High-performance aramid fiber, fiber-reinforced composite material and preparation method thereof

Abstract

The application discloses a kind of high-performance aramid fiber and preparation method and application of its composite material.The preparation method of the fiber includes: after 2,5-bis (4-aminophenyl) pyrimidine is pretreated, it is mixed with p-phenylenediamine, 3,4'-diamino diphenyl ether, is made by multistage twin-screw continuous polycondensation, dry spraying wet spinning and high-temperature heat stretching.The synergistic effect of introducing 2,5-bis (4-aminophenyl) pyrimidine rigid reinforcing unit and flexible ether bond unit, and specific preparation process, make the fiber have high strength, high modulus and high elongation.The fiber reinforced composite material provided is the sandwich structure board material that the above-mentioned fiber reinforced upper and lower panel and aramid paper honeycomb core material are compounded, and its preparation method includes prepreg preparation, panel forming and co-curing steps.The fiber reinforced composite material obtained by the application is suitable for the high-end interior and secondary load-bearing structure of aerospace, rail transit and other fields with extreme requirements of lightweight, impact resistance and mechanical properties.

Description

Technical Field

[0001] This invention relates to aramid fibers, their preparation methods, and applications, specifically to the field of high-performance aramid fiber material preparation and fiber-reinforced composite materials technology. Background Technology

[0002] Para-aramid, or poly(p-phenylene terephthalamide) fiber, is a typical single-component, high-performance aramid fiber composed of repeating units of a single type. Its highly regular molecular chains and high crystallinity endow the fiber with extremely high specific strength and specific modulus, making it widely used in protective and aerospace applications. However, its highly rigid molecular chain structure also leads to inherent drawbacks such as low elongation at break (typically <3.5%), poor compressive fatigue resistance, and insufficient toughness, limiting its application in high-end load-bearing structures requiring high energy absorption and repeated deformation.

[0003] To overcome the aforementioned drawbacks, those skilled in the art typically employ copolymerization modification, which involves introducing a third monomer during polymerization to disrupt the complete regularity of the molecular chains, sacrificing some rigidity for increased flexibility. On the other hand, to achieve more complex properties, multi-component composite fiber technology has also been developed. For example, through side-by-side, core-sheath, or island-of-the-sea spinning techniques, two or more polymers with different properties are combined in the same fiber to combine the advantages of each component. However, such technologies are complex, suffer from significant interfacial bonding issues, and generally fail to achieve the superior comprehensive mechanical properties and thermal stability found in para-aramid fibers and their copolymers.

[0004] In summary, while existing technologies have improved the elongation at break of fibers to some extent through copolymerization modification of para-aramid fibers, they still generally suffer from common challenges such as "discontinuous production processes, low efficiency, and high costs," as well as "the need for further improvement in overall performance (especially the synergistic effect of high strength, high modulus, and high elongation)." Therefore, developing a new method that enables continuous, efficient, and controllable polymerization to prepare single-component copolymerized aramid fibers with excellent strength, modulus, and high elongation in one step is of great significance for promoting the upgrading of high-performance aramid materials and expanding their application areas. This is precisely the technical problem that this invention aims to solve. Summary of the Invention

[0005] To address the above technical problems, this invention provides a high-performance aramid fiber, a fiber-reinforced composite material, and a method for preparing the same. The specific technical solution is as follows: In a first aspect, the present invention provides a method for preparing high-performance aramid fibers, characterized by comprising the following steps: Step 1, Monomer Pretreatment: Add 2,5-bis(4-aminophenyl)pyrimidine to a dry NMP / CaCl2 composite solvent, slowly heat to 50-55℃ under nitrogen protection, and stir until uniformly dispersed to obtain the pre-reaction solution; Step 2: Add p-phenylenediamine and 3,4'-diaminodiphenyl ether sequentially to the pre-reaction solution at 20-30℃, stir to dissolve, and then cool to 0~-5℃ to obtain a total diamine mixed solution; Step 3: Add terephthaloyl chloride to the total diamine mixed solution and mix using a first-stage twin-screw mixer at a speed of 100-200 r / min to form a prepolymer mixture; Step 4: Control the temperature of the prepolymer mixture at 0-10℃ and carry out the second-stage twin-screw mixing at a speed of 150-300r / min to form the prepolymer stock solution; Step 5: Control the temperature of the prepolymer solution at 50-80℃, add terephthaloyl chloride, and mix with a third-stage twin-screw mixer at a speed of 100-500 r / min to form a polymer solution; Step 6: Neutralize, degas, and filter the polymer solution to obtain the spinning solution. Perform dry-jet wet spinning and heat-stretch the resulting fibers at 380-480℃ and a tension of 0.3-1.2 cN / dtex to obtain the final product.

[0006] Preferably, the molar ratio of p-phenylenediamine, 3,4'-diaminodiphenyl ether, and 2,5-bis(4-aminophenyl)pyrimidine is (0.5~0.7):1.0:(0.20~0.30).

[0007] Preferably, the terephthaloyl chloride added in step 3 accounts for 55% to 75% of the total amount added (calculated by molar amount).

[0008] Preferably, the polymer solution obtained in step 5 has a solid content of 6% to 14% and a dynamic viscosity of 100,000 to 400,000 centipoise at 25°C.

[0009] PPD (p-phenylenediamine) provides a rigid framework, determining the upper limits of strength and modulus. When its proportion is <0.5, insufficient rigid segments result in a significant decrease in fiber strength and modulus, losing the high-performance nature of aramid. When its addition proportion is >0.7, excessive rigid segments lead to overly rigid molecular chains, resulting in poor solubility in solvents, easy precipitation, fiber brittleness, and excessively low elongation at break. Furthermore, the synergistic effect with 2,5-bis(4-aminophenyl)pyrimidine (BAMPym) is weakened. Adding an appropriate amount ensures sufficient rigidity while leaving space for flexible segments (ODA) and reinforcing units (BAMPym), achieving a balance between rigidity and flexibility.

[0010] 3,4'-ODA (3,4'-diaminodiphenyl ether) provides flexible ether bonds, disrupts crystallization, and improves elongation and solubility. Insufficient addition leads to polymer precipitation, making spinning impossible. Excessive addition results in excessive flexibility, causing a linear decline in fiber strength and modulus, potentially failing to meet high strength requirements (<25 cN / dtex).

[0011] BAMPym, as a core reinforcing unit, provides π-π stacking and hydrogen bonding, consuming energy during deformation and improving strength, modulus, and toughness. When its addition ratio is <0.20, the reinforcing effect is insufficient, and the performance is close to that of ordinary flexible aramid, with no significant improvement in strength and modulus. When its addition ratio is >0.30, the polymerization reaction activity may be reduced due to steric hindrance, resulting in a lower molecular weight and a plateau in performance improvement.

[0012] This invention employs a multi-stage temperature-controlled, stepped-speed twin-screw continuous polycondensation process, achieving precise control over the polymerization process and resulting in a polymer solution with a narrow molecular weight distribution and good batch stability. Combined with dry-jet wet spinning, the spinning speed is significantly increased, resulting in high production efficiency. Furthermore, the use of an NMP / CaCl2 composite solvent system reduces costs compared to traditional wet spinning solvents.

[0013] By introducing 2,5-bis(4-aminophenyl)pyrimidine, which has rigid planar structures and hydrogen bonding sites, as a third monomer, a ternary copolymer was formed with p-phenylenediamine and 3,4'-diaminodiphenyl ether. The introduction of the pyrimidine ring created a strong π-π stacking and multiple hydrogen bond network between the molecular chains, which effectively dissipates energy when the fiber is subjected to stress. Combined with the moderate disruption of the crystalline structure by the flexible ether bond units (from 3,4'-diaminodiphenyl ether), the orientation structure was finally locked through high-temperature thermal stretching, resulting in fibers that simultaneously possess high strength, high modulus, and high elongation.

[0014] In a second aspect, the present invention provides a high-performance aramid fiber prepared by the above method.

[0015] A third aspect of the present invention provides a fiber-reinforced composite material with the aforementioned high-performance aramid fiber as the core reinforcement. The fiber-reinforced composite material provided by the present invention has a sandwich structure, comprising upper and lower panels and a core material disposed therebetween. The upper and lower panels are composed of reinforcing fibers and a prepreg containing a resin matrix, wherein the reinforcing fibers are high-performance aramid fibers obtained by the aforementioned method; and the core material is aramid paper honeycomb.

[0016] Preferably, the thickness of the upper and lower panels is 0.5-2mm each, the thickness of the core material is 5-20mm, and the ratio of the core material thickness to the thickness of a single-sided panel is 5:1 to 20:1.

[0017] Preferably, the resin matrix in the prepreg is a mixture of epoxy resin and cyanate ester resin, with a mass ratio of 1 to 3:1.

[0018] In a fourth aspect, the present invention also provides a method for preparing the above-mentioned composite material, comprising: High-performance aramid fibers are made into non-woven fabric; The resin matrix, curing agent and toughening agent are mixed evenly in proportion and vacuum degassed to prepare a prepreg. The prepreg is evenly laid on the surface of the above non-woven fabric, pre-cured by heating and pressurizing and then cut to make the upper and lower panels. The upper and lower panels are stacked with the aramid paper honeycomb core material and heated and pressurized at 160-180℃ and 0.3-0.6 MPa for 1-3 hours to cure and form the final product.

[0019] Preferably, the curing agent is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and hexahydrophthalic anhydride; Preferably, the toughening agent is at least one of polyethersulfone microspheres, carboxyl-terminated butadiene nitrile rubber, polyethersulfone, and polycarbonate.

[0020] The fiber-reinforced composite material provided by this invention uses high-strength, high-toughness aramid fibers prepared according to this invention as reinforcement. After being compounded with a toughening resin matrix, the upper and lower panels of the resulting fiber-reinforced composite material inherit the excellent mechanical properties and energy absorption capacity of the fibers. Structurally, it adopts a sandwich structure of "high-performance aramid panel + aramid honeycomb core." The aramid paper honeycomb core material not only provides extremely high specific stiffness, achieving significant weight reduction, but also has good matching coefficients of thermal expansion with the panel material, resulting in a strong interfacial bond. The final composite material sheet has extremely high specific strength, specific stiffness, excellent impact resistance and delamination resistance, as well as good flame retardancy and fatigue resistance, making it particularly suitable for high-end interior and secondary load-bearing structures in aerospace, rail transportation, and other fields. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] It should be noted that, unless otherwise specified, all raw materials used in this invention are conventional raw materials that can be commercially obtained in the field. Unless otherwise specified, all testing methods used employ national standards or industry-standard methods in the field.

[0023] The aramid paper honeycomb used in the examples and comparative examples was ACCH-2I-2.75-48D (cell side length of 2.75 mm, density of 48 kg / m3) from AVIC Composite Materials Co., Ltd. Example 1

[0024] Preparation of high-performance aramid fibers: Raw materials and proportions: The composite solvent is composed of NMP (water content ≤100 ppm) and CaCl2, with CaCl2 content at 2 wt%. The monomer molar ratio is: p-phenylenediamine (PPD): 3,4'-diaminodiphenyl ether (3,4'-ODA): 2,5-bis(4-aminophenyl)pyrimidine (BAMPym) = 0.6 : 1.0 : 0.25, and the molar ratio of TPC to total diamine is 1.004 : 1.

[0025] Polymerization process: Step 1: Add BAMPym to the composite solvent, heat to 55°C under nitrogen protection, and stir for 90 minutes; Step 2: Under nitrogen protection, cool down to 25°C, add PPD and 3,4'-ODA in sequence, stir until completely dissolved, and cool to -5°C; Step 3: Add the first batch of terephthaloyl chloride (TPC, accounting for 70% of the total TPC) to the solution obtained in Step 2, and put it into a three-stage twin-screw system for the first stage (-5℃, 50 rpm, 15min) twin-screw stirring and mixing to form a prepolymer mixture; Step 4: Perform a second stage (0℃, 80 rpm, 20 min) twin-screw mixing to form a prepolymer stock solution; Step 5: Perform the third stage (add the remaining 30% TPC, 75℃, 450 rpm, 50min) with twin-screw stirring to form a polymer solution with a solid content of 10.5% and a dynamic viscosity of 280,000 centipoise at 25℃. Step 6: After neutralization, degassing, and filtration, the polymer solution is subjected to dry-jet wet spinning (spinneret orifice diameter 0.065 mm, air gap, spinning speed 60 m / min, coagulation bath 30% NMP aqueous solution). The resulting nascent fibers are then hot-stretched at 420℃ and tension 0.8 cN / dtex to obtain high-performance aramid fibers.

[0026] Comparative Example 1 Except for the omission of BAMPym and the adjustment of the molar ratio of PPD to 3,4'-ODA to 0.85:1.0 to maintain the total number of amino groups, the other raw materials, solvents, polymerization and spinning process parameters were exactly the same as in Example 1.

[0027] Comparative Example 2 The polymer solution was prepared and spun using the exact same process as in Example 1, but the final hot stretching step was omitted, and only conventional drying was performed.

[0028] Comparative Example 3 The same raw materials and proportions as in Example 1 were used, but the polymerization process was changed to a traditional low-temperature solution batch reactor polymerization: all the diamine and TPC were added at once in a jacketed reactor at -5°C and the reaction was carried out with low-speed stirring; other characteristics were also the same as in Example 1.

[0029] Due to the intense exothermic reaction, temperature control was difficult, and the reaction system was not uniform. The final polymer solution had a solid content of only 8% and exhibited large viscosity fluctuations. After spinning and hot stretching under the same conditions...

[0030] Comparative Example 4 Without the addition of 3,4'-ODA, the other characteristics are the same as in Example 1.

[0031] Comparative Example 5 (1) Raw materials and proportions: The composite solvent consists of NMP (water content ≤100 ppm) and CaCl2, with CaCl2 content at 2 wt%. The monomer molar ratio is: p-phenylenediamine (PPD): 3,4'-diaminodiphenyl ether (3,4'-ODA): 2,5-bis(4-aminophenyl)pyrimidine (BAMPym) = 0.6 : 1.0 : 0.25, and the molar ratio of TPC to total diamine is 1.004 : 1.

[0032] (2) Polymerization process: Step 1: Add BAMPym to the composite solvent, and under nitrogen protection and at 25°C, add PPD and 3,4'-ODA in sequence, stir until completely dissolved, and cool to -5°C; Step 2: Add the first batch of terephthaloyl chloride (TPC, accounting for 70% of the total TPC) to the solution obtained in Step 1, and put it into a three-stage twin-screw system for the first stage (-5℃, 50 rpm, 15min) twin-screw stirring and mixing to form a prepolymer mixture; Step 3: Perform a second stage (0℃, 80 rpm, 20 min) of twin-screw mixing to form a prepolymer stock solution; Step 4: Perform the third stage (add the remaining 30% TPC, 75℃, 450 rpm, 50min) with twin-screw stirring to form a polymer solution with a solid content of 10.5% and a dynamic viscosity of 280,000 centipoise at 25℃. Step 5: After neutralization, degassing, and filtration, the polymer solution is subjected to dry-jet wet spinning (spinneret orifice diameter 0.065 mm, air gap, spinning speed 60 m / min, coagulation bath 30% NMP aqueous solution). The resulting nascent fibers are then hot-stretched at 420℃ and tension 0.8 cN / dtex to obtain the final product.

[0033] Performance testing The mechanical properties of the above four fibers were tested according to GB / T 14344, and the results are recorded in Table 1.

[0034] Fracture strength (cN / dtex) Elastic modulus (cN / dtex) Elongation at break (%) Example 1 32.5 720 5.8 Invention Solution Comparative Example 1 24.1 480 6.2 Without BAMPym, the tensile modulus drops sharply. Comparative Example 2 26.3 580 4.1 Without hot stretching, the properties were not fully activated. Comparative Example 3 28.9 650 4.5 Intermittent polymerization results in poor performance uniformity. Comparative Example 4 - - - Without added ODA, the polymerization system precipitates out, making spinning impossible. Comparative Example 5 27.8 610 5.0 BAMPym's performance is significantly reduced due to lack of preprocessing. Comparative Example 1, employing a traditional approach that only introduces flexible ether groups, achieved a high elongation but suffered significant losses in strength and modulus. In contrast, Example 1, while introducing flexible ether bonds, also incorporates the rigid planar structure of BAMPym. The π-π stacking of its pyrimidine rings and the hydrogen bond network create "reversible physical crosslinking points" between the molecular chains. This "rigid-flexible" molecular design allows the flexible segments to provide deformation during fiber stretching, while the rigid network bears and transmits stress. This results in a significant leap in strength and modulus while maintaining excellent elongation at break.

[0035] In Comparative Example 2, without thermal stretching, the molecular chains and pyrimidine rings of BAMPym were not fully oriented, and its reinforcing network was not effectively constructed, resulting in all properties not reaching their optimal levels.

[0036] Comparative Example 3 employed a traditional batch process. Although the same monomers were used, uneven reaction mixing and imprecise temperature control resulted in a wide polymer molecular weight distribution, poor solution properties, and ultimately, fiber performance lower than that of Example 1. This demonstrates that the "multi-stage twin-screw continuous polycondensation" process employed in this invention, through precise segmented control of temperature, shear, and reaction progress, is the key guarantee for the reproducible and stable preparation of the aforementioned high-performance molecular structures.

[0037] In Comparative Example 4, the 3,4'-ODA monomer was missing. The flexible chain segments and steric hindrance provided by the ether bonds of the 3,4'-ODA monomer are crucial for disrupting the excessively rigid and easily crystallizable molecular chain structure formed by PPD and BAMPym. Without ODA, the resulting copolymer has extremely poor solubility in NMP / CaCl2 solvent, leading to precipitation during polymerization and rendering the system completely unspinnable. Example 2

[0038] Preparation of composite materials The aramid fibers obtained in Example 1 were processed into a non-woven fabric with a basis weight of 200 gsm.

[0039] Take 100 parts by weight of epoxy resin (E51), 50 parts of cyanate ester resin (BTCy), 35 parts of curing agent 4,4'-diaminodiphenyl sulfone, and 10 parts of toughening agent (core-shell rubber particles), mix them evenly, and after vacuum degassing, apply the adhesive evenly to the non-woven fabric using a scraping method. Pre-cure by hot pressing at 120℃ and 0.4 MPa for 15 minutes. After cutting, the upper and lower panels with a thickness of 1.0 mm are obtained. Aramid paper honeycomb (8mm) was used as the core material and laid in the order of "top panel - core material - bottom panel". It was placed in a hot press and cured at 175℃ and 0.5 MPa for 2 hours to obtain a sandwich composite material with a total thickness of 10 mm.

[0040] Comparative Example 6 Composite materials using commercially available para-aramid (DuPont Kevlar 29) Except for replacing the reinforcing fiber (high-performance aramid fiber of Example 1) with commercially available para-aramid (DuPont Kevlar 29) nonwoven fabric of the same specification, all other materials (resin, core material) and preparation process parameters are exactly the same as in Example 2, and a sandwich composite material is obtained.

[0041] Comparative Example 7 Coreless solid layer composite material Without composite core material, using the same panel material and process as in Example 2, the multi-layer panels are stacked and cured in one step to obtain a solid layer composite material with a total thickness of about 4 mm, making its surface density comparable to that of sandwich composite material.

[0042] Performance testing: The key mechanical and physical properties of the three composite materials were tested, and the results are recorded in the table below.

[0043] Test Project Example 2 Comparative Example 6 Comparative Example 7 Test Standards Surface density (kg / m²) 2.8 2.8 2.8 - Bending stiffness (relative value) 1.00 0.95 0.35 ASTM D790 Falling hammer impact energy (J) 45 32 28 ASTM D7136 Backside damage after impact No cracks, only dents Minor matrix cracking Fiber breakage, penetration Visual inspection Vertical flammability rating V-0 V-0 V-0 UL-94

[0044] Under the same structure and process, the composite material using the fibers of this invention exhibits approximately 5% higher flexural stiffness and 40% higher impact energy absorption capacity than the sheet material using commercial aramid (Kevlar 29), respectively. This demonstrates that the high modulus and high toughness of the high-performance aramid fibers of this invention are successfully transferred from the fiber level to the composite material level. In particular, after impact, the composite material obtained by this invention only shows dents, while the composite material using commercial aramid (Kevlar 29) shows matrix cracking, highlighting the superior damage tolerance brought about by the synergistic effect of the fibers and toughening resin matrix of this invention.

[0045] At the same areal density, the flexural stiffness of the sandwich-structured composite material obtained by this invention is nearly three times that of the solid-layer composite material (obtained in Comparative Example 7). This demonstrates that the composite material of this invention possesses lightweight and high-stiffness characteristics. Furthermore, its impact resistance is significantly superior to that of the composite material obtained in Comparative Example 7. This indicates that the use of the high-performance aramid fiber of this invention in composite materials is beneficial for achieving extreme lightweighting and high performance of components.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-performance aramid fiber, characterized in that, Includes the following steps: Step 1, Monomer Pretreatment: Add 2,5-bis(4-aminophenyl)pyrimidine to a dry NMP / CaCl2 composite solvent, and slowly heat to 50-55℃ under nitrogen protection. Stir at this temperature until the mixture is evenly dispersed to obtain the pre-reaction solution. Step 2: Under nitrogen protection, add p-phenylenediamine and 3,4'-diaminodiphenyl ether sequentially to the pre-reaction solution at 20-30℃ and stir until homogeneous. Then cool the resulting total diamine mixture to 0-5℃. Step 3: Add terephthaloyl chloride to the solution obtained in Step 2 and stir to mix. Then, perform first-stage twin-screw stirring and mixing at a speed of 100-200 r / min to form a prepolymer mixture. Step 4: Control the temperature of the prepolymer mixture at 0-10℃ and perform a second-stage twin-screw mixing at a speed of 150-300 r / min to form the prepolymer stock solution; Step 5: Control the temperature of the prepolymer solution at 50-80℃, add terephthaloyl chloride, and then mix it with a third-stage twin-screw mixer at a speed of 100-500 r / min to form a polymer solution. Step 6: After neutralizing, degassing, and filtering the polymer solution to obtain the spinning solution, dry-jet wet spinning is performed. The resulting fibers are then subjected to hot stretching treatment at 380-480℃ and a tension of 0.3-1.2 cN / dtex to obtain high-performance aramid fibers.

2. The method according to claim 1, characterized in that, The molar ratio of p-phenylenediamine: 3,4'-diaminodiphenyl ether: 2,5-bis(4-aminophenyl)pyrimidine is (0.5~0.7): 1.0: (0.20~0.30).

3. The method according to claim 1, characterized in that, The terephthaloyl chloride added in step 3 accounts for 55% to 75% of the total amount of terephthaloyl chloride added in steps 3 and 5.

4. The method according to claim 1, characterized in that, The polymer solution obtained in step 5 has a solid content of 6% to 14% and a dynamic viscosity of 100,000 to 400,000 centipoise at 25°C.

5. A high-performance aramid fiber prepared by the method according to any one of claims 1-4.

6. A fiber-reinforced composite material, characterized in that, The fiber-reinforced composite material has a sandwich structure, including: upper and lower panels and a core material disposed between the upper and lower panels; the upper and lower panels are composed of reinforcing fibers and a prepreg including a resin matrix, wherein the reinforcing fibers are the high-performance aramid fibers as described in claim 5; and the core material is aramid paper honeycomb.

7. The method for preparing the fiber-reinforced composite material according to claim 6, characterized in that, The thickness of the upper and lower panels is 0.5-2mm each, the thickness of the core material is 5-20mm, and the ratio of the core material thickness to the thickness of a single-sided panel is 5:1 to 20:

1.

8. The fiber-reinforced composite material according to claim 6, characterized in that, The resin matrix in the prepreg is a mixture of epoxy resin and cyanate ester resin, with a mass ratio of 1 to 3:

1.

9. A method for preparing a fiber-reinforced composite material according to any one of claims 6, characterized in that, Includes the following steps: High-performance aramid fibers are spun into non-woven fabric; Take 100 parts by weight of resin matrix, 30-35 parts by weight of curing agent and 10 parts by weight of toughening agent, mix them evenly, and then degas them under vacuum to obtain prepreg material; The prepreg material is evenly laid on the surface of the nonwoven fabric, and after pre-curing by heating and pressurizing and cutting, the upper and lower panels are obtained. The upper panel, core material, and lower panel are stacked, and then heated and pressurized to obtain the fiber-reinforced composite material.

10. The method for preparing the fiber-reinforced composite material according to claim 9, characterized in that, The curing agent is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and hexahydrophthalic anhydride; Or / and the toughening agent is at least one of polyethersulfone microspheres, carboxyl-terminated nitrile rubber, polyethersulfone, and polycarbonate.