High-efficiency wave-absorbing preparation process for synergistically modifying resin and wave-absorbing agent
By adding a microwave absorbing agent to the resin and adjusting its proportion to form a layered or uniform distribution, the problem of rapidly and efficiently preparing microwave absorbing materials is solved, achieving the effects of simple process, flexible adjustment of microwave absorption performance and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies make it difficult to quickly and efficiently prepare microwave absorbing materials with excellent microwave absorption performance, and the problem of electromagnetic performance deviation caused by changing traditional matrix materials is prominent.
By adding microwave absorbing powder to the resin and adjusting the ratio of resin to microwave absorbing agent, microwave absorbing materials are prepared by layering or uniform mixing. The density difference between the resin and the microwave absorbing agent is used to form a layered structure or uniform distribution, thereby optimizing the electromagnetic parameters of the composite material.
The preparation process is simple and highly applicable, and the absorption frequency and intensity can be flexibly adjusted according to the needs, reducing production costs, improving production efficiency, and the test results are more consistent with actual applications.
Smart Images
Figure CN121801415A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave absorbing materials technology, and in particular relates to a high-efficiency microwave absorbing preparation process that synergistically modifies resin and microwave absorbing agent. Background Technology
[0002] With the rapid development of modern science and technology, the negative impact of electromagnetic radiation on the environment is becoming increasingly prominent. In scenarios such as airport flight scheduling and the use of sophisticated medical equipment in hospitals, electromagnetic interference can cause serious problems such as flight delays and medical instrument malfunctions. Against this backdrop, the development of absorbing materials that can efficiently block and attenuate electromagnetic radiation has become an important research topic in the field of materials science.
[0003] Electromagnetic radiation can cause direct or indirect harm to the human body through thermal, non-thermal, and cumulative effects. Ferrite absorbing materials, with their superior performance in terms of wide absorption band, high absorption rate, and thin thickness, have been proven to be the best-performing absorbing material currently available. They can be integrated into electronic devices to absorb leaked electromagnetic radiation and effectively eliminate electromagnetic interference. Furthermore, absorbing materials not only have key applications in the military field but also drive the development of anti-interference devices in the civilian electronics industry. Currently, they are gradually moving towards commercialization, with their application scope continuously expanding, demonstrating enormous market potential. Therefore, there is an urgent need for a rapid and efficient method to prepare absorbing coatings with excellent absorption performance. Summary of the Invention
[0004] To achieve the above objectives, this invention provides a highly efficient microwave absorption preparation process that synergistically modifies resin and microwave absorbing agent. By adding microwave absorbing agent powder to the resin and adjusting the ratio of resin to microwave absorbing agent, the electromagnetic parameters of the composite material are altered, thereby optimizing the microwave absorption capability of the composite material.
[0005] The present invention discloses a high-efficiency microwave absorbing preparation process for synergistic modification of resin and microwave absorbing agent, comprising the following steps: uniformly mixing matrix material and microwave absorbing agent in a certain proportion and preparing a slurry; and obtaining microwave absorbing material after curing the slurry.
[0006] The matrix material includes a resin matrix and a curing agent. The resin matrix includes epoxy resin and phenolic resin.
[0007] The mass ratio of resin matrix to curing agent is 3:1, and the mass ratio of the total mass of resin matrix and curing agent to the mass of microwave absorber is 3:1 to 1:3.
[0008] When epoxy resin is used as the microwave absorbing resin matrix, amine or acid anhydride curing agents are used; when phenolic resin is used as the resin matrix, medium- and high-temperature curing agents such as benzoyl peroxide (BPO) or methyl ethyl ketone peroxide (MEKP) are used.
[0009] When epoxy resin is used as the resin matrix, the resin matrix is first mixed with the microwave absorber, and then the curing agent is added and mixed thoroughly during the stirring process to ensure that the resin, curing agent and microwave absorber are in uniform contact inside. The system can spontaneously carry out the curing reaction when left to stand at room temperature (20℃-25℃).
[0010] When using phenolic resin as the resin matrix, a staged temperature-increasing curing method is adopted: the resin matrix is first mixed with the curing agent and pre-cured at a low temperature of 40℃-60℃. Then, the microwave absorber is added and stirred evenly, and the temperature is raised to 80℃-120℃ for medium-temperature stage curing, which promotes the enhanced activity of molecular chain movement and accelerates the cross-linking reaction rate.
[0011] Finally, the degree of curing can be further improved according to the curing requirements by performing post-curing treatment at a high temperature of 120℃-150℃ to eliminate residual stress inside the system and promote the improvement of the cross-linked network structure.
[0012] The microwave absorbing agent includes dielectric loss type microwave absorbing agent and magnetic loss type microwave absorbing agent, preferably samarium iron nitrogen powder material.
[0013] After the resin matrix and the microwave absorbing agent are mixed and cured, delamination occurs between the resin matrix and the microwave absorbing agent, and between the matrix material and the microwave absorbing agent. This promotes dielectric loss and controls the effective absorption range of the microwave absorbing material to be 9GHz~15GHz, with a bandwidth of 6GHz.
[0014] During the curing process, the absorber and the resin matrix spontaneously separate due to their different densities, resulting in a layered structure in the absorbing material. This layered structure naturally creates a resin-to-resin / absorbing agent interface, which promotes dielectric loss and improves the absorption frequency band of the absorber. Simultaneously, the absorber can be selected based on density, choosing absorbers with densities similar to the resin, such as nano-carbon particles. During curing, this results in a mixed absorbing material where the absorber is uniformly dispersed within the resin. Furthermore, the resin slurry containing the absorber can be coated onto the substrate material for curing before curing, or, depending on size requirements, customized curing molds can be used to evenly spread the slurry inside the mold and cure it for the specified time. Complex-sized parts can be treated using multiple brush coatings or mold curing methods.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0016] (1) The preparation process is simple. The slurry is prepared by uniformly mixing the resin matrix material and the microwave absorbing agent in a certain proportion, and then the microwave absorbing material can be obtained by brushing or curing with a mold. Therefore, this process can be directly applied to mass industrial production.
[0017] (2) Depending on the needs, the same absorbing agent can be cured in one or multiple passes to prepare the absorbing coating, or a different absorbing agent can be cured multiple times to prepare a absorbing material with a different multi-layer coating. In industrial production, it can be flexibly selected and manufactured according to the needs, which improves production efficiency and reduces the fundamental problem of high production cost of preparing large-size absorbing coatings.
[0018] (3) This process has the characteristics of strong applicability. It can lay resin slurry containing wave absorber in mechanical reinforcing fiber, which not only enhances mechanical properties but also makes the composite material have a certain wave absorption property.
[0019] In summary, this invention uses resin as the matrix phase and composites it with an absorbing agent for modification. By precisely controlling the density matching relationship between the absorbing agent and the resin matrix, the composite method of the absorbing agent in the resin matrix (such as layered composite, uniform dispersion composite, etc.) is specifically determined, thereby achieving efficient control over the material's microwave absorption performance. Furthermore, the microwave absorption performance of test samples prepared using this process directly corresponds to that of industrial-grade finished products. Compared to traditional testing schemes using paraffin as the matrix, this effectively avoids the problem of electromagnetic performance deviation caused by changing the matrix material, significantly improving the guiding value of the test results for practical applications. This invention aims to rapidly and efficiently prepare microwave absorbing coatings, establishing a process flow for microwave absorbing composite coatings. Simultaneously, by simply adjusting the content of the resin matrix and the absorbing agent, the absorption frequency and intensity can be changed, reducing the complexity of the coating preparation process and providing a new solution for the production and modification of electromagnetic wave absorbing materials. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of a coaxial annular sample microwave absorbing material prepared by curing using a coaxial mold; where S1 is m(AB):m(SFN) = 3:1, S2 is m(AB):m(SFN) = 1:1, and S3 is m(AB):m(SFN) = 1:3.
[0021] Figure 2 The dispersion diagram shows the change of dielectric constant of the coaxial annular sample absorbing material in Example 1 (S1~S3) with electromagnetic field frequency; where (a) is the real part of the dielectric constant and (b) is the imaginary part of the dielectric constant.
[0022] Figure 3 The image shows the dispersion plots of the permeability of the coaxial annular sample absorbing material in Example 1 (S1~S3) as a function of electromagnetic field frequency; where (a) is the real part of the permeability and (b) is the imaginary part of the permeability.
[0023] Figure 4 The diagram shows the microwave absorption performance of the coaxial annular sample absorbing material in Example 1 (S1~S3).
[0024] Figure 5The image shows a composite board with a wave-absorbing material coating cured by brush coating process in Example 2; where (a) is m(AB):m(SFN)=1:1 and (b) is m(AB):m(SFN)=2:1.
[0025] Figure 6 The reflectance diagram of the composite plate containing the absorbing material in Example 2 is shown in the range of 0~18GHz. Detailed Implementation
[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. It should be noted that the embodiments described in this invention are only for further explanation and illustration, and not for limiting their application scope. Based on this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention.
[0027] Example 1
[0028] Raw material selection: AB resin (abbreviated as AB) is selected as the matrix material, wherein component A is E-51 bisphenol A type epoxy resin and component B is polyamide 650 curing agent. The ratio of m(A):m(B) = 3:1 is used as the overall resin matrix and the microwave absorber for quality control. The microwave absorber is samarium iron nitrogen (abbreviated as SFN) powder. m(AB) powder and m(SFN) powder are prepared into slurries with mass ratios of 3:1 (S1), 1:1 (S2), and 1:3 (S3), respectively.
[0029] In the preparation of the slurry, resin component A is first mixed with the microwave absorber powder, and curing agent component B is added during stirring. Equal amounts of the three slurries are then placed into a 7mm standard coaxial ring sample mold (a 7mm coaxial ring is a standard testing method). Because SFN has a higher density than AB resin, SFN and AB resin can achieve layered curing during the curing process. After natural curing at room temperature, the layered effect is achieved. Figure 1 As shown, demolding and sampling operations are then performed.
[0030] The electromagnetic parameters of samples S1, S2, and S3 were characterized using a vector network analyzer. The electromagnetic parameters of the three samples were measured, and the electromagnetic wave reflectivity at the same thickness was calculated. The measurement results are as follows: Figures 2-4 As shown.
[0031] from Figure 2 (a) and Figure 2 (b) and Figure 3 (a) and Figure 3(b) shows that changing the content of resin and absorbing agent significantly alters the electromagnetic parameters of the absorbing material. Regarding the dielectric constant, sample S1, with a higher content of AB resin, exhibits the highest imaginary part of the dielectric constant, while sample S2 has the largest real part. Regarding permeability, the composite of AB resin and SFN significantly increases the permeability of the absorbing material; that is, the composite can simultaneously increase dielectric loss and induce new magnetic losses.
[0032] Figure 4 The electromagnetic wave reflectivity of coaxial annular samples S1, S2, and S3 was calculated. It was found that S2 exhibits superior reflectivity, with an effective absorption bandwidth of 9 GHz to 15 GHz and a bandwidth as high as 6 GHz. This indicates that the method of this invention can be used to prepare high-performance absorbing materials.
[0033] Example 2
[0034] Raw material selection: Phenolic resin component A and high-temperature curing agent (benzoyl peroxide-BPO) component B are used as matrix materials, and SFN powder is used as microwave absorber. The ratio of m(resin):m(BPO) is 3:1. Then, slurries are prepared with the ratios of m(resin + curing agent):m(microwave absorber), i.e., m(AB):m(SFN), which are 1:1 and 2:1.
[0035] In the slurry preparation process, phenolic resin and BPO are first mixed thoroughly in a 50℃ water bath at a mass ratio of 3:1 for pre-curing. Then, SFN microwave absorbing agent is added and stirred evenly. The slurry prepared by the above two mass ratios is then brushed onto an aluminum plate at 120℃ for curing. The specific brushing process is as follows: The aluminum plate is 180mm×180mm in size and placed on a heating table. The temperature of the aluminum plate is controlled within the range of 120±5℃. Each brush stroke applies 0.5mm~0.8mm of slurry, followed by static curing for approximately 5 minutes. After 3~4 repeated brush strokes, the coating thickness is controlled between 2.5mm~3.0mm. After complete curing, demolding is performed to obtain a composite thin plate containing a microwave absorbing material coating. Figure 5 (a) and Figure 5 (b) shows the text on the label in the figure (which is not related to the invention).
[0036] The electromagnetic reflectivity of the composite thin plate in the range of 1 GHz to 18 GHz was measured using the bow-beam test method (refer to GJB 5239-2004). The electromagnetic reflectivity of the sample was measured, such as... Figure 6 As shown, the effective absorption range of the composite thin plate with a matrix material to absorber mass ratio of 1:1 is 10GHz~12GHz, with a bandwidth of 2GHz, while the effective absorption range of the composite thin plate with a matrix material to absorber mass ratio of 2:1 is 9GHz~12GHz, with a bandwidth of 3GHz.
[0037] In summary, by adjusting the ratio of resin to microwave absorber, the microwave absorption capacity and absorption frequency band can be effectively controlled, which also shows that the present invention is one of the effective processes for modifying microwave absorbers.
Claims
1. A high-efficiency microwave absorbing preparation process that synergistically modifies resin and microwave absorbing agent, characterized in that, The process includes the following: uniformly mixing a matrix material and a microwave absorbing agent in a certain proportion to prepare a slurry, and obtaining a microwave absorbing material after the slurry is cured; the matrix material includes a resin matrix and a curing agent.
2. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 1, characterized in that, The mass ratio of the resin matrix to the curing agent is 3:1, and the mass ratio of the total mass of the resin matrix and the curing agent to the mass of the microwave absorber is 3:1 to 1:
3.
3. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 1, characterized in that, The resin matrix includes epoxy resin and phenolic resin.
4. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 3, characterized in that, When the resin matrix is epoxy resin, amine or acid anhydride curing agents are used; when the resin matrix is phenolic resin, benzoyl peroxide or methyl ethyl ketone peroxide curing agents are used.
5. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 3, characterized in that, When the resin matrix is epoxy resin, the resin matrix is first mixed with the microwave absorber, and then the curing agent is added and mixed during the stirring process, and cured at room temperature.
6. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 3, characterized in that, When the resin matrix is phenolic resin, a staged temperature-increasing curing method is adopted: the resin matrix is first mixed with the curing agent and pre-cured at a low temperature of 40℃-60℃, then the microwave absorbing agent is added and mixed evenly, and the temperature is raised to 80℃-120℃ for medium-temperature stage curing.
7. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 6, characterized in that, After curing at the intermediate temperature stage, the temperature is raised to 120℃-150℃ for post-curing treatment to eliminate residual stress inside the system and promote the improvement of the cross-linked network structure.
8. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 1, characterized in that, The microwave absorbing agent includes dielectric loss type microwave absorbing agent and magnetic loss type microwave absorbing agent.
9. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 8, characterized in that, The microwave absorbing agent is a samarium iron nitrogen powder material.
10. The high-efficiency microwave absorbing preparation process of synergistic modification of resin and microwave absorbing agent according to claim 1, characterized in that, During the curing process, delamination occurs between the resin matrix and the microwave absorbing agent, and between the matrix material and the microwave absorbing agent, which promotes dielectric loss and controls the effective absorption range of the microwave absorbing material to 9GHz~15GHz.