Modified conductive carbon black and preparation method therefor, shielding material and preparation method therefor, and cable
Patent Information
- Application Number
- PCT/CN2025/120637
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-24
- Filing Date
- 2025-09-11
- Publication Date
- 2026-08-27
Smart Images
Figure CN2025120637_27082026_PF_FP_ABST
Abstract
Description
Modified conductive carbon black and its preparation method, shielding materials and their preparation methods, cables Technical Field
[0001] This application relates to the field of conductive materials technology, and in particular to a modified conductive carbon black and its preparation method, a shielding material and its preparation method, and a cable. Background Technology
[0002] Applying semiconductive composite materials to the shielding layer of high-voltage cables is crucial for optimizing the electric field distribution in high-voltage cables and improving their operational safety.
[0003] Conductive carbon black is widely used as a conductive filler in semi-conductive shielding materials for high-voltage cables due to its stable conductivity and cost-effectiveness; however, the aggregated structure of conductive carbon black makes it prone to agglomeration in polymer matrices, increasing contact resistance, affecting the performance of shielding materials, and thus reducing the electrical performance of cables.
[0004] Currently, researchers are attempting to improve the dispersibility and interfacial compatibility of conductive carbon black by using multifunctional wetting dispersants. However, the insulating properties of these dispersants reduce the conductivity of the conductive carbon black, limiting the improvement in the conductivity of the shielding material. Furthermore, researchers have also introduced graphene, which has a higher carrier mobility, as a second conductive filler to reduce the amount of conductive carbon black used. However, the strong intermolecular forces of graphene cause it to easily stack and entangle, resulting in an uneven conductive network and reducing the dispersibility of the shielding material.
[0005] Therefore, traditional shielding materials still need improvement. Summary of the Invention
[0006] Based on this, one or more embodiments of this application provide a modified conductive carbon black with low contact resistance and excellent conductivity and dispersibility, a method for preparing the same, a shielding material and a method for preparing the same, and a cable.
[0007] According to a first aspect of the embodiments of this application, a modified conductive carbon black is provided, comprising conductive carbon black modified with a silane coupling agent, and silver nanoparticles grown in situ on the surface of the conductive carbon black.
[0008] The volume percentage of the silver nanoparticles is 0.5% to 3% based on the total volume of the modified conductive carbon black.
[0009] In one embodiment, the silane coupling agent comprises one or more of the following groups: mercapto, amino, hydroxyl, vinyl, trifluoropropyl, and chlorine atom;
[0010] Optionally, the silane coupling agent comprises one or more of (3-mercaptopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.
[0011] According to a second aspect of the embodiments of this application, a method for preparing the above-mentioned modified conductive carbon black is provided, comprising the following steps:
[0012] Conductive carbon black was modified with a silane coupling agent to obtain modified conductive carbon black powder.
[0013] Silver nanoparticles are grown in situ on the surface of the modified conductive carbon black powder to obtain the modified conductive carbon black.
[0014] In one embodiment, the preparation method includes the following steps:
[0015] The conductive carbon black is mixed with the first solvent to obtain a conductive carbon black suspension;
[0016] The silane coupling agent is mixed with a second solvent to obtain a silane coupling agent solution;
[0017] The conductive carbon black suspension was mixed with a silane coupling agent solution and stirred at 60°C to 90°C to obtain a modified mixed solution.
[0018] The modified mixed solution was subjected to centrifugation, drying, and grinding in sequence to obtain the modified conductive carbon black powder;
[0019] The modified conductive carbon black powder was mixed with a reducing agent solvent to obtain a suspension;
[0020] The suspension was mixed with a silver nitrate solution and stirred to grow silver nanoparticles in situ 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 includes one or more of the following: 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% to 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 temperature of the stirring reaction is 25℃~35℃; the time is 2.5h~3.5h.
[0034] According to a third aspect of the embodiments of this application, a shielding material is provided, comprising, by weight parts: 29 to 31 parts modified conductive carbon black, 63 to 65 parts ethylene-butyl acrylate copolymer, 1.4 to 1.6 parts crosslinking agent, and 2.4 to 2.6 parts additives;
[0035] The modified conductive carbon black includes the modified conductive carbon black described above or the modified conductive carbon black prepared by the above-described method.
[0036] The additives include one or more of lubricants and antioxidants.
[0037] In one embodiment, the shielding material satisfies at least one of the following characteristics:
[0038] (1) The crosslinking 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 antioxidants include one or more of hindered phenolic antioxidants and phosphite antioxidants.
[0042] According to a fourth aspect of the embodiments of this application, a method for preparing a shielding material is provided, comprising the following steps:
[0043] The raw materials are provided according to the above-mentioned shielding material composition. Modified conductive carbon black, lubricant and antioxidant are mixed at 60℃~70℃ to obtain a premix.
[0044] The premix was mixed with ethylene-butyl acrylate copolymer to obtain a mixture;
[0045] The mixture is subjected to intensive mixing, melt extrusion and granulation in sequence to obtain granular material;
[0046] The granular material is mixed with a crosslinking 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 temperature of the internal mixing is 150℃~170℃, and the rotation speed is 80r / min~120r / min;
[0049] (2) The temperature of melt extrusion is 130℃~160℃.
[0050] According to a fifth aspect of the embodiments of this application, a cable is provided, comprising the shielding material described above or the shielding material prepared by the method described above.
[0051] Compared with traditional technologies, this application has the following advantages:
[0052] This application attaches silver nanoparticles with high electron mobility 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 tendency to aggregate due to van der Waals forces or electrostatic effects, and helping to maintain the dispersion state of 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 transport of charge carriers, thereby reducing the contact resistance of conductive carbon black. Attached Figure Description
[0053] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0054] Figure 1 is a schematic diagram of the structure of modified conductive carbon black in one embodiment of this application;
[0055] Figure 2 is a process flow diagram for preparing modified conductive carbon black in one embodiment of this application;
[0056] Figure 3 is a process flow diagram for preparing the shielding material in one embodiment of this application.
[0057] Explanation of reference numerals in the attached figures: 1. Silver nanoparticles; 2. Conductive carbon black. Detailed Implementation
[0058] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.
[0060] The first aspect of this application provides a modified conductive carbon black, including conductive carbon black modified with a silane coupling agent, and silver nanoparticles grown in situ on the surface of the conductive carbon black.
[0061] Based on the total volume of modified conductive carbon black, the volume percentage of silver nanoparticles is 0.5% to 3%.
[0062] Silver nanoparticles possess high electron mobility. When attached to the surface of conductive carbon black, they can enhance the conductivity of the carbon black, reduce the amount of conductive carbon black required to form a conductive network, and improve the electrical performance of semiconductive shielding materials. Simultaneously, silver nanoparticles can construct an interfacial transition layer between the conductive carbon black particles and the polymer matrix, providing additional steric hindrance and reducing the aggregation tendency caused by van der Waals forces or electrostatic interactions, thus helping to maintain the dispersion of conductive carbon black in the polymer matrix. Furthermore, this interfacial transition layer acts as a bridge between different conductive carbon black aggregates, effectively promoting charge carrier transport and significantly reducing the contact resistance of the conductive carbon black.
[0063] In this application, the volume percentage of silver nanoparticles is 0.5% to 3%; as an example, the volume percentage of silver nanoparticles can be, but is not limited to, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, or 3%.
[0064] In some alternative embodiments, the volume fraction of silver nanoparticles is 1% to 3%.
[0065] Furthermore, the volume percentage of silver nanoparticles is 2% to 3%.
[0066] In some embodiments, the silane coupling agent contains one or more of the following: mercapto (-SH), amino (-NH2), hydroxyl (-OH), vinyl (-CH=CH2), trifluoropropyl (-CH2CH2CF3), and chlorine (-Cl).
[0067] Understandably, the aforementioned 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 and -NH2 can react with Ag. + Forming coordinate bonds, -OH can react with Ag + Hydrogen bonds or coordinate bonds can be formed; -CH2CH2CF3 can react with Ag. + Weak ion-dipole interactions are formed; -Cl can react with Ag. + It forms 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-glycidoxypropyltrimethoxysilane, 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, namely KH590.
[0070] In one example, the structure of the modified conductive carbon black is shown in Figure 1.
[0071] The second aspect of this application provides a method for preparing the above-mentioned modified conductive carbon black, including steps S100 and S200.
[0072] S100: Conductive carbon black is modified with a silane coupling agent to obtain modified conductive carbon black powder;
[0073] S200: Silver nanoparticles are grown in situ 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 shown in Figure 2.
[0075] In some of these embodiments, S100 includes S110 to S140.
[0076] S110: The conductive carbon black is mixed with the first solvent to obtain a conductive carbon black suspension;
[0077] S120: Mix the silane coupling agent with the second solvent to obtain a silane coupling agent solution;
[0078] S130: A conductive carbon black suspension is mixed with a silane coupling agent solution and stirred at 60℃~90℃ to obtain a modified mixed solution;
[0079] S140: The modified mixed solution is centrifuged, dried and ground sequentially to obtain modified conductive carbon black powder.
[0080] In some specific embodiments, in S110, the conductive carbon black and the first solvent are thoroughly mixed by shearing to form a uniform conductive carbon black suspension.
[0081] Optionally, the shearing speed is 1000 r / min to 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 conductive carbon black to anhydrous ethanol in S110 is 1:(10-20). Understandably, mixing conductive carbon black and anhydrous ethanol in a specific ratio can reduce the processing viscosity of the conductive carbon black dispersion, thereby reducing its 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 to 4.5.
[0086] Optionally, the pH of anhydrous ethanol can be adjusted to 3.5–4.5 using an organic acid. Adjusting the pH of anhydrous ethanol to this range and then mixing it with the silane coupling agent promotes the hydrolysis of the silane coupling agent, allowing it to completely dissolve and become clear and transparent.
[0087] Alternatively, the organic acid includes 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, specific ratios such as 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 can 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, depending on the type 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, where W is the mass of the conductive carbon black in grams (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 m². 2 / g, S2 is the minimum coverage area of the silane coupling agent, in m². 2 / g, where Wc is the mass of the silane coupling agent in grams.
[0091] In some specific embodiments, the stirring speed in S130 is 800 r / min to 1500 r / min, and the reaction time is greater than 3 h.
[0092] In some specific embodiments, after S130 and before S140, the following steps are also included: naturally cooling the modified mixed solution to room temperature and transferring it to a centrifuge tube.
[0093] In some specific embodiments, the centrifugation speed in S140 is 3000 r / min to 10000 r / min, and the centrifugation time is not less than 20 min. Understandably, after centrifugation, the solid modified conductive carbon black in the modified mixed solution will be deposited at the bottom of the centrifuge tube, while unreacted silane coupling agent and solvent remain in the supernatant.
[0094] In some specific embodiments, S140, after centrifugation and before drying, further includes the following steps: washing the precipitate collected after centrifugation; adding an appropriate amount of washing solvent and ultrasonically treating the precipitate to thoroughly wash the modified conductive carbon black particles.
[0095] Alternatively, washing may be performed using one or more of anhydrous ethanol, propanol, and deionized water.
[0096] In some specific embodiments, the centrifugation and washing steps are repeated at least three times to ensure complete removal of residual silane coupling agent and byproducts.
[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℃~80℃. After drying for 24 hours, the sample mass is measured every 3 hours until the sample mass stabilizes, indicating that drying is complete.
[0099] S140 uses a mortar and pestle for grinding to remove larger aggregates in the dried modified conductive carbon black and obtain a uniformly dispersed powder.
[0100] In some implementations, S200 includes S210 and S220.
[0101] S210: The modified conductive carbon black powder is mixed with a reducing agent solvent to obtain a suspension;
[0102] S220: The suspension is mixed with silver nitrate solution and stirred to grow silver nanoparticles in situ on the surface of the modified conductive carbon black powder.
[0103] This application uses a chemical reduction method to obtain silver nanoparticles, which has the advantages of simple steps, no need for complex equipment and high-precision control conditions, and can efficiently synthesize silver nanoparticles in large quantities, making it 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. Choosing glucose to prepare the reducing agent solution allows for effective control of 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 4 wt% to 6 wt%. As an example, the concentration of the solute in the reducing agent solution can be, but is not limited to, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, 5 wt%, 5.1 wt%, 5.2 wt%, 5.3 wt%, 5.4 wt%, 5.5 wt%, 5.6 wt%, 5.7 wt%, 5.8 wt%, 5.9 wt%, or 6 wt%.
[0107] In some specific embodiments, the pH value of the reducing agent solution in S210 is 10.0–12.0. Optionally, the pH value of the reducing agent solution is adjusted using a 0.1 mol / L sodium hydroxide solution.
[0108] In some specific embodiments, the mass ratio of modified conductive carbon black powder to reducing agent solvent in S210 is 1:(20-50). As an example, the mass ratio of modified conductive carbon black powder to 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; more preferably, the rotation speed of the magnetic stirring is 400 r / min.
[0110] In some specific embodiments, the mixing in S220 involves adding a silver nitrate solution dropwise to the suspension. Optionally, the dropping rate is 1 mL / min to 3 mL / min. Controlling the dropping rate of the silver nitrate solution within the above-mentioned specific range ensures sufficient reaction time, thereby reducing silver ions to silver nanoparticles on the conductive carbon black surface.
[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 temperature of the stirring reaction is 25℃~35℃; the time is 2.5h~3.5h. As an example, the temperature of the stirring reaction can be, but is not limited to, specific values such as 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, or 35℃; the time of the stirring reaction can be, but is not limited to, specific values such as 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, or 3.5h.
[0113] In some implementations, S200 also includes S230.
[0114] S230: The modified conductive carbon black is centrifuged and dried sequentially.
[0115] Specifically, S230 includes: after the reaction in S220 is completed, transferring the product to a centrifuge tube for centrifugation, removing the supernatant and collecting the modified conductive carbon black precipitated at the bottom of the centrifuge tube; adding 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 moisture 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 centrifugation speed in S230 is 3000 r / min to 10000 r / min, and the centrifugation 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℃~80℃, and the sample mass is measured every 3 hours after drying for 24 hours until the sample mass is stable.
[0120] The preparation method described in this application has the advantages of being simple, rapid, and efficient.
[0121] The third aspect of this application provides a shielding material, comprising, by weight parts: 29 to 31 parts modified conductive carbon black, 63 to 65 parts ethylene-butyl acrylate copolymer, 1.4 to 1.6 parts crosslinking agent, and 2.4 to 2.6 parts additives;
[0122] The modified conductive carbon black includes the modified conductive carbon black described above or the modified conductive carbon black prepared by the above-described method; the additives include one or more of lubricants and antioxidants.
[0123] In some embodiments, the crosslinking agent includes dicumyl peroxide. Understandably, the type of crosslinking agent is not limited to those described above, and may also include other crosslinking agents commonly used in the art.
[0124] In some embodiments, the mass ratio of lubricant to antioxidant is (3.9 to 4.1):1. As an example, the mass ratio of lubricant to antioxidant can be, but is not limited to, 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 hindered phenolic antioxidants and phosphite antioxidants.
[0127] Silver nanoparticles possess high electron mobility, and when attached to the surface of conductive carbon black, they can effectively improve the conductivity of the conductive carbon black. Using the aforementioned modified conductive carbon black as a conductive filler in shielding materials can form a stable conductive network, thereby enhancing the electrical performance of the shielding material.
[0128] The fourth aspect of this application provides a method for preparing a shielding material, comprising the following steps a to d.
[0129] Step a: Provide the raw materials according to the above-mentioned shielding material composition, and mix the modified conductive carbon black, lubricant and antioxidant at 60℃~70℃ to obtain a premix;
[0130] Step b: Mix the premix with the ethylene-butyl acrylate copolymer to obtain a mixture;
[0131] Step c: The mixture is subjected to intensive mixing, melt extrusion, and granulation in sequence to obtain granular material;
[0132] Step d: Mix the granular material with the crosslinking agent and dry it to obtain the shielding material.
[0133] In some embodiments, the mixing 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 in step c is performed by six-zone heating; wherein the temperature of the first zone is 128°C to 132°C, the temperature of the second zone is 138°C to 142°C, the temperature of the third zone is 148°C to 152°C, the temperature of the fourth zone is 158°C to 162°C, the temperature of the fifth zone is 148°C to 152°C, and the temperature of the sixth zone is 138°C to 142°C.
[0136] In some embodiments, the mixing temperature in step d is 60°C to 70°C to ensure that the granules fully absorb the crosslinking agent.
[0137] In some specific embodiments, the preparation process of the above-mentioned shielding material is shown in Figure 2.
[0138] The fifth aspect of this application provides a cable comprising the shielding material described above or a shielding material prepared by the method described above.
[0139] Understandably, cables containing the aforementioned shielding materials can be used as high-voltage cables and have good conductivity and safety performance.
[0140] The present application will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present application. Unless otherwise specified, the raw materials involved in the following specific embodiments are all commercially available, the instruments used are all commercially available, and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.
[0141] Example 1
[0142] (1) Mix conductive carbon black and anhydrous ethanol at a mass ratio of 1:10 and mix thoroughly using a shearing machine to form a uniform conductive carbon black suspension. The shearing speed is 1500 r / min and the shearing time is 60 min.
[0143] (2) Using (3-mercaptopropyl)trimethoxysilane (also known as KH590) as a silane coupling agent, after adjusting the pH of anhydrous ethanol to 4.5 with formic acid, KH590 and anhydrous ethanol are mixed at a mass ratio of 1:10 and mixed thoroughly until KH590 is completely dissolved and the solution is clear and transparent; thus, a silane coupling agent solution is obtained.
[0144] (3) Add the conductive carbon black suspension from step (1) to the KH590 solution from step (2) at a mass ratio of 100:3 to obtain a modifier mixed solution.
[0145] (4) The modified agent mixture obtained in step (3) is mechanically stirred in a water bath at 60°C at a speed of 1000 r / min for 3 h.
[0146] (5) After the reaction is complete, the mixture is naturally cooled to room temperature, then transferred to a centrifuge tube and centrifuged using a high-speed centrifuge at a speed of 5000 r / min for 20 min.
[0147] (6) Remove the supernatant from step (5), add an appropriate amount of anhydrous ethanol, and sonicate to ensure that the conductive carbon black particles are thoroughly washed; repeat steps (5) to (6) a total of 3 times 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. After 24 hours, measure the sample mass every 3 hours until the sample mass is stable and the moisture and solvent are completely removed.
[0149] (8) Grind the modified conductive carbon black with 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 glucose aqueous solution with a concentration of 0.05 mol / L by mixing glucose with deionized water, and add 0.1 mol / L sodium hydroxide solution dropwise to the glucose aqueous solution to adjust the pH value to 12, thereby obtaining a reducing agent solution.
[0151] (10) The KH590@CCB obtained in step (8) is mixed with the reducing agent solution at a mass ratio of 1:20 and mixed evenly by magnetic stirring to form a suspension; the magnetic stirring speed is 400 r / min and the stirring time is 30 min.
[0152] (11) The silver nitrate solution described in step (9) is added dropwise to the suspension described in step (10) to reduce silver ions to silver nanoparticles on the KH590@CCB surface. The initial drop rate is 2 mL / min. The reaction is carried out at 25°C for no less than 2.5 h.
[0153] The amount of silver nitrate solution added was controlled so that the volume of the silver nanoparticles was 0.5% of the total volume of KH590@CCB and the silver nanoparticles. Specifically, if the mass of added KH590@CCB was 5g, then 7.3mL of silver nitrate solution was added to the suspension.
[0154] (12) The conductive carbon black with in-situ grown silver nanoparticles on the surface was cleaned according to the cleaning steps (5) to (6) to obtain modified conductive carbon black; named AgNPs@CCB-0.5vol%.
[0155] (13) Preparation of semiconductive shielding material: by mass parts, provide 64 parts of ethylene-butyl acrylate copolymer (EBA), 30 parts of AgNPs@CCB-0.5 vol% obtained in step (12), 1.5 parts of dicumyl peroxide, 2 parts of lubricant (in which zinc stearate and pentaerythritol are mixed in a mass ratio of 1:1), and 0.5 parts of antioxidant (in which antioxidant 1010 and antioxidant 168 are mixed in a mass ratio of 1:1).
[0156] The AgNPs@CCB-0.5vol%, lubricant, and antioxidant were mixed evenly by mechanical stirring at 65°C according to the above-mentioned parts by weight to prepare a mixture.
[0157] (14) The mixture obtained in step (13) and the ethylene-butyl acrylate copolymer are subjected to intensive mixing at a temperature of 160°C and a rotation speed of 100 r / min. Subsequently, the mixture is melt-extruded and granulated to prepare granules. 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) Mix the granular material with diisopropylbenzene peroxide evenly at a mixing temperature of 60°C and dry to obtain a semi-conductive shielding material.
[0159] Example 2
[0160] The process is basically the same as in Example 1, except that step (11) is different. Specifically, the volume of the silver nanoparticles is 1% of the total volume of KH590@CCB and the silver nanoparticles. Specifically, the mass of the added KH590@CCB is 5g, and 14.6mL of silver nitrate solution is added to the suspension. The modified conductive carbon black obtained is named AgNPs@CCB-1vol.
[0161] Example 3
[0162] The process is basically the same as in Example 1, except that step (11) is different. Specifically, the volume of the silver nanoparticles is 2% of the total volume of KH590@CCB and the silver nanoparticles. Specifically, the mass of the added KH590@CCB is 5g, and 29.5mL of silver nitrate solution is added to the suspension. The modified conductive carbon black obtained is named AgNPs@CCB-2vol%.
[0163] Example 4
[0164] The process is basically the same as in Example 1, except that step (11) is different. Specifically, the volume of the silver nanoparticles is 3% of the total volume of KH590@CCB and the silver nanoparticles. Specifically, the mass of the added KH590@CCB is 5g, and 44.6mL of silver nitrate solution is added to the suspension. The modified conductive carbon black obtained is named AgNPs@CCB-3vol%.
[0165] Comparative Example 1
[0166] The composition of the semiconductive shielding material is basically the same as that in Example 1, except that an equal mass fraction of commercially available conductive carbon black is used instead of AgNPs@CCB-0.5 vol%.
[0167] Comparative Example 2
[0168] The composition of the semiconductive shielding material in Comparative Example 2 is basically the same as that in 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 composition of the semiconductive shielding material in Example 1 is basically the same as that in Comparative Example 3, the conductive carbon black does not have silver nanoparticles attached to its surface after being modified with a silane coupling agent.
[0171] The granules prepared in Examples 1-4 and Comparative Examples 1-3 were heat-treated at 180℃ and 15MPa for 15 minutes using a flat vulcanizing machine via hot pressing to ensure full cross-linking and prepare sheets. The resistivity of these sheets was tested according to national standard GB / T3048.3. The surface of the shielding material sheets extruded by a single screw was observed using an optical microscope (GP-304K) to evaluate the surface smoothness of the samples. Specifically, the test was conducted under standard conditions of (23±2)℃ and (50±5)% relative humidity. A torque rheometer was used for extruding the shielding material sheets, which were 1mm thick and 25mm wide. The total surface area of the samples used for testing was 1m². 2 The size and number of surface protrusions were characterized based on the total test surface area of 1 m². 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 1-3, the shielding coatings prepared in Examples 1-4 of this application have significant advantages in electrical properties and surface smoothness (fewer protrusions). This is because the high electron mobility of silver nanoparticles and the interfacial transition layer constructed by in-situ grown silver nanoparticles on the surface of conductive carbon black particles, through bridging between different conductive carbon black aggregates, promote the effective transport of charge carriers and significantly reduce the contact resistance between aggregates. Simultaneously, this interfacial transition layer provides additional steric hindrance for the conductive carbon black particles, effectively reducing the tendency of conductive carbon black to aggregate due to van der Waals forces or electrostatic effects, maintaining its uniform dispersion in the polymer matrix, thereby significantly improving the surface smoothness of the high-voltage cable shielding material.
[0175] Compared with Example 3, where 2 vol% of silver nanoparticles were attached to the carbon black surface, the improvement in the electrical performance of the shielding material was not significant when 3 vol% of silver nanoparticles were attached to the carbon black surface in Example 4. This may be because the interfacial compatibility between silver and the matrix is weaker than that between silver and carbon black, which limits the enhancement of the electrical performance of the shielding material. Therefore, this application limits the volume ratio of silver nanoparticles to 0.5 vol% to 3 vol%.
[0176] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0177] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.
Claims
1. A modified conductive carbon black, characterized in that, The conductive carbon black is modified with a silane coupling agent, and silver nanoparticles are grown in situ on the surface of the conductive carbon black. The volume percentage of the silver nanoparticles is 0.5% to 3% based on the total volume of the modified conductive carbon black.
2. The modified conductive carbon black according to claim 1, characterized in that, The silane coupling agent contains one or more of the following groups: mercapto, amino, hydroxyl, vinyl, trifluoropropyl, and chlorine atom; Optionally, the silane coupling agent comprises one or more of (3-mercaptopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, vinyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.
3. A method for preparing modified conductive carbon black as described in any one of claims 1 to 2, characterized in that, Includes the following steps: Conductive carbon black was modified with a silane coupling agent to obtain modified conductive carbon black powder. Silver nanoparticles are grown in situ 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 includes the following steps: The conductive carbon black is mixed with the first solvent to obtain a conductive carbon black suspension; The silane coupling agent is mixed with a second solvent to obtain a silane coupling agent solution; The conductive carbon black suspension was mixed with a silane coupling agent solution and stirred at 60°C to 90°C to obtain a modified mixed solution. The modified mixed solution was subjected to centrifugation, drying, and grinding in sequence to obtain the modified conductive carbon black powder; The modified conductive carbon black powder was mixed with a reducing agent solvent to obtain a suspension; The suspension was mixed with a silver nitrate solution and stirred to grow silver nanoparticles in situ 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 satisfies 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 includes one or more of the following: 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% to 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 temperature of the stirring reaction is 25℃~35℃; the time is 2.5h~3.5h.
6. A shielding material, characterized in that, By weight, it comprises the following components: 29-31 parts modified conductive carbon black, 63-65 parts ethylene-butyl acrylate copolymer, 1.4-1.6 parts crosslinking agent, and 2.4-2.6 parts additives; The modified conductive carbon black includes the modified conductive carbon black prepared by any one of the methods described in claims 1 to 2 or the modified conductive carbon black prepared by any one of the methods described in claims 3 to 5. The additives include one or more of lubricants and antioxidants.
7. The shielding material according to claim 6, characterized in that, The shielding material satisfies at least one of the following characteristics: (1) The crosslinking 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 antioxidants include one or more of hindered phenolic antioxidants and phosphite antioxidants.
8. A method for preparing a shielding material, characterized in that, Includes the following steps: The raw materials for the shielding material according to any one of claims 6 to 7 are provided, and the modified conductive carbon black, lubricant and antioxidant are mixed at 60°C to 70°C to obtain a premix. The premix was mixed with ethylene-butyl acrylate copolymer to obtain a mixture; The mixture is subjected to intensive mixing, melt extrusion and granulation in sequence to obtain granular material; The granular material is mixed with a crosslinking 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 temperature of the internal mixing is 150℃~170℃, and the rotation speed is 80r / min~120r / min; (2) The temperature of melt extrusion is 130℃~160℃.
10. A cable, characterized in that, The shielding material includes the shielding material according to any one of claims 6 to 7 or the shielding material prepared by the method according to any one of claims 8 to 9.