High-elasticity multi-element doped silicone rubber composition as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of silicone rubber materials, and particularly discloses a high-elasticity multi-element doped silicone rubber composition as well as a preparation method and application thereof. The silicone rubber composition provided by the invention comprises a base rubber, an inorganic reinforcing filler, a flame-retardant anti-leakage filler, a functional modified filler, an anti-ultraviolet filler and an auxiliary agent. The silicone rubber provided by the invention is designed according to a special formula for different severe environments, can accurately meet the requirements of scenes such as strong ultraviolet high altitude, high humidity and high pollution, strong arc and high load, and is suitable for various electric power parts such as composite insulator umbrella skirts, electric power equipment composite jackets, anti-pollution flashover coatings and the like. In the preparation process of the silicone rubber, the silicone rubber material which is uniform in filler dispersion and excellent in strength and electrical performance is prepared by adopting a rigorous process of step-by-step preparation of a pre-dispersion body, internal mixing and defoaming, injection molding and secondary vulcanization.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber materials technology, and in particular to a highly elastic multi-doped silicone rubber composition, its preparation method, and its application. Background Technology

[0002] Silicone rubber, with its excellent electrical insulation, hydrophobicity and weather resistance, has become a core material for key components such as composite insulators for high-voltage transmission lines and composite jackets for power equipment.

[0003] However, power equipment often operates in harsh environments such as high altitudes with strong ultraviolet radiation, high humidity and heat, high pollution, and high loads with strong electric arcs. Traditional silicone rubber not only suffers from poor resistance to ultraviolet aging, weak resistance to humidity and heat pollution, and easy degradation of electrical properties, but also faces the critical bottleneck of insufficient elasticity. During long-term operation, traditional silicone rubber is prone to permanent deformation and fracture when subjected to external impacts, temperature changes, or continuous stress, leading to sheath cracking and outer sheath damage, which in turn can cause safety accidents such as leakage and flashover, seriously affecting the reliability of power grid operation. Existing improvement solutions mostly focus on improving the UV resistance, leakage resistance, or hydrophobic properties of silicone rubber, but neglect the synergistic optimization of high elasticity and other properties. Some solutions improve elasticity by adding a single elastic filler, but this leads to a decrease in electrical properties or weather resistance, making it difficult to meet the dual requirements of high elasticity and high reliability of power equipment in harsh environments.

[0004] Therefore, there is an urgent need to develop a silicone rubber material that combines multiple properties such as high elasticity, UV resistance, leakage resistance, and hydrophobicity. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention provides a highly elastic multi-component doped silicone rubber composition, its preparation method, and its applications. The silicone rubber of this invention solves the problems of insufficient elasticity in traditional silicone rubber and the difficulty in synergistically optimizing it with other properties, achieving simultaneous improvement in high elasticity and properties such as UV resistance, leakage resistance, hydrophobicity, and high mechanical strength.

[0006] The present invention also provides a method for preparing the highly elastic multi-doped silicone rubber composition.

[0007] The present invention also provides a highly elastic multi-doped silicone rubber.

[0008] In a first aspect, the present invention provides a highly elastic multi-component doped silicone rubber composition, comprising the following components: a base rubber, an inorganic reinforcing filler, a flame-retardant and anti-leakage filler, a functionally modified filler, an anti-ultraviolet filler, and additives;

[0009] The base adhesive includes methyl vinyl siloxane raw rubber; the inorganic reinforcing filler includes fumed silica, α-alumina, and alumina fiber; the flame-retardant and anti-leakage filler includes aluminum hydroxide micro powder, SiC-TiC composite filler, and kaolin; the functional modified filler includes graphene nanosheets, hydrophobic fumed silica, cross-linked polytetrafluoroethylene, and hydroxyl-terminated polybutadiene; the UV-resistant filler includes rutile titanium dioxide and zinc oxide; and the additives include mixed silicone oil, coupling agent, vulcanizing agent, defoamer, and inhibitor.

[0010] According to a specific embodiment of the present invention, the high elasticity multi-component doped silicone rubber composition provided by the present invention uses methyl vinyl siloxane raw rubber as the base rubber, combined with inorganic reinforcing fillers, functional modified fillers, flame retardant and anti-leakage fillers, anti-ultraviolet fillers and additives to form a multi-component synergistic system.

[0011] The base adhesive of this invention uses methyl vinyl siloxane raw rubber with a specific molecular weight and vinyl content, providing basic elasticity and insulation to the material and a good carrier for filler dispersion. In the inorganic reinforcing filler, fumed silica enhances mechanical strength and breakdown strength, inhibiting crack propagation; α-alumina optimizes insulation performance and reduces dielectric constant; alumina fibers construct a three-dimensional reinforcing network while also providing elastic support, preventing excessive material rigidity. In the flame-retardant and anti-leakage filler, dual-particle-size aluminum hydroxide micropowder decomposes at high temperature to dehydrate and cool, inhibiting electrical tracking; SiC-TiC composite filler controls conductivity and improves volume resistivity; kaolin inhibits surface carbonization and reduces leakage current peaks. In the functional modified filler, graphene nanosheets ablate to form a dense carbon layer, reducing UV and arc damage; hydrophobic silica constructs a nano-uneven surface, increasing the hydrophobic angle; cross-linked polytetrafluoroethylene synergistically enhances hydrophobicity and chemical corrosion resistance; hydroxyl-terminated polybutadiene specifically strengthens the material's elasticity and elastic recovery ability, solving the problem of easy deformation in traditional silicone rubber. In the UV-resistant filler, rutile titanium dioxide absorbs ultraviolet light and inhibits molecular chain breakage; zinc oxide synergistically resists ultraviolet light and improves vulcanization efficiency. In the additives, mixed silicone oil improves filler dispersibility and controls structure; coupling agents improve the compatibility between fillers and base rubber, enhancing mechanical strength and elastic stability; vulcanizing agents promote crosslinking and increase crosslinking density; defoamers reduce mixing bubbles and lower breakdown defects; and inhibitors control the vulcanization rate and prevent molding scorching.

[0012] According to some embodiments of the present invention, the components of the composition, by weight, include: 80-120 parts of base adhesive, 58-96 parts of inorganic reinforcing filler, 95-130 parts of flame retardant and anti-leakage filler, 45-90 parts of functional modified filler, 8-18 parts of anti-ultraviolet filler, and 22-75 parts of additives.

[0013] According to some embodiments of the present invention, the components of the composition, by weight, include: 80-120 parts of methyl vinyl siloxane raw rubber, 35-58 parts of fumed silica, 4-9 parts of α-alumina, 20-32 parts of alumina fiber, 75-95 parts of aluminum hydroxide micro powder, 22-45 parts of SiC-TiC composite filler, 0.8-6 parts of kaolin, 0.3-1.2 parts of graphene nanosheets, 35-60 parts of hydrophobic silica, 10-30 parts of crosslinked polytetrafluoroethylene, 0.5-2 parts of hydroxyl-terminated polybutadiene, 3-8 parts of rutile titanium dioxide, 5-10 parts of zinc oxide, 6-14 parts of mixed silicone oil, 14-32 parts of coupling agent, 0.6-3.2 parts of vulcanizing agent, 0.3-0.6 parts of defoamer, and 0.3-0.8 parts of inhibitor.

[0014] According to some preferred embodiments of the present invention, the components of the composition, by weight, include: 6-8 parts of rutile titanium dioxide and 8-10 parts of zinc oxide. This preferred amount of component in the high-elasticity multi-component doped silicone rubber composition selectively enhances its UV resistance. While ensuring good synergistic effect of the overall multi-component doped material, the preferred use of a larger amount of UV-resistant filler makes it more suitable for power equipment materials used in strong UV environments at high altitudes.

[0015] According to some preferred embodiments of the present invention, the components of the composition, by weight, include: 55-60 parts of hydrophobic silica, 22-30 parts of crosslinked polytetrafluoroethylene, and 11-14 parts of mixed silicone oil. This preferred amount of component in the high-elasticity multi-component doped silicone rubber composition of the present invention selectively enhances its resistance to damp heat. While ensuring good synergistic effects of the overall multi-component doped materials, the preferred use of a larger amount of hydrophobic functional filler makes it more suitable for use in power equipment materials in high-humidity, high-heat, and high-pollution environments.

[0016] According to some preferred embodiments of the present invention, the components of the composition, by weight, include: 40-45 parts SiC-TiC composite filler, 28-32 parts alumina fiber, and 1.3-2 parts hydroxyl-terminated polybutadiene. This preferred dosage of components in the high-elasticity multi-component doped silicone rubber composition selectively enhances its arc resistance. While ensuring good synergistic effects of the overall multi-component doped material, the preferred dosage of more arc-resistant and elastic-enhancing components makes it more suitable for use in power equipment materials under strong arc and high-load environments.

[0017] According to some embodiments of the present invention, the methyl vinyl siloxane raw rubber has a molecular weight of 450,000 to 800,000 and a vinyl content of 0.20 wt% to 0.25 wt%; the fumed silica has a specific surface area of ​​190 to 260 m². 2 g; the particle size of the α-alumina is 10~45μm; the length of the alumina fiber is 5~35μm.

[0018] According to some embodiments of the present invention, the length of the alumina fiber is 15~25 μm. The present invention has discovered that the use of alumina fiber and its length parameters in this silicone rubber composition have a significant impact on its mechanical and electrical properties. Alumina fibers using the preferred length parameters of the present invention exhibit relatively superior strength, breakdown resistance, and leakage resistance.

[0019] According to some embodiments of the present invention, the aluminum hydroxide micropowder comprises components with a particle size of 1.8~2.5μm and a particle size of 2.5~4.2μm, with a mass ratio of (4~6):1; the SiC-TiC composite filler is treated with a silane coupling agent and has a particle size of 40~90nm; the kaolin has a particle size of 0.6~2.2μm; the graphene nanosheets have a particle size of 4~8μm; and the hydrophobic silica has a specific surface area of ​​190~230m². 2 / g, pH value 6.8~7.8; the number average molecular weight of the hydroxyl-terminated polybutadiene is 1000~3000; the particle size of the rutile titanium dioxide is 18~45nm; the particle size of the zinc oxide is 45~95nm.

[0020] According to some embodiments of the present invention, the mixed silicone oil includes hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil; in the mixed silicone oil, the weight ratio of hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil is 1:(2~6):(12~22).

[0021] According to some embodiments of the present invention, the coupling agent comprises a silane coupling agent; the vulcanizing agent comprises 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane; the defoamer comprises triethanolamine; and the inhibitor comprises divinyltetramethyldisiloxane.

[0022] A second aspect of the present invention provides a method for preparing a highly elastic multi-element doped silicone rubber composition as described in the first aspect of the present invention, comprising the following steps:

[0023] S1. Preparation of pre-dispersion:

[0024] S1A. Add a portion of methyl vinyl siloxane raw rubber, a portion of mixed silicone oil and alumina micro powder to a kneader and knead to obtain a flame-retardant pre-dispersion.

[0025] S1B, Add the remaining methyl vinyl siloxane raw rubber, part of the mixed silicone oil, fumed silica, α-alumina and alumina fiber to a kneader and knead to obtain the reinforced predispersant;

[0026] S1C, hydrophobic silica, graphene nanosheets, SiC-TiC composite filler, and hydroxyl-terminated polybutadiene are dried, and the remaining mixed silicone oil is added to obtain a functional predispersant;

[0027] S2, Pre-vulcanization:

[0028] Flame retardant predispersant, reinforced predispersant, functional predispersant, rutile titanium dioxide, zinc oxide, kaolin, and coupling agent are added to a mixer and mixed to obtain pre-vulcanized silicone rubber.

[0029] S3, Injection Molding and Secondary Vulcanization:

[0030] Pre-cured silicone rubber is added to an injection molding machine to obtain a silicone rubber preform. The preform is placed in a hydrophobic silica pressure bed and kept under pressure to allow the hydrophobic silica to be adsorbed. The adsorbed preform is then vulcanized and cooled to room temperature to obtain a highly elastic multi-element doped silicone rubber.

[0031] The preparation method of this invention employs a rigorous process involving stepwise preparation of pre-dispersions, intensive mixing and degassing, injection molding, and secondary vulcanization. Stepwise preparation of flame-retardant pre-dispersions, reinforcing pre-dispersions, and functional pre-dispersions effectively avoids agglomeration between different fillers, ensuring uniform dispersion of each filler in the base rubber, especially guaranteeing the dispersion consistency of elastic fillers, providing a structural foundation for high elasticity. The intensive mixing process uses specific temperatures and vacuum levels to fully remove air bubbles, avoiding their impact on the material's elasticity and electrical properties. The temperature and pressure parameters for injection molding are optimized to ensure the material fully fills the mold, forming a uniform internal structure. The hydrophobic silica pressure bed holding step allows the hydrophobic silica to be uniformly adsorbed onto the surface of the preform, while further optimizing the material's surface elastic recovery properties. Secondary vulcanization, through precise control of temperature and time, ensures more complete cross-linking of the material, resulting in superior elasticity and stability.

[0032] According to some embodiments of the present invention, in step S1, the kneading temperature of the kneader is 145~160℃.

[0033] According to some embodiments of the present invention, in step S3, the temperature of the injection molding machine is 155~175℃ and the pressure is 9~13MPa; the pressure of the pressure bed is 4~6MPa, the holding time is 3~6min, the temperature of the pressure bed is 165~185℃, and the temperature difference between the pressure bed and the preform is ≤18℃; the vulcanization parameters are vulcanization at 185~205℃ for 2.5~4.5h.

[0034] A third aspect of the present invention provides a highly elastic multi-element doped silicone rubber, said silicone rubber being made from the highly elastic multi-element doped silicone rubber composition described in the first aspect of the present invention.

[0035] The beneficial effects of this invention are:

[0036] (1) This invention innovatively constructs a "high elasticity-multi-performance synergy" system. By introducing hydroxyl-terminated polybutadiene and optimizing the base rubber parameters and filler ratio, it achieves simultaneous improvement in high elasticity, UV resistance, leakage resistance, hydrophobicity, and high mechanical strength, solving the core problem of insufficient elasticity of traditional silicone rubber. The material's elongation at break can reach more than 230%, the elastic recovery rate exceeds 95%, and the elastic decay rate after strong UV aging is less than 5%.

[0037] (2) The present invention is designed with special formulas for different harsh environments, which can accurately match the needs of scenarios such as strong ultraviolet high altitude, high humidity and heat, high pollution, strong electric arc and high load. It is suitable for a variety of power components such as composite insulator skirts, composite jackets of power equipment, and anti-pollution flashover coatings. Its service life is extended by more than 60% compared with traditional silicone rubber, reducing the cost of unplanned replacement of power grids.

[0038] (3) The preparation process of the present invention follows the rubber industry standard. The required equipment such as kneader, internal mixer, and injection molding machine are the industry standard configuration. The step-by-step pre-dispersion process is easy to operate and facilitates large-scale production by enterprises.

[0039] (4) All components in the material of this invention meet environmental protection requirements, and the preparation process has no harmful gas emissions, which is in line with the concept of green manufacturing and helps the green and sustainable development of the power grid.

[0040] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0041] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0042] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0043] The high-elasticity multi-component doped silicone rubber composition of this invention uses methyl vinyl siloxane raw rubber as the base rubber, which has a molecular weight of 450,000 to 800,000 and a vinyl content of 0.20 wt% to 0.25 wt% by mass fraction. The formulations of each component by weight are shown in Table 1 below:

[0044] Example 1

[0045] This embodiment provides a general-purpose, highly elastic, multi-element doped silicone rubber. The raw material components of this silicone rubber, by weight, are as follows:

[0046] Base rubber: 100 parts of methyl vinyl siloxane raw rubber;

[0047] Inorganic reinforcing filler: 40 parts fumed silica, 6 parts α-alumina, and 25 parts alumina fiber;

[0048] Flame-retardant and anti-leakage filler: 85 parts aluminum hydroxide micro powder, 28 parts SiC-TiC composite filler, and 3 parts kaolin;

[0049] Functional modified filler: 0.8 parts graphene nanosheets, 45 parts hydrophobic silica, 20 parts cross-linked polytetrafluoroethylene, and 1 part hydroxyl-terminated polybutadiene;

[0050] UV-resistant filler: 5 parts rutile titanium dioxide, 7 parts zinc oxide;

[0051] Additives: 10 parts mixed silicone oil, 25 parts silane coupling agent, 1.8 parts vulcanizing agent, 0.4 parts defoamer, and 0.5 parts inhibitor;

[0052] Among them, the specific surface area of ​​fumed silica is 220 m². 2 / g, the particle size of α-alumina is 30μm, and the length of alumina fibers is 20μm; in the aluminum hydroxide micro powder, the weight ratio of aluminum hydroxide micro powder with a particle size of 1.9μm to 3.0μm is 5:1, the particle size of SiC-TiC composite filler is 60nm, and the particle size of kaolin is 1.2μm; the diameter of graphene nanosheets is 6μm, and the specific surface area of ​​hydrophobic silica is 210m². 2 / g, pH value 7.2, number average molecular weight of hydroxyl-terminated polybutadiene is 2000; rutile titanium dioxide particle size is 30nm, zinc oxide particle size is 60nm; in the mixed silicone oil, the weight ratio of hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil is 1:4:18, the vulcanizing agent is 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, the defoamer is triethanolamine, and the inhibitor is divinyltetramethyldisiloxane.

[0053] The preparation steps of the multi-doped silicone rubber in this embodiment are as follows:

[0054] 1) Preparation of pre-dispersion:

[0055] Add 50 parts of 100 parts of methyl vinyl siloxane raw rubber, 3 parts of 10 parts of mixed silicone oil, and 85 parts of aluminum hydroxide micro powder to a kneader and knead at 150°C for 1.5 hours to obtain a flame-retardant predispersant.

[0056] The remaining 50 parts of methyl vinyl siloxane raw rubber, 4 parts of 10 parts of mixed silicone oil, 40 parts of fumed silica, 6 parts of α-alumina, and 25 parts of alumina fiber were added to a kneader and kneaded at 155°C for 1.8 hours to obtain a reinforced predispersant.

[0057] 45 parts of hydrophobic silica, 0.8 parts of graphene nanosheets, 28 parts of SiC-TiC composite filler, and 1 part of hydroxyl-terminated polybutadiene were dried at 85°C for 10 hours to ensure that the moisture content was <0.1%. Then, they were mixed with the remaining 3 parts of mixed silicone oil for 1.2 hours to obtain a functional pre-dispersion.

[0058] 2) Pre-vulcanization:

[0059] Flame retardant predispersant, reinforced predispersant, functional predispersant, 5 parts rutile titanium dioxide, 7 parts zinc oxide, 3 parts kaolin, and 25 parts silane coupling agent were added to a mixer and mixed at 150°C and 0.08 MPa for 60 minutes. After removing air bubbles, pre-vulcanized silicone rubber was obtained.

[0060] 3) Injection molding and secondary vulcanization:

[0061] Pre-cured silicone rubber is added to an injection molding machine and injection molded at 165℃ and 11MPa to obtain silicone rubber preforms.

[0062] The preform was placed in a hydrophobic silica pressure bed and held at 175℃ and 5MPa for 4 minutes to ensure that the hydrophobic silica coverage was not less than 85%.

[0063] The adsorbed preform was vulcanized at 195℃ for 3 hours and then cooled to room temperature to obtain a general-purpose high-elasticity multi-element doped silicone rubber.

[0064] Example 2

[0065] This embodiment provides a UV-resistant, highly elastic, multi-doped silicone rubber.

[0066] The silicone rubber in this embodiment is suitable for strong ultraviolet radiation and high-altitude environments. Compared with Example 1, the formulation increases the amount of UV-resistant filler: rutile titanium dioxide is adjusted to 7 parts, zinc oxide to 9 parts, fumed silica to 48 parts, and hydroxyl-terminated polybutadiene to 1.2 parts. The remaining components and amounts are the same as in Example 1, and the preparation process parameters are the same as in Example 1.

[0067] Example 3

[0068] This embodiment provides a moisture- and heat-resistant, highly elastic, multi-doped silicone rubber.

[0069] The silicone rubber of this embodiment is suitable for high humidity, heat and pollution environments. Compared with the formulation of Example 1, the amount of hydrophobic functional filler is increased: hydrophobic silica is adjusted to 60 parts, cross-linked polytetrafluoroethylene is adjusted to 25 parts, and mixed silicone oil is adjusted to 12 parts. The weight ratio of hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil in the mixed silicone oil is 1:5:20. The remaining components and amounts are the same as in Example 1, and the preparation process parameters are the same as in Example 1.

[0070] Example 4

[0071] This embodiment provides an arc-resistant, highly elastic, multi-element doped silicone rubber.

[0072] The silicone rubber in this embodiment is suitable for high-load environments with strong electric arcs. Compared with Example 1, the formulation increases the components for arc resistance and elasticity enhancement: the SiC-TiC composite filler is adjusted to 45 parts, the alumina fiber is adjusted to 30 parts, and the hydroxyl-terminated polybutadiene is adjusted to 1.5 parts. The remaining components and their amounts are the same as in Example 1. In the preparation process, the vulcanization temperature is adjusted to 200℃, the vulcanization time is extended to 4 hours, and the remaining parameters are the same as in Example 1.

[0073] Example 5

[0074] This embodiment provides a general-purpose, highly elastic, multi-doped silicone rubber.

[0075] This embodiment is basically the same as Embodiment 1, except that different lengths of alumina fibers are used to prepare silicone rubber in this embodiment: X1: 5μm alumina fiber, X2: 15μm alumina fiber, X3: 25μm alumina fiber, X4: 35μm alumina fiber. The preparation process is the same as in Embodiment 1.

[0076] Comparative Example 1

[0077] This comparative example provides multi-doped silicone rubber.

[0078] This comparative example is basically the same as Example 1, except that the hydroxyl-terminated polybutadiene in the functional modified filler is removed from the silicone rubber component of this comparative example. The remaining components and preparation process are the same as in Example 1, and it is used to verify the effect of hydroxyl-terminated polybutadiene on the elasticity of silicone rubber.

[0079] Comparative Example 2

[0080] This comparative example provides multi-doped silicone rubber.

[0081] This comparative example is basically the same as Example 1. The difference is that in the preparation process of this comparative example, the step-by-step preparation step of the pre-dispersion is cancelled, and all components are directly added to the internal mixer in step 2) for subsequent processing. The remaining formula and process parameters are the same as those in Example 1. This is used to verify the effect of the step-by-step preparation process on the uniformity and elasticity of silicone rubber.

[0082] Comparative Example 3

[0083] This comparison sample provides silicone rubber.

[0084] This comparative example retains only three components from Example 1: methyl vinyl siloxane raw rubber, aluminum hydroxide micro powder, and fumed silica. All other components are removed. The preparation process is the same as in Example 1. This example is used to verify the advantages of the multi-component synergistic system in multi-component doped silicone rubber.

[0085] Comparative Example 4

[0086] This comparative example provides multi-doped silicone rubber.

[0087] This comparative example is basically the same as Example 5, except that different lengths of alumina fibers are used to prepare silicone rubber in this comparative example: X5: 3μm alumina fiber, X6: 40μm alumina fiber. The preparation process is the same as in Example 1, which is used to verify the effect of alumina fiber length on the performance of multi-element doped silicone rubber.

[0088] Comparative Example 5

[0089] This comparative example provides multi-doped silicone rubber.

[0090] This comparative example is basically the same as Example 1, except that the alumina fiber in the inorganic reinforcing filler is removed from the silicone rubber component of this comparative example. The remaining components and preparation process are the same as in Example 1, and it is used to verify the effect of alumina fiber on the performance of multi-element doped silicone rubber.

[0091] Comparative Example 6

[0092] This comparative example provides multi-doped silicone rubber.

[0093] This comparative example is basically the same as Example 1, except that in the silicone rubber component of this comparative example, cross-linked polytetrafluoroethylene is replaced with ordinary commercial polytetrafluoroethylene. The remaining components and preparation process are the same as in Example 1, and it is used to verify the effect of cross-linked polytetrafluoroethylene on the performance of multi-element doped silicone rubber.

[0094] Performance testing:

[0095] The silicone rubbers prepared in Examples 1-4 and Comparative Examples 1-3 were cut into samples of 14mm × 12mm × 2mm. Performance tests were conducted according to industry standards "DL / T376-2019 General Technical Conditions for Insulating Materials for Sheaths and Jackets of Polymer Insulators" and "GB / T528-2009 Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The tests focused on tensile strength, elongation at break, elastic recovery rate, breakdown strength, tracking depth, static contact angle, electrical erosion depth, and changes in performance after aging. The test results are shown in Table 2 below.

[0096] The performance of the silicone rubber products in Example 5 and Comparative Example 4 was compared and tested, and the results are shown in Table 3 below:

[0097] The performance of the silicone rubber products from Example 1 and Comparative Example 5 was compared and tested, and the results are shown in Table 4 below:

[0098] Further comparative testing of the silicone rubber products of Example 1 and Comparative Example 6 yielded results shown in Table 5 below:

[0099] Comparing the performance test results of the silicone rubber products in the above embodiments and comparative examples, it can be seen that the embodiments of the present invention, through the synergistic effect of multi-component synergy and optimized preparation process, have obtained silicone rubber materials with both high elasticity and excellent environmental resistance. From the test data, each embodiment shows outstanding performance in core performance indicators. Mechanical properties such as tensile strength and elongation at break after aging remain at high levels, elastic recovery rate is stable and within an excellent range, key properties such as electrical insulation, leakage resistance, and hydrophobicity are effectively optimized, the degree of electro-erosion is significantly reduced, and the performance degradation after aging is controlled within a small range. Furthermore, some embodiments also possess specific advantages such as durable hydrophobicity and excellent arc resistance, making them suitable for different application scenarios. For example, when the alumina fiber length is optimized to a suitable range (Table 3), all mechanical and electrical properties of the material reach optimal levels. In the UV aging test, Example 1 shows a significantly reduced degree of elastic decay, far superior to Comparative Example 5, and exhibits excellent chemical corrosion resistance and significantly enhanced hydrophobicity retention.

[0100] The comparative examples, due to the absence of key components or simplified processes, exhibited significantly deteriorated elasticity and overall performance. Comparative Examples 1-3 showed a substantial decrease in tensile strength, elongation at break, and elastic recovery after aging. Their electrical insulation properties also significantly declined, resistance to tracking deteriorated, and electrolytic corrosion intensified. The rate of performance degradation after aging was significantly increased, with some samples also exhibiting significant elasticity degradation and large fluctuations in volume resistivity. Comparative Example 5 showed a significantly higher degree of elasticity degradation after UV aging than Example 1. Comparative Example 6 exhibited poor hydrophobicity and chemical corrosion resistance, with insufficient hydrophobicity retention after aging, and its overall performance fell far short of the requirements for use in harsh environments.

[0101] The above data fully demonstrates the rationality and innovation of the formulation design and preparation process of this invention. The high-elasticity multi-doped silicone rubber of this invention maintains high elasticity while effectively improving multiple properties such as UV resistance, leakage resistance, hydrophobicity, mechanical strength, and chemical corrosion resistance. It is suitable for key components of power equipment in various harsh environments and has broad application prospects.

[0102] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A highly elastic multi-element doped silicone rubber composition, characterized in that, It includes the following components: base adhesive, inorganic reinforcing filler, flame retardant and anti-leakage filler, functional modified filler, UV-resistant filler and additives; The base adhesive includes methyl vinyl siloxane raw rubber; the inorganic reinforcing filler includes fumed silica, α-alumina, and alumina fiber; the flame-retardant and anti-leakage filler includes aluminum hydroxide micro powder, SiC-TiC composite filler, and kaolin; the functional modified filler includes graphene nanosheets, hydrophobic fumed silica, cross-linked polytetrafluoroethylene, and hydroxyl-terminated polybutadiene; the UV-resistant filler includes rutile titanium dioxide and zinc oxide; and the additives include mixed silicone oil, coupling agent, vulcanizing agent, defoamer, and inhibitor.

2. The highly elastic multi-element doped silicone rubber composition according to claim 1, characterized in that, The composition comprises, by weight, 80-120 parts of base adhesive, 58-96 parts of inorganic reinforcing filler, 95-130 parts of flame retardant and anti-leakage filler, 45-90 parts of functional modified filler, 8-18 parts of UV-resistant filler, and 22-75 parts of additives.

3. The highly elastic multi-element doped silicone rubber composition according to claim 2, characterized in that, The composition comprises, by weight, 80-120 parts of methyl vinyl siloxane raw rubber, 35-58 parts of fumed silica, 4-9 parts of α-alumina, 20-32 parts of alumina fiber, 75-95 parts of aluminum hydroxide micro powder, 22-45 parts of SiC-TiC composite filler, 0.8-6 parts of kaolin, 0.3-1.2 parts of graphene nanosheets, 35-60 parts of hydrophobic silica, 10-30 parts of crosslinked polytetrafluoroethylene, 0.5-2 parts of hydroxyl-terminated polybutadiene, 3-8 parts of rutile titanium dioxide, 5-10 parts of zinc oxide, 6-14 parts of mixed silicone oil, 14-32 parts of coupling agent, 0.6-3.2 parts of vulcanizing agent, 0.3-0.6 parts of defoamer, and 0.3-0.8 parts of inhibitor.

4. The highly elastic multi-element doped silicone rubber composition according to any one of claims 1 to 3, characterized in that, The methyl vinyl siloxane gum has a molecular weight of 450,000-800,000, and a vinyl content of 0.20wt%-0.25wt%; the fumed white carbon black has a specific surface area of 190-260m 2 G; the alpha-alumina has a particle size of 10-45um; and the alumina fiber has a length of 5-35um.

5. The highly elastic multi-element doped silicone rubber composition according to any one of claims 1 to 3, characterized in that, The aluminum hydroxide micropowder comprises components with a particle size of 1.8~2.5μm and a particle size of 2.5~4.2μm, with a mass ratio of (4~6):1; the SiC-TiC composite filler is treated with a silane coupling agent and has a particle size of 40~90nm; the kaolin has a particle size of 0.6~2.2μm; the graphene nanosheets have a particle size of 4~8μm; and the hydrophobic silica has a specific surface area of ​​190~230m². 2 / g, pH value 6.8~7.8; the number average molecular weight of the hydroxyl-terminated polybutadiene is 1000~3000; the particle size of the rutile titanium dioxide is 18~45nm; the particle size of the zinc oxide is 45~95nm.

6. The highly elastic multi-element doped silicone rubber composition according to any one of claims 1 to 3, characterized in that, The mixed silicone oil includes hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil; the weight ratio of hydrogen-containing silicone oil, methyl silicone oil and hydroxyl silicone oil in the mixed silicone oil is 1:(2~6):(12~22).

7. The highly elastic multi-element doped silicone rubber composition according to any one of claims 1 to 3, characterized in that, The coupling agent includes a silane coupling agent; the vulcanizing agent includes 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane; the defoamer includes triethanolamine; and the inhibitor includes divinyltetramethyldisiloxane.

8. The method for preparing the highly elastic multi-element doped silicone rubber composition according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Preparation of pre-dispersion: S1A. Add a portion of methyl vinyl siloxane raw rubber, a portion of mixed silicone oil and alumina micro powder to a kneader and knead to obtain a flame-retardant pre-dispersion. S1B, Add the remaining methyl vinyl siloxane raw rubber, part of the mixed silicone oil, fumed silica, α-alumina and alumina fiber to a kneader and knead to obtain the reinforced predispersant; S1C, hydrophobic silica, graphene nanosheets, SiC-TiC composite filler, and hydroxyl-terminated polybutadiene are dried, and the remaining mixed silicone oil is added to obtain a functional predispersant; S2, Pre-vulcanization: Flame retardant predispersant, reinforced predispersant, functional predispersant, rutile titanium dioxide, zinc oxide, kaolin, and coupling agent are added to a mixer and mixed to obtain pre-vulcanized silicone rubber. S3. Injection molding and secondary vulcanization: Pre-cured silicone rubber is added to an injection molding machine to obtain a silicone rubber preform. The preform is placed in a hydrophobic silica pressure bed and kept under pressure to allow the hydrophobic silica to be adsorbed. The adsorbed preform is then vulcanized and cooled to room temperature to obtain a highly elastic multi-element doped silicone rubber.

9. The preparation method according to claim 8, characterized in that, In step S1, the kneading temperature of the kneader is 145~160℃; in step S3, the injection molding machine temperature is 155~175℃, and the pressure is 9~13MPa; the pressure bed pressure is 4~6MPa, the holding time is 3~6min, the pressure bed temperature is 165~185℃, and the temperature difference between the pressure bed and the preform is ≤18℃; the vulcanization parameters are vulcanization at 185~205℃ for 2.5~4.5h.

10. A highly elastic multi-element doped silicone rubber, characterized in that, The silicone rubber is made from the highly elastic multi-doped silicone rubber composition according to any one of claims 1 to 7.

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