Epoxy resin composition, preparation method thereof and composite material

Abstract

The invention provides an epoxy resin composition, a preparation method thereof and a composite material. The epoxy resin composition comprises the following components in parts by mass: 58-75 parts of bisphenol A type epoxy resin, 8-18 parts of tetrafunctional epoxy resin, 4-15 parts of a polyether ketone toughening agent, 2-10 parts of core-shell particles, 3-8 parts of a latent curing agent, 0.5-2 parts of an accelerant and 1-5 parts of porous nanoparticles. According to the epoxy resin composition provided by the invention, under the specific components and mass parts, the toughness of the epoxy resin composition can be improved, the curing temperature of the epoxy resin composition is accurately controlled, and the process window is widened.

Description

Technical Field

[0001] The present disclosure relates to the technical field of composite materials, and in particular to an epoxy resin composition, a preparation method thereof, and a composite material. Background Art

[0002] Current epoxy resin systems for aviation prepregs generally face the following technical bottlenecks: 1. A narrow curing process window. Conventional dicyandiamide curing systems typically have a process window of less than 30°C (160-190°C), resulting in high temperature sensitivity. This can easily lead to under-curing or over-crosslinking during production, posing a particular challenge to the molding stability of large, complex components. 2. A conflict between toughening and processability. While conventional toughening methods (such as rubber particles and thermoplastics) can improve post-impact compression strength, they significantly increase resin viscosity (by 50-300%), shortening the working life. Furthermore, high toughening agent content can easily induce phase separation, compromising interlaminar shear strength. 3. Difficulty in synergistically optimizing multiple properties: Existing technologies struggle to simultaneously meet requirements for post-impact compression strength ≥300 MPa, interlaminar shear strength ≥100 MPa, and glass transition temperature ≥180°C. For example, the interlaminar shear strength of rubber-toughened systems is generally below 90 MPa, and the curing window of thermoplastic-toughened systems is narrowed to less than 20°C. Furthermore, nano-reinforcement technology can easily shorten the shelf life of prepregs (<30 days). The industry's mainstream products (such as Cycom 977-2 and HexPly M21) still rely on compromise designs, sacrificing some processability in exchange for improved mechanical properties, which restricts the large-scale application of composite materials in the main load-bearing structures of civil aircraft. Summary of the Invention

[0003] To solve the problems existing in the related art, the present disclosure provides an epoxy resin composition, a preparation method thereof, and a composite material.

[0004] According to a first aspect of an embodiment of the present disclosure, there is provided an epoxy resin composition comprising the following components in parts by mass:

[0005] 58-75 parts of bisphenol A epoxy resin,

[0006] 8-18 parts of tetrafunctional epoxy resin,

[0007] 4-15 parts of polyetherketone toughening agent,

[0008]

[0009] In some embodiments of the present disclosure, the mass ratio of the polyetherketone toughening agent, the core-shell particles and the porous nanoparticles is (5-12): (3-8): (1-3).

[0010] In some embodiments of the present disclosure, the mass ratio of the latent curing agent to the accelerator is (4-6): (0.5-1.5).

[0011] In some embodiments of the present disclosure, the mass ratio of the bisphenol A epoxy resin to the tetrafunctional epoxy resin is (4-7):1.

[0012] In some embodiments of the present disclosure, the specific surface area of the porous nanoparticles is 200±25m 2 / g, and the hydroxyl content in the porous nanoparticles is ≥3.0mmol / g.

[0013] In some embodiments of the present disclosure, active groups are grafted onto the surface of the core-shell particles, and the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of the active groups on the surface of the core-shell particles is ≥85%.

[0014] According to a second aspect of the embodiments of the present disclosure, a method for preparing an epoxy resin composition is provided. The method is used to prepare the above-mentioned epoxy resin composition, and the method comprises:

[0015] Stirring and mixing a bisphenol A epoxy resin and a tetrafunctional epoxy resin under first preset conditions to obtain a resin mixture;

[0016] dissolving a polyetherketone toughening agent in the resin mixture to obtain a toughened resin mixture;

[0017] The core-shell particles, porous nanoparticles, latent curing agent and accelerator are dispersed in the toughening resin mixture to obtain the epoxy resin composition.

[0018] In some embodiments of the present disclosure, dissolving the polyetherketone toughening agent in the resin mixture to obtain the toughened resin mixture comprises:

[0019] Adding the polyetherketone toughening agent to the resin mixture and pre-dispersing it at 80-100° C. for 1-2 hours to obtain a pre-dispersed mixture;

[0020] The pre-dispersed mixture is dissolved at 150-160° C. for 0.5-1 hour to obtain the toughening resin mixture.

[0021] In some embodiments of the present disclosure, before dispersing the core-shell particles in the toughening resin mixture, the preparation method further comprises:

[0022] The core-shell particles are surface-treated with γ-glycidyloxypropyltrimethoxysilane so that active groups are grafted onto the surface of the core-shell particles, wherein the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of the active groups on the surface of the core-shell particles is ≥85%.

[0023] According to a third aspect of the embodiments of the present disclosure, a composite material is provided, comprising the epoxy resin composition as described above, or an epoxy resin composition prepared by the method for preparing the epoxy resin composition as described above.

[0024] The beneficial effects of the present disclosure include but are not limited to: the epoxy resin composition provided by the present disclosure, in which the combination of bisphenol A epoxy resin and tetrafunctional epoxy resin as the base resin can balance toughness and heat resistance. The polyether ketone toughening agent forms an "island structure" with the resin matrix, the "soft core-hard shell" structure of the core-shell particles, and the interface enhancement performance of the porous nanoparticles, which can realize a triple composite toughening mechanism and improve the toughness of the epoxy resin composition. The composite curing system of the latent curing agent / accelerator and the porous structure of the porous nanoparticles inhibit convective heat transfer, which can accurately control the curing temperature of the epoxy resin composition and widen the process window. Therefore, the epoxy resin composition provided by this embodiment can improve the toughness of the epoxy resin composition under specific components and mass fractions, and accurately control the curing temperature of the epoxy resin composition and widen the process window.

[0025] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, are used to explain the principles of the embodiments of the present disclosure. In these drawings, similar reference numerals are used to represent similar elements. The drawings described below are some embodiments of the present disclosure, not all embodiments. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0027] Figure 1 The present invention is a flow chart of a method for preparing an epoxy resin composition according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be clearly and completely described below in conjunction with the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure. It should be noted that, in the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other.

[0029] Currently, epoxy resin systems used in aviation prepregs generally face the following technical bottlenecks: 1. Narrow curing process window; 2. Conflict between toughening and processability; 3. Difficulty in synergistic optimization of multiple properties: it is difficult to simultaneously meet indicators such as post-impact compressive strength ≥300MPa, interlaminar shear strength ≥100MPa, and glass transition temperature ≥180℃.

[0030] In order to solve the above technical problems, the present disclosure provides an epoxy resin composition, in which the combination of bisphenol A epoxy resin and tetrafunctional epoxy resin is used as a matrix resin to balance toughness and heat resistance. The polyether ketone toughening agent forms an "island structure" with the resin matrix, the "soft core-hard shell" structure of the core-shell particles, and the nanopores of the porous nanoparticles hinder cracks and interface enhancement performance, which can achieve a triple composite toughening mechanism, improve the toughness of the epoxy resin composition, and balance the viscosity of the epoxy resin composition. The composite curing system of the latent curing agent / accelerator and the porous structure of the porous nanoparticles suppress convection heat transfer, can accurately control the curing temperature of the epoxy resin composition, and widen the process window. Therefore, the epoxy resin composition provided by the present embodiment can improve the toughness of the epoxy resin composition under specific components and mass fractions, and accurately control the curing temperature of the epoxy resin composition, and widen the process window.

[0031] An exemplary embodiment of the present disclosure provides an epoxy resin composition, which includes the following components in parts by mass: 58 to 75 parts of bisphenol A epoxy resin, 8 to 18 parts of tetrafunctional epoxy resin, 4 to 15 parts of polyether ketone toughening agent, 2 to 10 parts of core-shell particles, 3 to 8 parts of latent curing agent, 0.5 to 2 parts of accelerator, and 1 to 5 parts of porous nanoparticles.

[0032] Among them, the core-shell particles can be core-shell rubber particles. The structure of the core-shell rubber particles uses polysiloxane as the core layer and acrylate polymer as the shell layer, forming a "soft core-hard shell" structure. When the composite material is subjected to stress, the "hard shell" of the core-shell particle or the surrounding resin matrix locally yields under stress, forming a microfibrillated structure (silver streaks), and the "soft core" prevents the silver streaks from expanding through plastic deformation. In addition, the "hard shell" can limit the excessive deformation of the "soft core" through its high modulus, and induce shear yielding of the resin matrix through interfacial stress transfer, synergistically consuming energy. Therefore, the "soft core-hard shell" structure of the core-shell rubber particles can effectively toughen the epoxy resin composition.

[0033] The latent curing agent can be a dicyandiamide curing agent, and the accelerator can be a urea accelerator. That is, the curing system in the epoxy resin composition can adopt a dicyandiamide curing agent / urea accelerator composite curing system. The dicyandiamide curing agent itself has high latency, and when used together with the urea accelerator, it can form a synergistic curing. That is, at low temperatures, the dicyandiamide curing agent and the urea accelerator are unreactive. When the temperature is increased, the decomposition temperature of the dicyandiamide curing agent matches the activation temperature of the urea accelerator, which can achieve the curing of the epoxy resin composition. By adjusting the mass ratio between the dicyandiamide curing agent and the urea accelerator, the curing temperature of the epoxy resin composition can be accurately controlled, and the process window can also be widened.

[0034] In an exemplary embodiment, the specific surface area of the porous nanoparticles is 200±25 m 2 / g, the hydroxyl content in the porous nanoparticles is ≥3.0mmol / g, and the porous nanoparticles can be nano-silicon dioxide.

[0035] High specific surface area (200±25m 2 Nanosilica with a hydroxyl content of 3.0 mmol / g or higher can provide more interfacial interaction sites. A hydroxyl content of 3.0 mmol / g or higher can enhance the chemical bonding between the nanosilica and the epoxy groups in the epoxy resin, significantly improving the composite's interfacial strength and delamination resistance. Furthermore, the porous structure of nanosilica can absorb impact energy when subjected to stress, enhancing stress transfer. Furthermore, the porous structure of nanosilica can inhibit convective heat transfer, thereby increasing the glass transition temperature of the epoxy resin composition and broadening the process window.

[0036] The polyetherketone toughening agent can form an "island structure" with the resin matrix (i.e., bisphenol A epoxy resin and tetrafunctional epoxy resin). When subjected to stress, the polyetherketone toughening agent acts as an "island" to absorb the destructive force, thereby providing toughness to the composite material. For example, the glass transition temperature (Tg) of the polyetherketone toughening agent can be 140-145°C.

[0037] Bisphenol A epoxy resin has excellent toughness and workability, while tetrafunctional epoxy resin has good heat resistance and mechanical properties. Using a combination of bisphenol A epoxy resin and tetrafunctional epoxy resin as the resin matrix can balance the toughness and heat resistance of the epoxy resin composition. For example, the epoxy value of the bisphenol A epoxy resin can be 0.48 to 0.54 mol / 100g, while the epoxy value of the tetrafunctional epoxy resin can be 0.80 to 0.90 mol / 100g.

[0038] The polyetherketone toughening agent, core-shell particles, and porous nanoparticles exhibit a synergistic toughening effect. When the composite material is subjected to stress, the "island structure" formed by the polyetherketone toughening agent in the resin matrix can delay crack propagation through plastic deformation and fiber pullout effects. The core-shell particles locally yield under stress through the "hard shell" or the surrounding resin matrix, forming a microfibrillated structure (silver crazing). The "soft core" prevents the expansion of silver crazing through plastic deformation. The "hard shell" can also limit excessive deformation of the "soft core" through its high modulus and induce shear yield in the resin matrix through interfacial stress transfer, synergistically consuming energy and forming multiple energy dissipation paths. The nanopores of the porous nanoparticles hinder the advancement of the crack tip and strengthen the interface through hydroxyl bonding, thus achieving a triple composite toughening mechanism. In addition, the epoxy groups on the surface of the core-shell particles can provide valence bonds with the resin matrix, and the ketone groups of the polyetherketone toughener form dynamic hydrogen bonds with the epoxy groups of the resin matrix, enhancing interfacial bonding. The porous nanoparticles can strengthen the interface through hydroxyl bonding and can also enhance physical anchoring through pores, thereby jointly constructing a multi-level interface and achieving efficient stress transfer. Moreover, the synergistic use of the polyetherketone toughener, core-shell particles, and porous nanoparticles can balance the viscosity of the epoxy resin composition. For example, the addition of the polyetherketone toughener increases the viscosity of the resin matrix, while the porous nanoparticles have a lubricating effect. Their dispersion in the resin matrix can reduce the flow resistance of the resin matrix, offsetting the increased viscosity of the polyetherketone toughener. The steric hindrance of the core-shell particles can hinder the entanglement of the polyetherketone toughener molecular chains, further suppressing the increase in the viscosity of the resin matrix.

[0039] In the epoxy resin composition provided by the present embodiment, the combination of bisphenol A epoxy resin and tetrafunctional epoxy resin as the matrix resin can balance toughness and heat resistance. The polyether ketone toughening agent forms an "island structure" with the resin matrix, the "soft core-hard shell" structure of the core-shell particles, and the nanopores of the porous nanoparticles hinder cracks and interface enhancement performance, which can achieve a triple composite toughening mechanism, improve the toughness of the epoxy resin composition, and balance the viscosity of the epoxy resin composition. The composite curing system of the latent curing agent / accelerator and the porous structure of the porous nanoparticles suppress convective heat transfer, which can accurately control the curing temperature of the epoxy resin composition and widen the process window. Therefore, the epoxy resin composition provided by the present embodiment can improve the toughness of the epoxy resin composition under specific component mass fractions, and accurately control the curing temperature of the epoxy resin composition and widen the process window.

[0040] In an exemplary embodiment, the mass ratio of the polyetherketone toughening agent, the core-shell particles and the porous nanoparticles is (5-12): (3-8): (1-3).

[0041] Polyetherketone toughening agents can form "island structures" with the resin matrix. When subjected to stress, the polyetherketone toughening agents act as "islands" to absorb and digest destructive forces, thereby providing a toughening effect for the composite material. When the composite material is subjected to stress, the "hard shell" of the core-shell particles or the surrounding resin matrix locally yields under stress, forming a microfibrillated structure (silver streaks), and the "soft core" prevents the expansion of silver streaks through plastic deformation. In addition, the "hard shell" can limit the excessive deformation of the "soft core" through its high modulus, and induce shear yielding of the resin matrix through interfacial stress transfer, synergistically consuming energy. Porous nanoparticles can provide more interfacial interaction sites, enhance the chemical bonding between nano-silica and epoxy groups in epoxy resin, significantly improve the interface strength and anti-delamination ability of the composite material, and its porous structure can absorb impact energy when subjected to stress, thereby improving stress transfer. This triple composite toughening mechanism can effectively improve the toughness of epoxy resin compositions. The mass ratio of the polyetherketone toughening agent, core-shell particles and porous nanoparticles is within the range of (5-12): (3-8): (1-3), which can ensure the synergistic effect of the three. The polyetherketone toughening agent provides macroscopic toughening, the core-shell particles disperse stress through the "silver streak-shear band" mechanism, and the porous nanoparticles enhance interfacial bonding through the nano effect, thereby effectively improving the toughness of the epoxy resin composition. For example, the mass ratio of the polyetherketone toughening agent, core-shell particles and porous nanoparticles can be 5:4:2, 8:5:1 or 10:6:3. The mass ratio of the polyetherketone toughening agent, core-shell particles and porous nanoparticles can also be any value between the exemplary ratios, for example, the mass ratio of the polyetherketone toughening agent, core-shell particles and porous nanoparticles can also be any value between (6-10): (5-8): (1.5-2.5).

[0042] In an exemplary embodiment, the mass ratio of the latent curing agent to the accelerator is (4-6): (0.5-1.5).

[0043] The curing system in the epoxy resin composition utilizes a latent curing agent / accelerator composite curing system, such as a dicyandiamide curing agent / urea accelerator composite curing system. The dicyandiamide curing agent itself has high latency, and when used in conjunction with a urea accelerator, it can form a synergistic cure. That is, at low temperatures, the dicyandiamide curing agent and the urea accelerator are inactive. However, when the temperature rises, the decomposition temperature of the dicyandiamide curing agent matches the activation temperature of the urea accelerator, enabling the epoxy resin composition to cure. By adjusting the mass ratio of the dicyandiamide curing agent to the urea accelerator within the range of (4-6):(0.5-1.5), the curing temperature of the epoxy resin composition can be precisely controlled, broadening the process window. For example, the mass ratio of the latent curing agent and the accelerator can be 4:1, 6:0.9 or 5:1.5. The mass ratio of the latent curing agent and the accelerator can also be any value between the exemplary ratios. For example, the mass ratio of the latent curing agent and the accelerator can be any value between (5 to 5.8): (0.8 to 1.2).

[0044] In an exemplary embodiment, the mass ratio of the bisphenol A epoxy resin to the tetrafunctional epoxy resin is (4-7):1.

[0045] Bisphenol A epoxy resin has excellent toughness and processability, and tetrafunctional epoxy resin has good heat resistance and mechanical properties. Using a combination of bisphenol A epoxy resin and tetrafunctional epoxy resin as a resin matrix, and controlling the mass ratio of bisphenol A epoxy resin to tetrafunctional epoxy resin within the range of (4 to 7): 1, can ensure the toughness of the epoxy resin composition while improving its heat resistance and rigidity, avoiding the problem of excessive brittleness or insufficient temperature resistance of a single resin. For example, the mass ratio of bisphenol A epoxy resin to tetrafunctional epoxy resin can be 4:1, 6:1 or 7:1, and the mass ratio of bisphenol A epoxy resin to tetrafunctional epoxy resin can also be any value between the exemplary ratios, for example, the mass ratio of bisphenol A epoxy resin to tetrafunctional epoxy resin can be any value between (4.5 to 6): 1.

[0046] In an exemplary embodiment, active groups are grafted onto the surface of the core-shell particles, and the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of the active groups on the surface of the core-shell particles is ≥85%.

[0047] Epoxy groups grafted onto the surface of core-shell particles can react with the resin matrix, reducing interfacial defects and enhancing the mechanical properties of the composite material (e.g., toughness and interlaminar shear strength). Siloxane groups grafted onto the surface of core-shell particles can improve the dispersion stability of the core-shell particles in the resin matrix through physical or chemical effects. Therefore, grafting epoxy and / or siloxane groups onto the surface of core-shell particles and controlling the grafting rate to ≥85% can form chemical bonds between the core-shell particles and the resin matrix, reducing interfacial defects. It can also improve interfacial compatibility and dispersibility, facilitating the uniform dispersion of the core-shell particles in the resin matrix.

[0048] An exemplary embodiment of the present disclosure provides a method for preparing an epoxy resin composition, wherein the method is used to prepare the above-mentioned epoxy resin composition, such as Figure 1 As shown, the preparation method comprises:

[0049] S100, stirring and mixing bisphenol A epoxy resin and tetrafunctional epoxy resin under first preset conditions to obtain a resin mixture.

[0050] A bisphenol A epoxy resin and a tetrafunctional epoxy resin are mixed under vacuum stirring at a ratio of 4 to 7 parts by mass of the bisphenol A epoxy resin to the tetrafunctional epoxy resin:1 at 60 to 80° C., with a vacuum degree of ≤-0.095 MPa, to obtain a resin mixture, i.e., a resin matrix. The stirring and mixing temperature can be, for example, 60° C., 70° C., or 80° C., or any value between the exemplary temperatures, for example, any value between 65 and 70° C.

[0051] S200, dissolving a polyetherketone toughening agent in the resin mixture to obtain a toughened resin mixture.

[0052] S300, dispersing the core-shell particles, porous nanoparticles, latent curing agent and accelerator in a toughening resin mixture to obtain an epoxy resin composition.

[0053] The core-shell particles may be core-shell rubber particles, the latent curing agent may be a dicyandiamide curing agent, the accelerator may be a urea accelerator, and the porous nanoparticles may be nano-silica.

[0054] The core-shell particles can be grinded by a three-roll mill (roller temperature 80±5℃, shear rate ≥10 4 s -1The porous nanoparticles can be dispersed into the toughening resin mixture using an ultrasonic oscillation machine (40 kHz frequency, 800-1000 W power, 30-45 min) prior to addition to the toughening resin mixture. This pre-disperses the porous nanoparticles and prevents agglomeration, which can hinder dispersion in the toughening resin mixture. The ultrasonic oscillation can be performed in a pulsed mode (e.g., with a duty cycle of 5s on / 2s off) to avoid heat generation from continuous ultrasonic oscillation, which could increase the temperature of the porous nanoparticles. The latent curing agent and accelerator can be dispersed into the toughening resin mixture by mixing at a low speed at a temperature of 40-50°C. Planetary agitation (vacuum -0.098 MPa, speed 1200 rpm) can be used to disperse the core-shell particles, porous nanoparticles, latent curing agent, and accelerator.

[0055] It should be noted that during the preparation of the epoxy resin composition, if the viscosity of the dispersion is greater than 6000 mPa·s, acetone solvent may be added to adjust the viscosity of the dispersion to prevent excessive viscosity, which could prevent the added components from dispersing. The amount of acetone solvent added should not exceed 15% of the total mass of the dispersion. In subsequent applications of the epoxy resin composition, the acetone solvent must be removed by vacuum (removal rate ≥ 99.5%) before curing.

[0056] The preparation method of the epoxy resin composition provided by the exemplary embodiment of the present disclosure first mixes bisphenol A epoxy resin and tetrafunctional epoxy resin to form a resin matrix to ensure the compatibility between the resins, and then introduces core-shell particles, porous nanoparticles, latent curing agent and accelerator in stages to avoid the problem of uneven dispersion caused by direct mixing of multi-phase systems. The epoxy resin composition finally prepared is uniform and stable.

[0057] In an exemplary embodiment, step S200 dissolving a polyetherketone toughening agent in a resin mixture to obtain a toughened resin mixture includes:

[0058] S210, adding the polyetherketone toughening agent to the resin mixture and pre-dispersing it at 80-100° C. for 1-2 hours to obtain a pre-dispersed mixture.

[0059] S220, dissolving the pre-dispersed mixture at 150-160° C. for 0.5-1 h to obtain a toughened resin mixture.

[0060] In this example, after the polyetherketone toughening agent is added to the resin mixture, it is pre-dispersed at a low temperature (80-100°C) to prevent the temperature from increasing too quickly, which would increase the viscosity of the dispersion system and make it more difficult to disperse the polyetherketone toughening agent in the dispersion system. After dispersing at low temperature for 0.5-1 hour, the temperature is then raised to a high temperature (150-160°C) to completely dissolve the polyetherketone toughening agent and achieve uniform distribution in the resin mixture.

[0061] Wherein, the temperature of low-temperature pre-dispersion can be 80°C, 90°C or 100°C, and the temperature of low-temperature pre-dispersion can also be any value between the exemplary temperatures, for example, the temperature of low-temperature pre-dispersion can also be any value between 85 and 90°C. The duration of low-temperature pre-dispersion can be 1 hour, 1.5 hours or 2 hours, and the duration of low-temperature pre-dispersion can also be any value between the exemplary durations, for example, the duration of low-temperature pre-dispersion can also be any value between 1.2 and 1.8 hours. The temperature of high-temperature dissolution can be 150°C, 155°C or 160°C, and the temperature of high-temperature dissolution can also be any value between the exemplary temperatures, for example, the temperature of high-temperature dissolution can also be any value between 152 and 158°C. The duration of high-temperature dissolution can be 0.5 hours, 0.8 hours or 1 hour, and the duration of high-temperature dissolution can also be any value between the exemplary durations, for example, the duration of high-temperature dissolution can also be any value between 0.6 and 0.8 hours.

[0062] In an exemplary embodiment, before dispersing the core-shell particles in the toughening resin mixture, the preparation method further includes: surface-treating the core-shell particles with γ-glycidyloxypropyltrimethoxysilane so that active groups are grafted onto the surface of the core-shell particles, and the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of active groups on the surface of the core-shell particles is ≥85%.

[0063] In this embodiment, before dispersing the core-shell particles in the toughening resin mixture, the core-shell particles are first surface-treated with γ-glycidyloxypropyltrimethoxysilane, such as immersion treatment, so that epoxy groups and / or siloxane groups are grafted onto the surface of the core-shell particles, and the grafting rate is controlled to be ≥85%. This allows chemical bonds to be formed between the core-shell particles and the resin matrix, improves interfacial compatibility and dispersibility, and facilitates the uniform dispersion of the core-shell particles in the resin matrix.

[0064] The epoxy resin compositions provided by the exemplary embodiments of the present disclosure, or the epoxy resin compositions prepared by the aforementioned methods for preparing epoxy resin compositions, are suitable for preparing carbon fiber, glass fiber, or aramid fiber prepregs. The epoxy resin composition content in the prepregs is controlled to be 30-40%, with a volatile matter content of ≤0.8%.

[0065] An exemplary embodiment of the present disclosure provides a composite material, the composite material includes an epoxy resin composition as described above, or an epoxy resin composition prepared by the preparation method of the epoxy resin composition as described above. Exemplarily, the composite material can be prepared by a curing method of 180°C / 2h+post-curing 200°C / 1h, and the prepared composite material has a porosity of ≤1.0% and a fiber volume fraction of 60±2%. The composite material provided by this exemplary embodiment has a CAI retention rate of ≥90% in the temperature range of -55 to 120°C, and an ILSS retention rate of ≥85% after wet heat aging (85°C / 85% RH / 1000h).

[0066] In order to more clearly explain the technical solution provided by the exemplary embodiment of the present disclosure, a specific example of preparing the epoxy resin composition provided by the exemplary embodiment of the present disclosure by the method of preparing the epoxy resin composition provided by the exemplary embodiment of the present disclosure is given.

[0067] The bisphenol A epoxy resin and the tetrafunctional epoxy resin were mixed under vacuum stirring at 60-80° C. for 1 h, with a vacuum degree of ≤-0.095 MPa and a rotation speed of 200 rpm to obtain a resin mixture.

[0068] The polyetherketone toughening agent is added to the resin mixture and pre-dispersed at 80-100° C. for 1-2 hours until the viscosity is reduced to 4500 mPa·s to obtain a pre-dispersed mixture.

[0069] The pre-dispersed mixture was heated to 150-160° C. and dissolved for 0.5-1 hour to obtain a toughened resin mixture. DSC confirmed that there was no pre-curing exothermic peak.

[0070] The core-shell particles are surface-treated with γ-glycidyloxypropyltrimethoxysilane, so that epoxy groups and / or siloxane groups are grafted onto the surfaces of the core-shell particles.

[0071] The surface treated core-shell particles were passed through a three-roll mill (roller temperature 80 ± 5 ° C, shear rate ≥ 10 4 s -1 , roller spacing 50-80 μm, speed ratio 1:3:9) is dispersed into the toughening resin mixture.

[0072] After the porous nanoparticles are treated with ultrasonic oscillation (frequency 40kHz, power 800-1000W, time 30-45min), they are added to the toughening resin mixture.

[0073] The latent curing agent (D90=8 μm) and the accelerator are mixed and dispersed into the toughening resin mixture at a temperature of 40-50° C. at a low speed to obtain an epoxy resin composition.

[0074] The components and their mass fractions of the epoxy resin compositions in Examples 1-15 are tabulated below. The epoxy resin compositions in Examples 1-15 were used to prepare composite panels, and the process window ΔT, post-impact compressive strength, and interlaminar shear strength of each composite panel were tested.

[0075] Table 1

[0076]

[0077]

[0078] In addition, the present disclosure also prepared and tested the epoxy resin compositions of Comparative Examples 1-3 with reference to the preparation method of Example 1 above. Among them, the difference between Comparative Example 1 and Example 1 is that only dicyandiamide curing agent is used as the curing system, and its process window ΔT is only 30°C. The difference between Comparative Example 2 and Example 1 is that the core-shell particles are not activated and grafted with active groups, and its post-impact compressive strength is 280MPa and the interlaminar shear strength is 85MPa. The difference between Comparative Example 3 and Example 1 is that core-shell particles and porous nanoparticles are not used, and its post-impact compressive strength is 250MPa and the interlaminar shear strength is 70MPa.

[0079] A comparison of the preparation and testing of the epoxy resin compositions of Examples 1-15 and Comparative Examples 1-3 in Table 1 demonstrates that the "island structure" formed by the polyetherketone toughening agent and the resin matrix, the "soft core-hard shell" structure of the core-shell particles, and the interface-enhancing properties of the porous nanoparticles enable a triple composite toughening mechanism, enhancing the toughness of the composite material. The combined curing system of the dicyandiamide curing agent / urea accelerator and the porous structure of the porous nanoparticles, which inhibits convective heat transfer, broaden the process window. Grafting active groups onto the surface of the core-shell particles improves interfacial compatibility and dispersibility, further enhancing the mechanical properties of the composite material.

[0080] The contents described above can be implemented individually or in combination in various ways, and these variations are all within the scope of protection of the present disclosure.

[0081] Finally, it should be noted that in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0082] The above embodiments are intended only to illustrate the technical solutions of the present disclosure and are not intended to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present disclosure.

Claims

1. An epoxy resin composition, characterized in that The epoxy resin composition comprises the following components in parts by mass:

2. The epoxy resin composition according to claim 1, wherein The mass ratio of the polyetherketone toughening agent, the core-shell particles and the porous nanoparticles is (5-12): (3-8): (1-3).

3. The epoxy resin composition according to claim 1, wherein The mass ratio of the latent curing agent to the accelerator is (4-6): (0.5-1.5).

4. The epoxy resin composition according to claim 1, wherein The mass ratio of the bisphenol A epoxy resin to the tetrafunctional epoxy resin is (4-7):

1.

5. The epoxy resin composition according to claim 1, wherein The specific surface area of the porous nanoparticles is 200±25 m2 / g, and the hydroxyl content in the porous nanoparticles is ≥3.0 mmol / g.

6. The epoxy resin composition according to claim 1, wherein Active groups are grafted onto the surface of the core-shell particles, and the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of the active groups on the surface of the core-shell particles is ≥85%.

7. A method for preparing an epoxy resin composition, characterized in that: The preparation method is used to prepare the epoxy resin composition according to any one of claims 1 to 6, and the preparation method comprises: Stirring and mixing a bisphenol A epoxy resin and a tetrafunctional epoxy resin under first preset conditions to obtain a resin mixture; dissolving a polyetherketone toughening agent in the resin mixture to obtain a toughened resin mixture; The core-shell particles, porous nanoparticles, latent curing agent and accelerator are dispersed in the toughening resin mixture to obtain the epoxy resin composition.

8. The method for preparing the epoxy resin composition according to claim 7, wherein The step of dissolving the polyetherketone toughening agent in the resin mixture to obtain the toughened resin mixture comprises: Adding the polyetherketone toughening agent to the resin mixture and pre-dispersing it at 80-100° C. for 1-2 hours to obtain a pre-dispersed mixture; The pre-dispersed mixture is dissolved at 150-160° C. for 0.5-1 hour to obtain the toughening resin mixture.

9. The method for preparing the epoxy resin composition according to claim 7, wherein: Before dispersing the core-shell particles in the toughening resin mixture, the preparation method further comprises: The core-shell particles are surface-treated with γ-glycidyloxypropyltrimethoxysilane so that active groups are grafted onto the surface of the core-shell particles, wherein the active groups include at least one of epoxy groups and siloxane groups; wherein the grafting rate of the active groups on the surface of the core-shell particles is ≥85%.

10. A composite material, characterized in that The composite material comprises the epoxy resin composition according to any one of claims 1 to 6, or the epoxy resin composition prepared by the preparation method of the epoxy resin composition according to any one of claims 7 to 9.

Images