A wave-absorbing epoxy resin and a preparation method thereof

Abstract

The application discloses a wave-absorbing epoxy resin and a preparation method thereof. The wave-absorbing epoxy resin is prepared from the following raw materials in parts by weight: 50-150 parts of an epoxy resin, 30-60 parts of a toughening agent, 150-300 parts of a sheet-shaped powder metal filler, 0-50 parts of a non-metal filler and 10-55 parts of a curing agent. The sheet-shaped powder metal filler is a metal filler modified by a ball milling method. The wave-absorbing epoxy resin is subjected to first curing at 20-25 DEG C and second curing at 80-100 DEG C.

Description

Technical Field

[0001] This application relates to the field of microwave absorbing epoxy resin technology, specifically to a microwave absorbing epoxy resin and its preparation method. Background Technology

[0002] Microwave-absorbing resins are a class of functional polymer materials that can absorb incident electromagnetic wave energy and convert it into heat energy or other forms of energy. They have important applications in military stealth, communication anti-jamming, and electromagnetic shielding of electronic equipment.

[0003] Traditional methods for preparing microwave-absorbing epoxy resins typically involve uniformly mixing the resin matrix and microwave-absorbing fillers at room temperature or under heating conditions, followed by curing. However, prolonged heating is required in the initial stages of curing, and the resin viscosity decreases significantly with increasing temperature. This causes the denser microwave-absorbing fillers to settle, ultimately resulting in uneven component distribution in the cured product, which affects the overall microwave absorption performance and the stability of product quality.

[0004] Currently, existing microwave-absorbing epoxy resins still suffer from problems such as overall microwave absorption performance failing to meet practical application requirements and unsatisfactory low-frequency reflection loss. Furthermore, their preparation efficiency is low, and the microwave-absorbing agent powder is difficult to disperse uniformly in the resin, resulting in incomplete coating and further limiting their application performance. Therefore, developing a microwave-absorbing resin that can self-cur at room temperature has significant research value and market potential. Summary of the Invention

[0005] To address the aforementioned deficiencies in this field, this application aims to provide a self-curing microwave absorbing epoxy resin and its preparation method.

[0006] According to one aspect of this application, a microwave-absorbing epoxy resin is provided, comprising the following raw materials in parts by weight: 50-150 parts epoxy resin 30-60 parts toughening agent 150-300 parts of flake-shaped powdered metal filler 0-50 parts of non-metallic filler 10-55 parts of curing agent The sheet-like powdered metal filler is a metal filler modified by ball milling; The microwave-absorbing epoxy resin undergoes a first curing at 20-25℃ and a second curing at 80-100℃.

[0007] According to some embodiments of this application, the microwave-absorbing epoxy resin further includes: 0.05-3% of the total mass of the above raw materials as a coupling agent and 0.05-3% of the total mass of the above raw materials as a defoamer.

[0008] According to some embodiments of this application, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin.

[0009] According to some embodiments of this application, the epoxy resin is selected from one or more of CYD-128, CYD-127, CYD-011, NPEL128, NPEL127, E51, NPEF170, NPEF171, NPEF175, NPPN-631, and NPCN-702.

[0010] According to some embodiments of this application, the toughening agent is selected from one or more of silicone-type epoxy toughening agents, core-shell type epoxy toughening agents, and reactive diluents.

[0011] According to some embodiments of this application, the metal filler is selected from one or more of carbonyl iron powder, ferrite powder, and metal micro powder.

[0012] According to some embodiments of this application, the non-metallic filler is selected from one or more of carbon black, graphite, graphene, carbon nanotubes, and polypyrrole.

[0013] According to some embodiments of this application, the curing agent is selected from one or more of aliphatic amine curing agents, modified amines, and imidazoles.

[0014] According to some embodiments of this application, the curing agent is selected from one or more of modified DETA, modified EDA, DMDC, and modified MI.

[0015] According to some embodiments of this application, the defoamer is selected from one or more of alcohols, fatty acids, phosphate esters, amides, and organosilicon defoamers.

[0016] According to some embodiments of this application, the coupling agent is selected from one or more of KH550, KH560 and KH570.

[0017] According to a second aspect of this application, a method for preparing the above-mentioned microwave-absorbing epoxy resin is provided, comprising: Metal fillers were modified by ball milling to prepare flake-shaped powdered metal fillers; Non-metallic fillers are added to solvents such as acetone, mixed, ultrasonically dispersed, and then dried to obtain a pre-dispersed mixture; The toughening agent is mixed with liquid epoxy resin to prepare a first mixed solution; A second mixed solution is prepared by adding flake-shaped powdered metal filler to an acetone solution; The second mixed solution and the pre-dispersed mixture were poured into the first mixed solution, mixed evenly, and then dried to prepare the epoxy resin-coated microwave absorbing filler. After the epoxy resin-coated microwave absorbing filler cools down, a coupling agent, a defoamer and a curing agent are added to it to obtain microwave absorbing epoxy resin. The microwave-absorbing epoxy resin undergoes a first curing at 20-25℃ and a second curing at 80-100℃.

[0018] According to some embodiments of this application, the preparation of sheet-like powdered metal fillers includes: After adding acetone to the metal filler and stirring until homogeneous, the mixture is ball-milled and then vacuum-dried to obtain powder. The powder is heat-treated in an inert atmosphere to obtain flake-shaped powder metal filler.

[0019] According to some embodiments of this application, the heat treatment temperature is 300-600℃; the heat treatment time is 0.5-2h.

[0020] According to some embodiments of this application, the ball-to-material ratio of the ball mill is (10-40):1, the rotation speed is 200-400 r / min, the ball milling time is 80-100 h, and the ball milling temperature is 20-40℃.

[0021] This application includes at least the following beneficial effects: The preparation method provided in this application is simple, efficient, and easy to industrialize. The filler obtained is a sheet-like soft magnetic powder that can break through the Snoke limit and has high magnetic permeability. The microwave absorbing epoxy resin prepared after being coated with resin exhibits better microwave absorption performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process of the microwave-absorbing epoxy resin of this application.

[0023] Figure 2 SEM images of the sheet-like powdered metal filler before (left) and after (right) ball milling, representing an example embodiment of this application.

[0024] Figure 3 The diagram shows the absorption performance of example embodiments and comparative examples of this application. Detailed Implementation

[0025] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] It should be particularly noted that similar substitutions and modifications made to this application are obvious to those skilled in the art, and they are all considered to be included in this application. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0027] Unless otherwise specified, this application shall be made in accordance with conventional conditions or conditions recommended by the manufacturer. Raw materials or excipients, as well as reagents or instruments whose manufacturers are not specified, shall be conventional products that can be obtained commercially.

[0028] The following is a detailed description of this application.

[0029] In an example embodiment of this application, a microwave-absorbing epoxy resin is provided, which is composed of the following raw materials in parts by weight: 50-150 parts epoxy resin 30-60 parts toughening agent 150-300 parts of flake-shaped powdered metal filler 0-50 parts of non-metallic filler 10-55 parts of curing agent The flake-shaped powdered metal filler is a metal filler modified by ball milling; The microwave-absorbing epoxy resin undergoes a first curing at 20-25℃ and a second curing at 80-100℃.

[0030] According to an optional embodiment of this application, the microwave-absorbing epoxy resin further includes: 0.05-3% of the total mass of the above raw materials as a coupling agent and 0.05-3% of the total mass of the above raw materials as a defoamer.

[0031] In the example embodiments of this application, Figure 1 This application illustrates a method for preparing the microwave-absorbing epoxy resin according to an embodiment. Specifically, it includes: S11: Preparation of sheet-like metal fillers.

[0032] In some example embodiments, the step includes: mixing metal powder with a dispersant to obtain a mixture; ball milling the mixture under an inert atmosphere and then vacuum drying it to obtain a flake-shaped powder metal filler.

[0033] The sheet-like powdered metal filler is heat-treated in an inert atmosphere to obtain heat-treated metal filler.

[0034] The metal powder used in this application may be selected from one or more of the following: carbonyl iron powder, carbonyl nickel powder, ferrite powder, carbonyl iron-nickel alloy powder, copper powder, and cobalt powder. Optionally, the purity of these metal powders is higher than 99%. Optionally, the particle size of these metal powders is less than 50 μm.

[0035] Optionally, in this application, the carbonyl iron powder is iron powder produced by the decomposition of carbonyl iron compounds, and the carbonyl iron powder can be obtained commercially. Optionally, its composition is: Fe 98%, C 0.5%, O 0.6%, N 0.3%.

[0036] Carbonyl nickel powder refers to nickel powder prepared by the carbonyl method, which has high purity, high nickel content, and magnetic and electrical properties. The carbonyl nickel powder of this application is commercially available. Optionally, its composition is: Ni 99.5%, Fe 0.01%, C 0.15%, O 0.15%, S 0.001%.

[0037] Optionally, the dispersant used is selected from one or more of polyvinyl alcohol, ethanol, and acetone. The dispersant prevents the metal powder from forming agglomerates during ball milling. Optionally, the amount of dispersant used is 0.2-2 wt% (mass percentage) of the metal powder.

[0038] Alternatively, if multiple metal powders are used, these metal powders should be mixed evenly first, then mixed with a dispersant, and then mechanically alloyed in a ball mill. The mixing speed can be 200-500 rpm.

[0039] The high-energy ball milling method described in this application utilizes the rotation or vibration of a ball mill to intensely impact, grind, and stir the raw material with hard balls, pulverizing the metal powder into ultrafine powder. Two or more metal powders are simultaneously placed into the ball mill for high-energy ball milling. The powder particles undergo repeated processes of rolling, pressing, crushing, and pressing (a repeated process of cold welding-crushing-cold welding), ultimately obtaining thin, flake-shaped powder with a uniform structure and composition distribution.

[0040] Alternatively, the inert atmosphere can be provided by nitrogen or argon. The inert atmosphere can be provided by repeatedly evacuating the system and then introducing nitrogen or argon.

[0041] Optionally, the heat treatment can be carried out in a muffle furnace. Optionally, the heat treatment temperature is 300-600℃, and the holding time is 0.5-2h. Optionally, the inert atmosphere can be provided by nitrogen or argon.

[0042] Heat treatment can eliminate internal stress and anisotropy in alloys, increase magnetic permeability, and reduce coercivity. At the same time, during heat treatment, certain atomic microcrystals precipitate inside the alloy, refining the magnetic domains and improving its shielding effectiveness.

[0043] S12: Epoxy resin coated heat-treated metal filler.

[0044] In some example embodiments, the step includes: adding heat-treated metal and / or non-metallic fillers to a dispersant, ultrasonically treating and mixing them uniformly to obtain a metal / non-metal mixture; adding a toughening agent to an epoxy resin and mixing them uniformly to obtain an epoxy resin mixture; slowly pouring the metal mixture into the epoxy resin mixture while stirring, manually mixing until uniform, and then treating it with a shearing machine for 1 hour to ensure that the epoxy resin mixture fully coats the metal mixture, mixing it uniformly, and then vacuum drying to obtain epoxy resin-coated heat-treated metal fillers.

[0045] S13: Heat-treated metal filler is mixed with coupling agent, defoamer, epoxy resin and curing agent to obtain microwave absorbing epoxy resin.

[0046] Optionally, the silane coupling agent is selected from one or more of KH550, KH560 and KH570; Optionally, the defoamer is selected from one or more of alcohols, fatty acids, phosphate esters, amides, and organosilicon defoamers.

[0047] Optionally, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin.

[0048] Optionally, the curing agent is selected from one or more of aliphatic amine curing agents, modified amines, and imidazoles.

[0049] The preparation method provided in this application is simple, efficient, and easy to industrialize. The filler obtained is a sheet-like soft magnetic powder that can break through the Snoke limit and has high magnetic permeability. The microwave absorbing epoxy resin prepared after being coated with the filler exhibits superior microwave absorption performance.

[0050] The method provided in this application is simple and has high production efficiency. The magnetic permeability and electrical conductivity of the material can be adjusted by adjusting the proportion of the metal filler used and the ball milling process parameters. The microwave absorbing filler is coated with epoxy resin as a matrix to prepare epoxy resin with excellent microwave absorbing properties.

[0051] The technical solution of this application will be further described below with reference to specific embodiments.

[0052] Example 1 Weigh the corresponding weight of carbonyl iron powder, add 5% (by mass) acetone, stir well, and then ball mill. Use stainless steel beads with a diameter of 10mm:5mm:3mm = 3:2:1 (ball-to-powder ratio of 40:1). Add the metal powder and stainless steel beads to the ball mill jar, seal and evacuate five times, purge with nitrogen and cooling water, maintain a ball mill temperature of 25℃, and a rotation speed of 300 r / min. After every 1 hour of ball milling, stop for 5 minutes, then reverse the rotation, repeating this process. After 80 hours of ball milling, cool to room temperature and remove. The powder was then vacuum dried at 100°C. The dried powder was placed in a muffle furnace, nitrogen gas was introduced, and the temperature was raised to 500°C at a rate of 10°C / min. After holding at this temperature for 1 hour, the powder was naturally cooled to room temperature to obtain modified carbonyl iron powder.

[0053] Weigh 60 parts of liquid phenolic epoxy resin and 40 parts of toughening agent and add them to a container. Stir well to obtain homemade epoxy resin.

[0054] Weigh 200 parts of the above modified carbonyl iron powder and 100 parts of acetone, sonicate for 20 minutes and stir evenly, then slowly pour into 100 parts of the above self-made epoxy resin while stirring. After mixing evenly, dry to obtain epoxy resin-coated carbonyl iron.

[0055] Weigh 300 parts of the above epoxy resin-coated carbonyl iron, add 2% (by mass) silane coupling agent and defoamer and mix evenly, then add 38 parts of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and 2 parts of 2-methylimidazole, and stir while vacuuming until evenly mixed to obtain microwave absorbing epoxy resin.

[0056] The above epoxy resin composition is injected into the corresponding mold, and then placed at 20-25°C for 24 hours for the first curing and at 80°C for 5 hours for the second curing to obtain a microwave absorbing epoxy resin casting.

[0057] Example 2 Weigh out the corresponding weights of ferrite powder and carbonyl iron powder at a weight ratio of 4:1, mix them evenly, add 5% (mass ratio) of acetone, stir evenly, and then ball mill. Use stainless steel beads with a diameter of 10mm:5mm:3mm = 3:2:1 (ball-to-powder ratio of 30:1). Add the above metal powder and stainless steel beads to a ball mill jar, seal and evacuate five times, purge with nitrogen and cooling water, control the ball milling temperature at 25℃, and the rotation speed at 350 r / min. After every 1 hour of ball milling, stop for 5 minutes, then reverse the rotation, repeating this process. After 90 hours of ball milling, cool to room temperature, remove the powder, and vacuum dry at 100℃. Place the powder in a muffle furnace, purge with nitrogen, heat to 450℃ at a rate of 10℃ / min, hold at this temperature for 1 hour, and then allow to cool naturally to room temperature to obtain the modified composite metal powder.

[0058] Weigh 50 parts of liquid bisphenol epoxy resin and 50 parts of toughening agent and add them to a container. Stir well to obtain homemade epoxy resin.

[0059] Weigh 200 parts of the above modified composite metal powder and 100 parts of acetone, sonicate for 20 minutes and stir evenly, then slowly pour into 100 parts of the above self-made epoxy resin while stirring. After mixing evenly, dry to obtain epoxy resin-coated composite metal powder.

[0060] Weigh 300 parts of the above epoxy resin-coated composite metal powder, add 0.2% (by mass) of silane coupling agent and defoamer and mix evenly, then add 10 parts of modified amine curing agent, and stir while vacuuming until evenly mixed to obtain microwave absorbing epoxy resin.

[0061] The above epoxy resin composition was injected into the corresponding mold, and the first curing was carried out at room temperature for 24 hours, and the second curing was carried out at 80°C for 3 hours to obtain the microwave absorbing epoxy resin casting.

[0062] Example 3 Weigh out the corresponding weights of ferrite powder and carbonyl iron powder at a weight ratio of 3:2, mix them evenly, add 5% (by weight) acetone, stir evenly, and then ball mill. Use stainless steel beads with a diameter of 10mm:5mm:3mm = 3:2:1 (ball-to-powder ratio of 20:1). Add the above metal powder and stainless steel beads to a ball mill jar, seal and evacuate five times, purge with nitrogen and cooling water, control the ball milling temperature at 25℃, and the rotation speed at 350 r / min. After every 1 hour of ball milling, stop for 5 minutes, then reverse the rotation, repeating this process. After ball milling for 100 hours, cool to room temperature, remove the powder, and vacuum dry at 100℃. Place the powder in a muffle furnace, purge with nitrogen, heat to 450℃ at a rate of 10℃ / min, hold at this temperature for 1 hour, and then allow to cool naturally to room temperature to obtain the modified composite metal powder.

[0063] Weigh out 50 parts of liquid epoxy resin, 50 parts of liquid phenolic epoxy resin, and 50 parts of toughening agent and add them to a container. Stir well to obtain epoxy resin (homemade).

[0064] Weigh 250 parts of the above modified composite metal powder and 150 parts of acetone, sonicate for 20 minutes and stir evenly, then slowly pour into 150 parts of the above self-made epoxy resin while stirring. After mixing evenly, dry to obtain epoxy resin-coated composite metal powder.

[0065] Weigh 400 parts of the above epoxy resin-coated composite metal powder, add 0.15% (by mass) of silane coupling agent and defoamer and mix evenly, then add 55 parts of alicyclic amine curing agent, and stir while vacuuming until evenly mixed to obtain microwave absorbing epoxy resin.

[0066] The above epoxy resin composition was injected into the corresponding mold, and the first curing was carried out at room temperature for 24 hours, and the second curing was carried out at 80°C for 5 hours to obtain the microwave absorbing epoxy resin casting.

[0067] Example 4 Weigh out 50 parts carbon black, 0.1 parts graphene, and 1 part silane coupling agent in sequence, add 5% (mass ratio) acetone, stir evenly, sonicate for 1 hour, and then dry to obtain a pre-dispersion.

[0068] Weigh 80 parts of liquid epoxy resin and 40 parts of toughening agent and add them to a container. Stir well to obtain epoxy resin (homemade).

[0069] Weigh 55 parts of the above pre-dispersion liquid and add it to the above self-made epoxy resin and mix evenly. Then add 0.5 parts of defoamer and 45 parts of modified amine curing agent in sequence, and stir while vacuuming until the mixture is evenly mixed to obtain microwave absorbing epoxy resin.

[0070] The above epoxy resin composition is injected into the corresponding mold, and the first curing is carried out at room temperature for 24 hours and the second curing is carried out at 80°C for 5 hours to obtain the microwave absorbing epoxy resin casting.

[0071] Comparative Example 1 The preparation steps are the same as in Example 1, except that the carbonyl iron powder is not ball-milled.

[0072] Comparative Example 2 The preparation steps are the same as in Example 2, except that the metal powder is not heat-treated, but is directly mixed with acetone after ball milling and drying.

[0073] Comparative Example 3 The preparation steps are the same as in Example 1, except that: instead of coating the carbonyl iron powder with epoxy resin, the modified carbonyl iron powder is directly added to epoxy resin, curing agent, coupling agent, etc. and mixed evenly.

[0074] Test case The absorption performance (Table 1), TG, and mechanical properties (Table 2) of the above embodiments and comparative examples were tested.

[0075] The specific steps for preparing the microwave absorption test plate and testing its absorption performance are as follows: Waveguide sample preparation requires cutting the absorbing epoxy resin casting into waveguide samples of corresponding sizes (2-18GHz, 5 samples per group); coaxial ring sample preparation requires casting the absorbing epoxy resin into a specific coaxial ring mold, curing it, and then cutting it into corresponding coaxial ring samples.

[0076] The absorption performance was tested using the waveguide cavity method and the coaxial ring method.

[0077] Table 1

[0078] Table 2

[0079] As can be seen from the above embodiments and comparative examples, ball milling and heat treatment can significantly improve the microwave absorption performance of epoxy resin. Ball milling can transform spherical carbonyl iron powder into flakes, breaking through the physical limit of high-frequency magnetic permeability. At the same time, by increasing resistance and interfacial polarization, the electromagnetic parameters of the material are more coordinated, thus exhibiting superior microwave absorption performance.

[0080] Ball milling alloys and refines two or more composite powders. Annealing eliminates internal stress and anisotropy in the alloy, increases magnetic permeability, and reduces coercivity. Simultaneously, during annealing, certain atomic microcrystals precipitate within the alloy, refining the magnetic domains and improving its microwave absorption efficiency. Furthermore, by adjusting the proportion of metal powders used and the ball milling process parameters, the magnetic permeability, electrical conductivity, and coercivity of the material can be controlled, thereby enabling the preparation of epoxy resins with high microwave absorption performance.

[0081] This application provides an epoxy resin with a room temperature curing mechanism. An epoxy resin with high compatibility with metal powder is selected and mixed with microwave absorbing filler. The uniformly dispersed resin can be initially cured at room temperature, thus avoiding problems such as filler sedimentation caused by direct heating. This application optimizes the ratio of resin matrix and filler, modifies metal fillers such as carbonyl iron through ball milling, and coats the microwave absorbing filler with epoxy resin as the matrix, ensuring effective bonding of the filler in the resin and guaranteeing that the prepared microwave absorbing epoxy resin has excellent microwave absorption and mechanical properties. Compared with existing preparation processes, this application simplifies the production process, shortens the curing time of the microwave absorbing material, improves production efficiency, and enables mass production.

[0082] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A microwave-absorbing epoxy resin, characterized in that, It consists of the following raw materials in parts by weight: 50-150 parts epoxy resin; 30-60 parts toughening agent; 150-300 parts of flake-shaped powdered metal filler; 0-50 parts of non-metallic filler; 10-55 parts of curing agent; The sheet-like powdered metal filler is a metal filler modified by ball milling; The microwave-absorbing epoxy resin undergoes a first curing at 20-25℃ and a second curing at 80-100℃.

2. The microwave-absorbing epoxy resin according to claim 1, characterized in that, The microwave-absorbing epoxy resin further includes: a coupling agent comprising 0.05-3% of the total mass of the raw materials as described in claim 1 and a defoamer comprising 0.05-3% of the total mass of the raw materials as described in claim 1.

3. The microwave-absorbing epoxy resin according to claim 1, characterized in that, The epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin; Optionally, the epoxy resin is selected from one or more of CYD-128, CYD-127, CYD-011, NPEL128, NPEL127, E51, NPEF170, NPEF171, NPEF175, NPPN-631, and NPCN-702.

4. The microwave-absorbing epoxy resin according to claim 1, characterized in that, The toughening agent is selected from one or more of the following: silicone-based epoxy toughening agents, core-shell epoxy toughening agents, and reactive diluents.

5. The microwave-absorbing epoxy resin according to claim 1, characterized in that, The metal filler is selected from one or more of carbonyl iron powder, ferrite powder, and metal micro powder; Optionally, the non-metallic filler is selected from one or more of carbon black, graphite, graphene, carbon nanotubes, and polypyrrole.

6. The microwave-absorbing epoxy resin according to claim 1, characterized in that, The curing agent is selected from one or more of aliphatic amine curing agents, modified amines, and imidazoles; Optionally, the curing agent is selected from one or more of modified DETA, modified EDA, DMDC, and modified MI.

7. The microwave-absorbing epoxy resin according to claim 2, characterized in that, The defoamer is selected from one or more of alcohols, fatty acids, phosphate esters, amides, and organosilicon defoamers; The coupling agent is selected from one or more of KH550, KH560 and KH570.

8. A method for preparing the microwave-absorbing epoxy resin according to any one of claims 1-7, characterized in that, include: Metal fillers were modified by ball milling to prepare flake-shaped powdered metal fillers; Non-metallic fillers are added to a solvent and mixed, then ultrasonically dispersed and dried to obtain a pre-dispersed mixture; The toughening agent is mixed with liquid epoxy resin to prepare a first mixed solution; The sheet-like powdered metal filler is added to an acetone solution to prepare a second mixed solution; The second mixed solution and the pre-dispersed mixture are poured into the first mixed solution, mixed evenly, and then dried to prepare the epoxy resin-coated microwave absorbing filler. After the epoxy resin-coated microwave absorbing filler has cooled, a coupling agent, a defoamer, and a curing agent are added to it to obtain a microwave absorbing epoxy resin. The microwave-absorbing epoxy resin undergoes a first curing at 20-25℃ and a second curing at 80-100℃.

9. The method for preparing the microwave-absorbing epoxy resin according to claim 8, characterized in that, The preparation of sheet-like powdered metal fillers includes: After adding acetone to the metal filler and stirring until homogeneous, the mixture is ball-milled and then vacuum-dried to obtain powder. The powder is heat-treated in an inert atmosphere to obtain a sheet-like powdered metal filler. Optionally, the heat treatment temperature is 300-600℃; the heat treatment time is 0.5-2h.

10. The method for preparing the microwave-absorbing epoxy resin according to claim 9, characterized in that, The ball mill has a ball-to-material ratio of (10-40):1, a rotation speed of 200-400 r / min, a milling time of 80-100 h, and a milling temperature of 20-40℃.

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