Wave-absorbing prepreg, preparation method thereof and composite material
By loading a suitable ratio of high-temperature epoxy resin, ferrite absorber and silane coupling agent onto aramid fiber cloth to prepare microwave absorbing prepreg, the problems of residual stress and curing deformation caused by the difference in thermal expansion coefficients after co-curing of microwave absorbing prepreg and carbon fiber unidirectional tape prepreg were solved, and better interlayer performance and assembly reliability were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-17
AI Technical Summary
Existing microwave absorbing prepregs, after being co-cured with carbon fiber unidirectional tape prepregs, suffer from significant differences in their coefficients of thermal expansion, resulting in large residual stress and curing deformation, making assembly difficult and even causing cracking or delamination.
Using aramid fiber cloth as a carrier, a microwave absorbing material composed of high-temperature epoxy resin, ferrite absorber and silane coupling agent in appropriate proportions is loaded. The microwave absorbing prepreg is prepared by coating and composite process, and the coefficient of thermal expansion is controlled within 4×10-6/℃ to reduce residual stress and curing deformation after co-curing.
It significantly reduced the deformation after co-curing, avoided damage to functional layer structural components, and improved interlayer performance and assembly reliability.
Smart Images
Figure CN121672971A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of microwave absorbing materials technology, and more specifically, to microwave absorbing prepregs, their preparation methods, and composite materials. Background Technology
[0002] Existing microwave-absorbing prepregs are prepared in a two-step process involving microwave-absorbing slurry and quartz fiber cloth via hot-melt bonding. Their typical warp and weft coefficients of thermal expansion are 30 × 10⁻⁶. -6 / ℃, and the coefficient of thermal expansion of unidirectional carbon fiber tape prepreg (typically 1×10⁻⁶ after isotropic layup). -6 The difference in temperature (°C) is significant, resulting in large residual stress and curing deformation after co-curing, which makes it difficult to assemble functional structural components and may even cause cracking, delamination and other problems.
[0003] In view of this, the present invention is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide microwave absorbing prepreg, its preparation method, and composite materials, aiming to improve at least one of the problems mentioned in the background art.
[0005] This invention is implemented as follows: In a first aspect, the present invention provides a microwave absorbing prepreg, comprising an aramid fiber cloth and a microwave absorbing material loaded on the aramid fiber cloth; The microwave absorbing material comprises, by weight, 100 parts high-temperature epoxy resin, 350-400 parts ferrite absorber, and 1-5 parts silane coupling agent; Each square meter of aramid fiber cloth is combined with 700~800g of microwave absorbing material.
[0006] In an optional embodiment, the absorbent is selected from at least one of carbon powder, graphene, silicon nitride, and ferrite.
[0007] In an optional embodiment, the coupling agent is selected from at least one of KH560, RT-3162, J&Y N321 and J&Y N326.
[0008] In an optional embodiment, the high-temperature epoxy resin is selected from at least one of WP-H1655, WP-H2002, EH200 and BAC828.
[0009] In an optional embodiment, the method for preparing the microwave absorbing material includes: High-temperature epoxy resin is placed in a mixer and stirred and melted at 65~75℃. Then, silane coupling agent is added and mixed evenly. Finally, ferrite absorbent is added and mixed evenly. Optionally, the mixing speed of the internal mixer is set to 14.5~15.5 r / min; Optionally, after adding high-temperature epoxy resin, mix for 15-25 minutes; after adding silane coupling agent, mix for 1-3 minutes; after adding ferrite absorbent, mix for 25-35 minutes.
[0010] In an optional embodiment, the weight of the aramid fiber fabric per square meter is 150~200g.
[0011] Secondly, the present invention provides a method for preparing a microwave absorbing prepreg as described in any of the foregoing embodiments, comprising: The microwave absorbing material is made into a film; The microwave-absorbing material is pressed onto the opposite sides of an aramid fiber cloth to obtain a microwave-absorbing prepreg.
[0012] In an optional embodiment, the thickness of the membrane-like absorbing material is 0.10~0.12 mm.
[0013] In an optional embodiment, a coating machine is used to form the microwave absorbing material into a film, and the roller temperature of the coating machine is 77~81°C. Optionally, a laminating machine is used to press the film-shaped microwave absorbing material onto the opposite sides of the aramid fiber cloth, with the heating roller temperature being 79.5~80.5℃.
[0014] Thirdly, the present invention provides a composite material, comprising a microwave absorbing prepreg and a carbon fiber prepreg as described in the foregoing embodiments, which are co-cured.
[0015] The present invention has the following beneficial effects: The microwave absorbing prepreg provided by this invention, because it is composed of a suitable ratio of high-temperature epoxy resin, ferrite absorber, and silane coupling agent, and uses aramid fiber cloth as the loading matrix, and a suitable amount of microwave absorbing material is laminated on the aramid fiber cloth, results in a typical value of 4×10⁻⁶ for the warp and weft thermal expansion coefficients of the microwave absorbing prepreg. -6 / ℃ can significantly reduce the residual stress and curing deformation generated after co-curing with carbon fiber unidirectional tape prepreg, and prevent damage to functional layer structural components (back-end products). Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the coating machine. Figure 2 This is a schematic diagram of the composite machine. Figure 3 The graph shows the warp thermal expansion coefficient test curve of the microwave absorbing prepreg in Example 1. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0019] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0020] This invention provides a microwave absorbing prepreg, comprising an aramid fiber cloth and a microwave absorbing material loaded on the aramid fiber cloth; The microwave absorbing material comprises, by weight, 100 parts high-temperature epoxy resin, 350-400 parts ferrite absorber, and 1-5 parts silane coupling agent; Each square meter of aramid fiber cloth is combined with 700~800g of microwave absorbing material.
[0021] High-temperature epoxy resin, as the matrix resin, can bond fibers and absorbents together and transfer loads. The absorbent, as a functional filler, plays a role in absorbing electromagnetic waves. The coupling agent can improve the interfacial properties between the resin, absorbent, and fiber cloth, and improve the interlaminar properties of the microwave absorbing prepreg. A suitable combination of these three components can yield a microwave absorbing slurry with excellent absorption and bonding properties. Aramid fiber cloth has high specific strength and specific modulus, as well as a negative coefficient of thermal expansion, but its bonding ability with epoxy resin is poor. Composite materials prepared using it as raw material have a low coefficient of thermal expansion, but poor interlaminar properties. When this microwave absorbing slurry is composited onto aramid fiber cloth, the typical values of its warp and weft coefficients of thermal expansion can reach (3~5)×10⁻⁶. -6 / ℃ can significantly reduce the residual stress and curing deformation generated after co-curing with carbon fiber unidirectional tape prepreg, thus preventing damage to functional layer structural components.
[0022] It should be noted that the components of the microwave absorbing material must be within the proportion range specified in this invention. For example, if the ferrite absorber content is too high, the low proportion of high-temperature epoxy resin will result in failure to form a film, while if the ferrite absorber content is too low, the microwave absorption effect will be poor. If the silane coupling agent content is too high, it will cause excessive cross-linking reaction with aramid fibers, resulting in uneven stress on the fibers, affecting resin curing, and ultimately leading to a decrease in interlayer performance. If the content is too low, it will also lead to insufficient interlayer performance.
[0023] The amount of microwave absorbing material composited on aramid fiber cloth should be within the range required by this invention. Too much or too little will make it difficult to achieve good results. If the composite amount is too little, it will be difficult to produce. If the composite amount is too much, the coefficient of thermal expansion will increase.
[0024] Optionally, the absorbent is selected from at least one of carbon powder, graphene, silicon nitride, and ferrite.
[0025] Optionally, the coupling agent is selected from at least one of KH560, RT-3162, J&Y N321 and J&Y N326.
[0026] Optionally, the high-temperature epoxy resin is selected from at least one of WP-H1655, WP-H2002, EH200 and BAC828.
[0027] Methods for preparing microwave absorbing materials include: The high-temperature epoxy resin is placed in a mixer and stirred and melted at 65~75℃. Then, a silane coupling agent is added and mixed evenly. Finally, a ferrite absorber is added and mixed evenly.
[0028] Specifically, the preparation method is as follows: The equipment is an internal mixer, with a mixing speed of 14.5~15.5 r / min, a temperature of 65~75℃, and a holding time of 25~35 min; Add high-temperature epoxy resin and mix for 15-25 minutes to fully melt the resin; Add silane coupling agent and mix for 1-3 minutes to ensure uniform dispersion of the coupling agent; Add the absorbent and mix for 25-35 minutes to ensure the slurry is evenly dispersed, thus obtaining a microwave absorbing material in which all components are evenly dispersed.
[0029] The method for preparing the microwave absorbing prepreg provided in this embodiment of the invention includes: The microwave absorbing material is made into a film; The microwave-absorbing material is pressed onto the opposite sides of an aramid fiber cloth to obtain a microwave-absorbing prepreg.
[0030] Specifically, the preparation method is as follows: S1, Coating The equipment is a coating machine, such as Figure 1 As shown; Heating and heat preservation: the temperature of the comma roller is (79±2)℃, the temperature of the C roller is (79±2)℃, the temperature of the large heating plate is (79±2)℃, and heat preservation is carried out for (60~65) min after reaching the specified temperature. Calibrate the gap; the gap between the C roller and the comma roller is (0.10~0.11) mm. For the adhesive bonding and paper threading process, the microwave absorbing material is divided into small pieces and placed on a large heating plate for adhesive bonding. The adhesive bonding time is 60-65 minutes. Release paper is then threaded and PE film is pasted on the equipment. Start the equipment with the overall speed at (3±0.5) m / min, the speed of roller B at (100±5)%, the speed ratio of roller C at (150±5)%, the unwinding tension at (310±2) N, and the winding tension at (150±2) N. After coating and applying the adhesive, the microwave absorbing material is squeezed by the comma roller and the C roller to form an adhesive film of a fixed thickness and adhere to the C roller. After the release paper is unwound, it passes through the B roller and the C roller. The adhesive film is transferred from the C roller to the release paper. Then, it is shaped by the cooling mechanism to prevent flow and deformation. Finally, it is covered with plastic film and wound up.
[0031] After coating, a film-like microwave absorbing material with a thickness of 0.10~0.12mm is obtained.
[0032] S2, Composite The equipment is a composite machine, such as Figure 2 As shown; Heating and heat preservation: the temperature of the coating roller is (30±2)℃, the temperature of the No. 3 heating roller is (80±0.5)℃, the temperature of the No. 2 heating roller is (80±0.5)℃, and the temperature of the No. 1 heating roller is (75±0.5)℃. After reaching the specified temperature, heat preservation is carried out for (60~65) min. Calibrate the gaps; adjust the gaps between heating rollers #1, #2, and #3 to (0.40~0.41) mm. Threading and splicing: The two prepared rolls of adhesive film are fed onto the machine, and release paper is threaded through them. Start the equipment with a global speed of (1±0.5) m / min, a winding tension of (240±2) N for the top adhesive film and (220±2) N for the bottom adhesive film, and a winding tension of (170±2) N for the finished product, (170±2) N for the top paper, (70±2) N for the top PE film, and (70±2) N for the bottom PE film. The lamination process involves unwinding two rolls of coated microwave-absorbing material, cooling them with cooling rollers, peeling off the plastic film to expose the material, placing the two rolls face each other, and simultaneously unwinding the fiber cloth. All three are then pulled by traction rollers into heating rollers. The microwave-absorbing material melts upon heating, and pressure is applied to force the material into the gaps in the fiber cloth. Heating rollers 1#, 2#, and 3# all provide heating and pressure, while heating plates 1 and 2 provide insulation. After extrusion, the material is cooled and shaped by cold plates, the release paper is rolled up, a mesh film is applied, and finally, the roll is wound up again.
[0033] The composite process is completed to obtain microwave absorbing prepreg.
[0034] This invention also provides a composite material, comprising: The microwave absorbing prepreg and carbon fiber prepreg provided in the embodiments of the present invention are co-cured to obtain the product.
[0035] Because the microwave absorbing prepreg and carbon fiber prepreg provided in this embodiment of the invention are co-cured, the deformation amount is reduced by 8 mm compared with the existing microwave absorbing prepreg co-curing.
[0036] Example 1 The microwave absorbing prepreg is provided, which comprises 100 parts of high-temperature epoxy resin (WP-H1655), 380 parts of ferrite absorber and 3 parts of silane coupling agent (KH560). The preparation method of microwave absorbing prepreg is as follows: The equipment is an internal mixer, with a mixing speed of 15 r / min, a temperature of 70℃, and a holding time of 30 min. Add high-temperature epoxy resin and mix for 20 minutes to fully melt the resin; Add silane coupling agent and mix for 2 minutes to ensure uniform dispersion of the coupling agent; Add the absorbent and mix for 30 minutes to ensure the slurry is evenly dispersed, thus obtaining a microwave absorbing material in which all components are evenly dispersed.
[0037] We offer aramid fiber fabric, brand name 100C170.
[0038] According to the preparation method of the microwave absorbing prepreg described above, a film-shaped microwave absorbing material with a thickness of 0.10 mm is prepared by step S1, and then the film-shaped microwave absorbing material is pressed onto the opposite sides of the aramid fiber cloth by step S2 to obtain a microwave absorbing prepreg with a thickness of 0.36 mm. The microwave absorbing material mass in each square meter of microwave absorbing prepreg is 780 g.
[0039] Example 2 This embodiment is basically the same as Embodiment 1, except that the composition of the microwave absorbing prepreg includes: 100 parts of high-temperature epoxy resin (grade WP-H1655), 350 parts of ferrite absorber and 1 part of silane coupling agent (KH560).
[0040] The prepared absorbing material contains 700g of absorbing material per square meter.
[0041] Example 3 This embodiment is basically the same as Embodiment 1, except that the composition of the microwave absorbing prepreg includes: 100 parts of high-temperature epoxy resin (brand name WP-H1655), 400 parts of ferrite absorber and 5 parts of silane coupling agent (KH560).
[0042] The prepared absorbing material contains 800g of absorbing material per square meter.
[0043] Comparative Example 1 This comparative example is basically the same as Example 1, except that it uses quartz fiber cloth.
[0044] Experimental Example The microwave absorbing prepregs provided in the various embodiments and comparative examples were co-cured with carbon fiber prepregs. The carbon fiber prepreg was AC531 / CCF800H, and the co-curing method was autoclave curing, following the recommended curing process for AC531 / CCF800H.
[0045] The performance of the microwave absorbing prepregs provided in each embodiment and comparative example was tested, wherein tensile properties were tested according to ASTM D3039, compressive properties were tested according to ASTM D6641, flexural properties were tested according to ASTM D7264, interlaminar shear strength was tested according to ASTM D2344, and coefficient of thermal expansion was tested according to ASTM E831. The deformation of the co-cured composite material was tested. The specific test method involved placing the co-cured test panel flat on a horizontal table, with the microwave-absorbing prepreg layer on top and the carbon fiber prepreg layer on the bottom. A vernier caliper was used to measure the distances from the bottom surface of the four corners of the test panel to the table surface, and the average of the four measurements was calculated. The test results were recorded in Table 1.
[0046] Table 1 Performance test results of each embodiment and comparative example
[0047] As can be seen from Table 1, the microwave absorbing prepregs prepared in the various embodiments of the present invention have excellent physical properties. After being combined with carbon fiber prepregs, the deformation is small, significantly less than that of the comparative examples. Comparing Comparative Examples 3 and 4 with Example 1, the effects of Comparative Examples 3 and 4 are significantly worse than those of Example 1, indicating that the loading amount of microwave absorbing material on the aramid fiber cloth should not be too much or too little; both excessive and insufficient loading will make it difficult to achieve good results.
[0048] In summary, the microwave absorbing prepreg provided by this invention, due to its composition of a suitable ratio of high-temperature epoxy resin, ferrite absorber, and silane coupling agent, and using aramid fiber cloth as the loading matrix, achieves typical values of 4×10⁻⁶ thermal expansion coefficients in both the warp and weft directions. -6 / ℃ can significantly reduce the residual stress and curing deformation generated after co-curing with carbon fiber unidirectional tape prepreg, thus preventing damage to functional layer structural components.
[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A wave-absorbing prepreg, characterized by, The aramid fiber cloth and a wave-absorbing material loaded on the aramid fiber cloth are included. The wave-absorbing material includes 100 parts of high-temperature epoxy resin, 350-400 parts of ferrite absorber and 1-5 parts of silane coupling agent. 700-800 g of the wave-absorbing material is compounded with each square meter of the aramid fiber cloth.
2. The wave-absorbing prepreg according to claim 1, characterized by, The absorber is selected from at least one of carbon powder, graphene, silicon nitride and ferrite.
3. The wave-absorbing prepreg according to claim 1, characterized in that, The coupling agent is selected from at least one of KH560, RT-3162, J&Y N321 and J&Y N326.
4. The wave-absorbing prepreg according to claim 1, characterized by, The high-temperature epoxy resin is selected from at least one of WP-H1655, WP-H2002, EH200 and BAC828.
5. The wave-absorbing prepreg according to claim 1, wherein The preparation method of the wave-absorbing material includes: The high-temperature epoxy resin is placed in a mixing machine and stirred and melted at 65-75 ℃, then the silane coupling agent is added and mixed uniformly, and finally the ferrite absorber is added and mixed uniformly. Optionally, the mixing machine is set to a stirring speed of 14.5-15.5 r / min. Optionally, after the high-temperature epoxy resin is added, the mixing is performed for 15-25 min, after the silane coupling agent is added, the mixing is performed for 1-3 min, and after the ferrite absorber is added, the mixing is performed for 25-35 min.
6. The wave-absorbing prepreg according to claim 1, wherein The mass of each square meter of the aramid fiber cloth is 150-200 g.
7. A method of producing a wave-absorbing prepreg as claimed in any one of claims 1 to 6, characterized by, The wave-absorbing material is prepared into a film shape. The film-shaped wave-absorbing material is laminated on opposite sides of the aramid fiber cloth to obtain the wave-absorbing prepreg. The thickness of the film-shaped wave-absorbing material is 0.10-0.12 mm.
8. The preparation method according to claim 7, characterized in that, The film-shaped wave-absorbing material is prepared by using a film coating machine, and the roller temperature of the film coating machine is 77-81 ℃.
9. The preparation method according to claim 7, characterized in that, Optionally, the film-shaped wave-absorbing material is laminated on opposite sides of the aramid fiber cloth by using a laminating machine, and the heating roller temperature is 79.5-80.5 ℃. The wave-absorbing prepreg is obtained by co-curing the wave-absorbing prepreg and a carbon fiber prepreg.
10. A composite material, characterized by,