Strong-toughness wave-absorbing epoxy resin plate as well as preparation method and application thereof

Abstract

The invention provides a wave-absorbing epoxy resin plate with high toughness. The wave-absorbing epoxy resin plate is prepared from the following raw materials in parts by weight: 180 to 282 parts of 862 type epoxy resin, 10 to 72 parts of 128 type epoxy resin, 8 to 48 parts of E39D type epoxy resin, 2500 to 4500 parts of carbonyl iron powder, 1750 to 3150 parts of a coupling agent, 1250 to 2250 parts of absolute ethyl alcohol, 8 to 12 parts of a de-foaming agent, 8 to 12 parts of a dispersing agent and 210 parts of a curing agent. The coupling agent is added to coat the carbonyl iron powder, so that the corrosion resistance of the wave-absorbing epoxy resin plate can be improved; the 862 type epoxy resin, the 128 type epoxy resin and the E39D type epoxy resin are mixed to obtain the compound epoxy resin, so that the composition and the structure of a macromolecular chain of the epoxy resin are changed, the flexibility of the molecular chain is increased, the glass-transition temperature of the wave-absorbing epoxy resin plate is reduced, and the toughness of the wave-absorbing epoxy resin plate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave-absorbing epoxy resin sheets, and in particular relates to a strong and tough microwave-absorbing epoxy resin sheet, a preparation method thereof and an application thereof. Background Art

[0002] Absorbing epoxy resin sheets can convert the electromagnetic energy of incident electromagnetic waves into heat energy for dissipation or make electromagnetic waves interfere with each other to reduce echoes and achieve the effect of absorbing electromagnetic waves. They are often used in T / R components, antennas and radars. In actual use, absorbing epoxy resin sheets need to take into account both absorbing properties and mechanical properties.

[0003] At present, the existing microwave-absorbing epoxy resin sheets use epoxy resin as the matrix and obtain microwave-absorbing properties by adding a certain amount of microwave-absorbing additives. Most of the microwave-absorbing epoxy resin sheets used are too brittle and difficult to be applied to curved surfaces or areas with concave and convex surfaces; secondly, the added microwave-absorbing additives have poor corrosion resistance and will cause severe powder corrosion when used in a hot and humid environment, resulting in rapid failure of the microwave-absorbing properties. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to improve the toughness and corrosion resistance of the wave-absorbing epoxy resin sheet.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] The first aspect of the present invention provides a strong and tough wave-absorbing epoxy resin sheet, comprising the following raw materials in parts by weight:

[0007] 180-282 parts of 862 epoxy resin, 10-72 parts of 128 epoxy resin, 8-48 parts of E39D epoxy resin, 2500-4500 parts of carbonyl iron powder, 1750-3150 parts of coupling agent, 1250-2250 parts of anhydrous ethanol, 8-12 parts of defoaming agent, 8-12 parts of dispersant and 210 parts of curing agent.

[0008] Beneficial effects: The present invention can improve the corrosion resistance of the absorbing epoxy resin sheet by adding a coupling agent to coat the carbonyl iron powder; the compound epoxy resin is obtained by mixing 862 epoxy resin, 128 epoxy resin and E39D epoxy resin, which changes the composition and structure of the polymer chain of the epoxy resin, increases the flexibility of the molecular chain, reduces the glass transition temperature of the absorbing epoxy resin sheet, and improves the toughness of the absorbing epoxy resin sheet.

[0009] Preferably, the coupling agent includes one of KH570 silane coupling agent, KH560 silane coupling agent and KH550 silane coupling agent.

[0010] Preferably, the defoamer includes one of BYK-555 defoamer and BYK-141 defoamer.

[0011] Preferably, the dispersant includes one of BYK-191 dispersant and BYK-184 dispersant.

[0012] Preferably, the curing agent is an anhydride curing agent.

[0013] The second aspect of the present invention provides a method for preparing the above-mentioned strong and tough microwave-absorbing epoxy resin sheet, comprising the following steps:

[0014] (1) Anhydrous ethanol, carbonyl iron powder and coupling agent are weighed and prepared according to weight parts, and the anhydrous ethanol is first heated to 60° C., the coupling agent is added and stirred until the temperature drops to room temperature, and then the carbonyl iron powder is added, and the mixture is continuously stirred for 2 hours and then dried to obtain carbonyl iron powder coated with the coupling agent;

[0015] (2) mixing 862 epoxy resin, 128 epoxy resin and E39D epoxy resin according to parts by weight to obtain a composite epoxy resin, adding a defoamer, a dispersant, a curing agent and the carbonyl iron powder coated with the coupling agent of step (1) thereto, and stirring thoroughly to obtain a mixture;

[0016] (3) Grinding, dispersing, degassing and curing the mixture of step (2) to obtain a strong and tough microwave-absorbing epoxy resin sheet.

[0017] Preferably, the grinding is performed by grinding the mixture in a three-roll mill for multiple times.

[0018] Preferably, the ground mixture is placed in a dispersion tube at 80°C and dispersed by a high-speed disperser at a speed of 2000 rpm for 5 minutes, and then the speed is increased to 4000 rpm until the temperature of the mixture in the dispersion tube reaches 70°C, and then the speed is reduced to 2000 rpm for 5 minutes.

[0019] Preferably, the dispersed mixture is placed in a vacuum degassing box for degassing at a pressure of 10 -3 Pa, the time is 20min, and the degassing treatment is carried out multiple times until the bubbles disappear.

[0020] Preferably, the degassed mixture is placed in a mold at 80°C, and the mold is placed in an oven for curing treatment. The curing treatment is specifically as follows: heating from 25°C to 80°C, keeping warm for 20 minutes; then heating to 110°C, keeping warm for 30 minutes; then heating to 150°C, keeping warm for 40 minutes; continuing to heat to 160°C, keeping warm for 120 minutes, and finally cooling with the furnace, demolding and taking out to obtain a strong and tough absorbing epoxy resin sheet.

[0021] Preferably, the weight ratio of the anhydrous ethanol, carbonyl iron powder and coupling agent is 0.6:1:0.7.

[0022] Beneficial effects: The present invention utilizes a coupling agent to coat carbonyl iron powder, which can improve the corrosion resistance of the strong and tough wave-absorbing epoxy resin sheet and extend the service life of the strong and tough wave-absorbing epoxy resin sheet; the compound epoxy resin is obtained by mixing 862 epoxy resin, 128 epoxy resin and E39D epoxy resin, which changes the composition and structure of the polymer chain of the epoxy resin, increases the flexibility of the molecular chain, reduces the glass transition temperature of the wave-absorbing epoxy resin sheet, and improves the toughness of the wave-absorbing epoxy resin sheet.

[0023] The third aspect of the present invention provides the application of the above-mentioned strong and tough absorbing epoxy resin sheet in antennas or radars. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a test diagram of electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet of Example 1;

[0025] Figure 2 This is a test diagram of electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet of Example 2;

[0026] Figure 3 This is a test diagram of electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet of Example 3. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0029] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0030] Example 1

[0031] This embodiment provides a strong and tough microwave-absorbing epoxy resin sheet, which specifically includes the following raw materials in parts by weight:

[0032] 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 2805 parts of carbonyl iron powder, 1964 parts of KH560 coupling agent, 1403 parts of anhydrous ethanol, 8 parts of BYK-530 defoamer, 8 parts of BYK-W903 dispersant, and 210 parts of anhydride curing agent.

[0033] The specific method for preparing the microwave-absorbing epoxy resin sheet is as follows:

[0034] (1) 1403 parts of anhydrous ethanol, 2805 parts of carbonyl iron powder and 1964 parts of KH560 silane coupling agent were weighed and set aside according to weight. The anhydrous ethanol was first heated to 60° C. using a heating magnetic stirrer and the KH560 silane coupling agent was added. After stirring for 40 minutes, the solution was cooled to room temperature and the carbonyl iron powder was added. After continuous stirring for 2 hours, the solution was dried to obtain the carbonyl iron powder coated with the KH560 silane coupling agent.

[0035] (2) 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 8 parts of BYK-530 defoamer, and 8 parts of BYK-W903 dispersant were weighed into a stainless steel container according to weight, and stirred evenly with a high-speed disperser until the liquid color was uniform, the speed was 500 rpm, and the dispersion time was 5 minutes; 210 parts of anhydride curing agent were added thereto and stirred at a speed of 500 rpm for a dispersion time of 5 minutes; and the carbonyl iron powder coated with KH560 silane coupling agent in step (1) was added thereto and stirred at a speed of 1000 rpm until no obvious particles were present, thereby obtaining a uniformly stirred mixture.

[0036] (3) Grind the mixture with a three-roll mill, grind it 8 times, put it into a dispersion tube at 80°C, and disperse it with a high-speed disperser at a speed of 2000 rpm for 5 minutes; then increase the speed to 4000 rpm until the temperature of the mixture in the dispersion tube reaches 70°C, reduce the speed to 2000 rpm, and disperse it for 5 minutes.

[0037] (4) Place the dispersed mixture into a vacuum degassing box for degassing at a pressure of 10 -3 Pa, the time is 20min, and the secondary degassing treatment is carried out until the bubbles disappear completely, the degassed mixture is cast into a mold preheated at 80°C, and the mold is placed in an oven for curing treatment. The curing treatment is specifically heated from 25°C to 80°C, and kept warm for 20min; then heated to 110°C, and kept warm for 30min; then heated to 150°C, and kept warm for 40min; continued to heat to 160°C, and kept warm for 120min, and finally cooled with the furnace, demolded and taken out to obtain a strong and tough absorbing epoxy resin sheet with a size of 300mm×300mm×2mm.

[0038] This embodiment tests the electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet. The test results are as follows: Figure 1 As shown by Figure 1 It can be seen that the strong and tough absorbing epoxy resin sheet of this embodiment has good attenuation constant and impedance matching characteristics; the Shore hardness, tensile strength, elongation at break and corrosion resistance of the strong and tough absorbing epoxy resin sheet are shown in Table 1, which are 94HD, 51.6MPa, 4.2% and 240min respectively.

[0039] Example 2

[0040] This embodiment provides a strong and tough microwave-absorbing epoxy resin sheet, which specifically includes the following raw materials in parts by weight:

[0041] 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 3570 parts of carbonyl iron powder, 2499 parts of KH560 coupling agent, 1785 parts of anhydrous ethanol, 11 parts of BYK-530 defoamer, 11 parts of BYK-W903 dispersant, and 210 parts of anhydride curing agent.

[0042] The specific method for preparing the microwave-absorbing epoxy resin sheet is as follows:

[0043] (1) 1785 parts of anhydrous ethanol, 3570 parts of carbonyl iron powder and 2499 parts of KH560 silane coupling agent were weighed and set aside. The anhydrous ethanol was heated to 60° C. and KH560 silane coupling agent was added by stirring with a heating magnetic device. After stirring for 40 minutes, the solution was cooled to room temperature and carbonyl iron powder was added. After continuous stirring for 2 hours, the solution was dried to obtain carbonyl iron powder coated with KH560 silane coupling agent.

[0044] (2) 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 11 parts of BYK-530 defoamer, and 11 parts of BYK-W903 dispersant were weighed into a stainless steel container according to weight, and stirred evenly with a high-speed disperser until the liquid color was uniform, the speed was 500 rpm, and the dispersion time was 5 minutes; 210 parts of anhydride curing agent were added thereto and stirred at a speed of 500 rpm for a dispersion time of 5 minutes; and the carbonyl iron powder coated with KH560 silane coupling agent in step (1) was added thereto and stirred at a speed of 1000 rpm until no obvious particles were present, thereby obtaining a uniformly stirred mixture.

[0045] (3) Grind the mixture with a three-roll mill, grind it 8 times, put it into a dispersion tube at 80°C, and disperse it with a high-speed disperser at a speed of 2000 rpm for 5 minutes; then increase the speed to 4000 rpm until the temperature of the mixture in the dispersion tube reaches 70°C, reduce the speed to 2000 rpm, and disperse it for 5 minutes.

[0046] (4) Place the dispersed mixture into a vacuum degassing box for degassing at a pressure of 10 -3 Pa, the time is 20min, and the secondary degassing treatment is carried out until the bubbles disappear completely, the degassed mixture is cast into a mold preheated at 80°C, and the mold is placed in an oven for curing treatment. The curing treatment is specifically heated from 25°C to 80°C, and kept warm for 20min; then heated to 110°C, and kept warm for 30min; then heated to 150°C, and kept warm for 40min; continued to heat to 160°C, and kept warm for 120min, and finally cooled with the furnace, demolded and taken out to obtain a strong and tough absorbing epoxy resin sheet with a size of 300mm×300mm×2mm.

[0047] This embodiment tests the electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet. The test results are as follows: Figure 2 As shown by Figure 2 It can be seen that the strong and tough absorbing epoxy resin sheet of this embodiment has good attenuation constant and impedance matching characteristics; the Shore hardness, tensile strength, elongation at break and corrosion resistance of the strong and tough absorbing epoxy resin sheet are shown in Table 1, which are 93HD, 53.2MPa, 3.7% and 230min respectively.

[0048] Example 3

[0049] This embodiment provides a strong and tough microwave-absorbing epoxy resin sheet, which specifically includes the following raw materials in parts by weight:

[0050] 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 4080 parts of carbonyl iron powder, 2856 parts of KH560 coupling agent, 2040 parts of anhydrous ethanol, 12 parts of BYK-555 defoamer, 11 parts of BYK-191 dispersant, and 210 parts of anhydride curing agent.

[0051] The specific method for preparing the microwave-absorbing epoxy resin sheet is as follows:

[0052] (1) 2040 parts of anhydrous ethanol, 4080 parts of carbonyl iron powder and 2856 parts of KH560 silane coupling agent were weighed and set aside according to weight. The anhydrous ethanol was heated to 60° C. and KH560 silane coupling agent was added by stirring with a heating magnetic device. After stirring for 40 minutes, the solution was cooled to room temperature and carbonyl iron powder was added. After continuous stirring for 2 hours, the solution was dried to obtain carbonyl iron powder coated with KH560 silane coupling agent.

[0053] (2) 261 parts of 862 epoxy resin, 27 parts of 128 epoxy resin, 12 parts of E39D epoxy resin, 12 parts of BYK-555 defoamer, and 11 parts of BYK-191 dispersant were weighed into a stainless steel container according to weight, and stirred evenly with a high-speed disperser until the liquid color was uniform, the speed was 500 rpm, and the dispersion time was 5 minutes; 210 parts of anhydride curing agent were added thereto and stirred at a speed of 500 rpm for a dispersion time of 5 minutes; and the carbonyl iron powder coated with KH560 silane coupling agent in step (1) was added thereto and stirred at a speed of 1000 rpm until no obvious particles were present, thereby obtaining a uniformly stirred mixture.

[0054] (3) Grind the mixture with a three-roll mill, grind it 8 times, put it into a dispersion tube at 80°C, and disperse it with a high-speed disperser at a speed of 2000 rpm for 5 minutes; then increase the speed to 4000 rpm until the temperature of the mixture in the dispersion tube reaches 70°C, reduce the speed to 2000 rpm, and disperse it for 5 minutes.

[0055] (4) Place the dispersed mixture into a vacuum degassing box for degassing at a pressure of 10 -3 Pa, the time is 20min, and the secondary degassing treatment is carried out until the bubbles disappear completely, the degassed mixture is cast into a mold preheated at 80°C, and the mold is placed in an oven for curing treatment. The curing treatment is specifically heated from 25°C to 80°C, and kept warm for 20min; then heated to 110°C, and kept warm for 30min; then heated to 150°C, and kept warm for 40min; continued to heat to 160°C, and kept warm for 120min, and finally cooled with the furnace, demolded and taken out to obtain a strong and tough absorbing epoxy resin sheet with a size of 300mm×300mm×2mm.

[0056] This embodiment tests the electromagnetic parameters of the strong and tough microwave-absorbing epoxy resin sheet. The test results are as follows: Figure 3 As shown by Figure 3 It can be seen that the strong and tough absorbing epoxy resin sheet of this embodiment has good attenuation constant and impedance matching characteristics; the Shore hardness, tensile strength, elongation at break and corrosion resistance of the strong and tough absorbing epoxy resin sheet are shown in Table 1, which are 96HD, 55.8MPa, 2.8% and 245min respectively.

[0057] Example 4

[0058] This embodiment provides a toughened absorbing epoxy resin sheet. The difference between this embodiment and Example 1 is that: 180 parts of 862 epoxy resin, 72 parts of 128 epoxy resin, and 48 parts of E39D epoxy resin are used. The preparation method is the same as that of Example 1.

[0059] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the microwave-absorbing epoxy resin sheet of this embodiment are shown in Table 1.

[0060] Example 5

[0061] This embodiment provides a toughened absorbing epoxy resin sheet. The difference between this embodiment and Example 1 is that: 282 parts of 862 epoxy resin, 10 parts of 128 epoxy resin, and 8 parts of E39D epoxy resin are used. The preparation method is the same as that of Example 1.

[0062] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the microwave-absorbing epoxy resin sheet of this embodiment are shown in Table 1.

[0063] Comparative Example 1

[0064] This comparative example provides a strong and tough absorbing epoxy resin sheet. The difference between this comparative example and Example 1 is that no coupling agent is added, and the preparation method is the same as that of Example 1.

[0065] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the microwave-absorbing epoxy resin sheet of this comparative example are shown in Table 1.

[0066] Comparative Example 2

[0067] This comparative example provides a strong and tough absorbing epoxy resin sheet. The difference between this comparative example and Example 1 is that only one type of epoxy resin, 300 parts of 862 type epoxy resin, is used; and the preparation method is the same as that of Example 1.

[0068] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the comparative microwave-absorbing epoxy resin sheet are shown in Table 1.

[0069] Comparative Example 3

[0070] This comparative example provides a strong and tough absorbing epoxy resin sheet. The difference between this comparative example and Example 1 is that only two types of epoxy resins are used, 261 parts of 862 type epoxy resin and 27 parts of 128 type epoxy resin; the preparation method is the same as that of Example 1.

[0071] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the microwave-absorbing epoxy resin sheet of this comparative example are shown in Table 1.

[0072] Comparative Example 4

[0073] This comparative example provides a strong and tough absorbing epoxy resin sheet. The difference between this comparative example and Example 1 is that only two types of epoxy resins are used, 261 parts of 862 epoxy resin and 12 parts of E39D epoxy resin, and the preparation method is the same as that of Example 1.

[0074] The Shore hardness, tensile strength, elongation at break and corrosion resistance of the microwave-absorbing epoxy resin sheet of this comparative example are shown in Table 1.

[0075] Experimental Example: The tough and resistant wave-absorbing epoxy resin sheets of Examples 1 to 5 and Comparative Examples 1 to 4 were tested for Shore hardness, tensile strength, elongation at break and corrosion resistance. The Shore hardness was tested by referring to GB / T 2411-2008 Plastics and hard rubber using a hardness tester to measure the indentation hardness (Shore hardness); the tensile strength and elongation at break were tested by referring to GBT 2567-2008 "Test Method for Properties of Resin Castings"; the corrosion resistance was tested by referring to GJB 150.11A-2009. The test results are shown in Table 1.

[0076] Table 1

[0077] Group Shore Hardness (HD) Tensile strength(MPa) Elongation at break (%) Corrosion resistance (min) Example 1 94 51.6 3.3 240 Example 2 93 53.2 3.7 230 Example 3 96 52.8 3.5 245 Example 4 91 47.3 2.0 217 Example 5 90 48.2 2.2 213 Comparative Example 1 92 49.3 3.4 25 Comparative Example 2 95 51.0 0.9 220 Comparative Example 3 92 38.4 1.8 210 Comparative Example 4 90 36.7 1.5 215

[0078] According to the data in Table 1, the microwave-absorbing epoxy resin plates of Examples 1 to 5 have high hardness, good toughness and corrosion resistance.

[0079] In Comparative Example 1, no coupling agent is added, and the carbonyl iron powder cannot be coated, which increases the contact area between the carbonyl iron powder and the outside world. When facing a salt spray environment, it is susceptible to corrosion, and its corrosion resistance is greatly reduced. Therefore, the corrosion resistance of Comparative Example 1 is much lower than that of Examples 1 to 5.

[0080] From the data of Comparative Examples 2 to 4, it can be found that compared with the microwave-absorbing epoxy resin sheet of the compounded epoxy resin in Example 1, when only one or two epoxy resins are added to Comparative Examples 2 to 4, or the optimal compounded epoxy resin ratio is not used, the elongation at break of the microwave-absorbing epoxy resin sheet is significantly reduced. This is because only one epoxy resin, two epoxy resins, or epoxy resins not in the optimal compounding ratio cannot achieve the purpose of lowering the glass transition temperature during the curing process, and therefore the toughness of the strong and tough microwave-absorbing epoxy resin sheet cannot be improved.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A strong and tough microwave-absorbing epoxy resin sheet, characterized in that: It includes the following raw materials in parts by weight: 180-282 parts of 862 epoxy resin, 10-72 parts of 128 epoxy resin, 8-48 parts of E39D epoxy resin, 2500-4500 parts of carbonyl iron powder, 1750-3150 parts of coupling agent, 1250-2250 parts of anhydrous ethanol, 8-12 parts of defoaming agent, 8-12 parts of dispersant and 210 parts of curing agent.

2. The strong and tough microwave-absorbing epoxy resin sheet according to claim 1, characterized in that: The coupling agent includes one of KH570 silane coupling agent, KH560 silane coupling agent and KH550 silane coupling agent; the defoaming agent includes one of BYK-530 defoaming agent, BYK-555 defoaming agent and BYK-141 defoaming agent.

3. The strong and tough microwave-absorbing epoxy resin sheet according to claim 1, characterized in that: The dispersant includes one of BYK-W903 dispersant, BYK-191 dispersant and BYK-184 dispersant; and the curing agent is an acid anhydride curing agent.

4. A method for preparing a strong and tough microwave-absorbing epoxy resin sheet as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Anhydrous ethanol, carbonyl iron powder and coupling agent are weighed and prepared according to weight parts, and the anhydrous ethanol is first heated to 60° C., the coupling agent is added and stirred until the temperature drops to room temperature, and then the carbonyl iron powder is added, and the mixture is continuously stirred for 2 hours and then dried to obtain carbonyl iron powder coated with the coupling agent; (2) mixing 862 epoxy resin, 128 epoxy resin and E39D epoxy resin according to parts by weight to obtain a composite epoxy resin, adding a defoamer, a dispersant, a curing agent and the carbonyl iron powder coated with the coupling agent of step (1) thereto, and stirring thoroughly to obtain a mixture; (3) Grinding, dispersing, degassing and curing the mixture of step (2) to obtain a strong and tough microwave-absorbing epoxy resin sheet.

5. The method for preparing a strong and tough microwave-absorbing epoxy resin sheet according to claim 4, characterized in that: The grinding was performed by grinding the mixture several times in a three-roll mill.

6. The method for preparing a strong and tough microwave-absorbing epoxy resin sheet according to claim 4, characterized in that: The ground mixture was placed in a dispersion tube at 80°C and dispersed by a high-speed disperser at a speed of 2000 rpm for 5 minutes. The speed was then increased to 4000 rpm until the mixture temperature in the dispersion tube reached 70°C, and the speed was then reduced to 2000 rpm for 5 minutes.

7. The method for preparing a strong and tough microwave-absorbing epoxy resin sheet according to claim 4, characterized in that: The dispersed mixture was placed in a vacuum degassing box for degassing at a pressure of 10 -3 Pa, the time is 20min, and the degassing treatment is carried out multiple times until the bubbles disappear.

8. The method for preparing a strong and tough microwave-absorbing epoxy resin sheet according to claim 4, characterized in that: The degassed mixture is placed in a mold at 80°C, and the mold is placed in an oven for curing. The curing process is specifically heating from 25°C to 80°C and keeping warm for 20 minutes; then heating to 110°C and keeping warm for 30 minutes; then heating to 150°C and keeping warm for 40 minutes; continuing to heat to 160°C and keeping warm for 120 minutes, finally cooling with the furnace, demolding and taking out to obtain a strong and tough absorbing epoxy resin sheet.

9. The method for preparing a strong and tough microwave-absorbing epoxy resin sheet according to claim 4, characterized in that: The weight ratio of the anhydrous ethanol, carbonyl iron powder and coupling agent is 0.6:1:0.

7.

10. Use of the strong and tough absorbing epoxy resin sheet as claimed in any one of claims 1 to 3 in antennas or radars.

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