A method for preparing a novel ultra-high voltage high-performance composite insulating material

Abstract

This invention discloses a method for preparing a novel ultra-high voltage high-performance composite insulating material, belonging to the field of composite insulating material preparation technology. The technical solution includes the following steps: S1, preparing a modified epoxy-silicone rubber composite resin matrix: 40-50 parts by weight of bisphenol A type epoxy resin (E-51) are placed in a reaction vessel, heated to 60-70℃, and continuously stirred at a stirring rate of 300-500 r / min. 10-15 parts by weight of terminal hydroxyl polysiloxane (molecular weight 5000-10000) are added, and the temperature is kept constant for 1.5-2 hours; subsequently, the system temperature is lowered to 40-50℃. The beneficial effects of this invention are: by setting up a resin matrix system of "terminated hydroxyl polysiloxane modified epoxy resin + nano-alumina / boron nitride composite reinforcement," the problem of imbalance between high voltage resistance and aging resistance in existing materials is solved. It exhibits significantly improved dielectric strength, greatly reduced dielectric loss, and excellent high and low temperature cycling performance, meeting the long-life operation requirements of ultra-high voltage equipment.

Description

Technical Field

[0001] This invention relates to the field of composite insulation material preparation technology, specifically to a method for preparing a novel ultra-high voltage high-performance composite insulation material. Background Technology

[0002] With the global energy structure transformation and the surge in demand for cross-regional energy allocation, ultra-high voltage (UHV) power transmission technology has become a core technological support for ensuring the safe and efficient transmission of energy. The stable operation of UHV power transmission systems is highly dependent on the performance of key insulating components such as insulators, insulating supports, and switchgear partitions. As the core substrate of these components, composite insulating materials directly determine the service life and maintenance costs of UHV equipment through their insulation reliability, mechanical load-bearing capacity, resistance to environmental aging, and stability of the manufacturing process. Currently, the mainstream composite insulation materials in the ultra-high voltage (UHV) field are mainly divided into two categories: one is epoxy glass fiber composite material; however, this type of material has obvious defects: ordinary glass fiber has a high density, resulting in heavy insulation components, increasing the load on towers and installation difficulty; moreover, the epoxy resin matrix is ​​prone to aging and embrittlement under outdoor ultraviolet radiation and high and low temperature cycling, the bonding force between the fiber and resin interface decreases, and insulation performance will degrade after years of use, requiring frequent replacement and high maintenance costs. The second is silicone rubber material, which has excellent hydrophobicity and is often used for insulator sheaths, but its mechanical strength is extremely low, requiring composite use with epoxy core rods. Moreover, its dielectric strength and arc resistance are insufficient, and it is prone to forming a conductive water film in industrial pollution and coastal salt spray environments, leading to a decrease in flashover voltage, requiring regular cleaning and maintenance. To address these shortcomings, the industry has explored various improvement solutions: for example, adding nanoparticles to epoxy resin to enhance dielectric properties, but individual nanoparticles are prone to agglomeration and the fiber-resin interface bonding problem remains unresolved; using carbon fiber to replace glass fiber achieves lightweighting, but carbon fiber has high dielectric loss (0.008-0.01 at 1kHz) and is expensive, making large-scale application difficult; although vacuum impregnation has been attempted in terms of process, the curing regime has not been optimized, resulting in internal stress concentration in the material, large batch-to-batch performance fluctuations, and low product qualification rates; Therefore, it is necessary to invent a new method for preparing ultra-high voltage high-performance composite insulation materials. Summary of the Invention

[0003] Therefore, this invention provides a method for preparing a novel ultra-high voltage high-performance composite insulating material to solve the problems in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a novel ultra-high voltage high-performance composite insulating material, characterized by comprising the following steps: S1. Preparation of modified epoxy-silicone rubber composite resin matrix: Take 40-50 parts by weight of bisphenol A type epoxy resin (E-51) and place it in a reaction vessel. Heat to 60-70℃ and stir continuously at a stirring rate of 300-500 r / min. Add 10-15 parts by weight of hydroxyl-terminated polysiloxane (molecular weight 5000-10000) and keep the temperature constant for 1.5-2 h. Then lower the system temperature to 40-50℃ and add 3-5 parts by weight of nano-alumina (particle size 20-50 nm) sequentially. 2-4 parts by weight of nano boron nitride (particle size 50-80nm) are dispersed using an ultrasonic device with a power of 300-500W for 30-40 minutes. Then, 30-35 parts by weight of methyltetrahydrophthalic anhydride, 0.5-1 parts by weight of 2-ethyl-4-methylimidazolium, 0.3-0.5 parts by weight of 2-hydroxy-4-methoxybenzophenone, and 0.1-0.2 parts by weight of polyether-modified siloxane are added and stirred until the system is homogeneous to obtain a composite resin matrix with a viscosity of 500-800mPa·s at 25℃. S2. Pretreatment of composite fiber felt: Select T700 grade carbon fiber (7-10μm in diameter) and basalt fiber (10-15μm in diameter) and mix them at a mass ratio of 30-40:60-70 to form a fiber felt with an areal density of 300-400g / m²; prepare a composite coupling agent solution containing 1-2% by mass of γ-aminopropyltriethoxysilane and 0.5-1% by mass of titanate coupling agent, immerse the fiber felt in the solution, soak it at 60-80℃ for 30-40min, then take out the fiber felt and dry it at 120℃ for 2h. S3. Vacuum-assisted impregnation: The fiber felt pretreated in step S2 is laid flat in the fixture of the impregnation machine. The composite resin matrix prepared in step S1 is injected into the impregnation machine. The vacuum degree of the impregnation environment is controlled at -0.08~-0.09MPa and the temperature is 40-50℃. The impregnation is maintained under these conditions for 20-30 minutes, so that the resin content of the fiber felt reaches 55-65% by mass. S4. Stepwise curing and molding: Transfer the fiber felt impregnated in step S3 to the molding mold, apply a pressure of 10-15 MPa to the mold, first raise the mold temperature to 80-90℃ and keep it at that temperature for 2-3 hours to complete the pre-curing; then raise the mold temperature to 120-130℃ and keep it at that temperature for 4-5 hours to complete the curing; after curing, allow the mold to cool naturally to room temperature, open the mold to demold, and obtain the composite insulation material blank; S5. Post-processing: The surface of the blank obtained in step S4 is polished using a polishing equipment to make the surface roughness Ra≤0.8μm; then, the polished blank surface is treated with a 100-150W plasma treatment equipment for 5-10 minutes to obtain a new type of ultra-high voltage high-performance composite insulation material.

[0005] Preferably, the molecular weight of the hydroxyl-terminated polysiloxane in step S1 is 8000-10000.

[0006] Preferably, in step S1, the mass ratio of nano-alumina to nano-boron nitride is 3:2.

[0007] Preferably, the mass ratio of carbon fiber to basalt fiber in step S2 is 35:65.

[0008] Preferably, the solvent of the composite coupling agent solution in step S2 is a mixture of ethanol and water, and the volume ratio of ethanol to water is 3:1.

[0009] Preferably, the impregnation time in step S3 is 25 minutes, and the resin content of the fiber felt after impregnation is controlled to be 60% by mass.

[0010] Preferably, the pre-curing temperature in step S4 is 85°C, and the post-curing temperature is 125°C.

[0011] Preferably, the plasma treatment power in step S5 is 120W and the treatment time is 8min.

[0012] The beneficial effects of this invention are: 1. This invention sets up a resin matrix system of "hydroxyl-terminated polysiloxane modified epoxy resin + nano alumina / boron nitride composite reinforcement", which solves the problem of imbalance between high voltage resistance and aging resistance of existing materials. It has the effects of significantly improved dielectric strength, greatly reduced dielectric loss, and excellent high and low temperature cycling performance, meeting the long-life operation requirements of ultra-high voltage equipment.

[0013] 2. This invention sets up a "carbon fiber and basalt fiber mixed reinforcement" system, which solves the contradiction between mechanical strength and lightweight of existing materials. It has the effect of high mechanical strength and low overall density, reducing the load-bearing capacity of towers and the difficulty of installation.

[0014] 3. The present invention includes a "composite coupling agent pretreatment of fiber felt" step, which solves the problem of weak fiber-resin interface bonding in existing materials. It has the effects of improving interface peel strength and enhancing the material's crack resistance, thus avoiding the decline in insulation performance due to interface failure during operation.

[0015] 4. The present invention sets up a process combination of "vacuum-assisted impregnation and step-by-step curing", which solves the problems of uneven impregnation, stress concentration and large batch performance fluctuation in the existing process. It has the effects of fewer internal defects in materials, stable batch performance and high product qualification rate, thereby improving production stability and finished product quality.

[0016] 5. The present invention includes a "plasma surface post-treatment" step, which solves the problem of insufficient pollution flashover resistance of existing materials. It has the effects of good surface hydrophobicity and high pollution flashover voltage, reducing the frequency of manual cleaning of UHV lines and lowering operation and maintenance costs. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 This is a schematic diagram of the method flow provided by the present invention. Detailed Implementation

[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1:

[0021] This invention provides a method for preparing a novel ultra-high voltage high-performance composite insulating material. The specific steps are as follows: First, prepare the raw materials, which include: bisphenol A type epoxy resin (E-51): industrial grade, epoxy value 0.51 eq / 100g; hydroxyl-terminated polysiloxane: molecular weight 8000, hydroxyl content 0.15 mmol / g; nano-alumina: particle size 30 nm, purity ≥99.9%; nano-boron nitride: particle size 60 nm, purity ≥99.5%; methyltetrahydrophthalic anhydride: industrial grade, purity ≥98%; 2-ethyl-4-methyl... Imidazole: Industrial grade, purity ≥99%; 2-Hydroxy-4-methoxybenzophenone: Industrial grade, purity ≥98%; Polyether-modified siloxane: Industrial grade, viscosity 500 mPa·s (25℃); T700 grade carbon fiber: diameter 8 μm, tensile strength 4900 MPa; Basalt fiber: diameter 12 μm, tensile strength 3800 MPa; γ-aminopropyltriethoxysilane: Industrial grade, purity ≥98%; Titanate coupling agent (model NDZ-101): Industrial grade, purity ≥98%; Ethanol, deionized water: analytical grade.

[0022] like Figure 1 As shown, the specific steps are as follows: S1. Preparation of modified epoxy-silicone rubber composite resin matrix 45 parts by weight of bisphenol A type epoxy resin (E-51) were placed in a reactor equipped with a stirring device and a temperature control system. Heating was turned on, and the temperature was raised to 65°C. The stirring speed was adjusted to 500 r / min. 12 parts by weight of terminal hydroxyl polysiloxane (molecular weight 8000) were slowly added to the reactor. The reaction was maintained at 65°C for 1.8 h to complete the grafting modification. Subsequently, the reactor temperature was lowered to 45°C, and 4 parts by weight of nano-alumina (30 nm) and 3 parts by weight of nano-boron nitride (60 nm) were added sequentially. A 400W ultrasonic device was then turned on for ultrasonic treatment. The nanoparticles were dispersed for 35 minutes to ensure uniform dispersion. Then, 32 parts by mass of methyltetrahydrophthalic anhydride, 0.8 parts by mass of 2-ethyl-4-methylimidazolium, 0.4 parts by mass of 2-hydroxy-4-methoxybenzophenone, and 0.15 parts by mass of polyether-modified siloxane were added to the reactor. The mixture was stirred at 500 r / min for 30 minutes until the system was homogeneous and transparent. The viscosity of the resin matrix was measured to be 650 mPa·s at 25°C using a rotational viscometer (NDJ-5S), thus obtaining the modified epoxy-silicone rubber composite resin matrix.

[0023] S2, pretreatment of composite fiber felt T700 grade carbon fiber (8 μm in diameter) and basalt fiber (12 μm in diameter) were mixed and woven into a fiber felt with an areal density of 350 g / m² using a braiding machine at a mass ratio of 35:65. A composite coupling agent solution was prepared by mixing ethanol and deionized water at a volume ratio of 3:1, adding γ-aminopropyltriethoxysilane (to a mass fraction of 1.5%) and titanate coupling agent (to a mass fraction of 0.8%) to the mixed solvent, and stirring until completely dissolved. The fiber felt was then immersed in the composite coupling agent solution and placed in a 60°C constant temperature water bath for 35 min. After that, the fiber felt was removed and dried in a 120°C forced-air drying oven for 2 h to remove the solvent, thus completing the pretreatment.

[0024] S3, Vacuum-assisted impregnation The pretreated fiber felt was laid flat in the tooling of the vacuum impregnation machine. The impregnation machine door was closed, the vacuum system was turned on, and the vacuum degree inside the chamber was evacuated to -0.085MPa. The vacuum state was maintained for 10 minutes to remove the air inside the fiber felt. Then, the composite resin matrix prepared in step (1) was injected into the impregnation machine. The temperature inside the impregnation machine chamber was controlled at 45℃, and the vacuum degree of -0.085MPa was maintained for 25 minutes. After the impregnation was completed, the vacuum system was turned off, the fiber felt was taken out, and the resin content was calculated by weighing (weight of fiber felt after impregnation - weight of fiber felt before impregnation). The resin content was measured to be 60% by mass, which meets the requirements.

[0025] S4, Step-by-step curing and molding Transfer the impregnated fiber felt to a stainless steel molding mold, close the mold, and apply a pressure of 12 MPa to the mold through the hydraulic system; turn on the mold temperature control system, first raise the mold temperature to 85℃, and keep it at that temperature for 2.5 hours to complete the pre-curing; then continue to raise the temperature to 125℃ and keep it at that temperature for 4.5 hours to complete the curing; after curing, turn off the heating system and let the mold cool down naturally to room temperature (about 25℃), open the mold, and take out the composite insulation material blank.

[0026] S5, Post-processing The surface of the blank was polished with sandpaper (model 1000#), and the surface roughness Ra of the blank after polishing was measured to be 0.6μm using a surface roughness meter (TR200). Then the blank was placed in a plasma treatment device (model PT-100), the treatment power was set to 120W, and the treatment time was 8min to complete the surface treatment, thus obtaining the new ultra-high voltage high-performance composite insulation material. Example 2:

[0027] Unlike Example 1: Adjustments were made to some of the raw materials: Hydroxyl-terminated polysiloxane: molecular weight 6000, hydroxyl content 0.2 mmol / g; carbon fiber to basalt fiber blending mass ratio: 30:70; nano alumina addition: 3 parts by mass; nano boron nitride addition: 2 parts by mass.

[0028] Some steps have been adjusted: S1, Preparation of modified epoxy-silicone rubber composite resin matrix The reaction temperature was raised to 60°C, the stirring rate was 300 r / min, the amount of hydroxyl-terminated polysiloxane (molecular weight 6000) added was 10 parts by mass, and the reaction time was 1.5 h; the temperature was lowered to 40°C, the ultrasonic power was 300 W, and the dispersion time was 30 min; the amount of other raw materials added was the same as in Example 1, and the viscosity of the resin matrix was measured to be 550 mPa·s at 25°C.

[0029] S3, Vacuum-assisted impregnation Vacuum degree -0.08MPa, temperature 40℃, impregnation time 20min, the resin content was measured to be 55% by mass.

[0030] S4, Step-by-step curing and molding Pressure 10MPa, pre-curing temperature 80℃, heat preservation for 2 hours; post-curing temperature 120℃, heat preservation for 4 hours; The other steps are the same as in Example 1. Example 3:

[0031] Unlike Example 1: Adjustments were made to some of the raw materials: Hydroxyl-terminated polysiloxane: molecular weight 10000, hydroxyl content 0.1mmol / g; carbon fiber and basalt fiber blending mass ratio: 40:60; nano alumina addition: 5 parts by mass, nano boron nitride addition: 4 parts by mass.

[0032] Some steps have been adjusted: S1, Preparation of modified epoxy-silicone rubber composite resin matrix The reaction temperature was raised to 70°C, the stirring rate was 500 r / min, the amount of hydroxyl-terminated polysiloxane (molecular weight 10000) added was 15 parts by mass, and the reaction time was 2 h; the temperature was lowered to 50°C, the ultrasonic power was 500 W, and the dispersion time was 40 min; the amount of other raw materials added was the same as in Example 1, and the viscosity of the resin matrix was measured to be 780 mPa·s at 25°C.

[0033] S3, Vacuum-assisted impregnation With a vacuum of -0.09 MPa, a temperature of 50°C, and an impregnation time of 30 min, the resin content was measured to be 65% by mass.

[0034] S4, Step-by-step curing and molding Pressure 15MPa, pre-curing temperature 90℃, heat preservation for 3 hours; post-curing temperature 130℃, heat preservation for 5 hours; The other steps are the same as in Example 1.

[0035] The composite insulating materials prepared using the methods described in Examples 1-3 above were tested, and the following data were obtained, as shown in the table below:

[0036] As can be seen from the table above, the composite insulating material prepared in Example 1 has the best overall performance.

[0037] Example 1 uses a hydroxyl-terminated polysiloxane (molecular weight 8000), carbon fiber and basalt fiber in a 35:65 blend, and achieves optimal matching of raw materials and processes through precise parameter control, including grafting reaction at 65℃, nano-dispersion at 45℃, vacuum impregnation at -0.085MPa, pre-curing at 85℃ and post-curing at 125℃. The composite insulation material prepared by the method in Example 1 has a dielectric strength of 32.5kV / mm, a tensile strength of 378MPa, a flexural strength of 472MPa, a surface contact angle of 118°, and a high and low temperature cycle decay rate of only 3.2%. This is not only significantly higher than that of Examples 2 and 3, but also perfectly meets the core requirements of ultra-high voltage insulation materials for "high insulation, high mechanical strength, aging resistance and lightweight".

[0038] The above description is merely a preferred embodiment of the present invention. Any person skilled in the art can modify the present invention or modify it into an equivalent technical solution using the technical solutions described above. Therefore, any simple modifications or equivalent substitutions made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A preparation method of a novel extra-high voltage high-performance composite insulating material, characterized in that, It comprises the following steps: S1, preparing a modified epoxy-silicone rubber composite resin matrix: 40-50 parts by mass of bisphenol A type epoxy resin (E-51) is placed in a reaction vessel, heated to 60-70°C, and continuously stirred at a stirring rate of 300-500 r / min, 10-15 parts by mass of hydroxyl-terminated polysiloxane (molecular weight 5000-10000) is added, and the temperature is kept constant for 1.5-2 h; then the temperature of the system is reduced to 40-50°C, 3-5 parts by mass of nano-aluminum oxide (particle size 20-50 nm) and 2-4 parts by mass of nano-boron nitride (particle size 50-80 nm) are added in turn, and dispersed for 30-40 min using an ultrasonic device with a power of 300-500 W, then 30-35 parts by mass of methyltetrahydrophthalic anhydride, 0.5-1 parts by mass of 2-ethyl-4-methylimidazole, 0.3-0.5 parts by mass of 2-hydroxy-4-methoxybenzophenone, and 0.1-0.2 parts by mass of polyether-modified siloxane are added, and stirred until the system is uniform, to obtain a composite resin matrix with a viscosity of 500-800 mPa・s at 25°C; S2, composite fiber felt pretreatment: T700 grade carbon fiber (diameter 7-10 μm) and basalt fiber (diameter 10-15 μm) are mixed and prepared into a fiber felt with a surface density of 300-400 g / m² at a mass ratio of 30-40:60-70; a composite coupling agent solution containing 1-2% by mass of γ-aminopropyltriethoxysilane and 0.5-1% by mass of titanate coupling agent is prepared, the above fiber felt is immersed in the solution, and soaked at 60-80°C for 30-40 min, then the fiber felt is taken out and dried at 120°C for 2 h; S3, vacuum assisted resin infusion: the fiber felt pretreated in step S2 is laid flat in the tooling of the resin infusion machine, the composite resin matrix prepared in step S1 is injected into the resin infusion machine, the vacuum degree of the resin infusion environment is controlled at -0.08~-0.09MPa, and the temperature is controlled at 40-50°C, the fiber felt is infused under the above conditions for 20-30 min, so that the resin content of the fiber felt reaches 55-65% by mass; S4, step curing and forming: the fiber felt after resin infusion in step S3 is transferred to a forming mold, a pressure of 10-15 MPa is applied to the mold, the mold is first heated to 80-90°C, and held for 2-3 h to complete pre-curing; then the mold temperature is raised to 120-130°C, and held for 4-5 h to complete post-curing; after curing, the mold is naturally cooled to room temperature, the mold is opened and demolded, and a composite insulating material blank is obtained; S5, post-treatment: the surface of the blank obtained in step S4 is polished using a polishing device, so that the surface roughness Ra of the blank is ≤0.8 μm; then the surface of the polished blank is treated using a plasma treatment device with a power of 100-150 W for 5-10 min, and a new type of ultra-high voltage high-performance composite insulating material is obtained.

2. The preparation method of the novel extra-high voltage high-performance composite insulating material according to claim 1, characterized in that: The molecular weight of the hydroxyl-terminated polysiloxane in step S1 is 8000-10000.

3. The preparation method of the novel extra-high voltage high-performance composite insulating material according to claim 1, characterized in that: The mass ratio of nano-aluminum oxide to nano-boron nitride in step S1 is 3:

2.

4. The preparation method of the novel extra-high voltage high-performance composite insulating material according to claim 1, characterized in that: The mixing ratio of the carbon fiber and the basalt fiber in the step S2 is 35:

65.

5. The preparation method of the novel extra-high voltage high-performance composite insulating material according to claim 1, characterized in that: The solvent of the coupling agent solution in the step S2 is a mixture of ethanol and water, and the volume ratio of the ethanol to the water is 3:

1.

6. The method of preparing novel extra-high voltage high performance composite insulation material as claimed in claim 1, wherein the said method comprises of the steps of: The impregnation time in the step S3 is 25 min, and the resin content of the fiber felt after impregnation is controlled to be 60% by mass.

7. The method for preparing the novel extra-high voltage high-performance composite insulation material according to claim 1, characterized in that: The pre-curing temperature in the step S4 is 85°C, and the post-curing temperature is 125°C.

8. The preparation method of the novel ultra-high voltage high-performance composite insulating material according to claim 1, characterized in that: The power of the plasma treatment in the step S5 is 120 W, and the treatment time is 8 min.

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