A silicone rubber seal ring for capacitors and a method for producing the same

Abstract

The application relates to the field of sealing rings and discloses a silicon rubber sealing ring for capacitors and a preparation method thereof, which comprises the following components: silicon rubber, modified multi-walled carbon nanotubes, hyperbranched triazine-based additives, vulcanizing agents and lubricants; the modified multi-walled carbon nanotubes are prepared by modifying multi-walled carbon nanotubes after introducing double bonds into a benzotriazole intermediate and glycidyl methacrylate in a hydrogen-containing silicone oil molecular chain through a silicon hydrogen addition reaction; the benzotriazole intermediate is prepared by substitution between 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and acryloyl chloride; the hyperbranched triazine-based additives are prepared by nucleophilic substitution reaction with a diamino phosphorus antioxidant prepared by reaction between phenylphosphoryl dichloride and p-phenylenediamine and cyanuric chloride as a monomer; the application is provided with good mechanical properties, antistatic properties, flame retardant properties and aging resistance by adding the modified multi-walled carbon nanotubes and the hyperbranched triazine-based additives.

Description

Technical Field

[0001] This invention belongs to the field of sealing ring technology, specifically relating to a silicone rubber sealing ring for capacitors and its preparation method. Background Technology

[0002] Capacitors are fundamental components in electronic circuits, widely used in communication equipment, new energy, automotive, railway transportation, aerospace, and other fields. With the advent of new energy and the 5G era, the operating environments for capacitors are becoming increasingly demanding, placing higher requirements on their sealing performance. Current capacitor seals primarily utilize different types of rubber materials to prevent electrolyte leakage and the intrusion of corrosive external ions. Commonly used sealing materials include silicone rubber, EPDM rubber, and butyl rubber. Silicone rubber, due to its excellent high and low temperature resistance, compression set resistance, and chemical inertness, is irreplaceable in the field of capacitor sealing rings. However, traditional silicone rubber seals are mostly electrical insulating materials with high volume resistivity, lacking electrostatic dissipation capabilities, and are flammable. Furthermore, they are susceptible to damage from long-term ultraviolet radiation and thermal aging. Under certain conditions, silicone rubber molecular chains are prone to breakage and cross-linking failure, leading to a decline in mechanical properties and a shortened sealing life. In addition, due to the high flexibility of silicone rubber molecules and the weak interaction forces between molecular chains, its mechanical properties are poor and cannot meet the application requirements. Existing technologies enhance the mechanical properties of rubber compounds by adding inorganic fillers, but inorganic fillers have poor compatibility with the matrix and are prone to agglomeration. Currently used silane coupling agents can improve the dispersibility of inorganic fillers, but existing silane coupling agents have disadvantages such as difficulty in controlling the hydrolysis process, easy occurrence of side reactions, and insufficient durability and anti-aging properties, which affect the performance of the products. Summary of the Invention

[0003] To address the shortcomings mentioned in the background art, the present invention aims to provide a silicone rubber sealing ring for capacitors and its preparation method. By adding modified multi-walled carbon nanotubes and hyperbranched triazine-based additives, the sample is endowed with good mechanical properties, antistatic properties, flame retardant properties and aging resistance.

[0004] The objective of this invention can be achieved through the following technical solutions: A silicone rubber sealing ring for capacitors comprises the following components in parts by weight: 100 parts silicone rubber, 5-12 parts modified multi-walled carbon nanotubes, 2-5 parts hyperbranched triazine-based additives, 1-3 parts vulcanizing agent, and 0.3-1 parts lubricant. The modified multi-walled carbon nanotubes are prepared by modifying multi-walled carbon nanotubes with an organosilicon benzotriazole compatibilizer. The organosilicon benzotriazole compatibilizer is prepared by introducing a double-bond modified benzotriazole intermediate and glycidyl methacrylate into the molecular chain of hydrogen-containing silicone oil through a hydrosilylation reaction. The double-bond modified benzotriazole intermediate is prepared by substitution of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole with acryloyl chloride. The hyperbranched triazine-based additive is prepared by a nucleophilic substitution reaction between phenylphosphine dichloride and p-phenylenediamine to obtain a bisamino phosphorus-containing antioxidant, which is then used as a monomer and cyanuric chloride to produce the additive through a nucleophilic substitution reaction.

[0005] Preferably, the method for preparing the modified multi-walled carbon nanotubes includes the following steps: A. Add 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and triethylamine to the reactor and stir to mix. Then add a mixed solution of acryloyl chloride and tetrahydrofuran dropwise. Stir the reaction under ice bath conditions for 7-9 hours. Wash the crude product with saturated sodium bicarbonate solution. Wash the oily liquid on the top with anhydrous ethanol and dry to prepare the double bond modified benzotriazole intermediate. B. Add isopropanol, double bond modified benzotriazole intermediate and hydrogen-containing silicone oil to the reactor, heat to 55~70℃ and stir to mix, then add Karstedt catalyst, further heat to 75~85℃ and stir to react for 3~4h, cool to obtain organosilicon benzotriazole derivative. C. Take isopropanol, glycidyl methacrylate and Karstedt catalyst, stir and mix to obtain a dispersion, slowly add the dispersion dropwise to a reactor containing organosilicon benzotriazole derivative, heat to 55~70℃ and stir for 2~3h. After the reaction is completed, add activated carbon and stir at 40℃ for 2h to adsorb the residual catalyst. Finally, filter and distill under reduced pressure to prepare organosilicon benzotriazole compatibilizer. D. Multi-walled carbon nanotubes were plasma-treated for 15 min and then dispersed in anhydrous ethanol. The dispersion was ultrasonically stirred for 0.5 h under ice-water bath conditions. The dispersion was then transferred to a reactor and slowly added dropwise with an ethanol dispersion containing organosilicon benzotriazole compatibilizer under stirring at 55-65℃. After the addition was complete, the reaction was carried out for 20-24 h. After the reaction was completed, the modified multi-walled carbon nanotubes were obtained by filtration, washing and drying.

[0006] Preferably, the molar ratio of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole to acryloyl chloride is 1:1 to 1.2.

[0007] Preferably, the active hydrogen mass fraction in the hydrogen-containing silicone oil is 0.12~0.75%, and the viscosity is 20~30 Pa·s.

[0008] Preferably, the mass ratio of the double bond modified benzotriazole intermediate, the hydrogen-containing silicone oil, and the glycidyl methacrylate is 0.45~0.5:1:0.1~0.15.

[0009] Preferably, the preparation method of the hyperbranched triazine-based additive includes the following steps: (1) Add p-phenylenediamine and tetrahydrofuran to the reactor, heat to 40~60℃ under nitrogen atmosphere, stir and mix, add phenylphosphodichloride and continue to react for 4~6h. During the reaction, add triethylamine in batches to remove the generated hydrogen chloride. After the reaction is completed, filter, evaporate and dry to prepare the diamino phosphorus antioxidant. (2) Add diamino phosphorus antioxidant, triethylamine and acetonitrile to the reactor and stir to dissolve. Purge with nitrogen and control the solution temperature at 0~5℃. Then slowly drop the acetonitrile solution containing cyanuric chloride into the above solution. After the addition is complete, keep the reaction at 0~5℃ for 4~5h. Then move the reactor to an oil bath at 45~50℃ and reflux under nitrogen atmosphere for 4~5h. Then raise the temperature to 75~85℃ and continue the reaction for 6~8h. After the reaction is complete, filter, wash and dry to prepare hyperbranched triazine additive.

[0010] Preferably, the molar ratio of phenylphosphodichloride to p-phenylenediamine is 1:2.5.

[0011] Preferably, the molar ratio of the diamino phosphorus-containing antioxidant to cyanuric chloride is 1.5~1.6:1.

[0012] Preferably, the vulcanizing agent is one or more of dicumyl peroxide, bis(2,5)sulfide, di-tert-butyl peroxide, benzoyl peroxide, and cyclohexanone peroxide; and the lubricant is one or more of stearic acid, polyethylene wax, and oxidized polyethylene wax.

[0013] The preparation method of the silicone rubber sealing ring for capacitors as described above includes the following steps: weigh each component according to the weight parts, mix silicone rubber, modified multi-walled carbon nanotubes, hyperbranched triazine additives and lubricant for 3-5 minutes, then add vulcanizing agent and mix evenly, and place at 120-160℃ for 5-8 minutes to vulcanize, and the obtained rubber compound is extruded through a mold to prepare the silicone rubber sealing ring for capacitors.

[0014] The beneficial effects of this invention are: This invention utilizes a nucleophilic substitution reaction between 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and acryloyl chloride to prepare a double-bond modified benzotriazole intermediate. Then, using hydrogen-containing silicone oil, the double-bond modified benzotriazole intermediate, and glycidyl methacrylate as raw materials, under the action of a Karstedt catalyst, a hydrosilylation reaction is carried out to introduce the double-bond modified benzotriazole intermediate and glycidyl methacrylate into the polysiloxane molecular chain, thereby increasing the polar groups in the polysiloxane molecular chain. This synthesizes a long-chain organosilicon benzotriazole compatibilizer containing phenolic hydroxyl and oxygen-containing polar groups, which is then used to modify multi-walled carbon nanotubes (MWCs). Modified MWCs are obtained. This organosilicon benzotriazole compatibilizer significantly improves the dispersibility and compatibility of MWCs in a silicone rubber matrix, thereby enhancing the antistatic and mechanical properties of the rubber compound. Furthermore, the introduction of benzotriazole groups with good UV absorption into its structure endows the rubber compound with excellent UV aging resistance.

[0015] This invention utilizes a nucleophilic substitution reaction between phenylphosphoryl dichloride and p-phenylenediamine to prepare a bisamino phosphorus-containing antioxidant containing an anti-aging functional group -NH and flame-retardant phosphorus. Then, using the bisamino phosphorus-containing antioxidant and cyanuric chloride as monomers, a hyperbranched triazine-based additive is synthesized through a nucleophilic substitution reaction. This hyperbranched triazine-based additive introduces phosphorus and nitrogen flame-retardant elements and a rigid benzene ring structure into its molecule, exhibiting good thermal stability, compatibility, low viscosity, and high flame-retardant efficiency. Furthermore, the introduction of the -NH functional group with anti-aging properties into the molecule structure of the hyperbranched triazine-based additive imparts excellent heat and oxygen aging resistance to the adhesive. At the same time, it can effectively solve the problems of poor compatibility, uneven dispersion, and easy loss from the matrix between small molecule flame retardants or antioxidants and the matrix, thus giving the adhesive a long-lasting performance. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A method for preparing modified multi-walled carbon nanotubes includes the following steps: A. 11.4 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 7 mL of triethylamine were added to the reactor and stirred. Then, a mixed solution of 5.2 g of acryloyl chloride and 20 mL of tetrahydrofuran was added dropwise. The mixture was stirred in an ice bath for 8 h. The crude product was washed with saturated sodium bicarbonate solution, and the oily liquid on top was washed with anhydrous ethanol and dried to prepare the double bond modified benzotriazole intermediate. B. Add 20 mL of isopropanol, 9.4 g of double-bond modified benzotriazole intermediate, and 20 g of hydrogen-containing silicone oil to the reactor, heat to 60 °C and stir to mix. Then add 4 × 10⁻⁶ g of the total mass of the reaction system. -6 The Karstedt catalyst was further heated to 80°C and stirred for 3 hours, and then cooled to obtain an organosilicon benzotriazole derivative. C. Take 10 mL of isopropanol, 2.4 g of glycidyl methacrylate, and 2 × 10⁻⁶ glycidyl methacrylate as the total mass of the reaction system. -6 The Karstedt catalyst was stirred and mixed to obtain a dispersion, which was then slowly added dropwise to a reactor containing an organosilicon benzotriazole derivative. The temperature was raised to 60°C and the reaction was stirred for 3 hours. After the reaction was completed, activated carbon was added and stirred at 40°C for 2 hours to adsorb the residual catalyst. Finally, the organosilicon benzotriazole compatibilizer was prepared by filtration and vacuum distillation. D. After plasma treatment for 15 min, 2 g of multi-walled carbon nanotubes were dispersed in 100 mL of anhydrous ethanol and ultrasonically stirred for 0.5 h under ice-water bath conditions. Then, the multi-walled carbon nanotube dispersion was transferred to a reactor and slowly added dropwise under stirring at 60 °C. After the addition was completed, the reaction was carried out for 24 h. After the reaction was completed, the modified multi-walled carbon nanotubes were prepared by filtration, washing and drying.

[0018] Example 2: A method for preparing a hyperbranched triazine-based additive includes the following steps: (1) Add 5.4g p-phenylenediamine and 80mL tetrahydrofuran to the reactor, heat to 50°C under a nitrogen atmosphere, stir and mix, then add 3.8g phenylphosphine dichloride and continue the reaction for 5h. During the reaction, add 7mL triethylamine in batches to remove the generated hydrogen chloride. After the reaction is completed, filter, evaporate and dry to prepare a diamino phosphorus-containing antioxidant. (2) Add 5.6g of diamino phosphorus antioxidant, 5mL of triethylamine and 200mL of acetonitrile to the reactor and stir to dissolve. Purge with nitrogen and control the solution temperature at 0℃. Then slowly drop 40mL of acetonitrile solution containing 2g of cyanuric chloride into the above solution. After the addition is completed, keep the reaction at 0℃ for 4h. Then move the reactor to a 50℃ oil bath and reflux under nitrogen atmosphere for 4h. Then raise the temperature to 80℃ and continue the reaction for 7h. After the reaction is completed, filter, wash and dry to prepare hyperbranched triazine additive.

[0019] Example 3 A silicone rubber sealing ring for capacitors, comprising the following components by weight: 100 parts silicone rubber, 5.3 parts modified multi-walled carbon nanotubes prepared in Example 1, 2.2 parts hyperbranched triazine-based additives prepared in Example 2, 1.1 parts dicumyl peroxide vulcanizing agent, and 0.3 parts stearic acid lubricant.

[0020] The above-mentioned method for preparing silicone rubber sealing rings for capacitors includes the following steps: weighing each component according to the weight parts, mixing silicone rubber, modified multi-walled carbon nanotubes, hyperbranched triazine additives and lubricants for 3 minutes, then adding vulcanizing agent and mixing evenly, and placing it at 155°C for 6 minutes for vulcanization, and extruding the obtained rubber compound through a mold to prepare silicone rubber sealing rings for capacitors.

[0021] Example 4 A silicone rubber sealing ring for capacitors, comprising the following components by weight: 100 parts silicone rubber, 8.6 parts modified multi-walled carbon nanotubes prepared in Example 1, 3.4 parts hyperbranched triazine-based additives prepared in Example 2, 1.7 parts dicumyl peroxide vulcanizing agent, and 0.5 parts stearic acid lubricant.

[0022] The preparation method of the silicone rubber sealing ring for the capacitor is the same as in Example 3.

[0023] Example 5 A silicone rubber sealing ring for capacitors, comprising the following components by weight: 100 parts silicone rubber, 10.7 parts modified multi-walled carbon nanotubes prepared in Example 1, 4.4 parts hyperbranched triazine-based additives prepared in Example 2, 2.6 parts dicumyl peroxide vulcanizing agent, and 0.7 parts stearic acid lubricant.

[0024] The preparation method of the silicone rubber sealing ring for the capacitor is the same as in Example 3.

[0025] Comparative Example 1: A method for preparing a hyperbranched triazine-based additive includes the following steps: 1.7 g of p-phenylenediamine, 5 mL of triethylamine, and 200 mL of acetonitrile were added to the reactor and stirred to dissolve. Nitrogen gas was introduced and the solution temperature was controlled at 0 °C. Then, 40 mL of acetonitrile solution containing 2 g of cyanuric chloride was slowly added dropwise to the above solution. After the addition was completed, the reaction was maintained at 0 °C for 4 h. The reactor was then transferred to a 50 °C oil bath and refluxed under a nitrogen atmosphere for 4 h. Subsequently, the temperature was raised to 80 °C and the reaction was continued for 7 h. After the reaction was completed, the mixture was filtered, washed, and dried to prepare the hyperbranched triazine-based additive.

[0026] Comparative Example 2 A silicone rubber sealing ring for a capacitor, comprising the following components in parts by weight: 100 parts silicone rubber, 10.7 parts multi-walled carbon nanotubes, 4.4 parts hyperbranched triazine-based additive prepared in Example 2, 2.6 parts dicumyl peroxide vulcanizing agent, and 0.7 parts stearic acid lubricant.

[0027] The preparation method of the silicone rubber sealing ring for the capacitor is the same as in Example 3.

[0028] Comparative Example 3 A silicone rubber sealing ring for a capacitor, comprising the following components by weight: 100 parts silicone rubber, 10.7 parts modified multi-walled carbon nanotubes prepared in Example 1, 4.4 parts hyperbranched triazine-based additive prepared in Comparative Example 1, 2.6 parts dicumyl peroxide vulcanizing agent, and 0.7 parts stearic acid lubricant.

[0029] The preparation method of the silicone rubber sealing ring for the capacitor is the same as in Example 3.

[0030] Comparative Example 4 A silicone rubber sealing ring for a capacitor, comprising the following components by weight: 100 parts silicone rubber, 10.7 parts modified multi-walled carbon nanotubes prepared in Example 1, 2.6 parts dicumyl peroxide vulcanizing agent, and 0.7 parts stearic acid lubricant.

[0031] The preparation method of the silicone rubber sealing ring for the capacitor is the same as in Example 3.

[0032] Performance testing The performance of the silicone rubber sealing rings prepared in Examples 3-5 and Comparative Examples 2-4 was tested: (1) Antistatic performance test: Volume resistivity and surface resistance were tested using a high resistance meter. The sample size was 100mm×100mm×2mm. The data results are shown in Table 1.

[0033] (2) Flame retardant performance test: The flame retardant performance was tested using the limiting oxygen index. The sample size was 130mm×6.5mm×3.2mm. The data results are shown in Table 1.

[0034] Table 1. Test results of antistatic and flame retardant properties of the samples.

[0035] As can be seen from the data in Table 1, the silicone rubber sealing rings prepared in Examples 3-5 of this invention possess good antistatic and flame-retardant properties. In Comparative Example 2, no modification treatment was performed on the multi-walled carbon nanotubes, yet its measured surface resistance and volume resistivity increased compared to Examples 3-5. This is because the organosilicon benzotriazole compatibilizer improved the compatibility between the multi-walled carbon nanotubes and the silicone rubber matrix, as well as the dispersion effect of the multi-walled carbon nanotubes, through surface modification, further promoting the construction of the conductive network. Comparative Example 3 did not introduce flame-retardant phosphorus, and Comparative Example 4 did not add hyperbranched triazine-based additives. The measured limiting oxygen index in Comparative Examples 3-4 was lower than that in Examples 3-5, and the decrease was more significant in Comparative Example 4 than in Comparative Example 3, indicating that the introduction of hyperbranched triazine-based additives is beneficial for improving the flame-retardant properties of the materials.

[0036] (3) Mechanical property test: The tensile strength and elongation at break were tested in accordance with GB / T 528-2009. The speed of the clamp during the stretching was 500 mm / min. The data results are shown in Table 2.

[0037] (4) UV aging resistance test: After the sample was irradiated with a 40W UV lamp at 60℃ for a total of 72h, the change rate of its tensile strength and elongation at break was tested. The distance between the sample and the lamp tube was 254mm. The data results are shown in Table 2.

[0038] (5) Test of heat and oxygen aging resistance: After aging the sample in a 110℃ heat and oxygen aging chamber for 168h, the change rate of its tensile strength and elongation at break was tested. The data results are shown in Table 2.

[0039] Table 2. Test results of mechanical properties and aging resistance of the samples

[0040] As can be seen from the data in Table 2, the silicone rubber sealing rings prepared in Examples 3-5 of this invention possess good mechanical properties, UV aging resistance, and thermo-oxidative aging resistance. The tensile strength and elongation at break in Comparative Example 2 were found to be lower than those in Examples 3-5. This is because the aggregation of multi-walled carbon nanotubes led to a decrease in mechanical properties. Furthermore, the changes in tensile strength and elongation at break after UV aging were significantly different from those in Examples 3-5. This is because the absence of benzotriazole groups resulted in reduced UV aging resistance. The changes in tensile strength and elongation at break in Comparative Example 3 after thermo-oxidative aging were significantly different from those in Examples 3-5. This is because the diamino phosphorus-containing antioxidant can form more anti-aging functional groups (-NH) than p-phenylenediamine, thus improving the thermo-oxidative aging resistance of the material to some extent. The thermo-oxidative aging resistance in Comparative Example 4 was even more significantly lower than that in Examples 3-5, indicating that the introduction of hyperbranched triazine additives can greatly improve the thermo-oxidative aging resistance of the material.

[0041] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A silicone rubber sealing ring for capacitors, characterized in that, It comprises the following components by weight: 100 parts silicone rubber, 5-12 parts modified multi-walled carbon nanotubes, 2-5 parts hyperbranched triazine-based additives, 1-3 parts vulcanizing agent, and 0.3-1 parts lubricant; The modified multi-walled carbon nanotubes are prepared by modifying multi-walled carbon nanotubes with an organosilicon benzotriazole compatibilizer. The organosilicon benzotriazole compatibilizer is prepared by introducing a double-bond modified benzotriazole intermediate and glycidyl methacrylate into the molecular chain of hydrogen-containing silicone oil through a hydrosilylation reaction. The double-bond modified benzotriazole intermediate is prepared by substitution of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole with acryloyl chloride. The hyperbranched triazine-based additive is prepared by a nucleophilic substitution reaction between phenylphosphine dichloride and p-phenylenediamine to obtain a bisamino phosphorus-containing antioxidant, which is then used as a monomer and cyanuric chloride to produce the additive through a nucleophilic substitution reaction.

2. The silicone rubber sealing ring for capacitors according to claim 1, characterized in that, The method for preparing the modified multi-walled carbon nanotubes includes the following steps: A. Add 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and triethylamine to the reactor and stir to mix. Then add a mixed solution of acryloyl chloride and tetrahydrofuran dropwise. Stir the reaction under ice bath conditions for 7-9 hours. Wash the crude product with saturated sodium bicarbonate solution. Wash the oily liquid on the top with anhydrous ethanol and dry to prepare the double bond modified benzotriazole intermediate. B. Add isopropanol, double bond modified benzotriazole intermediate and hydrogen-containing silicone oil to the reactor, heat to 55~70℃ and stir to mix, then add Karstedt catalyst, further heat to 75~85℃ and stir to react for 3~4h, cool to obtain organosilicon benzotriazole derivative. C. Take isopropanol, glycidyl methacrylate and Karstedt catalyst, stir and mix to obtain a dispersion, slowly add the dispersion dropwise to a reactor containing organosilicon benzotriazole derivative, heat to 55~70℃ and stir for 2~3h. After the reaction is completed, add activated carbon and stir at 40℃ for 2h to adsorb the residual catalyst. Finally, filter and distill under reduced pressure to prepare organosilicon benzotriazole compatibilizer. D. Multi-walled carbon nanotubes were plasma-treated for 15 min and then dispersed in anhydrous ethanol. The dispersion was ultrasonically stirred for 0.5 h under ice-water bath conditions. The dispersion was then transferred to a reactor and slowly added dropwise with an ethanol dispersion containing organosilicon benzotriazole compatibilizer under stirring at 55-65℃. After the addition was complete, the reaction was carried out for 20-24 h. After the reaction was completed, the modified multi-walled carbon nanotubes were obtained by filtration, washing and drying.

3. The silicone rubber sealing ring for capacitors according to claim 2, characterized in that, The molar ratio of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole to acryloyl chloride is 1:1~1.

2.

4. The silicone rubber sealing ring for capacitors according to claim 2, characterized in that, The hydrogen-containing silicone oil has an active hydrogen mass fraction of 0.12~0.75% and a viscosity of 20~30 Pa·s.

5. The silicone rubber sealing ring for capacitors according to claim 2, characterized in that, The mass ratio of the double-bond modified benzotriazole intermediate, the hydrogen-containing silicone oil, and the glycidyl methacrylate is 0.45~0.5:1:0.1~0.

15.

6. The silicone rubber sealing ring for capacitors according to claim 1, characterized in that, The preparation method of the hyperbranched triazine-based additive includes the following steps: (1) Add p-phenylenediamine and tetrahydrofuran to the reactor, heat to 40~60℃ under nitrogen atmosphere, stir and mix, add phenylphosphodichloride and continue to react for 4~6h. During the reaction, add triethylamine in batches to remove the generated hydrogen chloride. After the reaction is completed, filter, evaporate and dry to prepare the diamino phosphorus antioxidant. (2) Add diamino phosphorus antioxidant, triethylamine and acetonitrile to the reactor and stir to dissolve. Purge with nitrogen and control the solution temperature at 0~5℃. Then slowly drop the acetonitrile solution containing cyanuric chloride into the above solution. After the addition is complete, keep the reaction at 0~5℃ for 4~5h. Then move the reactor to an oil bath at 45~50℃ and reflux under nitrogen atmosphere for 4~5h. Then raise the temperature to 75~85℃ and continue the reaction for 6~8h. After the reaction is complete, filter, wash and dry to prepare hyperbranched triazine additive.

7. The silicone rubber sealing ring for capacitors according to claim 6, characterized in that, The molar ratio of phenylphosphodichloride to p-phenylenediamine is 1:2.

5.

8. The silicone rubber sealing ring for capacitors according to claim 6, characterized in that, The molar ratio of the diamino phosphorus-containing antioxidant to cyanuric chloride is 1.5~1.6:

1.

9. The silicone rubber sealing ring for capacitors according to claim 1, characterized in that, The vulcanizing agent is one or more of dicumyl peroxide, bis(2,5)sulfide, di-tert-butyl peroxide, benzoyl peroxide, and cyclohexanone peroxide; the lubricant is one or more of stearic acid, polyethylene wax, and oxidized polyethylene wax.

10. A method for preparing a silicone rubber sealing ring for a capacitor according to any one of claims 1 to 9, characterized in that, Includes the following steps: Weigh each component according to the weight parts, mix silicone rubber, modified multi-walled carbon nanotubes, hyperbranched triazine additives and lubricant for 3-5 minutes, then add vulcanizing agent and mix evenly, and place at 120-160℃ for 5-8 minutes. The resulting rubber compound is extruded through a mold to prepare silicone rubber sealing rings for capacitors.

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