Insulating rubber material for capacitor and preparation method thereof

Abstract

The invention relates to the technical field of insulating rubber composite materials, in particular to an insulating rubber material for a capacitor and a preparation method of the insulating rubber material. The invention provides an insulating rubber material for capacitors, which is prepared from the following raw materials in parts by weight: 80-120 parts of a 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 a vulcanizing agent and 0.5-1 part of an accelerant, so as to solve the problems of appearance deformation and poor sealing performance of a product caused by swelling of rubber. And meanwhile, good mechanical property and aging resistance can be kept, so that the requirement of using an immersed capacitor in an extreme environment can be met. A mixture of fluorinated silicone rubber and silicone rubber is used as a base material, and a chitosan / carbon black / tin antimony oxide composite material is used as modified carbon black, so that the mechanical property, oil resistance, aging resistance, environmental adaptability and electrical insulation property of the rubber material are synergistically enhanced, and the prepared rubber material is unlikely to swell after being soaked in mineral oil.

Description

Technical Field

[0001] The 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 requirements for heat dissipation of capacitors are getting higher and higher. Existing capacitor insulation materials are prone to swelling when immersed in mineral oil, causing deformation of the product appearance and affecting the performance and service life of the capacitor. Therefore, it is of great practical significance to develop an insulating rubber sheet for capacitors that is resistant to mineral oil swelling.

[0003] In the field of capacitor sealing materials, fluororubber is widely used due to its excellent oil resistance, high temperature resistance and chemical corrosion resistance. Chinese patent CN103772858A discloses a fluororubber capacitor sealing gasket and its preparation method, using fluororubber as the base rubber, the obtained sealing gasket has good oil resistance, but due to the poor mechanical properties and radiation resistance of fluororubber, especially below -20°C, its elasticity and flexibility will significantly decrease, poor mechanical properties will lead to reduced sealing performance, long-term exposure to radiation environment will also lead to poor mechanical properties of the material due to poor radiation resistance, and fluororubber has poor processing performance, difficult processing, high application cost, and is not conducive to widespread use; Chinese patent CN104292841A discloses a high-insulation mixed silicone rubber sealing gasket for metal film capacitors, using methyl vinyl raw rubber as raw rubber, with good insulation performance, mechanical properties and processing performance, but its solvent resistance and aging resistance are poor, it is easy to swell and deform under the immersion of mineral oil, and it is also easy to accelerate aging under high temperature environment, making the mechanical properties deteriorate.

[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 immersed capacitors in 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 white carbon black, 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, so that the insulating rubber material has 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; and the introduction of trifluoropropyl in fluorosilicone rubber makes vulcanization 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, it can further improve the performance of the composite material in extreme low-temperature environments after being combined with silicone rubber. In addition, both fluorosilicone rubber and silicone rubber have good weather resistance and can resist the influence of ultraviolet rays, ozone and climate change. Using them in combination 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 modifying white carbon black 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 comprises the following steps: stirring and mixing the modifier and silica in a weight ratio of (5 to 15):100, heating and reacting at 100 to 140° C. for 12 to 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 elaborated 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] As a commonly used reinforcing agent, carbon black can significantly improve the tensile strength, tear strength and wear resistance of rubber. Carbon black particles form physical crosslinking points in the rubber matrix, increasing the strength and toughness of the rubber; chitosan molecular chains can form physical or chemical bonds with rubber molecules to improve the strength and toughness of the rubber; antimony tin oxide is an inorganic filler with good oil resistance, which can improve the resistance of rubber to mineral oil swelling, allowing it to maintain stable physical properties in a mineral oil environment, helping to improve its appearance and aging resistance. The ultraviolet absorption properties of antimony tin oxide also help reduce the aging effect of rubber exposed to ultraviolet rays for a long time.

[0017] Chitosan, carbon black and antimony tin oxide work together, not only have their own original properties, but also because of the combination between them, the components interact with each other. The flexibility of chitosan, the rigidity of carbon black, and the oil resistance and aging resistance of antimony tin oxide can form a good toughening effect in rubber. The modification of carbon black by chitosan and antimony tin oxide also improves its electrical insulation properties. Therefore, it can further enhance the mechanical properties of rubber such as tensile strength, tear strength, impact strength and wear resistance, and also significantly enhance 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 sealing pads 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 diisopropylbenzene peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-di-tert-butylperoxydiisopropylbenzene, tert-butyl peroxybenzoate 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 mixer for mixing, heating to 30-40° C., and mixing for 30-60 minutes to obtain a mixed rubber material;

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

[0026] (4) After the rubber compound is mixed, leave it for 18 to 24 hours, then return it to the mixing mill, add the vulcanizer and accelerator, mix thoroughly at 45 to 50°C for 2 to 4 hours, and then take it 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 mineral oil swelling resistance of the insulating rubber material is increased while ensuring the high and low temperature resistance, mechanical properties and aging resistance of the composite material;

[0029] 2. The modified white carbon black used in the present invention 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;

[0030] 3. The present invention adopts 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 immersed 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 scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. The schematic implementation mode of the present invention and its 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, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without 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 meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 a conflict with any incorporated document, the content 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 of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are 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 problem 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, the present embodiment provides an insulating rubber material for capacitors, the raw materials of which include the following parts by weight: 80 to 120 parts of base material, 40 to 60 parts of modified white carbon black, 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 vulcanizing agent, and 0.5 to 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, use 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 modifying white carbon black 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] The method for modifying silica using the 1,3-dimethyl-1,3-ditrifluoropropyl-1,3-dimethoxydisiloxane or α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane comprises the following steps: mixing the modifier and silica in a weight ratio of (5-15):100, heating the mixture 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 elaborated 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, and also significantly enhance its oil resistance, aging resistance, environmental adaptability and electrical insulation properties, making it an ideal material choice, especially in applications with extremely high requirements for material performance, 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 rubber and can more effectively block the penetration of oil molecules, thereby improving the oil resistance of rubber.

[0049] As a preferred embodiment, the vulcanizing agent is a peroxide vulcanizing agent, and the peroxide vulcanizing agent is one or more of diisopropyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-di-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 also 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 mixer for mixing, heating to 30-40° C., and mixing for 30-60 minutes to obtain a mixed rubber material;

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

[0055] (4) After the rubber compound is mixed, leave it for 18 to 24 hours, then return it to the mixing mill, add the vulcanizer and accelerator, mix thoroughly at 45 to 50°C for 2 to 4 hours, and then take it out.

[0056] The present 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 resistance of the insulating rubber material to mineral oil swelling, ensuring the high and low temperature resistance, mechanical properties and aging resistance of the composite material; the modified white carbon black 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, and the synergistic effect of the three also 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 easy to swell.

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

[0058] Example 1

[0059] An insulating rubber material for capacitors, the raw materials of which include the following parts by weight: 80 parts of 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 vulcanizing agent, and 0.5 part of 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 comprises 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 mixer for mixing, heating to 30° C., and mixing for 60 minutes to obtain a mixed rubber material;

[0066] (3) The mixed rubber material was placed in an internal mixer, and zinc oxide and modified silica were added in sequence, and then heated to 50°C and mixed for 50 minutes;

[0067] (4) After the rubber compound is mixed, it is left for 18 hours and then remixed in an open mill. At the same time, vulcanizer 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 comprises: dissolving 5g chitosan in 1200ml 1% (v / v) acetic acid aqueous solution, then adding 1.5mg carbon black and 1g 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] An insulating rubber material for capacitors, the raw materials of which include the following parts by weight: 100 parts of 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 vulcanizing agent, and 0.8 parts of 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 comprises 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 mixer for mixing, heating to 35° C., and mixing for 50 min to obtain a mixed rubber material;

[0077] (3) The mixed rubber material was placed in an internal mixer, and zinc oxide and modified silica were added in sequence, followed by heating to 55°C and mixing for 40 minutes;

[0078] (4) After the rubber compound is mixed, it is left for 24 hours and then re-mixed in an open mixer. At the same time, 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 comprises: dissolving 4g chitosan in 800ml 1.5% (v / v) acetic acid aqueous solution, then adding 1.0g carbon black and 0.5g 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] An insulating rubber material for capacitors, the raw materials of which include the following parts by weight: 120 parts of 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 vulcanizing agent, and 1 part of 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 comprises 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 mixer for mixing, heating to 40° C., and mixing for 60 minutes to obtain a mixed rubber material;

[0088] (3) The mixed rubber material was placed in an internal mixer, and zinc oxide and modified silica were added in sequence, and then heated to 60°C and mixed for 50 minutes;

[0089] (4) After the rubber compound is mixed, it is left for 24 hours and then re-mixed in an open mixer. At the same time, 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 comprises: dissolving 5g chitosan in 1000ml 2% (v / v) acetic acid aqueous solution, then adding 2g carbon black and 0.8g 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 Embodiment 1, and the only difference from Embodiment 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 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 Embodiment 1, and the only difference from Embodiment 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-tritrifluoropropyl cyclotrisiloxane and end-capping with 1,1,3,3-tetramethyl-1,3-diethyldisiloxane; the weight average molecular weight of the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane is about 1200Da.

[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 the only difference from Example 1 is 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 the only difference from Example 1 is that the modified carbon black in this comparative example is chitosan modified carbon black, that is, this comparative example uses chitosan modified carbon black to replace the chitosan / carbon black / antimony tin oxide composite material in Example 1.

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

[0103] Comparative Example 3

[0104] This comparative example is based on Example 1, and the only difference from Example 1 is that: in this comparative example, no chitosan / carbon black / antimony tin oxide composite material is prepared. In the preparation process of the rubber material, chitosan, carbon black and antimony tin oxide are added simultaneously 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 comprises 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 mixer for mixing, heating to 40° C., and mixing for 60 minutes to obtain a mixed rubber material;

[0108] (3) The mixed rubber material is placed in an internal mixer, and zinc oxide is added followed by chitosan, carbon black and antimony tin oxide, and then the mixture is heated to 60° C. and mixed for 50 min.

[0109] (4) After the rubber compound is mixed, it is left for 24 hours and then re-mixed in an open mixer. At the same time, 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 raw 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 raw 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 embodiments 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 taken out to test the change rate of tensile strength, elongation at break, and Shore hardness before and after the aging test. The change rate of each performance = (performance value after aging test - corresponding initial performance value) / corresponding initial performance value × 100%.

[0118] Oil resistance test: The prepared insulating rubber material is made into samples of the same size, immersed in 20# engine oil at 100℃ for 48 hours, and then taken out to test the change rate of tensile strength, elongation at break, Shore hardness and volume before and after oil immersion. The change rate of each performance = (performance value after oil immersion test - corresponding initial performance value) / corresponding initial performance value × 100%.

[0119] Table 1 Insulation rubber material performance test results

[0120]

[0121]

[0122] From the data of Examples 1-5, it can be seen that the insulating rubber material for capacitors prepared by the present invention has good mechanical properties, aging resistance and oil resistance, and the mechanical property loss and deformation degree under mineral oil immersion are significantly lower than those of the comparative example. Among them, Examples 4-5 have significantly better mechanical properties, aging resistance and oil resistance, which proves that the use of silica modified with siloxane containing fluorine silicon structure is conducive to improving the above properties of insulating rubber materials, especially the α,ω-vinyl-terminated methyltrifluoropropyl oligosiloxane used in Example 5 has the most obvious improvement on the above properties of rubber.

[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 to 120 parts of base material, 40 to 60 parts of modified white carbon black, 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 vulcanizing agent, and 0.5 to 1 part of accelerator; Wherein, the base material is a mixture of fluorosilicone rubber and methyl vinyl silicone rubber.

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 KH550, KH560, KH570, 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 claim 1, characterized in that: The modified carbon black is a chitosan / carbon black / antimony tin oxide composite material.

7. The insulating rubber material for capacitors according to claim 6, characterized in that: The preparation method of the chitosan / carbon black / antimony tin oxide composite material comprises: dissolving chitosan in an acetic acid aqueous solution, then adding carbon black and antimony tin oxide, 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.

8. The insulating rubber material for capacitors according to any one of claims 1 to 7, characterized in that: The vulcanizing agent is one or more of diisopropylbenzene peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 1,4-di-tert-butylperoxydiisopropylbenzene, tert-butyl peroxybenzoate or 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne.

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

10. A method for preparing an insulating rubber material for a capacitor according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Weigh the above raw materials according to weight fraction; (2) adding the base material, stearic acid and modified carbon black into an open mixer for mixing, heating to 30-40° C., and mixing for 30-60 minutes to obtain a mixed rubber material; (3) Put the mixed rubber into an internal mixer, add zinc oxide and modified white carbon black in sequence, then heat to 50-60°C and continue mixing for 30-50 minutes; (4) After the rubber compound is mixed, leave it for 18 to 24 hours, then return it to the mixing mill, add the vulcanizer and accelerator, mix thoroughly at 45 to 50°C for 2 to 4 hours, and then take it out.

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