Epoxy composite material for porcelain insulator zero detection equipment and preparation method thereof

Abstract

The invention discloses an epoxy composite material for porcelain insulator zero detection equipment and a preparation method of the epoxy composite material. The epoxy composite material comprises the following components in parts by weight: 100-120 parts of epoxy resin, 100-120 parts of a curing agent, 80-100 parts of a toughening agent, 1-10 parts of an accelerant and 0.1-1 part of filler, wherein the flexibilizer is hyperbranched polyaryletherketone resin, and the filler is a multi-walled carbon nanotube.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and more specifically, to an epoxy composite material for a zero-value insulator detection device and a preparation method thereof. Background Art

[0002] With the rapid development of the UHV power transmission network, porcelain insulators, as the core insulation components of transmission lines, their performance stability is directly related to the safe operation of the power grid. The existence of zero-value insulators (i.e., porcelain insulators that have lost their insulation ability) can lead to accidents such as partial discharge, flashover, and even line breakage. Traditional detection methods such as manual inspection and spark gap method have problems such as low efficiency, poor safety, and inability to detect live. In recent years, detection technologies based on drones equipped with electric field sensors or ultraviolet imagers have been gradually applied, but they still rely on highly sensitive detection equipment, and the stability and anti-interference ability of such equipment in complex electromagnetic environments need to be improved urgently.

[0003] In the field of detection equipment, the low-voltage steep wave detection technology has become a research hotspot by applying a voltage pulse with a rapid rise to the insulator and using the electric field distortion characteristics of zero-value insulators for rapid positioning. However, in existing equipment, key components (such as electrodes and insulating support structures) mostly use traditional epoxy resin composite materials, and the coordination of mechanical strength and electrical performance at various ambient temperatures is insufficient. For example, conventional epoxy resin matrices are prone to partial discharge under high-voltage pulses, and the material toughness decreases at low temperatures, and long-term mechanical stress will cause interface delamination, affecting the equipment life.

[0004] The modification research of existing epoxy composite materials mostly focuses on the optimization of single performance, and the toughness of epoxy composite materials is insufficient at low temperatures. However, low-voltage steep wave detection equipment requires materials to simultaneously have high insulation strength (resistant to instantaneous electric field impact), excellent flexural strength (supporting high-frequency mechanical actions), and heat resistance and cold resistance (adapting to outdoor temperature changes). Traditional material formulations are difficult to meet the working conditions requirements at various ambient temperatures, and lack adaptability design for the special working conditions of detection equipment.

[0005] Therefore, it is of great significance to develop an epoxy composite material with high insulation, mechanical strength, and cold resistance, improve the reliability of detection equipment in extremely cold regions, and promote the development of live detection technology for zero-value insulators. Summary of the Invention

[0006] The main object of the present invention is to overcome the defect of insufficient coordination of mechanical strength and electrical performance at various ambient temperatures existing in the prior art, and provide an epoxy composite material with high mechanical strength that is simultaneously resistant to high temperature and cold for a low-voltage steep wave detection device and a preparation method thereof.

[0007] To achieve the above object, the present invention adopts the following technical solutions: An epoxy composite material for a porcelain insulator zero-check detection device comprises the following components by weight parts: 100-120 parts of epoxy resin, 100-120 parts of curing agent, 80-100 parts of toughening agent, 1-10 parts of accelerator and 0.1-1 part of filler; wherein, the toughening agent is hyperbranched polyaryletherketone resin, and the filler is multi-walled carbon nanotube.

[0008] Further, the epoxy resin includes one or more combinations of bisphenol A epoxy resin, bisphenol F diglycidyl ether, and bis(2,3-epoxypropyl) hexahydrophthalate; the curing agent is an alicyclic amine curing agent, including one or more combinations of m-phenylenediamine, isophorone diamine, cyclohexanedimethanamine, and dicyclopentadiene dimethylamine; the accelerator includes one or more combinations of N-methylpyrrolidone, tetrahydrofuran, and dimethyl sulfoxide.

[0009] Further, the hyperbranched polyaryletherketone resin is obtained by the polymerization reaction of non-coplanar 2,4,6-tris(4-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone with an asymmetric structure under the action of a catalyst potassium carbonate anhydrous. Further, the 2,4,6-tris(4-hydroxyphenyl)pyridine is prepared by the reaction of m-hydroxybenzaldehyde, p-hydroxyacetophenone and ammonium acetate in glacial acetic acid. Further, the molar ratio of the 2,4,6-tris(4-hydroxyphenyl)pyridine to the 2,4'-difluorobenzophenone is (1.6-1.8):1.

[0010] Further, the hyperbranched polyaryletherketone resin is obtained by the polymerization reaction of 4-fluorophenoxyphenol structural unit, 1,3,5-tris(4-fluorophenoxy)benzene and tetrafluoroterephthaloyl chloride under the action of a catalyst triethylamine. Further, the 4-fluorophenoxyphenol structural unit is prepared by the reaction of 4-fluorophenol, bisphenol AF and ammonium acetate in glacial acetic acid. Further, the molar ratio of the 4-fluorophenoxyphenol structural unit, 1,3,5-tris(4-fluorophenoxy)benzene to the tetrafluoroterephthaloyl chloride is (1.0-1.2):1:(1.5-1.8).

[0011] Further, the length of the multi-walled carbon nanotube is <10 μm, the tube diameter is 40-60 nm, the specific surface area is 60-100 m² / g, and the length-diameter ratio is 100-200.

[0012] The present invention also provides a preparation method of the foregoing epoxy composite material, comprising the following steps: 1) drying the epoxy resin, curing agent, hyperbranched polyaryletherketone resin toughening agent, accelerator and multi-walled carbon nanotube filler; 2) Mix 80 - 100 parts of hyperbranched polyaryletherketone resin toughener with N,N - dimethylformamide solvent, and stir until the toughener is completely dissolved; among them, the dosage of the solvent for every 1 g of toughener is 10 - 20 ml; 3) Mix 100 - 120 parts of epoxy resin that has been dried with the toughener solution obtained in step 2), add 0.1 - 1 part of multi - walled carbon nanotube filler, and successively carry out high - speed shear dispersion, ultrasonic treatment and grinding; 4) Add 100 - 120 parts of curing agent to the mixed system obtained in step 3), and add 1 - 10 parts of accelerator, and stir under preset temperature and preset vacuum conditions; 5) Inject the mixture obtained in step 4) into a vacuum degassing device, degas until no bubbles are evolved, and then cure it using a stepped curing process of pre - curing and post - curing; 6) After curing, cool down to below 60 °C for demolding, and carry out surface precision grinding after annealing treatment to obtain the epoxy composite material.

[0013] The beneficial effects of the technical solution of the present invention are reflected in: by introducing multi - walled carbon nanotubes and hyperbranched polyaryletherketone to modify epoxy resin synergistically, a composite material system with both high - temperature resistance, low - temperature toughness and high insulation characteristics is constructed, which can meet the performance requirements of low - voltage steep - wave detection equipment for insulating materials under extreme working conditions. Among them, multi - walled carbon nanotubes are uniformly embedded in the epoxy matrix through a multi - stage dispersion process to form a nano - reinforcement network, which significantly improves the low - temperature mechanical properties and heat - resistant stability of the epoxy composite material through physical dispersion and interfacial interaction; at the same time, the terminal hydroxyl groups of hyperbranched polyaryletherketone form covalent bonds with epoxy groups, and enhance the interfacial bonding through π - π interaction and molecular chain entanglement. Through molecular design, the chemical bonding between the hyperbranched topological structure and epoxy groups is realized, forming a rigid - flexible synergistic three - dimensional interpenetrating network, which focuses on optimizing the interfacial bonding strength of the epoxy composite material while maintaining the high heat - resistance of the material. The two modifiers respectively achieve precise regulation of the properties of the epoxy composite material through physical enhancement and chemical bonding mechanisms, can effectively improve the heat - resistant performance and mechanical properties of the epoxy composite material, and at the same time ensure its insulation performance, providing a reliable guarantee for the production and application of low - voltage steep - wave detection equipment.

[0014] The fluidity of polymer segments is directly related to the glass transition temperature of the polymer. Although multi - walled carbon nanotubes are comparable in size to polymer segments, they are more rigid, thus hindering the migration of polymer segments. The interaction between multi - walled carbon nanotubes and the epoxy matrix restricts the movement of epoxy segments, thereby effectively increasing the glass transition temperature of the epoxy composite material. The addition of hyperbranched polyaryletherketone also has a certain improvement in heat - resistance. Its benzene rings and pyridine rings form a rigid molecular backbone, inhibiting the relaxation of molecular chains at high temperatures. The three - dimensional branched structure hinders the slippage of molecular chains, forming a hyperbranched topological lock, which restricts the movement of epoxy segments.

[0015] In terms of mechanical properties at low temperatures, multi-walled carbon nanotubes are more tightly bonded to the epoxy matrix under low-temperature shrinkage. Through the "bridge effect", they prevent crack propagation and effectively improve its tensile strength and fracture strain. The addition of hyperbranched polyaryletherketone helps the material dissipate energy under impact. The "island-phase separation" of the hyperbranched structure of the material can still absorb impact energy through cavity deformation at low temperatures. Its terminal hydroxyl groups form covalent bonds with epoxy groups, enhancing the interfacial stress transfer efficiency, increasing the impact strength, and improving the mechanical properties at low temperatures.

[0016] At the same time, the nano-enhanced network formed by multi-walled carbon nanotubes and the three-dimensional interpenetrating network assisted by hyperbranched polyaryletherketone show a significant synergistic effect in insulation performance. Physically dispersed multi-walled carbon nanotubes play a role in blocking the conductive path and maintaining the volume resistivity at a relatively high level. Both the ether bonds and ketone bonds of hyperbranched polyaryletherketone have no free electrons, can maintain the stability of the dielectric constant at low temperatures, and at the same time reduce the moisture absorption rate, avoid insulation deterioration caused by humidity, and consolidate the insulation through the chemical inertness of the hyperbranched structure, meeting the dielectric strength requirements under low-voltage steep waves. Specific embodiments

[0017] The present invention will be further described below in conjunction with specific embodiments and examples. The purpose of providing the examples is only for illustration and not for any limitation.

[0018] An epoxy composite material for a porcelain insulator zero-detection device provided by an embodiment of the present invention includes the following components (by weight): Epoxy resin: 100 - 120 parts; Curing agent: 100 - 120 parts; Toughening agent: 80 - 100 parts; Accelerator: 1 - 10 parts; Filler: 0.1 - 1 part.

[0019] Among them, the epoxy resin can be bisphenol A epoxy resin (i.e., bisphenol A diglycidyl ether), and its main synthesis raw materials include bisphenol A, epichlorohydrin, diglycidyl ether, and linear prepolymer. In addition, the epoxy resin can also be bisphenol F diglycidyl ether or bis(2,3-epoxypropyl) hexahydrophthalate; or, a combination of two or more of bisphenol A epoxy resin, bisphenol F diglycidyl ether, and bis(2,3-epoxypropyl) hexahydrophthalate can be used. Those skilled in the art should understand that other epoxy resins with similar properties can also be used, and the present invention does not limit the specific type of epoxy resin.

[0020] The curing agent of the embodiment of the present invention can be an alicyclic amine curing agent, including one or a combination of two or more of m-phenylenediamine, isophorone diamine, cyclohexane dimethylamine, and dicyclopentadienyl dimethylamine. It should be understood by those skilled in the art that other curing agents with similar properties can also be used, and the present invention is not limited to the specific type of curing agent.

[0021] The accelerators in the embodiments of the present invention include one or a combination of two or more of N-methylpyrrolidone (NMP), tetrahydrofuran, and dimethyl sulfoxide. Those skilled in the art will appreciate that other accelerators with similar properties may also be used, and the present invention is not limited to the specific type of accelerator.

[0022] The hyperbranched polyaryletherketone resin in the embodiment of the present invention may be made of existing materials, or may be made of the novel hyperbranched polyaryletherketone resin proposed in the present invention.

[0023] In some specific embodiments, the novel hyperbranched polyaryletherketone resin is obtained by polymerization reaction of specific monomers - non-coplanar 2,4,6-tris(p-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone under the action of anhydrous potassium carbonate as a catalyst. Among them, 2,4,6-tris(p-hydroxyphenyl)pyridine is prepared by reacting m-hydroxybenzaldehyde, p-hydroxyacetophenone and ammonium acetate in glacial acetic acid. It has a large non-coplanar structure that can give the polymer unique properties; 2,4'-difluorobenzophenone preferably has an asymmetric structure, which can reduce the regularity of the polymer chain, thereby destroying the crystallinity and improving the solubility of the hyperbranched polyaryletherketone resin. The 2,4'-difluorobenzophenone used in the embodiment of the present invention can be purchased from conventional chemical reagent suppliers. Anhydrous potassium carbonate as a catalyst can effectively promote the polymerization reaction of 2,4,6-tris(p-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone, and when the amount is about 1.4 times the total weight of the monomers, the reaction can proceed smoothly and obtain a high molecular weight hyperbranched polyaryletherketone resin. The present invention does not specifically limit the source of anhydrous potassium carbonate, and conventional commercially available products can be used. In addition, in an embodiment of the present invention, the amount ratio of 2,4,6-tris(p-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone is preferably (1.6~1.8):1. Within this ratio range, the two can be fully reacted to obtain a hyperbranched polyaryletherketone resin with excellent solubility and thermal stability. The resin can be used as a toughening agent for epoxy resin to significantly improve the mechanical properties and thermal stability of epoxy resin.

[0024] In some other specific embodiments, the novel hyperbranched polyaryletherketone resin is obtained by a polymerization reaction of monomers, namely, 4-fluorophenoxyphenol structural units, 1,3,5-tris(4-fluorophenoxy)benzene, and tetrafluoroterephthaloyl chloride, under the action of a catalyst, triethylamine. Among them, the 4-fluorophenoxyphenol structural units are prepared by reacting 4-fluorophenol, bisphenol AF, and ammonium acetate in glacial acetic acid. It has a fluorine-containing group and a phenoxy structure, which can provide the polymer with low polarity characteristics and good stress dissipation ability. 1,3,5-Tris(4-fluorophenoxy)benzene has three-dimensional branching potential. As the core structural unit of the hyperbranched polymer, it can promote the formation of abundant branching points during the growth of the polymer chain, thereby increasing the free volume of the molecular chain. Tetrafluoroterephthaloyl chloride has two reactive sites, which can effectively promote the formation of the hyperbranched structure and introduce fluorine elements at the polymer end groups, endowing the material with low polarity and excellent dielectric properties. The tetrafluoroterephthaloyl chloride used in the examples of the present invention can be purchased from conventional chemical reagent suppliers. In the examples of the present invention, triethylamine, as a catalyst, can effectively promote the nucleophilic substitution reaction, enabling the monomers to polymerize fully. When the dosage is about 1.2 times the total amount of the three monomers in terms of the amount of substance, the reaction can proceed smoothly and a hyperbranched polyaryletherketone resin modified with fluorine-containing end groups and having a high degree of branching can be obtained. The present invention has no special limitation on the source of the triethylamine, and conventional commercially available products can be used. In addition, in the examples of the present invention, the molar ratio of the 4-fluorophenoxyphenol structural units, 1,3,5-tris(4-fluorophenoxy)benzene, and tetrafluoroterephthaloyl chloride is (1.0~1.2):1:(1.5~1.8). Controlling the molar amounts of the three monomers within this range can enable the monomers to react fully, thereby obtaining a hyperbranched polyaryletherketone resin modified with fluorine-containing end groups having excellent solubility, thermal stability, and toughening effect. As a toughening agent for epoxy resin, this resin can significantly improve the mechanical properties, thermal stability, and dielectric properties of epoxy resin, meeting the use requirements of the porcelain insulator zero detection equipment under harsh environments such as high temperature and high voltage stress.

[0025] In some specific embodiments of the present invention, the relevant dimensional requirements for multi-walled carbon nanotubes include: ① The tube diameter is 40~60 nm: A smaller tube diameter helps to provide a higher specific surface area, increase the physical contact area with epoxy resin, strengthen the interfacial bonding through van der Waals forces and chemical bonding, and at the same time can avoid agglomeration caused by large sizes. A smaller tube diameter is more likely to shrink synergistically with the matrix at low temperatures, reduce interfacial debonding caused by thermal stress, and improve the fracture strain; ② The length of the multi-walled carbon nanotubes < 10 μm: At this length, the epoxy composite material is easy to form a "nano-bridge" effect, effectively transferring stress to the epoxy matrix and improving the low-temperature tensile strength; ③ Specific surface area is 60 - 100 m² / g: The high specific surface area provides more reaction sites, promotes physical / chemical bonding with epoxy resin, and enhances thermal stability. ④ Aspect ratio is 100 - 200: At this aspect ratio, it is beneficial to ensure dispersibility and the mechanical property enhancement effect of the nanotubes. Additionally, a higher aspect ratio helps form a continuous heat conduction path and improve the thermal conductivity of the composite material.

[0026] In the embodiments of the present invention, by using a novel hyperbranched polyaryletherketone resin toughener to modify the epoxy composite material, the heat resistance of the epoxy composite and its mechanical properties at room temperature can be effectively improved. At the same time, multi - walled carbon nanotubes are used as fillers for the epoxy composite to improve the toughness and insulation properties of the material at low temperatures.

[0027] Another embodiment of the present invention also provides a preparation method for the aforementioned epoxy composite material, including the following steps: 1) Place bisphenol A epoxy resin, alicyclic amine curing agent, hyperbranched polyaryletherketone resin toughener, N - methylpyrrolidone promoter, and multi - walled carbon nanotube filler in a drying oven at 60 - 80°C for pretreatment for 2 - 4 h. Among them, the multi - walled carbon nanotube filler also needs to be vacuum - dried at 120°C for 4 - 5 h separately. 2) Mix 80 - 100 parts of hyperbranched polyaryletherketone resin toughener with N,N - dimethylformamide. The amount of N,N - dimethylformamide solution for dissolving each 1 g of toughener is 10 - 20 ml. Stir at a speed of 300 - 350 r / min for 25 - 30 min until the toughener is completely dissolved, and keep the dissolution temperature at room temperature. 3) Mix 100 - 120 parts of epoxy resin that has been dried with the toughener solution obtained in step 2), add 0.1 - 1 part of multi - walled carbon nanotube filler, and successively perform: high - speed shear dispersion at 2000 rpm for 30 - 35 min, ultrasonic treatment at a power of 500 W for 1 h, and three - roll milling machine circulation grinding 3 times. 4) Add 100 - 120 parts of alicyclic amine curing agent and 1 - 10 parts of promoter to the mixed system obtained in step 3), and stir at 80 - 100°C and a vacuum of - 0.1 MPa at a speed of 300 - 350 r / min for 30 - 50 min. 5) Inject the mixture obtained in step 4) into a vacuum degassing device, and degas in a vacuum environment at 40°C and - 0.1 MPa until no bubbles are evolved. 6) Adopt a step - curing process: Pre - curing: 80°C / 2 h + 120°C / 4 h, post - curing: 150°C / 2 h (can be adjusted to 170°C according to the type of curing agent); keep the mold at a pre - heated state of 60°C during the curing process. 7) After the curing is completed, cool down to below 60°C at a rate of ≤2°C / min for demolding. After annealing treatment at 180°C for 1 h, perform surface fine grinding treatment to obtain the epoxy composite material of the embodiment of the present invention.

[0028] In the above preparation method, it also includes the step of preparing a novel hyperbranched polyaryletherketone resin by the polymerization reaction of 2,4,6-tris(p-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone under the action of the catalyst anhydrous potassium carbonate. The specific steps are as follows: 1) Place m-hydroxybenzaldehyde, p-hydroxyacetophenone, 2,4'-difluorobenzophenone, and anhydrous potassium carbonate in a vacuum drying oven and dry at 80°C for 12 hours to ensure the dryness and purity of the raw materials; 2) Add m-hydroxybenzaldehyde (2.5 g), p-hydroxyacetophenone (5.5 g), ammonium acetate (20 g), and glacial acetic acid (100 mL) into a 500 mL three-necked flask in sequence. Under a nitrogen atmosphere, gradually heat the reaction mixture to 120°C and reflux and stir at this temperature for 8 hours; 3) After the reaction is completed, cool the reaction mixture to room temperature and slowly add it to hot deionized water to obtain a light yellow powder precipitate; then filter the precipitate with a Buchner funnel, wash it with deionized water to remove the residual acetic acid, and dry it to obtain a pale yellow solid - 2,4,6-tris(p-hydroxyphenyl)pyridine; 4) Add 2,4,6-tris(p-hydroxyphenyl)pyridine (3 g), 2,4'-difluorobenzophenone (1.2 g), anhydrous potassium carbonate (1.6 g), N-methylpyrrolidone (23 mL), and toluene (7 mL) into a 500 mL three-necked flask; under a nitrogen atmosphere, gradually heat the mixture to the reflux temperature to promote the formation of phenolate, and reflux and react for 4 hours; 5) Raise the temperature to 145°C to remove toluene, and then further raise the reaction temperature to 185°C and continue to react for 3 hours; 6) After the reaction is completed, cool the reaction mixture to room temperature and pour it into deionized water containing hydrochloric acid to obtain a brown powder precipitate; stir well, filter, and wash the precipitate with deionized water to remove the residual inorganic salts and solvents, and then dry it in an oven at 60°C for 12 hours; 7) Dissolve the dried solid in acetone and dry it again to obtain the target product hyperbranched polyaryletherketone resin.

[0029] In the above preparation method of the epoxy composite material, it also includes the step of preparing a novel hyperbranched polyaryletherketone resin by the polymerization reaction of 4-fluorophenoxyphenol structural units, 1,3,5-tris(4-fluorophenoxy)benzene, and tetrafluoroterephthaloyl chloride under the action of the catalyst triethylamine. The specific steps are as follows: 1) Place 4-fluorophenol (1.5 g), bisphenol AF (1.5 g), 1,3,5-tris(4-fluorophenoxy)benzene (1.5 g), tetrafluoroterephthaloyl chloride (3 g), triethylamine (2 g) and sodium fluoride (0.3 g) in a vacuum drying oven and dry at 90 °C for 24 hours to ensure the dryness and purity of the raw materials; 2) Add 4-fluorophenol, bisphenol AF, ammonium acetate (15 g) and glacial acetic acid (100 mL) successively into a 500 mL three-necked flask. Under a nitrogen atmosphere, gradually heat the reaction mixture to 110 °C and reflux and stir at this temperature for 10 hours; 3) After the reaction is completed, cool the reaction mixture to room temperature and slowly add it to hot deionized water to obtain a white powder precipitate; then filter the precipitate with a Buchner funnel, wash it with deionized water to remove the residual acetic acid, and dry it to obtain a pale yellow solid - 4-fluorophenoxyphenol structural unit; 4) Add the above-synthesized monomer 4-fluorophenoxyphenol structural unit, 1,3,5-tris(4-fluorophenoxy)benzene, tetrafluoroterephthaloyl chloride, triethylamine, and tetrahydrofuran (150 mL) successively into a 500 mL three-necked flask. Under a nitrogen atmosphere, gradually heat the mixture to 50 °C to promote the reaction and reflux for 6 hours; 5) Cool the reaction mixture to room temperature and slowly pour it into a large amount of water to precipitate the polymer; then wash the precipitate with ethanol 3 times to remove unreacted monomers and small molecule impurities; finally, dry the washed polymer in a vacuum drying oven at 60 °C to constant weight to obtain a fluorine-terminated modified hyperbranched polyaryletherketone resin.

[0030] The procurement sources of the reagents in the examples and comparative examples of the present invention are shown in Table 1: Table 1 Process properties of epoxy composites

[0031] The following are specific examples and comparative examples: The following Table 2 shows the raw material formulations of the epoxy composites in the specific examples and comparative examples, and Table 2 clarifies the components of each material in different examples and comparative examples.

[0032] Table 2 Epoxy composite material formulation

[0033] The preparation methods of the epoxy composites in the above examples and comparative examples include the following steps: 1) Pre-treat bisphenol A epoxy resin, alicyclic amine curing agent, hyperbranched polyaryletherketone toughening agent, N-methylpyrrolidone accelerator and multi-walled carbon nanotube filler in an oven at 80 °C for 3 h. The multi-walled carbon nanotube filler needs to be dried in vacuum at 120 °C for 4 h separately. 2) Mix the hyperbranched polyaryletherketone toughening agent with N,N-dimethylformamide solvent and stir at 300 r / min for 30 min until the toughening agent is completely dissolved. The dissolution temperature is kept at room temperature. 3) Mix the pre-treated epoxy resin with the toughening agent solution obtained in step 2, add the multi-walled carbon nanotube filler, and successively carry out: high-speed shear dispersion at 2000 rpm for 30 min, ultrasonic treatment at 500 W for 1 h, and three-roll milling for 3 cycles. 4) Add the alicyclic amine curing agent to the mixed system, together with the accelerator, and stir at 350 r / min at 80 °C and a vacuum degree of -0.1 MPa for 40 min. 5) Inject the mixture into a vacuum degassing device and degas in a vacuum environment at 40 °C and -0.1 MPa until no bubbles are evolved. 6) Adopt a stepwise curing process: pre-curing: 80 °C / 2 h + 120 °C / 4 h, post-curing: 150 °C / 2 h (can be adjusted to 170 °C according to the type of curing agent), and keep the mold at a preheated state of 60 °C during the curing process. 7) After curing, cool down to below 60 °C at a rate of 1.5 °C / min for demolding, and perform surface finishing after annealing treatment at 180 °C / 1 h.

[0034] Test Example Test the mechanical properties and thermal properties of the above Examples 1-3 and Comparative Examples 1-3. The standards for each test are as follows: Tensile strength (MPa): GB / T 1040.5-2008 Plastics - Determination of tensile properties - Part 5: Test conditions for unidirectional fibre-reinforced composites. Elongation at break (%): GB / T 1040.5-2008 Plastics - Determination of tensile properties - Part 5: Test conditions for unidirectional fibre-reinforced composites. Glass transition temperature: GB / T 19466.2-2004 Plastics - Differential scanning calorimetry (DSC) - Part 2: Determination of the glass transition temperature. Test the mechanical properties and heat resistance of Examples 1-3 and Comparative Examples 1-3, and test their flexural strength, impact strength, tensile shear strength and glass transition temperature. The test results are shown in Table 3.

[0035] Table 3 Mechanical properties of epoxy composites

[0036] As can be seen from the test results, the mechanical properties and heat resistance of Examples 1-3 at room temperature and low temperature are better than those of Comparative Examples 1-3. In Comparative Example 1, we did not use multi-walled carbon nanotubes and toughening agents for modification, so the toughness of the epoxy composite was insufficient and the glass transition temperature was relatively low. In Comparative Example 2, compared with Comparative Example 1, we used multi-walled carbon nanotubes for modification, which increased the glass transition temperature and significantly increased the elongation at break at low temperature. However, compared with Example 1, the lack of a suitable toughening agent made the material more prone to fracture at low and room temperatures. In Comparative Example 3, we used cyclohexanedimethylamine as the curing agent, which led to a lack of rigidity and insufficient curing degree of the epoxy composite. This was reflected in the performance of the epoxy composite as a decrease in its mechanical strength and heat resistance.

[0037] The insulation performance of the above Examples 1-3 and Comparative Examples 1-3 was tested, and the standards for each test are as follows: Volume resistivity (Ω·m): GB / T 31838.2-2019 Solid insulating materials - Dielectric and resistive properties - Part 2: Resistive properties (DC method) - Volume resistance and volume resistivity; Breakdown field strength (kV / mm): GB / T 1408.1-2016 Electrical strength test methods for insulating materials - Part 1: Tests at power frequency; The electrical properties of Examples 1-3 and Comparative Examples 1-3 were tested, and their volume resistivity and breakdown field strength were measured. The test results are shown in Table 4.

[0038] Table 4 Insulation performance of epoxy composites

[0039] As can be seen from the test results, the insulation performance of Examples 1-3 at room temperature and low temperature is better than that of Comparative Examples 1-3. In Comparative Example 1 and Comparative Example 3, we did not use multi-walled carbon nanotubes for modification, so the volume resistivity of the epoxy composite was relatively low. In Comparative Example 2, compared with Comparative Example 1, we used multi-walled carbon nanotubes for modification, which increased the volume resistivity. However, compared with Example 1, the lack of a suitable toughening agent led to a lower breakdown field strength of the material at low and room temperatures, affecting the insulation performance of the material. In Example 3, by adding hyperbranched polyaryletherketone resin as a toughening agent, the insulation performance of the material at room temperature and low temperature was significantly improved.

[0040] In summary, the present invention uses a novel hyperbranched polyaryletherketone resin toughener to modify epoxy composites, which can effectively improve the heat resistance of epoxy composites and their mechanical properties at room temperature. In addition, the present invention uses multi-walled carbon nanotubes as fillers for epoxy composites to improve the toughness and insulation properties of the materials at low temperatures.

[0041] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those skilled in the technical field to which the present invention belongs, without departing from the concept of the present invention, several equivalent substitutions or obvious variations can be made, and as long as the performance or use is the same, they should all be regarded as belonging to the protection scope of the present invention.

Claims

1. An epoxy composite material for a porcelain insulator zero detection device, characterized in that, It contains the following components by weight parts: 100 - 120 parts of epoxy resin, 100 - 120 parts of curing agent, 80 - 100 parts of toughening agent, 1 - 10 parts of accelerator, and 0.1 - 1 part of filler; wherein, the toughening agent is hyperbranched polyaryletherketone resin, and the filler is multi-walled carbon nanotube.

2. The epoxy composite material according to claim 1, characterized in that, The epoxy resin includes one or a combination of two or more of bisphenol A epoxy resin, bisphenol F diglycidyl ether, and bis(2,3-epoxycyclohexyl) adipate; the curing agent is an alicyclic amine curing agent, including one or a combination of two or more of m-phenylenediamine, isophorone diamine, cyclohexanedimethanamine, and dicyclopentadiene dimethylamine; the accelerator includes one or a combination of two or more of N-methylpyrrolidone, tetrahydrofuran, and dimethyl sulfoxide.

3. The epoxy composite material according to claim 1, characterized in that, The hyperbranched polyaryletherketone resin is obtained by the polymerization reaction of non-coplanar 2,4,6-tris(p-hydroxyphenyl)pyridine and 2,4'-difluorobenzophenone with an asymmetric structure under the action of the catalyst anhydrous potassium carbonate.

4. The epoxy composite material according to claim 3, characterized in that, The 2,4,6-tris(p-hydroxyphenyl)pyridine is prepared by the reaction of m-hydroxybenzaldehyde, p-hydroxyacetophenone, and ammonium acetate in glacial acetic acid.

5. The epoxy composite material according to claim 3, characterized in that, The molar ratio of the 2,4,6-tris(p-hydroxyphenyl)pyridine to the 2,4'-difluorobenzophenone is (1.6 - 1.8):

1.

6. The epoxy composite material according to claim 1, characterized in that, The hyperbranched polyaryletherketone resin is obtained by the polymerization reaction of 4-fluorophenoxyphenol structural unit, 1,3,5-tris(4-fluorophenoxy)benzene, and tetrafluoroterephthaloyl chloride under the action of the catalyst triethylamine.

7. The epoxy composite material according to claim 6, wherein, The 4-fluorophenoxyphenol structural unit is prepared by the reaction of 4-fluorophenol, bisphenol AF, and ammonium acetate in glacial acetic acid.

8. The epoxy composite material according to claim 6, wherein, The molar ratio of the 4-fluorophenoxyphenol structural unit, 1,3,5-tris(4-fluorophenoxy)benzene to tetrafluoroterephthaloyl chloride is (1.0 - 1.2):1:(1.5 - 1.8).

9. The epoxy composite material according to claim 1, wherein, The multi-walled carbon nanotubes have a length < 10 μm, a diameter of 40 - 60 nm, a specific surface area of 60 - 100 m² / g, and an aspect ratio of 100 - 200.

10. The preparation method of the epoxy composite material according to any one of claims 1-9, characterized in that, It includes the following steps: 1) Dry the epoxy resin, curing agent, hyperbranched polyaryletherketone resin toughening agent, accelerator, and multi-walled carbon nanotube filler. 2) Mix 80 - 100 parts of hyperbranched polyaryletherketone resin toughening agent with N,N-dimethylformamide solution and stir until the toughening agent is completely dissolved; wherein, the amount of the solution used for each 1 g of the toughening agent is 10 - 20 ml. 3) Mix the dried 100 - 120 parts of epoxy resin with the toughening agent solution obtained in step 2), add 0.1 - 1 part of multi-walled carbon nanotube filler, and perform high-speed shear dispersion, ultrasonic treatment, and grinding in sequence. 4) Add 100 - 120 parts of curing agent to the mixed system obtained in step 3), and add 1 - 10 parts of accelerator, and stir under preset temperature and preset vacuum conditions. 5) Inject the mixture obtained in step 4) into a vacuum degassing device, degas until no bubbles are evolved, and then cure it by a stepwise curing process of pre-curing and post-curing. 6) After curing is completed, cool down to below 60°C and demold. After annealing treatment, perform surface fine grinding to obtain the epoxy composite material.

Images