Special engineering plastic modified filler, composite material and preparation method

Abstract

The invention relates to the technical field of epoxy resin composite material modification, and provides a special engineering plastic modified filler, a composite material and a preparation method. The special engineering plastic particles are firstly subjected to ball-milling thinning treatment in which a urea solution participates, so that particle size refinement and surface grafting of amino groups are realized; and then secondary grafting is performed through a silane coupling agent, and a siloxane active group is further introduced, so that the interfacial compatibility between the filler and the epoxy resin prepolymer is remarkably improved. The modified filler is added into a bisphenol A type epoxy resin system according to the mass fraction of 0.5%-10%, and the composite material which is uniform in interface, free of filler sedimentation and stable in three-dimensional cross-linked structure can be obtained in combination with a specific curing agent ratio and a two-stage curing system. The tensile strength, the elongation at break, the bending strength, the dielectric strength, the volume resistivity and the like of the material are remarkably improved compared with those of an unmodified filler and an unfilled system, and particularly, the comprehensive performance is optimal when the filler addition amount is about 3%.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin composite material modification technology, specifically relating to a special engineering plastic modified filler, composite material, and preparation method. Background Technology

[0002] Epoxy resin, as a typical thermosetting polymer material, has long been widely used in the field of electrical equipment manufacturing, especially in scenarios requiring integral casting and long-term insulation support, such as dry-type reactors, instrument transformers, bushings, and power electronic packaging. Its cured product can form a dense three-dimensional cross-linked structure, exhibiting excellent insulation properties, dimensional stability, heat resistance, and moldability. With the development of power systems towards higher voltage and larger capacity, the operating conditions of epoxy resin in actual service are becoming increasingly harsh, with significantly increased electric field strength, thermal stress, mechanical stress, and environmental aging factors. Industry statistics show that a considerable proportion of operational failures in electrical equipment are related to the degradation of the mechanical properties of insulating materials, the decline in dielectric properties, or material cracking caused by environmental coupling effects. Therefore, improving the comprehensive performance of epoxy resin materials has become a key prerequisite for ensuring the long-term reliable operation of high-voltage equipment.

[0003] In research on improving the performance of epoxy resin materials, filler reinforcement, toughening techniques, and interface structure optimization are commonly employed to enhance mechanical strength, electrical properties, or long-term service stability without significantly altering the basic material system. In recent years, some high-performance engineering plastics, due to their high dielectric properties, good heat resistance, and certain toughness, have been considered promising functional filler materials. However, in practical applications, the inherent properties of engineering plastics often differ significantly from those of epoxy resin systems, including density, interfacial energy, surface chemical structure, and coefficient of thermal expansion. These differences can easily lead to problems such as dispersion difficulties, weak interfacial bonding, or filler sedimentation during resin mixing and curing. Especially in applications requiring high electrical insulation and mechanical properties, interfacial inhomogeneity within the material can cause localized stress concentration and dielectric field distortion, thereby affecting overall performance.

[0004] Furthermore, with the increasing size and structural complexity of high-voltage equipment, the overall dimensions of epoxy resin castings are constantly expanding, placing higher demands on the material's internal uniformity, crack resistance, and long-term stability. Traditional fillers have limited dispersion stability in resin, significantly affected by factors such as particle size, specific surface area, and interface state. This can lead to varying degrees of agglomeration or sedimentation during curing, creating non-uniform regions within the material and thus reducing key mechanical and electrical performance indicators. For high-end electrical equipment, these defects can potentially evolve into crack initiations during long-term operation, affecting the overall reliability and lifespan of the system.

[0005] Current technologies for improving epoxy resin performance still face several common challenges: for example, large filler particle sizes can disrupt the structural uniformity of the resin system; significant differences in properties between the filler and the resin itself result in insufficient interfacial bonding; and the anti-aging properties of materials under complex service environments fail to meet the requirements for long-life applications. These problems have long existed in the industry and are major obstacles limiting further performance improvements in epoxy resin insulation materials. How to achieve higher performance margins in resin composites in terms of mechanical, electrical, and long-term stability without altering existing equipment manufacturing systems has become a crucial and ongoing focus in the field of electrical materials. Summary of the Invention

[0006] The purpose of this invention is to solve the problems in the prior art where the particle size of special engineering plastic fillers is large and the interfacial compatibility is poor, which leads to easy sedimentation in epoxy resin and makes it difficult to improve mechanical and electrical properties.

[0007] The objective of this invention is achieved through the following technical solution: A special engineering plastic modified filler, wherein the modified filler is obtained by a two-stage modification of special engineering plastic powder through an amino introduction step and a silane coupling agent grafting step, wherein: Amino introduction step: The special engineering plastic powder is mixed with an active amino compound and a solvent and then subjected to 6 to 8 ball milling-cooling cycles to achieve particle thinning and introduce amino groups on the particle surface. Aminated special engineering plastic powder is obtained by centrifugation. Silane coupling agent grafting step: The aminated special engineering plastic powder is refluxed with 15% to 25% silane coupling agent solution at 60°C to 80°C to form a siloxane active structure on the surface. The modified filler obtained is in powder form after vacuum drying, with a particle size of less than 1000 mesh.

[0008] Preferably, the special engineering plastic includes at least one of polyetheretherketone, polysulfone, polyarylate, or liquid crystal polymer filled with short glass fibers.

[0009] Preferably, the silane coupling agent includes KH550 or KH560.

[0010] Based on the same inventive concept, this invention also provides a special engineering plastic modified epoxy resin composite material, which adopts the following curing and mixing system in parts by weight, the components and proportions of which include: 100 parts epoxy resin; 70-100 parts of reversible covalent anhydride curing agent; The special engineering plastic modified filler is used in parts of 0.5 to 10 parts. Accelerator 0.5–3 parts; The modified filler forms interfacial covalent bonds with the epoxy resin, thereby improving the elongation at break and dielectric strength of the cured product.

[0011] Preferably, the addition ratio of the special engineering plastic filler is 3 to 5 parts.

[0012] Preferably, the epoxy resin includes bisphenol A type epoxy resin E-51 or CLP-128.

[0013] Preferably, the accelerator comprises 2,4,6-tris(dimethylaminomethyl)phenol.

[0014] Preferably, the reversible covalent anhydride system curing agent is 85 parts.

[0015] Preferably, the promoter is 1 part.

[0016] Based on the same inventive concept, the present invention also provides a method for preparing a special engineering plastic modified epoxy resin composite material, the method comprising the following steps: Prepare epoxy resin, reversible covalent anhydride curing agent, special engineering plastic modifier, and accelerator according to the proportions described above; Epoxy resin, reversible covalent anhydride curing agent, and special engineering plastic modified filler are mixed in a vacuum environment of 60℃~70℃ to form a primary mixture; An accelerator is added to the primary mixture, and the mixture is stirred evenly under vacuum to obtain a secondary mixture; The secondary mixture is poured into a mold and cured in multiple stages to obtain the special engineering plastic modified epoxy resin composite material.

[0017] Preferably, the multi-stage curing includes: curing at 70°C for 2-3 hours, and then curing at 140°C-150°C for 5-6 hours.

[0018] Preferably, the vacuum environment includes mixing within a vacuum casting machine.

[0019] The "reversible covalent anhydride system curing agent" used in this invention is composed of an anhydride component and a sulfur-containing active component. The anhydride component is limited to methylnadic anhydride, responsible for the main ring-opening and cross-linking reactions of the epoxy resin. The sulfur-containing active component is selected from cystine, cystine dimethyl ester, or dithiodipropionic acid, and its molecules contain disulfide bonds, providing reversible exchange cross-linking sites in the curing network. The long-chain structure of the curing agent enhances the material's flexibility and stress relief capabilities.

[0020] The reversible covalent anhydride curing agent aims to introduce long-chain structural units with dynamic exchange capabilities into the epoxy resin curing network, thereby significantly improving the toughness and crack resistance of the material while ensuring the mechanical strength of the system. The curing agent system of this invention uses methylnadic anhydride (MNA) as the main anhydride and introduces specific sulfur- or amino-containing chain-extending and cross-linking structural units based on reversible covalent bonds. The inventors have verified that the mixed anhydride curing system composed of MNA and small molecule compounds containing –S–S– or –NH– groups can form bonding sites with dynamic exchange characteristics in the cured structure, ensuring that the cross-linked network contains a certain number of reversible covalent bonds.

[0021] In the specific formulation, the preferred curing agent system is a mixture of MNA and cystine at a mass ratio of 80:20. Cystine molecules contain disulfide bonds (–S–S–), which possess dynamic and reversible exchange capacity under high-temperature conditions. When these bonds are embedded in the cured network, they form "dynamic cross-linking points," enabling bond exchange and stress release during thermal stress concentration. Therefore, in high-temperature operating environments such as dry-type reactors, the reversible covalent bonds result in a slight decrease in stiffness at high temperatures, further improving the toughness of the dry-type reactor encapsulation. The product's crack resistance and crack propagation inhibition performance are significantly superior to traditional anhydride curing systems, meeting the needs of dry-type reactors to improve heat dissipation during energized operation and reduce encapsulation cracking failures under long-term service conditions.

[0022] In addition to cystine, the inventors further pointed out that other sulfur- or amino-containing small molecules with reversible exchange characteristics can also be used to replace or partially replace cystine, including dimethyl cystine ester and dithiodipropionic acid. The dimethyl cystine ester molecular chain also retains disulfide bonds and end-group structures that react with epoxy groups. Esterification treatment can reduce molecular rigidity, giving the cured network higher ductility, suitable for applications requiring a balance between dielectric strength and flexibility. The dithiodipropionic acid molecule contains dynamically exchangeable disulfide bonds and has relatively long chain segments. Its introduction provides longer flexible chain segments, improving the overall elongation at break of the cured product. All of the above sulfur-containing compounds can serve as reversible covalent bond units, with an anhydride component: sulfur-containing active component = 80:20 (mass ratio) as the preferred ratio. This ratio balances the curing reaction rate, crosslinking density, and reversible exchange efficiency of the dynamic network, achieving a better balance between dielectric properties, heat resistance, and mechanical flexibility in the final cured product.

[0023] In practical applications, the inventors further verified that the mass ratio of MNA to the reversible covalent component can also be adjusted according to the desired performance. For example, when it is necessary to improve the material's flexibility and crack resistance, the proportion of the reversible component can be appropriately increased to 30%–40%, such as 7:3 or 6:4, to increase the density of exchangeable bonds in the network; when higher crosslinking density, dielectric strength, or dimensional stability is required, the reversible component can be adjusted to 10%–20%, such as 9:1 or 8:2, to maintain a higher overall modulus. Through multiple sets of experiments, the inventors confirmed that the performance is most balanced when the proportion of the reversible component is 20% (MNA:reversible component ratio is 80:20), therefore this ratio is the preferred embodiment.

[0024] The reversible covalent anhydride curing agent forms a cross-linked network with the epoxy resin during curing. The reversible bond units provide potential chain segment mobility, enabling the material to exhibit flexibility and stress relief behavior at higher temperatures. At normal operating temperatures, it maintains a stable three-dimensional structure without affecting the material's dielectric strength and mechanical properties. This structural characteristic is highly compatible with the operational requirements of dry-type reactors in environments with high temperatures and electromagnetic vibrations, significantly reducing internal thermal stress accumulation, inhibiting crack initiation and propagation, and thus improving the overall reliability and service life of the material.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a dual modification route of "particle size reduction—surface activation—interfacial reactivity enhancement" to modify special engineering plastic fillers, enabling them to achieve stable dispersion and effective interfacial bonding in epoxy resin systems, thereby generating a series of beneficial technical effects with a clear causal chain. First, ball milling involving urea physically thins the engineering plastic particles, significantly reducing particle size and increasing specific surface area, exposing more potential bonding sites on the particle surface. During the ball milling-cooling cycle, the amino groups in the urea molecules can contact and remain on the particle surface under high-energy mechanical action, transforming the surface from an inert structure to an active structure. The reduced particle size decreases the sedimentation tendency of the filler due to density differences, while the introduction of amino groups provides the possibility for subsequent chemical or weak chemical reactions with the epoxy resin system, thus solving the problem of the original special engineering plastic particles' difficulty in bonding with the resin interface.

[0026] Subsequently, a second-stage chemical grafting process is performed on the activated plastic particles using a silane coupling agent, forming an interfacial reaction layer with a siloxane structure on the particle surface. One end of this layer can undergo a condensation reaction with the amino groups on the engineering plastic surface, while the alkoxy groups at the other end can form covalent or semi-covalent bonds with epoxy resin or reversible covalent anhydride curing agents in the curing system. Through this bridging effect of the two-end structure, engineering plastic particles that are originally difficult to "wet" by epoxy groups can be successfully embedded into the three-dimensional cross-linked network of the resin, significantly improving the dispersion uniformity and interfacial chemical adhesion of the particles in the curing system. Compared to untreated particles, this interfacial layer effectively inhibits sedimentation behavior before and after curing, resulting in a more uniform microstructure throughout the system and preventing stress concentration in weak interfacial regions.

[0027] After thorough mixing and curing at the optimized ratio, the modified filler is distributed stably and uniformly within the epoxy resin crosslinking network, effectively transferring the high strength and high dielectric properties of the filler itself to the composite material as a whole. The results show that when the filler mass fraction is approximately 3%, the tensile strength, flexural strength, elongation at break, impact performance, and dielectric strength of the composite material are significantly superior to both the unmodified filler system and the unfilled system. This performance improvement stems from two aspects: firstly, at the microstructural level, the uniform distribution of the filler eliminates local stress concentration, making it less prone to macroscopic cracking under load-bearing limits; secondly, at the interfacial level, the effective bonding between the filler and the resin allows stress to be transferred across the interface, avoiding the "debonding-void-fracture" evolution pattern commonly seen in traditional engineering plastic fillers.

[0028] Furthermore, since the modified filler can participate in or assist in the formation of the epoxy resin curing network, it does not form obvious interface defects during the curing process, thus maintaining stable and improved electrical properties of the cured body. The increase in volume resistivity and dielectric strength indicates a more uniform electric field distribution within the composite material, reduced interface defects, and significantly enhanced resistance to electrical densification and dielectric breakdown under long-term service conditions in ultra-high voltage equipment. In summary, this invention, through dual modification of special engineering plastic particles, achieves a complete logical closed loop of "technical characteristics—interface mechanism—performance improvement," resulting in significant and verifiable improvements in the mechanical, electrical, and long-term stability of epoxy resin composite materials, demonstrating its potential application in high-requirement electrical equipment. Detailed Implementation

[0029] The technical solution will be further described below with reference to specific embodiments to help understand the content of the present invention.

[0030] In the following examples, "curing agent" is an abbreviation for "reversible covalent anhydride system curing agent"; PEEK powder refers to a powdered special engineering plastic obtained by pulverizing or spray granulating polyetheretherketone (PEEK) resin. PEEK is a special engineering plastic with high temperature resistance, chemical corrosion resistance, and excellent mechanical properties, and is commonly used in aerospace, military, electrical insulation, and high-temperature components.

[0031] Example 1 A special engineering plastic modified filler, wherein the modified filler is obtained by a two-stage modification of special engineering plastic powder through an amino introduction step and a silane coupling agent grafting step, wherein: Amino introduction step: The special engineering plastic powder is mixed with an active amino compound and a solvent and then subjected to 6 to 8 ball milling-cooling cycles to achieve particle thinning and introduce amino groups on the particle surface. Aminated special engineering plastic powder is obtained by centrifugation. Silane coupling agent grafting step: The aminated special engineering plastic powder is refluxed with 15% to 25% silane coupling agent solution at 60°C to 80°C to form a siloxane active structure on the surface. The modified filler obtained is in powder form after vacuum drying, with a particle size of less than 1000 mesh.

[0032] The special engineering plastics include at least one of polyetheretherketone, polysulfone, polyarylate, or liquid crystal polymers filled with short glass fibers.

[0033] The silane coupling agent includes KH550 or KH560.

[0034] A typical implementation process is as follows: (1) Place the special engineering plastics, urea and deionized water solution in a planetary ball mill and stir at 300 rpm for 2 hours. Then place it in a refrigerator to cool and stand for 1 hour as one cycle. Perform a total of 8 cycles. Then place the special engineering plastic powder in a centrifuge for centrifugation and remove the precipitate.

[0035] (2) Dry the special engineering plastic at 70°C for 24 hours to remove urea solvent and water, grind it and then screen it through a 1000-mesh sieve to obtain modified special engineering plastic powder.

[0036] (3) Add 20% KH560 silane coupling agent solution to special engineering plastic powder, stir at 600 rpm for 30 min, pour into a flask and heat under reflux at 70°C and 600 rpm for 3 hours.

[0037] (4) The final product is vacuum dried at 70°C for 24 hours in a vacuum environment to obtain the special engineering plastic modified filler.

[0038] The special engineering plastic modified filler provided by this invention achieves overall performance improvement from particle structure, interfacial chemistry to dispersion behavior through dual surface modification of amino groups and silane coupling agents. Firstly, in the amino group introduction step, the ball milling-cooling cycle of the special engineering plastic powder and the active amino compound not only thins the particles due to mechanical shearing and significantly increases their surface area, but also, due to the energy excitation effect of the amino compound during ball milling, enables it to be directionally embedded or adsorbed onto the particle surface in a "mechanical-chemical" manner, thereby forming primary amino active sites on the powder surface. These amino sites provide reaction anchoring points for the subsequent silane coupling agent, allowing silane molecules to form stable chemical bonds with the aminated surface through condensation reactions, while simultaneously constructing an interfacial active shell with a siloxane structure on the outer layer.

[0039] In the silane coupling agent grafting step, silane molecules such as KH550 or KH560 undergo hydrolysis and condensation reactions at 60℃–80℃, forming covalent bonds with aminated particles through the amino, epoxy, or alkoxy groups in their end groups, thus creating siloxane segments that possess both polarity and flexibility. This structure not only improves the inherent hydrophobicity, inertia, and low interfacial activity of specialty engineering plastic powders but also establishes an active bridging layer on its surface that can further chemically react with epoxy resin, transforming the modified particles from "inert fillers" into "reactive fillers participating in interface construction." During this process, the flexible skeleton of the siloxane segments can alleviate the hardness difference between the filler and the resin, reduce stress concentration, and make the interfacial stress transmission more uniform, thereby improving the fracture toughness and mechanical stability of the composite system.

[0040] In summary, through the synergistic effect of amino group introduction and silane grafting, the special engineering plastic modified filler of this invention not only achieves surface chemical activation and polarity enhancement, improving its dispersibility in epoxy systems, but more importantly, the modified filler can form stable interfacial covalent bonds with the resin matrix during the curing reaction, fundamentally enhancing interfacial bonding strength and significantly improving the elongation at break, dielectric strength, and long-term service reliability of the composite material. This modification mechanism based on interfacial reaction gives the filler of this invention high performance, reactivity, and structural tunability, demonstrating significant technical advantages and application value.

[0041] Example 2 Based on the same inventive concept, this invention also provides a special engineering plastic modified epoxy resin composite material, which adopts the following curing and mixing system in parts by weight, the components and proportions of which include: 100 parts epoxy resin; 70-100 parts of reversible covalent anhydride curing agent; The special engineering plastic modified filler is used in parts of 0.5 to 10 parts. Accelerator 0.5–3 parts; The modified filler forms interfacial covalent bonds with the epoxy resin, thereby improving the elongation at break and dielectric strength of the cured product.

[0042] Preferably, the addition ratio of the special engineering plastic filler is 3 to 5 parts.

[0043] Preferably, the epoxy resin includes bisphenol A type epoxy resin E-51 or CLP-128.

[0044] Preferably, the accelerator comprises 2,4,6-tris(dimethylaminomethyl)phenol.

[0045] Preferably, the reversible covalent anhydride system curing agent is 85 parts, wherein the anhydride component is methylnadic anhydride, the sulfur-containing active component is cystine, and the ratio of methylnadic anhydride to cystine is 80:20.

[0046] Preferably, the promoter is 1 part.

[0047] A typical implementation process is as follows: (1) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:5, the mixture is stirred in a water bath at 70°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0048] (2) Add the accelerator according to the ratio of epoxy resin: accelerator = 100:1 and stir at 60°C for 30 min. Pour into the mold and then put into the oven at 70°C for 3 hours to cure. Finally, continue to cure at 145°C for 6 hours and take out the sample to obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0049] This invention improves the mechanical and aging resistance characteristics of epoxy resin while enhancing its crack resistance. The epoxy resin filler modification method can further improve the mechanical and aging resistance parameters of the cured epoxy resin crosslinking network with a significant increase in elongation at break. This results in epoxy resin products cast with this formula exhibiting superior long-term stability characteristics and has a wide range of applications in fields such as dry reactor encapsulation and casting.

[0050] Example 3 Based on the same inventive concept, the present invention also provides a method for preparing a special engineering plastic modified epoxy resin composite material, the method comprising the following steps: Prepare epoxy resin, reversible covalent anhydride curing agent, special engineering plastic modified filler, and accelerator according to the proportions described in Example 2; Epoxy resin, reversible covalent anhydride curing agent, and special engineering plastic modified filler are mixed in a vacuum environment of 60℃~70℃ to form a primary mixture; An accelerator is added to the primary mixture, and the mixture is stirred evenly under vacuum to obtain a secondary mixture; The secondary mixture is poured into a mold and cured in multiple stages to obtain the special engineering plastic modified epoxy resin composite material.

[0051] Preferably, the multi-stage curing includes: curing at 70°C for 2-3 hours, and then curing at 140°C-150°C for 5-6 hours.

[0052] Preferably, the vacuum environment includes mixing within a vacuum casting machine.

[0053] In this embodiment, the selected filler modifier is an active amino raw material such as urea and ammonia. The first-stage modification method is ball milling modification, and the second-stage modification method is mixing and stirring with silane coupling agent. The selected modifiers are KH560, KH550, etc.

[0054] The special engineering plastic modified filler is added at a content of 0.5%-10% of the epoxy resin, preferably 3%-5%. It should be noted that this scheme does not disregard other technical parameters of the epoxy resin, but rather aims to improve its electrical and insulation properties as much as possible while maintaining its own stable performance.

[0055] Step (a) involves thinning the special engineering plastic particles by ball milling. During this process, urea is added as a modified filler, and dichloromethane is used as a solvent. The mixture is stirred at 300 rpm for 2 hours, then cooled and allowed to stand in a refrigerator for 1 hour, constituting one cycle. A total of 6-8 cycles (preferably 8 cycles) are performed for amino grafting modification. After centrifugation, solvent evaporation, and particle sieving, 15%-25% of a silane coupling agent (preferably 20%) is added, and the mixture is stirred to perform grafting. The solvent is evaporated at 60℃~80℃ (preferably 70℃). After complete solvent removal, the modified special engineering plastic filler is in powder form. Step (b) involves reacting the curing agent with the industrial epoxy resin material, preferably CLP-128 type bisphenol A epoxy resin. The mixture is stirred in a vacuum environment and a reversible covalent anhydride system curing agent and filler are added. After rapid and uniform stirring, an accelerator is added quickly. The mixture is then poured into the corresponding material test mold under vacuum and cured.

[0056] A typical but non-limiting method for preparing epoxy resin materials filled with modified fillers from specialty engineering plastics includes the following steps: Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix thoroughly, stir at 300rpm for 2 hours, then cool and let stand in a refrigerator for 1 hour as one cycle, for a total of 8 cycles. Then, place the modified PEEK powder in a centrifuge and centrifuge at 7000rpm for 10 minutes, collecting the precipitate. Repeat the centrifugation process 8 times. The resulting white solid is dried and then sieved to obtain PEEK powder particles with the required particle size.

[0057] 10g of modified PEEK powder was mixed with 20% KH560 silane coupling agent solution and stirred at 600rpm for 30min. The mixture was then poured into a flask and heated under reflux at 70℃ and 600rpm for 3 hours to obtain a modified PEEK powder solution. The final product was then vacuumed at 70℃ for 24 hours.

[0058] The epoxy resin, reversible covalent anhydride system curing agent, and special engineering plastic modified filler were mixed in a ratio of 100:85:5. The mixture was then stirred in a water bath at 70°C for 2 hours to ensure thorough mixing, followed by stirring under vacuum conditions in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent was methyl nadic anhydride, and the sulfur-containing active component was dimethyl cysteine, with a methyl nadic anhydride:dimethyl cysteine ​​ratio of 90:10.

[0059] Two parts of accelerator were added, and the mixture was vacuum stirred and poured into a mold. Then, it was placed in an oven and cured at 70°C for 3 hours. Finally, the sample was removed after curing at 145°C for 6 hours, and the epoxy resin composite material filled with special engineering plastic modified filler was obtained.

[0060] Remove the epoxy resin test specimen from the mold and test the epoxy resin composite material sample according to the national standard.

[0061] The special engineering plastic filler raw materials prepared by the modification process of this invention are all commercially available, and the epoxy resin material directly uses the most common bisphenol A type epoxy resin in industry.

[0062] The entire modification process of this invention does not involve complex filtration or reaction conditions, and the modified special engineering plastic filler powder-filled epoxy resin composite material achieves a significant improvement in mechanical properties.

[0063] In this invention, the significant improvement in mechanical properties stems from the superior interfacial compatibility between the modified filler particles and epoxy resin. This effectively reduces particle agglomeration during tensile testing of special engineering plastic particles, delaying the breakage of the three-dimensional cross-linked network during extreme mechanical property tests, thereby enhancing the mechanical properties of the epoxy resin composite material. The resulting epoxy resin composite material exhibits improved tensile strength and toughness while maintaining other core technical parameters, making it highly promising for application as a support and outer insulating material, preventing equipment cracking and inter-turn short circuits caused by cracking and extreme stress environments.

[0064] This invention effectively improves the interfacial compatibility between special engineering plastic fillers and epoxy resins by thinning particles and adding active groups to the surface of the filler. The filler surface is successfully grafted with amino and siloxane groups, which can react with epoxy resins during the curing process. Relying on the excellent mechanical and electrical properties of the filler itself, the epoxy resin composite material prepared by this method has better electrical properties and is suitable for the field of electrical equipment manufacturing with high requirements for mechanical and insulation properties, thereby improving the crack resistance and long-term service characteristics of the equipment.

[0065] Example 4 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 8 cycles are performed.

[0066] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The lower layer of precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0067] (3) Add 20% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 70℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 70℃ for 24 hours.

[0068] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:0.5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is dithiodipropionic acid, with a ratio of methylnadic anhydride:dithiodipropionic acid = 60:40.

[0069] (5) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven to cure at 70°C for 3 hours, and finally continue to cure at 145°C for 6 hours to take out the sample and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0070] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0071] Example 5 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 8 cycles are performed.

[0072] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The lower layer of precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0073] (3) Add 20% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 70℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 70℃ for 24 hours.

[0074] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:1, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is dithiodipropionic acid, with a ratio of methylnadic anhydride:dithiodipropionic acid = 70:30.

[0075] (5) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0076] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0077] Example 6 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 8 cycles are performed.

[0078] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The lower layer of precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0079] (3) Add 20% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 70℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 70℃ for 24 hours.

[0080] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:3, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is dithiodipropionic acid, with a ratio of methylnadic anhydride:dithiodipropionic acid = 80:20.

[0081] (5) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0082] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0083] Example 7 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 8 cycles are performed.

[0084] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0085] (3) Add 20% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 70℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 70℃ for 24 hours.

[0086] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is cystine, with a methylnadic anhydride:cystine ratio of 65:35.

[0087] (5) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0088] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0089] Example 8 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 8 cycles are performed.

[0090] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0091] (3) Add 20% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 70℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 70℃ for 24 hours.

[0092] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:85:10, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methyl nadic anhydride, and the sulfur-containing active component is dimethyl cysteine, with a ratio of methyl nadic anhydride: dimethyl cysteine ​​= 80:20.

[0093] (5) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0094] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0095] Example 9 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, stir at 300rpm for 2h, and then put it in the refrigerator to cool and stand for 1h as one cycle. A total of 8 cycles are performed.

[0096] (2) The modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The resulting white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0097] (3) According to the ratio of epoxy resin: curing agent: special engineering plastic modified filler = 100:85:0.5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methyl nadic anhydride, and the sulfur-containing active component is dimethyl cysteine, with a ratio of methyl nadic anhydride:dimethyl cysteine ​​= 60:40.

[0098] (4) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0099] (5) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0100] Example 10 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, stir at 300rpm for 2h, and then put it in the refrigerator to cool and stand for 1h as one cycle. A total of 8 cycles are performed.

[0101] (2) The modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The resulting white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0102] (3) According to the ratio of epoxy resin: curing agent: special engineering plastic modified filler = 100:85:1, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is dithiodipropionic acid, with a ratio of methylnadic anhydride:dithiodipropionic acid = 60:40.

[0103] (4) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0104] (5) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0105] Example 11 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, stir at 300rpm for 2h, and then put it in the refrigerator to cool and stand for 1h as one cycle. A total of 8 cycles are performed.

[0106] (2) The modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The resulting white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0107] (3) According to the ratio of epoxy resin: curing agent: special engineering plastic modified filler = 100:85:3, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is cystine, with a methylnadic anhydride:cystine ratio of 60:40.

[0108] (4) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0109] (5) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0110] Example 12 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, stir at 300rpm for 2h, and then put it in the refrigerator to cool and stand for 1h as one cycle. A total of 8 cycles are performed.

[0111] (2) The modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The resulting white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0112] (3) According to the ratio of epoxy resin: curing agent: special engineering plastic modified filler = 100:85:5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is cystine, with a methylnadic anhydride:cystine ratio of 70:30.

[0113] (4) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0114] (5) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0115] Example 13 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, stir at 300rpm for 2h, and then put it in the refrigerator to cool and stand for 1h as one cycle. A total of 8 cycles are performed.

[0116] (2) The modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The resulting white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0117] (3) According to the ratio of epoxy resin: curing agent: special engineering plastic modified filler = 100:85:5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methylnadic anhydride, and the sulfur-containing active component is cystine, with a methylnadic anhydride:cystine ratio of 90:10.

[0118] (4) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0119] (5) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0120] Comparative Example 1 (1) Use untreated commercially available PEEK powder directly as filler.

[0121] (2) Referring to the ratio of epoxy resin: curing agent: unmodified engineering plastic modified filler = 100: 85: 0.5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0122] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, thus obtaining the epoxy resin material filled with special engineering plastics.

[0123] Comparative Example 2 (1) Use untreated commercially available PEEK powder directly as filler.

[0124] (2) Referring to the ratio of epoxy resin: curing agent: unmodified engineering plastic modified filler = 100:85:1, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0125] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, thus obtaining the epoxy resin material filled with special engineering plastics.

[0126] Comparative Example 3 (1) Use untreated commercially available PEEK powder directly as filler.

[0127] (2) Referring to the ratio of epoxy resin: curing agent: unmodified engineering plastic modified filler = 100:85:3, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0128] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, thus obtaining the epoxy resin material filled with special engineering plastics.

[0129] Comparative Example 4 (1) Use untreated commercially available PEEK powder directly as filler.

[0130] (2) Referring to the ratio of epoxy resin: curing agent: unmodified engineering plastic modified filler = 100:85:5, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0131] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, thus obtaining the epoxy resin material filled with special engineering plastics.

[0132] Comparative Example 5 (1) Use untreated commercially available PEEK powder directly as filler.

[0133] (2) Referring to the ratio of epoxy resin: curing agent: unmodified engineering plastic modified filler = 100: 85: 10, the mixture is stirred in a water bath at 60°C for 2 hours to ensure thorough mixing, and then stirred in a vacuum environment of a vacuum casting machine.

[0134] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample, thus obtaining the epoxy resin material filled with special engineering plastics.

[0135] Comparative Example 6 (1) Referring to the ratio of epoxy resin: curing agent = 100: 85, stir in a water bath at 70°C for 2 hours to ensure thorough mixing, and then stir in a vacuum environment of a vacuum casting machine.

[0136] (3) Add 1 part of accelerator, stir under vacuum and pour into the mold, then put it in the oven at 70°C for 3 hours to cure, and finally continue to cure at 145°C for 6 hours to take out the sample and obtain epoxy resin cured product without filler.

[0137] Table 1. Comparison of tensile strength and repair efficiency of materials in Examples 4-13 and Comparative Examples of the present invention.

[0138] As shown in Table 1, comparing Examples 4, 5, and 6, the mechanical properties (tensile strength, flexural strength, elongation at break, impact strength, etc.) of the materials all showed significant improvements, proving that modified special engineering plastics as fillers can effectively improve the mechanical and electrical properties of cured composite materials, providing greater margin for electrical equipment manufacturing. In Example 8, compared to Example 6, the electrical properties still increased, but the tensile and flexural strengths showed a significant decrease. This is because, after the filler content increased, the filler base of the composite material system experienced sedimentation. Due to sedimentation, the mechanical properties of the epoxy resin composite material showed significant differences at the interface, resulting in a decrease in mechanical properties. Examples 9-13, compared to Examples 4-8, did not undergo KH560 interface modification, and their mechanical properties did not improve due to sedimentation at lower filler mass fractions. Compared to 1-5, which directly used unmodified fillers, the mechanical properties of these plastics decreased immediately after the filler was added. This demonstrates that the special engineering plastics without any modification have very few surface-active groups and do not cross-link with the epoxy resin. As a result, the filler settles directly in the epoxy resin premix. The mechanical and electrical properties of these plastics decreased significantly compared to Comparative Example 6, i.e., the epoxy resin for electrical equipment without filler, after the addition of filler, rendering them unusable.

[0139] In the examples of the above materials, based on experimental results, the special engineering plastics using the dual-modification technique exhibited the best overall performance when the filler mass fraction was 3% of the epoxy resin monomer. While mechanical properties were significantly improved, electrical properties and volume resistivity remained at a high level. Furthermore, all examples demonstrate that both filler modifications using the dual-modification scheme are necessary and can improve the dispersion performance of the special engineering plastic filler within the epoxy resin. The unmodified special engineering plastics used as a comparative example do not possess this characteristic.

[0140] Example 14 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 7 cycles are performed.

[0141] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0142] (3) Add 25% KH550 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 60℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 60℃ for 24 hours.

[0143] (4) According to the mixing ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:100:3.5, the mixture is stirred in a water bath at 65°C for 2.5 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methyl nadic anhydride, and the sulfur-containing active component is dimethyl cysteine, with a methyl nadic anhydride:dimethyl cysteine ​​ratio of 75:25.

[0144] (5) Add 3 parts of accelerator, stir under vacuum and pour into the mold, then put it in the oven to cure at 70°C for 2.5 hours, and finally continue to cure at 140°C for 5.5 hours before taking out the sample. The epoxy resin composite material filled with special engineering plastic modified filler was obtained.

[0145] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0146] Example 15 (1) Mix 5g of PEEK powder with 50g of urea, add 10mL of deionized water, mix evenly, and then ball mill at 300rpm for 2h. After cooling and standing in the refrigerator for 1h, this is one cycle. A total of 6 cycles are performed.

[0147] (2) Subsequently, the modified PEEK powder was placed in a centrifuge and centrifuged at 7000 rpm for 10 min. The precipitate was removed, and the centrifugation process was repeated 8 times. The obtained white solid was dried and then screened through a sieve to obtain PEEK powder particles with the required particle size.

[0148] (3) Add 15% KH560 silane coupling agent solution to 10g of modified PEEK powder and special engineering plastic powder. Stir at 600rpm for 30min and pour into a flask for heating and reflux. Heat and reflux at 80℃ and 600rpm for 3 hours to obtain modified PEEK powder solution. Vacuum the final product at 80℃ for 24 hours.

[0149] (4) According to the ratio of epoxy resin: reversible covalent anhydride system curing agent: special engineering plastic modified filler = 100:70:4, the mixture is stirred in a water bath at 70°C for 2 hours to ensure thorough mixing, and then stirred under vacuum in a vacuum casting machine. The anhydride component in the reversible covalent anhydride system curing agent is methyl nadic anhydride, and the sulfur-containing active component is dimethyl cysteine, with a methyl nadic anhydride:dimethyl cysteine ​​ratio of 85:15.

[0150] (5) Add 0.5 parts of accelerator, stir under vacuum and pour into the mold, then put it in the oven to cure at 70°C for 2 hours, and finally continue to cure at 150°C for 5 hours to take out the sample and obtain epoxy resin composite material filled with special engineering plastic modified filler.

[0151] (6) Remove the epoxy resin test piece from the mold and test the epoxy resin composite material sample in accordance with the national standard.

[0152] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention.

Claims

1. A special engineering plastic modified filler, characterized in that, The modified filler is obtained by a two-stage modification of special engineering plastic powder through an amino introduction step and a silane coupling agent grafting step, wherein: Amino introduction step: The special engineering plastic powder is mixed with an active amino compound and a solvent and then subjected to 6 to 8 ball milling-cooling cycles to achieve particle thinning and introduce amino groups on the particle surface. Aminated special engineering plastic powder is obtained by centrifugation. Silane coupling agent grafting step: The aminated special engineering plastic powder is refluxed with 15% to 25% silane coupling agent solution at 60°C to 80°C to form a siloxane active structure on the surface. The modified filler obtained is in powder form after vacuum drying, with a particle size of less than 1000 mesh.

2. The special engineering plastic modified filler as described in claim 1, characterized in that, The special engineering plastics include at least one of polyetheretherketone, polysulfone, polyarylate, or liquid crystal polymers filled with short glass fibers.

3. A special engineering plastic modified filler as described in claim 1, characterized in that, The silane coupling agent includes KH550 or KH560.

4. A special engineering plastic modified epoxy resin composite material, characterized in that, The following curing mixture system is used, and its components and proportions include: 100 parts epoxy resin; 70-100 parts of reversible covalent anhydride curing agent; 0.5 to 10 parts of the special engineering plastic modified filler as described in any one of claims 1 to 3; Accelerator 0.5–3 parts; The modified filler forms interfacial covalent bonds with the epoxy resin, thereby improving the elongation at break and dielectric strength of the cured product.

5. A special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The addition ratio of the special engineering plastic filler is 3 to 5 parts.

6. A special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The epoxy resin includes bisphenol A type epoxy resin E-51 or CLP-128.

7. A special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The accelerator includes 2,4,6-tris(dimethylaminomethyl)phenol.

8. The special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The reversible covalent anhydride system curing agent is composed of an anhydride component and a sulfur-containing active component, wherein the anhydride component is methylnadic anhydride, and the sulfur-containing active component is selected from at least one of cystine, cystine dimethyl ester, or dithiodipropionic acid.

9. The special engineering plastic modified epoxy resin composite material as described in claim 8, characterized in that, The ratio of acid anhydride component to sulfur-containing active component is 90:10 to 60:

40.

10. The special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The reversible covalent anhydride system curing agent is 85 parts.

11. The special engineering plastic modified epoxy resin composite material as described in claim 4, characterized in that, The accelerator is 1 part.

12. A method for preparing a special engineering plastic modified epoxy resin composite material, characterized in that, The method includes the following steps: Prepare epoxy resin, reversible covalent anhydride system curing agent, special engineering plastic modified filler and accelerator according to the proportions described in any one of claims 4-11; Epoxy resin, reversible covalent anhydride curing agent, and special engineering plastic modified filler are mixed in a vacuum environment of 60℃~70℃ to form a primary mixture; An accelerator is added to the primary mixture, and the mixture is stirred evenly under vacuum to obtain a secondary mixture; The secondary mixture is poured into a mold and cured in multiple stages to obtain the special engineering plastic modified epoxy resin composite material.

13. The method for preparing a special engineering plastic modified epoxy resin composite material as described in claim 12, characterized in that, The multi-stage curing process includes curing at 70°C for 2–3 hours, followed by curing at 140°C–150°C for 5–6 hours.

14. The method for preparing a special engineering plastic modified epoxy resin composite material as described in claim 12, characterized in that, The vacuum environment includes mixing within a vacuum casting machine.

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