Modified conductive carbon black and preparation method thereof, shielding material and preparation method thereof, and cable

Abstract

The invention provides modified conductive carbon black and a preparation method thereof, a shielding material and a preparation method thereof, and a cable. The conductive carbon black comprises silane coupling agent modified conductive carbon black and silver nanoparticles grown on the surface of the conductive carbon black in situ; based on the total volume of the modified conductive carbon black, the volume ratio of the silver nanoparticles is 0.5%-3%. The silver nanoparticles with high electron mobility are attached to the surface of the conductive carbon black according to a specific volume ratio, the silver nanoparticles can form an interface transition layer on the surface of the conductive carbon black particles, additional steric hindrance is provided, the aggregation tendency caused by Van der Waals' force or electrostatic interaction is reduced, and the conductivity of the conductive carbon black is improved. The dispersion state of the conductive carbon black in a polymer matrix can be kept; meanwhile, the interface transition layer has a bridging effect among different conductive carbon black aggregates, so that the transmission of charge carriers is effectively promoted, and the contact resistance of the conductive carbon black can be reduced.

Description

Technical Field

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

[0002] Applying semiconductive composite materials to the shielding layer of high-voltage cables is crucial to optimizing the electric field distribution in high-voltage cables and improving the operating safety of high-voltage cables.

[0003] Conductive carbon black is widely used as a conductive filler in semi-conductive shielding materials of high-voltage cables due to its stable conductivity and cost-effectiveness; however, the aggregated structure of conductive carbon black causes it to easily agglomerate in the polymer matrix, increasing the contact resistance, affecting the performance of the shielding material, and thus reducing the electrical performance of the cable.

[0004] Currently, researchers are trying to use multifunctional wetting dispersants to improve the dispersibility and interfacial compatibility of conductive carbon black, but the insulating properties of the dispersants reduce the conductivity of conductive carbon black, limiting the improvement of the conductivity of shielding materials. In addition, researchers have also introduced graphene with higher carrier mobility as a second conductive filler to reduce the amount of conductive carbon black; however, the strong intermolecular forces of graphene make it easy to stack and entangle, resulting in an uneven conductive network and reducing the dispersibility of the shielding material.

[0005] Therefore, traditional shielding materials still need to be improved. Summary of the invention

[0006] Based on this, one or more embodiments of the present application provide a modified conductive carbon black having low contact resistance, excellent conductivity and dispersibility and a preparation method thereof, a shielding material and a preparation method thereof, and a cable.

[0007] According to a first aspect of an embodiment of the present application, a modified conductive carbon black is provided, comprising conductive carbon black modified by a silane coupling agent, and silver nanoparticles in situ grown on the surface of the conductive carbon black;

[0008] Based on the total volume of the modified conductive carbon black, the volume proportion of the silver nanoparticles is 0.5% to 3%.

[0009] In one embodiment, the silane coupling agent contains one or more of a mercapto group, an amine group, a hydroxyl group, a vinyl group, a trifluoropropyl group and a chlorine atom;

[0010] Optionally, the silane coupling agent includes one or more of (3-mercaptopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

[0011] According to a second aspect of the embodiment of the present application, there is provided a method for preparing the above-mentioned modified conductive carbon black, comprising the following steps:

[0012] Using a silane coupling agent to modify the conductive carbon black to obtain modified conductive carbon black powder;

[0013] Silver nanoparticles are in-situ grown on the surface of the modified conductive carbon black powder to obtain the modified conductive carbon black.

[0014] In one embodiment, the preparation method comprises the following steps:

[0015] Mixing the conductive carbon black with the first solvent to obtain a conductive carbon black suspension;

[0016] Mixing a silane coupling agent with a second solvent to obtain a silane coupling agent solution;

[0017] The conductive carbon black suspension is mixed with a silane coupling agent solution, and stirred at 60° C. to 90° C. to obtain a modified mixed solution;

[0018] Centrifuging, drying and grinding the modified mixed solution in sequence to obtain the modified conductive carbon black powder;

[0019] Mixing the modified conductive carbon black powder with a reducing agent solvent to obtain a suspension;

[0020] The suspension is mixed with a silver nitrate solution and stirred to react, so as to in-situ grow silver nanoparticles on the surface of the modified conductive carbon black powder.

[0021] In one embodiment, the preparation method satisfies at least one of the following characteristics:

[0022] (1) The first solvent is selected from anhydrous ethanol;

[0023] (2) The mass ratio of the conductive carbon black to the first solvent is 1:(10-20);

[0024] (3) the second solvent is selected from anhydrous ethanol;

[0025] (4) the pH value of the second solvent is 3.5 to 4.5;

[0026] (5) The mass ratio of the silane coupling agent to the second solvent is 1:(5-10);

[0027] (6) The mass ratio of the silane coupling agent solution to the conductive carbon black suspension is 1:(19-99);

[0028] (7) the reducing agent solution comprises one or more of anhydrous ethanol, glucose solution, trisodium citrate solution, formaldehyde solution, sodium hypophosphite solution, sodium dithionite solution and tannin solution;

[0029] (8) The concentration of the solute in the reducing agent solution is 4wt%~6wt%;

[0030] (9) The pH value of the reducing agent solution is 10.0 to 12.0;

[0031] (10) The concentration of the solute in the silver nitrate solution is 0.05 mol / L to 0.2 mol / L;

[0032] (11) The mass ratio of the modified conductive carbon black powder to the reducing agent solvent is 1: (20-50);

[0033] (12) The stirring reaction temperature is 25°C~35°C and the time is 2.5h~3.5h.

[0034] According to a third aspect of the embodiment of the present application, a shielding material is provided, comprising the following components, by mass: 29 to 31 parts of modified conductive carbon black, 63 to 65 parts of ethylene-butyl acrylate copolymer, 1.4 to 1.6 parts of a cross-linking agent, and 2.4 to 2.6 parts of an auxiliary agent;

[0035] Wherein, the modified conductive carbon black includes the modified conductive carbon black mentioned above or the modified conductive carbon black prepared by the preparation method of the modified conductive carbon black mentioned above;

[0036] The auxiliary agent includes one or more of a lubricant and an antioxidant.

[0037] In one embodiment, the shielding material satisfies at least one of the following characteristics:

[0038] (1) The cross-linking agent includes dicumyl peroxide;

[0039] (2) The mass ratio of the lubricant to the antioxidant is (3.9-4.1): 1;

[0040] (3) The lubricant includes one or more of zinc stearate and pentaerythritol;

[0041] (4) The antioxidant includes one or more of a hindered phenol antioxidant and a phosphite antioxidant.

[0042] According to a fourth aspect of an embodiment of the present application, a method for preparing a shielding material is provided, comprising the following steps:

[0043] Providing raw materials according to the components of the above-mentioned shielding material, mixing the modified conductive carbon black, lubricant and antioxidant at 60° C. to 70° C. to obtain a premix;

[0044] mixing the premix with ethylene-butyl acrylate copolymer to obtain a mixture;

[0045] The mixture is subjected to sequential internal mixing, melt extrusion and granulation to obtain granular material;

[0046] The granular material is mixed with a cross-linking agent and dried to obtain the shielding material.

[0047] In one embodiment, the method for preparing the shielding material satisfies at least one of the following characteristics:

[0048] (1) The mixing temperature is 150℃~170℃ and the speed is 80r / min~120r / min;

[0049] (2) The temperature of melt extrusion is 130℃~160℃.

[0050] According to a fifth aspect of an embodiment of the present application, there is provided a cable, comprising the above-mentioned shielding material or the shielding material produced by the above-mentioned method for producing the shielding material.

[0051] Compared with the traditional technology, this application has the following beneficial effects:

[0052] In the present application, silver nanoparticles with high electron mobility are attached to the surface of conductive carbon black in a specific volume ratio. The silver nanoparticles can form an interfacial transition layer on the surface of the conductive carbon black particles, providing additional steric hindrance, thereby reducing the aggregation tendency caused by van der Waals forces or electrostatic effects, and helping to maintain the dispersion state of the conductive carbon black in the polymer matrix; at the same time, the interfacial transition layer has a bridging effect between different conductive carbon black aggregates, effectively promoting the transmission of charge carriers, thereby reducing the contact resistance of the conductive carbon black. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] 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.

[0054] Figure 1 This is a schematic structural diagram of modified conductive carbon black in one embodiment of the present application;

[0055] Figure 2 This is a process flow chart for preparing modified conductive carbon black in one embodiment of the present application;

[0056] Figure 3 This is a process flow chart for preparing shielding material in one embodiment of the present application.

[0057] Explanation of reference numerals: 1. Silver nanoparticles; 2. Conductive carbon black. DETAILED DESCRIPTION

[0058] 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.

[0059] 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.

[0060] The first aspect of the present application provides a modified conductive carbon black, comprising conductive carbon black modified by a silane coupling agent, and silver nanoparticles in situ grown on the surface of the conductive carbon black;

[0061] Based on the total volume of the modified conductive carbon black, the volume proportion of the silver nanoparticles is 0.5%~3%.

[0062] Silver nanoparticles have a high electron mobility. When silver nanoparticles are attached to the surface of conductive carbon black, they can improve the conductivity of conductive carbon black and reduce the conductive carbon black content required to form a conductive network, which is beneficial to improving the electrical properties of semi-conductive shielding materials. At the same time, silver nanoparticles can construct an interface transition layer between the conductive carbon black particles and the polymer matrix, providing additional steric hindrance, thereby reducing the aggregation tendency caused by van der Waals forces or electrostatic effects, and helping to maintain the dispersion of conductive carbon black in the polymer matrix; in addition, the interface transition layer has a bridging effect between different conductive carbon black aggregates, effectively promoting the transmission of charge carriers, thereby significantly reducing the contact resistance of conductive carbon black.

[0063] In the present application, the volume proportion of silver nanoparticles is 0.5% to 3%; as an example, the volume proportion of silver nanoparticles can be but not limited to 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5% or 3%.

[0064] In some optional embodiments, the volume proportion of the silver nanoparticles is 1%-3%.

[0065] Furthermore, the volume proportion of silver nanoparticles is 2% to 3%.

[0066] In some embodiments, the silane coupling agent contains a thiol group (-SH), an amine group (-NH 2 ), hydroxyl (-OH), vinyl (-CH=CH 2 ), trifluoropropyl (-CH 2 CH 2 CF 3 ) and chlorine atom (-Cl) one or more.

[0067] It is understandable that the above groups in the silane coupling agent can react with Ag + There is an interaction that promotes Ag + Uniform deposition on the surface of conductive carbon black. Specifically, -SH, -NH 2 Can be used with Ag + Forming coordination bonds, -OH can react with Ag + Form hydrogen bonds or coordination bonds, -CH 2 CH 2 CF 3 Can be used with Ag + Forming weak ion-dipole interaction, -Cl can react with Ag + Forming halogen bonds or ionic bonds.

[0068] In some embodiments, the silane coupling agent includes one or more of (3-mercaptopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

[0069] In one example, the silane coupling agent is selected from (3-mercaptopropyl)trimethoxysilane, ie, KH590.

[0070] In one example, the structure of the modified conductive carbon black is as follows Figure 1 shown.

[0071] The second aspect of the present application provides a method for preparing the above-mentioned modified conductive carbon black, including S100 and S200.

[0072] S100: using a silane coupling agent to modify the conductive carbon black to obtain modified conductive carbon black powder;

[0073] S200: In situ growth of silver nanoparticles on the surface of modified conductive carbon black powder to obtain modified conductive carbon black.

[0074] In some specific embodiments, the preparation process of the modified conductive carbon black is as follows Figure 2 shown.

[0075] In some implementation modes, S100 includes S110 to S140.

[0076] S110: mixing the conductive carbon black with the first solvent to obtain a conductive carbon black suspension;

[0077] S120: mixing a silane coupling agent with a second solvent to obtain a silane coupling agent solution;

[0078] S130: mixing the conductive carbon black suspension with the silane coupling agent solution, stirring at 60° C. to 90° C. to obtain a modified mixed solution;

[0079] S140: Centrifuging, drying and grinding the modified mixed solution in sequence to obtain modified conductive carbon black powder.

[0080] In some specific embodiments, in S110 , the conductive carbon black and the first solvent are fully mixed by shearing to form a uniform conductive carbon black suspension.

[0081] Optionally, the shearing speed is 1000 r / min~2000 r / min, and the shearing time is not less than 60 min.

[0082] In some specific embodiments, the first solvent in S110 is selected from anhydrous ethanol.

[0083] In some specific embodiments, the mass ratio of the conductive carbon black to the anhydrous ethanol in S110 is 1:(10-20). It can be understood that mixing the conductive carbon black and the anhydrous ethanol in a specific ratio can reduce the processing viscosity of the conductive carbon black dispersion, thereby reducing the impact on subsequent processes.

[0084] In some specific embodiments, the second solvent in S120 is selected from anhydrous ethanol.

[0085] In some specific embodiments, the pH value of the anhydrous ethanol in S120 is 3.5-4.5.

[0086] Optionally, an organic acid is used to adjust the pH value of anhydrous ethanol to 3.5 to 4.5. After the pH value of anhydrous ethanol is adjusted to the above range, it is mixed with the silane coupling agent to promote the hydrolysis of the silane coupling agent and completely dissolve it to a clear and transparent state.

[0087] Optionally, the organic acid comprises one or more of formic acid and acetic acid.

[0088] In some specific embodiments, the mass ratio of the silane coupling agent to the second solvent in S120 is 1:(5-10). As an example, the mass ratio of the silane coupling agent to the second solvent can be, but is not limited to, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0089] In some specific embodiments, the mass ratio of the silane coupling agent solution to the conductive carbon black suspension in S130 is 1:(19-99). As an example, the mass ratio of the conductive carbon black suspension to the silane coupling agent solution may be, but is not limited to, 1:19, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95 or 1:99.

[0090] In some specific embodiments, according to the different types of conductive carbon black, the mass ratio of the silane coupling agent solution to the conductive carbon black suspension can be calculated using the formula Wc / W=S1 / S2, wherein W is the mass of the conductive carbon black, in g, and S1 is the specific surface area of ​​the conductive carbon black, which can be obtained from the product specifications of the conductive carbon black, in m 2 / g, S2 is the minimum coverage area of ​​silane coupling agent, unit is m 2 / g, Wc is the mass of silane coupling agent, in g.

[0091] In some specific embodiments, the stirring speed in S130 is 800 r / min-1500 r / min, and the reaction time is greater than 3 h.

[0092] In some specific embodiments, after S130 and before S140, the following step is further included: naturally cooling the modified mixed solution to room temperature and transferring it to a centrifuge tube.

[0093] In some specific embodiments, the centrifugal speed in S140 is 3000 r / min to 10000 r / min, and the centrifugal time is not less than 20 min. It can be understood that after centrifugation, the solid modified conductive carbon black in the modified mixed solution will be deposited at the bottom of the centrifuge tube, while the unreacted silane coupling agent and solvent remain in the supernatant.

[0094] In some specific embodiments, after centrifugation and before drying in S140, the following step is further included: washing the precipitate collected after centrifugation, adding an appropriate amount of washing solvent for ultrasonic treatment to fully wash the modified conductive carbon black particles.

[0095] Optionally, washing is performed using one or more of anhydrous ethanol, propanol and deionized water.

[0096] In some specific embodiments, the steps of centrifugation and washing are repeated at least three times to ensure that the residual silane coupling agent and by-products are completely removed.

[0097] In some specific embodiments, the drying step in S140 includes: spreading the wet modified conductive carbon black on a glass or ceramic plate and drying it in an oven.

[0098] Optionally, the drying temperature is 60° C. to 80° C. After drying for 24 hours, the sample mass is measured every 3 hours until the sample mass is stable and the drying is completed.

[0099] Grinding was performed using a mortar and pestle in the S140 to remove larger aggregates from the dried modified conductive carbon black and obtain a uniformly dispersed powder.

[0100] In some implementation modes, S200 includes S210 and S220.

[0101] S210: mixing the modified conductive carbon black powder with a reducing agent solvent to obtain a suspension;

[0102] S220: mixing the suspension with the silver nitrate solution and stirring the mixture to react, so as to in-situ grow silver nanoparticles on the surface of the modified conductive carbon black powder.

[0103] The present invention adopts a chemical reduction method to obtain silver nanoparticles, which has simple steps, does not require complex equipment and high-precision control conditions, and can efficiently synthesize silver nanoparticles in large quantities, and is suitable for large-scale production.

[0104] In some specific embodiments, the reducing agent solution in S210 includes one or more of anhydrous ethanol, glucose solution, trisodium citrate solution, formaldehyde solution, sodium hypophosphite solution, sodium dithionite solution and tannin solution.

[0105] In a specific example, the reducing agent solution in S210 is selected from a glucose solution. Selecting glucose to prepare the reducing agent solution can effectively control the morphology and particle size of the silver nanoparticles.

[0106] In some specific embodiments, the concentration of the solute in the reducing agent solution in S210 is 4wt% to 6wt%. As an example, the concentration of the solute in the reducing agent solution may be, but is not limited to, 4wt%, 4.1wt%, 4.2wt%, 4.3wt%, 4.4wt%, 4.5wt%, 4.6wt%, 4.7wt%, 4.8wt%, 4.9wt%, 5wt%, 5.1wt%, 5.2wt%, 5.3wt%, 5.4wt%, 5.5wt%, 5.6wt%, 5.7wt%, 5.8wt%, 5.9wt% or 6wt%.

[0107] In some specific embodiments, the pH value of the reducing agent solution in S210 is 10.0-12.0. Optionally, a sodium hydroxide solution with a concentration of 0.1 mol / L is used to adjust the pH value of the reducing agent solution.

[0108] In some specific embodiments, the mass ratio of the modified conductive carbon black powder to the reducing agent solvent in S210 is 1:(20-50). As an example, the mass ratio of the modified conductive carbon black powder to the reducing agent solvent can be, but is not limited to, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:35, 1:40, 1:45 or 1:50.

[0109] In some specific embodiments, the mixing method in S210 is magnetic stirring. Optionally, the rotation speed of the magnetic stirring is 380 r / min to 420 r / min; further optionally, the rotation speed of the magnetic stirring is 400 r / min.

[0110] In some specific embodiments, the mixing method in S220 is to drop the silver nitrate solution into the suspension. Optionally, the dropping rate is 1 mL / min to 3 mL / min. The dropping speed of the silver nitrate solution is controlled within the above-mentioned specific range to ensure sufficient reaction time, so that the silver ions are reduced to silver nanoparticles on the surface of the conductive carbon black.

[0111] In some specific embodiments, the concentration of the solute in the silver nitrate solution in S220 is 0.05 mol / L to 0.2 mol / L. As an example, the concentration of the solute in the silver nitrate solution can be, but is not limited to, specific values ​​such as 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L or 0.2 mol / L.

[0112] In some specific embodiments, the stirring reaction temperature is 25°C to 35°C; the time is 2.5h to 3.5h. As an example, the stirring reaction temperature can be but not limited to 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, etc.; the stirring reaction time can be but not limited to 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3.0h, 3.1h, 3.2h, 3.3h, 3.4h or 3.5h, etc.

[0113] In some implementation modes, S200 also includes S230.

[0114] S230: centrifuging and drying the modified conductive carbon black in sequence.

[0115] Specifically, S230 includes: after the reaction in S220 is completed, transferring the product to a centrifuge tube for centrifugal separation, removing the supernatant and collecting the modified conductive carbon black precipitated at the bottom of the centrifuge tube; adding a washing solvent and thoroughly washing the collected modified conductive carbon black by ultrasonic treatment; spreading the washed wet particles on a glass or ceramic plate, and drying the modified conductive carbon black in an oven until the water and solvent are completely removed.

[0116] Optionally, the washing solvent in S230 includes one or more of anhydrous ethanol, propanol and deionized water.

[0117] Optionally, the centrifugal speed in S230 is 3000 r / min~10000 r / min, and the centrifugal time is not less than 20 min.

[0118] Optionally, the centrifugation and washing steps in S230 are repeated at least 3 times.

[0119] Optionally, the drying temperature in S230 is 60° C. to 80° C., and after drying for 24 hours, the sample mass is measured every 3 hours until the sample mass is stable.

[0120] The above-mentioned preparation method of the present application has the advantages of being simple, rapid, and highly efficient.

[0121] The third aspect of the present application provides a shielding material, which comprises the following components, by weight: 29 to 31 parts of modified conductive carbon black, 63 to 65 parts of ethylene-butyl acrylate copolymer, 1.4 to 1.6 parts of a cross-linking agent, and 2.4 to 2.6 parts of an auxiliary agent;

[0122] Wherein, the modified conductive carbon black includes the modified conductive carbon black mentioned above or the modified conductive carbon black prepared by the preparation method of the modified conductive carbon black mentioned above; the auxiliary agent includes one or more of a lubricant and an antioxidant.

[0123] In some embodiments, the crosslinking agent includes dicumyl peroxide. It is understood that the type of the crosslinking agent is not limited to the above, and can also be other crosslinking agents commonly used in the art.

[0124] In some embodiments, the mass ratio of the lubricant to the antioxidant is (3.9-4.1): 1. As an example, the mass ratio of the lubricant to the antioxidant may be, but is not limited to, specific ratios such as 3.9:1, 3.95:1, 4.0:1, 4.05:1 or 4.1:1.

[0125] In some specific embodiments, the lubricant includes one or more of zinc stearate and pentaerythritol.

[0126] In some specific embodiments, the antioxidant includes one or more of a hindered phenol antioxidant and a phosphite antioxidant.

[0127] Silver nanoparticles have a high electron mobility. When silver nanoparticles are attached to the surface of conductive carbon black, the conductivity of the conductive carbon black can be effectively improved. The modified conductive carbon black is used as a conductive filler for shielding materials to form a stable conductive network, thereby improving the electrical properties of the shielding materials.

[0128] A fourth aspect of the present application provides a method for preparing a shielding material, comprising the following steps a to d.

[0129] Step a: providing raw materials according to the components of the above-mentioned shielding material, mixing the modified conductive carbon black, lubricant and antioxidant at 60° C. to 70° C. to obtain a premix;

[0130] Step b: mixing the premix with ethylene-butyl acrylate copolymer to obtain a mixture;

[0131] Step c: performing mixing, melt extrusion and granulation on the mixture in sequence to obtain granular material;

[0132] Step d: mixing the granular material with a cross-linking agent and drying to obtain a shielding material.

[0133] In some embodiments, the kneading temperature in step c is 150° C. to 170° C., and the rotation speed is 80 r / min to 120 r / min.

[0134] In some embodiments, the temperature of melt extrusion in step c is 130°C to 160°C.

[0135] In some embodiments, the melt extrusion method in step c is six-zone heating; wherein the temperature of the first zone is 128°C~132°C, the temperature of the second zone is 138°C~142°C, the temperature of the third zone is 148°C~152°C, the temperature of the fourth zone is 158°C~162°C, the temperature of the fifth zone is 148°C~152°C, and the temperature of the sixth zone is 138°C~142°C.

[0136] In some embodiments, the mixing temperature in step d is 60° C. to 70° C. to ensure that the particles fully absorb the crosslinking agent.

[0137] In some specific embodiments, the preparation process of the above-mentioned shielding material is as follows Figure 2 shown.

[0138] A fifth aspect of the present application provides a cable, comprising the above-mentioned shielding material or the shielding material produced by the above-mentioned method for preparing the shielding material.

[0139] It can be understood that the cable containing the above-mentioned shielding material can be used as a high-voltage cable and has good conductivity and safety performance.

[0140] 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.

[0141] Example 1

[0142] (1) Conductive carbon black and anhydrous ethanol were mixed in a mass ratio of 1:10 and fully mixed using a shearing machine to form a uniform conductive carbon black suspension. The shearing speed was 1500 r / min and the shearing time was 60 min.

[0143] (2) (3-Mercaptopropyl)trimethoxysilane (also known as KH590) is used as a silane coupling agent. After adjusting the pH value of anhydrous ethanol to 4.5 with formic acid, KH590 and anhydrous ethanol are mixed in a mass ratio of 1:10, and the mixture is fully mixed until KH590 is completely dissolved and the solution is clear and transparent; thereby obtaining a silane coupling agent solution.

[0144] (3) The conductive carbon black suspension in step (1) is added to the KH590 solution in step (2) at a mass ratio of 100:3 to obtain a modifier mixed solution.

[0145] (4) The modified agent mixed solution obtained in step (3) was mechanically stirred in a water bath at a temperature of 60° C., with a rotation speed of 1000 r / min and a reaction time of 3 h.

[0146] After the reaction is completed, the mixture is naturally cooled to room temperature, then transferred to a centrifuge tube and centrifuged using a high-speed centrifuge at a rotational speed of 5000 r / min for 20 min.

[0147] (6) Remove the supernatant in step (5), add an appropriate amount of absolute ethanol, and perform ultrasonic treatment to ensure that the conductive carbon black particles are thoroughly washed; repeat steps (5) - (6) three times in total to obtain wet conductive carbon black particles.

[0148] (7) Spread the wet conductive carbon black particles on a glass or ceramic plate and dry them in an oven at 70 °C. Measure the sample mass every 3 h after 24 h until the sample mass is stable and all moisture and solvents are completely removed.

[0149] (8) Grind using a mortar and pestle to remove the larger aggregates in the dried modified conductive carbon black and obtain a uniformly dispersed modified conductive carbon black powder, named KH590@CCCB.

[0150] (9) Prepare a silver nitrate solution with a concentration of 0.2 mol / L by mixing silver nitrate with deionized water. Prepare a 0.05 mol / L glucose aqueous solution by mixing glucose with deionized water, and gradually add 0.1 mol / L sodium hydroxide solution to the glucose aqueous solution to adjust the pH value to 12 to obtain a reducing agent solution.

[0151] (10) Mix the KH590@CCB prepared in step (8) with the reducing agent solution at a mass ratio of 1:20, and mix them evenly by magnetic stirring to form a suspension; the rotational speed of magnetic stirring is 400 r / min, and the stirring time is 30 min.

[0152] (11) Drop the silver nitrate solution described in step (9) into the suspension described in step (10) to reduce silver ions to silver nanoparticles on the surface of KH590@CCB, with an initial dropping rate of 2 mL / min. React at 25 °C for no less than 2.5 h.

[0153] Control the dropping amount of the silver nitrate solution so that the volume of silver nanoparticles is 0.5% of the total volume of KH590@CCB and silver nanoparticles. Specifically, if the mass of KH590@CCB added is 5 g, then 7.3 mL of silver nitrate solution is added to the suspension.

[0154] (12) Clean the conductive carbon black with in-situ grown silver nanoparticles on the surface according to the cleaning steps in steps (5) - (6) to obtain modified conductive carbon black; name it AgNPs@CCB - 0.5 vol%.

[0155] (13) Preparation of semiconductive shielding material: In parts by mass, 64 parts of ethylene-butyl acrylate copolymer (EBA), 30 parts of AgNPs@CCB-0.5 vol% prepared in step (12), 1.5 parts of diisopropylbenzene peroxide, 2 parts of lubricant (zinc stearate and pentaerythritol are mixed in a mass ratio of 1:1), and 0.5 parts of antioxidant (antioxidant 1010 and antioxidant 168 are mixed in a mass ratio of 1:1) are provided.

[0156] The AgNPs@CCB-0.5 vol%, lubricant and antioxidant were uniformly mixed by mechanical stirring at 65° C. to prepare a mixture.

[0157] (14) The mixed material obtained in step (13) and ethylene-butyl acrylate copolymer are subjected to banburying at a banburying temperature of 160°C and a rotation speed of 100 r / min, followed by melt extrusion and granulation to prepare granular material. The melt extrusion adopts a six-zone heating method, wherein the temperature of zone 1 is 128°C-132°C, the temperature of zone 2 is 138°C-142°C, the temperature of zone 3 is 148°C-152°C, the temperature of zone 4 is 158°C-162°C, the temperature of zone 5 is 148°C-152°C, and the temperature of zone 6 is 138°C-142°C.

[0158] (15) The pellets are mixed evenly with diisopropylbenzene peroxide at a mixing temperature of 60° C. and dried to obtain a semiconductive shielding material.

[0159] Example 2

[0160] The method is basically the same as Example 1, except that step (11) is different; specifically, the volume of silver nanoparticles is 1% of the total volume of KH590@CCB and silver nanoparticles. Specifically, the mass of KH590@CCB added is 5 g, and 14.6 mL of silver nitrate solution is added to the suspension. The modified conductive carbon black finally obtained is named AgNPs@CCB-1vol%.

[0161] Example 3

[0162] The method is basically the same as Example 1, except that step (11) is different; specifically, the volume of silver nanoparticles is 2% of the total volume of KH590@CCB and silver nanoparticles. Specifically, the mass of KH590@CCB added is 5 g, and 29.5 mL of silver nitrate solution is added to the suspension. The modified conductive carbon black finally obtained is named AgNPs@CCB-2 vol%.

[0163] Example 4

[0164] The method is basically the same as Example 1, except that step (11) is different; specifically, the volume of silver nanoparticles is 3% of the total volume of KH590@CCB and silver nanoparticles. Specifically, the mass of KH590@CCB added is 5 g, and 44.6 mL of silver nitrate solution is added to the suspension. The modified conductive carbon black finally obtained is named AgNPs@CCB-3vol%.

[0165] Comparative Example 1

[0166] The components of the semiconductive shielding material are substantially the same as those of Example 1, except that an equal mass fraction of commercially available conductive carbon black is used to replace AgNPs@CCB-0.5 vol%.

[0167] Comparative Example 2

[0168] The components of the semiconductive shielding material are substantially the same as those of Example 1, except that the conductive carbon black in Comparative Example 2 is not modified with a silane coupling agent.

[0169] Comparative Example 3

[0170] The components of the semiconductive shielding material are substantially the same as those of Example 1, except that, after the conductive carbon black in Comparative Example 3 is modified with a silane coupling agent, no silver nanoparticles are attached to the surface.

[0171] The granular materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were heat treated at 180°C and 15MPa for 15 minutes by a flat-plate vulcanizing machine through a hot pressing process to fully crosslink and prepare a plate. The resistivity of the plate was tested in accordance with the national standard GB / T3048.3. The surface of the shielding material sheet extruded by a single screw was observed using an optical microscope (GP-304K) to evaluate the surface finish of the sample. Specifically, the test should be carried out under standard conditions of (23±2)°C and relative humidity of (50±5)%. The shielding material sheet was extruded using a torque rheometer. The sheet thickness was 1mm and the width was 25mm. The total surface area of ​​the sample used for the test was 1m 2 The results of the characterization of the size and number of surface protrusions are based on the total surface area of ​​1m 2 For the samples, the number of surface protrusions with a height greater than 50 μm was recorded. The specific results are shown in Table 1.

[0172] Table 1

[0173]

[0174] As shown in Table 1, compared with Comparative Examples 1 to 3, the shielding coatings prepared in Examples 1 to 4 of the present application have significant advantages in electrical properties and surface finish (fewer protrusions). The reason is that the higher electron mobility of silver nanoparticles and the interface transition layer constructed by in-situ growth of silver nanoparticles on the surface of conductive carbon black particles, the bridging effect between different conductive carbon black aggregates, promote the effective transmission of charge carriers, and significantly reduce the contact resistance between aggregates. At the same time, the interface transition layer provides additional steric hindrance for the conductive carbon black particles, effectively reducing the aggregation tendency of conductive carbon black caused by van der Waals forces or electrostatic effects, maintaining its uniform dispersion in the polymer matrix, thereby significantly improving the surface finish of the high-voltage cable shielding material.

[0175] Compared with Example 3 in which 2 vol% of silver nanoparticles are attached to the surface of carbon black, Example 4 in which 3 vol% of silver nanoparticles are attached to the surface of carbon black does not significantly improve the electrical properties of the shielding material. This may be because the interface compatibility between silver and the substrate is weaker than that of carbon black, which limits the enhancement of the electrical properties of the shielding material; therefore, the present application limits the volume ratio of silver nanoparticles to 0.5 vol%~3 vol%.

[0176] 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.

[0177] 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 modified conductive carbon black, characterized in that: It comprises conductive carbon black modified by a silane coupling agent, and silver nanoparticles in situ grown on the surface of the conductive carbon black; Based on the total volume of the modified conductive carbon black, the volume proportion of the silver nanoparticles is 0.5% to 3%.

2. The modified conductive carbon black according to claim 1, characterized in that The silane coupling agent contains one or more of a mercapto group, an amine group, a hydroxyl group, a vinyl group, a trifluoropropyl group and a chlorine atom; Optionally, the silane coupling agent includes one or more of (3-mercaptopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

3. A method for preparing the modified conductive carbon black according to any one of claims 1 to 2, characterized in that: The steps include: Using a silane coupling agent to modify the conductive carbon black to obtain modified conductive carbon black powder; Silver nanoparticles are in-situ grown on the surface of the modified conductive carbon black powder to obtain the modified conductive carbon black.

4. The method for preparing modified conductive carbon black according to claim 3, characterized in that: The preparation method comprises the following steps: Mixing the conductive carbon black with the first solvent to obtain a conductive carbon black suspension; Mixing a silane coupling agent with a second solvent to obtain a silane coupling agent solution; The conductive carbon black suspension is mixed with a silane coupling agent solution, and stirred at 60° C. to 90° C. to obtain a modified mixed solution; Centrifuging, drying and grinding the modified mixed solution in sequence to obtain the modified conductive carbon black powder; Mixing the modified conductive carbon black powder with a reducing agent solvent to obtain a suspension; The suspension is mixed with a silver nitrate solution and stirred to react, so as to in-situ grow silver nanoparticles on the surface of the modified conductive carbon black powder.

5. The method for preparing modified conductive carbon black according to claim 4, characterized in that: The preparation method meets at least one of the following characteristics: (1) The first solvent is selected from anhydrous ethanol; (2) The mass ratio of the conductive carbon black to the first solvent is 1:(10-20); (3) the second solvent is selected from anhydrous ethanol; (4) the pH value of the second solvent is 3.5 to 4.5; (5) The mass ratio of the silane coupling agent to the second solvent is 1:(5-10); (6) The mass ratio of the silane coupling agent solution to the conductive carbon black suspension is 1:(19-99); (7) the reducing agent solution comprises one or more of anhydrous ethanol, glucose solution, trisodium citrate solution, formaldehyde solution, sodium hypophosphite solution, sodium dithionite solution and tannin solution; (8) The concentration of the solute in the reducing agent solution is 4wt%~6wt%; (9) The pH value of the reducing agent solution is 10.0 to 12.0; (10) The concentration of the solute in the silver nitrate solution is 0.05 mol / L to 0.2 mol / L; (11) The mass ratio of the modified conductive carbon black powder to the reducing agent solvent is 1: (20-50); (12) The stirring reaction temperature is 25°C~35°C and the time is 2.5h~3.5h.

6. A shielding material, characterized in that: The composition comprises the following components by weight: 29-31 parts of modified conductive carbon black, 63-65 parts of ethylene-butyl acrylate copolymer, 1.4-1.6 parts of a crosslinking agent, and 2.4-2.6 parts of an auxiliary agent; Wherein, the modified conductive carbon black comprises the modified conductive carbon black described in any one of claims 1 to 2 or the modified conductive carbon black prepared by the preparation method of the modified conductive carbon black described in any one of claims 3 to 5; The auxiliary agent includes one or more of a lubricant and an antioxidant.

7. The shielding material according to claim 6, characterized in that The shielding material meets at least one of the following characteristics: (1) The cross-linking agent includes dicumyl peroxide; (2) The mass ratio of the lubricant to the antioxidant is (3.9-4.1): 1; (3) The lubricant includes one or more of zinc stearate and pentaerythritol; (4) The antioxidant includes one or more of a hindered phenol antioxidant and a phosphite antioxidant.

8. A method for preparing a shielding material, characterized in that: The steps include: Providing raw materials according to the components of the shielding material according to any one of claims 6 to 7, mixing the modified conductive carbon black, the lubricant and the antioxidant at 60° C. to 70° C. to obtain a premix; mixing the premix with ethylene-butyl acrylate copolymer to obtain a mixture; The mixture is subjected to sequential internal mixing, melt extrusion and granulation to obtain granular material; The granular material is mixed with a cross-linking agent and dried to obtain the shielding material.

9. The method for preparing the shielding material according to claim 8, characterized in that: The method for preparing the shielding material satisfies at least one of the following characteristics: (1) The mixing temperature is 150℃~170℃ and the speed is 80r / min~120r / min; (2) The temperature of melt extrusion is 130℃~160℃.

10. A cable, characterized in that: The invention comprises a shielding material according to any one of claims 6 to 7 or a shielding material prepared by the method for preparing the shielding material according to any one of claims 8 to 9.

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