High-toughness high-temperature-resistant epoxy resin composition suitable for RTM (Resin Transfer Molding) process and preparation method thereof

Abstract

The invention discloses a high-toughness high-temperature-resistant epoxy resin composition suitable for an RTM (Resin Transfer Molding) process and a preparation method thereof, and relates to the technical field of epoxy resin. The composition comprises a component A and a component B, wherein the component A comprises an epoxy resin mixture, core-shell structure toughening particles and a stabilizer; and the component B is a composite amine curing agent consisting of aromatic amine, alicyclic amine and polyether amine. The epoxy resin mixture is compounded by trifunctional epoxy resin, bisphenol A epoxy resin and alicyclic epoxy resin according to a specific proportion. Through collaborative design of a core-shell particle toughening technology and a composite curing agent system, a cured resin matrix has high toughness and high heat resistance while a super-long process window is maintained, and the technical problem that high toughness, high heat resistance and long operation period are difficult to consider in an RTM process is solved.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin technology, and in particular to a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process and its preparation method. Background Technology

[0002] Resin transfer molding (RTM) is a key process for manufacturing high-performance composite components. This process requires a resin system with low viscosity and a long gel time to ensure adequate wetting of the high-density fiber preform. Simultaneously, the final composite components are often used in harsh environments, requiring the resin matrix to have high toughness to resist impact and microcracks, as well as a high glass transition temperature to maintain mechanical properties at high temperatures.

[0003] In existing technologies, methods to improve the toughness of epoxy resins typically involve adding liquid rubber, thermoplastics, or inorganic nanoparticles. However, these methods face challenges in RTM processes: liquid rubber may induce phase separation and significantly increase viscosity; thermoplastics often fail due to poor compatibility with epoxy resins or filtration by fibers during injection; and inorganic nanoparticles are prone to agglomeration, similarly leading to a sharp increase in viscosity and deterioration in processability.

[0004] Core-shell particles, as pre-formed microparticles with an elastomer core and a rigid polymer shell, can be directly incorporated into epoxy resins as toughening agents. Due to the good compatibility between their shell and the epoxy matrix, and their particle size being much smaller than the interfiber gaps, they are not easily filtered, making them theoretically very suitable for toughening in RTM processes. However, simply introducing core-shell particles is often insufficient to simultaneously achieve extremely high heat resistance and excellent processability. High Tg typically requires high crosslinking density, which contradicts the plastic deformation capacity required for high toughness. Furthermore, achieving high Tg above 190°C usually requires a high-temperature curing system, which makes obtaining an extremely long operating window at a given temperature even more difficult.

[0005] Therefore, developing an epoxy resin system that can simultaneously meet the requirements of ultra-long RTM process window, high toughness, and high heat resistance is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM processes, in order to solve the problem that existing epoxy resin systems cannot simultaneously meet the requirements of ultra-long RTM process window, high toughness, and high heat resistance.

[0007] The present invention also aims to provide a method for preparing a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, thereby preparing a liquid molding resin with high temperature resistance and high toughness, achieving a temperature resistance of over 190℃ and an impact toughness of 30KJ / m. 2The above has a usable period of more than 6 hours.

[0008] In a first aspect, the present invention provides a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, comprising component A and component B in a mass ratio of 100:(25-50); Component A comprises the following substances in parts by weight: 100 parts epoxy resin mixture, 5-15 parts core-shell toughening particles, and 0.1-5 parts stabilizer; Component B is a complex amine curing agent, including aromatic amines, alicyclic amines, and polyether amines.

[0009] By adopting the above technical solutions, the high-toughness, high-temperature resistant epoxy resin composition of the present invention comprises component A and component B in a mass ratio of 100:(25-50). This ratio ensures that the cured system has suitable stoichiometry and reactivity. Component A is composed of 100 parts epoxy resin mixture, 5-15 parts core-shell toughening particles, and 0.1-5 parts stabilizer. The introduction of core-shell particles provides effective stress concentration points and crack passivation mechanisms without significantly increasing the viscosity of the system, thereby greatly improving toughness. The stabilizer can effectively suppress potential side reactions between core-shell particles and epoxy groups during storage and processing, ensuring system stability. Component B includes a composite amine curing agent composed of aromatic amines, alicyclic amines, and polyether amines. This composite curing agent system combines the high-temperature performance of aromatic amines, the yellowing resistance and good toughness of alicyclic amines, and the flexible segments and long pot life of polyether amines. Through synergistic effects, it ensures that the final cured product reaches a glass transition temperature above 190°C while giving the resin an ultra-long low-viscosity operating window of more than 6 hours at a process temperature of 60°C. By using a specific combination and ratio of components A and B, this invention successfully resolves the inherent contradiction between high crosslinking density and high toughness, and between high-temperature curing requirements and a long process window.

[0010] Preferably, the mass ratio of the modified liquid aromatic amine, alicyclic amine and polyether amine is (50-70):(20-40):(10-20).

[0011] Preferably, the epoxy resin mixture comprises trifunctional epoxy resin, bisphenol A type epoxy resin and alicyclic epoxy resin in a mass ratio of (60-80):(10-30):(5-15).

[0012] Preferably, the core-shell toughening particles are acrylate-based core-shell rubber particles, with the core layer comprising cross-linked polybutadiene and / or polybutyl acrylate elastomer, and the shell layer comprising polymethyl methacrylate and / or methacrylate copolymers containing epoxy reactive functional groups.

[0013] Preferably, the stabilizer includes at least one of barbituric acid, citric acid, trimethyl borate, and triethyl borate.

[0014] Preferably, the trifunctional epoxy resin includes amino trifunctional epoxy resin and / or AG-80 epoxy resin.

[0015] Preferably, the average particle size of the core-shell toughening particles is 200–500 nm.

[0016] Preferably, aromatic amines include 4,4-diamino-3,3-diethyldiphenylmethane and / or diaminodiphenylmethane; alicyclic amines include isophorone diamine and / or 1,3-cyclohexanedimethylamine; and polyether amines include polyether amine D-230 and / or polyether amine T-403.

[0017] Secondly, the present invention also provides a method for preparing a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, comprising the following steps: S1. Stir the epoxy resin mixture until it is homogeneous, then add the core-shell toughening particles and stabilizer, and continue to shear, stir and degas to obtain a homogeneous component A. S2. Mix the aromatic amine, alicyclic amine and polyether amine evenly to obtain component B; S3. Mix components A and B in proportion at 40-60°C and inject into the mold. Maintain the mold temperature at 40-60°C and keep the resin mixture viscosity below 0.3 Pa·s for more than 360 min. Then raise the temperature to 180°C±5°C and keep it at that temperature for 2.5-3 h to cure.

[0018] Preferably, in step S1, the temperature for uniform mixing is 60–80°C under vacuum; the speed of shearing and mixing is 1000–3000 rpm; and the time is 30–60 min.

[0019] The beneficial effects of this invention are: 1. This invention selects low-viscosity alicyclic epoxy resin and a specific ratio of flexible polyetheramine, and combines it with stabilizers to finely control the reactivity of the system, so that the resin mixture can maintain a low viscosity of less than 0.3 Pa·s for a long time at a process temperature of 60°C. This provides an ample time window for resin injection and impregnation of fiber preforms for large or complex composite material components, ensuring the adequacy and reliability of the RTM process.

[0020] 2. This invention effectively improves the toughness of epoxy resin compositions by introducing acrylate core-shell rubber particles with a specific particle size range of 200–500 nm as toughening agents. The elastic core of these particles can effectively induce energy dissipation mechanisms such as crazes and shear banding, while their rigid shell, which has good compatibility with the epoxy matrix, ensures effective stress transfer and prevents particle agglomeration or fiber filtration. This "physical composite" toughening method significantly improves the impact toughness of the material to over 30 KJ / m² without sacrificing the system's process viscosity or inducing macroscopic phase separation, greatly enhancing the composite material's resistance to impact damage and microcrack propagation.

[0021] 3. This invention uses a high-functionality trifunctional epoxy resin to construct a high-crosslink density network skeleton, and combines it with a modified liquid aromatic amine with a rigid structure as the main curing agent. This ensures that the cured resin matrix has a solid molecular skeleton and an extremely high glass transition temperature, thereby ensuring that the composite material can maintain excellent mechanical properties and dimensional stability even at high temperatures.

[0022] 4. The invention introduces alicyclic amines into the composite curing agent system. Their unique cyclic structure not only helps to improve the balance between heat resistance and toughness, but also improves the compatibility with epoxy resin. The specific mass ratio of aromatic amines, alicyclic amines and polyether amines optimizes the curing reaction kinetics, so that the resin system reacts slowly at a low temperature of 60°C to maintain a long operating period, while it can be rapidly and completely cured after being heated to 180°C to form a dense and tough network structure. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0024] A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, comprising component A and component B in a mass ratio of 100:(25-50); Component A comprises the following substances in parts by weight: 100 parts epoxy resin mixture, 5-15 parts core-shell toughening particles, and 0.1-5 parts stabilizer; Component B is a complex amine curing agent, including aromatic amines, alicyclic amines, and polyether amines.

[0025] By adopting the above technical solutions, the high-toughness, high-temperature resistant epoxy resin composition of the present invention comprises component A and component B in a mass ratio of 100:(25-50). This ratio ensures that the cured system has suitable stoichiometry and reactivity. Component A is composed of 100 parts epoxy resin mixture, 5-15 parts core-shell toughening particles, and 0.1-5 parts stabilizer. The introduction of core-shell particles provides effective stress concentration points and crack passivation mechanisms without significantly increasing the viscosity of the system, thereby greatly improving toughness. The stabilizer can effectively suppress potential side reactions between core-shell particles and epoxy groups during storage and processing, ensuring system stability. Component B includes a composite amine curing agent composed of aromatic amines, alicyclic amines, and polyether amines. This composite curing agent system combines the high-temperature performance of aromatic amines, the yellowing resistance and good toughness of alicyclic amines, and the flexible segments and long pot life of polyether amines. Through synergistic effects, it ensures that the final cured product reaches a glass transition temperature above 190°C while giving the resin an ultra-long low-viscosity operating window of more than 6 hours at a process temperature of 60°C. By using a specific combination and ratio of components A and B, this invention successfully resolves the inherent contradiction between high crosslinking density and high toughness, and between high-temperature curing requirements and a long process window.

[0026] In some embodiments, the mass ratio of aromatic amine, alicyclic amine, and polyether amine is (50-70):(20-40):(10-20); for example, the mass ratio of aromatic amine, alicyclic amine, and polyether amine can be 50:20:10, 60:30:15, or 70:40:20. By adopting the above specific ratio, the curing reaction rate, crosslinking network structure, and chain segment flexibility can be precisely controlled. A higher proportion of aromatic amine ensures heat resistance, an appropriate amount of alicyclic amine helps improve toughness and compatibility, and the addition of polyether amine significantly prolongs the duration of the low viscosity plateau, enabling the system to maintain a stable low viscosity for more than 360 minutes at 60°C.

[0027] In some embodiments, the epoxy resin mixture includes a trifunctional epoxy resin, a bisphenol A epoxy resin, and an alicyclic epoxy resin in a mass ratio of (60-80):(10-30):(5-15); for example, the epoxy resin mixture includes a trifunctional epoxy resin, a bisphenol A epoxy resin, and an alicyclic epoxy resin in a mass ratio of 60:10:5, 70:20:10, or 80:30:15. By using the above-mentioned compound system, the trifunctional epoxy resin (such as AG-80) provides a high crosslinking density and heat-resistant skeleton, the bisphenol A epoxy resin contributes good mechanical properties and processability as a base resin, and the alicyclic epoxy resin can further reduce the viscosity of the system and improve the reactivity and weather resistance. The three work together to achieve excellent process adaptability under the premise of high heat resistance.

[0028] In some embodiments, the core-shell toughening particles are acrylate-based core-shell rubber particles, with the core layer comprising cross-linked polybutadiene and / or polybutyl acrylate elastomer, and the shell layer comprising polymethyl methacrylate and / or methacrylate copolymers containing epoxy reactive functional groups. By employing the above structure, the elastic core layer can effectively absorb impact energy, while the rigid shell layer not only has good physical compatibility or chemical bonding ability with the epoxy matrix, preventing particle aggregation and filtering, but also ensures that stress is effectively transferred from the matrix to the particles, thereby achieving efficient toughening without affecting transparency.

[0029] In some embodiments, the stabilizer includes at least one of barbituric acid, citric acid, trimethyl borate, and triethyl borate; by using the above stabilizer, the acidity and alkalinity of the system can be mildly adjusted, and active sites that may trigger resin prepolymerization or particle surface gelation can be passivated, ensuring that the viscosity of component A is stable during storage and preheating, and that the core-shell particle dispersion is durable.

[0030] In some embodiments, the trifunctional epoxy resin includes amino trifunctional epoxy resin and / or AG-80 epoxy resin. By using the above-mentioned trifunctional epoxy resin, the multiple epoxy active sites contained in its molecular structure can form a dense three-dimensional cross-linked network during the curing process, which significantly improves the glass transition temperature and high-temperature mechanical stability of the resin, providing a core guarantee for achieving temperature resistance performance above 190°C. At the same time, this type of epoxy resin has good compatibility with other components and will not affect the process performance of the system.

[0031] In some embodiments, the average particle size of the core-shell toughening particles is 200–500 nm. By controlling the particle size within this range, the particle size is much smaller than the pores between conventional fiber reinforcements, allowing them to pass smoothly through the fiber bed during RTM injection without being filtered or trapped. At the same time, this size also facilitates uniform dispersion in the matrix and achieves the best toughening effect.

[0032] In some embodiments, aromatic amines include 4,4-diamino-3,3-diethyldiphenylmethane and / or diaminodiphenylmethane; alicyclic amines include isophorone diamine and / or 1,3-cyclohexanedimethylamine; polyether amines include polyether amine D-230 and / or polyether amine T-403; by selecting these specific types of amine curing agents, the overall properties of the cured product can be optimized. Liquid aromatic amines such as 4,4-diamino-3,3-diethyldiphenylmethane provide high heat distortion temperatures while maintaining low viscosity; alicyclic amines such as isophorone diamine impart good toughness, chemical resistance, and weather resistance; polyether amines D-230 / T-403 act as flexibility modifiers, extending the pot life and improving impact resistance.

[0033] A method for preparing a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process includes the following steps: S1. Stir the epoxy resin mixture until it is homogeneous, then add the core-shell toughening particles and stabilizer, and continue to shear, stir and degas to obtain a homogeneous component A. S2. Mix the aromatic amine, alicyclic amine and polyether amine evenly to obtain component B; S3. Mix components A and B in proportion at 40-60°C and inject into the mold. Maintain the mold temperature at 40-60°C and keep the resin mixture viscosity below 0.3 Pa·s for more than 360 min. Then raise the temperature to 180°C±5°C and keep it at that temperature for 2.5-3 h to cure.

[0034] By adopting the above technical solution, this preparation method uses a stepwise preparation of components A and B, which ensures uniform mixing of each component and avoids performance defects caused by uneven concentration of local components. In step S1, shearing and stirring are used to achieve uniform dispersion and degassing of core-shell particles, ensuring the uniformity of component A. Step S2 ensures that the components of the composite curing agent are fully integrated and exert a synergistic effect. In step S3, the mixing and injection temperature of 60°C ensures that the viscosity of the system is at a low level, ensuring sufficient wetting of the fiber preform. The low viscosity time of more than 360 minutes provides a sufficient operating window for the RTM process. The subsequent curing process of holding at 180°C for 2.5 hours ensures complete curing reaction, forming a dense and stable cross-linked network, giving full play to the synergistic performance of each component, and finally obtaining a high-toughness, high-temperature resistant composite material component.

[0035] In some embodiments, in step S1, the temperature for uniform mixing is 60–80°C under vacuum; the shear stirring speed is 1000–3000 rpm, and the time is 30–60 min. By adopting the above process parameters, the vacuum environment can effectively remove bubbles generated during the mixing process, avoiding the influence of bubbles remaining in the final composite material on mechanical properties; the temperature of 60–80°C can reduce the viscosity of the epoxy resin mixture, improve mixing efficiency, and at the same time avoid premature reaction of components due to excessively high temperature; the high shear speed of 1000–3000 rpm can effectively break the agglomeration tendency of core-shell particles, ensuring that they are uniformly dispersed in the epoxy resin mixture; the stirring time of 30–60 min ensures that the components are fully integrated to form a uniform and stable component A, providing a basis for the performance stability after subsequent mixing with component B.

[0036] The raw materials used in this invention are as follows: Epoxy resins: AG-80 epoxy resin, E-51 epoxy resin, TDE-85 epoxy resin.

[0037] Core-shell toughened particles (CSR): The core layer is cross-linked polybutyl acrylate (PBA), and the shell layer is polymethyl methacrylate-glycidyl methacrylate copolymer (PMMA-co-GMA), with an average particle size of approximately 350 nm.

[0038] Stabilizer: Trimethyl borate (TMB).

[0039] Complex amine curing agents: 4,4'-diamino-3,3'-diethyldiphenylmethane (LAROMIN C 260), isophorone diamine (IPDA), polyetheramine D-230.

[0040] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0041] Example

[0042] To clearly demonstrate the role of each component, the following examples are divided into three series, which examine the effects of core-shell particle content, stabilizer content, and compound amine ratio, respectively. All series are based on a common basic formulation.

[0043] Basic formula (fixed portion of component A): Epoxy resin mixture: 100 parts by weight (of which AG-80: 70 parts, E-51: 20 parts, TDE-85: 10 parts).

[0044] Component B: The total mass of the composite amine curing agent is added at a ratio of 100:35 to component A, where the specific proportions of each amine are detailed in each series.

[0045] Series 1: The Influence of Toughening Particle Content on Core-Shell Structure

[0046] In this series, the stabilizer (trimethyl borate) in component A is fixed at 1 part, and the curing agent ratio in component B is LAROMIN C260:IPDA:D-230=60:25:15, only the amount of core-shell particles (CSR) added is changed.

[0047] Example 1-1: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 5 parts of CSR, and 1 part of trimethyl borate.

[0048] The mass ratio of component A to component B is 100:35, where component B includes LAROMIN C260, IPDA and D-230 in a mass ratio of 60:25:15.

[0049] Preparation and Curing: Component A was sheared and mixed at 2500 rpm for 45 minutes under vacuum (-0.09 MPa) at 70°C for degassing. Component B was stirred and mixed uniformly at 60°C. Components A and B were mixed in proportion at 60°C and injected into a mold at 60°C. The resin viscosity at 60°C was 0.16 Pa·s. Curing procedure: 180°C / 2.5h.

[0050] Performance test results: Impact strength 26.8 kJ / m 2 ; Tg 200℃; applicable period 410 min.

[0051] Examples 1-2: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 10 parts of CSR, and 1 part of trimethyl borate.

[0052] Component B and its process are the same as in Example 1-1.

[0053] Performance test results: Impact strength 31.5 kJ / m 2 ; Tg 198℃; applicable period 420 min.

[0054] Examples 1-3 illustrate a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM processes, prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 15 parts of CSR, and 1 part of trimethyl borate.

[0055] Component B and its process are the same as in Example 1-1.

[0056] Performance test results: Impact strength 29.5 kJ / m 2 Tg 194℃; pot life 400 min; initial viscosity rises to 0.23 Pa·s at 60℃.

[0057] Comparative Example 1-1: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, without CSR, and 1 part of trimethyl borate.

[0058] Component B and its process are the same as in Example 1-1.

[0059] Performance test results: Impact strength 16.0 kJ / m 2 Tg 205℃; applicable period 425 min.

[0060] Comparative Examples 1-2: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 20 parts of CSR, and 1 part of trimethyl borate.

[0061] Component B and its process are the same as in Example 1-1.

[0062] Performance test results: Impact strength 30.0 kJ / m 2 Tg 188℃; pot life 380 min; initial viscosity at 60℃ increases significantly to 0.32 Pa·s.

[0063] Series 2: Effect of Stabilizer Content

[0064] This series has a fixed A component of 100 parts of basic epoxy resin mixture and 10 parts of CSR. The B component has the same curing agent ratio and process as the same series, only the amount of stabilizer TMB added is changed.

[0065] Example 2-1: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 10 parts of CSR, and 0.1 parts of TMB.

[0066] Performance test results: Impact strength 31.3 kJ / m 2 ; Tg 198℃; applicable period 280 min.

[0067] Example 2-2: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process is prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 10 parts of CSR, and 1 part of TMB (same as Examples 1-2).

[0068] Performance test results: Impact strength 31.5 kJ / m 2 Tg 198℃; applicable period 420 min.

[0069] Examples 2-3 illustrate a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM processes, prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 10 parts of CSR, and 5 parts of TMB.

[0070] Performance test results: Impact strength 30.8 kJ / m 2 Tg 197℃; applicable period 460 min.

[0071] Comparative Example 2-1, a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, was prepared by the following method: Component A: 100 parts of base epoxy resin mixture, 10 parts of CSR, no TMB added.

[0072] Performance test results: Impact strength 31.0 kJ / m 2 ; Tg 199℃; applicable period 180 min.

[0073] Series 3: The Influence of Compound Amine Curing Agent Proportion

[0074] This series uses a fixed A component consisting of 100 parts of a base epoxy mixture, 10 parts of CSR, and 1 part of TMB. Only the ratio of the three amines in component B is changed, and the total curing agent equivalent is kept essentially consistent by fine-tuning the A:B ratio.

[0075] Example 3-1: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process is prepared by the following method: The mass ratio of component A to component B is 100:35, where component B includes LAROMIN C260, IPDA and D-230 in a mass ratio of 50:20:10.

[0076] Performance test results: Impact strength 30.5 kJ / m 2 ; Tg 196℃; applicable period 415 min.

[0077] Example 3-2: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process was prepared by the following method: The mass ratio of component A to component B is 100:35, where component B includes LAROMIN C260, IPDA and D-230 in a mass ratio of 60:25:15.

[0078] Performance test results: Impact strength 31.5 kJ / m 2 ; Tg 198℃; applicable period 420 min.

[0079] Example 3-3: A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process is prepared by the following method: The mass ratio of component A to component B is 100:35, where component B includes LAROMIN C260, IPDA and D-230 in a mass ratio of 70:40:20.

[0080] Performance test results: Impact strength 29.0 kJ / m 2 Tg 201℃; applicable period 395 min.

[0081] Comparative Example 3-1 (without aromatic amines): A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM processes was prepared by the following method: The mass ratio of component A to component B is 100:35, where component B includes IPDA and D-230 in a mass ratio of 50:20.

[0082] Performance test results: Impact strength 28.0 kJ / m 2; Tg 175℃; applicable period 500 min.

[0083] Performance testing

[0084] Impact strength was tested according to GB / T 1843-2008 (unnotched); glass transition temperature (Tg) was tested according to GB / T 2571-1995, and the peak tanδ was measured by dynamic mechanical analysis at a frequency of 1 Hz and a heating rate of 3 ℃ / min; viscosity was tested using a rotational rheometer at a constant temperature of 60 ℃, and the pot life was defined as the time it takes for the viscosity to reach 0.3 Pa·s. The results of the performance tests are listed in Table 1: Table 1 Performance test results

[0085] Conclusion of Series 1: Data shows that a core-shell particle content of 5–15 parts significantly improves resin toughness and increases impact strength by 67%–97%, while maintaining a controllable effect on the glass transition temperature (Tg) above 194℃ and a good working life. In Comparative Example 1-1, the content was too low, resulting in insufficient toughening; in Comparative Example 1-2, the content was too high, leading to a significant decrease in heat resistance, a surge in viscosity, and impaired processability. This series demonstrates the necessity and rationality of the core-shell particle content range specified in claim 1.

[0086] Series Two Conclusion: Data shows that adding 0.1–5 parts of stabilizer can effectively adjust the pot life of the resin system at 60°C, with minimal impact on the mechanical properties and heat resistance of the final cured product. In Comparative Example 2-1, without stabilizer, the pot life is shorter, making it difficult to meet the long process window requirements of RTM molding for large components. This series demonstrates the role of stabilizers in achieving the long pot life process characteristics of this invention.

[0087] Series 3 Conclusion: Data shows that within the composite amine ratio range of (50-70):(20-40):(10-20) of this invention, the resin system can simultaneously maintain good toughness, high heat resistance, and long pot life. Using the ratio of Comparative Example 3-1, which does not contain rigid aromatic amines, results in a severely insufficient glass transition temperature, failing to meet the high-temperature resistance requirements. This series demonstrates that a specific ratio of composite amine curing agent is key to achieving the three major characteristics of this invention: high toughness, high temperature resistance, and suitability for RTM processes.

[0088] The above examples and comparative examples fully illustrate that the present invention, through the synergistic effect of a specific epoxy resin mixture, 5-15 parts of core-shell toughening particles, 0.1-5 parts of stabilizer, and a composite amine curing agent composed of a specific ratio of modified liquid aromatic amine, alicyclic amine, and polyether amine, successfully provides an epoxy resin composition that simultaneously possesses high toughness, high heat resistance, and excellent RTM process adaptability, thus solving the technical problem that traditional high-performance epoxy resins cannot simultaneously achieve both toughness and processability in the RTM process.

[0089] Therefore, compared to existing epoxy resin compositions, the core-shell particles described in this application exhibit excellent miscibility with the epoxy resin matrix due to their unique structure. These particles effectively toughen and reinforce the epoxy resin while having minimal impact on the viscosity of the epoxy resin system. Consequently, the resulting epoxy resin composition possesses not only superior mechanical properties but also lower system viscosity. Furthermore, the RTM epoxy resin composition described in this application, due to the addition of stabilizers, exhibits a significantly extended pot life, thus meeting the process requirements of RTM molding.

[0090] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, characterized in that, Includes component A and component B with a mass ratio of 100:(25-50); Component A comprises the following substances in parts by weight: 100 parts epoxy resin mixture, 5-15 parts core-shell toughening particles, and 0.1-5 parts stabilizer; Component B is a complex amine curing agent, including aromatic amines, alicyclic amines, and polyether amines.

2. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The mass ratio of the aromatic amine, the alicyclic amine and the polyether amine is (50-70):(20-40):(10-20).

3. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The epoxy resin mixture includes trifunctional epoxy resin, bisphenol A type epoxy resin and alicyclic epoxy resin in a mass ratio of (60-80):(10-30):(5-15).

4. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The core-shell toughening particles are acrylate-based core-shell rubber particles, with the core layer comprising cross-linked polybutadiene and / or polybutyl acrylate elastomer, and the shell layer comprising polymethyl methacrylate and / or methacrylate copolymers containing epoxy reactive functional groups.

5. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The stabilizer includes at least one of barbituric acid, citric acid, trimethyl borate, and triethyl borate.

6. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 3, characterized in that, The trifunctional epoxy resin includes amino trifunctional epoxy resin and / or AG-80 epoxy resin.

7. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The core-shell toughening particles have an average particle size of 200–500 nm.

8. The high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 1, characterized in that, The aromatic amines include 4,4-diamino-3,3-diethyldiphenylmethane and / or diaminodiphenylmethane; the alicyclic amines include isophorone diamine and / or 1,3-cyclohexanedimethylamine; and the polyether amines include polyether amine D-230 and / or polyether amine T-403.

9. A method for preparing a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process, characterized in that, Includes the following steps: S1. Stir the epoxy resin mixture until it is homogeneous, then add the core-shell toughening particles and stabilizer, and continue to shear, stir and degas to obtain a homogeneous component A. S2. Mix the aromatic amine, alicyclic amine and polyether amine evenly to obtain component B; S3. Mix components A and B in proportion at 40-60°C and inject into the mold. Maintain the mold temperature at 40-60°C and keep the resin mixture viscosity below 0.3 Pa·s for more than 360 min. Then raise the temperature to 180°C±5°C and keep it at that temperature for 2.5-3 h to cure.

10. A method for preparing a high-toughness, high-temperature resistant epoxy resin composition suitable for RTM process according to claim 9, characterized in that, In step S1, the temperature at which the stirring and mixing are uniform is 60-80°C under vacuum; the rotation speed of the shearing and stirring is 1000-3000 rpm, and the time is 30-60 min.

Images