Composition for barium strontium titanate modified composite silicone rubber, composite silicone rubber as well as preparation method and application of composite silicone rubber

Abstract

The invention relates to the technical field of composite insulator materials, and discloses a composition for barium strontium titanate modified composite silicone rubber, the composite silicone rubber and a preparation method and application of the composite silicone rubber. The composition contains raw silicone rubber, modified barium strontium titanate, fumed silica, aluminum hydroxide, a vulcanizing agent and an auxiliary agent, relative to 100 parts by weight of the raw silicone rubber, the content of the modified barium strontium titanate is 10 to 30 parts by weight, the content of the fumed silica is 25 to 30 parts by weight, the content of the aluminum hydroxide is 100 to 120 parts by weight, the content of the vulcanizing agent is 0.1 to 0.2 part by weight, and the content of the auxiliary agent is 4 to 9 parts by weight; the raw silicone rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber in a content mass ratio of 1: (5-15); the barium strontium titanate modified composite silicone rubber provided by the invention has better mechanical properties and aging resistance, and keeps higher volume resistivity and breakdown strength at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite insulator materials, and particularly relates to a barium strontium titanate modified composite silicone rubber composition, a composite silicone rubber and a preparation method and application thereof. BACKGROUND

[0002] High temperature vulcanized silicone rubber (HTV-SiR) is widely used as the core insulating material of composite insulators due to its excellent weather resistance, insulation and elasticity, and is widely used in high-voltage power systems. With the development of power equipment towards high voltage and large capacity, the traditional vinyl silicone rubber (MVQ) has the problems of weak electric field sharing ability and insufficient breakdown strength, which easily leads to local electric field concentration of the insulator, causing insulation aging or breakdown failure, and limits its application in extra-high voltage equipment.

[0003] In the prior art, the performance of silicone rubber is often improved by nano-filler doping or polymer blending modification. For example, TiO2 modified silicone rubber can improve the dielectric performance, but the breakdown strength decreases greatly; the blending of fluorosilicone rubber and MVQ improves the dielectric properties, but the dielectric performance is limited, the price is high, and the high fluorine content may form micro-phase separation due to the increase of molecular chain rigidity and poor compatibility with the MVQ matrix. These interface defects may lead to a decrease in breakdown strength instead of an increase. Barium strontium titanate (BST) as a high dielectric constant ceramic is an ideal dielectric modification filler, which makes the dielectric constant matching degree between the silicone rubber and the core rod higher, thereby "flattening" the electric field distribution at the interface and effectively reducing the high electric field originally borne by the silicone rubber. However, the nano-particles of BST are easy to agglomerate and have poor compatibility with the silicone rubber matrix, and direct addition may form insulation weak points. Therefore, a single composite modification strategy (whether filler filling or polymer blending) is difficult to break the trade-off relationship between dielectric performance and breakdown strength and resistivity.

[0004] CN114750485A discloses a barium strontium titanate fluorosilicon rubber composite gradient material and a preparation method thereof, the preparation method comprising the following steps: uniformly mixing 80-120 parts of fluorosilicon rubber green gum, 30-40 parts of reinforcing agent, 1-6 parts of vulcanizing agent and 5-30 parts of barium strontium titanate according to weight parts, to obtain a mixture, and wherein the ratio of fluorosilicon rubber green gum to barium strontium titanate satisfies 100:5-30; the mixture is subjected to mixing and melting treatment, and an additive forming technology is used to obtain a layered barium strontium titanate fluorosilicon rubber composite gradient material, the barium strontium titanate fluorosilicon rubber composite gradient material comprising 1st to Nth composite material layers with the content of barium strontium titanate decreasing layer by layer from inside to outside, and N is not less than 3. The barium strontium titanate fluorosilicon rubber composite gradient material provided by the method is attached to a semi-conductive shielding layer, and the gradient dielectric constant is used to realize the purpose of homogenizing the electric field, which provides a novel structural design idea for synergistically improving the material performance. However, in the method, the filler is easy to form an insulating weak point in the silicon rubber due to agglomeration and poor compatibility, and a single matrix modification strategy is difficult to improve the dielectric performance while ensuring the breakdown strength; barium strontium titanate (BST) as a high dielectric constant ceramic is an ideal dielectric modification filler, but the nanoparticles are easy to agglomerate and have poor compatibility with the silicon rubber matrix, and direct addition is easy to form an insulating weak point; at the same time, a single matrix modification is difficult to realize the improvement of dielectric performance and dielectric resistance while maintaining the breakdown performance and resistivity.

[0005] In summary, it is of great significance to provide a new modified composite silicone rubber which can better meet the use requirements of high-voltage composite insulators. SUMMARY

[0006] The purpose of the present application is to overcome the problem that the existing barium strontium titanate nanoparticles improve the dielectric performance of the composite silicone rubber while greatly reducing the breakdown strength and resistivity, and to provide a new barium strontium titanate modified composite silicone rubber.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a barium strontium titanate modified composite silicone rubber composition, which contains silicone rubber green gum, modified barium strontium titanate, fumed white carbon black, aluminum hydroxide, vulcanizing agent and auxiliary agent; The content of the modified barium strontium titanate is 10-30 parts by weight, the content of the fumed white carbon black is 25-30 parts by weight, the content of the aluminum hydroxide is 100-120 parts by weight, the content of the vulcanizing agent is 0.1-0.2 parts by weight, and the content of the auxiliary agent is 4-9 parts by weight, relative to 100 parts by weight of the silicone rubber green gum; The silicone rubber green gum is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber with a content mass ratio of 1:5-15; The modified barium strontium titanate is obtained by modifying raw barium strontium titanate with a silane coupling agent, and the mass ratio of the silane coupling agent to the raw barium strontium titanate is 1:15-25.

[0008] According to a preferred embodiment, the silicone raw rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber, and the mass ratio of the two is 1:5-6.

[0009] According to a preferred embodiment, the content of the modified barium strontium titanate is 22-28 parts by weight relative to 100 parts by weight of the silicone raw rubber.

[0010] In some embodiments, the content of vinyl groups in the vinyl silicone rubber is 0.05-0.7 wt% based on the mass of the vinyl silicone rubber.

[0011] In some embodiments, the molar content of trifluoropropyl siloxane units in the trifluoropropyl silicone rubber is 10-20 mol% based on the molar mass of the trifluoropropyl silicone rubber.

[0012] According to a specific embodiment, the specific surface area of the fumed white carbon black is 185-225 m 2 / g.

[0013] According to a specific embodiment, the vulcanizing agent is selected from 1,1-bis-tert-butyl peroxy-3,3,5-trimethylcyclohexane and / or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0014] According to a specific embodiment, the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and vinyltrimethoxysilane.

[0015] In some embodiments, the auxiliary agent includes iron oxide and hydroxyl silicone oil; the content of the iron oxide is 3-4 parts by weight and the content of the hydroxyl silicone oil is 1-4 parts by weight relative to 100 parts by weight of the silicone raw rubber.

[0016] The second aspect of the present application provides a method for preparing a modified barium strontium titanate composite silicone rubber, which uses the components in the composition of the first aspect described above, and the method includes: (1) ultrasonically mixing a silane coupling agent with raw barium strontium titanate in the presence of ethanol, and obtaining modified barium strontium titanate after drying treatment; (2) pre-mixing silicone raw rubber to obtain material I; (3) melt blending the material I, the modified barium strontium titanate, fumed white carbon black, aluminum hydroxide and an auxiliary agent to obtain material II; (4) the vulcanizing agent is used to vulcanize the material II to obtain the barium strontium titanate modified composite silicone rubber.

[0017] According to a specific embodiment, in step (1), the conditions of the ultrasonic mixing include: ultrasonic power of 200-400 W, ultrasonic frequency of 20-30 kHz, temperature of 30-50℃, and time of 30-60 min.

[0018] According to a specific embodiment, in step (2), the conditions of the premixing treatment include: temperature of 50-70℃, and time of 5-7 min.

[0019] According to a specific embodiment, in step (3), the conditions of the melt blending include: temperature of 50-70℃, and time of 40-60 min.

[0020] According to a specific embodiment, in step (4), the conditions of the vulcanization treatment include: temperature of 150-180℃, pressure of 12-18 MPa, and time of 15-30 min.

[0021] The third aspect of the present application provides the barium strontium titanate modified composite silicone rubber prepared by the method of the second aspect.

[0022] The fourth aspect of the present application provides the application of the barium strontium titanate modified composite silicone rubber of the third aspect in high-voltage composite insulators.

[0023] By the above technical solution, the present application has at least the following beneficial technical effects: (1) In the present application, the specific ratio of trifluoropropyl silicone rubber and vinyl silicone rubber is used to form a binary matrix silicone rubber raw rubber. The "polar-nonpolar" interface can enhance the interface polarization effect, which is conducive to improving the dielectric constant of the composite silicone rubber and maintaining a high volume resistivity. At the same time, the interaction between the silane-modified barium strontium titanate and the aforementioned binary matrix is strengthened, making the dispersion more uniform. The modified barium strontium titanate forms a chemical bond or intermolecular force with the vinyl group in the vinyl silicone rubber and the active hydrogen in the trifluoropropyl silicone rubber, reducing the interface gap, so that the volume resistivity and breakdown strength do not decrease significantly.

[0024] (2) In the present application, the mutual synergistic effect between the components makes the obtained barium strontium titanate modified composite silicone rubber have better mechanical properties and aging resistance. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as implicitly disclosed by the language of the specification. The described ranges and values can encompass smaller increments of the value than the value itself and smaller increments are hereby expressly contemplated. For values that have a minimum and maximum value, the minimum and maximum value can be combined with other values to form a new range. The new range is also expressly disclosed.

[0026] As previously described, the first aspect of the present application provides a barium strontium titanate modified composite silicone rubber composition, which contains silicone rubber raw rubber, modified barium strontium titanate, fumed white carbon black, aluminum hydroxide, vulcanizing agent and auxiliary agent; The content of the modified barium strontium titanate is 10-30 parts by weight, the content of the fumed white carbon black is 25-30 parts by weight, the content of the aluminum hydroxide is 100-120 parts by weight, the content of the vulcanizing agent is 0.1-0.2 parts by weight, and the content of the auxiliary agent is 4-9 parts by weight, relative to 100 parts by weight of the silicone rubber raw rubber. The silicone rubber raw rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber in a content mass ratio of 1:5-15. The modified barium strontium titanate is obtained by modifying the raw barium strontium titanate with a silane coupling agent, and the mass ratio of the silane coupling agent to the raw barium strontium titanate is 1:15-25.

[0027] According to a preferred embodiment, the silicone rubber raw rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber in a content mass ratio of 1:5-6. The inventors of the present application have found that in this preferred case, the barium strontium titanate modified composite silicone rubber provided by the present application has better mechanical properties and high-temperature aging resistance.

[0028] According to a preferred embodiment, the content of the modified barium strontium titanate is 22-28 parts by weight, relative to 100 parts by weight of the silicone rubber raw rubber. The inventors of the present application have found that in this preferred case, the barium strontium titanate modified composite silicone rubber provided by the present application can better realize the synergy of its dielectric properties and insulation properties.

[0029] In some embodiments, the content of vinyl groups in the vinyl silicone rubber is 0.05-0.7wt%, based on the mass of the vinyl silicone rubber.

[0030] Preferably, the content of vinyl groups in the vinyl silicone rubber is 0.06-0.2wt%, based on the mass of the vinyl silicone rubber.

[0031] In some embodiments, the molar content of trifluoropropyl siloxane segments in the trifluoropropyl silicone rubber is 10-20mol%, based on the molar mass of the trifluoropropyl silicone rubber.

[0032] Preferably, the molar content of trifluoropropyl siloxane chain segments in the trifluoropropyl silicone rubber is 14-16 mol% based on the molar mass of the trifluoropropyl silicone rubber.

[0033] In some embodiments, the molecular weight of the vinyl silicone rubber is 6 x 10 5 to 7 x 10 5 .

[0034] In some embodiments, the molecular weight of the trifluoropropyl silicone rubber is 5 x 10 5 to 8 x 10 5 .

[0035] According to a specific embodiment, the specific surface area of the fumed white carbon black is 185-225 m 2 / g.

[0036] According to a specific embodiment, the vulcanizing agent is selected from 1,1-bis-tert-butyl peroxy-3,3,5-trimethylcyclohexane and / or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0037] According to a specific embodiment, the silane coupling agent is selected from at least one of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane and vinyl trimethoxysilane.

[0038] In some embodiments, the auxiliary agent includes iron oxide and hydroxyl silicone oil; the content of the iron oxide is 3-4 parts by weight and the content of the hydroxyl silicone oil is 1-4 parts by weight with respect to 100 parts by weight of the raw silicone rubber.

[0039] As described previously, the second aspect of the present application provides a method for preparing a barium strontium titanate modified composite silicone rubber, which applies the components in the composition of the aforementioned first aspect, and the method includes: (1) mixing a silane coupling agent with raw barium strontium titanate under ultrasonic mixing in the presence of ethanol, and obtaining modified barium strontium titanate after drying treatment; (2) performing premixing treatment on a raw silicone rubber to obtain material I; (3) performing melt blending on the material I, the modified barium strontium titanate, fumed white carbon black, aluminum hydroxide and an auxiliary agent to obtain material II; (4) performing vulcanization treatment on a vulcanizing agent and the material II to obtain the barium strontium titanate modified composite silicone rubber.

[0040] According to a specific embodiment, in step (1), the conditions of the ultrasonic mixing include: ultrasonic power of 200-400 W, ultrasonic frequency of 20-30 kHz, temperature of 30-50℃, and time of 30-60 min.

[0041] According to a specific embodiment, in step (1), the conditions of the drying treatment include: temperature of 90-120℃, and time of 3-5 h.

[0042] According to a specific embodiment, in step (1), the amount of the ethanol is controlled so that the solid-liquid mass ratio of the raw material mixture in step (1) is 1:9-11.

[0043] In some embodiments, in step (2), the conditions of the premixing treatment include: temperature of 50-70℃, and time of 5-7 min.

[0044] In some embodiments, in step (3), the conditions of the melt blending include: temperature of 50-70℃, and time of 40-60 min.

[0045] In some embodiments, in step (3), the modified barium strontium titanate is added for 2-4 times, and the interval time is 4-6 min.

[0046] In some embodiments, in step (3), the mixture obtained after the melt blending is further subjected to a standing treatment to obtain the material II; the conditions of the standing treatment include: temperature of 20-40℃, and time of 20-30 h.

[0047] According to a specific embodiment, in step (4), the conditions of the vulcanization treatment include: temperature of 150-180℃, pressure of 12-18 MPa, and time of 15-30 min.

[0048] As described above, the third aspect of the present application provides the modified barium strontium titanate composite silicone rubber prepared by the method of the second aspect.

[0049] As described above, the fourth aspect of the present application provides the use of the modified barium strontium titanate composite silicone rubber of the third aspect in high-voltage composite insulators.

[0050] In order to more clearly understand the technical features, objectives and advantages of the present application, the present application will be described in detail through examples. It should be understood that the specific examples described herein are only used to explain the present application, and the protection scope of the present application is not limited to the following description. In the following examples, unless otherwise specified, various raw materials and reagents used are commercially available products.

[0051] The part raw materials used in the following examples and sources are as follows: Vinyl silicone rubber-I (MVQ-I): the content of vinyl is 0.07-0.12wt%, the model is 110-1, and it is purchased from Huisong Silicone Co., Ltd.; Vinyl silicone rubber-II (MVQ-I): the content of vinyl is 1.5-2.4wt%, the model is 112-6, and it is purchased from Huisong Silicone Co., Ltd.; Trifluoropropyl silicone rubber-I (FMVQ-I): the molar content of trifluoropropyl siloxane chain is 15mol%, and it is purchased from Xinyuan Chemical Co., Ltd.; Trifluoropropyl silicone rubber-II (FMVQ-II): the molar content of trifluoropropyl siloxane chain is 25mol%, and it is purchased from Xinyuan Chemical Co., Ltd.; Silicone rubber raw rubber-I: the combination of MVQ-I and FMVQ-I with a content mass ratio of 85:15; Silicone rubber raw rubber-II: the combination of MVQ-I and FMVQ-I with a content mass ratio of 90:10; Silicone rubber raw rubber-III: the combination of MVQ-II and FMVQ-II with a content mass ratio of 85:15; Silicone rubber raw rubber-IV: the combination of MVQ-I and FMVQ-I with a content mass ratio of 80:20; Fumed white carbon black-I: the specific surface area is 185-225m 2 / g, the model is HS-200, and it is purchased from Huisong Silicone Co., Ltd.; Fumed white carbon black-II: the specific surface area is 150-185m 2 / g, the model is HS-150, and it is purchased from Huisong Silicone Co., Ltd.; Iron oxide: it is purchased from Shanghai Yipin Pigment Co., Ltd.; Hydroxyl silicone oil: it is purchased from Dow Corning Corporation; Vulcanizing agent: 1,1-bis-tert-butyl peroxy-3,3,5-trimethylcyclohexane, and it is purchased from Tak Chemicals Co., Ltd.; In the present application, room temperature is 25±2℃; and every 1 part by weight represents 1g.

[0052] Example 1 (1) 20g of raw material barium strontium titanate and 1g of γ-aminopropyl triethoxysilane were added into 200g of ethanol, and ultrasonic dispersion was carried out at a temperature of 40℃, a power of 300W and a frequency of 25kHz for 45min, and then drying was carried out at 100℃ for 4h to obtain modified barium strontium titanate.

[0053] (2) Put the raw silicone rubber-I into a double roll mill, set the roll temperature to 60°C, the front roll speed to 20 r / min, the rear roll speed to 22 r / min, and the roll gap to 0.7 mm, plasticize for 6 min to fully mix the molecular chains, and obtain material I.

[0054] (3) Mix the fumed white carbon black, aluminum hydroxide, and the auxiliary with material I, mix for 10 min, then add the modified barium strontium titanate in three portions, continue to mix for 20 min until no obvious particles are present; place the obtained mixed rubber at room temperature for 24 h to obtain material II.

[0055] (4) Mix material II with the vulcanizing agent and place it into an insulating mold, set the temperature to 160°C, the pressure to 15 MPa, and the time to 20 min in a flat plate vulcanizing agent, and after vulcanization, cool and demold to obtain the barium strontium titanate modified composite silicone rubber.

[0056] The types and amounts of some reagents in this example are shown in Table 1.

[0057] Example 2 (1) Add 15 g of raw barium strontium titanate and 1 g of vinyl trimethoxysilane into 160 g of ethanol, ultrasonically disperse at a temperature of 40°C, a power of 300 W, and a frequency of 25 kHz for 45 min, and then dry at 100°C for 4 h to obtain modified barium strontium titanate.

[0058] (2) Put the raw silicone rubber-I into a double roll mill, set the roll temperature to 70°C, the front roll speed to 20 r / min, the rear roll speed to 22 r / min, and the roll gap to 0.7 mm, plasticize for 5 min to fully mix the molecular chains, and obtain material I.

[0059] (3) Mix the fumed white carbon black, aluminum hydroxide, and the auxiliary with material I, mix for 10 min, then add the modified barium strontium titanate in three portions, continue to mix for 20 min until no obvious particles are present; place the obtained mixed rubber at room temperature for 24 h to obtain material II.

[0060] (4) Mix material II with the vulcanizing agent and place it into an insulating mold, set the temperature to 150°C, the pressure to 18 MPa, and the time to 30 min in a flat plate vulcanizing agent, and after vulcanization, cool and demold to obtain the barium strontium titanate modified composite silicone rubber.

[0061] The types and amounts of some reagents in this example are shown in Table 1.

[0062] Example 3 (1) Put 25 g of raw material barium strontium titanate and 1 g of γ-glycidoxypropyltrimethoxysilane into 250 g of ethanol, and perform ultrasonic dispersion for 45 min at a temperature of 40 ℃, a power of 300 W, and a frequency of 25 kHz, and then dry at 100 ℃ for 4 h to obtain modified barium strontium titanate.

[0063] (2) Put the raw rubber-I into a double roller mill, set the roller temperature to 50 ℃, the front roller speed to 20 r / min, the rear roller speed to 22 r / min, and the roller gap to 0.7 mm, and plasticize for 7 min to fully mix the molecular chains to obtain material I.

[0064] (3) Mix the fumed white carbon black, aluminum hydroxide, and the auxiliary agent with material I for 10 min, and then add the modified barium strontium titanate in three portions and continue to mix for 20 min until there are no obvious particles; place the obtained mixed rubber at room temperature for 24 h to obtain material II.

[0065] (4) Mix material II with the vulcanizing agent and place it into an insulating mold, and set the temperature to 150 ℃, the pressure to 12 MPa, and the time to 15 min in a flat plate vulcanizing agent, and after vulcanization, cool and demold to obtain the barium strontium titanate modified composite silicone rubber.

[0066] The types and amounts of some reagents in this example are shown in Table 1.

[0067] Table 1

[0068] Example 4 This example is prepared by a method similar to that of Example 1, except that in step (2), an equal weight portion of raw rubber-II is used instead of raw rubber-I in Example 1 to prepare the barium strontium titanate modified composite silicone rubber.

[0069] Example 5 This example is prepared by a method similar to that of Example 1, except that in step (2), an equal weight portion of raw rubber-III is used instead of raw rubber-I in Example 1 to prepare the barium strontium titanate modified composite silicone rubber.

[0070] Example 6 This example is prepared by a method similar to that of Example 1, except that in step (3), an equal weight portion of fumed white carbon black-II is used instead of fumed white carbon black-I in Example 1 to prepare the barium strontium titanate modified composite silicone rubber.

[0071] Example 7 This example was carried out by using the similar method of Example 1, except that in step (3), the amount of modified barium strontium titanate was adjusted to 15 parts by weight, and a barium strontium titanate modified composite silicone rubber was prepared.

[0072] Comparative Example 1 This comparative example was carried out by using the similar method of Example 1, except that in step (2), the same weight of silicone rubber raw rubber-IV was used to replace the silicone rubber raw rubber-I in Example 1, and a barium strontium titanate modified composite silicone rubber was prepared.

[0073] Comparative Example 2 This comparative example was carried out by using the similar method of Example 1, except that in step (2), the same weight of MVQ-I was used to replace the silicone rubber raw rubber-I in Example 1, and a barium strontium titanate modified composite silicone rubber was prepared.

[0074] Comparative Example 3 This comparative example was carried out by using the similar method of Example 1, except that in step (3), the amount of modified barium strontium titanate was adjusted to 35 parts by weight, and a barium strontium titanate modified composite silicone rubber was prepared.

[0075] Comparative Example 4 This comparative example was carried out by using the similar method of Example 1, except that the step (1) was not performed, and in step (3), the same weight of raw material barium strontium titanate was used to replace the modified barium strontium titanate in Example 1, and a barium strontium titanate modified composite silicone rubber was prepared.

[0076] Test Example This test example was used to illustrate the performance test of the barium strontium titanate modified composite silicone rubber prepared in each of the above examples and comparative examples.

[0077] Among them, the dielectric parameters: according to GB / T 1693-2007 standard, the dielectric parameters of the silicone rubber sample were measured by using Concept 80 type broadband dielectric spectrometer; Breakdown strength: according to GB / T 1408.1-2016 standard, the breakdown strength tester was used for testing; Volume resistivity: according to GB / T 1692-2008 standard, the high resistance meter was used for testing; The change rate of tensile strength and the change rate of elongation at break after aging were all tested according to GB / T 528-2009 standard.

[0078] The specific test results are shown in Table 2.

[0079] Table 2

[0080] As can be seen from the experimental results in Table 2, the barium strontium titanate modified composite silicone rubber provided by the present application successfully achieves an excellent balance between improving the dielectric constant, maintaining the insulation strength and volume resistivity, and ensuring the mechanical stability. Among them, Example 1 exhibits the most excellent comprehensive performance, successfully inhibiting the interface charge accumulation and insulation weakness problems that may be caused by the barium strontium titanate filler; Example 5 has a relatively high dielectric constant, but the breakdown strength and volume resistivity are low, and there is a short board; and Comparative Example 2 has the highest breakdown strength and resistivity, but its dielectric constant is too low, which is not conducive to the homogenization of the electric field. The dielectric constant of Comparative Examples 3 and 4 is improved, but the breakdown strength and volume resistivity of Comparative Examples 3 and 4 are significantly deteriorated.

[0081] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A composition for barium strontium titanate modified composite silicone rubber, characterized by, The composition contains silicone rubber raw rubber, modified barium strontium titanate, fumed white carbon black, aluminum hydroxide, vulcanizing agent and auxiliary agent; The content of the modified barium strontium titanate is 10-30 parts by weight, the content of the fumed white carbon black is 25-30 parts by weight, the content of the aluminum hydroxide is 100-120 parts by weight, the content of the vulcanizing agent is 0.1-0.2 parts by weight, and the content of the auxiliary agent is 4-9 parts by weight, relative to 100 parts by weight of the silicone rubber raw rubber; The silicone rubber raw rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber in a content mass ratio of 1:5-15; The modified barium strontium titanate is obtained by modifying raw barium strontium titanate with a silane coupling agent, and the mass ratio of the silane coupling agent to the raw barium strontium titanate is 1:15-25.

2. The composition of claim 1, wherein, The silicone rubber raw rubber is a combination of trifluoropropyl silicone rubber and vinyl silicone rubber in a content mass ratio of 1:5-6; And / or, the content of the modified barium strontium titanate is 22-28 parts by weight, relative to 100 parts by weight of the silicone rubber raw rubber.

3. The composition of claim 1, wherein, The content of vinyl groups in the vinyl silicone rubber is 0.05-0.7 wt%, based on the mass of the vinyl silicone rubber; And / or, the molar content of trifluoropropyl siloxane segments in the trifluoropropyl silicone rubber is 10-20 mol%, based on the molar mass of the trifluoropropyl silicone rubber.

4. The composition according to any one of claims 1-3, wherein, The specific surface area of the fumed white carbon is 185-225 m 2 / g; And / or, the vulcanizing agent is selected from 1,1-bis-tert-butyl peroxy-3,3,5-trimethylcyclohexane and / or 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; And / or, the silane coupling agent is selected from at least one of γ-aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane and vinyl trimethoxysilane.

5. The composition according to any one of claims 1-3, wherein, The auxiliary agent includes iron oxide and hydroxyl silicone oil; The content of the iron oxide is 3-4 parts by weight, and the content of the hydroxyl silicone oil is 1-4 parts by weight, relative to 100 parts by weight of the silicone rubber raw rubber.

6. A method of preparing barium strontium titanate modified composite silicone rubber, characterized by, The method applies each component in the composition of any one of claims 1-5, and the method comprises: (1) ultrasonic mixing of a silane coupling agent and raw barium strontium titanate in the presence of ethanol, and obtaining modified barium strontium titanate after drying treatment; (2) pre-mixing treatment of silicone rubber raw rubber to obtain material I; (3) melt blending of the material I, the modified barium strontium titanate, fumed white carbon black, aluminum hydroxide and auxiliary agent to obtain material II; (4) vulcanization treatment of a vulcanizing agent and the material II to obtain the barium strontium titanate modified composite silicone rubber.

7. The method of claim 6, wherein, In step (1), the ultrasonic mixing conditions include: ultrasonic power of 200-400 W, ultrasonic frequency of 20-30 kHz, temperature of 30-50℃, and time of 30-60 min; And / or, in step (2), the pre-mixing treatment conditions include: temperature of 50-70℃, and time of 5-7 min.

8. The method of claim 6 or 7, wherein, In step (3), the melt blending conditions include: temperature of 50-70℃, and time of 40-60 min; And / or, in step (4), the conditions of the vulcanization treatment include: temperature of 150-180℃, pressure of 12-18MPa, time of 15-30min.

9. The barium strontium titanate modified composite silicone rubber prepared by the method of any one of claims 6-8.

10. The use of the barium strontium titanate modified composite silicone rubber of claim 9 in high-voltage composite insulators.

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