A prepreg resin system formulation and preparation method suitable for T300 grade carbon fiber

Abstract

The application discloses a prepreg resin system formula suitable for T300-grade carbon fibers and relates to the technical field of composite materials, and comprises component A and component B; the component A contains liquid epoxy resin, solid epoxy resin and hyperbranched thermoplastic resin micro-nano filler; and the component B contains liquid epoxy resin, dicyandiamide curing agent and urea accelerator; the application improves the interlayer toughness and bonding force of the prepreg, optimizes the process performance of the resin, and improves the glass transition temperature of the resin system, thereby solving the problem of low glass transition temperature of the resin system for the prepreg.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and in particular to a prepreg resin system formulation and preparation method suitable for T300 grade carbon fiber. Technical Background

[0002] The composite materials industry is rapidly developing towards lightweight, high-performance, and low-cost directions, with demand for composite materials continuously rising in fields such as aerospace, rail transportation, new energy vehicles, and wind turbine blades. Prepregs, with their advantages of stable performance and efficient molding, are seeing significant market demand as a core intermediate carrier for composite materials. Composite materials made from carbon fiber / epoxy resin-based prepregs have become one of the core structural materials in these fields due to their high specific strength, specific modulus, good corrosion resistance, and flexible molding processes. Currently, the main prepreg preparation processes are hot-melt and solvent methods. Compared to solvent methods, the hot-melt method, with its advantages of environmental friendliness, high efficiency, and controllable cost, is partially replacing traditional processes. The mainstream hot-melt method is a two-step process, which first prepares the resin into a film, and then combines the film with reinforcing materials to form the prepreg.

[0003] T300 grade carbon fiber, as a general-purpose high-strength carbon fiber, combines excellent mechanical properties with a high cost-performance ratio. It is one of the most widely used and mature carbon fiber varieties, and is widely used in the manufacture of sporting goods, pressure vessels, etc. Epoxy resin has good adhesion, formability, and mechanical properties. Dicyandiamide, as a latent curing agent for epoxy resin, is suitable for solvent-free hot-melt prepreg resin systems. It has advantages such as moderate curing temperature and excellent heat resistance and chemical resistance of cured products. The resin system composed of the two is a classic combination for preparing high-performance carbon fiber prepregs, which meets the current development requirements of the composite materials industry for environmental protection, efficiency, and high performance. It is currently the most common and widely used hot-melt prepreg resin system.

[0004] The preparation of T300 grade carbon fiber prepreg has formed a relatively mature process route in the existing technology, but there are still some technical pain points: (1) the interlayer bonding force of carbon fiber composite products is weak and the interlayer cracking is easy under stress; (2) the viscosity-temperature curve is steep, the resin viscosity changes drastically with the temperature rise during molding, the process window is narrow, and the process performance is poor during molding; (3) the glass transition temperature is low, the thermal stability is poor, and the performance is easily degraded under high temperature environment.

[0005] The invention patent with publication number CN113002024A discloses a method for interlayer toughening of carbon fiber prepreg using a nanoparticle polymer composite nanofiber membrane. This invention utilizes a nanoparticle thermoplastic polymer composite nanofiber membrane as an interlayer reinforcing and toughening material. The composite nanofibers are directly spun onto the prepreg through electrospinning to form a nanofiber membrane toughening layer, which improves the problems of weak interlayer bonding and easy cracking. However, this invention uses a thermoplastic polymer composite nanofiber membrane, which itself has a low glass transition temperature, resulting in poor thermal stability.

[0006] The invention patent with publication number CN102731750A discloses a method for preparing a latent epoxy resin curing system. This invention uses a mixture of dicyandiamide and dicarboxylic acid dihydrazide, along with solvent mixing, to lower the curing temperature to below 120℃. The solvent mixing process can be completed using existing resin mixing equipment, without the need for additional complex steps; only the curing agent ratio and dissolution parameters need to be adjusted, resulting in a low production threshold. Simultaneously, the prepreg can still be stored at room temperature for more than two months, effectively resolving the contradiction between the high curing temperature and long-term storage of the dicyandiamide curing system. However, if the solvent removal process is incomplete during solvent mixing, residual organic solvents will remain in the resin system, causing defects such as bubbles and pinholes during prepreg curing, reducing the density and mechanical properties of the composite material, and resulting in uneven overall performance.

[0007] Chinese patent application CN106893256A discloses an epoxy resin composition for prepregs, its preparation method, and the prepreg. The composition comprises component A and component B. Component A contains solid epoxy resin and a toughening agent, while component B contains liquid epoxy resin, a dicyandiamide curing agent, an imidazole curing agent, and a urea accelerator. The epoxy resin composition for prepregs provided by this invention effectively improves the minimum viscosity retention time and significantly extends the process window. The dicyandiamide-imidazole-urea composite curing system in this invention has a complex reaction mechanism, a long process debugging cycle, and higher requirements for the professional skills of production operators. Furthermore, the use of imidazole curing agents enhances reactivity and shortens the storage time at room temperature.

[0008] Therefore, this invention introduces hyperbranched thermoplastic resin micro / nano fillers, aiming to construct an interpenetrating polymer network structure by leveraging its molecular-level toughening mechanism and interfacial compatibility modification technology. The steric hindrance effect of the filler optimizes the interfacial adhesion of the resin system, solving the problem of interlayer cracking in prepregs. Simultaneously, the uniformly dispersed thermoplastic filler, combined with the controlled ratio of liquid to solid bisphenol A epoxy resin, achieves precise viscosity control, thereby broadening the curing process platform. High-purity solid bisphenol A epoxy resin is selected to construct a dense bisphenol A aromatic ring crosslinking network, increasing the glass transition temperature of the prepreg resin system. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention adopts the following technical solution: a prepreg resin system formulation suitable for T300 grade carbon fiber, comprising component A and component B, wherein component A contains liquid epoxy resin, solid epoxy resin and hyperbranched thermoplastic resin micro-nano filler, and component B contains liquid epoxy resin, dicyandiamide curing agent and urea accelerator.

[0010] Furthermore, the liquid epoxy resin is a liquid bisphenol A type epoxy resin; liquid bisphenol A type epoxy resin: epoxy equivalent 184-190g / eq, viscosity at 25℃ 12000-15000cps; The solid epoxy resin includes: Solid bisphenol A type epoxy resin 1: epoxy equivalent 450-500 g / eq, softening point 64-74℃; Solid bisphenol A type epoxy resin II: epoxy equivalent 1800-2400 g / eq, softening point 130-150℃; Based on a total epoxy resin weight of 100 parts by weight, the resin system contains: 40 parts liquid bisphenol A epoxy resin, 60 parts solid bisphenol A epoxy resin (50 parts solid bisphenol A epoxy resin one, 10 parts solid bisphenol A epoxy resin two), 4.4 parts dicyandiamide curing agent, 1.1 parts urea accelerator, and 5 parts hyperbranched thermoplastic resin micro / nano filler.

[0011] A method for preparing a prepreg resin system suitable for T300 grade carbon fiber includes the following steps: S1. Component A is prepared by mixing liquid epoxy resin, solid epoxy resin and hyperbranched thermoplastic resin micro-nano filler; S2. Component B is prepared by mixing liquid epoxy resin, dicyandiamide curing agent and urea accelerator; S3. Mix component A and component B to obtain an epoxy resin system.

[0012] Furthermore, S1 specifically involves: mixing liquid epoxy resin, solid epoxy resin, and hyperbranched thermoplastic resin micro-nano filler in appropriate proportions using a planetary mixer at 150°C to obtain component A.

[0013] Further, S2 specifically involves: weighing an appropriate amount of liquid epoxy resin, and adding an appropriate amount of dicyandiamide curing agent and urea accelerator powder to the liquid epoxy resin. At room temperature, the powder is uniformly dispersed in the liquid epoxy resin by mechanical stirring. After the mixture is uniformly mixed by mechanical stirring, the formulation parameters of the three-roll mill are set, and the well-stirred system is poured into the three-roll mill for grinding. After grinding until the powder particle size is less than 5μm, the required grinding material is prepared.

[0014] Furthermore, S3 specifically involves: adjusting the temperature of the prepared component A to 60~80℃, adding component B, stirring evenly with a planetary mixer, and then performing vacuum degassing to obtain the target resin system.

[0015] The beneficial effects of this invention are as follows: (1) This invention improves the interlayer toughness and bonding strength of prepreg: This invention introduces hyperbranched thermoplastic resin micro-nano fillers, constructs an interpenetrating polymer network structure by means of molecular-level toughening, and optimizes the resin interface adhesion by utilizing the spatial position effect of the fillers. Compared with the comparative example, it fundamentally solves the problem of weak interlayer bonding strength and easy cracking under stress in the prepreg resin system, and enhances the prepreg's resistance to interlayer cracking; (2) This invention optimizes the resin processing performance: By controlling the solid-liquid bisphenol A epoxy resin ratio through uniformly dispersed thermoplastic fillers, the resin viscosity is precisely adjusted, extending the resin processing performance. The invention slows down the gelation process and broadens the curing process platform. Compared with the comparative example, it solves the problems of short gelation time, steep viscosity-temperature curve, narrow process window, and poor processability of the dicyandiamide curing system during molding. At the same time, it extends the gelation time of the prepreg by relying on the supramolecular inclusion effect of the filler. (3) The invention improves the glass transition temperature of the resin system: high-purity solid bisphenol A epoxy resin is selected to construct a dense bisphenol A aromatic ring crosslinking network. Compared with the comparative example, it improves the glass transition temperature of the prepreg resin system and solves the problem of low glass transition temperature of the resin system used for prepreg. Attached Figure Description

[0016] Figure 1 This is a comparison of the viscosity-temperature curves of the resin systems in Example 1 and Comparative Example 1.

[0017] Figure 2 This is a temperature-enthalpy curve of the resin system in Example 1.

[0018] Figure 3 The temperature-enthalpy curve of the resin system in Comparative Example 1 is shown.

[0019] Figure 4 This is a graph showing the glass transition temperature of the resin system in Example 1.

[0020] Figure 5 This is a graph showing the glass transition temperature of the resin system in Comparative Example 1. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] The composition and weight proportions of a prepreg resin system formulation suitable for T300 grade carbon fiber described in this example are as follows: liquid bisphenol A epoxy resin: 40 parts, solid bisphenol A epoxy resin: 60 parts (solid bisphenol A epoxy resin one: 50 parts, solid bisphenol A epoxy resin two: 10 parts), dicyandiamide curing agent: 4.4 parts, urea accelerator: 1.1 parts, hyperbranched thermoplastic resin micro / nano filler: 5 parts; The resin treatment temperature and time were determined by taking a small sample of resin, measuring the temperature-viscosity curve of the resin using a rotational viscometer, and then measuring the gel time of the resin at a specific temperature using a gel permeameter. The mixing temperature and time were determined by considering all factors, and the viscosity of the resin during vacuum mixing should be controlled at 16 Pa. For temperatures below s, the mixing temperature should be between 60 and 80°C, and the mixing time should be controlled within the gel time of the resin at the mixing temperature. The resin system should be thermally analyzed using a differential scanning calorimeter to determine the curing regime.

[0024] The manufacturing process is as follows: ① Add 32.3 parts of liquid bisphenol A epoxy resin to a planetary mixer, preheat to 150℃, then add 50 parts of solid bisphenol A epoxy resin I, 10 parts of solid bisphenol A epoxy resin II, and 5 parts of hyperbranched thermoplastic resin micro-nano filler. After the two solid epoxy resins have fully melted, turn on the mixer and mechanically stir for 30 minutes to fully disperse the hyperbranched thermoplastic resin micro-nano filler into the resin system to prepare component A. ② Add 4.4 parts of dicyandiamide curing agent and 1.1 parts of urea accelerator to 7.7 parts of liquid bisphenol A epoxy resin, mechanically stir for 20 minutes, and then grind with a three-roll mill until the powder particle size is less than 5μm to prepare component B. ③ Adjust the temperature of the prepared component A to 70℃, add component B, stir with a planetary mixer for 30 minutes, and then perform vacuum degassing to obtain the target resin system; the viscosity of the obtained epoxy resin system at 80℃ is 16 Pa. Near s.

[0025] Prepare the resin system according to the above resin system preparation method; clean the mold, apply a release agent and preheat it in an environment of 120℃ for 30 minutes; slowly inject the prepared resin system into the mold cavity, complete the resin crosslinking reaction according to the preset curing regime, and ensure that the casting is fully cured; after curing, demold the sample and polish it to meet the dimensional accuracy, the specific dimensions refer to GB / T2567-2021; The curing regime, pre-set according to the enthalpy-temperature curve, is as follows: 1. Preheat at 100℃ and keep warm for 2 hours; 2. Heat from 100℃ to 120℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 3. Heat from 120℃ to 130℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 4. Heat from 130℃ to 145℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 5. Heat from 145℃ to 155℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 6. Heat from 155℃ to 170℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 7. Allow to cool naturally from 170°C to room temperature in an oven.

[0026] Example 2

[0027] The above resin system was coated and then prepreg-impregnated with T300 grade carbon fiber fabric to obtain the finished product. The specific method for preparing composite material samples is as follows: Prepreg was prepared by hot melt method, and the prepared prepreg was cut, laid up and cured in an autoclave. The cut size was 300mm×300mm. Seven sheets of prepreg were laid up in the same direction to prepare a (2±0.2)mm thick laminate. The prepreg blank was placed in an autoclave and the autoclave curing process was as follows: a) The vacuum bag is evacuated, and the vacuum pressure inside the vacuum bag is not less than 0.092 MPa; b) Pressurize the autoclave to 0.5 MPa; c) Heat from room temperature to (80±5)℃ at a heating rate of 3℃ / min, and hold at that temperature for (30±5) minutes; d) Heat to (125±5)℃ at a heating rate of 3℃ / min and hold for more than 90min; e) Cool to below 60°C at a cooling rate of 3°C / min (maintain pressure until cooling is complete), open the autoclave to remove the part, and obtain the required laminate.

[0028] Based on the force direction of the tensile and bending tests, reinforcing sheets are bonded to the clamping area of ​​the laminate using structural adhesive. The tensile test reinforcing sheet has a width × thickness of 50 mm × 2 mm, and the compression test reinforcing sheet has a width × thickness of 63.5 mm × 2 mm. After the structural adhesive has fully cured, the laminate is machined to the test specimen dimensions specified in the national standard using a grinding machine. The tensile test specimen preparation standard refers to GB / T3354-2014, the bending test specimen preparation standard refers to GB / T3356-2014, the compression test specimen preparation standard refers to ASTM D6641-16, and the interlaminar shear test specimen preparation standard refers to JC / T773-2010.

[0029] Comparative Example 1

[0030] A commercially available resin system for a similar purpose was preheated to 70°C. The mold was cleaned, coated with a release agent, and preheated at 120°C for 30 minutes. The prepared resin system was slowly injected into the mold cavity, and the resin crosslinking reaction was completed according to the preset curing regime to ensure the casting was fully cured. After curing, the mold was demolded, and the sample was polished to meet dimensional accuracy, specifically referring to GB / T2567-2021. The preset curing regime is as follows: 1. Preheat at 100℃ and keep warm for 2 hours; 2. Heat from 100℃ to 120℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 3. Heat from 120℃ to 130℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 4. Heat from 130℃ to 145℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 5. Heat from 145℃ to 155℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 6. Heat from 155℃ to 170℃ at a rate of 2℃ / min and hold at that temperature for 1 hour; 7. Allow to cool naturally from 170°C to room temperature in an oven.

[0031] Comparative Example 2

[0032] Prepreg was prepared using a hot-melt method. The prepared prepreg was then cut, laid in layers, and cured in an autoclave. The cut fabric size was 300mm × 300mm. Seven sheets of prepreg were laid in the same direction to prepare a 2mm thick laminate. The autoclave curing process was as follows: a) The vacuum bag is evacuated, and the vacuum pressure inside the vacuum bag is not less than 0.092 MPa; b) Pressurize the autoclave to 0.5 MPa; c) Heat from room temperature to (80±5)℃ at a heating rate of 3℃ / min, and hold at that temperature for (30±5) minutes; d) Heat to (125±5)℃ at a heating rate of 3℃ / min and hold for more than 90min; e) Cool to below 60°C at a cooling rate of 3°C / min (maintain pressure until cooling is complete), open the autoclave and remove the part; obtain the required laminate; according to the force direction of the tensile and bending tests, use structural adhesive to attach reinforcing sheets to the clamping area of ​​the laminate, where the tensile test reinforcing sheet width × thickness is 50mm × 2mm, and the compression test reinforcing sheet width × thickness is 63.5mm × 2mm. After the structural adhesive has completely cured, use a grinder to process the laminate to the test specimen dimensions specified in the national standard. The tensile test specimen preparation standard refers to GB / T3354-2014, the bending test specimen preparation standard refers to GB / T3356-2014, the compression test specimen preparation standard refers to ASTM D6641-16, and the interlaminar shear test specimen preparation standard refers to JC / T773-2010.

[0033] The gelation time at 120°C of the resin systems in Example 1 and Comparative Example 1 was tested using a gelation time meter, and the specific method is as follows: 1. Adjust the temperature to 120℃ and stabilize it at this temperature; 2. Gently rub the hot plate with release wax, then wipe the hot plate clean with clean paper towels; 3. Use a small spoon to take 200mg±20mg of resin sample, pour it into the resin pool in the hot plate, and start timing immediately; 4. Use a toothpick to slide the resin in the hot plate in a circular motion to make the resin move evenly in the resin pool of the hot plate. 5. During the stirring process, you will feel the resin in the hot pan becoming thicker and thicker. At this point, you can slide the resin while using a toothpick to pick up and pull out the strands. 6. When the picked resin filament breaks, stop timing immediately. The time recorded at this moment is the resin gelation time.

[0034] The gel times at 120°C for the resin systems in Example 1 and Comparative Example 1 were 851 s and 779 s, respectively. This indicates that the introduction of hyperbranched thermoplastic resin micro / nano fillers extended the gel time of the resin system by 72 s. This result confirms that the hyperbranched thermoplastic resin fillers delayed the gelation and curing process of the resin system through their own steric hindrance effect.

[0035] The viscosity-temperature curves of the resin systems in Example 1 and Comparative Example 1 were tested using a rotational viscometer. A No. 29 rotor was used, with a rotational speed of 30 r / min and a heating rate of 1 °C / min. The test results are as follows: Figure 1As shown, judging from the characteristics of the viscosity-temperature curves, the resin system of Comparative Example 1 only exhibits a stable processing viscosity in the range of 100℃ to 110℃. However, in Example 1 with the addition of hyperbranched thermoplastic resin filler, the stable processing viscosity range is extended to 100℃ to 115℃. This result confirms that the hyperbranched thermoplastic resin filler weakens the thermo-induced viscosity change trend of the resin through molecular chain entanglement effect and steric hindrance, thereby extending the viscosity-temperature processing platform and providing a wider process window for high-temperature molding of the resin.

[0036] The temperature-enthalpy curves of the resin systems in Example 1 and Comparative Example 1 were tested using a differential scanning calorimeter. The heating rate was 10 °C / min, and the nitrogen flow rate was 60 mL / min. The test results are as follows: Figure 2 and Figure 3 As shown, a reasonable curing process was developed based on the temperatures at the starting point, peak value, and ending point.

[0037] The glass transition temperatures of the resin systems in Example 1 and Comparative Example 1 were tested using a differential scanning calorimeter. The heating rate was 10 °C / min, and the nitrogen gas flow rate was 60 mL / min. The test results are as follows: Figure 4 and Figure 5 As shown, the glass transition temperature of Example 1 (119.0°C) is higher than that of Comparative Example 1 (116.9°C). This result confirms that the hyperbranched thermoplastic resin filler forms a stronger intermolecular interaction with the resin matrix, which restricts the mobility of the resin molecular chains and thus increases the glass transition temperature of the resin system.

[0038] The tensile and flexural properties of the resin castings in Example 1 and Comparative Example 1 were tested according to GB / T2567-2021, and the results are shown in Table 1. The elongation at break of Example 1 (3.7%) was almost the same as that of Comparative Example 1 (3.8%), and the toughness was not damaged. However, the flexural strength and modulus increased from 62.3 MPa and 1.9 GPa to 100.7 MPa and 2.7 GPa, respectively, achieving a modification of the resin matrix that combines strength and toughness.

[0039] Table 1. Mechanical properties of resin castings in Example 1 and Comparative Example 1

[0040] name Tensile strength (MPa) Tensile modulus (GPa) Elongation at break (%) Bending strength (MPa) Flexural modulus (GPa) Example 1 80.9 3.4 3.7 100.7 2.7 Comparative Example 1 80.0 3.2 3.8 62.3 1.9

[0041] Mechanical properties were tested on the composite material samples from Example 2 and Comparative Example 2. Tensile properties were tested according to GB / T3354-2014, flexural properties according to GB / T3356-2014, compressive properties according to ASTM D6641-16, and interlaminar shear properties according to JC / T773-2010. The results are shown in Table 2. In the composite material samples, the interlaminar shear strength of Example 2 increased from 50.6 MPa to 61.9 MPa (an increase of over 22%). This significant improvement in core interlaminar toughness, combined with the simultaneous increase in tensile and compressive modulus and strength, proves that the filler achieves toughening of the resin-based material by optimizing the molecular chain interaction of the resin matrix and strengthening the interlaminar interface bonding of the composite material, fully demonstrating its excellent toughening modification effect.

[0042] Table 2. Mechanical properties of composite material specimens in Example 2 and Comparative Example 2

[0043] name Tensile strength (MPa) Tensile modulus (GPa) Bending strength (MPa) Flexural modulus (GPa) Compressive strength (MPa) Compression modulus (GPa) Interlaminar shear strength (MPa) Example 2 818.7 75.8 764.2 77.1 600.7 76.6 61.9 Comparative Example 2 705.0 59.9 784.8 38.2 556.5 55.7 50.6

Claims

1. A prepreg resin system formulation suitable for T300 grade carbon fiber, characterized in that, It includes component A and component B. Component A contains liquid epoxy resin, solid epoxy resin and hyperbranched thermoplastic resin micro-nano filler, and component B contains liquid epoxy resin, dicyandiamide curing agent and urea accelerator.

2. The prepreg resin system formulation suitable for T300 grade carbon fiber as described in claim 1, characterized in that: The liquid epoxy resin is a liquid bisphenol A type epoxy resin; liquid bisphenol A type epoxy resin: epoxy equivalent 184-190g / eq, viscosity at 25℃ 12000-15000cps; The solid epoxy resin includes: Solid bisphenol A type epoxy resin 1: epoxy equivalent 450-500 g / eq, softening point 64-74℃; Solid bisphenol A type epoxy resin II: epoxy equivalent 1800-2400 g / eq, softening point 130-150℃; Based on a total epoxy resin weight of 100 parts by weight, the resin system contains: 40 parts liquid bisphenol A epoxy resin, 60 parts solid bisphenol A epoxy resin (50 parts solid bisphenol A epoxy resin one, 10 parts solid bisphenol A epoxy resin two), 4.4 parts dicyandiamide curing agent, 1.1 parts urea accelerator, and 5 parts hyperbranched thermoplastic resin micro / nano filler.

3. A method for preparing a prepreg resin system suitable for T300 grade carbon fiber, characterized in that, Includes the following steps: S1. Component A is prepared by mixing liquid epoxy resin, solid epoxy resin and hyperbranched thermoplastic resin micro-nano filler; S2. Component B is prepared by mixing liquid epoxy resin, dicyandiamide curing agent and urea accelerator; S3. Mix component A and component B to obtain an epoxy resin system.

4. The method for preparing a prepreg resin system suitable for T300 grade carbon fiber as described in claim 3, characterized in that, Specifically, S1 involves mixing liquid epoxy resin, solid epoxy resin, and hyperbranched thermoplastic resin micro-nano filler in appropriate proportions using a planetary mixer at 150°C to obtain component A.

5. The method for preparing a prepreg resin system suitable for T300 grade carbon fiber as described in claim 4, characterized in that, S2 specifically involves: weighing an appropriate amount of liquid epoxy resin, and adding an appropriate amount of dicyandiamide curing agent and urea accelerator powder to the liquid epoxy resin. At room temperature, the powder is uniformly dispersed in the liquid epoxy resin using mechanical stirring. After the mixture is uniformly mixed by mechanical stirring, the formulation parameters of the three-roll mill are set, and the well-mixed system is poured into the three-roll mill for grinding. After grinding until the powder particle size is less than 5μm, the required grinding material is prepared.

6. The method for preparing a prepreg resin system suitable for T300 grade carbon fiber as described in claim 5, characterized in that, Specifically, S3 involves adjusting the temperature of the prepared component A to 60-80°C, adding component B, stirring evenly with a planetary mixer, and then performing vacuum degassing to obtain the target resin system.

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