielding due to their high electrical conductivity and high magnetic permeability. Non-metallic materials are a new type of cable shielding material that has emerged in recent years. They are usually composed of polymer materials and their shielding performance is improved by adding conductive fillers.

[0004] In high-voltage DC cables, the selection of shielding layer materials is very critical. The materials used for high-voltage DC cables need to have excellent electrical properties to meet the requirements of high-voltage DC insulation. At the same time, they also need to be resistant to high-temperature deformation and non-cross-linking for easy recycling. The current cable shielding layer materials need to be further improved in terms of high-temperature deformation resistance and electrical properties.

[0005] Based on this, the technical content of this application is specially proposed. Summary of the invention

[0006] Based on this, one or more embodiments of the present application provide a cable shielding layer material, a preparation method thereof, and a high-voltage DC cable. The cable shielding layer material of the present application has high-temperature deformation resistance and non-cross-linking properties, and has excellent electrical properties, and can be used to prepare the cable shielding layer of the high-voltage DC cable.

[0007] The technical solution of this application includes the following contents:

[0008] A cable shielding layer material, comprising, by weight: 100 parts of a base resin, 5 to 20 parts of a conductive material, 0.1 to 2 parts of a carbon black modifier, 0.1 to 2 parts of a space charge inhibitor, and 0.1 to 1 part of a processing aid;

[0009] The matrix resin comprises polypropylene and elastomer in a weight ratio of (3-7): (3-7);

[0010] The conductive material includes carbon black.

[0011] In some embodiments, the polypropylene includes copolymerized polypropylene, wherein the copolymerized polypropylene includes 5% to 20% by weight of ethylene and has a molecular weight of 300,000 to 500,000.

[0012] In some embodiments, the conductive material further comprises one or more of carbon nanotubes and functionalized graphene oxide; and / or

[0013] The conductive material comprises 80% to 100% by weight of carbon black; and / or

[0014] The particle size of the carbon black is 5nm~80nm.

[0015] In some embodiments, the elastomer includes one or more of polyolefin elastomer, EPDM rubber, hydrogenated styrene-butadiene block copolymer and ethylene-vinyl acetate copolymer.

[0016] In some embodiments, the carbon black modifier includes one or more of the long-chain silane coupling agents hexadecyltrimethoxysilane, dodecylalkoxysilane, and n-octyltriethoxysilane.

[0017] In some embodiments, the space charge inhibitor includes an organic inhibitor and an inorganic inhibitor;

[0018] The organic inhibitor includes one or more of unsaturated anhydride compounds, hindered phenol compounds and aromatic ketone compounds;

[0019] The inorganic inhibitor includes one or more of zeolite, mesoporous material and nano oxide.

[0020] In some embodiments, the processing aid includes one or more of an antioxidant and a copper inhibitor;

[0021] The antioxidant includes one or more of antioxidant 300, antioxidant 1010 and antioxidant 168;

[0022] The copper inhibitor includes one or more of Irganox MD1024 and oxalyl diamide.

[0023] A method for preparing the cable shielding layer material as described above comprises the following steps:

[0024] Stirring the carbon black modifier and the carbon black in the conductive material in a solution to obtain modified carbon black;

[0025] The remaining conductive materials, the modified carbon black, the elastomer and the space charge inhibitor are mixed and kneaded to obtain a shielding material masterbatch;

[0026] The shielding material masterbatch, the polypropylene and the processing aid are mixed and granulated to obtain the high-voltage direct current cable shielding material.

[0027] In some embodiments, the conditions for internal mixing include: a temperature of 160° C. to 190° C., a rotation speed of 30 rpm to 60 rpm; and / or a time of 10 min to 30 min.

[0028] A high-voltage direct current cable, the cable shielding layer of which comprises the cable shielding layer material mentioned above.

[0029] The cable shielding material of the present application includes an appropriate amount of conductive material (the conductive material includes an appropriate amount of carbon black), a carbon black modifier, an elastomer, polypropylene, a space charge inhibitor and a processing aid. The conductive particles in the cable shielding layer material can be well dispersed, so that the cable shielding layer material has high conductivity and conductive network stability, has good electrical properties, and can reduce the charge injection phenomenon of the shielding layer into the insulating layer in a high-voltage DC electric field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] Figure 1 TEM photos of carbon black and modified carbon black according to an embodiment of the present application. Figure 1 a) is a TEM image of carbon black, b) is a TEM image of A172-modified carbon black, and c) is a TEM image of hexadecyltrimethoxysilane-modified carbon black. The scale bar is 200 nm.

[0032] Figure 2 This is a TEM photo of carbon black and modified carbon black dispersed in a matrix resin according to an embodiment of the present application. Figure 2 (a) is a dispersion photo of 15 wt% carbon black and PP. Figure 2 (b) is a dispersion photo of 15 wt% carbon black and PP and POE. Figure 2 (c) is a dispersion photograph of 15wt% hexadecyltrimethoxysilane-modified carbon black and PP, POE; the scale bar is 5μm. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with the embodiments and examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. In addition, it should be understood that after reading the content taught in the present application, those skilled in the art may make various changes or modifications to the present application, and these equivalent forms also fall within the protection scope of the claims attached to the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] the term

[0036] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0037] The term "and / or" used in this article includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the arbitrary and all combinations include any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, the technical solution that is all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four of A, B, C, and D (that is, the technical solution that is all connected by "logical AND").

[0038] Herein, "preferred" and the like are merely used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute limitations on the scope of protection of the present application.

[0039] In the present application, "further" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0040] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0041] In this application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical range, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to integers within the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges included therein.

[0042] In a first aspect of the present application, a cable shielding layer material is provided, which has excellent electrical properties and high temperature resistance, and also has non-cross-linking properties and is easy to recycle.

[0043] The cable shielding layer material of the embodiment of the present application includes appropriate amounts of polypropylene, conductive materials (including carbon black) and elastomers, and includes a carbon black modifier that can perform surface modification on carbon black to improve the structural properties of carbon black and the dispersibility of carbon black in the polypropylene system. The cable shielding layer material also includes appropriate amounts of space charge inhibitors and processing aids that can reduce charge release in the conductive path.

[0044] The cable shielding layer material of the embodiment of the present application comprises, by weight: 100 parts of base resin, 5 to 20 parts of conductive material, 0.1 to 2 parts of carbon black modifier, 0.1 to 2 parts of space charge inhibitor, and 0.1 to 1 part of processing aid;

[0045] The matrix resin comprises polypropylene and elastomer in a weight ratio of (3-7): (3-7);

[0046] The conductive material includes carbon black.

[0047] The cable shielding layer material of the embodiment of the present application includes an appropriate amount of conductive material (the conductive material includes an appropriate amount of carbon black), a carbon black modifier, an elastomer, polypropylene, a space charge inhibitor and a processing aid. The conductive particles in the cable shielding layer material can be better dispersed, so that the cable shielding layer material has high conductivity and conductive network stability, and the charge injection from the shield to the insulation should be reduced in a high-voltage DC electric field.

[0048] The structure of carbon black is defined as the aggregation or adhesion state of carbon black particles, which is usually quantified by structure. Carbon black with high structure has small particle size, large number of particles, complex chain system, high branching degree, large specific surface area and large void volume, which is more conducive to dispersion in building a complex carbon black network.

[0049] In some embodiments, the particle size of the carbon black is 5 nm to 80 nm. In the present application, unless otherwise specified, the size, particle size, and diameter generally refer to the average value.

[0050] Alternatively, the particle size of carbon black can be selected from 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.

[0051] There are various oxygen-containing functional groups such as carboxyl on the surface of carbon black. These active sites provide the possibility for the modification of carbon black particles. By grafting and modifying carbon black, the intermolecular forces of carbon black can be reduced and the structural degree of carbon black can be improved. At the same time, the matrix resin is a non-polar / weakly polar material. A long-chain silane coupling agent with ≥10 carbon atoms in the alkyl group is selected as a carbon black modifier. The lipophilicity of its chain end can improve the compatibility and dispersibility of carbon black in the matrix resin, which is more conducive to building a conductive network and improving the resistance stability of the system, thereby improving the electrical and mechanical properties of the system.

[0052] In some embodiments, the carbon black modifier includes one or more of the long-chain silane coupling agents hexadecyltrimethoxysilane, dodecylalkoxysilane and n-octyltriethoxysilane, which can better improve the compatibility and dispersibility of carbon black in the matrix resin, and better be compatible with other components in the cable shielding layer material and improve the conductivity of the system and the stability of the conductive network.

[0053] In some embodiments, the conductive material includes 80% to 100% by weight of the carbon black. Optionally, the weight percentage of the carbon black in the conductive material may be 80%, 85%, 90%, 95%, 99%, 100%, etc.

[0054] In some embodiments, the conductive material further includes one or more of carbon nanotubes and functionalized graphene oxide.

[0055] In the cable shielding layer material of the embodiment of the present application, the base resin includes polypropylene and elastomer, and the weight ratio of polypropylene to elastomer is (3~7):(3~7), for example 7:3, 6:4, 5:5, 4:6, 3:7, etc.

[0056] In some embodiments, the elastomer includes one or more of polyolefin elastomer, EPDM rubber, hydrogenated styrene-butadiene block copolymer and ethylene-vinyl acetate copolymer.

[0057] In some embodiments, the polypropylene includes copolymerized polypropylene, wherein the copolymerized polypropylene includes 5% to 20% by weight of ethylene and has a molecular weight of 300000 to 500000. In the present application, unless otherwise specified, the molecular weight is an average molecular weight.

[0058] Optionally, the molecular weight of the copolymerized polypropylene can be selected from 312400, 380500, 404000, 472900, etc.

[0059] In some embodiments, the mass ratio of the matrix resin to the conductive material is 100:(5~20), and the mass ratio of the matrix resin to the conductive material can be but is not limited to 100:5, 100:7.5, 100:10, 100:12.5, 100:15, 100:17.5, 100:20 or a range consisting of any two of these values.

[0060] In some embodiments, the mass ratio of the base resin to the carbon black modifier is 100:(0.1~2), and the mass ratio of the base resin to the carbon black modifier can be but is not limited to 100:0.1, 100:0.3, 100:0.5, 100:0.8, 100:1, 100:1.2, 100:1.5, 100:1.8, 100:2 or a range consisting of any two of these values.

[0061] In the cable shielding layer material of the embodiment of the present application, the space charge inhibitor includes an organic inhibitor and an inorganic inhibitor;

[0062] The organic inhibitor includes one or more of unsaturated anhydride compounds, hindered phenol compounds and aromatic ketone compounds;

[0063] The inorganic inhibitor includes one or more of zeolite, mesoporous material and nano oxide.

[0064] In some embodiments, the mass ratio of the matrix resin to the space charge inhibitor is 100:(0.1~2), and the mass ratio of the matrix resin to the space charge inhibitor can be but is not limited to 100:0.1, 100:0.3, 100:0.5, 100:0.8, 100:1, 100:1.2, 100:1.5, 100:1.8, 100:2 or a range consisting of any two of these values.

[0065] In some embodiments, the space charge inhibitor is selected from an organic inhibitor. By adding an organic inhibitor to the matrix resin, the charge adsorption effect of the benzene ring is utilized, and the branch chain with the target functional group is grafted onto the polymer main chain to preferentially receive the electron impact or introduce charge traps, thereby reducing the shielding of the charge injection into the polypropylene insulation. By adding an inorganic space charge inhibitor to the matrix resin, the localized state introduced by the doped particles in the matrix or the surface structure and surface effect of the doped particles are utilized to change the depth, density and distribution of the trap energy level in the matrix, change the crystallization behavior of the polymer, and ultimately achieve the purpose of suppressing space charge.

[0066] In the cable shielding layer material of the embodiment of the present application, the processing aid includes one or more of an antioxidant and a copper inhibitor;

[0067] The antioxidant includes one or more of antioxidant 300, antioxidant 1010 and antioxidant 168;

[0068] The copper inhibitor includes one or more of Irganox MD1024 and oxalyl diamide.

[0069] In some embodiments, the mass ratio of the base resin to the processing aid is 100:(0.1~1), and the mass ratio of the base resin to the processing aid can be but is not limited to 100:0.1, 100:0.3, 100:0.5, 100:0.8, 100:1 or a range consisting of any two of these values.

[0070] One aspect of the present application also provides a method for preparing a cable shielding layer material, comprising the following steps:

[0071] The carbon black modifier and the carbon black in the conductive material are stirred in a solution to prepare modified carbon black;

[0072] The remaining conductive materials, modified carbon black, elastomer and space charge inhibitor are mixed and then kneaded to prepare a shielding material masterbatch;

[0073] The shielding material masterbatch, polypropylene and the processing aid are mixed and granulated to obtain the cable shielding layer material.

[0074] In the preparation method of the cable shielding layer material of the embodiment of the present application, the superconductive carbon black is modified by a solution reaction method, and long-chain organic groups are grafted to form more physical entanglement points with the carbon black, polypropylene and toughening resin, thereby enhancing the interface strength between the conductive particles and the resin.

[0075] In some embodiments, the conditions for internal mixing include: a temperature of 160° C. to 190° C., a rotation speed of 30 rpm to 60 rpm; and / or a time of 10 min to 30 min.

[0076] One aspect of the present application also provides a high-voltage DC cable, the composition of whose cable shielding layer includes the cable shielding layer material mentioned above, so that the injection of charges in the shielding layer of the high-voltage DC cable into the insulating layer can be well suppressed, and the shielding layer material also has excellent conductivity and stability of the conductive network, thereby meeting the requirements of high-voltage DC insulation.

[0077] The following are some specific embodiments.

[0078] For experimental parameters not specified in the following specific embodiments, reference is made to the instructions given in the present application document, and reference may also be made to experimental manuals in the art or other experimental methods known in the art, or to experimental conditions recommended by manufacturers.

[0079] The raw materials and reagents involved in the following specific examples can be obtained from commercial sources, or can be prepared by those skilled in the art according to known methods.

[0080] raw material:

[0081] Polypropylene: purchased from Yanshan Petrochemical / Shanghai Secco, brand K8303 / K8003,

[0082] Superconductive carbon black: purchased from Imerys, Switzerland, brand ENSACO 250G,

[0083] Elastomer: purchased from Borealis, brand 8210 / 8230,

[0084] Carbon black modifier: hexadecyl trimethoxysilane / vinyl tri(2-methoxyethoxy)silane, purchased from Aladdin / Hynes,

[0085] Space charge inhibitor: zeolite, purchased from Biter Pharmaceutical Technology, particle size ≤ 10.0 um,

[0086] Processing aids: antioxidant 300 / 1010 / 168, Irganox MD1024 / oxalyl diamide.

[0087] 1. Preparation of cable shielding materials

[0088] Table 1

[0089]

[0090] After preparing the raw materials of each embodiment and comparative example according to Table 1, a high voltage DC cable shielding material is prepared, and the preparation steps are as follows:

[0091] The first step: the superconductive carbon black is modified by the solution modification method. A certain amount of superconductive carbon black is placed in anhydrous ethanol and ultrasonically dispersed for 10 to 15 minutes. After obtaining a uniform dispersion of carbon black, a carbon black modifier is added and ultrasonicated for 10 to 15 minutes. After mixing evenly, the mixture is reacted at a certain temperature of 30 to 70°C in a magnetic stirrer. After the solvent is volatilized, modified carbon black particles are obtained.

[0092] Step 2: Put the modified carbon black particles, elastomer and space charge inhibitor obtained in the first step into an internal mixer by weight, and mix them for 10 min to 30 min at 160°C to 190°C and 30 rpm to 60 rpm. Then transfer the mixture to a single screw extruder for extrusion granulation to obtain a shielding material masterbatch.

[0093] In the third step, the masterbatch pellets, polypropylene pellets and processing aids obtained in the second step are mixed by weight, and extruded and granulated at 190° C. in a reciprocating machine to obtain a shielding material for a high-voltage direct current polypropylene cable.

[0094] 2. Morphology Characterization

[0095] The high-voltage direct current polypropylene cable shielding material of Example 1 was observed under a transmission electron microscope. Figure 1 Transmission electron microscope images of carbon black and modified carbon black at 200nm scale. Figure 1 (a) is a TEM photo of carbon black that has not been treated with a coupling agent. It can be seen that the carbon black aggregates are in the shape of grape chains. Figure 1 (b) is a TEM image of A172-modified carbon black. There is almost no aggregation between carbon black particles. Figure 1 (c) is a TEM photo of carbon black modified with hexadecyltrimethoxysilane. The particles have low stacking properties, a high overall morphology complexity, an improved structural degree, and a more obvious grape chain structure, which is more conducive to the carbon black connecting with each other to form channels, thereby obtaining better conductive properties.

[0096] Carbon black was directly dispersed in the resin matrix and observed under a transmission electron microscope. Figure 2 This is a scanning electron microscope image of carbon black dispersed in the resin matrix. Figure 2 (a) is a SEM photo of the dispersion of 15 wt% carbon black and polypropylene. Figure 2 (b) is a SEM photo of the dispersion of 15 wt% carbon black, polypropylene and POE. Figure 2 (c) is a SEM photo of the dispersion of 15 wt% hexadecyltrimethoxysilane-modified carbon black and polypropylene and POE. It can be found that a large number of densely and evenly distributed particles can be observed in the SEM photo, indicating that the carbon black is distributed in the form of point-like or spherical aggregates; at the same carbon black content, after POE is added to the system, the carbon black is selectively distributed in POE, the carbon black concentration is high, and the dispersion distribution in POE is more conducive to the establishment of a conductive network; after the carbon black is modified with hexadecyltrimethoxysilane, tiny chains can be observed on the brittle fracture surface, indicating that the grafting modification is successful, and the carbon black is more evenly dispersed, making the conductive network more stable.

[0097] 3. Performance Test

[0098] The performance of the high-voltage DC cable shielding materials of the above-mentioned embodiments and comparative examples was tested, including mechanical properties and electrical properties. 0 ~10 7The Ω·cm sample was tested using a BD400H semi-conductive rubber resistivity tester. The voltage range was set to 200mV, the current source was set to 1mA, and the sample size was 110×50×1mm:

[0099] The test results are shown in Table 2

[0100]

[0101] It can be seen from Table 1 that the volume resistivity of the high-voltage DC cable shielding material in the embodiment of the present application is 82.0~94.3 at room temperature; the volume resistivity at 90°C is 138.3~149.5; it can be seen that the high-voltage DC cable shielding material in the embodiment of the present application has excellent comprehensive performance.

[0102] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0103] The technical features of the above-mentioned implementation modes and examples can be combined in any appropriate manner. To make the description concise, not all possible combinations of the technical features in the above-mentioned implementation modes and examples 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.

[0104] The above-described embodiments only express several implementation methods of the present application, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for those of ordinary skill in the art, without departing from the concept of the present application, several variations and improvements can also be made, which all belong to the protection scope of the present application. In addition, it should be understood that after reading the above-mentioned teaching content of the present application, those skilled in the art can make various changes or modifications to the present application, and the equivalent forms obtained also fall within the protection scope of the present application. It should also be understood that the technical solutions obtained by those skilled in the art on the basis of the technical solutions provided in the present application through logical analysis, reasoning or limited experiments are all within the protection scope of the claims attached to the present application. Therefore, the protection scope of the patent of the present application shall be based on the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A cable shielding layer material, characterized in that: The composition comprises, by weight: 100 parts of base resin, 5 to 20 parts of conductive material, 0.1 to 2 parts of carbon black modifier, 0.1 to 2 parts of space charge inhibitor, and 0.1 to 1 part of processing aid; The matrix resin comprises polypropylene and elastomer in a weight ratio of (3-7): (3-7); The conductive material includes carbon black.

2. The cable shielding layer material according to claim 1, characterized in that: The polypropylene includes copolymerized polypropylene, wherein the copolymerized polypropylene includes propylene monomer and 5% to 20% by weight of ethylene; and / or, The molecular weight of the copolymerized polypropylene is 300,000-500,000.

3. The cable shielding layer material according to claim 1, characterized in that: The conductive material further comprises one or more of carbon nanotubes and functionalized graphene oxide; and / or The conductive material comprises 80% to 100% by weight of the carbon black; and / or The particle size of the carbon black is 5nm~80nm.

4. The cable shielding layer material according to claim 1, characterized in that: The elastomer includes one or more of polyolefin elastomer, ethylene propylene diene monomer rubber, hydrogenated styrene-butadiene block copolymer and ethylene-vinyl acetate copolymer.

5. The cable shielding layer material according to claim 1, characterized in that: The carbon black modifier includes one or more of long-chain silane coupling agents such as hexadecyltrimethoxysilane, dodecylalkoxysilane and n-octyltriethoxysilane.

6. The cable shielding layer material according to claim 1, characterized in that: The space charge inhibitor includes organic inhibitor and inorganic inhibitor; The organic inhibitor includes one or more of unsaturated anhydride compounds, hindered phenol compounds and aromatic ketone compounds; The inorganic inhibitor includes one or more of zeolite, mesoporous material and nano oxide.

7. The cable shielding layer material according to claim 1, characterized in that: The processing aid includes one or more of an antioxidant and a copper inhibitor; The antioxidant includes one or more of antioxidant 300, antioxidant 1010 and antioxidant 168; The copper inhibitor includes one or more of Irganox MD1024 and oxalyl diamide.

8. A method for preparing the cable shielding layer material according to any one of claims 1 to 7, characterized in that: The steps include: Stirring the carbon black modifier and the carbon black in the conductive material in a solution to obtain modified carbon black; The remaining conductive materials, the modified carbon black, the elastomer and the space charge inhibitor are mixed and then kneaded to obtain a shielding material masterbatch; The shielding material masterbatch, the polypropylene and the processing aid are mixed and granulated to obtain the cable shielding layer material.

9. The method for preparing a cable shielding layer material according to claim 8, characterized in that: The conditions for internal mixing include: a temperature of 160° C. to 190° C., a rotation speed of 30 rpm to 60 rpm; and / or a time of 10 min to 30 min.

10. A high voltage DC cable, characterized in that: The cable shielding layer comprises the cable shielding layer material described in any one of claims 1 to 7.

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