Insulating rubber material for capacitor and preparation method thereof

Abstract

The present invention relates to the technical field of insulating rubber composite materials, and in particular to an insulating rubber material for capacitors and a preparation method thereof. The present invention provides an insulating rubber material for capacitors, comprising the following raw materials in parts by weight: 80-120 parts of a base material, 40-60 parts of modified silica, 3-5 parts of zinc oxide, 1-2 parts of stearic acid, 10-20 parts of modified carbon black, 1-3 parts of a vulcanizing agent, and 0.5-1 part of an accelerator. This material addresses the problem of rubber swelling causing deformation of the product's appearance and deterioration of its sealing performance, while maintaining good mechanical properties and aging resistance to meet the needs of immersion capacitors for use in extreme environments. By using a mixture of fluorosilicone rubber and silicone rubber as the base material and a chitosan / carbon black / tin antimony oxide composite material as the modified carbon black, the mechanical properties, oil resistance, aging resistance, environmental adaptability, and electrical insulation properties of the rubber material are synergistically enhanced. The resulting rubber material is less susceptible to swelling after being immersed in mineral oil.

Description

Technical Field

[0001] The present invention relates to the technical field of insulating rubber composite materials, and in particular to an insulating rubber material for capacitors and a preparation method thereof. Background Art

[0002] With the rapid development of big data and AI servers, the heat dissipation requirements for capacitors are becoming increasingly stringent. Existing capacitor insulation materials are prone to swelling when immersed in mineral oil, causing deformation in the product's appearance and affecting the performance and service life of the capacitor. Therefore, developing a mineral oil-swelling-resistant insulating rubber sheet for capacitors is of great practical significance.

[0003] Fluororubber is widely used in capacitor sealing materials due to its excellent oil resistance, high temperature resistance, and chemical corrosion resistance. Chinese patent CN103772858A discloses a fluororubber capacitor gasket and its preparation method. Using fluororubber as the base rubber, the resulting gasket exhibits good oil resistance. However, due to fluororubber's poor mechanical and radiation resistance, especially below -20°C, its elasticity and flexibility significantly decrease. This poor mechanical performance leads to reduced sealing performance. Prolonged exposure to radiation also leads to a decrease in mechanical properties due to poor radiation resistance. Furthermore, fluororubber has poor processing properties, making it difficult to process and expensive to use, making it unsuitable for widespread use. Chinese patent CN104292841A discloses a high-insulation, mixed silicone rubber gasket specifically for metal film capacitors. Using methyl vinyl rubber as the base rubber, it exhibits excellent insulation, mechanical, and processing properties. However, its solvent and aging resistance are poor, and it easily swells and deforms when immersed in mineral oil. It also ages rapidly at high temperatures, resulting in poor mechanical properties.

[0004] Based on this, there is an urgent need for an insulating rubber material for capacitors that can maintain stable physical properties when immersed in mineral oil, avoid the problems of product appearance deformation and deterioration of sealing performance due to swelling, and maintain good mechanical properties and aging resistance to meet the needs of immersion capacitors for extreme environments. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides an insulating rubber material for capacitors, which comprises the following raw materials in parts by weight: 80 to 120 parts of a base material, 40 to 60 parts of modified silica, 3 to 5 parts of zinc oxide, 1 to 2 parts of stearic acid, 10 to 20 parts of modified carbon black, 1 to 3 parts of a vulcanizing agent, and 0.5 to 1 part of an accelerator.

[0006] Wherein, the base material is a mixture of fluorosilicone rubber and methyl vinyl silicone rubber.

[0007] The present invention uses fluorosilicone rubber and methyl vinyl silicone rubber in combination. Fluorosilicone rubber has good oil resistance, solvent resistance, chemical corrosion resistance and other properties, which makes the insulating rubber material have good resistance to mineral oil swelling in capacitor applications. However, the mechanical strength of fluorosilicone rubber, especially the tear strength, is relatively low. By using it in combination with silicone rubber, the mechanical strength of the composite material can be significantly improved. In addition, due to the introduction of trifluoropropyl groups, the vulcanization of fluorosilicone rubber is more difficult. Using it in combination with silicone rubber can simplify the vulcanization process and improve the performance of the rubber. At the same time, although fluorosilicone rubber has good low-temperature performance, when combined with silicone rubber, it can further improve the performance of the composite material in extreme low-temperature environments. In addition, both fluorosilicone rubber and silicone rubber have good weather resistance and can resist the effects of ultraviolet rays, ozone and climate change. Using them together can make the material perform better in outdoor and long-term exposure applications.

[0008] Furthermore, the weight ratio of the fluorosilicone rubber to the methyl vinyl silicone rubber is (2-5):1.

[0009] As a preferred technical solution, the modified silica is one of modified fumed silica and modified precipitated silica.

[0010] Furthermore, the modifier used for the modified silica is one or more of KH550, KH560, KH570, 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane.

[0011] Furthermore, the 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane is prepared by condensing trifluoropropylmethyldimethoxysilane under acid catalysis; the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is prepared by ring-opening reaction of 2,4,6-trimethyl-2,4,6-tritrifluoropropylcyclotrisiloxane under acid initiation and end-capping with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane; the weight-average molecular weight of the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is 500 to 2000 Da.

[0012] Furthermore, the method for modifying silica using the 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane includes the following steps: stirring and mixing the modifier and silica in a weight ratio of (5-15):100, heating and reacting at 100-140°C for 12-24 hours to obtain modified silica.

[0013] The methods of modifying white carbon black using silane coupling agents such as KH550, KH560, and KH570 are all prior arts and will not be described in detail in the present invention.

[0014] As a preferred technical solution, the modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

[0015] Furthermore, the preparation method of the chitosan / carbon black / antimony tin oxide composite material includes: dissolving chitosan in an acetic acid aqueous solution, then adding carbon black and antimony tin oxide, and ultrasonically treating for 2 to 4 hours until the suspension is uniform; then centrifuging and drying at 45 to 50° C. for 24 to 48 hours.

[0016] Carbon black, a commonly used reinforcing agent, can significantly improve the tensile strength, tear strength, and abrasion resistance of rubber. Carbon black particles form physical crosslinks within the rubber matrix, increasing the rubber's strength and toughness. Chitosan's molecular chains can form physical or chemical bonds with rubber molecules, enhancing the rubber's strength and toughness. Antimony tin oxide, an inorganic filler with excellent oil resistance, can improve the rubber's resistance to mineral oil swelling, maintaining stable physical properties in mineral oil environments, and contributing to improved appearance and aging resistance. Antimony tin oxide's UV absorption properties also help reduce the aging effects of prolonged UV exposure on rubber.

[0017] Chitosan, carbon black, and antimony tin oxide work synergistically, not only maintaining their inherent properties but also interacting with each other through their combined properties. The flexibility of chitosan, the rigidity of carbon black, and the oil and aging resistance of antimony tin oxide combine to create a strong toughening effect in rubber. The modification of carbon black with chitosan and antimony tin oxide also improves its electrical insulation properties. This further enhances the rubber's mechanical properties, including tensile strength, tear strength, impact strength, and wear resistance. It also significantly improves its oil resistance, aging resistance, environmental adaptability, and electrical insulation, making it an ideal material choice, particularly for applications requiring extremely high performance, such as capacitor gaskets in extreme environments.

[0018] Furthermore, the viscosity average molecular weight of the chitosan is 190,000-310,000 Da.

[0019] Furthermore, the particle size of the antimony tin oxide is less than 50 nanometers. The smaller particle size makes it more dispersible in the rubber and can more effectively block the penetration of oil molecules, thereby improving the oil resistance of the rubber.

[0020] As a preferred technical solution, the vulcanizing agent is one or more of diisopropyl benzene peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-bis-tert-butylperoxydiisopropylbenzene, tert-butyl perbenzoate or 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne.

[0021] As a preferred technical solution, the accelerator is one or more of accelerator TMTD, accelerator TMTM, accelerator DCP or accelerator DZ.

[0022] In order to prepare the insulating rubber material for capacitors, the present invention also provides a method for preparing the insulating rubber material for capacitors, comprising the following steps:

[0023] (1) Weigh the above raw materials according to weight fraction;

[0024] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 30-40° C., and mixing them for 30-60 minutes to obtain a mixed rubber material;

[0025] (3) Place the mixed rubber material into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 50-60°C and continue mixing for 30-50 minutes;

[0026] (4) After the rubber compound is mixed, it is left for 18 to 24 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added at 45 to 50 ° C. and fully mixed for 2 to 4 hours before being taken out.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The present invention provides an insulating rubber for capacitors and a preparation method thereof. By using a mixture of fluorosilicone rubber and silicone rubber as a base material, the insulating rubber material is improved in resistance to mineral oil swelling while ensuring the high and low temperature resistance, mechanical properties, and aging resistance of the composite material.

[0029] 2. The modified silica used in the present invention has good compatibility with the rubber base material and is evenly dispersed, thereby improving the processing performance of the composite material and further enhancing the mechanical properties of the rubber material;

[0030] 3. The present invention adopts a chitosan / carbon black / antimony tin oxide composite material as modified carbon black. The synergistic effect of the three significantly enhances the mechanical properties, oil resistance, aging resistance, environmental adaptability and electrical insulation properties of the rubber material. After the obtained rubber material is soaked in mineral oil, the physical properties (hardness, volume) change little and it is not easy to swell. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the examples. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. The embodiments described below are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0033] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0034] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0035] In order to ensure that the insulating rubber material used for capacitors can maintain stable physical properties when immersed in mineral oil, avoid the problems of product appearance deformation and deterioration of sealing performance due to swelling, and maintain good high and low temperature performance and aging resistance to meet the needs of capacitors for extreme environments, this embodiment provides an insulating rubber material for capacitors, the raw materials of which include the following parts by weight: 80-120 parts of base material, 40-60 parts of modified white carbon black, 3-5 parts of zinc oxide, 1-2 parts of stearic acid, 10-20 parts of modified carbon black, 1-3 parts of vulcanizing agent, and 0.5-1 part of accelerator.

[0036] Wherein, the base material is a mixture of fluorosilicone rubber and methyl vinyl silicone rubber.

[0037] The present invention uses fluorosilicone rubber and methyl vinyl silicone rubber in combination, so that the insulating rubber material has good mineral oil swelling resistance, mechanical strength, performance, high and low temperature performance and weather resistance in capacitor applications.

[0038] As a preferred embodiment, the weight ratio of the fluorosilicone rubber to the methyl vinyl silicone rubber is (2-5):1.

[0039] As a preferred embodiment, the modified silica is one of modified fumed silica and modified precipitated silica.

[0040] As a preferred embodiment, the modifier used for the modified silica is one or more of KH550, KH560, KH570, 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane.

[0041] The 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane is prepared by condensing trifluoropropylmethyldimethoxysilane under acid catalysis; the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is prepared by ring-opening reaction of 2,4,6-trimethyl-2,4,6-tritrifluoropropylcyclotrisiloxane under acid initiation and end-capping with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane; the weight-average molecular weight of the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is 500 to 2000 Da.

[0042] Among them, the method for modifying silica using the 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane includes the following steps: stirring and mixing the modifier and silica in a weight ratio of (5-15):100, heating and reacting at 100-150°C for 12-24 hours to obtain modified silica.

[0043] The methods of modifying white carbon black using silane coupling agents such as KH550, KH560, and KH570 are all prior arts and will not be described in detail in the present invention.

[0044] As a preferred embodiment, the modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

[0045] The preparation method of the chitosan / carbon black / antimony tin oxide composite material comprises: dissolving chitosan in a 1% to 5% (v / v) acetic acid aqueous solution, then adding carbon black and antimony tin oxide, and ultrasonically treating for 2 to 4 hours until the suspension is uniform; then centrifuging and drying at 45 to 50° C. for 24 to 48 hours to obtain the composite material.

[0046] The synergistic effect of chitosan, carbon black and antimony tin oxide can further enhance the mechanical properties of rubber, such as tensile strength, tear strength, impact strength and wear resistance. It also significantly enhances its oil resistance, aging resistance, environmental adaptability and electrical insulation properties, making it an ideal material choice, especially in applications with extremely high material performance requirements, such as capacitor gaskets in extreme environments.

[0047] As a preferred embodiment, the chitosan has a viscosity-average molecular weight of 190,000-310,000 Da and is purchased from Sigma.

[0048] As a preferred embodiment, the particle size of the antimony tin oxide is less than 50 nanometers. The smaller particle size makes it more dispersible in the rubber and can more effectively block the penetration of oil molecules, thereby improving the oil resistance of the rubber.

[0049] As a preferred embodiment, the vulcanizing agent is a peroxide vulcanizing agent, and the peroxide vulcanizing agent is one or more of dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-bis-tert-butylperoxydiisopropylbenzene, tert-butyl peroxybenzoate or 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne.

[0050] As a preferred embodiment, the accelerator is one or more of accelerator TMTD, accelerator TMTM, accelerator DCP or accelerator DZ.

[0051] In order to prepare the above-mentioned insulating rubber material for capacitors, this embodiment further provides a method for preparing the insulating rubber material for capacitors, comprising the following steps:

[0052] (1) Weigh the above raw materials according to weight fraction;

[0053] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 30-40° C., and mixing them for 30-60 minutes to obtain a mixed rubber material;

[0054] (3) Place the mixed rubber material into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 50-60°C and continue mixing for 30-50 minutes;

[0055] (4) After the rubber compound is mixed, it is left for 18 to 24 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added at 45 to 50 ° C. and fully mixed for 2 to 4 hours before being taken out.

[0056] This embodiment provides an insulating rubber for capacitors and a preparation method thereof, which uses a mixture of fluorosilicone rubber and silicone rubber as a base material. While increasing the insulating rubber material's resistance to mineral oil swelling, it also ensures the composite material's resistance to high and low temperatures, mechanical properties, and aging resistance. The modified silica used has good compatibility with the rubber base material and is evenly dispersed, which improves the processing performance of the composite material and further enhances the mechanical properties of the rubber material. A chitosan / carbon black / antimony tin oxide composite material is used as the modified carbon black. The synergistic effect of the three significantly enhances the mechanical properties, oil resistance, aging resistance, environmental adaptability, and electrical insulation properties of the rubber material. After the obtained rubber material is immersed in mineral oil, the physical properties (hardness, volume) change little and it is not prone to swelling.

[0057] In order to better illustrate the effect of the technical solution in this embodiment, the following specific examples are provided for illustration:

[0058] Example 1

[0059] Disclosed is an insulating rubber material for capacitors. The raw materials thereof comprise the following parts by weight: 80 parts of a base material, 40 parts of modified white carbon black, 3 parts of zinc oxide, 1 part of stearic acid, 15 parts of modified carbon black, 1 part of a vulcanizing agent, and 0.5 part of an accelerator.

[0060] The base material is a mixture of 60 parts of fluorosilicone rubber and 20 parts of methyl vinyl silicone rubber.

[0061] Wherein, the modified silica is KH550 modified fumed silica.

[0062] Wherein, the modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

[0063] The method for preparing the insulating rubber material for capacitors described in this embodiment includes the following steps:

[0064] (1) Weigh the above raw materials according to weight fraction;

[0065] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 30° C., and mixing them for 60 minutes to obtain a mixed rubber material;

[0066] (3) Place the mixed rubber material into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 50°C and continue mixing for 50 minutes;

[0067] (4) After the rubber compound is mixed, it is left for 18 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added and fully mixed at 45°C for 4 hours before being taken out.

[0068] The preparation method of the chitosan / carbon black / antimony tin oxide composite material includes: dissolving 5g of chitosan in 1200ml of 1% (v / v) acetic acid aqueous solution, then adding 1.5mg of carbon black and 1g of antimony tin oxide, ultrasonically treating for 2h until the suspension is uniform, then centrifuging, and drying at 45°C for 48h.

[0069] Example 2

[0070] Disclosed is an insulating rubber material for capacitors. The raw materials thereof comprise the following parts by weight: 100 parts of a base material, 60 parts of modified white carbon black, 5 parts of zinc oxide, 2 parts of stearic acid, 10 parts of modified carbon black, 2 parts of a vulcanizing agent, and 0.8 parts of an accelerator.

[0071] The base material is a mixture of 70 parts of fluorosilicone rubber and 30 parts of methyl vinyl silicone rubber.

[0072] Wherein, the modified silica is KH560 modified fumed silica.

[0073] Wherein, the modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

[0074] The method for preparing the insulating rubber material for capacitors described in this embodiment includes the following steps:

[0075] (1) Weigh the above raw materials according to weight fraction;

[0076] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 35° C., and mixing them for 50 minutes to obtain a mixed rubber material;

[0077] (3) Place the mixed rubber material into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 55°C and continue mixing for 40 minutes;

[0078] (4) After the rubber compound is mixed, it is left for 24 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added and fully mixed at 45°C for 3 hours before being taken out.

[0079] The preparation method of the chitosan / carbon black / antimony tin oxide composite material includes: dissolving 4g of chitosan in 800ml of 1.5% (v / v) acetic acid aqueous solution, then adding 1.0g of carbon black and 0.5g of antimony tin oxide, ultrasonically treating for 3h until the suspension is uniform, then centrifuging, and drying at 50°C for 24h.

[0080] Example 3

[0081] Disclosed is an insulating rubber material for capacitors. The raw materials thereof comprise the following parts by weight: 120 parts of a base material, 50 parts of modified white carbon black, 4 parts of zinc oxide, 1.5 parts of stearic acid, 20 parts of modified carbon black, 3 parts of a vulcanizing agent, and 1 part of an accelerator.

[0082] The base material is a mixture of 100 parts of fluorosilicone rubber and 20 parts of methyl vinyl silicone rubber.

[0083] Wherein, the modified silica is KH570 modified precipitated silica.

[0084] Wherein, the modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

[0085] The method for preparing the insulating rubber material for capacitors described in this embodiment includes the following steps:

[0086] (1) Weigh the above raw materials according to weight fraction;

[0087] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 40° C., and mixing them for 60 minutes to obtain a mixed rubber material;

[0088] (3) Place the mixed rubber material into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 60°C and continue mixing for 50 minutes;

[0089] (4) After the rubber compound is mixed, it is left for 24 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added and fully mixed at 50°C for 3 hours before being taken out.

[0090] The preparation method of the chitosan / carbon black / antimony tin oxide composite material includes: dissolving 5g of chitosan in 1000ml of 2% (v / v) acetic acid aqueous solution, then adding 2g of carbon black and 0.8g of antimony tin oxide, ultrasonically treating for 4h until the suspension is uniform, then centrifuging, and drying at 45°C for 36h.

[0091] Example 4

[0092] This embodiment is based on Example 1, and the only difference from Example 1 is that the modified silica described in this embodiment is 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane-modified fumed silica.

[0093] The preparation method of the modified silica comprises the following steps: mixing the modifier 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane and fumed silica in a weight ratio of 10:100, and heating the mixture at 120° C. for 16 hours.

[0094] Example 5

[0095] This embodiment is based on Example 1, and the only difference from Example 1 is that the modified silica described in this embodiment is α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane-modified fumed silica.

[0096] The α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is prepared by acid-induced ring-opening reaction of 2,4,6-trimethyl-2,4,6-tritrifluoropropylcyclotrisiloxane and end-capping with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane; the weight-average molecular weight of the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is approximately 1200 Da.

[0097] The preparation method of the modified silica comprises the following steps: mixing the modifier, ω-vinyl-terminated methyltrifluoropropyl oligosiloxane and fumed silica in a weight ratio of 10:100, and heating the mixture at 150° C. for 24 hours.

[0098] Comparative Example 1

[0099] This comparative example is based on Example 1, and differs from Example 1 only in that this comparative example uses unmodified carbon black to replace the chitosan / carbon black / antimony tin oxide composite material in Example 1.

[0100] Comparative Example 2

[0101] This comparative example is based on Example 1, and differs from Example 1 only in that the modified carbon black in this comparative example is chitosan-modified carbon black, that is, chitosan-modified carbon black is used in this comparative example to replace the chitosan / carbon black / antimony tin oxide composite material in Example 1.

[0102] The preparation method of the chitosan-modified carbon black comprises: dissolving 5 g of chitosan in 1200 ml of 1% (v / v) acetic acid aqueous solution, then adding 1.5 mg of carbon black, ultrasonically treating for 2 h until the suspension is uniform, then centrifuging, and drying at 45° C. for 48 h.

[0103] Comparative Example 3

[0104] This comparative example is based on Example 1, and differs from Example 1 only in that: in this comparative example, no chitosan / carbon black / antimony tin oxide composite material was prepared. Instead, chitosan, carbon black, and antimony tin oxide were added simultaneously during the preparation of the rubber material according to the raw material dosage ratio in the preparation method of the chitosan / carbon black / antimony tin oxide composite material described in Example 1.

[0105] The method for preparing the insulating rubber material for capacitors described in this embodiment includes the following steps:

[0106] (1) Weigh the above raw materials according to weight fraction;

[0107] (2) adding the base material, stearic acid and modified carbon black into an open mill and mixing them, heating them to 40° C., and mixing them for 60 minutes to obtain a mixed rubber material;

[0108] (3) The mixed rubber material was placed in an internal mixer, and after adding zinc oxide, chitosan, carbon black, and antimony tin oxide were added simultaneously. The mixture was then heated to 60°C and mixed for 50 minutes.

[0109] (4) After the rubber compound is mixed, it is left for 24 hours, then returned to the mixing mill, and vulcanizing agent and accelerator are added and fully mixed at 50°C for 3 hours before being taken out.

[0110] Comparative Example 4

[0111] This comparative example is based on Example 1, and the only difference from Example 1 is that the base material used in this comparative example is 80 parts of fluorosilicone rubber, and methyl vinyl silicone rubber is not used.

[0112] Comparative Example 5

[0113] This comparative example is based on Example 1, and the only difference from Example 1 is that the base material used in this comparative example is 80 parts of methyl vinyl silicone rubber, and fluorosilicone rubber is not used.

[0114] Comparative Example 6

[0115] This comparative example is based on Example 1, and the only difference from Example 1 is that this comparative example uses an equal amount of unmodified fumed silica to replace the KH550 modified fumed silica in Example 1.

[0116] The mechanical properties, aging resistance and oil resistance of the insulating rubber materials prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0117] Aging Resistance Test: The prepared insulating rubber material was treated at 100°C for 72 hours and then removed from the test. The change in tensile strength, elongation at break, and Shore hardness before and after the aging test was measured. The change in each property was calculated as (post-aging performance value - corresponding initial performance value) / corresponding initial performance value × 100%.

[0118] Oil Resistance Test: Identical specimens of the prepared insulating rubber material were prepared and immersed in 20# engine oil at 100°C for 48 hours. The changes in tensile strength, elongation at break, Shore hardness, and volume before and after oil immersion were measured. The change in each property was calculated as (post-oil immersion performance value - corresponding initial performance value) / corresponding initial performance value × 100%.

[0119] Table 1 Insulation rubber material performance test results

[0120]

[0121]

[0122] The data from Examples 1-5 demonstrate that the insulating rubber materials for capacitors prepared according to the present invention exhibit excellent mechanical properties, aging resistance, and oil resistance. The loss of mechanical properties and the degree of deformation when immersed in mineral oil are significantly lower than those of the comparative example. Examples 4-5 exhibit significantly superior mechanical properties, aging resistance, and oil resistance, demonstrating that silica modified with siloxanes containing fluorine and silicon structures can improve these properties of insulating rubber materials. The α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane used in Example 5 demonstrates the most significant improvement in these properties.

[0123] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An insulating rubber material for a capacitor, characterized in that: The invention comprises the following raw materials in parts by weight: 80-120 parts of base material, 40-60 parts of modified white carbon black, 3-5 parts of zinc oxide, 1-2 parts of stearic acid, 10-20 parts of modified carbon black, 1-3 parts of vulcanizing agent, and 0.5-1 part of accelerator; Wherein, the base material is a mixture of fluorosilicone rubber and methyl vinyl silicone rubber; The modified carbon black is a chitosan / carbon black / antimony tin oxide composite material, and its preparation method includes: dissolving chitosan in an acetic acid aqueous solution, then adding carbon black and antimony tin oxide, and ultrasonically treating for 2 to 4 hours until the suspension is uniform; then centrifuging and drying at 45 to 50°C for 24 to 48 hours.

2. The insulating rubber material for capacitors according to claim 1, characterized in that: The weight ratio of the fluorosilicone rubber to the methyl vinyl silicone rubber is (2-5):

1.

3. The insulating rubber material for capacitors according to claim 2, characterized in that: The modified silica is one of modified fumed silica and modified precipitated silica.

4. The insulating rubber material for capacitors according to claim 3, characterized in that: The modifier used for modifying white carbon black is one or more of 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane.

5. The insulating rubber material for capacitors according to claim 4, characterized in that: The 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane is prepared by condensing trifluoropropylmethyldimethoxysilane under acid catalysis; the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is prepared by ring-opening reaction of 2,4,6-trimethyl-2,4,6-tritrifluoropropylcyclotrisiloxane under acid initiation and end-capping with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane.

6. The insulating rubber material for capacitors according to any one of claims 1 to 5, characterized in that: The vulcanizing agent is one or more of diisopropyl benzene peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-bis-tert-butylperoxydiisopropyl benzene, tert-butyl peroxybenzoate or 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne.

7. The insulating rubber material for capacitors according to any one of claims 1 to 5, characterized in that: The accelerator is one or more of accelerator TMTD, accelerator TMTM, accelerator DCP or accelerator DZ.

8. A method for preparing an insulating rubber material for a capacitor according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Weigh the above raw materials according to weight fraction; (2) Add the base material, stearic acid and modified carbon black into an open mill and mix them, heat them to 30-40°C, and mix them for 30-60 minutes to obtain a mixed rubber material; (3) Place the mixed rubber into an internal mixer, add zinc oxide and modified silica in sequence, then heat to 50-60°C and continue mixing for 30-50 minutes; (4) After the rubber compound is mixed, it is left for 18 to 24 hours, then returned to the mixing mill. At the same time, vulcanizing agent and accelerator are added and fully mixed at 45 to 50 ° C for 2 to 4 hours before being taken out.

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