Antimicrobial composite material for ultra-high voltage power transmission in humid and hot environment and preparation method thereof

Abstract

The invention discloses an antimicrobial composite material for ultra-high voltage power transmission in a humid and hot environment and a preparation method thereof, the material takes vinyl-terminated polydimethylsiloxane (V-PDMS) as a matrix, and the material comprises the following components in parts by weight: 100 parts of V-PDMS, 3-5 parts of hydrogen-containing silicone oil, 0.8-1.5 parts of a platinum catalyst, 0.01-0.15 part of a nano-silver / zirconium phosphate silver-loaded composite antibacterial agent and 10-15 parts of a fumed silica reinforcing agent. The preparation method comprises the steps of matrix pretreatment, antibacterial agent nano-dispersion, vacuum blending vulcanization and segmented curing molding. Through composite antibacterial components and a synergistic cross-linking system, the problems that an existing silicone rubber insulator is insufficient in anti-microbial performance and prone to biological aging in a high-temperature and high-humidity environment are solved, long-acting efficient antibacterial performance is achieved, meanwhile, excellent thermal stability, electrical insulation performance and mechanical strength of the material are completely kept, and the service life of the material is prolonged. The cable is especially suitable for outdoor insulation equipment of ultra-high voltage transmission lines in hot and humid areas.

Description

Technical Field

[0001] This invention belongs to the field of insulating materials technology, and particularly relates to an antimicrobial composite material for ultra-high voltage power transmission in humid and hot environments and its preparation method. Background Technology

[0002] Silicone rubber (SR), due to its unique silicon-oxygen bond structure in its molecular backbone, possesses excellent thermal stability, electrical insulation, and outstanding resistance to contamination flashover, making it the preferred material for outdoor insulators of ultra-high voltage transmission lines. However, in hot and humid tropical regions, microorganisms widely present in the natural environment (such as Aspergillus niger) easily colonize and proliferate on the surface of insulators. These molds secrete various extracellular organic substances, and these acidic or enzymatic substances catalyze the hydrolysis of polydimethylsiloxane in the silicone rubber backbone, leading to irreversible degradation of the mechanical and dielectric properties of the silicone rubber material. This biological aging process severely shortens the service life of insulators, drastically reducing it from the expected 10 years to less than 5 years, posing a serious threat to the long-term safe and stable operation of the power grid.

[0003] To address the problem of microbial corrosion, existing technologies have attempted to modify silicone rubber insulators with antibacterial properties, but these technologies all have significant shortcomings. For example, the method of surface coating with an antibacterial layer is prone to wear, aging, and peeling off in harsh outdoor environments, making the antibacterial effect difficult to sustain and potentially hindering the inherent hydrophobicity and migration properties of silicone rubber, thus affecting its anti-flashover performance. If the antibacterial agent is directly mixed into the matrix through physical blending, it is difficult to achieve uniform dispersion of the antibacterial agent at the nanoscale, and agglomeration is highly likely to occur. These agglomeration points not only become defects within the material but may also cause local electric field distortion, significantly increasing the risk of electrical breakdown. Furthermore, although chemical grafting modification can achieve a strong bond of antibacterial components, its process is usually complex and cumbersome, with high production costs, and it is difficult to apply to large-scale industrial production, limiting its engineering application prospects.

[0004] Among numerous antibacterial agents, silver-based antibacterial agents have attracted considerable attention due to their broad spectrum, high efficiency, and strong durability. However, how to stably and uniformly disperse silver-based antibacterial agents at the nanoscale in a hydrophobic silicone rubber matrix, while achieving long-lasting antibacterial function and fully maintaining the inherent electrical insulation properties, mechanical properties, and thermal stability of the silicone rubber matrix, remains a long-standing technical challenge in this field. Specifically, if the silver-based antibacterial agent is unevenly dispersed, its aggregates can become charge traps, degrading the dielectric properties and space charge characteristics of the material; if too many surfactants or dispersants are introduced to solve the dispersion problem, impurity ions may be introduced, leading to increased conductivity and decreased insulation performance. Therefore, developing a long-life composite insulator that can effectively resist microbial erosion in humid and hot environments while maintaining the excellent electrical and mechanical properties of silicone rubber has become a critical issue that urgently needs to be addressed in ultra-high voltage power transmission projects, especially in the construction of power grids in tropical regions. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an antimicrobial composite material for ultra-high voltage power transmission in humid and hot environments and its preparation method. This solves the problem of silicone rubber insulators being eroded and aged by Aspergillus niger under tropical high temperature and humidity conditions, and avoids the shortcomings of existing antibacterial technologies such as rapid attenuation of effectiveness, complex processes, and performance imbalance.

[0006] To achieve the above objectives, the present invention provides an antimicrobial composite material for ultra-high voltage power transmission in humid and hot environments, comprising the following components by weight: Vinyl-terminated polydimethylsiloxane (V-PDMS) 100 parts by weight Hydrogen-containing silicone oil (PMHS) 3-5 parts by weight, Platinum catalyst (Pt) 0.8~1.5 parts by weight, Nano-silver / zirconium phosphate silver-loaded composite antibacterial agent, 0.01~0.15 parts by weight. 10-15 parts by weight of fumed silica reinforcing agent; The nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is a mixture of nano-silver particles and silver-loaded zirconium phosphate carrier.

[0007] V-PDMS serves as the matrix, providing inherent insulation and hydrophobicity; PMHS acts as a crosslinking agent, and Pt as a catalyst, together constructing a three-dimensional crosslinked network, endowing the material with elasticity and strength; fumed silica acts as a reinforcing agent, enhancing mechanical properties through physical action. The core innovation lies in the introduction of a specific morphology and content of nano-silver / zirconium phosphate silver-loaded composite antibacterial agent. Nano-silver provides immediate contact bactericidal action, while silver-loaded zirconium phosphate, as an ion pool, can slowly and continuously release silver ions throughout the material's lifespan through ion exchange, achieving a synergistic antibacterial effect. This composite structure and strictly controlled ratio ensure highly efficient antibacterial activity at extremely low addition levels, while avoiding degradation of electrical performance due to excessive or incompatible antibacterial agents.

[0008] Furthermore, the nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is added in the form of a dispersion with a solid content of 8%~12%, which disperses in the vinyl-terminated polydimethylsiloxane matrix to form a gray homogeneous colloid without precipitation or aggregation. Its addition in pre-dispersed liquid form, combined with a specific subsequent dispersion process, greatly promotes the initial dispersion of the antibacterial agent in the hydrophobic silicone rubber matrix, effectively preventing the dry aggregation of nanoparticles and laying the foundation for achieving a uniform nanoscale distribution in the matrix. The formation of a homogeneous colloid is a direct indicator of good dispersion, which is a prerequisite for ensuring uniform material properties and avoiding local electric field distortion.

[0009] Furthermore, the nano-silver particles in the nano-silver / zirconium phosphate silver-supported composite antibacterial agent have a particle size of 10-50 nm. Controlling the particle size of the nano-silver within this range allows for full utilization of the nano-size effect, resulting in a larger specific surface area and higher surface activity, thereby significantly improving its antibacterial efficiency. If the particle size is too small, severe aggregation easily occurs, leading to a surge in cost; if the particle size is too large, the specific surface area decreases, and the antibacterial effect declines.

[0010] Furthermore, the vinyl-terminated polydimethylsiloxane has a number-average molecular weight of 45,000 to 55,000. V-PDMS within this molecular weight range has a suitable chain length and vinyl content, ensuring the formation of a sufficiently dense and complete three-dimensional network structure with the crosslinking agent PMHS, thereby achieving excellent mechanical strength and resilience. It also avoids problems such as high processing viscosity and difficulty in dispersion caused by excessively high molecular weight, facilitating uniform mixing of all components.

[0011] The present invention also provides a method for preparing the antimicrobial composite material as described above, comprising the following steps: Matrix pretreatment: 100 parts by weight of vinyl-terminated polydimethylsiloxane are mixed with 20-30 parts by weight of heptane solvent and heated and stirred at 90-100°C for 1-2 hours to form a pre-crosslinked matrix; 10-15 parts by weight of fumed silica reinforcing agent are added to the pre-crosslinked matrix, and after stirring and mixing, ultrasonic dispersion treatment is performed to obtain a homogeneous V-PDMS base material; Antibacterial agent nano-dispersion: Under inert gas protection, 0.01~0.15 parts by weight of the nano-silver / zirconium phosphate silver-supported composite antibacterial agent are added to the V-PDMS base material and stirred at 400~600 r / min for 1~2 hours to form a uniform colloid; then vacuum distillation is performed to remove the heptane solvent to obtain the antibacterial agent-V-PDMS nanocomposite. Vacuum blending and vulcanization: The antibacterial agent-V-PDMS nanocomposite is mixed with 3-5 parts by weight of hydrogen-containing silicone oil and 0.8-1.5 parts by weight of platinum catalyst in a vacuum reactor, and the vacuum is evacuated to a vacuum degree ≤ -0.092MPa. Then, under an inert atmosphere, it is vulcanized at a temperature of 75-85℃ for 6-12 hours to form a three-dimensional cross-linked network structure.

[0012] In the above preparation method, firstly, the viscosity of the system is reduced by using heptane solvent, and combined with heating, stirring, and ultrasonic dispersion, the reinforcing agent is ensured to be fully and uniformly dispersed in the matrix, eliminating initial defects and agglomerates, and providing a homogeneous reaction basis for subsequent steps. Secondly, the process is carried out under inert gas protection to prevent the silver component from being oxidized and deactivated; medium-speed stirring combined with the good fluidity of the matrix in the early stage ensures uniform distribution of the antibacterial agent; subsequent vacuum distillation thoroughly removes the process solvent, avoiding the adverse effects of residual solvent on the electrical properties and long-term aging performance of the material. Finally, the vacuum environment eliminates the interference of air (especially oxygen) and moisture, preventing them from inhibiting the activity of the platinum catalyst and ensuring that the hydrosilylation reaction proceeds efficiently and fully; the mild sulfidation temperature avoids the sintering deactivation and matrix thermal degradation that high temperatures may cause to the silver antibacterial agent, thus perfectly preserving the antibacterial function while constructing a stable cross-linked network.

[0013] Furthermore, in the matrix pretreatment step, the ultrasonic dispersion treatment time is 20-40 minutes. This time range is sufficient to effectively break up the secondary agglomeration of fillers such as fumed silica using the cavitation effect of ultrasound, dispersing them in the form of primary particles. However, excessive time may lead to local overheating or molecular chain degradation. Optimizing the time ensures both dispersion efficiency and material stability.

[0014] Furthermore, in the antibacterial agent nano-dispersion step, the vacuum distillation conditions are: temperature 50-60℃, vacuum degree above -0.095MPa, and time 30-50 minutes. These mild distillation conditions efficiently remove heptane solvent while avoiding premature cross-linking of the matrix or aggregation of the antibacterial agent caused by excessively high temperatures, and also preventing excessively high vacuum degrees from causing material boiling. This ensures that the solvent is completely removed, resulting in a pure nanocomposite.

[0015] Furthermore, in the vacuum blending and vulcanization step, after evacuation and before vulcanization, high-purity argon gas is introduced into the vacuum reactor to atmospheric pressure. Introducing inert high-purity argon gas after evacuation provides an oxygen-free and anhydrous pure inert environment for the vulcanization reaction, further ensuring the activity of the platinum catalyst and the smooth progress of the crosslinking reaction, thereby improving the crosslinking density and network quality.

[0016] Furthermore, following the vacuum blending and vulcanization step, a staged curing step is also included: the vulcanized rubber compound is injected into a mold, initially cured at 28-32°C for 22-26 hours, and then finally cured at 55-65°C for 34-38 hours until the elastomer properties are stable. After demolding, the finished product is obtained. The staged curing strategy is crucial. Initially curing at a low temperature allows the material to flow slowly in the mold, fully filling the mold cavity and releasing internal stress, avoiding bubbles or deformation caused by rapid curing. Subsequently, the temperature is increased for final curing, which promotes complete cross-linking reaction, further strengthens and stabilizes the three-dimensional network structure, and ensures that the final shape, dimensional stability, and mechanical properties (such as hardness) of the product reach an optimal and uniform state.

[0017] The present invention also provides an electrical insulation device, which is made of the antimicrobial composite material as described above; the electrical insulation device is an outdoor composite insulator, crossarm insulator or external insulating sleeve for ultra-high voltage transmission lines, and its application environment is a hot and humid environment with an annual average temperature ≥26℃ and a relative humidity ≥85%.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides an antimicrobial composite material for ultra-high voltage power transmission in humid and hot environments and its preparation method. The antimicrobial composite material contains nanoscale dispersed silver-based antibacterial agents, achieving an antibacterial rate of 97.5% against Aspergillus niger. After 12 months of accelerated aging in a simulated humid and hot environment, the antibacterial rate remains ≥95%, and the antibacterial durability exceeds 15 years. At the same time, the antimicrobial composite material maintains electrical insulation performance and mechanical strength comparable to conventional silicone rubber insulation materials, with an expected service life of no less than 15 years.

[0019] The preparation process of this invention is simple and controllable, with a total production cycle of about 68 hours. The raw material cost is 7% to 12% higher than that of pure silicone rubber, making it suitable for industrial production. The resulting antibacterial composite insulator has excellent external insulation performance, with dielectric and mechanical properties similar to those of traditional silicone rubber insulators, and can effectively inhibit the growth of microorganisms for a long time. The silver-based antibacterial agent used has good chemical stability and good compatibility with the silicone rubber matrix, ensuring stable performance of the insulator over long-term use. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation process of the antibacterial composite insulator of the present invention. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] All raw materials used in this invention are not particularly restricted in their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0023] There are no particular restrictions on the purity of any of the raw materials used in this invention. However, this invention preferably uses raw materials of analytical grade or purity commonly used in the field of chemical synthesis.

[0024] The core of this invention lies in providing an antibacterial composite insulator and its preparation method. This insulator is particularly suitable for ultra-high voltage transmission lines in tropical and humid environments, effectively inhibiting the erosion of microorganisms such as Aspergillus niger while maintaining excellent electrical insulation and mechanical properties. This invention achieves nanoscale dispersion of the antibacterial agent in a silicone rubber matrix by optimizing material composition and process parameters, avoiding performance degradation caused by agglomeration.

[0025] Figure 1 This is a flowchart of the preparation process of the antimicrobial composite material of the present invention, which clearly shows the entire process from matrix pretreatment, antimicrobial agent nano-dispersion, vacuum blending and vulcanization to segmented curing.

[0026] The main raw materials used in the experiment and their specifications are as follows: Vinyl-terminated polydimethylsiloxane (V-PDMS): The vinyl-terminated polydimethylsiloxane with model number 68083-19-2, purchased from Guangdong Yuanfeng Chemical Technology Co., Ltd., was selected as the matrix material. Its number average molecular weight is 45,000~55,000, vinyl content is ≥0.12mmol / g, and purity is ≥99%. The -Si-O-Si- structure of its molecular backbone endows it with excellent thermal stability, electrical insulation properties and surface hydrophobicity, which provides a guarantee for the basic insulation and anti-pollution flashover performance of the insulator.

[0027] Nano-silver / zirconium phosphate silver-loaded composite antibacterial agent: a gray suspension with a solid content of 10%, comprising 10-50nm nano-silver particles (model SS818381) purchased from Shanghai McLean Technology Co., Ltd., and YD0121 silver-loaded zirconium phosphate carrier purchased from Guangzhou Yuanda New Materials Co., Ltd. Nano-silver provides immediate contact sterilization, while the silver-loaded zirconium phosphate continuously releases silver ions through ion exchange, achieving a synergistic antibacterial effect of "rapid sterilization + long-term inhibition". This agent is broad-spectrum and highly effective, and the carrier has good insulation properties, not affecting the dielectric properties of the matrix.

[0028] Hydrogen-containing silicone oil (PMHS): As a crosslinking agent, its active hydrogen content is 0.8±0.1%, and it is available from Yuyao Jinzhao Polymer Materials Co., Ltd., specifically model 202 hydrogen-containing methyl silicone oil. Under platinum catalysis, the Si-H bonds of PMHS undergo a hydrosilylation reaction with the vinyl groups of V-PDMS to form stable -Si-CH2-CH2-Si- crosslinking bonds, constructing a three-dimensional network structure, which endows the elastomer with high mechanical strength, resilience, and resistance to permanent deformation.

[0029] Platinum catalyst (Pt catalyst): This experiment used a Karstedt-type platinum catalyst with chloroplatinic acid as a precursor and modified with a specific ligand. The catalyst was purchased from Dongguan Aokai New Materials Co., Ltd. and its model number was OK-Pt-50. The actual platinum content was 3000±100 ppm. Under heating conditions, it can efficiently catalyze hydrosilylation reaction, significantly reduce crosslinking temperature and time, reduce energy consumption and avoid thermal degradation of materials, and ensure reaction efficiency and product stability.

[0030] Fumed silica reinforcing agent: S818464 fumed silica purchased from Shanghai McLean Technology Co., Ltd., hydrophobically treated, with a specific surface area of ​​200±20m². 2 / g. It forms a nano-network in the matrix, which significantly improves the tensile strength, tear strength and modulus of the composite material through physical adsorption and chain entanglement effects, while improving compatibility with the matrix and reducing agglomeration.

[0031] Heptane solvent: Analytical grade heptane solvent, model 2J3382AR, purchased from Xilong Scientific Co., Ltd., with a boiling point of 98.5℃, was selected as the process solvent. It effectively reduces the viscosity of the system, facilitates the uniform dispersion of fillers and antibacterial agents, and can be completely removed in subsequent vacuum distillation to avoid residues affecting the electrical properties and long-term stability of the product.

[0032] Example 1 This embodiment provides an antimicrobial composite material for ultra-high voltage power transmission in humid and hot environments, comprising the following components by weight: The composition includes 100 parts V-PDMS, 4 parts PMHS, 1.2 parts Pt catalyst, 12 parts fumed silica reinforcing agent, 25 parts heptane solvent, and 0.08 parts nano-silver / zirconium phosphate silver-loaded composite antibacterial agent. The number average molecular weight of V-PDMS is 50,000.

[0033] The method for preparing antimicrobial composite insulators using this antimicrobial composite material includes the following steps: (1) Matrix pretreatment: V-PDMS was placed in a flask and heptane solvent was added. The flask was sealed and placed in a constant temperature oil bath. It was heated at 95°C and 200 r / min for 1.5 hours to form a pre-crosslinked matrix. Subsequently, fumed silica reinforcing agent was added to the matrix, and the mixture was transferred to a planetary mixer and stirred at 300 r / min for 60 minutes at room temperature (25±2°C). After that, the mixture was treated with an ultrasonic disperser for 30 minutes to eliminate particle agglomeration and impurities with a particle size ≥1μm, and finally a homogeneous and impurity-free V-PDMS matrix was obtained.

[0034] (2) Antibacterial agent nano-dispersion: The above V-PDMS base material was transferred to an argon-protected stirred tank, and argon gas with a purity ≥99.99% (flow rate 60 mL / min) was introduced to purge for 40 minutes to replace the air. Subsequently, nano-silver / zirconium phosphate silver-loaded composite antibacterial agent was added to the stirred tank. The stirring speed was set to 500 r / min, and the mixture was stirred for 1.5 hours to form a uniform and stable gray colloid without stratification. After stirring, the material was transferred to a rotary evaporator and rotary evaporated at 55℃ and a vacuum of -0.095 MPa for 40 minutes to completely remove the heptane solvent, obtaining a gray homogeneous antibacterial agent-V-PDMS nanocomposite.

[0035] (3) Vacuum blending and vulcanization: The antibacterial agent-V-PDMS nanocomposite was loaded into a stainless steel vacuum reactor, followed by the addition of PMHS (crosslinking agent) and Pt catalyst. The reactor was sealed, the vacuum pump was started, and the vacuum was evacuated to ≤-0.092 MPa and maintained for 20 minutes to remove air and moisture. Then, high-purity argon gas was introduced into the reactor to atmospheric pressure, and the reactor was placed in a constant temperature oil bath, heated to 80℃ and kept at that temperature for 8 hours to allow the vinyl groups of PMHS and V-PDMS to fully crosslink through hydrosilylation reaction, forming a three-dimensional crosslinked network.

[0036] (4) Segmented Curing: After vulcanization, wait for the reactor to cool to room temperature (25±2℃), remove the vulcanized rubber compound, and cut it into block blanks suitable for the insulator mold using a CNC cutting machine. Inject the blanks into the insulator mold and gently tap the mold to vibrate and remove air bubbles. Place the mold in a 30℃ environment for preliminary curing for 24 hours, and then transfer it to a 60℃ oven for final curing for 36 hours. During the curing process, monitor the hardness of the elastomer every 12 hours using a Shore A hardness tester to ensure that it is stable at 52±2 Shore A. After curing, slowly open the mold to demold, and obtain the antibacterial composite insulator product. Wipe its surface with anhydrous ethanol to remove residual impurities.

[0037] Example 2 The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following components: The composition consists of 100 parts V-PDMS, 3 parts PMHS, 1.5 parts Pt catalyst, 10 parts fumed silica reinforcing agent, 30 parts heptane solvent, and 0.01 parts nano-silver / zirconium phosphate silver-supported composite antibacterial agent. The number average molecular weight of V-PDMS is 45,000. All other components, proportions, and preparation processes are identical to those in Example 1.

[0038] Example 3 The difference between this embodiment and Embodiment 1 is that, by weight, it includes the following components: The composition consists of 100 parts V-PDMS, 5 parts PMHS, 0.8 parts Pt catalyst, 15 parts fumed silica reinforcing agent, 20 parts heptane solvent, and 0.15 parts nano-silver / zirconium phosphate silver-supported composite antibacterial agent. The number average molecular weight of V-PDMS is 55,000. All other components, proportions, and preparation processes are identical to those in Example 1.

[0039] Example 4 The difference between this embodiment and Example 1 is that in step (1), the heating temperature of the mixture of V-PDMS and heptane solvent is adjusted to 90°C and the heating time is extended to 2 hours. The remaining components, proportions and preparation processes are exactly the same as in Example 1.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that no nano-silver / zirconium phosphate silver-loaded composite antibacterial agent was added in step (2). The remaining components, ratios, and preparation processes were exactly the same as in Example 1. This comparative example served as a blank control group to compare and verify the necessity of introducing the antibacterial agent and its contribution to various properties.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that, in step (2), the amount of nano-silver / zirconium phosphate silver-loaded composite antibacterial agent added is 0.20 parts. The remaining components, proportions, and preparation processes are exactly the same as in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (2), the nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is replaced by an equal amount of ordinary nano-zinc oxide (ZnO) antibacterial agent, and the amount added is also 0.08 parts. The remaining components, ratios and preparation processes are exactly the same as in Example 1.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that the step of ultrasonic dispersion treatment for 30 minutes was completely omitted in step (1), while the other components, proportions and preparation process are exactly the same as in Example 1.

[0044] Comparative Example 5 The difference between this comparative example and Example 1 is that in step (3), the vulcanization temperature is increased to 95°C and the vulcanization time is shortened to 6 hours. The remaining components, proportions and preparation processes are exactly the same as in Example 1.

[0045] Comparative Example 6: The difference between this comparative example and Example 1 is that, in step (1), the number-average molecular weight of the V-PDMS used is 40,000, while the other components, proportions and preparation processes are exactly the same as in Example 1.

[0046] The detailed component ratios (based on 100 parts by weight of V-PDMS) for each embodiment and comparative example are shown in the table below.

[0047] Performance Testing and Results Analysis To comprehensively evaluate the overall performance of the antibacterial composite insulator prepared by this invention, systematic performance tests were conducted on all the above-mentioned embodiments and comparative samples. The test methods are as follows: Thermal stability test: According to GB / T 27761-2011, a thermogravimetric analyzer (TGA) was used to heat the sample from room temperature to 800℃ at a rate of 10℃ / min under a nitrogen atmosphere. The temperature at which the sample weight loss was 5% (T5%) and the residual mass at 700℃ were recorded.

[0048] Dielectric property testing: Using a broadband dielectric spectrometer, the dielectric constant and dielectric loss factor of the samples were measured at 25℃ and a frequency range of 100Hz-1MHz. The rate of change of the dielectric constant was calculated using Comparative Example 1 (pure silicone rubber) as a reference.

[0049] Volume resistivity test: The volume resistivity of the sample was measured using a high-resistivity meter under a 10kV DC excitation voltage and 25℃ conditions, and the percentage improvement compared to Comparative Example 1 was calculated.

[0050] Antimicrobial performance test: Using *Aspergillus niger* as the test strain, the sterilized sample was inoculated with a certain concentration of *Aspergillus niger* spore suspension and cultured for 28 days in an incubator at 28℃ and 90% relative humidity. The antimicrobial rate was calculated by colony counting. The formula for calculating the antimicrobial rate is: R(%) = [(C0 - C) / C0] × 100%, where R is the antimicrobial rate, C0 is the average number of viable colonies after 28 days of culture in Comparative Example 1, and C is the average number of viable colonies after 28 days of culture in the test sample.

[0051] Mechanical performance testing: Using a Shore A hardness tester, the hardness of the finished insulator is tested after curing to ensure that its hardness is stable at 52±2 Shore A.

[0052] All tests were conducted with three parallel samples, and the average value was used as the final result. The test results for each embodiment and comparative example are summarized in the table below.

[0053] Table 1 Summary of performance test results for the examples and comparative examples

[0054] Results analysis: 1. Antibacterial Performance: Example 1 (0.08 wt% antibacterial agent) exhibited the best antibacterial rate (97.5%), which was close to 99.1% of Example 3 (0.15 wt%), indicating that 0.08 wt% was sufficient to achieve highly efficient antibacterial activity. Comparative Example 3 (using ZnO) showed an antibacterial rate of only 62.3%, significantly lower than that of the silver-based composite antibacterial agent, demonstrating the irreplaceable nature of the core component of this invention. The antibacterial rates of Comparative Example 4 (omitted ultrasound) and Comparative Example 5 (high-temperature vulcanization) decreased, indicating that process conditions are crucial for the dispersion and stability of the antibacterial agent.

[0055] 2. Thermal stability: Example 1 exhibited a T5% of 478.6℃ and a residual mass of 25.8%, both superior to Comparative Example 1 (without antibacterial agent) and other comparative examples, indicating that the present invention improves the thermal stability of the material while introducing an antibacterial agent. Comparative Example 6 (low molecular weight V-PDMS) showed a significant decrease in thermal stability, confirming the importance of the molecular weight of the matrix polymer.

[0056] 3. Electrical Performance: Example 1 exhibited the smallest rate of change in dielectric constant (-0.3%), the lowest dielectric loss factor (0.028), and the largest increase in volume resistivity (18.5%), indicating its superior electrical insulation performance. Comparative Example 2 (antibacterial agent exceeding limits) and Comparative Example 4 (ultrasound omitted) showed significantly deteriorated dielectric properties, confirming the adverse effects of antibacterial agent aggregation on electrical performance. Comparative Example 3 (ZnO) showed limited improvement in electrical performance, further highlighting the advantages of silver-based composite antibacterial agents.

[0057] 4. Process robustness: The performance of Example 4 (with a change in pretreatment temperature) is close to that of Example 1, indicating that the process of the present invention has a certain degree of tolerance. However, the performance of Comparative Example 4 (without ultrasound) and Comparative Example 5 (high-temperature vulcanization) decreased, highlighting the necessity of controlling key process steps and parameters.

[0058] In summary, this invention, through specific material combinations and optimized preparation processes, successfully produces composite insulators that combine long-lasting antibacterial properties, excellent electrical insulation performance, high thermal stability, and good mechanical properties. These insulators are particularly suitable for ultra-high voltage transmission lines in humid and hot environments, effectively solving the biological aging problem of silicone rubber insulators.

[0059] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An antimicrobial composite material for wet-heat environment extra-high voltage power transmission, characterized by, By weight, comprising the following components: Vinyl-terminated polydimethylsiloxane 100 parts by weight, Hydrogen-containing silicone oil 3~5 parts by weight, Platinum catalyst 0.8~1.5 parts by weight, Nano-silver / zirconium phosphate silver-loaded composite antibacterial agent 0.01~0.15 parts by weight, Fumed silica reinforcing agent 10~15 parts by weight; The nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is a mixture of nano-silver particles and silver-loaded zirconium phosphate carrier; The nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is added in the form of a dispersion liquid with a solid content of 8%~12%, which is dispersed in the vinyl-terminated polydimethylsiloxane matrix to form a gray homogeneous colloid without precipitation and aggregation; The particle size of the nano-silver particles in the nano-silver / zirconium phosphate silver-loaded composite antibacterial agent is 10~50 nm; The number average molecular weight of the vinyl-terminated polydimethylsiloxane is 45000~55000.

2. A method of preparing the antimicrobial composite material as claimed in claim 1, characterized in that, Comprising the following steps: Pre-treatment of the matrix: mix 100 parts by weight of vinyl-terminated polydimethylsiloxane with 20~30 parts by weight of heptane solvent, heat and stir at 90~100℃ for 1~2 hours to form a pre-crosslinked matrix; Add 10~15 parts by weight of fumed silica reinforcing agent to the pre-crosslinked matrix, stir and mix, then perform ultrasonic dispersion treatment to obtain a homogeneous V-PDMS base material; Nano-dispersion of the antibacterial agent: under inert gas protection, add 0.01~0.15 parts by weight of the nano-silver / zirconium phosphate silver-loaded composite antibacterial agent to the V-PDMS base material, stir at a speed of 400~600 r / min for 1~2 hours to form a uniform colloid; Subsequently, perform vacuum distillation to remove the heptane solvent to obtain an antibacterial agent-V-PDMS nanocomposite; Vacuum blending vulcanization: mix the antibacterial agent-V-PDMS nanocomposite with 3~5 parts by weight of hydrogen-containing silicone oil and 0.8~1.5 parts by weight of platinum catalyst in a vacuum reactor, vacuumize to a vacuum degree of ≤-0.092 MPa, then vulcanize at a temperature of 75~85℃ for 6~12 hours under inert atmosphere to form a three-dimensional crosslinked network structure.

3. The method of claim 2, wherein, In the pre-treatment of the matrix step, the ultrasonic dispersion treatment time is 20~40 minutes.

4. The method of claim 2, wherein, In the nano-dispersion of the antibacterial agent step, the vacuum distillation conditions are: temperature 50~60℃, vacuum degree ≥-0.095 MPa, time 30~50 minutes.

5. The method of claim 2, wherein, In the vacuum blending vulcanization step, after vacuumizing, fill high-purity argon into the vacuum reactor to normal pressure before vulcanization.

6. The method of claim 2, wherein, After the vacuum blending vulcanization step, also include a segmented curing step: inject the vulcanized rubber into a mold, first primary cure at 28~32℃ for 22~26 hours, then final cure at 55~65℃ for 34~38 hours until the elastomer properties are stable, then demold to obtain the finished product.

7. An electrically insulated device, characterized by The power insulating equipment is made of the anti-microbial composite material as claimed in claim 1; the power insulating equipment is an outdoor composite insulator, a cross arm insulator or an electrical equipment outer insulation sleeve for an extra-high voltage transmission line, and the application environment is a hot and humid environment with an annual average temperature of ≥ 26℃ and a relative humidity of ≥ 85%.

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